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Sample records for influence spatial variability

  1. Variable spatial magnetic field influences peripheral nerves regeneration in rats.

    Science.gov (United States)

    Suszyński, Krzysztof; Marcol, Wiesław; Szajkowski, Sebastian; Pietrucha-Dutczak, Marita; Cieślar, Grzegorz; Sieroń, Aleksander; Lewin-Kowalik, Joanna

    2014-09-01

    Generator of spatial magnetic field is one of most recent achievements among the magnetostimulators. This apparatus allows to obtain the rotating magnetic field. This new method may be more effective than other widely used techniques of magnetostimulation and magnetotherapy. We investigated the influence of alternating, spatial magnetic field on the regeneration of the crushed rat sciatic nerves. Functional and morphological evaluations were used. After crush injury of the right sciatic nerve, Wistar C rats (n = 80) were randomly divided into four groups (control and three experimental). The experimental groups (A, B, C) were exposed (20 min/day, 5 d/week, 4 weeks) to alternating spatial magnetic field of three different intensities. Sciatic Functional Index (SFI) and tensometric assessments were performed every week after nerve crush. Forty-eight hours before the sacrificing of animals, DiI (1,1'-di-octadecyl-3,3,3',3'-tetramethyloindocarbocyanine perchlorate) was applied 5 mm distally to the crush site. Collected nerves and dorsal root ganglia (DRG) were subjected to histological and immunohistochemical staining. The survival rate of DRG neurons was estimated. Regrowth and myelination of the nerves was examined. The results of SFI and tensometric assessment showed improvement in all experimental groups as compared to control, with best outcome observed in group C, exposed to the strongest magnetic field. In addition, DRG survival rate and nerve regeneration intensity were significantly higher in the C group. Above results indicate that strong spatial alternating magnetic field exerts positive effect on peripheral nerve regeneration and its application could be taken under consideration in the therapy of injured peripheral nerves.

  2. [Factors influencing the spatial variability in soil respiration under different land use regimes].

    Science.gov (United States)

    Chen, Shu-Tao; Liu, Qiao-Hui; Hu, Zheng-Hua; Liu, Yan; Ren, Jing-Quan; Xie, Wei

    2013-03-01

    In order to investigate the factors influencing the spatial variability in soil respiration under different land use regimes, field experiments were performed. Soil respiration and relevant environment, vegetation and soil factors were measured. The spatial variability in soil respiration and the relationship between soil respiration and these measured factors were investigated. Results indicated that land use regimes had significant effects on soil respiration. Soil respiration varied significantly (P DBH) of trees can be explained by a natural logarithmic function. A model composed of soil organic carbon (C, %), available phosphorous (AP, g x kg(-1)) and diameter at breast height (DBH, cm) explained 92.8% spatial variability in soil respiration for forest ecosystems.

  3. Nitrogen and phosphorus concentrations from agricultural catchments—influence of spatial and temporal variables

    Science.gov (United States)

    Arheimer, B.; Lidén, R.

    2000-01-01

    The eutrophication problem has drawn attention to nutrient leaching from arable land in southern Sweden, and further understanding of spatial and temporal variability is needed in order to develop decision-making tools. Thus, the influence of spatial and temporal variables was analysed statistically using empirical time series of different nutrient species from 35 well-documented catchments (2-35 km 2), which have been monitored for an average of 5 years. In the spatial analysis several significant correlations between winter median concentrations and catchment characteristics were found. The strongest correlation was found between inorganic nitrogen and land use, while concentrations of different phosphorus species were highly correlated to soil texture. Multiple linear regression models gave satisfactory results for prediction of median winter concentrations in unmeasured catchments, especially for inorganic nitrogen and phosphate. In the analysis of temporal variability within catchments, internal variables from a dynamic hydrological model (HBV) were linked to concentration fluxes. It was found that phosphorus and inorganic nitrogen concentrations were elevated during flow increase at low-flow conditions, while they were diluted as the wetness in the catchment increased. During unmonitored periods regression models were successful in predicting temporal variability of total phosphorus, phosphate and inorganic nitrogen, while organic nitrogen and particulate phosphorus could not be predicted with this approach. Dividing the data into different flow categories did not improve the prediction of nutrient concentration dynamics. The results and literature review presented, confirm parts of the present HBV-N model approach and will be useful for further development of nutrient routines linked to dynamic hydrological models.

  4. Spatial patterns of North Atlantic Oscillation influence on mass balance variability of European glaciers

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    B. Marzeion

    2012-06-01

    Full Text Available We present and validate a set of minimal models of glacier mass balance variability. The most skillful model is then applied to reconstruct 7735 individual time series of mass balance variability for all glaciers in the European Alps and Scandinavia. Subsequently, we investigate the influence of atmospheric variability associated with the North Atlantic Oscillation (NAO on the glaciers' mass balances.

    We find a spatial coherence in the glaciers' sensitivity to NAO forcing which is caused by regionally similar mechanisms relating the NAO forcing to the mass balance: in southwestern Scandinavia, winter precipitation causes a correlation of mass balances with the NAO. In northern Scandinavia, temperature anomalies outside the core winter season cause an anti-correlation between NAO and mass balances. In the western Alps, both temperature and winter precipitation anomalies lead to a weak anti-correlation of mass balances with the NAO, while in the eastern Alps, the influences of winter precipitation and temperature anomalies tend to cancel each other, and only on the southern side a slight anti-correlation of mass balances with the NAO prevails.

  5. Influence of spatial and temporal variability of subsurface soil moisture and temperature on vapour intrusion

    Science.gov (United States)

    Bekele, Dawit N.; Naidu, Ravi; Chadalavada, Sreenivasulu

    2014-05-01

    A comprehensive field study was conducted at a site contaminated with chlorinated solvents, mainly trichloroethylene (TCE), to investigate the influence of subsurface soil moisture and temperature on vapour intrusion (VI) into built structures. Existing approaches to predict the risk of VI intrusion into buildings assume homogeneous or discrete layers in the vadose zone through which TCE migrates from an underlying source zone. In reality, the subsurface of the majority of contaminated sites will be subject to significant variations in moisture and temperature. Detailed site-specific data were measured contemporaneously to evaluate the impact of spatial and temporal variability of subsurface soil properties on VI exposure assessment. The results revealed that indoor air vapour concentrations would be affected by spatial and temporal variability of subsurface soil moisture and temperature. The monthly monitoring of soil-gas concentrations over a period of one year at a depth of 3 m across the study site demonstrated significant variation in TCE vapour concentrations, which ranged from 480 to 629,308 μg/m3. Soil-gas wells at 1 m depth exhibited high seasonal variability in TCE vapour concentrations with a coefficient of variation 1.02 in comparison with values of 0.88 and 0.74 in 2 m and 3 m wells, respectively. Contour plots of the soil-gas TCE plume during wet and dry seasons showed that the plume moved across the site, hence locations of soil-gas monitoring wells for human risk assessment is a site specific decision. Subsurface soil-gas vapour plume characterisation at the study site demonstrates that assessment for VI is greatly influenced by subsurface soil properties such as temperature and moisture that fluctuate with the seasons of the year.

  6. Spatial variability of the Rotterdam urban heat island as influenced by urban land use

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    Heusinkveld, Bert G.; Steeneveld, G. J.; Hove, L. W. A.; Jacobs, C. M. J.; Holtslag, A. A. M.

    2014-01-01

    Novel bicycle traverse meteorological measurements were made in Rotterdam to assess the spatial variation of temperature during a tropical day. Nocturnal spatial urban temperature differences of 7 K were found to be related to city morphology. During midday measurements, the downtown was up to 1.2 K warmer than the surrounding rural area while a city park was 4.0 K cooler than downtown. A regression analysis showed that the nocturnal measured urban heat island (UHI) can be linked to land use, namely vegetation, built-up area, and water and is most significant for vegetation. From the traverse observation data, a multiple linear regression model was constructed and independently validated with 3 year summertime UHI statistics derived from four urban fixed meteorological stations and two fixed rural stations. Wind rose analysis shows that UHI is strongest from easterly directions and that the temperature signal of the WMO station is influenced from urban directions. A regression model reproduced the nighttime spatial variability of the UHI within a fractional bias of 4.3% and was used to derive an UHI map of Rotterdam and surroundings. This map shows that high-density urban configurations lacking greenery or close to large water bodies are vulnerable to high nocturnal temperatures during heat waves. The UHI map can be used as a valuable planning tool for mitigating nocturnal urban heat stress or identifying neighborhoods at risk during heat waves.

  7. Abiotic factors influencing the spatial and temporal variability of juvenile fish in Pamlico Sound, North Carolina

    Energy Technology Data Exchange (ETDEWEB)

    Pietrafesa, L.J.; Janowitz, G.S.; Miller, J.M.; Noble, E.B.; Ross, S.W.; Epperly, S.P.

    1985-07-01

    A 3-D, time dependent model of the circulation in Pamlico Sound, NC, is used to relate the direction and magnitude of winds to the number of juvenile fish sampled at specified estuarine nursery locations. NC marine sport fishes are known to be spawned in NC continental waters, and then make transit to an through barrier island inlets, into Pamlico Sound. The juveniles then move 40-70 kilometers across the Sound to the nurseries. It is hypothesized that wind driven, pressure gradient induced and topographically steered currents, all abiotic factors, provide the transport mechanisms, during the recruitment period February-April, necessary for the transect. Moreover, the inherent variability in the atmospherically derived physical factors and the influence of topographic irregularities such as a large shoal which laterally bisects the Sound and bifurcates the bottom currents are seen as sources of the temporal and spatial variation observed in the distribution of juvenile fish, while the influence of biological processes is viewed as providing fine-tuned structuring.

  8. Stochastic analyses of field-scale pesticide leaching risk as influenced by spatial variability in physical and biochemical parameters

    Science.gov (United States)

    Loll, Per; Moldrup, Per

    2000-04-01

    Field-scale pesticide leaching risk assessments were performed by incorporating a numerical, one-dimensional, water and pesticide transport and fate model into the two-step stochastic modeling approach by Loll and Moldrup [1998]. The numerical model included first-order pesticide degradation, linear equilibrium adsorption, and plant uptake of water and pesticide. Simazine was used as a model pesticide, and leaching risk was expressed as the cumulative mass fraction of applied pesticide leached below 100 cm after 1 year. Spatial variability in soil physical and biochemical data, as well as measured meteorological data from an average and a relatively wet year, was considered for two Danish field sites: (1) a coarse sandy soil, with relatively small variability in hydraulic properties, and (2) a sandy loam, with large variability in hydraulic properties. The two-step stochastic modeling approach was used to investigate the relative impact of spatial variability in saturated hydraulic conductivity Ks, soil-water retention through the Campbell [974] soil-water retention parameter b, and pesticide sorption through the organic carbon content (OC). For the coarse sandy soil, field-scale spatial variability in OC was the single most important parameter influencing leaching risk, whereas for the sandy loam, Ks was found more important than OC. The relative impact of field-scale spatial variability in these parameters was found independent of the meteorological conditions, whereas the absolute level of leaching risk was highly dependent on the meteorological conditions. Assuming a linear dependency between pesticide half-life and OC, a unified approach to modeling simultaneous field-scale variability in biodegradation and adsorption was proposed. Leaching risk assessments based on this approach showed that the parts of the field with both low biological activity and low adsorption capacity contributed with a dramatic increase in leaching risk, and suggested that field

  9. Influence of deterministic geologic trends on spatial variability of hydrologic properties in volcanic tuff

    Energy Technology Data Exchange (ETDEWEB)

    Rautman, C.A. [Sandia National Labs., Albuquerque, NM (United States); Flint, A.L. [Geological Survey, Mercury, NV (United States); Chornack, M.P. [Geological Survey, Denver, CO (United States); Istok, J.D. [Oregon State Univ., Corvallis, OR (United States). Dept. of Civil Engineering; Fling, L.E. [Raytheon Services Nevada, Mercury, NV (United States)

    1992-12-31

    Hydrologic properties have been measured on outcrop samples taken from a detailed, two-dimension grid covering a 1.4 km outcrop exposure of the 10-m thick non-welded-to-welded, shardy base microstratigraphic unit of the Tiva Canyon Member of the Miocene Paintbrush Tuff at Yucca Mountain, Nevada. These data allow quantification of spatial trends in rock matrix properties that exist in this important hydrologic unit. Geologic investigation, combined with statistical and geostatistical analyses of the numerical data, indicates that spatial variability of matrix properties is related to deterministic geologic processes that operated throughout the region. Linear vertical trends in hydrologic properties are strongly developed in the shardy base microstratigraphic unit, and they are more accurately modeled using the concept of a thickness-normalized stratigraphic elevation within the unit, rather than absolute elevation. Hydrologic properties appear to be correlated over distances of 0.25 to 0.3 of the unit thickness after removing the deterministic vertical trend. The use of stratigraphic elevation allows scaling of identified trends by unit thickness which may be of particular importance in a basal, topography-blanketing unit such as this one. Horizontal changes in hydrologic properties do not appear to form obvious trends within the limited lateral geographic extent of the ash-flow environment that was examined. Matrix properties appear to be correlated horizontally over distances between 100 and 400 m. The existence and quantitative description of these trends and patterns of vertical spatial continuity should increase confidence in models of hydrologic properties and groundwater flow in this area that may be constructed to support the design of a potential high-level nuclear waste repository at Yucca Mountain.

  10. Spatial variability of the Rotterdam urban heat island as influenced by urban land use

    NARCIS (Netherlands)

    Heusinkveld, B.G.; Steeneveld, G.J.; Hove, van L.W.A.; Jacobs, C.M.J.; Holtslag, A.A.M.

    2014-01-01

    Novel bicycle traverse meteorological measurements were made in Rotterdam to assess the spatial variation of temperature during a tropical day. Nocturnal spatial urban temperature differences of 7¿K were found to be related to city morphology. The coolest residential areas were green low-density urb

  11. Factors Influencing Spatial Variability in Nitrogen Processing in Nitrogen-Saturated Soils

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    Frank S. Gilliam

    2001-01-01

    Full Text Available Nitrogen (N saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF, West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and nitrification in N-saturated soils from FEF, and how these effects varied between high N-processing vs. low N-processing soils collected from two watersheds, WS3 (fertilized with [NH4]2SO4 and WS4 (untreated control. Samples of forest floor material (O1 horizon and mineral soil (to a 5-cm depth were taken from three subplots within each of four plots that represented the extremes of highest and lowest rates of net N mineralization and nitrification (hereafter, high N and low N, respectively of untreated WS4 and N-treated WS3: control/low N, control/high N, N-treated/low N, N-treated/high N. Forest floor material was analyzed for carbon (C, lignin, and N. Subsamples of mineral soil were extracted immediately with 1 N KCl and analyzed for NH4+ and NO3- to determine preincubation levels. Extracts were also analyzed for Mg, Ca, Al, and pH. To test the hypothesis that the lack of net nitrification observed in field incubations on the untreated/low N plot was the result of absence of nitrifier populations, we characterized the bacterial community involved in N cycling by amplification of amoA genes. Remaining soil was incubated for 28 d at three temperatures (10, 20, and 30°C, followed by 1 NKCl extraction and analysis for NH4+ and NO3-. Net nitrification was essentially 100% of net N mineralization for all samples combined. Nitrification rates from lab incubations at all temperatures supported earlier observations based on field incubations. At 30°C, rates from N-treated/high N were three times those of N-treated/low N. Highest rates were found for untreated/high N (two times greater than those of

  12. Influence of management of variables, sampling zones and land units on LR analysis for landslide spatial prevision

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    R. Greco

    2013-09-01

    Full Text Available Several authors, according to different methodological approaches, have employed logistic Regression (LR, a multivariate statistical analysis adopted to assess the spatial probability of landslide, even though its fundamental principles have remained unaltered. This study aims at assessing the influence of some of these methodological approaches on the performance of LR, through a series of sensitivity analyses developed over a test area of about 300 km2 in Calabria (southern Italy. In particular, four types of sampling (1 – the whole study area; 2 – transects running parallel to the general slope direction of the study area with a total surface of about 1/3 of the whole study area; 3 – buffers surrounding the phenomena with a 1/1 ratio between the stable and the unstable area; 4 – buffers surrounding the phenomena with a 1/2 ratio between the stable and the unstable area, two variable coding modes (1 – grouped variables; 2 – binary variables, and two types of elementary land (1 – cells units; 2 – slope units units have been tested. The obtained results must be considered as statistically relevant in all cases (Aroc values > 70%, thus confirming the soundness of the LR analysis which maintains high predictive capacities notwithstanding the features of input data. As for the area under investigation, the best performing methodological choices are the following: (i transects produced the best results (0 P(y ≤ 93.4%; Aroc = 79.5%; (ii as for sampling modalities, binary variables (0 P(y ≤ 98.3%; Aroc = 80.7% provide better performance than ordinated variables; (iii as for the choice of elementary land units, slope units (0 P(y ≤ 100%; Aroc = 84.2% have obtained better results than cells matrix.

  13. Influence of land use and land cover on the spatial variability of dissolved organic matter in multiple aquatic environments.

    Science.gov (United States)

    Singh, Shatrughan; Dash, Padmanava; Silwal, Saurav; Feng, Gary; Adeli, Ardeshir; Moorhead, Robert J

    2017-06-01

    Water quality of lakes, estuaries, and coastal areas serves as an indicator of the overall health of aquatic ecosystems as well as the health of the terrestrial ecosystem that drains to the water body. Land use and land cover plays not only a significant role in controlling the quantity of the exported dissolved organic matter (DOM) but also influences the quality of DOM via various biogeochemical and biodegradation processes. We examined the characteristics and spatial distribution of DOM in five major lakes, in an estuary, and in the coastal waters of the Mississippi, USA, and investigated the influence of the land use and land cover of their watersheds on the DOM composition. We employed absorption and fluorescence spectroscopy including excitation-emission matrix (EEM) combined with parallel factor (PARAFAC) analysis modeling techniques to determine optical properties of DOM and its characteristics in this study. We developed a site-specific PARAFAC model to evaluate DOM characteristics resulting in five diverse DOM compositions that included two terrestrial humic-like (C1 and C3), two microbial humic-like (C2 and C5), and one protein-like (C4) DOM. Our results showed elevated fluorescence levels of microbial humic-like or protein-like DOM in the lakes and coastal waters, while the estuarine waters showed relatively high fluorescence levels of terrestrial humic-like DOM. The results also showed that percent forest and wetland coverage explained 68 and 82% variability, respectively, in terrestrial humic-like DOM exports, while 87% variability in microbially derived humiclike DOM was explained by percent agricultural lands. Strong correlations between microbial humic-like DOM and fluorescence-derived DOM indices such as biological index (BIX) and fluorescence index (FI) indicated autochthonous characteristics in the lakes, while the estuary showed largely allochthonous DOM of terrestrial origin. We also observed higher concentrations of total dissolved

  14. Influence of estuarine dynamics on macrobenthos spatial variability along the southeast continental shelf of Brazil

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    Ilana R. Zalmon

    2015-09-01

    Full Text Available Along the southeast continental shelf of Brazil, the Paraíba do Sul River (PSR plays a fundamental role in sediment and nutrient transport. This study focuses on the contribution of the PSR and its effect on the benthic macrofauna. Physical and chemical analyses of the sediment were conducted, and the macrofauna were identified and counted. Multivariate analyses were used to compare the distribution patterns of the benthic assemblages related to the depth gradient over two sampling periods. The principal component analysis showed that shallow waters assemblages are mostly influenced by the environmental descriptors temperature, salinity and chlorophyll a, whereas pheophytin, degree of sediment sorting, total carbonate and organic carbon were correlated with benthic assemblages at greater depths. The high organic enrichment reflected an increase in surface and sub-surface deposit feeders such as the polychaetes Spiophanes sp. and Prionospio cristata and the crustacean Phtisica marinain the deeper stations, with a corresponding decrease in other trophic groups. This study provides evidence of differences in organic matter sources, from primary production in shallow waters to detritus in deep waters. These sources provide different niches for the corresponding macrofaunal assemblages along the continental shelf adjacent to the PSR, with species richness and abundance of benthic populations related to the river output.

  15. The influence of spatial and seasonal variability on the stability of the sea ice cover

    Science.gov (United States)

    Wagner, T. J. W.; Eisenman, I.

    2014-12-01

    Reports of ever new record lows of Arctic sea ice extent are making headlines almost continually in recent years. The change in albedo when sea ice is replaced by open water introduces an important nonlinearity to the system. It is this nonlinearity that has sparked an ongoing debate regarding the stability of the Arctic ice cover and the possibility of an Arctic `tipping point'. In previous studies, instabilities for a shrinking ice cover linked to the ice-albedo feedback have been identified in two different types of idealized models: (i) annual-mean diffusive energy balance models (EBMs) and (ii) seasonally-varying single-column models (SCMs). The incidence of instabilities in these low-order models stands in contrast with results from comprehensive climate models which have been found not to simulate any such instability. In the present study we investigate the stability of the sea ice cover from a theoretical perspective, developing a model that includes both seasonal and latitudinal variability. The model reduces to a standard EBM or SCM as limiting cases in the parameter regime, thus reconciling the two previous lines of research. The simple formulation of this model allows us to investigate the key physical processes that govern the stability of the system. Our results show that the stability of the ice cover vastly increases with the inclusion of additional degrees of freedom associated with a seasonal cycle or horizontal heat transport. The results suggest that the sea ice cover is substantially more stable than has been suggested by previous idealized modeling studies.

  16. Influence of the spatial variability of rainfall on hydrograph modelling at catchment outlet: a case study in the Cevennes region, France

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    Emmanuel Isabelle

    2016-01-01

    Full Text Available The influence of rainfall spatial variability on hydrographs modelling at catchment outlet remains an open scientific debate. [1] have proposed rainfall variability indexes aiming at summarising the influence of rainfall spatial organisation on hydrographs features. This preliminary work was based on a large simulated database. The present article shows how the proposed indexes may be used in a real case study to discriminate rainfall events for which information on spatial rainfall organization is crucial for hydrograph modelling, and therefore to better illustrate the added value of high resolution rainfall information as input of hydrological models. The presented case study is located in the Cevennes Region in south-eastern France. The tested flow events are split into two subsets according to the values of the rainfall variability indexes. The comparison between modelled and measured hydrographs is then performed separately for each subset. The results obtained suggest that, on average, modelling results taking into account high resolution rainfall data are significantly improved for the subset for which the influence of rainfall variability is expected to be significant according to the indexes values. Although limited to a relatively small number of hydrographs, this case study can be viewed as a first confirmation of the pertinence of the rainfall variability indexes proposed in [1] to investigate the influence of rainfall spatial variability on the shape of hydrographs at catchment outlet.

  17. Spatial Variability of Rainfall

    DEFF Research Database (Denmark)

    Jensen, N.E.; Pedersen, Lisbeth

    2005-01-01

    As a part of a Local Area Weather Radar (LAWR) calibration exercise 15 km south of Århus, Denmark, the variability in accumulated rainfall within a single radar pixel (500 by 500 m) was measured using nine high-resolution rain gauges. The measured values indicate up to a 100% variation between...

  18. Variability of mesozooplankton spatial distribution in the North Aegean Sea, as influenced by the Black Sea waters outflow

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    Siokou-Frangou, Ioanna; Zervoudaki, Soultana; Christou, Epaminondas D.; Zervakis, Vassilis; Georgopoulos, Dimitrios

    2009-11-01

    spreading and mixing of the Black sea water. The observed temporal and spatial variability in the distribution pattern of mesozooplankton standing stock and species composition seems to depend considerably on the variability of circulation and frontal flows.

  19. The influence of riparian woodland on the spatial and temporal variability of stream water temperatures in an upland salmon stream

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    I. A. Malcolm

    2004-01-01

    Full Text Available The spatio-temporal variability of stream water temperatures was investigated at six locations on the Girnock Burn (30km2 catchment, Cairngorms, Scotland over three hydrological years between 1998 and 2002. The key site-specific factors affecting the hydrology and climatology of the sampling points were investigated as a basis for physical process inference. Particular emphasis was placed on assessing the effects of riparian forest in the lower catchment versus the heather moorland riparian zones that are spatially dominant in the upper catchment. The findings were related to river heat budget studies that provided process detail. Gross changes in stream temperature were affected by the annual cycle of incoming solar radiation and seasonal changes in hydrological and climatological conditions. Inter-annual variation in these controlling variables resulted in inter-annual variability in thermal regime. However, more subtle inter-site differences reflected the impact of site-specific characteristics on various components of the river energy budget. Inter-site variability was most apparent at shorter time scales, during the summer months and for higher stream temperatures. Riparian woodland in the lower catchment had a substantial impact on thermal regime, reducing diel variability (over a period of 24 hours and temperature extremes. Observed inter-site differences are likely to have a substantial effect on freshwater ecology in general and salmonid fish in particular. Keywords: temperature, thermal regime, forest, salmon, hydrology, Girnock Burn, Cairngorm

  20. Satellite-measured interannual variability of turbid river plumes off central-southern Chile: Spatial patterns and the influence of climate variability

    Science.gov (United States)

    Saldías, Gonzalo S.; Largier, John L.; Mendes, Renato; Pérez-Santos, Iván; Vargas, Cristian A.; Sobarzo, Marcus

    2016-08-01

    Ocean color imagery from MODIS (Moderate Resolution Imaging Spectroradiometer) onboard the Aqua platform is used to characterize the interannual variability of turbid river plumes off central-southern Chile. Emphasis is placed on the influence of climate fluctuations, namely El Niño Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the Antarctic Oscillation (AAO). Additional satellite data on wind, boat-based hydrographic profiles, and regional climate indices are used to identify the influence of climate variability on the generation of anomalous turbid river plumes. The evolution of salinity at a coastal station on the 90 m isobath between the Itata and Biobío Rivers shows a freshwater surface layer with salinity importance of long-term and high-resolution ocean color observations for studying the temporal evolution of river plumes.

  1. Factorial kriging and stepwise regression approach to identify environmental factors influencing spatial multi-scale variability of heavy metals in soils.

    Science.gov (United States)

    Lv, Jianshu; Liu, Yang; Zhang, Zulu; Dai, Jierui

    2013-10-15

    The knowledge about spatial variations of heavy metals in soils and their relationships with environmental factors is important for human impact assessment and soil management. Surface soils from Rizhao city, Eastern China with rapid urbanization and industrialization were analyzed for six key heavy metals and characterized by parent material and land use using GIS-based data. Factorial kriging analysis and stepwise multiple regression were applied to examine the scale-dependent relationships among heavy metals and to identify environmental factors affecting spatial variability at each spatial scale. Linear model of coregionalization fitting showed that spatial multi-scale variation of heavy metals in soils consisted of nugget effect, an exponential structure with the range of 12 km (short-range scale), as well as a spherical structure with the range of 36 km (long-range scale). The short-range variation of Cd, Pb and Zn were controlled by land use, with higher values in urban areas as well as cultivated land in mountain area, and were related to human influence; while parent material dominated the long structure variations of these elements. Spatial variations of Cr and Ni were associated with natural geochemical sources at short- and long-range scales. At both two scales, Hg dominated by land use, corresponded well to spatial distributions of urban areas, and was attributed to anthropic emissions and atmosphere deposition.

  2. The influence of circulation weather patterns at different spatial scales on drought variability in the Iberian Peninsula

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    Ana Cristina Russo

    2015-02-01

    Full Text Available Europe has suffered several extreme weather events which were responsible for considerable ecological and economic losses in the last few decades. In Southern Europe, droughts are one of the most frequent extreme weather events, causing severe damages and various fatalities.The main goal of this study is to determine the role of Circulation Weather Types (CWT on spatial and temporal variability of droughts by means the new multi-scalar Standardized Precipitation Evapotranspiration Index (SPEI. This study aims also to identify the main CWTs associated with winter and summer droughts over different regions of Iberian Peninsula.During the period between 1950 and 2012, the most frequent CWTs were found to be the Anticyclonic (A, Cyclonic (C, North (N and Northeast (NE types. The trend analysis for winter season shows a clear increase of frequency CWTs associated to dry events (A, East and Southeast and a decrease of frequency of C and northern types while in summer a clear decrease of NE is observed.The spatial patterns of correlation between SPEI and CWT show large patterns of negative correlations with winter frequencies of A and eastern weather types, while the reverse occurs with C and western types. This feature is highlighted on a regional approach. The NE type presents negative correlations Central, Northwestern and Southwestern regions during winter and positive correlations in Eastern region during summer. In opposition, the West type presents positive correlations in all regions (except Eastern region during winter and does not present significant correlations during summer. In general, the predominant CWT associated to winter or summer drought conditions differs greatly between regions. The winter droughts are associated mainly with high frequency of E types and low frequency of W types for all areas, while the summer drought in eastern sectors are linked with low frequency of C type, as well as the western regions are related with the N

  3. Temporal and spatial patterns of wetland extent influence variability of surface water connectivity in the Prairie Pothole Region, United States

    Science.gov (United States)

    Vanderhoof, Melanie; Alexander, Laurie C.; Todd, Jason

    2016-01-01

    Context. Quantifying variability in landscape-scale surface water connectivity can help improve our understanding of the multiple effects of wetlands on downstream waterways. Objectives. We examined how wetland merging and the coalescence of wetlands with streams varied both spatially (among ecoregions) and interannually (from drought to deluge) across parts of the Prairie Pothole Region. Methods. Wetland extent was derived over a time series (1990-2011) using Landsat imagery. Changes in landscape-scale connectivity, generated by the physical coalescence of wetlands with other surface water features, were quantified by fusing static wetland and stream datasets with Landsat-derived wetland extent maps, and related to multiple wetness indices. The usage of Landsat allows for decadal-scale analysis, but limits the types of surface water connections that can be detected. Results. Wetland extent correlated positively with the merging of wetlands and wetlands with streams. Wetness conditions, as defined by drought indices and runoff, were positively correlated with wetland extent, but less consistently correlated with measures of surface water connectivity. The degree of wetland-wetland merging was found to depend less on total wetland area or density, and more on climate conditions, as well as the threshold for how wetland/upland was defined. In contrast, the merging of wetlands with streams was positively correlated with stream density, and inversely related to wetland density. Conclusions. Characterizing the degree of surface water connectivity within the Prairie Pothole Region in North America requires consideration of 1) climate-driven variation in wetness conditions and 2) within-region variation in wetland and stream spatial arrangements.

  4. Spatial variability of primary organic sources regulates ichthyofauna distribution despite seasonal influence in Terminos lagoon and continental shelf of Campeche, Mexico

    Science.gov (United States)

    Romo Rios, J. A.; Aguíñiga-García, S.; Sanchez, A.; Zetina-Rejón, M.; Arreguín-Sánchez, F.; Tripp-Valdéz, A.; Galeana-Cortazár, A.

    2013-05-01

    Human activities have strong impacts on coastal ecosystems functioning through their effect on primary organic sources distributions and resulting biodiversity. Hence, it appears to be of utmost importance to quantify contribution of primary producers to sediment organic matter (SOM) spatial variability and its associated ichthyofauna. The Terminos lagoon (Gulf of Mexico) is a tropical estuary severely impacted by human activities even though of primary concern for its biodiversity, its habitats, and its resource supply. Stable isotope data (d13C, d15N) from mangrove, seaweed, seagrass, phytoplankton, ichthyofauna and SOM were sampled in four zones of the lagoon and the continental shelf through windy (November to February), dry (March to June) and rainy (July to October) seasons. Stable Isotope Analysis in R (SIAR) mixing model were used to determine relative contributions of the autotrophic sources to the ichthyofauna and SOM. Analysis of variance of ichthyofauna isotopic values showed significant differences (P < 0.001) in the four zones of lagoon despite the variability introduced by the windy, dry and rainy seasons. In lagoons rivers discharge zone, the mangrove contribution to ichthyofauna was 40% and 84% to SOM. Alternative use of habitat by ichthyofauna was evidenced since in the deep area of the lagoon (4 m), the contribution of mangrove to fish is 50%, and meanwhile contribution to SOM is only 77%. Although phytoplankton (43%) and seaweed (41%) contributions to the adjacent continental shelf ichthyofauna were the main organic sources, there was 37% mangrove contribution to SOM, demonstrating conspicuous terrigenous influence from lagoon ecosystem. Our results point toward organic sources spatial variations that regulate fish distribution. In Terminos lagoon, significant correlation (p-value = 0.2141 and r=0.79) of Ariopsis felis and Sphoeroides testudineus abundances and seaweed and seagrasses contributions (30-35%) during both dry and rainy seasons

  5. Spatially-Resolved Influence of Temperature and Salinity on Stock and Recruitment Variability of Commercially Important Fishes in the North Sea.

    Science.gov (United States)

    Akimova, Anna; Núñez-Riboni, Ismael; Kempf, Alexander; Taylor, Marc H

    2016-01-01

    Understanding of the processes affecting recruitment of commercially important fish species is one of the major challenges in fisheries science. Towards this aim, we investigated the relation between North Sea hydrography (temperature and salinity) and fish stock variables (recruitment, spawning stock biomass and pre-recruitment survival index) for 9 commercially important fishes using spatially-resolved cross-correlation analysis. We used high-resolution (0.2° × 0.2°) hydrographic data fields matching the maximal temporal extent of the fish population assessments (1948-2013). Our approach allowed for the identification of regions in the North Sea where environmental variables seem to be more influential on the fish stocks, as well as the regions of a lesser or nil influence. Our results confirmed previously demonstrated negative correlations between temperature and recruitment of cod and plaice and identified regions of the strongest correlations (German Bight for plaice and north-western North Sea for cod). We also revealed a positive correlation between herring spawning stock biomass and temperature in the Orkney-Shetland area, as well as a negative correlation between sole pre-recruitment survival index and temperature in the German Bight. A strong positive correlation between sprat stock variables and salinity in the central North Sea was also found. To our knowledge the results concerning correlations between North Sea hydrography and stocks' dynamics of herring, sole and sprat are novel. The new information about spatial distribution of the correlation provides an additional help to identify mechanisms underlying these correlations. As an illustration of the utility of these results for fishery management, an example is provided that incorporates the identified environmental covariates in stock-recruitment models.

  6. Spatial Heterogeneity of Soil Moisture and the Scale Variability of Its Influencing Factors: A Case Study in the Loess Plateau of China

    Directory of Open Access Journals (Sweden)

    Mingyue Zhao

    2013-08-01

    mosaic patterns. For example, low-density woodland or wild grassland would be appropriate for sites with low soil moisture content, such as upper slope, high elevation and steep slope sites. A stepwise regression analysis indicated that the dominant factor controlling the spatial variability of soil moisture values varied at different scales. At the small watershed scale, the order of significance for the influence of environmental factors on soil moisture values was as follows: land use type, slope, relative elevation and vegetation cover. The order of significance at the watershed scale was also determined: location on the hill slope, vegetation cover, slope, relative elevation and sine of the aspect. This result indicated that the influence of different environmental factors on soil moisture variability was dependent on the scale. The forecasting capability of regression models for soil moisture decreases from the small watershed scale to the watershed scale. This study could provide a reference for relevant scale transformation studies and offer guidance for water resource management and vegetation restoration approaches on the Loess Plateau.

  7. Spatial variability of throughfall in a stand of Scots pine (Pinus sylvestris L.) with deciduous admixture as influenced by canopy cover and stem distance

    Science.gov (United States)

    Kowalska, Anna; Boczoń, Andrzej; Hildebrand, Robert; Polkowska, Żaneta

    2016-07-01

    Vegetation cover affects the amount of precipitation, its chemical composition and its spatial distribution, and this may have implications for the distribution of water, nutrients and contaminants in the subsurface soil layer. The aim of this study was a detailed diagnosis of the spatio-temporal variability in the amount of throughfall (TF) and its chemical components in a 72-year-old pine stand with an admixture of oak and birch. The spatio-temporal variability in the amount of TF water and the concentrations and deposition of the TF components were studied. The components that are exchanged in canopy (H+, K, Mg, Mn, DOC, NH4+) were more variable than the components whose TF deposition is the sum of wet and dry (including gas) deposition and which undergo little exchange in the canopy (Na, Cl, NO3-, SO42-). The spatial distribution was temporally stable, especially during the leafed period. This study also investigated the effect of the selected pine stand characteristics on the spatial distribution of throughfall and its chemical components; the characteristics included leaf area index (LAI), the proportion of the canopy covered by deciduous species and pine crowns, and the distance from the nearest tree trunk. The LAI measured during the leafed and leafless periods had the greatest effect on the spatial distribution of TF deposition. No relationship was found between the spatial distribution of the amount of TF water and (i) the LAI; (ii) the canopy cover of broadleaf species or pines; or (iii) the distance from the trunks.

  8. Variables influencing cardiovascular function.

    Science.gov (United States)

    Fitzsimmons, L; Shively, M; Verderber, A

    1991-07-01

    Two studies are reviewed, one regarding the effects of music therapy on psychophysiologic stress in coronary care unit patients and one regarding the effects of age and gender on cardiovascular autonomic reactivity in healthy adults. Music therapy is determined to be safe for coronary care unit patients and effective in modulating the psychophysiologic manifestations of stress. The second study suggests that age--gender interactions may influence autonomic cardiovascular responsiveness. It is suggested that older adults be taught methods to reduce straining, so that rapid transient changes in blood pressure are avoided.

  9. Spatial Variability of Soil Morphorlogical and Physico-Chemical ...

    African Journals Online (AJOL)

    Spatial Variability of Soil Morphorlogical and Physico-Chemical Properties in ... the spatial variability of soil morphological, physical and chemical properties in the ... organic matter (g/kg), and available phosphorus were extremely variable soil ...

  10. The influence of watershed characteristics on spatial patterns of trends in annual scale streamflow variability in the continental U.S.

    Science.gov (United States)

    Rice, Joshua S.; Emanuel, Ryan E.; Vose, James M.

    2016-09-01

    As human activity and climate variability alter the movement of water through the environment the need to better understand hydrologic cycle responses to these changes has grown. A reasonable starting point for gaining such insight is studying changes in streamflow given the importance of streamflow as a source of renewable freshwater. Using a wavelet assisted method we analyzed trends in the magnitude of annual scale streamflow variability from 967 watersheds in the continental U.S. (CONUS) over a 70 year period (1940-2009). Decreased annual variability was the dominant pattern at the CONUS scale. Ecoregion scale results agreed with the CONUS pattern with the exception of two ecoregions closely divided between increases and decreases and one where increases dominated. A comparison of trends in reference and non-reference watersheds indicated that trend magnitudes in non-reference watersheds were significantly larger than those in reference watersheds. Boosted regression tree (BRT) models were used to study the relationship between watershed characteristics and the magnitude of trends in streamflow. At the CONUS scale, the balance between precipitation and evaporative demand, and measures of geographic location were of high relative importance. Relationships between the magnitude of trends and watershed characteristics at the ecoregion scale exhibited differences from the CONUS results and substantial variability was observed among ecoregions. Additionally, the methodology used here has the potential to serve as a robust framework for top-down, data driven analyses of the relationships between changes in the hydrologic cycle and the spatial context within which those changes occur.

  11. Spatial ascariasis risk estimation using socioeconomic variables.

    Science.gov (United States)

    Valencia, Luis Iván Ortiz; Fortes, Bruno de Paula Menezes Drumond; Medronho, Roberto de Andrade

    2005-12-01

    Frequently, disease incidence is mapped as area data, for example, census tracts, districts or states. Spatial disease incidence can be highly heterogeneous inside these areas. Ascariasis is a highly prevalent disease, which is associated with poor sanitation and hygiene. Geostatistics was applied to model spatial distribution of Ascariasis risk and socioeconomic risk events in a poor community in Rio de Janeiro, Brazil. Data were gathered from a coproparasitologic and a domiciliary survey in 1550 children aged 1-9. Ascariasis risk and socioeconomic risk events were spatially estimated using Indicator Kriging. Cokriging models with a Linear Model of Coregionalization incorporating one socioeconomic variable were implemented. If a housewife attended school for less than four years, the non-use of a home water filter, a household density greater than one, and a household income lower than one Brazilian minimum wage increased the risk of Ascariasis. Cokriging improved spatial estimation of Ascariasis risk areas when compared to Indicator Kriging and detected more Ascariasis very-high risk areas than the GIS Overlay method.

  12. Influence of Spatial Features on Land and Housing Prices

    Institute of Scientific and Technical Information of China (English)

    GAO Xiaolu; ASAMI Yasushi

    2005-01-01

    The analysis of hidden spatial features is crucial for the improvement of hedonic regression models for analyzing the structure of land and housing prices. If critical variables representing the influence of spatial features are omitted in the models, the residuals and the coefficients estimated usually exhibit some kind of spatial pattern. Hence, exploration of the relationship between the spatial patterns and the spatial features essentially leads to the discovery of omitted variables. The analyses in this paper were based on two exploratory approaches: one on the residual of a global regression model and the other on the geographically weighted regression (GWR) technique. In the GWR model, the regression coefficients are allowed to differ by location so more spatial patterns can be revealed. Comparison of the two approaches shows that they play supplementary roles for the detection of lot-associated variables and area-associated variables.

  13. SPATIAL VARIABILITY OF PEDOZEMS MECHANICAL IMPEDANCE

    Directory of Open Access Journals (Sweden)

    Zhukov A.V.

    2013-04-01

    Full Text Available We studied the spatial variability of pedozem mechanical impedance in ResearchRemediation Center of the Dnipropetrovsk State Agrarian University in Ordzhonikidze. Thestatistical distribution of the soil mechanical impedance within the studied area is characterized by deviation from the normal law in 0–10 and 30–50 cm layers from the surface. 2D and 3D modeling shows the structural design of the soil as locations of high mechanical impedance which found in the soils with less hardness.

  14. How does spatial variability of climate affect catchment streamflow predictions?

    Science.gov (United States)

    Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distribute...

  15. Spatially Resolved Images and Solar Irradiance Variability

    Indian Academy of Sciences (India)

    R. Kariyappa

    2008-03-01

    The Sun is the primary source of energy that governs both the terrestrial climate and near-earth space environment. Variations in UV irradiances seen at earth are the sum of global (solar dynamo) to regional (active region, plage, network, bright points and background) solar magnetic activities that can be identified through spatially resolved photospheric, chromospheric and coronal features. In this research, the images of CaII K-line (NSO/Sac Peak) have been analysed to segregate the various chromospheric features.We derived the different indices and estimated their contribution from the time series data to total CaII K emission flux and UV irradiance variability. A part of the important results from this research is discussed in this paper.

  16. Land use and soil organic matter in South Africa 1: A review on spatial variability and the influence of rangeland stock production

    Directory of Open Access Journals (Sweden)

    Pearson N.S. Mnkeni

    2011-05-01

    Full Text Available Degradation of soil as a consequence of land use poses a threat to sustainable agriculture in South Africa, resulting in the need for a soil protection strategy and policy. Development of such a strategy and policy require cognisance of the extent and impact of soil degradation processes. One of the identified processes is the decline of soil organic matter, which also plays a central role in soil health or quality. The spatial variability of organic matter and the impact of grazing and burning under rangeland stock production are addressed in this first part of the review. Data from uncoordinated studies showed that South African soils have low organic matter levels. About 58% of soils contain less than 0.5% organic carbon and only 4% contain more than 2% organic carbon. Furthermore, there are large differences in organic matter content within and between soil forms, depending on climatic conditions, vegetative cover, topographical position and soil texture. A countrywide baseline study to quantify organic matter contents within and between soil forms is suggested for future reference. Degradation of rangeland because of overgrazing has resulted in significant losses of soil organic matter, mainly as a result of lower biomass production. The use of fire in rangeland management decreases soil organic matter because litter is destroyed by burning. Maintaining or increasing organic matter levels in degraded rangeland soils by preventing overgrazing and restricting burning could contribute to the restoration of degraded rangelands. This restoration is of the utmost importance because stock farming uses the majority of land in South Africa.

  17. Sparse modeling of spatial environmental variables associated with asthma.

    Science.gov (United States)

    Chang, Timothy S; Gangnon, Ronald E; David Page, C; Buckingham, William R; Tandias, Aman; Cowan, Kelly J; Tomasallo, Carrie D; Arndt, Brian G; Hanrahan, Lawrence P; Guilbert, Theresa W

    2015-02-01

    Geographically distributed environmental factors influence the burden of diseases such as asthma. Our objective was to identify sparse environmental variables associated with asthma diagnosis gathered from a large electronic health record (EHR) dataset while controlling for spatial variation. An EHR dataset from the University of Wisconsin's Family Medicine, Internal Medicine and Pediatrics Departments was obtained for 199,220 patients aged 5-50years over a three-year period. Each patient's home address was geocoded to one of 3456 geographic census block groups. Over one thousand block group variables were obtained from a commercial database. We developed a Sparse Spatial Environmental Analysis (SASEA). Using this method, the environmental variables were first dimensionally reduced with sparse principal component analysis. Logistic thin plate regression spline modeling was then used to identify block group variables associated with asthma from sparse principal components. The addresses of patients from the EHR dataset were distributed throughout the majority of Wisconsin's geography. Logistic thin plate regression spline modeling captured spatial variation of asthma. Four sparse principal components identified via model selection consisted of food at home, dog ownership, household size, and disposable income variables. In rural areas, dog ownership and renter occupied housing units from significant sparse principal components were associated with asthma. Our main contribution is the incorporation of sparsity in spatial modeling. SASEA sequentially added sparse principal components to Logistic thin plate regression spline modeling. This method allowed association of geographically distributed environmental factors with asthma using EHR and environmental datasets. SASEA can be applied to other diseases with environmental risk factors.

  18. Understanding Mountain Range Spatial Variability of Surface Hoar

    Science.gov (United States)

    Hendrikx, J.

    2014-12-01

    Surface hoar, once buried often produce a persistent weak layer that is a common instability problem in the snow pack in SW Montana and many other areas around the world. Surface hoar is a common weak layer type in avalanche accidents in a continental and intermountain snowpack. It is however relatively well understood that aspect plays an important role in the spatial location of the growth, and survival of these grain forms, due to the unequal distribution of incoming radiation. However this factor alone does not explain the complex and often confusing spatial pattern of these grains forms throughout the landscape at larger, mountain range spatial scales. In this paper we present a unique data set including over one hundred days of manual observations of surface hoar at sixteen locations on Pioneer Mountain at the Yellowstone Club in southwestern Montana. Using this wealth of observational data located on different aspects, elevations and exposures, coupled with detailed meteorological observations, detailed site scale observations (e.g. Sky view plots) we examine the spatial variability of surface hoar at this scale, and examine the factors that control its spatial distribution. Our results further supports our preliminary work, which shows that small-scale meteorological differences, site scale differences, and local scale lapse rates can greatly influence the spatial variability of surface hoar, over and above that which aspect alone can explain. These results highlight our incomplete understanding of the processes at this large, mountain range scale, and are likely to have implications for both regional and local scale avalanche forecasting in environments where surface hoar cause ongoing instabilities.

  19. Mathematical Modeling of spatial disease variables by Spatial Fuzzy Logic for Spatial Decision Support Systems

    Science.gov (United States)

    Platz, M.; Rapp, J.; Groessler, M.; Niehaus, E.; Babu, A.; Soman, B.

    2014-11-01

    A Spatial Decision Support System (SDSS) provides support for decision makers and should not be viewed as replacing human intelligence with machines. Therefore it is reasonable that decision makers are able to use a feature to analyze the provided spatial decision support in detail to crosscheck the digital support of the SDSS with their own expertise. Spatial decision support is based on risk and resource maps in a Geographic Information System (GIS) with relevant layers e.g. environmental, health and socio-economic data. Spatial fuzzy logic allows the representation of spatial properties with a value of truth in the range between 0 and 1. Decision makers can refer to the visualization of the spatial truth of single risk variables of a disease. Spatial fuzzy logic rules that support the allocation of limited resources according to risk can be evaluated with measure theory on topological spaces, which allows to visualize the applicability of this rules as well in a map. Our paper is based on the concept of a spatial fuzzy logic on topological spaces that contributes to the development of an adaptive Early Warning And Response System (EWARS) providing decision support for the current or future spatial distribution of a disease. It supports the decision maker in testing interventions based on available resources and apply risk mitigation strategies and provide guidance tailored to the geo-location of the user via mobile devices. The software component of the system would be based on open source software and the software developed during this project will also be in the open source domain, so that an open community can build on the results and tailor further work to regional or international requirements and constraints. A freely available EWARS Spatial Fuzzy Logic Demo was developed wich enables a user to visualize risk and resource maps based on individual data in several data formats.

  20. On the spatial and temporal variability of ENSO precipitation and drought teleconnection in mainland Southeast Asia

    OpenAIRE

    T. A. Räsänen; Lindgren, V; Guillaume, J H A; Buckley, B.M.; Kummu, M.

    2015-01-01

    The variability in the hydroclimate over mainland Southeast Asia is strongly influenced by the El Niño–Southern Oscillation (ENSO) phenomenon, which has been linked to severe drought and floods that profoundly influence human societies and ecosystems alike. However, the spatial characteristics and long-term stationarity of ENSO's influence in the region are not well understood. We thus aim to analyse seasonal evolution and spatial variations in the effect of ENSO on precipit...

  1. 陆地生态系统土壤呼吸时空变异的影响因素研究进展%Review of the Factors Influencing the Temporal and Spatial Variability of Soil Respiration in Terrestrial Ecosystem

    Institute of Scientific and Technical Information of China (English)

    陈书涛; 胡正华; 张勇; 沈小帅; 史艳姝

    2011-01-01

    土壤呼吸是碳循环中的1个重要过程,土壤呼吸作用的过程及其影响因子对理解陆地碳循环极为关键.本文对迄今为止国内外关于土壤呼吸时空变异性影响因素的一些研究进行综述,分析了气候、植被、土壤因素对土壤呼吸变异性的影响规律.以往的研究表明,气候因素中对土壤呼吸具有重要影响的因子为气温和降水,植被因素中对土壤呼吸具有重要影响的因子为叶面积指数、凋落物质量、细根生物量,而土壤因素中的有机碳含量、质地对土壤呼吸具有影响.气候、植被、土壤因素对土壤呼吸的影响往往表现为综合作用.温度、降水一方面直接影响土壤中根系和微生物的呼%Soil respiration is an important process in carbon cycling.Understanding the processes and controlling factors of soil respiration are crucial in investigating the terrestrial carbon cycling.This article reviews the investigations about the factors controlling the temporal and spatial variability of soil respiration.The temporal and spatial variability in soil respiration is linked with climate,vegetation and soil factors.Air temperature and precipitation generally contribute great to the variability of soil respiration.Leaf area index(LAI),litter fall and fine root biomass are three plant-related factors that can be employed to explained the variability of soil respiration,while soil carbon content and texture are two soil factors responsible for the variability of soil respiration.Generally,climate,vegetation and soil factors contribute collectively to the temporal and spatial variability of terrestrial soil respiration.Temperature and precipitation,on the one hand,directly affect the root and microbial respiration rates.On the other hand,temperature and precipitation indirectly affect soil respiration by influencing the plant and microbial growth and soil conditions.In order to understand the controlling factors of the

  2. Climate variability effects on spatial soil moisture dynamics

    NARCIS (Netherlands)

    Teuling, A.J.; Hupet, F.; Uijlenhoet, R.; Troch, P.A.

    2007-01-01

    We investigate the role of interannual climate variability on spatial soil moisture variability dynamics for a field site in Louvain-la-Neuve, Belgium. Observations were made during 3 years under intermediate (1999), wet (2000), and extremely dry conditions (2003). Soil moisture variability dynamics

  3. Spatial Variability of Metals in Surface Water and Sediment in the Langat River and Geochemical Factors That Influence Their Water-Sediment Interactions

    Directory of Open Access Journals (Sweden)

    Wan Ying Lim

    2012-01-01

    Full Text Available This paper determines the controlling factors that influence the metals’ behavior water-sediment interaction facies and distribution of elemental content (75As, 111Cd, 59Co, 52Cr, 60Ni, and 208Pb in water and sediment samples in order to assess the metal pollution status in the Langat River. A total of 90 water and sediment samples were collected simultaneously in triplicate at 30 sampling stations. Selected metals were analyzed using ICP-MS, and the metals’ concentration varied among stations. Metal concentrations of water ranged between 0.08–24.71 μg/L for As, <0.01–0.53 μg/L for Cd, 0.06–6.22 μg/L for Co, 0.32–4.67 μg/L for Cr, 0.80–24.72 μg/L for Ni, and <0.005–6.99 μg/L for Pb. Meanwhile, for sediment, it ranged between 4.47–30.04 mg/kg for As, 0.02–0.18 mg/kg for Cd, 0.87–4.66 mg/kg for Co, 4.31–29.04 mg/kg for Cr, 2.33–8.25 mg/kg for Ni and 5.57–55.71 mg/kg for Pb. The average concentration of studied metals in the water was lower than the Malaysian National Standard for Drinking Water Quality proposed by the Ministry of Health. The average concentration for As in sediment was exceeding ISQG standards as proposed by the Canadian Sediment Quality Guidelines. Statistical analyses revealed that certain metals (As, Co, Ni, and Pb were generally influenced by pH and conductivity. These results are important when making crucial decisions in determining potential hazardous levels of these metals toward humans.

  4. Spatial distribution analysis on climatic variables in northeast China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Information ecology is a new research area of modern ecology.Here describes spatial distribution analysis methods of four sorts of climatic variables, i.e. temperature, precipitation, relative humidity and sunshine fraction on Northeast China. First,Digital terrain models was built with large-scale maps and vector data. Then trend surface analysis and interpolation method were used to analyze the spatial distribution of these four kinds of climatic variables at three temporal scale: (1) monthly data; (2)mean monthly data of thirty years, and (3) mean annual data of thirty years. Ecological information system were used for graphics analysis on the spatial distribution of these climate variables.

  5. Climate variability effects on spatial soil moisture dynamics

    OpenAIRE

    A. J. Teuling; Hupet, F.; R. Uijlenhoet; P. A. Troch

    2007-01-01

    We investigate the role of interannual climate variability on spatial soil moisture variability dynamics for a field site in Louvain-la-Neuve, Belgium. Observations were made during 3 years under intermediate (1999), wet (2000), and extremely dry conditions (2003). Soil moisture variability dynamics are simulated with a comprehensive model for the period 1989-2003. The results show that climate variability induces non-uniqueness and two distinct hysteresis modes in the yearly relation between...

  6. Spatial variability of chloride in concrete within homogeneously exposed areas

    NARCIS (Netherlands)

    Angst, U.M.; Polder, R.B.

    2014-01-01

    The concept of variability is increasingly considered in service life predictions. This paper reports experimental data on the spatial distribution of chloride in uncracked concrete subjected to homogeneous exposure. Chloride concentrations were measured with potentiometric sensors embedded in concr

  7. Managing Temporal and Spatial Variability in Vapor Intrusion Data

    Science.gov (United States)

    2012-03-28

    Managing Temporal and Spatial Variability in Vapor Intrusion Data Todd McAlary, M.Sc., P.Eng., P.G. Geosyntec Consultants, Inc...TITLE AND SUBTITLE Managing Temporal and Spatial Variability in Vapor Intrusion Data 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...Koc (mL/g) OSWER indoor conc. at 10-6 risk (ppb) Vapour pressure (atm) Water solubility (g/l) 1,1,1-Trichloroethane 110 400

  8. A Non-Gaussian Spatial Generalized Linear Latent Variable Model

    KAUST Repository

    Irincheeva, Irina

    2012-08-03

    We consider a spatial generalized linear latent variable model with and without normality distributional assumption on the latent variables. When the latent variables are assumed to be multivariate normal, we apply a Laplace approximation. To relax the assumption of marginal normality in favor of a mixture of normals, we construct a multivariate density with Gaussian spatial dependence and given multivariate margins. We use the pairwise likelihood to estimate the corresponding spatial generalized linear latent variable model. The properties of the resulting estimators are explored by simulations. In the analysis of an air pollution data set the proposed methodology uncovers weather conditions to be a more important source of variability than air pollution in explaining all the causes of non-accidental mortality excluding accidents. © 2012 International Biometric Society.

  9. Spatial impacts of urban structures on micrometeorological variables

    Science.gov (United States)

    Koelbing, Merle; Schuetz, Tobias; Weiler, Markus

    2016-04-01

    humidity can clearly be observed for a larger green space. In areas that are shaded by buildings, air temperature is lower than at the fixed station. We can also observe a higher amount of reflected shortwave radiation on locations with brighter ground cover. We are able to detect thermal radiation by buildings. The detected pattern is most distinctive at days with high incoming solar radiation for all observed parameters except wind. For wind, wind tunnel effects can clearly be shown for locations which are confined by high buildings on two sides. As the results show, the selected method is a suitable approach to assess the variability of micrometeorological variables on small spatial scales in an urban surrounding. Further testing is still needed especially with regard to the influence of the source area of the observed air mass on the measurement results and how the measured variables change i.e. with increasing/decreasing distance to a building, solitary tree or green space.

  10. Determining the spatial variability of personal sampler inlet locations.

    Science.gov (United States)

    Vinson, Robert; Volkwein, Jon; McWilliams, Linda

    2007-09-01

    This article examines the spatial variability of dust concentrations within a coal miner's breathing zone and the impact of sampling location at the cap lamp, nose, and lapel. Tests were conducted in the National Institute for Safety and Health Pittsburgh Research Laboratory full-scale, continuous miner gallery using three prototype personal dust monitors (PDM). The dust masses detected by the PDMs were used to calculate the percentage difference of dust mass between the cap lamp and the nose and between the lapel and the nose. The calculated percentage differences of the masses ranged from plus 12% to minus 25%. Breathing zone tests were also conducted in four underground coal mines using the torso of a mannequin to simulate a miner. Coal mine dust was sampled with multi-cyclone sampling cans mounted directly in front of the mannequin near the cap lamp, nose, and lapel. These four coal mine tests found that the spatial variability of dust levels and imprecision of the current personal sampler is a greater influence than the sampler location within the breathing zone. However, a one-sample t-test of this data did find that the overall mean value of the cap lamp/nose ratio was not significantly different than 1 (p-value = 0.21). However, when applied to the overall mean value of the lapel/nose ratio there was a significant difference from 1 (p-value important because the lapel has always been the sampling location for coal mine dust samples. But these results suggest that the cap location is slightly more indicative of what is breathed through the nose area.

  11. Spatial variability and rainfall characteristics of Kerala

    Indian Academy of Sciences (India)

    Anu Simon; K Mohankumar

    2004-06-01

    Geographical regions of covariability in precipitation over the Kerala state are exposed using factor analysis. The results suggest that Kerala can be divided into three unique rainfall regions, each region having a similar covariance structure of annual rainfall. Stations north of 10°N (north Kerala) fall into one group and they receive more rainfall than stations south of 10°N (south Kerala). Group I stations receive more than 65% of the annual rainfall during the south-west monsoon period, whereas stations falling in Group II receive 25-30% of annual rainfall during the pre-monsoon and the north-east monsoon periods. The meteorology of Kerala is profoundly influenced by its orographical features, however it is difficult to make out a direct relationship between elevation and rainfall. Local features of the state as reflected in the rainfall distribution are also clearly brought out by the study.

  12. Spatial-Temporal variability of seismic hazard in Peninsular India

    Indian Academy of Sciences (India)

    Kishor Jaiswal; Ravi Sinha

    2008-11-01

    This paper examines the variability of seismic activity observed in the case of different geological zones of peninsular India (10°N–26°N; 68°E–90°E) based on earthquake catalog between the period 1842 and 2002 and estimates earthquake hazard for the region. With compilation of earthquake catalog in terms of moment magnitude and establishing broad completeness criteria, we derive the seismicity parameters for each geologic zone of peninsular India using maximum likelihood procedure. The estimated parameters provide the basis for understanding the historical seismicity associated with different geological zones of peninsular India and also provide important inputs for future seismic hazard estimation studies in the region. Based on present investigation, it is clear that earthquake recurrence activity in various geologic zones of peninsular India is distinct and varies considerably between its cratonic and rifting zones. The study identifies the likely hazards due to the possibility of moderate to large earthquakes in peninsular India and also presents the influence of spatial rate variation in the seismic activity of this region. This paper presents the influence of source zone characterization and recurrence rate variation pattern on the maximum earthquake magnitude estimation. The results presented in the paper provide a useful basis for probabilistic seismic hazard studies and microzonation studies in peninsular India.

  13. Temporal variability in aboveground plant biomass decreases as spatial variability increases.

    Science.gov (United States)

    McGranahan, Devan Allen; Hovick, Torre J; Elmore, R Dwayne; Engle, David M; Fuhlendorf, Samuel D; Winter, Stephen L; Miller, James R; Debinski, Diane M

    2016-03-01

    Ecological theory predicts that diversity decreases variability in ecosystem function. We predict that, at the landscape scale, spatial variability created by a mosaic of contrasting patches that differ in time since disturbance will decrease temporal variability in aboveground plant biomass. Using data from a multi-year study of seven grazed tallgrass prairie landscapes, each experimentally managed for one to eight patches, we show that increased spatial variability driven by spatially patchy fire and herbivory reduces temporal variability in aboveground plant biomass. This pattern is associated with statistical evidence for the portfolio effect and a positive relationship between temporal variability and functional group synchrony as predicted by metacommunity variability theory. As disturbance from fire and grazing interact to create a shifting mosaic of spatially heterogeneous patches within a landscape, temporal variability in aboveground plant biomass can be dampened. These results suggest that spatially heterogeneous disturbance regimes contribute to a portfolio of ecosystem functions provided by biodiversity, including wildlife habitat, fuel, and forage. We discuss how spatial patterns of disturbance drive variability within and among patches.

  14. Spatial variability, structure and composition of crustose algal communities in Diadema africanum barrens

    Science.gov (United States)

    Sangil, Carlos; Sansón, Marta; Díaz-Villa, Tania; Hernández, José Carlos; Clemente, Sabrina; Afonso-Carrillo, Julio

    2014-12-01

    Crustose algal communities were studied in Diadema africanum urchin barrens around Tenerife (Canary Islands, NE Atlantic). A hierarchical nested sampling design was used to study patterns of community variability at different spatial scales (sectors, three sides of the island; sites within each sector, 5-10 km apart; stations within each site, 50-100 m apart). Although noncrustose species contributed the most to community richness, cover was dominated by crustose forms, like the coralline algae Hydrolithon farinosum, H. samoënse, H. onkodes, Neogoniolithon orotavicum and N. hirtum, and the phaeophycean Pseudolithoderma adriaticum. The structure of these communities showed high spatial variability, and we found differences in the structure of urchin barrens when compared across different spatial scales. Multivariate analysis showed that variability in community structure was related to the five environmental variables studied (wave exposure, urchin density, substrate roughness, productivity and depth). Wave exposure was the variable that contributed most to community variability, followed by urchin density and substrate roughness. Productivity and depth had limited influence. The effects of these variables differed depending on the spatial scale; wave exposure and productivity were the main variables influencing community changes at the largest scale (between different sectors of the island), while D. africanum density, roughness and depth were the most influential at medium and small scales.

  15. Nonmetropolitan Migration: The Influence of Neglected Variables.

    Science.gov (United States)

    Cook, Annabel Kirschner

    1987-01-01

    Compares influence of employment growth/diversity, commuting, retirement migration, income, unemployment, age structure, and adjacency with influence of nonfarm self-employment and percentage of labor force that is female on recent declines in nonmetropolitan growth rates. Suggests last two variables are more important determinants of…

  16. Spatial and temporal variability of rainfall in the Nile Basin

    Directory of Open Access Journals (Sweden)

    C. Onyutha

    2014-10-01

    Full Text Available Spatio-temporal variability in annual and seasonal rainfall totals were assessed at 37 locations of the Nile Basin in Africa using quantile perturbation method. To get insight into the spatial difference in rainfall statistics, the stations were grouped based on the pattern of the long-term mean of monthly rainfall and that of temporal variability. To find the origin of the driving forces for the temporal variability in rainfall, correlation analyses were carried out using global monthly sea level pressure and surface temperature. Further investigations to support the obtained correlations were made using a total of 10 climate indices. It was possible to obtain 3 groups of stations; those within the equatorial region (A, Sudan and Ethiopia (B, and Egypt (C. For group A, annual rainfall was found to be below (above the reference during the late 1940s to 1950s (1960s to mid 1980s. Conversely for groups B and C, the period 1930s to late 1950s (1960s to 1980s was characterized by anomalies being above (below the reference. For group A, significant linkages were found to Niño 3, Niño 3.4 and the North Atlantic and Indian Ocean drivers. Correlations of annual rainfall of group A with Pacific Ocean-related climate indices were inconclusive. With respect to the main wet seasons, the June to September rainfall of group B has strong connection to the influence from the Indian Ocean. For the March to May (October to February rainfall of group A (C, possible links to the Atlantic and Indian Oceans were found.

  17. Reward expectation influences audiovisual spatial integration.

    Science.gov (United States)

    Bruns, Patrick; Maiworm, Mario; Röder, Brigitte

    2014-08-01

    In order to determine the spatial location of an object that is simultaneously seen and heard, the brain assigns higher weights to the sensory inputs that provide the most reliable information. For example, in the well-known ventriloquism effect, the perceived location of a sound is shifted toward the location of a concurrent but spatially misaligned visual stimulus. This perceptual illusion can be explained by the usually much higher spatial resolution of the visual system as compared to the auditory system. Recently, it has been demonstrated that this cross-modal binding process is not fully automatic, but can be modulated by emotional learning. Here we tested whether cross-modal binding is similarly affected by motivational factors, as exemplified by reward expectancy. Participants received a monetary reward for precise and accurate localization of brief auditory stimuli. Auditory stimuli were accompanied by task-irrelevant, spatially misaligned visual stimuli. Thus, the participants' motivational goal of maximizing their reward was put in conflict with the spatial bias of auditory localization induced by the ventriloquist situation. Crucially, the amounts of expected reward differed between the two hemifields. As compared to the hemifield associated with a low reward, the ventriloquism effect was reduced in the high-reward hemifield. This finding suggests that reward expectations modulate cross-modal binding processes, possibly mediated via cognitive control mechanisms. The motivational significance of the stimulus material, thus, constitutes an important factor that needs to be considered in the study of top-down influences on multisensory integration.

  18. Panel data models extended to spatial error autocorrelation or a spatially lagged dependent variable

    NARCIS (Netherlands)

    Elhorst, J. Paul

    2001-01-01

    This paper surveys panel data models extended to spatial error autocorrelation or a spatially lagged dependent variable. In particular, it focuses on the specification and estimation of four panel data models commonly used in applied research: the fixed effects model, the random effects model, the

  19. How spatial context influences entrepreneurial value creation

    DEFF Research Database (Denmark)

    Müller, Sabine

    2014-01-01

    This paper investigates how rural communities are enriched by entrepreneurial value-creating activities that go beyond job creation and growth. In addition, this study explores how spatial context influences these value-creating activities. This qualitative case-based study shows that rural......-being of the community. Thus, this study contributes to an in-depth understanding of how and why entrepreneurship can create multiple forms of value in rural areas as well as how value creation behaviours are motivated by the spatial context. In addition, it provides explanations why not all rural entrepreneurs...... contribute or at least intend to contribute equally and in a similar way to local development. Thus, by adding contextualized explanations of rural entrepreneurial behaviour to the literature, this study places itself in the recent debate and call for contextualizing entrepreneurship research....

  20. Spatial and temporal variability of chlorophyll in Bay of Bengal.

    Science.gov (United States)

    Jutla, A.; Akanda, S.; Islam, S.

    2009-04-01

    The Bay of Bengal (BoB) receives approximately 628 km3/ year of freshwater discharge from the Ganges and Brahmaputra rivers. Freshwater discharge from rivers increases the nutrient load and thereby enhances phytoplankton production in the BoB. Cholera, an infectious water-borne disease caused by bacterium Vibrio cholerae, remains endemic in the BoB region. Phytoplankton provides favorable environment for survival of cholera bacteria. Therefore, for development of any predictive model for cholera, it is important to quantify the spatial and temporal variability of phytoplankton in the BoB. Satellite remote sensing is the most effective way to quantify this variability over a range of space and time scales. Using ten years (1998-2007) of daily, weekly and monthly SeaWiFs chlorophyll, a surrogate variable for measuring phytoplankton, imagery we explore the spatial pattern and dominant temporal variability of chlorophyll over the BoB region. We find that chlorophyll in the coastal waters has more variability, both in temporal and spatial scales, than the offshore waters. Mechanism of production and space-time variability of coastal chlorophyll is different from those of offshore chlorophyll. While coastal chlorophyll is dominated by influx of terrestrial nutrients through river discharge, chlorophyll in the offshore region is primarily controlled by oceanic processes. We will also explore issues related to dominant space and time scales of chlorophyll variations in the entire bay.

  1. Ionospheric total electron content: Spatial patterns of variability

    Science.gov (United States)

    Lean, J. L.; Meier, R. R.; Picone, J. M.; Sassi, F.; Emmert, J. T.; Richards, P. G.

    2016-10-01

    The distinctive spatial patterns of the ionosphere's total electron content (TEC) response to solar, seasonal, diurnal, and geomagnetic influences are determined across the globe using a new statistical model constructed from 2-hourly TEC observations from 1998 to 2015. The model combines representations of the physical solar EUV photon and geomagnetic activity drivers with solar-modulated sinusoidal parameterizations of four seasonal cycles and solar-modulated and seasonally modulated parameterizations of three diurnal cycles. The average absolute residual of the data-model differences is 2.1 total electron content unit, 1 TECU = 1016 el m-2 (TECU) (9%) and the root-mean-square error is 3.5 TECU (15%). Solar and geomagnetic variability, the semiannual oscillation and the diurnal and semidiurnal oscillations all impact TEC most at low magnetic latitudes where TEC itself maximizes, with differing degrees of longitudinal inhomogeneity. In contrast, the annual oscillation manifests primarily in the Southern Hemisphere with maximum amplitude over midlatitude South America, extending to higher southern latitudes in the vicinity of the Weddell Sea. Nighttime TEC levels in the vicinity of the Weddell Sea exceed daytime levels every year in Southern Hemisphere summer as a consequence of the modulation of the diurnal oscillations by the seasonal oscillations. The anomaly, which is present at all phases of the solar cycle, commences sooner and ends later under solar minimum conditions. The model minus data residuals maximize at tropical magnetic latitudes in four geographical regions similar to the ionosphere pattern generated by lower atmospheric meteorology. Enhanced residuals at northern midlatitudes during winter are consistent with an influence of atmospheric gravity waves.

  2. Assessment of Temperature and Elevation Controls on Spatial Variability of Rainfall in Iran

    OpenAIRE

    Majid Javari

    2017-01-01

    With rainfall changes, hydrological process variability increases. This study predicts the potential effects of temperature and topography characteristics on rainfall spatial variability. Temperature and topography were considered as two effective factors that may influence monthly rainfall. This study uses rainfall and temperature data from 174 synoptic and climatic stations and 39,055 rain, elevation and temperature points extracted by ArcGIS10.3 over the 40 years (1975–2014). In this study...

  3. FUNDAMENTALS OF TRANSMISSION FLUCTUATION SPECTROMETRY WITH VARIABLE SPATIAL AVERAGING

    Institute of Scientific and Technical Information of China (English)

    Jianqi Shen; Ulrich Riebel; Marcus Breitenstein; Udo Kr(a)uter

    2003-01-01

    Transmission signal of radiation in suspension of particles performed with a high spatial and temporal resolution shows significant fluctuations, which are related to the physical properties of the particles and the process of spatial and temporal averaging. Exploiting this connection, it is possible to calculate the parti cie size distribution (PSD)and particle concentration. This paper provides an approach of transmission fluctuation spectrometry (TFS) with variable spatial averaging. The transmission fluctuations are expressed in terms of the expectancy of transmission square (ETS)and are obtained as a spectrum, which is a function of the variable beam diameter. The reversal point and the depth of the spectrum contain the information of particle size and particle concentration, respectively.

  4. Spatial variability in streambed hydraulic conductivity of contrasting stream morphologies

    DEFF Research Database (Denmark)

    Sebök, Éva; Calvache, Carlos Duque; Engesgaard, Peter Knudegaard;

    2015-01-01

    Streambed hydraulic conductivity is one of the main factors controlling variability in surface water-groundwater interactions, but only few studies aim at quantifying its spatial and temporal variability in different stream morphologies. Streambed horizontal hydraulic conductivities (Kh) were...... therefore determined from in-stream slug tests, vertical hydraulic conductivities (Kv) were calculated with in-stream permeameter tests and hydraulic heads were measured to obtain vertical head gradients at eight transects, each comprising five test locations, in a groundwater-dominated stream. Seasonal...... small-scale measurements were taken in December 2011 and August 2012, both in a straight stream channel with homogeneous elevation and downstream of a channel meander with heterogeneous elevation. All streambed attributes showed large spatial variability. Kh values were the highest at the depositional...

  5. Impact of rainfall spatial variability on Flash Flood Forecasting

    Science.gov (United States)

    Douinot, Audrey; Roux, Hélène; Garambois, Pierre-André; Larnier, Kevin

    2014-05-01

    According to the United States National Hazard Statistics database, flooding and flash flooding have caused the largest number of deaths of any weather-related phenomenon over the last 30 years (Flash Flood Guidance Improvement Team, 2003). Like the storms that cause them, flash floods are very variable and non-linear phenomena in time and space, with the result that understanding and anticipating flash flood genesis is far from straightforward. In the U.S., the Flash Flood Guidance (FFG) estimates the average number of inches of rainfall for given durations required to produce flash flooding in the indicated county. In Europe, flash flood often occurred on small catchments (approximately 100 km2) and it has been shown that the spatial variability of rainfall has a great impact on the catchment response (Le Lay and Saulnier, 2007). Therefore, in this study, based on the Flash flood Guidance method, rainfall spatial variability information is introduced in the threshold estimation. As for FFG, the threshold is the number of millimeters of rainfall required to produce a discharge higher than the discharge corresponding to the first level (yellow) warning of the French flood warning service (SCHAPI: Service Central d'Hydrométéorologie et d'Appui à la Prévision des Inondations). The indexes δ1 and δ2 of Zoccatelli et al. (2010), based on the spatial moments of catchment rainfall, are used to characterize the rainfall spatial distribution. Rainfall spatial variability impacts on warning threshold and on hydrological processes are then studied. The spatially distributed hydrological model MARINE (Roux et al., 2011), dedicated to flash flood prediction is forced with synthetic rainfall patterns of different spatial distributions. This allows the determination of a warning threshold diagram: knowing the spatial distribution of the rainfall forecast and therefore the 2 indexes δ1 and δ2, the threshold value is read on the diagram. A warning threshold diagram is

  6. Spatial and temporal variability of mobile macro-invertebrate assemblages associated to coralligenous habitat

    Directory of Open Access Journals (Sweden)

    R. BEDINI

    2014-03-01

    Full Text Available The study aimed to investigate patterns of spatial and temporal variability of mobile macroinvertebrate assemblages associated to coralligenous habitat. A multi-factorial sampling design was used to test the hypotheses that the structure of assemblages and their spatial and temporal variability changed in relation to substrate inclination. Moreover, macroalgae and sessile macro-invertebrates were also investigated in order to detect eventual relationship between sessile and mobile assemblages. A total of 236 mobile macro-invertebrate taxa were identified, among them 2 Platyhelminthes, 4 Sipuncula, 6 Nemertea, 27 Mollusca, 86 Annelida, 103 Arthropoda, 8 Echinodermata. Results of the study showed that mobile macro-invertebrate assemblages of coralligenous habitat were little influenced by the inclination of substrate and by the morphology of sessile organisms, as patterns of variation were different between the two assemblages. Mobile macro-invertebrate assemblages changed among sampling dates within one year period and they showed high variability at the spatial scale examined.

  7. Random spatial processes and geostatistical models for soil variables

    Science.gov (United States)

    Lark, R. M.

    2009-04-01

    Geostatistical models of soil variation have been used to considerable effect to facilitate efficient and powerful prediction of soil properties at unsampled sites or over partially sampled regions. Geostatistical models can also be used to investigate the scaling behaviour of soil process models, to design sampling strategies and to account for spatial dependence in the random effects of linear mixed models for spatial variables. However, most geostatistical models (variograms) are selected for reasons of mathematical convenience (in particular, to ensure positive definiteness of the corresponding variables). They assume some underlying spatial mathematical operator which may give a good description of observed variation of the soil, but which may not relate in any clear way to the processes that we know give rise to that observed variation in the real world. In this paper I shall argue that soil scientists should pay closer attention to the underlying operators in geostatistical models, with a view to identifying, where ever possible, operators that reflect our knowledge of processes in the soil. I shall illustrate how this can be done in the case of two problems. The first exemplar problem is the definition of operators to represent statistically processes in which the soil landscape is divided into discrete domains. This may occur at disparate scales from the landscape (outcrops, catchments, fields with different landuse) to the soil core (aggregates, rhizospheres). The operators that underly standard geostatistical models of soil variation typically describe continuous variation, and so do not offer any way to incorporate information on processes which occur in discrete domains. I shall present the Poisson Voronoi Tessellation as an alternative spatial operator, examine its corresponding variogram, and apply these to some real data. The second exemplar problem arises from different operators that are equifinal with respect to the variograms of the

  8. [Influence of interpolation method and sampling number on spatial prediction accuracy of soil Olsen-P].

    Science.gov (United States)

    Sun, Yi-xiang; Wu, Chuan-zhou; Zhu, Ke-bao; Cui, Zhen-ling; Chen, Xin-ping; Zhang, Fu-suo

    2009-03-01

    Different from the large scale farm management in Europe and America, the scattered farmland management in China made the spatial variability of soil nutrients at county scale in this country more challenging. Taking soil Olsen-P in Wuhu County as an example, the influence of interpolation method and sampling number on the spatial prediction accuracy of soil nutrients was evaluated systematically. The results showed that local polynomial method, ordinary kriging, simple kriging, and disjunctive kriging had higher spatial prediction accuracy than the other interpolation methods. Considering of its simplicity, ordinary kriging was recommended to evaluate the spatial variability of soil Olsen-P within a county. The spatial prediction accuracy would increase with increasing soil sampling number. Taking the spatial prediction accuracy and soil sampling cost into consideration, the optimal sampling number should be from 500 to 1000 to evaluate the spatial variability of soil Olsen-P at county scale.

  9. Observations on the spatial variability of the Prut river discharges

    Directory of Open Access Journals (Sweden)

    Emil-Andrei BRICIU

    2011-06-01

    Full Text Available Liquid and solid discharges of the Prut River were analysed based on measurementsperformed in 7 points from the Romanian national network of water monitoring during aperiod of 30 years. The analyses were performed on flows for the period after theconstruction of the Stânca-Costeşti dam and show the influence of the dam for the entireanalysed time. The analysis from upstream to downstream of the spatial variability of thePrut River annual discharges showed their steady increase downstream and then adecrease in the sector next to Oancea station. A statistical minority of the annualdischarges showed a continuous increase of them until the flowing of Prut into Danube.Knowing that the lower basin of the river is characterized by a low amount of rainfall anda higher evapo(transpiration than the remaining basin, the decreasing flows to the rivermouth is explicable; but the increasing flows to the river mouth cannot be justified, underthese conditions of water balance, than by certain climatological parameters of thermodynamicalnature which generate, with increased frequency, more intense and rich rainfall, with a torrential character. The analyses on couples of three months showed thatthe Oancea flows are higher than the upstream stations (opposite than usual in yearswhen the flows of the upstream hydrometrical stations are lower than the multiannualaverage and that supports the mentioned pluviometrical character. A plausible cause for"Oancea phenomenon" is the increase and the decrease of the sunspots number, whosecycles are relatively well fold on the increase and decrease of annual average flow atOancea hydrometrical station. The strongest increased discharges of the Prut River overthe discharges at the upstream stations occur from May to July (MJJ, the months with thehighest amount of rainfall. Seasonal analysis of MJJ and other couples of 3 monthsshowed that there are also growing flows at Prisăcani station relative to the adjacentstations, but

  10. Spatial Allometric Scaling of Cities Based on Variable Urban Boundaries

    CERN Document Server

    Chen, Yanguang; Li, Xijing

    2015-01-01

    It has been demonstrated that urban growth and hierarchies of cities follow the allometric scaling law. However, there is no study on the allometric relations of the internal spatial structure within a city. This paper is devoted to explore the allometric scaling of intraurban patterns by means of variable boundaries of cities. Based on a digital map, an urban boundary can be determined by given searching radius. Changing the searching radius, we have different urban boundaries for the same city. A set of urban boundaries based on different searching radius is similar to a set of isograms. Three typical measurements can be obtained, including urban area, total length of streets, and number of street nodes. These measurements represent three basic spatial elements of geographical systems, i.e., area, lines, and points. A finding is that the numerical relationships between urban area, street length, and node number follow allometric scaling laws. In practice, the spatial allometry can be used to estimate the fr...

  11. Spatial variability of fine particles in Parisian streets

    OpenAIRE

    Duché, Sarah; Beltrando, Gérard

    2012-01-01

    International audience; To study the spatial variability of airborne particles and to evaluate the personal and tourist exposure to fine particles in Paris, measurements of fine particles (PM2.5) concentrations have been made in Parisian streets in different mode of transport (bus, bike and walking), using a portable sensor. We use also meteorological parameters sensor (temperature,humidity and wind speed), a camera to view traffic and a GPS to compare with particles levels. PM2.5 levels are ...

  12. Spatial variability and Cesium-137 inventories in native forest

    Energy Technology Data Exchange (ETDEWEB)

    Andrello, A.C.; Appoloni, C.R. [Universidade Estadual de Londrina, PR (Brazil). Dept. de Fisica

    2004-09-15

    With the nuclear fission discovery and development of nuclear weapons in 1940s, artificial radioisotopes were introduced in the environment. This contamination is due to worldwide fallout by superficial nuclear tests realized from early 1950s to late 1970s by USA, former URSS, UK, France and China. One of theses radioisotopes that have been very studied is cesium-137. Cesium-137 has a half-life of 30.2 years and its biological behavior is similar to the potassium. The behavior in soil matrix, depth distribution, spatial variability and inventories values of cesium-137 has been determinate for several regions of the world. In Brazil, some research groups have worked on this subject, but there are few works published about theses properties of cesium-137. The aim of this paper was study the depth distribution, spatial variability, and inventory of cesium-137 in native forest. Two native forests (Mata 1 and Mata UEL) were sampling in region of Londrina, PR. The results shows that there is a spatial variability of 40% for Mata 1 and 42% for Mata UEL. The depth distribution of cesium-137 for two forests presented a exponential form, characteristic to undisturbed soil. Cesium-137 inventory determinate for Mata 1 was 358 Bq m{sup -2} and for Mata UEL was 320 Bq m{sup -2}. (author)

  13. Small relief shape variations influence spatial variability of soil chemical attributes Pequenas variações das formas de relevo influenciam a variabilidade espacial de atributos químicos do solo

    Directory of Open Access Journals (Sweden)

    Zigomar Menezes de Souza

    2006-04-01

    Full Text Available Soils with small variations in relief and under the same management system present differentiated spatial variabilities of their attributes. This variability is a function of soil position in the landscape, even if the relief has little expression. The aim of this work was to investigate the effects of relief shape and depth on spatial variability of soil chemical attributes in a Typic Hapludox cultivated with sugar cane at two landscape compartments. Soil samples were collected in the intercrossing points of a grid, in the traffic line, at 0-0.2 m and 0.6-0.8 m depths, comprising a set of 100 georeferenced points. The spatial variabilities of pH, P, K, Ca, Mg, cation exchange capacity and base saturation were quantified. Small relief shape variations lead to differentiated variability in soil chemical attributes as indicated by the dependence on pedoform found for chemical attributes at both 0-0.2 m and 0.6-0.8 m depths. Because of the higher variability, it is advisable to collect large number of samples in areas with concave and convex shapes. Combining relief shapes and geostatistics allows the determination of areas with different spatial variability for soil chemical attributes.Solos submetidos ao mesmo sistema de manejo em locais com pequena variação de relevo, manifestam variabilidade espacial diferenciada de seus atributos. Esta variabilidade é condicionada pela posição dos solos na paisagem ou no declive, mesmo que o relevo seja de pequena expressão. O estudo teve como objetivo avaliar a influência da forma do relevo na variabilidade espacial de atributos químicos em um latossolo cultivado com cana-de-açúcar em dois compartimentos da paisagem. Os solos foram amostrados nos pontos de cruzamento de uma malha, com intervalos regulares de 10 m, perfazendo um total de 100 pontos, nas profundidades de 0-0,2 m e 0,6-0,8 m. Foi avaliado a variabilidade espacial do pH, fósforo (P, potássio (K, cálcio (Ca, magnésio (Mg, acidez

  14. Spatial variability of soil moisture content and its influencing factors in small Karst catchment during dry period%喀斯特小流域土壤含水率空间异质性及其影响因素

    Institute of Scientific and Technical Information of China (English)

    付同刚; 陈洪松; 张伟; 高鹏; 王克林

    2014-01-01

    and other soil properties, including bulk density (BD), capillary capacity (CP), non-capillary capacity (NCP), soil organic carbon (SOC), and rock fragment content (RC). Environmental factors including topographical position (upper-slope, middle-slope, lower-slope and depression), land use type (forestland, shrubland, shrub-grassland and farmland), slope gradient (SG), slope aspect (SA) and bare rock (BR) were investigated around the sampling points. Spatial variability of SMC and its influencing factors were analyzed by both geostatistical and classical analysis methods. The results showed that the mean value of SMC was 34.43%. The SMC had a moderate variation with the coefficient of variation of 0.33. The geostatistical results showed that the semivariance of SMC was best fitted by exponential model with a higher determination coefficient of 0.910. The range was 381.00 m and the nugget/sill value was 0.382, indicating a moderate spatial correlation of SMC. When the lag distance was smaller than 200 m, the variation in 120° direction was higher than that of 30° direction. However, when the lag distance was exceeded 200 m, no anisotropy was found in 120° and 30° directions with the anisotropy ratio fluctuated around 1. The Kriging map showed that SMC generally decreased with the increasing altitude. Most of the slope had a lower SMC value less than 35%. The highest SMC value always appeared in the east of the depression which was higher than 50%. The Pearson correlation analysis showed that CP had a significant (p<0.01) positive correlation with SMC but RC and BD had a significant negative correlation with SMC. NCP had a significantly negatives effect on SMC with the significant value of 0.022. However, SOC only significantly affected SMC at 0.10 level. This suggested that all the soil properties had important influence on SMC. However, for the topographical factors, only SG had a significant influence on SMC with the correlation coefficient of-0.435 (p<0

  15. Minimizing Spatial Variability of Healthcare Spatial Accessibility—The Case of a Dengue Fever Outbreak

    Science.gov (United States)

    Chu, Hone-Jay; Lin, Bo-Cheng; Yu, Ming-Run; Chan, Ta-Chien

    2016-01-01

    Outbreaks of infectious diseases or multi-casualty incidents have the potential to generate a large number of patients. It is a challenge for the healthcare system when demand for care suddenly surges. Traditionally, valuation of heath care spatial accessibility was based on static supply and demand information. In this study, we proposed an optimal model with the three-step floating catchment area (3SFCA) to account for the supply to minimize variability in spatial accessibility. We used empirical dengue fever outbreak data in Tainan City, Taiwan in 2015 to demonstrate the dynamic change in spatial accessibility based on the epidemic trend. The x and y coordinates of dengue-infected patients with precision loss were provided publicly by the Tainan City government, and were used as our model’s demand. The spatial accessibility of heath care during the dengue outbreak from August to October 2015 was analyzed spatially and temporally by producing accessibility maps, and conducting capacity change analysis. This study also utilized the particle swarm optimization (PSO) model to decrease the spatial variation in accessibility and shortage areas of healthcare resources as the epidemic went on. The proposed method in this study can help decision makers reallocate healthcare resources spatially when the ratios of demand and supply surge too quickly and form clusters in some locations. PMID:27983611

  16. Minimizing Spatial Variability of Healthcare Spatial Accessibility—The Case of a Dengue Fever Outbreak

    Directory of Open Access Journals (Sweden)

    Hone-Jay Chu

    2016-12-01

    Full Text Available Outbreaks of infectious diseases or multi-casualty incidents have the potential to generate a large number of patients. It is a challenge for the healthcare system when demand for care suddenly surges. Traditionally, valuation of heath care spatial accessibility was based on static supply and demand information. In this study, we proposed an optimal model with the three-step floating catchment area (3SFCA to account for the supply to minimize variability in spatial accessibility. We used empirical dengue fever outbreak data in Tainan City, Taiwan in 2015 to demonstrate the dynamic change in spatial accessibility based on the epidemic trend. The x and y coordinates of dengue-infected patients with precision loss were provided publicly by the Tainan City government, and were used as our model’s demand. The spatial accessibility of heath care during the dengue outbreak from August to October 2015 was analyzed spatially and temporally by producing accessibility maps, and conducting capacity change analysis. This study also utilized the particle swarm optimization (PSO model to decrease the spatial variation in accessibility and shortage areas of healthcare resources as the epidemic went on. The proposed method in this study can help decision makers reallocate healthcare resources spatially when the ratios of demand and supply surge too quickly and form clusters in some locations.

  17. Temporal Changes in the Spatial Variability of Soil Nutrients

    Energy Technology Data Exchange (ETDEWEB)

    R. L. Hoskinson; J. R. Hess; R. S. Alessi

    1999-07-01

    This paper reports the temporal changes in the spatial variability of soil nutrient concentrations across a field during the growing season, over a four-year period. This study is part of the Site-Specific Technologies for Agriculture (SST4Ag) precision farming research project at the INEEL. Uniform fertilization did not produce a uniform increase in fertility. During the growing season, several of the nutrients and micronutrients showed increases in concentration although no additional fertilization had occurred. Potato plant uptake did not explain all of these changes. Some soil micronutrient concentrations increased above levels considered detrimental to potatoes, but the plants did not show the effects in reduced yield. All the nutrients measured changed between the last sampling in the fall and the first sampling the next spring prior to fertilization. The soil microbial community may play a major role in the temporal changes in the spatial variability of soil nutrient concentrations. These temporal changes suggest potential impact when determining fertilizer recommendations, and when evaluating the results of spatially varying fertilizer application.

  18. Rainfall interception and spatial variability of throughfall in spruce stand

    Directory of Open Access Journals (Sweden)

    Dohnal Michal

    2014-12-01

    Full Text Available The interception was recognized as an important part of the catchment water balance in temperate climate. The mountainous forest ecosystem at experimental headwater catchment Liz has been subject of long-term monitoring. Unique dataset in terms of time resolution serves to determine canopy storage capacity and free throughfall. Spatial variability of throughfall was studied using one weighing and five tipping bucket rain gauges. The basic characteristics of forest affecting interception process were determined for the Norway spruce stand at the experimental area - the leaf area index was 5.66 - 6.00 m2 m-2, the basal area was 55.7 m2 ha-1, and the crown closure above individual rain gauges was between 19 and 95%. The total interception loss in both growing seasons analyzed was 34.5%. The mean value of the interception capacity determined was about 2 mm. Throughfall exhibited high variability from place to place and it was strongly affected by character of rainfall. On the other hand, spatial pattern of throughfall in average showed low variability.

  19. Spatial and temporal variability of precipitation and drought in Portugal

    Directory of Open Access Journals (Sweden)

    D. S. Martins

    2012-05-01

    Full Text Available The spatial variability of precipitation and drought are investigated for Portugal using monthly precipitation from 74 stations and minimum and maximum temperature from 27 stations, covering the common period of 1941–2006. Seasonal precipitation and the corresponding percentages in the year, as well as the precipitation concentration index (PCI, was computed for all 74 stations and then used as an input matrix for an R-mode principal component analysis to identify the precipitation patterns. The standardized precipitation index at 3 and 12 month time scales were computed for all stations, whereas the Palmer Drought Severity Index (PDSI and the modified PDSI for Mediterranean conditions (MedPDSI were computed for the stations with temperature data. The spatial patterns of drought over Portugal were identified by applying the S-mode principal component analysis coupled with varimax rotation to the drought indices matrices. The result revealed two distinct sub-regions in the country relative to both precipitation regimes and drought variability. The analysis of time variability of the PC scores of all drought indices allowed verifying that there is no linear trend indicating drought aggravation or decrease. In addition, the analysis shows that results for SPI-3, SPI-12, PDSI and MedPDSI are coherent among them.

  20. Spatial variability of CO2 uptake in polygonal tundra

    DEFF Research Database (Denmark)

    Pirk, Norbert; Sievers, Jakob; Mertes, Jordan

    2017-01-01

    with an unmanned aerial vehicle (UAV) that mapped ice-wedge morphology to complement eddy covariance (EC) flux measurements of CO2. The analysis of spectral distributions showed that conventional EC methods do not accurately capture the turbulent CO2 exchange with a spatially heterogeneous surface that typically......The large spatial variability in Arctic tundra complicates the representative assessment of CO2 budgets. Accurate measurements of these heterogeneous landscapes are, however, essential to understanding their vulnerability to climate change. We surveyed a polygonal tundra lowland on Svalbard...... features small flux magnitudes. Nonlocal (low-frequency) flux contributions were especially pronounced during snow melt and introduced a large bias of -46 gC m(-2) to the annual CO2 budget in conventional methods (the minus sign indicates a higher uptake by the ecosystem). Our improved flux calculations...

  1. Predictivity strength of the spatial variability of phenanthrene sorption across two sandy loam fields

    DEFF Research Database (Denmark)

    Soares, Antonio; Paradelo Pérez, Marcos; Møldrup, Per

    2015-01-01

    Sorption is commonly suggested as the major process underlying the transport and fate of polycyclic aromatic hydrocarbons (PAHs) in soils. However, studies focusing in spatial variability at the field scale in particular are still scarce. In order to investigate the sorption of phenanthrene at th......). Other factors, such as the soil structure, available water content and the soil mineral fraction, might greatly influence the transport phenomenon, thus acting for important environmental repercussions....

  2. SPATIAL VARIABILITY OF SOIL PROPERTIES IN AN AGRARIAN REFORM SETTLEMENT

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    James Ribeiro de Azevedo

    2015-12-01

    Full Text Available ABSTRACT The study of soil chemical and physical properties variability is important for suitable management practices. The aim of this study was to evaluate the spatial variability of soil properties in the Malhada do Meio settlement to subsidize soil use planning. The settlement is located in Chapadinha, MA, Brazil, and has an area of 630.86 ha. The vegetation is seasonal submontane deciduous forest and steppe savanna. The geology is formed of sandstones and siltstones of theItapecuru Formation and by colluvial and alluvial deposits. The relief consists of hills with rounded and flat tops with an average altitude of 67 m, and frequently covered over by ferruginous duricrusts. A total of 183 georeferenced soil samples were collected at the depth of 0.00-0.20 m inPlintossolos, Neossolo andGleissolo. The following chemical variables were analyzed: pH(CaCl2, H+Al, Al, SB, V, CEC, P, K, OM, Ca, Mg, SiO2, Al2O3, and Fe2O3; along with particle size variables: clay, silt, and sand. Descriptive statistical and geostatistical analyses were carried out. The coefficient of variation (CV was high for most of the variables, with the exception of pH with a low CV, and of sand with a medium CV. The models fitted to the experimental semivariograms of these variables were the exponential and the spherical. The range values were from 999 m to 3,690 m. For the variables pH(CaCl2, SB, and clay, there are three specific areas for land use planning. The central part of the area (zone III, where thePlintossolos Pétricos and Neossolos Flúvicos occur, is the most suitable for crops due to higher macronutrient content, organic matter and pH. Zones I and II are indicated for environmental preservation.

  3. Spatial variability in bank resistance to erosion on a large meandering, mixed bedrock-alluvial river

    Science.gov (United States)

    Konsoer, Kory M.; Rhoads, Bruce L.; Langendoen, Eddy J.; Best, James L.; Ursic, Mick E.; Abad, Jorge D.; Garcia, Marcelo H.

    2016-01-01

    Spatial heterogeneity in the erosion-resistance properties of the channel banks and floodplains associated with sediment characteristics, vegetation, or bedrock can have a substantial influence on the morphodynamics of meandering rivers, resulting in highly variable rates of bank erosion and complex patterns of planform evolution. Although past studies have examined the spatial variability in bank erodibility within small rivers, this aspect of the erosion-resistance properties for large rivers remains poorly understood. Furthermore, with the exception of recent numerical modeling that incorporates stochastic variability of floodplain erosional resistance, most models of meandering river dynamics have assumed uniform erodibility of the bank and floodplain materials. The present paper investigates the lateral and vertical heterogeneity in bank material properties and riparian vegetation within two elongate meander loops on a large mixed bedrock-alluvial river using several geotechnical field and laboratory methods. Additionally, the bank stability and toe-erosion numerical model (BSTEM) and repeat terrestrial LiDAR surveys are used to evaluate the capacity of the bank material properties to modify the rates and mechanisms of bank retreat. Results show that the textural properties of the bank materials, soil cohesion, and critical shear stress necessary for sediment entrainment differ substantially between the two bends and are also highly variable within each bend - laterally and vertically. Trees growing along the banks increase the resistance to erosion by contributing to the shear strength of the bank materials and are capable of increasing bank stability along a large river. Locally outcropping bedrock also influences bank erodibility in both bends. The results of this study demonstrate that spatial variability in the erosion-resistance properties of the channel banks is an important factor contributing to spatial variability in the rates and mechanisms of bank

  4. Spatially-variable carbonation reactions in polycrystalline olivine

    Science.gov (United States)

    Wells, Rachel K.; Xiong, Wei; Sesti, Erika; Cui, Jinlei; Giammar, Daniel; Skemer, Philip; Hayes, Sophia E.; Conradi, Mark S.

    2017-05-01

    Carbon dioxide (CO2) injection into olivine-rich mafic and ultramafic rocks is expected to result in the precipitation of divalent metal carbonate minerals, permanently storing the CO2 underground. Previous experiments that used unconsolidated forsterite (Mg2SiO4) particles in experimental investigations of reactions with water and carbon dioxide have been useful for determining the identity, rates of formation, and spatial location of carbonate mineral reaction products. However there remains a need for information regarding the influence of the internal pore structure and grain boundary surfaces on the extent and locations of these reactions in dense aggregates. We conducted several experiments at 100 °C and 100 bar CO2 using sintered San Carlos olivine (Fo90) and pure forsterite (Fo100) cylinders, and we documented the type and spatial distribution of the reaction products. Timing of carbonation was measured using in-situ 13C NMR spectroscopy without removing the sample from the reactor. Ex-situ solid-state NMR spectroscopy, Raman spectroscopy, and electron microscopy were used to examine reacted samples and precipitates. Within 15 days, magnesite is observed only on the surface of Fo90. After 53 and 102 days of reaction, magnesite and amorphous silica are observed as a crust around the entire Fo100 cylinder and as isolated layers within the sample. The spatial transition from an amorphous silica layer to the host Fo100 indicates that the development of amorphous silica did not impede further forsterite dissolution. While earlier studies documented localized reactions at the grain scale, the development of distinct zones of magnesite and amorphous silica suggest that divalent metal cations are mobile during carbonation of olivine. Grain boundaries, pore structure, and geochemical gradients strongly influence the locations of silicate mineral dissolution and carbonate mineral precipitation even in the absence of advective transport or confinement. The clear

  5. Spatial variability of soils in a seasonally dry tropical forest

    Science.gov (United States)

    Pulla, Sandeep; Riotte, Jean; Suresh, Hebbalalu; Dattaraja, Handanakere; Sukumar, Raman

    2016-04-01

    Soil structures communities of plants and soil organisms in tropical forests. Understanding the controls of soil spatial variability can therefore potentially inform efforts towards forest restoration. We studied the relationship between soils and lithology, topography, vegetation and fire in a seasonally dry tropical forest in southern India. We extensively sampled soil (available nutrients, Al, pH, and moisture), rocks, relief, woody vegetation, and spatial variation in fire burn frequency in a permanent 50-ha plot. Lower elevation soils tended to be less moist and were depleted in several nutrients and clay. The availability of several nutrients was, in turn, linked to whole-rock chemical composition differences since some lithologies were associated with higher elevations, while the others tended to dominate lower elevations. We suggest that local-scale topography in this region has been shaped by the spatial distribution of lithologies, which differ in their susceptibility to weathering. Nitrogen availability was uncorrelated with the presence of trees belonging to Fabaceae, a family associated with N-fixing species. No effect of burning on soil parameters could be discerned at this scale.

  6. SPATIAL MODELLING FOR DESCRIBING SPATIAL VARIABILITY OF SOIL PHYSICAL PROPERTIES IN EASTERN CROATIA

    Directory of Open Access Journals (Sweden)

    Igor Bogunović

    2016-06-01

    Full Text Available The objectives of this study were to characterize the field-scale spatial variability and test several interpolation methods to identify the best spatial predictor of penetration resistance (PR, bulk density (BD and gravimetric water content (GWC in the silty loam soil in Eastern Croatia. The measurements were made on a 25 x 25-m grid which created 40 individual grid cells. Soil properties were measured at the center of the grid cell deep 0-10 cm and 10-20 cm. Results demonstrated that PR and GWC displayed strong spatial dependence at 0-10 cm BD, while there was moderate and weak spatial dependence of PR, BD and GWC at depth of 10-20 cm. Semi-variogram analysis suggests that future sampling intervals for investigated parameters can be increased to 35 m in order to reduce research costs. Additionally, interpolation models recorded similar root mean square values with high predictive accuracy. Results suggest that investigated properties do not have uniform interpolation method implying the need for spatial modelling in the evaluation of these soil properties in Eastern Croatia.

  7. Modeling temporal and spatial variability of crop yield

    Science.gov (United States)

    Bonetti, S.; Manoli, G.; Scudiero, E.; Morari, F.; Putti, M.; Teatini, P.

    2014-12-01

    In a world of increasing food insecurity the development of modeling tools capable of supporting on-farm decision making processes is highly needed to formulate sustainable irrigation practices in order to preserve water resources while maintaining adequate crop yield. The design of these practices starts from the accurate modeling of soil-plant-atmosphere interaction. We present an innovative 3D Soil-Plant model that couples 3D hydrological soil dynamics with a mechanistic description of plant transpiration and photosynthesis, including a crop growth module. Because of its intrinsically three dimensional nature, the model is able to capture spatial and temporal patterns of crop yield over large scales and under various climate and environmental factors. The model is applied to a 25 ha corn field in the Venice coastland, Italy, that has been continuously monitored over the years 2010 and 2012 in terms of both hydrological dynamics and yield mapping. The model results satisfactorily reproduce the large variability observed in maize yield (from 2 to 15 ton/ha). This variability is shown to be connected to the spatial heterogeneities of the farmland, which is characterized by several sandy paleo-channels crossing organic-rich silty soils. Salt contamination of soils and groundwater in a large portion of the area strongly affects the crop yield, especially outside the paleo-channels, where measured salt concentrations are lower than the surroundings. The developed model includes a simplified description of the effects of salt concentration in soil water on transpiration. The results seem to capture accurately the effects of salt concentration and the variability of the climatic conditions occurred during the three years of measurements. This innovative modeling framework paves the way to future large scale simulations of farmland dynamics.

  8. Exploring patterns of variation in amphipod assemblages at multiple spatial scales: natural variability versus coastal aquaculture effect

    OpenAIRE

    2013-01-01

    A 5-factor design survey was carried out to examine the spatial distribution at different scales of amphipod assemblages and sedimentary variables in soft bottoms adjacent to coastal aquaculture installations. Natural variability of sediment variables showed the highest values at the scales of sites (10s of meters) and locality (1 to 10 km), while the greatest component of variation of amphipod assemblages occurred among replicates (on the scale of meters). Regarding the influence of coastal ...

  9. Variables influencing victim selection in genocide.

    Science.gov (United States)

    Komar, Debra A

    2008-01-01

    While victims of racially motivated violence may be identified through observation of morphological features, those targeted because of their ethnic, religious, or national identity are not easily recognized. This study examines how perpetrators of genocide recognize their victims. Court documents, including indictments, witness statements, and testimony from the International Criminal Tribunals for Rwanda and the former Yugoslavia (FY) detail the interactions between victim and assailant. A total of 6012 decedents were included in the study; only 20.8% had been positively identified. Variables influencing victim selection in Rwanda included location, segregation, incitement, and prior relationship, while significant factors in FY were segregation, location, age/gender, and social data. Additional contributing factors in both countries included self-identification, victim behavior, linguistic or clothing evidence, and morphological features. Understanding the system of recognition used by perpetrators aids investigators tasked with establishing victim identity in such prosecutions.

  10. Spatial variability of Chinook salmon spawning distribution and habitat preferences

    Science.gov (United States)

    Cram, Jeremy M.; Torgersen, Christian; Klett, Ryan S.; Pess, George R.; May, Darran; Pearsons, Todd N.; Dittman, Andrew H.

    2017-01-01

    We investigated physical habitat conditions associated with the spawning sites of Chinook Salmon Oncorhynchus tshawytscha and the interannual consistency of spawning distribution across multiple spatial scales using a combination of spatially continuous and discrete sampling methods. We conducted a census of aquatic habitat in 76 km of the upper main-stem Yakima River in Washington and evaluated spawning site distribution using redd survey data from 2004 to 2008. Interannual reoccupation of spawning areas was high, ranging from an average Pearson’s correlation of 0.62 to 0.98 in channel subunits and 10-km reaches, respectively. Annual variance in the interannual correlation of spawning distribution was highest in channel units and subunits, but it was low at reach scales. In 13 of 15 models developed for individual years (2004–2008) and reach lengths (800 m, 3 km, 6 km), stream power and depth were the primary predictors of redd abundance. Multiple channels and overhead cover were patchy but were important secondary and tertiary predictors of reach-scale spawning site selection. Within channel units and subunits, pool tails and thermal variability, which may be associated with hyporheic exchange, were important predictors of spawning. We identified spawning habitat preferences within reaches and channel units that are relevant for salmonid habitat restoration planning. We also identified a threshold (i.e., 2-km reaches) beyond which interannual spawning distribution was markedly consistent, which may be informative for prioritizing habitat restoration or conservation. Management actions may be improved through enhanced understanding of spawning habitat preferences and the consistency with which Chinook Salmon reoccupy spawning areas at different spatial scales.

  11. Spatial variability of POPs in European background air

    Directory of Open Access Journals (Sweden)

    A. K. Halse

    2011-02-01

    Full Text Available Passive air samplers (PAS were deployed at 86 European background sites during summer 2006 in order (i to gain further insight into spatial patterns of persistent organic pollutants (POPs in European background air and, (ii to evaluate PAS as an alternative sampling technique under EMEP (Co-operative programme for monitoring and evaluation of the long-range transmissions of air pollutants in Europe. The samples were analyzed for selected PCBs, HCHs, DDTs, HCB, PAHs and chlordanes, and air concentrations were calculated on the basis of losses of performance reference compounds. Air concentrations of PCBs were generally lowest in more remote areas of northern Europe with elevated levels in more densely populated areas. γ-HCH was found at elevated levels in more central parts of Europe, whereas α-HCH, β-HCH and DDTs showed higher concentrations in the south-eastern part. There was no clear spatial pattern in the concentrations for PAHs, indicative of influence by local sources, rather than long range atmospheric transport (LRAT. HCB was evenly distributed across Europe, while the concentrations of chlordanes were typically low or non-detectable. A comparison of results obtained on the basis of PAS and active air sampling (AAS illustrated that coordinated PAS campaigns have the potential serve as useful inter-comparison exercises within and across existing monitoring networks. The results also highlighted limitations of the current EMEP measurement network with respect to spatial coverage. We finally adopted an existing Lagrangian transport model (FLEXPART as recently modified to incorporate key processes relevant for POPs to evaluate potential source regions affecting observed concentrations at selected sites. Using PCB-28 as an example, the model predicted concentrations which agreed within a factor of 3 with PAS measurements for all except 1 out of the 17 sites selected for this analysis.

  12. Temporal and Spatial Variability along the Deep Western Boundary Current

    Science.gov (United States)

    Schmidtko, Sunke; Fischer, Jürgen

    2017-04-01

    The North Atlantic Deep Western Boundary Current (DWBC) connects the polar and subpolar regions, where the ocean is ventilated to greater depth, with the tropical oceans and beyond. It is part of the global ocean circulation as the deep branch of the Atlantic meridional overturning circulation (AMOC). It has a core depth between 1500-4500m with water mass properties varying by origin and decade. We analyze all publically available CTD data from Porcupine Abyssal Plain along Denmark Straight, Labrador Sea, Cape Cod, Cape Hatteras and Bahamas to the equator. The spatial and temporal development is analyzed for the past five decades. Waters originating from the overflow regions between Greenland and Scotland and from the Labrador Sea merge along the pathway but show distinct temporal variability and trends. We distinguish between local and large-scale variability and relate our results with the atmospheric forcing of the North Atlantic. This gives insight into new key aspects to be validated with state of the art ocean circulation models.

  13. Spatial and temporal variability of Mediterranean drought events

    Science.gov (United States)

    Trigo, R.; Sousa, P.; Nieto, R.; Gimeno, L.

    2009-04-01

    The original Palmer Drought Severity Index (PDSI) and a recent adaptation to European soil characteristics, the Self Calibrated PDSI (or scPDSI) proposed by Schrier et al (2005) were used. We have computed monthly, seasonal and annual trends between 1901 and 2000 but also for the first and second halves of the 20th century. Results were represented only when achieving a minimum level of statistical significance (either 5% or 10% using a Mann-Kendall test) and confirm that the majority of the western and central Mediterranean is getting drier in the last decades of the 20th century while Turkey is generally getting wetter (Trigo et al., 2006). The spatio-temporal variability of these indices was evaluated with an EOF analysis, in order to reduce the large dimensionality of the fields under analysis. Spatial representation of the first EOF patterns shows that EOF 1 covers the entire Mediterranean basin (16.4% of EV), while EOF2 is dominated by a W-E dipole (10% EV). The following EOF patterns present smaller scale features, and explain smaller amounts of variance. The EOF patterns have also facilitated the definition of four sub-regions with large socio-economic relevance: 1) Iberia, 2) Italian Peninsula, 3) Balkans and 4) Turkey. The inter-annual variability of the regional spatial droughts indices for each region was analyzed separately. We have also performed an evaluation of their eventual links with large-scale atmospheric circulation indices that affect the Mediterranean basin, namely the NAO, EA, and SCAND. Finally we have evaluated the main sources of moisture affecting two drought prone areas in the western (Iberia) and eastern (Balkans) Mediterranean. This analysis was performed by means of backward tracking the air masses that ultimately reach these two regions using the Lagrangian particle dispersion model FLEXPART (Stohl et al., 1998) and meteorological analysis data from the ECMWF to track atmospheric moisture. This was done for a five-year period (2000

  14. Spatial Durbin Model (SDM For Identified Influence Dengue Hemorrhagic Fever Factors in Kabupaten Malang

    Directory of Open Access Journals (Sweden)

    Indah Resti Ayuni Suri

    2012-05-01

    Full Text Available Dengue Hemorrhagic Fever or usually populer call DBD (Demam Berdarah Degue is the cronic desease that caused by virus infection who carry by Aedes Aegypti mousquito. The observation act by DBD descriptioning and some factors territorial view that influence them, also DBD’s modeling use Spatial Durbin Model (SDM. SDM is the particullary case from Spatial Autoregresive Model (SAR, it means modeling with spatial lag at dependen variable and independen variable. This observation use ratio DBD invectors amount with population amount of citizenry at Kabupaten Malang in 2009. Some variable was used, those are the precentation of existention free number embrio, ratio of civil amount between family, procentation of healthy clinic between invectors and procentase of the invectors who taking care by medical help with amount of invectors. The fourth variables are independen variable to ratio of DBD invector amount with population of citizenry amount, as dependen variable trough spatial SDM modelling. The result of SDM parameter modelling, the significant influence variable in session % is the procentation of free amount embrio existention from their own district, the procentation of healthy clinic amount with the DBD invector amount from their own district, the ratio of the population of citizenry with the family from their neighborhood district, and the procentation of healthy clinic amount with the DBD invector amount from their neighborhood district.

  15. On the spatial and temporal variability of ENSO precipitation and drought teleconnection in mainland Southeast Asia

    Science.gov (United States)

    Räsänen, Timo A.; Lindgren, Ville; Guillaume, Joseph H. A.; Buckley, Brendan M.; Kummu, Matti

    2016-09-01

    The variability of the hydroclimate over mainland Southeast Asia is strongly influenced by the El Niño-Southern Oscillation (ENSO), which has been linked to severe droughts and floods that profoundly influence human societies and ecosystems alike. Although the significance of ENSO is well understood, there are still limitations in the understanding of its effects on hydroclimate, particularly with regard to understanding the spatio-temporal characteristics and the long-term variation of its effects. Therefore we analysed the seasonal evolution and spatial variations in the effect of ENSO on precipitation over the period of 1980-2013 and the long-term variation in the ENSO teleconnection using tree-ring-derived Palmer drought severity indices (PDSIs) for the March-May season that span over the time period 1650-2004. The analyses provided an improved understanding of the seasonal evolution of the precipitation anomalies during ENSO events. The effects of ENSO were found to be most consistent and expressed over the largest areal extents during March-May of the year when the ENSO events decay. On a longer timescale, we found that ENSO has affected the region's March-May hydroclimate over the majority (95 %) of the 355-year study period and that during half (52 %) of the time ENSO caused a significant increase in hydroclimatic variability. The majority of the extremely wet and dry March-May seasons also occurred during ENSO events. However, considerable variability in ENSO's influence was revealed: the spatial pattern of precipitation anomalies varied between individual ENSO events, and the strength of ENSO's influence was found to vary through time. Given the high variability in ENSO teleconnection that we described and the limitations of the current understanding of the effects of ENSO, we suggest that the adaptation to ENSO-related extremes in hydroclimate over mainland Southeast Asia needs to recognise uncertainty as an inherent part of adaptation, must go beyond

  16. Spatial variability of detrended soil plow layer penetrometer resistance transect in a sugarcane field

    Science.gov (United States)

    Pérez, Luis D.; Cumbrera, Ramiro; Mato, Juan; Millán, Humberto; Tarquis, Ana M.

    2015-04-01

    Spatial variability of soil properties is relevant for identifying those zones with physical degradation. In this sense, one has to face the problem of identifying the origin and distribution of spatial variability patterns (Brouder et al., 2001; Millán et al., 2012). The objective of the present work was to quantify the spatial structure of soil penetrometer resistance (PR) collected from a transect data consisted of 221 points equidistant. In each sampling, readings were obtained from 0 cm till 70 cm of depth, with an interval of 5 cm (Pérez, 2012). The study was conducted on a Vertisol (Typic Hapludert) dedicated to sugarcane (Saccharum officinarum L.) production during the last sixty years (Pérez et al., 2010). Recently, scaling approach has been applied on the determination of the scaling data properties (Tarquis et al., 2008; Millán et al., 2012; Pérez, 2012). We focus in the Hurst analysis to characterize the data variability for each depth. Previously a detrended analysis was conducted in order to better study de intrinsic variability of the series. The Hurst exponent (H) for each depth was estimated showing a characteristic pattern and differentiating PR evolution in depth. References Brouder, S., Hofmann, B., Reetz, H.F., 2001. Evaluating spatial variability of soil parameters for input management. Better Crops 85, 8-11. Millán, H; AM Tarquís, Luís D. Pérez, Juan Mato, Mario González-Posada, 2012. Spatial variability patterns of some Vertisol properties at a field scale using standardized data. Soil and Tillage Research, 120, 76-84. Pérez, Luís D. 2012. Influencia de la maquinaria agrícola sobre la variabilidad espacial de la compactación del suelo. Aplicación de la metodología geoestadística-fractal. PhD thesis, UPM (In Spanish). Pérez, Luís D., Humberto Millán, Mario González-Posada 2010. Spatial complexity of soil plow layer penetrometer resistance as influenced by sugarcane harvesting: A prefractal approach. Soil and Tillage

  17. Explaining Spatial Variability in Wellbore Impairment Risk for Pennsylvania Oil and Gas Wells, 2000-2014

    Science.gov (United States)

    Santoro, R.; Ingraffea, A. R.

    2015-12-01

    Previous modeling (ingraffea et al. PNAS, 2014) indicated roughly two-times higher cumulative risk for wellbore impairment in unconventional wells, relative to conventional wells, and large spatial variation in risk for oil and gas wells drilled in the state of Pennsylvania. Impairment risk for wells in the northeast portion of the state were found to be 8.5-times greater than that of wells drilled in the rest of the state. Here, we set out to explain this apparent regional variability through Boosted Regression Tree (BRT) analysis of geographic, developmental, and general well attributes. We find that regional variability is largely driven by the nature of the development, i.e. whether conventional or unconventional development is dominant. Oil and natural gas market prices and total well depths present as major influences in wellbore impairment, with moderate influences from well densities and geologic factors. The figure depicts influence paths for predictors of impairments for the state (top left), SW region (top right), unconventional/NE region (bottom left) and conventional/NW region (bottom right) models. Influences are scaled to reflect percent contributions in explaining variability in the model.

  18. Tools for Optimizing Management of a Spatially Variable Organic Field

    Directory of Open Access Journals (Sweden)

    Thomas Panagopoulos

    2015-03-01

    Full Text Available Geostatistical tools were used to estimate spatial relations between wheat yield and soil parameters under organic farming field conditions. Thematic maps of each factor were created as raster images in R software using kriging. The Geographic Resources Analysis Support System (GRASS calculated the principal component analysis raster images for soil parameters and yield. The correlation between the raster arising from the PC1 of soil and yield parameters showed high linear correlation (r = 0.75 and explained 48.50% of the data variance. The data show that durum wheat yield is strongly affected by soil parameter variability, and thus, the average production can be substantially lower than its potential. Soil water content was the limiting factor to grain yield and not nitrate as in other similar studies. The use of precision agriculture tools helped reduce the level of complexity between the measured parameters by the grouping of several parameters and demonstrating that precision agriculture tools can be applied in small organic fields, reducing costs and increasing wheat yield. Consequently, site-specific applications could be expected to improve the yield without increasing excessively the cost for farmers and enhance environmental and economic benefits.

  19. Land agroecological quality assessment in conditions of high spatial soil cover variability at the Pereslavskoye Opolye.

    Science.gov (United States)

    Morev, Dmitriy; Vasenev, Ivan

    2015-04-01

    The essential spatial variability is mutual feature for most natural and man-changed soils at the Central region of European territory of Russia. The original spatial heterogeneity of forest soils has been further complicated by a specific land-use history and human impacts. For demand-driven land-use planning and decision making the quantitative analysis and agroecological interpretation of representative soil cover spatial variability is an important and challenging task that receives increasing attention from private companies, governmental and environmental bodies. Pereslavskoye Opolye is traditionally actively used in agriculture due to dominated high-quality cultivated soddy-podzoluvisols which are relatively reached in organic matter (especially for conditions of the North part at the European territory of Russia). However, the soil cover patterns are often very complicated even within the field that significantly influences on crop yield variability and have to be considered in farming system development and land agroecological quality evaluation. The detailed investigations of soil regimes and mapping of the winter rye yield have been carried in conditions of two representative fields with slopes sharply contrasted both in aspects and degrees. Rye biological productivity and weed infestation have been measured in elementary plots of 0.25 m2 with the following analysis the quality of the yield. In the same plot soil temperature and moisture have been measured by portable devices. Soil sampling was provided from three upper layers by drilling. The results of ray yield detailed mapping shown high differences both in average values and within-field variability on different slopes. In case of low-gradient slope (field 1) there is variability of ray yield from 39.4 to 44.8 dt/ha. In case of expressed slope (field 2) the same species of winter rye grown with the same technology has essentially lower yield and within-field variability from 20 to 29.6 dt/ha. The

  20. Drivers for spatial variability in agricultural soil organic carbon stocks in Germany

    Science.gov (United States)

    Vos, Cora; Don, Axel; Hobley, Eleanor; Prietz, Roland; Heidkamp, Arne; Freibauer, Annette

    2017-04-01

    Soil organic carbon is one of the largest components of the global carbon cycle. It has recently gained importance in global efforts to mitigate climate change through carbon sequestration. In order to find locations suitable for carbon sequestration, and estimate the sequestration potential, however, it is necessary to understand the factors influencing the high spatial variability of soil organic carbon stocks. Due to numerous interacting factors that influence its dynamics, soil organic carbon stocks are difficult to predict. In the course of the German Agricultural Soil Inventory over 2500 agricultural sites were sampled and their soil organic carbon stocks determined. Data relating to more than 200 potential drivers of SOC stocks were compiled from laboratory measurements, farmer questionnaires and climate stations. The aims of this study were to 1) give an overview of soil organic carbon stocks in Germany's agricultural soils, 2) to quantify and explain the influence of explanatory variables on soil organic carbon stocks. Two different machine learning algorithms were used to identify the most important variables and multiple regression models were used to explore the influence of those variables. Models for predicting carbon stocks in different depth increments between 0-100 cm were developed, explaining up to 62% (validation, 98% calibration) of total variance. Land-use, land-use history, clay content and electrical conductivity were main predictors in the topsoil, while bedrock material, relief and electrical conductivity governed the variability of subsoil carbon stocks. We found 32% of all soils to be deeply anthropogenically transformed. The influence of climate related variables was surprisingly small (≤5% of explained variance), while site variables explained a large share of soil carbon variability (46-100% of explained variance), in particular in the subsoil. Thus, the understanding of SOC dynamics at regional scale requires a thorough description

  1. Repeated morphine treatment influences operant and spatial learning differentially

    Institute of Scientific and Technical Information of China (English)

    Mei-Na WANG; Zhi-Fang DONG; Jun CAO; Lin XU

    2006-01-01

    Objective To investigate whether repeated morphine exposure or prolonged withdrawal could influence operant and spatial learning differentially. Methods Animals were chronically treated with morphine or subjected to morphine withdrawal. Then, they were subjected to two kinds of learning: operant conditioning and spatial learning.Results The acquisition of both simple appetitive and cued operant learning was impaired after repeated morphine treatment. Withdrawal for 5 weeks alleviated the impairments. Single morphine exposure disrupted the retrieval of operant memory but had no effect on rats after 5-week withdrawal. Contrarily, neither chronic morphine exposure nor 5-week withdrawal influenced spatial learning task of the Morris water maze. Nevertheless, the retrieval of spatial memory was impaired by repeated morphine exposure but not by 5-week withdrawal. Conclusion These observations suggest that repeated morphine exposure can influence different types of learning at different aspects, implicating that the formation of opiate addiction may usurp memory mechanisms differentially.

  2. Temporal and spatial variability of the sea surface salinity in the Nordic Seas

    Science.gov (United States)

    Furevik, Tore; Bentsen, Mats; Drange, Helge; Johannessen, Johnny A.; Korablev, Alexander

    2002-12-01

    In this paper, the temporal and spatial variability of the sea surface salinity (SSS) in the Nordic Seas is investigated. The data include a Russian hydrographical database for the Nordic Seas and daily to weekly observations of salinity at Ocean Weather Station Mike (OWSM) (located at 66°N, 2°E in the Norwegian Sea). In addition, output from a medium-resolution version of the Miami Isopycnic Coordinate Ocean Model (MICOM), forced with daily National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data, is used to complement the analysis of the temporal and spatial fields constructed from the observational data sets. The Nordic Seas show a strong seasonal variability in the vertical density stratification and the mixed layer (ML) depth, with a weak stratification and a several hundred meters deep ML during winter and a well-defined shallow ML confined to the upper few tens of meters during summer. The seasonal variability strongly influences the strength of the high-frequency variability and to what extent subsurface anomalies are isolated from the surface. High-frequency variability has been investigated in terms of standard deviation of daily SSS, calculated for the different months of the year. From observations at OWSM, typical winter values range from 0.03 to 0.04 psu and summer values range from 0.06 to 0.07 psu. Results from the model simulation show that highest variability is found in frontal areas and in areas with strong stratification and lowest variability in the less stratified areas in the central Norwegian Sea and south of Iceland. Investigation of the interannual variability over the last 50 years shows a marked freshening of the Atlantic Water in the Norwegian and Greenland Seas. Moreover, the strength of the southern sector of the Polar front, as defined by the 34.8-35.0 psu isohalines along the western boundary of the inflowing Atlantic Water, undergoes significant interannual variability

  3. Spatial variability and sources of ammonia in three European cities

    Science.gov (United States)

    Prevot, Andre S. H.; Elser, Miriam; El Haddad, Imad; Maasikmets, Marek; Bozzetti, Carlo; Robert, Wolf; Richter, Rene; Slowik, Jay; Teinemaa, Erik; Hueglin, Christoph; Baltensperger, Urs

    2017-04-01

    For the assessment of ammonia (NH3) effects on ecosystems and climate, one would ideally know the emission sources and also the spatial distributions. Agriculture is the largest global source of NH3. However traffic, especially gasoline vehicles, biomass burning or waste management can be significant in urban areas. Ambient NH3 measurements using cavity ring-down spectroscopy were performed online at high time resolution on a moving vehicle in three cities: Zurich (Switzerland), Tartu (Estonia) and Tallinn (Estonia). Initial tests showed that a regular inlet cannot be used. A heated line including an auxiliary flow was finally deployed to minimize NH3 adsorption onto the inlet walls. We will present the characterization of the response and recovery times of the measurement system which was used to deconvolve the true NH3 signal from the remaining adsorption-induced hysteresis. Parallel measurements with an Aerodyne aerosol mass spectrometer were used to correct the observed NH3 for the contribution of ammonium nitrate (NH4NO3) which completely evaporated to NH3 and nitric acid (HNO3) in the heated line at the chosen temperature, in contrast to ammonium sulfate. Finally, quantitative measurements of ambient NH3 are possible with sufficient time resolution to enable measurement of NH3 point or line sources with a mobile sampling platform. The NH3 analyzer and the aerosol mass spectrometer were complemented by an aethalometer to measure black carbon and various gas-phase analyzers to enable a complete characterization of the sources of air pollution, including the spatial distributions and the regional background concentrations and urban increments of all measured components. Although at all three locations similar urban increment levels of organic aerosols were attributed to biomass burning and traffic, traffic emissions clearly dominated the city enhancements of NH3, equivalent black carbon (eBC) and carbon dioxide (CO2). Concentration gradients in areas strongly

  4. Temporal, spatial, and environmental influences on the demographics of grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Schwartz, Charles C.; Haroldson, Mark A.; White, Gary C.; Harris, Richard B.; Cherry, Steve; Keating, Kim A.; Moody, Dave; Servheen, Christopher

    2006-01-01

    During the past 2 decades, the grizzly bear (Ursus arctos) population in the Greater Yellowstone Ecosystem (GYE) has increased in numbers and expanded in range. Understanding temporal, environmental, and spatial variables responsible for this change is useful in evaluating what likely influenced grizzly bear demographics in the GYE and where future management efforts might benefit conservation and management. We used recent data from radio-marked bears to estimate reproduction (1983–2002) and survival (1983–2001); these we combined into models to evaluate demographic vigor (lambda [λ]). We explored the influence of an array of individual, temporal, and spatial covariates on demographic vigor.

  5. Spatial and temporal variability of biophysical variables in Southwestern France from airborne L-band radiometry

    Directory of Open Access Journals (Sweden)

    E. Zakharova

    2012-01-01

    tended to increase the CAROLS SSM spatial variability, up to 0.10 m3 m−3. Also, the grid cells characterised by a high vegetation cover heterogeneity presented higher standard deviation values, for both SSM and VOD.

  6. Spatial and temporal variability of biophysical variables in southwestern France from airborne L-band radiometry

    Directory of Open Access Journals (Sweden)

    E. Zakharova

    2012-06-01

    ISBA-A-gs grid cells tended to increase the CAROLS SSM spatial variability, up to 0.10 m3 m−3. Also, the grid cells characterised by a high vegetation cover heterogeneity presented higher standard deviation values, for both SSM and VOD.

  7. Spatial variability of the topsoil organic carbon in the Moso bamboo forests of southern China in association with soil properties.

    Science.gov (United States)

    Zhang, Houxi; Zhuang, Shunyao; Qian, Haiyan; Wang, Feng; Ji, Haibao

    2015-01-01

    Understanding the spatial variability of soil organic carbon (SOC) must be enhanced to improve sampling design and to develop soil management strategies in terrestrial ecosystems. Moso bamboo (Phyllostachys pubescens Mazel ex Houz.) forests have a high SOC storage potential; however, they also vary significantly spatially. This study investigated the spatial variability of SOC (0-20 cm) in association with other soil properties and with spatial variables in the Moso bamboo forests of Jian'ou City, which is a typical bamboo hometown in China. 209 soil samples were collected from Moso bamboo stands and then analyzed for SOC, bulk density (BD), pH, cation exchange capacity (CEC), and gravel content (GC) based on spatial distribution. The spatial variability of SOC was then examined using geostatistics. A Kriging map was produced through ordinary interpolation and required sample numbers were calculated by classical and Kriging methods. An aggregated boosted tree (ABT) analysis was also conducted. A semivariogram analysis indicated that ln(SOC) was best fitted with an exponential model and that it exhibited moderate spatial dependence, with a nugget/sill ratio of 0.462. SOC was significantly and linearly correlated with BD (r = -0.373**), pH (r = -0.429**), GC (r = -0.163*), CEC (r = 0.263**), and elevation (r = 0.192**). Moreover, the Kriging method requires fewer samples than the classical method given an expected standard error level as per a variance analysis. ABT analysis indicated that the physicochemical variables of soil affected SOC variation more significantly than spatial variables did, thus suggesting that the SOC in Moso bamboo forests can be strongly influenced by management practices. Thus, this study provides valuable information in relation to sampling strategy and insight into the potential of adjustments in agronomic measure, such as in fertilization for Moso bamboo production.

  8. Map Analysis and Spatial Statistic: Assessment of Spatial Variability of Agriculture Land Conversion at Urban Fringe Area of Yogyakarta

    Science.gov (United States)

    Susilo, Bowo

    2016-11-01

    Urban development has brought various effects, one of which was the marginalization of the agricultural sector. Agricultural land is gradually converted to other type of land uses which considered more profitable. Conversion of agricultural land cannot be avoided but it should be controlled. Early identification on spatial distribution and intensity of agricultural land conversion as well as its related factor is necessary. Objective of the research were (1) to assess the spatial variability of agricultural land conversion, (2) to identify factors that affecting the spatial variability of agricultural land conversion. Research was conducted at urban fringe area of Yogyakarta. Spatial variability of agricultural land conversion was analysed using an index called Relative Conversion Index (RCI). Combined of map analysis and spatial statistical were used to determine the center of agricultural land conversion. Simple regression analysis was used to determine the factors associated with the conversion of agricultural land. The result shows that intensity of agricultural land conversion in the study area varies spatially as well as temporally. Intensity of agricultural land conversion in the period 1993-2000, involves three categories which are high, moderate and low. In the period of 2000-2007, the intensity of agricultural land conversion involves two categories which are high and low. Spatial variability of agricultural land conversion in the study area has a significant correlation with three factors: population growth, fragmentation of agricultural land and distance of agricultural land to the city

  9. Spatial variability of total carbon and soil organic carbon in agricultural soils in Baranja region, Croatia

    Science.gov (United States)

    Bogunović, Igor; Trevisani, Sebastiano; Pereira, Paulo; Šeput, Miranda

    2017-04-01

    Climate change is expected to have an important influence on the crop production in agricultural regions. Soil carbon represents an important soil property that contributes to mitigate the negative influence of climate change on intensive cropped areas. Based on 5063 soil samples sampled from soil top layer (0-30 cm) we studied the spatial distribution of total carbon (TC) and soil organic carbon (SOC) content in various soil types (Anthrosols, Cambisols, Chernozems, Fluvisols, Gleysols, Luvisols) in Baranja region, Croatia. TC concentrations ranged from 2.10 to 66.15 mg/kg (with a mean of 16.31 mg/kg). SOC concentrations ranged from 1.86 to 58.00 mg/kg (with a mean of 13.35 mg/kg). TC and SOC showed moderate heterogeneity with coefficient of variation (CV) of 51.3% and 33.8%, respectively. Average concentrations of soil TC vary in function of soil types in the following decreasing order: Anthrosols (20.9 mg/kg) > Gleysols (19.3 mg/kg) > Fluvisols (15.6 mg/kg) > Chernozems (14.2 mg/kg) > Luvisols (12.6 mg/kg) > Cambisols (11.1 mg/kg), while SOC concentrations follow next order: Gleysols (15.4 mg/kg) > Fluvisols (13.2 mg/kg) = Anthrosols (13.2 mg/kg) > Chernozems (12.6 mg/kg) > Luvisols (11.4 mg/kg) > Cambisols (10.5 mg/kg). Performed geostatistical analysis of TC and SOC; both the experimental variograms as well as the interpolated maps reveal quite different spatial patterns of the two studied soil properties. The analysis of the spatial variability and of the spatial patterns of the produced maps show that SOC is likely influenced by antrophic processes. Spatial variability of SOC indicates soil health deterioration on an important significant portion of the studied area; this suggests the need for future adoption of environmentally friendly soil management in the Baranja region. Regional maps of TC and SOC provide quantitative information for regional planning and environmental monitoring and protection purposes.

  10. The active liquid Earth - importance of temporal and spatial variability

    Science.gov (United States)

    Arheimer, Berit

    2016-04-01

    The Planet Earth is indeed liquid and active - 71 percent of its surface is water-covered and this water never rests. Thanks to the water cycle, our planet's water supply is constantly moving from one place to another and from one form to another. Only 2.5% of the water is freshwater and it exists in the air as water vapor; it hits the ground as rain and snow; it flows on the surface from higher to lower altitudes in rivers, lakes, and glaciers; and it flows in the ground in soil, aquifers, and in all living organisms until it reaches the sea. On its way over the Earth's crust, some returns quickly to vapor again, while some is trapped and exposed to many "fill and spill" situations for a long journey. The variability in the water balance is crucial for hydrological understanding and modelling. The water cycle may appear simple, but magnitudes and rates in fluxes are very different from one place to another, resulting from variable drivers such as solar energy, precipitation and gravity in co-evolution with geology, soil, vegetation and fauna. The historical evolution, the temporal fluxes and diversity in space continue to fascinate hydrological scientists. Specific physical processes may be well known, but their boundary conditions, interactions and rate often remain unknown at a specific site and are difficult to monitor in nature. This results in mysterious features where trends in drivers do not match runoff, like the Sahelian Paradox or discharge to the Arctic Ocean. Humans have always interfered with the water cycle and engineering is fundamental for water regulation and re-allocation. Some 80% of the river flow from the northern part of the Earth is affected by fragmentation of the river channels by dams. In water management, there is always a tradeoff between upstream and downstream activities, not only regarding total water quantities but also for temporal patterns and water quality aspects. Sharing a water resource can generate conflicts but geopolitical

  11. Controls on the temporal and spatial variability of soil moisture in a mountainous landscape: the signature of snow and complex terrain

    Directory of Open Access Journals (Sweden)

    J. P. McNamara

    2009-07-01

    Full Text Available The controls on the spatial distribution of soil moisture include static and dynamic variables. The superposition of static and dynamic controls can lead to different soil moisture patterns for a given catchment during wetting, draining, and drying periods. These relationships can be further complicated in snow-dominated mountain regions where soil water input by precipitation is largely dictated by the spatial variability of snow accumulation and melt. In this study, we assess controls on spatial and temporal soil moisture variability in a small (0.02 km2, snow-dominated, semi-arid catchment by evaluating spatial correlations between soil moisture and site characteristics through different hydrologic seasons. We assess the relative importance of snow with respect to other catchment properties on the spatial variability of soil moisture and track the temporal persistence of those controls. Spatial distribution of snow, distance from divide, soil texture, and soil depth exerted significant control on the spatial variability of moisture content throughout most of the hydrologic year. These relationships were strongest during the wettest period and degraded during the dry period. As the catchment cycled through wet and dry periods, the relative spatial variability of soil moisture tended to remain unchanged. We suggest that the static properties in complex terrain (slope, aspect, soils impose first order controls on the spatial variability of snow and resulting soil moisture patterns, and that the interaction of dynamic (timing of water input and static influences propagate that relative constant spatial variability through most of the hydrologic year. The results demonstrate that snow exerts significant influence on how water is retained within mid-elevation semi-arid catchments and suggest that reductions in annual snowpacks associated with changing climate regimes may strongly influence spatial and temporal soil moisture patterns and

  12. Spatial variability of soil structure and its impact on transport processes and some associated land qualities.

    NARCIS (Netherlands)

    Finke, P.A.

    1992-01-01

    This thesis treats the impact of soil spatial variability on spatial variability of simulated land qualities. A sequence of procedures that were done to determine this impact is described in chapters 2 and 3. The subchapters correspond to seven manuscripts that either have appeared in or have been s

  13. Determinants of spatial variability of methane emissions from wet grasslands on peat soil

    NARCIS (Netherlands)

    Pol-Van Dasselaar, van den A.; Beusichem, van M.L.; Oenema, O.

    1999-01-01

    Methane (CH4) emissions from soils, representing the consequence of CH4 production, CH4 consumption and CH4 transport, are poorly characterised and show a large spatial variability. This study aimed to assess the determinants of field-scale spatial variability of CH4 emissions from wet grasslands on

  14. Spatial and temporal variability in recruitment of intertidal mussels ...

    African Journals Online (AJOL)

    ... in the temporal and spatial dynamics of mussel populations (Griffiths 1981; Crawford & ..... recruitment intensity (ANOYA, F ~ 9.357, df58, P < 0.01). (a) Regional ...... rocky shores: the role of geographic variation and wave action. J. Blogeogr.

  15. Spatial Variability of Soil Properties and Rice Yield Along Two Catenas in Southeast China

    Institute of Scientific and Technical Information of China (English)

    B. R(U)TH; B. LENNARTZ

    2008-01-01

    In the light of an increasing demand for staple food, especially rice, in southeast China, investigations on the specific site potential expressed as the relationship between soil and crop yield parameters gain increasing importance. Soil texture and several soil chemical parameters as well as plant properties such as crop height, biomass and grain yield were investigated along two terraced catenas with contrasting soil textures cropped with wet rice. We were aiming at identifying correlative relationships between soil and crop properties. Data were analyzed both statistically and geostatistically on the basis of semivariograms. Statistical analysis indicated a significant influence of the relief position on the spatial distribution of soil texture, total carbon and total nitrogen contents. Significant correlations were found for the catena located in a sandstone area (Catena A) between rice yield and silt as well as total nitrogen content. Corresponding relationships were not detectable for paddy fields that developed from Quaternary clays (Catena B). As suggested by the nugget to sill ratio,spatial variability of soil texture, total carbon and nitrogen was mainly controlled by intrinsic factors, which might be attributed to the erosional transport of fine soil constituents, indicating the importance of the relief position and slope in soil development even in landscapes that are terraced. The crop parameters exhibited short ranges of influence and about one third of their variability was unexplained. Comparable ranges of selected crop and soil parameters, found only for Catena A, are indicative of close spatial interactions between rice yield and soil features. Our findings show that especially in sandstone-dominated areas, a site-specific management can contribute to an environmentally safe rice production increase.

  16. Influence of Spinning Variable on the FR Properties of Yarns

    Institute of Scientific and Technical Information of China (English)

    Eric Oyondi Nganyi; YU Chong-wen(郁崇文)

    2003-01-01

    Broadly considered, spinning variables influences the properties of yarns. However there is scant information on the influence on the fire retardancy (FR) properties. The present work aims to establish the influence of the spinning method, twist, and fibre distribution in a blended yarn, on the FR properties of the yarn.

  17. Characteristics of Spatial Structural Patterns and Temporal Variability of Annual Precipitation in Ningxia

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the characteristics of the spatial structural patterns and temporal variability of annual precipitation in Ningxia.[Method] Using rotated empirical orthogonal function,the precipitation concentration index,wavelet analysis and Mann-Kendall rank statistic method,the characteristics of precipitation on the spatial-temporal variability and trend were analyzed by the monthly precipitation series in Ningxia during 1951-2008.[Result] In Ningxia,the spatial structural patterns of a...

  18. Testing in a Random Effects Panel Data Model with Spatially Correlated Error Components and Spatially Lagged Dependent Variables

    Directory of Open Access Journals (Sweden)

    Ming He

    2015-11-01

    Full Text Available We propose a random effects panel data model with both spatially correlated error components and spatially lagged dependent variables. We focus on diagnostic testing procedures and derive Lagrange multiplier (LM test statistics for a variety of hypotheses within this model. We first construct the joint LM test for both the individual random effects and the two spatial effects (spatial error correlation and spatial lag dependence. We then provide LM tests for the individual random effects and for the two spatial effects separately. In addition, in order to guard against local model misspecification, we derive locally adjusted (robust LM tests based on the Bera and Yoon principle (Bera and Yoon, 1993. We conduct a small Monte Carlo simulation to show the good finite sample performances of these LM test statistics and revisit the cigarette demand example in Baltagi and Levin (1992 to illustrate our testing procedures.

  19. What variables can influence clinical reasoning?

    Directory of Open Access Journals (Sweden)

    Vahid Ashoorion

    2012-01-01

    Full Text Available Background: Clinical reasoning is one of the most important competencies that a physician should achieve. Many medical schools and licensing bodies try to predict it based on some general measures such as critical thinking, personality, and emotional intelligence. This study aimed at providing a model to design the relationship between the constructs. Materials and Methods: Sixty-nine medical students participated in this study. A battery test devised that consist four parts: Clinical reasoning measures, personality NEO inventory, Bar-On EQ inventory, and California critical thinking questionnaire. All participants completed the tests. Correlation and multiple regression analysis consumed for data analysis. Results: There is low to moderate correlations between clinical reasoning and other variables. Emotional intelligence is the only variable that contributes clinical reasoning construct (r=0.17-0.34 (R 2 chnage = 0.46, P Value = 0.000. Conclusion: Although, clinical reasoning can be considered as a kind of thinking, no significant correlation detected between it and other constructs. Emotional intelligence (and its subscales is the only variable that can be used for clinical reasoning prediction.

  20. What variables can influence clinical reasoning?

    Science.gov (United States)

    Ashoorion, Vahid; Liaghatdar, Mohammad Javad; Adibi, Peyman

    2012-12-01

    Clinical reasoning is one of the most important competencies that a physician should achieve. Many medical schools and licensing bodies try to predict it based on some general measures such as critical thinking, personality, and emotional intelligence. This study aimed at providing a model to design the relationship between the constructs. Sixty-nine medical students participated in this study. A battery test devised that consist four parts: Clinical reasoning measures, personality NEO inventory, Bar-On EQ inventory, and California critical thinking questionnaire. All participants completed the tests. Correlation and multiple regression analysis consumed for data analysis. There is low to moderate correlations between clinical reasoning and other variables. Emotional intelligence is the only variable that contributes clinical reasoning construct (r=0.17-0.34) (R(2) chnage = 0.46, P Value = 0.000). Although, clinical reasoning can be considered as a kind of thinking, no significant correlation detected between it and other constructs. Emotional intelligence (and its subscales) is the only variable that can be used for clinical reasoning prediction.

  1. Vegetation and Variable Snow Cover: Spatial Patterns of Shrubland, and Grassland Snow

    Science.gov (United States)

    Liston, G. E.; Hiemstra, C. A.; Strack, J. E.

    2003-12-01

    Regions that experience long winters with snowfall and high winds frequently exhibit heterogeneous snow distribution patterns that arise from interactions among snow, wind, topography, and vegetation. Variable snow cover and resultant heterogeneities in albedo and growing season length can affect local weather patterns and energy budgets, and produce spatially co-variable ecosystem properties. While snow influences local atmospheric processes and ecosystems, an important and underappreciated feedback exists between vegetation and snow cover. Plant size, canopy density, and rigidity determine how much snow accumulates on the lee side of individual plants (e.g., shrubland vs. grassland). In addition, the canopy can also influence how much energy reaches the snowpack, thereby hindering or accelerating snowmelt. An overhanging canopy reduces incoming solar radiation while providing a source of turbulent sensible and longwave radiative energy. Historically, most snow vegetation interaction studies have been limited to areas that experience an abundance of snow (e.g., mountainous areas) where trees have a large influence on seasonal snow-cover. In contrast, snow cover patterns associated with shrublands and grasslands have received little attention, despite covering vast expanses (53%) of the seasonally snow-covered globe. In this study, snow depths were measured every two weeks from December through March in a small, 0.25 km2 study area located in North Park, Colorado. The study area possesses little topographic relief and consists of shrub patches, dominated by greasewood (Sarcobatus vermiculatus) and sagebrush (Artemisia tridentata), embedded in a matrix of graminoids (sedges, rushes, and grasses). Snow cover patterns and spatial statistics were dramatically different in graminoid-dominated cover compared with shrub cover. The graminoid snow cover was thinner, less variable, and more ephemeral than the shrub snow pack. Snow was readily eroded by wind from graminoid

  2. Implied motion language can influence visual spatial memory.

    Science.gov (United States)

    Vinson, David W; Engelen, Jan; Zwaan, Rolf A; Matlock, Teenie; Dale, Rick

    2017-03-15

    How do language and vision interact? Specifically, what impact can language have on visual processing, especially related to spatial memory? What are typically considered errors in visual processing, such as remembering the location of an object to be farther along its motion trajectory than it actually is, can be explained as perceptual achievements that are driven by our ability to anticipate future events. In two experiments, we tested whether the prior presentation of motion language influences visual spatial memory in ways that afford greater perceptual prediction. Experiment 1 showed that motion language influenced judgments for the spatial memory of an object beyond the known effects of implied motion present in the image itself. Experiment 2 replicated this finding. Our findings support a theory of perception as prediction.

  3. Spatial variability and prediction modeling of groundwater arsenic distributions in the shallowest alluvial aquifers in Bangladesh

    OpenAIRE

    Shamsudduha, M.

    2007-01-01

    Elevated arsenic in groundwater is the greatest environmental problem in Bangladesh. Spatial variability of arsenic in groundwater has been examined by semivariogram analysis that revealed high degree of small-scale spatial variability in alluvial aquifers. Small-scale variability of arsenic concentrations, indicated by high "nugget" values in semivariograms, is associated with heterogeneity in local-scale geology and geochemical processes. In unsampled locations, arsenic concentrations have ...

  4. Do existing classification systems capture mountain snowpack heterogeneity? Accounting for spatial variability in a changing environment

    Science.gov (United States)

    Tennant, C.; Godsey, S.; Harpold, A. A.; Link, T. E.; Rajagopal, S.; Larsen, L.

    2016-12-01

    Spatial patterns of snow accumulation and melt control water and nutrient fluxes from mountain landscapes and determine the dynamics of resource availability for nearby human and ecological communities. Because seasonal snowpack is sensitive to changes in regional climate, there is a growing need for a snowpack classification system that (1) recognizes salient processes, (2) captures the variance of the system, (3) recognizes temporal and/or spatial change, and (4) has application to predicting snowmelt runoff regimes. Previous classification systems have focused on textural and stratigraphic snow characteristics or climatological observations to map broad geographic classes (e.g. maritime, continental, ephemeral, etc.). While these approaches have revealed general patterns, they may not capture the spatial heterogeneity of snowpack characteristics that are common across high relief terrain. Here, we use 1 km resolution gridded outputs from a physically based, spatially-distributed energy- and mass-balance snow model (SNODAS) to produce a snow classification system for the western U.S. and Great Plains. To meet the outlined criterion, we initially explored the ability of a large number of metrics (13) to characterize the amount, timing, and melt-rate of snowpack. Principal components analysis and pairwise correlations were used to identify a subset of metrics (6) that captured the variance of the system but also contributed unique information. K-means was used to delineate 12 process-based groups that reveal both climatic and orographic influences on snowpack accumulation, timing, and melt rate. The important effects of elevation-mediated processes in our classification system suggest a greater spatial diversity in snowpack patterns than suggested by previous characterizations (e.g. maritime-to-continental). Application of the system from the early 2000's to present reveals that interannual temporal and spatial variability have been greatest in the Columbia Plateau

  5. Spatial variability of the trends in climatic variables across China during 1961-2010

    Science.gov (United States)

    Yang, Hanbo; Yang, Dawen; Hu, Qingfang; Lv, Huafang

    2015-05-01

    Distribution of meteorological stations is not uniform in many regions of the world, especially in developing countries like China. To eliminate the effect of uneven stations, this study produced a data set of areal average precipitation, air temperature, solar radiation, and wind speed from 736 meteorological station observations during 1961-2010 using an inverse-distance weighted technique. Based on the data set, this study detected the trends in climatic variables. Precipitation has a slight but no significant ( p = 0.78) trend for the whole of China and has a significant increase trend in northwest China. Surface air temperature has a significant ( p < 0.001) accelerating warming trend of 0.032 °C/a for the whole of China, and spatially larger in northern China than that in southern China. Solar radiation has a significant ( p < 0.001) dimming trend of -0.14 W/(m2 · a) for the whole of China, and the largest dimming trend appears in eastern China, the possible cause for which is a high-aerosol concentration. Surface wind speed has a significant ( p < 0.001) stilling trend of -0.012 m/(s·a) for the whole of China, the causes for which were speculated the changes in atmospheric circulation and surface roughness, as well as increases in aerosol concentration and the decrease in the south-north temperature gradient in China. In addition, three large-scale instrument replacements increase uncertainties of the trend analysis.

  6. Spatial variability of enthalpy in broiler house during the heating phase

    Directory of Open Access Journals (Sweden)

    Patrícia F. P. Ferraz

    2016-06-01

    Full Text Available ABSTRACT The thermal environment inside a broiler house has a great influence on animal welfare and productivity during the production phase. Enthalpy is a thermodynamic property that has been proposed to evaluate the internal broiler house environment, for being an indicator of the amount of energy contained in a mixture of water vapor and dry air. Therefore, this study aimed to characterize the spatial variability of enthalpy in a broiler house during the heating phase using geostatistics. The experiment was conducted in the spring season, in a commercial broiler house with heating system consisting of two furnaces that heat the air indirectly, in the first 14 days of the birds' life. It was possible to characterize enthalpy variability using geostatistical techniques, which allowed observing the spatial dependence through kriging maps. The analyses of the maps allowed observing problems in the heating system in regions inside the broiler house, which may cause a thermal discomfort to the animals besides productive and economic losses.

  7. Spatial and Temporal Variability of Winter Accumulation on Taku Glacier, Southeast Alaska, between 2012 and 2015

    Science.gov (United States)

    Smith, B.; Campbell, S. W.; Hollander, J.; Slavin, B. V.; Wolf, J.; Wilner, J.; Moore, T.

    2015-12-01

    Glacier mass balance is an integral part of understanding a glacier's health and dynamics. A key component of determining mass balance is winter accumulation which is traditionally estimated by digging and measuring snow densities from within snow pits. However, this method represents a labor-intensive point measurement which may not fully capture spatial variability of accumulation. To more efficiently estimate spatial variability of winter accumulation across Taku Glacier and its main tributaries in southeastern Alaska in 2015, we used a 400 MHz Ground Penetrating Radar (GPR) Common Offset (CO) surveys along centerline transects which were also collected during a 2012 study. We used common midpoint (CMP) surveys, migration, snow pits, and probing to improve depth estimates and provide ground truth of winter accumulation depth measurements from CO surveys. We determined that the winter accumulation was significantly lower in 2015 than in 2012. However, gradients in accumulation versus elevation were consistent from year to year along centerline transects. We suggest that this low accumulation may be influencing the recent two year stall of Taku Glacier which has exhibited an advancing terminus for nearly a century. We recommend that further studies be conducted to extend the reach of this dataset beyond 2 years. This data would be invaluable to future models and mass balance studies on the Icefield and may capture key components that suggest a tipping point from advance to retreat of Taku Glacier.

  8. A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes

    Science.gov (United States)

    Shanafield, Margaret; Niswonger, Richard G.; Prudic, David E.; Pohll, Greg; Susfalk, Richard; Panday, Sorab

    2014-01-01

    Infiltration along ephemeral channels plays an important role in groundwater recharge in arid regions. A model is presented for estimating spatial variability of seepage due to streambed heterogeneity along channels based on measurements of streamflow-front velocities in initially dry channels. The diffusion-wave approximation to the Saint-Venant equations, coupled with Philip's equation for infiltration, is connected to the groundwater model MODFLOW and is calibrated by adjusting the saturated hydraulic conductivity of the channel bed. The model is applied to portions of two large water delivery canals, which serve as proxies for natural ephemeral streams. Estimated seepage rates compare well with previously published values. Possible sources of error stem from uncertainty in Manning's roughness coefficients, soil hydraulic properties and channel geometry. Model performance would be most improved through more frequent longitudinal estimates of channel geometry and thalweg elevation, and with measurements of stream stage over time to constrain wave timing and shape. This model is a potentially valuable tool for estimating spatial variability in longitudinal seepage along intermittent and ephemeral channels over a wide range of bed slopes and the influence of seepage rates on groundwater levels.

  9. Investigation of the seasonal spatial variability of the Caspian Sea level by satellite altimetry.

    Science.gov (United States)

    Safarov, Elnur; Mammadov, Ramiz; Cretaux, Jean-Francois; Arsen, Adalbert; Safarov, Said; Amrahov, Elvin

    2016-07-01

    Sea level fluctuations are among the most outstanding and debated issues of the Caspian Sea. Precipitation, underground water and river input are consistent parts of the inflow of the Caspian Sea water balance. The river input is also considered to be the main driver of the seasonal level changes of the Caspian Sea. Sufficiently large amount of this input is provided by the Volga. Although there is a good network of sea level stations covering the coastline of the sea, these facilities are not capable to reflect the sea level variations over the all surface. Meanwhile, the Caspian Sea is well observed by satellites Jason 1, Jason 2 and ENVISAT. Altimetric data taken from these satellites covers the surface of the sea much better than the data from the in-situ network stations. In this paper we investigate the spatial variability of the sea level that could provide more insight into the influence of river input (especially the Volga river), precipitation and other hydro-meteorological parameters on the Caspian Sea level.The altimetric data was averaged per every 10 square kilometers through all the tracks by means of the pre-prepared program made especially for this work. Also new maps of seasonal spatial variability of amplitude and phase of the annual signal of the Caspian Sea level for each investigated satellite were created by employing ARCGIS software. Moreover, these peaks of sea level amplitude and phase of annual signal results were comparatively analyzed with the corresponding river discharge of the Volga.

  10. Spatial and temporal variability of soil electrical conductivity related to soil moisture

    Directory of Open Access Journals (Sweden)

    José Paulo Molin

    2013-02-01

    Full Text Available Soil electrical conductivity (ECa is a soil quality indicator associated to attributes interesting to site-specific soil management such as soil moisture and texture. Soil ECa provides information that helps guide soil management decisions, so we performed spatial evaluation of soil moisture in two experimental fields in two consecutive years and modeled its influence on soil ECa. Soil ECa, moisture and clay content were evaluated by statistical, geostatistical and regression analyses. Semivariogram models, adjusted for soil moisture, had strong spatial dependence, but the relationship between soil moisture and soil ECa was obtained only in one of the experimental fields, where soil moisture and clay content range was higher. In this same field, coefficients of determinations between soil moisture and clay content were above 0.70. In the second field, the low soil moisture and clay content range explain the absence of a relationship between soil ECa and soil moisture. Data repetition over the years, suggested that ECa is a qualitative indicator in areas with high spatial variability in soil texture.

  11. Spatial Variability Analysis of Within-Field Winter Wheat Nitrogen and Grain Quality Using Canopy Fluorescence Sensor Measurements

    Directory of Open Access Journals (Sweden)

    Xiaoyu Song

    2017-03-01

    Full Text Available Wheat grain protein content (GPC is a key component when evaluating wheat nutrition. It is also important to determine wheat GPC before harvest for agricultural and food process enterprises in order to optimize the wheat grading process. Wheat GPC across a field is spatially variable due to the inherent variability of soil properties and position in the landscape. The objectives of this field study were: (i to assess the spatial and temporal variability of wheat nitrogen (N attributes related to the grain quality of winter wheat production through canopy fluorescence sensor measurements; and (ii to examine the influence of spatial variability of soil N and moisture across different growth stages on the wheat grain quality. A geostatistical approach was used to analyze data collected from 110 georeferenced locations. In particular, Ordinary Kriging Analysis (OKA was used to produce maps of wheat GPC, GPC yield, and wheat canopy fluorescence parameters, including simple florescence ratio and Nitrogen Balance Indices (NBI. Soil Nitrate-Nitrogen (NO3-N content and soil Time Domain Reflectometry (TDR value in the study field were also interpolated through the OKA method. The fluorescence parameter maps, soil NO3-N and soil TDR maps obtained from the OKA output were compared with the wheat GPC and GPC yield maps in order to assess their relationships. The results of this study indicate that the NBI spatial variability map in the late stage of wheat growth can be used to distinguish areas that produce higher GPC.

  12. Controls on the temporal and spatial variability of soil moisture in a mountainous landscape: the signatures of snow and complex terrain

    Directory of Open Access Journals (Sweden)

    C. J. Williams

    2008-07-01

    Full Text Available The controls on the spatial distribution of soil moisture include static and dynamic variables. The superposition of static and dynamic controls can lead to different soil moisture patterns for a given catchment during wetting, draining, and drying periods. These relationships can be further complicated in snow-dominated mountain regions where soil water input by precipitation is largely dictated by the spatial variability of snow accumulation and melt. In this study, we assess controls on spatial and temporal soil moisture variability in a small (0.02 km2, snow-dominated, semi-arid catchment by evaluating spatial correlations between soil moisture and site characteristics through different hydrologic seasons. We assess the relative importance of snow with respect to other catchment properties on the spatial variability of soil moisture and track the temporal persistence of those controls. Spatial distribution of snow, distance from divide, soil texture, and soil depth exerted significant control on the spatial variability of moisture content throughout most of the hydrologic year. These relationships were strongest during the wettest period and degraded during the dry period. As the catchment cycled through wet and dry periods, the relative spatial variability of soil moisture tended to remain unchanged. We suggest that the static properties in complex terrain (slope, aspect, soils impose first order controls on the spatial variability of snow and consequent soil moisture, and that the interaction of dynamic (timing of water input and static properties propagate that relative constant spatial variability through the hydrologic year. The results demonstrate snow exerts significant influence on how water is retained within mid-elevation semi-arid catchments throughout the year and infer that reductions in annual snowpacks associated with changing climate regimes may strongly influence spatial and temporal soil moisture patterns and

  13. Spatial variability of heating profiles in windrowed poultry litter

    Science.gov (United States)

    In-house windrow composting of broiler litter has been suggested as a means to reduce microbial populations between flocks. Published time-temperature goals are used to determine the success of the composting process for microbial reductions. Spatial and temporal density of temperature measurement ...

  14. Head lice prevalence among households in Norway: importance of spatial variables and individual and household characteristics.

    Science.gov (United States)

    Rukke, Bjørn Arne; Birkemoe, Tone; Soleng, Arnulf; Lindstedt, Heidi Heggen; Ottesen, Preben

    2011-09-01

    Head lice prevalence varies greatly between and within countries, and more knowledge is needed to approach causes of this variation. In the present study, we investigated head lice prevalence among elementary school students and their households in relation to individual and household characteristics as well as spatial variables. The investigation included households from 5 geographically separated municipalities. Present infestations among household members as well as previous infestations in the household were reported in a questionnaire. In elementary school students prevalence was low (1·63%), but more than one-third of the households (36·43%) had previously experienced pediculosis. Prevalence was higher in elementary school students than in other household members, and highest in third-grade children. Prevalence was also influenced by the school attended, which suggested that interactions between children in the same school are important for head lice transmission. Previous occurrence of head lice in homes also increased the risk of present infestation. Prevalence of previous infestations was higher in households with more children and in more densely populated municipalities, indicating that the density of hosts or groups of hosts influences transmission rates. These results demonstrate that information of hosts' spatial distribution as well as household and individual characteristics is needed to better understand head lice population dynamics.

  15. Small-Scale Spatial Variability of Soil Nutrients and Vegetation Properties in Semi-Arid Northern China

    Institute of Scientific and Technical Information of China (English)

    CHEN Fu-Sheng; ZENG De-Hui; HE Xing-Yuan

    2006-01-01

    A field experiment was conducted at Kezuohouqi County, Inner Mongolia Autonomous Region of China, which was located on the southeastern edge of the Horqin Sandy Land, to study the spatial variability of soil nutrients for a smallscale, nutrient-poor, sandy site in a semi-arid region of northern China; to investigate whether or not there were "islands of fertility" at the experimental site; and to determine the key nutrient elements that sustained ecosystem stability. Results obtained from geostatistical analysis indicated that the spatial distribution pattern of soil total nitrogen (STN) was far different from those of soil organic matter (SOM), total phosphorus (STP), and total potassium (STK). Compared to SOM, STP, and STK, STN had a lower structural heterogeneity ratio and a longer range, while other elements were all similar. In addition, STN had an isotropic spatial structure, whereas the others had an anisotropic spatial structure.The spatial structure patterns of herbage species, cover, and height also differed, indicating that spatial variability was subjected to different ecological factors. Differences in the spatial variability patterns among soil nutrients and vegetation properties showed that soil nutrients for a small-scale were not the primary limiting factors that influenced herbage spatial distribution patterns. Incorporating spatial distribution patterns of tree species, namely, Pinus sylvestris var. mongolica Litv. and shrub Lespedeza bicolor Turcz. in a research plot and using fractal dimension, SOM, STP, and STK were shown to contribute to the "islands of fertility" phenomenon, however STN was not, possibly meaning that nitrogen was a key limiting element. Therefore, during restoration of similar ecosystems more attention should be given to soil nitrogen.

  16. Variables that influence junior secondary school students‟ attitude ...

    African Journals Online (AJOL)

    Variables that influence junior secondary school students‟ attitude to agricultural ... and cluster) sampling techniques was employed to select a sample of 254 students. ... It was recommended that efforts be geared towards implementation of ...

  17. Relative Influence Of Sociodemographic Variables On Oral Health ...

    African Journals Online (AJOL)

    Relative Influence Of Sociodemographic Variables On Oral Health And Habits Of Some Nigerian School Children. ... The pupils were from two different socioeconomic strata of the society and their ages ranged between 7 and 16 years.

  18. The Influence of Independent and Intervening Variables on Adoption ...

    African Journals Online (AJOL)

    and intervening variables in determining the adoption behaviour of recommended maize varieties ... in time from 5% percent of the population ... be investigated first followed by the influence ...... Macmillan Publishing Co., Inc. New York.

  19. Consistent patterns of spatial variability between NE Atlantic and Mediterraneanrocky shores

    NARCIS (Netherlands)

    dal Bello, M.; Leclerc, J.-C.; Benedetti-Cecchi, L.; Hummel, H.

    2016-01-01

    Examining how variability in population abundance and distribution is allotted among different spatial scales can inform of processes that are likely to generate that variability. Results of studies dealing with scale issues in marine benthic communities suggest that variability is concentrated at s

  20. Indian Summer Monsoon Rainfall: Implications of Contrasting Trends in the Spatial Variability of Means and Extremes.

    Directory of Open Access Journals (Sweden)

    Subimal Ghosh

    Full Text Available India's agricultural output, economy, and societal well-being are strappingly dependent on the stability of summer monsoon rainfall, its variability and extremes. Spatial aggregate of intensity and frequency of extreme rainfall events over Central India are significantly increasing, while at local scale they are spatially non-uniform with increasing spatial variability. The reasons behind such increase in spatial variability of extremes are poorly understood and the trends in mean monsoon rainfall have been greatly overlooked. Here, by using multi-decadal gridded daily rainfall data over entire India, we show that the trend in spatial variability of mean monsoon rainfall is decreasing as exactly opposite to that of extremes. The spatial variability of extremes is attributed to the spatial variability of the convective rainfall component. Contrarily, the decrease in spatial variability of the mean rainfall over India poses a pertinent research question on the applicability of large scale inter-basin water transfer by river inter-linking to address the spatial variability of available water in India. We found a significant decrease in the monsoon rainfall over major water surplus river basins in India. Hydrological simulations using a Variable Infiltration Capacity (VIC model also revealed that the water yield in surplus river basins is decreasing but it is increasing in deficit basins. These findings contradict the traditional notion of dry areas becoming drier and wet areas becoming wetter in response to climate change in India. This result also calls for a re-evaluation of planning for river inter-linking to supply water from surplus to deficit river basins.

  1. Indian Summer Monsoon Rainfall: Implications of Contrasting Trends in the Spatial Variability of Means and Extremes.

    Science.gov (United States)

    Ghosh, Subimal; Vittal, H; Sharma, Tarul; Karmakar, Subhankar; Kasiviswanathan, K S; Dhanesh, Y; Sudheer, K P; Gunthe, S S

    2016-01-01

    India's agricultural output, economy, and societal well-being are strappingly dependent on the stability of summer monsoon rainfall, its variability and extremes. Spatial aggregate of intensity and frequency of extreme rainfall events over Central India are significantly increasing, while at local scale they are spatially non-uniform with increasing spatial variability. The reasons behind such increase in spatial variability of extremes are poorly understood and the trends in mean monsoon rainfall have been greatly overlooked. Here, by using multi-decadal gridded daily rainfall data over entire India, we show that the trend in spatial variability of mean monsoon rainfall is decreasing as exactly opposite to that of extremes. The spatial variability of extremes is attributed to the spatial variability of the convective rainfall component. Contrarily, the decrease in spatial variability of the mean rainfall over India poses a pertinent research question on the applicability of large scale inter-basin water transfer by river inter-linking to address the spatial variability of available water in India. We found a significant decrease in the monsoon rainfall over major water surplus river basins in India. Hydrological simulations using a Variable Infiltration Capacity (VIC) model also revealed that the water yield in surplus river basins is decreasing but it is increasing in deficit basins. These findings contradict the traditional notion of dry areas becoming drier and wet areas becoming wetter in response to climate change in India. This result also calls for a re-evaluation of planning for river inter-linking to supply water from surplus to deficit river basins.

  2. Variables Influencing Teacher Autonomy, Administrative Coordination, and Collaboration

    Science.gov (United States)

    Prichard, Caleb; Moore, Jana E.

    2016-01-01

    Purpose: Schools often vary in how they balance teacher autonomy (TA) and administrative control, and research suggests that there may be several context-specific variables which may be influential. The purpose of this paper is to determine the influence of program variables on the level of TA, administrative coordination, and administration-staff…

  3. Variables Influencing Teacher Autonomy, Administrative Coordination, and Collaboration

    Science.gov (United States)

    Prichard, Caleb; Moore, Jana E.

    2016-01-01

    Purpose: Schools often vary in how they balance teacher autonomy (TA) and administrative control, and research suggests that there may be several context-specific variables which may be influential. The purpose of this paper is to determine the influence of program variables on the level of TA, administrative coordination, and administration-staff…

  4. Effects of attentional and cognitive variables on unilateral spatial neglect.

    Science.gov (United States)

    Ricci, Raffaella; Salatino, Adriana; Garbarini, Francesca; Ronga, Irene; Genero, Rosanna; Berti, Anna; Neppi-Mòdona, Marco

    2016-11-01

    Patients with visuospatial neglect when asked to cancel targets partially or totally omit to cancel contralesional stimuli. It has been shown that increasing the attentional demands of the cancellation task aggravates neglect contralesionally. However, some preliminary evidence also suggests that neglect might be worsened by engaging the patient in a demanding, non-spatial, cognitive activity (i.e. a mathematical task). We studied cancellation performance of 16 patients with right-hemisphere lesions, 8 with neglect, 8 without neglect, and 8 age-matched healthy control participants by means of five cancellation tasks which varied for the degree of attentional and/or high level cognitive demands (preattentive and attentive search of a visual target, searching for numbers containing the digit 3, even numbers, and multiples of 3). Results showed that attentive search of visual targets, relative to the preattentive search condition, aggravated neglect patients' performance. Moreover, searching for multiples not only worsened spatial neglect contralesionally, but also slowed down performance of patients with right-hemisphere lesions without neglect. Our findings further demonstrate the presence of specific deficits of attention in neglect. In addition, the worse performance of patients without neglect in the 'multiples of 3' task is consistent with the evidence that right-hemisphere lesions per se impair the ability to maintain attention (i.e. sustained attention). This suggests that the exacerbation of neglect during execution of a demanding, non-spatial, cognitive task might be explained by a deficit of sustained attention in addition to a selective deficit of spatial attention.

  5. Identification and influence of spatial outliers in air quality measurements

    Science.gov (United States)

    O'Leary, B. F.; Lemke, L. D.

    2015-12-01

    The heterogeneous nature of urban air complicates the analysis of spatial and temporal variability in air quality measurements. Evaluation of potentially inaccurate measurements (i.e., outliers) poses particularly difficult challenges in extensive air quality datasets with multiple measurements distributed in time and space. This study investigated the identification and impact of outliers in measurements of NO­2, BTEX, PM2.5, and PM10 in the contiguous Detroit, Michigan, USA and Windsor, Ontario, Canada international airshed. Measurements were taken at 100 locations during September 2008 and June 2009 and modeled at a 300m by 300m scale resolution. The objective was to determine if outliers were present and, if so, to quantify the magnitude of their impact on modeled spatial pollution distributions. The study built upon previous investigations by the Geospatial Determinants of Health Outcomes Consortium that examined relationships between air pollutant distributions and asthma exacerbations in the Detroit and Windsor airshed. Four independent approaches were initially employed to identify potential outliers: boxplots, variogram clouds, difference maps, and the Local Moran's I statistic. Potential outliers were subsequently reevaluated for consistency among methods and individually assessed to select a final set of outliers. The impact of excluding individual outliers was subsequently determined by revising the spatially variable air pollution models and recalculating associations between air contaminant concentrations and asthma exacerbations in Detroit and Windsor in 2008. For the pollutants examined, revised associations revealed weaker correlations with spatial outliers removed. Nevertheless, the approach employed improves the model integrity by increasing our understanding of the spatial variability of air pollution in the built environment and providing additional insights into the association between acute asthma exacerbations and air pollution.

  6. Frog eat frog: exploring variables influencing anurophagy

    Directory of Open Access Journals (Sweden)

    G. John Measey

    2015-08-01

    Full Text Available Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested.Methods. We reviewed the literature on frog diet in order to test the size hypothesis and determine whether there are other putative explanations for anurans in the diet of post-metamorphic frogs. In addition to size, we recorded the habitat, the number of other sympatric anuran species, and whether or not the population was invasive. We controlled for taxonomic bias by including the superfamily in our analysis.Results. Around one fifth of the 355 records included anurans as dietary items of populations studied, suggesting that frogs eating anurans is not unusual. Our data showed a clear taxonomic bias with ranids and pipids having a higher proportion of anuran prey than other superfamilies. Accounting for this taxonomic bias, we found that size in addition to being invasive, local anuran diversity, and habitat produced a model that best fitted our data. Large invasive frogs that live in forests with high anuran diversity are most likely to have a higher proportion of anurans in their diet.Conclusions. We confirm the validity of the size hypothesis for anurophagy, but show that there are additional significant variables. The circumstances under which frogs eat frogs are likely to be complex, but our data may help to alert conservationists to the possible dangers of invading frogs entering areas with threatened anuran species.

  7. Factors modulating social influence on spatial choice in rats.

    Science.gov (United States)

    Bisbing, Teagan A; Saxon, Marie; Sayde, Justin M; Brown, Michael F

    2015-07-01

    Three experiments examined the conditions under which the spatial choices of rats searching for food are influenced by the choices made by other rats. Model rats learned a consistent set of baited locations in a 5 × 5 matrix of locations, some of which contained food. In Experiment 1, subject rats could determine the baited locations after choosing 1 location because all of the baited locations were on the same side of the matrix during each trial (the baited side varied over trials). Under these conditions, the social cues provided by the model rats had little or no effect on the choices made by the subject rats. The lack of social influence on choices occurred despite a simultaneous social influence on rats' location in the testing arena (Experiment 2). When the outcome of the subject rats' own choices provided no information about the positions of other baited locations, on the other hand, social cues strongly controlled spatial choices (Experiment 3). These results indicate that social information about the location of food influences spatial choices only when those cues provide valid information that is not redundant with the information provided by other cues. This suggests that social information is learned about, processed, and controls behavior via the same mechanisms as other kinds of stimuli. (c) 2015 APA, all rights reserved).

  8. Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

    Science.gov (United States)

    Han, Weiqing; Meehl, Gerald A.; Stammer, Detlef; Hu, Aixue; Hamlington, Benjamin; Kenigson, Jessica; Palanisamy, Hindumathi; Thompson, Philip

    2017-01-01

    Sea level rise (SLR) can exert significant stress on highly populated coastal societies and low-lying island countries around the world. Because of this, there is huge societal demand for improved decadal predictions and future projections of SLR, particularly on a local scale along coastlines. Regionally, sea level variations can deviate considerably from the global mean due to various geophysical processes. These include changes of ocean circulations, which partially can be attributed to natural, internal modes of variability in the complex Earth's climate system. Anthropogenic influence may also contribute to regional sea level variations. Separating the effects of natural climate modes and anthropogenic forcing, however, remains a challenge and requires identification of the imprint of specific climate modes in observed sea level change patterns. In this paper, we review our current state of knowledge about spatial patterns of sea level variability associated with natural climate modes on interannual-to-multidecadal timescales, with particular focus on decadal-to-multidecadal variability. Relevant climate modes and our current state of understanding their associated sea level patterns and driving mechanisms are elaborated separately for the Pacific, the Indian, the Atlantic, and the Arctic and Southern Oceans. We also discuss the issues, challenges and future outlooks for understanding the regional sea level patterns associated with climate modes. Effects of these internal modes have to be taken into account in order to achieve more reliable near-term predictions and future projections of regional SLR.

  9. Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

    Science.gov (United States)

    Han, Weiqing; Meehl, Gerald A.; Stammer, Detlef; Hu, Aixue; Hamlington, Benjamin; Kenigson, Jessica; Palanisamy, Hindumathi; Thompson, Philip

    2016-10-01

    Sea level rise (SLR) can exert significant stress on highly populated coastal societies and low-lying island countries around the world. Because of this, there is huge societal demand for improved decadal predictions and future projections of SLR, particularly on a local scale along coastlines. Regionally, sea level variations can deviate considerably from the global mean due to various geophysical processes. These include changes of ocean circulations, which partially can be attributed to natural, internal modes of variability in the complex Earth's climate system. Anthropogenic influence may also contribute to regional sea level variations. Separating the effects of natural climate modes and anthropogenic forcing, however, remains a challenge and requires identification of the imprint of specific climate modes in observed sea level change patterns. In this paper, we review our current state of knowledge about spatial patterns of sea level variability associated with natural climate modes on interannual-to-multidecadal timescales, with particular focus on decadal-to-multidecadal variability. Relevant climate modes and our current state of understanding their associated sea level patterns and driving mechanisms are elaborated separately for the Pacific, the Indian, the Atlantic, and the Arctic and Southern Oceans. We also discuss the issues, challenges and future outlooks for understanding the regional sea level patterns associated with climate modes. Effects of these internal modes have to be taken into account in order to achieve more reliable near-term predictions and future projections of regional SLR.

  10. Spatial and interannual variability in Baltic sprat batch fecundity

    DEFF Research Database (Denmark)

    Haslob, H.; Tomkiewicz, Jonna; Hinrichsen, H.H.;

    2011-01-01

    in the central Baltic Sea, namely the Bornholm Basin, Gdansk Deep and Southern Gotland Basin. Environmental parameters such as hydrography, fish condition and stock density were tested in order to investigate the observed variability in sprat fecundity. Absolute batch fecundity was found to be positively related...

  11. Mineralogy of the clay fraction of Alfisols in two slope curvatures: III - spatial variability

    Directory of Open Access Journals (Sweden)

    Livia Arantes Camargo

    2013-04-01

    Full Text Available A good knowledge of the spatial distribution of clay minerals in the landscape facilitates the understanding of the influence of relief on the content and crystallographic attributes of soil minerals such as goethite, hematite, kaolinite and gibbsite. This study aimed at describing the relationships between the mineral properties of the clay fraction and landscape shapes by determining the mineral properties of goethite, hematite, kaolinite and gibbsite, and assessing their dependence and spatial variability, in two slope curvatures. To this end, two 100 × 100 m grids were used to establish a total of 121 regularly spaced georeferenced sampling nodes 10 m apart. Samples were collected from the layer 0.0-0.2 m and analysed for iron oxides, and kaolinite and gibbsite in the clay fraction. Minerals in the clay fraction were characterized from their X-ray diffraction (XRD patterns, which were interpreted and used to calculate the width at half height (WHH and mean crystallite dimension (MCD of iron oxides, kaolinite, and gibbsite, as well as aluminium substitution and specific surface area (SSA in hematite and goethite. Additional calculations included the goethite and hematite contents, and the goethite/(goethite+hematite [Gt/(Gt+Hm] and kaolinite/(kaolinite+gibbsite [Kt/(Kt+Gb] ratios. Mineral properties were established by statistical analysis of the XRD data, and spatial dependence was assessed geostatistically. Mineralogical properties differed significantly between the convex area and concave area. The geostatistical analysis showed a greater number of mineralogical properties with spatial dependence and a higher range in the convex than in the concave area.

  12. Spatial variability in the soil water content of a Mediterranean agroforestry system with high soil heterogeneity

    Science.gov (United States)

    Molina, Antonio Jaime; Llorens, Pilar; Aranda, Xavier; Savé, Robert; Biel, Carmen

    2013-04-01

    Variability of soil water content is known to increase with the size of spatial domain in which measurements are taken. At field scale, heterogeneity in soil, vegetation, topography, water input volume and management affects, among other factors, hydrologic plot behaviour under different mean soil water contents. The present work studies how the spatial variability of soil water content (SWC) is affected by soil type (texture, percentage of stones and the combination of them) in a timber-orientated plantation of cherry tree (Prunus avium) under Mediterranean climatic conditions. The experimental design is a randomized block one with 3 blocks * 4 treatments, based on two factors: irrigation (6 plots irrigated versus 6 plots not irrigated) and soil management (6 plots tillaged versus 6 plots not tillaged). SWC is continuously measured at 25, 50 and 100 cm depth with FDR sensors, located at two positions in each treatment: under tree influence and 2.5 m apart. This study presents the results of the monitoring during 2012 of the 24 sensors located at the 25 cm depth. In each of the measurement point, texture and percentage of stones were measured. Sandy-loam, sandy-clay-loam and loam textures were found together with a percentage of stones ranging from 20 to 70 %. The results indicated that the relationship between the daily mean SWC and its standard deviation, a common procedure used to study spatial variability, changed with texture, percentage of stones and the estimation of field capacity from the combination of both. Temporal stability analysis of SWC showed a clear pattern related to field capacity, with the measurement points of the sandy-loam texture and the high percentage of stones showing the maximun negative diference with the global mean. The high range in the mean relative difference observed (± 75 %), could indicate that the studied plot may be considered as a good field-laboratory to extrapolate results at higher spatial scales. Furthermore, the

  13. Spatial Variability of Soil Inorganic N in a Mature Oil Palm Plantation in Sabah, Malaysia

    Directory of Open Access Journals (Sweden)

    Abdul R. Anuar

    2008-01-01

    Full Text Available The identification and understanding of soil factors influencing yield variability of oil palm enable their efficient management. Soil samples were therefore collected from a fertilizer response trial on oil palm to study the spatial inorganic N distribution and some selected soil chemical properties as affected by long-term N fertilizer applications. The experiment was conducted on mature oil palms grown on Kumansi family (Typic Paleudults soil in Tawau, Sabah, Malaysia. The soil samples were taken from 2 areas; with and without N treatments for 8 years. They were analyzed for total N, NH4+-N, NO3--N, exchangeable K, and pH. Semivariance analysis was used to characterize the spatial variance of soil NH4+-N and NO3--N while point kriging method was used to illustrate their spatial distributions. Results showed that application of N in the palm circle increased soil NH4+-N above 150 mg kg-1 at 0 to 15 cm depth. In unmanured plot, the NH4+-N contents were similar in the different sites within a palm area although the frond heap area tended to have higher NH4+-N probably due to the N return from the decaying cut fronds. The coefficient of variations for both soil NH4+-N and NO3--N exceeded 30% even within each microsite of palm circle, interrow, frond heaps, and harvesting path. Semivariance analysis showed that the maximum range of soil NH4+-N could be reached at 10 m and 90 m in areas with and without N respectively, indicating that the application of N fertilizer reduced its spatial variability in mature oil palm agroecosystem. The kriged soil map showed localized spots of high NH4+-N content, which corresponded to the palm circles where N fertilizer was applied. Gradual changes in soil fertility were observed in area without N, moving from northern to southern portion of the field. Long-term applications of N caused significant downward movement of NH4+-N and NO3--N to the lower soil depth. They also decreased the soil pH from 4.2 to 3.7, and

  14. Assessment of spatial structure of groundwater quality variables based on the entropy theory

    Directory of Open Access Journals (Sweden)

    Y. Mogheir

    2003-01-01

    Full Text Available Fundamental to the spatial sampling design of a groundwater quality monitoring network is the spatial structure of groundwater quality variables. The entropy theory presents an alternative approach to describe this variability. A case study is presented which used groundwater quality observations (13 years; 1987-2000 from groundwater domestic wells in the Gaza Strip, Palestine. The analyses of the spatial structure used the following variables: Electrical Conductivity (EC, Total Dissolved Solids (TDS, Calcium (Ca, Magnesium (Mg, Sodium (Na, Potassium (K, Chloride (Cl, Nitrate (NO3, Sulphate (SO4, alkalinity and hardness. For all these variables the spatial structure is described by means of Transinformation as a function of distance between wells (Transinformation Model and correlation also as a function of distance (Correlation Model. The parameters of the Transinformation Model analysed were: (1 the initial value of the Transinformation; (2 the rate of information decay; (3 the minimum constant value; and (4 the distance at which the Transinformation Model reaches its minimum value. Exponential decay curves were fitted to both models. The Transinformation Model was found to be superior to the Correlation Model in representing the spatial variability (structure. The parameters of the Transinformation Model were different for some variables and similar for others. That leads to a reduction of the variables to be monitored and consequently reduces the cost of monitoring. Keywords: transinformation, correlation, spatial structure, municipal wells, groundwater monitoring, entropy

  15. Circulation weather types and spatial variability of daily precipitation in the Iberian Peninsula %K circulation weather types, daily gridded precipitation, Iberian Peninsula, spatial variability, seasonal variability

    Science.gov (United States)

    Ramos, Alexandre; Cortesi, Nicola; Trigo, Ricardo

    2014-10-01

    The relationships between atmospheric circulation patterns and daily Iberian rainfall are here explored at high spatial resolution (0.2°) using the Jenkinson and Collison automated classification scheme with 26 Weather Types (WTs). The WTs were computed by means of the daily EMULATE Mean Sea Level Pressure dataset (EMSLP) while the high resolution precipitation database corresponds to the recent Iberia02 daily gridded precipitation dataset over the 1950-2003 period. Six monthly indexes relating the WTs and precipitation were analyzed: their Frequency, the Mean Precipitation, the Percentage Contribution, the Area of Influence, the Precipitation Intensity and Efficiency. Except for the Frequency of the WTs, all other indexes were evaluated studying their spatial distribution over the Iberian Peninsula, focusing on a WT and a month at time. A small number of WTs (7) was found to capture a high percentage (~70%) of monthly Iberian precipitation. The Westerly WT is the most influent one, followed by the Cyclonic, the Northwesterly and the Southwesterly WTs. Westerly flows, however, do not affect the Mediterranean fringe or the Cantabrian coast, which are dominated by the Easterly and Northerly WTs, respectively. Rainfall along the Mediterranean coastline and the Ebro basin depends on a variety of WTs, but their effects are confined to narrow areas and short temporal intervals, suggesting that local factors such as convective processes, orography and the proximity to a warm water body could play a major role in precipitation processes. We show that the use of daily gridded precipitation dataset holds the advantage of measuring the daily rainfall amount due to each WT directly instead to relying on the predicted values of the regression model as done in previous works.

  16. Solar wind influences on atmospheric electricity variables in polar regions

    Science.gov (United States)

    Michnowski, Stanisław

    The measurement techniques applied in magnetospheric and ionospheric research enable detection of strong, intrinsic effects of solar wind on ionospheric electrical potential distribution and conductivity of the atmosphere. These manifestations of the solar wind interaction with the magnetosphere and ionosphere are especially evident at high latitudes. The possibility of observing there the response of the atmospheric electricity variables to solar wind has been questioned for a long time despite the fact that the atmospheric electric field and current variations at the ground are physically linked with electric potential of the ionosphere and conductivity of the lower atmosphere. The serious doubts were mainly due to the generally accepted opinion that the highly conducting ionosphere is an almost ideal equipotential electric screen that separates the weakly conductive lower atmosphere of the influence from space. This assumption could not be further upheld in view of the new findings. They have been provided for some time by ground-based atmospheric electric field and current measurements (AEMs) with simultaneous upper atmosphere observations and by corresponding balloon measurements. Recent ground-based AEMs in polar regions, i.e., in the near-subauroral, auroral, and polar cap high-latitude regions, have detected considerable influence of solar wind on the lower-atmosphere electric variables. However, the use of atmospheric electric observations in studying solar-terrestrial relations is still limited. The main reason is difficulty in separating various local meteorological effects, anthropogenic effects, and the effects of the global electric current circuit which affect simultaneously the measured quantities. Transmission of the electric signals through the lower atmosphere can also introduce troublesome disturbances. The paper outlines these problems and hints how the difficulties involved might be partly overcome in a feasible way. The needs and possible

  17. Evaluation of spatial variability of metal bioavailability in soils using geostatistics

    DEFF Research Database (Denmark)

    Owsianiak, Mikolaj; Hauschild, Michael Zwicky; Rosenbaum, Ralph K.

    2012-01-01

    for different soils. Here, variography is employed to analyse spatial variability of bioavailability factors (BFs) of metals at the global scale. First, published empirical regressions are employed to calculate BFs of metals for 7180 topsoil profiles. Next, geostatistical interpretation of calculated BFs...... is performed using ArcGIS Geostatistical Analyst. Results show that BFs of copper span a range of 6 orders of magnitude, and have signifficant spatial variability at local and continental scales. The model nugget variance is signifficantly higher than zero, suggesting the presence of spatial variability...... at lags smaller than those in the data set. Geostatistical analyses indicate however, that BFs exhibit no signifficant spatial correlation at a range beyond 3200 km. Because BF is spatially correlated, its values at unsampled locations can be predicted, as demonstrated using ordinary kriggin method...

  18. Spatial variability of soybean yields under two systems cropping in savannah

    Directory of Open Access Journals (Sweden)

    Lúcio Bastos Madeiros

    2009-08-01

    Full Text Available The geostatistics is an important tool in analysis and description of soil variability properties. The maps of productivity are considered an excellent tool for analysis of performance at the level of agricultural property. Objective was to analyze the spatial yield variability of soybean in no-tillage e conventional-tillage. The experiment was carried out in two plots in sampling points defined accordingly to grid with dimension of 40 x 55 m, totaling 44 points spaced 5m. Statistical and geostatistical analysis were performed to monitor the range of spatial variability and spatial dependence. Soybean yield didn't present spatial dependence in none systems. The management in conventional-tillage was decisive in increase the yield of soybean in relation to no-tillage.Key-words: geostatistic; spatial dependence; management soil.

  19. Geostatistical independent simulation of spatially correlated soil variables

    Science.gov (United States)

    Boluwade, Alaba; Madramootoo, Chandra A.

    2015-12-01

    The selection of best management practices to reduce soil and water pollution often requires estimation of soil properties. It is important to find an efficient and robust technique to simulate spatially correlated soils parameters. Co-kriging and co-simulation are techniques that can be used. These methods are limited in terms of computer simulation due to the problem of solving large co-kriging systems and difficulties in fitting a valid model of coregionalization. The order of complexity increases as the number of covariables increases. This paper presents a technique for the conditional simulation of a non-Gaussian vector random field on point support scale. The technique is termed Independent Component Analysis (ICA). The basic principle underlining ICA is the determination of a linear representation of non-Gaussian data so that the components are considered statistically independent. With such representation, it would be easy and more computationally efficient to develop direct variograms for the components. The process is presented in two stages. The first stage involves the ICA decomposition. The second stage involves sequential Gaussian simulation of the generated components (which are derived from the first stage). This technique was applied for spatially correlated extractable cations such as magnesium (Mg) and iron (Fe) in a Canadian watershed. This paper has a strong application in stochastic quantification of uncertainties of soil attributes in soil remediation and soil rehabilitation.

  20. Spatial variability and its scale dependency of observed and modeled soil moisture under different climate conditions

    Directory of Open Access Journals (Sweden)

    B. Li

    2012-09-01

    Full Text Available Past studies on soil moisture spatial variability have been mainly conducted in catchment scales where soil moisture is often sampled over a short time period. Because of limited climate and weather conditions, the observed soil moisture often exhibited smaller dynamic ranges which prevented the complete revelation of soil moisture spatial variability as a function of mean soil moisture. In this study, spatial statistics (mean, spatial variability and skewness of in situ soil moisture measurements (from a continuously monitored network across the US, modeled and satellite retrieved soil moisture obtained in a warm season (198 days were examined at large extent scales (>100 km over three different climate regions. The investigation on in situ measurements revealed that their spatial moments strongly depend on climates, with distinct mean, spatial variability and skewness observed in each climate zone. In addition, an upward convex shape, which was revealed in several smaller scale studies, was observed for the relationship between spatial variability of in situ soil moisture and its spatial mean across dry, intermediate, and wet climates. These climate specific features were vaguely or partially observable in modeled and satellite retrieved soil moisture estimates, which is attributed to the fact that these two data sets do not have climate specific and seasonal sensitive mean soil moisture values, in addition to lack of dynamic ranges. From the point measurements to satellite retrievals, soil moisture spatial variability decreased in each climate region. The three data sources all followed the power law in the scale dependency of spatial variability, with coarser resolution data showing stronger scale dependency than finer ones. The main findings from this study are: (1 the statistical distribution of soil moisture depends on spatial mean soil moisture values and thus need to be derived locally within any given area; (2 the boundedness of soil

  1. Natural and Anthropogenic Influences on Atmospheric Aerosol Variability

    Energy Technology Data Exchange (ETDEWEB)

    Asmi, A.

    2012-07-01

    Aerosol particles are everywhere in the atmosphere. They are a key factor in many important processes in the atmosphere, including cloud formation, scattering of incoming solar radiation and air chemistry. The aerosol particles have relatively short lifetimes in lower atmosphere, typically from days to weeks, and thus they have a high spatial and temporal variability. This thesis concentrates on the extent and reasons of sub-micron aerosol particle variability in the lower atmosphere, using both global atmospheric models and analysis of observational data. Aerosol number size distributions in the lower atmosphere are affected strongly by the new particle formation. Perhaps more importantly, a strong influence new particle formation is also evident in the cloud condensation nuclei (CCN) concentrations, suggesting a major role of the sulphuric acid driven new particle formation in the climate system. In this thesis, the sub-micron aerosol number size distributions in the European regional background air were characterized for the first time from consistent, homogenized and comparable datasets. Some recent studies have suggested that differences in aerosol emissions between weekdays could also affect the weather via aerosol-cloud interactions. In this thesis, the weekday-to-weekday variation of CCN sized aerosol number concentrations in Europe were found to be much smaller than expected from earlier studies, based on particle mass measurements. This result suggests that a lack of week-day variability in meteorology is not necessarily a sign of weak aerosol-cloud interactions. An analysis of statistically significant trends in past decades of measured aerosol number concentrations from Europe, North America, Pacific islands and Antarctica generally show decreases in concentrations. The analysis of these changes show that a potential explanation for the decreasing trends is the general reduction of anthropogenic emissions, especially SO{sub 2}, although a combination of

  2. Annual and spatial variability in gains of body weight in

    NARCIS (Netherlands)

    Beukema, J.J.; Cadée, G.C.A.; Dekker, R.; Philippart, C.J.M.

    2014-01-01

    The present paper reports on the results of a long-term field study on the simultaneous influence of 2 environmental factors (temperature and food supply) on annual growth rates in the tellinid bivalve Macoma balthica. For > 30 y (1978–2009) we monitored twice-annually the weight changes of soft par

  3. Spatial and temporal variability of tropospheric ozone over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Scheel, H.E.; Sladkovic, R. [Fraunhofer Inst. (IFU), Garmisch-Partenkirchen (Germany); Ancellet, G. [Universite Paris 6 (France). Service d`Aeronomie du CNRS; Areskoug, H. [Air Pollution Lab., Inst. of Applied Environmental Research, Stockholm Univ. (Sweden); Beck, J.; Waal, L. de [RIVM-LLO, Bilthoven (Netherlands); Boesenberg, J.; Grabbe, G. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Muer, D. de [Meteorological Inst. of Belgium (KMI), Brussels (Belgium); Dutot, A.L.; Etienne, A.; Perros, P.; Toupance, G. [Universite Paris XII-Creteil (France). Lab. de Physico-Chimie de l`Environment; Egelov, A.H.; Granby, K. [National Environmental Research Inst., Roskilde (Denmark); Esser, P.; Roemer, M. [IMW-TNO, Delft (Netherlands); Ferenczi, Z.; Haszpra, L. [Institute for Atmospheric Physics, Budapest (Hungary); Geiss, H.; Smit, H. [Forschungszentrum Juelich (Germany). Inst. fuer Chemie und Dynamik der Geosphaere (ICG-2); Gomiscek, B. [Ljubljana Univ. (Slovenia). Faculty of Chemistry and Chemical Technology; Kezele, N.; Klasinc, L. [Institut Rudjer Boskovic, Zagreb (Croatia); Laurila, T. [Finnish Meteorological Inst., Helsinki (Finland). Dept. of Air Quality; Lindskog, A.; Mowrer, J. [Swedish Environmental Research Inst. (IVL), Goeteborg (Sweden); Nielsen, T. [Risoe National Laboratory, Roskilde (Denmark); Schmitt, R. [Meteorologie Consult GmbH, Glashuetten (Germany); Simmonds, P. [International Science Consultants, Ringwood (United Kingdom); Solberg, S. [NILU, Kjeller (Norway); Varotsos, C. [Athens Univ. (Greece); TOR Task Group 1

    1997-12-31

    The first section is concerned with the characteristics of the TOR-measurement sites and the data used. It describes the methodologies employed for the selection of data in order to obtain representative ozone concentrations with minimum bias caused by the individual location. The question of representativeness of the O{sub 3} concentrations at the TOR sites was given special attention, since it is a crucial point for all conclusions drawn from the observations. Therefore several studies were focused on this issue. The further sections of the report deal with results on the spatial and seasonal variations of ozone concentrations over Europe. Results obtained from in-situ measurements in the boundary layer/lower free troposphere and from vertical soundings in the free troposphere are regarded separately. Finally, trend estimates are presented for ozone as well as for some of its precursors. (orig./KW)

  4. Multivariate spatially-structured variability of ovine helminth infections

    Directory of Open Access Journals (Sweden)

    Annibale Biggeri

    2007-11-01

    Full Text Available A cross-sectional survey was carried out on 2004-2005 in the Campania region, southern Italy, to study the multivariate geographical distribution of four different sheep helminths, i.e. Fasciola hepatica (liver fluke, Calicophoron (Paramphistomum daubneyi (rumen fluke, Dicrocoelium dendriticum (lancet fluke, and the gastrointestinal strongyle Haemonchus contortus. A series of multivariate Bayesian hierarchical models based on square root transformation of faecal egg counts were performed. The results were consistent with theoretical knowledge of the biology and epidemiology of the four studied helminths. In particular, the impact of common intermediate hosts (F. hepatica and C. daubneyi share the same intermediate host species was quantified and evidence of previously unknown ecological components was given. D. dendriticum was correlated to F. hepatica and H. contortus was found not to be spatially associated with the previously mentioned helminths.

  5. Spatial and temporal variability of rainfall erosivity factor for Switzerland

    Directory of Open Access Journals (Sweden)

    A. Steel

    2011-09-01

    Full Text Available Rainfall erosivity, considering rainfall amount and intensity, is an important parameter for soil erosion risk assessment under future land use and climate change. Despite its importance, rainfall erosivity is usually implemented in models with a low spatial and temporal resolution. The purpose of this study is to assess the temporal- and spatial distribution of rainfall erosivity (R-factor in Switzerland. Time series of 22 yr for rainfall (10 min resolution and temperature (1 h resolution data were analysed for 71 automatic gauging stations distributed throughout Switzerland. Multiple regression was used to interpolate the erosivity values of single stations and to generate a map for Switzerland. Latitude, longitude, average annual precipitation, biogeographic units (Jura, Midland, etc., aspect and elevation were used as covariates, of which average annual precipitation, elevation and the biographic unit (Western Alps were significant predictors. The mean value of long-term rainfall erosivity is 1323 MJ mm ha−1 h−1 yr−1 with a range of lowest values of 124 MJ mm ha−1 h−1 yr−1 at an elevated station in Grisons to highest values of 5611 MJ mm ha−1 h−1 yr−1 in Ticino. All stations have highest erosivity values from July to August and lowest values in the winter month. Swiss-wide the month May to October show significantly increasing trends of erosivity (p<0.005. Only in February a significantly decreasing trend of rainfall erosivity is found (p<0.01. The increasing trends of erosivity in May, September and October when vegetation cover is susceptible are likely to enhance soil erosion risk for certain agricultural crops and alpine grasslands in Switzerland.

  6. Sensitivity of Average Annual Runoff to Spatial Variability and Temporal Correlation of Rainfall.

    Science.gov (United States)

    Babin, Steven M.

    1995-08-01

    This paper examines the sensitivity of annual area mean runoff calculations to the effects of spatial variability and temporal correlation of rainfall. The model used is based upon the hypothesis that the annual water balance is determined only by rainfall, potential evapotranspiration, and soil water storage. A simple bucket hydrology model with a seasonally varying potential evapotranspiration is used with rainfall data measured at several sites on the Delmarva Peninsula. Annual area mean runoffs are calculated for three cases: 1) actual spatial variability among the rain gauge sites and temporal correlation between consecutive 1-min rainfall amounts are maintained (the actual case); 2) actual spatial variability among the sites is maintained but temporal correlation between the consecutive 1-min rainfall amounts is minimized (the site-shuffled case); and 3) both spatial variability and temporal correlation are ignored (the area-averaged case). The actual case represents the baseline for comparison with the other two cases. The annual a' mean runoffs show little sensitivity to spatial variability and temporal correlation for this model. Therefore, if finite soil permeability effects are ignored in favor of simple water storage capacity, then spatial variability and temporal correlation of rainfall appear to have little impact on the annual area mean runoff for the data considered in this study.

  7. Spatial Variability of Soil Properties in Archeological Dark Earth Sites under Cacao Cultivation

    Directory of Open Access Journals (Sweden)

    Douglas Marcelo Pinheiro da Silva

    2016-01-01

    Full Text Available ABSTRACT Soils with an A horizon formed by human activity, an anthropogenic A horizon, are found in the Amazon Region. Few studies have examined the spatial distribution of the properties of these soils. We mapped the spatial variability of some soil properties in an area of Archaeological Dark Earth (ADE in the Brazilian Amazon. A sampling grid was defined over an area of 42 × 88 m under cacao cultivation in which sampling points were established at a spacing of 6 × 8 m, for a total of 88 points. Samples were collected from the 0.00-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m depth layers. Soil texture, aggregate stability, and organic carbon (OC analyses were performed on disturbed soil samples. Undisturbed samples were used to determine soil macroporosity (Macro, microporosity (Micro, total porosity (TP, and soil resistance to penetration (RP. The results were analyzed by descriptive statistic, Pearson correlation (p<0.01, and geostatistics. Soil bulk density, total pore volume, and geometric mean diameter are dependent on the total amount of OC in the ADE area. Increased soil bulk density and RP are proportional to a decrease in OC content and lower Micro and TP. Moreover, soil resistance to penetration is influenced by soil water and clay content with depth.

  8. Spatial and temporal variability in seasonal snow density

    KAUST Repository

    Bormann, Kathryn J.

    2013-03-01

    Snow density is a fundamental physical property of snowpacks used in many aspects of snow research. As an integral component in the remote sensing of snow water equivalent and parameterisation of snow models, snow density may be used to describe many important features of snowpack behaviour. The present study draws on a significant dataset of snow density and climate observations from the United States, Australia and the former Soviet Union and uses regression-based techniques to identify the dominant climatological drivers for snow densification rates, characterise densification rate variability and estimate spring snow densities from more readily available climate data. Total winter precipitation was shown to be the most prominent driver of snow densification rates, with mean air temperature and melt-refreeze events also found to be locally significant. Densification rate variance is very high at Australian sites, very low throughout the former Soviet Union and between these extremes throughout much of the US. Spring snow densities were estimated using a statistical model with climate variable inputs and best results were achieved when snow types were treated differently. Given the importance of snow density information in many snow-related research disciplines, this work has implications for current methods of converting snow depths to snow water equivalent, the representation of snow dynamics in snow models and remote sensing applications globally. © 2013 Elsevier B.V.

  9. Understanding the spatial and temporal variability of water sources in a humid forested catchment

    Science.gov (United States)

    Pianezzola, Luisa; Zuecco, Giulia; Pozzoni, Santiago; Penna, Daniele; Borga, Marco

    2016-04-01

    streamflow during baseflow conditions. Shallow groundwater shows a remarkable spatial variability in its hydrochemical signature, but a relative smaller temporal variability. On the contrary, soil water shows a large temporal variability, especially in its isotopic composition, partly reflecting the signal of infiltrating rainfall. The largest sampled event (131 mm) is characterized by four streamflow peaks of increasing size, proportionally matched by fluctuations in soil moisture and water table. Three-component hydrograph separation for this event shows that, on average, according to different scenarios, the rainfall component accounts for 3%-14% of the total streamflow, soil water fractions range between 45% and 58%, and groundwater fractions vary between 30% and 46%, with maximum instantaneous contribution up to 90% during the last and largest streamflow peak. The temporal analysis reveals that at the beginning of the event streamflow is mainly composed by riparian groundwater. With increasing rainfall amount and wetness conditions, streamflow is principally influenced by soil water and rain water likely due to the saturation of the near-stream riparian corridor. At the end of the event the sharp rise of water table on the hillslopes and the development of subsurface connectivity contribute to sustain groundwater in the lower part of the catchment producing a marked streamflow response. Keywords: humid catchment; isotopes; ions; runoff response; shallow groundwater.

  10. Spatial Variability of Soil Chemical Properties in the Reclaiming Marine Foreland to Yellow Sea of China

    Institute of Scientific and Technical Information of China (English)

    WEI Yi-chang; BAI You-lu; JIN Ji-yun; ZHANG Fang; ZHANG Li-ping; LIU Xiao-qiang

    2009-01-01

    Precise information about the spatial variability of soil properties is essential in developing site-specific soil management,such as variable rate application of fertilizers.In this study the sampling grid of 100 m×100 m was established to collect 1703 soil samples at the depth of 0-20 cm,and examine spatial patterns including 13 soil chemical properties (pH,OM,NH4+,PK,Ca,Mg,S,B,Cu,Fe,Mn,and Zn) in a 1760 ha rice field in Haifeng farm,China,from 6th to 22nd of April,2006,before fertilizer application and planting.Soil analysis was performed by ASI (Agro Services International) and data were analyzed both statistically and geostatistically.Results showed that the contents of soil OM,NH4+,and Zn in Haifeng farm were very low for rice production and those of others were enough to meet the need for rice cultivation.The spatial distribution model and spatial dependence level for 13 soil chemical properties varied in the field.Soil Mg and B showed strong spatial variability on both descriptive statistics and geostatistics,and other properties showed moderate spatial variability.Themaximum ranges for K,Ca,Mg,S,Cu and Mn were all~3990.6m and the minimum ranges for soil pH,OM,NH4+,P,Fe,and Zn ranged from 516.7 to 1166.2 m.Clearpatchy distribution of N,P,K,Mg,S,B,Mn,and Zn were found from their spatial distribution maps.This proved that sampling strategy for estimating variability should be adapted to the different soil chemical properties and field management.Therefore,the spatial variability of soil chemical properties with strong spatial dependence could be readily managed and a site-specific fertilization scheme for precision farming could be easily developed.

  11. Spatial and temporal variability of rainfall erosivity factor for Switzerland

    Directory of Open Access Journals (Sweden)

    K. Meusburger

    2012-01-01

    Full Text Available Rainfall erosivity, considering rainfall amount and intensity, is an important parameter for soil erosion risk assessment under future land use and climate change. Despite its importance, rainfall erosivity is usually implemented in models with a low spatial and temporal resolution. The purpose of this study is to assess the temporal- and spatial distribution of rainfall erosivity in form of the (Revised Universal Soil Loss Equation R-factor for Switzerland. Time series of 22 yr for rainfall (10 min resolution and temperature (1 h resolution data were analysed for 71 automatic gauging stations distributed throughout Switzerland. Regression-kriging was used to interpolate the rainfall erosivity values of single stations and to generate a map for Switzerland. Latitude, longitude, average annual precipitation, biogeographic units (Jura, Midland, etc., aspect and elevation were used as covariates, of which average annual precipitation, elevation and the biographic unit (Western Central Alps were significant (p<0.01 predictors. The mean value of long-term rainfall erosivity is 1330 MJ mm ha−1 h−1 yr−1 with a range of lowest values of 124 MJ mm ha−1 h−1 yr−1 at an elevated station in Grisons to highest values of 5611 MJ mm ha−1 h−1 yr−1 in Ticino. All stations have highest erosivity values from July to August and lowest values in the winter months. Swiss-wide the month May to October show significantly increasing trends of rainfall erosivity for the observed period (p<0.005. Only in February a significantly decreasing trend of rainfall erosivity is found (p<0.01. The increasing trends of rainfall erosivity in May, September and October when vegetation cover is scarce are likely to enhance soil erosion risk for certain agricultural crops and alpine grasslands in Switzerland.

  12. Eddies spatial variability at Makassar Strait – Flores Sea

    Science.gov (United States)

    Nuzula, F.; Syamsudin, M. L.; Yuliadi, L. P. S.; Purba, N. P.; Martono

    2017-01-01

    This study was aimed to get the distribution of eddies spatially and temporally from Makassar Waters (MW) to Flores Sea (FS), as well as its relations with the upwelling, the downwelling, and chlorophyll-a concentration. The study area extends from 115º–125º E to 2.5º–8º S. The datasets were consisted of monthly geostrophic currents, sea surface heights, sea surface temperatures, and chlorophyll-a from 2008 – 2012. The results showed that eddies which found at Makassar Strait (MS) has the highest diameter and speed of 255.3 km and 21.4 cm/s respectively, while at the southern MW has 266.4 km and 15.6 cm/s, and at FS has 182.04 km and 11.4 cm/s. From a total of 51 eddies found, the majority of eddies type was anticyclonic. At MS and FS, eddies formed along the year, whereas at southern MW were found missing in West Season. Moreover, the chlorophyll-a concentration was consistently higher at the eddies area. Even though, the correlation among eddies and the upwelling downwelling phenomena was not significantly as shown by sea surface temperatures value.

  13. Spatial monsoon variability with respect to NAO and SO

    Indian Academy of Sciences (India)

    S B Kakade; S S Dugam

    2006-10-01

    In this paper, the simultaneous effect of North Atlantic Oscillation (NAO) and Southern Oscillation (SO) on monsoon rainfall over different homogeneous regions/subdivisions of India is studied. The simultaneous effect of both NAO and SO on Indian summer monsoon rainfall (ISMR) is more important than their individual impact because both the oscillations exist simultaneously throughout the year. To represent the simultaneous impact of NAO and SO, an index called effective strength index (ESI) has been defined on the basis of monthly NAO and SO indices. The variation in the tendency of ESI from January through April has been analyzed and reveals that when this tendency is decreasing, then the ESI value throughout the monsoon season (June-September) of the year remains negative and vice versa. This study further suggests that during the negative phase of ESI tendency, almost all subdivisions of India show above-normal rainfall and vice versa. The correlation analysis indicates that the ESI-tendency is showing an inverse and statistically significant relationship with rainfall over 14 subdivisions of India. Area wise, about 50% of the total area of India shows statistically significant association. Moreover, the ESI-tendency shows a significant relationship with rainfall over north west India, west central India, central north east India, peninsular India and India as a whole. Thus, ESI-tendency can be used as a precursor for the prediction of Indian summer monsoon rainfall on a smaller spatial scale.

  14. Environmental Variables That Influence Patient Satisfaction: A Review of the Literature.

    Science.gov (United States)

    MacAllister, Lorissa; Zimring, Craig; Ryherd, Erica

    2016-10-01

    Patient's perception of care-referred to as patient satisfaction-is of great interest in the healthcare industry, as it becomes more directly tied to the revenue of the health system providers. The perception of care has now become important in addition to the actual health outcome of the patient. The known influencers for the patient perception of care are the patient's own characteristics as well as the quality of service received. In patient surveys, the physical environment is noted as important for being clean and quiet but is not considered a critical part of patient satisfaction or other health outcomes. Patient perception of care is currently measured as patient satisfaction, a systematic collection of perceptions of social interactions from an individual person as well as their interaction with the environment. This exploration of the literature intends to explore the rigorous, statistically tested research conducted that has a spatial predictor variable and a health or behavior outcome, with the intent to begin to further test the relationships of these variables in the future studies. This literature review uses the patient satisfaction framework of components of influence and identifies at least 10 known spatial environmental variables that have been shown to have a direct connection to the health and behavior outcome of a patient. The results show that there are certain features of the spatial layout and environmental design in hospital or work settings that influence outcomes and should be noted in the future research.

  15. Partitioning the impacts of spatial and climatological rainfall variability in urban drainage modeling

    Science.gov (United States)

    Peleg, Nadav; Blumensaat, Frank; Molnar, Peter; Fatichi, Simone; Burlando, Paolo

    2017-03-01

    The performance of urban drainage systems is typically examined using hydrological and hydrodynamic models where rainfall input is uniformly distributed, i.e., derived from a single or very few rain gauges. When models are fed with a single uniformly distributed rainfall realization, the response of the urban drainage system to the rainfall variability remains unexplored. The goal of this study was to understand how climate variability and spatial rainfall variability, jointly or individually considered, affect the response of a calibrated hydrodynamic urban drainage model. A stochastic spatially distributed rainfall generator (STREAP - Space-Time Realizations of Areal Precipitation) was used to simulate many realizations of rainfall for a 30-year period, accounting for both climate variability and spatial rainfall variability. The generated rainfall ensemble was used as input into a calibrated hydrodynamic model (EPA SWMM - the US EPA's Storm Water Management Model) to simulate surface runoff and channel flow in a small urban catchment in the city of Lucerne, Switzerland. The variability of peak flows in response to rainfall of different return periods was evaluated at three different locations in the urban drainage network and partitioned among its sources. The main contribution to the total flow variability was found to originate from the natural climate variability (on average over 74 %). In addition, the relative contribution of the spatial rainfall variability to the total flow variability was found to increase with longer return periods. This suggests that while the use of spatially distributed rainfall data can supply valuable information for sewer network design (typically based on rainfall with return periods from 5 to 15 years), there is a more pronounced relevance when conducting flood risk assessments for larger return periods. The results show the importance of using multiple distributed rainfall realizations in urban hydrology studies to capture the

  16. Estimating range of influence in case of missing spatial data

    DEFF Research Database (Denmark)

    Bihrmann, Kristine; Ersbøll, Annette K

    2015-01-01

    BACKGROUND: The range of influence refers to the average distance between locations at which the observed outcome is no longer correlated. In many studies, missing data occur and a popular tool for handling missing data is multiple imputation. The objective of this study was to investigate how...... the estimated range of influence is affected when 1) the outcome is only observed at some of a given set of locations, and 2) multiple imputation is used to impute the outcome at the non-observed locations. METHODS: The study was based on the simulation of missing outcomes in a complete data set. The range...... of influence was estimated from a logistic regression model with a spatially structured random effect, modelled by a Gaussian field. Results were evaluated by comparing estimates obtained from complete, missing, and imputed data. RESULTS: In most simulation scenarios, the range estimates were consistent...

  17. Spatial variability of heavy metals in the coastal soils under long-term reclamation

    Science.gov (United States)

    Wang, Lin; Coles, Neil A.; Wu, Chunfa; Wu, Jiaping

    2014-12-01

    The coastal plain of Cixi City, China, has experienced over 1000 years of reclamation. With the rapid development of agriculture and industry after reclamation, successive inputs into agricultural soils have drastically modified the soil environment. To determine the spatial distribution of heavy metals and to evaluate the influence of anthropogenic activities, a total of 329 top soil samples were taken along a transect on the coastal plain. The samples collected across 11 sea dikes, were selected by a nested sampling methodology. Total Cu, Fe, Mn, Ni, Pb, and Zn concentrations, as well as their diethylenetriamine penta-acetic acid (DTPA) extractable (available) concentrations were determined. Results indicated that except for Zn concentrations, there was neither heavy metals pollution nor mineral deficiency in the soils. Heavy metals exhibited considerable spatial variability, obvious spatial dependence, and close relationships on the reclaimed land. For most metals, the reclamation history was the main influencing factor. Metals concentrations generally showed discontinuities around the position of sea dikes, and the longer reclamation histories tended to have higher metals concentrations than the recently reclaimed sectors. As for Cu and Zn total concentrations, stochastic factors, like industrial waste discharge, fertilization and pesticide application, probably led to the high nugget effect and altered this relationship. The 6th and 10th zones generally had the highest total metals concentrations, due to the concentration of household appliance manufacturers in these reclaimed areas. The first two zones were characterized by high available metals concentrations, probably due to the alternant flooding and emergence, low pH values and high organic matter contents in these paddy field soils. From the 3rd to 7th zones with the same land use history and soil type, metals concentrations, especially available concentrations, showed homogeneity. The nested sampling

  18. A methodology to support the decision to invest in spatially variable nitrogen fertilisation

    NARCIS (Netherlands)

    Smit, A.B.; Stoorvogel, J.J.; Wossink, G.A.A.

    2000-01-01

    This paper reports a methodology to define and select basic activities for spatially variable N-management, referred to as management tracks. Their main purpose is to support decision making whether or not to apply variable nitrogen fertilisation. The methodology is based on biophysical simulation o

  19. Climatic variability and spatial distribution of herbaceous fodders in the Sudanian zone of Benin (West Africa.

    Directory of Open Access Journals (Sweden)

    Myrèse C. Ahoudji

    2016-01-01

    Full Text Available This study focused on future spatial distributions of Andropogon gayanus, Loxodera ledermanii and Alysicarpus ovalifolius regarding bioclimatic variables in the Sudanian zone of Benin, particularly in the W Biosphere Reserve (WBR. These species were selected according to their importance for animals feed and the intensification of exploitation pressure induced change in their natural spatial distribution. Twenty (20 bioclimatic variables were tested and variables with high auto-correlation values were eliminated. Then, we retained seven climatic variables for the model. A MaxEnt (Maximum Entropy method was used to identify all climatic factors which determined the spatial distribution of the three species. Spatial distribution showed for Andropogon gayanus, a regression of high area distribution in detriment of low and moderate areas. The same trend was observed for Loxodera ledermannii spatial distribution. For Alysicarpus ovalifolius, currently area with moderate and low distribution were the most represented but map showed in 2050 that area with high distribution increased. We can deduce that without bioclimatic variables, others factors such as: biotic interactions, dispersion constraints, anthropic pressure, human activities and another historic factor determined spatial distribution of species. Modeling techniques that require only presence data are therefore extremely valuable.

  20. High-speed limnology: using advanced sensors to investigate spatial variability in biogeochemistry and hydrology.

    Science.gov (United States)

    Crawford, John T; Loken, Luke C; Casson, Nora J; Smith, Colin; Stone, Amanda G; Winslow, Luke A

    2015-01-06

    Advanced sensor technology is widely used in aquatic monitoring and research. Most applications focus on temporal variability, whereas spatial variability has been challenging to document. We assess the capability of water chemistry sensors embedded in a high-speed water intake system to document spatial variability. This new sensor platform continuously samples surface water at a range of speeds (0 to >45 km h(-1)) resulting in high-density, mesoscale spatial data. These novel observations reveal previously unknown variability in physical, chemical, and biological factors in streams, rivers, and lakes. By combining multiple sensors into one platform, we were able to detect terrestrial-aquatic hydrologic connections in a small dystrophic lake, to infer the role of main-channel vs backwater nutrient processing in a large river and to detect sharp chemical changes across aquatic ecosystem boundaries in a stream/lake complex. Spatial sensor data were verified in our examples by comparing with standard lab-based measurements of selected variables. Spatial fDOM data showed strong correlation with wet chemistry measurements of DOC, and optical NO3 concentrations were highly correlated with lab-based measurements. High-frequency spatial data similar to our examples could be used to further understand aquatic biogeochemical fluxes, ecological patterns, and ecosystem processes, and will both inform and benefit from fixed-site data.

  1. Measurements of spatial population synchrony: influence of time series transformations.

    Science.gov (United States)

    Chevalier, Mathieu; Laffaille, Pascal; Ferdy, Jean-Baptiste; Grenouillet, Gaël

    2015-09-01

    Two mechanisms have been proposed to explain spatial population synchrony: dispersal among populations, and the spatial correlation of density-independent factors (the "Moran effect"). To identify which of these two mechanisms is driving spatial population synchrony, time series transformations (TSTs) of abundance data have been used to remove the signature of one mechanism, and highlight the effect of the other. However, several issues with TSTs remain, and to date no consensus has emerged about how population time series should be handled in synchrony studies. Here, by using 3131 time series involving 34 fish species found in French rivers, we computed several metrics commonly used in synchrony studies to determine whether a large-scale climatic factor (temperature) influenced fish population dynamics at the regional scale, and to test the effect of three commonly used TSTs (detrending, prewhitening and a combination of both) on these metrics. We also tested whether the influence of TSTs on time series and population synchrony levels was related to the features of the time series using both empirical and simulated time series. For several species, and regardless of the TST used, we evidenced a Moran effect on freshwater fish populations. However, these results were globally biased downward by TSTs which reduced our ability to detect significant signals. Depending on the species and the features of the time series, we found that TSTs could lead to contradictory results, regardless of the metric considered. Finally, we suggest guidelines on how population time series should be processed in synchrony studies.

  2. Mapping the Centimeter-Scale Spatial Variability of PAHs and Microbial Populations in the Rhizosphere of Two Plants.

    Directory of Open Access Journals (Sweden)

    Amélia Bourceret

    Full Text Available Rhizoremediation uses root development and exudation to favor microbial activity. Thus it can enhance polycyclic aromatic hydrocarbon (PAH biodegradation in contaminated soils. Spatial heterogeneity of rhizosphere processes, mainly linked to the root development stage and to the plant species, could explain the contrasted rhizoremediation efficiency levels reported in the literature. Aim of the present study was to test if spatial variability in the whole plant rhizosphere, explored at the centimetre-scale, would influence the abundance of microorganisms (bacteria and fungi, and the abundance and activity of PAH-degrading bacteria, leading to spatial variability in PAH concentrations. Two contrasted rhizospheres were compared after 37 days of alfalfa or ryegrass growth in independent rhizotron devices. Almost all spiked PAHs were degraded, and the density of the PAH-degrading bacterial populations increased in both rhizospheres during the incubation period. Mapping of multiparametric data through geostatistical estimation (kriging revealed that although root biomass was spatially structured, PAH distribution was not. However a greater variability of the PAH content was observed in the rhizosphere of alfalfa. Yet, in the ryegrass-planted rhizotron, the Gram-positive PAH-degraders followed a reverse depth gradient to root biomass, but were positively correlated to the soil pH and carbohydrate concentrations. The two rhizospheres structured the microbial community differently: a fungus-to-bacterium depth gradient similar to the root biomass gradient only formed in the alfalfa rhizotron.

  3. How does spatial study design influence density estimates from spatial capture-recapture models?

    Directory of Open Access Journals (Sweden)

    Rahel Sollmann

    Full Text Available When estimating population density from data collected on non-invasive detector arrays, recently developed spatial capture-recapture (SCR models present an advance over non-spatial models by accounting for individual movement. While these models should be more robust to changes in trapping designs, they have not been well tested. Here we investigate how the spatial arrangement and size of the trapping array influence parameter estimates for SCR models. We analysed black bear data collected with 123 hair snares with an SCR model accounting for differences in detection and movement between sexes and across the trapping occasions. To see how the size of the trap array and trap dispersion influence parameter estimates, we repeated analysis for data from subsets of traps: 50% chosen at random, 50% in the centre of the array and 20% in the South of the array. Additionally, we simulated and analysed data under a suite of trap designs and home range sizes. In the black bear study, we found that results were similar across trap arrays, except when only 20% of the array was used. Black bear density was approximately 10 individuals per 100 km(2. Our simulation study showed that SCR models performed well as long as the extent of the trap array was similar to or larger than the extent of individual movement during the study period, and movement was at least half the distance between traps. SCR models performed well across a range of spatial trap setups and animal movements. Contrary to non-spatial capture-recapture models, they do not require the trapping grid to cover an area several times the average home range of the studied species. This renders SCR models more appropriate for the study of wide-ranging mammals and more flexible to design studies targeting multiple species.

  4. Dust deposition and ambient PM10 concentration in northwest China: spatial and temporal variability

    Science.gov (United States)

    Zhang, Xiao-Xiao; Sharratt, Brenton; Chen, Xi; Wang, Zi-Fa; Liu, Lian-You; Guo, Yu-Hong; Li, Jie; Chen, Huan-Sheng; Yang, Wen-Yi

    2017-02-01

    Eolian dust transport and deposition are important geophysical processes which influence global bio-geochemical cycles. Currently, reliable deposition data are scarce in central and east Asia. Located at the boundary of central and east Asia, Xinjiang Province of northwestern China has long played a strategic role in cultural and economic trade between Asia and Europe. In this paper, we investigated the spatial distribution and temporal variation in dust deposition and ambient PM10 (particulate matter in aerodynamic diameter ≤ 10 µm) concentration from 2000 to 2013 in Xinjiang Province. This variation was assessed using environmental monitoring records from 14 stations in the province. Over the 14 years, annual average dust deposition across stations in the province ranged from 255.7 to 421.4 t km-2. Annual dust deposition was greater in southern Xinjiang (663.6 t km-2) than northern (147.8 t km-2) and eastern Xinjiang (194.9 t km-2). Annual average PM10 concentration across stations in the province varied from 100 to 196 µg m-3 and was 70, 115 and 239 µg m-3 in northern, eastern and southern Xinjiang, respectively. The highest annual dust deposition (1394.1 t km-2) and ambient PM10 concentration (352 µg m-3) were observed in Hotan, which is located in southern Xinjiang and at the southern boundary of the Taklamakan Desert. Dust deposition was more intense during the spring and summer than other seasons. PM10 was the main air pollutant that significantly influenced regional air quality. Annual average dust deposition increased logarithmically with ambient PM10 concentration (R2 ≥ 0.81). While the annual average dust storm frequency remained unchanged from 2000 to 2013, there was a positive relationship between dust storm days and dust deposition and PM10 concentration across stations. This study suggests that sand storms are a major factor affecting the temporal variability and spatial distribution of dust deposition in northwest China.

  5. Spatial variability change of MgO content in Jelsava magnesite deposit (Slovakia)

    OpenAIRE

    J. Kondela; Jacko, S.; L. Vizi

    2017-01-01

    The presented paper deals with the study of the spatial variability changes of MgO content within the Jelšava magnesite deposit in Slovakia. The geostatistical structural analysis was used to study the spatial variability changes of the MgO content within three mining sectors A, B and C, localised in different parts of the deposit. The results show some important connections between the variability of MgO content and the structure setting of the deposit with utilization for the magnesite proc...

  6. Tannat grape composition responses to spatial variability of temperature in an Uruguay's coastal wine region

    Science.gov (United States)

    Fourment, Mercedes; Ferrer, Milka; González-Neves, Gustavo; Barbeau, Gérard; Bonnardot, Valérie; Quénol, Hervé

    2017-05-01

    Spatial variability of temperature was studied in relation to the berry basic composition and secondary compounds of the Tannat cultivar at harvest from vineyards located in Canelones and Montevideo, the most important wine region of Uruguay. Monitoring of berries and recording of temperature were performed in 10 commercial vineyards of Tannat situated in the southern coastal wine region of the country for three vintages (2012, 2013, and 2014). Results from a multivariate correlation analysis between berry composition and temperature over the three vintages showed that (1) Tannat responses to spatial variability of temperature were different over the vintages, (2) correlations between secondary metabolites and temperature were higher than those between primary metabolites, and (3) correlation values between berry composition and climate variables increased when ripening occurred under dry conditions (below average rainfall). For a particular studied vintage (2013), temperatures explained 82.5% of the spatial variability of the berry composition. Daily thermal amplitude was found to be the most important spatial mode of variability with lower values recorded at plots nearest to the sea and more exposed to La Plata River. The highest levels in secondary compounds were found in berries issued from plots situated as far as 18.3 km from La Plata River. The increasing knowledge of temperature spatial variability and its impact on grape berry composition contributes to providing possible issues to adapt grapevine to climate change.

  7. Spatial relationships between polychaete assemblages and environmental variables over broad geographical scales.

    Directory of Open Access Journals (Sweden)

    Lisandro Benedetti-Cecchi

    Full Text Available This study examined spatial relationships between rocky shore polychaete assemblages and environmental variables over broad geographical scales, using a database compiled within the Census of Marine Life NaGISA (Natural Geography In Shore Areas research program. The database consisted of abundance measures of polychaetes classified at the genus and family levels for 74 and 93 sites, respectively, from nine geographic regions. We tested the general hypothesis that the set of environmental variables emerging as potentially important drivers of variation in polychaete assemblages depend on the spatial scale considered. Through Moran's eigenvector maps we indentified three submodels reflecting spatial relationships among sampling sites at intercontinental (>10,000 km, continental (1000-5000 km and regional (20-500 km scales. Using redundancy analysis we found that most environmental variables contributed to explain a large and significant proportion of variation of the intercontinental submodel both for genera and families (54% and 53%, respectively. A subset of these variables, organic pollution, inorganic pollution, primary productivity and nutrient contamination was also significantly related to spatial variation at the continental scale, explaining 25% and 32% of the variance at the genus and family levels, respectively. These variables should therefore be preferably considered when forecasting large-scale spatial patterns of polychaete assemblages in relation to ongoing or predicted changes in environmental conditions. None of the variables considered in this study were significantly related to the regional submodel.

  8. Identifying Spatially Variable Sensitivity of Model Predictions and Calibrations

    Science.gov (United States)

    McKenna, S. A.; Hart, D. B.

    2005-12-01

    Stochastic inverse modeling provides an ensemble of stochastic property fields, each calibrated to measured steady-state and transient head data. These calibrated fields are used as input for predictions of other processes (e.g., contaminant transport, advective travel time). Use of the entire ensemble of fields transfers spatial uncertainty in hydraulic properties to uncertainty in the predicted performance measures. A sampling-based sensitivity coefficient is proposed to determine the sensitivity of the performance measures to the uncertain values of hydraulic properties at every cell in the model domain. The basis of this sensitivity coefficient is the Spearman rank correlation coefficient. Sampling-based sensitivity coefficients are demonstrated using a recent set of transmissivity (T) fields created through a stochastic inverse calibration process for the Culebra dolomite in the vicinity of the WIPP site in southeastern New Mexico. The stochastic inverse models were created using a unique approach to condition a geologically-based conceptual model of T to measured T values via a multiGaussian residual field. This field is calibrated to both steady-state and transient head data collected over an 11 year period. Maps of these sensitivity coefficients provide a means of identifying the locations in the study area to which both the value of the model calibration objective function and the predicted travel times to a regulatory boundary are most sensitive to the T and head values. These locations can be targeted for deployment of additional long-term monitoring resources. Comparison of areas where the calibration objective function and the travel time have high sensitivity shows that these are not necessarily coincident with regions of high uncertainty. The sampling-based sensitivity coefficients are compared to analytically derived sensitivity coefficients at the 99 pilot point locations. Results of the sensitivity mapping exercise are being used in combination

  9. Riparian zone processes and soil water total organic carbon (TOC: implications for spatial variability, upscaling and carbon exports

    Directory of Open Access Journals (Sweden)

    T. Grabs

    2012-03-01

    Full Text Available Groundwater flowing from hillslopes through riparian (near stream soils often undergoes chemical transformations that can substantially influence stream water chemistry. We used landscape analysis to predict total organic carbon (TOC concentrations profiles and groundwater levels measured in the riparian zone (RZ of a 67 km2 catchment in Sweden. TOC exported from 13 riparian soil profiles was then estimated based on the riparian flow-concentration integration model (RIM. Much of the observed spatial variability of riparian TOC concentrations in this system could be predicted from groundwater levels and the topographic wetness index (TWI. Organic riparian peat soils in forested areas emerged as hotspots exporting large amounts of TOC. Exports were subject to considerable temporal variations caused by a combination of variable flow conditions and changing soil water TOC concentrations. From more mineral riparian gley soils, on the other hand, only small amounts with relatively time-invariant concentrations were exported. Organic and mineral soils in RZs constitute a heterogeneous landscape mosaic that controls much of the spatial variability of stream water TOC. We developed an empirical regression-model based on the TWI to move beyond the plot scale to predict spatially variable riparian TOC concentration profiles for RZs underlain by glacial till.

  10. The influence of various distracting stimuli on spatial working memory

    Directory of Open Access Journals (Sweden)

    Martina Starc

    2016-01-01

    Full Text Available Protecting information from distraction is essential for optimal performance of working memory. We examined how the presence of distracting stimuli influences spatial working memory and compared the effect of both task-similar and negatively emotionally salient distractors. We checked the effect of distractors on the accuracy of high-resolution representations, as well as the maintenance of spatial categories, and more precisely defined not only the existence but also the direction of the distracting influences (towards or away from the position of the distractor. Participants (n = 25, 8 men, 19–31 years old were asked to remember the exact position of a target scrambled image and recall it with a joystick after a delay. In some trials an additional distracting image (scrambled, neutral or negative was shown during the delay. We measured the spread of responses (standard deviation of angular error and shifts of the average response towards the prototype angles (45° or towards the position of distractors. Distracting stimuli did not affect the spread of responses and decreased the tendency of participants to move the responses towards the prototype angle. Different types of distractors did not differ in this effect. Contrary to expectations, the participants moved their responses away from the position of distractors; this effect was more pronounced for negative distractors. In addition to memorizing the exact position and maintaining attention on the position of the stimulus, participants are likely to strategically use information about spatial category membership (quadrants and information about the position of the distractor. The repulsive effect of the distractor likely results from inhibition of its position and indicates the need to supplement computational models of spatial working memory and to take into account different strategies of working memory use.

  11. Herbivore-Alga Interaction Strength Influences Spatial Heterogeneity in a Kelp-Dominated Intertidal Community.

    Directory of Open Access Journals (Sweden)

    Moisés A Aguilera

    Full Text Available There is a general consensus that marine herbivores can affect algal species composition and abundance, but little empirical work exists on the role of herbivores as modifiers of the spatial structure of resource assemblages. Here, we test the consumption/bulldozing effects of the molluscan grazer Enoplochiton niger and its influence on the spatial structure of a low intertidal community dominated by the bull kelp Durvillaea antarctica and the kelp Lessonia spicata. Through field experiments conducted at a rocky intertidal shore in north-central Chile (~30°-32°S, the edge of the grazer and algae geographic distributions, we estimated the strength and variability of consumptive effects of the grazer on different functional group of algae. We also used data from abundance field surveys to evaluate spatial co-occurrence patterns of the study species. Exclusion-enclosure experiments showed that E. niger maintained primary space available by preventing algal colonization, even of large brown algae species. The grazing activity of E. niger also reduced spatial heterogeneity of the ephemeral algal species, increasing bare space availability and variability through time in similar ways to those observed for the collective effect with other grazers. Overall, our result suggests that E. niger can be considered an important modifier of the spatial structure of the large brown algae-dominated community. Effects of E. niger on resource variability seem to be directly related to its foraging patterns, large body size, and population densities, which are all relevant factors for management and conservation of the large brown algae community. Our study thus highlights the importance of considering functional roles and identity of generalist consumers on spatial structure of the entire landscape.

  12. Herbivore-Alga Interaction Strength Influences Spatial Heterogeneity in a Kelp-Dominated Intertidal Community.

    Science.gov (United States)

    Aguilera, Moisés A; Valdivia, Nelson; Broitman, Bernardo R

    2015-01-01

    There is a general consensus that marine herbivores can affect algal species composition and abundance, but little empirical work exists on the role of herbivores as modifiers of the spatial structure of resource assemblages. Here, we test the consumption/bulldozing effects of the molluscan grazer Enoplochiton niger and its influence on the spatial structure of a low intertidal community dominated by the bull kelp Durvillaea antarctica and the kelp Lessonia spicata. Through field experiments conducted at a rocky intertidal shore in north-central Chile (~30°-32°S), the edge of the grazer and algae geographic distributions, we estimated the strength and variability of consumptive effects of the grazer on different functional group of algae. We also used data from abundance field surveys to evaluate spatial co-occurrence patterns of the study species. Exclusion-enclosure experiments showed that E. niger maintained primary space available by preventing algal colonization, even of large brown algae species. The grazing activity of E. niger also reduced spatial heterogeneity of the ephemeral algal species, increasing bare space availability and variability through time in similar ways to those observed for the collective effect with other grazers. Overall, our result suggests that E. niger can be considered an important modifier of the spatial structure of the large brown algae-dominated community. Effects of E. niger on resource variability seem to be directly related to its foraging patterns, large body size, and population densities, which are all relevant factors for management and conservation of the large brown algae community. Our study thus highlights the importance of considering functional roles and identity of generalist consumers on spatial structure of the entire landscape.

  13. Exploring the spatial variability of soil properties in an Alfisol Catena

    Energy Technology Data Exchange (ETDEWEB)

    Rosemary, F.; Vitharana, U. W. A.; Indraratne, S. P.; Weerasooriya, R.; Mishra, U.

    2016-11-10

    Detailed digital soil maps showing the spatial heterogeneity of soil properties consistent with the landscape are required for site-specific management of plant nutrients, land use planning and process-based environmental modeling. We characterized the short-scale spatial heterogeneity of soil properties in an Alfisol catena in a tropical landscape of Sri Lanka. The impact of different land-uses (paddy, vegetable and un-cultivated) was examined to assess the impact of anthropogenic activities on the variability of soil properties at the catenary level. Conditioned Latin hypercube sampling was used to collect 58 geo-referenced topsoil samples (0–30 cm) from the study area. Soil samples were analyzed for pH, electrical conductivity (EC), organic carbon (OC), cation exchange capacity (CEC) and texture. The spatial correlation between soil properties was analyzed by computing crossvariograms and subsequent fitting of theoretical model. Spatial distribution maps were developed using ordinary kriging. The range of soil properties, pH: 4.3–7.9; EC: 0.01–0.18 dS m–1 ; OC: 0.1–1.37%; CEC: 0.44– 11.51 cmol (+) kg–1 ; clay: 1.5–25% and sand: 59.1–84.4% and their coefficient of variations indicated a large variability in the study area. Electrical conductivity and pH showed a strong spatial correlation which was reflected by the cross-variogram close to the hull of the perfect correlation. Moreover, cross-variograms calculated for EC and Clay, CEC and OC, CEC and clay and CEC and pH indicated weak positive spatial correlation between these properties. Relative nugget effect (RNE) calculated from variograms showed strongly structured spatial variability for pH, EC and sand content (RNE < 25%) while CEC, organic carbon and clay content showed moderately structured spatial variability (25% < RNE < 75%). Spatial dependencies for examined soil properties ranged from 48 to 984 m. The mixed effects model fitting followed by Tukey's post

  14. Socio-economic variables that influence participation of women in ...

    African Journals Online (AJOL)

    Socio-economic variables that influence participation of women in rural ... Rural development is a strategy designed to improve the social and economic life of the rural ... Educational qualification (t=2.55) and leadership position (t= 2.34) were ...

  15. Tidal and spatial variability of nitrous oxide (N2O) in Sado estuary (Portugal)

    Science.gov (United States)

    Gonçalves, Célia; Brogueira, Maria José; Nogueira, Marta

    2015-12-01

    The estimate of the nitrous oxide (N2O) fluxes is fundamental to assess its impact on global warming. The tidal and spatial variability of N2O and the air-sea fluxes in the Sado estuary in July/August 2007 are examined. Measurements of N2O and other relevant environmental parameters (temperature, salinity, dissolved oxygen and dissolved inorganic nitrogen - nitrate plus nitrite and ammonium) were recorded during two diurnal tidal cycles performed in the Bay and Marateca region and along the estuary during ebb, at spring tide. N2O presented tidal and spatial variability and varied spatially from 5.0 nmol L-1 in Marateca region to 12.5 nmol L-1 in Sado river input. Although the Sado river may constitute a considerable N2O source to the estuary, the respective chemical signal discharge was rapidly lost in the main body of the estuary due to the low river flow during the sampling period. N2O varied with tide similarly between 5.2 nmol L-1 (Marateca) and 10.0 nmol L-1 (Sado Bay), with the maximum value reached two hours after flooding period. The influence of N2O enriched upwelled seawater (˜10.0 nmol L-1) was well visible in the estuary mouth and apparently represented an important contribution of N2O in the main body of Sado estuary. Despite the high water column oxygen saturation in most of Sado estuary, nitrification did not seem a relevant process for N2O production, probably as the concentration of the substrate, NH4+, was not adequate for this process to occur. Most of the estuary functioned as a N2O source, and only Marateca zone has acted as N2O sink. The N2O emission from Sado estuary was estimated to be 3.7 Mg N-N2O yr-1 (FC96) (4.4 Mg N-N2O yr-1, FRC01). These results have implications for future sampling and scaling strategies for estimating greenhouse gases (GHGs) fluxes in tidal ecosystems.

  16. Spatial variability and influencing factors of soil catalase activity in grapevine fields in Huailai-Zhuolu Basin%怀涿葡萄产区土壤过氧化氢酶活性空间分布规律及影响因素分析

    Institute of Scientific and Technical Information of China (English)

    马堃; 李橙; 肖凡; 冯圣东; 杨志新

    2013-01-01

    This study assessed the physicochemical factors influencing the spatial variability of soil catalase activity in grapevine fields.83 samples of 0~20 cm soil layer was collected from grapevine fields in the Huailai-Zhuolu basin (HZB) of Hebei,China.Geostatistics and GIS environments were used to analyze the spatial variability of soil catalase activity for different combinations of grape variety and soil property.Also the contributing factors to enzyme activity were analyzed.The results showed strongly spatial correlation of catalase activity in 0~20 cm soil layer of grapevine field in HZB.The variations of catalase activity in the study area tracked a zonal distribution,gradually decreasing from west to east along river courses.Based on semi-variance analysis,the best-fitted model for soil catalase activity distribution in the study area was an exponential model.With the exception of potassium,all macro-elements,micro-elements,quantitative elements,heavy metals and other beneficial elements had a significant positive activation effect on soil catalase activity in grapevine fields.In traditional soil-grape cropping systems,catalase activity was closely correlated with the distribution characteristics of most elements at different locations in grapevine fields.Also a significant positive correlation was noted between catalase activity and fine sand content.A highly significant positive correlation was noted between catalase activity and clay.The physical properties,especially clay and fine sand content,were other critical factors that influenced the spatial variability of soil catalase activity.Ggrape varieties and soil pH were not correlated with spatial variability of soil catalase activity.%为了探明影响土壤过氧化氢酶活性空间变异规律的葡萄品种、土壤物理、化学因素及其内在关系,本文利用GIS和地统计学分析方法研究了怀涿葡萄产区(河北省怀来、涿鹿两县)的83个表层土壤样品.结果表明:怀

  17. Multi-taxa integrated landscape genetics for zoonotic infectious diseases: deciphering variables influencing disease emergence.

    Science.gov (United States)

    Leo, Sarah S T; Gonzalez, Andrew; Millien, Virginie

    2016-05-01

    Zoonotic disease transmission systems involve sets of species interacting with each other and their environment. This complexity impedes development of disease monitoring and control programs that require reliable identification of spatial and biotic variables and mechanisms facilitating disease emergence. To overcome this difficulty, we propose a framework that simultaneously examines all species involved in disease emergence by integrating concepts and methods from population genetics, landscape ecology, and spatial statistics. Multi-taxa integrated landscape genetics (MTILG) can reveal how interspecific interactions and landscape variables influence disease emergence patterns. We test the potential of our MTILG-based framework by modelling the emergence of a disease system across multiple species dispersal, interspecific interaction, and landscape scenarios. Our simulations showed that both interspecific-dependent dispersal patterns and landscape characteristics significantly influenced disease spread. Using our framework, we were able to detect statistically similar inter-population genetic differences and highly correlated spatial genetic patterns that imply species-dependent dispersal. Additionally, species that were assigned coupled-dispersal patterns were affected to the same degree by similar landscape variables. This study underlines the importance of an integrated approach to investigating emergence of disease systems. MTILG is a robust approach for such studies and can identify potential avenues for targeted disease management strategies.

  18. Spatial Scaling of Environmental Variables Improves Species-Habitat Models of Fishes in a Small, Sand-Bed Lowland River.

    Directory of Open Access Journals (Sweden)

    Johannes Radinger

    Full Text Available Habitat suitability and the distinct mobility of species depict fundamental keys for explaining and understanding the distribution of river fishes. In recent years, comprehensive data on river hydromorphology has been mapped at spatial scales down to 100 m, potentially serving high resolution species-habitat models, e.g., for fish. However, the relative importance of specific hydromorphological and in-stream habitat variables and their spatial scales of influence is poorly understood. Applying boosted regression trees, we developed species-habitat models for 13 fish species in a sand-bed lowland river based on river morphological and in-stream habitat data. First, we calculated mean values for the predictor variables in five distance classes (from the sampling site up to 4000 m up- and downstream to identify the spatial scale that best predicts the presence of fish species. Second, we compared the suitability of measured variables and assessment scores related to natural reference conditions. Third, we identified variables which best explained the presence of fish species. The mean model quality (AUC = 0.78, area under the receiver operating characteristic curve significantly increased when information on the habitat conditions up- and downstream of a sampling site (maximum AUC at 2500 m distance class, +0.049 and topological variables (e.g., stream order were included (AUC = +0.014. Both measured and assessed variables were similarly well suited to predict species' presence. Stream order variables and measured cross section features (e.g., width, depth, velocity were best-suited predictors. In addition, measured channel-bed characteristics (e.g., substrate types and assessed longitudinal channel features (e.g., naturalness of river planform were also good predictors. These findings demonstrate (i the applicability of high resolution river morphological and instream-habitat data (measured and assessed variables to predict fish presence, (ii the

  19. Spatial Scaling of Environmental Variables Improves Species-Habitat Models of Fishes in a Small, Sand-Bed Lowland River.

    Science.gov (United States)

    Radinger, Johannes; Wolter, Christian; Kail, Jochem

    2015-01-01

    Habitat suitability and the distinct mobility of species depict fundamental keys for explaining and understanding the distribution of river fishes. In recent years, comprehensive data on river hydromorphology has been mapped at spatial scales down to 100 m, potentially serving high resolution species-habitat models, e.g., for fish. However, the relative importance of specific hydromorphological and in-stream habitat variables and their spatial scales of influence is poorly understood. Applying boosted regression trees, we developed species-habitat models for 13 fish species in a sand-bed lowland river based on river morphological and in-stream habitat data. First, we calculated mean values for the predictor variables in five distance classes (from the sampling site up to 4000 m up- and downstream) to identify the spatial scale that best predicts the presence of fish species. Second, we compared the suitability of measured variables and assessment scores related to natural reference conditions. Third, we identified variables which best explained the presence of fish species. The mean model quality (AUC = 0.78, area under the receiver operating characteristic curve) significantly increased when information on the habitat conditions up- and downstream of a sampling site (maximum AUC at 2500 m distance class, +0.049) and topological variables (e.g., stream order) were included (AUC = +0.014). Both measured and assessed variables were similarly well suited to predict species' presence. Stream order variables and measured cross section features (e.g., width, depth, velocity) were best-suited predictors. In addition, measured channel-bed characteristics (e.g., substrate types) and assessed longitudinal channel features (e.g., naturalness of river planform) were also good predictors. These findings demonstrate (i) the applicability of high resolution river morphological and instream-habitat data (measured and assessed variables) to predict fish presence, (ii) the

  20. Monitoring meteorological spatial variability in viticulture using a low-cost Wireless Sensor Network

    Science.gov (United States)

    Matese, Alessandro; Crisci, Alfonso; Di Gennaro, Filippo; Primicerio, Jacopo; Tomasi, Diego; Guidoni, Silvia

    2014-05-01

    In a long-term perspective, the current global agricultural scenario will be characterize by critical issues in terms of water resource management and environmental protection. The concept of sustainable agriculture would become crucial at reducing waste, optimizing the use of pesticides and fertilizers to crops real needs. This can be achieved through a minimum-scale monitoring of the crop physiologic status and the environmental parameters that characterize the microclimate. Viticulture is often subject to high variability within the same vineyard, thus becomes important to monitor this heterogeneity to allow a site-specific management and maximize the sustainability and quality of production. Meteorological variability expressed both at vineyard scale (mesoclimate) and at single plant level (microclimate) plays an important role during the grape ripening process. The aim of this work was to compare temperature, humidity and solar radiation measurements at different spatial scales. The measurements were assessed for two seasons (2011, 2012) in two vineyards of the Veneto region (North-East Italy), planted with Pinot gris and Cabernet Sauvignon using a specially designed and developed Wireless Sensor Network (WSN). The WSN consists of various levels: the Master/Gateway level coordinates the WSN and performs data aggregation; the Farm/Server level takes care of storing data on a server, data processing and graphic rendering. Nodes level is based on a network of peripheral nodes consisting of a sensor board equipped with sensors and wireless module. The system was able to monitor the agrometeorological parameters in the vineyard: solar radiation, air temperature and air humidity. Different sources of spatial variation were studied, from meso-scale to micro-scale. A widespread investigation was conducted, building a factorial design able to evidence the role played by any factor influencing the physical environment in the vineyard, such as the surrounding climate

  1. Temporal and spatial variability of soil biological activity at European scale

    Science.gov (United States)

    Mallast, Janine; Rühlmann, Jörg

    2015-04-01

    The CATCH-C project aims to identify and improve the farm-compatibility of Soil Management Practices including to promote productivity, climate change mitigation and soil quality. The focus of this work concentrates on turnover conditions for soil organic matter (SOM). SOM is fundamental for the maintenance of quality and functions of soils while SOM storage is attributed a great importance in terms of climate change mitigation. The turnover conditions depend on soil biological activity characterized by climate and soil properties. Soil biological activity was investigated using two model concepts: a) Re_clim parameter within the ICBM (Introductory Carbon Balance Model) (Andrén & Kätterer 1997) states a climatic factor summarizing soil water storage and soil temperature and its influence on soil biological activity. b) BAT (biological active time) approach derived from model CANDY (CArbon and Nitrogen Dynamic) (Franko & Oelschlägel 1995) expresses the variation of soil moisture, soil temperature and soil aeration as a time scale and an indicator of biological activity for soil organic matter (SOM) turnover. During an earlier stage both model concepts, Re_clim and BAT, were applied based on a monthly data to assess spatial variability of turnover conditions across Europe. This hampers the investigation of temporal variability (e.g. intra-annual). The improved stage integrates daily data of more than 350 weather stations across Europe presented by Klein Tank et al. (2002). All time series data (temperature, precipitation and potential evapotranspiration and soil texture derived from the European Soil Database (JRC 2006)), are used to calculate soil biological activity in the arable layer. The resulting BAT and Re_clim values were spatio-temporal investigated. While "temporal" refers to a long-term trend analysis, "spatial" includes the investigation of soil biological activity variability per environmental zone (ENZ, Metzger et al. 2005 representing similar

  2. Spatial variability of available water and micro-sprinkler irrigation in cambisol

    Directory of Open Access Journals (Sweden)

    Larissa Luana Nicodemos Ferreira

    Full Text Available ABSTRACT The technology of irrigation is vital for agricultural production. Thus, description of spatial patterns of both water application and available water capacity in the soil, as well as their interactions, is essential to maximize efficiency of water use in irrigated areas. The objective of this study was to analyze spatial variability of available water capacity in the soil and water application via irrigation using geostatistics. The experiment was conducted in a commercial mango orchard in Cambisol irrigated by micro sprinkler system, in the municipality of Alto do Rodrigues, RN. Analyses of descriptive statistics and geostatistics were performed using the programs GeoR and GS+. Geostatistics was found suitable for describing the structure of spatial dependence of available water capacity in the soil and the flow rate distributed in the area by sprinklers. Moreover, even with good results for Christiansen Uniformity Coefficient (CU and Distribution Uniformity Coefficient (DU, the area showed spatial variability of flow rate.

  3. Characterization of the Spatial Variability of Methane, Ozone, and Carbon Dioxide in Two Oil and Gas Production Basins Via a Spatial Grid of Continuous Measurements

    Science.gov (United States)

    Casey, J. G.; Collier, A. M.; Hannigan, M.; Piedrahita, R.; Vaughn, B. H.; Sherwood, O.

    2015-12-01

    In recent years, aided by the advent of horizontal drilling used in conjunction with hydraulic fracturing, oil and gas production in basins around the United States has increased significantly. A study was conducted in two oil and gas basins during the spring and summer of 2015 to investigate the spatial and temporal variability of several atmospheric trace gases that can be influenced by oil and gas extraction including methane, ozone, and carbon dioxide. Fifteen air quality monitors were distributed across the Denver Julesburg Basin in Northeast Colorado, and the San Juan Basin, which stretches from Southwest Colorado into Northwest New Mexico in Four Corners Region. Spatial variability in ozone was observed across each basin. The presence of dynamic short-term trends observed in the mole fraction of methane and carbon dioxide indicate the extent to which each site is uniquely impacted by local emission sources. Diurnal trends of these two constituents lead toward a better understanding of local pooling of emissions that can be influenced by topography, the planetary boundary layer height, atmospheric stability, as well as the composition and flux of local and regional emissions sources.

  4. Multi-spatial variability modes of the Atlantic Meridional Overturning Circulation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Tianjun

    2003-01-01

    The multi-spatial variability modes of the Atlantic Meridional Overturning Circulation (MOC) are identified in the natural coupled simulation of two climate models, the MOC either oscillates at decadal scales with strong cross- equatorial flow or fluctuates locally at interannual scales with weaker cross-equatorial flow. Former studies mainly emphasize the paleo-environmental and paleo-climatic impacts of the meridional overturning states transition; this analysis indicates the existence of the multi-spatial variability modes of the MOC at interannual to decadal scales. Further analysis indicates that the conventionally used MOC index, which is defined as the maximum zonal mean meridional stream-function of the North Atlantic, cannot properly describe the multi-spatial variability characteristics of the MOC.

  5. Spatial variability and uncertainty in ecological risk assessment: a case study on the potential risk of cadmium for the little owl in a Dutch river flood plain.

    Science.gov (United States)

    Kooistra, Lammert; Huijbregts, Mark A J; Ragas, Ad M J; Wehrens, Ron; Leuven, Rob S E W

    2005-04-01

    This paper outlines a procedure that quantifies the impact of different sources of spatial variability and uncertainty on ecological risk estimates. The procedure is illustrated in a case study that estimates the risks of cadmium for a little owl (Athene noctua vidalli) living in a Dutch river flood plain along the river Rhine. A geographical information system (GIS) was used to quantify spatial variability in contaminant concentrations and habitats. It was combined with an exposure and effect model that uses Monte Carlo simulation to quantify parameter uncertainty. Spatial model uncertainty was assessed by the application of two different spatial interpolation methods (classification and kriging) and foraging ranges. The results of the case study show that parameter uncertainty is the main type of uncertainty influencing the risk estimate, and to a lesser extent spatial variability, while spatial model uncertainty was of minor importance. Compared to the deterministically calculated hazard index for the little owl (0.9), inclusion of spatial variability resulted in a median hazard index that can vary between 0.8 and 1.4. It is concluded that a single estimator for a whole flood plain may over- or underestimate risks for specific parts within the flood plain. Further research that expands the procedure presented in this paper is necessary to improve the incorporation of spatial factors in ecological risk assessment.

  6. Spatial Variability of Soil Cation Exchange Capacity in Hilly Tea Plantation Soils Under Different Sampling Scales

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Studies on the spatial variability of the soil cation exchange capacity (CEC) were made to provide a theoretical basis for an ecological tea plantation and management of soil fertilizer in the tea plantation. Geostatistics were used to analyze the spatial variability of soil CEC in the tea plantation site on Mengding Mountain in Sichuan Province of China on two sampling scales. It was found that, (1) on the small scale, the soil CEC was intensively spatially correlative, the rate of nugget to sill was 18.84% and the spatially dependent range was 1 818 m, and structural factors were the main factors that affected the spatial variability of the soil CEC; (2) on the microscale, the soil CEC was also consumingly spatially dependent,and the rate of nugget to sill was 16.52%, the spatially dependent range was 311 m, and the main factors affecting the spatial variability were just the same as mentioned earlier. On the small scale, soil CEC had a stronger anisotropic structure on the slope aspect, and a weaker one on the lateral side. According to the ordinary Kriging method, the equivalence of soil CEC distributed along the lateral aspect of the slope from northeast to outhwest, and the soil CEC reduced as the elevation went down. On the microscale, the anisotropic structure was different from that measured on the small scale. It had a stronger anisotropic structure on the aspect that was near the aspect of the slope, and a weaker one near the lateral aspect of the slope. The soil CEC distributed along the lateral aspect of the slope and some distributed in the form of plots.From the top to the bottom of the slope, the soil CEC increased initially, and then reduced, and finally increased.

  7. Temporal Trends and Spatial Variability of Vegetation Phenology over the Northern Hemisphere during 1982-2012

    OpenAIRE

    Siyuan Wang; Bojuan Yang; Qichun Yang; Linlin Lu; Xiaoyue Wang; Yaoyao Peng

    2016-01-01

    Satellite-derived vegetation phenology has been recognized as a key indicator for detecting changes in the terrestrial biosphere in response to global climate change. However, multi-decadal changes and spatial variation of vegetation phenology over the Northern Hemisphere and their relationship to climate change have not yet been fully investigated. In this article, we investigated the spatial variability and temporal trends of vegetation phenology over the Northern Hemisphere by calibrating ...

  8. Spatial variability of soil attributes and sugarcane yield in relation to topographic location

    OpenAIRE

    de Souza, Zigomar M.; Domingos G. P. Cerri; Paulo S. G. Magalhães; Siqueira, Diego S.

    2010-01-01

    Soils submitted to the same management system in places with little variation of landscape, manifest differentiated spatial variability of their attributes and crop yield. The aim of this work was to investigate the correlation between spatial variability of the soil attributes and sugarcane yield as a result of soil topography. To achieve this objective, a test area of 42 ha located at the São João Sugar Mill, in Araras, in the State of São Paulo, Brazil, was selected. Sugarcane yield was me...

  9. Spatial aggregation for crop modelling at regional scales: the effects of soil variability

    Science.gov (United States)

    Coucheney, Elsa; Villa, Ana; Eckersten, Henrik; Hoffmann, Holger; Jansson, Per-Erik; Gaiser, Thomas; Ewert, Franck; Lewan, Elisabet

    2017-04-01

    Modelling agriculture production and adaptation to the environment at regional or global scale receives much interest in the context of climate change. Process-based soil-crop models describe the flows of mass (i.e. water, carbon and nitrogen) and energy in the soil-plant-atmosphere system. As such, they represent valuable tools for predicting agricultural production in diverse agro-environmental contexts as well as for assessing impacts on the environment; e.g. leaching of nitrates, changes in soil carbon content and GHGs emissions. However, their application at regional and global scales for climate change impact studies raises new challenges related to model input data, calibration and evaluation. One major concern is to take into account the spatial variability of the environmental conditions (e.g. climate, soils, management practices) used as model input and because the impacts of climate change on cropping systems depend strongly on the site conditions and properties (1). For example climate change effects on yield can be either negative or positive depending on the soil type (2). Additionally, the use of different methods of upscaling and downscaling adds new sources of modelling uncertainties (3). In the present study, the effect of aggregating soil input data by area majority of soil mapping units was explored for spatially gridded simulations with the soil-vegetation model CoupModel for a region in Germany (North Rhine-Westphalia, NRW). The data aggregation effect (DAE) was analysed for wheat yield, water drainage, soil carbon mineralisation and nitrogen leaching below the root zone. DAE was higher for soil C and N variables than for yield and drainage and were strongly related to the spatial coverage of specific soils within the study region. These 'key soils' were identified by a model sensitivity analysis to soils present in the NRW region. The spatial aggregation of the key soils additionally influenced the DAE. Our results suggest that a spatial

  10. Spatial variability of throughfall and raindrops under a single canopy with different canopy structure

    Science.gov (United States)

    Nanko, Kazuki; Onda, Yuichi; Ito, Akane; Moriwaki, Hiromu

    2013-04-01

    To evaluate the spatial variability of throughfall amount, raindrops, and erosivity under a single canopy during calm meteorological conditions, indoor experiments were conducted using a 9.8-m-tall transplanted Japanese cypress (Chamaecyparis obtusa) and a large-scale rainfall simulator. Drop size distribution, drop velocity, and kinetic energy of throughfall varied spatially under a single canopy as did throughfall amount and rain rate. Compared with throughfall rain rate, the variability was similar in drop size distribution, lower in drop velocity, and higher in kinetic energy. The results suggest that the spatial distribution of throughfall amount was dominated by the canopy shape and position of branches inside the canopy, and thus the spatial distribution was correlated with the radial distance from the trunk. Throughfall amount and rate were lower at the midway point between the trunk and the canopy edge. Throughfall drop size indices (drop size distribution, drop velocity, and unit kinetic energy) varied spatially while did not differ significantly. On the other hand, time-specific throughfall kinetic energy was correlated with the radial distance from the trunk. The dependence the throughfall kinetic energy on the radial distance from the trunk was dominated by the spatial distribution of throughfall amount. The trend in the spatial distribution of throughfall revealed in this study will aid in modelling canopy water processes and in predicting soil erosion on the bare forest floor. The part of this study is published in Nanko et al. (2011, Agric. Forest. Meteorol. 151, 1173-1182).

  11. Do neighbours influence value-added-tax introduction? A spatial duration analysis

    NARCIS (Netherlands)

    Cizek, Pavel; Lei, J.; Ligthart, J.E.

    2017-01-01

    The spatial survival models typically impose frailties, which characterize unobserved heterogeneity, to be spatially correlated. However, the spatial effect may not only exist in the unobserved errors, but it can also be present in the baseline hazards and the dependent variables. A new spatial surv

  12. Spatial variability and response to anthropogenic pressures of assemblages dominated by a habitat forming seaweed sensitive to pollution (northern coast of Alboran Sea).

    Science.gov (United States)

    Bermejo, Ricardo; de la Fuente, Gina; Ramírez-Romero, Eduardo; Vergara, Juan J; Hernández, Ignacio

    2016-04-15

    The Cystoseira ericaefolia group is conformed by three species: C. tamariscifolia, C. mediterranea and C. amentacea. These species are among the most important habitat forming species of the upper sublittoral rocky shores of the Mediterranean Sea and adjacent Atlantic coast. This species group is sensitive to human pressures and therefore is currently suffering important losses. This study aimed to assess the influence of anthropogenic pressures, oceanographic conditions and local spatial variability in assemblages dominated by C. ericaefolia in the Alboran Sea. The results showed the absence of significant effects of anthropogenic pressures or its interactions with environmental conditions in the Cystoseira assemblages. This fact was attributed to the high spatial variability, which is most probably masking the impact of anthropogenic pressures. The results also showed that most of the variability occurred on at local levels. A relevant spatial variability was observed at regional level, suggesting a key role of oceanographic features in these assemblages.

  13. Spatial variability and landscape controls of near-surface permafrost within the Alaskan Yukon River Basin

    Science.gov (United States)

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Rose, Joshua R.; Rigge, Matthew; Walvoord, Michelle A.

    2014-01-01

    The distribution of permafrost is important to understand because of permafrost's influence on high-latitude ecosystem structure and functions. Moreover, near-surface (defined here as within 1 m of the Earth's surface) permafrost is particularly susceptible to a warming climate and is generally poorly mapped at regional scales. Subsequently, our objectives were to (1) develop the first-known binary and probabilistic maps of near-surface permafrost distributions at a 30 m resolution in the Alaskan Yukon River Basin by employing decision tree models, field measurements, and remotely sensed and mapped biophysical data; (2) evaluate the relative contribution of 39 biophysical variables used in the models; and (3) assess the landscape-scale factors controlling spatial variations in permafrost extent. Areas estimated to be present and absent of near-surface permafrost occupy approximately 46% and 45% of the Alaskan Yukon River Basin, respectively; masked areas (e.g., water and developed) account for the remaining 9% of the landscape. Strong predictors of near-surface permafrost include climatic indices, land cover, topography, and Landsat 7 Enhanced Thematic Mapper Plus spectral information. Our quantitative modeling approach enabled us to generate regional near-surface permafrost maps and provide essential information for resource managers and modelers to better understand near-surface permafrost distribution and how it relates to environmental factors and conditions.

  14. Basal respiration - a proxy to understand spatial variability of soil CO2 emissions in urban regions

    Science.gov (United States)

    Vasenev, Viacheslav; Stoorvogel, Jetse; Ananyeva, Nadezhda; Ivashchenko, Kristina; Vizirskaya, Marya; Valentini, Riccardo

    2015-04-01

    Soil respiration (Rs) is an important terrestrial CO2 efflux and received significant attention at different scale levels. However, the sampling density is limited and global Rs databases are biased towards natural ecosystems and towards north America and Europe. This limits our understanding of the spatial variability of Rs. The methodological constraints of direct Rs measurements in the field limit the number of observations. As an alternative approach to approximate the spatial variability of Rs, we used basal respiration (BR) as an indirect measurement. First, the direct Rs and indirect BR measurements were compared at a 10 km2 test area in Moscow city, which included adjacent forests, croplands and urban lawn plots. Rs was monitored by in situ chamber approach with an IR Li-820 gas analyzer at 50 points during the growing season (June-October 2013, 9 time repetitions per point). In the same area, 32 locations were sampled and BR was measured under controlled conditions. Rs was affected by anthropogenic disturbance with the highest values in urban lawns. BR was mainly controlled by soil organic carbon (SOC) with maximum rates in the forested area. Total variability reported by direct observations was 10% higher, than one for BR, although the spatial variability captured by both approaches was similar confirmed by significant correlation between variance coefficients (CV) of the values. This shows that BR is a relevant proxy to analyze the spatial variability of Rs. Subsequently, the sampling area was expanded to the Moscow region for which respiration was mapped using digital soil mapping techniques and BR as a proxy for Rs. Although the absolute levels of respiration remained uncertain, the spatial patterns of BR are likely to correspond well with Rs patterns. Land use largely determined the spatial heterogeneity of soil respiration. Most variation occurred in the urban areas. BR is a relevant and straightforward proxy to understand patterns of Rs especially

  15. Spatial Variability and Uncertainty of Water Use Impacts from U.S. Feed and Milk Production.

    Science.gov (United States)

    Henderson, Andrew D; Asselin-Balençon, Anne C; Heller, Martin; Lessard, Lindsay; Vionnet, Samuel; Jolliet, Olivier

    2017-02-21

    This paper addresses water use impacts of agriculture, developing a spatially explicit approach tracing the location of water use and water scarcity related to feed production, transport, and livestock, tracking uncertainties and illustrating the approach with a case study on dairy production in the United States. This approach was developed as a step to bring spatially variable production and impacts into a process-based life cycle assessment (LCA) context. As water resources and demands are spatially variable, it is critical to take into account the location of activities to properly understand the impacts of water use, accounting for each of the main feeds for milk production. At the crop production level, the example of corn grain shows that 59% of water stress associated with corn grain production in the United States is located in Nebraska, a state with moderate water stress and moderate corn production (11%). At the level of milk production, four watersheds account for 78% of the national water stress impact, as these areas have high milk production and relatively high water stress; it is the production of local silage and hay crops that drives water consumption in these areas. By considering uncertainty in both inventory data and impact characterization factors, we demonstrate that spatial variability may be larger than uncertainty, and that not systematically accounting for the two can lead to artificially high uncertainty. Using a nonspatial approach in a spatially variable setting can result in a significant underestimation or overestimation of water impacts. The approach demonstrated here could be applied to other spatially variable processes.

  16. Groundwater Variability Across Temporal and Spatial Scales in the Central and Northeastern U.S.

    Science.gov (United States)

    Li, Bailing; Rodell, Matthew; Famiglietti, James S.

    2015-01-01

    Depth-to-water measurements from 181 monitoring wells in unconfined or semi-confined aquifers in nine regions of the central and northeastern U.S. were analyzed. Groundwater storage exhibited strong seasonal variations in all regions, with peaks in spring and lows in autumn, and its interannual variability was nearly unbounded, such that the impacts of droughts, floods, and excessive pumping could persist for many years. We found that the spatial variability of groundwater storage anomalies (deviations from the long term mean) increases as a power function of extent scale (square root of area). That relationship, which is linear on a log-log graph, is common to other hydrological variables but had never before been shown with groundwater data. We describe how the derived power function can be used to determine the number of wells needed to estimate regional mean groundwater storage anomalies with a desired level of accuracy, or to assess uncertainty in regional mean estimates from a set number of observations. We found that the spatial variability of groundwater storage anomalies within a region often increases with the absolute value of the regional mean anomaly, the opposite of the relationship between soil moisture spatial variability and mean. Recharge (drainage from the lowest model soil layer) simulated by the Variable Infiltration Capacity (VIC) model was compatible with observed monthly groundwater storage anomalies and month-to-month changes in groundwater storage.

  17. Climatic trends in hail precipitation in France: spatial, altitudinal, and temporal variability.

    Science.gov (United States)

    Hermida, Lucía; Sánchez, José Luis; López, Laura; Berthet, Claude; Dessens, Jean; García-Ortega, Eduardo; Merino, Andrés

    2013-01-01

    Hail precipitation is characterized by enhanced spatial and temporal variability. Association Nationale d'Etude et de Lutte contre les Fléaux Atmosphériques (ANELFA) installed hailpad networks in the Atlantic and Midi-Pyrénées regions of France. Historical data of hail variables from 1990 to 2010 were used to characterize variability. A total of 443 stations with continuous records were chosen to obtain a first approximation of areas most affected by hail. The Cressman method was selected for this purpose. It was possible to find relationships between spatial distributions of the variables, which are supported by obtained Pearson correlations. Monthly and annual trends were examined using the Mann-Kendall test for each of the total affected hailpads. There were 154 pads with a positive trend; most were located between Tarbes and Saint-Gaudens. We found 177 pads with a negative trend, which were largely south of a pine forest in Landes. The remainder of the study area showed an elevated spatial variability with no pattern, even between relatively close hailpads. A similar pattern was found in Lérida (Spain) and Southeast France. In the entire area, monthly trends were predominantly negative in June, July, and August, whereas May had a positive trend; again, however, there was no spatial pattern. There was a high concentration of hailpads with positive trend near the Pyrenees, probably owing to orographic effects, and if we apply cluster analysis with the Mann-Kendall values, the spatial variability is accentuated for stations at higher altitude.

  18. Spatial-temporal variability of the microbial respiration at the regional scale: comparison of field and laboratory approaches

    Science.gov (United States)

    Vasenev, Viacheslav; Stoorvogel, Jetse; Ananyeva, Nadezhda D.; Valentini, Riccardo

    2013-04-01

    the region. The chamber approach focuses on temporal dynamics whilst description of the spatial variability is limited to a confined local site. The BR approach provides a dataset suitable for a regional spatial analysis although temporal dynamics is not included. Surprisingly, similar variability was shown for both approaches. Coefficients of variance (CV) obtained were 63% for the chambers and 61% for the topsoil (67% for the subsoil) based on the BR. The CV obtained by chambers includes both temporal and spatial components (although for a confined area), whereas the one derived from BR referred only to the spatial variation. In order to split these components CV was estimated on the bases of average values per location and per week separately. The spatial CV (45%) was considerably higher than the temporal CV (17%). An ANOVA also demonstrated that "location" factor had significant influence on MR variance (36%, p<0.01), whilst "week" factor was not significant (6%, p= 0.37). The BR database provided higher spatial variability results than chamber approach, whereas the covered by the chambers was considerably smaller than one BR approach enables to analyze. It may be concluded that chamber approach is more convenient when high temporal variability is expected, although standardized BR technique provides more explicit results when spatial variability dominates.

  19. Characterizing spatial variability of air pollution from vehicle traffic around the Houston Ship Channel area

    Science.gov (United States)

    Zhang, Xueying; Craft, Elena; Zhang, Kai

    2017-07-01

    Mobile emissions are a major source of urban air pollution and have been associated with a variety of adverse health outcomes. The Houston Ship Channel area is the home of a large number of diesel-powered vehicles emitting fine particulate matter (PM2.5; ≤2.5 μm in aerodynamic diameter) and nitrogen oxides (NOx). However, the spatial variability of traffic-related air pollutants in the Houston Ship Channel area has rarely been investigated. The objective of this study is to characterize spatial variability of PM2.5 and NOx concentrations attributable to on-road traffic in the Houston Ship Channel area in the year of 2011. We extracted the road network from the Texas Department of Transportation Road Inventory, and calculated emission rates using the Motor Vehicle Emission Simulator version 2014a (MOVES2014a). These parameters and preprocessed meteorological parameters were entered into a Research LINE-source Dispersion Model (RLINE) to conduct a simulation. Receptors were placed at 50 m resolution within 300 m to major roads and at 150 m resolution in the rest of the area. Our findings include that traffic-related PM2.5 were mainly emitted from trucks, while traffic-related NOx were emitted from both trucks and cars. The traffic contributed 0.90 μg/m3 PM2.5 and 29.23 μg/m3 NOx to the annual average mass concentrations of on-road air pollution, and the concentrations of the two pollutants decreased by nearly 40% within 500 m distance to major roads. The pollution level of traffic-related PM2.5 and NOx was higher in winter than those in the other three seasons. The Houston Ship Channel has earlier morning peak hours and relative late afternoon hours, which indicates the influence of goods movement from port activity. The varied near-road gradients illustrate that proximities to major roads are not an accurate surrogate of traffic-related air pollution.

  20. Addressing Spatial Variability of Surface-Layer Wind with Long-Range WindScanners

    DEFF Research Database (Denmark)

    Berg, Jacob; Vasiljevic, Nikola; Kelly, Mark C.;

    2015-01-01

    This paper presents an analysis of mean wind measurements from a coordinated system of long-range WindScanners. From individual scan patterns the mean wind field was reconstructed over a large area, and hence it highlights the spatial variability. From comparison with sonic anemometers, the quality...

  1. The Weakest Link: Spatial Variability in the Piping Failure Mechanism of Dikes

    NARCIS (Netherlands)

    Kanning, W.

    2012-01-01

    Piping is an important failure mechanism of flood defense structures. A dike fails due to piping when a head difference causes first the uplift of an inland blanket layer, and subsequently soil erosion due to a ground water flow. Spatial variability of subsoil parameters causes the probability of pi

  2. Effects of various representations of temporally and spatially variable agricultural processes in air quality dispersion modeling

    Science.gov (United States)

    Agricultural activities that are both temporally and spatially variable, such as tillage and harvesting, can be challenging to represent as sources in air quality dispersion modeling. Existing models were mainly developed to predict concentrations resulting from a stationary and continuous source wi...

  3. Effect of Spatial Variability on Maintenance and Repair Decisions for Concrete Structures

    NARCIS (Netherlands)

    Li, Y.

    2004-01-01

    Due to the increasingly number of elder and deteriorating structures, maintenance is becoming a serious and more complex problem in most of the countries. A lot of studies have been carried out in this area for years. However, the fact that a lot of parameters show spatial random variability, which

  4. Soil salinity and acidity: Spatial variability and effects on rice production in West Africa's mangrove zone.

    NARCIS (Netherlands)

    Sylla, M.

    1994-01-01

    In the mangrove environment of West Africa, high spatial and temporal variability of soil constraints (salinity and acidity) to rice production is a problem for the transfer and adoption of new agronomic techniques, for land use planning, and for soil and water management. Recently, several National

  5. A preliminary characterization of the spatial variability of precipitation at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Hevesi, J.A.; Flint, A.L. [Geological Survey, Mercury, NV (United States); Ambos, D.S. [Foothill Engineering Consultants, Mercury, NV (United States)

    1994-12-31

    Isohyetal maps of precipitation and numerical models for simulating precipitation are needed to characterize natural infiltration at Yucca Mountain, Nevada. The objective of this study was to characterize the spatial variability of precipitation within the domain of the natural catchments overlying the potential repository, and to define preliminary geostatistical models based on differences in storm type for the numerical simulation of precipitation.

  6. The Economics of Storage, Transmission and Drought: Integrating Variable Wind Power into Spatially Separated Electricity Grids

    NARCIS (Netherlands)

    Scora, H.; Sopinka, A.; Kooten, van G.C.

    2012-01-01

    To mitigate the high variability of wind and make it a more viable renewable energy source, observers recommend greater integration of spatially-separated electrical grids, with high transmission lines linking load centers, scattered wind farms and hydro storage sites. In this study, we examine the

  7. Prediction of spatially variable unsaturated hydraulic conductivity using scaled particle-size distribution functions

    NARCIS (Netherlands)

    Nasta, P.; Romano, N.; Assouline, S; Vrugt, J.A.; Hopmans, J.W.

    2013-01-01

    Simultaneous scaling of soil water retention and hydraulic conductivity functions provides an effective means to characterize the heterogeneity and spatial variability of soil hydraulic properties in a given study area. The statistical significance of this approach largely depends on the number of s

  8. Spatial and temporal variability of spring ecosystems in Cuatro Ciénegas, MX

    Science.gov (United States)

    Corman, J. R.; Ramos, J.; Childers, D. L.; Elser, J. J.

    2013-12-01

    Springs in desert ecosystems provide vital water resources and are often hotspots of biodiversity. Indeed, the Cuatro Ciénegas (CC) Valley, México, which hosts >300 springs, lakes, streams, and ponds, has the highest rate of endemism in North America. This region of the Chihuahuan Desert and its aquatic ecosystems are thought to be supported by both precipitation events and local and regional aquifers, however, the hydrologic influence and connectivity of the springs are not well understood. We have been monitoring the physicochemical characteristics of this system since 1998 and yearly since 2011. Our basin-wide study of 15 different aquatic features provides an opportunity to (1) characterize the physicochemical and nutrient landscape of the aquatic ecosystems and (2) test the assumptions of hypothesized hydrologic dynamics. The aquatic ecosystems of CC have an impressive spatial diversity in their physicochemical properties and support a locally-connected hydrologic model of the valley. Aqueous specific conductivity spanned 1.1 - 9.6 mS/cm2, with the highest values found in the eastern lobe and lowest values in the southeastern and northern regions. Dissolved organic carbon concentrations ranged over two orders of magnitude (max: 5.3 mM), with a similar spatial variability as specific conductivity. Nutrient data also showed geographic trends, however patterns differed for nitrogen (N) and phosphorus (P). While total dissolved N and P were highest in the eastern lobe, the highest values of each were not found at the same sites. Rancho las Pozas had the highest N (>500 uM N), while Los Hundidos had the highest P concentrations (as high as 10.8 uM P). Atomic N:P ratios ranged from 7 - 997 across CC, with a mean of 139. Both the highest (>500) and lowest (27 cm of rain in some regions. A comparison of our longest record from Río Mesquites, a spring-fed stream, and Los Hundidos, a collection of spring-fed and evaporitic ponds, shows the spatial dissimilarity of CC

  9. On the Spatial Variability of Arsenic Contamination in the Groundwater of Bangladesh

    Science.gov (United States)

    Karthik, B.; Islam, S.; Harvey, C. F.

    2001-05-01

    The widespread arsenic contamination of groundwater in Bangladesh has been recognized as posing a serious health problem to millions of people in the region. We have performed a detailed spatial analysis of arsenic data from groundwater in an attempt to identify dominant controls on the spatial distribution of arsenic. The variogram analysis suggests that large-scale geological and physical features control a significant fraction of the spatial variability in shallow wells (55 %) as well as in the deeper wells (88 %). We propose that the prevalence of higher arsenic concentrations of arsenic in shallow wells is because of the `small-scale' processes (less than 6 km. approx.) exerting a greater degree of control at shallower depths in the sediments. A comparison of the correlated spatial variability for high and low arsenic concentrations indicates that the `large scale' processes also control the distribution of higher arsenic concentrations to a significant extent. Through an indicator variogram analysis we demonstrate that the correlation structure of the arsenic magnitudes is primarily due to the spatial distribution of their locations, around an approximate concentration cut-off limit of 0.07 mg/L. Our results suggest that the complex spatial distribution of high-level arsenic concentrations is a consequence of interactions among multiscale geologic and geochemical processes.

  10. Spatial variability of soil fertility and its relation with cocoa yield

    Directory of Open Access Journals (Sweden)

    Railton O. dos Santos

    Full Text Available ABSTRACT The knowledge on the spatial variability of soil properties and crops is important for decision-making on agricultural management. The objective of this study was to evaluate the spatial variability of soil fertility and its relation with cocoa yield. The study was conducted over 14 months in an area cultivated with cocoa. A sampling grid was created to study soil chemical properties and cocoa yield (stratified in season, off-season and annual. The data were analyzed using descriptive and exploratory statistics, and geostatistics. The chemical attributes were classified using fuzzy logic to generate a soil fertility map, which was correlated with maps of crop yield. The soil of the area, except for the western region, showed possibilities ranging from medium to high for cocoa cultivation. Soil fertility showed positive spatial correlation with cocoa yield, and its effect was predominant only for the off-season and annual cocoa.

  11. A mobile system for quantifying the spatial variability of the surface energy balance: design and application

    Science.gov (United States)

    Wohlfahrt, Georg; Tasser, Erich

    2015-05-01

    We present a mobile device for the quantification of the small-scale (a few square meters) spatial variability in the surface energy balance components and several auxiliary variables of short-statured (ecological research questions. The potential of the new device is demonstrated through four selected case studies, which cover the issues of net radiation heterogeneity within the footprint of eddy covariance flux measurements due to (1) land use and (2) slope and aspect of the underlying surface, (3) controls on landscape-scale variability in soil temperature and albedo and (4) the estimation of evapotranspiration based exclusively on measurements with the mobile device.

  12. Spatial Variability of Nutrient Properties in Black Soil of Northeast China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xing-Yi; SUI Yue-Yu; ZHANG Xu-Dong; MENG Kai; S.J.HERBERT

    2007-01-01

    A total of 1400 soil samples from the plow layer (0-20 cm) at an approximate interval of 5 km were collected in the autumn of 2002 over the entire black soil arable crops region to determine the spatial variability of seven variables, such as total organic matter content (OMC), total N, total P, total K, alkali-dissolvable N (AN), available P (AP) and available K (AK), with classical statistics and geostatistical analysis across the entire black soil area in Northeast China. In nonsampled areas ordinary kriging was utilized for interpolation of estimated nutrient determinations. Classical statistics revealed highly significant (P ≤ 0.01) correlations with all seven of the soil properties, except for OMC with AP and total K with AK. In addition, using coefficients of variation, all soil properties, except for total K, were moderately variable. A geostatistical analysis indicated that structural factors, such as parent material, terrain, and water table, were the main causes of the spatial correlations. Strong spatial correlations were noted with OMC, total N, total P, AN, and AP, while they were moderate for total K and AK. The effective spatial autocorrelation of OMC, total N, total P, and AN ranged from 1 037 to 1 353 km, whereas the ranges of total K, AP, and AK were only from 6 to 138 km. The fit of the experimental semi-variograms to the theoretical models indicated that except for AN, kriging could successfully interpolate other six variables. Thus, the geostatistical method used on a large scale could accurately evaluate the spatial variability of most black soil nutrient properties in Northeast China.

  13. Spatial variability overwhelms seasonal patterns in bacterioplankton communities across a river to ocean gradient

    Science.gov (United States)

    Fortunato, Caroline S; Herfort, Lydie; Zuber, Peter; Baptista, Antonio M; Crump, Byron C

    2012-01-01

    Few studies of microbial biogeography address variability across both multiple habitats and multiple seasons. Here we examine the spatial and temporal variability of bacterioplankton community composition of the Columbia River coastal margin using 16S amplicon pyrosequencing of 300 water samples collected in 2007 and 2008. Communities separated into seven groups (ANOSIM, P850 m). The ordination of these samples was correlated with salinity (ρ=−0.83) and depth (ρ=−0.62). Temporal patterns were obscured by spatial variability among the coastal environments, and could only be detected within individual groups. Thus, structuring environmental factors (for example, salinity, depth) dominate over seasonal changes in determining community composition. Seasonal variability was detected across an annual cycle in the river, estuary and plume where communities separated into two groups, early year (April–July) and late year (August–Nov), demonstrating annual reassembly of communities over time. Determining both the spatial and temporal variability of bacterioplankton communities provides a framework for modeling these communities across environmental gradients from river to deep ocean. PMID:22011718

  14. Determining the spatial variability of crop yields of two different climatic regions in Southwest Germany

    Science.gov (United States)

    Eshonkulov, Ravshan; Poyda, Arne; Ingwersen, Joachim; Streck, Thilo

    2017-04-01

    Assessing the spatial variability of soil physical properties is crucial for agricultural land management. We determined the spatial variability within two agricultural fields in the regions of Kraichgau and Swabian Jura in Southwest Germany. We determined soil physical properties and recorded the temporal development of soil mineral nitrogen (N) and water content as well as that of plant variables (phenology, biomass, leaf area index (LAI), N content, green vegetation fraction (GVF). The work was conducted during the vegetation periods of 2015 and 2016 in winter wheat, and winter rapeseed in Kraichgau and winter barley and silage maize on Swabian Jura. Measurements were taken in three-weekly intervals. On each field, we identified three plots with reduced plant development using high-resolution (RapidEye) satellite images ("cold spots"). Measurements taken on these cold spots were compared to those from five established (long-term) reference plots representing the average field variability. The software EXPERT-N was used to simulate the soil crop system at both cold spots and reference plots. Sensitivity analyses were conducted to identify the most important parameters for the determination of spatial variability in crop growth dynamics.

  15. Patterns of variability in early-life traits of fishes depend on spatial scale of analysis.

    Science.gov (United States)

    Di Franco, Antonio; Guidetti, Paolo

    2011-06-23

    Estimates of early-life traits of fishes (e.g. pelagic larval duration (PLD) and spawning date) are essential for investigating and assessing patterns of population connectivity. Such estimates are available for a large number of both tropical and temperate fish species, but few studies have assessed their variability in space, especially across multiple scales. The present study, where a Mediterranean fish (i.e. the white seabream Diplodus sargus sargus) was used as a model, shows that spawning date and PLD are spatially more variable at a scale of kilometres than at a scale of tens to hundreds of kilometres. This study indicates the importance of considering spatial variability of early-life traits of fishes in order to properly delineate connectivity patterns at larval stages (e.g. by means of Lagrangian simulations), thus providing strategically useful information on connectivity and relevant management goals (e.g. the creation of networks of marine reserves).

  16. Influence of spatial temperature distribution on high accuracy interferometric metrology

    Science.gov (United States)

    Gu, Yongqiang; Miao, Erlong; Yan, Feng; Zhang, Jian; Yang, Huaijiang

    2010-10-01

    We calculate the influence of temperature change on the refractive index of air, establish a model of air temperature distribution and analyze the effect of different temperature distribution on the high accuracy interferometric metrology. First, a revised Edlen formula is employed to acquire the relation between temperature and refractive index of air, followed by introducing the fixed temperature gradient distribution among the spatial grid within the optical cavity between the reference flat and the test flat of the Fizeau interferometer, accompanied by a temperature change random function within each grid. Finally, all the rays through the air layer with different incident angles are traced by Matlab program in order to obtain the final output position, angle and OPD for each ray. The influence of different temperature distribution and the length of the optical cavity in on the testing accuracy can be analyzed through the RMS value that results from repeatable rays tracing. As a result, the horizontal distribution (vertical to optical axis) has a large effect on the testing accuracy. Thus, to realize the high accuracy figure metrology, the horizontal distribution of temperature must be rigorously controlled as well as to shorten the length of the optical cavity to a large extent. The results from our simulation are of great significant for the accuracy analysis of interferometric testing and the research of manufacturing a interferometer.

  17. Estimating Spatially Variable Parameters of the Epidemic Type Aftershock Sequence (ETAS) in California

    Science.gov (United States)

    Nandan, Shyam; Ouillon, Guy; Sornette, Didier; Wiemer, Stefan

    2016-04-01

    The ETAS model is widely employed to model the spatio-temporal distribution of earthquakes, generally using spatially invariant parameters, which is most likely a gross simplification considering the extremely heterogeneous structure of the Earth's crust. We propose an efficient method for the estimation of spatially varying parameters, using an expectation maximization (EM) algorithm and spatial Voronoi tessellations. We assume that each Voronoi cell is characterized by a set of eight constant ETAS parameters. For a given number of randomly distributed cells, Vi=1 to N, we jointly invert the ETAS parameters within each cell using an EM algorithm. This process is progressively repeated several times for a given N (which controls the complexity), which is itself increased incrementally. We use the Bayesian Information Criterion (BIC) to rank all the inverted models given their likelihood and complexity and select the top 1% models to compute the average model at any location. Using a synthetic catalog, we also check that the proposed method correctly inverts the known parameters. We apply the proposed method to earthquakes (M>=3) included in the ANSS catalog that occurred within the time period 1981-2016 in the spatial polygon defined by RELM/CSEP around California. The results indicate significant spatial variation of the ETAS parameters. Using these spatially variable estimates of ETAS parameters, we are better equipped to answer some important questions: (1) What is the seismic hazard (both long- and short-term) in a given region? (2) What kind of earthquakes dominate triggering? (3) are there regions where earthquakes are most likely preceded by foreshocks? Last but not the least, a possible correlation of the spatially varying ETAS parameters with spatially variable geophysical properties can lead to an improved understanding of the physics of earthquake triggering beside providing physical meaning to the parameters of the purely statistical ETAS model.

  18. Spatial and Temporal Variability of Remotely Sensed Ocean Color Parameters in Coral Reef Regions

    Science.gov (United States)

    Otis, Daniel Brooks

    The variability of water-column absorption due to colored dissolved organic matter (CDOM) and phytoplankton in coral reef regions is the focus of this study. Hydrographic and CDOM absorption measurements made on the Bahamas Banks and in Exuma Sound during the spring of 1999 and 2000 showed that values of salinity and CDOM absorption at 440nm were higher on the banks (37.18 psu, 0.06 m. -1), compared to Exuma Sound (37.04 psu, 0.03 m. -1). Spatial patternsof CDOM absorption in Exuma Sound revealed that plumes of CDOM-rich water flow into Exuma Sound from the surrounding banks. To examine absorption variability in reef regions throughout the world, a thirteen-year time series of satellite-derived estimates of water-column absorption due to CDOM and phytoplankton were created from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS) data. Time series data extracted adjacent to coral reef regions showed that variability in absorption depends on oceanographic conditions such as circulation patterns and winds as well as proximity to sources of light-absorbing materials that enter the water column, such as from terrestrial runoff. Waters near reef regions are generally clear, exhibiting a lower "baseline" level of CDOM absorption of approximately 0.01 m. -1 at 443nm. The main differences between regions lie in the periodsduring the year when increased levels of absorption are observed, which can be triggered by inputs of terrestrially-derived material, as in the Great Barrier Reef lagoon, or wind-driven upwelling as in the Andaman Sea and eastern Pacific Ocean near Panama. The lowest CDOM absorption levels found were approximately 0.003 m. -1 at 443nm near the islands of Palau and Yap, which are removed fromsources of colored materials. The highest absorption levels near reefs were associated with wind-driven upwelling during the northeast monsoon on the Andaman coast of Thailand where values of CDOM absorption at 443nm

  19. Cytogenetic variability in pinus sylvestris L. populations experiencing anthropogenic influence

    Energy Technology Data Exchange (ETDEWEB)

    Oudalova, A.; Geras' kin, S.; Vasiliev, D.; Dikarev, V. [Russian Institute of Agricultural Radiology and Agroecology, Obninsk (Russian Federation)

    2004-07-01

    Techno-genic pollution has become one of the most significant ecological factors determining biosphere existence and development. An analysis of genetic consequences of the radiation accidents in the South Urals and Chernobyl has shown that mutation and recombination processes are considerably accelerated in plant and animal's populations experiencing techno-genic influence. This implies that there are complicated adaptation processes leading to changes in genetic structure of populations and increasing genetic load. Pinus sylvestris L. populations growing at the territory of the 'radon' Leningrad regional radioactive waste reprocessing enterprise and Sosnovy Bor town were monitored 6 years (1997-2002) by a set of cyto-genetical and morphological tests. Cytogenetic damage levels within intercalary meristem of needle as well as in root meristem of seedlings were found to significantly exceed corresponding controls. A higher radioresistance of the Scots pine seeds analyzed was demonstrated with an acute {gamma}-radiation that also revealed a selection process directed at an enhancement of repair efficiency and resulting in a shift of mean values of radioresistance in populations towards higher values. An enlargement of variance of studied cytogenetic parameters was found in the populations experiencing techno-genic influence. This indicates, with an account of phenomenon of the enhanced radioresistance, that there are processes of cyto-genetical adaptation in the investigated regions. An analysis of the structure of ecological-genetical variability was carried out with the purpose of separating two components in the inter-population variability - the first is engaged to the genetically determined variability of biological characteristics intrinsic for this species, and the second is responsible for the variability originating from anthropogenic contamination of the natural habitat. Changes of these two types of variability were studied in dependence on

  20. Spatial variability of the Black Sea surface temperature from high resolution modeling and satellite measurements

    Science.gov (United States)

    Mizyuk, Artem; Senderov, Maxim; Korotaev, Gennady

    2016-04-01

    Large number of numerical ocean models were implemented for the Black Sea basin during last two decades. They reproduce rather similar structure of synoptical variability of the circulation. Since 00-s numerical studies of the mesoscale structure are carried out using high performance computing (HPC). With the growing capacity of computing resources it is now possible to reconstruct the Black Sea currents with spatial resolution of several hundreds meters. However, how realistic these results can be? In the proposed study an attempt is made to understand which spatial scales are reproduced by ocean model in the Black Sea. Simulations are made using parallel version of NEMO (Nucleus for European Modelling of the Ocean). A two regional configurations with spatial resolutions 5 km and 2.5 km are described. Comparison of the SST from simulations with two spatial resolutions shows rather qualitative difference of the spatial structures. Results of high resolution simulation are compared also with satellite observations and observation-based products from Copernicus using spatial correlation and spectral analysis. Spatial scales of correlations functions for simulated and observed SST are rather close and differs much from satellite SST reanalysis. Evolution of spectral density for modelled SST and reanalysis showed agreed time periods of small scales intensification. Using of the spectral analysis for satellite measurements is complicated due to gaps. The research leading to this results has received funding from Russian Science Foundation (project № 15-17-20020)

  1. Factors influencing the spatial extent of mobile source air pollution impacts: a meta-analysis

    Directory of Open Access Journals (Sweden)

    Levy Jonathan I

    2007-05-01

    Full Text Available Abstract Background There has been growing interest among exposure assessors, epidemiologists, and policymakers in the concept of "hot spots", or more broadly, the "spatial extent" of impacts from traffic-related air pollutants. This review attempts to quantitatively synthesize findings about the spatial extent under various circumstances. Methods We include both the peer-reviewed literature and government reports, and focus on four significant air pollutants: carbon monoxide, benzene, nitrogen oxides, and particulate matter (including both ultrafine particle counts and fine particle mass. From the identified studies, we extracted information about significant factors that would be hypothesized to influence the spatial extent within the study, such as the study type (e.g., monitoring, air dispersion modeling, GIS-based epidemiological studies, focus on concentrations or health risks, pollutant under study, background concentration, emission rate, and meteorological factors, as well as the study's implicit or explicit definition of spatial extent. We supplement this meta-analysis with results from some illustrative atmospheric dispersion modeling. Results We found that pollutant characteristics and background concentrations best explained variability in previously published spatial extent estimates, with a modifying influence of local meteorology, once some extreme values based on health risk estimates were removed from the analysis. As hypothesized, inert pollutants with high background concentrations had the largest spatial extent (often demonstrating no significant gradient, and pollutants formed in near-source chemical reactions (e.g., nitrogen dioxide had a larger spatial extent than pollutants depleted in near-source chemical reactions or removed through coagulation processes (e.g., nitrogen oxide and ultrafine particles. Our illustrative dispersion model illustrated the complex interplay of spatial extent definitions, emission rates

  2. Observed small spatial scale and seasonal variability of the CO2-system in the Southern Ocean

    Directory of Open Access Journals (Sweden)

    L. Resplandy

    2013-08-01

    Full Text Available The considerable uncertainties in the carbon budget of the Southern Ocean are largely attributed to unresolved variability, in particular at seasonal time scale and small spatial scale (~ 100 km. In this study, the variability of surface pCO2 and DIC at seasonal and small-spatial scales is examined using a dataset of surface drifters including ~ 80 000 measurements at high spatio-temporal resolution. On spatial scales of 100 km, we find gradients ranging from 5 to 50 μ atm for pCO2 and 2 to 30 μ mol kg−1 for DIC, with highest values in energetic and frontal regions. This result is supported by a second estimate obtained with SST satellite images and local DIC/SST relationships derived from drifters observations. We find that dynamical processes drives the variability of DIC at small spatial scale in most regions of the Southern Ocean, the cascade of large-scale gradients down to small spatial scales leading to gradients up to 15 μ mol kg−1 over 100 km. Although the role of biological activity is more localized, it enhances the variability up to 30 μ mol kg−1 over 100 km. The seasonal cycle of surface DIC is reconstructed following Mahadevan et al. (2011, using an annual climatology of DIC and a monthly climatology of mixed layer depth. This method is evaluated using drifters observations and proves to be a reasonable first-order estimate of the seasonality in the Southern Ocean, which could be used to validate models simulations. We find that small spatial scales structures are a non negligible source of variability for DIC, with amplitudes of about a third of the variations associated with the seasonality and up to 10 times the magnitude of large-scale gradients. The amplitude of small-scale variability reported here should be kept in mind when inferring temporal changes (seasonality, inter-annual variability, decadal trends of the carbon budget from low resolution observations and models.

  3. May We Identify The Spatial Variability of Soil Hydraulic Properties Based On Measurements With "spatial Tdr"? A) Model Study

    Science.gov (United States)

    Zehe, E.; Becker, R.; Schädel, W.

    A dynamic system left without external disturbances, will always tend to a stable equilibrium state that is consistent with the internal physics. For natural soils such an equilibrium state is reached when the gradients of the total hydraulic potential tend to zero. This statement is still valid for heterogeneous soils, because the hydraulic po- tential is an intensive state variable and therefore continuous at discontinuities of the pore space. In contrary the soil water content is as an extensive property discontinu- ous at discontinuities of the pore space. Hence, a small scale soil moisture pattern that persists if the soil state tends to hydraulic equilibrium, reflects the lateral small scale variability of the pore space. The objectives of our study are to show a) whether and how we could use TDR observations to identify the small scale variability of the pore space. For that purpose we analyse artificial TDR measurements, taken from physi- cally based simulations of soil water dynamics in heterogeneous media. b) We want to introduce a new TDR technology which we call "Spatial TDR", that is suitable for that purposes. To produce the artificial TDR-datasets we generate random fields of soil porosity and saturated hydraulic conductivity with different statistical properties based on field data in a Luvisol and simulate artificial water dynamics in this model soil based on Richards-equation. Within this model soil we define several hypothetical "Spatial TDR" clusters, that differ in the lateral spacing and the number of the probes, in the temporal resolution of the hypothetical measurements and in the assumed mea- surement accuracy. If the model soil approaches hydraulic equilibrium, the remaining soil moisture pattern will be dominated by the statistical properties of the porosity. In contrary the variability of the hydraulic conductivity will dominate the soil moisture patterns during infiltration events. The hypothetical Spatial TDR measurements within the

  4. Instrumented Impact Testing: Influence of Machine Variables and Specimen Position

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E.; McCowan, C. N.; Santoyo, R. A.

    2008-09-15

    An investigation has been conducted on the influence of impact machine variables and specimen positioning on characteristic forces and absorbed energies from instrumented Charpy tests. Brittle and ductile fracture behavior has been investigated by testing NIST reference samples of low, high and super-high energy levels. Test machine variables included tightness of foundation, anvil and striker bolts, and the position of the center of percussion with respect to the center of strike. For specimen positioning, we tested samples which had been moved away or sideways with respect to the anvils. In order to assess the influence of the various factors, we compared mean values in the reference (unaltered) and altered conditions; for machine variables, t-test analyses were also performed in order to evaluate the statistical significance of the observed differences. Our results indicate that the only circumstance which resulted in variations larger than 5 percent for both brittle and ductile specimens is when the sample is not in contact with the anvils. These findings should be taken into account in future revisions of instrumented Charpy test standards.

  5. Variable impact of chronic stress on spatial learning and memory in BXD mice.

    Science.gov (United States)

    Shea, Chloe J A; Carhuatanta, Kimberly A K; Wagner, Jessica; Bechmann, Naomi; Moore, Raquel; Herman, James P; Jankord, Ryan

    2015-10-15

    The effects of chronic stress on learning are highly variable across individuals. This variability stems from gene-environment interactions. However, the mechanisms by which stress affects genetic predictors of learning are unclear. Thus, we aim to determine whether the genetic pathways that predict spatial memory performance are altered by previous exposure to chronic stress. Sixty-two BXD recombinant inbred strains of mice, as well as parent strains C57BL/6J and DBA/2J, were randomly assigned as behavioral control or to a chronic variable stress paradigm and then underwent behavioral testing to assess spatial memory and learning performance using the Morris water maze. Quantitative trait loci (QTL) mapping was completed for average escape latency times for both control and stress animals. Loci on chromosomes 5 and 10 were found in both control and stress environmental populations; eight additional loci were found to be unique to either the control or stress environment. In sum, results indicate that certain genetic loci predict spatial memory performance regardless of prior stress exposure, while exposure to stress also reveals unique genetic predictors of training during the memory task. Thus, we find that genetic predictors contributing to spatial learning and memory are susceptible to the presence of chronic stress.

  6. The Formation of Cataclysmic Variables: The Influence of Nova Eruptions

    Science.gov (United States)

    Nelemans, G.; Siess, L.; Repetto, S.; Toonen, S.; Phinney, E. S.

    2016-01-01

    The theoretical and observed populations of pre-cataclysmic variables are dominated by systems with low-mass white dwarfs (WDs), while the WD masses in cataclysmic variables (CVs) are typically high. In addition, the space density of CVs is found to be significantly lower than in the theoretical models. We investigate the influence of nova outbursts on the formation and initial evolution of CVs. In particular, we calculate the stability of the mass transfer in the case where all of the material accreted on the WD is lost in classical novae and part of the energy to eject the material comes from a common-envelope-like interaction with the companion. In addition, we study the effect of an asymmetry in the mass ejection that may lead to small eccentricities in the orbit. We find that a common-envelope-like ejection significantly decreases the stability of the mass transfer, particularly for low-mass WDs. Similarly, the influence of asymmetric mass loss can be important for short-period systems and even more so for low-mass WDs; however, this influence likely disappears long before the next nova outburst due to orbital circularization. In both cases the mass-transfer rates increase, which may lead to observable (and perhaps already observed) consequences for systems that do survive to become CVs. However, a more detailed investigation of the interaction between nova ejecta and the companion and the evolution of slightly eccentric CVs is needed before definite conclusions can be drawn.

  7. Spatial variability of soil nutrient in paddy plantation: Sites FELCRA Seberang Perak

    Science.gov (United States)

    Kamarudin, H.; Adnan, N. A.; Mispan, M. R.; Athirah. A, A.

    2016-06-01

    The conventional methods currently used for rice cultivation in Malaysia are unable to give maximum yield although the yield production of paddy is increasing. This is due to the conversional method being unable to include soil properties as one of their parameters in agriculture management. Soil properties vary spatially in farm scale due to differences in topography, parent material, vegetation or land management and soil characteristics; also plantation productivity varies significantly over small spatial scales. Knowledge of spatial variability in soil fertility is important for site specific nutrient management. Analysis of spatial variability of soil nutrient of nitrogen (N), phosphorus (P) and potassium (K) were conducted in this study with the aid of GIS (i.e ArcGIS) and statistical softwares. In this study different temporal and depths of soil nutrient were extracted on the field and further analysis of N,P,K content were analysed in the chemical laboratory and using spatially technique in GIS sofware. The result indicated that for the Seberang Perak site of 58 hactares area, N and K are met minimum requirements nutrient content as outlines by the MARDI for paddy cultivation. However, P indicated poor condition in the study area; therefore the soil needs further attention and treatment.

  8. Spatial Variation of Leaf Optical Properties in a Boreal Forest Is Influenced by Species and Light Environment

    Science.gov (United States)

    Atherton, Jon; Olascoaga, Beñat; Alonso, Luis; Porcar-Castell, Albert

    2017-01-01

    Leaf Optical Properties (LOPs) convey information relating to temporally dynamic photosynthetic activity and biochemistry. LOPs are also sensitive to variability in anatomically related traits such as Specific Leaf Area (SLA), via the interplay of intra-leaf light scattering and absorption processes. Therefore, variability in such traits, which may demonstrate little plasticity over time, potentially disrupts remote sensing estimates of photosynthesis or biochemistry across space. To help to disentangle the various factors that contribute to the variability of LOPs, we defined baseline variation as variation in LOPs that occurs across space, but not time. Next we hypothesized that there were two main controls of potentially disruptive baseline spatial variability of photosynthetically-related LOPs at our boreal forest site: light environment and species. We measured photosynthetically-related LOPs in conjunction with morphological, biochemical, and photosynthetic leaf traits during summer and across selected boreal tree species and vertical gradients in light environment. We then conducted a detailed correlation analysis to disentangle the spatial factors that control baseline variability of leaf traits and, resultantly, LOPs. Baseline spatial variability of the Photochemical Reflectance Index (PRI) was strongly influenced by species and to a lesser extent light environment. Baseline variability of spectral fluorescence derived LOPs was less influenced by species; however at longer near-infrared wavelengths, light environment was an important control. In summary, remote sensing of chlorophyll fluorescence has good potential to detect variation in photosynthetic performance across space in boreal forests given reduced sensitivity to species related baseline variability in comparison to the PRI. Our results also imply that spatially coarse remote sensing observations are potentially unrepresentative of the full scope of natural variation that occurs within a boreal

  9. Identifying Spatially Inhomogeneous Relationships Between Drainage Density and Its Controlling Variables

    Science.gov (United States)

    Stepinski, T.; Ranatunga, T.; Jasiewicz, J.

    2011-12-01

    Spatial variation of the value of drainage density (D) is observed on variety of scales. It is attributed to a nonuniform distribution of variables that exert control over D. Comprehensive understanding of the dependence of D on its controlling factors is lacking because of complex, nonlinear character of such dependence. This study presents the use of the regression tree technique to identify different relationships between D and its controlling variables across the conterminous United States. Local drainage density (response variable) is calculated on a 4 km-size regular grid from high resolution stream network data from the National Hydrographic Dataset. Explanatory variables pertaining to geology, soil, terrain, climate, land cover, and vegetation density are also calculated on the same grid. The resulting grids are fed to a GUIDE algorithm to build a regression tree. The algorithm performs "regression by parts" - it hierarchically partitions the dataset so as to increase the accuracy of linear regression in each partition. Each final partition (a terminal node of the tree) contains entries in the dataset (cells in a grid) for which a good-fit linear relation between D and its controlling variables can be established. Ranges of explanatory variables in each node are determined by the path in the tree, and spatial extent (footprint of relationship) of the node is mapped. Collection of all such relations and their footprints provides comprehensive understanding of dependence of D on its controlling factors.

  10. Spatial analysis of factors influencing long-term stress in the grizzly bear (Ursus arctos population of Alberta, Canada.

    Directory of Open Access Journals (Sweden)

    Mathieu L Bourbonnais

    Full Text Available Non-invasive measures for assessing long-term stress in free ranging mammals are an increasingly important approach for understanding physiological responses to landscape conditions. Using a spatially and temporally expansive dataset of hair cortisol concentrations (HCC generated from a threatened grizzly bear (Ursus arctos population in Alberta, Canada, we quantified how variables representing habitat conditions and anthropogenic disturbance impact long-term stress in grizzly bears. We characterized spatial variability in male and female HCC point data using kernel density estimation and quantified variable influence on spatial patterns of male and female HCC stress surfaces using random forests. Separate models were developed for regions inside and outside of parks and protected areas to account for substantial differences in anthropogenic activity and disturbance within the study area. Variance explained in the random forest models ranged from 55.34% to 74.96% for males and 58.15% to 68.46% for females. Predicted HCC levels were higher for females compared to males. Generally, high spatially continuous female HCC levels were associated with parks and protected areas while low-to-moderate levels were associated with increased anthropogenic disturbance. In contrast, male HCC levels were low in parks and protected areas and low-to-moderate in areas with increased anthropogenic disturbance. Spatial variability in gender-specific HCC levels reveal that the type and intensity of external stressors are not uniform across the landscape and that male and female grizzly bears may be exposed to, or perceive, potential stressors differently. We suggest observed spatial patterns of long-term stress may be the result of the availability and distribution of foods related to disturbance features, potential sexual segregation in available habitat selection, and may not be influenced by sources of mortality which represent acute traumas. In this wildlife

  11. Spatial analysis of factors influencing long-term stress in the grizzly bear (Ursus arctos) population of Alberta, Canada.

    Science.gov (United States)

    Bourbonnais, Mathieu L; Nelson, Trisalyn A; Cattet, Marc R L; Darimont, Chris T; Stenhouse, Gordon B

    2013-01-01

    Non-invasive measures for assessing long-term stress in free ranging mammals are an increasingly important approach for understanding physiological responses to landscape conditions. Using a spatially and temporally expansive dataset of hair cortisol concentrations (HCC) generated from a threatened grizzly bear (Ursus arctos) population in Alberta, Canada, we quantified how variables representing habitat conditions and anthropogenic disturbance impact long-term stress in grizzly bears. We characterized spatial variability in male and female HCC point data using kernel density estimation and quantified variable influence on spatial patterns of male and female HCC stress surfaces using random forests. Separate models were developed for regions inside and outside of parks and protected areas to account for substantial differences in anthropogenic activity and disturbance within the study area. Variance explained in the random forest models ranged from 55.34% to 74.96% for males and 58.15% to 68.46% for females. Predicted HCC levels were higher for females compared to males. Generally, high spatially continuous female HCC levels were associated with parks and protected areas while low-to-moderate levels were associated with increased anthropogenic disturbance. In contrast, male HCC levels were low in parks and protected areas and low-to-moderate in areas with increased anthropogenic disturbance. Spatial variability in gender-specific HCC levels reveal that the type and intensity of external stressors are not uniform across the landscape and that male and female grizzly bears may be exposed to, or perceive, potential stressors differently. We suggest observed spatial patterns of long-term stress may be the result of the availability and distribution of foods related to disturbance features, potential sexual segregation in available habitat selection, and may not be influenced by sources of mortality which represent acute traumas. In this wildlife system and others

  12. Spatial and temporal variability of the sea surface temperature in the Ballenas-Salsipuedes Channel (central Gulf of California)

    Science.gov (United States)

    MartíNez-DíAz-De-León, A.; Pacheco-RuíZ, I.; Delgadillo-Hinojosa, F.; Zertuche-GonzáLez, J. A.; Chee-BarragáN, A.; Blanco-Betancourt, R.; GuzmáN-Calderón, J. M.; GáLvez-Telles, A.

    2006-02-01

    The Ballenas-Salsipuedes Channel (BSC) is considered an oceanographic province on its own within the Gulf of California. In this region, tidal mixing is modulated by quarterdiurnal, semidiurnal, diurnal, and fortnightly frequencies, producing a strong outcropping of cold and nutrient-rich waters. In this work we analyze the temporal and spatial variability of sea surface temperature (SST) data recorded simultaneously over a period of 1 year in six bays along the BSC. Minimum mean SST differences ( 2.5°C) were recorded in June. The monthly SST anomaly showed that from late October to late January, the channel behaved as a very well mixed region. In contrast, SST anomalies of up to 2.2°C among bays were observed from May to September, indicating intense heat gain in summer and highlighting spatial heterogeneity in the intensity of vertical mixing. Besides the seasonal temperature cycle, influenced by solar irradiation, four main periods (0.25, 0.5, 1, and 15 days) were identified, corresponding to the main timescales of variability induced by the tides. This work demonstrates that the main source of temporal SST variability in BSC is the tide-induced fortnightly modulation, suggesting the possibility of a pulsation mechanism in the outcropping of nutrient-rich waters reaching the surface layer throughout the channel; this could play a crucial role in explaining the exceptionally high biological production of this region.

  13. DISCOVERY 2010: Spatial and temporal variability in a dynamic polar ecosystem

    Science.gov (United States)

    Tarling, G. A.; Ward, P.; Atkinson, A.; Collins, M. A.; Murphy, E. J.

    2012-01-01

    DIC deficits, the South Georgia bloom was found to contain the strongest seasonal carbon uptake in the ice-free zone of the Southern Ocean. The surveys also encountered low-production, iron-limited regions, a situation more typical of the wider Southern Ocean. The response of primary and secondary consumers to spatial and temporal heterogeneity in production was complex. Many of the life-cycles of small pelagic organisms showed a close coupling to the seasonal cycle of food availability. For instance, Antarctic krill showed a dependence on early, non-ice-associated blooms to facilitate early reproduction. Strategies to buffer against environmental variability were also examined, such as the prevalence of multiyear life-cycles and variability in energy storage levels. Such traits were seen to influence the way in which Scotia Sea communities were structured, with biomass levels in the larger size classes being higher than in other ocean regions. Seasonal development also altered trophic function, with the trophic level of higher predators increasing through the course of the year as additional predator-prey interactions emerged in the lower trophic levels. Finally, our studies re-emphasised the role that the simple phytoplankton-krill-higher predator food chain plays in this Southern Ocean region, particularly south of the SACCF. To the north, alternative food chains, such as those involving copepods, macrozooplankton and mesopelagic fish, were increasingly important. Continued ocean warming in this region is likely to increase the prevalence of such alternative such food chains with Antarctic krill predicted to move southwards.

  14. Spatial and temporal variability of the refractivity over Tahiti from a coarse network of GPS stations

    Science.gov (United States)

    Serafini, J.; Fadil, A.; Sichoix, L.; Barriot, J.

    2010-12-01

    Slant wet delays (SWD) caused by the presence of water vapor in the atmosphere are routinely obtained from GPS measurements. Powerful tomography techniques have been developed to derive from them the refractivity of the atmosphere, which could be subject to strong spatial and temporal variations, especially over tropical zones. In this poster we model the spatial and temporal variability of the refractivity over the Tahiti Island. In a first study, we model the spatial part of the variability. For this purpose, GPS data spanning a four months period (June-Sept 2010) from a coarse network of nine stations are analyzed using the GAMIT software package. In particular, we found that the SWD variability is more important at the South East of the Island. In a second study we reconstruct the temporal part of the variability. For this purpose, ten years of GPS data from the IGS station THTI, located on the Punaauia suburb of Papeete are processed with respect to the precise point positioning (PPP) mode of the GIPSY-OASIS II software package. The derived SWD allow us to reconstruct, through a regularized inverse process, time series of the ZWD and North / East gradients of the refractivity. We show that the main components of the SWD are relative to semi-diurnal and seasonal terms. Finally, this spatio-temporal model of the refractivity permits us to build a robust estimate of the covariance matrix of the underlying stochastic process.

  15. Spatial variability of soil potassium in sugarcane areas subjected to the application of vinasse

    Directory of Open Access Journals (Sweden)

    LAÉRCIO A. DE CARVALHO

    2014-12-01

    Full Text Available When deposited on land the vinasse can promote improvement in fertility, however, often fertilizer application occurs in areas considered homogeneous, without taking into account the variability of the soil. The objective of this study was to evaluate the effect of vinasse application on potassium content in two classes of soils cultivated with sugarcane, and characterize the spatial variability of soil using geostatistical techniques. In the 2010 and 2011 crop year, soil samples were collected from an experimental grid at 0-0.2 and 0.2-0.4 m depth in three soils cultivated with sugarcane, totaling 90 samplings in each grid, for the determination of pH, calcium (Ca, magnesium (Mg, potassium (K, phosphorus (P, aluminum (Al and potential acidity (H + Al. The data have been submitted to analysis of descriptive statistics and the K attribute was subjected to geostatistical analysis. The coefficient of variation indicated medium and high variability of K for the three soils. The results showed that the spatial dependence of K increased in depth to FRce and decreased to PHlv, indicating that the attribute could have followed the pattern of distribution of clay in depth. The investigation of the spatial variability of K on the surface and subsurface soils provided the definition of management zones with different levels of fertility, which can be organized into sub-areas for a more efficient management of the resources and the environment.

  16. Field Scale Studies on the Spatial Variability of Soil Quality Indicators in Washington State, USA

    Directory of Open Access Journals (Sweden)

    Jeffrey L. Smith

    2011-01-01

    Full Text Available Arable lands are needed for sustainable agricultural systems to support an ever-growing human population. Soil quality needs to be defined to assure that new land brought into crop production is sustainable. To evaluate soil quality, a number of soil attributes will need to be measured, evaluated, and integrated into a soil-quality index using the multivariable indicator kriging (MVIK procedure. This study was conducted to determine the spatial variability and correlation of indicator parameters on a field scale with respect to soil quality and suitability for use with MVIK. The variability of the biological parameters decreased in the order of respiration > enzyme assays and qCO2 > microbial biomass C. The distribution frequency of all parameters except respiration were normal although the spatial distribution across the landscape was highly variable. The biological parameters showed little correlation with each other when all data points were considered; however, when grouped in smaller sections, the correlations were more consistent with observed patterns across the field. To accurately assess soil quality, and arable land use, consideration of spatial and temporal variability, soil conditions, and other controlling factors must be taken into account.

  17. [Spatial pattern of soil fertility in Bashan tea garden: a prediction based on environmental auxiliary variables].

    Science.gov (United States)

    Qin, Le-feng; Yang, Chao; Lin, Fen-fang; Yang, Ning; Zheng, Xin-yu; Xu, Hong-wei; Wang, Ke

    2010-12-01

    Taking topographic factors and NDVI as auxiliary variables, and by using regression-kriging method, the spatial variation pattern of soil fertility in Bashan tea garden in the hilly area of Fuyang City was explored. The spatial variability of the soil fertility was mainly attributed to the structural factors such as relative elevation and flat/vertical curvature. The lower the relative elevation, the worse the soil fertility was. The overall soil fertility level was relatively high, and the area with lower soil fertility only accounted for 5% of the total. By using regression-kriging method with relative elevation as auxiliary variable, the prediction accuracy of soil fertility was obviously higher than that by using ordinary kriging method, with the mean error and root mean square error being 0. 028 and 0. 108, respectively. It was suggested that the prediction method used in this paper could fully reflect the effects of environmental variables on soil fertility , improve the prediction accuracy about the spatial pattern of soil fertility, and provide scientific basis for the precise management of tea garden.

  18. Spatial and temporal variability of snow depth and SWE in a small mountain catchment

    Directory of Open Access Journals (Sweden)

    T. Grünewald

    2010-01-01

    Full Text Available The spatio-temporal variability of the mountain snow cover determines the avalanche danger, snow water storage, permafrost distribution and the local distribution of fauna and flora. Using a new type of terrestrial laser scanner (TLS, which is particularly suited for measurements of snow covered surfaces, snow depth, snow water equivalent (SWE and melt rates have been monitored in a high alpine catchment during an ablation period. This allowed for the first time to get a high resolution (2.5 m cell size picture of spatial variability and its temporal development. A very high variability in which maximum snow depths between 0–9 m at the end of the accumulation season was found. This variability decreased during the ablation phase, although the dominant snow deposition features remained intact. The spatial patterns of calculated SWE were found to be similar to snow depth. Average daily melt rate was between 15 mm/d at the beginning of the ablation period and 30 mm/d at the end. The spatial variation of melt rates increased during the ablation rate and could not be explained in a simple manner by geographical or meteorological parameters, which suggests significant lateral energy fluxes contributing to observed melt. It could be qualitatively shown that the effect of the lateral energy transport must increase as the fraction of snow free surfaces increases during the ablation period.

  19. Rainfall variability over Alagoas under the influences of SST anomalies

    Science.gov (United States)

    Lyra, G. B.; Oliveira-Júnior, J. F.; Gois, G.; Cunha-Zeri, G.; Zeri, M.

    2017-04-01

    The rainfall variability for the state of Alagoas, Northeast of Brazil, was evaluated based on the Standardized Precipitation Index (SPI). Harmonic decomposition was applied to 31 years-long (1960-1990) series of SPI, from 33 stations, to relate their modes of variability to El Niño-Southern Oscillation (ENSO) and the Atlantic Ocean sea surface temperature (SST). The most important harmonics identified by the spectral analysis had periods of 10-15 and 2-3 years, followed by other oscillations with smaller periods. The 10-15 years harmonic was associated with the Atlantic interhemispheric SST gradient (AITG), a cross-equatorial dipole which impacts the northeast region of Brazil by influencing the position of the intertropical convergence zone (ITCZ), leading to dry or wet conditions. The 2-3 years harmonic was consistent with the variability of ENSO events. The harmonic analysis is a powerful tool to identify the principal modes of variability of SPI. Although the magnitude of SPI is underestimated in some cases, this tool significantly increases the knowledge of the main drivers of rainfall and droughts in the region.

  20. Spatial variability of anaerobic processes and wastewater pH in force mains

    DEFF Research Database (Denmark)

    Rudelle, Elise Alice; Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild;

    2016-01-01

    The present study focuses on anaerobic organic matter transformation processes in force mains for the purpose of improving existing sewer process models. Wastewater samples were obtained at 100 m intervals from a 1 km long pilot scale force main and measured for several wastewater parameters. Tra....... A significant spatial variablilty was observed for the average transformation rates of all parameters........ Transformation rates for selected parameters were calculated and their spatial variability analyzed. In terms of electron transfer, fermentation was the most significant process, resulting in a net volatile fatty acid formation of 0.83 mmol/L. Sulfate reduction resulted in a production of 0.73 mmol...

  1. Influence of internal variability on population exposure to hydroclimatic changes

    Science.gov (United States)

    Mankin, Justin S.; Viviroli, Daniel; Mekonnen, Mesfin M.; Hoekstra, Arjen Y.; Horton, Radley M.; E Smerdon, Jason; Diffenbaugh, Noah S.

    2017-04-01

    Future freshwater supply, human water demand, and people’s exposure to water stress are subject to multiple sources of uncertainty, including unknown future pathways of fossil fuel and water consumption, and ‘irreducible’ uncertainty arising from internal climate system variability. Such internal variability can conceal forced hydroclimatic changes on multi-decadal timescales and near-continental spatial-scales. Using three projections of population growth, a large ensemble from a single Earth system model, and assuming stationary per capita water consumption, we quantify the likelihoods of future population exposure to increased hydroclimatic deficits, which we define as the average duration and magnitude by which evapotranspiration exceeds precipitation in a basin. We calculate that by 2060, ∽31%-35% of the global population will be exposed to >50% probability of hydroclimatic deficit increases that exceed existing hydrological storage, with up to 9% of people exposed to >90% probability. However, internal variability, which is an irreducible uncertainty in climate model predictions that is under-sampled in water resource projections, creates substantial uncertainty in predicted exposure: ∽86%-91% of people will reside where irreducible uncertainty spans the potential for both increases and decreases in sub-annual water deficits. In one population scenario, changes in exposure to large hydroclimate deficits vary from -3% to +6% of global population, a range arising entirely from internal variability. The uncertainty in risk arising from irreducible uncertainty in the precise pattern of hydroclimatic change, which is typically conflated with other uncertainties in projections, is critical for climate risk management that seeks to optimize adaptations that are robust to the full set of potential real-world outcomes.

  2. The spatial heterogeneity between Japanese encephalitis incidence distribution and environmental variables in Nepal.

    Directory of Open Access Journals (Sweden)

    Daniel E Impoinvil

    Full Text Available BACKGROUND: To identify potential environmental drivers of Japanese Encephalitis virus (JE transmission in Nepal, we conducted an ecological study to determine the spatial association between 2005 Nepal JE incidence, and climate, agricultural, and land-cover variables at district level. METHODS: District-level data on JE cases were examined using Local Indicators of Spatial Association (LISA analysis to identify spatial clusters from 2004 to 2008 and 2005 data was used to fit a spatial lag regression model with climate, agriculture and land-cover variables. RESULTS: Prior to 2006, there was a single large cluster of JE cases located in the Far-West and Mid-West terai regions of Nepal. After 2005, the distribution of JE cases in Nepal shifted with clusters found in the central hill areas. JE incidence during the 2005 epidemic had a stronger association with May mean monthly temperature and April mean monthly total precipitation compared to mean annual temperature and precipitation. A parsimonious spatial lag regression model revealed, 1 a significant negative relationship between JE incidence and April precipitation, 2 a significant positive relationship between JE incidence and percentage of irrigated land 3 a non-significant negative relationship between JE incidence and percentage of grassland cover, and 4 a unimodal non-significant relationship between JE Incidence and pig-to-human ratio. CONCLUSION: JE cases clustered in the terai prior to 2006 where it seemed to shift to the Kathmandu region in subsequent years. The spatial pattern of JE cases during the 2005 epidemic in Nepal was significantly associated with low precipitation and the percentage of irrigated land. Despite the availability of an effective vaccine, it is still important to understand environmental drivers of JEV transmission since the enzootic cycle of JEV transmission is not likely to be totally interrupted. Understanding the spatial dynamics of JE risk factors may be

  3. Spatial Variability Some Physical and Chemical Prpperties Soil surface In Dasht-e-Tabriz Different Landforms

    Science.gov (United States)

    Foroughifar, Hamed; Asghar Jafarzadeh, Ali; Torabi, Hosien; Aliasgharzad, Naser; Toomanian, Norair

    2010-05-01

    Spatial distribution of soil properties at the field and watershed scale(region scale) affect yield potential, hydrologic responses , and transport of herbicides and No3 to surface or groundwater.The present study aim was to evaluate some physical and chemical properties spatial variability and frequency distribution within and between landforms of Dash-e-Tabriz in the northwest of Iran.For this evaluation 98 samples from soils surface of layer according to grid sampling design and with 500-1000 meters distance based on soils variability were selected and analysed.Landforms were hill, piedmont plain, plain, river alluvial plain and lowland.The study of soil variables frequency distribution showed that Bd, CEC, Caco3, pH,clay and silt follow normal distribution ,which to study their variation one can use parametric statistical method.Variables such as MWD, N(total), SAR, EC, P(available) and sand showed log-normal distribution,that for their variation study,should first be transformed to a logarithmic scale.The variables frequency distribution increase within landforms,which in lowland, hill, and river alluvial plain they showed normal distribution and only EC in piedmont plain and sand, OC and N(total) in plain had log-normal distributions.The results indicate significantly differences of soil properties distribution among landforms,which clay ,pH, EC ,SAR and MWD, CEC, Bd, N(total), OC, P(available), sand, silt were strongly and moderately spatial dependent respectively and Caco3 had no spatial dependence and it is following nugget model.These results indicate that strong spatial dependence due to the effects of intrinsic factors such as parent material, relief and soil types. Also soil properties variations result from variation in depositional environments and or differences in pedogenic or hydrologic processes for different landform positions,and so it can be affected by the flood irrigation,fertilizeir addition,high watertable level or agriculture practices

  4. Investigating coastal erosion variability and framework geology influence along the Grand Strand, South Carolina

    Science.gov (United States)

    Dolan, Aundrea Marie

    Increasing erosional pressures along coastal systems require a better understanding of the mechanisms of natural and human-induced alterations. This is especially important in sediment-starved coastal systems where the effects from geologic framework may exert a disproportionate influence on shoreline behavior. Existing studies into geologic framework and shoreline variability are comprehensive and well documented; yet analysis into the spatial relationships between shoreline variability, lower shoreface morphodynamics, and framework in South Carolina is limited. The Grand Strand region of South Carolina has an extensive set of geophysical data, such as CHIRP seismic, sidescan sonar, borehole logs, and inner shelf cores. In addition, there is a rich suite of RTK-DGPS surveys of a shoreline contour (MHW; 0.625 m) collected monthly since 2007 to consider shoreline variability over 52 km of coastline. Calculation of various statistical parameters using the USGS Digital Shoreline Analysis System v4.2 software, including end point rate (EPR), linear regression rate (LRR) and shoreline change envelope (SCE), provides quantitative assessment of shoreline behavior. Spectral analysis is utilized to define patterns in spatial variability. In effort to target the sediment-limited lower shoreface, a multibeam survey of the region was acquired and identified sections of low relief, low backscatter cuspate-like linear scour depression features in close proximity to the depth of closure. The 6-meter contour wad digitized onto backscatter imagery and intensity values were extracted and correlated to shoreline (MHW) change throughout the study area. Chi-square analysis and correlations between geologic and physical metrics (e.g. paleochannel presence, shoreface slope, backscatter intensity) were computed to identify spatial relationships. Analyses indicate a relationship between shoreline change and backscatter intensity where deep paleochannels were present. Furthermore, power

  5. Spatial Variability of Indicators of Jiaokou Reservoir Under Different Sampling Scales

    Directory of Open Access Journals (Sweden)

    WEI Wen-juan

    2016-12-01

    Full Text Available This research determined total nitrogen, total phosphorus, ammonia nitrogen and potassium permanganate contents in different scales of Jiaokou reservoir with the purpose of exploring the applicability of spatial variability and its characteristic in different sampling scales. The results showed that, compared the sampling scales of 100 m with 200 m, there were some differences among four indicators in the spatial variation, interpolation simulation and spatial distribution. About the testing model fit, the fitting model for the total nitrogen, permanganate index was Gaussian model, the fitting model for total phosphorus, ammonia nitrogen was the spherical model; Combining evaluation of parameters of models and comprehensive evaluation of spatial interpolation, total nitrogen, total phosphorus showed stronger spatial correlation and better interpolation simulation quality on the sampling scales of 200 m, while total phosphorus and permanganate index showed certain advantages on the 100 m scale; On the aspect of spatial distributions, the contents of ammonia nitrogen and potassium permanganate were mainly affected by human factors, the total phosphorus was affected by internal factors of the reservoir, while total nitrogen was closely related to farming activities around reservoir. The above results showed that total nitrogen, ammonia nitrogen were more available for the 200 m scales and total phosphorus, potassium permanganate were more available for the 100 m scales.

  6. Mapping spatial variability of soil salinity in a coastal paddy field based on electromagnetic sensors.

    Science.gov (United States)

    Guo, Yan; Huang, Jingyi; Shi, Zhou; Li, Hongyi

    2015-01-01

    In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles.

  7. Spatial and temporal variability of grass cover in two olive grove catchments on contrasting soil types

    Science.gov (United States)

    Aguilera, Laura; Taguas, Encarnación V.; Gimeno, Enrique; Gómez, José A.

    2013-04-01

    mechanically killed by several tractor passes. Ground cover was evaluated by a field surveys (4 per year) in which the same areas were measured at an approximate density of 4 samples/ha. In each point, over a 0.25 m2 area ground cover was measured using photographs, then point measurements were interpolated using method of Inverse Distance Weighting methods, to generate continuous distribution maps. The spatial and temporal evolution of ground cover in both farms presented a notably different patterns in both farms. In "La Conchuela", maximum values of cover can be reached in winter (61%, Dec-2011) while in "Arroyo Blanco", the maximum values were observed during the spring (50% May-2011) and are dramatically lower in the seasons of summer and autumn. These differences are justified by the influence of the management, the precipitation regime and the soil qualities such as the depth. On the other hand, the large spatial variability of ground cover measurements in both catchments, with coefficients of variation between 41 and 167%, was mainly led by the topography. In both farms the highest values of ground cover were found in those areas with deeper soils located in also in converging areas where surface runoff is concentrated. In the highest and shallowest area, soil management operations might improve the establishment of the vegetation as well as to address the growing in the most erosive periods. Finally, the impact of grass cover on the hydrological and erosive responses in the catchment is also discussed. References Aguilera, L. 2012. Estudio de cubiertas vegetales para el control de la erosión en olivar. Evaluación espacio-temporal en dos fincas comerciales, y exploración de nuevas opciones de cubiertas. Master Thesis. University of Cordoba. Gómez, J.A., Giráldez, J.V. Erosión y degradación de suelos. In: Sostenibilidad de la producción de olivar en Andalucía. Gómez, J.A. (Editor). Junta de Andalucía. Sevilla, p. 45-86. Gómez, J.A., Sobrinho, T.A., Gir

  8. Use of precision agriculture technology to investigate spatial variability in nitrogen yields in cut grassland.

    Science.gov (United States)

    Bailey, J S; Wang, K; Jordan, C; Higgins, A

    2001-01-01

    Spatial variability in N uptake and utilisation by swards within uniformly managed field units could be responsible for a significant proportion of the NH3, N2O, NO3- and NOx (NO and NO2) 'pollutants' generated by agriculture and released to the environment. An investigation was commenced, therefore, to quantify, map and explain the spatial variability in sward N yield in a 'large' silage field and to assess the potential for managing this variability using some of the latest precision agriculture technology. Sward dry matter (DM) and N yields were predicted from the results of plant tissue analyses using mathematical models. Sward N yields were found to vary greatly across the field seemingly because of differences in net soil N mineralisation, but the pattern of variability appeared to remain constant with time. Conventional soil analysis of a range of soil chemical and physical properties, however, failed to explain this variability. It was concluded that the N-yield distribution map might be used in place of soil analysis as the basis for varying the rates of N application to different parts of the field with the twin objectives of maximising fertiliser use efficiency and minimising N emissions to air and water.

  9. Spatial variable selection methods for investigating acute health effects of fine particulate matter components.

    Science.gov (United States)

    Boehm Vock, Laura F; Reich, Brian J; Fuentes, Montserrat; Dominici, Francesca

    2015-03-01

    Multi-site time series studies have reported evidence of an association between short term exposure to particulate matter (PM) and adverse health effects, but the effect size varies across the United States. Variability in the effect may partially be due to differing community level exposure and health characteristics, but also due to the chemical composition of PM which is known to vary greatly by location and time. The objective of this article is to identify particularly harmful components of this chemical mixture. Because of the large number of highly-correlated components, we must incorporate some regularization into a statistical model. We assume that, at each spatial location, the regression coefficients come from a mixture model with the flavor of stochastic search variable selection, but utilize a copula to share information about variable inclusion and effect magnitude across locations. The model differs from current spatial variable selection techniques by accommodating both local and global variable selection. The model is used to study the association between fine PM (PM <2.5μm) components, measured at 115 counties nationally over the period 2000-2008, and cardiovascular emergency room admissions among Medicare patients.

  10. Spatial variability studies in São Paulo, Brazil along the last twenty five years

    Directory of Open Access Journals (Sweden)

    Sidney Rosa Vieira

    2010-01-01

    Full Text Available Soil properties vary in space due to many causes. For this reason it is wise to know the magnitude and behaviour of the variability for adequate data analysis and decision making. Our work on spatial variability of soil properties in São Paulo, Brazil began in 1982 with a very simple soil sampling in a small field. Much progress has been made since then on sampling designs, field equipment and methods, and mostly on computation equipment and softwares. This paper reports the results corresponding to some aspects of this progress, as far as the field, analysis and computation work are concerned. The objective of this study was to illustrate the use of geostatistics in data analysis for three sampling conditions on long term no-tillage system. The analysis is done on a wide range of field scales, variables, sampling schemes as well as repeating sampling scheme for the same variable in different years. Semivariograms are compared for the same variables in different scales and sampling dates and depths as to provide a guide for sampling spacing and number of samples. Normalized crop yield parameters for many years are used in the discussion of time variability and on the use of yield maps to locate management zones. The time of the year in which measurements of soil physical properties are made affected the results both in terms of descriptive statistical and spatial dependence parameters. Crop yields changed (soybean decrease and maize increase with time of no-tillage but the real cause was not identified. The length of time with no-tillage affected the range of dependence for the main crops (increased for soybean, maize and oats and therefore increased the size of the homogeneous management zones. The evolution of the sampling grid from 20 m with 63 sampling points to 10 m with 302 sampling points allowed for a much better knowledge of the spatial variability of crop yields but it had the reverse effect on the spatial variability of soil physical

  11. Spatial variability of soil organic carbon in the forestlands of northeast China

    Institute of Scientific and Technical Information of China (English)

    Ling Liu; Haiyan Wang; Wei Dai; Xiangdong Lei; Xiaojuan Yang; Xu Li

    2014-01-01

    Soil organic carbon (SOC) is an effective indicator of soil fertility and productivity, and it varies spatially and temporally in relation to other soil properties. Spatial variability of SOC in the forestlands of northeast China was characterized using geostatistics. Soil samples at the depths of 0-20 cm, 20-40 cm and 40-60 cm were collected from six-ty-three temporary plots to evaluate SOC concentration and density (SOCD) and other soil properties. We analyzed correlations between SOC and soil properties. Soil organic carbon concentrations were high. The total amount of C stored in soil (0-60 cm) was 16.23 kg·m-2 with the highest SOCD of 7.98 kg×m-2 in topsoil. Soil properties in most cases differed by horizon, suggesting different processes and effects in each horizon. Soil organic carbon had positive relationships with total N, P and K as well as readily available K, but did not show a significant posi-tive correlation with available P. Spatial factors including elevation, slope and aspect affected SOC distribution. Soil organic carbon at 0-60 cm had strong spatial autocorrelation with nugget/sill ratio of 5.7%, and moderate structured dependence was found at 0-20 cm, which indicated the existence of a highly developed spatial structure. Spatial distributions of SOC concentration and SOCD were estimated using regres-sion-kriging, with higher prediction accuracy than ordinary kriging. The fractal dimension of SOC indicated the preferential pattern of SOC dis-tribution, with the greatest spatial heterogeneity and strongest spatial dependence in the northeast-southwest direction.

  12. Progression paths in children's problem solving: The influence of dynamic testing, initial variability, and working memory.

    Science.gov (United States)

    Resing, Wilma C M; Bakker, Merel; Pronk, Christine M E; Elliott, Julian G

    2017-01-01

    The current study investigated developmental trajectories of analogical reasoning performance of 104 7- and 8-year-old children. We employed a microgenetic research method and multilevel analysis to examine the influence of several background variables and experimental treatment on the children's developmental trajectories. Our participants were divided into two treatment groups: repeated practice alone and repeated practice with training. Each child received an initial working memory assessment and was subsequently asked to solve figural analogies on each of several sessions. We examined children's analogical problem-solving behavior and their subsequent verbal accounts of their employed solving processes. We also investigated the influence of verbal and visual-spatial working memory capacity and initial variability in strategy use on analogical reasoning development. Results indicated that children in both treatment groups improved but that gains were greater for those who had received training. Training also reduced the influence of children's initial variability in the use of analogical strategies with the degree of improvement in reasoning largely unrelated to working memory capacity. Findings from this study demonstrate the value of a microgenetic research method and the use of multilevel analysis to examine inter- and intra-individual change in problem-solving processes. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Influence of the North Atlantic on simulated atmospheric variability

    Directory of Open Access Journals (Sweden)

    Z. X. Li

    2003-06-01

    Full Text Available An atmospheric general circulation model is used to investigate the influence of the North Atlantic Ocean on atmospheric variability. The study covers the period from 1950 to 1994. The observed sea surface temperature and sea ice extension are used to force the atmospheric model. Several configurations of the oceanic boundary conditions were made to isolate the role of the North Atlantic and to study its non-linear interaction with forcings from other oceanic basins. The multi-realization character of the experiments distinguishes between the internal random part and the external forced part of the total variability. The potential predictability can thus be evaluated. The response of the atmosphere is also studied with a modal approach in terms of hemispheric teleconnection patterns. The North Atlantic Ocean has a direct influence on both the Northern Hemisphere annular mode and the Pacific-North-America pattern, leading to a weak predictability. However the direct response is largely modulated by forcings from other oceanic basins. The non-linearity of the system compensates the predictable component of the annular mode induced by the North Atlantic forcing. Furthermore it reduces the forced component of the Pacific-North-America pattern, increasing its chaoticity.

  14. Spatial and temporal CH4 flux variability in a shallow tropical floodplain lake, Pantanal, South America

    Science.gov (United States)

    Peixoto, R.; Enrich Prast, A.; Silva, E. C.; Pontual, L.; Marotta, H.; Pinho, L.; Bastviken, D.

    2012-04-01

    Spatial and temporal CH4 flux variability in a shallow tropical floodplain lake, Pantanal, South America Peixoto, R, Enrich-Prast, A., Silva, E. C., Pontual, L., Marotta, H., Pinho, L. Q. and Bastviken, D. Methane (CH4) is an important greenhouse gas produced during anaerobic decomposition of organic matter (OM). It can play a significant role in carbon emissions from tropical aquatic ecosystems to the atmosphere and have a substantial participation in greenhouse gas balances. However, most studies report low numbers of short-term (≤ 24h) measurements in each system and the spatial and temporal variability is poorly understood. In this study we analyzed the temporal and spatial variability of CH4 emissions from a shallow Pantanal lake. Pantanal is the world's largest savanna tropical floodplain with a significant input of organic matter from the drainage area around and an annual inundation pulse. Methane fluxes were measured in September 2008 with floating chambers over 24 hour periods for five consecutive days. We used > 20 chambers along transects from the marginal vegetated regions of the lake to the central parts of the lake. Methane fluxes were determined as described by Bastviken et al. 2010 (doi: 10.1021/es1005048). There was no significant difference of methane fluxes among sampling days. Methane fluxes at the vegetated area and the margin were significantly higher than at central parts of the lake showing clearly the importance of different compartments within lakes. This study indicates that a) 24 hour measurements may be representative for time perspectives of a week given similar weather conditions, while b) spatial variability within lakes must be considered to correctly evaluate CH4 emissions from aquatic systems.

  15. Verification of Spatial Forecasts of Continuous Meteorological Variables Using Categorical and Object-Based Methods

    Science.gov (United States)

    2016-08-01

    SUPPLEMENTARY NOTES 14. ABSTRACT Spatial forecasts from Numerical Weather Prediction (NWP) models of meteorological variables to support Army operations...contingency- table scores and statistics that can be calculated and, when analyzed together, may reveal more information about model performance and provide a... Model evaluation tools version 4.1 (METv4.1), user’s guide 4.1. Boulder (CO); 2013 May. [NOAA] Meteorological assimilation data ingest system (MADIS

  16. Fine scale spatial variability of microbial pesticide degradation in soil: scales, controlling factors, and implications

    Directory of Open Access Journals (Sweden)

    Arnaud eDechesne

    2014-12-01

    Full Text Available Pesticide biodegradation is a soil microbial function of critical importance for modern agriculture and its environmental impact. While it was once assumed that this activity was homogeneously distributed at the field scale, mounting evidence indicates that this is rarely the case. Here, we critically examine the literature on spatial variability of pesticide biodegradation in agricultural soil. We discuss the motivations, methods, and main findings of the primary literature. We found significant diversity in the approaches used to describe and quantify spatial heterogeneity, which complicates inter-studies comparisons. However, it is clear that the presence and activity of pesticide degraders is often highly spatially variable with coefficients of variation often exceeding 50% and frequently displays nonrandom spatial patterns. A few controlling factors have tentatively been identified across pesticide classes: they include some soil characteristics (pH and some agricultural management practices (pesticide application, tillage, while other potential controlling factors have more conflicting effects depending on the site or the pesticide. Evidence demonstrating the importance of spatial heterogeneity on the fate of pesticides in soil has been difficult to obtain but modelling and experimental systems that do not include soil’s full complexity reveal that this heterogeneity must be considered to improve prediction of pesticide biodegradation rates or of leaching risks. Overall, studying the spatial heterogeneity of pesticide biodegradation is a relatively new field at the interface of agronomy, microbial ecology, and geosciences and a wealth of novel data is being collected from these different disciplinary perspectives. We make suggestions on possible avenues to take full advantage of these investigations for a better understanding and prediction of the fate of pesticides in soil.

  17. Linkage between the temporal and spatial variability of dissolved organic matter and whole-stream metabolism

    Directory of Open Access Journals (Sweden)

    S. Halbedel

    2013-08-01

    Full Text Available Dissolved organic matter (DOM is an important resource for microbes, thus affecting whole-stream metabolism. However, the factors influencing its chemical composition and thereby also its bio-availability are complex and not thoroughly understood. It was hypothesized that whole-stream metabolism is linked to DOM composition and that the coupling of both is influenced by seasonality and different land-use types. We tested this hypothesis in a comparative study on two pristine forestry streams and two non-forestry streams. The investigated streams were located in the Harz Mountains (central Europe, Germany. The metabolic rate was measured with a classical two-station oxygen change technique and the variability of DOM with fluorescence spectroscopy. All streams were clearly net heterotrophic, whereby non-forestry streams showed a higher primary production, which was correlated to irradiance and phosphorus concentration. We detected three CDOM components (C1, C2, C3 using parallel factor (PARAFAC analysis. We compared the excitation and emission maxima of these components with the literature and correlated the PARAFAC components with each other and with fluorescence indices. The correlations suggest that two PARAFAC components are derived from allochthonous sources (C1, C3 and one is derived autochthonously (C2. The chromophoric DOM matrix was dominated by signals of humic-like substances with a highly complex structure, followed by humic-like, fulfic acids, low-molecular-weight substances, and with minor amounts of amino acids and proteins. The ratios of these PARAFAC components (C1 : C2, C1 : C3, C3 : C2 differed with respect to stream types (forestry versus non-forestry. We demonstrated a significant correlation between gross primary production (GPP and signals of autochthonously derived, low-molecular-weight humic-like substances. A positive correlation between P / R (i.e. GPP/daily community respiration and the fluorescence index FI suggests

  18. Summer Temperature and Spatial Variability of all-Cause Mortality in Surat City, India.

    Science.gov (United States)

    Rathi, S K; Desai, V K; Jariwala, P; Desai, H; Naik, A; Joseph, A

    2017-01-01

    Ample information is available on extreme heat associated mortality for few Indian cities, but scant literature is available on effect of temperature on spatial variability of all-cause mortality for coastal cities. To assess the effect of daily maximum temperature, relative humidity and heat index on spatial variability of all-cause mortality for summer months (March to May) from 2014 to 2015 for the urban population of Surat (coastal) city. Retrospective analysis of the all-cause mortality data with temperature and humidity was performed on a total of 9,237 deaths for 184 summer days (2014-2015). Climatic and all-cause mortality data were obtained through Tutiempo website and Surat Municipal Corporation respectively. Bivariate analysis performed through SPSS. Mean daily mortality was estimated at 50.2 ± 8.5 for the study period with a rise of 20% all-cause mortality at temperature ≥ 40°C and rise of 10% deaths per day during extreme danger level (HI: > 54°C) days. Spatial (Zone wise) analysis revealed rise of 61% all-cause mortality for Southeast and 30% for East zones at temperature ≥ 40°C. All-cause mortality increased on high summer temperature days. Presence of spatial variation in all-cause mortality provided the evidence for high risk zones. Findings may be helpful in designing the interventions at micro level.

  19. Summer temperature and spatial variability of all-cause mortality in Surat city, India

    Directory of Open Access Journals (Sweden)

    S K Rathi

    2017-01-01

    Full Text Available Background: Ample information is available on extreme heat associated mortality for few Indian cities, but scant literature is available on effect of temperature on spatial variability of all-cause mortality for coastal cities. Objective: To assess the effect of daily maximum temperature, relative humidity and heat index on spatial variability of all-cause mortality for summer months (March to May from 2014 to 2015 for the urban population of Surat (coastal city. Materials and Methods: Retrospective analysis of the all-cause mortality data with temperature and humidity was performed on a total of 9,237 deaths for 184 summer days (2014-2015. Climatic and all-cause mortality data were obtained through Tutiempo website and Surat Municipal Corporation respectively. Bivariate analysis performed through SPSS. Observations: Mean daily mortality was estimated at 50.2 ± 8.5 for the study period with a rise of 20% all-cause mortality at temperature ≥ 40°C and rise of 10% deaths per day during extreme danger level (HI: > 54°C days. Spatial (Zone wise analysis revealed rise of 61% all-cause mortality for Southeast and 30% for East zones at temperature ≥ 40°C. Conclusions: All-cause mortality increased on high summer temperature days. Presence of spatial variation in all-cause mortality provided the evidence for high risk zones. Findings may be helpful in designing the interventions at micro level.

  20. Spatial variability of chemical and physical attributes of dystrophic Red-Yellow Latosol in no tillage

    Directory of Open Access Journals (Sweden)

    João Vidal de Negreiros Neto

    2014-02-01

    Full Text Available Knowledge of spatial variability in chemical and physical properties of the soil is very important, especially for precision agriculture. Geostatistics is seeking to improve techniques that can enable the correct and responsible use of soil. So during the agricultural year 2011/2012 in an area of direct planting the corn crop in the municipality of Gurupi (TO, in the Brazilian Cerrado, aimed to analyze the spatial variability of chemical and physical properties in a Typic Dystrophic tillage. Was installed sampling grid for the collection of soil, with 100 sampling points in an area of 1755m2. The contents of available phosphorus, organic matter, pH (H2O, concentrations of K +, Ca2+, Mg2+, the sum of values and base saturation (BS, V at depths of 0-0.20 m, and resistance to penetration (RP at depths 0-0.05 m, 0.05-0.10 m, 0.10-0.20 m and 0.20-0.40 m and bulk density (Ds. We conducted a descriptive analysis classic, with the aid of statistical software ASSISTAT, and then were modeled semivariograms for all attributes, resulting in their cross-validation and kriging maps. The chemical and physical properties of soil, except the base saturation (V, spatial dependence. Probably the discontinuity of the spatial dependence of Vvalue, is due to fertility management over the years.

  1. Spatial variability of the properties of marsh soils and their impact on vegetation

    Science.gov (United States)

    Sidorova, V. A.; Svyatova, E. N.; Tseits, M. A.

    2015-03-01

    Spatial variability of the properties of soils and the character of vegetation was studied on seacoasts of the Velikii Island in the Kandalaksha Bay of the White Sea. It was found that the chemical and physicochemical properties of marsh soils (Tidalic Fluvisols) are largely dictated by the distance from the sea and elevation of the sampling point above sea level. The spatial distribution of the soil properties is described by a quadratic trend surface. With an increase in the distance from the sea, the concentration of ions in the soil solution decreases, and the organic carbon content and soil acidity become higher. The spatial dependence of the degree of variability in the soil properties is moderate. Regular changes in the soil properties along the sea-land gradient are accompanied by the presence of specific spatial patterns related to the system of temporary water streams, huge boulders, and beached heaps of sea algae and wood debris. The cluster analysis made it possible to distinguish between five soil classes corresponding to the following plant communities: barren surface (no permanent vegetation), clayey-sandy littoral with sparse halophytes, marsh with large rhizomatous grasses, and grass-forb-bunchberry vegetation of forest margins. The subdivision into classes is especially distinct with respect to the concentration of chloride ions. The following groups of factors affect the distribution of vegetation: the composition of the soil solution, the height above sea level, the pH of water suspensions, and the humus content.

  2. A preliminary characterization of the spatial variability of precipitation at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Hevesi, J.A.; Flint, A.L. [Geological Survey, Mercury, NV (United States); Ambos, D.S. [Foothill Eng. Consultants, Mercury, NV (United States)

    1994-12-31

    Isohyetal maps of precipitation and numerical models for simulating precipitation are needed to help characterize natural infiltration at Yucca Mountain, Nevada. A geostatistical analysis of measured precipitation accumulated from storm periods. Precipitation was measured during a 3.8 year period from January 1990 to October, 1993 using a network of precipitation gages. A total of 34 winter-type storms and 12 summer-type storm, categorized using synoptic weather records, were analyzed using the 1st and 2nd statistical moments and sample variograms. Average standardized variograms indicated good spatial correlation for both storm types with only slight differences in the general spatial structure. Coefficients of variation and average relative variograms indicated that summer storms are characterized by greater variability as compared to winter storms. Models were fitted to the average summer and winter standarized variograms for each storm using the mean storm depth and the coefficient of variation as scaling parameters. Isohyetal maps of 4 representative storms were created using the standarized models. Results indicate that standarized models can be used to simulate the spatial distribution of precipitation depth, provided that the 1st and 2nd moments are known or can be estimated, and that identifiable deterministic trends can be included in the models. A single, fixed model representing the spatial variability of precipitation at Yucca Mountain is not recommended.

  3. Modeling inter-subject variability in fMRI activation location: A Bayesian hierarchical spatial model

    Science.gov (United States)

    Xu, Lei; Johnson, Timothy D.; Nichols, Thomas E.; Nee, Derek E.

    2010-01-01

    Summary The aim of this work is to develop a spatial model for multi-subject fMRI data. There has been extensive work on univariate modeling of each voxel for single and multi-subject data, some work on spatial modeling of single-subject data, and some recent work on spatial modeling of multi-subject data. However, there has been no work on spatial models that explicitly account for inter-subject variability in activation locations. In this work, we use the idea of activation centers and model the inter-subject variability in activation locations directly. Our model is specified in a Bayesian hierarchical frame work which allows us to draw inferences at all levels: the population level, the individual level and the voxel level. We use Gaussian mixtures for the probability that an individual has a particular activation. This helps answer an important question which is not addressed by any of the previous methods: What proportion of subjects had a significant activity in a given region. Our approach incorporates the unknown number of mixture components into the model as a parameter whose posterior distribution is estimated by reversible jump Markov Chain Monte Carlo. We demonstrate our method with a fMRI study of resolving proactive interference and show dramatically better precision of localization with our method relative to the standard mass-univariate method. Although we are motivated by fMRI data, this model could easily be modified to handle other types of imaging data. PMID:19210732

  4. An LES study on the spatial variability impact of surface sensible heat flux (SHF) on the convective boundary layer (CBL)

    Science.gov (United States)

    Kang, S. L.; Chun, J.; Kumar, A.

    2015-12-01

    We study the spatial variability impact of surface sensible heat flux (SHF) on the convective boundary layer (CBL), using the Weather Research and Forecasting (WRF) model in large eddy simulation (LES) mode. In order to investigate the response of the CBL to multi-scale feature of the surface SHF field over a local area of several tens of kilometers or smaller, an analytic surface SHF map is crated as a function of the chosen feature. The spatial variation in the SHF map is prescribed with a two-dimensional analytical perturbation field, which is generated by using the inverse transform technique of the Fourier series whose coefficients are controlled, of which spectrum to have a particular slope in the chosen range of wavelength. Then, the CBL responses to various SHF heterogeneities are summarized as a function of the spectral slope, in terms of mean structure, turbulence statistics and cross-scale processes. The range of feasible SHF heterogeneities is obtained from the SHF maps produced by a land surface model (LSM) of the WRF system. The LSM-derived SHF maps are a function of geographical data on various resolutions. Based on the numerical experiment results with the surface heterogeneities in the range, we will discuss the uncertainty in the SHF heterogeneity and its impact on the atmosphere in a numerical model. Also we will present the range of spatial scale of the surface SHF heterogeneity that significantly influence on the whole CBL. Lastly, we will report the test result of the hypothesis that the spatial variability of SHF is more representative of surface thermal heterogeneity than is the latent heat flux over the local area of several tens of kilometers or smaller.

  5. Gamma-ray attenuation method as an efficient tool to investigate soil bulk density spatial variability

    Energy Technology Data Exchange (ETDEWEB)

    Pires, L.F., E-mail: lfpires@uepg.b [Laboratory of Soil Physics and Environmental Sciences, State University of Ponta Grossa, UEPG, C.E.P. 84.030-900 Ponta Grossa, PR (Brazil); Rosa, J.A. [Laboratory of Soil Physics, Agricultural Research Institute of Parana, IAPAR, C.E.P. 84.001-970 Ponta Grossa, PR (Brazil); Pereira, A.B. [Laboratory of Agrometeorology, State University of Ponta Grossa, UEPG, C.E.P. 84.030-900 Ponta Grossa, PR (Brazil); Arthur, R.C.J.; Bacchi, O.O.S. [Laboratory of Soil Physics, Center for Nuclear Energy in Agriculture, USP/CENA, C.E.P. 13.400-970 Piracicaba, SP (Brazil)

    2009-11-15

    The spatial variability of soil bulk density (rho{sub b}) was measured by using the volumetric ring method (VRM) and the gamma-ray attenuation method (GAM). Collimated radiation from 3.7 GBq of {sup 241}Am was used to evaluate the soil mass attenuation coefficient and its bulk density. Circular lead collimators were adjusted and aligned between source (D = 1, 2 and 3 mm) and detector (D = 4.5 mm). Results of GAM for average rho{sub b} provided good agreement with the corresponding values obtained gravimetrically. Variations in bulk density for different collimator dimensions can be attributed to multiple scattering after photons interaction with soil, mainly for 3 mm collimator size. The best result of rho{sub b} by the nuclear technique was obtained when rho{sub b} represents an average of the measurements for collimators of 1 and 2 mm. Another cause for the differences in rho{sub b} by GAM and VRM is the heterogeneity of soil when the collimated beam can interact with stones or large air-filled holes or channels present in the sample. Therefore, the pattern of spatial variability obtained by VRM was confirmed by GAM for all collimator sizes. This result is a good indication that GAM can be used with success to analyze soil spatial variability.

  6. Influence of temporally variable groundwater flow conditions on point measurements and contaminant mass flux estimations

    DEFF Research Database (Denmark)

    Rein, Arno; Bauer, S; Dietrich, P

    2009-01-01

    is present, the concentration variability due to a fluctuating groundwater flow direction varies significantly within the control plane and between the different realizations. Determination of contaminant mass fluxes is also influenced by the temporal variability of the concentration measurement, especially......Monitoring of contaminant concentrations, e.g., for the estimation of mass discharge or contaminant degradation rates. often is based on point measurements at observation wells. In addition to the problem, that point measurements may not be spatially representative. a further complication may arise...... due to the temporal dynamics of groundwater flow, which may cause a concentration measurement to be not temporally representative. This paper presents results from a numerical modeling study focusing on temporal variations of the groundwater flow direction. "Measurements" are obtained from point...

  7. Spatial variability of biotic and abiotic tree establishment constraints across a treeline ecotone in the Alaska Range

    Science.gov (United States)

    Stueve, K.M.; Isaacs, R.E.; Tyrrell, L.E.; Densmore, R.V.

    2011-01-01

    Throughout interior Alaska (USA), a gradual warming trend in mean monthly temperatures occurred over the last few decades (;2-48C). The accompanying increases in woody vegetation at many alpine treeline (hereafter treeline) locations provided an opportunity to examine how biotic and abiotic local site conditions interact to control tree establishment patterns during warming. We devised a landscape ecological approach to investigate these relationships at an undisturbed treeline in the Alaska Range. We identified treeline changes between 1953 (aerial photography) and 2005 (satellite imagery) in a geographic information system (GIS) and linked them with corresponding local site conditions derived from digital terrain data, ancillary climate data, and distance to 1953 trees. Logistic regressions enabled us to rank the importance of local site conditions in controlling tree establishment. We discovered a spatial transition in the importance of tree establishment controls. The biotic variable (proximity to 1953 trees) was the most important tree establishment predictor below the upper tree limit, providing evidence of response lags with the abiotic setting and suggesting that tree establishment is rarely in equilibrium with the physical environment or responding directly to warming. Elevation and winter sun exposure were important predictors of tree establishment at the upper tree limit, but proximity to trees persisted as an important tertiary predictor, indicating that tree establishment may achieve equilibrium with the physical environment. However, even here, influences from the biotic variable may obscure unequivocal correlations with the abiotic setting (including temperature). Future treeline expansion will likely be patchy and challenging to predict without considering the spatial variability of influences from biotic and abiotic local site conditions. ?? 2011 by the Ecological Society of America.

  8. Spatial variability of biotic and abiotic tree establishment constraints across a treeline ecotone in the Alaska range.

    Science.gov (United States)

    Stueve, Kirk M; Isaacs, Rachel E; Tyrrell, Lucy E; Densmore, Roseann V

    2011-02-01

    Throughout interior Alaska (U.S.A.), a gradual warming trend in mean monthly temperatures occurred over the last few decades (approximatlely 2-4 degrees C). The accompanying increases in woody vegetation at many alpine treeline (hereafter treeline) locations provided an opportunity to examine how biotic and abiotic local site conditions interact to control tree establishment patterns during warming. We devised a landscape ecological approach to investigate these relationships at an undisturbed treeline in the Alaska Range. We identified treeline changes between 1953 (aerial photography) and 2005 (satellite imagery) in a geographic information system (GIS) and linked them with corresponding local site conditions derived from digital terrain data, ancillary climate data, and distance to 1953 trees. Logistic regressions enabled us to rank the importance of local site conditions in controlling tree establishment. We discovered a spatial transition in the importance of tree establishment controls. The biotic variable (proximity to 1953 trees) was the most important tree establishment predictor below the upper tree limit, providing evidence of response lags with the abiotic setting and suggesting that tree establishment is rarely in equilibrium with the physical environment or responding directly to warming. Elevation and winter sun exposure were important predictors of tree establishment at the upper tree limit, but proximity to trees persisted as an important tertiary predictor, indicating that tree establishment may achieve equilibrium with the physical environment. However, even here, influences from the biotic variable may obscure unequivocal correlations with the abiotic setting (including temperature). Future treeline expansion will likely be patchy and challenging to predict without considering the spatial variability of influences from biotic and abiotic local site conditions.

  9. Graffiti for science - erosion painting reveals spatially variable erosivity of sediment-laden flows

    Science.gov (United States)

    Beer, Alexander R.; Kirchner, James W.; Turowski, Jens M.

    2016-12-01

    Spatially distributed detection of bedrock erosion is a long-standing challenge. Here we show how the spatial distribution of surface erosion can be visualized and analysed by observing the erosion of paint from natural bedrock surfaces. If the paint is evenly applied, it creates a surface with relatively uniform erodibility, such that spatial variability in the erosion of the paint reflects variations in the erosivity of the flow and its entrained sediment. In a proof-of-concept study, this approach provided direct visual verification that sediment impacts were focused on upstream-facing surfaces in a natural bedrock gorge. Further, erosion painting demonstrated strong cross-stream variations in bedrock erosion, even in the relatively narrow (5 m wide) gorge that we studied. The left side of the gorge experienced high sediment throughput with abundant lateral erosion on the painted wall up to 80 cm above the bed, but the right side of the gorge only showed a narrow erosion band 15-40 cm above the bed, likely due to deposited sediment shielding the lower part of the wall. This erosion pattern therefore reveals spatial stream bed aggradation that occurs during flood events in this channel. The erosion painting method provides a simple technique for mapping sediment impact intensities and qualitatively observing spatially distributed erosion in bedrock stream reaches. It can potentially find wide application in both laboratory and field studies.

  10. Spatially variable risk factors for malaria in a geographically heterogeneous landscape, western Kenya: an explorative study.

    Science.gov (United States)

    Homan, Tobias; Maire, Nicolas; Hiscox, Alexandra; Di Pasquale, Aurelio; Kiche, Ibrahim; Onoka, Kelvin; Mweresa, Collins; Mukabana, Wolfgang R; Ross, Amanda; Smith, Thomas A; Takken, Willem

    2016-01-04

    Large reductions in malaria transmission and mortality have been achieved over the last decade, and this has mainly been attributed to the scale-up of long-lasting insecticidal bed nets and indoor residual spraying with insecticides. Despite these gains considerable residual, spatially heterogeneous, transmission remains. To reduce transmission in these foci, researchers need to consider the local demographical, environmental and social context, and design an appropriate set of interventions. Exploring spatially variable risk factors for malaria can give insight into which human and environmental characteristics play important roles in sustaining malaria transmission. On Rusinga Island, western Kenya, malaria infection was tested by rapid diagnostic tests during two cross-sectional surveys conducted 3 months apart in 3632 individuals from 790 households. For all households demographic data were collected by means of questionnaires. Environmental variables were derived using Quickbird satellite images. Analyses were performed on 81 project clusters constructed by a traveling salesman algorithm, each containing 50-51 households. A standard linear regression model was fitted containing multiple variables to determine how much of the spatial variation in malaria prevalence could be explained by the demographic and environmental data. Subsequently, a geographically-weighted regression (GWR) was performed assuming non-stationarity of risk factors. Special attention was taken to investigate the effect of residual spatial autocorrelation and local multicollinearity. Combining the data from both surveys, overall malaria prevalence was 24%. Scan statistics revealed two clusters which had significantly elevated numbers of malaria cases compared to the background prevalence across the rest of the study area. A multivariable linear model including environmental and household factors revealed that higher socioeconomic status, outdoor occupation and population density were

  11. Throughfall and its spatial variability beneath xerophytic shrub canopies within water-limited arid desert ecosystems

    Science.gov (United States)

    Zhang, Ya-feng; Wang, Xin-ping; Hu, Rui; Pan, Yan-xia

    2016-08-01

    Throughfall is known to be a critical component of the hydrological and biogeochemical cycles of forested ecosystems with inherently temporal and spatial variability. Yet little is understood concerning the throughfall variability of shrubs and the associated controlling factors in arid desert ecosystems. Here we systematically investigated the variability of throughfall of two morphological distinct xerophytic shrubs (Caragana korshinskii and Artemisia ordosica) within a re-vegetated arid desert ecosystem, and evaluated the effects of shrub structure and rainfall characteristics on throughfall based on heavily gauged throughfall measurements at the event scale. We found that morphological differences were not sufficient to generate significant difference (P decline with the increase in rainfall amount, intensity and duration, and stabilized passing a certain threshold. Our findings highlight the great variability of throughfall beneath the canopies of xerophytic shrubs and the time stability of throughfall pattern among rainfall events. The spatially heterogeneous and temporally stable throughfall is expected to generate a dynamic patchy distribution of soil moisture beneath shrub canopies within arid desert ecosystems.

  12. Temporal and spatial variation of limnological variables and biomass of different macrophyte species in a Neotropical reservoir (São Paulo - Brazil

    Directory of Open Access Journals (Sweden)

    Flávia Bottino

    2013-12-01

    Full Text Available AIM: This study reports an investigation of limnological characteristics and aquatic macrophyte occurrence in a neotropical reservoir in order to assess the spatio-temporal variation of water and sediment variables and their influence on plant distribution. METHODS: Macrophytes, water and sediment samples were collected from a Brazilian reservoir in different seasons from four main arms of the reservoir. In total sixteen water-sediment variables were analyzed including N:P ratio and Trophic State Index. The plants were collected using a quadrat sampling procedure and the dry weight per sample was measured. MANOVA was performed to evaluate spatial and temporal variation of environmental variables as well as seasonal biomass differences. To assess the relationship among environmental variables and macrophytes an ordination analysis (using Canonical Correspondence Analysis: CCA was carried out. RESULTS: The spatial and temporal variation of limnological variables generated a heterogeneous system which supports the presence of different species of macrophyte. pH, dissolved oxygen and sediment composition were important predictors of Polygonum lapathifolium occurrence while nutrients were associated with Eichhornia crassipes and Pistia stratiotes. Inorganic substances were related to biomass variation of Eichhornia azurea and Myriophyllum aquaticum. CONCLUSIONS: The spatial variation of the environmental variables has caused heterogeneity in the reservoir and it may support the occurrence of different species of macrophyte. Limnological variables highlighted in CCA are important to predict the species occurrence and their control in the study area.

  13. Spatial Variability Analysis of Within-Field Winter Wheat Nitrogen and Grain Quality Using Canopy Fluorescence Sensor Measurements

    OpenAIRE

    Xiaoyu Song; Guijun Yang; Chenghai Yang; Jihua Wang; Bei Cui

    2017-01-01

    Wheat grain protein content (GPC) is a key component when evaluating wheat nutrition. It is also important to determine wheat GPC before harvest for agricultural and food process enterprises in order to optimize the wheat grading process. Wheat GPC across a field is spatially variable due to the inherent variability of soil properties and position in the landscape. The objectives of this field study were: (i) to assess the spatial and temporal variability of wheat nitrogen (N) attributes rela...

  14. Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    D. Cromwell

    2006-01-01

    Full Text Available We investigate the spatial and temporal variability of sea surface height (SSH in the North Atlantic basin using satellite altimeter data from October 1992–January 2004. Our primary aim is to provide a detailed description of such variability, including that associated with propagating signals. We also investigate possible correlations between SSH variability and atmospheric pressure changes as represented by climate indices. We first investigate interannual SSH variations by deriving the complex empirical orthogonal functions (CEOFs of altimeter data lowpass-filtered at 18 months. We determine the spatial structure of the leading four modes (both in amplitude and phase and also the associated principal component (PC time series. Using wavelet analysis we derive the time-varying spectral density of the PCs, revealing when particular modes were strongest between 1992–2004. The spatial pattern of the leading CEOF, comprising 30% of the total variability, displays a 5-year periodicity in phase; signal propagation is particularly marked in the Labrador Sea. The second mode, with a dominant 3-year signal, has strong variability in the eastern basin. Secondly, we focus on the Azores subtropical frontal zone. The leading mode (35% is strong in the south and east of this region with strong variations at 3- and 5-year periods. The second mode (21% has a near-zonal band of low variance between  22°–27° N, sandwiched between two regions of high variance. Thirdly, we lowpass filter the altimeter data at a cutoff of 30 days, instead of 18 months, in order to retain signals associated with propagating baroclinic Rossby waves and/or eddies. The leading mode is the annual steric signal, around 46% of the SSH variability. The third and fourth CEOFs,  11% of the remaining variability, are associated with westward propagation which is particularly dominant in a "waveband" between 32°–36° N. For all three cases considered above, no significant cross

  15. Spatial and temporal variability of soil electrical conductivity related to soil moisture

    OpenAIRE

    José Paulo Molin; Gustavo Di Chiacchio Faulin

    2013-01-01

    Soil electrical conductivity (ECa) is a soil quality indicator associated to attributes interesting to site-specific soil management such as soil moisture and texture. Soil ECa provides information that helps guide soil management decisions, so we performed spatial evaluation of soil moisture in two experimental fields in two consecutive years and modeled its influence on soil ECa. Soil ECa, moisture and clay content were evaluated by statistical, geostatistical and regression analyses. Semiv...

  16. Spatial variability of harmful algal blooms in Milford Lake, Kansas, July and August 2015

    Science.gov (United States)

    Foster, Guy M.; Graham, Jennifer L.; Stiles, Tom C.; Boyer, Marvin G.; King, Lindsey R.; Loftin, Keith A.

    2017-01-09

    Cyanobacterial harmful algal blooms (CyanoHABs) tend to be spatially variable vertically in the water column and horizontally across the lake surface because of in-lake and weather-driven processes and can vary by orders of magnitude in concentration across relatively short distances (meters or less). Extreme spatial variability in cyanobacteria and associated compounds poses unique challenges to collecting representative samples for scientific study and public-health protection. The objective of this study was to assess the spatial variability of cyanobacteria and microcystin in Milford Lake, Kansas, using data collected on July 27 and August 31, 2015. Spatially dense near-surface data were collected by the U.S. Geological Survey, nearshore data were collected by the Kansas Department of Health and Environment, and open-water data were collected by U.S. Army Corps of Engineers. CyanoHABs are known to be spatially variable, but that variability is rarely quantified. A better understanding of the spatial variability of cyanobacteria and microcystin will inform sampling and management strategies for Milford Lake and for other lakes with CyanoHAB issues throughout the Nation.The CyanoHABs in Milford Lake during July and August 2015 displayed the extreme spatial variability characteristic of cyanobacterial blooms. The phytoplankton community was almost exclusively cyanobacteria (greater than 90 percent) during July and August. Cyanobacteria (measured directly by cell counts and indirectly by regression-estimated chlorophyll) and microcystin (measured directly by enzyme-linked immunosorbent assay [ELISA] and indirectly by regression estimates) concentrations varied by orders of magnitude throughout the lake. During July and August 2015, cyanobacteria and microcystin concentrations decreased in the downlake (towards the outlet) direction.Nearshore and open-water surface grabs were collected and analyzed for microcystin as part of this study. Samples were collected in the

  17. Spatial-temporal variability in GHG fluxes and their functional interpretation in RusFluxNet

    Science.gov (United States)

    Vasenev, Ivan; Meshalkina, Julia; Sarzhanov, Dmitriy; Mazirov, Ilia; Yaroslavtsev, Alex; Komarova, Tatiana; Tikhonova, Maria

    2016-04-01

    High spatial and temporal variability is mutual feature for most modern boreal landscapes in the European Territory of Russia. This variability is result of their relatively young natural and land-use age with very complicated development stories. RusFluxNet includes a functionally-zonal set of representative natural, agricultural and urban ecosystems from the Central Forest Reserve in the north till the Central Chernozemic Reserve in the south (more than 1000 km distance). Especial attention has been traditionally given to their soil cover and land-use detailed variability, morphogenetic and functional dynamics. Central Forest Biosphere Reserve (360 km to North-West from Moscow) is the principal southern-taiga one in the European territory of Russia with long history of mature spruce ecosystem structure and dynamics investigation. Our studies (in frame of RF Governmental projects #11.G34.31.0079 and #14.120.14.4266) have been concentrated on the soil carbon stocks and GHG fluxes spatial variability and dynamics due to dominated there windthrow and fallow-forest successions. In Moscow RTSAU campus gives a good possibility to develop the ecosystem and soil monitoring of GHG fluxes in the comparable sites of urban forest, field crops and lawn ecosystems taking especial attention on their meso- and micro-relief, soil cover patterns and subsoil, vegetation and land-use technologies, temperature and moisture spatial and temporal variability. In the Central Chernozemic Biosphere Reserve and adjacent areas we do the comparative analysis of GHG fluxes and balances in the virgin and mowed meadow-steppe, forest, pasture, cropland and three types of urban ecosystems with similar subsoil and relief conditions. The carried out researches have shown not only sharp (in 2-5 times) changes in GHG ecosystem and soil fluxes and balances due to seasonal and daily microclimate variation, vegetation and crop development but their essential (in 2-4 times) spatial variability due to

  18. Variability of apparently homogeneous soilscapes in São Paulo state, Brazil: I. spatial analysis

    Directory of Open Access Journals (Sweden)

    M. van Den Berg

    2000-06-01

    Full Text Available The spatial variability of strongly weathered soils under sugarcane and soybean/wheat rotation was quantitatively assessed on 33 fields in two regions in São Paulo State, Brazil: Araras (15 fields with sugarcane and Assis (11 fields with sugarcane and seven fields with soybean/wheat rotation. Statistical methods used were: nested analysis of variance (for 11 fields, semivariance analysis and analysis of variance within and between fields. Spatial levels from 50 m to several km were analyzed. Results are discussed with reference to a previously published study carried out in the surroundings of Passo Fundo (RS. Similar variability patterns were found for clay content, organic C content and cation exchange capacity. The fields studied are quite homogeneous with respect to these relatively stable soil characteristics. Spatial variability of other characteristics (resin extractable P, pH, base- and Al-saturation and also soil colour, varies with region and, or land use management. Soil management for sugarcane seems to have induced modifications to greater depths than for soybean/wheat rotation. Surface layers of soils under soybean/wheat present relatively little variation, apparently as a result of very intensive soil management. The major part of within-field variation occurs at short distances (< 50 m in all study areas. Hence, little extra information would be gained by increasing sampling density from, say, 1/km² to 1/50 m². For many purposes, the soils in the study regions can be mapped with the same observation density, but residual variance will not be the same in all areas. Bulk sampling may help to reveal spatial patterns between 50 and 1.000 m.

  19. Influence of antenatal physical exercise on heart rate variability and QT variability.

    Science.gov (United States)

    Carpenter, R E; Emery, S J; Uzun, O; Rassi, D; Lewis, M J

    2017-01-01

    We sought to characterise the influence of an antenatal exercise programme on ECG-derived cardiac variables. Fifity-one healthy pregnant women were recruited and randomly assigned (2 × 2×2 design) to an exercise group or a control group. Exercising groups attended weekly classes from the 20th week of pregnancy onwards. Cardiovascular assessments (heart rate variabiliy (HRV), QT, and the QT variability index (QTVI)) were performed at 12-16, 26-28, 34-36 weeks and 12 weeks following birth, during supine rest and exercise conditions. Advancing gestation was associated with an increased maternal heart rate (p = 0.001), shorter QT interval (p = 0.003), diminished HRV (p = 0.002) and increased QTVI (p = 0.002). Each of these changes was reversed within 12 weeks postpartum (p Exercise group displayed exaggerated changes for all variables (except QT) but only during supine rest in the third trimester (p exercise programme undertaken between mid and late pregnancy exaggerated these changes during rest in the third trimester of pregnancy.

  20. Spatial Reasoning Influences Students' Performance on Mathematics Tasks

    Science.gov (United States)

    Lowrie, Tom; Logan, Tracy; Ramful, Ajay

    2016-01-01

    Although the psychological literature has demonstrated that spatial reasoning and mathematics performance are correlated, there is scant research on these relationships in the middle years. The current study examined the commonalities and differences in students' performance on instruments that measured three spatial reasoning constructs and two…

  1. Spatial and temporal variability of bronchiectasis cases in Silesian voivodeship in 2006–2010

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    Ewa Niewiadomska

    2016-08-01

    Full Text Available Objectives: Reports on an increasing number of hospitalizations in other European countries and the lack of epidemiological data on the prevalence of bronchiectasis in Poland constituted motivation for the authors to investigate temporal changes of the registered incidence and hospitalization due to bronchiectasis in Silesian voivodeship, and to evaluate spatial variability of the disease in the study region. Material and Methods: The study is a descriptive epidemiological project. Temporal and spatial variability of coefficients describing numbers of newly diagnosed cases and first time hospitalizations due to bronchiectasis (code J47 according to International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10 were evaluated based on the registered data available from the National Health Found (2006–2010 and the data from MZ/Szp-11 reports (2000–2011. The data concerned adults aged ≥ 19 years, inhabitants of Silesian voivodeship. Maps of incidence or hospitalization rates due to bronchiectasis were constructed by the use of a geographical information system ArcGIS. Results: The obtained results show a stable trend of reported new diseases, whereas the number of first time hospitalizations is increasing. Values of the standardized incidence were 19.9–25.1/100 000 inhabitants, and values of the standardized first-time hospitalization were 1.2–2.9/100 000 inhabitants. The reported rates of bronchiectasis indicate significant spatial differences in epidemiological situation in the study region. Conclusions: The findings showed territorial variability of the incidence and hospitalization of bronchiectasis recorded in Silesian voivodeship. The observed variability might result from regional differences in the availability of specialized medical services.

  2. Influence of climate model variability on projected Arctic shipping futures

    Science.gov (United States)

    Stephenson, Scott R.; Smith, Laurence C.

    2015-11-01

    Though climate models exhibit broadly similar agreement on key long-term trends, they have significant temporal and spatial differences due to intermodel variability. Such variability should be considered when using climate models to project the future marine Arctic. Here we present multiple scenarios of 21st-century Arctic marine access as driven by sea ice output from 10 CMIP5 models known to represent well the historical trend and climatology of Arctic sea ice. Optimal vessel transits from North America and Europe to the Bering Strait are estimated for two periods representing early-century (2011-2035) and mid-century (2036-2060) conditions under two forcing scenarios (RCP 4.5/8.5), assuming Polar Class 6 and open-water vessels with medium and no ice-breaking capability, respectively. Results illustrate that projected shipping viability of the Northern Sea Route (NSR) and Northwest Passage (NWP) depends critically on model choice. The eastern Arctic will remain the most reliably accessible marine space for trans-Arctic shipping by mid-century, while outcomes for the NWP are particularly model-dependent. Omitting three models (GFDL-CM3, MIROC-ESM-CHEM, and MPI-ESM-MR), our results would indicate minimal NWP potential even for routes from North America. Furthermore, the relative importance of the NSR will diminish over time as the number of viable central Arctic routes increases gradually toward mid-century. Compared to vessel class, climate forcing plays a minor role. These findings reveal the importance of model choice in devising projections for strategic planning by governments, environmental agencies, and the global maritime industry.

  3. The Influence of Ephemeral Beaches on Alongshore Variability of Hard-rock Cliff Erosion

    Science.gov (United States)

    Vann Jones, E. C.; Rosser, N. J.; Brain, M.; Varley, S. J.

    2015-12-01

    The role of abrasion of rock cliffs is typically considered in the long-term presence of a beach. During monthly monitoring of hard rock cliff erosion along the North Yorkshire coast, UK, we have observed a number of small ephemeral beaches of highly variable duration and extent. The erosive significance of the temporary presence of sediment at the cliffs is unknown and we set out to examine whether observed alongshore variability in erosion can be linked to the presence of ephemeral beaches. We explore the temporal and spatial variability in sediment deposition and transport along a low-sediment rock coast foreshore, the controlling marine conditions and the effects on cliff erosion. We focus on a 500 m wide embayment set into 70 m high hard rock cliffs consisting of horizontally bedded Jurassic mudstone, shale, siltstone and sandstone. The bay has a wide, shallow gradient foreshore up to 300 m wide with highly variable topography. With the exception of an ephemeral beach (of widths up to approximately 150 m alongshore and 10 m cross-shore) the rock foreshore is typically sand-free, with failed material from the cliffs quickly removed from the cliff toe by the sea leaving only boulders. The high tidal range (6 m) and storm wave environment of the North Sea result in variable marine conditions at the site. We use magnetic sand tracers and a grid of foreshore and cliff face magnets to examine the sand transport across the foreshore and to identify the vertical extent of cliff face impacted by sand. We monitor the driving marine conditions on the foreshore using a network of current meters and wave pressure sensors. Erosion of the cliff face across the whole bay is monitored at high-resolution using terrestrial laser scanning to examine the spatial distribution of abrasion and the influence of the ephemeral beach.

  4. Global SST influence on twentieth century NAO variability

    Energy Technology Data Exchange (ETDEWEB)

    Paeth, H.; Hense, A. [Meteorologisches Institut, Universitaet Bonn, 53121 Bonn (Germany); Latif, M. [Max-Planck-Institut fuer Meteorologie, 20146 Hamburg (Germany)

    2003-07-01

    Recent studies have suggested that sea surface temperature (SST) is an important source of variability of the North Atlantic Oscillation (NAO). Here, we deal with four basic aspects contributing to this issue: (1) we investigate the characteristic time scales of this oceanic influence; (2) quantify the scale-dependent hindcast potential of the NAO during the twentieth century as derived from SST-driven atmospheric general circulation model (AGCM) ensembles; (3) the relevant oceanic regions are identified, corresponding SST indices are defined and their relationship to the NAO are evaluated by means of cross spectral analysis and (4) our results are compared with long-term coupled control experiments with different ocean models in order to ensure whether the spectral relationship between the SST regions and the NAO is an intrinsic mode of the coupled climate system, involving the deep ocean circulation, rather than an artefact of the unilateral SST forcing. The observed year-to-year NAO fluctuations are barely influenced by the SST. On the decadal time scales the major swings of the observed NAO are well reproduced by various ensembles from the middle of the twentieth century onward, including the negative state in the 1960s and part of the positive trend afterwards. A six-member ECHAM4-T42 ensemble reveals that the SST boundary condition affects 25% of total decadal-mean and interdecadal-trend NAO variability throughout the twentieth century. The most coherent NAO-related SST feature is the well-known North Atlantic tripole. Additional contributions may arise from the southern Pacific and the low-latitude Indian Ocean. The coupled climate model control runs suggest only the North Atlantic SST-NAO relationship as being a true characteristic of the coupled climate system. The coherence and phase spectra of observations and coupled simulations are in excellent agreement, confirming the robustness of this decadal-scale North Atlantic air-sea coupled mode. (orig.)

  5. Developments of rtop - interpolation and simulation of data with a variable spatial support

    Science.gov (United States)

    Olav Skøien, Jon; Blöschl, Günter; Laaha, Gregor; Parajka, Juraj; Pebesma, Edzer; Viglione, Alberto

    2015-04-01

    The rtop package (Skøien et al., 2014) is an R-package (R Core Team, 2014) which makes it possible to spatially interpolate data which has a variable spatial support, such as runoff data or population health data. The new version of the package includes some new features which have previously not been available for such data in an open source and easy to use program. These include: - Simulations; it is now possible to simulate values at prediction locations, similar to what has for a long time been possible for point observations through e.g. gstat (Pebesma, 2004) - Interpolation of time series; the previous version of the package could make a separate interpolation for each time step, the new version derives a temporally averaged variogram which is then used for interpolation of time series. Additionally, the computational speed has been increased by taking advantage of the possibilities for parallelization in R. Pebesma, E. J. (2004). Multivariable geostatistics in S: the gstat package. Computers & Geosciences, 30, 683-691. R Core Team. (2014). R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing. Retrieved from http://www.r-project.org Skøien, J. O., Blöschl, G., Laaha, G., Pebesma, E., Parajka, J., & Viglione, A. (2014). rtop: An R package for interpolation of data with a variable spatial support, with an example from river networks. Computers & Geosciences, 67, 180-190. doi:10.1016/j.cageo.2014.02.009

  6. [Soil nutrients spatial variability and soil fertility suitability in Qujing tobacco-planting area].

    Science.gov (United States)

    Li, Qiang; Zhou, Ji-heng; Yang, Rong-sheng; Zhang, Zheng-yan; Xie, Yan; Zhang, Yi-yang; Huang, Kua-ke; Li, Wei

    2011-04-01

    By adopting GPS technique, 2088 sampling sites were installed in the tobacco-planting area of Qujing City, Yunnan Province, with 0-20 cm soil samples collected to determine their main nutrients contents. The overall characteristics and spatial variability of the tobacco soil nutrients were analyzed by classic statistics and geo-statistics, and the soil fertility suitability in planting tobacco was evaluated by the methods of fuzzy mathematics. In the study area, soil pH and soil organic matter, available S, and water-soluble Cl contents were appropriate, soil total N and alkalihydrolyzable N contents were too high, soil available K, Ca, Mg, Cu, Fe, Zn, Mo, and Mn contents were abundant, soil available P content was at medium level, while soil total P and K and available B contents were insufficient. All the nutrient indices presented anisotropic distribution, among which, the spatial variability of soil available P and B was mainly caused by random factors, and that of other nutrients was caused by the co-effects of structural and random factors. The spatial distribution map of soil fertility suitability index (SFI) showed that there was no the excellent grade region for tobacco-planting, good grade region accounted for 8.0%, general grade region accounted for 51.6%, moderate grade region accounted for 39.0%, and low grade region accounted for 1.4%.

  7. Spatial and Temporal Variability of Satellite-Derived Cloud and Surface Characteristics During FIRE-ACE

    Science.gov (United States)

    Maslanik, J. A.; Key, J.; Fowler, C. W.; Nguyen, T.; Wang, X.a

    2000-01-01

    Advanced very high resolution radiometer (AVHRR) products calculated for the western Arctic for April-July 1998 are used to investigate spatial, temporal, and regional patterns and variability in energy budget parameters associated with ocean- ice-atmosphere interactions over the Arctic Ocean during the Surface Heat Budget of the Arctic Ocean (SHEBA) project and the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment - Arctic Cloud Experiment (FIRE-ACE). The AVHRR-derived parameters include cloud fraction, clear-sky and all-sky skin temperature and broadband albedo, upwelling and downwelling shortwave and longwave radiation, cloud top pressure and temperature, and cloud optical depth. The remotely sensed products generally agree well with field observations at the SHEBA site, which in turn is shown to be representative of a surrounding region comparable in size to a climate-model grid cell. Time series of products for other locations in the western Arctic illustrate the magnitude of spatial variability during the study period and provide spatial and temporal detail useful for studying regional processes. The data illustrate the progression of reduction in cloud cover, albedo decrease, and the considerable heating of the open ocean associated with the anomalous decrease in sea ice cover in the eastern Beaufort Sea that began in late spring. Above-freezing temperatures are also recorded within the ice pack, suggesting warming of the open water areas within the ice cover.

  8. A model for the spatial distribution of snow water equivalent parameterized from the spatial variability of precipitation

    Science.gov (United States)

    Skaugen, Thomas; Weltzien, Ingunn H.

    2016-09-01

    Snow is an important and complicated element in hydrological modelling. The traditional catchment hydrological model with its many free calibration parameters, also in snow sub-models, is not a well-suited tool for predicting conditions for which it has not been calibrated. Such conditions include prediction in ungauged basins and assessing hydrological effects of climate change. In this study, a new model for the spatial distribution of snow water equivalent (SWE), parameterized solely from observed spatial variability of precipitation, is compared with the current snow distribution model used in the operational flood forecasting models in Norway. The former model uses a dynamic gamma distribution and is called Snow Distribution_Gamma, (SD_G), whereas the latter model has a fixed, calibrated coefficient of variation, which parameterizes a log-normal model for snow distribution and is called Snow Distribution_Log-Normal (SD_LN). The two models are implemented in the parameter parsimonious rainfall-runoff model Distance Distribution Dynamics (DDD), and their capability for predicting runoff, SWE and snow-covered area (SCA) is tested and compared for 71 Norwegian catchments. The calibration period is 1985-2000 and validation period is 2000-2014. Results show that SDG better simulates SCA when compared with MODIS satellite-derived snow cover. In addition, SWE is simulated more realistically in that seasonal snow is melted out and the building up of "snow towers" and giving spurious positive trends in SWE, typical for SD_LN, is prevented. The precision of runoff simulations using SDG is slightly inferior, with a reduction in Nash-Sutcliffe and Kling-Gupta efficiency criterion of 0.01, but it is shown that the high precision in runoff prediction using SD_LN is accompanied with erroneous simulations of SWE.

  9. The formation of Cataclysmic Variables: the influence of nova eruptions

    CERN Document Server

    Nelemans, G; Repetto, S; Toonen, S; Phinney, E S

    2015-01-01

    The theoretical and observed populations of pre-cataclysmic variables (pre-CVs) are dominated by systems with low-mass white dwarfs (WDs), while the WD masses in CVs are typically high. In addition, the space density of CVs is found to be significantly lower than theoretical models. We investigate the influence of nova outbursts on the formation and (initial) evolution of CVs. In particular, we calculate the stability of the mass transfer in case all the material accreted on the WD is lost in classical novae, and part of the energy to eject the material comes from a common-envelope like interaction with the companion. In addition, we study the effect of an asymmetry in the mass ejection, that may lead to small eccentricities in the orbit. We find that a common-envelope like ejection significantly decreases the stability of the mass transfer, in particular for low-mass WD. Similarly, the influence of asymmetric mass loss can be important for short-period systems and even more so for low-mass WD, but likely dis...

  10. Spatial Variability Mapping of Crop Residue Using Hyperion (EO-1 Hyperspectral Data

    Directory of Open Access Journals (Sweden)

    Abderrazak Bannari

    2015-06-01

    Full Text Available Soil management practices that maintain crop residue cover and reduce tillage improve soil structure, increase organic matter content in the soil, positively influence water infiltration, evaporation and soil temperature, and play an important role in fixing CO2 in the soil. Consequently, good residue management practices on agricultural land have many positive impacts on soil quality, crop production quality and decrease the rate of soil erosion. Several studies have been undertaken to develop and test methods to derive information on crop residue cover and soil tillage using empirical and semi-empirical methods in combination with remote sensing data. However, these methods are generally not sufficiently rigorous and accurate for characterizing the spatial variability of crop residue cover in agricultural fields. The goal of this research is to investigate the potential of hyperspectral Hyperion (Earth Observing-1, EO-1 data and constrained linear spectral mixture analysis (CLSMA for percent crop residue cover estimation and mapping. Hyperion data were acquired together with ground-reference measurements for validation purposes at the beginning of the agricultural season (prior to spring crop planting in Saskatchewan (Canada. At this time, only bare soil and crop residue were present with no crop cover development. In order to extract the crop residue fraction, the images were preprocessed, and then unmixed considering the entire spectral range (427 nm–2355 nm and the pure spectra (endmember. The results showed that the correlation between ground-reference measurements and extracted fractions from the Hyperion data using CLMSA showed that the model was overall a very good predictor for crop residue percent cover (index of agreement (D of 0.94, coefficient of determination (R2 of 0.73 and root mean square error (RMSE of 8.7% and soil percent cover (D of 0.91, R2 of 0.68 and RMSE of 10.3%. This performance of Hyperion is mainly due to the

  11. Spatial variability in floodplain sedimentation: the use of generalized linear mixed-effects models

    Directory of Open Access Journals (Sweden)

    A. Cabezas

    2010-02-01

    Full Text Available Sediment, Total Organic Carbon (TOC and total nitrogen (TN accumulation during one overbank flood (1.15 y were examined at one reach of the Middle Ebro River (NE Spain for elucidating spatial patterns. To achieve this goal, four areas with different geomorphological features and located within the study reach were examined by using artificial grass mats. Within each area, 1 m2 study plots consisting on three pseudo-replicates were placed in a semi-regular grid oriented perpendicular to the main channel. TOC, TN and Particle-Size composition of deposited sediments were examined and accumulation rates estimated. Generalized linear mixed-effects models were used to analyze sedimentation patterns in order to handle clustered sampling units, specific-site effects and spatial self-correlation between observations. Our results confirm the importance of channel-floodplain morphology and site micro-topography in explaining sediment, TOC and TN deposition patterns, although the importance of another factors as vegetation morphology should be included in further studies to explain small scale variability. Generalized linear mixed-effect models provide a good framework to deal with the high spatial heterogeneity of this phenomenon at different spatial scales, and should be further investigated in order to explore its validity when examining the importance of factors such as flood magnitude or suspended sediment solid concentration.

  12. Spatial variability in floodplain sedimentation: the use of generalized linear mixed-effects models

    Science.gov (United States)

    Cabezas, A.; Angulo-Martínez, M.; Gonzalez-Sanchís, M.; Jimenez, J. J.; Comín, F. A.

    2010-08-01

    Sediment, Total Organic Carbon (TOC) and total nitrogen (TN) accumulation during one overbank flood (1.15 y return interval) were examined at one reach of the Middle Ebro River (NE Spain) for elucidating spatial patterns. To achieve this goal, four areas with different geomorphological features and located within the study reach were examined by using artificial grass mats. Within each area, 1 m2 study plots consisting of three pseudo-replicates were placed in a semi-regular grid oriented perpendicular to the main channel. TOC, TN and Particle-Size composition of deposited sediments were examined and accumulation rates estimated. Generalized linear mixed-effects models were used to analyze sedimentation patterns in order to handle clustered sampling units, specific-site effects and spatial self-correlation between observations. Our results confirm the importance of channel-floodplain morphology and site micro-topography in explaining sediment, TOC and TN deposition patterns, although the importance of other factors as vegetation pattern should be included in further studies to explain small-scale variability. Generalized linear mixed-effect models provide a good framework to deal with the high spatial heterogeneity of this phenomenon at different spatial scales, and should be further investigated in order to explore its validity when examining the importance of factors such as flood magnitude or suspended sediment concentration.

  13. Spatial Variability of Soil Organic Carbon in a Watershed on the Loess Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Yun-Qiang; ZHANG Xing-Chang; ZHANG Jing-Li; LI Shun-Ji

    2009-01-01

    Soil organic carbon (SOC) has great impacts on global warming,land degradation and food security.Classic statistical and geostatistical methods were used to characterize and compare the spatial heterogeneity of SOC and related factors,such as topography,soil type and land use,in the Liudaogou watershed on the Loess Plateau of North China.SOC concentrations followed a log-normal distribution with an arithmetic and geometric means of 23.4 and 21.3 g kg-1,respectively,were moderately variable (CV=75.9%),and demonstrated a moderate spatial dependence according to the nugget ratio (34.7%).The experimental variogram of SOC was best-fitted by a spherical model,after the spatial outliers had been detected and subsequently eliminated.Lower SOC concentrations were associated with higher elevations.Warp soils and farmland had the highest SOC concentrations,while aeolian sand soil and shrublands had the lowest SOC values.The geostatistical characteristics of SOC for the different soil and land use types were different.These patterns were closely related to the spatial structure of topography,and soil and land use types.

  14. Temporal Trends and Spatial Variability of Vegetation Phenology over the Northern Hemisphere during 1982-2012.

    Science.gov (United States)

    Wang, Siyuan; Yang, Bojuan; Yang, Qichun; Lu, Linlin; Wang, Xiaoyue; Peng, Yaoyao

    2016-01-01

    Satellite-derived vegetation phenology has been recognized as a key indicator for detecting changes in the terrestrial biosphere in response to global climate change. However, multi-decadal changes and spatial variation of vegetation phenology over the Northern Hemisphere and their relationship to climate change have not yet been fully investigated. In this article, we investigated the spatial variability and temporal trends of vegetation phenology over the Northern Hemisphere by calibrating and analyzing time series of the satellite-derived normalized difference vegetation index (NDVI) during 1982-2012, and then further examine how vegetation phenology responds to climate change within different ecological zones. We found that during the period from 1982 to 2012 most of the high latitude areas experienced an increase in growing period largely due to an earlier beginning of vegetation growing season (BGS), but there was no significant trend in the vegetation growing peaks. The spatial pattern of phenology within different eco-zones also experienced a large variation over the past three decades. Comparing the periods of 1982-1992, 1992-2002 with 2002-2012, the spatial pattern of change rate of phenology shift (RPS) shows a more significant trend in advancing of BGS, delaying of EGS (end of growing season) and prolonging of LGS (length of growing season) during 2002-2012, overall shows a trend of accelerating change. Temperature is a major determinant of phenological shifts, and the response of vegetation phenology to temperature varied across different eco-zones.

  15. Spatial variability of selected physicochemical parameters within peat deposits in small valley mire: a geostatistical approach

    Directory of Open Access Journals (Sweden)

    Pawłowski Dominik

    2014-12-01

    Full Text Available Geostatistical methods for 2D and 3D modelling spatial variability of selected physicochemical properties of biogenic sediments were applied to a small valley mire in order to identify the processes that lead to the formation of various types of peat. A sequential Gaussian simulation was performed to reproduce the statistical distribution of the input data (pH and organic matter and their semivariances, as well as to honouring of data values, yielding more ‘realistic’ models that show microscale spatial variability, despite the fact that the input sample cores were sparsely distributed in the X-Y space of the study area. The stratigraphy of peat deposits in the Ldzań mire shows a record of long-term evolution of water conditions, which is associated with the variability in water supply over time. Ldzań is a fen (a rheotrophic mire with a through-flow of groundwater. Additionally, the vicinity of the Grabia River is marked by seasonal inundations of the southwest part of the mire and increased participation of mineral matter in the peat. In turn, the upper peat layers of some of the central part of Ldzań mire are rather spongy, and these peat-forming phytocoenoses probably formed during permanent waterlogging.

  16. Spatial and Temporal Variability of Soil Redistribution in a Heterogeneous Shrub Dominated Landscape

    Science.gov (United States)

    Van Pelt, R. S.; Zobeck, T. M.

    2015-12-01

    Redistribution of soil by wind results when the erosive force of the wind impacts bare, susceptible soil surfaces. In semi-arid and arid environments, many grasslands with protected surfaces are being replaced by heterogeneous shrub communities with bare, susceptible soil surfaces between the individual shrubs. The development of nutrient islands and the increases of fugitive dust in these areas is indicative of increases of soil redistribution, but few quantitative measurements have been made to date. We fenced three 1 ha areas in an approximately 100 ha coppice dune area of southeast New Mexico dominated by shinnery oak, sand sage, and mesquite and installed a 4 X 4 grid of MWAC sampler masts spaced at 20 m from each other. Weather data were collected at an automated weather station in each of the fenced areas. We found the patterns of soil redistribution to be highly variable in space and time. Differences in vegetation patterns and wind fields were noted among the plots for the same discrete time period that could explain some of the spatial variability. We also noted seasonality of wind fields that accounted for the temporally variable spatial patterns of soil redistribution. We conclude that accurate measurement of soil redistribution patterns in a heterogeneous shrub community requires a very large number of samplers and a long period of study and we believe that net soil loss from an area is limited to fine dust emissions.

  17. Spatial variability of soil properties and soil erodibility in the Alqueva dam watershed, Portugal

    Science.gov (United States)

    Ferreira, V.; Panagopoulos, T.; Andrade, R.; Guerrero, C.; Loures, L.

    2015-01-01

    The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor) were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this, three areas representative of different land uses (agroforestry grassland, Lucerne crop and olive orchard) were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation), vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while K factor increased with intensive cultivation. The HJ-biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion.

  18. Spatial variability of soil properties and soil erodibility in the Alqueva reservoir watershed

    Science.gov (United States)

    Ferreira, V.; Panagopoulos, T.; Andrade, R.; Guerrero, C.; Loures, L.

    2015-04-01

    The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor) were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this end, three areas representative of different land uses (agroforestry grassland, lucerne crop and olive orchard) were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation), vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while the K factor increased with intensive cultivation. The HJ-Biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. The K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion.

  19. Spatial variability of soil properties and soil erodibility in the Alqueva dam watershed, Portugal

    Directory of Open Access Journals (Sweden)

    V. Ferreira

    2015-01-01

    Full Text Available The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this, three areas representative of different land uses (agroforestry grassland, Lucerne crop and olive orchard were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation, vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while K factor increased with intensive cultivation. The HJ-biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion.

  20. Spatial-Temporal Yield Trend of Oil Palm as Influenced by Nitrogen Fertilizer Management

    Directory of Open Access Journals (Sweden)

    Abdul R. Anuar

    2008-01-01

    Full Text Available One of the major challenges in oil palm (Elaeis guineensis Jacq. plantations today is proper interpretation of yield maps for site-specific management and identification and understanding of the causal factors influencing the variability of oil palm yields. A study was conducted to examine the structural yield variation in order to assess the spatial and temporal yield trends so as to interpret multi-year yield maps of oil palm as influenced by the long-term N fertilizer applications in the palm circle in fertilizer response trial in Sabah, Malaysia. Two clusters of palms were selected for the study; with and without N fertilizer applications for the past 10 years. Fresh fruit bunch (ffb yields were recorded and summarized on an annual basis. Geostatistical analysis was used to characterize the spatial structure of the semivariogram while point kriging was used to interpolate the ffb yields at unsampled locations. A classified management zone map was developed based on the spatial and temporal stability yield maps from 1992-1999. Semivariance analysis revealed that the yield variations between plots and within plots could be distinguished from the structural semivariogram. The variability between plots was relatively higher compared with within plots. The maximum range of the semivariance of both fertilizer treatments was about 6-palm distance which corresponded well to the experimental plot size of 30 (5×6 palms. It was also observed that the structure of the semivariogram was governed by the sampling pattern and the experimental plot size. The annual yield maps suggested that the application of N could sustain ffb yields above 30 t ha-1 year-1 whereas its removal could result in a drastic decline in ffb yields after 1992. Long-term N fertilizer applications reduced the annual ffb yield fluctuations to between 35 and 45% based on the coefficient of variations between years obtained from individual palms. The results further demonstrate the

  1. Interannual and spatial variability of maple syrup yield as related to climatic factors

    Directory of Open Access Journals (Sweden)

    Louis Duchesne

    2014-06-01

    Full Text Available Sugar maple syrup production is an important economic activity for eastern Canada and the northeastern United States. Since annual variations in syrup yield have been related to climate, there are concerns about the impacts of climatic change on the industry in the upcoming decades. Although the temporal variability of syrup yield has been studied for specific sites on different time scales or for large regions, a model capable of accounting for both temporal and regional differences in yield is still lacking. In the present study, we studied the factors responsible for interregional and interannual variability in maple syrup yield over the 2001–2012 period, by combining the data from 8 Quebec regions (Canada and 10 U.S. states. The resulting model explained 44.5% of the variability in yield. It includes the effect of climatic conditions that precede the sapflow season (variables from the previous growing season and winter, the effect of climatic conditions during the current sapflow season, and terms accounting for intercountry and temporal variability. Optimal conditions for maple syrup production appear to be spatially restricted by less favourable climate conditions occurring during the growing season in the north, and in the south, by the warmer winter and earlier spring conditions. This suggests that climate change may favor maple syrup production northwards, while southern regions are more likely to be negatively affected by adverse spring conditions.

  2. Spatial variability of recent sedimentation in Lake Ohrid (Albania/Macedonia

    Directory of Open Access Journals (Sweden)

    H. Vogel

    2010-10-01

    Full Text Available Lake Ohrid is likely of Pliocene age and thus commonly referred to as the oldest existing lake in Europe. In this study spatial variability of recent sediment composition is assessed using >50 basin wide distributed surface sediment samples. Analysis of biogeochemical bulk parameters, selected metals, pigment concentrations as well as grain size distributions revealed a significant spatial heterogeneity in surface sediment composition. It implies that sedimentation in Lake Ohrid is controlled by an interaction of multiple natural and anthropogenic factors and processes. Major factors controlling surface sediment composition are related to differences in geological catchment characteristics, anthropogenic land use, and a counterclockwise rotating surface water current. In some instances processes controlling sediment composition also seem to impact distribution patterns of biodiversity, which suggests a common interaction of processes responsible for both patterns.

  3. Industrial implementation of spatial variability control by real-time SPC

    Science.gov (United States)

    Roule, O.; Pasqualini, F.; Borde, M.

    2016-10-01

    Advanced technology nodes require more and more information to get the wafer process well setup. The critical dimension of components decreases following Moore's law. At the same time, the intra-wafer dispersion linked to the spatial non-uniformity of tool's processes is not capable to decrease in the same proportions. APC systems (Advanced Process Control) are being developed in waferfab to automatically adjust and tune wafer processing, based on a lot of process context information. It can generate and monitor complex intrawafer process profile corrections between different process steps. It leads us to put under control the spatial variability, in real time by our SPC system (Statistical Process Control). This paper will outline the architecture of an integrated process control system for shape monitoring in 3D, implemented in waferfab.

  4. Climatic spatial variability in Extremadura (Spain) based on viticultural bioclimatic indices

    Science.gov (United States)

    Moral, F. J.; Rebollo, F. J.; Paniagua, L. L.; García, A.

    2014-12-01

    The evaluation of general suitability for viticulture in wine regions requires a knowledge of the spatial variation in temperature, which is also used to assess different grapevine cultivars and to delimit appropriate zones for winegrape production. However, usually temperature data and methods applied to properly delineate homogeneous areas are not adequate to generate accurate maps. With the aim of providing an analysis using four temperature-based indices, quantifying their spatial variability, and representing the spatial pattern of each index throughout Extremadura, one of the most important Spanish wine regions, temperature data from 117 meteorological stations, considering the 1980-2011 period, were utilized. The statistical properties of each index were assessed and, later, they were mapped by means of an integrated geographic information system (GIS) and a multivariate geostatistics (regression-kriging) approach. Results show that heat-sum temperature indices were highly related to the more simple growing season temperature; however, temperature regime differences varied upon which index was employed. The spatial variability of climate within Extremaduran natural regions (NR) is significant; although the warmer conditions predominate, some NR have part of their territory by up to eight climate classes. This information enables a better understanding of the viticulture suitability within each NR and delineating homogeneous zones. The use of consistent bioclimatic indices and an advanced geostatistical algorithm have made it possible to delimit and compare within-region climates and also enabled comparisons of Extremaduran NR with others worlwide, which should be taken into account to select varieties and assess the possibilities of producing new wines.

  5. Spatial variability of soil carbon stock in the Urucu river basin, Central Amazon-Brazil.

    Science.gov (United States)

    Ceddia, Marcos Bacis; Villela, André Luis Oliveira; Pinheiro, Érika Flávia Machado; Wendroth, Ole

    2015-09-01

    The Amazon Forest plays a major role in C sequestration and release. However, few regional estimates of soil organic carbon (SOC) stock in this ecoregion exist. One of the barriers to improve SOC estimates is the lack of recent soil data at high spatial resolution, which hampers the application of new methods for mapping SOC stock. The aims of this work were: (i) to quantify SOC stock under undisturbed vegetation for the 0-30 and the 0-100 cm under Amazon Forest; (ii) to correlate the SOC stock with soil mapping units and relief attributes and (iii) to evaluate three geostatistical techniques to generate maps of SOC stock (ordinary, isotopic and heterotopic cokriging). The study site is located in the Central region of Amazon State, Brazil. The soil survey covered the study site that has an area of 80 km(2) and resulted in a 1:10,000 soil map. It consisted of 315 field observations (96 complete soil profiles and 219 boreholes). SOC stock was calculated by summing C stocks by horizon, determined as a product of BD, SOC and the horizon thickness. For each one of the 315 soil observations, relief attributes were derived from a topographic map to understand SOC dynamics. The SOC stocks across 30 and 100 cm soil depth were 3.28 and 7.32 kg C m(-2), respectively, which is, 34 and 16%, lower than other studies. The SOC stock is higher in soils developed in relief forms exhibiting well-drained soils, which are covered by Upland Dense Tropical Rainforest. Only SOC stock in the upper 100 cm exhibited spatial dependence allowing the generation of spatial variability maps based on spatial (co)-regionalization. The CTI was inversely correlated with SOC stock and was the only auxiliary variable feasible to be used in cokriging interpolation. The heterotopic cokriging presented the best performance for mapping SOC stock.

  6. Variability of fMRI-response patterns at different spatial observation scales.

    Science.gov (United States)

    Ball, Tonio; Breckel, Thomas P K; Mutschler, Isabella; Aertsen, Ad; Schulze-Bonhage, Andreas; Hennig, Jürgen; Speck, Oliver

    2012-05-01

    Functional organization units of the cerebral cortex exist over a wide range of spatial scales, from local circuits to entire cortical areas. In the last decades, scale-space representations of neuroimaging data suited to probe the multi-scale nature of cortical functional organization have been introduced and methodologically elaborated. For this purpose, responses are statistically detected over a range of spatial scales using a family of Gaussian filters, with small filters being related to fine and large filters-to coarse spatial scales. The goal of the present study was to investigate the degree of variability of fMRI-response patterns over a broad range of observation scales. To this aim, the same fMRI data set obtained from 18 subjects during a visuomotor task was analyzed with a range of filters from 4- to 16-mm full width at half-maximum (FWHM). We found substantial observation-scale-related variability. For example, using filter widths of 6- to 8-mm FWHM, in the group-level results, significant responses in the right secondary visual but not in the primary visual cortex were detected. However, when larger filters were used, the responses in the right primary visual cortex reached significance. Often, responses in probabilistically defined areas were significant when both small and large filters, but not intermediate filter widths were applied. This suggests that brain responses can be organized in local clusters of multiple distinct activation foci. Our findings illustrate the potential of multi-scale fMRI analysis to reveal novel features in the spatial organization of human brain responses.

  7. [Study on three-dimension spatial variability of regional soil salinity based on spectral indices].

    Science.gov (United States)

    Liu, Guang-Ming; Wu, Ya-Kun; Yang, Jin-Song; Yu, Shi-Peng

    2013-10-01

    In order to illustrate the three-dimension spatial variability of soil salinity in central China flood area of the Yellow river, integrated soil sampling data and remote sensing data, spectral indices and inverse distance weighting (IDW) method were applied to the estimation and simulation of three-dimension spatial distribution of soil salinity. The study was carried out in typical central China flood area of the Yellow river in Fengqiu County, Henan Province, China. The electrical conductivity of the saturation extract (EC1: 5) of 505 soil samples collected at 101 points was measured. The results indicated that the coefficient of variation of soil salinity at each soil layer is from 0.218 to 0.324 and exhibited the moderate spatial variability. The average of soil electrical conductivity is from 0.121 to 0.154 ds x m(-1). The 2 820 three-dimension spatial scattered data for soil electrical conductivity were taken at soil salinity mapping interpreted by spectral indices and soil electrical conductivity. Three-dimension IDW interpolation showed that a large area of high soil salinity mainly located in the region of Tianran canal and the along of the Yellow river. The shape of the soil salinity profile was downward flowed, revealing soil salinity increasing with depth in whole soil profile and soil salinity accumulated in the subsoil. The accuracy of the predictions was tested using 20 soil sampled points. The root mean square error (RMSE) of calibration for three-dimension distribution of soil salinity showed that the IDW method based on spectral indices was ideal. The research results can provide theoretical foundations to the management and utilization of salt-affected land in China flood area, especially in the Yellow river zone.

  8. Short-term spatial and temporal variability of disinfection by-product occurrence in small drinking water systems.

    Science.gov (United States)

    Guilherme, Stéphanie; Rodriguez, Manuel J

    2015-06-15

    Disinfection by-products (DBPs) constitute a large family of compounds. Trihalomethanes and haloacetic acids are regulated in various countries, but most DBPs are not. Monitoring DBPs can be delicate, especially for small systems, because various factors influence their formation and speciation. Short-term variations of DBPs can be important and particularly difficult for small systems to handle because they require robust treatment and operation processes. According to our knowledge, for the first time, our study covers the short-term variability of regulated and non-regulated DBP occurrence in small systems in the summer. An intensive sampling program was carried out in six small systems in Canada. Systems in the provinces of Newfoundland and Labrador and Quebec were sampled daily at the water treatment plant and at six different locations along the distribution system. Five DBP families were studied: trihalomethanes, haloacetic acids, haloacetonitriles, halonitromethanes and haloketones. Results show that there were considerable variations in DBP levels from week to week during the month of study and even from day to day within the week. On a daily basis, DBP levels can fluctuate by 22% to 96%. Likewise, the large number of sampling locations served to observe DBP variations along the distribution system. Observations revealed some degradation and decomposition of non-regulated DBPs never before studied in small systems that are associated with the difficulty these systems experience in maintaining adequate levels of residual disinfectant. Finally, this study reveals that the short term temporal variability of DBPs is also influenced by spatial location along the distribution system. In the short term, DBP levels can fluctuate by 23% at the beginning of the system, compared to 40% at the end. Thus, spatial and temporal variations of DBPs in the short term may make it difficult to select representative locations and periods for DBP monitoring purposes in small

  9. Spatial and temporal variability in sediment deposition and seabed character on the Waipaoa River margin, New Zealand

    Science.gov (United States)

    Walsh, J. P.; Corbett, D. R.; Kiker, J. M.; Orpin, A. R.; Hale, R. P.; Ogston, A. S.

    2014-09-01

    The stratigraphic record is the manifestation of a wide range of processes, interactions and responses to environmental drivers. Understanding the functioning of river sediment dispersal systems is necessary to determine the fate of sediment and associated material in the marine environment and differentiate key influences in the development of the stratigraphic record. To that end, this study uses sediment cores collected on four successive cruises (January, May and September 2010 and February 2011) on the Waipaoa River margin, New Zealand, to provide insight into spatial and temporal variability in sediment deposition and seabed character. The Waipaoa River discharges a large sediment load into an energetic coast that has a complex margin morphology. Several flood and wave events occurred during the study, and sedimentation varied spatially and temporally. X-radiographs and short-lived radioisotopes indicate emplacement of new event layers prior to all cruises. Notable variation in surficial seabed character (grain-size composition, loss-on-ignition percentage) was apparent on the inner shelf (water depths Poverty Bay, into which the Waipaoa River discharges directly, and subsequent export and dispersal patterns are linked to the relative timing and size of flood and wave events. Surficial deposits with characteristics of fluid muds and wave-enhanced sediment gravity flows were noted at some (<25 sites total) mid-shelf and shallower sites from all cruises. During the last cruise considerable inter- and intra-site seabed variability occurred in the interbedded river-proximal inner-shelf deposits over spatial scales of less than a few kilometers. Evidence from earlier sidescan data infer that this could be related to variation in bedform development or influence. Contrasts in the observed event layering recorded over the experiment with the longer pattern of accumulation suggests stochastic dispersal behavior and reworking over time must shape the seabed to produce

  10. Groundwater Quality: Analysis of Its Temporal and Spatial Variability in a Karst Aquifer.

    Science.gov (United States)

    Pacheco Castro, Roger; Pacheco Ávila, Julia; Ye, Ming; Cabrera Sansores, Armando

    2017-06-15

    This study develops an approach based on hierarchical cluster analysis for investigating the spatial and temporal variation of water quality governing processes. The water quality data used in this study were collected in the karst aquifer of Yucatan, Mexico, the only source of drinking water for a population of nearly two million people. Hierarchical cluster analysis was applied to the quality data of all the sampling periods lumped together. This was motivated by the observation that, if water quality does not vary significantly in time, two samples from the same sampling site will belong to the same cluster. The resulting distribution maps of clusters and box-plots of the major chemical components reveal the spatial and temporal variability of groundwater quality. Principal component analysis was used to verify the results of cluster analysis and to derive the variables that explained most of the variation of the groundwater quality data. Results of this work increase the knowledge about how precipitation and human contamination impact groundwater quality in Yucatan. Spatial variability of groundwater quality in the study area is caused by: a) seawater intrusion and groundwater rich in sulfates at the west and in the coast, b) water rock interactions and the average annual precipitation at the middle and east zones respectively, and c) human contamination present in two localized zones. Changes in the amount and distribution of precipitation cause temporal variation by diluting groundwater in the aquifer. This approach allows to analyze the variation of groundwater quality controlling processes efficiently and simultaneously. © 2017, National Ground Water Association.

  11. Soil internal drainage: temporal stability and spatial variability in succession bean-black oat

    Science.gov (United States)

    Salvador, M. M. S.; Libardi, P. L.; Moreira, N. B.; Sousa, H. H. F.; Neiverth, C. A.

    2012-04-01

    There are a variety of studies considering the soil water content, but those who consider the flow of water, which are translated by deep drainage and capillary rise are scarce, especially those who assess their spatio-temporal variability, due to its laborious obtaining. Large areas have been considered homogeneous, but show considerable spatial variability inherent in the soil, causing the appearance of zones of distinct physical properties. In deep, sandy soils where the groundwater level is far below the root zone of interference, internal drainage is one of the factors limiting the supply of water to the soil surface, and possibly one of the biggest factors that determines what kinds satisfactory development of plants present in a given landscape. The forms of relief may also be indicators of changes in soil properties, because this variability is caused by small changes that affect the slope of the pedogenetic processes and the transport and storage of water in the soil profile, i.e., the different trajectories of water flow in different forms of the landscape, is the cause of variability. The objectives of this research were: i) evaluate the spatial and temporal stability of internal soil water drainage in a place near and another distant from the root system in a bean-black-oat succession and ii) verify their spatial variability in relation to relief. With the hydraulic conductivity obtained by the instantaneous profile method and the total potential gradient obtained from the difference in readings of tensiometers installed at depths of 0.35 and 0.45 and 0.75 and 0.85 m in 60 sampling points totaling 1680 and 1200 observations during the cultivation of beans and oats, respectively, was obtained so the internal drainage / capillary rise through the Darcy-Buckingham equation. To evaluate the temporal stability the method used was the relative difference and Spearman correlation test and the spatial variability was analyzed as geostatistical methodology

  12. Snowpack spatial variability: Towards understanding its effect on remote sensing measurements and snow slope stability

    Science.gov (United States)

    Marshall, Hans-Peter

    The distribution of water in the snow-covered areas of the world is an important climate change indicator, and it is a vital component of the water cycle. At local and regional scales, the snow water equivalent (SWE), the amount of liquid water a given area of the snowpack represents, is very important for water resource management, flood forecasting, and prediction of available hydropower energy. Measurements from only a few automatic weather stations, such as the SNOTEL network, or sparse manual snowpack measurements are typically extrapolated for estimating SWE over an entire basin. Widespread spatial variability in the distribution of SWE and snowpack stratigraphy at local scales causes large errors in these basin estimates. Remote sensing measurements offer a promising alternative, due to their large spatial coverage and high temporal resolution. Although snow cover extent can currently be estimated from remote sensing data, accurately quantifying SWE from remote sensing measurements has remained difficult, due to a high sensitivity to variations in grain size and stratigraphy. In alpine snowpacks, the large degree of spatial variability of snowpack properties and geometry, caused by topographic, vegetative, and microclimatic effects, also makes prediction of snow avalanches very difficult. Ground-based radar and penetrometer measurements can quickly and accurately characterize snowpack properties and SWE in the field. A portable lightweight radar was developed, and allows a real-time estimate of SWE to within 10%, as well as measurements of depths of all major density transitions within the snowpack. New analysis techniques developed in this thesis allow accurate estimates of mechanical properties and an index of grain size to be retrieved from the SnowMicroPenetrometer. These two tools together allow rapid characterization of the snowpack's geometry, mechanical properties, and SWE, and are used to guide a finite element model to study the stress distribution

  13. Diurnal spatial variability of soil respiration estimated by ordinary kriging and sequential Gaussian simulation

    Science.gov (United States)

    de Bortoli Teixeira, Daniel; Rodrigo Panosso, Alan; Tadeu Pereira, Gener; Pelegrino Cerri, Carlos Eduardo; La Scala, Newton, Jr.

    2010-05-01

    The role of greenhouse gases in the climate change is well know, however, the balance of greenhouse gases due to land use and management is still lacking. Hence it is important to characterize the main aspects of soil respiration (or soil CO2 emission) in agricultural areas, including its spatial variability, as quantitatively as possible. The objective of this work was to study the diurnal spatial variability of the soil respiration including their estimations by different methods: ordinary kriging and sequential Gaussian simulation. Evaluations were conducted in a regular grid having 64 points installed over a bare Eutrustox clay texture during the morning and afternoon periods. Measurements were conducted from 7:30 - 10:30 am (morning) and 13:30 - 16:30 pm (afternoon) using a portable soil respiration system (LI-8100), Lincoln, NE, USA. In order to estimate the best interpolation method it was applied the so-called external validation, where the respiration values of 5 points in grid were removed from interpolation process and after were estimated in the same points by kriging or sequential Gaussian simulation methods. This evaluation was also based on the sum of the square of residues, comparing observed with predicted respiration values in each of the 5 points selected for external validation. The highest CO2 emission was observed in the afternoon period, with mean value of 6.24 µmol m-2 s-1, when compared to the morning (4.54 µmol m-2 s-1). Our results indicate that the measurement period (morning or afternoon) did not interfere into the definition of emission spatial variability structure, as coefficient of variation, spatial variability models and their parameters were quite similar in morning and afternoon. However, despite the high correlation between kriging and sequential Gaussian simulation respiration maps (R2 =0.99) sequential Gaussian simulation showed to be more efficient into the estimations of non-sampled emissions in both periods, mornings and

  14. Understanding the Temporal and Spatial Variability of New Generation Gridded TMYs

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Anthony

    2017-04-26

    Presentation at ASHRAE about the spatial and temporal variability of gridded TMYs, discussing advanced GIS and Web services that allow for direct access to data, surface-based observations for thousands of stations, climate reanalysis data, and products derived from satellite data; new developments in NREL's solar databases based on both observed data and satellite-derived gridded data, status of TMY3 weather files, and NREL's plans for the next-generation TMY weather files; and also covers what is new and different in the Climatic Design Conditions Table in the 2013 ASHRAE Handbook of Fundamentals.

  15. Linking the spatial variability of glacier mass loss to fjord geometry

    Science.gov (United States)

    Porter, D. F.; Tinto, K. J.; Boghosian, A.; Cochran, J. R.; Csatho, B. M.; Bell, R. E.

    2015-12-01

    There is compelling evidence of increasing mass loss of the ice sheets using a diverse set of observations, including increased thinning rates measured from both airborne and satellite altimeters, elevated mass fluxes resulting from the acceleration of outlet glaciers, and mass changes measured directly from satellite gravimetry. A dominant characteristic of observed change in Greenland outlet glaciers is that it is locally random. Numerous studies have revealed a high degree of spatial and temporal variability of outlet glacier mass change. Modeling studies suggest that increased ocean temperatures may be responsible for the observed glacial retreat in Greenland through increased basal melting, leading to increased calving rates, terminus retreat, glacier speedup, and eventually thinning of inland ice. Knowledge of fjord geometry is crucial for ice-ocean interaction because the availability of ocean heat to the ice will be restricted by narrow sills and shallow grounding lines. We investigate whether the variability in observed changes among Greenland glaciers can be partially explained by variation in fjord geometry. Using statistical techniques commonly employed to detect patterns in complex spatial data, we objectively show that mass change in Greenland tidewater glaciers between 2003 and 2009 is indeed mostly spatially incoherent. Except for a few clusters of similar change in the NW and Scoresby Sund regions, there is significant glacier-scale variability in mass loss rates. To understand the drivers of this local variability, we compare fjord bathymetries from all regions of Greenland, modeled using airborne gravimetry measurements from NASA Operation IceBridge flights, to estimates of glaciological change. Specifically, we investigate the correlation between water depths at the grounding line and the dynamic mass loss of tidewater glaciers. In theory, a deep grounding line will allow greater interaction with the warm Atlantic Water observed in most fjords

  16. Spatial variability more influential than soil pH and land relief on thermophilous vegetation in overgrown coppice oak forests

    Directory of Open Access Journals (Sweden)

    Tomasz H. Szymura

    2013-03-01

    Full Text Available The overgrown coppice oak forests that cover the southern slopes beneath the foothills of the Sudetes (Silesia, Central Europe are considered to be Euro-Siberian steppic woods with a Quercus sp. habitat (91I0: a priority habitat in the European Union, according to the Natura 2000 system. In subcontinental parts of Central Europe, thermophilous oak forest vegetation is found extrazonally; its presence, in the study site, is related to previous coppice management. In this paper we explore the differentiation of the vegetation caused both by land-relief derived variables (potential heat load, slope inclination and exposition, soil depth and soil pH, as well as spatial processes. The data on the vegetation were collected from 117 regularly arranged sampling plots, located in three mountain ranges. The vegetation consisted of a mixture of species considered as typical for different habitats (mesophilous forests, acidophilous forests, thermophilous oak forests, grassland, thermophilous fringes and mesophilous mantle and was relatively rich in species. Many of the species found were rare and are protected in Poland. The results of the bioindication, on the basis of Ellenberg indicator values, suggest the pH gradient to be the most important, followed by the insolation/moisture gradient, to the differentiation of the studied vegetation. The thermophilous oak forests seem to occupy the niche between acidophilous and mesophilous forest. However the decomposition of spatial variation, assessed on the basis of semivariance values of the vegetation similarity coefficient (frequency index, emphasizes a strong differentiation of vegetation between sites and mountain ranges. The results of canonical correspondence analysis, performed on a spatially stratified sub-set of the data, revealed a stronger effect caused by spatial variation (32.7% of explained species variation than environmental variables, such as soil pH and potential heat load (13.1%. Since the

  17. A method for quantitative analysis of spatially variable physiological processes across leaf surfaces.

    Science.gov (United States)

    Aldea, Mihai; Frank, Thomas D; DeLucia, Evan H

    2006-11-01

    Many physiological processes are spatially variable across leaf surfaces. While maps of photosynthesis, stomatal conductance, gene expression, water transport, and the production of reactive oxygen species (ROS) for individual leaves are readily obtained, analytical methods for quantifying spatial heterogeneity and combining information gathered from the same leaf but with different instruments are not widely used. We present a novel application of tools from the field of geographical imaging to the multivariate analysis of physiological images. Procedures for registration and resampling, cluster analysis, and classification provide a general framework for the analysis of spatially resolved physiological data. Two experiments were conducted to illustrate the utility of this approach. Quantitative analysis of images of chlorophyll fluorescence and the production of ROS following simultaneous exposure of soybean leaves to atmospheric O3 and soybean mosaic virus revealed that areas of the leaf where the operating quantum efficiency of PSII was depressed also experienced an accumulation of ROS. This correlation suggests a causal relationship between oxidative stress and inhibition of photosynthesis. Overlaying maps of leaf surface temperature and chlorophyll fluorescence following a photoinhibition treatment indicated that areas with low operating quantum efficiency of PSII also experienced reduced stomatal conductance (high temperature). While each of these experiments explored the covariance of two processes by overlaying independent images gathered with different instruments, the same procedures can be used to analyze the covariance of information from multiple images. The application of tools from geographic image analysis to physiological processes occurring over small spatial scales will help reveal the mechanisms generating spatial variation across leaves.

  18. Validation of spatial variability in downscaling results from the VALUE perfect predictor experiment

    Science.gov (United States)

    Widmann, Martin; Bedia, Joaquin; Gutiérrez, Jose Manuel; Maraun, Douglas; Huth, Radan; Fischer, Andreas; Keller, Denise; Hertig, Elke; Vrac, Mathieu; Wibig, Joanna; Pagé, Christian; Cardoso, Rita M.; Soares, Pedro MM; Bosshard, Thomas; Casado, Maria Jesus; Ramos, Petra

    2016-04-01

    VALUE is an open European network to validate and compare downscaling methods for climate change research. Within VALUE a systematic validation framework to enable the assessment and comparison of both dynamical and statistical downscaling methods has been developed. In the first validation experiment the downscaling methods are validated in a setup with perfect predictors taken from the ERA-interim reanalysis for the period 1997 - 2008. This allows to investigate the isolated skill of downscaling methods without further error contributions from the large-scale predictors. One aspect of the validation is the representation of spatial variability. As part of the VALUE validation we have compared various properties of the spatial variability of downscaled daily temperature and precipitation with the corresponding properties in observations. We have used two test validation datasets, one European-wide set of 86 stations, and one higher-density network of 50 stations in Germany. Here we present results based on three approaches, namely the analysis of i.) correlation matrices, ii.) pairwise joint threshold exceedances, and iii.) regions of similar variability. We summarise the information contained in correlation matrices by calculating the dependence of the correlations on distance and deriving decorrelation lengths, as well as by determining the independent degrees of freedom. Probabilities for joint threshold exceedances and (where appropriate) non-exceedances are calculated for various user-relevant thresholds related for instance to extreme precipitation or frost and heat days. The dependence of these probabilities on distance is again characterised by calculating typical length scales that separate dependent from independent exceedances. Regionalisation is based on rotated Principal Component Analysis. The results indicate which downscaling methods are preferable if the dependency of variability at different locations is relevant for the user.

  19. Geomorphometric tool associated with soil types and properties spatial variability at watersheds under tropical conditions

    Directory of Open Access Journals (Sweden)

    Sérgio Henrique Godinho Silva

    2016-08-01

    Full Text Available ABSTRACT The application of quantitative methods to digital soil and geomorphological mapping is becoming an increasing trend. One of these methods, Geomorphons, was developed to identify the ten most common landforms based on digital elevation models. This study aimed to make a quantitative assessment of the relationships between Geomorphons units, determined at three spatial resolutions and nine radii, and soil types and properties of two watersheds with different soil-landscape relationships in Brazil to help soil surveying and mapping under tropical conditions. The study was conducted at Lavrinha Creek (LCW and Marcela Creek (MCW watersheds, located in the state of Minas Gerais, Brazil. Spatial resolutions of 10, 20 and 30 m were the basis for generating Geomorphons at 9 radii of calculation for the watersheds. They were overlapped to detailed soil maps of the watersheds and a chi-square test was carried out to assess their relationship with soil types. Observation points were compared with the most highly correlated Geomorphons to also assess relationships with soil properties. Geomorphons with resolution of 30-m and radii of 20 and 50 cells, respectively for LCW and MCW, were more highly correlated with the variability of soil types, in accordance with the terrain features of these watersheds. The majority of observation points for each soil type was located in the same Geomorphon unit that was dominant when analyzing soil maps. There was less variability in soil properties between Geomorphon units, which was probably due to the highly weathered-leached stage of soils. Geomorphons can help to improve soil maps in tropical conditions when assessing soil variability due to its high correlation with tropical soil types variability.

  20. Environmental controls on the spatial variability of soil water dynamics in a small watershed

    Science.gov (United States)

    Hu, Wei; Chau, Henry Wai; Qiu, Weiwen; Si, Bingcheng

    2017-08-01

    Soil water content (SWC) in the root zone is controlled by a suite of environmental variables. Complication arises from the cross-correlation between these environmental variables. Therefore, there is still a poor understanding on the controls of root zone SWC dynamics due, in part, to a lack of an appropriate method to untangle the controls. The objective of this study was to reveal the dominant controls of root zone soil water dynamics in a small watershed using an appropriate method based on empirical orthogonal function (EOF). For this purpose, SWC of 0-0.8 m layer in a small watershed on the Chinese Loess Plateau was used. The space-variant temporal anomaly (Rtn) of SWC, which is responsible for the spatial variability of soil water dynamics, was decomposed using the EOF. Results indicated that 86% of the total variations of Rtn were explained by three significant spatial structures (EOFs). Sand content and grass yield dominated the EOF1 of Rtn and elevation and aspect dominated EOF2 and EOF3 of Rtn , respectively. Moreover, their effects on soil water dynamics were time-dependent. The EOF analysis showed that three independent groups of factors (i.e., soil and vegetation dominated earth surface condition, elevation related near surface air humidity, and aspect regulated energy input) may drive the variability in soil water dynamics. Traditional correlation analysis, however, indicated that SWC was greater at higher elevation and sun-facing slopes, which distorted the soil water dynamics controls. Although original SWC-based partial correlation basically supported our findings, the results highly depended on the controlling factors selected. This study implied that Rtn rather than original SWC should be preferred for understanding soil water dynamics controls.

  1. Assessing the role of spatial rainfall variability on watersheds response using weather radar A case study in the Gard region, France

    Science.gov (United States)

    Anggraheni, Evi; Payrastre, Olivier; Emmanuel, Isabelle; Andrieu, Herve

    2014-05-01

    The consideration of spatial rainfall variability in hydrological modeling is not only an important scientific issue but also, with the current development of high resolution rainfall data from weather radars, an increasing request from managers of sewerage networks and from flood forecasting services. Although the literature on this topic is already significant, at this time the conclusions remain contrasted. The impact of spatial rainfall variability on the hydrological responses appears to highly depend both on the organization of rainfall fields and on the watershed characteristics. The objective of the study presented here is to confirm and analyze the high impact of spatial rainfall variability in the specific context of flash floods. The case study presented is located in the Gard region in south east of France and focuses on four events which occurred on 13 different watersheds in 2008. The hydrological behaviors of these watersheds have been represented by the distributed rainfall - runoff model CINECAR, which already proved to well represent the hydrological responses in this region (Naulin et al., 2013). The influence of spatial rainfall variability has been studied here by considering two different rainfall inputs: radar data with a resolution of 1 km x 1 km and the spatial average rainfall over the catchment. First, the comparison between simulated and measured hydrographs confirms the good performances of the model for intense rainfall events, independently of the level of spatial rainfall variability of these events. Secondly, the simulated hydrographs obtained from radar data are taken as reference and compared to those obtained from the average rainfall inputs by computing two values: the time difference and the difference of magnitude between the simulated peaks discharge. The results highly depend on the rainfall event considered, and on the level of organization of the spatial rainfall variability. According to the model, the behavior of the

  2. Spatial variability of E. coli in an urban salt-wedge estuary.

    Science.gov (United States)

    Jovanovic, Dusan; Coleman, Rhys; Deletic, Ana; McCarthy, David

    2017-01-15

    This study investigated the spatial variability of a common faecal indicator organism, Escherichia coli, in an urban salt-wedge estuary in Melbourne, Australia. Data were collected through comprehensive depth profiling in the water column at four sites and included measurements of temperature, salinity, pH, dissolved oxygen, turbidity, and E. coli concentrations. Vertical variability of E. coli was closely related to the salt-wedge dynamics; in the presence of a salt-wedge, there was a significant decrease in E. coli concentrations with depth. Transverse variability was low and was most likely dwarfed by the analytical uncertainties of E. coli measurements. Longitudinal variability was also low, potentially reflecting minimal die-off, settling, and additional inputs entering along the estuary. These results were supported by a simple mixing model that predicted E. coli concentrations based on salinity measurements. Additionally, an assessment of a sentinel monitoring station suggested routine monitoring locations may produce conservative estimates of E. coli concentrations in stratified estuaries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Spatial and temporal variability in response to hybrid electro-optical stimulation

    Science.gov (United States)

    Duke, Austin R.; Lu, Hui; Jenkins, Michael W.; Chiel, Hillel J.; Jansen, E. Duco

    2012-06-01

    Hybrid electro-optical neural stimulation is a novel paradigm combining the advantages of optical and electrical stimulation techniques while reducing their respective limitations. However, in order to fulfill its promise, this technique requires reduced variability and improved reproducibility. Here we used a comparative physiological approach to aid the further development of this technique by identifying the spatial and temporal factors characteristic of hybrid stimulation that may contribute to experimental variability and/or a lack of reproducibility. Using transient pulses of infrared light delivered simultaneously with a bipolar electrical stimulus in either the marine mollusk Aplysia californica buccal nerve or the rat sciatic nerve, we determined the existence of a finite region of excitability with size altered by the strength of the optical stimulus and recruitment dictated by the polarity of the electrical stimulus. Hybrid stimulation radiant exposures yielding 50% probability of firing (RE50) were shown to be negatively correlated with the underlying changes in electrical stimulation threshold over time. In Aplysia, but not in the rat sciatic nerve, increasing optical radiant exposures (J cm-2) beyond the RE50 ultimately resulted in inhibition of evoked potentials. Accounting for the sources of variability identified in this study increased the reproducibility of stimulation from 35% to 93% in Aplysia and 23% to 76% in the rat with reduced variability.

  4. Environment and Spatial Influences on Aquatic Insect Communities in Cerrado Streams: the Relative Importance of Conductivity, Altitude, and Conservation Areas.

    Science.gov (United States)

    Godoy, B S; Queiroz, L L; Lodi, S; Oliveira, L G

    2017-04-01

    The aquatic insect community is an important element for stream functionality and diversity, but the effects of altitude and conservation areas on the aquatic insect community have been poorly explored in neotropical ecozone. The lack of studies about the relative importance of space and environment on community structure is another obstacle within aquatic insect ecology, which precludes the inclusion of these studies in more current frameworks, like the metacommunity dynamics. We evaluated the relationship between the aquatic insect community structure at 19 streams in the Brazilian Cerrado and spatial and environmental variables, namely geographical distance among sites, stream altitude, chemical variables, and environmental protection areas. We partitioned the variance explained by spatial and environmental components using a partial redundancy analysis. The environment exhibited a strong spatial structure for abundance and number of genera, increasing these community parameters with elevated water conductivity. Only community composition had a large unexplained portion of variance, with a small portion constrained by environmental (altitude and conductivity) and spatial factors. A relevant point in the result was the streams with high conductivity were located outside of the conservation areas. These results suggest that the relationship between number of genera and abundance with environmental conditions is always associated with spatial configuration of streams. Our study shows that altitude is an important determinant of community structure, as it exerts indirect influences, and electrical conductivity directly determines community composition, and that some national parks may be inefficient in maintaining the diversity of aquatic insects in the Cerrado region.

  5. Measuring structural-functional correspondence: spatial variability of specialised brain regions after macro-anatomical alignment.

    Science.gov (United States)

    Frost, Martin A; Goebel, Rainer

    2012-01-16

    The central question of the relationship between structure and function in the human brain is still not well understood. In order to investigate this fundamental relationship we create functional probabilistic maps from a large set of mapping experiments and compare the location of functionally localised regions across subjects using different whole-brain alignment schemes. To avoid the major problems associated with meta-analysis approaches, all subjects are scanned using the same paradigms, the same scanner and the same analysis pipeline. We show that an advanced, curvature driven cortex based alignment (CBA) scheme largely removes macro-anatomical variability across subjects. Remaining variability in the observed spatial location of functional regions, thus, reflects the "true" functional variability, i.e. the quantified variability is a good estimator of the underlying structural-functional correspondence. After localising 13 widely studied functional areas, we found a large variability in the degree to which functional areas respect macro-anatomical boundaries across the cortex. Some areas, such as the frontal eye fields (FEF) are strongly bound to a macro-anatomical location. Fusiform face area (FFA) on the other hand, varies in its location along the length of the fusiform gyrus even though the gyri themselves are well aligned across subjects. Language areas were found to vary greatly across subjects whilst a high degree of overlap was observed in sensory and motor areas. The observed differences in functional variability for different specialised areas suggest that a more complete estimation of the structure-function relationship across the whole cortex requires further empirical studies with an expanded test battery.

  6. Vegetation-induced spatial variability of soil redox properties in wetlands

    Science.gov (United States)

    Szalai, Zoltán; Jakab, Gergely; Kiss, Klaudia; Ringer, Marianna; Balázs, Réka; Zacháry, Dóra; Horváth Szabó, Kata; Perényi, Katalin

    2016-04-01

    Vegetation induced land patches may result spatial pattern of on soil Eh and pH. These spatial pattern are mainly emerged by differences of aeration and exudation of assimilates. Present paper focuses on vertical extent and temporal dynamics of these patterns in wetlands. Two study sites were selected: 1. a plain wetland on calcareous sandy parent material (Ceglédbercel, Danube-Tisza Interfluve, Hungary); 2. headwater wetland with calcareous loamy parent material (Bátaapáti, Hungary). Two vegetation patches were studied in site 1: sedgy (dominated by Carex riparia) and reedy (dominated by Phragmites australis). Three patches were studied in site2: sedgy1 (dominated by C vulpina), sedgy 2 (C. riparia); nettle-horsetail (Urtica dioica and Equisetum arvense). Boundaries between patches were studied separately. Soil redox, pH and temperature studied by automated remote controlled instruments. Three digital sensors (Ponsell) were installed in each locations: 20cm and 40cm sensors represent the solum and 100 cm sensor monitors the subsoil). Groundwater wells were installed near to triplets for soil water sampling. Soil Eh, pH and temperature values were recorded in each 10 minutes. Soil water sampling for iron and DOC were carried out during saturated periods. Spatial pattern of soil Eh is clearly caused by vegetation. We measured significant differences between Eh values of the studied patches in the solum. We did not find this kinds horizontal differences in the subsoil. Boundaries of the patches usually had more reductive soil environment than the core areas. We have found temporal dynamics of the spatial redox pattern. Differences were not so well expressed during wintertime. These spatial patterns had influence on the DOC and iron content of porewater, as well. Highest temporal dynamics of soil redox properties and porewater iron could be found in the boundaries. These observations refer to importance patchiness of vegetation on soil chemical properties in

  7. Preliminary Study on Spatial Variability and Distribution of Soil Available Microelements in Pinggu County, Beijing, China

    Institute of Scientific and Technical Information of China (English)

    WANG Shu-ying; YU Tong-quan; WANG Jian-li; YANG Liu; YANG Kai; LU Ping

    2008-01-01

    The objectives of this study were to explore the spatial distribution of soil available microelements and to provide a firm foundation for scientifically formulated fertilizer. 1076 soil samples were collected from Pinggu County of Beijing, China, and the contents of available Cu, Zn, Fe, and Mn in topsoil (0-20 cm) and subsoil (20-40 cm) were analyzed respectively. Descriptive statistics and geostatistics were used to analyze the data. The mean values of topsoil available Cu, Zn, Fe, and Mn were 1.96, 2.51,17.32, and 10.91 mg kg-', respectively, which were at medium or at slightly above medium level. The topsoil content of the soil available microelements was more than that of subsoil. The result of semivariance analysis showed that the topsoil available Fe and Mn were spatially correlated at a larger distance of 21.6 and 45.3 km, and the available Cu and Zn were at a shorter distance of 3.1 and 2.9 km, respectively. The subsoil spatial correlation distances were obviously different from the topsoil, which were in the order of available Mn>Cu>Zn = Fe. The Kriging method was applied to calculate the unobserved points and was used to generate the contour map. The results showed that the structural factors, such as topology, soil types, and soil properties, were the main factors influencing the spatial distribution of topsoil available Fe and Mn. Topsoil available Cu and Zn contents were mainly affected by land use, and their contents in orchard and in vegetable land were greatly higher than in field. The spatial distribution of subsoil microelements was similar to that of the topsoil, which exhibited vertical distribution patterns. Fertilizer and pesticide application resulted in the higher contents of available Cu and Zn in Pinggu County. The higher content of available Zn is potentially harmful to soil environmental quality, which should be inspected.

  8. Spatial variability of N, P, and K in rice field in Sawah Sempadan, Malaysia

    Directory of Open Access Journals (Sweden)

    Saeed Mohamed Eltaib

    2002-04-01

    Full Text Available The variability of soil chemical properties such as total N, available P, and exchangeable K were examined on a 1.2 ha rice (Oryza sativa field. The soil (n = 72 samples were systematically taken from individual fields in Sawah Sempadan in thirty-six locations at two depths (0-20 and 20-30 cm. The Differential Global Positioning System (DGPS was used for locating the sample position. Geostatistical techniques were used to analyze the soil chemical properties variability of the samples that assist in site-specific management of the field. Results showed that areas of similarity were much greater for the soil chemical properties measured at the depth of (0-20 cm than that of the second lower (20- 30 cm. The ranges of the semivariogram for total N, available P, and exchangeable K were 12, and 13 m (0-20 cm, 12 and 38 m (20-30 cm, respectively. Point kriging calculated from the semivariogram was employed for spatial distribution map. The results suggested that soil chemical properties measured may be spatially dependent even within the small.

  9. Providing a non-deterministic representation of spatial variability of precipitation in the Everest region

    Directory of Open Access Journals (Sweden)

    J. Eeckman

    2017-09-01

    Full Text Available This paper provides a new representation of the effect of altitude on precipitation that represents spatial and temporal variability in precipitation in the Everest region. Exclusive observation data are used to infer a piecewise linear function for the relation between altitude and precipitation and significant seasonal variations are highlighted. An original ensemble approach is applied to provide non-deterministic water budgets for middle and high-mountain catchments. Physical processes at the soil–atmosphere interface are represented through the Interactions Soil–Biosphere–Atmosphere (ISBA surface scheme. Uncertainties associated with the model parametrization are limited by the integration of in situ measurements of soils and vegetation properties. Uncertainties associated with the representation of the orographic effect are shown to account for up to 16 % of annual total precipitation. Annual evapotranspiration is shown to represent 26 % ± 1 % of annual total precipitation for the mid-altitude catchment and 34% ± 3 % for the high-altitude catchment. Snowfall contribution is shown to be neglectable for the mid-altitude catchment, and it represents up to 44 % ± 8 % of total precipitation for the high-altitude catchment. These simulations on the local scale enhance current knowledge of the spatial variability in hydroclimatic processes in high- and mid-altitude mountain environments.

  10. [Nutrient spatial variability of tobacco soil restoration area and fertility suitability level evaluation].

    Science.gov (United States)

    Xu, Da-Bing; Deng, Jian-Qiang; Liu, Dong-Bi; Si, Guo-Han; Peng, Cheng-Lin; Yuan, Jia-Fu; Zhao, Shu-Jun; Wang, Rui

    2014-03-01

    By using geographic information system technology (GIS) and geostatistics methods, this paper studied the spatial variability of soil properties and available nutrients in the new regulation area units located in Qingjiangyuan modern tobacco agriculture science and technology park (Enshi, Hubei), suburb of Enshi City and the Baiyang base of Lichuan City, and further evaluation of the soil fertility suitability index (SFI) was carried out by use fuzzy mathematics. The results indicated that the effects of land restoration on the soil available phosphorus content variability and spatial distribution were very obvious, possibly due to the landform characteristics and restoration extent. The effect of land restoration on soil pH was small, however, serious soil acidification was detected in the soil sampled from Baiyang (pH soils taken from the suburb, Baiyang and Qingjiangyuan, respectively. In conclusion, attentions should be paid on soil acidification in Baiyang, soil fertility and equalization in the suburb, and soil fertility in the region of Qingjiangyuan with low SFI.

  11. Assessing spatial variability of soil petroleum contamination using visible near-infrared diffuse reflectance spectroscopy.

    Science.gov (United States)

    Chakraborty, Somsubhra; Weindorf, David C; Zhu, Yuanda; Li, Bin; Morgan, Cristine L S; Ge, Yufeng; Galbraith, John

    2012-11-01

    Visible near-infrared (VisNIR) diffuse reflectance spectroscopy (DRS) is a rapid, non-destructive method for sensing the presence and amount of total petroleum hydrocarbon (TPH) contamination in soil. This study demonstrates the feasibility of VisNIR DRS to be used in the field to proximally sense and then map the areal extent of TPH contamination in soil. More specifically, we evaluated whether a combination of two methods, penalized spline regression and geostatistics could provide an efficient approach to assess spatial variability of soil TPH using VisNIR DRS data from soils collected from an 80 ha crude oil spill in central Louisiana, USA. Initially, a penalized spline model was calibrated to predict TPH contamination in soil by combining lab TPH values of 46 contaminated and uncontaminated soil samples and the first-derivative of VisNIR reflectance spectra of these samples. The r(2), RMSE, and bias of the calibrated penalized spline model were 0.81, 0.289 log(10) mg kg(-1), and 0.010 log(10) mg kg(-1), respectively. Subsequently, the penalized spline model was used to predict soil TPH content for 128 soil samples collected over the 80 ha study site. When assessed with a randomly chosen validation subset (n = 10) from the 128 samples, the penalized spline model performed satisfactorily (r(2) = 0.70; residual prediction deviation = 2.0). The same validation subset was used to assess point kriging interpolation after the remaining 118 predictions were used to produce an experimental semivariogram and map. The experimental semivariogram was fitted with an exponential model which revealed strong spatial dependence among soil TPH [r(2) = 0.76, nugget = 0.001 (log(10) mg kg(-1))(2), and sill 1.044 (log(10) mg kg(-1))(2)]. Kriging interpolation adequately interpolated TPH with r(2) and RMSE values of 0.88 and 0.312 log(10) mg kg(-1), respectively. Furthermore, in the kriged map, TPH distribution matched with the expected TPH variability of the study site. Since the

  12. Temporal and Spatial Variability of Droughts in Southwest China from 1961 to 2012

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    Yaohuan Huang

    2015-10-01

    Full Text Available Southwest China (SC has suffered a series of super extreme droughts in the last decade. This study analyzed the temporal and spatial variations of drought in SC from 1961 to 2012. Based on precipitation anomaly index (PAI that was derived from 1 km gridded precipitation data, three time scales (month, year and decade for the drought frequency (DF and drought area were applied to estimate the spatio-temporal structure of droughts. A time-series analysis showed that winter droughts and spring droughts occurred frequently for almost half of the year from November to March. Summer droughts occasionally occurred in severe drought decades: the 1960s, 1980s and 2000s. During the period of observation, the percent of drought area in SC increased from the 1960s (<5% to the 2000s (>25%. A total of 57% of the area was affected by drought in 2011, when the area experienced its most severe drought both in terms of area and severity. The spatial analysis, which benefitted from the gridded data, detailed that all of SC is at drought risk except for the central Sichuan Basin. The area at high risk for severe and extreme droughts was localized in the mountains of the junction of Sichuan and Yunnan. The temporal and spatial variability can be prerequisites for drought resistance planning and drought risk management of SC.

  13. Spatial and temporal variability of the Glossina palpalis palpalis population in the Mbini focus (Equatorial Guinea

    Directory of Open Access Journals (Sweden)

    Nzambo-Ondo Sisinio

    2007-08-01

    Full Text Available Abstract Background Human African Trypanosomiasis is a vector-borne parasitic disease. The geographical distribution of the disease is linked to the spatial distribution of the tsetse fly. As part of a control campaign using traps, the spatial and temporal variability is analysed of the glossina populations present in the Mbini sleeping sickness foci (Equatorial Guinea. Results A significant drop in the annual mean of the G. p. palpalis apparent density was noted from 2004 to 2005, although seasonal differences were not observed. The apparent density (AD of G. p. palpalis varies significantly from one biotope to another. The fish dryers turned out to be zones with the greatest vector density, although the AD of G. p. palpalis fell significantly in all locations from 2004 to 2005. Conclusion Despite the tsetse fly density being relatively low in fish dryers and jetties, the population working in those zones would be more exposed to infection. The mono-pyramidal traps in the Mbini focus have been proven to be a useful tool to control G. p. palpalis, even though the activity on the banks of the River Wele needs to be intensified. The application of spatial analysis techniques and geographical information systems are very useful tools to discriminate zones with high and low apparent density of G. p. palpalis, probably associated with different potential risk of sleeping sickness transmission.

  14. Spatial and temporal variabilities of rainfall data using functional data analysis

    Science.gov (United States)

    Suhaila, Jamaludin; Yusop, Zulkifli

    2017-07-01

    The main concern of this study is to build a functional data object from discrete rainfall observations by looking at how rainfall fluctuates, both spatially and temporally, in the form of smoothing curves. The functional data methods employed in this study are able to extract additional information contained in the function and its derivatives which may not be normally available from traditional statistical methods. Functional concepts such as functional descriptive statistics and functional analysis of variance were applied to describe the spatial and temporal rainfall variations at the stations and at any time throughout the year. This study involves 32 rainfall stations in Peninsular Malaysia and rainfall records for 32 years. Eleven basis functions were used to describe the unimodal rainfall pattern for stations in the East Peninsula, while five and seven bases were required to describe the rainfall pattern for stations in the northwest, west, southwest, and central regions of the peninsula. Based on the location and scale curves, the highest mean and the highest variability of rainfall were observed during the northeast monsoon flow. On the other hand, the concept of functional analysis of variance allows the detailed information in determining when, in a time series, differences may exist in rainfall profiles between two or more regions. In general, the findings suggested that the rainfall profiles of the regions are very dependent on their geographical and spatial locations, as well as the monsoon effect, which reflects the time of year.

  15. Spatial and Temporal Variability of N, P and K Balances for Agroecosystems in China

    Institute of Scientific and Technical Information of China (English)

    SHEN Run-Ping; SUN Bo; ZHAO Qi-Guo

    2005-01-01

    Nitrogen, phosphorus, and potassium balances for agroecosystems in China from 1993 to 2001 were calculated at national and provincial levels using statistical data and related parameters, and their spatial and temporal variabilities were analyzed with GIS to estimate the potential impacts of nutrient N, P and K surpluses or deficits to soil, water and air. At the national scale, the N and P balances from 1993 to 2001 showed a surplus, with the nitrogen surplus remaining relatively stable from 1997-2001. Although during this period the P surplus pattern was similar to N, it had smaller values and kept increasing as the use of phosphate fertilizer increased year by year. However, K was deficient from 1993 to 2001 even though from 1999 to 2001 the K deficit decreased. The spatial analysis revealed higher N surpluses in the more developed southeastern provinces and lowest in the western and northern provinces where there was less chemical fertilizer input. The serious K deficit mainly occurred in Shanghai and Beijing municipalities, Jiangsu, Zhejiang and Hubei provinces, and Xinjiang autonomous regions. For the years 1992, 1996 and 2001, N surpluses and K deficits had significant positive spatial correlations with per capita gross domestic product (GDP), per capita gross industrial output value, and per capita net income of rural households. This showed that the level of economic development played an important role on nutrient balances in the agroecosystems.

  16. Spatial variability of microbial biomass and organic matter labile pools in a haplic planosol soil

    Directory of Open Access Journals (Sweden)

    Diego Campana Loureiro

    2010-01-01

    Full Text Available The objective of this work was to study the spatial variability of soil microbial biomass (SMB and labile soil organic matter pools (labile SOM, under different management systems and plant cover. The experiment was conducted in a Haplic Planosol soil on an Integrated Agroecological Production System (SIPA, in Seropédica, Rio de Janeiro. The evaluated management systems were: alley cropping, pasture, and bush garden, the late one was used as reference area. Three grids of regular spacing of 2.5 x 2.5 meters were used for sampling, consisting of 25 georeferenced points each, where soil samples were taken at 0-10 cm depth. The following labile constituents of soil organic matter were determined: free light fraction (FLF, water soluble C and N, C and N of SMB (SMB-C and SMB-N, and glomalin content. The textural fractions (sand, silt, and clay, pH in water, and chemical attributes (organic C, total N, Ca, Mg, Al, P, K, and CEC-cation exchange capacity were also determined. The areas of alley cropping and pasture showed spatial dependence to the attributes of SOM. The occurrence of high spatial dependence for the attributes associated to microbial biomass in the alley cropping system (C, FLF, SMB-N and respiration, probably was due to external factors related to management, such as: intensive rotational cropping system, diversity of crops and different inputs of organic matter to soil such as pruning material and organic compost.

  17. Influence of environmental variables on Baylisascaris procyonis infection in raccoons.

    Science.gov (United States)

    Samson, Amanda; Dubay, Shelli A; Huspeni, Todd C; Cyr, Amanda

    2012-12-01

    Baylisascaris procyonis is a zoonotic nematode commonly found in raccoons (Procyon lotor). Human-altered landscapes can support dense populations of raccoons, increasing the potential for interaction between humans and these animals. We used raccoon feces provided by licensed fur trappers to investigate environmental variables that influence prevalence of B. procyonis at 2 sites in Wisconsin. Trappers submitted raccoon feces to us, along with information on sex, age (juvenile and adult), and approximate trap location for each animal. We used zinc sulfate (1.18 specific gravity) flotation to detect B. procyonis eggs in approximately 1 g of fecal matter from each host. We used ArcView software to determine the distance of each trap location to an urban area as determined by the U.S. Census Bureau in 2000. We compared the habitat components in buffered home ranges (0.805 km around trap locations) of infected animals with those from uninfected animals using Mann-Whitney U-tests (P Raccoons infected with B. procyonis had significantly larger area of agricultural habitats and significantly smaller areas of forested habitats in buffered home ranges than uninfected individuals. We found that raccoons near Madison and Milwaukee, Wisconsin, are commonly infected with B. procyonis , indicating that public education regarding protection from disease is warranted.

  18. Spatial prediction of the variability of Early Pleistocene subsurface sediments in the Netherlands - Part 1 : Heavy minerals

    NARCIS (Netherlands)

    Huisman, D.J.; Weijers, J.P.; Dijkshoorn, L.; Veldkamp, A.

    2000-01-01

    We investigated the spatial variability of the heavy-mineral composition in the Early Pleistocene fluviatile Kedichem Formation in the Netherlands in order to meet the demand for more information about subsurface sediment composition. We first determined the spatial extension and thickness of the se

  19. Performance analysis of improved methodology for incorporation of spatial/spectral variability in synthetic hyperspectral imagery

    Science.gov (United States)

    Scanlan, Neil W.; Schott, John R.; Brown, Scott D.

    2004-01-01

    Synthetic imagery has traditionally been used to support sensor design by enabling design engineers to pre-evaluate image products during the design and development stages. Increasingly exploitation analysts are looking to synthetic imagery as a way to develop and test exploitation algorithms before image data are available from new sensors. Even when sensors are available, synthetic imagery can significantly aid in algorithm development by providing a wide range of "ground truthed" images with varying illumination, atmospheric, viewing and scene conditions. One limitation of synthetic data is that the background variability is often too bland. It does not exhibit the spatial and spectral variability present in real data. In this work, four fundamentally different texture modeling algorithms will first be implemented as necessary into the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model environment. Two of the models to be tested are variants of a statistical Z-Score selection model, while the remaining two involve a texture synthesis and a spectral end-member fractional abundance map approach, respectively. A detailed comparative performance analysis of each model will then be carried out on several texturally significant regions of the resultant synthetic hyperspectral imagery. The quantitative assessment of each model will utilize a set of three peformance metrics that have been derived from spatial Gray Level Co-Occurrence Matrix (GLCM) analysis, hyperspectral Signal-to-Clutter Ratio (SCR) measures, and a new concept termed the Spectral Co-Occurrence Matrix (SCM) metric which permits the simultaneous measurement of spatial and spectral texture. Previous research efforts on the validation and performance analysis of texture characterization models have been largely qualitative in nature based on conducting visual inspections of synthetic textures in order to judge the degree of similarity to the original sample texture imagery. The quantitative

  20. Hot spots of mercury methylation in northern peatlands : spatial and seasonal variability

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, C.P.J.; Branfireun, B.A. [Toronto Univ., ON (Canada). Dept. of Geography; Heyes, A. [Maryland Univ., Solomons, MD (United States). Center for Environmental Science, Chesapeake Biological Lab; Kolka, R.K. [USDA Forest Service, North Central Research Station, Grand Rapids, MN (United States)

    2006-07-01

    Studies have shown that peatlands are an important sources of methylmercury (MeHg) to downstream aquatic ecosystems at the watershed scale. Hot spots of overly high MeHg concentration have been found to occur periodically in zones of groundwater upwelling. However, the spatiotemporal distribution, size, and importance of these MeHg hot spots to peatland MeHg export are not currently understood. For that reason, peat pore waters were sampled extensively throughout 4 small, northern peatlands in order to assess the spatial patterns of total mercury (HgT) and MeHg. The transferability of findings among peatlands was also assessed. Sampling took place during the spring, mid-summer and fall of 2005 at 2 peatlands in north central Minnesota and 2 in northwestern Ontario. In addition to this spatial survey, 4 high-resolution sampling grids were also established at the Minnesota sites in order to investigate the size of hot spots and the effects of upland runoff. In all cases, spatial variability in pore water MeHg concentration was much higher than the variability in HgT concentration, with standard deviations typically exceeding mean values. The spatial pattern of pore water MeHg concentration was characterized into the following 2 distinct zones: (1) the upland-peatland interface, where MeHg concentrations higher than 2 ng/L occur consistently, (2) the peatland interior, where concentrations rarely exceed 0.5 ng/L. In addition, extremely high concentrations of up to 12 ng/L were only found at the upland-peatland interface. These values corresponded to MeHg:HgT ratios greater than 65 per cent, while these ratios rarely exceeded 5 to 10 per cent elsewhere. It was concluded that these hot spots can be attributed to the limited reactants in zones where the in-situ biogeochemical milieu is conducive to mercury methylation. The uniform patterns noted across the peatlands indicate that spatial patterns of HgT and MeHg are important for mechanistic modelling and landscape

  1. Drivers of spatial and temporal variability of streamflow in the Incomati River Basin

    Directory of Open Access Journals (Sweden)

    A. M. L. Saraiva Okello

    2014-07-01

    Full Text Available The Incomati is a semi-arid trans-boundary river basin in southern Africa, with a high variability of streamflow and competing water demands from irrigated agriculture, energy, forestry and industries. These sectors compete with environmental flows and basic human water needs, resulting in a "stressed" water resources system. The impacts of these demands, relative to the natural flow regime, appear significant. However, despite being a relatively well-gauged basin in South Africa, the natural flow regime and its spatial and temporal variability are poorly understood and remain poorly described, resulting in a limited knowledge base for water resources planning and management decisions. Thus, there is an opportunity to improve water management, if it can be underpinned by a better scientific understanding of the drivers of streamflow availability and variability in the catchment. In this study, long-term rainfall and streamflow records were analysed. Statistical analysis, using annual anomalies, was conducted on 20 rainfall stations, for the period of 1950 to 2011. The Spearman Test was used to identify any trends in the records at annual and monthly time scales. The variability of rainfall across the basin was confirmed to be high, both intra- and inter-annually. The statistical analysis of rainfall data revealed no significant trend of increase or decrease for the studied period. Observed flow data from 33 gauges was screened and analyzed, using the Indicators of Hydrologic Alteration (IHA approach. Long-term analyses were conducted to identify temporal/spatial variability and trends in streamflow records. Temporal variability was high, with the coefficient of variation of annual flows in the range of 1 to 3.6. Significant declining trends in October flows, and low flows indicators were also identified at most gauging stations of the Komati and Crocodile sub-catchments, however no trends were evident on the other parameters, including high

  2. Geo(spatial) Health Investigation of Rotavirus in an Endemic Region: Hydroclimatic Influences and Epidemiology of Rotavirus in Bangladesh

    Science.gov (United States)

    Hasan, M. A.; Akanda, A. S.; Jutla, A.; Colwell, R. R.

    2016-12-01

    Rotavirus is the leading cause of severe dehydrating diarrhea among children under 5. Over 80% of the approximate half a million child deaths every year occur in South Asia and sub-Saharan Africa alone. Although less explored than cholera as a climate driven and influenced global health problem, recent studies have showed that the disease shown strong seasonality and spatio-temporal variability depending on regional hydroclimatic and local environmental conditions. Understanding the epidemiology of this disease, especially the spatio-temporal incidence patterns with respect to environmental factors is vitally important to allow for identification of "hotspots", preventative preparations, and vaccination strategies to improve wellbeing of the vulnerable populations. With climate change, spatio-temporal signatures and footprints of the disease are changing along with increasing burden. However, a robust understanding of the relationships between rotavirus epidemiology and hydroclimatic drivers is yet to be developed. In this study, we evaluate the seasonality and epidemiologic characteristics of rotavirous infection and its spatio-temporal incidence patterns with respect to regional hydroclimatic variables and their extremes in an endemic region in South Asia. Hospital-based surveillance data from different geographic locations allowed us to explore the detailed spatial and temporal characteristics of rotavirus propagation under the influence of climate variables in both coastal and inland areas. The rotavirus transmission patterns show two peaks in a year in the capital city of Dhaka, where winter season (highest in January) shows a high peak and the July-August monsoon season shows a smaller peak. Correlation with climate variables revealed that minimum temperature has strong influence on the winter season outbreak, while rainfall extremes show a strong positive association with the secondary monsoon peak. Spatial analysis also revealed that humidity and soil

  3. Assessing the Spatial Variability of Alfalfa Yield Using Satellite Imagery and Ground-Based Data

    Science.gov (United States)

    Kayad, Ahmed G.; Al-Gaadi, Khalid A.; Tola, ElKamil; Madugundu, Rangaswamy; Zeyada, Ahmed M.; Kalaitzidis, Chariton

    2016-01-01

    Understanding the temporal and spatial variability in a crop yield is viewed as one of the key steps in the implementation of precision agriculture practices. Therefore, a study on a center pivot irrigated 23.5 ha field in Saudi Arabia was conducted to assess the variability in alfalfa yield using Landsat-8 imagery and a hay yield monitor data. In addition, the study was designed to also explore the potential of predicting the alfalfa yield using vegetation indices. A calibrated yield monitor mounted on a large rectangular hay baler was used to measure the actual alfalfa yield for four alfalfa harvests performed in the period from October 2013 to May 2014. A total of 18 Landsat-8 images, representing different crop growth stages, were used to derive different vegetation indices (VIs). Data from the yield monitor was used to generate yield maps, which illustrated a definite spatial variation in alfalfa yield across the experimental field for the four studied harvests as indicated by the high spatial correlation values (0.75 to 0.97) and the low P-values (4.7E-103 to 8.9E-27). The yield monitor-measured alfalfa actual yield was compared to the predicted yield form the Vis. Results of the study showed that there was a correlation between actual and predicted yield. The highest correlations were observed between actual yield and the predicted using NIR reflectance, SAVI and NDVI with maximum correlation coefficients of 0.69, 0.68 and 0.63, respectively. PMID:27281189

  4. Spatial and temporal variability of late Holocene sea-level changes in the North Atlantic (Invited)

    Science.gov (United States)

    Kemp, A.; Kopp, R. E.; Horton, B.; Cahill, N.

    2013-12-01

    Proxy sea-level reconstructions spanning the last ~2000 years capture multiple phases of climate and sea level behavior for model calibration, provide a pre-anthropogenic background against which to compare recent trends, and characterize patterns of natural spatial and temporal variability. In the western North Atlantic basin, salt-marsh sediment is an archive for reconstructing sea level with the decimeter and multi-decadal resolution necessary to characterize subtle changes. New and existing salt-marsh reconstructions from northern Florida, North Carolina, New Jersey, Connecticut, and Massachusetts provide a dataset for investigating spatial and temporal sea-level variability during the late Holocene. The reconstructions were developed using foraminifera, plants, and bulk sediment δ13C values as sea-level proxies. The age of sediment deposition was estimated from composite chronologies of radiocarbon and chronohorizons of regional pollution and land-use change that were combined in age depth models. We used a spatio-temporal Gaussian process model to identify and characterize persistent phases of sea level behavior during the late Holocene in the western North Atlantic Ocean. The results indicate an acceleration in global mean sea level from the early 19th century through the early 20th century. The rate of sea-level rise increased significantly in the late 19th century. The timing and magnitude of this rise varied among sites even after accounting for differences in glacio-isostatic adjustment. Sea level in North Carolina rose faster than in New Jersey sea-level during the Medieval Climate Optimum, while sea level in New Jersey rose faster during the Little Ice Age. Spatially variable sea-level rise on the Atlantic coast of North America can be caused by dynamic oceanographic processes and/or melting of the Greenland Ice Sheet. Our analysis suggests that plausible levels of meltwater input from Greenland would be inadequate to explain the reconstructed pattern

  5. Hydrological response to changing climate conditions: Spatial streamflow variability in the boreal region

    Science.gov (United States)

    Teutschbein, Claudia; Grabs, Thomas; Karlsen, Reinert H.; Laudon, Hjalmar; Bishop, Kevin

    2016-04-01

    It has long been recognized that streamflow-generating processes are not only dependent on climatic conditions, but also affected by physical catchment properties such as topography, geology, soils and land cover. We hypothesize that these landscape characteristics do not only lead to highly variable hydrologic behavior of rather similar catchments under the same stationary climate conditions (Karlsen et al., 2014), but that they also play a fundamental role for the sensitivity of a catchment to a changing climate (Teutschbein et al., 2015). A multi-model ensemble based on 15 regional climate models was combined with a multi-catchment approach to explore the hydrologic sensitivity of 14 partially nested and rather similar catchments in Northern Sweden to changing climate conditions and the importance of small-scale spatial variability. Current (1981-2010) and future (2061-2090) streamflow was simulated with the HBV model. As expected, projected increases in temperature and precipitation resulted in increased total available streamflow, with lower spring and summer flows, but substantially higher winter streamflow. Furthermore, significant changes in flow durations with lower chances of both high and low flows can be expected in boreal Sweden in the future. This overall trend in projected streamflow pattern changes was comparable among the analyzed catchments while the magnitude of change differed considerably. This suggests that catchments belonging to the same region can show distinctly different degrees of hydrological responses to the same external climate change signal. We reason that differences in spatially distributed physical catchment properties at smaller scales are not only of great importance for current streamflow behavior, but also play a major role as first-order control for the sensitivity of catchments to changing climate conditions. References Karlsen, R.H., T. Grabs, K. Bishop, H. Laudon, and J. Seibert (2014). Landscape controls on

  6. The spatial multiscale variability of heavy metals based on factorial kriging analysis:A case study in the northeastern Beibu Gulf

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jianru; CHU Fengyou; JIN Xianglong; WU Qingsong; YANG Kehong; GE Qian; JIN Lu

    2015-01-01

    Factorial kriging analysis is applied to the research on the spatial multiscale variability of heavy metals in submarine. It is used to analyze the multiscale spatial structures of seven heavy metals, Ni, Cu, Zn, Pb, Cr, As and Cd in the surface sediment from the northeastern of Beibu Gulf, identify and separate spatial variations at different scales of heavy metals, and discuss the provenance of heavy metals and the influencing factors. The results show that the existence of three-scale spatial variations those consist of nugget effect, a spherical structure with range of 30 km (short-range scale) and a spherical structure with range of 140 km (long-range scale) in the linear model of coregionalization fitted. The spatial distribution features of seven heavy metals at short-range scale reflect “spot-like” or “stripe-like” local-scale spatial variations; the spatial distribution features of the seven heavy metals at long-range scale represent “slice-like” regional-scale spatial variations. At local scale, Zn, Cr, Ni, Cu, Pb and Cd are derived primarily from parent materials of Hainan Island, Leizhou Peninsula and Guangxi land, whose spatial distribution characteristics are controlled by granularity of sediments, while As is influenced dominantly by human pollution components from Hainan Island and Leizhou Peninsula. At regional scale, Zn, Cr, Ni and Cu originate primarily from parent rock materials of Leizhou Peninsula and Hainan Island, secondly from Guangxi land; As originated primarily from parent rock materials from Hainan Island, secondly from Leizhou Peninsula and Guangxi land. These metals are transported and migrated with sediments dominated by the anticlockwise circulation of Beibu Gulf year-round, deposited in “convergence center”, forming the whole sedimentary pattern in direction of NWW-NNW at regional scale. The difference in distribution type between As and other metals at regional scale is mainly due to their different geochemical

  7. Ecophysiological variables influencing Aleppo pine seed and cone production: a review.

    Science.gov (United States)

    Ayari, Abdelaziz; Khouja, Mohamed Larbi

    2014-04-01

    The most interesting factors associated with seed and cone production of Aleppo pine were largely reviewed to identify broad patterns and potential effectiveness of reforestation efforts and planning. Aleppo pine cone production and seed yields are relatively variable, with differences between spatial and temporal influences. These differences are considered, mainly between (i) year, (ii) stand characteristics and (iii) individual tree measurements. Annual variability among populations was recorded for cone production per tree, based on influencing factors such as genetic characteristics, wetness, nutrient availability, insect pests and disease. In addition, some factors may affect Aleppo pine tree growth directly but may be affecting seed and cone production indirectly. Therefore, reduced stand density results in less competition among Aleppo pine trees and accompanying understory flora, which subsequently increases the stem diameter and other tree dimensions, including seed production. This review suggests that reforestation planning, particularly thinning, will result in improved tree morphology that will increase Aleppo pine seed and cone crops. Wildfire intensity and stand conditions such as light and soil nutrient status are also examined.

  8. Spatial Variability in Enceladus' Plume Material: Convergence of Evidence or Coincidence?

    Science.gov (United States)

    Dhingra, Deepak; Hedman, Matthew M.; Clark, Roger Nelson

    2016-10-01

    Systematic spatial trends in the properties of the plume material emerging from Enceladus' tiger stripes can be observed in multiple observations from the Cassini mission. Subtle near infrared spectral differences within the plume have been reported across tiger stripes based on Visual and Infrared Mapping Spectrometer (VIMS) observations at high spatial resolution [1]. These spectral differences are likely due to variable water-ice grain size distribution along the source fissures (i.e. tiger stripes) and perhaps by the presence/absence of water vapor emission [2]. We now report a correlation of this spatial trend (along tiger stripes) with several other published results including (a) differences in the ice particle sizes across tiger stripes on Enceladus' surface [3, 4], (b) the surface abundance of organic material [3] and finally, (c) the relative proportion of type II grains (associated with organic/siliceous material) in the plume [5] from Damascus to Alexandria as measured by the Cosmic Dust Analyzer (CDA) instrument.The general trend indicates that at least some of the plume properties (viz. particle size, organic abundance) achieve a peak over Damascus and then become gradually subtle towards Alexandria. The observed differences between tiger stripes eruptions and the nature of correlations (trends from Damascus to Alexandria) hold important clues to the subsurface environment at Enceladus including differences in the geological setting of the individual tiger stripes [6]. The latter is a likely possibility given the large spatial spread of eruptions in Encealdus' South Polar Terrain (SPT).[1] Dhingra et al., (2015) 46th Lunar Planet. Sci. Conf., Abstract#1648[2] Dhingra et al. (2016) Icarus, submitted[3] Brown et al. (2006) Science, 311, 1425-1428[4] Jaumann et al. (2008) Icarus, 193, 407-419[5] Postberg et al. (2011) Nature, doi:10.1038/nature10175[6] Yin and Pappalardo (2015) Icarus, 260, 409-439

  9. Relative spatial soil geochemical variability along two transects across the United States and Canada

    Science.gov (United States)

    Garrett, Robert G.

    2009-01-01

    To support the development of protocols for the proposed North American Soil Geochemical Landscapes project, whose objective is to establish baselines for the geochemistry of North American soils, two continental-scale transects across the United States and Canada were sampled in 2004. The sampling employed a spatially stratified random sampling design in order to estimate the variability between 40-km linear sampling units, within them, at sample sites, and due to sample preparation and analytical chemical procedures. The 40-km scale was chosen to be consistent with the density proposed for the continental-scale project. The two transects, north–south (N–S) from northern Manitoba to the USA–Mexico border near El Paso, Texas, and east–west (E–W) from the Virginia shore north of Washington, DC, to north of San Francisco, California, closely following the 38th parallel, have been studied individually. The purpose of this study was to determine if statistically significant systematic spatial variation occurred along the transects. Data for 38 major, minor and trace elements in A- and C-horizon soils where less than 5% of the data were below the detection limit were investigated by Analysis of Variance (ANOVA). A total of 15 elements (K, Na, As, Ba, Be, Ce, La, Mn, Nb, P, Rb, Sb, Th, Tl and W) demonstrated statistically significant (p<0.05) variability at the between-40-km scale for both horizons along both transects. Only Cu failed to demonstrate significant variability at the between-40-km scale for both soil horizons along both transects.

  10. The influence of spatial coherence on the Goos-Haenchen shift at total internal reflection

    Energy Technology Data Exchange (ETDEWEB)

    Wang Liqin; Wang Ligang; Zhu Shiyao [Department of Physics, Zhejiang University, Hangzhou, 310027 (China); Zubairy, M Suhail [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)], E-mail: sxwlg@yahoo.com.cn

    2008-03-14

    In this paper, the influence of spatial coherence on the Goos-Haenchen (GH) shift at total internal reflection is theoretically investigated. Based on the theory of partial coherence, a general integral expression of the cross-spectral density is derived for a partially coherent beam reflected from an interface. Using numerical simulation, we find that the GH shift of the reflected beam greatly depends on the spatial coherence, and the GH shift is greatly reduced with a decrease in spatial coherence.

  11. Variables influencing the frictional behaviour of in vivo human skin

    NARCIS (Netherlands)

    Veijgen, N.K.; Masen, M.A.; Heide, van der E.

    2013-01-01

    In the past decades, skin friction research has focused on determining which variables are important to affect the frictional behaviour of in vivo human skin. Until now, there is still limited knowledge on these variables. This study has used a large dataset to identify the effect of variables on t

  12. Variables influencing the frictional behaviour of in vivo human skin

    NARCIS (Netherlands)

    Veijgen, N.K.; Masen, M.A.; Heide, E. van der

    2013-01-01

    In the past decades, skin friction research has focused on determining which variables are important to affect the frictional behaviour of in vivo human skin. Until now, there is still limited knowledge on these variables.This study has used a large dataset to identify the effect of variables on the

  13. The influence of caffeine on spatial-selective attention : an event-related potential study

    NARCIS (Netherlands)

    de Ruiter, MB; Snel, J; Lorist, MM; Ruijter, J

    2000-01-01

    Objectives: Following the indications of previous studies that caffeine might have a specific effect on the processing of spatial information compared with other types of information, the present study investigated the influence of caffeine on an often used spatial-selective attention task. Methods:

  14. Design in the planning arena : how regional designing influences strategic spatial planning

    NARCIS (Netherlands)

    Kempenaar, Annet

    2017-01-01

    Regional designing is a form of spatial design that engages with the future physical form and arrangement of regions, including its aesthetic appearances and how it can come about. As such it is closely entangled with spatial planning. This thesis studies the influence of regional designing on

  15. Evolution of Macao’s Urban Spatial Morphology and Its Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    After more than 450 years’ development, Macao has evolved into a world heritage city and world tourism and leisure city from a traditional Chinese fishing village. Its urban spatial morphology has gone through six stages. Based on the analysis of the historic events in Macao at different stages, this paper elaborates the process, characteristics, and influencing factors of the urban spatial morphology evolution.

  16. Untangling the contribution of aspect, drainage position and elevation to the spatial variability of fine surface fuels in south east Australian forests

    Science.gov (United States)

    Sheridan, Gary; nyman, petter; Duff, Tom; Baillie, Craig; Bovill, William; Lane, Patrick; Tolhurst, Kevin

    2015-04-01

    The prediction of fuel moisture content is important for estimating the rate of spread of wildfires, the ignition probability of firebrands, and for the efficient scheduling of prescribed fire. The moisture content of fine surface fuels varies spatially at large scales (10's to 100's km) due to variation in meteorological variables (eg. temperature, relative humidity, precipitation). At smaller scales (100's of metres) in steep topography spatial variability is attributed to topographic influences that include differences in radiation due to aspect and slope, differences in precipitation, temperature and relative humidity due to elevation, and differences in soil moisture due to hillslope drainage position. Variable forest structure and canopy shading adds further to the spatial variability in surface fuel moisture. In this study we aim to combine daily 5km resolution gridded weather data with 20m resolution DEM and vegetation structure data to predict the spatial variability of fine surface fuels in steep topography. Microclimate stations were established in south east Australia to monitor surface fine fuel moisture continuously (every 15 minutes) using newly developed instrumented litter packs, in addition to temperature and relative humidity measurements inside the litter pack, and measurement of precipitation and energy inputs above and below the forest canopy. Microclimate stations were established across a gradient of aspect (5 stations), drainage position (7 stations), elevation (15 stations), and canopy cover conditions (6 stations). The data from this extensive network of microclimate stations across a broad spectrum of topographic conditions is being analysed to enable the downscaling of gridded weather data to spatial scales that are relevant to the connectivity of wildfire fuels and to the scheduling and outcome of prescribed fires. The initial results from the first year of this study are presented here.

  17. KRIGRADI: A cokriging program for estimating the gradient of spatial variables from sparse data

    Science.gov (United States)

    Pardo-Igúzquiza, Eulogio; Chica-Olmo, Mario

    2007-05-01

    KRIGRADI is a universal cokriging program for estimating the directional derivatives of a spatial variable from sparse measurements of the variable and gradient measurements (if available). Then, the gradient vector field can be estimated because the components of the gradient vector are the directional derivatives along the main axis of coordinates. A typical example is the estimation of the hydraulic gradient from head data in groundwater hydrology. The only inferential requirement is the covariance (or semi-variogram) from the measurements of the variable and any other necessary covariance or cross-covariance is obtained by linear systems theory. There is, then, the possibility of including direct measurements of the gradient (if available, and no matter how few) in the estimation of a directional derivative or in the estimation of the gradient field. This is therefore an application of kriging for estimating a vector field from scalars and where experimental vector values could be used in the estimation. The program implements a number of possibilities for estimating the gradient as described in the appropriate section. The program, written in Fortran, can be easily modified for particular needs if desired. A case study is provided to illustrate the performance and implementation of the program.

  18. Space Technology 5 Multipoint Observations of Temporal and Spatial Variability of Field-Aligned Currents

    Science.gov (United States)

    Le, G.; Wang, Y.; Slavin, J. A.; Strangeway, R. L.

    2009-01-01

    Space Technology 5 (ST5) is a constellation mission consisting of three microsatellites. It provides the first multipoint magnetic field measurements in low Earth orbit, which enables us to separate spatial and temporal variations. In this paper, we present a study of the temporal variability of field-aligned currents using the ST5 data. We examine the field-aligned current observations during and after a geomagnetic storm and compare the magnetic field profiles at the three spacecraft. The multipoint data demonstrate that mesoscale current structures, commonly embedded within large-scale current sheets, are very dynamic with highly variable current density and/or polarity in approx.10 min time scales. On the other hand, the data also show that the time scales for the currents to be relatively stable are approx.1 min for mesoscale currents and approx.10 min for large-scale currents. These temporal features are very likely associated with dynamic variations of their charge carriers (mainly electrons) as they respond to the variations of the parallel electric field in auroral acceleration region. The characteristic time scales for the temporal variability of mesoscale field-aligned currents are found to be consistent with those of auroral parallel electric field.

  19. Measuring natural pest suppression at different spatial scales affects the importance of local variables.

    Science.gov (United States)

    Bennett, A B; Gratton, C

    2012-10-01

    The role biodiversity plays in the provision of ecosystem services is widely recognized, yet few ecological studies have identified characteristics of natural systems that support and maintain ecosystem services. The purpose of this study was to identify landscape variables correlated with natural pest suppression carried out by arthropod natural enemies, predators and parasitoids. We conducted two field experiments, one observational and one experimental, where landscape variables at broad and local scales were measured and related to natural pest suppression. The first experiment measured natural pest suppression at 16 sites across an urban to rural landscape gradient in south central Wisconsin. We found natural enemy diversity positively affected natural pest suppression, whereas flower diversity negatively affected pest suppression. No relationship was found between natural pest suppression and broad scale variables, which measured the percentage of different land cover classes in the surrounding landscape. In the second experiment, we established small (2- by 3-m) replicated plots that experimentally varied flower diversity (0, 1, or 7 species) within a plot. We found no significant relationship between natural pest suppression and the different levels of flower diversity. The fact that we only found differences in natural pest suppression in our first experiment, which measured natural pest suppression at sites separated by larger distances than our second experiment, suggests the more appropriate scale for measuring ecosystem services performed by mobile organisms like insects, is across broad spatial scales where variation in natural enemies communities and the factors that affect them become more apparent.

  20. Right-hemisphere (spatial?) acalculia and the influence of neglect

    OpenAIRE

    Silvia eBenavides-Varela; Marco ePitteri; Konstantinos ePriftis; Laura ePassarini; Francesca eMeneghello; Carlo eSemenza

    2014-01-01

    The present study aimed at exploring basic number and calculation abilities in right-hemisphere damaged patients (RHD), focusing primarily on one-digit orally presented tasks, which do not require explicit visuo-spatial abilities. Twenty-four non mentally-deteriorated RHD patients [12 with clinical neglect (RHDN+), 12 without clinical neglect (RHDN−)], and 12 healthy controls were included in the study. Participants were administered an ad hoc numerical battery assessing abilities such as cou...

  1. Right-hemisphere (spatial?) acalculia and the influence of neglect.

    Science.gov (United States)

    Benavides-Varela, Silvia; Pitteri, Marco; Priftis, Konstantinos; Passarini, Laura; Meneghello, Francesca; Semenza, Carlo

    2014-01-01

    The present study aimed at exploring basic number and calculation abilities in right-hemisphere damaged patients (RHD), focusing primarily on one-digit orally presented tasks, which do not require explicit visuo-spatial abilities. Twenty-four non mentally-deteriorated RHD patients [12 with clinical neglect (RHDN+), 12 without clinical neglect (RHDN-)], and 12 healthy controls were included in the study. Participants were administered an ad hoc numerical battery assessing abilities such as counting, number magnitude comparison, writing and reading Arabic numerals and mental calculation, among others. Significant differences emerged among healthy controls and both the RHDN+ group and the RHDN- group, suggesting that the mathematical impairment of RHD patients does not necessarily correspond to the presence of left-neglect. A detailed analysis of the sub-tests of the battery evidenced expected differences among RHDN+ patients, RHDN- patients, and controls in writing and reading Arabic numerals. Crucially, differences between RHDN+ patients and controls were also found in tasks such as mental subtraction and mental multiplication, which do not require written visuo-spatial abilities. The present findings thus suggest that unilateral right hemisphere lesions may produce specific representational deficits that affect simple mental calculation, and not only the spatial arrangement of multi-digit written numbers as previously thought.

  2. Alaskan soil carbon stocks: spatial variability and dependence on environmental factors

    Directory of Open Access Journals (Sweden)

    U. Mishra

    2012-09-01

    Full Text Available The direction and magnitude of soil organic carbon (SOC changes in response to climate change depend on the spatial and vertical distributions of SOC. We estimated spatially resolved SOC stocks from surface to C horizon, distinguishing active-layer and permafrost-layer stocks, based on geospatial analysis of 472 soil profiles and spatially referenced environmental variables for Alaska. Total Alaska state-wide SOC stock was estimated to be 77 Pg, with 61% in the active-layer, 27% in permafrost, and 12% in non-permafrost soils. Prediction accuracy was highest for the active-layer as demonstrated by highest ratio of performance to deviation (1.5. Large spatial variability was predicted, with whole-profile, active-layer, and permafrost-layer stocks ranging from 1–296 kg C m−2, 2–166 kg m−2, and 0–232 kg m−2, respectively. Temperature and soil wetness were found to be primary controllers of whole-profile, active-layer, and permafrost-layer SOC stocks. Secondary controllers, in order of importance, were found to be land cover type, topographic attributes, and bedrock geology. The observed importance of soil wetness rather than precipitation on SOC stocks implies that the poor representation of high-latitude soil wetness in Earth system models may lead to large uncertainty in predicted SOC stocks under future climate change scenarios. Under strict caveats described in the text and assuming temperature changes from the A1B Intergovernmental Panel on Climate Change emissions scenario, our geospatial model indicates that the equilibrium average 2100 Alaska active-layer depth could deepen by 11 cm, resulting in a thawing of 13 Pg C currently in permafrost. The equilibrium SOC loss associated with this warming would be highest under continuous permafrost (31%, followed by discontinuous (28%, isolated (24.3%, and sporadic (23.6% permafrost areas. Our high-resolution mapping of soil carbon stock reveals the

  3. Spatial Variability of Arsenic Concentrations in two Villages in Araihazar Upazila, Narayanganj District of Bangladesh

    Science.gov (United States)

    Dhar, R.; Zheng, Y.; Zheng, Y.; Stute, M.; Stute, M.; van Geen, A.; Gavrieli, I.; Gavrieli, I.; Versteeg, R.; Versteeg, R.; Steckler, M.; Goodbred, S.; Horneman, A.; Simpson, H. J.; Ahmed, K. M.

    2001-05-01

    In the Ganges-Brahmaputra Delta, concentrations of arsenic in tube wells have been known to vary spatially on both the basin (tens of km) and the local (tens of meter) scale. Based on arsenic concentration measured in 5000 contiguous tube wells from Araihazar Upazila, 20 km east of Dhaka, we began to investigate the geological, hydrological and geochemical controls on the arsenic spatial heterogeneity in two villages on spatial scales of order 100 m in January, 2001. In Dari Satyabhadi village (23.785° N, 90.603° E), arsenic concentrations in 157 wells range from 50 ug/L. Arsenic concentrations in 124 wells from Baylakandi village (23.780° N, 90.640° E) range from 10 ug/L to 520 ug/L (266 +/- 95 ug/L), with 98% of wells above 50 ug/L. Sediment coring in both villages to 92 m depth recovered a fine-grained clay zone separating an upper, perhaps less confined aquifer and a lower, confined aquifer. In Dari Satyabhadi village, The clay is located between 13 m and 30 m, with a thin silty sand layer at 20.1-20.7 m and a peat layer at 20.7-21.4 m. Below the clay, all existing tube wells, as well as monitoring wells, are found to have arsenic concentrations <50 ug/L. In Baylakandi village, a clay layer was found at greater depth between 30 and 50 m, with a silty sand layer between 36 and 43 m. None of the existing tube wells are deeper than the clay in Baylakandi, but monitoring wells installed at 53 m and 92 m yield water containing <50 ug/L arsenic. Results from both villages suggest that a lower aquifer isolated by a clay layer from shallow, high-arsenic aquifer contains little arsenic. In contrast, there is, however, considerable spatial variability in arsenic concentrations in both villages within the upper aquifer. In Dari Satyabhadi, arsenic concentrations in 120 shallow wells (< 30 m) from the upper aquifer ranges from <5 ug/L to 800 ug/L (158 +/- 160 ug/L), with 66% of wells above 50 ug/L. The source of this variability appears to be linked to the distribution

  4. Assimilation of temperature and hydraulic gradients for quantifying the spatial variability of streambed hydraulics

    Science.gov (United States)

    Huang, Xiang; Andrews, Charles B.; Liu, Jie; Yao, Yingying; Liu, Chuankun; Tyler, Scott W.; Selker, John S.; Zheng, Chunmiao

    2016-08-01

    Understanding the spatial and temporal characteristics of water flux into or out of shallow aquifers is imperative for water resources management and eco-environmental conservation. In this study, the spatial variability in the vertical specific fluxes and hydraulic conductivities in a streambed were evaluated by integrating distributed temperature sensing (DTS) data and vertical hydraulic gradients into an ensemble Kalman filter (EnKF) and smoother (EnKS) and an empirical thermal-mixing model. The formulation of the EnKF/EnKS assimilation scheme is based on a discretized 1D advection-conduction equation of heat transfer in the streambed. We first systematically tested a synthetic case and performed quantitative and statistical analyses to evaluate the performance of the assimilation schemes. Then a real-world case was evaluated to calculate assimilated specific flux. An initial estimate of the spatial distributions of the vertical hydraulic gradients was obtained from an empirical thermal-mixing model under steady-state conditions using a constant vertical hydraulic conductivity. Then, this initial estimate was updated by repeatedly dividing the assimilated specific flux by estimates of the vertical hydraulic gradients to obtain a refined spatial distribution of vertical hydraulic gradients and vertical hydraulic conductivities. Our results indicate that optimal parameters can be derived with fewer iterations but greater simulation effort using the EnKS compared with the EnKF. For the field application in a stream segment of the Heihe River Basin in northwest China, the average vertical hydraulic conductivities in the streambed varied over three orders of magnitude (5 × 10-1 to 5 × 102 m/d). The specific fluxes ranged from near zero (qz < ±0.05 m/d) to ±1.0 m/d, while the vertical hydraulic gradients were within the range of -0.2 to 0.15 m/m. The highest and most variable fluxes occurred adjacent to a debris-dam and bridge pier. This phenomenon is very likely

  5. Spatial variability of soil carbon stock in the Urucu river basin, Central Amazon-Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ceddia, Marcos Bacis, E-mail: marcosceddia@gmail.com [Department of Soil, Institute of Agronomy, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropédica, RJ 23890-000 (Brazil); Villela, André Luis Oliveira [Colégio Técnico da UFRRJ, RJ, Seropédica 23890-000 (Brazil); Pinheiro, Érika Flávia Machado [Department of Soil, Institute of Agronomy, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropédica, RJ 23890-000 (Brazil); Wendroth, Ole [Department of Plant & Soil Sciences, University of Kentucky, College of Agriculture, Lexington, KY (United States)

    2015-09-01

    The Amazon Forest plays a major role in C sequestration and release. However, few regional estimates of soil organic carbon (SOC) stock in this ecoregion exist. One of the barriers to improve SOC estimates is the lack of recent soil data at high spatial resolution, which hampers the application of new methods for mapping SOC stock. The aims of this work were: (i) to quantify SOC stock under undisturbed vegetation for the 0–30 and the 0–100 cm under Amazon Forest; (ii) to correlate the SOC stock with soil mapping units and relief attributes and (iii) to evaluate three geostatistical techniques to generate maps of SOC stock (ordinary, isotopic and heterotopic cokriging). The study site is located in the Central region of Amazon State, Brazil. The soil survey covered the study site that has an area of 80 km{sup 2} and resulted in a 1:10,000 soil map. It consisted of 315 field observations (96 complete soil profiles and 219 boreholes). SOC stock was calculated by summing C stocks by horizon, determined as a product of BD, SOC and the horizon thickness. For each one of the 315 soil observations, relief attributes were derived from a topographic map to understand SOC dynamics. The SOC stocks across 30 and 100 cm soil depth were 3.28 and 7.32 kg C m{sup −2}, respectively, which is, 34 and 16%, lower than other studies. The SOC stock is higher in soils developed in relief forms exhibiting well-drained soils, which are covered by Upland Dense Tropical Rainforest. Only SOC stock in the upper 100 cm exhibited spatial dependence allowing the generation of spatial variability maps based on spatial (co)-regionalization. The CTI was inversely correlated with SOC stock and was the only auxiliary variable feasible to be used in cokriging interpolation. The heterotopic cokriging presented the best performance for mapping SOC stock. - Highlights: • The SOC stocks across 30 and 100 cm depth were 3.28 and 7.32 kg C m{sup −2}, respectively. • SOC stocks were 34 and 16

  6. Alaskan soil carbon stocks: spatial variability and dependence on environmental factors

    Directory of Open Access Journals (Sweden)

    U. Mishra

    2012-05-01

    Full Text Available The direction and magnitude of soil organic carbon (SOC changes in response to climate change depend on the spatial and vertical distributions of SOC. We estimated spatially-resolved SOC stocks from surface to C horizon, distinguishing active-layer and permafrost-layer stocks, based on geospatial analysis of 472 soil profiles and spatially referenced environmental variables for Alaska. Total Alaska state-wide SOC stock was estimated to be 77 Pg, with 61% in the active-layer, 27% in permafrost, and 12% in non-permafrost soils. Prediction accuracy was highest for the active-layer as demonstrated by highest ratio of performance to deviation (1.5. Large spatial variability was predicted, with whole-profile, active-layer, and permafrost-layer stocks ranging from 1–296 kg C m−2, 2–166 kg m−2, and 0–232 kg m−2, respectively. Temperature and soil wetness were found to be primary controllers of whole-profile, active-layer, and permafrost-layer SOC stocks. Secondary controllers, in order of importance, were: land cover type, topographic attributes, and bedrock geology. The observed importance of soil wetness rather than precipitation on SOC stocks implies that the poor representation of high-latitude soil wetness in Earth System Models may lead to large uncertainty in predicted SOC stocks under future climate change scenarios. Under strict caveats described in the text and assuming temperature changes from the A1B Intergovernmental Panel on Climate Change emissions scenario, our geospatial model indicates that the equilibrium average 2100 Alaska active-layer depth could deepen by 11 cm, resulting in a thawing of 13 Pg C currently in permafrost. The equilibrium SOC loss associated with this warming would be highest under continuous permafrost (31%, followed by discontinuous (28%, isolated (24.3%, and sporadic (23.6% permafrost areas. Our high resolution mapping of soil carbon stock reveals the potential

  7. Spatial and temporal patterns of larval dispersal in a coral-reef fish metapopulation: evidence of variable reproductive success.

    Science.gov (United States)

    Pusack, Timothy J; Christie, Mark R; Johnson, Darren W; Stallings, Christopher D; Hixon, Mark A

    2014-07-01

    Many marine organisms can be transported hundreds of kilometres during their pelagic larval stage, yet little is known about spatial and temporal patterns of larval dispersal. Although traditional population-genetic tools can be applied to infer movement of larvae on an evolutionary timescale, large effective population sizes and high rates of gene flow present serious challenges to documenting dispersal patterns over shorter, ecologically relevant, timescales. Here, we address these challenges by combining direct parentage analysis and indirect genetic analyses over a 4-year period to document spatial and temporal patterns of larval dispersal in a common coral-reef fish: the bicolour damselfish (Stegastes partitus). At four island locations surrounding Exuma Sound, Bahamas, including a long-established marine reserve, we collected 3278 individuals and genotyped them at 10 microsatellite loci. Using Bayesian parentage analysis, we identified eight parent-offspring pairs, thereby directly documenting dispersal distances ranging from 0 km (i.e., self-recruitment) to 129 km (i.e., larval connectivity). Despite documenting substantial dispersal and gene flow between islands, we observed more self-recruitment events than expected if the larvae were drawn from a common, well-mixed pool (i.e., a completely open population). Additionally, we detected both spatial and temporal variation in signatures of sweepstakes and Wahlund effects. The high variance in reproductive success (i.e., 'sweepstakes') we observed may be influenced by seasonal mesoscale gyres present in the Exuma Sound, which play a prominent role in shaping local oceanographic patterns. This study documents the complex nature of larval dispersal in a coral-reef fish, and highlights the importance of sampling multiple cohorts and coupling both direct and indirect genetic methods in order disentangle patterns of dispersal, gene flow and variable reproductive success. © 2014 John Wiley & Sons Ltd.

  8. [Estimating nonstructural carbon content of tree crown considering its spatial variability: A case study on Juglans mandshurica and Ulmus japonica].

    Science.gov (United States)

    Cheng, Fang-yan; Wang, Chuan-kuan

    2015-08-01

    Using Juglans mandshurica and Ulmus japonica as test materials, we examined the variability in nonstructural carbohydrates (NSC) concentrations in the branches with different basal diameters with a branch analysis method and explored potential errors in estimating the crown-scale NSC content introduced from various sampling protocols. The results showed that organs significantly influenced the crown NSC concentrations for both species. The mean concentrations of the sum of soluble sugars and starch (TNC) of the leaves, new twigs, old branches, and dead branches were 17.6%, 12.6%, 5.7% and 2.9%, respectively. Most of the NSC concentrations in leaves and new twigs varied insignificantly with basal diameter, age, length and height of the branch. However, the NSC concentration in old branches increased significantly with decreasing the basal diameter, age and length of the branch, and with increasing the relative height of the branch. Among the branch traits, basal diameter was the best predictor for the NSC concentration of the old branch (the R2 between 0.87 and 0.95). The mean TNC contents of leaves, new branches, and old branches for the two species accounted for 28%, 2% and 70% of the crown TNC content, respectively. Considering the effect of the spatial variability in the estimation of NSC content, we recommend the sampling protocol that applies the NSC concentration of new twigs and old branches with a diameter of 3 cm to up-scale the crown NSC content as a simple and practical method.

  9. Investigating soil controls on soil moisture spatial variability: Numerical simulations and field observations

    Science.gov (United States)

    Wang, Tiejun; Franz, Trenton E.; Zlotnik, Vitaly A.; You, Jinsheng; Shulski, Martha D.

    2015-05-01

    Due to its complex interactions with various processes and factors, soil moisture exhibits significant spatial variability across different spatial scales. In this study, a modeling approach and field observations were used to examine the soil control on the relationship between mean (θ bar) and standard deviation (σθ) of soil moisture content. For the numerical experiments, a 1-D vadose zone model along with van Genuchten parameters generated by pedotransfer functions was used for simulating soil moisture dynamics under different climate and surface conditions. To force the model, hydrometeorological and physiological data that spanned over three years from five research sites within the continental US were used. The modeling results showed that under bare surface conditions, different forms of the θ bar -σθ relationship as observed in experimental studies were produced. For finer soils, a positive θ bar -σθ relationship gradually changed to an upward convex and a negative one from arid to humid conditions; whereas, a positive relationship existed for coarser soils, regardless of climatic conditions. The maximum σθ for finer soils was larger under semiarid conditions than under arid and humid conditions, while the maximum σθ for coarser soils increased with increasing precipitation. Moreover, vegetation tended to reduce θ bar and σθ, and thus affected the θ bar -σθ relationship. A sensitivity analysis was also conducted to examine the controls of different van Genuchten parameters on the θ bar -σθ relationship under bare surface conditions. It was found that the residual soil moisture content mainly affected σθ under dry conditions, while the saturated soil moisture content and the saturated hydraulic conductivity largely controlled σθ under wet conditions. Importantly, the upward convex θ bar -σθ relationship was mostly caused by the shape factor n that accounts for pore size distribution. Finally, measured soil moisture data from a

  10. Evaluating the influence of spatial resolutions of DEM on watershed runoff and sediment yield using SWAT

    Indian Academy of Sciences (India)

    A Sivasena Reddy; M Janga Reddy

    2015-10-01

    Digital elevation model (DEM) of a watershed forms key basis for hydrologic modelling and its resolution plays a key role in accurate prediction of various hydrological processes. This study appraises the effect of different DEMs with varied spatial resolutions (namely TOPO 20 m, CARTO 30 m, ASTER 30 m, SRTM 90 m, GEO-AUS 500 m and USGS 1000 m) on hydrological response of watershed using Soil and Water Assessment Tool (SWAT) and applied for a case study of Kaddam watershed in India for estimating runoff and sediment yield. From the results of case study, it was observed that reach lengths, reach slopes, minimum and maximum elevations, sub-watershed areas, land use mapping areas within the sub-watershed and number of HRUs varied substantially due to DEM resolutions, and consequently resulted in a considerable variability in estimated daily runoff and sediment yields. It was also observed that, daily runoff values have increased (decreased) on low (high) rainy days respectively with coarser resolution of DEM. The daily sediment yield values from each sub-watershed decreased with coarser resolution of the DEM. The study found that the performance of SWAT model prediction was not influenced much for finer resolution DEMs up to 90 m for estimation of runoff, but it certainly influenced the estimation of sediment yields. The DEMs of TOPO 20 m and CARTO 30 m provided better estimates of sub-watershed areas, runoff and sediment yield values over other DEMs.

  11. Key variables influencing patterns of lava dome growth and collapse

    Science.gov (United States)

    Husain, T.; Elsworth, D.; Voight, B.; Mattioli, G. S.; Jansma, P. E.

    2013-12-01

    Lava domes are conical structures that grow by the infusion of viscous silicic or intermediate composition magma from a central volcanic conduit. Dome growth can be characterized by repeated cycles of growth punctuated by collapse, as the structure becomes oversized for its composite strength. Within these cycles, deformation ranges from slow long term deformation to sudden deep-seated collapses. Collapses may range from small raveling failures to voluminous and fast-moving pyroclastic flows with rapid and long-downslope-reach from the edifice. Infusion rate and magma rheology together with crystallization temperature and volatile content govern the spatial distribution of strength in the structure. Solidification, driven by degassing-induced crystallization of magma leads to the formation of a continuously evolving frictional talus as a hard outer shell. This shell encapsulates the cohesion-dominated soft ductile core. Here we explore the mechanics of lava dome growth and failure using a two-dimensional particle-dynamics model. This meshless model follows the natural evolution of a brittle carapace formed by loss of volatiles and rheological stiffening and avoids difficulties of hour-glassing and mesh-entangelment typical in meshed models. We test the fidelity of the model against existing experimental and observational models of lava dome growth. The particle-dynamics model follows the natural development of dome growth and collapse which is infeasible using simple analytical models. The model provides insight into the triggers that lead to the transition in collapse mechasnism from shallow flank collapse to deep seated sector collapse. Increase in material stiffness due to decrease in infusion rate results in the transition of growth pattern from endogenous to exogenous. The material stiffness and strength are strongly controlled by the magma infusion rate. Increase in infusion rate decreases the time available for degassing induced crystallization leading to a

  12. Hierarchical Bayesian spatial models for predicting multiple forest variables using waveform LiDAR, hyperspectral imagery, and large inventory datasets

    Science.gov (United States)

    Finley, Andrew O.; Banerjee, Sudipto; Cook, Bruce D.; Bradford, John B.

    2013-01-01

    In this paper we detail a multivariate spatial regression model that couples LiDAR, hyperspectral and forest inventory data to predict forest outcome variables at a high spatial resolution. The proposed model is used to analyze forest inventory data collected on the US Forest Service Penobscot Experimental Forest (PEF), ME, USA. In addition to helping meet the regression model's assumptions, results from the PEF analysis suggest that the addition of multivariate spatial random effects improves model fit and predictive ability, compared with two commonly applied modeling approaches. This improvement results from explicitly modeling the covariation among forest outcome variables and spatial dependence among observations through the random effects. Direct application of such multivariate models to even moderately large datasets is often computationally infeasible because of cubic order matrix algorithms involved in estimation. We apply a spatial dimension reduction technique to help overcome this computational hurdle without sacrificing richness in modeling.

  13. Cluster analysis applied to the spatial and temporal variability of monthly rainfall in Mato Grosso do Sul State, Brazil

    Science.gov (United States)

    Teodoro, Paulo Eduardo; de Oliveira-Júnior, José Francisco; da Cunha, Elias Rodrigues; Correa, Caio Cezar Guedes; Torres, Francisco Eduardo; Bacani, Vitor Matheus; Gois, Givanildo; Ribeiro, Larissa Pereira

    2016-04-01

    The State of Mato Grosso do Sul (MS) located in Brazil Midwest is devoid of climatological studies, mainly in the characterization of rainfall regime and producers' meteorological systems and rain inhibitors. This state has different soil and climatic characteristics distributed among three biomes: Cerrado, Atlantic Forest and Pantanal. This study aimed to apply the cluster analysis using Ward's algorithm and identify those meteorological systems that affect the rainfall regime in the biomes. The rainfall data of 32 stations (sites) of the MS State were obtained from the Agência Nacional de Águas (ANA) database, collected from 1954 to 2013. In each of the 384 monthly rainfall temporal series was calculated the average and applied the Ward's algorithm to identify spatial and temporal variability of rainfall. Bartlett's test revealed only in January homogeneous variance at all sites. Run test showed that there was no increase or decrease in trend of monthly rainfall. Cluster analysis identified five rainfall homogeneous regions in the MS State, followed by three seasons (rainy, transitional and dry). The rainy season occurs during the months of November, December, January, February and March. The transitional season ranges between the months of April and May, September and October. The dry season occurs in June, July and August. The groups G1, G4 and G5 are influenced by South Atlantic Subtropical Anticyclone (SASA), Chaco's Low (CL), Bolivia's High (BH), Low Levels Jet (LLJ) and South Atlantic Convergence Zone (SACZ) and Maden-Julian Oscillation (MJO). Group G2 is influenced by Upper Tropospheric Cyclonic Vortex (UTCV) and Front Systems (FS). The group G3 is affected by UTCV, FS and SACZ. The meteorological systems' interaction that operates in each biome and the altitude causes the rainfall spatial and temporal diversity in MS State.

  14. Temporal variability in emission category influence on organic matter aerosols in the Indian region

    Science.gov (United States)

    Cherian, R.; Venkataraman, C.; Ramachandran, S.

    2009-03-01

    The dependence of carbonaceous aerosol properties, like radiation absorption and hygroscopicity, on the emission source of origin motivate this work. The influence of emission categories, including crop residue and forest burning, biofuel combustion, brick kilns, thermal power plants, diesel transport and ``other industry'', is estimated on organic matter (OM) surface concentrations in the Indian ocean region. The approach uses general circulation model predicted OM surface concentrations during a ship cruise, identifies probable source regions for high concentration episodes using the potential source contribution function, and estimates collocated OM emissions resolved by category. Distinct source regions identified, are the Indo-Gangetic Plain during 20-30th January, 1999, and central/south India during 1-11th March, 1999. Contributing emission categories are primarily biofuel combustion (18 Gg) during 20-30th January, but a combination of forest burning (8 Gg), biofuel combustion (7 Gg) and crop residue (5 Gg) during 1-11th March. The magnitude of emission flux rather than spatial extent of an emission category, was seen to increase its influence on the receptor. This approach can be used to investigate seasonal and inter-annual variability in emission category influence on atmospheric pollutants.

  15. Spatial Models for Prediction and Early Warning of Aedes aegypti Proliferation from Data on Climate Change and Variability in Cuba.

    Science.gov (United States)

    Ortiz, Paulo L; Rivero, Alina; Linares, Yzenia; Pérez, Alina; Vázquez, Juan R

    2015-04-01

    Climate variability, the primary expression of climate change, is one of the most important environmental problems affecting human health, particularly vector-borne diseases. Despite research efforts worldwide, there are few studies addressing the use of information on climate variability for prevention and early warning of vector-borne infectious diseases. Show the utility of climate information for vector surveillance by developing spatial models using an entomological indicator and information on predicted climate variability in Cuba to provide early warning of danger of increased risk of dengue transmission. An ecological study was carried out using retrospective and prospective analyses of time series combined with spatial statistics. Several entomological and climatic indicators were considered using complex Bultó indices -1 and -2. Moran's I spatial autocorrelation coefficient specified for a matrix of neighbors with a radius of 20 km, was used to identify the spatial structure. Spatial structure simulation was based on simultaneous autoregressive and conditional autoregressive models; agreement between predicted and observed values for number of Aedes aegypti foci was determined by the concordance index Di and skill factor Bi. Spatial and temporal distributions of populations of Aedes aegypti were obtained. Models for describing, simulating and predicting spatial patterns of Aedes aegypti populations associated with climate variability patterns were put forward. The ranges of climate variability affecting Aedes aegypti populations were identified. Forecast maps were generated for the municipal level. Using the Bultó indices of climate variability, it is possible to construct spatial models for predicting increased Aedes aegypti populations in Cuba. At 20 x 20 km resolution, the models are able to provide warning of potential changes in vector populations in rainy and dry seasons and by month, thus demonstrating the usefulness of climate information for

  16. Quantifying the spatial variability in critical zone architecture through surface mapping and near-surface geophysics

    Science.gov (United States)

    DiBiase, R.; Del Vecchio, J.; Mount, G.; Hayes, J. L.; Comas, X.; Guo, L.; Lin, H.; Zarif, F.; Forsythe, B.; Brantley, S. L.

    2016-12-01

    The composition and structure of Earth's surface and shallow subsurface control the flux of water, solutes, and sediment from hillslopes into rivers. Additionally, bedrock weathering profiles and the stratigraphy of soil and colluvium preserve a record of past surface processes. However, landscapes often exhibit heterogeneity in critical zone architecture that is difficult to capture with remote sensing and costly to characterize through direct measurement in soil pits or drill cores. Here we present results from a multifaceted approach to quantifying spatial variability in critical zone architecture using airborne lidar topography, surface mapping, and a suite of geophysical surveys. We focus on Garner Run, a first order sandstone catchment in the Susquehanna Shale Hills Critical Zone Observatory situated in the valley and ridge province of central Pennsylvania, 80 km southwest of the last glacial maximum ice limit. Results from lidar topographic analysis and detailed mapping of surface cover (e.g., soil versus boulder-mantled) reveal a pattern of relict periglacial landforms and deposits that vary depending on slope position and aspect. Additionally, a drill core taken from an unchanneled valley at the head of Garner Run indicates at least 9 meters of alternating sand- and boulder-rich colluvial fill sourced from adjacent hillslopes, indicating the potential preservation of multiple cycles of periglacial climate conditions. Through the use of shallow geophysical techniques, including cross-valley transects of seismic refraction, multiple frequency ground-penetrating radar (GPR), and electrical resistivity tomography (ERT), we image spatial patterns in subsurface architecture at a range of scales (10-1,000 m), and high spatial resolution (cm). Notably, despite challenging environmental conditions, there is agreement among diverse subsurface methods in highlighting aspect-dependent controls on weathering zone thickness that furthermore can be directly connected to

  17. Spatial and temporal variability of composition of urban effluents in the island of Lesvos, Greece.

    Science.gov (United States)

    Aloupi, M; Angelidis, M O; Scoullos, M

    2000-08-01

    The spatial and temporal variability in the composition of effluents of the coastal town of Mytilene, island of Lesvos, Greece, was investigated in 8 sewers of the town. Differences were found in the quality of effluents between the old and new parts of the town and were attributed mainly to the different design and construction of the sewers, as well as to the occasional discharge of septage into the sewerage network in parts of the town. During summer the population and water consumption increase, leading to partial dilution of the organic load. However, in the same period (July), the concentrations of dissolved Zn and particulate Pb were enriched. The reasons for such an increase are not clear. At present the seasonal metal peaks (Pb and Zn) are attributed to the increased traffic (Pb and Zn) and to increased corrosion under the prevailing weather conditions of the water supply network, which includes a very large number of galvanized storage tanks (Zn).

  18. Spatial variability of hydraulic conductivity of an unconfined sandy aquifer determined by a mini slug test

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Hinsby, Klaus; Christensen, Thomas Højlund;

    1992-01-01

    The spatial variability of the hydraulic conductivity in a sandy aquifer has been determined by a mini slug test method. The hydraulic conductivity (K) of the aquifer has a geometric mean of 5.05 × 10−4 m s−1, and an overall variance of 1n K equal to 0.37 which corresponds quite well to the results...... obtained by two large scale tracer experiments performed in the aquifer. A geological model of the aquifer based on 31 sediment cores, proposed three hydrogeological layers in the aquifer concurrent with the vertical variations observed with respect to hydraulic conductivity. The horizontal correlation...... length of the hydraulic conductivity has been determined for each of the three hydrogeological layers and is found to be small (1–2.5 m). The asymptotic longitudinal dispersivity of the aquifer has been estimated from the variance in hydraulic conductivity and the horizontal correlation length...

  19. Riparian zone hydrology and soil water total organic carbon (TOC: implications for spatial variability and upscaling of lateral riparian TOC exports

    Directory of Open Access Journals (Sweden)

    T. Grabs

    2012-10-01

    Full Text Available Groundwater flowing from hillslopes through riparian (near-stream soils often undergoes chemical transformations that can substantially influence stream water chemistry. We used landscape analysis to predict total organic carbon (TOC concentration profiles and groundwater levels measured in the riparian zone (RZ of a 67 km2 catchment in Sweden. TOC exported laterally from 13 riparian soil profiles was then estimated based on the riparian flow–concentration integration model (RIM. Much of the observed spatial variability of riparian TOC concentrations in this system could be predicted from groundwater levels and the topographic wetness index (TWI. Organic riparian peat soils in forested areas emerged as hotspots exporting large amounts of TOC. These TOC fluxes were subject to considerable temporal variations caused by a combination of variable flow conditions and changing soil water TOC concentrations. Mineral riparian gley soils, on the other hand, were related to rather small TOC export rates and were characterized by relatively time-invariant TOC concentration profiles. Organic and mineral soils in RZs constitute a heterogeneous landscape mosaic that potentially controls much of the spatial variability of stream water TOC. We developed an empirical regression model based on the TWI to move beyond the plot scale and to predict spatially variable riparian TOC concentration profiles for RZs underlain by glacial till.

  20. Spatial sediment variability in a tropical tide dominated estuary: Sources and drivers

    Science.gov (United States)

    Sousa, Silvia H. M.; Ferreira, Paulo A. L.; Martins, Maria V. A.; Siegle, Eduardo; Amaral, Paula G. C.; Figueira, Rubens C. L.; Yamashita, Cintia; Rodrigues, André R.; Mahiques, Michel M.

    2016-12-01

    Surficial sediment composition and spatial variability reflect the dynamics and level of natural and anthropogenic impact in estuarine systems. The aim of this study is to evaluate some key environmental and sedimentary variables, as well as to evaluate the current environmental quality in the tide-dominated Caravelas estuarine system (Brazil). Sixty-five surficial sediment samples were studied for grain size as well as calcium carbonate, total organic carbon, total nitrogen, metals, semi-metals and rare earth elements and for organic matter δ13C. Based on the spatial distribution of these data and summarizing our findings, three sectors can be individualized in the Caravelas estuarine system: i. Barra Velha inlet; ii. the main channel of the Caravelas estuary, and iii. the channel interconnecting Caravelas and Nova Viçosa estuaries. In the inlet the sedimentary organic matter is provided essentially by marine sources, which corroborates the small continental input. Freshwater dissolved organic carbon and particulate organic carbon occur in the interconnecting channel, proving the occurrence of the residual transport towards the Caravelas estuary, with continental contribution towards Caravelas River. The geochemical fingerprint indicates that the Barreiras Group, composed by Neogene terrigenous deposits, located west of the study area, as an important source of terrigenous material to the entire Caravelas estuary system. The higher values of heavy rare earth elements (between 20 and 30 mg kg-1) in the northern sector of the study area may be related to the high degree of chemical weathering in magmatic or metamorphic rocks, which occur to the north of the study area.

  1. Spatial modelling of marine organisms in Forsmark and Oskarshamn. Including calculation of physical predictor variables

    Energy Technology Data Exchange (ETDEWEB)

    Carlen, Ida; Nikolopoulos, Anna; Isaeus, Martin (AquaBiota Water Research, Stockholm (SE))

    2007-06-15

    GIS grids (maps) of marine parameters were created using point data from previous site investigations in the Forsmark and Oskarshamn areas. The proportion of global radiation reaching the sea bottom in Forsmark and Oskarshamn was calculated in ArcView, using Secchi depth measurements and the digital elevation models for the respective area. The number of days per year when the incoming light exceeds 5 MJ/m2 at the bottom was then calculated using the result of the previous calculations together with measured global radiation. Existing modelled grid-point data on bottom and pelagic temperature for Forsmark were interpolated to create surface covering grids. Bottom and pelagic temperature grids for Oskarshamn were calculated using point measurements to achieve yearly averages for a few points and then using regressions with existing grids to create new maps. Phytoplankton primary production in Forsmark was calculated using point measurements of chlorophyll and irradiance, and a regression with a modelled grid of Secchi depth. Distribution of biomass of macrophyte communities in Forsmark and Oskarshamn was calculated using spatial modelling in GRASP, based on field data from previous surveys. Physical parameters such as those described above were used as predictor variables. Distribution of biomass of different functional groups of fish in Forsmark was calculated using spatial modelling based on previous surveys and with predictor variables such as physical parameters and results from macrophyte modelling. All results are presented as maps in the report. The quality of the modelled predictions varies as a consequence of the quality and amount of the input data, the ecology and knowledge of the predicted phenomena, and by the modelling technique used. A substantial part of the variation is not described by the models, which should be expected for biological modelling. Therefore, the resulting grids should be used with caution and with this uncertainty kept in mind. All

  2. Simulating maize yield and bomass with spatial variability of soil field capacity

    Science.gov (United States)

    Ma, Liwang; Ahuja, Lajpat; Trout, Thomas; Nolan, Bernard T.; Malone, Robert W.

    2015-01-01

    Spatial variability in field soil properties is a challenge for system modelers who use single representative values, such as means, for model inputs, rather than their distributions. In this study, the root zone water quality model (RZWQM2) was first calibrated for 4 yr of maize (Zea mays L.) data at six irrigation levels in northern Colorado and then used to study spatial variability of soil field capacity (FC) estimated in 96 plots on maize yield and biomass. The best results were obtained when the crop parameters were fitted along with FCs, with a root mean squared error (RMSE) of 354 kg ha–1 for yield and 1202 kg ha–1 for biomass. When running the model using each of the 96 sets of field-estimated FC values, instead of calibrating FCs, the average simulated yield and biomass from the 96 runs were close to measured values with a RMSE of 376 kg ha–1 for yield and 1504 kg ha–1 for biomass. When an average of the 96 FC values for each soil layer was used, simulated yield and biomass were also acceptable with a RMSE of 438 kg ha–1 for yield and 1627 kg ha–1 for biomass. Therefore, when there are large numbers of FC measurements, an average value might be sufficient for model inputs. However, when the ranges of FC measurements were known for each soil layer, a sampled distribution of FCs using the Latin hypercube sampling (LHS) might be used for model inputs.

  3. Spatial and temporal variability in denudation across the Bolivian Andes from multiple geochronometers

    Science.gov (United States)

    Insel, Nadja; Ehlers, Todd A.; Schaller, Mirjam; Barnes, Jason B.; Tawackoli, Sohrab; Poulsen, Christopher J.

    2010-10-01

    We quantify spatial and temporal variations in denudation rates across the central Andean fold-thrust belt in Bolivia with particular focus on the Holocene. Measured and predicted 10Be cosmogenic radionuclide (CRN) concentrations in river sediments are used to (1) calculate catchment-averaged denudation rates from 17 basins across two transects at different latitudes, and (2) evaluate the sensitivity of Holocene climate change on the denudation history recorded by the CRN data. Estimated denudation rates vary by two orders of magnitude from 0.04 to 1.93 mm yr - 1 with mean values of 0.40 ± 0.29 mm yr - 1 in northern Bolivia and 0.51 ± 0.50 mm yr - 1 in the south. Results demonstrate no statistically significant correlation between denudation rates and morphological parameters such as relief, slope or drainage basin size. In addition, the CRN-derived denudation rates do not reflect present-day latitudinal variations in precipitation. Comparison to ˜ 130 previously published denudation rates calculated over long (thermochronology-derived; > 10 6 yrs), medium (CRN-derived; 10 2-10 4 yrs), and short timescales (sediment flux-derived; 10 1 yrs) indicate temporal variations in denudation rates that increase between 0 and 200% over the last ˜ 5 ka. CRN modeling results suggest that the CRN-derived denudation rates may not be fully adjusted to wetter climate conditions recorded in the central Andes since the mid-Holocene. We conclude that large spatial variability in CRN denudation may be due to local variations in tectonics (e.g. faulting), while large temporal variability in denudation may be due to temporal variations in climate.

  4. Healthcare environments and spatial variability of healthcare associated infection risk: cross-sectional surveys.

    Directory of Open Access Journals (Sweden)

    Jean Gaudart

    Full Text Available Prevalence of healthcare associated infections remains high in patients in intensive care units (ICU, estimated at 23.4% in 2011. It is important to reduce the overall risk while minimizing the cost and disruption to service provision by targeted infection control interventions. The aim of this study was to develop a monitoring tool to analyze the spatial variability of bacteriological contamination within the healthcare environment to assist in the planning of interventions. Within three cross-sectional surveys, in two ICU wards, air and surface samples from different heights and locations were analyzed. Surface sampling was carried out with tryptic Soy Agar contact plates and Total Viable Counts (TVC were calculated at 48 hrs (incubation at 37 °C. TVCs were analyzed using Poisson Generalized Additive Mixed Model for surface type analysis, and for spatial analysis. Through three cross-sectional survey, 370 samples were collected. Contamination varied from place-to-place, height-to-height, and by surface type. Hard-to-reach surfaces, such as bed wheels and floor area under beds, were generally more contaminated, but the height level at which maximal TVCs were found changed between cross-sectional surveys. Bedside locations and bed occupation were risk factors for contamination. Air sampling identified clusters of contamination around the nursing station and surface sampling identified contamination clusters at numerous bed locations. By investigating dynamic hospital wards, the methodology employed in this study will be useful to monitor contamination variability within the healthcare environment and should help to assist in the planning of interventions.

  5. Spatial variability of chlorophyll and nitrogen content of rice from hyperspectral imagery

    Science.gov (United States)

    Moharana, Shreedevi; Dutta, Subashisa

    2016-12-01

    Chlorophyll and nitrogen are the most essential parameters for paddy crop growth. Spectroradiometric measurements were collected at canopy level during critical growth period of rice. Chemical analysis was performed to quantify the total leaf content. By exploiting the ground based measurements, regression models were established for chlorophyll and nitrogen aimed indices with their corresponding crop growth variables. Vegetation index models were developed for mapping these parameters from Hyperion imagery in an agriculture system. It was inferred that the present Simple Ratio (SR) and Leaf Nitrogen Concentration (LNC) indices, which followed a linear and nonlinear relationship respectively, were completely different from published Tian et al. (2011). The nitrogen content varied widely from 1 to 4% and only 2 to 3% for paddy crop using present modified index models and Tian et al. (2011) respectively. The modified LNC index model performed better than the established Tian et al. (2011) model as far as estimated nitrogen content from Hyperion imagery was concerned. Furthermore, within the observed chlorophyll range obtained from the studied rice varieties grown in the rice agriculture system, the index models (LNC, OASVI, Gitelson, mSR and MTCI) performed well in the spatial distribution of rice chlorophyll content from Hyperion imagery. Spatial distribution of total chlorophyll content varied widely from 1.77 to 5.81 mg/g (LNC), 3.0 to 13 mg/g (OASVI), 0.5 to 10.43 mg/g (Gitelson), 2.18 to 10.61 mg/g (mSR) and 2.90 to 5.40 mg/g (MTCI). The spatial information of these parameters will help in proper nutrient management, yield forecasting, and will serve as inputs for crop growth and forecasting models for a precision rice agriculture system.

  6. Spatial distribution and variability of carbon storage in different sympodial bamboo species in China.

    Science.gov (United States)

    Teng, Jiangnan; Xiang, Tingting; Huang, Zhangting; Wu, Jiasen; Jiang, Peikun; Meng, Cifu; Li, Yongfu; Fuhrmann, Jeffry J

    2016-03-01

    Selection of tree species is potentially an important management decision for increasing carbon storage in forest ecosystems. This study investigated and compared spatial distribution and variability of carbon storage in 8 sympodial bamboo species in China. The results of this study showed that average carbon densities (CDs) in the different organs decreased in the order: culms (0.4754 g g(-1)) > below-ground (0.4701 g g(-1)) > branches (0.4662 g g(-1)) > leaves (0.4420 g g(-1)). Spatial distribution of carbon storage (CS) on an area basis in the biomass of 8 sympodial bamboo species was in the order: culms (17.4-77.1%) > below-ground (10.6-71.7%) > branches (3.8-11.6%) > leaves (0.9-5.1%). Total CSs in the sympodial bamboo ecosystems ranged from 103.6 Mg C ha(-1) in Bambusa textilis McClure stand to 194.2 Mg C ha(-1) in Dendrocalamus giganteus Munro stand. Spatial distribution of CSs in 8 sympodial bamboo ecosystems decreased in the order: soil (68.0-83.5%) > vegetation (16.8-31.1%) > litter (0.3-1.7%). Total current CS and biomass carbon sequestration rate in the sympodial bamboo stands studied in China is 93.184 × 10(6) Mg C ha(-1) and 8.573 × 10(6) Mg C yr(-1), respectively. The sympodial bamboos had a greater CSs and higher carbon sequestration rates relative to other bamboo species. Sympodial bamboos can play an important role in improving climate and economy in the widely cultivated areas of the world.

  7. Intra-community spatial variability of particulate matter size distributions in southern California/Los Angeles

    Directory of Open Access Journals (Sweden)

    M. Krudysz

    2008-05-01

    Full Text Available Ultrafine particle (UFP number concentrations vary significantly on small spatial and temporal scales due to their short atmospheric lifetimes and multiplicity of sources. To determine UFP exposure gradients within a community, simultaneous particle number concentration measurements at a network of sites are necessary. Concurrent particle size distribution measurements aid in identifying UFP sources, while providing data to investigate local scale effects of both photochemical and physical processes on UFP. From April to December 2007, we monitored particle size distributions at 13 sites within 350 m to 11 km of each other in the vicinity of the Ports of Los Angeles and Long Beach using Scanning Mobility Particle Sizers (SMPS. Typically, three SMPS units were simultaneously deployed and rotated among sites at 1–2 week intervals. Total particle number concentration measurements were conducted continuously at all sites. Seasonal and diurnal size distribution patterns are complex, highly dependent on local meteorology, nearby PM sources, and times of day, and cannot be generalized over the study area nor inferred from one or two sampling locations. Spatial variation in particle number size distributions was assessed by calculating the coefficient of divergence (COD and correlation coefficients (r between site pairs. Results show an overall inverse relationship between particle size and CODs, implying that number concentrations of smaller particles (<40 nm differ from site to site, whereas larger particles tend to have similar concentrations at various sampling locations. In addition, variations in r values as a function of particle size are not necessarily consistent with corresponding COD values, indicating that using results from correlation analysis alone may not accurately assess spatial variability.

  8. The influence of row width and seed spacing on uniformity of plant spatial distributions

    DEFF Research Database (Denmark)

    Griepentrog, Hans W.; Olsen, Jannie Maj; Weiner, Jacob

    2009-01-01

    Crop performance and weed suppression increase with increasing crop spatial uniformity. We use spatial pattern simulations and field experiments to show the current state-of-the-art for spatial uniformity for different seeding technologies. We use Morisita's Index to quantify how changes in row...... width and evenness of spacing within rows influences two-dimensional spatial quality. The results can be used to define new requirements for improved seeding technologies to achieve higher benefits in sustainable crop production systems. In general it can be concluded that more even plant distributions...

  9. Spatial variability of throughfall in a Chinese Pine (Pinus tabulaeformis) plantation in northern China

    Institute of Scientific and Technical Information of China (English)

    ZHAN Weiqing; ZHANG Zhiqiang; WU Jun; XIAO Jinqiang

    2007-01-01

    The interception of rainfall by vegetation and the subsequent evaporation of intercepted water from the canopy surface play an important role in hydrological processes,and the water and energy balance of forest ecosystems.Spatial variability of interception has different effects on water yield from watersheds located in different climatic and biome regions.In order to explain the spatial patterns of interception,we adopted grid-sampling method to install rain-gauges to measure throughfall.Results show that the coefficient of variation (Cv) of throughfall tends to decline as rain intensity increases.After the canopy is saturated,Cv of throughfall remained at a constant value,which is close to the Cv of the canopy leaf area index (LAI) value 0.18.Thus,the Cv of LAI is regarded as the extremum of that of throughfall.Because of the special characteristic of Chinese pine (Pinus tabulaeformis),and the lower droopy branches,negative values for interception account for only 13% of the total samples.Furthermore,the max is above 70% of gross rainfall.

  10. [Spatial variability and management zone of soil major nutrients in tobacco fields in Qiannan mountainous region].

    Science.gov (United States)

    Wu, De-Chuan; Luo, Hong-Xiang; Song, Ze-Min; Guo, Guang-Dong; Chen, Yong-An; Li, Yu-Xiang; Jiang, Yu-Ping; Li, Zhang-Hai

    2014-06-01

    Spatial variability and management zone of soil major nutrients in tobacco fields in Qian-nan mountainous region were analyzed using geostatistics and fuzzy c-mean algorithm. Results indicated that the level of soil organic matter (OM) was moderate, and alkalytic nitrogen (AN), available phosphorus (AP) and available potassium (AK) were rich according to tobacco soil nutrient classification standards. Coefficients of variation (CV) of OM, AN, AP and AK were moderate. Contents of OM, AN, AP and AK fitted log-normal distributions. Correlation analysis showed moderate correlations between OM and AN, AP and AK. OM and AN were best described by Gaussian semivariogram models, while AP and AK were described by exponential models. The four nutrients displayed moderate spatial autocorrelation. There were significant differences among lag distances of four soil nutrients. OM, AN, AP and AK in the majority of studied regions varied at moderate to very rich levels, and deficiencies of OM, AN, AP and AK only accounted for 0.93%, 0.53%, 0.24% and 7.91% of the total studied region, respectively. Based on the results, the studied region was divided into two management zones (MZ), namely MZ1 and MZ2, accounting for 69. 8% and 30. 2% of the studied region respectively. The soil levels of OM, AN, AP and AK in MZ1 were significantly lower than those in MZ2 (P < 0.01).

  11. Comparison of stochastic and deterministic methods for mapping groundwater level spatial variability in sparsely monitored basins.

    Science.gov (United States)

    Varouchakis, Epsilon A; Hristopulos, D T

    2013-01-01

    In sparsely monitored basins, accurate mapping of the spatial variability of groundwater level requires the interpolation of scattered data. This paper presents a comparison of deterministic interpolation methods, i.e. inverse distance weight (IDW) and minimum curvature (MC), with stochastic methods, i.e. ordinary kriging (OK), universal kriging (UK) and kriging with Delaunay triangulation (DK). The study area is the Mires Basin of Mesara Valley in Crete (Greece). This sparsely sampled basin has limited groundwater resources which are vital for the island's economy; spatial variations of the groundwater level are important for developing management and monitoring strategies. We evaluate the performance of the interpolation methods with respect to different statistical measures. The Spartan variogram family is applied for the first time to hydrological data and is shown to be optimal with respect to stochastic interpolation of this dataset. The three stochastic methods (OK, DK and UK) perform overall better than the deterministic counterparts (IDW and MC). DK, which is herein for the first time applied to hydrological data, yields the most accurate cross-validation estimate for the lowest value in the dataset. OK and UK lead to smooth isolevel contours, whilst DK and IDW generate more edges. The stochastic methods deliver estimates of prediction uncertainty which becomes highest near the southeastern border of the basin.

  12. Spatial variability in the diagnosis of nutritional status in the papaya

    Directory of Open Access Journals (Sweden)

    Julião Soares de Sousa Lima

    2016-06-01

    Full Text Available ABSTRACT Leaf analysis is widely used to study the nutritional status of plants, based on the fact of there being a direct correlation between rate of growth and the nutrient levels in leaf tissue. This study was carried out on a commercial crop of Golden THB papaya, in the north of the State of Espirito Santo, Brazil, to determine the spatial variability of nutrients in the petiole of leaf samples collected when carrying out sexing in a regular grid of 129 georeferenced points. Harvesting was carried out manually 270-365 days after transplanting. All the characteristics displayed a strong spatial dependence, the spherical and exponential semivariograms being adjusted for the data. The greatest and smallest ranges were found for the micronutrients Mn and Zn respectively. Mean productivity was considered to be low at 13.6 Mg ha-1. Geostatistical analysis of the data aided in the preparation of thematic maps showing the different areas of productivity and foliar application of fertiliser in the papaya. However, the largest regions in the area were displayed by those classes which included the mean value for an attribute, indicating the use of the mean values in the recommendation of foliar fertilisation, with the exception of P and K.

  13. Spatial and temporal variability of microbes in selected soils at the Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Angerer, J.P.; Winkel, V.K.; Ostler, W.K.; Hall, P.F.

    1993-12-31

    Large areas encompassing almost 800 hectares on the Nevada Test Site, Nellis Air Force Range and the Tonopah Test Range are contaminated with plutonium. Decontamination of plutonium from these sites may involve removal of plants and almost 370,000 cubic meters of soil. The soil may be subjected to a series of processes to remove plutonium. After decontamination, the soils will be returned to the site and revegetated. There is a paucity of information on the spatial and temporal distribution of microbes in soils of the Mojave and Great Basin Deserts. Therefore, this study was initiated to determine the biomass and diversity of microbes in soils prior to decontamination. Soils were collected to a depth of 10 cm along each of five randomly located 30-m transects at each of four sites. To ascertain spatial differences, soils were collected from beneath major shrubs and from associated interspaces. Soils were collected every three to four months to determine temporal (seasonal) differences in microbial parameters. Soils from beneath shrubs generally had greater active fungi and bacteria, and greater non-amended respiration than soils from interspaces. Temporal variability also was found; total and active fungi, and non-amended respiration were correlated with soil moisture at the time of sampling. Information from this study will aid in determining the effects of plutonium decontamination on soil microorganisms, and what measures, if any, will be required to restore microbial populations during revegetation of these sites.

  14. Spatial variability of herbicide mobilisation and transport at catchment scale: insights from a field experiment

    Directory of Open Access Journals (Sweden)

    T. Doppler

    2012-07-01

    additional shortcuts to the stream.

    Although fast flow processes such as overland and macropore flow reduce the influence of the herbicide's chemical properties on transport due to short travel times, sorption properties influenced the herbicide transfer from ponding overland flow to tile drains (macropore flow. However, no influence of sorption was observed during the mobilisation of the herbicides from soil to overland flow. These observations on the role of herbicide properties contradict previous findings to some degree. Furthermore, they demonstrate that valuable insight can be gained by making spatially detailed observations along the flow paths.

  15. Spatial variability of herbicide mobilisation and transport at catchment scale: insights from a field experiment

    Directory of Open Access Journals (Sweden)

    T. Doppler

    2012-02-01

    the stream via macropores and tile drains. Manholes of the drainage system and catch basins for road and farmyard runoff acted as additional shortcuts to the stream.

    Although fast flow processes like overland and macropore flow reduce the influence of herbicide properties due to short travel times, sorption properties influenced the herbicide transfer from ponding overland flow to tile drains (macropore flow. However, no influence of sorption was observed during the mobilisation of the herbicides from soil to overland flow. These two observations on the role of herbicide properties contradict, to some degrees, previous findings. They demonstrate that valuable insight can be gained by spatially detailed observations along the flow paths.

  16. Right-Hemisphere (Spatial? Acalculia and the Influence of Neglect

    Directory of Open Access Journals (Sweden)

    Silvia eBenavides-Varela

    2014-08-01

    Full Text Available The present study aimed at exploring basic number and calculation abilities in right-hemisphere damaged patients (RHD, focusing primarily on one-digit orally presented tasks, which do not require explicit visuo-spatial abilities. Twenty-four non mentally-deteriorated RHD patients (12 with clinical neglect (RHDN+, 12 without clinical neglect (RHDN-, and 12 healthy controls were included in the study. Participants were administered an ad hoc numerical battery assessing abilities such as counting, number magnitude comparison, writing and reading Arabic numerals and mental calculation, among others. Significant differences emerged among healthy controls and both the RHDN+ group and the RHDN- group, suggesting that the mathematical impairment of RHD patients does not necessarily correspond to the presence of left-neglect. A detailed analysis of the sub-tests of the battery evidenced expected differences among RHDN+ patients, RHDN- patients, and controls in writing and reading Arabic numerals. Crucially, differences between RHDN+ patients and controls were also found in tasks such as mental subtraction and mental multiplication. The present findings thus suggest that unilateral right hemisphere lesions may produce specific representational deficits that affect simple mental calculation, and not only the spatial arrangement of multi-digit written numbers as previously thought.

  17. Spatial and temporal variability of rainfall and their effects on hydrological response in urban areas – a review

    Directory of Open Access Journals (Sweden)

    E. Cristiano

    2017-07-01

    Full Text Available In urban areas, hydrological processes are characterized by high variability in space and time, making them sensitive to small-scale temporal and spatial rainfall variability. In the last decades new instruments, techniques, and methods have been developed to capture rainfall and hydrological processes at high resolution. Weather radars have been introduced to estimate high spatial and temporal rainfall variability. At the same time, new models have been proposed to reproduce hydrological response, based on small-scale representation of urban catchment spatial variability. Despite these efforts, interactions between rainfall variability, catchment heterogeneity, and hydrological response remain poorly understood. This paper presents a review of our current understanding of hydrological processes in urban environments as reported in the literature, focusing on their spatial and temporal variability aspects. We review recent findings on the effects of rainfall variability on hydrological response and identify gaps where knowledge needs to be further developed to improve our understanding of and capability to predict urban hydrological response.

  18. Spatial and temporal variability of throughfall at the plot scale in the Italian pre-Alps

    Science.gov (United States)

    Zuecco, Giulia; Oliviero, Omar; Penna, Daniele; van Meerveld, Ilja; Hopp, Luisa; Dalla Fontana, Giancarlo; Borga, Marco

    2014-05-01

    The redistribution of rainfall in the forest canopy affects many hydrological and biogeochemical processes. Although many studies have focused on the quantification of throughfall, the controls on the spatial variability and temporal persistence of throughfall patterns are still poorly understood. This study therefore aims to: i) quantify throughfall at the plot scale for a pre-Alpine forested hillslope in Italy; ii) assess measurement differences between two different throughfall collectors; and iii) investigate the spatial and temporal variability of throughfall patterns and their relation to canopy characteristics. Throughfall measurements were taken from April to November 2013 in a 500 m2 experimental plot on the hillslope of a small and densely forested catchment (Ressi) in the Italian pre-Alps. The main tree species in the plot are beech and chestnut. The median Diameter at Breast Height of the trees in the plot is 4 cm (range 1-61 cm). Two different rainfall collectors were used: buckets (collecting area: 556 cm2; capacity: 162 mm) and rain gauges (collecting area: 47 cm2; capacity: 80 mm). Fifty buckets were randomly distributed in the plot, while 40 rain gauges were installed on a regular grid (spacing 2.5x3 m). One bucket and one rain gauge collected rainfall in a nearby open area. A tipping bucket rain gauge was installed in the open area as well. Rainfall and throughfall were measured for 20 events by manually emptying the collectors and measuring the volume of water in the collectors. Canopy openness was determined by taking pictures with a 24 mm lens upward from each sampler and selecting thresholds between dark (canopy) and light (sky) areas. For the measured events, rainfall in the open area ranged from 4 mm to 122 mm. Plot-average throughfall for these events ranged between 69%-94% and 68%-100% of precipitation for the buckets and rain gauges, respectively. Throughfall measured by the two types of samplers was statistically similar (Mann

  19. Estimating range of influence in case of missing spatial data

    DEFF Research Database (Denmark)

    Bihrmann, Kristine; Ersbøll, Annette Kjær

    2015-01-01

    the estimated range of influence is affected when 1) the outcome is only observed at some of a given set of locations, and 2) multiple imputation is used to impute the outcome at the non-observed locations. METHODS: The study was based on the simulation of missing outcomes in a complete data set. The range...

  20. Spatial variability of drinking water iodine in Denmark: implications for future policy making

    Science.gov (United States)

    Voutchkova, Denitza; Ernstsen, Vibeke; Kristiansen, Søren; Hansen, Birgitte

    2014-05-01

    The iodine-an essential component of human thyroid hormones-is provided to our organisms naturally from the food and water and/or is added artificially to the diet. One of the major natural contributors to the dietary iodine intake in Denmark is the drinking water. Both insufficient or excessive iodine intake can cause health problems however the attention falls mainly on the iodine deficiency (ID). Denmark is classified to have mild ID, which is based on sub-national data only. On a bigger scale, in Europe, about 40% of the general population is estimated to suffer from insufficient iodine intake (based on recent update on the iodine status worldwide). A mandatory addition of iodine to the salt was introduced in 2001 in Denmark to address the population's mild deficiency. One of the components of the Danish monitoring program investigating the effect of the salt iodizing (DanThyr) was based on the geographical variation of drinking water iodine levels. More specifically, the location of the two DanThyr cohort studies was chosen to reflect the low concentrations in the western part of Denmark and higher concentration in the eastern part. However, the knowledge about the spatial variability of iodine in Danish ground- and drinking water at that time was quite limited and misrepresentation of the natural variability is suspected. The presented sampling campaign was completed in 2013, and includes 144 waterworks with annual abstraction of about 175 mio m3 groundwater (~45% of the total groundwater abstraction by all active public and private Danish waterworks). The results show a surprisingly complex spatial pattern concerning both the iodine concentrations and speciation. By estimating the dietary iodine intake from water and comparing it to the WHO recommendations, it becomes possible to recognize potentially deficient/excessive geographical areas. Moreover, it is demonstrated that drinking water iodine levels (major dietary iodine contributor in Denmark) can be

  1. The geovisualisation window of the temporal and spatial variability for Volunteered Geographic Information activities

    Science.gov (United States)

    Medynska-Gulij, Beata; Myszczuk, Miłosz

    2012-11-01

    This study presents an attempt to design geographical visualisation tools that allow to tackle the immensity of spatial data provided by Volunteered Geographic Information (VGI), both in terms of temporal and spatial aspects. In accordance with the assumptions made at the conceptual stage, the final action was the implementation of the window entitled ‘Geovisualisation of the Panoramio.com Activities in District of Poznan 2011’ into the web browser. The concept has been based on a division of the geovisualisation window into three panels, of which the most important - in order to capture spatial variability - have statistical maps at the general level (dot map and choropleth map), while at the detailed level - a dot map on a topographic reference map or tourist map. For two ranges, temporal variability is presented by graphs, while a review of attributes of individual activities of the social website in question is set forward in the table panel. The element that visually interlinks all of the panels is the emphasised individual activity. Problemem podjetym w tych badaniach stało sie wykorzystanie metod z nurtu geograficznej wizualizacji do wskazania cech fenomenu VGI w zakresie zmiennosci czasowo-przestrzennej. Zgodnie z załozeniami poczynionymi w etapie koncepcyjnym finalnym działaniem stało sie zaimplementowanie do przegladarki internetowej okna pod tytułem: ”Geowizualizacja aktywnosci społecznosci Panoramio.com w powiecie poznanskim w 2011 roku”. Koncepcja została oparta na podziale okna geowizualizacji na trzy panele, z których najwazniejsze znaczenie dla uchwycenia zmiennosci przestrzennej na poziomie ogólnym ma kartogram, natomiast na poziomie szczegółowym mapa kropkowa wyswietlana na podkładzie mapy topograficznej lub turystycznej. Zmiennosc czasowa w dwóch zakresach prezentuja wykresy, a przeglad atrybutów poszczególnych aktywnosci prezentowanego portalu społecznosciowego zapewnia tabela. Elementem spajajacym wizualnie wszystkie

  2. Terrestrial and oceanic influence on spatial hydrochemistry and trophic status in subtropical marine near-shore waters.

    Science.gov (United States)

    Morales-Ojeda, Sara M; Herrera-Silveira, Jorge A; Montero, Jorge

    2010-12-01

    Terrestrial and oceanic influences like groundwater discharges and/or oceanic upwelling define the hydrochemical and biological characteristics of near-shore regions. In karst environments, such as the Yucatan Peninsula (SE Mexico), the balance between these two influences on spatial and temporal scales is poorly understood. This study focused on near-shore waters within 200 m offshore along the Yucatan coast. The trophic status and hydrochemical zones of the study area were determined as a function of physical and nutrient data collected from 2005 to 2006. The main terrestrial influence was groundwater discharge, while the most important marine influence was related to seasonal changes in water turbulence. Spatial differences (p Dzilam exhibited the maximum influence of groundwater discharge estimated by salinity dissolution (δ). During the rainy and "nortes" seasons, there is a balance between oceanic and terrestrial influences. The trophic status measured using the TRIX index, indicated that near-shore waters were mainly oligo-mesotrophic; with a meso-eutrophic status in areas with documented anthropogenic impacts. Four hydrological zones were identified by a Canonical Variate Analysis (CVA) using salinity, NO(2)(-), k and NH(4)(+) as the main discriminating variables. Zones I and II showed almost pristine conditions, with well-balanced terrestrial-oceanic influences. In Zone III, terrestrial influences such as groundwater discharges and inland pollution suggesting human impacts were dominant respect to the effects of oceanic influences like upwelling and sediment resuspension caused by winds and oceanic currents. Zone IV received enhanced groundwater and associated nutrients. Anthropogenic activities have led to ecosystem degradation but the speed at which this occurs depends on local and regional characteristics. Therefore, this study has defined those characteristics so as to enact better management policies.

  3. Distribution and variability of redox zones controlling spatial variability of arsenic in the Mississippi River Valley alluvial aquifer, southeastern Arkansas

    Science.gov (United States)

    Sharif, M.U.; Davis, R.K.; Steele, K.F.; Kim, B.; Hays, P.D.; Kresse, T.M.; Fazio, J.A.

    2008-01-01

    . Spatial variability of gypsum solubility and simultaneous SO42- reduction with co-precipitation of As and sulfide is an important limiting process controlling the concentration of As in groundwater in the area. ?? 2008 Elsevier B.V. All rights reserved.

  4. Spatial variability of soil moisture regimes at different scales: implications in the context of precision agriculture.

    Science.gov (United States)

    Voltz, M

    1997-01-01

    Precision agriculture is based on the concept of soil-specific management, which aims to adapt management within a field according to specific site conditions in order to maximize production and minimize environmental damage. This paper examines how the nature and sources of variation in soil moisture regimes affect our ability to simulate soil water behaviour within a field with adequate precision in order to advise optimal soil-specific management. Field examples of variation in soil moisture regimes are described to illustrate the difficulties involved. A discussion identifies three main points. First, it is recognized that the current modelling approaches to soil moisture regimes do not sufficiently account for local heterogeneities in soil and crop characteristics such as soil morphology and rooting patterns. Second, the estimation of within-field variation of soil hydraulic properties is difficult because of large short-range variation of the properties and general lack of observed data; one way to overcome this problem is to seek new measurement techniques or to find easy-to-measure auxiliary variables spatially correlated to the variables of interest. Last, as pollution impacts often become noticeable to society at scales larger than the scale of agricultural management, hydrological modelling can serve for linking both scales and advising agricultural practices that minimize undesirable pollution effects.

  5. Comparative Study on Response Surfaces for Reliability Analysis of Spatially Variable Soil Slope

    Institute of Scientific and Technical Information of China (English)

    李亮; 褚雪松

    2015-01-01

    This paper focuses on the performance of the second-order polynomial-based response surfaces on the reliability of spatially variable soil slope. A single response surface constructed to approximate the slope system failure performance functionG(X) (called single RS) and multiple response surfaces constructed on finite number of slip surfaces (called multiple RS) are developed, respectively. Single RS and multiple RS are applied to evaluate the system failure probability pf for a cohesive soil slope together with Monte Carlo simulation (MCS). It is found thatpf calculated by single RS deviates significantly from that obtained by searching a large number of potential slip surfaces, and this deviation becomes insignificant with the decrease of the number of random variables or the increase of the scale of fluctuation. In other words, single RS cannot approximateG(X) with reasonable accuracy. The value ofpf from multiple response surfaces fits well with that obtained by searching a large number of potential slip surfaces. That is, multiple RS can estimateG(X) with reasonable accuracy.

  6. Evolution of dispersal in spatially and temporally variable environments: The importance of life cycles.

    Science.gov (United States)

    Massol, François; Débarre, Florence

    2015-07-01

    Spatiotemporal variability of the environment is bound to affect the evolution of dispersal, and yet model predictions strongly differ on this particular effect. Recent studies on the evolution of local adaptation have shown that the life cycle chosen to model the selective effects of spatiotemporal variability of the environment is a critical factor determining evolutionary outcomes. Here, we investigate the effect of the order of events in the life cycle on the evolution of unconditional dispersal in a spatially heterogeneous, temporally varying landscape. Our results show that the occurrence of intermediate singular strategies and disruptive selection are conditioned by the temporal autocorrelation of the environment and by the life cycle. Life cycles with dispersal of adults versus dispersal of juveniles, local versus global density regulation, give radically different evolutionary outcomes that include selection for total philopatry, evolutionary bistability, selection for intermediate stable states, and evolutionary branching points. Our results highlight the importance of accounting for life-cycle specifics when predicting the effects of the environment on evolutionarily selected trait values, such as dispersal, as well as the need to check the robustness of model conclusions against modifications of the life cycle. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  7. Spatial Variability in Surface Elevation Changes of Central-West Greenland Outlet Glaciers

    Science.gov (United States)

    Felikson, D.; Catania, G. A.; Kjaer, K. H.; Korsgaard, N. J.; Stearns, L. A.; Nash, J. D.; Shroyer, E.; Sutherland, D.; Walker, R. T.

    2014-12-01

    The mass balance of the Greenland ice sheet (GrIS) is, in part, governed by the dynamics of ocean-terminating glaciers. GRACE data reveal that along the central-west coast of the GrIS, overall ice loss has been accelerating since 2007. However, we do not know the physical processes controlling the loss here, and the changes observed are not uniform in this region; several glaciers have gone through periods of slow-down in the recent past. To address these uncertainties, we have performed ~30-year DEM differences of outlet glaciers in the region. Present-day DEMs have been created from WorldView-1 and -2 (WV) stereo imagery acquired in 2012 and 2013 using the AMES Stereo Pipeline. A 1985 DEM was created from a Greenland aerial photo survey. The DEM differences between the present-day WV DEMs and the 1985 aerial photo DEM show clearly that spatial variability in the surface elevation and terminus position changes of the glaciers in the region has been ongoing for the last ~30 years. We examine this variability in the context of ocean temperature and surface mass balance estimates to yield further insight into the external controls on these glaciers.

  8. Drought intensity and spatial variability in Gabes Watershed, south-eastern Tunisia

    Directory of Open Access Journals (Sweden)

    Jemai Sabrine

    2016-12-01

    Full Text Available Chronological series of monthly and annual precipitation data recorded in Gabes Watershed, south-eastern Tunisia, were analyzed. The study is based on the standardized precipitation index (SPI values, computed for 10 rainfall stations over the period 1987–2012, which corresponds to an observatory period of 25 hydrologic years (from September to August. The results obtained show a great variability in SPI values. The historical evolution of the SPI made it possible to define the periods of excess and deficit, corresponding to wet and dry periods respectively. The wet years were found to be 1989–1990, 1995–1996 and 2006–2007 while the dry years were 1987–1988, 1996–1997, 2000–2001, 2001–2002, 2007–2008, 2008–2009 and 2009–2010. This clearly shows alternating wet and dry periods, but with drought episodes taking prevalence over rainy fronts throughout the study period. Indeed, a high tendency towards a drop in precipitation and important sequences of drought were observed. Spatial variability of drought throughout Gabes Watershed was examined by geostatistical analysis of SPI, as drought and rainfall distribution vary with latitude, longitude, topography and proximity to the Mediterranean Sea. The results obtained showed that, compared to coastal and southern areas, drought was observed to be more important in the West and the North of Gabes Watershed. The SPI showed that moderate droughts are generally more frequent than severe or extreme droughts in most of the Watershed.

  9. [Spatial-Temporal variability of aquatic plant communities in the Venezuelan Llanos].

    Science.gov (United States)

    Rial B, Anabel

    2006-06-01

    The richness and abundance of aquatic plant communities were studied in 14 habitats of the Venezuelan "llanos" (07 degrees 35'-07 degrees 55' N-68 degrees 50'-69 degrees 00' W, Apure) during an annual cycle. Annual means were 27 degrees C, 115 mm rainfall and 77% relative humidity. A permanent transect was set in each habitat (ten consecutive square meter quadrats from the shore to the water). The plants and the area they covered in each quadrat were recorded monthly for a year. The total richness was 69 species. Alatalo and Alatalo's diversity analysis indicates that season, and its correlate, water level, influence species diversity and abundance more than habitat (spatial factor: geometric index-Euclidean distance).

  10. Spatial variability of air temperature in a free-stall in the Northeastern semi-arid region of Brazil

    Directory of Open Access Journals (Sweden)

    Indira C. M. Gonçalves

    2016-01-01

    Full Text Available ABSTRACT The knowledge on the spatial variability of climatic attributes and the building of Kriging maps can assist in the design and management of confined animal facilities, by allowing a spatial visualization that is helpful for the planning and control of information from the production environment. The study aimed to characterize the spatial variability of air temperature in a free-stall barn used for dairy cattle confinement located in Petrolina-PE, Brazil, in different seasons and at different times. The variable air temperature was recorded at 136 points distributed in the areas under the shed and the shade cloth for the study of spatial variability and the construction of maps by Kriging. Air temperature data was collected in the winter and in the summer, in the months of July and August (2013 and January and February (2014, at different times (9 and 15 h. According to the results, the use of geostatistics enabled to define areas with different spatial variabilities in air temperature and specific areas in the free-stall with values higher than the recommended levels for thermal comfort. In addition, the central part of the facility is the region with the lowest values of air temperatures, due to the presence of a ridge vent.

  11. A method to combine non-probability sample data with probability sample data in estimating spatial means of environmental variables.

    Science.gov (United States)

    Brus, D J; de Gruijter, J J

    2003-04-01

    In estimating spatial means of environmental variables of a region from data collected by convenience or purposive sampling, validity of the results can be ensured by collecting additional data through probability sampling. The precision of the pi estimator that uses the probability sample can be increased by interpolating the values at the nonprobability sample points to the probability sample points, and using these interpolated values as an auxiliary variable in the difference or regression estimator. These estimators are (approximately) unbiased, even when the nonprobability sample is severely biased such as in preferential samples. The gain in precision compared to the pi estimator in combination with Simple Random Sampling is controlled by the correlation between the target variable and interpolated variable. This correlation is determined by the size (density) and spatial coverage of the nonprobability sample, and the spatial continuity of the target variable. In a case study the average ratio of the variances of the simple regression estimator and pi estimator was 0.68 for preferential samples of size 150 with moderate spatial clustering, and 0.80 for preferential samples of similar size with strong spatial clustering. In the latter case the simple regression estimator was substantially more precise than the simple difference estimator.

  12. Intra-urban spatial variability and uncertainty assessment of PM2.5 sources based on carbonaceous species

    Science.gov (United States)

    Xie, Mingjie; Coons, Teresa L.; Hemann, Joshua G.; Dutton, Steven J.; Milford, Jana B.; Peel, Jennifer L.; Miller, Shelly L.; Kim, Sun-Young; Vedal, Sverre; Sheppard, Lianne; Hannigan, Michael P.

    2012-12-01

    To identify the sources of PM2.5 - bound carbonaceous species and examine the spatial variability of source contributions in the Denver metropolitan area, positive matrix factorization (PMF) was applied to one year of every sixth day ambient PM2.5 compositional data, including elemental carbon (EC), organic carbon (OC), and 32 organic molecular markers, from four sites (two residential and two near-traffic). Statistics (median, inner quantiles and 5th - 95th percentiles range) of factor contributions, expressed as reconstructed carbonaceous mass (EC + OC), were estimated from PMF solutions of replicate datasets generated by using a stationary block bootstrap technique. A seven-factor solution was resolved for a set of data pooled across the four sites, as it gave the most interpretable results and had the highest rate of neural network factor matching (76.9%). Identified factors were primarily associated with high plant wax, summertime emission, diesel vehicle emission, fossil fuel combustion, motor vehicle emission, lubricating oil combustion and wood burning. Pearson correlation coefficients (r) and coefficients of divergence (COD) were used to assess spatial variability of factor contributions. The summertime emission factor exhibited the highest spatial correlation (r = 0.74 - 0.88) and lowest CODs (0.32 - 0.38) among all resolved factors; while the three traffic dominated factors (diesel vehicle emission, motor vehicle emission and lubricating oil combustion) showed lower correlations (r = 0.47 - 0.55) and higher CODs (0.41 - 0.53) on average. Average total EC and OC mass were apportioned to each factor and showed a similar distribution across the four sites. Modeling uncertainties were defined as the 5th - 95th percentile range of the factor contributions derived from valid bootstrap PMF solutions, and were highly correlated with the median factor contribution in each factor (r = 0.77 - 0.98). Source apportionment was also performed on site specific datasets

  13. Modelling spatial variability and uncertainty of cadmium leaching to groundwater in an urban region

    Science.gov (United States)

    Beyer, Christof; Altfelder, Sven; Duijnisveld, Wilhelmus H. M.; Streck, Thilo

    2009-05-01

    SummaryOver the last century, soils in the region of Nordenham in northern Germany received high loads of heavy-metals by air-borne immissions from a close-by metal smelter. Based on measured soil properties and cadmium contamination data the leaching of Cd to groundwater was predicted for Nordenham using a numerical transport model based on the convection-dispersion equation. The main objective in this study was to account for the spatial variability and uncertainty of Cd sorption controlling soil properties ( pH, organic carbon content) and to analyze their propagation into the variance of area-related model outputs, i.e. Cd breakthrough concentrations at the groundwater surface. For this purpose a nested Monte-Carlo method was combined with deterministic numerical 1D simulations of Cd leaching. The transport model was parameterized without any parameter fitting involved. The validity of the model was verified by retrospective simulations from the initial operation of the smelter until the year of soil sampling. Forecast simulations were run for a period of 200 years. Predicted local scale Cd breakthrough concentrations at the groundwater surface were evaluated by spatial aggregation for single blocks at the field scale, yielding area-related concentrations with associated uncertainties from imprecise knowledge on local soil properties. Significant exceedance of the limit of the German drinking water ordinance of 5 μg L -1 is observed on approximately 90% of the study area with the average point in time of limit value exceedance being the year 2066 and a 90% prediction interval of 2049-2092. At the end of the simulation period, Cd concentrations at the groundwater surface still increase on large parts of the study area. The spatially averaged Cd concentration is 19.89 μg L -1 with a 90% prediction interval of 15.28-24.69 μg L -1. Locally, however, concentrations larger than 60 μg L -1 may be reached. Prediction uncertainty is only moderate and does not

  14. Drivers of spatial and temporal variability of streamflow in the Incomati River basin

    Science.gov (United States)

    Saraiva Okello, A. M. L.; Masih, I.; Uhlenbrook, S.; Jewitt, G. P. W.; van der Zaag, P.; Riddell, E.

    2015-02-01

    The Incomati is a semi-arid trans-boundary river basin in southern Africa, with a high variability of streamflow and competing water demands from irrigated agriculture, energy, forestry and industries. These sectors compete with environmental flows and basic human water needs, resulting in a "stressed" water resource system. The impacts of these demands, relative to the natural flow regime, appear significant. However, despite being a relatively well-gauged basin in South Africa, the natural flow regime and its spatial and temporal variability are poorly understood and remain poorly described, resulting in a limited knowledge base for water resource planning and management decisions. Thus, there is an opportunity to improve water management, if it can be underpinned by a better scientific understanding of the drivers of streamflow availability and variability in the catchment. In this study, long-term rainfall and streamflow records were analysed. Statistical analysis, using annual anomalies, was conducted on 20 rainfall stations, for the period 1950-2011. The Spearman test was used to identify trends in the records on annual and monthly timescales. The variability of rainfall across the basin was confirmed to be high, both intra- and inter-annually. The statistical analysis of rainfall data revealed no significant trend of increase or decrease. Observed flow data from 33 gauges were screened and analysed, using the Indicators of Hydrologic Alteration (IHA) approach. Temporal variability was high, with the coefficient of variation of annual flows in the range of 1 to 3.6. Significant declining trends in October flows, and low flow indicators, were also identified at most gauging stations of the Komati and Crocodile sub-catchments; however, no trends were evident in the other parameters, including high flows. The trends were mapped using GIS and were compared with historical and current land use. These results suggest that land use and flow regulation are larger

  15. Multi-scale controls on spatial variability in river biogeochemical cycling

    Science.gov (United States)

    Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jennifer; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

    2016-04-01

    Excessive nutrient concentrations are common in surface waters and groundwaters in agricultural catchments worldwide. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical cycling rates can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are largely unknown. Here, we aimed to assess: 1) how differences in river geomorphological heterogeneity control solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small scale targeted management interventions to alter geomorphic heterogeneity may be effective in creating hotspots of river biogeochemical cycling and nutrient load

  16. Geomorphic and substrate controls on spatial variability in river solute transport and biogeochemical cycling

    Science.gov (United States)

    Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jen; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

    2016-04-01

    Nutrient concentrations in surface waters and groundwaters are increasing in many agricultural catchments worldwide as a result of anthropogenic activities. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical transformation rates (e.g. denitrification) can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are not well understood. Here, we aimed to assess: 1) how differences in geomorphological heterogeneity control river solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive 'smart' tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small-scale targeted management interventions to alter geomorphic heterogeneity may be

  17. Spatial variability of benthic-pelagic coupling in an estuary ecosystem: consequences for microphytobenthos resuspension phenomenon.

    Directory of Open Access Journals (Sweden)

    Martin Ubertini

    Full Text Available The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic regime, grain size of the sediment, and suspended matter and biological parameters (flora and fauna assemblages, chlorophyll were analyzed to characterize benthic-pelagic coupling at the bay scale. Samples were collected in two contrasted periods, spring and late summer, to assess the impact of forcing variables on benthic-pelagic coupling. A mapping approach using kriging interpolation enabled us to overlay benthic and pelagic maps of physical and biological variables, for both hydrological conditions and trophic indicators. Pelagic Chl a concentration was the best predictor explaining the suspension-feeders spatial distribution. Our results also suggest a perennial spatio-temporal structure of both benthic and pelagic compartments in the ecosystem, at least when the system is not imposed to intense wind, with MPB distribution controlled by both grain size and bathymetry. The benthic component appeared to control the pelagic one via resuspension phenomena at the scale of the bay. Co-inertia analysis showed closer benthic-pelagic coupling between the variables in spring. The higher MPB biomass observed in summer suggests a higher contribution to filter-feeders diets, indicating a higher

  18. Spatial and temporal variability of soil moisture in a restored reach of an Alpine river

    Science.gov (United States)

    Luster, Jörg

    2010-05-01

    In order to assess the effects of river restoration on water quality, the biogeochemical functions of restored river reaches have to be quantified, and soil moisture is a key environmental variable controlling this functionality. Restored sections of rivers often are characterized by a dynamic mosaic of riparian zones with varying exposure to flooding. In this presentation, the spatial and temporal variability of soil moisture in riparian soils of a restored reach of the Alpine river Thur in northeastern Switzerland is shown. The study was part of the interdisciplinary project cluster RECORD, which was initiated to advance the mechanistic understanding of coupled hydrological and ecological processes in river corridors. The studied river reach comprised the following three functional processing zones (FPZ) representing a lateral successional gradient with decreasing hydrological connectivity (i.e. decreasing flooding frequency and duration). (i) The grass zone developed naturally on a gravel bar after restoration of the channelized river section (mainly colonized by canary reed grass Phalaris arundinacae). The soil is loamy sand to sandy loam composed of up to 80 cm thick fresh sediments trapped and stabilized by the grass roots. (ii) The bush zone is composed of young willow trees (Salix viminalis) planted during restoration to stabilize older overbank deposits with a loamy fine earth. (iii) The mixed forest is a mature riparian hardwood forest with ash and maple as dominant trees developed on older overbank sediments with a silty loamy fine earth. The study period was between spring 2009 and winter 2009/2010 including three flood events in June, July and December 2009. The first and third flood inundated the grass zone and lower part of the bush zone while the second flood was bigger and swept through all the FPZs. Water contents in several soil depths were measured continuously in 30 minute intervals using Decagon EC-5 and EC-TM sensors. There were six spatial

  19. Crop-ecology and nutritional variability influence growth and secondary metabolites of Stevia rebaudiana Bertoni.

    Science.gov (United States)

    Pal, Probir Kumar; Kumar, Rajender; Guleria, Vipan; Mahajan, Mitali; Prasad, Ramdeen; Pathania, Vijaylata; Gill, Baljinder Singh; Singh, Devinder; Chand, Gopi; Singh, Bikram; Singh, Rakesh Deosharan; Ahuja, Paramvir Singh

    2015-02-27

    Plant nutrition and climatic conditions play important roles on the growth and secondary metabolites of stevia (Stevia rebaudiana Bertoni); however, the nutritional dose is strongly governed by the soil properties and climatic con