WorldWideScience

Sample records for extreme runoff characteristics

  1. Extreme heat and runoff extremes in the Swiss Alps

    Directory of Open Access Journals (Sweden)

    M. Zappa

    2007-06-01

    Full Text Available The hydrological response of Swiss river basins to the 2003 European summer heatwave was evaluated by a combined analysis of historical discharge records and specific applications of distributed hydrological modeling. In the summer of 2003, the discharge from headwater streams of the Swiss Central Plateau was only 40%–60% of the long-term average. For alpine basins runoff was about 60%–80% of the average. Glacierized basins showed the opposite behavior. According to the degree of glacierization, the average summer runoff was close or even above average. The hydrological model PREVAH was applied for the period 1982–2005. Even if the model was not calibrated for such extreme meteorological conditions, it was well able to simulate the hydrological responses of three basins. The aridity index φ describes feedbacks between hydrological and meteorological anomalies, and was adopted as an indicator of hydrological drought. The anomalies of φ and temperature in the summer of 2003 exceeded the 1982–2005 mean by more than 2 standard deviations. Catchments without glaciers showed negative correlations between φ and discharge R. In basins with about 15% glacierization, φ and R were not correlated. River basins with higher glacier percentages showed a positive correlation between φ and R. Icemelt was positively correlated with φ and reduced the variability of discharge with larger amounts of meltwater. Runoff generation from the non-glaciated sub-areas was limited by high evapotranspiration and reduced precipitation. The 2003 summer heatwave could be a precursor to similar events in the near future. Hydrological models and further data analysis will allow the identification of the most sensitive regions where heatwaves may become a recurrent natural hazard with large environmental, social and economical impacts.

  2. Climate Extremes Events and their Connection with Runoff in the Yellow River Basin

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    Hu, Caihong; Lei, Deyi; He, Huli; Wang, Jijun

    2016-04-01

    This study analyzes the temporal and spatial distribution of runoff and their relationship with the extreme values of eight climate indices, based on observational data from 143 meteorological stations and 6 hydrological stations across the basin. The eight core indices selected from the STARDEX projects reflect rather moderate extremes. Statistics methods and GIS technology were be used for analysis on the relationship and distribution characteristics. We analyzed the reason of runoff change and the relationship between the climate extreme events and observed runoff from six hydrological stations. Our results show that the annual and seasonal runoff showed obviously decrease tendency. Sharp decreases of runoff in six hydrological stations occurred in the late 1980s and 1990s. It can be seen that the decrease in runoff was caused by climate change, increased demands for water supply, land use change, etc. And the difference between the magnitude of the increasing and decreasing trends for different indices at different stations suggests that the climate extremes and environment change resulted in a decrease in runoff. The results also show that the shortage of water resources will become more pronounced in the Yellow River Basin with the increased occurrence of climate extremes. The results presented here will help to improve our understanding of the changes to climate extremes, and provide a basis for further investigation.

  3. Extreme Precipitation and Runoff under Changing Climate in Southern Maine

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Eugene [Argonne National Lab. (ANL), Argonne, IL (United States); Jared, Alissa [Argonne National Lab. (ANL), Argonne, IL (United States); Mahat, Vinod [Argonne National Lab. (ANL), Argonne, IL (United States); Picel, Mark [Argonne National Lab. (ANL), Argonne, IL (United States); Verner, Duane [Argonne National Lab. (ANL), Argonne, IL (United States); Wall, Thomas [Argonne National Lab. (ANL), Argonne, IL (United States); Moges, Edom M. [Washington State Univ., Pullman, WA (United States); Demissie, Yonas K. [Washington State Univ., Pullman, WA (United States); Pierce, Julia [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-12-01

    The quantification of extreme precipitation events is vitally important for designing and engineering water and flood sensitive infrastructure. Since this kind of infrastructure is usually built to last much longer than 10, 50, or even 100 years, there is great need for statistically sound estimates of the intensity of 10-, 50-, 100-, and 500-year rainstorms and associated floods. The recent assessment indicated that the intensity of the most extreme precipitation events (or the heaviest 1% of all daily events) have increased in every region of the contiguous states since the 1950s (Melillo et al. 2014). The maximum change in precipitation intensity of extreme events occurred in the northeast region reaching 71%. The precipitation extremes can be characterized using intensity-duration-frequency analysis (IDF). However, the current IDFs in this region were developed around the assumption that climate condition remains stationary over the next 50 or 100 years. To better characterize the potential flood risk, this project will (1) develop precipitation IDFs on the basis of both historical observations and future climate projections from dynamic downscaling with Argonne National Laboratory’s (Argonne’s) regional climate model and (2) develop runoff IDFs using precipitation IDFs for the Casco Bay Watershed. IDF development also considers non-stationary distribution models and snowmelt effects that are not incorporated in the current IDFs.

  4. Sensitivity of the Runoff Characteristics of Small Alpine Catchments to Climate Change

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    Meißl, Gertraud; Klebinder, Klaus; Formayer, Herbert; Kerl, Florian; Schöberl, Friedrich; Geitner, Clemens; Markart, Gerhard; Kohl, Bernhard; Nadeem, Imran; Leidinger, David; Bronstert, Axel; Bürger, Gerd

    2016-04-01

    Floods and debris flows in small torrent catchments (Nardus stricta) may show increased surface runoff in case of precipitation events with high intensity after dry periods. The analyses of the maximum intensity of heavy precipitation events indicate a clear increase up to 10% till the end of the century. If one of these trends equalizes the other out resulting in unchanged occurrence probabilities of extreme runoff events, cannot be answered generally because of the local characteristics of relevant processes and uncertainties regarding the modelling chain. Regardless of the open question about its return period, peak runoff of extreme events may increase by approximately 25% comparing to current peak runoff due to the higher rain intensities.

  5. Top-down methodology for rainfall-runoff modelling and evaluation of hydrological extremes

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    Willems, Patrick

    2014-05-01

    A top-down methodology is presented for implementation and calibration of a lumped conceptual catchment rainfall-runoff model that aims to produce high model performance (depending on the quality and availability of data) in terms of rainfall-runoff discharges for the full range from low to high discharges, including the peak and low flow extremes. The model is to be used to support water engineering applications, which most often deal with high and low flows as well as cumulative runoff volumes. With this application in mind, the paper wants to contribute to the above-mentioned problems and advancements on model evaluation, model-structure selection, the overparameterization problem and the long time the modeller needs to invest or the difficulties one encounters when building and calibrating a lumped conceptual model for a river catchment. The methodology is an empirical and step-wise technique that includes examination of the various model components step by step through a data-based analysis of response characteristics. The approach starts from a generalized lumped conceptual model structure. In this structure, only the general components of a lumped conceptual model, such as the existence of storage and routing elements, and their inter-links, are pre-defined. The detailed specifications on model equations and parameters are supported by advanced time series analysis of the empirical response between the rainfall and evapotranspiration inputs and the river flow output. Subresponses are separated and submodel components and related subsets of parameters are calibrated as independently as possible. At the same time, the model-structure identification process aims to reach parsimonious submodel-structures, and accounts for the serial dependency of runoff values, which typically is higher for low flows than for high flows. It also accounts for the heteroscedasticity and dependency of model residuals when evaluating the model performance. It is shown that this step

  6. Heavy Metal Runoff in Relation to Soil Characteristics

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Cu,Zn,Pb and Hg runoff from yellow limestone soil and purple soils and the relationships between the mobility of the heavy metals and the soil characteristics were studied in laboratory using a rainfall simulator.The results showed that the concentrations of soluble Zn in surface runoff were significantly negatively correlated with the contents of <0.002 mm particles and CEC of the soils, indicating that Zn was mostly adsorbed by clays in the soils.The contents of Cu and Hg in surface runoff were positively related to their contents in the soils.The amounts of Gu, Zn,Pb and Hg removed by surface runoff were influenced by the amounts of soil and water losses and their contents in the soils,and were closely related to the contents of soil particles 1~0.02 mm in size.

  7. DISTRIBUTION OF RIVER RUNOFF AND ITS CLIMATE FACTORS IN AVERAGE AND EXTREME YEARS

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    Vladimir Konovalov

    2011-01-01

    Full Text Available Schematic maps of spatial distribution of seasonal precipitation amounts and average air temperatures were obtained for the areas studied in years with normal and extreme values of annual river runoff. Data on precipitation for January–December (I–XII and on average air temperatures for June–September (VI–IX during 1961–1990 collected at 93 meteorological stations located along 30.20°–44.08°N and 67.20°–82.98°E, altitude 122–4 169 m above sea level, were used in the maps’ compilation. For each point-element (i.e. a meteorological station with proper data, the ordinates of an integral empirical function of distribution of probabilities P were calculated from these data for a 30-year sample period and for each year were received average values and standard deviations of P. In characteristic years were revealed, significant differences of spatial distribution of climatic factors and runoff. It was found out also that the spatial distribution of the total volume of glaciers melting is less variable in the years with extreme water yields compared to the average years. This peculiarity is very beneficial for hydropower and agriculture sectors because it provides additional natural ability to stabilize water balance of reservoirs. Piecewise multi-factor linear equations were obtained to calculate the statistical probability of glaciers’ total melting in low and high flow years as a function of geographical coordinates and the average altitude of firn boundary.

  8. Impacts of extreme climate on simulated runoff in the Yellow River Basin

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    Tang, Y.; Tang, Q.

    2011-12-01

    Historical observations show that extreme climate events have increased in frequency in the Yellow River Basin. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4) projects higher climate variability in a warmer climate, suggesting an increase of extreme climate frequency in the 21st century. The responses of available water resources to the extreme climate remain relatively unexplored in the Yellow River Basin. This study examines the change in the climate extreme and its impacts on streamflow using a long time series of runoff estimated from the Soil and Water Assessment Tool (SWAT) model. The linear regression and the Mann-Kendall non-parameter statistical method are used to detect the change trend in climate (primary precipitation and temperature) extreme frequency and intensity. Three SWAT simulations are conducted. The first simulation is a control SWAT experiment using the observed climate data. The second simulation is driven by a de-trended climate data in which the linear trend is removed and the mean values are fixed to the means of the first decade. The third simulation is a stable simulation where climate conditions repeated from the first decade. The trends of the simulated runoff are analyzed and compared. The effects of changes in the temporal climate pattern and mean climate condition are computed from the estimated runoff trends. The differences between the SWAT simulations represent the contribution of the change to the alteration of the simulated runoff. Our preliminary results suggest that the extreme precipitation has significantly changed the simulated runoff both in the flow frequency and mean value.

  9. RUNOFF GENERATION CHARACTERISTICS IN TYPICAL EROSION REGIONS ON THE LOESS PLATEAU

    Institute of Scientific and Technical Information of China (English)

    Li CHEN; Qingquan LIU; Jiachun LI

    2001-01-01

    This paper presents a process-based model for runoff generation on slopes. One dimensional kinematic wave theory combined with the revised Green-Ampt infiltration formula is applied in the model. According to the characteristics of soil and rainfall in the Loess Plateau area, six types of storm are defined, and among them three typical erosion zones that have different values of representative parameters are chosen to simulate the runoff generation processes. The primary hydraulic characteristics of the runoff generation, such as unit discharge, runoff depth, flow velocity, shear stress and ratio of runoff generation, are obtained and analyzed. The results demonstrate that the different erosion characteristics are related to different runoff generation zones.

  10. Analysis on the Pollution Characteristics of Surface Runoff in Zhenjiang City

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to analyze the pollution characteristics of surface runoff in Zhenjiang City.[Method] On July 4 and August 16,2010,surface runoff samples were collected in different rainfall durations in Zhenjiang City,and the variation characteristics of suspended substance (SS),chemical oxygen demand (CODCr),ammonia nitrogen (NH3-N) and total phosphorus (TP) in surface runoff were analyzed.[Result] With the increase of rainfall duration,SS concentration in surface runoff of Zhenjiang City on July ...

  11. Characteristics of Extreme Auroral Charging Events

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    Minow, Joseph I.; Willis, Emily; Parker, Linda Neergaard

    2014-01-01

    Today’s presentation describes preliminary results from a study of extreme auroral charging in low Earth orbit. Goal of study is to document characteristics of auroral charging events of importance to spacecraft design, operations, and anomaly investigations.

  12. First flush characteristics of rainfall runoff from a paddy field in the Taihu Lake watershed, China.

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    Li, Songmin; Wang, Xiaoling; Qiao, Bin; Li, Jiansheng; Tu, Jiamin

    2017-02-06

    Nonpoint storm runoff remains a major threat to surface water quality in China. As a paddy matures, numerous fertilizers are needed, especially in the rainy seasons; the concentration of nitrogen and phosphorus in rainfall runoff from farmland is much higher than at other times, and this poses a great threat to water bodies and is the main reason for water eutrophication, especially in high concentration drainages. To date, most studies regarding the characteristics of pollutants in rainfall runoff have mainly been concentrated on urban runoff and watershed runoff; therefore, it is particularly important to investigate the characteristics of nitrogen and phosphorus loss in rainfall runoff from paddy fields. To study the characteristics of nitrogen and phosphorus loss and whether the first flush effect exists, continuous monitoring of the rainfall runoff process of six rainfall events was conducted in 2013, of which four rainfall events during storm, high, middle, and low intensity rainfalls were analyzed, and runoff and quality parameters, such as suspended solids (SS), total nitrogen (TN), ammonium nitrogen (NH4(+)-N), nitrate nitrogen (NO3(-)-N), total phosphorus (TP), and phosphate (PO4(3-)-P), were analyzed to determine the relationship between runoff and water quality. The paddy field is located north of Wuxi Lake Basin along the Hejia River upstream in Zhoutie town, Yixing city. An analysis of the load distribution during rainfall runoff was conducted. Event mean concentration (EMC) was used to evaluate the pollution situation of the paddy field's rainfall runoff. A curve of the dimensionless normalized cumulative load (L) vs. normalized cumulative flow (F) (L-F curve), the probability of the mass first flush (MFFn), and the pollutants carried by the initial 25% of runoff (FF25) were used to analyze the first flush effect of the paddy field runoff, and different contaminants show different results: the concentration of nitrogen and phosphorus fluctuate and

  13. DETERMINATION OF CHARACTERISTICS MAXIMAL RUNOFF MOUNTAIN RIVERS IN CRIMEA

    Directory of Open Access Journals (Sweden)

    V. A. Ovcharuk

    2016-05-01

    Full Text Available This article has been examined maximum runoff of the rivers of theCrimeanMountains. The rivers flow through the western and eastern part of the northern slope Crimean Mountains, and on its southern coast. The largest of them: Belbek, Alma, Salgir, Su-Indol and others. To characterize the maximum runoff of rain floods (the layers of rain floods and maximum discharge of water on the rivers of the Crimean Mountains were used materials of observations for long-term period (from the beginning of observations to 2010 inclusive on 54 of streamflow station with using a the so-called «operator» model for maximum runoff formation.

  14. Effects of check dams on runoff characteristics along gully reaches, the case of Northern Ethiopia

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    Guyassa, Etefa; Frankl, Amaury; Zenebe, Amanuel; Poesen, Jean; Nyssen, Jan

    2017-02-01

    In the Highlands of Northern Ethiopia soil and water conservation (SWC) practices, including construction of check dams in gullies, have been widely implemented for the last three decades. Despite this extensive installation of check dams, their effects on runoff response are not well understood as compared to those of other SWC practices. Hence, this study examines the effects of check dams on runoff response in gully channels. 90 degree V-notch weirs were installed to measure a wide range of runoff discharges at the upper and lower sections of five gully reaches: two channel cut in sandstone (a gully with check dams and vegetation (SCV) and an untreated gully (S)) and three cut in limestone (an untreated gully (L), a gully with check dams but no vegetation (LC) and a gully with check dams and vegetation (LCV)). Automatic sensors were installed to monitor runoff depth during two rainy seasons (29/08/14 - 17/09/14 and 24/7/15 - 14/09/15). All runoff characteristics at the lower section of each gully reaches were calculated for a gully reaches length of 50 m. In the sandstone area, the results show longer lag times of runoff to reach the lower section of the channel reach in the treated gully (SCV) compared to the untreated gully: difference in time lag equal lag to production of runoff equals 51% for runoff initiation, 61% for peak runoff and 44% for runoff end. An increase of hydraulic roughness by check dams and water transmission losses in deposited sediments are responsible for the delay of runoff to reach the lower part of the gully channels. In the limestone area, different time lags were recorded in different gully reaches regardless of the treatment effects (lag to runoff initiation, lag to peak flow and lag to runoff end were larger at LC, L and LCV, respectively). The reduction of peak runoff discharge between the upper and lower gully sections was larger in the gullies with check dam and vegetation (8-17%) than in gullies without treatment (5

  15. Effects of check dams on runoff characteristics along gully reaches, the case of Northern Ethiopia

    Science.gov (United States)

    Guyassa, Etefa; Frankl, Amaury; Zenebe, Amanuel; Poesen, Jean; Nyssen, Jan

    2017-04-01

    In the Highlands of Northern Ethiopia soil and water conservation (SWC) practices, including construction of check dams in gullies, have been widely implemented for the last three decades. Despite this extensive installation of check dams, their effects on runoff response are not well understood as compared to those of other SWC practices. Hence, this study examines the effects of check dams on runoff response in gully channels. 90 degree V-notch weirs were installed to measure a wide range of runoff discharges at the upper and lower sections of five gully reaches: two channel cut in sandstone (a gully with check dams and vegetation (SCV) and an untreated gully (S)) and three cut in limestone (an untreated gully (L), a gully with check dams but no vegetation (LC) and a gully with check dams and vegetation (LCV)). Automatic sensors were installed to monitor runoff depth during two rainy seasons (29/08/14 - 17/09/14 and 24/7/15 - 14/09/15). All runoff characteristics at the lower section of each gully reaches were calculated for a gully reaches length of 50 m. In the sandstone area, the results show longer lag times of runoff to reach the lower section of the channel reach in the treated gully (SCV) compared to the untreated gully: difference in time lag equal lag to production of runoff equals 51% for runoff initiation, 61% for peak runoff and 44% for runoff end. An increase of hydraulic roughness by check dams and water transmission losses in deposited sediments are responsible for the delay of runoff to reach the lower part of the gully channels. In the limestone area, different time lags were recorded in different gully reaches regardless of the treatment effects (lag to runoff initiation, lag to peak flow and lag to runoff end were larger at LC, L and LCV, respectively). The reduction of peak runoff discharge between the upper and lower gully sections was larger in the gullies with check dam and vegetation (8% - 17%) than in gullies without treatment (5% - 6

  16. Analyses of extreme precipitation and runoff events including uncertainties and reliability in design and management of urban water infrastructure

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    Hailegeorgis, Teklu T.; Alfredsen, Knut

    2017-01-01

    There is a need for assessment of uncertainties and hence effects on reliability of design and management of stormwater pipes due to the prevalence of urban floods trigged by modification of land cover and high precipitation intensities respectively due to increasing urbanization and changing climate. Observed annual maximum series (AMS) of extreme precipitation intensities of 17 durations (1-min to 1440-min) and runoff records of 27 years from a 21.255 ha (23% impervious, 35% built-up and 41% open areas) Risvollan catchment in Trondheim City were used. Using a balanced bootstrap resampling (BBRS) with frequency analysis, we quantified considerable uncertainty in precipitation and runoff quantiles due to the sampling variability of systematic observations (e.g., -43% to +49% relative differences from the quantile estimates for the original sample). These differences are higher than suggested increase in design rainfall and floods by many countries for climate change adjustment. The uncertainties in IDF curves and derived design storm hyetographs are found to have large effects on the reliability of sizing of stormwater pipes. The study also indicated low validity of the assumptions on extreme precipitation and runoff relationships in the return period-based method for the partially paved urban catchment: (i) maximum of only 46% of the AMS of extreme precipitation and runoff events occurred concurrently and (ii) T-year return period extreme precipitation events do not necessarily result in T-year flood events. These indicate that there are effects of snowmelt seasonality, and probably catchment moisture states and interactions between the flows in subsurface media and pipes. The results substantiate the need for better understanding of relationships between precipitation and runoff extremes and urban runoff generation process, and importance of uncertainty assessment and application of reliability-based methods for design and management of water infrastructure.

  17. Research on the characteristics of the water quality of rainwater runoff from green roofs.

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    Gong, Kena; Wu, Qing; Peng, Sen; Zhao, Xinhua; Wang, Xiaochen

    2014-01-01

    This paper investigates the water quality characteristics of rainwater runoff from dual-substrate-layer green roofs in Tianjin, China. The data were collected from four different assemblies and three types of simulated rains. The storm-water runoff quality was monitored from early June through late October 2012 and from July through late November 2013. The results revealed that the runoff water quality would be improved to some extent with the ageing of green roofs and that the quality retention rate better reflected the pollutant retention capacity of the green roof than the pollutant concentration in the runoff water. The investigation clearly demonstrated that green roofs also effectively reduced the chemical oxygen demand and turbidity value and neutralised acid rain to stabilise the pH of the runoff.

  18. [Characteristics of Nitrogen and Phosphorus Losses in Longhong Ravine Basin of Westlake in Rainstorm Runoff].

    Science.gov (United States)

    Yang, Fan; Jiang, Yi-feng; Wang, Cui-cui; Huang, Xiao-nan; Wu, Zhi-ying; Chen, Lin

    2016-01-15

    In order to understand the non-point source pollution status in Longhong ravine basin of Westlake, the characteristics of nutrient losses in runoff was investigated during three rainstorms in one year. The results showed that long duration rainstorm event generally formed several runoff peaks, and the time of its lag behind the peaks of rain intensity was dependent on the distribution of heavy rainfall. The first flush was related to the antecedent rainfall, and the less rainfall in the earlier period, the more total phosphorus (TP) and ammonia (NH4+ -N) in runoff was washed off. During the recession of runoff, more subsurface runoff would result in a concentration peak of total nitrogen (TN) and nitrogen (NO3- -N) . The event mean concentration (EMC) of runoff nitrogen had a negative correlation with rainfall, rainfall duration, maximum rain intensity and average rain intensity except for antecedent rainfall, whereas the change in TP EMC showed the opposite trend. The transport fluxes of nutrients increased with an elevation in runoffs, and Pearson analysis showed that the transport fluxes of TN and NO3- -N had good correlations with runoff depth. The average transport fluxes of TP, TN, NH4+ -N and NO3- -N were 34.10, 1195.55, 1006.62 and 52.38 g x hm(-2), respectively, and NO3- -N was the main nitrogen form and accounted for 84% of TN.

  19. The runoff characteristics and harmonic analysis of the soil moisture dynamics in Robinia pseudoacacia stand

    Institute of Scientific and Technical Information of China (English)

    GAOPeng; LIUZuo-xin; CHENFu-sheng

    2003-01-01

    Robinia pseudoacacia stands act as a typical ecorogicar protection forest in hirly semi-arid area of China. Two fierds of surface runoff were separately set up in R. pseudoacacia stand and its crearcut area in the western Liaoning Province (18°50′-122°25′E, 40°24′-42°34′N) for measuring the characteristics of runoff and sediment as werl as soir moisture dynamics.Contractive analysis of the two land types showed that there existed a significant difference in vorumes of runoff and sediment between the sites of R. pseudoacacia stand and its crearcut area. The runoff vorume and sediment vorume in crearcut area were much bigger than those in R. pseudoacacia stand, with an increase amount of 40%-177% for runoff and 180%-400% for sediment. Hydrograph of surface runoff of typical rainfall showed that the peak value of runoff in R. pseudoacacia stand was decreased by 1.0-2.5x10-3m3·s-1 compared with that in its crearcut area, and the occurring time of peak varue of runoff in R.pseudoacacia stand was 10-20 rain later than that in its crearcut area. Harmonic analysis of soir moisture dynamics indicated that the soir moisture in R. pseudoacacia stand was 2.3 % higher than that in clearcut area, and the soir moisture both in R. pseudoacacia stand and its clearcut area courd be divided into dry season and humid season and varied periodicarly with annual rainfall precipitation. It was concruded that R. pseudoacacia stand plays a very important rote in storing water, increasing soil moisture, and reducing surface runoff and soil erosion.

  20. Why can postwildfire runoff and erosion vary from negligible to extreme?

    Science.gov (United States)

    Noske, P.; Nyman, P.; Lane, P. N. J.; Van der Sant, R.; Sheridan, G. J.

    2016-12-01

    Soil surface properties vary with aridity, as does runoff and erosion after wildfire. Here we draw on studies conducted in different upland eucalypt forests of Victoria Australia, to compare and contrast the hydrological effects of wildfire. The study central to this presentation was conducted in two small (0.2-0.3 ha) dry forested headwater catchments burned during the 2009 Black Saturday wildfire. Surface runoff ratios during rainfall events approached 0.45 in the first year postwildfire. High runoff ratios in these dry forests were attributed to wildfire-induced soil water repellency and inherently low hydraulic conductivity. Average annual sediment yields peaked at 10 t ha-1 during the first year before declining dramatically to background levels, suggesting high-magnitude erosion processes may become limited by sediment availability on hillslopes. Surface runoff and erosion differed substantially between the equatorial and polar-facing catchments; this was most likely due to higher rates of infiltration and surface roughness on polar-facing slopes. Data collected from a plot scale study from 5 different burned forest locations of differing aridity produced a range of runoff ratios that support the findings of the central study. Additional data from burned catchments supporting wetter forests are also presented to further illustrate the contrast in rates of runoff and recovery from a different forest type. Results show that rates of postwildfire erosion and runoff in eucalypt forests in south-east Australia are highly variable. Large differences in erosion and runoff occur with relatively small changes in aridity.

  1. Rainfall and runoff Intensity-Duration-Frequency Curves for Washington State considering the change and uncertainty of observed and anticipated extreme rainfall and snow events

    Science.gov (United States)

    Demissie, Y. K.; Mortuza, M. R.; Li, H. Y.

    2015-12-01

    The observed and anticipated increasing trends in extreme storm magnitude and frequency, as well as the associated flooding risk in the Pacific Northwest highlighted the need for revising and updating the local intensity-duration-frequency (IDF) curves, which are commonly used for designing critical water infrastructure. In Washington State, much of the drainage system installed in the last several decades uses IDF curves that are outdated by as much as half a century, making the system inadequate and vulnerable for flooding as seen more frequently in recent years. In this study, we have developed new and forward looking rainfall and runoff IDF curves for each county in Washington State using recently observed and projected precipitation data. Regional frequency analysis coupled with Bayesian uncertainty quantification and model averaging methods were used to developed and update the rainfall IDF curves, which were then used in watershed and snow models to develop the runoff IDF curves that explicitly account for effects of snow and drainage characteristic into the IDF curves and related designs. The resulted rainfall and runoff IDF curves provide more reliable, forward looking, and spatially resolved characteristics of storm events that can assist local decision makers and engineers to thoroughly review and/or update the current design standards for urban and rural storm water management infrastructure in order to reduce the potential ramifications of increasing severe storms and resulting floods on existing and planned storm drainage and flood management systems in the state.

  2. [Sediment content and nitrogen and phosphorus load characteristics of surface runoff on bamboo forest slopes: a simulation test].

    Science.gov (United States)

    Zhang, Li-Ping; Fu, Xing-Tao; Wu, Xi-Yuan

    2012-04-01

    To understand the load characteristics and related mechanisms of surface runoff on two management types of bamboo forests (bamboo timber forest and bamboo shoot forest) slopes (gradient 20 degrees) in Zhejiang Province, this study measured the runoff volume, sediment yield, its total nitrogen (TN) and total phosphorus (TP) concentrations of runoff under six artificial simulated rainfall intensity (31.8-114.0 mm x h(-1)). In bamboo timber forest, the total runoff volume and runoff coefficient were higher, but the runoff sediment content and the total sediment yield were far lower, as compared with those in bamboo shoot forest. The runoff TN concentration in bamboo shoot forest decreased with increasing rainfall intensity. Under the same rainfall intensity, the runoff TN concentration in bamboo shoot forest was 5-6 times of that in bamboo timber forest. The runoff TP concentration was higher in bamboo timber forest than in bamboo shoot forest, but the TP loss from the sediment runoff in bamboo shoot forest was hundreds times of that in bamboo timber forest. During the processes of the TN and TP losses from the sediment runoff, the TN and TP concentrations at the prophase of runoff yield played a cardinal role, while the runoff volume and sediment yield at the anaphase played a decisive role.

  3. Impact of land cover and land use change on runoff characteristics.

    Science.gov (United States)

    Sajikumar, N; Remya, R S

    2015-09-15

    Change in Land Cover and Land Use (LCLU) influences the runoff characteristics of a drainage basin to a large extent, which in turn, affects the surface and groundwater availability of the area, and hence leads to further change in LCLU. This forms a vicious circle. Hence it becomes essential to assess the effect of change in LCLU on the runoff characteristics of a region in general and of small watershed levels (sub-basin levels) in particular. Such an analysis can effectively be carried out by using watershed simulation models with integrated GIS frame work. SWAT (Soil and Water Analysis Tool) model, being one of the versatile watershed simulation models, is found to be suitable for this purpose as many GIS integration modules are available for this model (e.g. ArcSWAT, MWSWAT). Watershed simulation using SWAT requires the land use and land cover data, soil data and many other features. With the availability of repository of satellite imageries, both from Indian and foreign sources, it becomes possible to use the concurrent local land use and land cover data, thereby enabling more accurate modelling of small watersheds. Such availability will also enable us to assess the effect of LCLU on runoff characteristics and their reverse impact. The current study assesses the effect of land use and land cover on the runoff characteristics of two watersheds in Kerala, India. It also assesses how the change in land use and land cover in the last few decades affected the runoff characteristics of these watersheds. It is seen that the reduction in the forest area amounts to 60% and 32% in the analysed watersheds. However, the changes in the surface runoff for these watersheds are not comparable with the changes in the forest area but are within 20%. Similarly the maximum (peak) value of runoff has increased by an amount of 15% only. The lesser (aforementioned) effect than expected might be due to the fact that forest has been converted to agricultural purpose with major

  4. The analytical derivation of multiple elasticities of runoff to climate change and catchment characteristics alteration

    Science.gov (United States)

    Wang, Weiguang; Zou, Shan; Shao, Quanxi; Xing, Wanqiu; Chen, Xi; Jiao, Xiyun; Luo, Yufeng; Yong, Bin; Yu, Zhongbo

    2016-10-01

    The concept of elasticity has been widely employed to quantify the hydrological response to changes in climate and catchments properties. To separate the effect of different climatic variables on runoff, the potential evaporation (E0) elasticity of runoff needs to be presented in term of observed climate variables. To fully reflect the effects of maximum and minimum temperatures and reduce the influence of the correlations of radiation with sunshine duration and relative humidity on the assessment results, we decompose the E0 elasticity into five evaporation-related elasticities (i.e., sunshine duration, maximum and minimum temperature, wind speed and relative humidity) via the first-order differentiation of the FAO 56 Penman equation. As the catchment runoff is frequently affected by the land use/cover change, we also consider changes in catchment characteristics and derive a catchment alteration elasticity based on the Budyko framework. An application was carried out in 30 catchments with widespread climatic types in China. For the two periods (i.e., the baseline period and the changed period) divided by the Pettitt test, the contributions of different climatic variables and land use/cover conditions to runoff change were quantified. In general, the alteration of catchment characteristics and climatic change should be mainly responsible for changes in runoff in water-limited and humid basins, respectively. Although the elasticity of maximum temperature are usually higher than that of minimum temperature, the contributions to runoff change present the opposite direction. Furthermore, additional analysis indicated some overestimation in relative humidity elasticities in the previous studies, further emphasizing the necessity of our extension to alleviate the influence of correlation between climatic variables to the assessment results. Moreover, the results of model performance versus model complexity showed that the choice of model complexity still depends on the

  5. Analysis and Modeling of Time-Correlated Characteristics of Rainfall-Runoff Similarity in the Upstream Red River Basin

    Directory of Open Access Journals (Sweden)

    Xiuli Sang

    2012-01-01

    Full Text Available We constructed a similarity model (based on Euclidean distance between rainfall and runoff to study time-correlated characteristics of rainfall-runoff similar patterns in the upstream Red River Basin and presented a detailed evaluation of the time correlation of rainfall-runoff similarity. The rainfall-runoff similarity was used to determine the optimum similarity. The results showed that a time-correlated model was found to be capable of predicting the rainfall-runoff similarity in the upstream Red River Basin in a satisfactory way. Both noised and denoised time series by thresholding the wavelet coefficients were applied to verify the accuracy of model. And the corresponding optimum similar sets obtained as the equation solution conditions showed an interesting and stable trend. On the whole, the annual mean similarity presented a gradually rising trend, for quantitatively estimating comprehensive influence of climate change and of human activities on rainfall-runoff similarity.

  6. Water-quality characteristics of stormwater runoff in Rapid City, South Dakota, 2008-14

    Science.gov (United States)

    Hoogestraat, Galen K.

    2015-01-01

    The water quality of Rapid Creek is important because the reach that flows through Rapid City, South Dakota, is a valuable spawning area for a self-sustaining trout fishery, actively used for recreation, and a seasonal municipal water supply for the City of Rapid City. This report presents the current (2008–14) water-quality characteristics of urban stormwater runoff in selected drainage networks within the City of Rapid City, and provides an evaluation of the pollutant reductions of wetland channels implemented as a best-management practice. Stormwater runoff data were collected at nine sites in three drainage basins within Rapid City: the Arrowhead (2 monitoring sites), Meade-Hawthorne (1 monitoring site), and Downtown (6 monitoring sites) drainage basins. Stormwater runoff was evaluated for concentrations of total suspended solids (TSS) and bacteria at sites in the Arrowhead and Meade-Hawthorne drainage basins, and for concentrations of TSS, chloride, bacteria, nutrients, and metals at sites in the Downtown drainage basin.

  7. [Output characteristics of rainfall runoff phosphorus pollution from a typical small watershed in Yimeng mountainous area].

    Science.gov (United States)

    Yu, Xing-xiu; Li, Zhen-wei; Liu, Qian-jin; Jing, Guang-hua

    2012-08-01

    Relationships between phosphorus pollutant concentrations and precipitation-runoff were analyzed by monitoring pollutant losses at outlets of the Menglianggu watershed in 2010. A typical small watershed was selected to examine the runoff and quality parameters such as total phosphorus (TP), particle phosphorus (PP), dissolve phosphorus (DP) and dissolve inorganic phosphorus (DIP) in rainfall-runoff of 10 rainfall events. Precipitation was above 2 mm for all the 10 rainfall events. The results showed that the peak of phosphorus concentrations occurred before the peak of water flows, whereas change processes of the phosphorus fluxes were consistent with that of the water flows and the phosphorus flux also have a strong linear relationship with the water flows. The minimums of the phosphorus concentrations in every 10 natural rainfall events have small differences with each other, but the maximum and EMCs of the phosphorus concentrations have significant differences with each rainfall event. This was mainly influenced by the precipitation, maximum rainfall intensity and mean rainfall intensity (EMCs) and was less influenced by rainfall duration. DP and TP were mainly composed of DIP and PP, respectively. There were no significant correlations between DIP/DP dynamic changes and rainfall characteristics, whereas significant correlations between PP/TP dynamic changes and maximum rainfall intensity were detected. The production of DIP, DP, AND TP were mainly influenced by the direct runoff (DR) and base flow (BF). The EMCs of DIP, DP, TP and the variations of DIP/DP were all found to have significant polynomial relationships with DR/TR., but the dynamic changes of PP/ TP and the EMCS of PP were less influenced by the DR/TR.

  8. Water-quality characteristics in runoff for three discovery farms in North Dakota, 2008-12

    Science.gov (United States)

    Nustad, Rochelle A.; Rowland, Kathleen M.; Wiederholt, Ronald

    2015-01-01

    The U.S. Geological Survey, in cooperation with North Dakota State University Agriculture Research Extension and in collaboration with North Dakota State Department of Health, North Dakota State Water Commission, U.S. Environmental Protection Agency, and several agricultural producers, helped organize a Discovery Farms program in North Dakota in 2007. Discharge measurements and water-quality samples collected at the three Farms (Underwood, Dazey, and Embden) were used to describe water-quality characteristics in runoff, and compute estimates of annual loads and yields for selected constituents from spring 2008 through fall 2012.

  9. Predicting shifts in rainfall-runoff partitioning during multiyear drought: Roles of dry period and catchment characteristics

    Science.gov (United States)

    Saft, Margarita; Peel, Murray C.; Western, Andrew W.; Zhang, Lu

    2016-12-01

    While the majority of hydrological prediction methods assume that observed interannual variability explores the full range of catchment response dynamics, recent cases of prolonged climate drying suggest otherwise. During the ˜decade-long Millennium drought in south-eastern Australia significant shifts in hydrologic behavior were reported. Catchment rainfall-runoff partitioning changed from what was previously encountered during shorter droughts, with significantly less runoff than expected occurring in many catchments. In this article, we investigate the variability in the magnitude of shift in rainfall-runoff partitioning observed during the Millennium drought. We re-evaluate a large range of factors suggested to be responsible for the additional runoff reductions. Our results suggest that the shifts were mostly influenced by catchment characteristics related to predrought climate (aridity index and rainfall seasonality) and soil and groundwater storage dynamics (predrought interannual variability of groundwater storage and mean solum thickness). The shifts were amplified by seasonal rainfall changes during the drought (spring rainfall deficits). We discuss the physical mechanisms that are likely to be associated with these factors. Our results confirm that shifts in the annual rainfall-runoff relationship represent changes in internal catchment functioning, and emphasize the importance of cumulative multiyear changes in the catchment storage for runoff generation. Prolonged drying in some regions can be expected in the future, and our results provide an indication of which catchments characteristics are associated with catchments more susceptible to a shift in their runoff response behavior.

  10. Generation of runoff characteristics over three time period for four typical forests in Jinyun Mountain, Chongqing City southwest China

    Institute of Scientific and Technical Information of China (English)

    Xiaoyuan CHU; Yujie WANG; Yiping XIA; Yun WU; Lin CHEN

    2009-01-01

    In order to provide a basis for water conservation in the restoration of vegetation for an urban water resource area, we studied the generation of runoff characteristics in four typical forests over three time periods in Jinyun Mountain, Chongqing City, based on the observation data of rainfall and runoff processes during the period 2002-2005. The results show that: 1) Rainfall was distributed evenly during the years 2002-2005. Annual rainfall variability was 4.46% and coefficient of variation was 0.0618. Average monthly rainfall tended towards a normal distribution N (113.8, 45972). 2) Both precipitation and runoff can be clearly divided into a dry and a wet season. The dry season was from October to March and the wet season from April to September. Most of annual runoff of the four forest stands occurred in the wet season. The surface runoff in the wet season accounted for more than 85% of the annual runoff, and more than 75% of underground runoff. 3) Both peak values of surface runoff and underground runoff occurred in June. The relation between monthly rainfall and surface/underground runoff was fitted by the model W = aP2 + bP + c. The order of annual surface runoff was as follows: Phyllostachys pub-escens forest > shrub forest > mixed Pinus massoniana-broadleaf forest > evergreen broad-leaved forest. The annual underground runoff was evergreen broad-leaved forest > mixed Pinus massoniana-broadleaf forest >Phyl-lostachys pubescens forest > shrub forest. 4) Under similar rainstorms events, the order of the surface runoff coefficient was: evergreen broad-leaved forest mixed Pinus massoniana-broadleaf forest > Phyllostachys pubescens forest > shrub forest. The relation between rainstorms and surface runoff was fitted by the linear relationship: Q = mp-n. Both mixed Pinus massoniana-broadleaf forest and evergreen broad-leaved forest have better flood regulation effects on an annual and monthly basis and per individual rainstorm. The function of Phyllostachys

  11. Runoff properties of extreme discharges on Paraná and Uruguay rivers

    Directory of Open Access Journals (Sweden)

    W. Vargas

    2010-05-01

    Full Text Available Climate variability in different spatial scales is a study area which has reached interest in application, especially during de last years. River discharges can be considered as a robust integrator of the properties of the basin; under these premises the goal of this work is to analyse flows from the Paraná and Uruguay rivers in several gauge stations and study the behavior of positive and negative anomalies and their extremes. The variable to be analysed was defined as the number of anomalies with the same sign per year. Results show that the structures are different for both rivers, which implies a different stochastic process. Identical representativeness was found between the anomaly series in each river. The risk estimation of extremes in both rivers indicates that it is possible to establish a decision model. Additionally, the series of annual number of anomalies presented a climatic jump in the seventies, for both rivers.

  12. Runoff properties of extreme discharges on Paraná and Uruguay rivers

    Science.gov (United States)

    Vargas, W.; Bischoff, S.; Naumann, G.; Marcuzzi, E.

    2010-05-01

    Climate variability in different spatial scales is a study area which has reached interest in application, especially during de last years. River discharges can be considered as a robust integrator of the properties of the basin; under these premises the goal of this work is to analyse flows from the Paraná and Uruguay rivers in several gauge stations and study the behavior of positive and negative anomalies and their extremes. The variable to be analysed was defined as the number of anomalies with the same sign per year. Results show that the structures are different for both rivers, which implies a different stochastic process. Identical representativeness was found between the anomaly series in each river. The risk estimation of extremes in both rivers indicates that it is possible to establish a decision model. Additionally, the series of annual number of anomalies presented a climatic jump in the seventies, for both rivers.

  13. Dynamic Variation Characteristics of Phosphorus in Paddy Field Runoff in Saline Land and Its Potential Environmental Effect

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the dynamic variation characteristics of phosphorus in paddy field runoff in saline land and its potential environmental effect. [Method] Taking Qianguo irrigation district in soda-saline land in Songnen Plain as study object, the dynamic variation law of phosphorus in paddy field runoff under different irrigation conditions and its potential environmental effect were discussed. [Result] Surface water in paddy field was alkaline, and scattered soil had poor fertilizer conser...

  14. Regional impacts of global change: seasonal trends in extreme rainfall, run-off and temperature in two contrasting regions of Morocco

    Science.gov (United States)

    Khomsi, Kenza; Mahe, Gil; Tramblay, Yves; Sinan, Mohamed; Snoussi, Maria

    2016-05-01

    In Morocco, socio-economic activities are highly vulnerable to extreme weather events. This study investigates trends in mean and extreme rainfall, run-off and temperature, as well as their relationship with large-scale atmospheric circulation. It focuses on two Moroccan watersheds: the subhumid climate region of Bouregreg in the north and the semi-arid region of Tensift in the south, using data from 1977 to 2003. The study is based on a set of daily temperature, precipitation and run-off time series retrieved from weather stations in the two regions. Results do not show a homogeneous behaviour in the two catchments; the influence of the large-scale atmospheric circulation is different and a clear spatial dependence of the trend analysis linked to the distance from the coast and the mountains can be observed. Overall, temperature trends are mostly positive in the studied area, while weak statistically significant trends can be identified in seasonal rainfall, extreme rainfall events, average run-off and extreme run-off events.

  15. The effects of climate change and extreme wildfire events on runoff erosion over a mountain watershed

    Science.gov (United States)

    Gould, Gregory K.; Liu, Mingliang; Barber, Michael E.; Cherkauer, Keith A.; Robichaud, Peter R.; Adam, Jennifer C.

    2016-05-01

    Increases in wildfire occurrence and severity under an altered climate can substantially impact terrestrial ecosystems through enhancing runoff erosion. Improved prediction tools that provide high resolution spatial information are necessary for location-specific soil conservation and watershed management. However, quantifying the magnitude of soil erosion and its interactions with climate, hydrological processes, and fire occurrences across a large region (>10,000 km2) is challenging because of the large computational requirements needed to capture the fine-scale complexities of the land surface that govern erosion. We apply the physically-based coupled Variable Capacity Infiltration-Water Erosion Prediction Project (VIC-WEPP) model to study how wildfire occurrences can enhance soil erosion in a future climate over a representative watershed in the northern Rocky Mountains - the Salmon River Basin (SRB) in central Idaho. While the VIC model simulates hydrologic processes at larger scales, the WEPP model simulates erosion at the hillslope scale by sampling representative hillslopes. VIC-WEPP model results indicate that SRB streamflow will have an earlier shift in peak flow by one to two months under future climate scenarios in response to a declining snowpack under warming temperatures. The magnitude of peak flow increases with each higher severity fire scenario; and under the highest fire severity, the peak flow is shifted even earlier, exacerbating the effects of climate change. Similarly, sediment yield also increases with higher fire severities for both historical and future climates. Sediment yield is more sensitive to fire occurrence than to climate change by one to two orders of magnitude, which is not unexpected given that our fire scenarios were applied basin wide as worst case scenarios. In reality, fires only occur over portions of the basin in any given year and subsequent years' vegetation regrowth reduces erosion. However, the effects of climate

  16. Runoff of the upper Yellow River above Tangnag:characteristics, evolution and changing trends

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Runoff and its evolution, based on hydrometeorological data fromsurface measurement stations, are analyzed for the upper reaches of the Yellow River above Tangnag. Some mathematical statistical models, for example, Period Extrapolation-Gradual Regression Model, Grey Topology Forecast Model and Box-Jinkins Model, are applied in predicting changing trends on the runoff The analysis indicates that the runoff volume in the upper Yellow River above Tangnag is ending a period of extended minimum flows. Increasing runoff is expected in the coming years.

  17. Multiple Time-scale Characteristics of Runoff Variations in Middle Reaches of Huolin River and Their Effects

    Institute of Scientific and Technical Information of China (English)

    LU Xiaoning; DENG Wei; ZHANG Shuqing

    2007-01-01

    The Huolin River is one of the most important water sources for Xianghai wetland, Horqin wetland, and Chaganhu wetland in the western Songnen Plain of Northeast China. The annual runoff series of 46 years at Baiyunhushuo Hydrologic Station, which is located in the middle reaches of the Huolin River, were analyzed by using wavelet analysis. Main objective was to discuss the periodic characteristics of the runoff, and examine the temporal patterns of the Huolin River recharging to the floodplain wetlands in the lower reaches of the river, and the corresponding effects of recharging variation on the environmental evolution of the wetlands. The results show that the annual runoff varied mainly at three time scales. The intensities of periodical signals at different time scales were strongly characterized by local distribution in its time frequency domain. The interdecadal variation at a scale of more than 30yr played a leading role in the temporal pattern of runoff variation, and at this scale, the runoff at Baiyunhushuo Hydrologic Station varied in turn of flood, draught and flood. Accordingly, the landscape of the floodplain wetlands presented periodic features, especially prominent before the 1990s. Compared with intense human activities, the runoff periodic pattern at middle (10-20yr) and small (l-10yr) scales, which has relatively low energy, exerted unobvious effects on the environmental evolution of the floodplain wetlands, especially after the 1990s.

  18. Linear and nonlinear characteristics of the runoff response to regional climate factors in the Qira River basin, Xinjiang, Northwest China.

    Science.gov (United States)

    Xue, Jie; Gui, Dongwei

    2015-01-01

    The inland river watersheds of arid Northwest China represent an example of how, in recent times, climatic warming has increased the complexity of Earth's hydrological processes. In the present study, the linear and nonlinear characteristics of the runoff response to temperature and precipitation were investigated in the Qira River basin, located on the northern slope of the Kunlun Mountains. The results showed that average temperature on annual and seasonal scales has displayed a significantly increasing trend, but this has not been reflected in accumulated precipitation and runoff. Using path analysis, a positive link between precipitation and runoff was found both annually and in the summer season. Conversely, it was found that the impact of temperature on runoff has been negative since the 1960s, attributable to higher evaporation and infiltration in the Qira River basin. Over the past 50 years, abrupt changes in annual temperature, precipitation and runoff occurred in 1997, 1987 and 1995, respectively. Combined with analysis using the correlation dimension method, it was found that the temperature, precipitation and runoff, both annually and seasonally, possessed chaotic dynamic characteristics, implying that complex hydro-climatic processes must be introduced into other variables within models to describe the dynamics. In addition, as determined via rescaled range analysis, a consistent annual and seasonal decreasing trend in runoff under increasing temperature and precipitation conditions in the future should be taken into account. This work may provide a theoretical perspective that can be applied to the proper use and management of oasis water resources in the lower reaches of river basins like that of the Qira River.

  19. [Variation characteristics of runoff coefficient of Taizi River basin in 1967-2006].

    Science.gov (United States)

    Deng, Jun-Li; Zhang, Yong-Fang; Wang, An-Zhi; Guan, De-Xin; Jin, Chang-Jie; Wu, Jia-Bing

    2011-06-01

    Based on the daily precipitation and runoff data of six main embranchments (Haicheng River, Nansha River, Beisha River, Lanhe River, Xihe River, and Taizi River south embranchment) of Taizi River basin in 1967-2006, this paper analyzed the variation trend of runoff coefficient of the embranchments as well as the relationship between this variation trend and precipitation. In 1967-2006, the Taizi River south embranchment located in alpine hilly area had the largest mean annual runoff coefficient, while the Haicheng River located in plain area had the relatively small one. The annual runoff coefficient of the embranchments except Nansha River showed a decreasing trend, being more apparent for Taizi River south embranchment and Lanhe River. All the embranchments except Xihe River had an obvious abrupt change in the annual runoff coefficient, and the beginning year of the abrupt change differed with embranchment. Annual precipitation had significant effects on the annual runoff coefficient.

  20. Wave Characteristics and Extreme Parameters in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-feng; WU Ke-jian; ZHOU Liang-ming; WU Lun-yu

    2012-01-01

    This paper is aimed at the whole Bohai Sea,as the complement and improvement of wave characteristics and extreme parameters.Wave fields were simulated in the Bohai Sea by using wave model SWAN from 1985 to 2004.The input data based on the hindcast of high-resolution wind fields from RAMS and water level fields from POM,which have been tested and verified well.Comparisons of significant wave heights between simulation and station observations show a good agreement in general.By statistical analysis,the wave characteristics such as significant wave heights,dominant wave directions and their seasonal variations are discussed.In addition,main wave extreme parameters and directional extreme values particularly for 100-year return period are investigated.

  1. Characteristics of the event mean concentration (EMC) from rainfall runoff on an urban highway

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ju Young, E-mail: juyounglee@snu.ac.kr [Natural Products Center, KIST(Korea Institute of Science and Technology)-Gangneung Institute, Gangnueng 210-340 (Korea, Republic of); Kim, Hyoungjun, E-mail: kimhj9415@hanmail.net [Department of Civil and Environmental Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kim, Youngjin, E-mail: mukta73@korea.kr [Department of Agricultural Engineering, National Institute of Agricultural Science, Gwonseon-Gu, Suwon 442-701 (Korea, Republic of); Han, Moo Young, E-mail: myhan@snu.ac.kr [Department of Civil and Environmental Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

    2011-04-15

    The purpose of this study was to investigate the characterization of the event mean concentration (EMC) of runoff during heavy precipitation events on highways. Highway runoff quality data were collected from the 7th highway, in South Korea during 2007-2009. The samples were analyzed for runoff quantity and quality parameters such as COD{sub cr}, TSS, TPHs, TKN, NO{sub 3}, TP, PO{sub 4} and six heavy metals, e.g., As, Cu, Cd, Ni, Pb and Zn. Analysis of resulting hydrographs and pollutant graphs indicates that the peak of the pollutant concentrations in runoff occurs 20 min after the first rainfall runoff occurrence. The first flush effect depends on the preceding dry period and the rainfall intensity. The results of this study can be used as a reference for water quality management of urban highways. - Research highlights: > Field test on urban highway were performed to 50 of 100 storm events for 3 years. > The peak pollutant concentrations occurs 20 min after the first runoff. > The first flush effect depends on the preceding dry period and rainfall intensity. > Relationship between runoff and event mean concentration for SS and COD. > A crest of the EMC by 70-80 m{sup 3}/event and decreasing EMC after 70-80 m{sup 3}/event. - This study investigate the characterization of the EMC of runoff during rainfall event on highway.

  2. Characteristics of the event mean concentration (EMC) from rainfall runoff on an urban highway.

    Science.gov (United States)

    Lee, Ju Young; Kim, Hyoungjun; Kim, Youngjin; Han, Moo Young

    2011-04-01

    The purpose of this study was to investigate the characterization of the event mean concentration (EMC) of runoff during heavy precipitation events on highways. Highway runoff quality data were collected from the 7th highway, in South Korea during 2007-2009. The samples were analyzed for runoff quantity and quality parameters such as COD(cr), TSS, TPHs, TKN, NO₃, TP, PO₄ and six heavy metals, e.g., As, Cu, Cd, Ni, Pb and Zn. Analysis of resulting hydrographs and pollutant graphs indicates that the peak of the pollutant concentrations in runoff occurs 20 min after the first rainfall runoff occurrence. The first flush effect depends on the preceding dry period and the rainfall intensity. The results of this study can be used as a reference for water quality management of urban highways.

  3. 近60 a新疆开都河径流变化特征分析%Study on Variation Characteristics of Runoff in Kaidu River Over 60 Years

    Institute of Scientific and Technical Information of China (English)

    邱慧琼; 刘俊

    2016-01-01

    Based on the Dashankou Hydrometric Station monthly runoff data from 1956 to 2012, this paper used non parametric test, R/S method and the maximum entropy spectral method to analyze the variation characteristics of annual runoff in Kaidu River. The results show that the annual runoff in Kaidu River mutations occurrs in 1997 and reaches the extremely significant level. The calculation results are consistent with the M-K method;annual runoff passes significant test and Z value is positive, showing a rising trend in the recent 60 a. The dip ratio is 0.1182×108 m3/a;Hearst index is 0.8774, that means annual runoff changes still keep increasing trend in the future;28 a as the first main period, 9 a as the second main period and 16 a as the third main period. The results provide an important reference for reasonable development and utilization of regional water resources.%根据新疆开都河大山口水文站1956—2012年逐月径流量资料,采用非参数检验、R/S法及最大熵谱法分析了年径流量变化特征。结果表明:开都河年径流量在1997年发生突变,并达到极显著水平,这与M-K法的计算结果一致;年尺度下的径流量变化通过了显著性检验,Z值为正,表明近60 a来径流量呈增长趋势,倾向率为0.1182亿m3/a;径流量赫斯特指数为0.8774,表明未来径流量仍呈增加趋势;年径流量变化以28 a为第一主周期,9 a为第二主周期,16 a为第三主周期。

  4. [Comparative study on characteristics of urban rainfall runoff from two urban lawn catchments in Macau and Xiamen].

    Science.gov (United States)

    Huang, Jin-liang; Tu, Zhen-shun; Du, Peng-fei; Li, Qing-sheng; Lin, Jie; Yang, Long-qi

    2009-12-01

    A comparative study on characteristics of stormwater runoff from two urban lawn catchments in Macau (ELH) and Xiamen (PGH) with separated sewer system were conducted. The result obtained shows that COD, TP and NO3- -N are the major pollutants with mean EMC of 165.77-60.48 mg/L, 0.96-0.44 mg/L and 7.16-1.18 mg/L, respectively, and the mean values of pollutants loads of COD, TP and NO3- -N from study lawn catchments are 6.53-0.63 kg/hm2, 0.0375-0.0047 kg/hm2 and 0.0122-0.0128 kg/hm2, respectively. Peak values of major pollutant concentrations usually precede the flow peak. First flush effect of rainfall runoff from two study catchments is no obvious, which can be reflected by the low mean value of FF30 of TSS, COD, TP and NO3- -N, with 36.26%, 26.13%, 28.13% and 39.03%, respectively. Based on multivariate statistical analysis, first flush effect from urban lawn rainfall runoff is greatly influenced by total rainfall amount (Tr) and total runoff volume (V).

  5. Poultry manure runoff and its influence on fluorescence characteristics of dissolved organic matter (DOM)

    Science.gov (United States)

    Singh, S.; Dutta, S.; Inamdar, S. P.

    2013-12-01

    Land application of poultry manure as a substitute for synthetic fertilizer is a common practice in states like Delaware which have a surplus of this animal waste. However, this practice can generate large amounts of labile DOM and nutrients in agricultural runoff that can cause eutrophication of downstream aquatic ecosystems. We determined the concentrations of dissolved organic carbon (DOC) and dissolved inorganic nitrogen (DIN) and the quality of DOM for a cropland receiving poultry manure in the coastal plain soils of Delaware. Manure was applied at the rate of 9 Mg ha-1 in the spring (March 10) of 2010 to an agricultural field planted in corn. Sampling was performed for surface runoff and soil waters at four landscape positions - field edge, upper and lower riparian zones and the stream. Sampling was conducted for eight storm events, one before manure application and seven after (March through July spanning over 100 days). DOM quality was characterized using spectrofluorometric techniques and the development of a site-specific PARAFAC model. DOC and DIN concentrations in surface runoff ranged from 18.1 to 77.2 mg/l and 4.2 to 22.6 mg/l, respectively. The percent of protein-like and humic-like DOM in surface runoff ranged between 3.9 to 23.5% and 12.3 to 41.6%, respectively. Highest concentrations of DOC and DIN were observed at the field edge and lowest in the stream. Protein-like and humic-like DOM decreased from the field edge to stream in surface runoff and soil waters. Temporally, both humic-like and protein-like DOM showed significant increases in storm runoff following manure application. After manure application, humic-like DOM increased by 70% while protein-like DOM increased by more than 200% in surface runoff indicating elevated content of labile DOM in poultry manure. These concentrations remained high for more than 60 days following manure application. Protein-like DOM was significantly correlated with nitrate-nitrogen (r = 0.43; p < 0

  6. Runoff erosion

    OpenAIRE

    Evelpidou, Niki; Cordier, Stephane; Merino, Agustin (Ed.); Figueiredo, Tomás; Centeri, Csaba

    2013-01-01

    Table of Contents PART I – THEORY OF RUNOFF EROSION CHAPTER 1 - RUNOFF EROSION – THE MECHANISMS CHAPTER 2 - LARGE SCALE APPROACHES OF RUNOFF EROSION CHAPTER 3 - MEASURING PRESENT RUNOFF EROSION CHAPTER 4 - MODELLING RUNOFF EROSION CHAPTER 5 - RUNOFF EROSION AND HUMAN SOCIETIES: THE INFLUENCE OF LAND USE AND MANAGEMENT PRACTICES ON SOIL EROSION PART II - CASE STUDIES CASE STUDIES – INTRODUCTION: RUNOFF EROSION IN MEDITERRANEAN AREA CASE STUDY 1: Soil Erosion Risk...

  7. Predicting characteristics of rainfall driven estrogen runoff and transport from swine AFO spray fields.

    Science.gov (United States)

    Lee, Boknam; Kullman, Seth W; Yost, Erin E; Meyer, Michael T; Worley-Davis, Lynn; Williams, C Michael; Reckhow, Kenneth H

    2015-11-01

    Animal feeding operations (AFOs) have been implicated as potentially major sources of estrogenic contaminants into the aquatic environment due to the relatively minimal treatment of waste and potential mobilization and transport of waste components from spray fields. In this study a Bayesian network (BN) model was developed to inform management decisions and better predict the transport and fate of natural steroidal estrogens from these sites. The developed BN model integrates processes of surface runoff and sediment loss with the modified universal soil loss equation (MUSLE) and the soil conservation service curve number (SCS-CN) runoff model. What-if scenario simulations of lagoon slurry wastes to the spray fields were conducted for the most abundant natural estrogen estrone (E1) observed in the system. It was found that E1 attenuated significantly after 2 months following waste slurry application in both spring and summer seasons, with the overall attenuation rate predicted to be higher in the summer compared to the spring. Using simulations of rainfall events in conjunction with waste slurry application rates, it was predicted that the magnitude of E1 runoff loss is significantly higher in the spring as compared to the summer months, primarily due to spray field crop management plans. Our what-if scenario analyses suggest that planting Bermuda grass in the spray fields is likely to reduce runoff losses of natural estrogens near the water bodies and ecosystems, as compared to planting of soybeans.

  8. Effects of roof and rainwater characteristics on copper concentrations in roof runoff.

    Science.gov (United States)

    Bielmyer, Gretchen K; Arnold, W Ray; Tomasso, Joseph R; Isely, Jeff J; Klaine, Stephen J

    2012-05-01

    Copper sheeting is a common roofing material used in many parts of the world. However, copper dissolved from roof sheeting represents a source of copper ions to watersheds. Researchers have studied and recently developed a simple and efficient model to predict copper runoff rates. Important input parameters include precipitation amount, rain pH, and roof angle. We hypothesized that the length of a roof also positively correlates with copper concentration (thus, runoff rates) on the basis that runoff concentrations should positively correlate with contact time between acidic rain and the copper sheet. In this study, a novel system was designed to test and model the effects of roof length (length of roof from crown to the drip edge) on runoff copper concentrations relative to rain pH and roof angle. The system consisted of a flat-bottom copper trough mounted on an apparatus that allowed run length and slope to be varied. Water of known chemistry was trickled down the trough at a constant rate and sampled at the bottom. Consistent with other studies, as pH of the synthetic rainwater decreased, runoff copper concentrations increased. At all pH values tested, these results indicated that run length was more important in explaining variability in copper concentrations than was the roof slope. The regression equation with log-transformed data (R(2) = 0.873) accounted for slightly more variability than the equation with untransformed data (R(2) = 0.834). In log-transformed data, roof angle was not significant in predicting copper concentrations.

  9. Comparison of sediment and nutrient export and runoff characteristics from watersheds with centralized versus distributed stormwater management.

    Science.gov (United States)

    Hopkins, Kristina G; Loperfido, J V; Craig, Laura S; Noe, Gregory B; Hogan, Dianna M

    2017-12-01

    Stormwater control measures (SCMs) are used to retain stormwater and pollutants. SCMs have traditionally been installed in a centralized manner using detention to mitigate peak flows. Recently, distributed SCM networks that treat runoff near the source have been increasingly utilized. The aim of this study was to evaluate differences among watersheds that vary in SCM arrangement by assessing differences in baseflow nutrient (NOx-N and PO4(-)) concentrations and fluxes, stormflow export of suspended sediments and particulate phosphorus (PP), and runoff characteristics. A paired watershed approach was used to compare export between 2004 and 2016 from one forested watershed (For-MD), one suburban watershed with centralized SCMs (Cent-MD), and one suburban watershed with distributed SCMs (Dist-MD). Results indicated baseflow nitrate (NOx-N) concentrations typically exceeded 1 mg-N/L in all watersheds and were highest in Dist-MD. Over the last 10 years in Dist-MD, nitrate concentrations in both stream baseflow and in a groundwater well declined as land use shifted from agriculture to suburban. Baseflow nitrate export temporarily increased during the construction phase of SCM development in Dist-MD. This temporary pulse of nitrate may be attributed to the conversion of sediment control facilities to SCMs and increased subsurface flushing as infiltration SCMs came on line. During storm flow, Dist-MD tended to have less runoff and lower maximum specific discharge than Cent-MD for small events (1.3 cm). Mass export estimated during paired storm events indicated Dist-MD exported 30% less sediment and 31% more PP than Cent-MD. For large precipitation events, export of sediment and PP was similar among all three watersheds. Results suggest that distributed SCMs can reduce runoff and sediment loads during small rain events compared to centralized SCMs, but these differences become less evident for large events when peak discharge likely leads to substantial bank erosion

  10. [Characteristics of nutrient loss by runoff in sloping arable land of yellow-brown under different rainfall intensities].

    Science.gov (United States)

    Chen, Ling; Liu, De-Fu; Song, Lin-Xu; Cui, Yu-Jie; Zhang, Gei

    2013-06-01

    In order to investigate the loss characteristics of N and P through surface flow and interflow under different rainfall intensities, a field experiment was conducted on the sloping arable land covered by typical yellow-brown soils inXiangxi River watershed by artificial rainfall. The results showed that the discharge of surface flow, total runoff and sediment increased with the increase of rain intensity, while the interflow was negatively correlated with rain intensity under the same total rainfall. TN, DN and DP were all flushed at the very beginning in surface flow underdifferent rainfall intensities; TP fluctuated and kept consistent in surface flow without obvious downtrend. While TN, DN and DP in interflow kept relatively stable in the whole runoff process, TP was high at the early stage, then rapidly decreased with time and kept steady finally. P was directly influenced by rainfall intensity, its concentration in the runoff increased with the increase of the rainfall intensity, the average concentration of N and P both exceeded the threshold of eutrophication of freshwater. The higher the amount of P loss was, the higher the rain intensity. The change of N loss was the opposite. The contribution rate of TN loss carried by surface flow increased from 36.5% to 57.6% with the increase of rainfall intensity, but surface flow was the primary form of P loss which contributed above 90.0%. Thus, it is crucial to control interflow in order to reduce N loss. In addition, measures should be taken to effectively manage soil erosion to mitigate P loss. The proportion of dissolved nitrogen in surface flow elevated with the decrease of rainfall intensity, but in interflow, dissolved form was predominant. P was exported mainly in the form of particulate under different rainfall intensities and runoff conditions.

  11. Quantifying runoff water quality characteristics from nurseries and avocado groves subjected to altered irrigation and fertilizer regimes

    Science.gov (United States)

    Samant, S. A.; Beighley, R. E.

    2007-12-01

    surface water quality, aquatic habitats, and overall stream health. Preliminary results for runoff water quality (N and P) and plant growth characteristics from two months of monitoring are presented.

  12. Comparison of sediment and nutrient export and runoff characteristics from watersheds with centralized versus distributed stormwater management

    Science.gov (United States)

    Hopkins, Kristina; Loperfido, J.V.; Craig, Laura S.; Noe, Gregory; Hogan, Dianna

    2017-01-01

    Stormwater control measures (SCMs) are used to retain stormwater and pollutants. SCMs have traditionally been installed in a centralized manner using detention to mitigate peak flows. Recently, distributed SCM networks that treat runoff near the source have been increasingly utilized. The aim of this study was to evaluate differences among watersheds that vary in SCM arrangement by assessing differences in baseflow nutrient (NOx-N and PO4−) concentrations and fluxes, stormflow export of suspended sediments and particulate phosphorus (PP), and runoff characteristics. A paired watershed approach was used to compare export between 2004 and 2016 from one forested watershed (For-MD), one suburban watershed with centralized SCMs (Cent-MD), and one suburban watershed with distributed SCMs (Dist-MD). Results indicated baseflow nitrate (NOx-N) concentrations typically exceeded 1 mg-N/L in all watersheds and were highest in Dist-MD. Over the last 10 years in Dist-MD, nitrate concentrations in both stream baseflow and in a groundwater well declined as land use shifted from agriculture to suburban. Baseflow nitrate export temporarily increased during the construction phase of SCM development in Dist-MD. This temporary pulse of nitrate may be attributed to the conversion of sediment control facilities to SCMs and increased subsurface flushing as infiltration SCMs came on line. During storm flow, Dist-MD tended to have less runoff and lower maximum specific discharge than Cent-MD for small events (1.3 cm). Mass export estimated during paired storm events indicated Dist-MD exported 30% less sediment and 31% more PP than Cent-MD. For large precipitation events, export of sediment and PP was similar among all three watersheds. Results suggest that distributed SCMs can reduce runoff and sediment loads during small rain events compared to centralized SCMs, but these differences become less evident for large events when peak discharge likely leads to substantial bank erosion.

  13. Spatial rainfall variability and runoff response during an extreme event in a semi-arid catchment in the South Pare Mountains, Tanzania

    Directory of Open Access Journals (Sweden)

    M. L. Mul

    2008-09-01

    Full Text Available This paper describes an extreme flood event that occurred in the South Pare Mountains in northern Tanzania. A high spatial and temporal resolution data set was gathered in a previously ungauged catchment. This data was analysed using a multi-method approach, to gather information about the processes that resulted in the flood event. On 1 March 2006, extreme rainfall occurred in the Makanya catchment, (300 km2, where up to 100 mm were recorded in Bangalala village in only 3 h. Runoff was devastating, inundating large parts of the flood plain. The spatial variability of the rainfall during the event was very large, even in areas with the same altitude. The Vudee sub-catchment (25.8 km2 was in the centre of the rainfall event, receiving about 75 mm in 3 h divided over the two upstream tributaries: the Upper-Vudee and Ndolwa. The peak flow at the weir site has been determined using the slope-area method and gradually varied flow calculations, indicating a peak discharge of 32 m3 s−1. Rise and fall of the flood was very sharp, with the peak flow occurring just one hour after the peak of the rainfall. The flow receded to 1% of the maximum flow within 24 h. Hydrograph separation using hydrochemical parameters indicates that at the peak of the flow 50% was generated by direct surface runoff (also indicated by the large amount of sediments in the samples, whereas the recession originated from displaced groundwater (>90 %. The subsequent base flow in the river remained at 75 l s−1 for the rest of the season, which is substantially higher than the normal base flow observed during the previous rainy seasons (15 l s−1 indicating significant groundwater recharge during this extreme event.

  14. Effect of climate change on stormwater runoff characteristics and treatment efficiencies of stormwater retention ponds; a case study from Denmark using TSS and Cu as indicator pollutants. SpringerPlus, 5:1984, 1-12

    DEFF Research Database (Denmark)

    Sharma, Anitha Kumari; Vezzaro, Luca; Birch, Heidi

    2016-01-01

    This study investigated the potential effect of climate changes on stormwater pollution runoff characteristics and the treatment efficiency of a stormwater retention pond in a 95 ha catchment in Denmark. An integrated dynamic stormwater runoff quality and treatment model was used to simulate two...... scenarios: one representing the current climate and another representing a future climate scenario with increased intensity of extreme rainfall events and longer dry weather periods. 100-year long high-resolution rainfall time series downscaled from regional climate model projections were used as input...... concentrations. The future climate simulations showed an increased frequency of higher flows and increased total concentrations discharged from the catchment. The effect on the outlet from the pond was an increase in the total concentrations (TSS and Cu), whereas no major effect was observed on dissolved Cu...

  15. Features of hyperbolic metamaterials with extremal optical characteristics

    Science.gov (United States)

    Kurilkina, S. N.; Binhussain, M. A.; Belyi, V. N.; Kazak, N. S.

    2016-08-01

    The possibility is shown and conditions are found for the realization of the type I or II epsilon-near-zero (ENZ) metamaterials based on a multilayer metal-dielectric structure. It is found that, for both propagating and evanescent extraordinary waves, diffraction-free energy transportation occurs with low losses within narrow channels inside the type I ENZ metamaterial on the basis of such a structure. The research presents the possibility of forming the type II ENZ metamaterial inside the two kinds of propagating light waves for which the amplitude decays from the boundary and the phase fronts move away from and towards the boundary of the metamaterial, respectively. The interaction between Gaussian light beams and metamaterials with extremal characteristics is theoretically investigated. The prospect of the practical application of these media is considered.

  16. Comparison of parameters influencing the behavior of concentration of nitrates and phosphates during different extreme rainfall-runoff events in small watersheds

    Directory of Open Access Journals (Sweden)

    J. Moravcová

    2013-10-01

    Full Text Available The behavior of solute concentrations during storm events is completely different from their behaviour under normal conditions, and very often results in hysteresis. This study aim is to explore the relationship between the biogeochemical and hydrological parameters describing natural conditions and the reciprocal interactions between changes in concentration of selected indicators of water quality in water and the discharge dynamics during different types of extreme rainfall-runoff events in the Jenínský stream and the Kopaninský stream catchment (Czech Republic. The relationship between concentrations and runoffs is explained by concentration-discharge hysteretic loops. As the statistical method used for cross analyzing the impact of the parameters there was chosen the RDA analysis. The relationships between the particular parameters were examined separately by conditions of spring snow melt and summer storm events. The results than confirmed the very strong relationship between parameters describing water quality and percentage of stable parts of the catchment and also of infiltration vulnerable sites.

  17. Runoff characteristics and nutrient loss mechanism from plain farmland under simulated rainfall conditions.

    Science.gov (United States)

    Liu, Ruimin; Wang, Jiawei; Shi, Jianhan; Chen, Yaxin; Sun, Chengchun; Zhang, Peipei; Shen, Zhenyao

    2014-01-15

    In recent years, nonpoint source (NPS) pollution has become the main contributor to water quality problems. Research on nitrogen (N) and phosphorus (P) losses from farmland and the factors that influence these losses is very meaningful both for increasing the crop yield and for improving environmental water quality. To explore the mechanism by which N and P are lost from farmland in the North China Plain (NCP), 16 simulated rainfalls were conducted in 14 experimental fields (each of which had different conditions) in the NCP from July to August in 2010. The results showed that the rainfall intensity, the antecedent soil moisture content, and the vegetation cover status were the main factors that affected the surface runoff in the NCP. The runoff volume increased with the increasing rainfall intensity and the increasing soil moisture content, and decreased with the increasing vegetation cover. These factors also significantly affected the losses of P and N. The losses of P and N were positively correlated with the rainfall intensity and the antecedent soil moisture content, and negatively correlated with the vegetation cover. A longer and more intense rainfall resulted in a higher loss of N and P. Dissolved nitrogen was the predominant form of N loss. For phosphorous, the predominant loss form was greatly influenced by the rainfall intensity, the vegetation cover, and the antecedent soil moisture content. Most of phosphorus existed as dissolved phosphorus in Baizhuang (BZ) and as particulate phosphorus in Tangcheng (TC) and Fentai (FT). The minimum requirements for runoff occurrence in experimental regions were a rainfall depth of 5.1mm, a rainfall intensity of 50mm/h, and an antecedent soil moisture of approximately 29.6%.

  18. Runoff characteristics and washoff loads from rainfall-simulation experiments on a street surface and a native pasture in the Denver metropolitan area, Colorado

    Science.gov (United States)

    Mustard, Martha H.; Ellis, Sherman R.; Gibbs, Johnnie W.

    1987-01-01

    Rainfall simulation studies were conducted in conjunction with the Denver Regional Urban Runoff Program to: (1) Compare runoff quantity and quality from two different intensities of rainfall on impervious plots having identical antecedent conditions, (2) document a first flush of constituent loads in runoff from l,000-square-foot street-surface plots, (3) compare runoff characteristics from a street surface subjected to simulated rainfall with those from a 69-acre urban basin of mixed land use subjected to natural rainfall, (4) perform statistical analysis of constituent loads in the runoff with several independent variables, and (5) compare the quantity and quality of runoff from 400-square-foot plots of native grasses used for pasture and subjected to simulated rainfall with that from a 405-acre basin covered with native grasses used for pasture and subjected to natural rainfall. The rainfall simulations conducted on the street surface showed that higher intensity simulated rainfall produced a higher percentage of runoff than lower intensity rainfall. A first flush of constituent loads occurred for most constituents in the runoff from most rainfall simulations on the street surface; however, a first flush did not occur in the runoff from simulated rainfall on the pasture. The event mean concentrations of constituents in the runoff from simulated storms on the street surface were generally much smaller than the event mean concentrations of constituents in the runoff from an adjacent urban basin. Analysis of the data from the rainfall simulations on a street surface indicates that intensity of rainfall and total rainfall are important variables determining constituent loads. The design of the experiment was such that intensity of rainfall and total rainfall were highly correlated, thus precluding the development of useful regression equations to predict washoff loads. The quality of runoff from the simulated rainfall on the pasture was influenced by the disturbed

  19. Imaging characteristics of the Extreme Ultraviolet Explorer microchannel plate detectors

    Science.gov (United States)

    Vallerga, J. V.; Kaplan, G. C.; Siegmund, O. H. W.; Lampton, M.; Malina, R. F.

    1989-01-01

    The Extreme Ultraviolet Explorer (EUVE) satellite will conduct an all-sky survey over the wavelength range from 70 A to 760 A using four grazing-incidence telescopes and seven microchannel-plate (MCP) detectors. The imaging photon-counting MCP detectors have active areas of 19.6 cm2. Photon arrival position is determined using a wedge-and-strip anode and associated pulse-encoding electronics. The imaging characteristics of the EUVE flight detectors are presented including image distortion, flat-field response, and spatial differential nonlinearity. Also included is a detailed discussion of image distortions due to the detector mechanical assembly, the wedge-and-strip anode, and the electronics. Model predictions of these distortions are compared to preflight calibration images which show distortions less than 1.3 percent rms of the detector diameter of 50 mm before correction. The plans for correcting these residual detector image distortions to less than 0.1 percent rms are also presented.

  20. Precipitation-runoff relations and water-quality characteristics at edge-of-field stations, Discovery Farms and Pioneer Farm, Wisconsin, 2003-8

    Science.gov (United States)

    Stuntebeck, Todd D.; Komiskey, Matthew J.; Peppler, Marie C.; Owens, David W.; Frame, Dennis R.

    2011-01-01

    A cooperative study between the U.S. Geological Survey, the University of Wisconsin (UW)-Madison Discovery Farms program (Discovery Farms), and the UW-Platteville Pioneer Farm program (Pioneer Farm) was developed to identify typical ranges and magnitudes, temporal distributions, and principal factors affecting concentrations and yields of sediment, nutrients, and other selected constituents in runoff from agricultural fields. Hydrologic and water-quality data were collected year-round at 23 edge-of-field monitoring stations on 5 privately owned Discovery Farms and on Pioneer Farm during water years 2003-8. The studied farms represented landscapes, soils, and farming systems typical of livestock farms throughout southern Wisconsin. Each farm employed a variety of soil, nutrient, and water-conservation practices to help minimize sediment and nutrient losses from fields and to improve crop productivity. This report summarizes the precipitation-runoff relations and water-quality characteristics measured in edge-of-field runoff for 26 "farm years" (aggregate years of averaged station data from all 6 farms for varying monitoring periods). A relatively wide range of constituents typically found in agricultural runoff were measured: suspended sediment, phosphorus (total, particulate, dissolved reactive, and total dissolved), and nitrogen (total, nitrate plus nitrite, organic, ammonium, total Kjeldahl and total Kjeldahl-dissolved), chloride, total solids, total suspended solids, total volatile suspended solids, and total dissolved solids. Mean annual precipitation was 32.8 inches for the study period, about 3 percent less than the 30-year mean. Overall mean annual runoff was 2.55 inches per year (about 8 percent of precipitation) and the distribution was nearly equal between periods of frozen ground (54 percent) and unfrozen ground (46 percent). Mean monthly runoff was highest during two periods: February to March and May to June. Ninety percent of annual runoff occurred

  1. Epidemiological characteristics of lower extremity cellulitis after a typhoon flood.

    Directory of Open Access Journals (Sweden)

    Pei-Chen Lin

    Full Text Available OBJECTIVE: The flood after a typhoon may lead to increase in patients with cellulitis of lower limbs. However, the microbiological features of these cases are rarely reported. We conducted a study of patients with lower extremity cellulitis after a typhoon followed in southern Taiwan to study the risk factors of cellulitis and the bacteriological features of the patients. METHODS: We reviewed all the medical records of cellulitis at emergency departments of two teaching hospitals in southern Taiwan 30 days before and after the landing of Typhoon Morakot and collected data on the demographic and bacteriological characteristics. In addition, we evaluated the relationship between the daily number of patients and the rainfall in the Tainan area. RESULTS: The number of cellulitis patients increased from 183 to 344 during the 30-day period after the typhoon. The number peaked in the third and fourth days and lasted for 3 weeks. The proportion of patients with water immersion of the affected limb was higher after the typhoon (6% vs. 37%, odds ratio [OR]: 9.0, 95% Confidence interval [CI]: 4.7-17.2. We found cultures from the infected limbs with immersion had more polymicrobial (73% vs. 26%, OR: 7.8, 95% CI: 3.2-19.2 and Gram-negative bacilli infection (86% vs. 34%, OR: 11.8, 95% CI: 4.1-34.5. CONCLUSIONS: Flood arose from Typhoon Morakot caused increases in cellulitis patients, which lasted for 3 weeks. Antibiotic treatment that were effective to both Gram-positive cocci and Gram-negative bacilli are recommended for patients with limbs emerged in the water.

  2. Characteristics of the extreme rainfall event and consequent flash floods in W Slovenia in September 2007

    Directory of Open Access Journals (Sweden)

    S. Rusjan

    2009-06-01

    Full Text Available During a weather front that passed over large parts of Slovenia on 18.9.2007, extreme rainfall events were triggered causing several severe flash floods with six casualties. Out of 210 municipalities in Slovenia, 60 were reporting flood damages, and the total economic flood damage was later estimated at close to 200 million Euro; highest damage was claimed by Železniki municipality in NW Slovenia. The main purpose of the study presented in this paper was to put together available meteorological and hydrological data in order to get better insight into temporal and spatial dynamics and variability of the flash flood event along the Selška Sora River flowing through the town of Železniki. The weather forecast by the Environmental Agency of the Republic of Slovenia (ARSO lead to early warning of floodings but has underestimated rainfall amounts by a factor of 2. Also meteorological radar underestimated ground rainfall as much as by 50%. During that day, in many rainfall gauging stations operated by ARSO in the area under investigation, extreme rainfall amounts were measured, e.g. 303 mm in 24 h or 157 mm in 2 h. Some of the measured rainfall amounts were the highest registered amounts in Slovenia so far. Statistical analysis using Gumble distribution was performed and rainfall return periods were estimated. When assessing rainfall return periods, a question of the sampling error as a consequence of short rainfall records used was raised. Furthermore, measured rainfall data were used to reconstruct hydrographs on selected water stations along the Selška Sora River. The cumulative areal precipitation for the Selška Sora River catchment upstream of Železniki amounted to 219 mm, while the modeled effective precipitation used to simulate the hydrograph peak was only 57 mm. The modeled direct runoff coefficient therefore amounts to 0.26. Surprisingly low value is mainly caused by the applied unit hydrograph method that seeks to meet the peak

  3. [Hydrochemical characteristics and evolution of runoff at Qiyi glacier, Qilian Mts].

    Science.gov (United States)

    Wu, Xiao-Bo; Li, Quan-Lian; Song, Gao-Ju; He, Jian-Qiao; Jiang, Xi

    2008-03-01

    Glacier ice, supraglacier stream water, ice-marginal stream water, proglacier stream water samples were collected at Qiyi glacier located in central part of Qilian Mountain 2006-06 - 2006-07. Major ions concentration, pH and EC were analyzed. The results indicate that pH varies from 8.05 to 8.79, and EC 32.4 - 134.4 microS cm(-1). The order of major ions concentration in differed water is: supraglacier stream water SO4(2-) > Cl(-) > NO3(-), Ca(2+) > Mg(2+) > Na(+) > K(+) mainly comes from carbonate weathering,and some is from sulfate dissolution. Concentrations of Mg(2+) and K(+) increase quicker than Na(+) and Ca(2+) in proglacier stream and ice-margin stream that is inverse to their abundance in crust. The spatial characteristic of ions concentration is controlled by the process of water-rock and temporal change is hydrological factors.

  4. Characteristics of Runoff Changes in the Minjiang River Basin from 1960 to 2006%19602006年闽江流域径流演变特征

    Institute of Scientific and Technical Information of China (English)

    陈莹; 陈兴伟; 尹义星

    2011-01-01

    In this paper, the runoff change in the Minjiang River Basin is investigated and its re- sponse to main meteorological elements is explored based on the monthly runoff, precipitation and temperature data from 1960 to 2006. The adopted methods include Mann-Kendall trend analysis and empirical mode decomposition. The results are as follows: First, the annual runoff in the Minjiang River Basin is on the increase, and the runoff in the non-flood season contributes a lot to this increase. The trend of autumn and winter runoff is upward for most of the time. The runoff in summer has been on the increase while the runoff in spring on the decrease since the 1990s. Sec- ond, both precipitation and temperature of the basin increased for the study period, especially for temperature series. And the upward trend of runoff is more evident than that of precipitation. Third, multi-scale characteristics of runoff and precipitation have been detected and the periods of precipitation are longer than those of the runoff. The amplitude of decadal variability in the pre- cipitation and runoff series has been weakened while the amplitude of inter-annual variability has been intensified since the 1980s. The paper revealed that the reason for runoff increase to be more evident than precipitation increase is that the evaportranspiration is on the decrease and precipita- tion intensity is on the increase in the basin. What' s more, the influences of underlying surface also contribute to runoff increase.%基于闽江流域1960--2006年逐月径流、降水以及气温等资料,应用Mann—KendaⅡ趋势分析、经验模态分解等方法,探讨流域径流演变规律及其对气象要素变化的响应特征。结果表明:①闽江流域年径流呈上升趋势,其上升主要来自非汛期径流的贡献;秋季和冬季径流始终以上升趋势为主;夏季径流20世纪90年代以来呈上升趋势,而春季径流则呈现下降趋势。②流

  5. Characteristics of runoff and sediment generation of forest vegetation on a hill slope by use of artificial rainfall apparatus

    Institute of Scientific and Technical Information of China (English)

    LI Xiang; NIU Jian-zhi; LI Jiao; XIE Bao-yuan; HAN Yi-ni; TAN Jing-ping; ZHANG Ying-hu

    2012-01-01

    We studied the impact of forest vegetation on soil erosion,surface runoff,and sediment generation by using field simulated rainfall apparatus.We measured runoff and sediment generation of five 4.5 × 2.1m runoff plots (a bare soil as a control; two Pinus tabulaeformis forest plots and two Platycladus orientalis forest with row spacing of 1m × 1m and 1.5 m × 1.5 m,respectively) in Beijing Jiu Feng National Forest Park under three rainfall intensities (0.42,0.83,1.26 mm per minute).Forest vegetation significantly reduced soil erosion and sediment yield.Mean total runoff volume in the four tree stand plots was 93% of that in the control plot,demonstrating the limited effectiveness of forest vegetation in runoff control.With increasing rainfall intensity,runoff reduction in forest plots declined from 28.32% to 2.1%.Similar trends in runoff coefficient and the relationship between runoffvolume and rainfall duration was observed.Mean total sediment yield and mean sediment yield reduction rate under different treatments was 55.05% and 43.17% of those in the bare soil control plot,respectively.Rainfall intensity played an important role in runoffand sediment generation processes,and had a greater impact on runoff than on soil erosion and sediment generation.When considering several factors in runoff and sediment transport processes,the P.tabulaeform plot with row spacing at 1 × 1 m had a greater effect on soil and water conservation than did other forested plots.

  6. Characteristics of extreme ultraviolet emission from high-Z plasmas

    Science.gov (United States)

    Ohashi, H.; Higashiguchi, T.; Suzuki, Y.; Kawasaki, M.; Suzuki, C.; Tomita, K.; Nishikino, M.; Fujioka, S.; Endo, A.; Li, B.; Otsuka, T.; Dunne, P.; O'Sullivan, G.

    2016-03-01

    We demonstrate the extreme ultraviolet (EUV) and soft x-ray sources in the 2 to 7 nm spectral region related to the beyond EUV (BEUV) question at 6.x nm and the water window source based on laser-produced high-Z plasmas. Resonance emission from multiply charged ions merges to produce intense unresolved transition arrays (UTAs), extending below the carbon K edge (4.37 nm). An outline of a microscope design for single-shot live cell imaging is proposed based on high-Z plasma UTA source, coupled to multilayer mirror optics.

  7. Stormwater runoff pollutant loading distributions and their correlation with rainfall and catchment characteristics in a rapidly industrialized city.

    Science.gov (United States)

    Li, Dongya; Wan, Jinquan; Ma, Yongwen; Wang, Yan; Huang, Mingzhi; Chen, Yangmei

    2015-01-01

    Fast urbanization and industrialization in developing countries result in significant stormwater runoff pollution, due to drastic changes in land-use, from rural to urban. A three-year study on the stormwater runoff pollutant loading distributions of industrial, parking lot and mixed commercial and residential catchments was conducted in the Tongsha reservoir watershed of Dongguan city, a typical, rapidly industrialized urban area in China. This study presents the changes in concentration during rainfall events, event mean concentrations (EMCs) and event pollution loads per unit area (EPLs). The first flush criterion, namely the mass first flush ratio (MFFn), was used to identify the first flush effects. The impacts of rainfall and catchment characterization on EMCs and pollutant loads percentage transported by the first 40% of runoff volume (FF40) were evaluated. The results indicated that the pollutant wash-off process of runoff during the rainfall events has significant temporal and spatial variations. The mean rainfall intensity (I), the impervious rate (IMR) and max 5-min intensity (Imax5) are the critical parameters of EMCs, while Imax5, antecedent dry days (ADD) and rainfall depth (RD) are the critical parameters of FF40. Intercepting the first 40% of runoff volume can remove 55% of TSS load, 53% of COD load, 58% of TN load, and 61% of TP load, respectively, according to all the storm events. These results may be helpful in mitigating stormwater runoff pollution for many other urban areas in developing countries.

  8. Stormwater Runoff Pollutant Loading Distributions and Their Correlation with Rainfall and Catchment Characteristics in a Rapidly Industrialized City

    Science.gov (United States)

    Li, Dongya; Wan, Jinquan; Ma, Yongwen; Wang, Yan; Huang, Mingzhi; Chen, Yangmei

    2015-01-01

    Fast urbanization and industrialization in developing countries result in significant stormwater runoff pollution, due to drastic changes in land-use, from rural to urban. A three-year study on the stormwater runoff pollutant loading distributions of industrial, parking lot and mixed commercial and residential catchments was conducted in the Tongsha reservoir watershed of Dongguan city, a typical, rapidly industrialized urban area in China. This study presents the changes in concentration during rainfall events, event mean concentrations (EMCs) and event pollution loads per unit area (EPLs). The first flush criterion, namely the mass first flush ratio (MFFn), was used to identify the first flush effects. The impacts of rainfall and catchment characterization on EMCs and pollutant loads percentage transported by the first 40% of runoff volume (FF40) were evaluated. The results indicated that the pollutant wash-off process of runoff during the rainfall events has significant temporal and spatial variations. The mean rainfall intensity (I), the impervious rate (IMR) and max 5-min intensity (Imax5) are the critical parameters of EMCs, while Imax5, antecedent dry days (ADD) and rainfall depth (RD) are the critical parameters of FF40. Intercepting the first 40% of runoff volume can remove 55% of TSS load, 53% of COD load, 58% of TN load, and 61% of TP load, respectively, according to all the storm events. These results may be helpful in mitigating stormwater runoff pollution for many other urban areas in developing countries. PMID:25774922

  9. EIG - II. Intriguing characteristics of the most extremely isolated galaxies

    Science.gov (United States)

    Spector, O.; Brosch, N.

    2017-07-01

    We have selected a sample of 41 extremely isolated galaxies (EIGs) from the local Universe using both optical and H i Arecibo Legacy Fast ALFA survey redshifts. Narrow-band H α and wide-band imaging along with public data were used to derive star formation rates (SFRs), star formation histories and morphological classifications for the EIGs. We have found that the extreme isolation of the EIGs does not affect considerably their star formation compared to field galaxies. EIGs are typically 'blue cloud' galaxies that fit the 'main sequence of star-forming galaxies' and may show asymmetric star formation and strong compact star-forming regions. We discovered surprising environmental dependences of the H i content, {M} _{H I}, and of the morphological type of EIGs; the most isolated galaxies (of subsample EIG-1) have lower {M} _{H I} on average (with 2.5σ confidence) and a higher tendency to be early types (with 0.94 confidence) compared to the less isolated galaxies of subsample EIG-2. To the best of our knowledge, this is the first study that finds an effect in which an isolated sample shows a higher fraction of early types compared to a less isolated sample. Both early-type and late-type EIGs follow the same colour-to-M*, SFR-to-M* (main sequence) and {M} _{H I}-to-M* relations. This indicates that the mechanisms and factors governing star formation, colour and the {M} _{H I}-to-M* relation are similar in early-type and late-type EIGs, and that the morphological type of EIGs is not governed by their {M} _{H I} content, colour or SFR.

  10. 城市雨水径流水质特征及应对方法%Water Quality Characteristics of Urban Runoff and Its Solution

    Institute of Scientific and Technical Information of China (English)

    陈水平; 付国楷; 喻晓琴; 徐官安; 雷莉

    2013-01-01

    Based on the research of non-point source pollution caused by urban runoff at home and abroad ,a summa-ry was made on runoff quality characteristics ,their influencing factors ,first flush situation and the flow control of initial rainwater runoff of city roads ,roofs and green lands .Generally ,initial rainwater runoff has higher concentra-tion of pollutants ,while its concentration values of COD ,TSS ,TN and TP are similar to that of urban sewerage . It’s of great significance for water environment protection to handle this part of the flow .%  在研究国内外有关雨水径流非点源污染研究成果的基础上,综述了城市道路、屋面、绿地雨水的水质特征及其影响因素,初期冲刷情况,以及初期雨水径流的截流控制应对方法。降雨的初期径流普遍有较高的污染物浓度,COD、T SS、T N、T P浓度值与城市污水浓度相近,截流处理这部分流量对保护水体环境意义重大。

  11. Small-scale characteristics of extremely high latitude aurora

    Directory of Open Access Journals (Sweden)

    J. A. Cumnock

    2009-09-01

    Full Text Available We examine 14 cases of an interesting type of extremely high latitude aurora as identified in the precipitating particles measured by the DMSP F13 satellite. In particular we investigate structures within large-scale arcs for which the particle signatures are made up of a group of multiple distinct thin arcs. These cases are chosen without regard to IMF orientation and are part of a group of 87 events where DMSP F13 SSJ/4 measures emissions which occur near the noon-midnight meridian and are spatially separated from both the dawnside and duskside auroral ovals by wide regions with precipitating particles typical of the polar cap. For 73 of these events the high-latitude aurora consists of a continuous region of precipitating particles. We focus on the remaining 14 of these events where the particle signatures show multiple distinct thin arcs. These events occur during northward or weakly southward IMF conditions and follow a change in IMF By. Correlations are seen between the field-aligned currents and plasma flows associated with the arcs, implying local closure of the FACs. Strong correlations are seen only in the sunlit hemisphere. The convection associated with the multiple thin arcs is localized and has little influence on the large-scale convection. This also implies that the sunward flow along the arcs is unrelated to the overall ionospheric convection.

  12. 1956-2010年淮河流域极端径流的时空变化及统计模拟%Temporal and spatial variations and statistical models of extreme runoff in Huaihe River Basin during 1956-2010

    Institute of Scientific and Technical Information of China (English)

    XIA Jun; DU Hong; ZENG Sidong; SHE Dunxian; ZHANG Yongyong; YAN Ziqi; YE Yan

    2012-01-01

    Based on the daily runoff data from 20 hydrological stations above the Bengbu Sluice in the Huaihe River Basin during 1956-2010,run test,trend test and Mann-Kendall test are used to analyze the variation trend of annual maximum runoff series.The annual maximum series (AM) and peaks over threshold series (POT) are selected to describe the extreme distributions of generalized extreme value distribution (GEV) and generalized Pareto distribution (GPD).Temporal and spatial variations of extreme runoff in the Huaihe River Basin are analyzed.The results show that during the period 1956-2010 in the Huaihe River Basin,annual maximum runoff at 10 stations have a decreasing trend,while the other 10 stations have an unobvious increasing trend.The maximum runoff events almost occurred in the flood period during the 1960s and 1970s.The extreme runoff events in the Huaihe River Basin mainly occurred in the mainstream of the Huaihe River,Huainan mountainous areas,and Funiu mountainous areas.Through Kolmogorov-Smirnov test,GEV and GPD distributions can be well fitted with AM and POT series respectively.Percentile value method,mean excess plot method and certain numbers of peaks over threshold method are used to select threshold,and it is found that percentile value method is the best of all for extreme runoff in the Huaihe River Basin.%@@

  13. [Characteristics of soil phosphorus runoff under different rainfall intensities in the typical vegetable plot of Taihu Basin].

    Science.gov (United States)

    Yang, Li-Xia; Yang, Gui-Shan; Yuan, Shao-Feng; Wu, Ye

    2007-08-01

    Experiments of field runoff plots, which were conducted at vegetable plots in Hongsheng town of Wuxi city--the typical region of Taihu Basin, were designed to assess the effects of different rainfall intensities on soil phosphorus runoff loss from vegetable plots by artificial rainfall simulations. Results showed that there was a relationship of power function between initial runoff-generation time and rainfall intensity. Runoff amount slowly increased under small rainfall intensity, but rapidly increased with rainfall intensity increase. The concentrations of total phosphorus (TP) and particulate phosphorus (PP) were higher at the early stage, then gradually decreased with time and finally reached a comparative steady stage under 0.83, 1.17 and 1.67 mm x min(-1). However they indicated no obvious trend except wavy undulation under 2.50 mm x min(-1). In the course of rainfall-runoff, dissolved phosphorus (DP) gently varied and accounted for 20% - 32% of TP. PP was 68% - 80% of TP and its change trend was consistent with TP. Therefore, PP was main loss form of soil phosphorus runoff. Comparison of different phosphorous loss rate under different rainfall intensities suggested that loss rate of TP and DP under 2.50 mm x min(-1) was 20 times and 33 times higher than that under 0.83 mm x min(-1), which showed that loss rate of PP and DP increased with the increase of rainfall intensities. Results indicated that lots of inorganic dissolved phosphorus (DIP) of phosphorous fertilizer was discharged into water environment by using fertilizer in soil surface before rainfall, which increased loss of DP and greatly aggravated degree of water eutrophication.

  14. Runoff and soil loss characteristics on loess slopes covered with aeolian sand layers of different thicknesses under simulated rainfall

    Science.gov (United States)

    Zhang, F. B.; Bai, Y. J.; Xie, L. Y.; Yang, M. Y.; Li, Z. B.; Wu, X. R.

    2017-06-01

    In the Wind-Water Erosion Crisscross Region of the northern Loess Plateau, parts of loess slopes have been covered by layers of aeolian sand of different thicknesses. Knowledge of soil erosion processes and magnitudes on these slopes is essential to understanding the coupled water-wind erosion processes and to address the resulting downstream coarse sediment problems in the Yellow River. Simulated rainfall (intensity 90 mm h-1) was performed to explore the effects of sand layer thickness on runoff and soil loss from loess slopes covered with different sand layer thicknesses (0, 0.5, 2, 5, 10, 15, 20, and 25 cm). Initial runoff time increased with increasing sand layer thickness, with greater changes occurring for the increases in the thinner (0-5 cm) than for the thicker layers (5-25 cm). Total runoff yield from the sand-covered loess slopes was 18%-55% lower than from the uncovered loess slope and decreased with increasing sand layer thickness. In contrast, total sediment yield was up to 14 times greater from the sand-covered loess slopes than from the uncovered loess slope and rapidly increased with increasing sand layer thickness. During the rainstorm, runoff and soil loss rates exhibited unimodal distributions, and they were related by a positive linear function, both before and after the maximum soil loss rate, that had a high determination coefficient (R2 > 0.8, p qualitative change in runoff and sediment production modes, appeared to be in the range of 5-10 cm. These results indicated that the thickness of the sand layer on the loess slope significantly influenced runoff and sediment production processes and mechanisms. These effects should be considered when assessing and predicting soil losses in this region and from similar slopes elsewhere.

  15. A modelling approach to assess the hydrological response of small Mediterranean catchments to the variability of soil characteristics in a context of extreme events

    Directory of Open Access Journals (Sweden)

    C. Manus

    2008-09-01

    Full Text Available This paper presents a modeling study aiming at quantifying the possible impact of soil characteristics on the hydrological response of small ungauged catchments in a context of extreme events. The study focuses on the September 2002 event in the Gard region (South-Eastern France, which led to catastrophic flash-floods. The proposed modeling approach is able to take into account rainfall variability and soil profiles variability. Its spatial discretization is determined using Digital Elevation Model (DEM and a soil map. The model computes infiltration, ponding and vertical soil water distribution, as well as river discharge. The model is set up without any calibration and the soil parameter specification is based on an existing soil database. To perform the simulations, radar rainfall estimations are used at a 1 km2 and 5 min resolution. To specify the soil hydraulic properties, two types of pedotransfer function (PTF are compared. It is shown that the PTF including information about soil structure reflects better the spatial variability that can be encountered in the field. The study is focused on four small ungauged catchments of less than 10 km2, which experienced casualties. Simulated specific peak discharges are found to be in agreement with estimations from a post-event in situ investigation. Examining the dynamics of simulated infiltration and saturation degrees, two different behaviors are shown which correspond to different runoff production mechanisms that could be encountered within catchments of less than 10 km2. They produce simulated runoff coefficients that evolve in time and highlight the variability of the infiltration capacity of the various soil types. Therefore, we propose a cartography distinguishing between areas prone to saturation excess and areas prone only to infiltration excess mechanisms. The questions raised by this modeling study will be useful to improve field observations, aiming at

  16. 密云水库上游流域次降雨坡面产流产沙特征%Characteristics of runoff and sediment during individual rainfall in upper area of Miyun Reservoir

    Institute of Scientific and Technical Information of China (English)

    何杨洋; 王晓燕; 段淑怀

    2015-01-01

    Rainfall is the main factor driving surface runoff and soil erosion. In order to clarify the characteristics of individual rainfall runoff and soil erosion in upper area of Miyun Reservoir and the impact of rainfall depth and intensity on surface runoff and soil erosion under different land use types with various slopes, data on rainfall runoff and soil erosion of 213 individual rainfalls in experimental plots of Shixia watershed from 2006 to 2010 were collected and analyzed. Clustering analysis, variance analysis and correlation analysis was conducted, and the results showed that: 1) The critical period to implement soil and water conservation measures was in July and August of each year. When the rainfall depth of 24h was larger than 10 mm, the water and soil conservation measures should be adopted; 2) In upper area of Miyun Reservoir, the rainfall could be divided into 3 different types according to rainfall depth and intensity. The main rainfall type in this region was the low precipitation with low intensity, although it couldn’t drive soil loss substantially. Across the land-uses of bare land, arable land and forestland, high depth but medium intensity rainfall is always the major reason that should be responsible for surface runoff and soil erosion. While, in the grass land, medium depth but high intensity rainfall was the main type causing surface runoff and soil erosion; 3) The runoff depth and sediment yield of bare land was always the highest among different land-use patterns. For the medium precipitation with high intensity, forestland can greatly reduce the runoff in comparison with bare land. While, for low precipitation with low intensity and high precipitation but with medium intensity, the runoff reduction efficiency in the arable land was very low, while the efficiency was extremely high in the grassland and forestland. The reduction of sediment had not shown any significant difference across these land-uses; 4) The relationship between runoff

  17. Runoff estimation in residencial area

    Directory of Open Access Journals (Sweden)

    Meire Regina de Almeida Siqueira

    2013-12-01

    Full Text Available This study aimed to estimate the watershed runoff caused by extreme events that often result in the flooding of urban areas. The runoff of a residential area in the city of Guaratinguetá, São Paulo, Brazil was estimated using the Curve-Number method proposed by USDA-NRCS. The study also investigated current land use and land cover conditions, impermeable areas with pasture and indications of the reforestation of those areas. Maps and satellite images of Residential Riverside I Neighborhood were used to characterize the area. In addition to characterizing land use and land cover, the definition of the soil type infiltration capacity, the maximum local rainfall, and the type and quality of the drainage system were also investigated. The study showed that this neighborhood, developed in 1974, has an area of 792,700 m², a population of 1361 inhabitants, and a sloping area covered with degraded pasture (Guaratinguetá-Piagui Peak located in front of the residential area. The residential area is located in a flat area near the Paraiba do Sul River, and has a poor drainage system with concrete pipes, mostly 0.60 m in diameter, with several openings that capture water and sediments from the adjacent sloping area. The Low Impact Development (LID system appears to be a viable solution for this neighborhood drainage system. It can be concluded that the drainage system of the Guaratinguetá Riverside I Neighborhood has all of the conditions and characteristics that make it suitable for the implementation of a low impact urban drainage system. Reforestation of Guaratinguetá-Piagui Peak can reduce the basin’s runoff by 50% and minimize flooding problems in the Beira Rio neighborhood.

  18. Individual and coupled influences of AMO and ENSO on regional precipitation characteristics and extremes

    Science.gov (United States)

    Goly, Aneesh; Teegavarapu, Ramesh S. V.

    2014-06-01

    Understanding the influences of Atlantic multidecadal oscillation (AMO) and El Niño southern oscillation (ENSO) on regional precipitation extremes and characteristics in the state of Florida is the focus of this study. Exhaustive evaluations of individual and combined influences of these oscillations using, descriptive indices-based assessment of statistically significant changes in rainfall characteristics, identification of spatially varying influences of oscillations on dry and wet spell transition states, antecedent precipitation prior to extreme events, intraevent temporal distribution of precipitation and changes in temporal occurrences of extremes including dry/wet cycles are carried out. Rain gage and gridded precipitation data analysis using parametric hypothesis tests confirm statistically significant changes in the precipitation characteristics from one phase to another of each oscillation and also in coupled phases. Spatially nonuniform and uniform influences of AMO and ENSO, respectively, on precipitation are evident. AMO influences vary in peninsular and continental parts of Florida and the warm (cool) phase of AMO contributes to increased precipitation extremes during wet (dry) season. The influence of ENSO is confined to dry season with El Niño (La Niña) contributing to increase (decrease) in extremes and total precipitation. Wetter antecedent conditions preceding daily extremes are dominant in AMO warm phase compared to the cool and are likely to impact design floods in the region. AMO influence on dry season precipitation extremes is noted for ENSO neutral years. The two oscillations in different phases modulate each other with seasonal and spatially varying impacts and implications on flood control and water supply in the region.

  19. Changing characteristics of extreme wet and dry spells of Indian monsoon rainfall

    Science.gov (United States)

    Vinnarasi, R.; Dhanya, C. T.

    2016-03-01

    Modeling of extreme events and its dynamic behavior have always been an intriguing topic. Increase in the magnitude and frequency of extreme events has widely been reported in recent decades, which is attributed to abrupt changes in climate. Numerous studies on extreme Indian monsoon characteristics, using a coarse-resolution data set, have pointed out significant changes in heavy precipitation pattern over India. However, these studies differ in their conclusions, emphasizing the need for a fine-resolution analysis. The present study aims to analyze the spatiotemporal variations and trends in the extreme (wet and dry) Indian monsoon precipitation, using 0.25° × 0.25° high-resolution gridded data for a period of 113 years (1901-2013). Significant increase in the maximum intensity of rainfall and spatial heterogeneity is observed over the past half century. In addition, significant negative trends in wet spell durations and positive trends in dry spell durations are observed over wet regions; whereas contrasting trends are observed over dry regions. A shift in the frequency distribution of extreme events during the monsoon period is also noticed. The 50 year return level of maximum intensity clearly shows positive trends over the past century. Though characteristics of extremes are observed to be highly localized, apparent signs of wet regions turning drier and dry regions turning wetter are obtained. A comprehensive insight into different characteristics (intensity, spell, onset, and frequency) of Indian monsoon extremes is provided, which will help in effective water resources management and flood/drought hazard preparedness.

  20. Comparison of extreme precipitation characteristics between the Ore Mountains and the Vosges Mountains (Europe)

    Science.gov (United States)

    Minářová, Jana; Müller, Miloslav; Clappier, Alain; Kašpar, Marek

    2017-08-01

    Understanding the characteristics of extreme precipitation events (EPEs) not only helps in mitigating the hazards associated with it but will also reduce the risks by improved planning based on the detailed information, and provide basis for better engineering decisions which can withstand the recurring and likely more frequent events predicted in future in the context of global climate change. In this study, extremity, temporal and spatial characteristics, and synoptic situation of the 54 EPEs that occurred during 1960-2013 were compared between two low mountain ranges situated in Central Europe: the Ore Mountains (OM) and Vosges Mountains (VG). The EPEs were defined using the Weather Extremity Index, which quantifies the extremity, duration, and spatial extent of events. Comparative analysis of EPE characteristics showed that in both regions the EPEs were mostly short (lasted 1-2 days) and their seasonal occurrence significantly depended on the synoptic situation and duration of EPEs; the low was related to summer short EPEs, while zonal circulation to winter long EPEs. The EPEs were generally related to lows in OM and to troughs in VG. The lows often moved to OM from the Mediterranean area, i.e. along the Vb track. However, five EPEs in VG occurred during a low with Vb track significantly deflected westwards. The EPEs in VG affected smaller area as compared to that in OM. The comparison of EPEs between the two low mountain ranges is first of its kind and contributes to the understanding of EPE characteristics in the regions.

  1. Trends and seasonality of extreme precipitation characteristics related to mid-latitude cyclones in Europe

    Directory of Open Access Journals (Sweden)

    A. Karagiannidis

    2009-03-01

    Full Text Available An attempt is made to study the extreme precipitation characteristics, which are related to the mid-latitude cyclonic systems. Daily pluviometric data, from several stations across the continental Europe and the British Islands, are used. The covered time-period is from 1958 to 2000. Only extreme precipitation events related to mid-latitude cyclonic systems are studied, since thermal thunderstorm episodes are being excluded. To accomplish that, summer months are excluded and a strict criterion for identifying the exact episodes is set, which also defines the episode itself and the extremity of it. A decreasing trend in the cases of extreme precipitation of the European continent was found. It starts in the mid 60's and continues until the mid 70's. After that and until the end of the examined period, no significant trend was found. Seasonality of extreme precipitation cases and episodes is also studied. October and November are the two months that present the higher frequencies of such cases and episodes. In general, autumn months indicate the higher percentages of extreme precipitation, with winter and spring months to follow.

  2. Multiple runoff processes and multiple thresholds control agricultural runoff generation

    Science.gov (United States)

    Saffarpour, Shabnam; Western, Andrew W.; Adams, Russell; McDonnell, Jeffrey J.

    2016-11-01

    Thresholds and hydrologic connectivity associated with runoff processes are a critical concept for understanding catchment hydrologic response at the event timescale. To date, most attention has focused on single runoff response types, and the role of multiple thresholds and flow path connectivities has not been made explicit. Here we first summarise existing knowledge on the interplay between thresholds, connectivity and runoff processes at the hillslope-small catchment scale into a single figure and use it in examining how runoff response and the catchment threshold response to rainfall affect a suite of runoff generation mechanisms in a small agricultural catchment. A 1.37 ha catchment in the Lang Lang River catchment, Victoria, Australia, was instrumented and hourly data of rainfall, runoff, shallow groundwater level and isotope water samples were collected. The rainfall, runoff and antecedent soil moisture data together with water levels at several shallow piezometers are used to identify runoff processes in the study site. We use isotope and major ion results to further support the findings of the hydrometric data. We analyse 60 rainfall events that produced 38 runoff events over two runoff seasons. Our results show that the catchment hydrologic response was typically controlled by the Antecedent Soil Moisture Index and rainfall characteristics. There was a strong seasonal effect in the antecedent moisture conditions that led to marked seasonal-scale changes in runoff response. Analysis of shallow well data revealed that streamflows early in the runoff season were dominated primarily by saturation excess overland flow from the riparian area. As the runoff season progressed, the catchment soil water storage increased and the hillslopes connected to the riparian area. The hillslopes transferred a significant amount of water to the riparian zone during and following events. Then, during a particularly wet period, this connectivity to the riparian zone, and

  3. Analysis of Annual Runoff Variation Characteristics in Main Rivers of China%中国主要江河年径流变化特性分析

    Institute of Scientific and Technical Information of China (English)

    李东龙; 王文圣; 李跃清

    2011-01-01

    The relevant statistical properties including the characteristics of interannual variations and annual distribu-tion of runoff, trends, sudden change, periodicities for main rivers of China, are discussed based on the stochastic analy-sis. The results show that annual runoff in main rivers of China has large non-uniformity, especially larger in Haihe River Basin, Huaihe River Basin, Songhua River Basin and Liao River Basin; compared with before 1980, in addition to a little increasing non-uniformity in Huaihe River and Songhua River, the non-uniformity in main rivers of China generally de-creases) the amount of water resources in South are larger than in North but the change range and intensity of annual run-off in northern rivers are greater than in southern rivers. Compared with before 1980, in addition to a little increasing an-nual runoff in Wangjiaba station and Haerbin station, the annual runoff in main rivers of China generally decreases in var-ying degrees. The drought in downstream of Yellow River Basin and Haihe River Basin occurred nearly 60 years, and e-ven much higher than the frequency of abundance of other river basins; Affected by climate change and human activities, in addition to indistinctive increasing trend of annual runoff in Shijiao station, Wangjiaba station and Haerbin station, the annual runoff in most of China main rivers declines in the trend, especially in Haihe River Basin, Liao River Basin and the downstream of the Yellow River Basin; the sudden change points of annual runoff in the Yangtze River Basin and Pearl River Basin mainly occur between the 50's to70's in the 20th century and the beginning of the 21st century while it mainly occur in the 20's, 60's and 90's of the 20th century in Songhua River Basin; In Yellow River Basin, Haihe River Basin, Huaihe River Basin and Liao River Basin, the sudden change points of annual runoff mainly occur between the 50's and 80's in the 20th centurys there exists different periodicities in

  4. Prevalence and risk factor analysis of lower extremity abnormal alignment characteristics among rice farmers

    Directory of Open Access Journals (Sweden)

    Karukunchit U

    2015-06-01

    Full Text Available Usa Karukunchit,1,2 Rungthip Puntumetakul,1,3 Manida Swangnetr,1,4 Rose Boucaut5 1Research Center in Back, Neck, Other Joint Pain and Human Performance (BNOJPH, 2Faculty of Associated Medical Sciences, Khon Kaen University, 3School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, 4Department of Production Technology, Faculty of Technology, Khon Kaen University, Khon Kaen, Thailand; 5School of Health Sciences (Physiotherapy, iCAHE (International Centre for Allied Health Evidence, Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia Background: Rice farming activities involve prolonged manual work and human–machine interaction. Prolonged farming risk-exposure may result in lower limb malalignment. This malalignment may increase the risk of lower extremity injury and physical disabilities. However, the prevalence and factors associated with lower extremity malalignment have not yet been reported. This study aimed to investigate the prevalence and risk factors of lower extremity malalignment among rice farmers.Methods: A cross-sectional survey was conducted with 249 rice farmers. Lower extremity alignment assessment included: pelvic tilt angle, limb length equality, femoral torsion, quadriceps (Q angle, tibiofemoral angle, genu recurvatum, rearfoot angle, and medial longitudinal arch angle. Descriptive statistics were used to analyze participant characteristics and prevalence of lower extremity malalignment. Logistic regression analysis was used to identify risk factors.Results: The highest prevalence of lower extremity malalignment was foot pronation (36.14%, followed by the abnormal Q angle (34.94%, tibiofemoral angle (31.73%, pelvic tilt angle (30.52%, femoral antetorsion (28.11%, limb length inequality (22.49%, tibial torsion (21.29%, and genu recurvatum (11.24%. In females, the risk factors were abnormal Q angle, tibiofemoral angle, and genu recurvatum. Being overweight

  5. Global characteristics of extreme winters from a multi-millennial simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, B.G. [CSIRO Marine and Atmospheric Research, PO Box 1, Aspendale (Australia)

    2011-10-15

    Output from a multi-millennial simulation with the CSIRO Mark 2 coupled global climatic model has been analysed to determine the principal characteristics of extreme winters over the globe for ''present conditions''. Thus, this study is not concerned with possible changes in winter conditions associated with anthropogenically induced climatic change. Defining an extreme winter as having a surface temperature anomaly of below -2 standard deviations (sd) revealed a general occurrence rate over the globe of between 100 and 200 over a 6,000-year period of the simulation, with somewhat higher values over northwest North America. For temperature anomalies below -3 sd the corresponding occurrence rate drops to about 10. Spatial correlation studies revealed that extreme winters over regions in Europe, North America or Asia were very limited geographically, with time series of the surface temperature anomalies for these regions having mutual correlation coefficients of about 0.2. The temporal occurrence rates of winters (summers) having sd below -3 (above +3) were very asymmetric and sporadic, suggesting that such events arise from stochastic influences. Multi-year sequences of extreme winters were comparatively rare events. Detailed analysis revealed that the temporal and spatial evolution of the monthly surface temperature anomalies associated with an individual extreme winter were well replicated in the simulation, as were daily time series of such anomalies. Apart from an influence of the North Atlantic Oscillation on extreme winters in Europe, other prominent climatic oscillations were very poorly correlated with such winters. Rather modest winter temperature anomalies were found in the southern hemisphere. (orig.)

  6. A modeling approach to assess the hydrological response of small mediterranean catchments to the variability of soil characteristics in a context of extreme events

    Directory of Open Access Journals (Sweden)

    C. Manus

    2009-02-01

    Full Text Available This paper presents a modeling study aiming at quantifying the possible impact of soil characteristics on the hydrological response of small ungauged catchments in a context of extreme events. The study focuses on the September 2002 event in the Gard region (South-Eastern France, which led to catastrophic flash-floods. The proposed modeling approach is able to take into account rainfall variability and soil profiles variability. Its spatial discretization is determined using Digital Elevation Model (DEM and a soil map. The model computes infiltration, ponding and vertical soil water distribution, as well as river discharge. In order to be applicable to ungauged catchments, the model is set up without any calibration and the soil parameter specification is based on an existing soil database. The model verification is based on a regional evaluation using 17 estimated discharges obtained from an extensive post-flood investigation. Thus, this approach provides a spatial view of the hydrological response across a large range of scales. To perform the simulations, radar rainfall estimations are used at a 1 km2 and 5 min resolution. To specify the soil hydraulic properties, two types of pedotransfer function (PTF are compared. It is shown that the PTF including information about soil structure reflects better the spatial variability that can be encountered in the field. The study is focused on four small ungauged catchments of less than 10 km2, which experienced casualties. Simulated specific peak discharges are found to be in agreement with estimations from a post-event in situ investigation. Examining the dynamics of simulated infiltration and saturation degrees, two different behaviors are shown which correspond to different runoff production mechanisms that could be encountered within catchments of less than 10 km2. They produce simulated runoff coefficients that evolve in time and highlight the variability of the

  7. The effect of management team characteristics on performance and style extremity of mutual fund portfolios

    Directory of Open Access Journals (Sweden)

    Liu Qiong

    2014-01-01

    Full Text Available Purpose: Along with mutual funds’ scale and quantity expanding for our country, it is common for fund management companies hiring new managers or the original fund managers mobilizing from one to another. The high liquidity of fund managers makes different managers regroup to manage the funds that belong to the same fund management company in each fund year. The characteristics of these different management team will influence the fund performance, and also affect the earnings of the fund management company and portfolio investors. The purpose of this paper is as follows. First, evaluating the effect of management team characteristics on portfolio characteristics: risk, performance, and extremity. Second, testing the hypothesis that the ranking of mid-year performance have effect on investment style extremity and research what relationship exists between this phenomenon and management team characteristics in depth.Design/methodology/approach: On the analysis of the relationships between the management team characteristics and portfolio characteristics, a series of OLS regressions is run where the time series regression model (the factor model and cross-sectional regression are included based on using the STATA, EVIEWS and MATLAB. The validity and practicability of the model will be verified in the paper. All of the above are aimed at achieving portfolio optimization and realizing the maximization of the interests of fund management companies and investors.Findings: The main findings are as follows. Teams with more doctors or MBA (CPA and CFA hold more risky portfolios, while teams with long team tenure hold less. More members and large gender diversity have negative effect on performance, and the opposite is age diversity. Teams with more members and long tenure tend to hold less extreme style decisions, but age diversity is related to more. Besides, tournament hypothesis does exist in China investment funds industry especially when the

  8. The Runoff Abrupt Change and Periodic Characteristics of the Wudinghe River During 1933-2012%1933~2012年无定河径流突变与周期特征诊断

    Institute of Scientific and Technical Information of China (English)

    张健; 李同昇; 张俊辉; 徐象平

    2016-01-01

    River is the path of water current on the land surface that collection and transmission, and the hydro-logical response of a catchment and hydrological processes which represents the global changes of the re-sponse of the earth's surface. It is of great importance to study the runoff evolvement process. Changing rules and the influence factors in the Yellow River and would enhance sustainable development of social economy and effectively protect our environment under the reasonable utilization of river basin water resources. If we want to identify the ways of response of runoff to climate change in semi-arid region in northwest of China, the study should be first based on the grasp of the long period evolvement rules of runoff. Based on the ob-served annual runoff data of the Wudinghe River during 1945-2012, the characteristic of the abrupt change had been diagnosed by employing the methods of Moving t-test technique and Mann-Kendall and Yamamoto. The analysis showed that the annual runoff of the Wudinghe River changed abruptly in 1972, in the year since, the decrease of the runoff is about 3.55 × 108m3 on average. Precipitation decrease about 6.28%but runoff decrease about 26.62%on average after the abrupt change of the Wudinghe River runoff during 1933-2012. Although precipitation was the primary factor to affect surface water resource, precipitation was not the main reason for runoff decrease compared with human activities. Then reconstruct the sequence of natural runoff of the Wud-inghe River during 1933-2012 according to the significant correlation between precipitation and runoff before 1972. Morlet complex wavelet function was used to transform the sequence of runoff of Baijiachuan hydrolog-ic stationin of the Wudinghe River during 1933-2012. According to wavelet to analyze the periodic characteris-tics of the natural annual runoff, the results showed that the average period of annual runoff change have multi-scale periods such as 35.5 a, 22.2 a, 16.8 a, 12

  9. Characteristics of extreme climate sequences over Korea using a regional climate change scenario

    Energy Technology Data Exchange (ETDEWEB)

    Eun-Soon, I.; Kwon, W.T. [KMA, Seoul (Korea). Climate Research Lab.

    2007-07-01

    The authors investigate the characteristics and potential future change of extreme climate phenomena based on daily statistical properties. To assess the fine-scale climate change projection over Korea, an ECHO-G B2 scenario simulation has been dynamically downscaled by using the RegCM3 nesting system. Two sets of multidecadal simulations are performed for the present day (1971.2000) and future climate (2021.2050). They analyze four categories of weather spells in terms of the sequences of dry/wet and frost/hot days from the nested domain simulation of 20 km grid spacing. In the validation of the reference scenario, the model shows a reasonable performance of reproducing both observed climatological and distinct characteristics of each spell. Regarding the projected extreme climate events, the results indicate not only a significant change in frequency and intensity, but also substantial change in the fine scale detail of the regional distribution of temperature-based as well as precipitation-based extreme events. A substantial increase of hot spells is found along with increasing of maximum temperature. Longer-period frost spells are projected to decrease, whereas relatively short-period frost spells are likely to increase due to breaks of long spells by greenhouse warming. Wet spells of long periods tend to be more frequent, showing a distinct variation across regions. A recent study using the outputs of the IPCC AR4 coupled climate models also reports a significant increase of summer monsoon precipitation and a possible increase in the length of the summer monsoon period over East Asia in particular over Korea (Kripalani et al. 2006). Hence it is important to quantify the influence of greenhouse-gas-induced climate change upon the frequency and intensity of extreme events at regional scale.

  10. STATISTICAL STUDY OF STRONG AND EXTREME GEOMAGNETIC DISTURBANCES AND SOLAR CYCLE CHARACTERISTICS

    Energy Technology Data Exchange (ETDEWEB)

    Kilpua, E. K. J. [Department of Physics, University Helsinki (Finland); Olspert, N.; Grigorievskiy, A.; Käpylä, M. J.; Tanskanen, E. I.; Pelt, J. [ReSoLVE Centre of Excellence, Department of Computer Science, P.O. Box 15400, FI-00076 Aalto Univeristy (Finland); Miyahara, H. [Musashino Art University, 1-736 Ogawa-cho, Kodaira-shi, Tokyo 187-8505 (Japan); Kataoka, R. [National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518 (Japan); Liu, Y. D. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-06-20

    We study the relation between strong and extreme geomagnetic storms and solar cycle characteristics. The analysis uses an extensive geomagnetic index AA data set spanning over 150 yr complemented by the Kakioka magnetometer recordings. We apply Pearson correlation statistics and estimate the significance of the correlation with a bootstrapping technique. We show that the correlation between the storm occurrence and the strength of the solar cycle decreases from a clear positive correlation with increasing storm magnitude toward a negligible relationship. Hence, the quieter Sun can also launch superstorms that may lead to significant societal and economic impact. Our results show that while weaker storms occur most frequently in the declining phase, the stronger storms have the tendency to occur near solar maximum. Our analysis suggests that the most extreme solar eruptions do not have a direct connection between the solar large-scale dynamo-generated magnetic field, but are rather associated with smaller-scale dynamo and resulting turbulent magnetic fields. The phase distributions of sunspots and storms becoming increasingly in phase with increasing storm strength, on the other hand, may indicate that the extreme storms are related to the toroidal component of the solar large-scale field.

  11. Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic

    Science.gov (United States)

    Hansen, Brage B.; Isaksen, Ketil; Benestad, Rasmus E.; Kohler, Jack; Pedersen, Åshild Ø.; Loe, Leif E.; Coulson, Stephen J.; Larsen, Jan Otto; Varpe, Øystein

    2014-11-01

    One predicted consequence of global warming is an increased frequency of extreme weather events, such as heat waves, droughts, or heavy rainfalls. In parts of the Arctic, extreme warm spells and heavy rain-on-snow (ROS) events in winter are already more frequent. How these weather events impact snow-pack and permafrost characteristics is rarely documented empirically, and the implications for wildlife and society are hence far from understood. Here we characterize and document the effects of an extreme warm spell and ROS event that occurred in High Arctic Svalbard in January-February 2012, during the polar night. In this normally cold semi-desert environment, we recorded above-zero temperatures (up to 7 °C) across the entire archipelago and record-breaking precipitation, with up to 98 mm rainfall in one day (return period of >500 years prior to this event) and 272 mm over the two-week long warm spell. These precipitation amounts are equivalent to 25 and 70% respectively of the mean annual total precipitation. The extreme event caused significant increase in permafrost temperatures down to at least 5 m depth, induced slush avalanches with resultant damage to infrastructure, and left a significant ground-ice cover (˜5-20 cm thick basal ice). The ground-ice not only affected inhabitants by closing roads and airports as well as reducing mobility and thereby tourism income, but it also led to high starvation-induced mortality in all monitored populations of the wild reindeer by blocking access to the winter food source. Based on empirical-statistical downscaling of global climate models run under the moderate RCP4.5 emission scenario, we predict strong future warming with average mid-winter temperatures even approaching 0 °C, suggesting increased frequency of ROS. This will have far-reaching implications for Arctic ecosystems and societies through the changes in snow-pack and permafrost properties.

  12. Highway runoff quality in Ireland.

    Science.gov (United States)

    Berhanu Desta, Mesfin; Bruen, Michael; Higgins, Neil; Johnston, Paul

    2007-04-01

    Highway runoff has been identified as a significant source of contaminants that impact on the receiving aquatic environment. Several studies have been completed documenting the characteristics of highway runoff and its implication to the receiving water in the UK and elsewhere. However, very little information is available for Ireland. The objective of this study was to determine the quality of highway runoff from major Irish roads under the current road drainage design and maintenance practice. Four sites were selected from the M4 and the M7 motorways outside Dublin. Automatic samplers and continuous monitoring devices were deployed to sample and monitor the runoff quality and quantity. More than 42 storm events were sampled and analysed for the heavy metals Cd, Cu, Pb, and Zn, 16 US EPA specified PAHs, volatile organic compounds including MTBE, and a number of conventional pollutants. All samples were analysed based on the Standard Methods. Significant quantities of solids and heavy metals were detected at all sites. PAHs were not detected very often, but when detected the values were different from quantities observed in UK highways. The heavy metal concentrations were strongly related to the total suspended solids concentrations, which has a useful implication for runoff management strategies. No strong relationship was discovered between pollutant concentrations and event characteristics such as rainfall intensity, antecedent dry days (ADD), or rainfall depth (volume). This study has demonstrated that runoff from Irish motorways was not any cleaner than in the UK although the traffic volume at the monitored sites was relatively smaller. This calls for a site specific investigation of highway runoff quality before adopting a given management strategy.

  13. Attribution analysis of runoff decline in a semiarid region of the Loess Plateau, China

    Science.gov (United States)

    Li, Binquan; Liang, Zhongmin; Zhang, Jianyun; Wang, Guoqing; Zhao, Weimin; Zhang, Hongyue; Wang, Jun; Hu, Yiming

    2016-12-01

    Climate variability and human activities are two main contributing attributions for runoff changes in the Yellow River, China. In the loess hilly-gully regions of the middle Yellow River, water shortage has been a serious problem, and this results in large-scale constructions of soil and water conservation (SWC) measures in the past decades in order to retain water for agricultural irrigation and industrial production. This disturbed the natural runoff characteristics. In this paper, we focused on a typical loess hilly-gully region (Wudinghe and Luhe River basins) and investigated the effects of SWC measures and climate variability on runoff during the period of 1961-2013, while the SWC measures were the main representative of human activities in this region. The nonparametric Mann-Kendall test was used to analyze the changes of annual precipitation, air temperature, potential evapotranspiration (PET), and runoff. The analysis revealed the decrease in precipitation, significant rise in temperature, and remarkable runoff reduction with a rate of more than 0.4 mm per year. It was found that runoff capacity in this region also decreased. Using the change point detection methods, the abrupt change point of annual runoff series was found at 1970, and thus, the study period was divided into the baseline period (1961-1970) and changed period (1971-2013). A conceptual framework based on four statistical runoff methods was used for attribution analysis of runoff decline in the Wudinghe and Luhe River basins (-37.3 and -56.4%, respectively). Results showed that runoff reduction can be explained by 85.2-90.3% (83.3-85.7%) with the SWC measures in the Wudinghe (Luhe) River basin while the remaining proportions were caused by climate variability. The findings suggested that the large-scale SWC measures demonstrated a dominant influence on runoff decline, and the change of precipitation extreme was also a promoting factor of the upward trending of SWC measures' contribution to

  14. Characteristics of storms that contribute to extreme precipitation events over the Iberian Peninsula

    Science.gov (United States)

    Trigo, Ricardo; Ramos, Alexandre M.; Ordoñez, Paulina; Liberato, Margarida L. R.; Trigo, Isabel F.

    2014-05-01

    Floods correspond to one of the most deadly natural disasters in the Iberian Peninsula during the last century. Quite often these floods are associated to intense low pressure systems with an Atlantic origin. In recent years a number of episodes have been evaluated on a case-by-case approach, with a clear focus on extreme events, thus lacking a systematic assessment. In this study we focus on the characteristics of storms for the extended winter season (October to March) that are responsible for the most extreme rainfall events over large areas of the Iberian Peninsula. An objective method for ranking daily precipitation events during the extended winter is used based on the most comprehensive database of high resolution (0.2º latitude by 0.2º longitude) gridded daily precipitation dataset available for the Iberian Peninsula. The magnitude of an event is obtained after considering the total area affected as well as its intensity in every grid point (taking into account the daily normalised departure from climatology). Different precipitation rankings are studied considering the entire Iberian Peninsula, Portugal and also the six largest river basins in the Iberian Peninsula (Duero, Ebro, Tagus, Minho, Guadiana and Guadalquivir). Using an objective cyclone detecting and tracking scheme [Trigo, 2006] the storm track and characteristics of the cyclones were obtained using the ERA-Interim reanalyses for the 1979-2008 period. The spatial distribution of extratropical cyclone positions when the precipitation extremes occur will be analysed over the considered sub-domains (Iberia, Portugal, major river basins). In addition, we distinguish the different cyclone characteristics (lifetime, direction, minimum pressure, position, velocity, vorticity and radius) with significant impacts in precipitation over the different domains in the Iberian Peninsula. This work was partially supported by FEDER (Fundo Europeu de Desenvolvimento Regional) funds through the COMPETE (Programa

  15. Characteristics of sub-daily precipitation extremes in observed data and regional climate model simulations

    Science.gov (United States)

    Beranová, Romana; Kyselý, Jan; Hanel, Martin

    2017-03-01

    The study compares characteristics of observed sub-daily precipitation extremes in the Czech Republic with those simulated by Hadley Centre Regional Model version 3 (HadRM3) and Rossby Centre Regional Atmospheric Model version 4 (RCA4) regional climate models (RCMs) driven by reanalyses and examines diurnal cycles of hourly precipitation and their dependence on intensity and surface temperature. The observed warm-season (May-September) maxima of short-duration (1, 2 and 3 h) amounts show one diurnal peak in the afternoon, which is simulated reasonably well by RCA4, although the peak occurs too early in the model. HadRM3 provides an unrealistic diurnal cycle with a nighttime peak and an afternoon minimum coinciding with the observed maximum for all three ensemble members, which suggests that convection is not captured realistically. Distorted relationships of the diurnal cycles of hourly precipitation to daily maximum temperature in HadRM3 further evidence that underlying physical mechanisms are misrepresented in this RCM. Goodness-of-fit tests indicate that generalised extreme value distribution is an applicable model for both observed and RCM-simulated precipitation maxima. However, the RCMs are not able to capture the range of the shape parameter estimates of distributions of short-duration precipitation maxima realistically, leading to either too many (nearly all for HadRM3) or too few (RCA4) grid boxes in which the shape parameter corresponds to a heavy tail. This means that the distributions of maxima of sub-daily amounts are distorted in the RCM-simulated data and do not match reality well. Therefore, projected changes of sub-daily precipitation extremes in climate change scenarios based on RCMs not resolving convection need to be interpreted with caution.

  16. Damage Characteristics of Altered and Unaltered Diabases Subjected to Extremely Cold Freeze-Thaw Cycles

    Science.gov (United States)

    Luo, Xuedong; Jiang, Nan; Zuo, Changqun; Dai, Zhenwei; Yan, Suntao

    2014-11-01

    Altered and unaltered diabases are commonly deposited on hydrothermally mineralized slopes. To study their damage characteristics during freeze-thaw cycles, they were sampled from Cihai iron ore mine located in an extremely cold region, Xinjiang, China and examined using acoustic and X-ray diffraction experiments to analyze the differences in their main mineral components and explore their damage characteristics under freeze-thaw conditions. Based on the results of these experiments, their damage and degradation patterns were obtained and the evolution of their physical characteristics including the rock mass loss rate ( L F), rock strength loss rate ( R σ ), P-wave velocity loss rate ( V l), and freeze-thaw coefficient ( K f) was analyzed. In addition, two groups of equations were established to characterize the relationships of these physical and mechanical properties of the rock specimens with the number and temperature of freeze-thaw cycles. The results show that the mineral composition of diabase changes during its alteration, showing increased clay and calcite, and the degradation and evolution patterns of the physical and mechanical parameters ( L F, R σ , V l, and K f) of the altered rocks during freeze-thaw cycles are different from those of diabase, with the altered diabase exhibiting greater damage than the diabase.

  17. Effects of physical characteristics and residence style on alignment of lower extremity.

    Science.gov (United States)

    Lee, Jangwon; Park, Hye-Sang

    2016-04-01

    This research was performed to identify the incidence of deformity of lower extremity and to identify the relationship of the incidence between the deformities. Once the incidences and relationship are found, next purpose was to find the effects of physical characteristics and residence styles on the development of lower extremity deformities. One hundred fifteen males and 108 females participated in this study. Data collecting was performed by questionnaire and visual postural evaluation. The incidence of genu varus was significantly high in standing-up life style compared to sitting-on life style (chi-square=8.28; P=0.004). However, the incidences of heel varus (chi-square=13.223; P=0.004) and femoral torsion (chi-square=19.347; Pstyle than standing-up life style. The incidences of genu varus (chi-square=24.18; Pstyle compared to standing-up life style (Pstyle against standing-up life style showed 6.6 times significantly high relationship in femoral torsion (95% confidence range, 1.64-26.47) in men.

  18. [Identification of male somatotype based on osteometric characteristics of the upper and lower extremities].

    Science.gov (United States)

    Zviagin, V N; Sineva, I M

    2009-01-01

    This osteologic study included examination of 101 skeletons from the collections of the Department of Anthropology, M. V. Lomonosov Moscow State University, and Peter the Great Museum of Anthropology and Ethnography (Sankt-Peterburg). The results were compared with the data obtained by examining materials excavated from grave sites of an Yoshkar-Ola cemetery and from the Isupovo necropole (Kostroma) to evaluate the possibility of identifying human somatotypes from bone remains. Multidimensional discriminative analysis demonstrated that the equation derived by comparing characteristic signs of all long tubular bones of the extremities was of highest diagnostic value for the purpose of the study. Diagnostic equations are proposed for the identification of individual somatotypes based on the analysis of skeletal remains for the use in practical forensic medical examination.

  19. Radiative Characteristics of Aerosol During Extreme Fire Event over Siberia in Summer 2012

    Science.gov (United States)

    Zhuravleva, Tatiana B.; Kabanov, Dmitriy M.; Nasrtdinov, Ilmir M.; Russkova, Tatiana V.; Sakerin, Sergey M.; Smirnov, Alexander; Holben, Brent N.

    2017-01-01

    Microphysical and optical properties of aerosol were studied during a mega-fire event in summer 2012 over Siberia using ground-based measurements of spectral solarradiation at the AERONET site in Tomsk and satellite observations. The data were analyzed using multi-year (2003-2013) measurements of aerosol characteristics under back-ground conditions and for less intense fires, differing in burning biomass type, stage of fire, remoteness from observation site, etc. (ordinary smoke). In June-August 2012, the average aerosol optical depth (AOD, 500 nm) had been 0.95+/-0.86, about a factor of 6 larger than background values (0.16+/-0.08), and a factor of 2.5 larger than in ordinary smoke. The AOD values were extremely high on 24-28 July and reached 3-5. A comparison with satellite observations showed that ground-based measurements in the region of Tomsk not only reflect the local AOD features, but are also characteristic for the territory of Western Siberia as a whole. Single scattering albedo (SSA, 440 nm) in this period ranged from 0.91 to 0.99 with an average of approx. 0.96 in the entire wavelength range of 440-1020 nm. The increase in absorptance of aerosol particles (SSA(440 nm)=0.92) and decrease in SSA with wavelength observed in ordinary smoke agree with the data from multi-year observations in analogous situations in the boreal zone of USA and Canada. Volume aerosol size distribution in extreme and ordinary smoke had a bimodal character with significant prevalence of fine-mode particles, but in summer 2012 the mean median radius and the width of the fine-mode distribution somewhat increased. In contrast to data from multi-year observations, in summer 2012 an increase in the volume concentration and median radius of the coarse mode was observed with growing AOD.

  20. Rainfall-runoff model HEC-HMS in a small inhomogeneous basin

    Science.gov (United States)

    Ponížilová, Iva; Unucka, Jan; Říhová, Veronika

    2014-05-01

    The contribution focuses on the applicability of the hydrologic rainfall-runoff model HEC-HMS to verify the effect of inhomogeneities of the basin surface. The simulation of an extreme rainfall-runoff episode using the HEC-HMS model should prove the influence of basin inhomogeneity on the speed and volume of runoff and the potential of watersheds on runoff mitigation. The area of interest is situated in North Bohemia, Czech Republic. Inhomogeneity of the Robecsky stream basin is caused by different physical-geographic conditions in the basin of the main reaches of the Robecsky stream and its major left tributary which is the Bobri stream. Before their confluence, both streams have a comparable catchment area of about 130 km2. Significant differences are manifested in average altitude of the basin, basin shape, basin slope, time of concentration and the proportion of forest areas. The Bobri stream shows more extreme runoff characteristics in combination with a smaller area of forestation. Another important factor affecting runoff from the basin is the proportion of watersheds that accumulate water in the landscape and cause runoff mitigation and slowdown. To illustrate the influence of watersheds Machovo Lake on the Robecsky stream and Holansky pond on the Bobri stream were selected. Machovo Lake is the third largest watershed in the territory of the Czech Republic. Holansky pond is the largest of the system of Holansky ponds. The Robecsky stream has the lowest runoff coefficient from the entire Ploucnice basin. The lakes surface-drainage area ratio is approximately 1.7% of the total catchment area of the Robecsky stream. The rainfall-runoff model HEC-HMS was utilized for the analysis and to determine the volume of runoff the method of CN curves was used that depends on hydrological properties of soils. For schematisation of extreme runoff conditions of the basin the precipitation period from 6th to 8th August 2010 was selected. Extremeness of peak flows of the

  1. Soils - Potential Runoff

    Data.gov (United States)

    Kansas Data Access and Support Center — This digital spatial data set provides information on the spatial distribution of potential runoff-contributing areas in Kansas. Potential runoff-contributing areas...

  2. 黄河上游径流统计特征及演变规律分析%Analysis of Statistical Characteristics and Evolution Law of Runoff in the Upper Yellow River

    Institute of Scientific and Technical Information of China (English)

    白夏; 王义民; 戚晓明; 柴娟; 杨兰

    2016-01-01

    Based on the runoff process series of 1956-2011 of Tangnaihai Station in the Upper Yellow River, the annual distribution and inter⁃annual varying characteristics of the historical runoff process was analyzed and the trend and periodicity of the runoff process series were discussed by applying the linear trend estimation and maximum entropy spectral analysis method in this paper. The results show that a) the annual distribution of runoff process in the upper Yellow River varies obviously and the runoff in summer flood period ( from July to October) accounts for 60%;b) the amount of wet and special rainy year accounts for 48.21% among the research periods, the ratio for the maximum and the minimum annual runoff is 3. 08 and the runoff process presents a weak decreasing trend, which is useful for the comprehensively development of water resources in the upper Yellow River;c) the runoff process in the Upper Yellow River has an obvious cycle periods of 28 a, 8 a and 5 a.%以黄河上游唐乃亥水文站1956—2011年径流量资料为基础,分析了年内、年际径流量的变化特征,采用线性倾向估计法和极大熵谱分析法对径流量序列的趋势性和周期性进行了识别。结果表明:①黄河上游径流量年内分配差异明显,径流量主要集中在7—10月,7—10月径流量占全年径流总量的60%;②研究时段内丰水/特丰年份占整个序列长度的48.21%,年径流量极值比为3.08,径流量呈微弱减小趋势,有利于黄河上游水资源的综合开发利用;③黄河上游径流量存在28、8、5 a的显著周期。

  3. Analysis of an extreme rainfall-runoff event at the Landscape Evolution Observatory by means of a three-dimensional physically-based hydrologic model

    Directory of Open Access Journals (Sweden)

    G.-Y. Niu

    2013-10-01

    Full Text Available We present a detailed analysis, by means of a three-dimensional physically-based hydrological model, of the first experiment conducted at the Biosphere 2 Landscape Evolution Observatory (LEO. The experiment was driven by an intense rainfall event and produced a hydrological response characterized predominantly by water outflow along the lower lateral boundary (seepage face of LEO, together with overland flow that began 15 h after the start of rainfall and caused erosion of the superficial soil and formation of a small channel. The analysis is designed to test the null hypothesis that the soil is hydraulically homogenous, and an alternative hypothesis that the soil has developed some hydraulic heterogeneity in the downstream direction due to saturated soil compaction near the seepage face. More than 20 000 sensitivity simulations were run in a systematic search for optimal parameters to reproduce measurements of seepage face outflow and hillslope water storage. We varied the saturated hydraulic conductivity (Ksat of the seepage face (18 values, Ksat in the rest of the LEO soil (30 values, and soil porosity (21 values, and we considered two values of the pore size distribution parameter (n in the water retention characteristics, obtained from a particle size distribution analysis and from laboratory experiments on LEO soil samples. For both n values, the best simulations under the heterogeneous soil hypothesis produced smaller errors than the best runs under the null hypothesis. Moreover the heterogeneous runs yielded a higher probability of best realizations than the homogenous runs. These results support the hypothesis of localized incipient heterogeneity of the LEO soil.

  4. Effect of vegetative filter strips on herbicide runoff under various types of rainfall.

    Science.gov (United States)

    Otto, Stefan; Cardinali, Alessandra; Marotta, Ester; Paradisi, Cristina; Zanin, Giuseppe

    2012-06-01

    Narrow vegetative filter strips proved to effectively reduce herbicide runoff from cultivated fields mainly due to the ability of vegetation to delay surface runoff, promote infiltration and adsorb herbicides. A field trial was conducted from 2007 to 2009 in north-east Italy in order to evaluate the effectiveness of various types of vegetative filter strips to reduce spring-summer runoff of the herbicides mesotrione, metolachlor and terbuthylazine, widely used in maize, and to evaluate the effect of the rainfall characteristics on the runoff volume and concentration. Results show that without vegetative filter strip the herbicide load that reaches the surface water is about 5-6 g ha(-1)year(-1) for metolachlor and terbuthylazine (i.e. 0.5-0.9% of the applied rate), confirming that runoff from flat fields as in the Po Valley can have a minor effect on the water quality, and that most of the risk is posed by a few, or even just one extreme rainfall event with a return period of about 25-27 years, causing runoff with a maximum concentration of 64-77 μg L(-1). Mesotrione instead showed rapid soil disappearance and was observed at a concentration of 1.0-3.8 μg L(-1) only after one extreme (artificial) rainfall. Vegetative filter strips of any type are generally effective and can reduce herbicide runoff by 80-88%. Their effectiveness is steady even under severe rainfall conditions, and this supports their implementation in an environmental regulatory scheme at a catchment or regional scale.

  5. Rainfall and runoff quantity and quality characteristics of four urban land-use catchments in Fresno, California, October 1981 to April 1983

    Science.gov (United States)

    Oltmann, Richard N.; Shulters, Michael V.

    1989-01-01

    Rainfall and runoff quantity and quality were monitored for industrial, single-dwelling residential, multiple-dwelling residential, and commercial land-use catchments during the 1981-82 and 1982-83 rain seasons. Storm-composite rainfall and discrete run6ff samples were analyzed for numerous inorganic, biological, physical, and organic constituents. Atmospheric dry-deposition and street-surface particulate samples also were collected and analyzed. With the exception of the industrial catchment, the highest runoff concentrations for most constituents occurred during the initial storm runoff and then decreased throughout the remainder of the storm, independent of hydraulic conditions. Metal concentrations were high during initial runoff, but also increased as flow increased. Constituent concentrations for the industrial catchment fluctuated greatly during storms. Statistical tests showed higher ammonia plus organic nitrogen, ammonia, pH, and phenol concentrations in rainfall at the industrial site than at the single-dwelling residential and laboratory sites. Statistical testing of runoff quality data showed higher concentrations for the industrial catchment than for the two residential and commercial catchments for most constituents. Total recoverable lead was one of the few constituents that had lower concentrations for the industrial catchment than for the other three catchments. The two residential catchments showed no significant difference in runoff concentrations for 50 of the 57 constituents used in the statistical analysis. The commercial catchment runoff concentrations for most constituents generally were similar to the residential catchments. Although constituent concentrations generally were higher for the industrial catchment than for the commercial catchment, constituent storm loads from the commercial catchment were similar to the industrial catchment because of the greater runoff volume from the highly impervious commercial catchment. Between 10 and 50

  6. Projected changes to surface wind characteristics and extremes over North America in CRCM5

    Science.gov (United States)

    Jeong, Dae Il; Sushama, Laxmi

    2017-04-01

    Changes in the tendency of wind speed and direction have significant implications for long-term water cycle, air pollution, arid and semiarid environments, fire activity, and wind energy production. Furthermore, changes in wind extremes have direct impacts on buildings, infrastructures, agriculture, power lines, and trees. This study evaluates projected changes to wind speed characteristics (i.e., seasonal and annual mean, seasonal and diurnal cycles, directional distribution, and extreme events) for the future 2071-2100 period, with respect to the current 1981-2010 period over North America, using four different simulations from the fifth-generation Canadian Regional Climate Model (CRCM5) with two driving GCMs under RCP (Representative Concentration Pathways) 4.5 and 8.5 scenarios. The CRCM5 simulates the climatology of mean sea level pressure gradient and associated wind direction over North America well when compared to ERA-Interim reanalysis dataset. The CRCM5 also reproduces properly the spatial distributions of observed seasonal and annual mean wind speeds obtained from 611 meteorological stations across North America. The CRCM5 simulations generally suggest an increase in future mean wind speed for northern and eastern parts of Canada, due to a decrease of future mean sea level pressure and more intense low pressure air circulation systems already situated in those regions such as Aleutian and Icelandic Lows. Projected changes to annual maximum wind speed show more spatial variability compared to seasonal and annual mean wind speed as extreme wind speed is influenced more by regional-scale features associated with instantaneous surface temperature and air pressure gradients. The CRCM5 simulations suggest some increases in the future 50-year return levels of wind speed, mainly due to changes in the inter-annual variability of annual maximum wind speed. However, the projected changes vary in spatial pattern with the driving GCM fields and emission scenarios

  7. Surface Rainfall-Runoff Analysis Using NRCS Curve Number and Semi-Distributed Model in Urban Watershed of Jeju Island, Korea

    Science.gov (United States)

    Yang, S. K.; Kar, K. K.; Lee, J. H.

    2015-12-01

    Rainfall-runoff modeling is a basic tool for assessing hydrological processes where natural features (geology and geography) play a pivotal role. Due to global warming, the trends of torrential rainfall and typhoon events have been found to increase spontaneously in Jeju Island of Korea. As such, the island has been shown distinctive hydrologic characteristics. The study therefore, attempts to analyze the diversified rainfall-runoff characteristics of Jeju Island during extreme hydrologic events. The study domain covers mostly the urban areas of island and the most prominent Hancheon Stream which restrains most of its overland runoff during rainfall. For watershed delineation, 30-m resolution's digital elevation model (DEM) generated from contours and 50 years' (1964-2013) historical rainfall data from the Korea meteorological administration (KMA) were used. Furthermore, geo-spatial data collected from the Korean society of agriculture engineers (KSAE) has been used for soil texture and land use classification. Some identical studies implied to predict semi-distributed (e.g. SWAT and WMS) watershed model runoff in the island. However, the significance of this study is that it considers a GIS semi-distributed model to imply NRCS curve number technique and predict accurate results for unique runoff characteristics, by considering high catchment slope. Rainfall data from 2009 to 2013 has been used as baseline information to estimate annual runoff variations, which has been used in the spatial and statistical analyses. The study infers that the simulated runoff percentages varied from 18% to 44%, accounting for the temporal fluctuations of rainfall. Afterwards, to assess the ten year interval relationship between rainfall-runoff, the study uses historical rainfall data of Jeju-si meteorological station and four rainfall station. Lastly, the ongoing rainfall-runoff analysis will be concluded by comparing the runoff result with SWAT model result.Keywords: NRCS curve

  8. Radiative characteristics of aerosol during extreme fire event over Siberia in summer 2012

    Science.gov (United States)

    Zhuravleva, Tatiana B.; Kabanov, Dmitriy M.; Nasrtdinov, Ilmir M.; Russkova, Tatiana V.; Sakerin, Sergey M.; Smirnov, Alexander; Holben, Brent N.

    2017-01-01

    Microphysical and optical properties of aerosol were studied during a mega-fire event in summer 2012 over Siberia using ground-based measurements of spectral solar radiation at the AERONET site in Tomsk and satellite observations. The data were analysed using multi-year (2003-2013) measurements of aerosol characteristics under background conditions and for less intense fires, differing in burning biomass type, stage of fire, remoteness from observation site, etc. (ordinary smoke). In June-August 2012, the average aerosol optical depth (AOD, 500 nm) had been 0.95 ± 0.86, about a factor of 6 larger than background values (0.16 ± 0.08), and a factor of 2.5 larger than in ordinary smoke. The AOD values were extremely high on 24-28 July and reached 3-5. A comparison with satellite observations showed that ground-based measurements in the region of Tomsk not only reflect the local AOD features, but are also characteristic for the territory of Western Siberia as a whole. Single scattering albedo (SSA, 440 nm) in this period ranged from 0.91 to 0.99 with an average of ˜ 0.96 in the entire wavelength range of 440-1020 nm. The increase in absorptance of aerosol particles (SSA(440 nm) = 0.92) and decrease in SSA with wavelength observed in ordinary smoke agree with the data from multi-year observations in analogous situations in the boreal zone of USA and Canada. Volume aerosol size distribution in extreme and ordinary smoke had a bimodal character with significant prevalence of fine-mode particles, but in summer 2012 the mean median radius and the width of the fine-mode distribution somewhat increased. In contrast to data from multi-year observations, in summer 2012 an increase in the volume concentration and median radius of the coarse mode was observed with growing AOD. The calculations of the average radiative effects of smoke and background aerosol are presented. Compared to background conditions and ordinary smoke, under the extreme smoke conditions the cooling

  9. Characteristics of extreme dust events observed over two urban areas in Iran

    Indian Academy of Sciences (India)

    Abbas-Ali A Bidokhti; Maryam Gharaylou; Nafiseh Pegahfar; Samaneh Sabetghadam; Maryam Rezazadeh

    2016-03-01

    Determination of dust loading in the atmosphere is important not only from the public health point of view, but also for regional climate changes. The present study focuses on the characteristics of two major dust events for two urban areas in Iran, Kermanshah and Tehran, over the period of 4 years from 2006 to 2009. To detect extreme dust outbreaks, various datasets including synoptic data, dust concentration, reanalysis data and numerical results of WRF and HYSPLIT models were used. The weather maps demonstrate that for these events dusts are mainly generated when wind velocity is high and humidity islow in the lower troposphere and the region is under the influence of a thermal low. The event lasts until the atmospheric stability prevails and the surface wind speed weakens. The thermal low nature of the synoptic conditions of these major events is also responsible for deep boundary layer development with its thermals affecting the vertical dust flux over the region. Trajectory studies show that the dust events originated from deserts in Iraq and Syria and transported towards Iran. The main distinction between the two types of mobilizations seems to affect the dust concentrations in the Tehran urban area.

  10. User characteristics and effect profile of Butane Hash Oil: An extremely high-potency cannabis concentrate.

    Science.gov (United States)

    Chan, Gary C K; Hall, Wayne; Freeman, Tom P; Ferris, Jason; Kelly, Adrian B; Winstock, Adam

    2017-09-01

    Recent reports suggest an increase in use of extremely potent cannabis concentrates such as Butane Hash Oil (BHO) in some developed countries. The aims of this study were to examine the characteristics of BHO users and the effect profiles of BHO. Anonymous online survey in over 20 countries in 2014 and 2015. Participants aged 18 years or older were recruited through onward promotion and online social networks. The overall sample size was 181,870. In this sample, 46% (N=83,867) reported using some form of cannabis in the past year, and 3% reported BHO use (n=5922). Participants reported their use of 7 types of cannabis in the past 12 months, the source of their cannabis, reasons for use, use of other illegal substances, and lifetime diagnosis for depression, anxiety and psychosis. Participants were asked to rate subjective effects of BHO and high potency herbal cannabis. Participants who reported a lifetime diagnosis of depression (OR=1.15, p=0.003), anxiety (OR=1.72, pcannabis. BHO users also reported stronger negative effects and less positive effects when using BHO than high potency herbal cannabis (pcannabis. Copyright © 2017. Published by Elsevier B.V.

  11. Physiological characteristics of the extreme thermophile Caldicellulosiruptor saccharolyticus: an efficient hydrogen cell factory

    Directory of Open Access Journals (Sweden)

    Zeidan Ahmad A

    2010-11-01

    Full Text Available Abstract Global concerns about climate changes and their association with the use of fossil fuels have accelerated research on biological fuel production. Biological hydrogen production from hemicellulose-containing waste is considered one of the promising avenues. A major economical issue for such a process, however, is the low substrate conversion efficiency. Interestingly, the extreme thermophilic bacterium Caldicellulosiruptor saccharolyticus can produce hydrogen from carbohydrate-rich substrates at yields close to the theoretical maximum of the dark fermentation process (i.e., 4 mol H2/mol hexose. The organism is able to ferment an array of mono-, di- and polysaccharides, and is relatively tolerant to high partial hydrogen pressures, making it a promising candidate for exploitation in a biohydrogen process. The behaviour of this Gram-positive bacterium bears all hallmarks of being adapted to an environment sparse in free sugars, which is further reflected in its low volumetric hydrogen productivity and low osmotolerance. These two properties need to be improved by at least a factor of 10 and 5, respectively, for a cost-effective industrial process. In this review, the physiological characteristics of C. saccharolyticus are analyzed in view of the requirements for an efficient hydrogen cell factory. A special emphasis is put on the tight regulation of hydrogen production in C. saccharolyticus by both redox and energy metabolism. Suggestions for strategies to overcome the current challenges facing the potential use of the organism in hydrogen production are also discussed.

  12. Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles.

    NARCIS (Netherlands)

    Kuijk, A.A. van; Anker, L.C.; Pasman, J.W.; Hendriks, J.C.M.; Elswijk, G.A.F. van; Geurts, A.C.H.

    2009-01-01

    OBJECTIVE: To compare stimulus-response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles. METHODS: Stimulus-response curves of MEPs and SPs were obtained from the biceps bra

  13. Electrofiltration of fly ashes extremely strong and special characteristics; Electrofiltracion de Cenizas de Alta Resistividad y Caracteristicas Especiales

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    The main objective of CARE project was to improve the utilization of electrostatic precipitator technology for control of particle emission to the atmosphere, specially from coal-fired power stations burning coal with fly ash characteristics exhibiting extremely strong particle cohesion. (Author)

  14. Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles.

    NARCIS (Netherlands)

    Kuijk, A.A. van; Anker, L.C.; Pasman, J.W.; Hendriks, J.C.M.; Elswijk, G.A.F. van; Geurts, A.C.H.

    2009-01-01

    OBJECTIVE: To compare stimulus-response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles. METHODS: Stimulus-response curves of MEPs and SPs were obtained from the biceps bra

  15. Microchannels affect runoff and sediment yield from a shortgrass prairie

    Science.gov (United States)

    Runoff and sediment yield from rangelands are extremely important variables that affect productivity, but are difficult to quantify. Studies have been conducted to assess erosion on rangelands, but very little has been done to determine if microchannels (rills) affect runoff and sediment yield. Rain...

  16. Research on Multiple-Time Scale Variable Characteristics and Calculation of Runoff of the Zhaikou River%寨口河径流变化特征及估算

    Institute of Scientific and Technical Information of China (English)

    沈雪峰

    2014-01-01

    以喀什河乌拉斯台水文站及种蜂场站为参证站,利用1958-2008年实测月、年径流量资料分析了寨口河径流量的变化特征,计算了寨口河雪山沟及红水沟入河断面不同频率的年径流量及其年内分配。结果表明:寨口河7月径流量最大,占多年平均值的20.8%,2月最小,约占2.0%;夏季约占56.0%,冬季仅占7.0%;变差系数为0.15,年际变化比较稳定;雪山沟及红水沟入河断面多年平均天然年径流量分别为1.1650亿、0.0982亿m3,同时计算得到了不同保证率下寨口河雪山沟及红水沟入河断面多年平均径流量及其各月分配。%This paper set the Wulasitai and Zhongfengchang hydrological stations which are located on the Kashgar River as the reference station,ana-lyzed the variation characteristics of the runoff of Zhaikou River and calculated the multi-year average runoff and its distribution in a year under differ-ent frequency at the river cross section of Zhaikou River,named Xueshangou and the Hongshuigou by monthly runoff series during 1958-2008. The results show that the maximum value of runoff appears in July,takes up the account of annual average about 20. 8%,but,it is the smallest in Febru-ary,accounting for 2. 0%. Moreover,the ratio is about 56. 0% in summer and only 7. 0% in winter. Variation coefficient is 0. 15 and the inter-annu-al variation is relatively stable. The account of average natural annual runoff is 116. 50 million and 9. 82 million m3 in Xueshangou and Hongshuigou respectively. Furthermore,it has obtained the multi-year average runoff and its distribution in a year under different frequency for the river cross sec-tion of Xueshangou and the Hongshuigou through calculation.

  17. Dosimetric characteristics of a TLD dosemeter with extremities; Caracteristicas dosimetricas de un dosimetro TLD de extremidades

    Energy Technology Data Exchange (ETDEWEB)

    Molina P, D.; Diaz B, E.; Lien V, R. [Centro de Proteccion e Higiene de las Radiaciones, CPHR, Apdo.Postal 6195, Habana 6, CP 10600, Ciudad Habana (Cuba)

    1999-07-01

    It was designed a TLD dosemeter for the monitoring of the extremities. This one consists in a metallic ring with a circular orifice where is arranged a T L detector of LiF: Mg,Ti (Model JR1152C) 5 x 5 x 0.8 mm{sup 3} covered by a polyethylene fine layer. In this work were studied the dosimetric properties of the dosemeter for its application in the dosimetry of extremities for photonic radiation. the results obtained allow conclude that the designed dosemeter can be used for the extremities monitoring. (Author)

  18. Comparison of Conventional Angiographic Findings between Trauma Patients with or without Runoff

    Directory of Open Access Journals (Sweden)

    Hassan Ravari

    2014-04-01

    Full Text Available Objective: To compare the conventional angiographic findings in extremity trauma patients with or without runoff. Methods: This was cross-sectional study including all the patients with extremity trauma who underwent conventional angiography during the 2 year period from 2011 to 2013 in Angiography departments of Mashhad University of Medical Sciences. Mechanism of trauma, type of injury and angiographic findings were recorded in a questionnaire for each patient. After completion of treatment and discharge, the treatment type was added. The characteristics as well as clinical findings were compared between those who were diagnosed to have arterial runoff ad those who did not. Results: One hundred and forty eight traumatic patients including 15 female with age range of 11-82 years and 133 men ranging from 25 to 40 years were enrolled. Abnormal angiographic findings were provided in 99 (66.9% patients including cutoff with distal runoff (n=60, 60.6% of abnormalities, cut off without distal runoff (n=21, 21.2% and spasm (n=14, 14.1% and other findings (n=4, 4%. Fifty one cases were treated under open surgery and amputation of traumatic limb was done for 13 patients. Amputation rate was higher in patients with cutoff and without runoff than those with cutoff and runoff (33.3% vs. 6.78%; p=0.002. Conclusion: Causes and types of traumatic arterial injury in our study were different with other reports. It was shown that angiographic findings were less important in prognosis and management of patients. Patients with spasm in angiographic findings had a better prognosis than other patients and mostly did not need any vascular surgery. The presence or absence of a distal run off in primary angiographic findings can have a predictive value in the final amputation rate.

  19. Hepatocellular carcinoma in extremely elderly patients: An analysis of clinical characteristics, prognosis and patient survival

    Institute of Scientific and Technical Information of China (English)

    Gengo Tsukioka; Akira Kojima; Yuichi Yamazaki; Toshiyuki Otsuka; Yutaka Matsuzaki; Fujio Makita; Daisuke Kanda; Katsuhiko Horiuchi; Tetsuya Hamada; Mieko Kaneko; Hideyuki Suzuki; Satoru Kakizaki; Masatomo Mori; Naondo Sohara; Ken Sato; Hitoshi Takagi; Hirotaka Arai; Takehiko Abe; Mitsuo Toyoda; Kenji Katakai

    2006-01-01

    AIM: To identify the clinical and prognostic features of patients with hepatocellular carcinoma (HCC) aged 80years or more.METHODS: A total of 1310 patients with HCC were induded in this study. Nin ety-one patients aged 80 years or more at the time of diagnosis of HCC were defined as the extremely elderly group. Two hundred and thirty-four patients aged ≥ 50 years but less than 60 years were regarded as the non-elderly group.RESULTS: The sex ratio (male to female) was significantly lower in the extremely elderly group (0.90:1)than in the non-elderly group (3.9:1, P<0.001). The positive rate for HBsAg was significantly lower in the extremely elderly group and the proportion of patients negative for HBsAg and HCVAb obviously increased in the extremely elderly group (P<0.001). There were no significant differences in the following parameters:diameter and number of tumors, Child-Pugh grading,tumor staging, presence of portal thrombosis or ascites,and positive rate for HCVAb. Extremely elderly patients did not often receive surgical treatment (P<0.001) and they were more likely to receive conservative treatment (P<0.01). There were no significant differences in survival curves based on the Kaplan-Meier methods in comparison with the overall patients between the two groups. However, the survival curves were significantly worse in the extremely elderly patients with stage Ⅰ/Ⅱ,stage Ⅰ/Ⅱ and Child-Pugh grade A cirrhosis in comparison with the non-elderly group. The causes of death did not differ among the patients, and most cases died of liverrelated diseases even in the extremely elderly patients.CONCLUSION: In the patients with good liver functions and good performance status, aggressive treatment for HCC might improve the survival rate, even in extremely elderly patients.

  20. Analysis of Runoff Variation Characteristics of Beiluo River%北洛河径流量变化特征分析

    Institute of Scientific and Technical Information of China (English)

    董起广; 周维博; 刘雷; 舒媛媛; 李云排

    2014-01-01

    The distribution non-uniform coefficient,concentration degree and variation amplitude of the Beiluo River runoff were detailedly calculat-ed based on the monthly runoff data measured at Jiaokouhe Hydrological Station from 1964 to 2008. The method of Mann-Kendall rank correlation was used to analyze the annual and seasonal runoff change trend and mutation of high and low flow periods. The results show that:a)The annual distribution of runoff of Beiluo River is relatively concentrated in 1960s and 1970s,and then in the 21st century the annual distribution is relatively uniform and runoff mainly concentrated in July,August and September;b)Trend of Beiluo River annual runoff is significantly decreasing,the de-crease trend in winter is not significant and in the other seasons is very obvious;c)The annual runoff mutates mainly in 1973 and 2003,the trends of the wet season and dry season are consistent with the whole year,but there is a mutation in 1983 in wet season and two mutations in 1982 and 1994 in dry season,and the overall trend of runoff is reduced.%采用北洛河交口河水文站1964-2008年实测月径流量资料,对径流年内分配的不均匀性、集中程度、变化幅度进行了分析;应用Mann-Kendall方法分析了北洛河径流量的年际、季节变化趋势,并对丰水期和枯水期的径流量进行了突变分析。结果表明:①北洛河河川径流量在20世纪60、70年代的年内分配比较集中,进入21世纪后年内分配相对均匀,径流量主要集中在7-9月;②北洛河年径流量呈明显减小趋势,冬季的减小趋势不显著,其他季节的减小趋势均十分明显;③北洛河年径流量在1973年、2003年发生两次突变,丰水期和枯水期的径流量变化趋势基本与全年的保持一致,但丰水期在1983年多出一次突变,枯水期在1982年、1994年多出两个突变点,径流量变化的总体趋势都是减小的。

  1. Chemical composition of runoff water in Raipur city, central India

    Science.gov (United States)

    Ambade, Balram

    2015-03-01

    Runoff water is an important transporting medium for various pollutants from land to surface water. Several mobiles and stationary sources such as vehicles, steel cement and thermal power plants, cooking, street, construction debris, etc. are emitting effluents in the environment of the central India. The rain runoff water washes out the air as well as land pollutants and flushes out into water bodies. Therefore, rain runoff water pollution in most urbanized and industrialized city of central India, i.e., Raipur during rainy season (May-September 2012) is analyzed statistically using cluster and principal component analysis to assess sources. The cluster analysis grouped runoff water samples into two clusters based on the similarity of runoff water quality characteristics of the total variance. The factor analysis differentiated the diffused sources of runoff water contaminants. The enrichment factors and runoff fluxes of the contaminants are discussed.

  2. Characteristics of Soluble and Exchangeable Acidity in an Extremely Acidified Acid Sulfate Soil

    Institute of Scientific and Technical Information of China (English)

    C.Lin; M.D.MELVILLE; 等

    1999-01-01

    An extremely acidified acid sulfate soil(ASS) was investigated to characterise its soluble and exchangeable acidity,The results showed that soluble acidity of a sample dtermined by titration with a KOH soulution was much significantly greater than that indicated by pH measured using a pH meter,paricularly for the extremely acidic soil samples,This is because the total soluble acidity of the extremely acidic soil samples was mainly composed of various soluble Al and Fe species,possibly in forms of Al sulfate complexes(e.g.,AlSO4+) and feerous Fe(Fe2+)_,It is therefore suggested not to use pH alone as an indicator of soluble acidity in ASS,particularly for extremely acidic ASS,It is also likely that AlSO4+ actively participated in cation exchange reactions.It appears that the possible involvement of this Al sulfate cation in the cation adsorption has significant effect on increasing the amount of acidity being adsorbed by the soils.

  3. Characteristic Features of Precipitation Extremes over India in the Warming Scenarios

    Directory of Open Access Journals (Sweden)

    J. V. Revadekar

    2011-01-01

    Full Text Available The detection of possible changes in extreme climate events, in terms of the frequency, intensity as well as duration assumes profound importance on the local, regional, and national scales, due to the associated critical socioeconomic consequences. Therefore, an attempt is made in this paper to evaluate various aspects of future projections of precipitation extremes over India, as projected by a state-of-art regional climate modeling system, known as PRECIS (Providing REgional Climates for Impacts Studies towards the end of the 21st century (that is, 2071–2100 using standardized indices. Study reveals that PRECIS simulations under scenarios of increasing greenhouse gas concentration and sulphate aerosols indicate marked increase in precipitation towards the end of the 21st century and is expected to increase throughout the year. However the changes in daily precipitation and the precipitation extremes during summer monsoon (June through September season are prominent than during the rest of year. PRECIS simulations under both A2 and B2 scenarios indicate increase in frequency of heavy precipitation events and also enhancement in their intensity towards the end of the 21st century. Both A2 and B2 scenarios show similar patterns of projected changes in the precipitation extremes towards the end of the 21st century. However, the magnitudes of changes in B2 scenario are on the lower side.

  4. Characteristics of autumn-winter extreme precipitation on the Norwegian west coast identified by cluster analysis

    Science.gov (United States)

    Heikkilä, U.; Sorteberg, A.

    2012-08-01

    Extremely high autumn and winter precipitation events on the European west coast are often driven by low-pressure systems in the North Atlantic. Climate projections suggest the number and intensity of these events is likely to increase far more than the mean precipitation. In this study we investigate the autumn-winter extreme precipitation on the Norwegian west coast and the connection between its spatial distribution and sea level pressure (SLP) patterns using the k-means cluster analysis. We use three relatively high resolved downscalings of one global coupled model: the Arpège global atmospheric model (stretched grid with 35-km horizontal resolution over Norway) and the WRF-downscaled Arpège model (30 and 10-km) for the 30-year periods of 1961-1990 and 2021-2050. The cluster analysis finds three main SLP patterns responsible for extreme precipitation in different parts of the country. The SLP patterns found are similar to the NAO positive pattern known to strengthen the westerly flow towards European coast. We then apply the method to investigate future change in extreme precipitation. We find an increase in the number of days with extreme precipitation of 15, 39 and 35% in the two simulations (Arpège 35-km and WRF 30 and 10-km, respectively). We do not find evidence of a significant change in the frequency of weather patterns between the present and the future periods. Rather, it is the probability of a given weather pattern to cause extreme precipitation which is increased in the future, probably due to higher temperatures and an increased moisture content of the air. The WRF model predicts the increase in this probability caused by the most important SLP patterns to be >50%. The Arpège model does not predict such a significant change because the general increase in extreme precipitation predicted is smaller, probably due to its coarser resolution over ocean which leads to smoother representation of the low pressure systems.

  5. Research on pollution characteristics of runoff of rain pipeline in urban%城区雨水管网径流污染特征研究

    Institute of Scientific and Technical Information of China (English)

    陈伟伟; 申继先; 卞艳丽; 宋静茹

    2014-01-01

    Taking urban roof as the catchment area in Xinxiang City, the paper researched the hydrology and water quality process of each rainfall event so as to provide the basis for effective use of urban rainfall and control of non-point source pollution.The samples includes the contents of SS, COD and TN.The results show that the variation trend of pollutant index SS, COD in runoff is similar and tends to a steady value.the contents gradually decrease and reach a stable value with the duration of rainfall.With the ac-cumulation of rainfall, the change amplitude of TN gradually reduce, but which has a rebound and in-crease tendency before the end of rain.The standard deviation rate of water quality indicator is in the or-der of SS>COD>TN.The first flush of roof runoff is clear, and the initial runoff amount is equivalent to former 1~3mm rainfall.The correlation between SS and COD, TN in runoff is good.It shows that the similar measures can be taken to remove them in controlling the runoff pollution.That the runoff pollu-tants flow into the receiving water body directly through urban drainage pipes has an important effect on its quality.The change of SS and COD is obvious.%以新乡市城区屋面作为汇水区域,开展试验对雨水管网中场次降雨径流水文水质过程进行研究,可为有效利用城市雨水、控制非点源污染等提供依据。水质指标包括SS、COD和TN。结果表明:水质指标中SS、COD变化趋势基本一致,随着降雨过程的持续浓度逐渐降低并趋于一个稳定值;TN随着雨量的累积浓度逐渐降低,但在降雨结束前有反弹趋势;指标标准差率呈SS>COD>TN的趋势;径流初期屋面冲刷效应明显,初期径流量可定义为前1~3mm的降雨量;径流中SS与COD、TN之间的相关性较好,在控制径流污染时可采取措施同时去除;径流污染物直接通过城区排水管网汇入受纳水体后对其水质影响较大,尤以SS、COD的变化最为明显。

  6. Hourly storm characteristics along the U.S. West Coast: Role of atmospheric rivers in extreme precipitation

    Science.gov (United States)

    Lamjiri, Maryam A.; Dettinger, Michael; Ralph, F. Martin; Guan, B.

    2017-01-01

    Gridded hourly precipitation observations over the conterminous U.S., from 1948 to 2002, are analyzed to determine climatological characteristics of storm precipitation totals. Despite generally lower hourly intensities, precipitation totals along the U.S. West Coast (USWC) are comparable to those in southeast U.S. (SEUS). Storm durations, more so than hourly intensities, strongly modulate precipitation-total variability over the USWC, where the correlation coefficients between storm durations and storm totals range from 0.7 to 0.9. Atmospheric rivers (ARs) contribute 30–50% of annual precipitation on the USWC and make such large contributions to extreme storms that 60–100% of the most extreme storms, i.e., storms with precipitation-total return intervals longer than 2 years, are associated with ARs. These extreme storm totals are more strongly tied to storm durations than to storm hourly or average intensities, emphasizing the importance of AR persistence to extreme storms on the USWC.

  7. Variation Characteristics and Attribution of Runoff in Xinjiang Drainage Basin During 1953-2011%1953-2011年信江流域径流量变化特征及归因分析

    Institute of Scientific and Technical Information of China (English)

    胡菊芳; 赵冠男; 蔡哲; 马锋敏

    2014-01-01

    利用信江流域梅港水文控制站1953-2011年径流量观测资料和11个气象站同期气象观测资料,采用统计方法、Mann-Kendall非参数检验方法、Morlet小波分析法,对信江流域径流量年内、年际变化的不均匀性、长期趋势、周期变化,及其与气候因素的相关性等进行分析。结果显示,信江流域多年平均径流量呈缓慢增大趋势,但具有显著的年际和年代际变化特征,振荡周期明显,年际变化的主要周期为6-8 a,年代际变化的主要周期为准22 a,在20世纪70-90年代最明显。年流量以主汛期(4-6月)为最多,春、夏季(3-8月)径流变差系数小,水量稳定,冬季变差系数大,水量不稳定。流域径流量与气候因素中的降水、蒸发具有显著的相关性,而人类活动中的城镇化、经济、人口等因素对径流变化起到了一定的辅助作用。%In this paper, th e annual runoff variation and its climate impact factors were analyzed by using statistical analysis method, Mann-Kendall test method and Morlet wavelet analysis method based on the data of runoff volumes at Meigang hydrological station in Xinjiang basin during the period of 1953-2011. The results show that the annual runoff volumes present slightly increase trend with obvious interannual and interdecadal variation characteristics, especially for the period of 1970-1990. The interannual cycle change is 6-8 years and the interdecadal cycle change is about 22 years. The maximal monthly runoff appeared in the main flood season(April-June). During spring and summer, variation of runoff shows a low coefficient with stable flow quantity while shows the opposite state in winter. Obvious correlation can be found between runoff volumes and climate factors. Moreover, economy, population and human activities in the urbanization played supporting roles in runoff changes.

  8. [Gender determination based on osteometric characteristics of the upper and lower extremities by discriminant analysis].

    Science.gov (United States)

    Zviagin, V N; Sineva, I M

    2007-01-01

    The authors studied the osteological collection of the Chair of Antropology of the Moscow State University. The results of measurement of length of long tubular bones and articular parts of scapula and pelvis were statistically treated. The complex of discriminant models calculated by the Fisher's method is recommended for the sex identification. The diagnostic accuracy is 74 - 83.5% (separated bones) and 85.7 - 95.2% (complex of bones of upper and lower extremities).

  9. Terrestrial Laser Scanner (TLS) as a tool for the reconstruction of extreme wave event characteristics

    Science.gov (United States)

    Schneider, Bastian; Hoffmann, Gösta

    2017-04-01

    The shores of the Northern Indian Ocean were exposed to extreme wave inundation in the past. Two relevant hazards, storm surges triggered by tropical cyclones and tsunamis, are known to occur in the region but are rarely instrumentally recorded. Various sediment deposits along the coast are the only remnants of those past events. A profound understanding of return periods and magnitudes of past events is essential for developing land-use planning and risk mitigation measures in Oman and neighboring countries. A detailed investigation of these deposits, in this case primarily blocks and boulder trains but also fine grained sediments, provides insight on parameters such as wave height and inundation distance. These parameters can then be used for modeling inundation scenarios superimposed on modern infrastructure. We are investigating the spatial 3D-distribution of the extreme wave event sediments along the coastline through a high-precision survey of the event deposits using a Faro Focus 3D X330 TLS. A TLS is capable of recording high-detail and colored point clouds, which allows detailed measurements and has proved to be a powerful tool in geosciences. These multi-parameter point clouds in combination with dating results serve as a base for extreme wave event return period and magnitude estimations. Relevant parameters on large sediments are size, shape, volume, mass as well as relative arrangement, sorting and orientation. Furthermore, the TLS data is used to distinguish between the various boulder lithologies using a multi-scale supervised classification. Surface roughness as a result of weathering can serve as an indicator for exposure time of boulders and hint on various generations of extreme wave events. The distribution of the boulders relative to the site they were quarried from indicates on the flow direction of the waves and consequently might help to distinguish between storm and tsunami waves.

  10. Characteristics of mesoscale-convective-system-produced extreme rainfall over southeastern South Korea: 7 July 2009

    Science.gov (United States)

    Jeong, Jong-Hoon; Lee, Dong-In; Wang, Chung-Chieh; Han, In-Seong

    2016-04-01

    An extreme-rainfall-producing mesoscale convective system (MCS) associated with the Changma front in southeastern South Korea was investigated using observational data. This event recorded historic rainfall and led to devastating flash floods and landslides in the Busan metropolitan area on 7 July 2009. The aim of the present study is to analyse the influences for the synoptic and mesoscale environment, and the reasons that the quasi-stationary MCS causes extreme rainfall. Synoptic and mesoscale analyses indicate that the MCS and heavy rainfall occurred in association with a stationary front which resembled a warm front in structure. A strong southwesterly low-level jet (LLJ) transported warm and humid air and supplied the moisture toward the front, and the air rose upwards above the frontal surface. As the moist air was conditionally unstable, repeated upstream initiation of deep convection by back-building occurred at the coastline, while old cells moved downstream parallel to the convective line with training effect. Because the motion of convective cells nearly opposed the backward propagation, the system as a whole moved slowly. The back-building behaviour was linked to the convectively generated cold pool and its outflow boundary, which played a role in the propagation and maintenance of the rainfall system. As a result, the quasi-stationary MCS caused a prolonged duration of heavy rainfall, leading to extreme rainfall over the Busan metropolitan area.

  11. Assessing the characteristics of extreme precipitation over northeast China using the multifractal detrended fluctuation analysis

    Science.gov (United States)

    Du, Haibo; Wu, Zhengfang; Zong, Shengwei; Meng, Xiangjun; Wang, Lei

    2013-06-01

    Extreme climate events have inflicted severe and adverse effects on human life, social economy, and natural ecosystems. In this study, the precipitation time series from a network of 90 weather stations in Northeast China (NEC) and for the period of 1961-2009 are used. An objective method, the multifractal detrended fluctuation analysis method, is applied to determine the thresholds of extreme events. Notable occurrence frequency and strong intensity of extreme precipitation (EP) mainly occur in Liaoning Province and the piedmont regions in Changbai Mountains and Xiao Hinggan Mountains. Generally, EP frequency shows a nonsignificant negative trend, whereas EP intensity has a weak and nonsignificant positive trend for the entire NEC in the period of 1961-2009. To assess EP severity, we propose an EP severity index (EPSI) combining both EP frequency and intensity, rather than separately analyze the EP frequency or intensity. Spatial gradients of EPSI are observed in northeast-southwest and northwest-southeast directions over NEC. The EPSI in northwestern and southeastern NEC are low (0.02-0.3), whereas high EPSI (0.34-0.83) occurs in the southwestern and northeastern portions of the region. Higher EPSI (0.4-0.83) occurs in southern Liaoning Province, which decreases along the southwest-northeast direction. The spatial patterns of EPSI are associated with the circulation over East Asia. Areas that have a short distance from sea and that locate in the windward slope of mountain will probably accompany high EP severity over NEC.

  12. Lags in hydrologic recovery following an extreme drought: Assessing the roles of climate and catchment characteristics

    Science.gov (United States)

    Yang, Yuting; McVicar, Tim R.; Donohue, Randall J.; Zhang, Yongqiang; Roderick, Michael L.; Chiew, Francis H. S.; Zhang, Lu; Zhang, Junlong

    2017-06-01

    Drought, generally characterized by below-average water supply, propagates through the hydrologic system with consequent ecological and societal impacts. Compared with other drought aspects, the recovery of drought especially in the hydrological components, which directly relates to the recovery of water resources for agricultural, ecological and human needs, is less-understood. Here, taking the Millennium drought in southeast Australia (˜1997-2009) as an illustrating case, we comprehensively examined multiple aspects of the meteorological (i.e., precipitation) and hydrological (i.e., streamflow and base flow) droughts across 130 unimpaired catchments using long-term hydro-meteorological observations. Results show that the duration and intensity of the meteorological drought are both lengthened and amplified in the hydrological drought, suggesting a nonstationarity in the rainfall-runoff relationship during a prolonged drought. Additionally, we find a time lag commonly exists between the end of the meteorological droughts and the end of the hydrological drought, with the recovery of base flow showing a longer lag than the recovery of streamflow. The recovery rate of precipitation after drought was found to be the dominant factor that controls the recovery of hydrological droughts while catchment landscape (i.e., valley bottom flatness) plays an important but secondary role in controlling the lags in the hydrological recovery. Other hydro-climatic factors and catchment properties appear to have only minor influences governing hydrological drought recovery. Our findings highlight a delayed response in the terrestrial components of the hydrological cycle to precipitation after prolonged drought, and provide valuable scientific guidance to water resources management and water security assessment in regions facing future droughts.

  13. Rainfall-runoff Characteristics of Artificial Micro-catchments for Rainwater Harvesting%人工集水面降雨径流观测实验研究

    Institute of Scientific and Technical Information of China (English)

    李小雁; 龚家栋

    2001-01-01

    The results of the field experiments indicated that runoff fromearth catchments (undisturbed loess slope, clearing loess slope and compacted catchments) occurr ed as infiltration-excess process, and it was mainly depended upon rainfall i nt ensity. Annual runoff mainly produced from a few high-intensity rainfall event s and the annual runoff efficiency ranged from 7.4% to 35.5%, therefore, more wate r would be collected from earth catchments by the increase of natural catchment area. The rainfall amount and intensity had little effect on the water yield fro m asphalt felt, asphalt spraying and concrete treated catchments with a mean ann ual runoff efficiency of 50%~80% and a high cost. The trend of high efficient us e of harvested water for such catchments is to combine the water harvesting syste m with installation agriculture. The plastic catchment had low cost and higher a nnual runoff efficiency, but it could not resist radiation and lasted only 4~5 m onths. So temporarily moveable plastic film catchment can be recommended to use in rainy period in the field or yard for storing rainwater in the cistern for supplementary irrigation.%野外降雨径流观测实验研究表明:土质集水面(自然黄土坡面、清除杂草自然黄土坡面和夯实集水面)的降雨产流方式为超渗产流,受降雨强度的影响大,径流的产生主要是由几次高强度的暴雨引起。此类集水面的年平均集水效率在7.4%~35.5%之间,因此,增大集水区面积是保证土质集水面收集到更多雨水的基本途径。油毡、沥青和混凝土处理集水面的产流过程受降雨量和降雨强度的影响小,年平均集水效率在50%~80%之间,但投资成本较高,其雨水利用方向是和设施农业相结合,修建固定集水面,发展高投入高产出农业。塑料膜集水面一次性投入低且平均集水效率较高,但寿命较短,建议利用简单临时性的移动塑料集水面收集雨水以

  14. Spatiotemporal distribution characteristics and attribution of extreme regional low temperature event

    Institute of Scientific and Technical Information of China (English)

    封泰晨; 张珂铨; 苏海晶; 王晓娟; 龚志强; 张文煜

    2015-01-01

    Based on an objective identification technique for regional low temperature event (OITRLTE), the daily minimum temperature in China has been detected from 1960 to 2013. During this period, there were 60 regional extreme low temperature events (ERLTEs), which are included in the 690 regional low temperature events (RLTEs). The 60 ERLTEs are analyzed in this paper. The results show that in the last 50 years, the intensity of the ERLTEs has become weak;the number of lasted days has decreased;and, the affected area has become small. However, that situation has changed in this century. In terms of spatial distribution, the high intensity regions are mainly in Northern China while the high frequency regions concentrate in Central and Eastern China. According to the affected area of each event, the 60 ERLTEs are classified into six types. The atmospheric circulation background fields which correspond to these types are also analyzed. The results show that, influenced by stronger blocking highs of Ural and Lake Baikal, as well as stronger southward polar vortex and East Asia major trough at 500-hPa geopotential height, cold air from high latitudes is guided to move southward and abnormal northerly winds at 850 hPa makes the cold air blow into China along diverse paths, thereby forming different types of regional extreme low temperatures in winter.

  15. An analysis of the radiation field characteristics for extremity dose assessment during maintenance periods at nuclear power plants in Korea.

    Science.gov (United States)

    Kim, Hee Geun; Kong, Tae Young

    2012-12-01

    Workers who maintain the water chambers of steam generators during maintenance periods in nuclear power plants (NPPs) have a higher likelihood of high radiation exposure, even if they are exposed for a short period of time. In particular, it is expected that the hands of workers would receive the highest radiation exposure as a consequence of hand contact with radioactive materials. In this study, a characteristic analysis of inhomogeneous radiation fields for contact operations was conducted using thermoluminescent dosemeters for the whole body and extremities during maintenance periods at Korean NPPs. It was observed that inhomogeneous radiation fields for contact operations at NPPs were dominated by high-energy photons.

  16. Distribution Characteristics of the Intensity and Extreme Intensity of Tropical Cyclones Influencing China

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yongguang; CHEN Jiong; TAO Zuyu

    2014-01-01

    To address the defi ciency of climatological research on tropical cyclones (TCs) infl uencing China, we analyze the distributions of TCs with diff erent intensities in the region, based on the best-track TC data for 1949-2011 provided by the Shanghai Typhoon Institute. We also present the distributions of 50-and 100-yr return-period TCs with diff erent intensities using the Gumbel probability distribution. The results show that TCs with diff erent intensities exert distinctive eff ects on various regions of China and its surrounding waters. The extreme intensity distributions of TCs over these diff erent regions also diff er. Super and severe typhoons mainly infl uence Taiwan Island and coastal areas of Fujian and Zhejiang provinces, while typhoons and TCs with lower intensities infl uence South China most frequently. The probable maximum TC intensity (PMTI) with 50- and 100-yr return periods infl uencing Taiwan Island is below 890 hPa; the PMTI with a 50-yr return period infl uencing the coastal areas of Fujian and Zhejiang provinces is less than 910 hPa, and that with a 100-yr return period is less than 900 hPa;the PMTI with a 50-yr return period infl uencing the coastal areas of Hainan, Guangdong, and the northern part of the South China Sea is lower than 930 hPa, and that with a 100-yr return period is less than 920 hPa. The results provide a useful reference for the estimation of extreme TC intensities over diff erent regions of China.

  17. Rhizobial Diversity and Nodulation Characteristics of the Extremely Promiscuous Legume Sophora flavescens.

    Science.gov (United States)

    Jiao, Yin Shan; Liu, Yuan Hui; Yan, Hui; Wang, En Tao; Tian, Chang Fu; Chen, Wen Xin; Guo, Bao Lin; Chen, Wen Feng

    2015-12-01

    In present study, we report our extensive survey on the diversity and biogeography of rhizobia associated with Sophora flavescens, a sophocarpidine (matrine)-containing medicinal legume. We additionally investigated the cross nodulation, infection pattern, light and electron microscopies of root nodule sections of S. flavescens infected by various rhizobia. Seventeen genospecies of rhizobia belonging to five genera with seven types of symbiotic nodC genes were found to nodulate S. flavescens in natural soils. In the cross-nodulation tests, most representative rhizobia in class α-Proteobacteria, whose host plants belong to different cross-nodulation groups, form effective indeterminate nodules, while representative rhizobia in class β-Proteobacteria form ineffective nodules on S. flavescens. Highly host-specific biovars of Rhizobium leguminosarum (bv. trifolii and bv. viciae) and Rhizobium etli bv. phaseoli could establish symbioses with S. flavescens, providing further evidence that S. flavescens is an extremely promiscuous legume and it does not have strict selectivity on either the symbiotic genes or the species-determining housekeeping genes of rhizobia. Root-hair infection is found as the pattern that rhizobia have gained entry into the curled root hairs. Electron microscopies of ultra-thin sections of S. flavescens root nodules formed by different rhizobia show that the bacteroids are regular or irregular rod shape and nonswollen types. Some bacteroids contain poly-β-hydroxybutyrate (PHB), while others do not, indicating the synthesis of PHB in bacteroids is rhizobia-dependent. The extremely promiscuous symbiosis between S. flavescens and different rhizobia provide us a basis for future studies aimed at understanding the molecular interactions of rhizobia and legumes.

  18. Rain Characteristics and Large-Scale Environments of Precipitation Objects with Extreme Rain Volumes from TRMM Observations

    Science.gov (United States)

    Zhou, Yaping; Lau, William K M.; Liu, Chuntao

    2013-01-01

    This study adopts a "precipitation object" approach by using 14 years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Feature (PF) and National Centers for Environmental Prediction (NCEP) reanalysis data to study rainfall structure and environmental factors associated with extreme heavy rain events. Characteristics of instantaneous extreme volumetric PFs are examined and compared to those of intermediate and small systems. It is found that instantaneous PFs exhibit a much wider scale range compared to the daily gridded precipitation accumulation range. The top 1% of the rainiest PFs contribute over 55% of total rainfall and have 2 orders of rain volume magnitude greater than those of the median PFs. We find a threshold near the top 10% beyond which the PFs grow exponentially into larger, deeper, and colder rain systems. NCEP reanalyses show that midlevel relative humidity and total precipitable water increase steadily with increasingly larger PFs, along with a rapid increase of 500 hPa upward vertical velocity beyond the top 10%. This provides the necessary moisture convergence to amplify and sustain the extreme events. The rapid increase in vertical motion is associated with the release of convective available potential energy (CAPE) in mature systems, as is evident in the increase in CAPE of PFs up to 10% and the subsequent dropoff. The study illustrates distinct stages in the development of an extreme rainfall event including: (1) a systematic buildup in large-scale temperature and moisture, (2) a rapid change in rain structure, (3) explosive growth of the PF size, and (4) a release of CAPE before the demise of the event.

  19. The characteristics of clusters of weather and extreme climate events in China during the past 50 years

    Institute of Scientific and Technical Information of China (English)

    Yang Ping; Hou Wei; Feng Guo-Lin

    2012-01-01

    The pick-up algorithm by the k-th order cluster for the closest distance is used in the fields of weather and climactic events,and the technical terms clustered index and high clustered region are defined to investigate their temporal and spatial distribution characteristics in China during the past 50 years.The results show that the contribution of extreme high-temperature event clusters changed in the period from the 1960s to the 1970s,and its strength was enhanced.On the other hand,the decreasing trend in the clusters of low-temperature extremes can be taken as a signal for warmer winters to follow in the decadal time scale.Torrential rain and heavy rainfall clusters have both been lessened in the past 50 years,and have different cluster characteristics because of their definitions.Regions with high clustered indexes are concentrated in southern China.The spatial evolution of the heavy rainfall clusters reveals that clustered heavy rainfall has played an important role in the rain-belt pattern over China during the last 50 years.

  20. Prognosis of complicated clinical course of varicose veins of lower extremities on the basis of analysis of phenotypic characteristics of connective tissue dysplasia

    OpenAIRE

    Tsarev О.А.; Anisimov A.Yu.; Zakharov N.N.

    2015-01-01

    Aim: to identify the phenotypic characteristics of indeterminate connective tissue dysplasia, which help to predict the progression of varicose veins of lower extremities and disease recurrence after surgery. Material and Methods. The long-term results of surgical treatment of 60 patients with varicose veins of lower extremities in a 5-year period after phlebectomy were analyzed. The phenotypic characteristics of indeterminate connective tissue dysplasia were researched. 24 patients had recur...

  1. Variation of IUH shapes with size of rainfall-runoff events in a small agricultural catchment

    Science.gov (United States)

    Banasik, Kazimierz; Hejduk, Leszek; Banasik, Jerzy

    2013-04-01

    Instantaneous unit hydrograph (IUH) is one of the key components in many procedures for design flood estimation. The IUH defined by gamma pdf, called also Nash model, has been estimated for each of the over 30 recorded rainfall-runoff events, in a small (A=82.4 km2), lowland, agricultural catchment located in central Poland, in the period 1980-2010 (Banasik et al., 2011). Variability of the IUH characteristics (such as lag time, time to peak, maximum ordinate) vs. rainfall-runoff parameters (such as peak discharge and runoff depth) will be presented. A larger variability of the IUH characteristics for smaller events was noted. Two methods for estimating, empirically based, representative IUH, for the catchment and for the design flood estimation, are presented. The first one is based on mean values of time to peak and peak ordinate of all individual IUHs, and the other one is taking into account only the largest events when the lag time has tendency to decrease with runoff depth increasing. The empirically estimated representative IUHs are compared with unit hydrograph of FSSR and ReFH (Kjeldsen 2007). Results of single event model application, with the IUH incorporated in it, are compared with results of FFA for this catchment. Banasik K., Hejduk L. and Oygarden L., 2011. Prediction and reduction of diffuse pollution, solid emission and extreme flows from rural areas - case study of small agricultural catchments. Warsaw University of Life Sciences Press, Warsaw. Kjeldsen T.R., 2007. Flood Estimation Handbook, Supplementary Report No. 1. The revitalized FSR/FEH rainfall-runoff method. Centre for Ecology & Hydrology, Wallingford, UK. ACKNOWLEDGMENTS The investigation described in the paper is part of the research project KORANET founded by PL-National Center for Research and Development.

  2. Bone characteristics of late-term embryonic and hatchling broilers: bone development under extreme growth rate.

    Science.gov (United States)

    Yair, R; Uni, Z; Shahar, R

    2012-10-01

    The development of broilers is an extreme example of rapid growth, increasing in weight from 40 g at hatch to 2,000 g 5 to 6 wk later. Such rapid growth requires a correspondingly fast development of the skeleton. Bone development is a genetically programmed process that is modified by epigenetic factors, mainly muscle-induced stresses and strains. In this study, we describe the temporal changes in bone morphology and material properties during the prehatch period [embryonic day (E) 14, E17, E19, E21] and posthatch d 3 and 7. The bones were examined for their weight, length, ash content, mechanical properties, and cortical structure. We show that the cross-sectional shape of the tibia and femur changes during the examination period from circular to elliptical. Additionally, the changes in bone properties are time-dependent and nonuniform: from E14 to E17 and from d 3 to 7, fast bone growth was noted, with major increases in both mechanical properties (stiffness, ultimate load, and energy to fracture) and geometric properties (cross-sectional area and thickness, medullary area, and moment of inertia). On the other hand, during the last days of incubation, most mechanical and geometric properties remain unchanged or even decrease. The reasons for this finding may relate to the hatching process but also to mineral shortage during the last days of incubation. This study leads to better understanding of bone development in ovo and posthatch in fast-growing broilers.

  3. Characteristics of episodes with extremely low ozone values in the northern middle latitudes 1957−2000

    Directory of Open Access Journals (Sweden)

    D. S. Balis

    Full Text Available A number of episodes are observed when the total ozone for 2 to 3 days has fallen below 220 matm-cm in the northern mid- and polar latitudes in autumn. The occurrences of such episodes represent ozone deviations of about one-third from the pre-1976 Oct-Nov-Dec monthly mean! By using primarily quality checked Dobson data, a clear identification was made of more than three dozen short spells with extremely low ozone in the 1957–1978 period. In the following twenty-two years (1979–2000, using mainly TOMS data, one can identify ~ 46 cases with ozone values falling below 220 matm-cm for longer than 1 day, with each time over an area greater than 500,000 km2 . The Ozone Mass Deficiency (O3MD from the pre-1976 average ozone values over the affected area was ~2.8 Mt per day, i.e. four to seven times greater than it would be, assuming only a long-term trend in the Oct-Nov-Dec period. The Extremely Low Ozone (ELO3 events on the day of their appearance over the N. Atlantic/European region contribute to the O3MD by representing 16% of the deficiency due to the Oct-Nov trend in the entire 40–65° N latitudinal belt. The O3MD of the greater pool with low ozone (here taken as <260 matm-cm surrounding the area of the lowest events could contribute on the day of their appearance in Oct-Nov up to 60% and in December, ~30% to the deficiency due to the trend over the entire 40–65° N belt. Analysis of synoptic charts, supported by a backward trajectory on the isentropic surfaces 350 and 380 K, shows that in most of the events, subtropical air masses with low ozone content were transported from the Atlantic toward the UK, Scandinavia, and in many cases, further to the western sub-polar regions of Russia. This transport was sometimes combined with upward motions above a tropospheric anticyclone which lifted low ozone mixing ratios to higher altitudes. The ELO3 events cause a significant deficiency above the tropopause where, in general, the subtropical air is

  4. Coronal mass ejections and other extreme characteristics of the 2003 October-November solar eruptions

    Science.gov (United States)

    Gopalswamy, N.; Yashiro, S.; Liu, Y.; Michalek, G.; Vourlidas, A.; Kaiser, M. L.; Howard, R. A.

    2005-09-01

    Fast coronal mass ejections (CMEs), X-class flares, solar energetic particle (SEP) events, and interplanetary shocks were abundantly observed during the episode of intense solar activity in late October and early November 2003. Most of the 80 CMEs originated from three active regions (NOAA ARs 484, 486, and 488). We compare the statistical properties of these CMEs with those of the general population of CMEs observed during cycle 23. We find that (1) the 2003 October-November CMEs were fast and wide on the average and hence were very energetic, (2) nearly 20 percent of the ultrafast CMEs (speed ≥2000 km s-1) of cycle 23 occurred during the October-November interval, including the fastest CME of the study period (˜2700 km s-1 on 4 November 2003 at 1954 UT), (3) the rate of full-halo CMEs was nearly four times the average rate during cycle 23, (4) at least sixteen shocks were observed near the Sun, while eight of them were intercepted by spacecraft along the Sun-Earth line, (5) the CMEs were highly geoeffective: the resulting geomagnetic storms were among the most intense of cycle 23, (6) the CMEs were associated with very large SEP events, including the largest event of cycle 23. These extreme properties were commensurate with the size and energy of the associated active regions. This study suggests that the speed of CMEs may not be much higher than ˜3000 km s-1, consistent with the free energy available in active regions. An important practical implication of such a speed limit is that the Sun-Earth travel times of CME-driven shocks may not be less than ˜0.5 day. Two of the shocks arrived at Earth in documented cases of such events since 1859.

  5. [Morphological characteristics and intracellular electrolytic composition of blood cells at surgeries on lower extremities arteries].

    Science.gov (United States)

    Katel'nitskiĭ, I I; Dudarev, I V; Matsionis, A E; Povilaĭtite, P E; Kvitko, I A

    2007-01-01

    Morphological characteristics and trace and macroelement composition of blood cells flowing out of ischemic lower limb before, during and after reconstructive surgeries under different type of anesthesia. A total of 102 male patients aged 45 to 60 years with atherosclerotic occlusions of the arteries of the femoral-popliteal zone were included into the study. According to anesthesia type all the patients were divided into 3 groups: group 1 consisted of 34 patients operated under spinal anesthesia, 37 patients of group 2 underwent surgery under combined anesthesia (spinal anesthesia with intravenous sedation), 31 patients of group 3 - under total intravenous anesthesia with myoplegia and artificial pulmonary ventilation. All the blood examinations were carried out with scanning electron microscope XL-30 ("Philips") and X-ray spectrum microanalyzer Edax ( "Edax International", USA). It is demonstrated that in spinal and combined anesthesia morphological characteristics of blood cells normalized due to optimization of intraerythrocytic and intrathrombocytic electrolytic homeostasis unlike total intravenous anesthesia, when intracellular imbalance of trace and macroelements progresses and ultrastructural cellular alterations persist.

  6. GREENROOF RUNOFF WATER QUALITY

    Science.gov (United States)

    Runoff samples were collected from 5 experimental green roof test plots on small buildings at the Center for Green Roof Research at Rock Springs, PA during the period from January 2005 through May 2006. Samples were either analyzed in-house for pH, Electrical Conductivity (EC), T...

  7. The power of runoff

    Science.gov (United States)

    Wörman, A.; Lindström, G.; Riml, J.

    2017-05-01

    Although the potential energy of surface water is a small part of Earth's energy budget, this highly variable physical property is a key component in the terrestrial hydrologic cycle empowering geomorphological and hydrological processes throughout the hydrosphere. By downscaling of the daily hydrometeorological data acquired in Sweden over the last half-century this study quantifies the spatial and temporal distribution of the dominating energy components in terrestrial hydrology, including the frictional resistance in surface water and groundwater as well as hydropower. The energy consumed in groundwater circulation was found to be 34.6 TWh/y or a heat production of approximately 13% of the geothermal heat flux. Significant climate driven, periodic fluctuations in the power of runoff, stream flows and groundwater circulation were revealed that have not previously been documented. We found that the runoff power ranged from 173 to 260 TWh/y even when averaged over the entire surface of Sweden in a five-year moving window. We separated short-term fluctuations in runoff due to precipitation filtered through the watershed from longer-term seasonal and climate driven modes. Strong climate driven correlations between the power of runoff and climate indices, wind and solar intensity were found over periods of 3.6 and 8 years. The high covariance that we found between the potential energy of surface water and wind energy implies significant challenges for the combination of these renewable energy sources.

  8. Dose and scatter characteristics of a novel cone beam CT system for musculoskeletal extremities

    Science.gov (United States)

    Zbijewski, W.; Sisniega, A.; Vaquero, J. J.; Muhit, A.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Carrino, J. A.; Siewerdsen, J. H.

    2012-03-01

    A novel cone-beam CT (CBCT) system has been developed with promising capabilities for musculoskeletal imaging (e.g., weight-bearing extremities and combined radiographic / volumetric imaging). The prototype system demonstrates diagnostic-quality imaging performance, while the compact geometry and short scan orbit raise new considerations for scatter management and dose characterization that challenge conventional methods. The compact geometry leads to elevated, heterogeneous x-ray scatter distributions - even for small anatomical sites (e.g., knee or wrist), and the short scan orbit results in a non-uniform dose distribution. These complex dose and scatter distributions were investigated via experimental measurements and GPU-accelerated Monte Carlo (MC) simulation. The combination provided a powerful basis for characterizing dose distributions in patient-specific anatomy, investigating the benefits of an antiscatter grid, and examining distinct contributions of coherent and incoherent scatter in artifact correction. Measurements with a 16 cm CTDI phantom show that the dose from the short-scan orbit (0.09 mGy/mAs at isocenter) varies from 0.16 to 0.05 mGy/mAs at various locations on the periphery (all obtained at 80 kVp). MC estimation agreed with dose measurements within 10-15%. Dose distribution in patient-specific anatomy was computed with MC, confirming such heterogeneity and highlighting the elevated energy deposition in bone (factor of ~5-10) compared to soft-tissue. Scatter-to-primary ratio (SPR) up to ~1.5-2 was evident in some regions of the knee. A 10:1 antiscatter grid was found earlier to result in significant improvement in soft-tissue imaging performance without increase in dose. The results of MC simulations elucidated the mechanism behind scatter reduction in the presence of a grid. A ~3-fold reduction in average SPR was found in the MC simulations; however, a linear grid was found to impart additional heterogeneity in the scatter distribution

  9. Patient-, treatment-, and facility-level structural characteristics associated with the receipt of preoperative lower extremity amputation rehabilitation.

    Science.gov (United States)

    Bates, Barbara E; Hallenbeck, Richard; Ferrario, Toni; Kwong, Pui L; Kurichi, Jibby E; Stineman, Margaret G; Xie, Dawei

    2013-01-01

    To determine patient, treatment, or facility characteristics that influence decisions to initiate a rehabilitation assessment before transtibial or transfemoral amputation within the Veterans Affairs (VA) health care system. Retrospective database study. VA medical centers. A total of 4226 veterans with lower extremity amputations discharged from a VA medical center between October 1, 2002, and September 30, 2004. Evidence of a preoperative rehabilitation assessment after the index surgical stay admission but before the surgical date. Evidence was found that 343 of 4226 veterans (8.12%) with lower extremity amputations received preoperative rehabilitation assessments. Veterans receiving preoperative rehabilitation were more likely to be older, admitted from home, or transferred from another hospital. Patients who underwent surgical amputation at smaller-sized hospitals or in the South Central or Mountain Pacific regions were more likely to receive preoperative rehabilitation compared with patients in mid-sized hospitals or in the Northeast, Southeast, or Midwest regions. Patients with evidence of paralysis, patients treated in facilities with programs accredited by the Commission on Accreditation of Rehabilitation Facilities (P facility-level structural characteristics, we found that older patients were more likely to receive preoperative rehabilitation services (odds ratio [OR] 1.01, 95% confidence interval [CI] 1.01-1.02). Patients with a contributing amputation etiology of a previous amputation complication were more likely to receive preoperative consultation rehabilitation services (OR 1.50, 95% CI 1.02-2.19) compared with patients who did not have this etiology. Compared with patients treated in the Southeast region of the United States, those treated in the South Central region (OR 2.52, 95% CI 1.82-3.48) or Mountain Pacific region (OR 1.62, 95% CI 1.11-2.37) were more likely to receive preoperative consultation rehabilitation services. Patients with

  10. Quantifying the present-day human influence on temperature, precipitation, and runoff in an pre-Alpine Swiss catchment

    Science.gov (United States)

    Mülchi, Regula; Rössler, Ole; Romppainen-Martius, Olivia; Pall, Pardeep; Weingartner, Rolf

    2017-04-01

    Understanding the influence of anthropogenic greenhouse gas (GHG) emissions on climate and environmental variables is still a challenge in science. Many detection and attribution studies have been carried out focusing on global and regional scales or on single events. However, the influence of anthropogenic greenhouse gas emission on both, runoff regime and driving meteorological characteristics is still an open question. This study assesses the influence of anthropogenic GHG emissions on temperature, precipitation, and river runoff in a pre-Alpine catchment in Switzerland. For this purpose, thousands of one-year (April 2000-March 2001) simulations representing both, a present-day climate with actual anthropogenic GHG concentrations (A2000), and a climate with pre-industrial GHG concentrations (A2000N) were bias-corrected and used to analyze changes in temperature and precipitation. The two variables were then used to drive the hydrological model GR4J including the snow module Cemaneige for the river Thur (1700 km2). Comparing the runoff of the two scenarios and calculating the fraction of attributable risk (FAR) as well as the change in probability of occurrence (PR) for specific runoff thresholds enabled the assessment of the influence of anthropogenic GHG emissions. We found higher mean runoff in winter and spring in the A2000 scenario compared to the A2000N scenario. This is mainly caused by the combination of higher precipitation and higher temperatures in winter resulting in less snow accumulation in the A2000 scenario. Therefore, more liquid water is available in the hydrological model leading to enhanced runoff. In contrast, the A2000 simulations exhibit lower runoff in summer and autumn than the A2000N simulations. We relate this to higher temperatures in the A2000 scenario enhancing evapotranspiration and lower precipitation amounts. The calculation of FAR and PR for different runoff thresholds indicates that the FAR and PR increase with higher thresholds

  11. Early retirement among Danish female cleaners and shop assistants according to work environment characteristics and upper extremity complaints

    DEFF Research Database (Denmark)

    Jensen, Lone Donbæk; Bonde, Jens Peter Ellekilde; Christensen, Michael Victor

    2016-01-01

    -year cohort study with registry-based follow-up of 1430 female cleaners and 579 shop assistants. In subsequent analyses of female cleaners, disability pension and voluntary early retirement were modeled according to work characteristics and upper extremity complaints. RESULTS: The adjusted hazard rate......BACKGROUND: Studies have shown a negative social gradient in the incidence of early retirement. To prevent undesired early retirement, there is a need for knowledge of specific predictors in addition to social factors with a limited potential for change. The main purpose of this study...... was to examine musculoskeletal complaints and working conditions as predictors of early retirement among Danish female cleaners. METHODS: Using Cox regression with an adjustment for extraneous factors, we compared the risk of disability pension and retirement before the nominal retirement age (65 years) in an 11...

  12. The Stellar Abundances for Galactic Archeology (SAGA) Database - Compilation of the Characteristics of Known Extremely Metal-Poor Stars

    CERN Document Server

    Suda, Takuma; Yamada, Shimako; Suwa, Tamon; Ishizuka, Chikako; Komiya, Yutaka; Sorai, Kazuo; Aikawa, Masayuki; Fujimoto, Masayuki Y

    2008-01-01

    We describe the construction of a database of extremely metal-poor (EMP) stars in the Galactic halo whose elemental abundances have been determined. Our database contains detailed elemental abundances, reported equivalent widths, atmospheric parameters, photometry, and binarity status, compiled from papers in the recent literature that report studies of EMP halo stars with [Fe/H] < -2.5. The compilation procedures for this database have been designed to assemble the data effectively from electronic tables available from online journals. We have also developed a data retrieval system that enables data searches by various criteria, and permits the user to explore relationships between the stored variables graphically. Currently, our sample includes 1212 unique stars (many of which are studied by more than one group) with more than 15000 individual reported elemental abundances, covering all of the relevant papers published by December 2007. We discuss the global characteristics of the present database, as re...

  13. Temporal and spatial characteristics of extreme precipitation events in the Midwest of Jilin Province based on multifractal detrended fluctuation analysis method and copula functions

    Science.gov (United States)

    Guo, Enliang; Zhang, Jiquan; Si, Ha; Dong, Zhenhua; Cao, Tiehua; Lan, Wu

    2016-08-01

    Environmental changes have brought about significant changes and challenges to water resources and management in the world; these include increasing climate variability, land use change, intensive agriculture, and rapid urbanization and industrial development, especially much more frequency extreme precipitation events. All of which greatly affect water resource and the development of social economy. In this study, we take extreme precipitation events in the Midwest of Jilin Province as an example; daily precipitation data during 1960-2014 are used. The threshold of extreme precipitation events is defined by multifractal detrended fluctuation analysis (MF-DFA) method. Extreme precipitation (EP), extreme precipitation ratio (EPR), and intensity of extreme precipitation (EPI) are selected as the extreme precipitation indicators, and then the Kolmogorov-Smirnov (K-S) test is employed to determine the optimal probability distribution function of extreme precipitation indicators. On this basis, copulas connect nonparametric estimation method and the Akaike Information Criterion (AIC) method is adopted to determine the bivariate copula function. Finally, we analyze the characteristics of single variable extremum and bivariate joint probability distribution of the extreme precipitation events. The results show that the threshold of extreme precipitation events in semi-arid areas is far less than that in subhumid areas. The extreme precipitation frequency shows a significant decline while the extreme precipitation intensity shows a trend of growth; there are significant differences in spatiotemporal of extreme precipitation events. The spatial variation trend of the joint return period gets shorter from the west to the east. The spatial distribution of co-occurrence return period takes on contrary changes and it is longer than the joint return period.

  14. Spatiotemporal characteristics and synchronization of extreme rainfall in South America with focus on the Andes Mountain range

    Science.gov (United States)

    Boers, Niklas; Bookhagen, Bodo; Marwan, Norbert; Kurths, Jürgen

    2016-01-01

    The South American Andes are frequently exposed to intense rainfall events with varying moisture sources and precipitation-forming processes. In this study, we assess the spatiotemporal characteristics and geographical origins of rainfall over the South American continent. Using high-spatiotemporal resolution satellite data (TRMM 3B42 V7), we define four different types of rainfall events based on their (1) high magnitude, (2) long temporal extent, (3) large spatial extent, and (4) high magnitude, long temporal and large spatial extent combined. In a first step, we analyze the spatiotemporal characteristics of these events over the entire South American continent and integrate their impact for the main Andean hydrologic catchments. Our results indicate that events of type 1 make the overall highest contributions to total seasonal rainfall (up to 50 %). However, each consecutive episode of the infrequent events of type 4 still accounts for up to 20 % of total seasonal rainfall in the subtropical Argentinean plains. In a second step, we employ complex network theory to unravel possibly non-linear and long-ranged climatic linkages for these four event types on the high-elevation Altiplano-Puna Plateau as well as in the main river catchments along the foothills of the Andes. Our results suggest that one to two particularly large squall lines per season, originating from northern Brazil, indirectly trigger large, long-lasting thunderstorms on the Altiplano Plateau. In general, we observe that extreme rainfall in the catchments north of approximately 20°S typically originates from the Amazon Basin, while extreme rainfall at the eastern Andean foothills south of 20°S and the Puna Plateau originates from southeastern South America.

  15. Soil water, salt, and groundwater characteristics in shelterbelts with no irrigation for several years in an extremely arid area.

    Science.gov (United States)

    Zhao, Xinfeng; Xu, Hailiang; Zhang, Peng; Fu, Jinyi; Bai, Yuan

    2013-12-01

    This paper is based on long-term monitoring data for soil water, salt content, and groundwater characteristics taken from shelterbelts where there has been no irrigation for at least 5 years. This study investigated the distribution characteristics of soil water and salt content in soils with different textures. The relationships between soil moisture, soil salinity, and groundwater level were analyzed using 3 years of monitoring data from a typical oasis located in an extremely arid area in northwest China. The results showed that (1) the variation trend in soil moisture with soil depth in the shelterbelts varied depending on soil texture. The soil moisture was lower in sandy and loamy shelterbelts and higher in clay shelterbelts. (2) Salinity was higher (about 3.0 mS cm(-1)) in clay shelterbelts and lower (about 0.8 mS cm(-1)) in sandy shelterbelts. (3) There was a negative correlation between soil moisture in the shelterbelts and groundwater level. Soil moisture decreased gradually as the depth of groundwater table declined. (4) There was a positive correlation between soil salinity in the shelterbelts and the depth of groundwater table. Salinity increased gradually as groundwater levels declined.

  16. Precipitation-runoff modeling system; user's manual

    Science.gov (United States)

    Leavesley, G.H.; Lichty, R.W.; Troutman, B.M.; Saindon, L.G.

    1983-01-01

    The concepts, structure, theoretical development, and data requirements of the precipitation-runoff modeling system (PRMS) are described. The precipitation-runoff modeling system is a modular-design, deterministic, distributed-parameter modeling system developed to evaluate the impacts of various combinations of precipitation, climate, and land use on streamflow, sediment yields, and general basin hydrology. Basin response to normal and extreme rainfall and snowmelt can be simulated to evaluate changes in water balance relationships, flow regimes, flood peaks and volumes, soil-water relationships, sediment yields, and groundwater recharge. Parameter-optimization and sensitivity analysis capabilites are provided to fit selected model parameters and evaluate their individual and joint effects on model output. The modular design provides a flexible framework for continued model system enhancement and hydrologic modeling research and development. (Author 's abstract)

  17. Prognosis of complicated clinical course of varicose veins of lower extremities on the basis of analysis of phenotypic characteristics of connective tissue dysplasia

    Directory of Open Access Journals (Sweden)

    Tsarev О.А.

    2015-12-01

    Full Text Available Aim: to identify the phenotypic characteristics of indeterminate connective tissue dysplasia, which help to predict the progression of varicose veins of lower extremities and disease recurrence after surgery. Material and Methods. The long-term results of surgical treatment of 60 patients with varicose veins of lower extremities in a 5-year period after phlebectomy were analyzed. The phenotypic characteristics of indeterminate connective tissue dysplasia were researched. 24 patients had recurrence of varicose veins of lower extremities associated with disease progression; 36 patients did not have recurrence of varicose veins of lower extremities. Results. All the patients demonstrated the signs of indeterminate connective tissue dysplasia, whereas their frequency was different. There were specified nine phenotypic characteristics of indeterminate connective tissue dysplasia, which were significantly more frequent for patients with recurrence of varicose vein disease of lower extremities: 1 postural abnormality, 2 flat foot, 3 skin pallor, 4 hyperextension of skin, 5 positive "wrist test", 6 positive "pollex test", 7 diastasis recti abdominis, 8 myopia, 9 hematomas which form quickly. Conclusion. The determined sum of phenotypic characters of indeterminate connective tissue dysplasia allows to predict progression of varicose vein disease of lower extremities, and offers new opportunities for improving the results of surgical treatment via developing special therapeutic measures aimed at improving lifestyle and dysplasia treatment.

  18. STUDY OF RUNOFF IN UNDA WATERSHED

    Directory of Open Access Journals (Sweden)

    SATRIA WAHYU 0ETOM0

    2015-06-01

    Full Text Available When rain falls on the earth, it just does not sit there, it starts moving according to the laws of gravity. A portion of the precipitation seeps into the ground to replenish Earth's groundwater. Most of it flows downhill as runoff. Runoff is extremely important in that not only does it keep rivers and lakes full of water, but it also changes the landscape by the action of erosion. The purpose and objective in this study are to estimate the conditions of land cover of Unda Watershed based on the results of image processing, to estimate the monthly average runoff and discharge in outlet of Unda Watershed from 1999 to 2003. The research location is in Unda Watershed. This watershed lies in Province of Bali which has wide 233.1 km2 (23.310 Ha (Balai Wilayah Sungai Bali-Penida. Administratively this watershed lies in 3 Regencies that are Karangasem, Klungkung and Bangli Regency. Mostly the region lies in the Karangasem Regency. In this research, the monthly rainfall data employed to generate the runoff process. Analyze of contour map from topography map obtained the watershed area, physical parameter of river and concentration time. In this research used monthly average rainf all data (from 1999 to 2003 from Pempatan, Besakih, Singarata, Sidemen, Klungkung, Telengan, Rain Gauge Station and Polygon Thiesen method employed to analyze the datas. Apart of rainfall, there are a number of site specific factors which have a direct bearing on the occurrence and volume of runoff, they are soil type, land cover and slope. The soil types in this research area are all Regosol, this soil mapping does not need to be overlayed in obtaining the land unit. Analyze of land cover was employed by Supervised Classification method. By image processing obtained land cover of Unda Watershed estimated consists of 38.129 km2 of forest area (16.357°Ai, 19.122 km2 of grassland area (8.203%, 100.991 km2 of farmland area (43.325%, 62-412 km2 of area housing (26.775%, 2.625 km2

  19. Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley.

    Science.gov (United States)

    Otto, Stefan; Pappalardo, Salvatore E; Cardinali, Alessandra; Masin, Roberta; Zanin, Giuseppe; Borin, Maurizio

    2016-01-01

    In intensive agricultural systems runoff is one of the major potential diffuse pollution pathways for pesticides and poses a risk to surface water. Ditches are common in the Po Valley and can potentially provide runoff mitigation for the protection of watercourses. The effectiveness depends on ditch characteristics, so there is an urgent need for site-specific field trials. The use of a fugacity model (multimedia model) can allows recognition of the mitigation main processes. A field experiment was conducted in order to evaluate the mitigation capacity of a typical vegetated ditch, and results were compared with predictions by a fugacity model. To evaluate herbicide mitigation after an extreme runoff, the ditch was flooded with water containing mesotrione, S-metolachlor and terbuthylazine. Two other subsequent floods with uncontaminated water were applied 27 and 82 days later to evaluate herbicides release. Results show that the ditch can immediately reduce runoff concentration of herbicides by at least 50% even in extreme flooding conditions. The half-distances were about 250 m. As a general rule, a runoff of 1 mm from 5 ha is mitigated by 99% in 100 m of vegetated ditch. Herbicides retention in the vegetated ditch was reversible, and the second flood mobilized 0.03-0.2% of the previous one, with a concentration below the drinking water limit of 0.1 μg L(-1). No herbicide was detected in the third flood, because the residual amount in the ditch was too low. Fugacity model results show that specific physical-chemical parameters may be used and a specific soil-sediment-plant compartment included for modelling herbicides behaviour in a vegetated ditch, and confirm that accumulation is low or negligible for herbicides with a half-life of 40 days or less. Shallow vegetated ditches can thus be included in a general agri-environment scheme for the mitigation of pesticides runoff together with wetlands and linear buffer strips. These structures are present in the

  20. INTEGRATED PROJECTION FOR RUNOFF CHANGES IN LARGE RUSSIAN RIVER BASINS IN THE XXI CENTURY

    Directory of Open Access Journals (Sweden)

    Alexander G. Georgiadi

    2016-01-01

    Full Text Available The paper discusses an approach to a long-term forecast of river runoff changes for Russian large river basins in the first third of the XXI century caused by climate warming and social-economic changes. The approach considers runoff changes under a range of possible climate warming effects. This range is chosen by generalizing the calculation results obtained by using an ensemble of global climate models within CMIP 3 and CMIP 5 experiments for twocontrasting scenarios (A2/RCP 8.5 and B1/RCP 2.6 of globally averaged air temperature rises. The approach also utilizes a method for alternative scenario for water consumption related to socio-economic changes. The obtained scenario estimates show that expected changes in the Volga and Don annual river runoff and its intra-annual distribution in the first third of this century can be relatively small, while changes in water use characteristics may be extremely negative in some scenarios, especially in the Don River basin.

  1. Advances in rainfall-runoff estimation using the NRCS-CN model in a changing climate in semiarid zones in both the northern and southern hemispheres

    Science.gov (United States)

    Durán-Barroso, Pablo; João Simas Guerreiro, Maria; De Andrade, Eunice Maia; González, Javier

    2016-04-01

    Extreme events runoff is one of the most important variables in water resources management, but its quantification in semiarid watersheds is not easy, especially because of their large retention capacity. In the worldwide used NRCS Curve Number model (CN), retention capacity is conditioned by the initial abstraction parameter, for which this manuscript questions its assessment procedure. We propose a more accurate procedure to compute the initial abstractions based on previous cumulative dry days (CDD). We also analyze the combined effect of initial abstractions and climatic characteristics by analyzing CN in a dry (Walnut Gulch, US) and wet (Ceará, Brazil) semiarid environment. With this new methodology and the evolution of rainfall volumes and CDD analysis, it is possible to suggest consequences of climate change on floods forecast of extreme rainfall-runoff events in a semiarid environment.

  2. 近50年泾河流域降雨-径流关系变化及驱动因素定量分析%Variation characteristics of rainfall-runoff relationship and driving factors analysis in Jinghe river basin in nearly 50 years

    Institute of Scientific and Technical Information of China (English)

    郭爱军; 畅建霞; 王义民; 黎云云

    2015-01-01

    Under the background of changing global environment and frequent anthropogenic activities, rainfall-runoff relationship has suffered tremendous change in many regions of China, particularly in arid and semi-arid regions. The Jinghe River basin (JRB) in the middle of the Loess Plateau, which is the major base of grain production in Shannxi Province, has experienced significant changes in hydro-climatic variables and the relationship between them during the past decades, causing many water resources problems. In this paper, we focused on analyzing the variation characteristics of rainfall-runoff relationship in JRB, and quantitatively assessing the effects of climate changes and human activities on the runoff reduction. It was of great importance for mastering the evolution of hydrological cycle, water resources planning and management, and water and soil conservation in JRB. The monthly rainfall and runoff data were used in the study and summed annually to investigate the variation characteristics in 1960-2010. To detect the change points of rainfall-runoff relationship, the sliding partial correlation coefficients method was proposed and the change points were further confirmed by the double mass curve method. On the basis of the studies, the relative changes of rainfall, runoff, and rainfall-runoff relationship were analyzed around the change points. Moreover, we also introduced the Archimedean Copula function, from the perspective of probability, to analyze the probability of synchronous-asynchronous encounter of rainfall and runoff in JRB. What caused the variation of rainfall-runoff relationship? Climate change or human activities? To figure out this, the method of slope change ratio of cumulative quantity (SCRCQ) was adopted in this paper. According to these results, we obtained the following conclusions: (i) Annual runoff and rainfall presented wavelike decrease change. Nevertheless, annual runoff declined more greatly than rainfall; especially, in some

  3. Flood damage claims reveal insights about surface runoff in Switzerland

    Science.gov (United States)

    Bernet, D. B.; Prasuhn, V.; Weingartner, R.

    2015-12-01

    A few case studies in Switzerland exemplify that not only overtopping water bodies frequently cause damages to buildings. Reportedly, a large share of the total loss due to flooding in Switzerland goes back to surface runoff that is formed and is propagating outside of regular watercourses. Nevertheless, little is known about when, where and why such surface runoff occurs. The described process encompasses surface runoff formation, followed by unchannelised overland flow until a water body is reached. It is understood as a type of flash flood, has short response times and occurs diffusely in the landscape. Thus, the process is difficult to observe and study directly. A promising source indicating surface runoff indirectly are houseowners' damage claims recorded by Swiss Public Insurance Companies for Buildings (PICB). In most of Switzerland, PICB hold a monopoly position and insure (almost) every building. Consequently, PICB generally register all damages to buildings caused by an insured natural hazard (including surface runoff) within the respective zones. We have gathered gapless flood related claim records of most of all Swiss PICB covering more than the last two decades on average. Based on a subset, we have developed a methodology to differentiate claims related to surface runoff from other causes. This allows us to assess the number of claims as well as total loss related to surface runoff and compare these to the numbers of overtopping watercourses. Furthermore, with the good data coverage, we are able to analyze surface runoff related claims in space and time, from which we can infer spatial and temporal characteristics of surface runoff. Although the delivered data of PICB are heterogeneous and, consequently, time-consuming to harmonize, our first results show that exploiting these damage claim records is feasible and worthwhile to learn more about surface runoff in Switzerland.

  4. Hydrochemical Characteristics and Controls of Runoff at the Headwaters of the Urumqi River, Eastern Tianshan Mountain%天山乌鲁木齐河源区径流水化学特征及影响因素分析

    Institute of Scientific and Technical Information of China (English)

    冯芳; 李忠勤; 张明军; 金爽; 王飞腾

    2011-01-01

    在乌鲁木齐河源区采集两年的大气降水和1号冰川、空冰斗、总控3个水文点逐日定时径流样品,对主要离子、pH、电导率EC和总溶解固体TDS进行了分析。结果表明,大气降水离子类型为Ca^2+-Na^+-HCO3--SO4^2-,接近中性;径流离子类型为Ca^2+-Na^+-HCO3--SO4^2-,呈弱碱性。径流中EC和TDS均值总控〉1号冰川〉空冰斗,其中1号冰川径流的峰值远高于其它两个水文点。受不同下垫面的影响,1号冰川水文点TDS变化受日径流量影响显著,而空冰斗水文点基本不受影响。径流中离子组成主要受岩石风化作用影响,离子比值和Piper图分析说明控制径流离子的主要过程是碳酸盐、黄铁矿和长石类矿物风化。海盐校正分析得出,大气降水对1号冰川、空冰斗、总控径流离子贡献率分别为4.91%,9.10%和5.42%。通过阳离子通量计算,2006年、2007年1号冰川径流的化学风化侵蚀率分别为18.1t/(km^2·a)和12.3t/(km^2·a)。%Glacierised alpine basins present an ideal environment for studying interactions between water and rock, since chemical weathering rates are generally high and anthropogenic impacts are often minimal. Studies on glacier hydrochemistry are still at an initial stage in China, with less data being published on glacierized catchments. An analytical study of hydrochemical characteristics and controls of the proglacial streams at the headwaters of the Urumqi River were carried out in this study. Over the period from May 2006 through April 2008, a 2-year continuous precipitation and runoff samples were analyzed for major cations (Mg^2+, Ca^2+, Na^+, and K^+) and anions (SO42-, NO; and Cl-), pH, electrical conductivity (EC), and total dissolved solids (TDS). Results reveal that Ca^2+ and Na + were the dominant cations, and HCOf and SO,2 were the dominant anions in precipitation. The anions and cations

  5. [A review of green roof performance towards management of roof runoff].

    Science.gov (United States)

    Chen, Xiao-ping; Huang, Pei; Zhou, Zhi-xiang; Gao, Chi

    2015-08-01

    Green roof has a significant influence on reducing runoff volume, delaying runoff-yielding time, reducing the peak flow and improving runoff quality. This paper addressed the related research around the world and concluded from several aspects, i.e., the definition of green roof of different types, the mechanism how green roof manages runoff quantity and quality, the ability how green roof controls roof runoff, and the influence factors of green roof toward runoff quantity and quality. Afterwards, there was a need for more future work on research of green roof toward roof runoff, i.e., vegetation selection of green roof, efficient construction model selection of green roof, the regulating characteristics of green roof on roof runoff, the value assessment of green roof on roof runoff, analysis of source-sink function of green roof on the water pollutants of roof runoff and the research on the mitigation measures of roof runoff pollution. This paper provided a guideline to develop green roofs aiming to regulating roof runoff.

  6. SPATIAL DISTRIBUTION OF THE AVERAGE RUNOFF IN THE IZA AND VIȘEU WATERSHEDS

    Directory of Open Access Journals (Sweden)

    HORVÁTH CS.

    2015-03-01

    Full Text Available The average runoff represents the main parameter with which one can best evaluate an area’s water resources and it is also an important characteristic in al river runoff research. In this paper we choose a GIS methodology for assessing the spatial evolution of the average runoff, using validity curves we identifies three validity areas in which the runoff changes differently with altitude. The tree curves were charted using the average runoff values of 16 hydrometric stations from the area, eight in the Vișeu and eight in the Iza river catchment. Identifying the appropriate areas of the obtained correlations curves (between specific average runoff and catchments mean altitude allowed the assessment of potential runoff at catchment level and on altitudinal intervals. By integrating the curves functions in to GIS we created an average runoff map for the area; from which one can easily extract runoff data using GIS spatial analyst functions. The study shows that from the three areas the highest runoff corresponds with the third zone but because it’s small area the water volume is also minor. It is also shown that with the use of the created runoff map we can compute relatively quickly correct runoff values for areas without hydrologic control.

  7. A noise-optimized virtual monochromatic reconstruction algorithm improves stent visualization and diagnostic accuracy for detection of in-stent re-stenosis in lower extremity run-off CT angiography.

    Science.gov (United States)

    Mangold, Stefanie; De Cecco, Carlo N; Schoepf, U Joseph; Yamada, Ricardo T; Varga-Szemes, Akos; Stubenrauch, Andrew C; Caruso, Damiano; Fuller, Stephen R; Vogl, Thomas J; Nikolaou, Konstantin; Todoran, Thomas M; Wichmann, Julian L

    2016-12-01

    To evaluate the impact of noise-optimized virtual monochromatic imaging (VMI+) on stent visualization and accuracy for in-stent re-stenosis at lower extremity dual-energy CT angiography (DE-CTA). We evaluated third-generation dual-source DE-CTA studies in 31 patients with prior stent placement. Images were reconstructed with linear blending (F_0.5) and VMI+ at 40-150 keV. In-stent luminal diameter was measured and contrast-to-noise ratio (CNR) calculated. Diagnostic confidence was determined using a five-point scale. In 21 patients with invasive catheter angiography, accuracy for significant re-stenosis (≥50 %) was assessed at F_0.5 and 80 keV-VMI+ chosen as the optimal energy level based on image-quality analysis. At CTA, 45 stents were present. DSA was available for 28 stents whereas 12 stents showed significant re-stenosis. CNR was significantly higher with ≤80 keV-VMI+ (17.9 ± 6.4-33.7 ± 12.3) compared to F_0.5 (16.9 ± 4.8; all p VMI+ (4.90 ± 0.48-4.88 ± 0.63 vs. 4.60 ± 0.66, p = 0.001, 0.0042). Sensitivity, negative predictive value and accuracy for re-stenosis were higher with 80 keV-VMI+ (100, 100, 96.4 %) than F_0.5 (90.9, 94.1, 89.3 %). 80 keV-VMI+ improves image quality, diagnostic confidence and accuracy for stent evaluation at lower extremity DE-CTA. • The impact of noise-optimized virtual monochromatic imaging on stent visualization was assessed. • Virtual monochromatic imaging significantly improves stent lumen visualization and diagnostic confidence. • At 80 keV diagnostic performance for detection of in-stent restenosis was increased. • 80 keV virtual monochromatic images are recommended for stent evaluation of lower extremity vasculature.

  8. Runoff inundation hazard cartography

    Science.gov (United States)

    Pineux, N.; Degré, A.

    2012-04-01

    Between 1998 and 2004, Europe suffered from more than hundred major inundations, responsible for some 700 deaths, for the moving of about half a million of people and the economic losses of at least 25 billions Euros covered by the insurance policies. Within this context, EU launched the 2007/60/CE directive. The inundations are natural phenomenon. They cannot be avoided. Nevertheless this directive permits to better evaluate the risks and to coordinate the management measures taken at member states level. In most countries, inundation maps only include rivers' overflowing. In Wallonia, overland flows and mudflows also cause huge damages, and must be included in the flood hazard map. Indeed, the cleaning operations for a village can lead to an estimated cost of 11 000 €. Average construction cost of retention dams to control off-site damage caused by floods and muddy flows was valued at 380 000€, and yearly dredging costs associated with these retention ponds at 15 000€. For a small city for which a study was done in a more specific way (Gembloux), the mean annual cost for the damages that can generate the runoff is about 20 000€. This cost consists of the physical damages caused to the real estate and movable properties of the residents as well as the emergency operations of the firemen and the city. On top of damages to public infrastructure (clogging of trenches, silting up of retention ponds) and to private property by muddy flows, runoff generates a significant loss of arable land. Yet, the soil resource is not an unlimited commodity. Moreover, sediments' transfer to watercourses alters their physical and chemical quality. And that is not to mention the increased psychological stress for people. But to map overland flood and mud flow hazard is a real challenge. This poster will present the methodology used to in Wallonia. The methodology is based on 3 project rainfalls: 25, 50 and 100 years return period (consistency with the cartography of the

  9. Spatial characteristics of extreme rainfall over China with hourly through 24-hour accumulation periods based on national-level hourly rain gauge data

    Science.gov (United States)

    Zheng, Yongguang; Xue, Ming; Li, Bo; Chen, Jiong; Tao, Zuyu

    2016-11-01

    Hourly rainfall measurements of 1919 national-level meteorological stations from 1981 through 2012 are used to document, for the first time, the climatology of extreme rainfall in hourly through 24-h accumulation periods in China. Rainfall amounts for 3-, 6-, 12- and 24-h periods at each station are constructed through running accumulation from hourly rainfall data that have been screened by proper quality control procedures. For each station and for each accumulation period, the historical maximum is found, and the corresponding 50-year return values are estimated using generalized extreme value theory. Based on the percentiles of the two types of extreme rainfall values among all the stations, standard thresholds separating Grade I, Grade II and Grade III extreme rainfall are established, which roughly correspond to the 70th and 90th percentiles for each of the accumulation periods. The spatial characteristics of the two types of extreme rainfall are then examined for different accumulation periods. The spatial distributions of extreme rainfall in hourly through 6-h periods are more similar than those of 12- and 24-h periods. Grade III rainfall is mostly found over South China, the western Sichuan Basin, along the southern and eastern coastlines, and in the large river basins and plains. There are similar numbers of stations with Grade III extreme hourly rainfall north and south of 30°N, but the percentage increases to about 70% south of 30°N as the accumulation period increases to 24 hours, reflecting richer moisture and more prolonged rain events in southern China. Potential applications of the extreme rainfall climatology and classification standards are suggested at the end.

  10. Derivation of climate elasticity of runoff to assess the effects of climate change on annual runoff

    Science.gov (United States)

    Yang, Hanbo; Yang, Dawen

    2011-07-01

    Climate elasticity of runoff is an important indicator for evaluating the effects of climate change on runoff. Consequently, this paper proposes an analytical derivation of climate elasticity. Based on the mean annual water-energy balance equation, two dimensionless numbers (the elasticities of runoff to precipitation and potential evaporation) were derived. Combining the first-order differential of the Penman equation, the elasticities of runoff to precipitation, net radiation, air temperature, wind speed, and relative humidity were derived to separate the contributions of different climatic variables. The case study was carried out in the Futuo River catchment in the Hai River basin, as well as in 89 catchments of the Hai River and the Yellow River basins of China. Based on the mean annual of climatic variables, the climate elasticity in the Futuo River basin was estimated as follows: precipitation elasticity ?, net radiation elasticity ?, air temperature elasticity ?, wind speed elasticity ?, and relative humidity elasticity ?. In this catchment, precipitation decrease was mainly responsible for runoff decline, and wind speed decline had the second greatest effect on runoff. In the 89 catchments of the Hai River and the Yellow River basins of China, climate elasticity was estimated as follows: ? ranging from 1.6 to 3.9, ? ranging from -1.9 to -0.3, ? ranging from -0.11 to -0.02°C-1, ? ranging from -0.8 to -0.1, and ? ranging from 0.2 to 1.9. Additional analysis shows that climate elasticity was sensitive to catchment characteristics.

  11. A noise-optimized virtual monochromatic reconstruction algorithm improves stent visualization and diagnostic accuracy for detection of in-stent re-stenosis in lower extremity run-off CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Mangold, Stefanie [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); De Cecco, Carlo N.; Yamada, Ricardo T.; Varga-Szemes, Akos; Stubenrauch, Andrew C.; Fuller, Stephen R. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Schoepf, U.J. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Caruso, Damiano [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Rome ' ' Sapienza' ' , Department of Radiological Sciences, Oncology and Pathology, Rome (Italy); Vogl, Thomas J.; Wichmann, Julian L. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Nikolaou, Konstantin [Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Todoran, Thomas M. [Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States)

    2016-12-15

    To evaluate the impact of noise-optimized virtual monochromatic imaging (VMI+) on stent visualization and accuracy for in-stent re-stenosis at lower extremity dual-energy CT angiography (DE-CTA). We evaluated third-generation dual-source DE-CTA studies in 31 patients with prior stent placement. Images were reconstructed with linear blending (F{sub 0}.5) and VMI+ at 40-150 keV. In-stent luminal diameter was measured and contrast-to-noise ratio (CNR) calculated. Diagnostic confidence was determined using a five-point scale. In 21 patients with invasive catheter angiography, accuracy for significant re-stenosis (≥50 %) was assessed at F{sub 0}.5 and 80 keV-VMI+ chosen as the optimal energy level based on image-quality analysis. At CTA, 45 stents were present. DSA was available for 28 stents whereas 12 stents showed significant re-stenosis. CNR was significantly higher with ≤80 keV-VMI+ (17.9 ± 6.4-33.7 ± 12.3) compared to F{sub 0}.5 (16.9 ± 4.8; all p < 0.0463); luminal stent diameters were increased at ≥70 keV (5.41 ± 1.8-5.92 ± 1.7 vs. 5.27 ± 1.8, all p < 0.001) and diagnostic confidence was highest at 70-80 keV-VMI+ (4.90 ± 0.48-4.88 ± 0.63 vs. 4.60 ± 0.66, p = 0.001, 0.0042). Sensitivity, negative predictive value and accuracy for re-stenosis were higher with 80 keV-VMI+ (100, 100, 96.4 %) than F{sub 0}.5 (90.9, 94.1, 89.3 %). 80 keV-VMI+ improves image quality, diagnostic confidence and accuracy for stent evaluation at lower extremity DE-CTA. (orig.)

  12. Microbial Diversity and Its Relationship to Physicochemical Characteristics of the Water in Two Extreme Acidic Pit Lakes from the Iberian Pyrite Belt (SW Spain.

    Directory of Open Access Journals (Sweden)

    Esther Santofimia

    Full Text Available The Iberian Pyrite Belt (IPB hosts one of the world's largest accumulations of acidic mine wastes and pit lakes. The mineralogical and textural characteristics of the IPB ores have favored the oxidation and dissolution of metallic sulfides, mainly pyrite, and the subsequent formation of acidic mining drainages. This work reports the physical properties, hydrogeochemical characteristics, and microbial diversity of two pit lakes located in the IPB. Both pit lakes are acidic and showed high concentrations of sulfate and dissolved metals. Concentrations of sulfate and heavy metals were higher in the Nuestra Señora del Carmen lake (NSC by one order of magnitude than in the Concepción (CN lake. The hydrochemical characteristics of NSC were typical of acid mine waters and can be compared with other acidic environments. When compared to other IPB acidic pit lakes, the superficial water of CN is more diluted than that of any of the others due, probably, to the strong influence of runoff water. Both pit lakes showed chemical and thermal stratification with well defined chemoclines. One particular characteristic of NSC is that it has developed a chemocline very close to the surface (2 m depth. Microbial community composition of the water column was analyzed by 16S and 18S rRNA gene cloning and sequencing. The microorganisms detected in NSC were characteristic of acid mine drainage (AMD, including iron oxidizing bacteria (Leptospirillum, Acidithiobacillus ferrooxidans and facultative iron reducing bacteria and archaea (Acidithiobacillus ferrooxidans, Acidiphilium, Actinobacteria, Acidimicrobiales, Ferroplasma detected in the bottom layer. Diversity in CN was higher than in NSC. Microorganisms known from AMD systems (Acidiphilium, Acidobacteria and Ferrovum and microorganisms never reported from AMD systems were identified. Taking into consideration the hydrochemical characteristics of these pit lakes and the spatial distribution of the identified

  13. Nitrogen removal from urban stormwater runoff through layered bioretention columns.

    Science.gov (United States)

    Hsieh, Chi-hsu; Davis, Allen P; Needelman, Brian A

    2007-11-01

    Bioretention is a low-impact technology used for the treatment of stormwater runoff in developed areas. The fates of mineral nitrogen compounds in two bioretention columns (RP1 and RP2) with different media-layering characteristics were investigated under multiple loadings of simulated urban runoff. The immediate capture of nitrogen was evaluated, with nitrogen transformation reactions that occurred during the drying periods between rainfall events. A greater proportion of ammonium was removed from runoff in RP2 (68 +/- 16%), which had a high permeability layer over a lower permeability layer, than in RP1 (12 +/- 6%), which had the inverse configuration. Both column systems demonstrated nitrate export (9 +/- 32% and 54 +/- 22% greater than input for RP1 and RP2, respectively), attributed to washout of nitrate resulting from nitrification processes between runoff loading events. Bioretention media with a less permeable bottom soil layer could form an anoxic/anaerobic zone for promoting nitrification/denitrification processes.

  14. A Review of Adsorbents Used for Storm Water Runoff Cleaning

    Directory of Open Access Journals (Sweden)

    Andrius Agintas

    2011-04-01

    Full Text Available Heavy metals, petroleum products, sediments and other pollutants get in the environment with insufficiently cleaned storm water runoff. Contaminated storm water runoff is one of the most significant sources for pollution in rivers, lakes and estuaries. Storm water runoff must be treated using not only simple methods but also using adsorption processes. Adsorbents can be natural organic, natural nonorganic and synthetic. Main adsorption characteristic, way of utilization and storm water runoff inflow rate, quantity and pollution need to be investigated when trying to use adsorbents in reasonably way. It is very important to treat storm water properly during the primary mechanical treatment otherwise adsorbents will act as mechanical filters.Article in Lithuanian

  15. [Monitoring and analysis on evolution process of rainfall runoff water quality in urban area].

    Science.gov (United States)

    Dong, Wen; Li, Huai-En; Li, Jia-Ke

    2013-02-01

    In order to find the water quality evolution law and pollution characteristics of the rainfall runoff from undisturbed to the neighborhood exit, 6 times evolution process of rainfall runoff water quality were monitored and analyzed from July to October in 2011, and contrasted the clarification efficiency of the grassland to the roof runoff rudimentarily at the same time. The research showed: 1. the results of the comparison from "undisturbed, rainfall-roof, rainfall runoff-road, rainfall-runoff the neighborhood exit runoff " showed that the water quality of the undisturbed rain was better than that from the roof and the neighborhood exist, but the road rainfall runoff water quality was the worst; 2. the average concentrations of the parameters such as COD, ammonia nitrogen and total nitrogen all exceeded the Fifth Class of the Surface Water Quality Standard except for the soluble total phosphorus from undisturbed rainfall to the neighborhood exit; 3. the runoff water quality of the short early fine days was better than that of long early fine days, and the last runoff water quality was better than that of the initial runoff in the same rainfall process; 4. the concentration reduction of the grassland was notable, and the reduction rate of the grassland which is 1.0 meter wide of the roof runoff pollutants such as COD and nitrogen reached 30%.

  16. Multifractal modelling of runoffs of karstic springs

    Science.gov (United States)

    Márkus, L.

    2003-04-01

    A new multifractal stochastic process, Terdik and Iglói call the Limit of the Integrated Superposition of Diffusion processes with Linear differential Generator (LISDLG) , has been defined for modelling network traffic multifractality. The process is stationary, and exhibits long range dependency or long memory. Its characteristic property is that its bispectrum is real. It serves as the basis of distinction e.g. from the superposition of Levy-processes driven Ornstein-Uhlenbeck processes. Its further appealing property is that its finite dimensional distribution stems from multivariate Gamma, therefore it is inherently positive and skewed (and hence non-Gaussian). All together, this makes it a very promising candidate for modelling e.g. runoff data of springs or river flows. Quite recently Labat et al. (2002, J. of Hydrology, Vol 256, pp.176-195) pointed out multifractal properties of the runoff time series of French karstic springs. We show that runoff data of karstic springs in north-east Hungary possesses multifractal and cumulant-multifractal property as well as long range dependency and fit the above described LISDLG process, to model the phenomenon. Acknowledgement: This research was supported by the Nat. Sci. Research Fund OTKA, grant No.: T 032725.

  17. Distal run-off vessel of descending branch of lateral femoral circumflex artery used for reconstruction of extremity defects with free anterolateral thigh flap%旋股外动脉降支远端血管在股前外侧游离皮瓣修复四肢创面中的应用

    Institute of Scientific and Technical Information of China (English)

    何晓清; 朱跃良; 徐永清; 梅良斌; 王毅; 范新宇; 董凯旋

    2015-01-01

    目的 探讨旋股外动脉降支远端血管在股前外侧游离皮瓣修复四肢创面中的应用价值.方法 回顾性分析2009年3月至2013年6月采用带旋股外动脉降支远端血管的股前外侧游离皮瓣修复的14例四肢组织缺损患者资料,男13例,女1例;平均年龄为34.6岁(8~ 57岁).组织缺损部位:足踝部8例,小腿部3例,手部3例.创面缺损面积为5.5cm×4.5cm~25.0cm×14.0 cm.降支远端血管以Flow-through皮瓣方式同时完成血管重建和创面覆盖4例,以Flow-through皮瓣方式保留受区血管连续性6例,以重组嵌合皮瓣方式串联第2足趾同时完成创面覆盖与食指再造1例,以串联横支穿支皮瓣完成足背大创面修复1例,术后血管危象探查中降支远端血管以备用血管发挥作用2例. 结果 14例患者降支远端血管的分离时间为3~7 min,平均4.6 min.降支远端血管平均长度为3.8 cm(1.5 ~6.0 cm).所有患者均未因降支远端血管的切取而出现相关并发症.14例患者术后获2~18个月(平均6.4个月)随访.所有患者皮瓣均完全成活,随访过程中无感染、坏死发生,质地、色泽均良好.8例足踝部缺损及3例小腿部缺损患者均恢复行走功能,足远端血供良好.3例手部缺损患者功能恢复良好. 结论 在股前外侧游离皮瓣修复四肢创面中旋股外动脉降支远端血管分离容易,切取后对供区无额外损伤,且可以根据不同手术目的保留适当长度,以Flow-through皮瓣、重组嵌合皮瓣及备用血管等方式发挥重要作用.%Objective To explore the value of the distal run-off vessel of the descending branch of the lateral circumflex femoral artery in reconstruction of extremity defects with free anterolateral thigh flap.Methods From March 2009 to June 2013,14 patients with extremity defects were repaired with free anterolateral thigh flap that carried the distal run-off vessel of the descending branch of the lateral circumflex femoral artery

  18. Analysis on Runoff Variation Characteristics of Yellow River Source Region from 1956 to 2012%1956要2012年黄河源区径流变化特征分析

    Institute of Scientific and Technical Information of China (English)

    苏中海; 陈伟忠

    2016-01-01

    Based on the source region of the Yellow River as research area,using concentration,concentrated period,the linear trend estimation,Mann-Kendall mutation testing,runoff during the year,interannual and interdecadal trend changes,and sudden change detection were studied. Results showed that during 1956-2012,the runoff increased slightly in upstream of source region of Yellow River,and decreased slightly in downstream,and interannual variability of upstream was drastically compared with downstream. Runoff concentration was mainly concentrated in 40%~60%,and concentration of runoff in upstream was higher than that in downstream. Concentrated period of runoff was mainly distributed from late July to late August,and this trend became much earlier. Since the 21 Century,runoff was abundant in upstream of source region of Yellow River,and low in downstream. Annual runoff sudden change at Jimai Station occurred in 1988 and 2008,and at Maqu Station and Tangnaihai Station,annual runoff sudden changes all occurred in 1991.%以黄河源为研究区,采用集中度、集中期、线性倾向估计、Mann-Kendall突变检验等方法,研究了黄河源区径流的年内、年际、年代际趋势性变化,突变点检测。结果表明:黄河源区上游1956-2012年径流量总体呈弱增加趋势,下游呈弱减少趋势,上游径流量年际变化较下游剧烈。黄河源径流集中度主要集中在40%~60%,上游集中度高于下游。集中期主要分布在7月下旬到8月下旬且有提前趋势。21世纪以来,黄河源径流上游偏丰,下游偏枯。吉迈站年径流量突变点发生在1988年、2008年。玛曲站和唐乃亥站年径流量突变均发生在1991年。

  19. Stormwater Runoff: What it is and Why it is Important in Johnson County, Kansas

    Science.gov (United States)

    Rasmussen, Teresa J.; Schmidt, Heather C.

    2009-01-01

    Stormwater runoff is a leading contributor to pollution in streams, rivers, and lakes in Johnson County, Kansas, and nationwide. Because stormwater runoff contains pollutants from many different sources, decreasing pollution from stormwater runoff is a challenging task. It requires cooperation from residents, businesses, and municipalities. An important step in protecting streams from stormwater pollution is understanding watershed processes, stormwater characteristics, and their combined effects on streams and water quality.

  20. Multifractal Analysis of the Small Time-Scale Boundary-Layer Characteristics of the Wind: the Anisotropy and Extremes

    Science.gov (United States)

    Fitton, G. F.; Tchiguirinskaia, I.; Schertzer, D. J.; Lovejoy, S.

    2012-12-01

    Under various physical conditions (mean temperature and velocity gradients, stratification and rotation) atmospheric turbulent flows remain intrinsically anisotropic. The immediate vicinity of physical boundaries rises to a greater complexity of the anisotropy effects. In this paper we address the issue of the scaling anisotropy of the wind velocity fields within the atmospheric boundary layer (ABL). Under the universal multifractal (UM) framework we compare the small time-scale (0.1 to 1,000 seconds) boundary-layer characteristics of the wind for two different case studies. The first case study consisted of a single mast located within a wind farm in Corsica, France. Three sonic anemometers were installed on the mast at 22, 23 and 43m, measuring three-dimensional wind velocity data at 10Hz. Wakes, complex terrain and buoyancy forces influenced the measurements. The second case study (GROWIAN experiment in Germany) consisted of an array of propeller anemometers measuring wind speed inflow data at 2.5Hz over flat terrain. The propeller anemometers were positioned vertically at 10, 50, 75, 100, 125 and 150m with four horizontal measurements taken at 75, 100 and 125m. The spatial distribution allowed us to calculate the horizontal and vertical shear structure functions of the horizontal wind. Both case studies are within a kilometre from the sea. For the first case study (10Hz measurements in a wind farm test site) the high temporal resolution of the data meant we observed Kolmogorov scaling from 0.2 seconds (with intermittency correction) right up to 1,000 seconds at which point a scaling break occurred. After the break we observed a scaling power law of approximately 2, which is in agreement with Bolgiano-Obukhov scaling theory with intermittency correction. However, for the second case study (2.5Hz on flat terrain) we only observed Kolmogorov scaling from 6.4 seconds (also with intermittency correction). The spectra of horizontal velocity components remain

  1. The effect of leaf litter cover on surface runoff and soil erosion in Northern China.

    Directory of Open Access Journals (Sweden)

    Xiang Li

    Full Text Available The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter, four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (p<0.05. Average runoff yield was 29.5% and 31.3% less than bare-soil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, p<0.05, and the efficiency in runoff reduction by litter decreased considerably. Runoff yield and the runoff coefficient increased dramatically by 72.9 and 5.4 times, respectively. The period of time before runoff appeared decreased approximately 96.7% when rainfall intensity increased from 5.7 to 75.6 mm h-1. Broadleaf and needle leaf litter showed similarly relevant effects on runoff and soil erosion control, since no significant differences (p≤0.05 were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (p<0.05 with sediment yield. These results suggest that the protective role of leaf litter in runoff and erosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes.

  2. Analyzing runoff processes through conceptual hydrological modelling in the Upper Blue Nile basin, Ethiopia

    Directory of Open Access Journals (Sweden)

    M. Dessie

    2014-05-01

    Full Text Available Understanding runoff processes in a basin is of paramount importance for the effective planning and management of water resources, in particular in data scarce regions of the Upper Blue Nile. Hydrological models representing the underlying hydrological processes can predict river discharges from ungauged catchments and allow for an understanding of the rainfall–runoff processes in those catchments. In this paper, such a conceptual process-based hydrological model is developed and applied to the upper Gumara and Gilgel Abay catchments (both located within the Upper Blue Nile basin, the Lake Tana sub-basin to study the runoff mechanisms and rainfall–runoff processes in the basin. Topography is considered as a proxy for the variability of most of the catchment characteristics. We divided the catchments into different runoff production areas using topographic criteria. Impermeable surfaces (rock outcrops and hard soil pans, common in the Upper Blue Nile basin were considered separately in the conceptual model. Based on model results, it can be inferred that about 65% of the runoff appears in the form of interflow in the Gumara study catchment, and baseflow constitutes the larger proportion of runoff (44–48% in the Gilgel Abay catchment. Direct runoff represents a smaller fraction of the runoff in both catchments (18–19% for the Gumara, and 20% for the Gilgel Abay and most of this direct runoff is generated through infiltration excess runoff mechanism from the impermeable rocks or hard soil pans. The study reveals that the hillslopes are recharge areas (sources of interflow and deep percolation and direct runoff as saturated excess flow prevails from the flat slope areas. Overall, the model study suggests that identifying the catchments into different runoff production areas based on topography and including the impermeable rocky areas separately in the modeling process mimics well the rainfall–runoff process in the Upper Blue Nile basin

  3. Analysis of change characteristics and variability of runoff in Beijiang river basin under influence of human activity%人类活动影响下的北江流域径流变化特征及其变异性分析

    Institute of Scientific and Technical Information of China (English)

    李艳; 张鹏飞

    2014-01-01

    Due to the impact of environment change and especial human activities , the hydrology and wa-ter resources systems appear new features .Understanding the variation rule of hydrological characteristics has important meaning to maintain sustainable development of human society .Using the analysis methods of trend,jumping and correlation , the thesis studied the variation characteristics of runoff in BeiJiang Riv-er basin based on the runoff data of 53 years in ShiJiao station from 1956 to 2008 .The results show that the inter-annual variation is obvious and the seasonal distribution is non-uniform.Runoff has no signifi-cant ascending trend and occured one jump change in 1973 .From the analysis of precipitation , evapora-tion and runoff coefficient ,the runoff varied at 1973 .The effect of human activity on runoff evolution was analyzed based on rainfall-runoff relationship .The urbanization and soil erosion result in runoff variation in BeiJiang River basin .In conclusion , the variability of runoff in BeiJiang River basin has taken place under the influence of human activity .%由于受环境变化特别是人类活动的影响,水文水资源系统出现了新的特征。认识水文特征变异规律,对维持人类社会的永续发展具有重要意义。本文以北江流域主要控制性水文站石角站53年(1956-2008)径流序列为基础,运用趋势分析、跳跃分析、相关分析等方法,研究了北江流域径流变化的基本特征和变异规律。结果表明:径流年内分配不均,年际变化大,年径流量序列呈不显著上升趋势,1973年发生了一次径流增量跃变。从对降雨、蒸发、径流系数的分析看,径流在1973年发生了变异,利用降雨-径流关系,分析了人类活动对径流演变的作用,发现城市化发展和水土流失加剧等导致了北江流域径流发生变异。可见,在人类活动的影响下,北江流域径流发生了变异。

  4. A Comparative Analysis of Primary and Extreme Characteristics of Dry or Wet Status between Asia and North America

    Institute of Scientific and Technical Information of China (English)

    HUA Lijuan; MA Zhuguo; ZHONG Linhao

    2011-01-01

    In this study, the Palmer Drought Severity Index (PDSI) was used to analyze the average and extreme dry/wet states of Asia and North America from 1953 to 2003. The results indicate that the two continents underwent drying trends during this period. Compared with North America, Asia showed more severe drought trends. However, more significant and regular seasonal variation for drought was found in North America. The driest regions in Asia were located in the northern region of China, Mongolia, and eastern mid-Siberian plateau. Most regions in central North America were relatively wetter than other regions.The northern and southwestern regions of North America, as well as the Atlantic and Pacific coastal areas,experienced the most drought during this period. A sharp increase of the drought area and the number of extreme drought events took place from 1997 to 2003 in both Asia and North America. Severe drought events were more likely to occur during the summer on both continents. Asia had the most extreme drought events during July, but North America reached its highest drought frequency from June to September. In Asia, a persistent increasing trend of extreme drought emerged throughout the studied period. However,a more complex evolution of drought emerged in North America: a decreasing trend appeared before the mid-1960s and an increasing trend appeared after the late 1970s. A relatively steady dry/wet status was observed between the mid-1960s and the late 1970s. The role of exceptional, extreme drought events with respect to the La Nifia event was considered during 1997-2003.

  5. River Channel Expansion Reveals Ice Sheet Runoff Variations

    Science.gov (United States)

    Overeem, I.; Hudson, B. D.; Welty, E.; LeWinter, A.; Mikkelsen, A. B.

    2013-12-01

    The Greenland Ice Sheet has been rapidly melting over the last decades. To quantify its contribution to global sea-level rise, we urgently need to understand flux of meltwater into proglacial rivers. Direct measurements of river runoff at the Greenlandic coast are sparse due to the dynamic braided channels with unstable banks, which makes in-situ discharge monitoring challenging. Here, we explore the use of ';inundation-discharge' relationships through analysis of both time-lapse camera imagery and MODIS remote-sensing reflectance data to provide us with a proxy record of river discharge for proglacial systems. We utilize MODIS band6 (mid IR 1628 - 1652 nm). Light in this band is strongly absorbed by water, and reflectance is not sensitive to sediment suspended in the water, making it an appropriate proxy for river braidplain inundation. Our focus is on two Greenlandic river systems; the Watson River near Kangerlussuaq and the Naujat Kuat River near Nuuk, to track band6 reflectance characteristics over all cloud-free days for the summers of 2000-2012. For validation, a ground-based inundation record is assembled from time-lapse imagery overlooking the Watson River for 2012. Exponential inundation-discharge relationships were established using our in-situ discharge records for the Watson River near Kangerlussuaq (2007-2012, R2=0.55) and the Naujat Kuat River near Nuuk (2011-2012, R2 = 0.42). Using these relationships to predict total annual river discharge proves reasonably accurate for most years of the observational record (varying between 96-86%). Interestingly, the extreme melt year of 2012 was not reliably predicted using the established relationship. We compared these predictions against an inundation record from the in-situ time-lapse camera and found that a ground-based observations track extreme discharge events more reliably (R2 = 0.60). This methodology allows us to extend existing river records back beyond the 5 or 2 years of in-situ observations

  6. Identification of Extreme Events Under Climate Change Conditions Over Europe and The Northwest-atlantic Region: Spatial Patterns and Time Series Characteristics

    Science.gov (United States)

    Leckebusch, G.; Ulbrich, U.; Speth, P.

    In the context of climate change and the resulting possible impacts on socio-economic conditions for human activities it seems that due to a changed occurrence of extreme events more severe consequences have to be expected than from changes in the mean climate. These extreme events like floods, excessive heats and droughts or windstorms possess impacts on human social and economic life in different categories such as forestry, agriculture, energy use, tourism and the reinsurance business. Reinsurances are affected by nearly 70% of all insured damages over Europe in the case of wind- storms. Especially the December 1999 French windstorms caused damages about 10 billion. A new EU-founded project (MICE = Modelling the Impact of Climate Ex- tremes) will focus on these impacts caused by changed occurrences of extreme events over Europe. Based upon the output of general circulation models as well as regional climate models, investigations are carried out with regard to time series characteristics as well as the spatial patterns of extremes under climate changed conditions. After the definition of specific thresholds for climate extremes, in this talk we will focus on the results of the analysis for the different data sets (HadCM3 and CGCMII GCM's and RCM's, re-analyses, observations) with regard to windstorm events. At first the results of model outputs are validated against re-analyses and observations. Especially a comparison of the stormtrack (2.5 to 8 day bandpass filtered 500 hPa geopotential height), cyclone track, cyclone frequency and intensity is presented. Highly relevant to damages is the extreme wind near the ground level, so the 10 m wind speed will be investigated additionally. of special interest to possible impacts is the changed spatial occurrence of windspeed maxima under 2xCO2-induced climate change.

  7. Characterization of surface runoff from a subtropics urban catchment

    Institute of Scientific and Technical Information of China (English)

    HUANG Jin-liang; DU Peng-fei; AO Chi-tan; LEI Mui-heong; ZHAO Dong-quan; HO Man-him; WANG Zhi-shi

    2007-01-01

    Characteristics of surface runoff from a 0.14-km2 urban catchment with separated sewer in Macau was investigated. Water quality measurements of surface runoff were carried out on five rainfall events during the period of August to November, 2005. Water quality parameters such as pH, turbidity, TSS, COD, TN, Zn, Pb, and Cu were analyzed. The results show that TN and COD are the major pollutants from surface runoff with mean concentration of 8.5 and 201.4 mg/L, both over 4-fold higher compared to the Class V surface water quality standard developed by China SEPA. Event mean concentration (EMC) for major pollutants showed considerable variations between rainfall events. The largest rainfall event with the longest length of antecedent dry weather period (ADWP) produced the highest EMC of TN, TSS and COD. From the pollutographs analysis, the peak concentration of TN precedes the peak runoff flow rate for all three rainfall events. The tendency of the concentration of TSS, turbidity and COD changing with runoff flow varies between rainfall events. The relationship between TSS and other parameters were analyzed to evaluate the efficiency of the physical treatment process to control the surface runoff in the urban catchment. Based on the correlation of parameters with TSS, high treatment efficiency of TSS, TN and COD was expected. The most significant event in term of first flush is the one with the strongest rainfall intensity and longest length of ADWP. TN always showed first flush phenomenon in all three rainfall events, which suggested that the surface runoff in the early stage of surface runoff should be dealt with for controlling TN losses during rainfall events.

  8. How extreme are extremes?

    Science.gov (United States)

    Cucchi, Marco; Petitta, Marcello; Calmanti, Sandro

    2016-04-01

    High temperatures have an impact on the energy balance of any living organism and on the operational capabilities of critical infrastructures. Heat-wave indicators have been mainly developed with the aim of capturing the potential impacts on specific sectors (agriculture, health, wildfires, transport, power generation and distribution). However, the ability to capture the occurrence of extreme temperature events is an essential property of a multi-hazard extreme climate indicator. Aim of this study is to develop a standardized heat-wave indicator, that can be combined with other indices in order to describe multiple hazards in a single indicator. The proposed approach can be used in order to have a quantified indicator of the strenght of a certain extreme. As a matter of fact, extremes are usually distributed in exponential or exponential-exponential functions and it is difficult to quickly asses how strong was an extreme events considering only its magnitude. The proposed approach simplify the quantitative and qualitative communication of extreme magnitude

  9. The geomorphic structure of the runoff peak

    Directory of Open Access Journals (Sweden)

    R. Rigon

    2011-06-01

    Full Text Available This paper develops a theoretical framework to investigate the core dependence of peak flows on the geomorphic properties of river basins. Based on the theory of transport by travel times, and simple hydrodynamic characterization of floods, this new framework invokes the linearity and invariance of the hydrologic response to provide analytical and semi-analytical expressions for peak flow, time to peak, and area contributing to the peak runoff. These results are obtained for the case of constant-intensity hyetograph using the Intensity-Duration-Frequency (IDF curves to estimate extreme flow values as a function of the rainfall return period. Results show that, with constant-intensity hyetographs, the time-to-peak is greater than rainfall duration and usually shorter than the basin concentration time. Moreover, the critical storm duration is shown to be independent of rainfall return period as well as the area contributing to the flow peak. The same results are found when the effects of hydrodynamic dispersion are accounted for. Further, it is shown that, when the effects of hydrodynamic dispersion are negligible, the basin area contributing to the peak discharge does not depend on the channel velocity, but is a geomorphic propriety of the basin. As an example this framework is applied to three watersheds. In particular, the runoff peak, the critical rainfall durations and the time to peak are calculated for all links within a network to assess how they increase with basin area.

  10. Glacier runoff variation and its influence on river runoff during 1961–2006 in the Tarim River Basin, China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Using monthly precipitation and temperature data from national meteorological stations, 90 m resolution DEM and a digital vector map of modern glaciers from the Chinese Glacier Inventory, the glacier mass balance and glacier runoff in the Tarim River Basin (TRB), China, were estimated based on a monthly degree-day model for 1961–2006. The results suggest that the modified monthly degree-day model can simulate the long-term changes in glacier mass balance and glacier runoff, which have been confirmed by short-term observation data and other results in literatures. The characteristics and trends of mass balance and glacier runoff variation were analyzed. It was found that the mean annual glacier mass balance during 1961–2006 was ?139.2 mm per year and the cumulative mass balance over the 46 year period was ?6.4 m in the TRB. The glacier mass balance displayed a clear decreasing trend over the entire TRB during 1961–2006. The average annual glacier runoff in the TRB was 144.16×108 m3 for 1961–2006. The results also show that glacier runoff has increased in the last 46 years, especially since the 1990s with 85.7% of the increased river flow being derived from the increased glacier runoff caused by loss of ice mass. Over the entire TRB, glacier runoff accounts for 41.5% of the total river flow during 1961–2006. The impact of glacier runoff on river flow has increased in the TRB as a result of glacier shrinkage.

  11. Do upslope impervious surfaces impact the run-on/runoff relationship?

    Science.gov (United States)

    Development of watersheds previously managed for agricultural uses for commercial and residential uses results in the replacement of pervious soil surfaces with impervious surfaces. Characteristics of runoff generated on new upslope impervious surfaces may differ from runoff generated on the predeve...

  12. 三峡水库进出库水沙特征及其影响因素分析%Analysis of characteristics of inflow and outflow runoff and sediment in Three Gorges Reservoir and its influential factors

    Institute of Scientific and Technical Information of China (English)

    李海宁; 张燕菁

    2015-01-01

    受气候变化和人类活动的影响,近年来三峡水库进出库水沙条件发生了很大变化。运用Mann-Kendall方法及小波分析方法,研究了三峡水库入出库主要控制站近60 a的实测径流量和输沙量时间序列。结果表明:进出库径流量存在减小趋势但减幅不大,入库输沙量明显减小;主要控制站径流量和输沙量序列均具有明显的多时间尺度特征,径流量和输沙量的第一主周期分别为12~28 a,15~25 a;水土保持、上游修建水利工程、河道采砂等人类活动是输沙量明显减小的主要原因,而其对径流量的影响相对较小。%The runoff and sediment condition of Three Gorges Reservoir has changed significantly in recent years due to the effects of climate changes and human activities. The Mann-Kendall method and wavelet transform method are applied to analyze the annual runoff and sediment discharge data of the main controlling hydrological stations in recent 60 years. The results show that the runoff has a slight decreasing trend, while the sediment decreases sharply. Both runoff and sediment series of the main stations have an obvious properties of multiple time scale, the dominant period of runoff and sediment are 12-year to 28-year and 15-year to 25-year respectively. The impact of runoff changes on the sediment changes is small, while the soil and water conservation measures, construction of hydraulic engineering projects on upstream and the sand mining are the main causes for the sediment reduction.

  13. Clinical Characteristics and Treatment of Extremity Chronic Osteomyelitis in Southern China: A Retrospective Analysis of 394 Consecutive Patients.

    Science.gov (United States)

    Jiang, Nan; Ma, Yun-Fei; Jiang, Yi; Zhao, Xing-Qi; Xie, Guo-Ping; Hu, Yan-Jun; Qin, Cheng-He; Yu, Bin

    2015-10-01

    Although extremity chronic osteomyelitis is common in China, updated data were still limited regarding its characterizations. The present study aimed to review clinical features of extremity chronic osteomyelitis in Southern China.A retrospective analysis was conducted in the patients who had sought medical attention from January 2010 to April 2015 for extremity chronic osteomyelitis in Nanfang Hospital in Southern China. Clinical data were collected and analyzed.A total of 394 patients (307 males and 87 females) were included, giving a gender ratio of 3.53. The median age at first diagnosis was 42 years for all. The most frequent type was traumatic osteomyelitis (262 cases, 66.50%), which was mainly caused by open injury (166 cases, 63.36%) and during a road accident (91 cases, 34.73%). Single-site infection accounted for 81.98% (323 cases), with tibia (126 cases), femur (79 cases), calcaneus (37 cases), and toes (37 cases) as the top sites. The positive rate of intraoperative culture was 70.63% (214/303), 78.97% (169/214) of which was monomicrobial infection. Staphylococcus aureus (59 cases) was the most frequent bacteria for monomicrobial infection, followed by Pseudomonas aeruginosa (29 cases) and Escherichia coli (11 cases). The positive ratios of preoperative serum white blood cell (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) were 21.63%, 64.92%, 53.27%, 42.25%, 72.82%, and 66.67%, respectively. The most frequently used intravenous antibiotic was cephalosporins. The overall cure rate was 77.74%, with a total amputation rate of 16.75%.In this representative Chinese cohort, extremity chronic osteomyelitis was mostly caused by open injury and during a road accident, predominated in males and favored the tibia. S. aureus was the most frequent pathogenic organism. Preoperative elevated levels of serum IL-6, TNF-α, and ESR may be helpful diagnostic

  14. Comparison and analysis characteristics of PHAs pollution for different types of roof runoff%不同屋面雨水径流中PAHs污染特性对比分析

    Institute of Scientific and Technical Information of China (English)

    张科峰; 傅大放; 李贺

    2012-01-01

    对南京市典型沥青屋面、瓦屋面径流中PAHs含量进行了9场降雨事件的现场取样监测,对比分析了2种不同屋面径流中PAHs的EMC值及其各组分的浓度,并对其初期效应及影响因素进行了分析和探讨.结果表明,沥青屋面径流PAHs污染较严重,其平均浓度为4 261.7 ng/L,而瓦屋面径流PAHs平均浓度仅为351.2 ng/L.沥青屋面、瓦屋面径流中PAHs均以4环组分为主,沥青屋面径流中3环组分占较大含量,而瓦屋面径流中5环和6环PAHs浓度仅次于4环PAHs.大多数降雨事件中总PAHs及各组分均存在较显著的初期效应;前期晴天数对PAHs在屋面的累积影响最大,瓦屋面径流PAHs含量受降雨强度影响较大,而沥青屋面径流PAHs含量受降雨量影响较大.%PAHs content in the runoff of two different types of roofs in Nanjing were monitored through the field sampling during 9 rainfall events. The EMCs( event mean concentration) and PAHs (polycyclic aromatic hydrocarbons) composition were analyzed and compared, and then the first flush effect and the influential factors were discussed. The results show that the PAHs pollution in asphalt roof runoff is more serious. The average EMC value of PAHs in asphalt roof and tile roof runoff are 4 261.7,351.2 ng/L, respectively. The main component of PAHs in both roof runoffs is 4-ring PAHs, 3-ring PAHs in asphalt roof runoff also account for a large proportion, while 5-ring and 6-ring PAHs in tile roof runoff are only slightly less than 4-ring PAHs. Total PAHs and relevant components exhibit a pronounced first flush effect in most rainfall events; Correlation analysis suggests that the antecedent dry period is the most significant influential factor for PAHs accumulation on the roof, and the PAHs content in tile roof runoff is mainly influenced by rainfall intensity, while the PAHs content in asphalt roof runoff is mainly influenced by rainfall quantity.

  15. Assessment of Vulnerability to Extreme Flash Floods in Design Storms

    Directory of Open Access Journals (Sweden)

    Hyun Il Choi

    2011-07-01

    Full Text Available There has been an increase in the occurrence of sudden local flooding of great volume and short duration caused by heavy or excessive rainfall intensity over a small area, which presents the greatest potential danger threat to the natural environment, human life, public health and property, etc. Such flash floods have rapid runoff and debris flow that rises quickly with little or no advance warning to prevent flood damage. This study develops a flash flood index through the average of the same scale relative severity factors quantifying characteristics of hydrographs generated from a rainfall-runoff model for the long-term observed rainfall data in a small ungauged study basin, and presents regression equations between rainfall characteristics and the flash flood index. The aim of this study is to develop flash flood index-duration-frequency relation curves by combining the rainfall intensity-duration-frequency relation and the flash flood index from probability rainfall data in order to evaluate vulnerability to extreme flash floods in design storms. This study is an initial effort to quantify the flash flood severity of design storms for both existing and planned flood control facilities to cope with residual flood risks due to extreme flash floods that have ocurred frequently in recent years.

  16. Assessment of vulnerability to extreme flash floods in design storms.

    Science.gov (United States)

    Kim, Eung Seok; Choi, Hyun Il

    2011-07-01

    There has been an increase in the occurrence of sudden local flooding of great volume and short duration caused by heavy or excessive rainfall intensity over a small area, which presents the greatest potential danger threat to the natural environment, human life, public health and property, etc. Such flash floods have rapid runoff and debris flow that rises quickly with little or no advance warning to prevent flood damage. This study develops a flash flood index through the average of the same scale relative severity factors quantifying characteristics of hydrographs generated from a rainfall-runoff model for the long-term observed rainfall data in a small ungauged study basin, and presents regression equations between rainfall characteristics and the flash flood index. The aim of this study is to develop flash flood index-duration-frequency relation curves by combining the rainfall intensity-duration-frequency relation and the flash flood index from probability rainfall data in order to evaluate vulnerability to extreme flash floods in design storms. This study is an initial effort to quantify the flash flood severity of design storms for both existing and planned flood control facilities to cope with residual flood risks due to extreme flash floods that have ocurred frequently in recent years.

  17. Comparison of the Spatio-Temporal Variability of Annual Minimum Daily Extreme Flow Characteristics as a Function of Land Use and Dam Management Mode in Quebec, Canada

    OpenAIRE

    Jean-Michel Sylvain; Ali Assani; Raphaëlle Landry; Jean-François Quessy; Christophe Kinnard

    2015-01-01

    This study presents a comparison of the spatio-temporal variability of characteristics (magnitude, duration and timing) of annual minimum daily extreme flows (AMEF) as a function of land use and the mode of management of dams. Streamflow measured at stations not affected by dams at Joliette, along the L’Assomption River (agricultural watershed, 1340 km2), and at Saint-Michel-des-Saints, on the Matawin River (forested watershed, 1390 km2) on one hand, and downstream from the Rawdon dam (regu...

  18. A protocol for conducting rainfall simulation to study soil runoff.

    Science.gov (United States)

    Kibet, Leonard C; Saporito, Louis S; Allen, Arthur L; May, Eric B; Kleinman, Peter J A; Hashem, Fawzy M; Bryant, Ray B

    2014-04-03

    Rainfall is a driving force for the transport of environmental contaminants from agricultural soils to surficial water bodies via surface runoff. The objective of this study was to characterize the effects of antecedent soil moisture content on the fate and transport of surface applied commercial urea, a common form of nitrogen (N) fertilizer, following a rainfall event that occurs within 24 hr after fertilizer application. Although urea is assumed to be readily hydrolyzed to ammonium and therefore not often available for transport, recent studies suggest that urea can be transported from agricultural soils to coastal waters where it is implicated in harmful algal blooms. A rainfall simulator was used to apply a consistent rate of uniform rainfall across packed soil boxes that had been prewetted to different soil moisture contents. By controlling rainfall and soil physical characteristics, the effects of antecedent soil moisture on urea loss were isolated. Wetter soils exhibited shorter time from rainfall initiation to runoff initiation, greater total volume of runoff, higher urea concentrations in runoff, and greater mass loadings of urea in runoff. These results also demonstrate the importance of controlling for antecedent soil moisture content in studies designed to isolate other variables, such as soil physical or chemical characteristics, slope, soil cover, management, or rainfall characteristics. Because rainfall simulators are designed to deliver raindrops of similar size and velocity as natural rainfall, studies conducted under a standardized protocol can yield valuable data that, in turn, can be used to develop models for predicting the fate and transport of pollutants in runoff.

  19. Mapping mean monthly runoff pattern using EOF analysis

    Directory of Open Access Journals (Sweden)

    E. Sauquet

    2000-01-01

    Full Text Available Runoff generation in a forested catchment (0.18 km2 was simulated using a quasi-three-dimensional rainfall-runoff model. The model was formulated over a finite grid where water movement was assumed to be dominantly vertical in the unsaturated soil zone and horizontal in the saturated soil. The vertical soil moisture distribution at each grid cell was calculated using a conceptual approximation to the one-dimensional Richards equation. The approximation allowed the use of a simple soil surface boundary condition and an efficient solution to the water table elevation over the finite grid. The approximation was coupled with a two-dimensional ground water model to calculate lateral soil water movement between the grid cells and exfiltration over saturated areas, where runoff was produced by the saturation-excess mechanism. Runoff was an input to a channel network, which was modelled as a nonlinear reservoir. The proposed approximation for the vertical soil moisture distribution in unsaturated soil compared well to a numerical solution of the Richards equation during shallow water table conditions, but was less satisfactory during prolonged dry periods. The simulation of daily catchment outflow was successful with the exception of underprediction of extremely high peak flows. The calculated water table depth compared satisfactorily with the measurements. An overall comparison with the earlier results of tracer studies indicated that the modelled contribution of direct rainfall/snowmelt in streamflow was higher than the isotopically traced fraction of event-water in runoff. The seasonal variation in the modelled runoff-contributing areas was similar to that in the event-water-contributing areas from the tracer analysis.

  20. Extreme haze pollution in Beijing during January 2013: chemical characteristics, formation mechanism and role of fog processing

    Science.gov (United States)

    Huang, K.; Zhuang, G.; Wang, Q.; Fu, J. S.; Lin, Y.; Liu, T.; Han, L.; Deng, C.

    2014-03-01

    Severe haze hovered over large areas of China in January 2013 right after the public release of PM2.5 data of major cities in China at the very first time. This historical severe haze emerged over the northern China with monthly average concentrations of PM2.5, SO2, and NO2 exceeding 225, 200, and 80 μg m-3, respectively. Surface aerosol mean concentration of Beijing in January 2013 reached record high (only slightly lower than 2006) compared to historical data from 2003-2012, but with the largest daily fluctuation. Anomalous meteorological conditions in 2013 compared to the mean climatology from 2007-2012 were especially favorable for the formation of haze, such as higher humidity, lower temperature, lower PBL height, lower wind speed, and the high frequency of fog occurrences. The field campaign in Beijing showed an extremely high PM2.5 average concentration of 299.2 ± 79.1μg m-3 with extremely low visibility of 0.92 ± 0.82 km during an episode of high relative humidity with fog events. High AOD (Aerosol Optical Depth) was observed during fog days but with relatively low Angstrom exponent (relative humidity, suggesting the significant impact of aerosol hygroscopicity on the visibility impairment. SO42- increased ∼5 folds while NO3-, NH4+, and C2O42- increased ∼3 folds in the fog days compared to the non-fog days. Aerosol in fog days was much more acidic than that in non-fog days. The in situ aerosol pH ranged from -0.78 to 0.14 in fog days based on the E-AIM model simulation. Bisulfate (HSO42-) accounted for 52% of the total sulfate and free hydrogen ion (H+Aq) accounted for 27% of the total acids in average. Enhanced coal combustion during the winter heating season along with traffic and industrial emissions were recognized to be the major causes for this severe haze. Fog processing was found to be the major pathway of producing extremely high yields of secondary inorganic aerosol and impacting the neutralization process (i.e. aerosol acidity) in this

  1. Event-based stormwater management pond runoff temperature model

    Science.gov (United States)

    Sabouri, F.; Gharabaghi, B.; Sattar, A. M. A.; Thompson, A. M.

    2016-09-01

    Stormwater management wet ponds are generally very shallow and hence can significantly increase (about 5.4 °C on average in this study) runoff temperatures in summer months, which adversely affects receiving urban stream ecosystems. This study uses gene expression programming (GEP) and artificial neural networks (ANN) modeling techniques to advance our knowledge of the key factors governing thermal enrichment effects of stormwater ponds. The models developed in this study build upon and compliment the ANN model developed by Sabouri et al. (2013) that predicts the catchment event mean runoff temperature entering the pond as a function of event climatic and catchment characteristic parameters. The key factors that control pond outlet runoff temperature, include: (1) Upland Catchment Parameters (catchment drainage area and event mean runoff temperature inflow to the pond); (2) Climatic Parameters (rainfall depth, event mean air temperature, and pond initial water temperature); and (3) Pond Design Parameters (pond length-to-width ratio, pond surface area, pond average depth, and pond outlet depth). We used monitoring data for three summers from 2009 to 2011 in four stormwater management ponds, located in the cities of Guelph and Kitchener, Ontario, Canada to develop the models. The prediction uncertainties of the developed ANN and GEP models for the case study sites are around 0.4% and 1.7% of the median value. Sensitivity analysis of the trained models indicates that the thermal enrichment of the pond outlet runoff is inversely proportional to pond length-to-width ratio, pond outlet depth, and directly proportional to event runoff volume, event mean pond inflow runoff temperature, and pond initial water temperature.

  2. Using Support Vector Machines to Characterize Runoff-triggering in Small Watersheds

    Science.gov (United States)

    Misra, D.; Oommen, T.; Radatz, T.; Thompson, A.

    2009-12-01

    Runoff is one of the most complex hydrological phenomena to comprehend due to the tremendous spatial variability of catchment characteristics and precipitation patterns. However, the determination of runoff is critical for flood protection works, effective water storage and release, and protection of agricultural lands. The quantity of runoff depends on parameters such as rainfall intensity, duration, initial soil moisture, land use, and catchment geomorphology or relief. One common approach to estimate runoff is to develop physical models validated with measured data that relate the variables (input - output relationship) in the system. Conversely, this extraction of knowledge from the data requires large datasets, sophisticated modeling techniques as well as human intuition and experience. Additionally, the exact conditions that trigger runoff are difficult to predict because of their dependency on a combination of rainfall intensity, antecedent soil moisture conditions, and physical soil properties. Currently, pattern-learning algorithms based on artificial intelligence have shown promise in developing non-parametric models involving complex processes using few input parameters due to their ability to learn and recognize trends in the data. In this study, we explore the applicability of a sparse pattern-learning algorithm called Support Vector Machines (SVM) for modeling runoff from small watersheds. Results indicate that these methods can be an effective alternative to physical models for identifying runoff generation characteristics. Once identified, characteristics that trigger runoff from catchments, such as rainfall intensity and antecedent soil moisture, may be successfully used for large scale monitoring of watersheds using remote methods such as satellite sensors.

  3. Integrated assessment of climate change impact on surface runoff contamination by pesticides.

    Science.gov (United States)

    Gagnon, Patrick; Sheedy, Claudia; Rousseau, Alain N; Bourgeois, Gaétan; Chouinard, Gérald

    2016-07-01

    Pesticide transport by surface runoff depends on climate, agricultural practices, topography, soil characteristics, crop type, and pest phenology. To accurately assess the impact of climate change, these factors must be accounted for in a single framework by integrating their interaction and uncertainty. This article presents the development and application of a framework to assess the impact of climate change on pesticide transport by surface runoff in southern Québec (Canada) for the 1981-2040 period. The crop enemies investigated were: weeds for corn (Zea mays); and for apple orchard (Malus pumila), 3 insect pests (codling moth [Cydia pomonella], plum curculio [Conotrachelus nenuphar], and apple maggot [Rhagoletis pomonella]), 2 diseases (apple scab [Venturia inaequalis], and fire blight [Erwinia amylovora]). A total of 23 climate simulations, 19 sites, and 11 active ingredients were considered. The relationship between climate and phenology was accounted for by bioclimatic models of the Computer Centre for Agricultural Pest Forecasting (CIPRA) software. Exported loads of pesticides were evaluated at the edge-of-field scale using the Pesticide Root Zone Model (PRZM), simulating both hydrology and chemical transport. A stochastic model was developed to account for PRZM parameter uncertainty. Results of this study indicate that for the 2011-2040 period, application dates would be advanced from 3 to 7 days on average with respect to the 1981-2010 period. However, the impact of climate change on maximum daily rainfall during the application window is not statistically significant, mainly due to the high variability of extreme rainfall events. Hence, for the studied sites and crop enemies considered, climate change impact on pesticide transported in surface runoff is not statistically significant throughout the 2011-2040 period. Integr Environ Assess Managem 2016;12:559-571. © Her Majesty the Queen in Right of Canada 2015; Published 2015 SETAC.

  4. Upper Extremity Injured Workers Stratified by Current Work Status: An Examination of Health Characteristics, Work Limitations and Work Instability

    Directory of Open Access Journals (Sweden)

    H Grant

    2010-06-01

    Full Text Available Background: Upper extremity injured workers are an under-studied population. A descriptive comparison of workers with shoulder, elbow and hand injuries reporting to a Canadian Workplace Safety and Insurance Board (WSIB clinic was undertaken.Objective: To determine if differences existed between injury groups stratified by current work status.Methods: All WSIB claimants reporting to our upper extremity clinic between 2003 and 2008 were approached to participate in this descriptive study. 314 working and 146 non-working WSIB claimants completed the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH; Short Form health survey (SF36; Worker’s Limitations Questionnaire and the Work Instability Scale. Various parametric and non-parametric analyses were used to assess significant differences between groups on demographic, work and health related variables.Results: Hand, followed by the shoulder and elbow were the most common site of injury. Most non-workers listed their current injury as the reason for being off work, and attempted to return to work once since their injury occurrence. Non-workers and a subset of workers at high risk for work loss showed significantly worse mental functioning. Workers identified physical demands as the most frequent injury-related on the job limitation. 60% of current workers were listed as low risk for work loss on the Work Instability Scale.Conclusions: Poorer mental functioning, being female and sustaining a shoulder injury were risk factors for work instability. Our cohort of injured non-workers were unable to return to work due to their current injury, reinforcing the need to advocate for modified duties, shorter hours and a work environment where stress and injury recurrence is reduced. Future studies examining pre-injury depression as a risk factor for prolonged work absences are warranted.

  5. 城市不同功能区径流中PCBs的污染特征及毒性评价%Pollution characteristics and toxicological assessment of PCBs in urban runoff

    Institute of Scientific and Technical Information of China (English)

    韩景超; 毕春娟; 陈振楼; 吕金刚; 王薛平; 周婕成

    2013-01-01

    Concentrations of fourteen polychlorinated biphenyls (PCBs) in runoff samples were investigated, which collected from the different sites in the city, road in residential area, parking lot, drainage outlet, roof and main transport road. The source of PCBs in urban runoff was explored using multivariate statistical analysis. The results showed that the concentrations and detection rate of PCBs varied at different site in a small range. PCBs concentration in roof runoff was higher than that in main transport road,drainage outlet, parking lot and residential area road runoff (mean values were 337.9, 306.3, 240.1, 193.2,172.7ng/L). PCBs in runoff were dominated by penta-CBs, which occupied 31.4%~56.2% of total PCBs. There was no significant correlation between the concentrations of PCBs and SS. Multivariate statistical analyzing demonstrated that high and low chlorinated PCBs in runoff came from different sources. Moreover, values of 2,3,7,8-tetrachlorodibenzodioxin (TCDD, dioxin) equivalents (TEQS) in drainage outlet, residential area road and parking lot runoff were relatively higher (up to 4.4, 4.1, 4.0 ng/L, respectively), which might be related with the higher concentrations of CB126.%选取温州不同城市功能区小区路面、停车场、汇流口、小区屋面以及交通干道作为研究对象,采集径流样品测定了14种多氯联苯(PCBs)的浓度,并对其进行多元统计分析,探讨了其可能的污染来源.结果表明,不同城市功能区径流中PCBs含量和检出率有所差别但变化不大,其中小区屋面要高于交通干道、汇流口、停车场和小区路面(均值分别为337.9,306.3,240.1,193.2,172.7ng/L);径流中以五氯代PCBs为主,占到总量31.4%~56.2%;径流中PCBs跟SS浓度相关性较差;由多元统计分析结果可以看出,高低氯代PCBs污染来源不同;TEQS在汇流口、小区路面、停车场径流中浓度相对较大,分别达到4.4,4.1,4.0ng/L,这跟其径流中CB126含量较高有关.

  6. Characteristics of stable hydrogen and oxygen isotopes of precipitation and runoff in Wudaogou Hydrological Experimental Catchment%五道沟试验场降雨径流中的氢氧稳定同位素特征分析

    Institute of Scientific and Technical Information of China (English)

    谭忠成; 陆宝宏; 汪集旸; 孙营营

    2009-01-01

    在淮北平原区五道沟水文水资源试验场,对降雨径流中的氢氧稳定同位素组成变化的特点及控制平原区河道径流组分划分的一些流域水文因素进行了同位素示踪实验研究.结果表明,实验期间降雨中的δ(~(18)O)(-0.918%~-0.518%)及δ(~2H)(-5.064%~-2.310%)的变幅较大,并随雨强的降低而增大;1,3,6号测井地下水的δ(~(18)O)(或δ(~2H))主要与补给区水源及降雨的δ(~(18)O)(或δ(~2H))有关,其对降雨入渗补给的响应较慢,有明显的滞后效应;IR自记井及S4抽水井由于受抽水灌溉等人类活动的持续影响,δ(~(18)O)(或δ(~2H))明显偏负,表明有来自深部潜水的补给.此外,流域出口断面河水的δ(~(18)O)(或δ(~2H))受平原型流域较强均化作用的影响,其变幅远远小于降雨的δ(~(18)O)(或δ(~2H))变幅,在使用同位素方法划分河道径流组分时,需要考虑降雨到形成河道径流的传输时间.%The characteristics of stable hydrogen and oxygen isotopes of precipitation-runoff components and some factors controlling the partitioning of different water sources of streamflows were investigated for a precipitation event in the Wudaogou Hydrological Experimental Catchment on the Huaibei Plain of China. The analytic results show that the values of the isotopic composition δ(~(18)O)( -0.918% ~ -0.518%) and δ(~2H)( -5.064% ~ -2.310%) of precipitation have large ranges of variation, and increase with the decrease of the precipitation intensity. The values of δ(~(18)O) (or δ(~2H)) forgroundwater from holes 1, 3 and 6 mainly relate to those of δ(~(18)O) (or δ(~2H)) for the groundwater recharge sources and precipitation in the area. They show a slow response to the precipitation infiltration and there exists a time lag effect. Well IR and pumping well S4 have been continuously influenced by human activities such as pumping and irrigation. The values of δ(~(18)O) (or δ(~2H)) are relatively negative, indicating

  7. Forecasting runoff from Pennsylvania landscapes

    Science.gov (United States)

    Identifying sites prone to surface runoff has been a cornerstone of conservation and nutrient management programs, relying upon site assessment tools that support strategic, as opposed to operational, decision making. We sought to develop simple, empirical models to represent two highly different me...

  8. In Situ Raman Spectral Characteristics of Carbon Dioxide in a Deep-Sea Simulator of Extreme Environments Reaching 300 ℃ and 30 MPa.

    Science.gov (United States)

    Li, Lianfu; Du, Zengfeng; Zhang, Xin; Xi, Shichuan; Wang, Bing; Luan, Zhendong; Lian, Chao; Yan, Jun

    2017-01-01

    Deep-sea carbon dioxide (CO2) plays a significant role in the global carbon cycle and directly affects the living environment of marine organisms. In situ Raman detection technology is an effective approach to study the behavior of deep-sea CO2. However, the Raman spectral characteristics of CO2 can be affected by the environment, thus restricting the phase identification and quantitative analysis of CO2. In order to study the Raman spectral characteristics of CO2 in extreme environments (up to 300 ℃ and 30 MPa), which cover most regions of hydrothermal vents and cold seeps around the world, a deep-sea extreme environment simulator was developed. The Raman spectra of CO2 in different phases were obtained with Raman insertion probe (RiP) system, which was also used in in situ Raman detection in the deep sea carried by remotely operated vehicle (ROV) "Faxian". The Raman frequency shifts and bandwidths of gaseous, liquid, solid, and supercritical CO2 and the CO2-H2O system were determined with the simulator. In our experiments (0-300 ℃ and 0-30 MPa), the peak positions of the symmetric stretching modes of gaseous CO2, liquid CO2, and supercritical CO2 shift approximately 0.6 cm(-1) (1387.8-1388.4 cm(-1)), 0.7 cm(-1) (1385.5-1386.2 cm(-1)), and 2.5 cm(-1) (1385.7-1388.2 cm(-1)), and those of the bending modes shift about 1.0 cm(-1) (1284.7-1285.7 cm(-1)), 1.9 cm(-1) (1280.1-1282.0 cm(-1)), and 4.4 cm(-1) (1281.0-1285.4 cm(-1)), respectively. The Raman spectral characteristics of the CO2-H2O system were also studied under the same conditions. The peak positions of dissolved CO2 varied approximately 4.5 cm(-1) (1282.5-1287.0 cm(-1)) and 2.4 cm(-1) (1274.4-1276.8 cm(-1)) for each peak. In comparison with our experiment results, the phases of CO2 in extreme conditions (0-3000 m and 0-300 ℃) can be identified with the Raman spectra collected in situ. This qualitative research on CO2 can also support the further quantitative

  9. Analysis on characteristics of extreme drought and flood events in Huaihe River Basin%淮河流域极端旱涝特征分析

    Institute of Scientific and Technical Information of China (English)

    吴永祥; 姚惠明; 王高旭; 沈国昌; 施睿; 侯保灯

    2011-01-01

    The rainstorm, flood and disaster characteristics and weather process of extreme drought and flood events in Huaihe River Basin were analyzed using historical hydrological and meteorological data and serial information of flood and drought disasters, and the general law was concluded that extreme drought and flood events occurred randomly and alternately in the area. The analysis showed that the frequency of drought and flood events in the Huaihe River Basin during 1470-2010 was propinquant, 46 times and 63 times respectively, and averagely the extreme event occurred every 5 years. It was proposed that the most direct factor causing extreme flood or drought events was excessive increase or decrease of precipitation in Meiyu period, and the root cause was the seasonal anomalies of westerly circulation and subtropical high pressure in medium and high latitude.%利用淮河流域历史水文气象、水旱灾害受灾成灾等系列资料,分析了极端旱涝的暴雨、洪水、洪灾和干旱灾害特征,以及天气成因,揭示了交替随机发生极端旱涝的基本规律.结果表明,1470-2010年淮河流域发生的极端旱涝分别为46和63次,平均5a发生1次极端早涝;梅雨期降水量的极端偏多(或偏少)是形成极端洪涝(或干旱)最直接的因素;中高纬度西风环流和副高的季节性异常是发生极端洪涝(或干旱)的根本原因.

  10. Spot Spraying Reduces Herbicide Concentrations in Runoff.

    Science.gov (United States)

    Melland, Alice R; Silburn, D Mark; McHugh, Allen D; Fillols, Emilie; Rojas-Ponce, Samuel; Baillie, Craig; Lewis, Stephen

    2016-05-25

    Rainfall simulator trials were conducted on sugar cane paddocks across dry-tropical and subtropical Queensland, Australia, to examine the potential for spot spraying to reduce herbicide losses in runoff. Recommended rates of the herbicides glyphosate, 2,4-D, fluoroxypyr, atrazine, and diuron were sprayed onto 0, 20, 40, 50, 70, or 100% of the area of runoff plots. Simulated rainfall was applied 2 days after spraying to induce runoff at one plant cane and three ratoon crop sites. Over 50% of all herbicides were transported in the dissolved phase of runoff, regardless of the herbicide's sediment-water partition coefficient. For most sites and herbicides, runoff herbicide concentrations decreased with decreasing spray coverage and with decreasing herbicide load in the soil and cane residues. Importantly, sites with higher infiltration prior to runoff and lower total runoff had lower runoff herbicide concentrations.

  11. Evaluation of Rainfall-Runoff Models for Mediterranean Subcatchments

    Science.gov (United States)

    Cilek, A.; Berberoglu, S.; Donmez, C.

    2016-06-01

    The development and the application of rainfall-runoff models have been a corner-stone of hydrological research for many decades. The amount of rainfall and its intensity and variability control the generation of runoff and the erosional processes operating at different scales. These interactions can be greatly variable in Mediterranean catchments with marked hydrological fluctuations. The aim of the study was to evaluate the performance of rainfall-runoff model, for rainfall-runoff simulation in a Mediterranean subcatchment. The Pan-European Soil Erosion Risk Assessment (PESERA), a simplified hydrological process-based approach, was used in this study to combine hydrological surface runoff factors. In total 128 input layers derived from data set includes; climate, topography, land use, crop type, planting date, and soil characteristics, are required to run the model. Initial ground cover was estimated from the Landsat ETM data provided by ESA. This hydrological model was evaluated in terms of their performance in Goksu River Watershed, Turkey. It is located at the Central Eastern Mediterranean Basin of Turkey. The area is approximately 2000 km2. The landscape is dominated by bare ground, agricultural and forests. The average annual rainfall is 636.4mm. This study has a significant importance to evaluate different model performances in a complex Mediterranean basin. The results provided comprehensive insight including advantages and limitations of modelling approaches in the Mediterranean environment.

  12. EVALUATION OF RAINFALL-RUNOFF MODELS FOR MEDITERRANEAN SUBCATCHMENTS

    Directory of Open Access Journals (Sweden)

    A. Cilek

    2016-06-01

    Full Text Available The development and the application of rainfall-runoff models have been a corner-stone of hydrological research for many decades. The amount of rainfall and its intensity and variability control the generation of runoff and the erosional processes operating at different scales. These interactions can be greatly variable in Mediterranean catchments with marked hydrological fluctuations. The aim of the study was to evaluate the performance of rainfall-runoff model, for rainfall-runoff simulation in a Mediterranean subcatchment. The Pan-European Soil Erosion Risk Assessment (PESERA, a simplified hydrological process-based approach, was used in this study to combine hydrological surface runoff factors. In total 128 input layers derived from data set includes; climate, topography, land use, crop type, planting date, and soil characteristics, are required to run the model. Initial ground cover was estimated from the Landsat ETM data provided by ESA. This hydrological model was evaluated in terms of their performance in Goksu River Watershed, Turkey. It is located at the Central Eastern Mediterranean Basin of Turkey. The area is approximately 2000 km2. The landscape is dominated by bare ground, agricultural and forests. The average annual rainfall is 636.4mm. This study has a significant importance to evaluate different model performances in a complex Mediterranean basin. The results provided comprehensive insight including advantages and limitations of modelling approaches in the Mediterranean environment.

  13. Human impacts on runoff regime of middle and lower Yellow River

    Directory of Open Access Journals (Sweden)

    Yan-fang SANG

    2011-03-01

    Full Text Available In this study, the 54-year (1950 to 2003 monthly runoff series from February, April, August, and November, as well as the annual runoff series, measured at both Huayuankou and Lijin hydrological stations were chosen as representative data, and the continuous wavelet transform (CWT was applied to analyze the impacts of human activities on the runoff regime of the middle and lower Yellow River. A point of change in 1970 was first determined, and the observed series before 1970 were considered natural runoff while those after 1970 were restored according to linear trends. Then, the CWT was applied to both the observed and restored runoff series to reveal their variations at multi-temporal scales, including the five temporal ranges of 1-4, 6-8, 9-12, 16-22, and 22-30 years, and the trend at the temporal scale of 54 years. These analysis results are compared and discussed in detail. In conclusion, because of the impacts of human activities, there have been significant changes in the runoff regime in the middle and lower Yellow River since 1970. The decaying tendency of annual runoff has become more pronounced, and the inner-annual distribution of runoff has changed, but human activities have had little impact on the periodic characteristics of runoff.

  14. Missing (in-situ) snow cover data hampers climate change and runoff studies in the Greater Himalayas

    Energy Technology Data Exchange (ETDEWEB)

    Rohrer, Mario [Meteodat GmbH, Technoparkstrasse 1, CH-8005 Zurich (Switzerland); Salzmann, Nadine [Department of Geosciences, Geography, University of Fribourg, Chemin du Musée 4, CH-1700 Fribourg (Switzerland); Stoffel, Markus, E-mail: markus.stoffel@unige.ch [Institute for Environmental Sciences, University of Geneva, Chemin de Drize 7, CH-1227 Carouge, Geneva (Switzerland); Dendrolab.ch, Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, CH-3012 Bern (Switzerland); Kulkarni, Anil V. [Divecha Center for Climate Change, Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012 (India)

    2013-12-01

    The Himalayas are presently holding the largest ice masses outside the polar regions and thus (temporarily) store important freshwater resources. In contrast to the contemplation of glaciers, the role of runoff from snow cover has received comparably little attention in the past, although (i) its contribution is thought to be at least equally or even more important than that of ice melt in many Himalayan catchments and (ii) climate change is expected to have widespread and significant consequences on snowmelt runoff. Here, we show that change assessment of snowmelt runoff and its timing is not as straightforward as often postulated, mainly as larger partial pressure of H{sub 2}O, CO{sub 2}, CH{sub 4}, and other greenhouse gases might increase net long-wave input for snowmelt quite significantly in a future atmosphere. In addition, changes in the short-wave energy balance – such as the pollution of the snow cover through black carbon – or the sensible or latent heat contribution to snowmelt are likely to alter future snowmelt and runoff characteristics as well. For the assessment of snow cover extent and depletion, but also for its monitoring over the extremely large areas of the Himalayas, remote sensing has been used in the past and is likely to become even more important in the future. However, for the calibration and validation of remotely-sensed data, and even more so in light of possible changes in snow-cover energy balance, we strongly call for more in-situ measurements across the Himalayas, in particular for daily data on new snow and snow cover water equivalent, or the respective energy balance components. Moreover, data should be made accessible to the scientific community, so that the latter can more accurately estimate climate change impacts on Himalayan snow cover and possible consequences thereof on runoff. - Highlights: • Remotely sensed snow-cover data need to be validated by in-situ measurements. • More in-situ snow measurement programs are

  15. Rest-frame ultraviolet-to-optical spectral characteristics of extremely metal-poor and metal-free galaxies

    CERN Document Server

    Inoue, Akio K

    2011-01-01

    Finding the first generation of galaxies in the early Universe is the greatest step forward for understanding galaxy formation and evolution. For strategic survey of such galaxies and interpretation of the obtained data, this paper presents an ultraviolet-to-optical spectral model of galaxies with a great care of the nebular emission. In particular, we present a machine-readable table of intensities of 119 nebular emission lines from Ly$\\alpha$ to the rest-frame 1 $\\mu$m as a function of metallicity from zero to the Solar one. Based on the spectral model, we present criteria of broad-band colours and equivalent widths of Ly$\\alpha$, He {\\sc ii} $\\lambda1640$, H$\\alpha$, H$\\beta$, [O {\\sc iii}] $\\lambda5007$ to select extremely metal-poor and metal-free galaxies although these criteria have uncertainty caused by the Lyman continuum escape fraction and the star formation duration. The criteria of broad-band colours will be useful to select candidates for spectroscopic follow-up from drop-out galaxies. We propos...

  16. W(310) cold-field emission characteristics reflecting the vacuum states of an extreme high vacuum electron gun

    Science.gov (United States)

    Cho, Boklae; Shigeru, Kokubo; Oshima, Chuhei

    2013-01-01

    An extremely high vacuum cold-field electron emission (CFE) gun operating at pressures ranging from ˜10-8 Pa to ˜10-10 Pa was constructed. Only the CFE current emitting from W(310) surfaces revealed the existence of a "stable region" with high current angular density just after tip flash heating. In the "stable region," the CFE current was damped very slowly. The presence of non-hydrogen gas eliminated this region from the plot. Improvement of the vacuum prolonged the 90% damping time of the CFE current from ˜10 min to 800 min. The current angular density I' of CFE current was 60 and 250 μA/sr in the "stable region" for total CFE currents of 10 and 50 μA, respectively. These results were about three times larger than I' when measured after the complete damping of the CFE current. The CFE gun generated bright scanning transmission electron microscopy images of a carbon nanotube at 30 kV.

  17. Clouds enhance Greenland ice sheet meltwater runoff

    NARCIS (Netherlands)

    Van Tricht, K.; Lhermitte, S.; Lenaerts, J. T M|info:eu-repo/dai/nl/314850163; Gorodetskaya, I. V.; L'Ecuyer, T. S.; Noël, B.|info:eu-repo/dai/nl/370612345; Van Den Broeke, M. R.|info:eu-repo/dai/nl/073765643; Turner, D. D.; Van Lipzig, N. P M

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative

  18. Clouds enhance Greenland ice sheet meltwater runoff

    NARCIS (Netherlands)

    Van Tricht, K.; Lhermitte, S.; Lenaerts, J. T M|info:eu-repo/dai/nl/314850163; Gorodetskaya, I. V.; L'Ecuyer, T. S.; Noël, B.|info:eu-repo/dai/nl/370612345; Van Den Broeke, M. R.|info:eu-repo/dai/nl/073765643; Turner, D. D.; Van Lipzig, N. P M

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative

  19. Synchronism of runoff response to climate change in Kaidu River Basin in Xinjiang, Northwest China

    Institute of Scientific and Technical Information of China (English)

    Jie Xue; JiaQiang Lei; DongWei Gui; JianPing Zhao; DongLei Mao; Jie Zhou

    2016-01-01

    The runoff in alpine river basins where the runoff is formed in nearby mountainous areas is mainly affected by temperature and precipitation. Based on observed annual mean temperature, annual precipitation, and runoff time-series datasets during 1958–2012 within the Kaidu River Basin, the synchronism of runoff response to climate change was analyzed and iden-tified by applying several classic methods, including standardization methods, Kendall's W test, the sequential version of the Mann-Kendall test, wavelet power spectrum analysis, and the rescaled range (R/S) approach. The concordance of the nonlinear trend variations of the annual mean temperature, annual precipitation, and runoff was tested significantly at the 0.05 level by Kendall's W method. The sequential version of the Mann-Kendall test revealed that abrupt changes in annual runoff were synchronous with those of annual mean temperature. The periodic characteristics of annual runoff were mainly consistent with annual precipitation, having synchronous 3-year significant periods and the same 6-year, 10-year, and 38-year quasi-periodicities. While the periodic characteristics of annual runoff in the Kaidu River Basin tracked well with those of annual precipitation, the abrupt changes in annual runoff were synchronous with the annual mean temperature, which directly drives glacier- and snow-melt processes. R/S analysis indicated that the annual mean temperature, annual precipitation, and runoff will continue to increase and remain synchronously persistent in the future. This work can im-prove the understanding of runoff response to regional climate change to provide a viable reference in the management of water resources in the Kaidu River Basin, a regional sustainable socio-economic development.

  20. Characterizing Runoff and Water Yield from Headwater Catchments in the Southern Sierra Nevada

    Science.gov (United States)

    Safeeq, M.; Hunsaker, C. T.

    2015-12-01

    In a mediterranean climate where much of the annual precipitation falls during winter, the snow-capped Sierra Nevada serves as the primary source of dry season runoff that supports agriculture, industries, urban, and other ecosystems. Increased warming has led to significant reductions in mountain snowpack accumulation and earlier snowmelt throughout the western United States where most of the snow accumulates at temperatures near the freezing point. As a result, declines in dry season runoff magnitude, earlier runoff timing, and altered flood risk have been reported across the region. An important question in this context is, how to best manage forested catchments for water and other ecosystem services? We depict the differences in hydrologic response of ten catchments in the Kings River Experimental Watersheds (KREW) research project using continuous precipitation, snow, and runoff data during 2004-2014. The size of these catchments ranges from 50 to 475 ha, and they span a 600-m elevation range in the rain snow transitional zone. In terms of soil, Shaver and Gerle-Cagwin dominate the lower elevation Providence catchments, and Cagwin soils dominate the higher elevation Bull catchments. The majority of these catchments have southwest aspect, moderate average slope (i.e. annual runoff ranges between 281 to 408 mm in Providence and 436 to 656 mm in Bull catchments despite no significant difference in precipitation among KREW's four meteorological stations. However, high elevation Bull catchments receive significantly more precipitation as snow than the low elevation Providence catchments. The average runoff ratio ranges from 18% to as high as 43% among different catchments, indicating that the catchment evapotranspiration exceeds the catchment runoff. Inter-catchment variability in runoff, runoff ratio, characteristics of runoff ratio-precipitation relationship (i.e. slope and intercept), and precipitation elasticity of runoff can be primarily explained by

  1. Variation Characteristics Analysis of Natural Runoff Series of Huaihe River Basin over Past 50 Years%淮河流域近50年天然径流演变规律分析

    Institute of Scientific and Technical Information of China (English)

    郝婷婷; 钟平安; 魏蓬

    2011-01-01

    Based on the nearly 50 years natural annual runoff series of four intervals in Huaihe River Basin which is the upper reaches of Linyi, the upper reaches of Wangjiaba. Wangjiaba to Bengbu and Bengbu to Zhongdu, annual distributions, inter-annual variation, trends, jumps and periodicities are analyzed by using mathematics statistics, linear trend, residual mass curve, t-test and wavelet analysis. The results show that the intra-year natural runoff distributions have large difference while inter-annual rainy and dry water variation is obvious; annual runoff series of four intervals have not remarkable downtrend; natural runoff series of the upper reaches of Linyi station and Bengbu station to Zhongdu station have jump around 1965 while two other intervals do not have jump phenomenon; the main cycles and minor cycles of four intervals are 10 years and 4 years, 7 years and 4 years, 7 years and 2 years, 7 years and 2 years, respectively.%以淮河流域临沂以上、王家坝以上、王家坝至蚌埠、蚌埠至中渡四个区间近50年的天然径流系列为倒,采用数理统计、线性倾向分析、差积曲线法、t检验法、小波分析等方法分析了多年天然径流量的年内分配与年际变化及趋势性、突变性和周期性等特征.结果表明,淮河流域天然径流年内分配差异大、年际丰枯变化剧烈;四个区间年径流序列存在不显著的下降趋势;临沂以上和蚌埠至中渡区间的天然年径流序列均在1965年发生突变,其他两区间不存在突变年;四个区间的主周期和次周期分别为10年和4年、7年和4年、7年和2年、7年和2年.

  2. Characteristics of a Novel Highly Thermostable and Extremely Thermophilic Alkalitolerant Amylase from Hyperthermophilic Bacillus Strain HUTBS71

    Directory of Open Access Journals (Sweden)

    Hazem Akel

    2009-01-01

    Full Text Available Problem statement: This study reported the purification and characterization of a novel highly thermostable alkaline amylase from a newly isolated Bacillus strain HUTBS71. Approach: The enzyme was purified using ammonium sulfate precipitation, ion exchange and gel filtration chromatography. Results: Maximum amylase activity (72 U mL-1 was obtained at 100°C after 10 min of incubation. The enzyme was purified 24 fold with 12.5% yield and showed a monomer band with a molecular weight of 58.8 kDa by SDS-PAGE. This enzyme exhibited maximum activity at pH and temperature, 7.8 and 100°C, respectively. It performed stability over a broad range of pH and temperature, 5.2-10.0 and 80-115°C, respectively. The half-life of the enzyme at 90 and 100°C was estimated to be 3 h. The activation energy of denaturation of purified enzyme was 2.53 kJ moL-1. The enzyme was activated by 5 mM of CoCl2, MgSO4, MnCl2, ZnSO4 and MnSO4 (relative activity was 133, 126, 133, 106.6 and 103%, respectively. It was strongly inhibited by CuSO4 and CdCl2 but less affected by NaCl, CaCl2, FeCl3, ZnCl2 and EDTA. Conclusion: The present purified amylase therefore could be defined as a highly thermostable, extremely hyperthermophilic and alkalitolerant with new properties make the present enzyme applicable for many starch processing and food industries.

  3. Impacts of Climatic Factors on Runoff Coefficients in Source Regions of the Huanghe River

    Institute of Scientific and Technical Information of China (English)

    CHEN Liqun; LIU Changming; LI Yanping; WANG Guoqiang

    2007-01-01

    Runoff coefficients of the source regions of the Huanghe River in 1956-2000 were analyzed in this paper. In the 1990s runoff of Tangnaihai Hydrologic Station of the Huanghe River experienced a serious decrease, which had attracted considerable attention. Climate changes have important impact on the water resources availability. From the view of water cycling, runoff coefficients are important indexes of water resources in a particular catchment. Kalinin baseflow separation technique was improved based on the characteristics of precipitation and streamflow. After the separation of runoff coefficient (R/P), baseflow coefficient (Br/P) and direct runoff coefficient (Dr/P) were estimated. Statistic analyses were applied to assessing the impact of precipitation and temperature on runoff coefficients (including Dr/P,Br/P and R/P). The results show that in the source regions of the Huanghe River, mean annual baseflow coefficient was higher than mean annual direct runoff coefficient. Annual runoff coefficients were in direct proportion to annual precipitation and in inverse proportion to annual mean temperature. The decrease of runoff coefficients in the 1990s was closely related to the decrease in precipitation and increase in temperature in the same period. Over different sub-basins of the source regions of the Huanghe River, runoff coefficients responded differently to precipitation and temperature. In the area above Jimai Hydrologic Station where annual mean temperature is -3.9 ℃, temperature is the main factor influencing the runoff coefficients. Runoff coefficients were in inverse relation to temperature, and precipitation had nearly no impact on runoff coefficients. In subbasin between Jimai and Maqu Hydrologic Station Dr/P was mainly affected by precipitation while R/P and Br/P were both significantly influenced by precipitation and temperature. In the area between Maqu and Tangnaihai hydrologic stations all the three runoff coefficients increased with the rising

  4. Pollutant Removal from Highway Runoff Using Retention/Detention Units

    Directory of Open Access Journals (Sweden)

    Ashraf El-Shahat Elsayed

    2001-01-01

    Full Text Available Highway runoff contains total suspended solids, hydrocarbons, oil and greases, chloride, and other contaminants that are transported in solution and particulate forms to adjacent floodplains, roadside swales, and retention/detention ponds. Oil and grit chambers represent a type of retention/detention unit used for removing heavy particulates and adsorbed hydrocarbon particulates. Storage/sediment units also represent a type of retention/detention unit used for controlling peak flow and removing suspended solids. The aim of this study is to evaluate the effect of traffic volume and site characteristics on highway runoff quality. The study also aims to evaluate the performance of retention/detention units that collect runoff from the Prague-Brno and Prague-Plzeň highways, Czech Republic. The results of this study indicate no definitive relationship between average daily traffic and concentration of runoff constituents, though the site characteristics have a strong relation to some constituents. The results also show that retention/detention units are effective in treating organic compounds.

  5. Characteristics of nitrogen and phosphorus runoff losses from croplands with different planting patterns in a riverine plain area of Zhejiang Province, East China%水网平原地区不同种植类型农田氮磷流失特征

    Institute of Scientific and Technical Information of China (English)

    章明奎; 王阳; 黄超

    2011-01-01

    采用田间径流小区定位研究方法,在浙江省绍兴县选择27块农田,研究了自然降雨条件下水网平原地区7种种植类型农田N、P的径流流失特征、负荷及影响因素.结果表明:农田径流总P(TP)、水溶态P(DP)和颗粒态P(PP)的年流失量平均分别为4.75、0.74和4.01 kg ·hm-2;PP占TP的比例高于DP.径流总N(TN)、水溶态总N(DTN)、水溶态有机N( DON)、NH4+-N和NO3--N的年流失量平均分别为21.87、17.19、0.61、3.63和12.95kg·hm-2;流失的DTN各组分以NO3--N为主,其次为NH4+-N,DON的比例较低.不同种植类型农田径流TN、DTN、DON和NO3--N的流失量由低至高依次为:休闲地<苗木地<单季晚稻农田<双季稻农田<油菜(或小麦)-单季水稻农田<小麦-早稻-晚稻农田<蔬菜地,而径流TP和PP的流失量依次为:休闲地<苗木地<单季晚稻、双季稻农田<小麦-早稻-晚稻农田<油菜(或小麦)-单季水稻农田<蔬菜地,不同种植类型间的DP流失量差异较小.N、P流失主要发生在作物生产期间,TN和TP的流失比例随作物复种指数的提高而增加.TN、DTN和NO3--N流失量主要与N肥施用量有关,土壤中NO3--N含量对TN和DTN流失量也有明显影响;农田DON的流失除与N肥施用量有关外,还受土壤全N和有机质积累的影响;NH4+-N的流失量主要与土壤NH4+-N水平有关,受N肥施用量的影响不明显;径流TP和PP的流失量受P肥施用量、土壤P积累的共同影响,而DP的流失与施P量关系不大,但与土壤全P和有效P都存在显著相关关系.%By the method of site-specific observation, and selecting 27 field plots with 7 planting patterns in Shaoxing county of Zhejiang Province as test objects, this paper studied the characteristics of nitrogen ( N) and phosphorous (P) runoff losses, loads, and their affecting factors in the croplands with different planting patterns in riverine plain area of the Province under natural rainfall. The

  6. Characterization of extreme years in Central Europe between 2000 and 2016 according to specific vegetation characteristics based on Earth Observatory data

    Science.gov (United States)

    Kern, Anikó; Marjanović, Hrvoje; Barcza, Zoltán

    2017-04-01

    behavior of the various plant functional types MODIS (MCD12) and CORINE (CLC2012) land cover datasets were applied and handled together. Based on the determination of the reliable pixels with different plant types the response of broadleaf forests, coniferous forests, grasslands and croplands were discriminated and investigated. Characteristic time periods were selected based on the remote sensing data to define anomalies, and then the meteorological data were used to define critical time periods within the year that has the strongest effect on the observed anomalies. Similarities/dissimilarities between the behaviors of the different remotely sensed measures are also studied to elucidate the consistency of the indices. The results indicate that the diverse remote sensing indices typically co-vary but reveal strong plant functional type dependency. The study suggest that the selection of extreme years based on annual data is not the best choice, as shorter time periods within the years explain the anomalies to a higher degree than annual data. The results can be used to select anomalous years outside of the satellite era as well. Keywords: Remote sensing, meteorology; extreme years; MODIS, NDVI; EVI; LAI; FPAR; GPP; phenology

  7. Prediction of Basketball Shooting Ability on the Basis of Anthropometric Characteristics, Wrist Range of Motion, and Strength of Upper Extremity in Elite Female Basketball Players

    Directory of Open Access Journals (Sweden)

    Nahid Adibpour

    2016-03-01

    Full Text Available Objective: This study aims to predict basketball shooting ability on the basis of anthropometric characteristics, wrist range of motion, and strength of upper extremity in elite female basketball players. Methods: The sample of the study included 34 female basketball players invited to attend the national team trainings. 15 subjects were playing in center and 19 subjects in guard and forward positions. Measuring tapes and standard method (ISAK were used to measure the length of segments of dominant or shooting upper extremity. Digital dynamometer and goniometer were used to measure muscular strength and the wrist range of motion, respectively. Shooting ability of players was assessed by standard tests of free throw, three pointer and elbow shot. The research data was statistically analyzed using linear regression analysis. Results: Results showed that only forearm length variable is significantly effective on free throw shot. However, according to measures and regression coefficient, this effect was low. Conclusion: When choosing players for the guard and forward positions, coaches can necessarily ignore the stature and length of upper limb issue, and pay more attention to the other factors such as their shooting technique.

  8. First observation of natural circular dichroism spectra in the extreme ultraviolet region using a polarizing undulator-based optical system and its polarization characteristics.

    Science.gov (United States)

    Tanaka, Masahito; Yagi-Watanabe, Kazutoshi; Kaneko, Fusae; Nakagawa, Kazumichi

    2009-07-01

    Natural circular dichroism (CD) spectra in the extreme ultraviolet (EUV) region down to a wavelength of 80 nm have been observed for the first time, using an alanine thin film deposited on sodium salicylate coated glass as a sample. Calibrated EUV-CD spectra of L-alanine exhibited a large negative peak at around 120 nm and a positive CD signal below 90 nm, which were roughly predicted by theoretical calculations. A CD measurement system with an Onuki-type polarizing undulator was used to obtain the EUV-CD spectra. This CD system, the development of which took five years, can be used to observe even weak natural CD spectra. The polarization characteristics of this system were also evaluated in order to calibrate the recorded CD spectra.

  9. Effect of climate change on runoff of Campylobacter and Cryptosporidium from land to surface water.

    Science.gov (United States)

    Sterk, Ankie; Schijven, Jack; de Roda Husman, Ana Maria; de Nijs, Ton

    2016-05-15

    Faeces originating from wildlife, domestic animals or manure-fertilized fields, is considered an important source of zoonotic pathogens to which people may be exposed by, for instance, bathing or drinking-water consumption. An increase in runoff, and associated wash-off of animal faeces from fields, is assumed to contribute to the increase of disease outbreaks during periods of high precipitation. Climate change is expected to increase winter precipitation and extreme precipitation events during summer, but has simultaneously also other effects such as temperature rise and changes in evapotranspiration. The question is to what extent the combination of these effects influence the input of zoonotic pathogens to the surface waters. To quantitatively analyse the impacts of climate change on pathogen runoff, pathogen concentrations reaching surface waters through runoff were calculated by combining an input model for catchment pathogen loads with the Wageningen Lowland Runoff Simulator (WALRUS). Runoff of Cryptosporidium and Campylobacter was evaluated under different climate change scenarios and by applying different scenarios for sources of faecal pollution in the catchments, namely dairy cows and geese and manure fertilization. Model evaluation of these scenarios shows that climate change has little overall impact on runoff of Campylobacter and Cryptosporidium from land to the surface waters. Even though individual processes like runoff fluxes, pathogen release and dilution are affected, either positively or negatively, the net effect on the pathogen concentration in surface waters and consequently also on infection risks through recreation seems limited.

  10. Assessment of runoff contributing catchment areas in rainfall runoff modelling

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Johansen, C.; Schaarup-Jensen, Kjeld

    2006-01-01

    recommended literature values for residential areas. It is proven by comparing rainfall-runoff measurements from four different residential catchments that the literature values of the hydrological reduction factor are over-estimated for this type of catchment. In addition, different catchment descriptions...... are presented in order to investigate how the hydrological reduction factor depends on the level of detail regarding the catchment description. When applying a total survey of the catchment area, including all possible impervious surfaces, a hydrological reduction factor of approximately 0.5 for residential...

  11. Assessment of Runoff Contributing Catchment Areas in Rainfall Runoff Modelling

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Johansen, C.; Schaarup-Jensen, Kjeld

    2005-01-01

    recommended literary values for residential areas. It is proven by comparing rainfall-runoff measurements from four different residential catchments that the literary values of the hydrological reduction factor are over-estimated for this type of catchments. In addition, different catchment descriptions...... are presented in order to investigate how the hydrological reduction factor depends on the level of detail regarding the catchment description. When applying a total survey of the catchment area, including all possible impervious surfaces, a hydrological reduction factor of approximately 0.5 for residential...

  12. Climate Characteristics of Extreme Drought Events in Yunnan%云南极端气候干旱的特征分析

    Institute of Scientific and Technical Information of China (English)

    张万诚; 郑建萌; 任菊章

    2013-01-01

    By using precipitation and temperature data of 124 stations in Yunnan during 1961 -2011, drought strength in Yunnan since 1961 are analyzed based on integrated meteorological drought index and daily precipitation. Extreme droughts could be appropriately chosen with drought process intensity index - 50 in Yunnan and above -100 of regional representative stations. Four extreme drought events in Yunnan, respectively in 1962 -1963, 1968 -1969, 1978 -1979 and 2009 -2010, are chosen as extreme drought year, and analysis on which indicate that the drought from autumn 2009 to early summer 2010 is the most serious one in the historical meteorological recording, and those in 1978 - 1979, 1968 - 1969 and 1962 - 1963 follow. High frequency, long duration and consistent distribution are main characteristics of droughts in Yunnan. Droughts appear in winter, spring and early summer most but autumn droughts happen most in recent years. Due to uneven distribution of precipitation, drought strength different places in Yunnan are different, extreme droughts are less in some areas in the west and southwest for more rainfalls, extreme droughts happen mostly in most places especially in the middle and east of Yunnan. Since 1970, intension and duration of extreme drought aggravated consistently.%应用云南124个站点1961-2011年的旬、日、月降水和气温资料,采用综合气象干旱指数和逐日降水分析云南1961年以来的干旱强度.以云南的干旱过程强度指数为-50、区域代表站的干旱过程用强度指数为-100以上选取极端干旱较为合适,选取干旱强度最大1962/1963、1968/1969、1978/1979和2009/2010年为极端干旱年进行分析表明,在4次极端干旱过程中,强度最强的是2009/2010年出现的秋冬春初夏连旱,是有气象记录以来最强的,其造成的危害及经济损失也最大,其次是1978/1979年、1968/1969年和1962/1963年出现的冬春初夏连旱.云南干旱灾害出现频繁、持续时间长,其

  13. Study on Management and Control of Nonpoint Source Pollution from Urban Surface Runoff

    Institute of Scientific and Technical Information of China (English)

    Chen Keliang; Zhu Xiaodong; Wang Xianghua; Ma Yan

    2007-01-01

    Urbanization is the dominant form of land-use change in terms of impacts on water quality, hydrology, physical properties of watersheds and their nonpoint source (NPS) pollution potential at present. Urbanization has changed the source, process and sink of urban NPS pollution, especially raised the pollution load of urban runoff NPS in receiving water. Urban runoff pollution is a hot spot of research on NPS. This paper analyzed type,source and harm of the NPS pollutants of urban runoff and its influence on the receiving water. Through estimating NPS pollution load of urban runoff and summarizing the law and characteristics of urban runoff NPS systemically, study on management and control of urban runoff NPS pollution was focused on the application of BMPs (best management practices). It is a fresh methodology that management and control on NPS pollution from urban surface runoff was analyzed by methods of landscape ecology,environmental economics and environmental management. The paper provided a scientific reference for mitigating urban water environment pressure and an effective method for management and control of NPS pollution from urban surface runoff..

  14. Chemical characteristics and chemical weathering of surface runoff in typical granitic watersheds of subtropical China%亚热带典型花岗岩小流域径流化学特征与化学风化

    Institute of Scientific and Technical Information of China (English)

    黄来明; 张甘霖; 杨金玲

    2012-01-01

    In order to study the effect of biogeochemical cycling processes on surface runoff and the consumption of CO2 by chemical weathering of granite at small-watershed scale,the surface runoffs in two small watersheds(F-forest,FA-forest/farmland) with different land uses,which located in the typical granitic region of subtropical China,were monitored continuously for three years,and the major ions and dissolved Si were analyzed.The results showed that the dissolved Si,Na+ and HCO-3 were the predominant ions in the chemical composition of surface runoffs,and the total dissolved salts of FA watershed were higher than those of F watershed,showing the contribution of agricultural activities in FA watershed to the chemical runoffs.The ratios of Sidiss/Na+ and NO-3/SO2-4 in typical granitic watersheds(F,FA) of south Anhui Province were much higher than those in the Taihu Basin,which was rich in carbonate rocks and located in the same bioclimatic zone,indicating that the lithology and the chemical composition of acid deposition caused by human activities were the primary factors controlling the chemical runoffs.The contribution of precipitation to the chemical composition of surface runoffs in the granitic watersheds(F,FA) of south Anhui Province was 43% and 38% respectively,and the contribution of rock weathering was 57% and 50% respectively,while the contribution of the agricultural activities in the FA watershed was 12%.The consumption of CO2 by chemical weathering of granite in the small watersheds(F,FA) of south Anhui Province was(0.67—0.96)×105 mol · km-2 · a-1 and(0.64—1.05)×105 mol · km-2 · a-1 respectively,which were much lower than those of watersheds with carbonate rocks.%为了解小流域尺度下生物地球化学过程对径流水体的影响及花岗岩化学风化对CO2的吸收,对亚热带典型花岗岩区不同利用条件下的2个相邻小流域(F-森林、FA-森林/农田)的地表径流及其常量离子

  15. 高速公路路面径流沉降过程中重金属去除特性%Characteristics of heavy metal removal during highway runoff sedimentation

    Institute of Scientific and Technical Information of China (English)

    左晓俊; 傅大放; 李贺

    2009-01-01

    The removal rates of four heavy metals( Cu, Zn, Cd and Pb)during free sedimentation of runoff were investigated based on test results on the initial road surface runoff after 15 rainfall events from February 2008 to February 2009 on the Lingqiao section of the Nanjing Airport Expressway. The emphasis was placed on the relationship between the heavy metal removal and the settlement rate, as well as the relationship between the heavy metal removal and SS removal, and the effects of precipitation features and runoff pH values on the removal rates of heavy metals were explored. The removal rates of Cu, Zn, Cd and Pb increased rapidly during the first 30 minutes of settling, accounting for over 60% of the total removal rates of the four heavy metals in 2 hours. Pb had the highest 2 h mean removal rate (25.62%) and the 2 h mean removal rates of Cu, Cd and Zn were 21.20% , 19.97% and 19.10% , respectively. With every 10% increase of settling removal rate of the same heavy metal, the range and maximum value of settling velocity decreased by around 5 times. Under the same settling velocity, the removal efficiency of Pb is best while those of Cd, Cu and Zn showed little difference. The linear correlations of the settling removal rate between Cu, Zn, Cd, Pb and SS were different. Since Pb existed mostly in particulate form, the correlation of settling removal rate between Pb and SS was the highest, with a correlation coefficient of 0.8126 (p = 0. 0002 ). The correlation coefficients of settling removal rate between Cd, Cu, Zn and SS were 0. 6871,0. 6804 and 0. 7653 respectively. The runoff pH value had significant impact on the removal features of heavy metals, maintaining a positive relationship with the settling removal of the four heavy metals, and the correlation coefficients between runoff pH value and Zn, Cd and Pb were all higher than 0.5. Since Zn was mostly dissolved, its settling removal was most significantly impacted by the runoff pH value, and they were

  16. Extreme Heat

    Science.gov (United States)

    ... Landslides & Debris Flow Nuclear Blast Nuclear Power Plants Power Outages Pandemic Radiological Dispersion Device Severe Weather Snowstorms & Extreme ... Landslides & Debris Flow Nuclear Blast Nuclear Power Plants Power Outages Pandemic Radiological Dispersion Device Severe Weather Snowstorms & Extreme ...

  17. Functional approach to exploring climatic and landscape controls on runoff generation. 2. Timing of runoff storm response

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongyi; Sivapalan, Murugesu

    2014-12-09

    Hortonian overland flow, Dunne overland flow and subsurface stormflow are the three dominant mechanisms contributing to both the volume and timing of streamflow. A previous study quantified the climatic and landscape controls on the relative dominance of the volumes of the different runoff components. In this paper we explore the impacts of climate, soil and topography on the timing of these runoff components in small catchments within the framework of the Connected Instantaneous Response Functions (CIRF). The CIRF here is viewed as a probability density function of travel times of water droplets associated with a given runoff generation mechanism (from the locations where they are generated to the catchment outlet). CIRF is a refinement of the traditional catchment IRF in that it explicitly accounts for variable contributing areas: only those partial areas of runoff generation which are hydrologically connected to the outlet are regarded as contributing areas. The CIRFs are derived for each runoff mechanism through the numerical simulations with a spatially distributed hydrological model which accounts for spatially distributed runoff generation and routing, involving all three mechanisms, under multiple combinations of climate, soil and topographic properties. The advective and dispersive aspects of catchment’s runoff routing response are captured through the use of, respectively, the mean travel times and dimensionless forms of the CIRFs (i.e., scaled by their respective mean travel times). It was found that the CIRFs, upon non-dimensionalization, collapsed to common characteristic shapes, which could be explained in terms of the relative contributions of hillslope and channel network flows, and especially of the size of the runoff contributing areas. The contributing areas are themselves governed by the competition between drainage and recharge to the water table, and could be explained by a dimensionless drainage index which quantifies this competition. On

  18. Influence of storm magnitude and watershed size on runoff nonlinearity

    Science.gov (United States)

    Lee, Kwan Tun; Huang, Jen-Kuo

    2016-06-01

    The inherent nonlinear characteristics of the watershed runoff process related to storm magnitude and watershed size are discussed in detail in this study. The first type of nonlinearity is referred to rainfall-runoff dynamic process and the second type is with respect to a Power-law relation between peak discharge and upstream drainage area. The dynamic nonlinearity induced by storm magnitude was first demonstrated by inspecting rainfall-runoff records at three watersheds in Taiwan. Then the derivation of the watershed unit hydrograph (UH) using two linear hydrological models shows that the peak discharge and time to peak discharge that characterize the shape of UH vary event-to-event. Hence, the intention of deriving a unique and universal UH for all rainfall-runoff simulation cases is questionable. In contrast, the UHs by the other two adopted nonlinear hydrological models were responsive to rainfall intensity without relying on linear proportion principle, and are excellent in presenting dynamic nonlinearity. Based on the two-segment regression, the scaling nonlinearity between peak discharge and drainage area was investigated by analyzing the variation of Power-law exponent. The results demonstrate that the scaling nonlinearity is particularly significant for a watershed having larger area and subjecting to a small-size of storm. For three study watersheds, a large tributary that contributes relatively great drainage area or inflow is found to cause a transition break in scaling relationship and convert the scaling relationship from linearity to nonlinearity.

  19. Runoff generation mechanism at two distinct headwater catchments - isotopic evidence

    Science.gov (United States)

    Dohnal, Michal; Votrubová, Jana; Šanda, Martin; Tesař, Miroslav; Vogel, Tomáš; Dušek, Jaromír

    2016-04-01

    Data from two headwater catchments indicate considerably different runoff formation mechanisms. The contributions of different surface and subsurface runoff mechanisms to the catchment discharge formation at these two small forested headwater catchments are studied with help of the natural isotopic signatures of the observed fluxes. The Uhlirska catchment (1.78 sq. km, Jizera Mts., Czech Republic) is situated in headwater area of Cerna Nisa stream. Deluviofluvial granitic sediments in the valley bottom areas (riparian zones/wetlands) are surrounded by gentle hillslopes with shallow soils developed on crystalline bedrock. The Liz catchment (0.99 sq. km, Bohemian Forest, Czech Republic) belongs to hillslope-type catchments without riparian zones situated in headwater area of Volynka River. The soil at Liz is developed on biotite paragneiss bedrock. Autocorrelation analysis of the measured catchment discharge rates reveals different hydrograph characteristics for each of the two catchments. Estimated autocorrelation lengths differ by an order of magnitude. Variations of oxygen-18 isotope concentrations in precipitation, groundwater and streamflow were analyzed. Several significant rainfall-runoff events at each of the two catchments were analyzed in detail. These events exhibit substantial difference in isotopic compositions of event and pre-event water, which facilitates hydrograph separation. Clockwise and counterclockwise hysteretic relationships between the stream discharge and its isotope concentration were identified. Results were confronted with the previously published concepts of the runoff formation at the catchments under study. The research was funded by the Czech Science Foundation, project No. 14-15201J.

  20. Lead Isotopes in Highway Runoff

    Science.gov (United States)

    Ferreira, M.; Lau, S.; Green, P. G.; Stenstrom, M. K.

    2011-12-01

    Lead (Pb) isotopes have been used extensively to study the provenance of lead pollution on air, water, and sediments. In this study, we measured Pb isotopes and Pb aqueous concentration in highway runoff in three west Los Angeles sites. Those three sites, part of a long-term study sponsored by the California Department of Transportation, represent small catchment areas, and host heavy traffic. In addition, there were no inputs of sand or salt to the highway because the sites are almost completely impervious and also due to the lack of snow to be controlled. Highway runoff from the three sites was collected for 7 storms during the 2004-2005 Winter. Grab samples were collected every 15 minutes during the first hour, and hourly afterwards. A total of 202 samples were collected and filtered into five size fractions (100μm). Aqueous concentration of Pb range from 0.08μg/L to 46.95μg/L (7.98±10.89μg/L) and it is not correlated with any of the lead isotope ratios. The 208Pb/206Pb ratio ranges from 1.983 to 2.075 (2.024±0.026) and there is no statistical difference for the mean value of the 208Pb/206Pb ratio for the four particulate size fractions (0.45-8μm, 8-20μm, 20-100μm, >100μm). However, the 208Pb/206Pb ratio of nearby soils yield 2.060±0.021 and it is statistically different from the ratios obtained for the highway runoff. This hints that the lead present in highway runoff does not come from local soils. The 207Pb/206Pb ratio ranges from 0.804 to 0.847 (0.827±0.011) and there is no statistical difference for the mean value of the 207Pb/206Pb ratio for the four particulate size fractions (0.45-8μm, 8-20μm, 20-100μm, >100μm). Surprisingly, there is also no statistical difference with the 207Pb/206Pb ratio of nearby soils (0.833±0.009).

  1. Effects of forest vegetation on runoff and sediment transport of watershed in Loess area,west China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaoming; YU Xinxiao; WU Sihong; LIU Huifang

    2007-01-01

    This paper aims to study the effects of vegetation on runoff and sediment transport at the watershed scale,and to provide a theoretical basis for afforestation in the Loess area,in the nested Caijiachuan watershed,Jixian County,Shanxi Province of west China.Forest watersheds and farmland watersheds with similar ten'ain features were selected through cluster analysis to study their runoff and sediment transport characteristics.Results showed that compared with farmland watersheds,runoff generation time in forest watersheds was delayed remarkably,and peak flow was reduced greatly,which indicates that vegetation played an important role in holding and absorbing rainfall.Besides,with the increase of forest coverage,the runoff amount,runoff depth and runoff coefficient decreased during the rainy seasons.The runoff depth and runoff coefficient of farmland watersheds in the rainy season were 5-20-fold as much as that of forest watersheds,and runoff and sediment yield of watersheds with low forest coverage were 2.7-2.9-fold and 3-5-fold as great as those with high coverage during rainstorms,and low forest coverage had larger variation in sediment hydrograph.For the complexity and scale dependence of the influence of forest vegetation on runoff,forest hydrological functions based on regional scale or watershed scale were worthy of further studies.

  2. Dominant climatic factor driving annual runoff change at catchments scale over China

    Directory of Open Access Journals (Sweden)

    Z. Huang

    2015-12-01

    Full Text Available With global climate changes intensifying, the hydrological response to climate changes has attracted more attentions. It is beneficial not only for hydrology and ecology but also for water resources planning and management to reveal the impacts of climate change on runoff. It is of great significance of climate elasticity of runoff to estimate the impacts of climatic factors on runoff. In addition, there are large spatial variations in climate type and geography characteristics over China. To get a better understanding the spatial variation of runoff response to climate variables change and detect the dominant climatic factor driving annual runoff change, we chose the climate elasticity method proposed by Yang and Yang (2011, where the impact of the catchment characteristics on runoff was represented by a parameter n. The results show that the dominant climatic factor driving annual runoff is precipitation in the most part of China, net radiation in the lower reach of Yangtze River Basin, the Pearl River Basin, the Huai River Basin and the southeast area, and wind speed in part of the northeast China.

  3. Hydrology of small field plots used to study phosphorus runoff under simulated rainfall.

    Science.gov (United States)

    Srinivasan, M S; Kleinman, P J A; Sharpley, A N; Buob, T; Gburek, W J

    2007-01-01

    Use of small plots and rainfall simulators to extrapolate trends in runoff water quality requires careful consideration of hydrologic process represented under such conditions. A modified version of the National Phosphorus Runoff Project (NPRP) protocol was used to assess the hydrology of paired 1 x 2 m plots established on two soils with contrasting hydrologic properties (somewhat poorly drained vs. well drained). Rain simulations (60 mm h(-1)) were conducted to generate 30 min of runoff. For the somewhat poorly drained soil, simulations were conducted in October and May to contrast dry conditions typically targeted by NPRP protocols with wet conditions generally associated with natural runoff. For the well-drained soil, only dry conditions (October) were evaluated. Under dry antecedent moisture conditions, an average of 64 mm of rainfall was applied to the somewhat poorly drained soil to generate 30 min of runoff, as opposed to 96 mm to the well-drained soil. At an extreme, differences in rainfall were equivalent to a 50-yr rainfall-return period. An absence of detectable spatial trends in surface soil moisture suggests uniformity of runoff processes within the plots. No differences in applied rainfall were evident between wet and dry antecedent conditions for the somewhat poorly drained soil. However, significant differences in runoff generation processes were observed in dissolved P concentrations between wet and dry conditions. As natural runoff from the somewhat poorly drained soil is largely under wet antecedent conditions, this study highlights the need for care in interpreting findings from generalized protocols that favor infiltration-excess runoff mechanisms.

  4. Mandelbrot's Extremism

    NARCIS (Netherlands)

    Beirlant, J.; Schoutens, W.; Segers, J.J.J.

    2004-01-01

    In the sixties Mandelbrot already showed that extreme price swings are more likely than some of us think or incorporate in our models.A modern toolbox for analyzing such rare events can be found in the field of extreme value theory.At the core of extreme value theory lies the modelling of maxima

  5. Uncertainty based modeling of rainfall-runoff: Combined differential evolution adaptive Metropolis (DREAM) and K-means clustering

    Science.gov (United States)

    Zahmatkesh, Zahra; Karamouz, Mohammad; Nazif, Sara

    2015-09-01

    Simulation of rainfall-runoff process in urban areas is of great importance considering the consequences and damages of extreme runoff events and floods. The first issue in flood hazard analysis is rainfall simulation. Large scale climate signals have been proved to be effective in rainfall simulation and prediction. In this study, an integrated scheme is developed for rainfall-runoff modeling considering different sources of uncertainty. This scheme includes three main steps of rainfall forecasting, rainfall-runoff simulation and future runoff prediction. In the first step, data driven models are developed and used to forecast rainfall using large scale climate signals as rainfall predictors. Due to high effect of different sources of uncertainty on the output of hydrologic models, in the second step uncertainty associated with input data, model parameters and model structure is incorporated in rainfall-runoff modeling and simulation. Three rainfall-runoff simulation models are developed for consideration of model conceptual (structural) uncertainty in real time runoff forecasting. To analyze the uncertainty of the model structure, streamflows generated by alternative rainfall-runoff models are combined, through developing a weighting method based on K-means clustering. Model parameters and input uncertainty are investigated using an adaptive Markov Chain Monte Carlo method. Finally, calibrated rainfall-runoff models are driven using the forecasted rainfall to predict future runoff for the watershed. The proposed scheme is employed in the case study of the Bronx River watershed, New York City. Results of uncertainty analysis of rainfall-runoff modeling reveal that simultaneous estimation of model parameters and input uncertainty significantly changes the probability distribution of the model parameters. It is also observed that by combining the outputs of the hydrological models using the proposed clustering scheme, the accuracy of runoff simulation in the

  6. Modeling on runoff concentration caused by rainfall on hillslopes and application in Maoping slope

    Institute of Scientific and Technical Information of China (English)

    LIU Qingquan; LI Jiachun

    2006-01-01

    Based on the fact that the concentration flowlines of overland flow depend on the surface landform of hillslope, a kinematic wave model was developed for simulating runoff generation and flow concentration caused by rainfall on hillslopes. The model-simulated results agree well with the experimental observations. Applying the model to the practical case of Maoping slope, we obtained the characteristics of runoff generation and infiltration on the slope. Especially, the simulated results adequately reflected the confluent pattern of surface runoff, which offers a scientific foundation for designing the drainage engineering on the Maoping slope.

  7. Analysis of clinical characteristics and efficacy of chronic myeloid leukemia onset with extreme thrombocytosis in the era of tyrosine kinase inhibitors

    Directory of Open Access Journals (Sweden)

    Liu Z

    2017-07-01

    Full Text Available Zhihe Liu, Hongqiong Fan, Yuying Li, Chunshui Liu Department of Hematology, Cancer Center, The First Hospital of Jilin University, Changchun, People’s Republic of China Abstract: The aim of this study was to investigate the clinical characteristics and efficacy of chronic myeloid leukemia (CML onset with extreme thrombocytosis. A total of 121 newly diagnosed and untreated CML patients in chronic phase with complete clinical information from the First Hospital of Jilin University, from January 2010 to December 2014 were retrospectively recruited. Based on the platelet (PLT count, 22 patients were assigned into CML with thrombocytosis (CML-T group (PLT >1,000×109/L and 65 patients were classified into CML without extreme thrombocytosis (CML-N group (PLT ≤1,000×109/L. Fifty-four point five percent of patients in the CML-T group were female, which was higher than that in the CML-N group (27.7% (P=0.022. Except for gender, there was no significant difference for clinical information of patients between the two groups. For Sokal and Hasford scoring systems, the percentage of patients at high risk in the CML-T group were higher than those in the CML-N group, 95.5% vs 52.3% (P=0.000 and 68.2% vs 41.5% (P=0.031, respectively; however, there was no significant difference for European Treatment and Outcome Study (EUTOS score system between the two groups (P=0.213. In terms of major molecular response (MMR rate, the percent of patients with MMR in CML-T group was lower than that in CML-N group at 36 months after tyrosine kinase inhibitor therapy (P=0.037. Up until December 2016, the median of event-free survival was 21 months in the CML-T group, however, that was not reached in the CML-N group (P=0.027. The majority of CML patients with extreme thrombocytosis were females, and compared to patients in the CML-N group, the percentage of high risk patients based on the Sokal and Hasford scoring systems was higher in the CML-T group, and the median

  8. Clinical Characteristics and Risk Factor Analysis for Lower-Extremity Amputations in Diabetic Patients With Foot Ulcer Complicated by Necrotizing Fasciitis.

    Science.gov (United States)

    Chen, I-Wen; Yang, Hui-Mei; Chiu, Cheng-Hsun; Yeh, Jiun-Ting; Huang, Chung-Huei; Huang, Yu-Yao

    2015-11-01

    Patients with diabetes are at a higher risk of having diabetic foot ulcers (DFUs) or necrotizing fasciitis (NF). The present study aims to examine the clinical characteristics and associated risk factors for lower-extremity amputation (LEA) in patients with DFU complicated by NF.We retrospectively reviewed patients treated at a major diabetic foot center in Taiwan between 2009 and 2014. Of the 2265 cases 110 had lower-extremity NF. Limb preservation outcomes were classified as major LEA, minor LEA, or limb-preserved. Clinical characteristics, laboratory data, and bacterial culture results were collected for analysis.Of the 110 patients with NF, 100 had concomitant DFUs (NF with DFU) and the remaining 10 had no DFU (NF without DFU). None of the NF patients without DFU died nor had their leg amputated. Two NF patients with DFU died of complications. The amputation rate in the surviving 98 NF patients with DFU was 72.4% (46.9% minor LEA and 25.5% major LEA). Seventy percent of the NF patients without DFU had monomicrobial infections (60% with Streptococcus species), and 81.4% NF patients with DFU had polymicrobial infections. Anaerobic organisms were identified in 66% of the NF patients with DFU. Multinomial logistic regression analysis revealed an association between high-grade Wagner wound classification (Wagner 4 and Wagner 5) and LEA (adjusted odds ratio [aOR] = 21.856, 95% confidence interval [95% CI] = 1.625-203.947, P = 0.02 and aOR = 20.094, 95% CI = 1.968-205.216, P = 0.01 for major and minor LEA, respectively) for NF patients with DFU. In addition, a lower serum albumin level was associated with major LEA (OR = 0.066, P = 0.002).In summary, once DFUs were complicated by NF, the risk of amputation increased. Empirical treatment for NF patients with DFU should cover polymicrobial infections, including anaerobic organisms. The high-grade wound classification and low serum albumin level were associated with LEA.

  9. Predicting hydrological signatures in ungauged catchments using spatial interpolation, index model, and rainfall-runoff modelling

    Science.gov (United States)

    Zhang, Yongqiang; Vaze, Jai; Chiew, Francis H. S.; Teng, Jin; Li, Ming

    2014-09-01

    Understanding a catchment's behaviours in terms of its underlying hydrological signatures is a fundamental task in surface water hydrology. It can help in water resource management, catchment classification, and prediction of runoff time series. This study investigated three approaches for predicting six hydrological signatures in southeastern Australia. These approaches were (1) spatial interpolation with three weighting schemes, (2) index model that estimates hydrological signatures using catchment characteristics, and (3) classical rainfall-runoff modelling. The six hydrological signatures fell into two categories: (1) long-term aggregated signatures - annual runoff coefficient, mean of log-transformed daily runoff, and zero flow ratio, and (2) signatures obtained from daily flow metrics - concavity index, seasonality ratio of runoff, and standard deviation of log-transformed daily flow. A total of 228 unregulated catchments were selected, with half the catchments randomly selected as gauged (or donors) for model building and the rest considered as ungauged (or receivers) to evaluate performance of the three approaches. The results showed that for two long-term aggregated signatures - the log-transformed daily runoff and runoff coefficient, the index model and rainfall-runoff modelling performed similarly, and were better than the spatial interpolation methods. For the zero flow ratio, the index model was best and the rainfall-runoff modelling performed worst. The other three signatures, derived from daily flow metrics and considered to be salient flow characteristics, were best predicted by the spatial interpolation methods of inverse distance weighting (IDW) and kriging. Comparison of flow duration curves predicted by the three approaches showed that the IDW method was best. The results found here provide guidelines for choosing the most appropriate approach for predicting hydrological behaviours at large scales.

  10. Mid- and long-term runoff predictions by an improved phase-space reconstruction model.

    Science.gov (United States)

    Hong, Mei; Wang, Dong; Wang, Yuankun; Zeng, Xiankui; Ge, Shanshan; Yan, Hengqian; Singh, Vijay P

    2016-07-01

    In recent years, the phase-space reconstruction method has usually been used for mid- and long-term runoff predictions. However, the traditional phase-space reconstruction method is still needs to be improved. Using the genetic algorithm to improve the phase-space reconstruction method, a new nonlinear model of monthly runoff is constructed. The new model does not rely heavily on embedding dimensions. Recognizing that the rainfall-runoff process is complex, affected by a number of factors, more variables (e.g. temperature and rainfall) are incorporated in the model. In order to detect the possible presence of chaos in the runoff dynamics, chaotic characteristics of the model are also analyzed, which shows the model can represent the nonlinear and chaotic characteristics of the runoff. The model is tested for its forecasting performance in four types of experiments using data from six hydrological stations on the Yellow River and the Yangtze River. Results show that the medium-and long-term runoff is satisfactorily forecasted at the hydrological stations. Not only is the forecasting trend accurate, but also the mean absolute percentage error is no more than 15%. Moreover, the forecast results of wet years and dry years are both good, which means that the improved model can overcome the traditional ''wet years and dry years predictability barrier,'' to some extent. The model forecasts for different regions are all good, showing the universality of the approach. Compared with selected conceptual and empirical methods, the model exhibits greater reliability and stability in the long-term runoff prediction. Our study provides a new thinking for research on the association between the monthly runoff and other hydrological factors, and also provides a new method for the prediction of the monthly runoff.

  11. Research on runoff forecast approaches to the Aksu River basin

    Institute of Scientific and Technical Information of China (English)

    OUYANG RuLin; CHENG WeiMing; WANG WeiSheng; JIANG Yan; ZHANG YiChi; WANG YongQin

    2007-01-01

    The Aksu River (the international river between China and Kirghiz) has become the main water source for the Tarim River. It significantly influences the Tarim River's formation, development and evolution.Along with the western region development strategy and the Tarim River basin comprehensive development and implementation, the research is now focused on the Aksu River basin hydrologic characteristic and hydrologic forecast. Moreover, the Aksu River is representative of rivers supplied with glacier and snow melt in middle-high altitude arid district. As a result, the research on predicting the river flow of the Aksu River basin has theoretical and practical significance. In this paper, considering the limited hydrometeorological data for the Aksu River basin, we have constructed four hydrologic forecast approaches using the daily scale to simulate and forecast daily runoff of two big branches of the Aksu River basin. The four approaches are the upper air temperature and the daily runoff correlation method, AR(p) runoff forecast model, temperature and precipitation revised AR(p) model and the NAM rainfall-runoff model. After comparatively analyzing the simulation results of the four approaches, we discovered that the temperature and precipitation revised AR(p) model, which needs less hydrological and meteorological data and is more predictive, is suitable for the short-term runoff forecast of the Aksu River basin. This research not only offers a foundation for the Aksu River and Tarim Rivers' hydrologic forecast, flood prevention, control and the entire basin water collocation, but also provides the hydrologic forecast reference approach for other arid ungauged basins.

  12. Study on snowmelt runoff simulation in the Kaidu River basin

    Institute of Scientific and Technical Information of China (English)

    ZHANG YiChi; LI BaoLin; BAO AnMing; ZHOU ChengHu; CHEN Xi; ZHANG XueRen

    2007-01-01

    Alpine snowmelt is an important generation mode for runoff in the source region of the Tarim River basin, which covers four subbasins characterized by large area, sparse gauge stations, mixed runoff supplied by snowmelt and rainfall, and remarkably spatially heterogeneous precipitation. Taking the Kaidu River basin as a research area, this study analyzes the influence of these characteristics on the variables and parameters of the Snow Runoff Model and discusses the corresponding determination strategy to improve the accuracy of snowmelt simulation and forecast. The results show that: (i) The temperature controls the overall tendency of simulated runoff and is dominant to simulation accuracy,as the measured daily mean temperature cannot represent the average level of the same elevation in the basin and that directly inputting it to model leads to inaccurate simulations. Based on the analysis of remote sensing snow maps and simulation results, it is reasonable to approximate the mean temperature with 0.5 time daily maximum temperature. (ii) For the conflict between the limited gauge station and remarkably spatial heterogeneity of rainfall, it is not realistic to compute rainfall for each elevation zone. After the measured rainfall is multiplied by a proper coefficient and adjusted with runoff coefficient for rainfall, the measured rainfall data can satisfy the model demands. (iii) Adjusting time lag according to the variation of snowmelt and rainfall position can improve the simulation precision of the flood peak process. (iv) Along with temperature, the rainfall increases but cannot be completely monitored by limited gauge stations, which results in precision deterioration.

  13. Comparison of the Spatio-Temporal Variability of Annual Minimum Daily Extreme Flow Characteristics as a Function of Land Use and Dam Management Mode in Quebec, Canada

    Directory of Open Access Journals (Sweden)

    Jean-Michel Sylvain

    2015-03-01

    Full Text Available This study presents a comparison of the spatio-temporal variability of characteristics (magnitude, duration and timing of annual minimum daily extreme flows (AMEF as a function of land use and the mode of management of dams. Streamflow measured at stations not affected by dams at Joliette, along the L’Assomption River (agricultural watershed, 1340 km2, and at Saint-Michel-des-Saints, on the Matawin River (forested watershed, 1390 km2 on one hand, and downstream from the Rawdon dam (regulated natural-type management mode, on the Ouareau River (1260 km2, which is the main tributary of the L’Assomption River, and from the Matawin dam (inverted-type management mode, on the Matawin River (4070 km2, on the other hand, were compared over the period from 1930 to 2010. As far as the spatial variability of natural rivers is concerned, the magnitude and duration of AMEF are higher in the forested watershed than in the agricultural watershed. In regulated rivers, AMEF magnitude is higher downstream from the dam characterized by a natural-type management mode than downstream from the dam characterized by inversion-type management. However, downstream from the latter, AMEF occur much more frequently and very early in the year. As for temporal variability, the Lombard method did not reveal any influence of land use differences on the stationarity of series of AMEF characteristics. In contrast, differences in dam management mode result in occurrences of AMEF downstream from the inversion-type dam progressively earlier in the year. The duration and timing of AMEF are not correlated with the same climate variables, be it in natural rivers or downstream from dams.

  14. Exposure to extremely low frequency (50 Hz electromagnetic field changes the survival rate and morphometric characteristics of neurosecretory neurons of the earthworm Eisenia foetida (Oligochaeta under illumination stress

    Directory of Open Access Journals (Sweden)

    Banovački Zorana

    2013-01-01

    Full Text Available An in vivo model was set up to establish the behavioral stress response (rate of survival and morphometric characteristics of A1 protocerebral neurosecretory neurons (cell size of Eisenia foetida (Oligochaeta as a result of the synergetic effect of extremely low frequency electromagnetic fields (ELF-EMF - 50 Hz, 50 μT, 17 V/m and 50 Hz, 150 μT, 17 V/m, respectively and constant illumination (420-450 lux. If combined, these two stressors significantly (p<0.05 increased the survival rate of E. foetida in the 150 μT-exposed animals, because of delayed caudal autotomy reflex, an indicator of stress response. In addition, morphometric analysis indicated that there were changes in the protocerebral neurosecretory cells after exposure to the ELF-EMF. The present data support the view that short-term ELF-EMF exposure in “windows” of intensity is likely to stimulate the immune and neuroendocrine response of E. foetida.

  15. Aging characteristics of blue InGaN micro-light emitting diodes at an extremely high current density of 3.5 kA cm-2

    Science.gov (United States)

    Tian, Pengfei; Althumali, Ahmad; Gu, Erdan; Watson, Ian M.; Dawson, Martin D.; Liu, Ran

    2016-04-01

    The aging characteristics of blue InGaN micro-light emitting diodes (micro-LEDs) with different sizes have been studied at an extremely high current density 3.5 kA cm-2 for emerging micro-LED applications including visible light communication (VLC), micro-LED pumped organic lasers and optogenetics. The light output power of micro-LEDs first increases and then decreases due to the competition of Mg activation in p-GaN layer and defect generation in the active region. The smaller micro-LEDs show less light output power degradation compared with larger micro-LEDs, which is attributed to the lower junction temperature of smaller micro-LEDs. It is found that the high current density without additional junction temperature cannot induce significant micro-LED degradation at room temperature but the combination of the high current density and high junction temperature leads to strong degradation. Furthermore, the cluster LEDs, composed of a micro-LED array, have been developed with both high light output power and less light output degradation for micro-LED applications in solid state lighting and VLC.

  16. Estimating Runoff Coefficients Using Weather Radars

    DEFF Research Database (Denmark)

    Ahm, Malte; Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2012-01-01

    This paper presents a method for estimating runoff coefficients of urban drainage catchments based on a combination of high resolution weather radar data and insewer flow measurements. By utilising the spatial variability of the precipitation it is possible to estimate the runoff coefficients...

  17. Estimating Runoff Coefficients Using Weather Radars

    DEFF Research Database (Denmark)

    Ahm, Malte; Thorndahl, Søren Liedtke; Rasmussen, Michael R.;

    2012-01-01

    This paper presents a method for estimating runoff coefficients of urban drainage catchments based on a combination of high resolution weather radar data and insewer flow measurements. By utilising the spatial variability of the precipitation it is possible to estimate the runoff coefficients...

  18. Impact of urbanization on rainfall-runoff processes: case study in the Liangshui River Basin in Beijing, China

    Science.gov (United States)

    Xu, Zongxue; Zhao, Gang

    2016-05-01

    China is undergoing rapid urbanization during the past decades. For example, the proportion of urban population in Beijing has increased from 57.6 % in 1980 to 86.3 % in 2013. Rapid urbanization has an adverse impact on the urban rainfall-runoff processes, which may result in the increase of urban flood risk. In the present study, the major purpose is to investigate the impact of land use/cover change on hydrological processes. The intensive human activities, such as the increase of impervious area, changes of river network morphology, construction of drainage system and water transfer, were considered in this study. Landsat TM images were adopted to monitor urbanization process based on Urban Land-use Index (ULI). The SWMM model considering different urbanized scenarios and anthropogenic disturbance was developed. The measured streamflow data was used for model calibration and validation. Precipitation with different return periods was taken as model input to analyse the changes of flood characteristics under different urbanized scenarios. The results indicated that SWMM provided a good estimation for storms under different urbanized scenarios. The volume of surface runoff after urbanization was 3.5 times greater than that before urbanization; the coefficient of runoff changed from 0.12 to 0.41, and the ratio of infiltration decreased from 88 to 60 %. After urbanization, the time of overland flow concentration increased while the time of river concentration decreased; the peak time did not show much difference in this study. It was found that the peak flow of 20-year return-period after urbanization is greater than that of 100-year return-period before urbanization. The amplification effect of urbanization on flood is significant, resulting in an increase of the flooding risk. These effects are especially noticeable for extreme precipitation. The results in this study will provide technical support for the planning and management of urban storm water and the

  19. Effects of pre-dry grade on soil cracks and characteristics of runoff and sediment in red soil slopes%前期旱情等级对红壤坡面土壤裂缝及产流产沙特征的影响

    Institute of Scientific and Technical Information of China (English)

    陈晓安

    2015-01-01

    在人工模拟试验的基础上,采用图片处理技术和统计分析方法,分析无旱、轻旱、中旱、重旱4种旱情级别下的坡面土壤裂缝特征以及前期干旱影响下的坡面产流产沙特征。结果表明:土壤裂缝长度密度、面积密度、宽度、裂缝交点数、土壤裂缝弯曲度从小到大依次为轻旱、中旱、重旱;土壤裂缝条数从轻旱到中旱略有下降,到重旱后土壤裂缝数量激增,土壤裂缝网络的连通性从轻旱到中旱急剧增大,中旱到重旱基本一致。轻旱、中旱、重旱下土壤产流开始时间比无旱土壤分别增加1.83、2.43、3.87 min,产流截止时间比无旱土壤分别减少0.97、1.23、1.40 min;无旱、轻旱、中旱、重旱土壤产流稳定前各时段产流量依次减小,稳定后无明显差异,总产流量随旱情等级加大而减小。土壤平均产沙浓度从无旱、轻旱、中旱依次增加,中旱到重旱有所减小,稳定前土壤产沙速率从轻旱到重旱依次减小,无旱土壤最小,从无旱到重旱总侵蚀产沙先增大后减小,轻旱、中旱、重旱土壤侵蚀量分别是无旱的3.92、3.85、2.50倍。%Based on artificial stimulation experiment,soil crack characteristics and runoff and sediment yields under different drought grades such as no drought,slight drought,medium drought and severe drought have been investigated with the help of photograph processing and statistical methods.The results suggested that soil crack length density,area density,width, intersection and curvature increased with the increasing of drought grade.In addition, the number of soil crack under slight drought was slightly less than medium drought,but much less than severe drought.Soil crack connectivity sharply increased from slight drought to medium slight with no differences between medium slight and severe drought.The starting time of runoff yield under slight drought,medium drought

  20. Rainfall timing and runoff: The influence of the criterion for rain event separation

    Directory of Open Access Journals (Sweden)

    Molina-Sanchis Isabel

    2016-09-01

    Full Text Available Rain is not uniform in time and space in semiarid areas and its distribution is very important for the runoff process. Hydrological studies usually divide rainfall into events. However, defining rain events is complicated, and rain characteristics vary depending on how the events are delimited. Choosing a minimum inter-event time (MIT is a commonly used criterion. Our hypothesis is that there will be an optimal MIT that explains the maximum part of the variance of the runoff, with time to runoff used as a surrogate. The objective is to establish a procedure in order to decide upon this optimal MIT. We developed regressions between time to runoff (T0 and three descriptive variables of rain. Our results show that the optimum MIT is 1 hour, which seems to be the minimum period of time required for water in larger macropores to drain and sufficiently modify the effect of antecedent soil moisture on the runoff generation process. Rain events are classified into three significantly different groups: (1 large and intense rains, (2 light rains on wet soil, and (3 light rains on dry soil. Intense rains produce most of the runoff, but there were significant differences between small events in the runoff generated. Of rain events, 63.75% are single-tip events, and many could be dew.

  1. Impacts of Climatic Change on River Runoff in Northern Xinjiang of China over Last Fifty Years

    Institute of Scientific and Technical Information of China (English)

    YANG Yuhui; CHEN Yaning; LI Weihong; WANG Minzhong; SUN Guili

    2010-01-01

    The characteristics of climatic change and river runoff, as well as the response of river runoff to climatic change in the northern Xinjiang are analyzed on the basis of the hydrological and meteorological data over the last 50 years by the methods of Mann-Kendall nonparametric test and the nonlinear regression model. The results show that: 1) The temperature and the precipitation increased significantly in the whole northern Xinjiang, but the precipitation displayed no obvious change, or even a decreasing trend in the northern mountainous area of the northern Xinjiang. 2) River runoff varied in different regions in the northern Xinjiang. It significantly increased in the northern slope of the Tianshan Mountains and the north of the northern Xinjiang (p=0.05), while slightly increased in the west of the northern Xinjiang. 3) North Atlantic Oscillation (NAO) affects river runoff by influencing temperature and precipita-tion. The NAO and precipitation had apparent significant correlations with the river runoff, but the temperature did not in the northern Xinjiang. Since the mid-1990s river runoff increase was mainly caused by the increasing temperature in the northern slope of the Tianshan Mountains and the north of the northern Xinjiang. Increased precipitation resulted in increased river runoff in the west of the northern Xinjiang.

  2. The effect of leaf litter cover on surface runoff and soil erosion in Northern China.

    Science.gov (United States)

    Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

    2014-01-01

    The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter), four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (psoil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, psoil erosion control, since no significant differences (p≤0.05) were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (perosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes.

  3. Possible change on the runoff in the upper Yellow River basin under global climate change

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this study,the characteristics and changing trends of temperature,precipitation,and runoff in the upper Yellow River basin up Tangnag station are analyzed by using hydrological and meteorological data in the past 50 years from observation stations in the basin.Further,in this study,the evolving trend of runoff in the future decades is forecasted in the basin based on the method of suppositional climate scenes combination.The results indicate temperature variation in the basin has an evident positive relation with global warming,and the precipitation variations are quite complicated in the basin because of differences of located geographic positions during the past 50 years.Runoff in the basin has been decreasing continually since the end of the 1980s because the mean temperature in the basin has been rising and precipitation in the main areas of runoff formation in the basin has been decreasing.Runoff will largely decrease if precipitation decreases and temperature rises continuously,whereas runoff will increase if temperature is invariable and precipitation increases largely;the increase magnitude of runoff may be more than that of precipitation because of the synchronously increasing supply of meltwater from snow,glacier,and frozen soils in future several decades.

  4. Hydrology without hillslopes: runoff controls and pathways on a near-level, engineered landscape

    Science.gov (United States)

    Petzold, Halya; Ali, Genevieve

    2015-04-01

    Low relief, artificially drained landscapes like those of the Prairies in south-central Canada have received little consideration in hydrologic study. While topography is generally asserted as the main control of runoff generation, it is unknown whether this is also the case where relief is low, or if in the absence of high relief other landscape characteristics become relatively more influential. To address this knowledge gap, runoff behaviour was analysed via event rainfall-runoff hydrographs and perched water table level at 6 study sites to infer dominant runoff processes and their control factors. Instrumentation was deployed in the Catfish Creek watershed, a 642 km2 near-level, mixed land use and engineered Prairie watershed located 90 km northeast of Winnipeg, Manitoba, Canada. Specifically, surface water levels were measured at the outlet of six sub-watersheds while perched water table levels were monitored in riparian areas. At each site, rainfall events were delineated and rainfall-runoff parameters, perched water table maximum rise and antecedent rainfall variables (as surrogates for antecedent moisture conditions or AMCs) were calculated on an event basis. Landscape characteristics, including elevation, slope, and land use and land cover statistics, were also determined for each sub-watershed. Correlation analysis and principal component analysis were then carried out including all variables. Rainfall-runoff responses were highly variable across sites. Event hydrographs were generally characterized by short lag times and initial abstractions which correlated moderately to total event rainfall. However, sub-watersheds characteristics did not influence the different hydrograph characteristics recorded across sites. Threshold behaviour was observed only in the two study sub-watersheds of greatest relief. Runoff generation was hypothesized to occur predominantly as Hortonian overland flow, although the dominant runoff process shifted under certain moisture

  5. Runoff initiation versus runoff yield: Understanding the complexity of the hydrological effect of biological soil crusts

    Science.gov (United States)

    Kidron, G. J.; Monger, H. C.; Büdel, B.; Vonshak, A.; Conrod, W.

    2012-04-01

    The differentiation between runoff initiation and runoff yield (amount) is not always clear. In many cases they often seem interchangeable. Some of the differences were pinpointed following research conducted at two sand fields in Israel (Nizzanim, NIM, at the southern coast and Nizzana, NIZ in the Negev) and three sites in the Chihuahuan Desert, New Mexico, USA (silty-loessial sediments at the Jornada Experimental Range, JER; quartzose sand in the Sevilleta Wildlife Refuge, SEV; gypseous sand at the White Sands National Monument, WS) during which intact plots were compared to scalped plots. While the parent material, the effective rain, and the exopolysacharide (EPS) content of the crust determined runoff initiation in the Chihuahuan Desert, the effective rain and the crust microrelief determined the amount (yield) of runoff in areas where runoff initiation took place. Low EPS-crusts did not facilitated runoff initiation, even at high-chlorophyll crusts such as in WS. Similar results were obtained for NIM. Data from NIZ also highlighted the fundamental role played by the EPS in the determination of the amounts of runoff. This however was not the case with the chlorophyll content per se, that did not determine runoff initiation or yield. The findings also indicate that under the conditions examined, microrelief could not have controlled runoff initiation. Nevertheless, it affected the runoff amounts, as found in the Chihuahuan Desert and the Negev. The presence of rills and gullies may be indicative of the potentiality of BSCs to initiate runoff.

  6. Average annual runoff in the United States, 1951-80

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This is a line coverage of average annual runoff in the conterminous United States, 1951-1980. Surface runoff Average runoff Surface waters United States

  7. Use of Entropy in the Assessment of Uncertainty of River Runoff Regime in Poland

    Science.gov (United States)

    Wrzesiński, Dariusz

    2016-10-01

    The objective of this paper is to describe spatial differences in the uncertainty of features of the runoff regimes of Polish rivers based on entropy in Shannon's information theory. They included: the entropy of monthly river runoff and the entropy of river runoff distribution over time. An analysis of monthly flow series for the years 1951-2010 from 395 gauging stations located on 248 rivers in Poland was performed. This allowed a quantitative determination of the degree of uncertainty of two regime characteristics indirectly establishing the predictability, regularity, and stability of their appearance and their spatial variability. An analysis of relations between the calculated entropy, as well as between the entropy and the classical parameters commonly used was performed in describing the hydrological regime. The obtained grouping of rivers into four categories in terms of entropy of volume and distribution of runoff in the annual cycle clearly coincides with the types of river regime distinguished in Poland.

  8. Multiple Time Scale Analysis of River Runoff Using Wavelet Transform for Dagujia River Basin, Yantai, China

    Institute of Scientific and Technical Information of China (English)

    LIU Delin; LIU Xianzhao; LI Bicheng; ZHAO Shiwei; LI Xiguo

    2009-01-01

    Based on monOdy river runoff and meteorological data, a method of Morlet wavelet transform was used to analyze the multiple time scale characteristics of river runoffin the Dagnjia River Basin, Yantai City, Shandong Province. The results showed that the total annual river runoff in the Dagujia River Basin decreased significantly from 1966 to 2004, and the rate of decrease was 48×106m3/10yr, which was higher than the mean value of most rivers in China. Multiple time scale characteristics existed, which accounted for different aspects of the changes in annual river runoff, and the major periods of the runoff time series were identified as about 28 years, 14 years and 4 years with decreasing levels of fluctuation. The river runoff evolution process was controlled by changes in precipitation to a certain extent, but it was also greatly influenced by human activities. Also, for different time periods and scales, the impacts of climate changes and human activities on annual river runoff evolution occurred at the same time. Changes in the annual river runoffwere mainly associated with climate change before the 1980s and with human activities after 1981.

  9. Spatial and temporal change characteristics of extremely cold weather in Hulun Buir%呼伦贝尔市极寒天气时空分布特征

    Institute of Scientific and Technical Information of China (English)

    阴秀霞

    2016-01-01

    With extremely cold days data from 16 stations in Hulun Buir during 1960—2014,the results showed that the geographical distribution of arctic days were unevenness and decreased from north to south;the forest area was more than pastoral area and rural area was the least. Interdecadal characteristics showed that arctic days in the 1960 s and 1970 s were the most,up to the 1960 s and the number of days significantly reduced in the 1980 s,at least in the 1990 s. At the beginning of 21 century,another arctic day slightly increased.The arctic days more appered in late December to late January, up to mid-January,followed by late January and gradual decreased after the beginning of spring in February.%文章对呼伦贝尔市16个台站1960—2014年极寒日进行了统计分析,结果表明:极寒日的地域分布不均匀,由北向南逐渐减少,林区多于牧区,牧区又多于农区;年代际特征是20世纪60年代与70年代日数较多,60年代最多;到了80年代日数大幅减少,90年代最少。进入21世纪初,极寒日又有小幅增多。隆冬12月下旬至1月下旬是极寒日数多的月份,其中1月中旬最多,1月下旬次之,立春后2月份逐渐减少。

  10. An association analysis between psychophysical characteristics and genome-wide gene expression changes in human adaptation to the extreme climate at the Antarctic Dome Argus.

    Science.gov (United States)

    Xu, C; Ju, X; Song, D; Huang, F; Tang, D; Zou, Z; Zhang, C; Joshi, T; Jia, L; Xu, W; Xu, K-F; Wang, Q; Xiong, Y; Guo, Z; Chen, X; Huang, F; Xu, J; Zhong, Y; Zhu, Y; Peng, Y; Wang, L; Zhang, X; Jiang, R; Li, D; Jiang, T; Xu, D; Jiang, C

    2015-04-01

    Genome-wide gene expression measurements have enabled comprehensive studies that integrate the changes of gene expression and phenotypic information to uncover their novel associations. Here we reported the association analysis between psychophysical phenotypes and genome-wide gene expression changes in human adaptation to one of the most extreme climates on Earth, the Antarctic Dome Argus. Dome A is the highest ice feature in Antarctica, and may be the coldest, driest and windiest location on earth. It is considered unapproachable due to its hostile environment. In 2007, a Chinese team of 17 male explorers made the expedition to Dome A for scientific investigation. Overall, 133 psychophysical phenotypes were recorded, and genome-wide gene expression profiles from the blood samples of the explorers were measured before their departure and upon their arrival at Dome A. We found that mood disturbances, including tension (anxiety), depression, anger and fatigue, had a strong, positive, linear relationship with the level of a male sex hormone, testosterone, using the Pearson correlation coefficient (PCC) analysis. We also demonstrated that significantly lowest-level Gene Ontology groups in changes of gene expression in blood cells with erythrocyte removal were consistent with the adaptation of the psychophysical characteristics. Interestingly, we discovered a list of genes that were strongly related to significant phenotypes using phenotype and gene expression PCC analysis. Importantly, among the 70 genes that were identified, most were significantly related to mood disturbances, where 42 genes have been reported in the literature mining, suggesting that the other 28 genes were likely novel genes involved in the mood disturbance mechanism. Taken together, our association analysis provides a reliable method to uncover novel genes and mechanisms related to phenotypes, although further studies are needed.

  11. Phosphorus losses in furrow irrigation runoff.

    Science.gov (United States)

    Westermann, D T; Bjorneberg, D L; Aase, J K; Robbins, C W

    2001-01-01

    Phosphorus (P) often limits the eutrophication of streams, rivers, and lakes receiving surface runoff. We evaluated the relationships among selected soil P availability indices and runoff P fractions where manure, whey, or commercial fertilizer applications had previously established a range of soil P availabilities on a Portneuf silt loam (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid) surface-irrigated with Snake River water. Water-soluble P, Olsen P (inorganic and organic P), and iron-oxide impregnated paper-extractable P (FeO-Ps) were determined on a 0.03-m soil sample taken from the bottom of each furrow before each irrigation in fall 1998 and spring 1999. Dissolved reactive phosphorus (DRP) in a 0.45-microm filtered runoff sample, and iron-oxide impregnated paper-extractable P (FeO-Pw), total P, and sediment in an unfiltered runoff sample were determined at selected intervals during a 4-h irrigation on 18.3-m field plots. The 1998 and 1999 data sets were combined because there were no significant differences. Flow-weighted average runoff DRP and FeO-Pw concentrations increased linearly as all three soil P test concentrations increased. The average runoff total P concentration was not related to any soil P test but was linearly related to sediment concentration. Stepwise regression selected the independent variables of sediment, soil lime concentration, and soil organic P extracted by the Olsen method as related to average runoff total P concentration. The average runoff total P concentration was 1.08 mg L(-1) at a soil Olsen P concentration of 10 mg kg(-1). Soil erosion control will be necessary to reduce P losses in surface irrigation runoff.

  12. Clouds enhance Greenland ice sheet meltwater runoff

    OpenAIRE

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2)Wm-2. Co...

  13. Clouds enhance Greenland ice sheet meltwater runoff

    OpenAIRE

    K. Van Tricht; Lhermitte, S.; Lenaerts, J. T. M.; Gorodetskaya, I. V.; L'Ecuyer, T. S.; Noël, B; Van Den Broeke, M.R.; Turner, D. D.; Van Lipzig, N. P. M.

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2)Wm-2. Co...

  14. Extreme cosmos

    CERN Document Server

    Gaensler, Bryan

    2011-01-01

    The universe is all about extremes. Space has a temperature 270°C below freezing. Stars die in catastrophic supernova explosions a billion times brighter than the Sun. A black hole can generate 10 million trillion volts of electricity. And hypergiants are stars 2 billion kilometres across, larger than the orbit of Jupiter. Extreme Cosmos provides a stunning new view of the way the Universe works, seen through the lens of extremes: the fastest, hottest, heaviest, brightest, oldest, densest and even the loudest. This is an astronomy book that not only offers amazing facts and figures but also re

  15. Interception of rainfall and surface runoff in the Brazilian Cerrado

    Science.gov (United States)

    Tarso Oliveira, Paulo; Wendland, Edson; Nearing, Mark; Perea Martins, João

    2014-05-01

    The Brazilian Cerrado plays a fundamental role in water resources dynamics because it distributes fresh water to the largest basins in Brazil and South America. In recent decades, the native Cerrado vegetation has increasingly been replaced by agricultural crops and pasture. These land cover and land use changes have altered the hydrological processes. Meanwhile, little is known about the components of the water balance in the Brazilian Cerrado, mainly because the experimental field studies in this region are scarce or nonexistent. The objective of this study was to evaluate two hydrological processes under native Cerrado vegetation, the canopy interception (CI) and the surface runoff (R). The Cerrado physiognomy was classified as "cerrado sensu stricto denso" with an absolute density of 15,278 trees ha-1, and a basal area of 11.44 m2 ha-1. We measured the gross rainfall (P) from an automated tipping bucket rain gauge (model TB4) located in a tower with 11 m of height on the Cerrado. Throughfall (TF) was obtained from 15 automated tipping bucket rain gauges (model Davis) spread below the Cerrado vegetation and randomly relocated every month during the wet season. Stemflow (SF) was measured on 12 trees using a plastic hose wrapped around the trees trunks, sealed with neutral silicone sealant, and a bucket to store the water. The canopy interception was computed by the difference between P and the sum of TF and SF. Surface runoff under undisturbed Cerrado was collected in three plots of 100 m2(5 x 20 m) in size and slope steepness of approximately 0.09 m m-1. The experimental study was conducted between January 2012 and November 2013. We found TF of 81.0% of P and SF of 1.6% of P, i.e. the canopy interception was calculated at 17.4% of P. There was a statistically significant correlation (p 0.8. Our results suggest that the rainfall intensity, the characteristics of the trees trunks (crooked and twisted) and stand structure are the main factors that have influenced

  16. Multiple-scale analysis of runoff-sediment tendency in Zhenjiangguan watershed based on stage characteristics%基于阶段特性的岷江镇江关以上流域水沙趋势多尺度分析

    Institute of Scientific and Technical Information of China (English)

    张会兰; 李丹勋; 姜晓明; 王兴奎

    2013-01-01

    The wavelet theory for multi-temporal and multi-spatial scale analysis was applied to study the variability characteristics of the monthly runoff and sediment transport at the Zhenjiangguan station in the upper Min River basin in flood seasons (from May to October) of 1964-2006.Multi-resolution analysis (MRA)was used to calculate the trends of runoff and sediment variations.Results show that the runoff and the sediment discharge had been increasing until 1986 and then were decreasing.For these two records,continuous wavelet transform (CWT) and spectrum charts were applied to identify their periodicity and plusminus phase structures,and their dominant frequencies at different stages.This analysis reveals that the dominant periods of both records in the time period up to 1986 were 8 years,while after that they changed into 5 years and 16 years in the runoff and sediment discharge respectively.Such structural transformation comes from a contradiction of less soil erosion against worse water supply.Thus,sufficient water resources and stable water supply become an essential problem in the management of this watershed.Human activities and climate changes are two major factors responsible for the changes in water-sediment conditions.%基于小波分析理论对岷江上游镇江关水文站1964-2006年汛期(5~10月)月径流和月输沙量的变化特性进行了多时空尺度分析.利用多分辨率分析对水沙序列变化趋势分析表明,以1986年为时间拐点,水沙序列呈现出先上升后下降的阶段特性.采用连续小波变换分析水沙序列的周期特性和位相结构,并利用方差图定量计算不同阶段的主周期变化.结果表明:在全时域和1986年前期,二者均以8年为主周期,而1986年后二者的主周期分别转变为5年和16年,来沙条件有所好转而来水条件变得恶劣,水资源供给和水土流失矛盾发生了结构性转变,水资源的充分和稳定供给成为流

  17. Influence of storm magnitude and watershed size on runoff nonlinearity

    Indian Academy of Sciences (India)

    Kwan Tun Lee; Jen-Kuo Huang

    2016-06-01

    The inherent nonlinear characteristics of the watershed runoff process related to storm magnitude andwatershed size are discussed in detail in this study. The first type of nonlinearity is referred to rainfallrunoffdynamic process and the second type is with respect to a Power-law relation between peakdischarge and upstream drainage area. The dynamic nonlinearity induced by storm magnitude was firstdemonstrated by inspecting rainfall-runoff records at three watersheds in Taiwan. Then the derivation ofthe watershed unit hydrograph (UH) using two linear hydrological models shows that the peak dischargeand time to peak discharge that characterize the shape of UH vary event-to-event. Hence, the intentionof deriving a unique and universal UH for all rainfall-runoff simulation cases is questionable. In contrast,the UHs by the other two adopted nonlinear hydrological models were responsive to rainfall intensitywithout relying on linear proportion principle, and are excellent in presenting dynamic nonlinearity.Based on the two-segment regression, the scaling nonlinearity between peak discharge and drainagearea was investigated by analyzing the variation of Power-law exponent. The results demonstrate thatthe scaling nonlinearity is particularly significant for a watershed having larger area and subjecting toa small-size of storm. For three study watersheds, a large tributary that contributes relatively greatdrainage area or inflow is found to cause a transition break in scaling relationship and convert the scalingrelationship from linearity to nonlinearity.

  18. Shrubs and Runoff in Semiarid Landscapes: Whats the Linkage?

    Science.gov (United States)

    Wilcox, B. P.; Owens, M. K.; Knight, R.; Lyons, R. K.

    2001-12-01

    Here we examine linkage between streamflow and shrub cover in semiarid landscapes with a focus on the extensive Texas rangelands covered by mesquite and juniper. The conclusions drawn are consistent with results from field studies and with our understanding of runoff processes from rangelands. Whether and how shrub control will affect streamflow depends on shrub characteristics, precipitation, soils, and geology. Precipitation is perhaps the most fundamental of these factors: there is little if any real potential for increasing streamflow where annual precipitation is below about 500 mm. For areas in which precipitation is sufficient, an excellent indicator that there is potential for increasing streamflow through shrub control is that base flow is an important component of streamflow. Another key indicator is shallow soils underlain by fractured parent material; under such conditions, increased streamflows are possible mainly because water that would otherwise be lost through interception by the canopy instead moves into the soil and quickly travels beyond the root zone. Conversely, where soils are deep there is little evidence that streamflow can be significantly increased by reducing brush cover. Results from a 10 year small watershed study where juniper was selectively removed in the Edwards plateau region of Texas will be summarized in this presentation. In assessing the potential for shrub control to increase streamflow, the runoff generation process should be explicitly identified. Areas in which Horton overland flow is the primary runoff mechanism offer little potential for increasing streamflow via vegetation management.

  19. Green Roofs for Stormwater Runoff Control - Abstract

    Science.gov (United States)

    This project evaluated green roofs as a stormwater management tool. Specifically, runoff quantity and quality from green and flat asphalt roofs were compared. Evapotranspiration from planted green roofs and evaporation from unplanted media roofs were also compared. The influence...

  20. Total pollution effects of urban surface runoff

    Institute of Scientific and Technical Information of China (English)

    LUO Hong-bing; LUO Lin; HUANG Gu; LIU Ping; LI Jing-xian; HU Sheng; WANG Fu-xiang; XU Rui; HUANG Xiao-xue

    2009-01-01

    e values of MFFn (mass first flush ratio) and FF30 (first 30% of runoff volume) can be considered as split-flow control criteria to enable more effective and economical design of structural BMPs (best management practices) facilities.

  1. Influence of soil water repellency on runoff and solute loss from New Zealand pasture

    Science.gov (United States)

    Jeyakumar, P.; Müller, K.; Deurer, M.; van den Dijssel, C.; Mason, K.; Green, S.; Clothier, B. E.

    2012-04-01

    persistence and degree of SWR. The runoff coefficients were 96 (±2), 28 (±4), and 16 (±2.5) % for the Histosol, Gleysol and Fluvisol, respectively. However, even the extremely hydrophobic Histosol, which had a runoff coefficient of 96%, only lost 13% of the applied bromide via run-off demonstrating that run-off occurred in channels. In addition, SWR reduced the water storage by 33, 14, and 41% for the Fluvisol, Gleysol and Histosol, respectively. We identified difficulties around the accuracy and meaningfulness of the persistence of SWR determined with the water drop penetration time (WDPT) test, which measures the persistence of SWR at a single point. In contrast, our ROMA experiments integrate the spatial variability of SWR of an undisturbed soil slab. In addition, the method is faster for extremely hydrophobic soils once the ROMA is set up. We are currently analyzing if our soil slab experiments are representative of larger scale run-off behaviour on the field.

  2. Impact of landuse/land cover change on run-off in the catchment of a hydro power project

    Science.gov (United States)

    Khare, Deepak; Patra, Diptendu; Mondal, Arun; Kundu, Sananda

    2017-05-01

    The landuse/land cover change and rainfall have a significant influence on the hydrological response of the river basins. The run-off characteristics are changing naturally due to reduction of initial abstraction that increases the run-off volume. Therefore, it is necessary to quantify the changes in the run-off characteristics of a catchment under the influence of changed landuse/land cover. Soil conservation service model has been used in the present study to analyse the impact of various landuse/land cover (past, present and future time period) change in the run-off characteristics of a part of Narmada basin at the gauge discharge site of Mandaleswar in Madhya Pradesh, India. Calculated run-off has been compared with the observed run-off data for the study. The landuse/land cover maps of 1990, 2000 and 2009 have been prepared by digital classification method with proper accuracy using satellite imageries. The impact of the run-off change on hydro power potential has been assessed in the study along with the estimation of the future changes in hydro power potential. Five types of conditions (+10, +5 %, average, -5, -10 % of average rainfall) have been applied with 90 and 75 % dependability status. The generated energy will be less in 90 % dependable flow in respect to the 75 % dependable flow. This work will be helpful for future planning related to establishment of hydropower setup.

  3. Regionalized rainfall-runoff model to estimate low flow indices

    Science.gov (United States)

    Garcia, Florine; Folton, Nathalie; Oudin, Ludovic

    2016-04-01

    Estimating low flow indices is of paramount importance to manage water resources and risk assessments. These indices are derived from river discharges which are measured at gauged stations. However, the lack of observations at ungauged sites bring the necessity of developing methods to estimate these low flow indices from observed discharges in neighboring catchments and from catchment characteristics. Different estimation methods exist. Regression or geostatistical methods performed on the low flow indices are the most common types of methods. Another less common method consists in regionalizing rainfall-runoff model parameters, from catchment characteristics or by spatial proximity, to estimate low flow indices from simulated hydrographs. Irstea developed GR2M-LoiEau, a conceptual monthly rainfall-runoff model, combined with a regionalized model of snow storage and melt. GR2M-LoiEau relies on only two parameters, which are regionalized and mapped throughout France. This model allows to cartography monthly reference low flow indices. The inputs data come from SAFRAN, the distributed mesoscale atmospheric analysis system, which provides daily solid and liquid precipitation and temperature data from everywhere in the French territory. To exploit fully these data and to estimate daily low flow indices, a new version of GR-LoiEau has been developed at a daily time step. The aim of this work is to develop and regionalize a GR-LoiEau model that can provide any daily, monthly or annual estimations of low flow indices, yet keeping only a few parameters, which is a major advantage to regionalize them. This work includes two parts. On the one hand, a daily conceptual rainfall-runoff model is developed with only three parameters in order to simulate daily and monthly low flow indices, mean annual runoff and seasonality. On the other hand, different regionalization methods, based on spatial proximity and similarity, are tested to estimate the model parameters and to simulate

  4. Understanding Greenland Ice Sheet Runoff Losses

    Science.gov (United States)

    Rennermalm, A. K.; Tedesco, M.; Smith, L. C.; Pitcher, L. H.; Mote, T. L.; Yager, P. L.; Moustafa, S.; Cooper, M. G.; van As, D.; Hasholt, B.; Mikkelsen, A. B.

    2016-12-01

    One of the main ways the ice sheet loses mass is by meltwater runoff. Because of Greenland's great size, regional surface mass balance models are key to understanding large-scale runoff patterns and trends. At the same time, remote sensing and field observations reveal a complex hydrological system on the ice sheet's surface that are not well captured by these models. Yet, understanding the fate and impact of the meltwater on the ocean depends on knowing these temporal and spatial details. Unusually thick, near surface, ice lenses found in firn cores, most likely formed during very large recent melt events signify meltwater refreezing, but may also prevent further infiltration while facilitating runoff. Maps derived from remote sensing show how this runoff flows through an extensive network of supraglacial streams and lakes before it drains into the ice via moulins. Observations of discharge on the ice sheet surface and its margin provide evidence of runoff delays and retention before it is exported to the surrounding oceans. Here, trends and spatial patterns in ice sheet runoff will be examined by using model outputs from the regional surface mass balance model Modèle Atmosphérique Régional and compared with recent remotely sensed and field observations.

  5. Future Changes in Surface Runoff over Korea Projected by a Regional Climate Model under A1B Scenario

    Directory of Open Access Journals (Sweden)

    Ji-Woo Lee

    2014-01-01

    Full Text Available This study assesses future change of surface runoff due to climate change over Korea using a regional climate model (RCM, namely, the Global/Regional Integrated Model System (GRIMs, Regional Model Program (RMP. The RMP is forced by future climate scenario, namely, A1B of Intergovernmental Panel on Climate Change (IPCC Fourth Assessment Report (AR4. The RMP satisfactorily reproduces the observed seasonal mean and variation of surface runoff for the current climate simulation. The distribution of monsoonal precipitation-related runoff is adequately captured by the RMP. In the future (2040–2070 simulation, it is shown that the increasing trend of temperature has significant impacts on the intra-annual runoff variation. The variability of runoff is increased in summer; moreover, the strengthened possibility of extreme occurrence is detected in the future climate. This study indicates that future climate projection, including surface runoff and its variability over Korea, can be adequately addressed on the RMP testbed. Furthermore, this study reflects that global warming affects local hydrological cycle by changing major water budget components. This study adduces that the importance of runoff should not be overlooked in regional climate studies, and more elaborate presentation of fresh-water cycle is needed to close hydrological circulation in RCMs.

  6. Simulation of surface runoff in the Wujiang River watershed based on GIS

    Institute of Scientific and Technical Information of China (English)

    TANG Congguo; LIU Congqiang

    2007-01-01

    Surface runoff in the Wujiang River watershed was simulated by a GIS-based method using precipitation, hydrology data, and land-use data. The volume of surface runoff is chiefly controlled by climates, topographical characteristics and types of land use at the watershed. Five subwatersheds that can represent the whole watershed were chosen and their average annual precipitation, average annual surface runoff and current land use were calculated respectively in the grid model of the Wujiang River watershed based on the climate and hydrology data from 1965 to 2000 and the land-use data acquired in the year of 2000. Surface runoff is assumed to be a function of precipitation and land use and the multiple regression tool is used to determine the relationship between surface runoff, precipitation and present land use. Thus, the rainfall-runoff model for each land-use type has been established. When calibrating these models, the results show that the percent errors are all below 7%, which indicates that the accuracy of this simulation is high.

  7. Characterization of Surface Runoff, Soil Erosion, Nutrient Loss and their relationship for Agricultural plots in India

    Directory of Open Access Journals (Sweden)

    Mohan La

    2015-08-01

    Full Text Available The present study was carried out to explore the existence of relationship among rainfall, runoff, soil loss and nutrient losses from the agricultural plots located at Roorkee, Uttarakhand, India. The natural rainfall generated runoff and soil loss from the 12 agricultural runoff plots (with four land uses namely sugarcane, maize, black gram and fallow land and having slope 5%, 3% and 1% for each land use were recorded during monsoon period (June 2013 to September 2013. The highest grade plot was found to yield the highest magnitude of runoff (i.e. runoff coefficient for a given land use and soil type. The soil loss from the experimental plots of various characteristics shown that for given rainfall input, on average, the plots with sugarcane land use were found to produce high amount of soil loss followed by Maize, fallow land and Blackgram. The nutrients losses were very low in the sediment as compared to the dissolved losses. Nutrients concentrations in sediment and runoff water were found to be more during the critical period. The higher limit of seasonal sediment yield obtained from the present study is lower than soil loss tolerance limit of 2.5 to 12.5 t/ha /yr for Indian subcontinent.

  8. Water Residence Times and Runoff Sources Across an Urbanizing Gradient (Croton Water Supply Area, New York)

    Science.gov (United States)

    Vitvar, T.; Burns, D. A.; Duncan, J. M.; Hassett, J. M.; McDonnell, J. J.

    2002-12-01

    Water residence times and nutrient budgets were measured in 3 small watersheds in the Croton water supply area, NY. The watersheds (less than 1km 2) have different levels of urbanization (natural, semi-developed and fully developed), different mechanisms of runoff generation (quick flow on impervious surfaces and slow flow through the subsurface) and different watershed landscape characteristics (wet zones, hillslopes). Throughfall, stream water, soil water and groundwater in the saturated zone were sampled bi-weekly during a period of up to 2 years and analyzed for major chemical constituents, oxygen-18 content, and nitrogen species. Mean residence times of the stream water of about 30 weeks were estimated using Oxygen-18 and Helium-3/Tritium isotopes for all 3 watersheds. There was no significant difference in mean residence times among the three study watersheds, despite their different levels of urbanization. However, residence times from a few weeks up to ca 2 years vary within the watersheds, depending on the local runoff sources and their geographical conditions (riparian and hillslope topography, aquifer type). The runoff sources were quantified for selected streamwater and groundwater sampling sites using the end member mixing analysis technique (EMMA). The mixing analysis shows the impact of the runoff sources on runoff generation in the selected watersheds, i.e. it shows how big is the impact of urbanization on the runoff generation and how big is the natural control. These results may be useful in watershed management and planning of further urbanization in the Croton water supply area.

  9. A GIS-based Upscaling Estimation of Nutrient Runoff Losses from Rice Paddy Fields to a Regional Level.

    Science.gov (United States)

    Sun, Xiaoxiao; Liang, Xinqiang; Zhang, Feng; Fu, Chaodong

    2016-11-01

    Nutrient runoff losses from cropping fields can lead to nonpoint source pollution; however, the level of nutrient export is difficult to evaluate, particularly at the regional scale. This study aimed to establish a novel yet simple approach for estimating total nitrogen (TN) and total phosphorus (TP) runoff losses from regional paddy fields. In this approach, temporal changes of nutrient concentrations in floodwater were coupled with runoff-processing functions in rice ( L.) fields to calculate nutrient runoff losses for three site-specific field experiments. Validation experiments verified the accuracy of this method. The geographic information system technique was used to upscale and visualize the TN and TP runoff losses from field to regional scales. The results indicated that nutrient runoff losses had significant spatio-temporal variation characteristics during rice seasons, which were positively related to fertilizer rate and precipitation. The average runoff losses over five study seasons were 20.21 kg N ha for TN and 0.76 kg P ha for TP. Scenario analysis showed that TN and TP losses dropped by 7.64 and 3.0%, respectively, for each 10% reduction of fertilizer input. For alternate wetting and drying water management, the corresponding reduction ratio was 24.7 and 14.0% respectively. Our results suggest that, although both water and fertilizer management can mitigate nutrient runoff losses, the former is significantly more effective. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  10. Multi-objective optimization for combined quality-quantity urban runoff control

    Science.gov (United States)

    Oraei Zare, S.; Saghafian, B.; Shamsai, A.

    2012-12-01

    Urban development affects the quantity and quality of urban surface runoff. In recent years, the best management practices (BMPs) concept has been widely promoted for control of both quality and quantity of urban floods. However, means to optimize the BMPs in a conjunctive quantity/quality framework are still under research. In this paper, three objective functions were considered: (1) minimization of the total flood damages, cost of BMP implementation and cost of land-use development; (2) reducing the amount of TSS (total suspended solid) and BOD5 (biological oxygen demand), representing the pollution characteristics, to below the threshold level; and (3) minimizing the total runoff volume. The biological oxygen demand and total suspended solid values were employed as two measures of urban runoff quality. The total surface runoff volume produced by sub-basins was representative of the runoff quantity. The construction and maintenance costs of the BMPs were also estimated based on the local price standards. Urban runoff quantity and quality in the case study watershed were simulated with the Storm Water Management Model (SWMM). The NSGA-II (Non-dominated Sorting Genetic Algorithm II) optimization technique was applied to derive the optimal trade off curve between various objectives. In the proposed structure for the NSGA-II algorithm, a continuous structure and intermediate crossover were used because they perform better as far as the optimization efficiency is concerned. Finally, urban runoff management scenarios were presented based on the optimal trade-off curve using the k-means method. Subsequently, a specific runoff control scenario was proposed to the urban managers.

  11. Glacier surface mass balance and freshwater runoff modeling for the entire Andes Cordillera

    Science.gov (United States)

    Mernild, Sebastian H.; Liston, Glen E.; Yde, Jacob C.

    2017-04-01

    Glacier surface mass balance (SMB) observations for the Andes Cordillera are limited and, therefore, estimates of the SMB contribution from South America to sea-level rise are highly uncertain. Here, we simulate meteorological, snow, glacier surface, and hydrological runoff conditions and trends for the Andes Cordillera (1979/80-2013/14), covering the tropical latitudes in the north down to the sub-polar latitudes in the far south, including the Northern Patagonia Ice Field (NPI) and Southern Patagonia Ice Field (SPI). SnowModel - a fully integrated energy balance, blowing-snow distribution, multi-layer snowpack, and runoff routing model - was used to simulate glacier SMBs for the Andes Cordillera. The Randolph Glacier Inventory and NASA Modern-Era Retrospective Analysis for Research and Applications products, downscaled in SnowModel, allowed us to conduct relatively high-resolution simulations. The simulated glacier SMBs were verified against independent directly-observed and satellite gravimetry and altimetry-derived SMB, indicating a good statistical agreement. For glaciers in the Andes Cordillera, the 35-year mean annual SMB was found to be -1.13 m water equivalent. For both NPI and SPI, the mean SMB was positive (where calving is the likely reason for explaining why geodetic estimates are negative). Further, the spatio-temporal freshwater river runoff patterns from individual basins, including their runoff magnitude and change, were simulated. For the Andes Cordillera rivers draining to the Pacific Ocean, 86% of the simulated runoff originated from rain, 12% from snowmelt, and 2% from ice melt, whereas, for example, for Chile, the water-source distribution was 69, 24, and 7%, respectively. Along the Andes Cordillera, the 35-year mean basin outlet-specific runoff (L s-1 km-2) showed a characteristic regional hourglass shape pattern with highest runoff in both Colombia and Ecuador and in Patagonia, and lowest runoff in the Atacama Desert area.

  12. Multi-objective optimization for combined quality–quantity urban runoff control

    Directory of Open Access Journals (Sweden)

    S. Oraei Zare

    2012-12-01

    Full Text Available Urban development affects the quantity and quality of urban surface runoff. In recent years, the best management practices (BMPs concept has been widely promoted for control of both quality and quantity of urban floods. However, means to optimize the BMPs in a conjunctive quantity/quality framework are still under research. In this paper, three objective functions were considered: (1 minimization of the total flood damages, cost of BMP implementation and cost of land-use development; (2 reducing the amount of TSS (total suspended solid and BOD5 (biological oxygen demand, representing the pollution characteristics, to below the threshold level; and (3 minimizing the total runoff volume. The biological oxygen demand and total suspended solid values were employed as two measures of urban runoff quality. The total surface runoff volume produced by sub-basins was representative of the runoff quantity. The construction and maintenance costs of the BMPs were also estimated based on the local price standards. Urban runoff quantity and quality in the case study watershed were simulated with the Storm Water Management Model (SWMM. The NSGA-II (Non-dominated Sorting Genetic Algorithm II optimization technique was applied to derive the optimal trade off curve between various objectives. In the proposed structure for the NSGA-II algorithm, a continuous structure and intermediate crossover were used because they perform better as far as the optimization efficiency is concerned. Finally, urban runoff management scenarios were presented based on the optimal trade-off curve using the k-means method. Subsequently, a specific runoff control scenario was proposed to the urban managers.

  13. Snowmelt runoff modeling: Limitations and potential for mitigating water disputes

    Science.gov (United States)

    Kult, Jonathan; Choi, Woonsup; Keuser, Anke

    2012-04-01

    SummaryConceptual snowmelt runoff models have proven useful for estimating discharge from remote mountain basins including those spanning the various ranges of the Himalaya. Such models can provide water resource managers with fairly accurate predictions of water availability for operational purposes (e.g. irrigation and hydropower). However, these models have limited ability to address characteristic components of water disputes such as diversions, storage and withholding. Contemporary disputes between India and Pakistan surrounding the snowmelt-derived water resources of the Upper Indus Basin highlight the need for improved water balance accounting methods. We present a research agenda focused on providing refined hydrological contributions to water dispute mitigation efforts.

  14. Spatio-temporal characteristics of the extreme precipitation by L-moment-based index-flood method in the Yangtze River Delta region, China

    Science.gov (United States)

    Yin, Yixing; Chen, Haishan; Xu, Chong-Yu; Xu, Wucheng; Chen, Changchun; Sun, Shanlei

    2016-05-01

    The regionalization methods, which "trade space for time" by pooling information from different locations in the frequency analysis, are efficient tools to enhance the reliability of extreme quantile estimates. This paper aims at improving the understanding of the regional frequency of extreme precipitation by using regionalization methods, and providing scientific background and practical assistance in formulating the regional development strategies for water resources management in one of the most developed and flood-prone regions in China, the Yangtze River Delta (YRD) region. To achieve the main goals, L-moment-based index-flood (LMIF) method, one of the most popular regionalization methods, is used in the regional frequency analysis of extreme precipitation with special attention paid to inter-site dependence and its influence on the accuracy of quantile estimates, which has not been considered by most of the studies using LMIF method. Extensive data screening of stationarity, serial dependence, and inter-site dependence was carried out first. The entire YRD region was then categorized into four homogeneous regions through cluster analysis and homogenous analysis. Based on goodness-of-fit statistic and L-moment ratio diagrams, generalized extreme-value (GEV) and generalized normal (GNO) distributions were identified as the best fitted distributions for most of the sub-regions, and estimated quantiles for each region were obtained. Monte Carlo simulation was used to evaluate the accuracy of the quantile estimates taking inter-site dependence into consideration. The results showed that the root-mean-square errors (RMSEs) were bigger and the 90 % error bounds were wider with inter-site dependence than those without inter-site dependence for both the regional growth curve and quantile curve. The spatial patterns of extreme precipitation with a return period of 100 years were finally obtained which indicated that there are two regions with highest precipitation

  15. 近50年来祁连山及河西走廊极端气温的季节变化特征%Seasonal Characteristics of Extreme Temperature Changes in Qilian Mountains and Hexi Corridor During Last Fifty Years

    Institute of Scientific and Technical Information of China (English)

    贾文雄

    2012-01-01

    Based on daily temperature data of 18 meteorological stations in Qilian Mountains and Hexi Corri- dor from 1960 to 2009, the seasonal characteristics of extreme temperature change were analyzed by methods of linear trend, Morlet wavelet and Mann-Kendall. The results indicate that extreme high temperature days in each season are on the rise significantly, especially increased with larger scales after the middle of 1980s. But that is contrary to extreme low temperature days, which decreased with larger scales after the middle of 1980s in spring and summer, and decreased after the middle and later of 1960s in autumn and winter. The changing scale of extreme temperature days is the largest in winter, and the changes of them are before ten years in win- ter than in other seasons, which indicated that the significant change of extreme temperature days took place in winter firstly. The cycle changes of extreme temperature days in different seasons are different, but they are grouped in 6-10 a, 12-16 a and 18-22 a. The major cycle of extreme high temperature days in spring, summer, autumn and winter are changing respectivelywith 8 a, 14 a, 16 a and 16 a, and that of extreme low temperature days are changing respectively with 14 a, 16 a, 14 a and 6 a. The mutation of extreme high temperature days in spring, summer, autumn and winter increased in 2002, 1997, 1994, 1986, respectively, but that of extreme low temperature days decreased in 2002, 1997, 1987, 1986, respectively. Except autumn, the abrupt changes of ex- treme high temperature days and extreme low temperature days in other seasons are coincident. The response to global warming of extreme temperature days is earlier in autumn and winter than that in spring and summer. The change of extreme temperature days will bring some effect to the Qilian Mountains and Hexi Corridor. The increase of extreme high temperature days will add pressure of preventing fire for forest and grasslands in Qilian Mountains. The decrease of

  16. Runoff production from intercrater plains on Mars

    Science.gov (United States)

    Irwin, R. P., III; Matsubara, Y.; Cawley, J. C.

    2016-12-01

    Ancient fluvial paleochannels and paleolakes constrain the hydrology of a wetter epoch in the early history of Mars. The cross-sectional dimensions of fluvial channels scale with discharge, watershed topography is generally well preserved, and adjustments can be made for gravity. These factors have supported conservative estimates of runoff production during event floods more than 3.5 billion years ago. Assuming weak channel banks, such that discharge is low per unit channel width, event floods in smaller watersheds had estimated runoff production of 1 cm/day. Highland surfaces generated runoff inefficiently, such that channel width increases with only the 0.3 power of watershed area. Inefficient runoff production on Mars is also suggested by new landscape evolution modeling. In long-term simulations that accurately reproduce the present landscape, forming and degrading all of the Middle and Late Noachian impact craters in selected study areas, inefficient runoff production is needed to degrade craters without intensely dissecting intercrater surfaces. The model shows that discharge generally cannot increase at more than the 0.3 power of watershed area. Paleolakes provide useful constraints on paleohydrology over intermediate timescales of years to millennia. Most local highland basins were never integrated into regional drainage systems, but some have both a contributing valley network and an outlet valley, indicating that they overflowed. Paleolake overflows require a medium-term water supply that exceeds losses to evaporation. Reasonable evaporation of 0.1 to 1 m/yr and watersheds that are mostly >10 times the area of overflowed paleolakes suggest runoff production of gardening, and lesser aeolian erosion. Low drainage density is an obvious explanation for inefficient runoff production, but it may be the consequence of moderate rainfall or snowmelt, as well as incision of valley networks over a finite timescale.

  17. 黄土丘陵沟壑区坡地土壤侵蚀与降雨产流关系%Study on the Relationship Between Rainfall Runoff and Soil Erosion of Slopeland in Gullied Rolling Loess Area

    Institute of Scientific and Technical Information of China (English)

    焦金鱼

    2015-01-01

    Based on the data of 27 erosive rainfalls from 2009 to 2012 of four farmland runoff plots in Anjiapo small watershed,this paper analyzed the relationship characteristics of the rainfall runoff and the soil erosion in gullied rolling loess area. The results show that rainfall runoff and soil erosion of cultivated land are proportional to the gradient variables under the same rainfall conditions. The erosive rainfall distributions are extremely uneven and show obvious distribution characteristics of one-peak in flood seasons. Leading to the soil and water loss of farmland rainfall about the runoff level is heavy rain in gullied rolling loess area. Especially,the erosive rainfall in July is the largest. Therefore,July becomes the most critical period to prevent and control the soil erosion of farmland in the gullied rolling loess area.%基于2009—2012年安家坡小流域4个农田径流小区27场侵蚀性降雨的数据资料,分析了黄土丘陵沟壑区降雨产流与土壤侵蚀的关系。结果表明:相同降雨条件下坡耕地降雨产流、土壤侵蚀与坡度成正比;汛期侵蚀性降雨的分布极不均衡,表现出明显的单峰分布特征。造成黄土丘陵沟壑区坡耕地水土流失的产流性雨量级别以大雨为主,其中7月的侵蚀性降雨量最大,成为土壤侵蚀防治的最关键时期。

  18. Long-term Trend and Fractal of Annual Runoff Process in Mainstream of Tarim River

    Institute of Scientific and Technical Information of China (English)

    XU Jianhua; CHEN Yaning; LI Weihong; DONG Shan

    2008-01-01

    Based on the time series data from the Aral hydrological station for the period of 1958-2005, the paper re-veals the long-term trend and fractal of the annual runoff process in the mainstream of the Tarim River by using thewavelet analysis method and the fractal theory. The main conclusions are as follows: 1) From a large time scale pointof view, i.e. the time scale of 16 (24) years, the annual runoff basically shows a slightly decreasing trend as a wholefrom 1958 to 2005. If the time scale is reduced to 8 (23) or 4 (22) years, the annual runoff still displays the basic trendas the large time scale, but it has fluctuated more obviously during the period. 2) The correlation dimension for theannual runoff process is 3.4307, non-integral, which indicates that the process has both fractal and chaotic characteris-tics. The correlation dimension is above 3, which means that at least four independent variables are needed to describethe dynamics of the annual runoff process. 3) The Hurst exponent for the first period (1958-1973) is 0.5036, whichequals 0.5 approximately and indicates that the annual runoff process is in chaos. The Hurst exponents for the second(1974-1989) and third (1990-2005) periods are both greater than 0.50, which indicate that the annual runoff processshowed a long-enduring characteristic in the two periods. The Hurst exponent for the period from 1990 to 2005 indi-cates that the annual runoffwill show a slightly increasing trend in the 16 years after 2005.

  19. Effects of elevated mean and extremely high temperatures on the physio-ecological characteristics of geographically distinctive populations of Cunninghamia lanceolata

    Science.gov (United States)

    Zhou, Ting; Jia, Xiaorong; Liao, Huixuan; Peng, Shijia; Peng, Shaolin

    2016-12-01

    Conventional models for predicting species distribution under global warming scenarios often treat one species as a homogeneous whole. In the present study, we selected Cunninghamia lanceolata (C. lanceolata), a widely distributed species in China, to investigate the physio-ecological responses of five populations under different temperature regimes. The results demonstrate that increased mean temperatures induce increased growth performance among northern populations, which exhibited the greatest germination capacity and largest increase in the overlap between the growth curve and the monthly average temperature. However,tolerance of the southern population to extremely high temperatures was stronger than among the population from the northern region,shown by the best growth and the most stable photosynthetic system of the southern population under extremely high temperature. This result indicates that the growth advantage among northern populations due to increased mean temperatures may be weakened by lower tolerance to extremely high temperatures. This finding is antithetical to the predicted results. The theoretical coupling model constructed here illustrates that the difference in growth between populations at high and low latitudes and altitudes under global warming will decrease because of the frequent occurrence of extremely high temperatures.

  20. Hydrologic sensitivity of flood runoff and inundation: 2011 Thailand floods in the Chao Phraya River basin

    Science.gov (United States)

    Sayama, T.; Tatebe, Y.; Iwami, Y.; Tanaka, S.

    2015-07-01

    The Thailand floods in 2011 caused unprecedented economic damage in the Chao Phraya River basin. To diagnose the flood hazard characteristics, this study analyses the hydrologic sensitivity of flood runoff and inundation to rainfall. The motivation is to address why the seemingly insignificant monsoon rainfall, or 1.2 times more rainfall than for past large floods, including the ones in 1995 and 2006, resulted in such devastating flooding. To quantify the hydrologic sensitivity, this study simulated long-term rainfall-runoff and inundation for the entire river basin (160 000 km2). The simulation suggested that the flood inundation volume was 1.6 times more in 2011 than for the past flood events. Furthermore, the elasticity index suggested that a 1 % increase in rainfall causes a 2.3 % increase in runoff and a 4.2 % increase in flood inundation. This study highlights the importance of sensitivity quantification for a better understanding of flood hazard characteristics; the presented basin-wide rainfall-runoff-inundation simulation was an effective approach to analyse the sensitivity of flood runoff and inundation at the river basin scale.

  1. Towards a comprehensive physically-based rainfall-runoff model

    Directory of Open Access Journals (Sweden)

    Z. Liu

    2002-01-01

    Full Text Available This paper introduces TOPKAPI (TOPographic Kinematic APproximation and Integration, a new physically-based distributed rainfall-runoff model deriving from the integration in space of the kinematic wave model. The TOPKAPI approach transforms the rainfall-runoff and runoff routing processes into three ‘structurally-similar’ non-linear reservoir differential equations describing different hydrological and hydraulic processes. The geometry of the catchment is described by a lattice of cells over which the equations are integrated to lead to a cascade of non-linear reservoirs. The parameter values of the TOPKAPI model are shown to be scale independent and obtainable from digital elevation maps, soil maps and vegetation or land use maps in terms of slope, soil permeability, roughness and topology. It can be shown, under simplifying assumptions, that the non-linear reservoirs aggregate into three reservoir cascades at the basin scale representing the soil, the surface and the drainage network, following the topographic and geomorphologic elements of the catchment, with parameter values which can be estimated directly from the small scale ones. The main advantage of this approach lies in its capability of being applied at increasing spatial scales without losing model and parameter physical interpretation. The model is foreseen to be suitable for land-use and climate change impact assessment; for extreme flood analysis, given the possibility of its extension to ungauged catchments; and last but not least as a promising tool for use with General Circulation Models (GCMs. To demonstrate the quality of the comprehensive distributed/lumped TOPKAPI approach, this paper presents a case study application to the Upper Reno river basin with an area of 1051 km2 based on a DEM grid scale of 200 m. In addition, a real-world case of applying the TOPKAPI model to the Arno river basin, with an area of 8135 km2 and using a DEM grid scale of 1000 m, for the

  2. Establishing temporally and spatially variable soil hydraulic data for use in a runoff simulation in a loess region of the Netherlands

    NARCIS (Netherlands)

    Stolte, J.; Ritsema, C.J.; Veerman, G.J.; Hamminga, W.

    1996-01-01

    Soil hydraulic functions for run-off simulation were collected in catchment areas in a loess region. Each soil horizon was sampled and water retention and hydraulic conductivity characteristics were determined. Run-off generation during standard rain events was quantified by simulation. Based on the

  3. Which resilience of the continental rainfall-runoff chain?

    Science.gov (United States)

    Fraedrich, Klaus

    2015-04-01

    Processes along the continental rainfall-runoff chain are extremely variable over a wide range of time and space scales. A key societal question is the multiscale resilience of this chain. We argue that the adequate framework to tackle this question can be obtained by combining observations (ranging from minutes to decades) and minimalist concepts: (i) Rainfall exhibits 1/f-spectra if presented as binary events (tropics) and extrema world wide increase with duration according to Jennings' scaling law as simulated by a censored first-order autoregressive process representing vertical moisture fluxes. (ii) Runoff volatility (Yangtze) shows data collapse which, linked to an intra-annual 1/f-spectrum, is represented by a single function (Gumbel) not unlike physical systems at criticality, while short and long return times of extremes are Weibull-distributed. (iii) Soil moisture, interpreted by a biased coinflip Ansatz for rainfall events, provides an equation of state to the surface energy and water flux balances comprising Budyko's framework for quasi-stationary watershed analysis. (iv) Vegetation-greenness (NDVI), included as an active tracer extends Budyko's eco-hydrologic state space analysis, supplements the common geographical presentations, and it may be linked to a minimalist biodiversity concept. (v) Finally, attributions of change to external (or climate) and internal (or anthropogenic) causes are determined by eco-hydrologic state space trajectories using surface flux ratios of energy excess (loss by sensible heat over supply by net radiation) versus water excess (loss by discharge over gain by precipitation). Risk-estimates (by GCM-emulators) and possible policy advice mechanisms enter the outlook.

  4. [Runoff and sediment yielding processes on red soil engineering accumulation containing gravels by a simulated rainfall experiment].

    Science.gov (United States)

    Shi, Qian-hua; Wang, Wen-long; Guo, Ming-ming; Bai, Yun; Deng, Li-qiang; Li, Jian-ming; Li, Yao-lin

    2015-09-01

    Engineering accumulation formed in production and construction projects is characterized by unique structure and complex material composition. Characteristics of soil erosion on the engineering accumulation significantly differ from those on farmland. An artificially simulated rainfall experiment was carried out to investigate the effects of rainfall intensity on the processes of runoff and sediment yielding on the engineering accumulation of different gravel contents (0%, 10%, 20% and 30%) in red soil regions. Results showed that the initial time of runoff generation decreased with increases in rainfall intensity and gravel content, the decreased amplitudes being about 48.5%-77.9% and 4.2%-34.2%, respectively. The initial time was found to be a power function of rainfall intensity. Both runoff velocity and runoff rate manifested a trend of first rising and then in a steady state with runoff duration. Rainfall intensity was found to be the main factor influencing runoff velocity and runoff rate, whereas the influence of gravel content was not significant. About 10% of gravel content was determined to be a critical value in the influence of gravel content on runoff volume. For the underlying surface of 10% gravel content, the runoff volume was least at rainfall intensity of 1.0 mm · min(-1) and maximum at rainfall intensity of greater than 1.0 mm · min(-1). The runoff volume in- creased 10%-60% with increase in rainfall intensity. Sediment concentration showed a sharp decline in first 6 min and then in a stable state in rest of time. Influence of rainfall intensity on sediment concentration decreased as gravel content increased. Gravels could reduce sediment yield significantly at rainfall intensity of greater than 1.0 mm · min(-1). Sediment yield was found to be a linear function of rainfall intensity and gravel content.

  5. Climate change and its driving effect on the runoff in the “Three-River Headwaters” region

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shifeng; HUA Dong; MENG Xiujing; ZHANG Yongyong

    2011-01-01

    Based on the precipitation and temperature data of the 12 meteorological stations in the “Three-River Headwaters” region and the observed runoff data of Zhimenda in the headwater sub-region of the Yangtze River,Tangnaihai in the headwater sub-region of the Yellow River and Changdu in the headwater sub-region of the Lancang River during the period 1965-2004,this paper analyses the trends of precipitation,temperature,runoff depth and carries out significance tests by means of Mann-Kendall-Sneyers sequential trend test.Makkink model is applied to calculate the potential evaporation.The runoff model driven by precipitation and potential evaporation is developed and the influence on runoff by climate change is simulated under different scenarios.Results show that during the period 1965-2004 the temperature of the “Three-River Headwaters” region is increasing,the runoff of the three hydrological stations is decreasing and both of them had abrupt changes in 1994,while no significant trend changes happen to the precipitation.The runoff model suggests that the precipitation has a positive effect on the runoff depth,while the potential evaporation plays a negative role.The influence of the potential evaporation on the runoff depth of the Lancang River is found to be the significant in the three rivers; and that of the Yellow River is the least.The result of the scenarios analysis indicates that although the precipitation and the potential evaporation have positive and negative effects on runoff relatively,fluctuated characteristics of individual effect on the runoff depth in specific situations are represented.

  6. Modeling of hydrographs in torrent catchments by use of improved field data and adapted precipitation/runoff models

    Science.gov (United States)

    Kohl, B.; Klebinder, K.; Kirnbauer, R.; Markart, G.

    2009-04-01

    For description of runoff formation in alpine catchments still often simple runoff formulas are used on the one hand. On the other hand many precipitation / runoff models for assessment of runoff characteristics in mesoscale and microscale catchments require detailed input data and some are using algorithms which don't describe runoff processes "process-oriented". This especially applies to lumped and to some conceptual models. Fully distributed models mostly require enormous effort for determining serious catchment description parameters. As a first step into the direction of a time and cost sparing but still process based assessment of runoff development in alpine torrent catchments a two column-procedure has been developed at the BFW in cooperation with university scientists and in cooperation with the Austrian Avalanche and Torrent Control Service and the Bavarian Environmental Agency: 1) Based on the results of about 700 simulations of torrential rain on various soil vegetation complexes and land-use forms in the Eastern Alps a code of practice for assessment of surface runoff coefficients in torrential rain has been developed. By use of three indicator groups (soil conditions, sort and condition of plant cover, way and intensity of land-use / cultivation) runoff coefficients and surface roughness coefficients can be easily attributed to runoff contributing hydrological vegetation units. The big advantage: Dominant infiltration and runoff controlling processes are integrated in the assessed runoff and surface roughness coefficients. The manual is freely available under: http://bfw.ac.at/rz/bfwcms.web?dok=4342 (in German language). 2) The coefficients derived from field studies and/or GIS analysis form input parameters for the precipitation / runoff model ZEMOKOST (The runtime Method of ZEller MOdified by KOhl and STepanek), an MS-EXCEL based calculation tool which can be used with or without GIS-environment. The approach is permanently improved by addition of

  7. Precursors of extreme increments

    CERN Document Server

    Hallerberg, S; Holstein, D; Kantz, H; Hallerberg, Sarah; Altmann, Eduardo G.; Holstein, Detlef; Kantz, Holger

    2006-01-01

    We investigate precursors and predictability of extreme events in time series, which consist in large increments within successive time steps. In order to understand the predictability of this class of extreme events, we study analytically the prediction of extreme increments in AR(1)-processes. The resulting strategies are then applied to predict sudden increases in wind speed recordings. In both cases we evaluate the success of predictions via creating receiver operator characteristics (ROC-plots). Surprisingly, we obtain better ROC-plots for completely uncorrelated Gaussian random numbers than for AR(1)-correlated data. Furthermore, we observe an increase of predictability with increasing event size. Both effects can be understood by using the likelihood ratio as a summary index for smooth ROC-curves.

  8. Application of wavelet transform in runoff sequence analysis

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A wavelet transform is applied to runoff analysis to obtain the composition of the runoff sequence and to forecast future runoff. An observed runoff sequence is firstly decomposed and reconstructed by wavelet transform and its expanding tendency is derived. Then, the runoff sequence is forecasted by the back propagation artificial neural networks (BPANN) and by a wavelet transform combined with BPANN. The earlier researches seldom involve the problem of how to choose wavelet function, which is important and cannot be ignored when the wavelet transform is used. With application of the developed approach to the analysis of runoff sequence, several kinds of wavelet functions have been tested.

  9. Physicochemical conditions and properties of particles in urban runoff and rivers: Implications for runoff pollution.

    Science.gov (United States)

    Wang, Qian; Zhang, Qionghua; Wu, Yaketon; Wang, Xiaochang C

    2017-04-01

    In this study, to gain an improved understanding of the fate and fractionation of particle-bound pollutants, we evaluated the physicochemical conditions and the properties of particles in rainwater, urban runoff, and rivers of Yixing, a city with a large drainage density in the Taihu Lake Basin, China. Road runoff and river samples were collected during the wet and dry seasons in 2015 and 2016. There were significant differences between the physicochemical conditions (pH, oxidation-reduction potential (ORP), and electroconductivity (EC)) of rainwater, runoff, and rivers. The lowest pH and highest ORP values of rainwater provide the optimal conditions for leaching of particle-bound pollutants such as heavy metals. The differences in the physicochemical conditions of the runoff and rivers may contribute to the redistribution of pollutants between particulate and dissolved phases after runoff is discharged into waterways. Runoff and river particles were mainly composed of silt and clay (pollutants and settling ability of particles, which shows that it can be used as an index when monitoring runoff pollution.

  10. Characteristics of mercury-rich and extreme mercury-rich coals in the Donbas Region of Ukraine and Guizhou Province, China

    Energy Technology Data Exchange (ETDEWEB)

    Allan Kolker; Harvey E. Belkin [U.S. Geological Survey, Reston, VA (United States). Eastern Energy Resources Team

    2007-07-01

    Metal-enriched coals are present in the Donets Basin (Donbas), Ukraine, and in Guizhou Province, China, due to interaction, in the geologic past, of mineralizing fluids with coal-bearing sequences. Locally, this has resulted in extreme metal enrichment that poses a potential heath hazard where these coals are collected by local residents and used for domestic purposes. In the Donbas, coals with subppm to ppm mercury contents are produced commercially, whereas coals with tens of ppm mercury were formerly produced as a byproduct of a large-scale mercury extraction operation that remains publicly accessible. In Guizhou Province, small scale non-commercial mines have been worked for coals with extreme concentrations of mercury and arsenic. Commercial coals in Guizhou Province have much lower mercury contents, with average values not appreciably greater than in USA commercial coals. Samples from active Donbas coal mines show a good correlation between mercury content and pyritic sulfur, indicating that mercury occurs primarily as a trace constituent in iron sulfides. In extreme mercury-rich coals, mercury contents are higher than can be accounted for by substitution in iron sulfides, indicating that discrete mercury minerals such as cinnabar, tiemannite, and native mercury, are present. 13 refs., 3 figs.

  11. Characteristics of the spatiotemporal distribution of daily extreme temperature events in China: Minimum temperature records in different climate states against the background of the most probable temperature

    Institute of Scientific and Technical Information of China (English)

    Qian Zhong-Hua; Hu Jing-Guo; Feng Guo-Lin; Cao Yong-Zhong

    2012-01-01

    Based on the skewed function,the most probable temperature is defined and the spatiotemporal distributions of the frequencies and strengths of extreme temperature events in different climate states over China are investigated,where the climate states are referred to as State Ⅰ,State Ⅱ and State Ⅲ,i.e.,the daily minimum temperature records of 1961-1990,1971-2000,and 1981-2009.The results show that in space the frequency of high temperature events in summer decreases clearly in the lower and middle reaches of the Yellow River in State Ⅰ and that low temperature events decrease in northern China in State Ⅱ.In the present state,the frequency of high temperature events increases significantly in most areas over China except the north east,while the frequency of low temperature events decreases mainly in north China and the regions between the Yangtze River and the Yellow River.The distributions of frequencies and strengths of extreme temperature events are consistent in space.The analysis of time evolution of extreme events shows that the occurrence of high temperature events become higher with the change in state,while that of low temperature events decreases.High temperature events are becoming stronger as well and deserve to be paid special attention.

  12. Estimating Subcatchment Runoff Coefficients using Weather Radar and a Downstream Runoff Sensor

    DEFF Research Database (Denmark)

    Ahm, Malte; Thorndahl, Søren Liedtke; Rasmussen, Michael R.;

    2013-01-01

    This paper presents a method for estimating runoff coefficients of urban drainage subcatchments based on a combination of high resolution weather radar data and flow measurements from a downstream runoff sensor. By utilising the spatial variability of the precipitation it is possible to estimate...... the runoff coefficients of the separate subcatchments. The method is demonstrated through a case study of an urban drainage catchment (678 ha) located in the city of Aarhus, Denmark. The study has proven that it is possible to use corresponding measurements of the relative rainfall distribution over...

  13. Water quality of surface runoff and lint yield in cotton under furrow irrigation in Northeast Arkansas.

    Science.gov (United States)

    Adviento-Borbe, M Arlene A; Barnes, Brittany D; Iseyemi, Oluwayinka; Mann, Amanda M; Reba, Michele L; Robertson, William J; Massey, Joseph H; Teague, Tina G

    2017-09-11

    Use of furrow irrigation in row crop production is a common practice through much of the Midsouth US and yet, nutrients can be transported off-site through surface runoff. A field study with cotton (Gossypium hirsutum, L.) was conducted to understand the impact of furrow tillage practices and nitrogen (N) fertilizer placement on characteristics of runoff water quality during the growing season. The experiment was designed as a randomized complete block design with conventional (CT) and conservation furrow tillage (FT) in combination with either urea (URN) broadcast or 32% urea ammonium nitrate (UAN) injected, each applied at 101kgNha(-1). Concentrations of ammonium (NH4-N), nitrate (NO3-N), nitrite (NO2-N), and dissolved phosphorus (P) in irrigation runoff water and lint yields were measured in all treatments. The intensity and chemical form of nutrient losses were primarily controlled by water runoff volume and agronomic practice. Across tillage and fertilizer N treatments, median N concentrations in the runoff were irrigation water and less likely to impair pollution in waterways. Lint yields averaged 1111kgha(-1) and were higher (P-value=0.03) in FT compared to CT treatments. Runoff volumes across irrigation events were greater (P-value=0.02) in CT than FT treatments, which increased NO3-N mass loads in CT treatments (394gNO3-Nha(-1)season(-1)). Nitrate-N concentrations in CT treatments were still low and pose little threat to N contaminations in waterways. The findings support the adoption of conservation practices for furrow tillage and N fertilizer placement that can reduce nutrient runoff losses in furrow irrigation systems. Copyright © 2017. Published by Elsevier B.V.

  14. Transfer of pesticides and copper in a stormwater wetland receiving contaminated runoff from a vineyard catchment

    Science.gov (United States)

    Maillard, E.; Babcsanyi, I.; Payraudeau, S.; Imfeld, G.

    2012-04-01

    Wetlands can collect contaminated runoff from urban and agricultural catchments, and have intrinsic physical, chemical and biological processes useful for mitigating pesticides. However, knowledge about the ability of wetlands to mitigate pesticide mixtures in runoff is currently very limited. Our results show that stormwater wetlands that primarily serve for flood protection can also be effective tools for reducing concentrations and loads of runoff-related pesticides. Concentrations and loads of 20 pesticides and degradation products, as well as copper were continuously recorded during the period of pesticide application (April to September 2009, 2010 and 2011) at the inlet, the outlet and in sediments of a stormwater wetland that collects runoff from a vineyard catchment. Removal rates of dissolved loads ranged from 39% (simazine) to 100% (cymoxanil, gluphosinate, kresoxim methyl and terbuthylazine). Dimethomorph, diuron, glyphosate and metalaxyl were more efficiently removed in spring than in summer. The calculation of sedimentation rates from discharge measurements and total suspended solids (TSS) values revealed that the wetland retained more than 77% of the input mass of suspended solids, underscoring the capability of the wetland to trap pesticide-laden particles. Only flufenoxuron was frequently detected in the wetland sediments. An inter-annual comparison showed that changes in the removal of aminomethylphosphonic acid (AMPA, a degradation product of glyphosate), isoxaben or simazine can be attributed mainly to the larger vegetation cover in 2010 compared to 2009. More than 80% of the copper load entering the wetland was retained in the sediments and the plants. Our results demonstrate that stormwater wetlands can efficiently remove pesticide mixtures and copper in agricultural runoff during critical periods of pesticide application. Nevertheless, fluctuations in the runoff regime, as well as the vegetation and hydrochemical characteristics affect the

  15. Web-based collaborative decision support services for river runoff and flood risk prediction in the Oak Ridge Moraine Area, Canada

    Science.gov (United States)

    Wang, Lei; Cheng, Qiuming

    2006-10-01

    River runoff is highly related to the precipitation events and the land use characteristics. It is an important component in the hydrologic cycle because of its relationship to issues such as flood and water quantity. The Oak Ridge Moraine (ORM) Area, Southern Ontario has always been faced with the impacts of extreme hydrological events. Flood not only has an impact on the ORM economical, social well-being and particularly public safety, but also exacerbates major environmental problems. Prediction of flood is a complex system of which involves variable factors including climate condition, basin attributes, land use/cover types and ground water discharge. The application of flood prediction model requires the efficient management of large spatial and temporal datasets, which involves data acquisition, storage, and processing, as well as manipulation, reporting and display results. The complexity of flood prediction makes it difficult for individual organization to deal effectively with decision-making. Difficulty in linking data, analysis tools and models across organization is one of the barriers to be overcome in developing integrated river runoff and flood risks prediction system. Therefore, it is required to develop a standardized framework for Web-based Collaborative Decision Support Services (WCDSS), supporting information exchange and knowledge and model sharing from different organizations on the web. Such a WCDSS supply both metadata services, geo-data services and geo-processing services to help collaborative decision-making, not only support distributed data sharing and services, but also support distributed model sharing and services. This paper develop a WCDSS that provides a comprehensive environment for on-line river runoff and flood risk prediction, integrating information retrieval, analysis and model analysis for information sharing and decision-making support. Such a SDSS will improve understanding of the environmental, planning and management

  16. Regionalization parameters of conceptual rainfall-runoff model

    Science.gov (United States)

    Osuch, M.

    2003-04-01

    Main goal of this study was to develop techniques for the a priori estimation parameters of hydrological model. Conceptual hydrological model CLIRUN was applied to around 50 catchment in Poland. The size of catchments range from 1 000 to 100 000 km2. The model was calibrated for a number of gauged catchments with different catchment characteristics. The parameters of model were related to different climatic and physical catchment characteristics (topography, land use, vegetation and soil type). The relationships were tested by comparing observed and simulated runoff series from the gauged catchment that were not used in the calibration. The model performance using regional parameters was promising for most of the calibration and validation catchments.

  17. Runoff quality prediction from small urban catchments using SWMM

    Science.gov (United States)

    Tsihrintzis, Vassilios A.; Hamid, Rizwan

    1998-02-01

    The RUNOFF block of EPA's storm water management model (SWMM) was used to simulate the quantity and quality of urban storm water runoff from four relatively small sites (i.e. 5·97-23·56 ha) in South Florida, each with a specific predominant land use (i.e. low density residential, high density residential, highway and commercial). The objectives of the study were to test the applicability of this model in small subtropical urban catchments and provide modellers with a way to select appropriate input parameters to be used in planning studies. A total of 58 storm events, measured by the US Geological Survey (USGS), provided hyetographs, hydrographs and pollutant loadings for biological oxygen demand (BOD5), total suspended solids (TSS), total Kjeldahl nitrogen (TKN) and lead (Pb), and were used for calibration of the model. Several other catchment characteristics, also measured or estimated by USGS, were used in model input preparation. Application of the model was done using the Green-Ampt equation for infiltration loss computation, a pollutant accumulation equation using a power build-up equation dependent on the number of dry days, and a power wash-off equation dependent on the predicted runoff rate. Calibrated quantity input parameters are presented and compared with suggested values in the literature. The impervious depression storage was generally found to be the most sensitive calibration parameter, followed by the Manning's roughness coefficients of conduit and overland flow, the Green-Ampt infiltration parameters and, finally, the pervious depression storage. Calibrated quality input parameters are presented in the form of regression equations, as a function of rainfall depth and the number of antecedent dry days. A total of 16 independent rainfall events were used for verification of the model, which showed a good comparison with observed data for both hydrographs and pollutant loadings. Average model predictions for the four constituent concentrations

  18. Clouds enhance Greenland ice sheet meltwater runoff

    Science.gov (United States)

    Van Tricht, Kristof; Lhermitte, Stef; Lenaerts, Jan T. M.; Gorodetskaya, Irina V.; L'Ecuyer, Tristan S.; Noël, Brice; van den Broeke, Michiel R.; Turner, David D.; van Lipzig, Nicole P. M.

    2016-04-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2) W m-2. Contrary to conventional wisdom, however, the Greenland ice sheet responds to this energy through a new pathway by which clouds reduce meltwater refreezing as opposed to increasing surface melt directly, thereby accelerating bare-ice exposure and enhancing meltwater runoff. The high sensitivity of the Greenland ice sheet to both ice-only and liquid-bearing clouds highlights the need for accurate cloud representations in climate models, to better predict future contributions of the Greenland ice sheet to global sea level rise.

  19. Groundwater Recharge, Evapotranspiration and Surface Runoff ...

    African Journals Online (AJOL)

    Bheema

    Department of Earth Science, CNCS, P.O. Box 231, Mekelle University, ... The mean annual groundwater recharge, evapotranspiration and runoff were ... Accordingly, recharge accounts for 12% of the precipitation .... So, to apply the WetSpass for Illala catchment, input of the meteorological grid map ..... Review of Australian.

  20. Green Roofs for Stormwater Runoff Control

    Science.gov (United States)

    This project evaluated green roofs as a stormwater management tool. Specifically, runoff quantity and quality from green and flat asphalt roofs were compared. Evapotranspiration from planted green roofs and evaporation from unplanted media roofs were also compared. The influence...

  1. water infiltration, conductivity and runoff under fallow

    African Journals Online (AJOL)

    sections of sloping terraces on water infiltration and subsequent runoff on a Haplic ... Infiltration measurements, done by a tension infiltrometer, were conducted under 3-year old tree .... head first avoid hysteresis (Reynolds and Elrick, ..... terrace (60%), perhaps reflecting the influence of ..... Water Resources Research 14:.

  2. Characterization of chromium species in urban runoff

    DEFF Research Database (Denmark)

    Cederkvist, Karin; Jensen, Marina Bergen; Holm, Peter Engelund

    2013-01-01

    Little is known about the presence of the element Cr in its toxic hexavalent form Cr(VI) in stormwater runoff from urban areas. Most studies report only total Cr concentration, i.e., including also the nontoxic Cr(III) molecular form. The objective of this study was to evaluate a field method bas...

  3. Urban Runoff and Combined Sewer Overflow.

    Science.gov (United States)

    Field, Richard; Gardner, Bradford B.

    1978-01-01

    Presents a literature review of wastewater treatment, covering publications of 1976-77. This review includes areas such as: (1) urban runoff quality and quantity; (2) urban hydrology; (3) management practices; and (4) combined sewer overflows. A list of 140 references is also presented. (HM)

  4. Clouds enhance Greenland ice sheet meltwater runoff.

    Science.gov (United States)

    Van Tricht, K; Lhermitte, S; Lenaerts, J T M; Gorodetskaya, I V; L'Ecuyer, T S; Noël, B; van den Broeke, M R; Turner, D D; van Lipzig, N P M

    2016-01-12

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2) W m(-2). Contrary to conventional wisdom, however, the Greenland ice sheet responds to this energy through a new pathway by which clouds reduce meltwater refreezing as opposed to increasing surface melt directly, thereby accelerating bare-ice exposure and enhancing meltwater runoff. The high sensitivity of the Greenland ice sheet to both ice-only and liquid-bearing clouds highlights the need for accurate cloud representations in climate models, to better predict future contributions of the Greenland ice sheet to global sea level rise.

  5. Clouds enhance Greenland ice sheet meltwater runoff

    Science.gov (United States)

    Van Tricht, K.; Lhermitte, S.; Lenaerts, J. T. M.; Gorodetskaya, I. V.; L'Ecuyer, T. S.; Noël, B.; van den Broeke, M. R.; Turner, D. D.; van Lipzig, N. P. M.

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2) W m−2. Contrary to conventional wisdom, however, the Greenland ice sheet responds to this energy through a new pathway by which clouds reduce meltwater refreezing as opposed to increasing surface melt directly, thereby accelerating bare-ice exposure and enhancing meltwater runoff. The high sensitivity of the Greenland ice sheet to both ice-only and liquid-bearing clouds highlights the need for accurate cloud representations in climate models, to better predict future contributions of the Greenland ice sheet to global sea level rise. PMID:26756470

  6. Wetland Purification Pattern for Surface Runoff Pollution of Coastal Highway in Liaoning Province

    Institute of Scientific and Technical Information of China (English)

    Yanbo; ZHAO; Wenzhi; YAN; Hongwei; YAN

    2015-01-01

    Taking surface runoff of Coastal Highway in Liaoning Province as research object,this paper analyzed water quality characteristics of runoff and flow rules of pollutants. It proposed using constructed wetland treatment technique in the drainage system from the perspective of effectively removing major pollutants. Using the constructed wetland k- C* model and relevant experience,parameters of constructed wetland can be obtained. The basic model is as follows: constructed wetland lies in two sides of the road,and surface runoff sewage is collected and treated separately with 1 km road section as the collection unit. The wetland area in one side is 191. 6 m2,average water depth is 0. 5 m,wetland width is 8 m,and wetland length is 24 m.

  7. Surface runoff in the Itaim Watershed

    Directory of Open Access Journals (Sweden)

    Getulio Teixeira Batista

    2007-06-01

    Full Text Available This paper describes a work done in the Itaim watershed at Taubaté, SP, and had the objective of estimating the surface runoff based on the Curve-Number (CN method in area with vegetation cover of grassland (Brachiaria Decumbens, that prevails in this watershed. The surface runoff was estimated using three different methods: 1st values of accumulated Infiltration (IAc obtained in the field were used, considered as the Potential Infiltration (S, which varied from 15.37 mm to 51.88 mm with an average value of 23.46 mm. With those measured infiltration rates and using the maximum precipitation values for Taubaté, SP, with duration time of 3 hours: P = 54.4; 70.3; 80.8; 86.7; 90.9; 94.1 and 103.9 mm, respectively, for the return times, Tr = 2, 5, 10, 15, 25, 50 and 100 years, the following values of surface runoff were generated: 34.83; 49.33; 59.14; 64.71; 68.69; 71.73 and 81.10 mm, respectively; In the 2nd method it was considered that the prevailing vegetation cover of the watershed was Dirty Pasture (Pasture with regrowth of natural vegetation and therefore, a value of CN = 75 was used and generated a potential infiltration, S = 84,7 mm and resulted in surface runoff values that varied from 11 to 44 mm; In the 3rd method, the value of CN was considered equal to 66.57. This value was calculated weighting the contribution of all land use cover classes of the watershed, and as a result a higher value of potential infiltration, S = 127 mm, was obtained. Consequently, the surface runoff values were 5.33; 11.64; 16.72; 19.83; 22.16; 23.98 and 29.83 mm, respectively. Therefore, the comparison with the results obtained by the two Curve-Number methods (conventional and weighted allowed to be concluded that the Curve-Number method applied in a conventional way underestimated the surface runoff in the studied area. However, results indicate that it is possible to use this method for surface runoff estimates as long as adjustments based on potential

  8. MODELING OF STORM WATER RUNOFF FROM GREEN ROOFS

    OpenAIRE

    Ewa Burszta-Adamiak; Wiesław Fiałkiewicz

    2014-01-01

    Apart from direct measurements, modelling of runoff from green roofs is valuable source of information about effectiveness of this type of structure from hydrological point of view. Among different type of models, the most frequently used are numerical models. They allow to assess the impact of green roofs on decrease and attenuation of runoff, reduction of peak runoff and value of water retention. This paper presents preliminary results of research on computing the rate of runoff from green ...

  9. 29 CFR 452.30 - Run-off elections.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 2 2010-07-01 2010-07-01 false Run-off elections. 452.30 Section 452.30 Labor Regulations... OF 1959 Frequency and Kinds of Elections § 452.30 Run-off elections. A run-off election must meet the... example, if the run-off is to be held at the same meeting as the original election, the original notice...

  10. Chlorpyrifos and atrazine removal from runoff by vegetated filter strips: experiments and predictive modeling.

    Science.gov (United States)

    Poletika, N N; Coody, P N; Fox, G A; Sabbagh, G J; Dolder, S C; White, J

    2009-01-01

    Runoff volume and flow concentration are hydrological factors that limit effectiveness of vegetated filter strips (VFS) in removing pesticides from surface runoff. Empirical equations that predict VFS pesticide effectiveness based solely on physical characteristics are insufficient on the event scale because they do not completely account for hydrological processes. This research investigated the effect of drainage area ratio (i.e., the ratio of field area to VFS area) and flow concentration (i.e., uniform versus concentrated flow) on pesticide removal efficiency of a VFS and used these data to provide further field verification of a recently proposed numerical/empirical modeling procedure for predicting removal efficiency under variable flow conditions. Runoff volumes were used to simulate drainage area ratios of 15:1 and 30:1. Flow concentration was investigated based on size of the VFS by applying artificial runoff to 10% of the plot width (i.e., concentrated flow) or the full plot width (i.e., uniform flow). Artificial runoff was metered into 4.6-m long VFS plots for 90 min after a simulated rainfall of 63 mm applied over 2 h. The artificial runoff contained sediment and was dosed with chlorpyrifos and atrazine. Pesticide removal efficiency of VFS for uniform flow conditions (59% infiltration; 88% sediment removal) was 85% for chlorpyrifos and 62% for atrazine. Flow concentration reduced removal efficiencies regardless of drainage area ratio (i.e., 16% infiltration, 31% sediment removal, 21% chlorpyrifos removal, and 12% atrazine removal). Without calibration, the predictive modeling based on the integrated VFSMOD and empirical hydrologic-based pesticide trapping efficiency equation predicted atrazine and chlorpyrifos removal efficiency under uniform and concentrated flow conditions. Consideration for hydrological processes, as opposed to statistical relationships based on buffer physical characteristics, is required to adequately predict VFS pesticide trapping

  11. Current research issues related to post-wildfire runoff and erosion processes

    Science.gov (United States)

    Moody, John A.; Shakesby, Richard A.; Robichaud, Peter R.; Cannon, Susan H.; Martin, Deborah A.

    2013-01-01

    Research into post-wildfire effects began in the United States more than 70 years ago and only later extended to other parts of the world. Post-wildfire responses are typically transient, episodic, variable in space and time, dependent on thresholds, and involve multiple processes measured by different methods. These characteristics tend to hinder research progress, but the large empirical knowledge base amassed in different regions of the world suggests that it should now be possible to synthesize the data and make a substantial improvement in the understanding of post-wildfire runoff and erosion response. Thus, it is important to identify and prioritize the research issues related to post-wildfire runoff and erosion. Priority research issues are the need to: (1) organize and synthesize similarities and differences in post-wildfire responses between different fire-prone regions of the world in order to determine common patterns and generalities that can explain cause and effect relations; (2) identify and quantify functional relations between metrics of fire effects and soil hydraulic properties that will better represent the dynamic and transient conditions after a wildfire; (3) determine the interaction between burned landscapes and temporally and spatially variable meso-scale precipitation, which is often the primary driver of post-wildfire runoff and erosion responses; (4) determine functional relations between precipitation, basin morphology, runoff connectivity, contributing area, surface roughness, depression storage, and soil characteristics required to predict the timing, magnitudes, and duration of floods and debris flows from ungaged burned basins; and (5) develop standard measurement methods that will ensure the collection of uniform and comparable runoff and erosion data. Resolution of these issues will help to improve conceptual and computer models of post-wildfire runoff and erosion processes.

  12. Woody plant encroachment reduces annual runoff and shifts runoff mechanisms in the tallgrass prairie, USA

    Science.gov (United States)

    Qiao, Lei; Zou, Chris B.; Stebler, Elaine; Will, Rodney E.

    2017-06-01

    Woody plant encroachment into semiarid and subhumid rangelands is a global phenomenon with important hydrological implications. Observational and experimental results reported both increases and decreases in annual runoff for encroached watersheds and little is known regarding the underlying runoff generation mechanisms. To systematically study the effect of woody plant encroachment on runoff generation processes, seven experimental watersheds were instrumented in 2010, three on grassland sites and four on adjacent sites that were heavily encroached by eastern redcedar (Juniperus virginiana) in the southern Great Plains, USA. Results showed that the runoff coefficient was 1.4 ± 0.6% in eastern redcedar encroached watersheds, significantly lower than 4.4 ± 0.7% in grassland watersheds for the four water years from 2011 to 2014. Eastern redcedar encroachment resulted in reduction of both surface and subsurface flows and the magnitude of reduction depended on annual precipitation. While there were nearly equal contributions between overland flow and subsurface flow, 87% of the total runoff from grassland watersheds occurred under saturated or nearly saturated soil condition, while 86% of runoff under encroached watersheds was generated under unsaturated soil condition, suggesting a shift from saturation excess overland flow to infiltration excess overland flow. These results permitted reconciliation of observed difference of streamflow responses associated with Juniperus spp. encroachment in the region and provided insights to better predict change in water resources under vegetation changes in subhumid regions of the south-central USA.

  13. Runoff characteristics in flood and dry seasons based on wavelet analysis in the source regions of the Yangtze and Yellow rivers%基于小波分析的江河源区汛期和枯水期径流特征

    Institute of Scientific and Technical Information of China (English)

    BING Longfei; SHAO Quanqin; LIU Jiyuan

    2012-01-01

    @@%By decomposing and reconstructing the runoff information from 1965 to 2007 of the hydrologic stations of Tuotuo River and Zhimenda in the source region of the Yangtze River,and Jimai and Tangnaihai in the source region of the Yellow River with db3 wavelet,runoff of different hydrologic stations tends to be declining in the seasons of spring flood,summer flood and dry ones except for that in Tuotuo River.The declining flood/dry seasons series was summer > spring > dry; while runoff of Tuotuo River was always increasing in different stages from 1965 to 2007 with a higher increase rate in summer flood seasons than that in spring ones.Complex Morlet wavelet was selected to detect runoff periodicity of the four hydrologic stations mentioned above.Over all seasons the periodicity was 11-12 years in the source region of the Yellow River.For the source region of the Yangtze River the periodicity was 4-6 years in the spring flood seasons and 13-14 years in the summer flood seasons.The differences of variations of flow periodicity between the upper catchment areas of the Yellow River and the Yangtze River and between seasons were considered in relation to glacial melt and annual snowfall and rainfall as providers of water for runoff.

  14. Physically based modelling of rainfall-runoff processes

    NARCIS (Netherlands)

    Diermanse, F.L.M.

    2001-01-01

    This PhD. research was set up to investigate the use of rainfall-runoff models for simulation of high water events in hillslope areas. First, dominant parameters for runoff production during high water events have been identified. Subsequently, the influence of antecedent conditions on runoff percen

  15. APPROACHES FOR DETERMINING SWALE PERFORMANCE FOR STORMWATER RUNOFF - Wilmington, NC

    Science.gov (United States)

    Swales are “engineered vegetated ditches” that provide stable routing for stormwater runoff and a low-cost drainage option for highways, farms, industrial sites, and commercial areas. It is reported in the literature that swales mitigate runoff-carried pollutants, reduce runoff ...

  16. APPROACHES FOR DETERMINING SWALE PERFORMANCE FOR STORMWATER RUNOFF

    Science.gov (United States)

    Swales are “engineered vegetated ditches” that provide stable routing for stormwater runoff and a low-cost drainage option for highways, farms, industrial sites, and commercial areas. It is reported in the literature that swales mitigate runoff-carried pollutants, reduce runoff v...

  17. Runoff initiation, soil detachment and connectivity are enhanced as a consequence of vineyards plantations.

    Science.gov (United States)

    Cerdà, A; Keesstra, S D; Rodrigo-Comino, J; Novara, A; Pereira, P; Brevik, E; Giménez-Morera, A; Fernández-Raga, M; Pulido, M; di Prima, S; Jordán, A

    2017-11-01

    Rainfall-induced soil erosion is a major threat, especially in agricultural soils. In the Mediterranean belt, vineyards are affected by high soil loss rates, leading to land degradation. Plantation of new vines is carried out after deep ploughing, use of heavy machinery, wheel traffic, and trampling. Those works result in soil physical properties changes and contribute to enhanced runoff rates and increased soil erosion rates. The objective of this paper is to assess the impact of the plantation of vineyards on soil hydrological and erosional response under low frequency - high magnitude rainfall events, the ones that under the Mediterranean climatic conditions trigger extreme soil erosion rates. We determined time to ponding, Tp; time to runoff, Tr; time to runoff outlet, Tro; runoff rate, and soil loss under simulated rainfall (55 mm h(-1), 1 h) at plot scale (0.25 m(2)) to characterize the runoff initiation and sediment detachment. In recent vine plantations (50 years; O). Slope gradient, rock fragment cover, soil surface roughness, bulk density, soil organic matter content, soil water content and plant cover were determined. Plantation of new vineyards largely impacted runoff rates and soil erosion risk at plot scale in the short term. Tp, Tr and Tro were much shorter in R plots. Tr-Tp and Tro-Tr periods were used as connectivity indexes of water flow, and decreased to 77.5 and 33.2% in R plots compared to O plots. Runoff coefficients increased significantly from O (42.94%) to R plots (71.92%) and soil losses were approximately one order of magnitude lower (1.8 and 12.6 Mg ha(-1) h(-1) for O and R plots respectively). Soil surface roughness and bulk density are two key factors that determine the increase in connectivity of flows and sediments in recently planted vineyards. Our results confirm that plantation of new vineyards strongly contributes to runoff initiation and sediment detachment, and those findings confirms that soil erosion control strategies

  18. [Treatment of Urban Runoff Pollutants by a Multilayer Biofiltration System].

    Science.gov (United States)

    Wang, Xiao-lu; Zuo, Jian-e; Gan, Li-li; Xing, Wei; Miao, Heng-feng; Ruan, Wen-quan

    2015-07-01

    In order to control the non-point source pollution from road runoff in Wuxi City effectively, a multilayer biofiltration system was designed to remove a variety of pollutants according to the characteristics of road runoff in Wuxi, and the experimental research was carried out to study the effect on rainwater pollution purification. The results show that the system has a good performance on removing suspended solids (SS), organic pollutant (COD), nitrogen and phosphorus: all types of multilayer biofiltration systems have a high removal rate for SS, which can reach 90%. The system with activated carbon (GAC) has higher removal rates for COD and phosphorus. The system with zeolite (ZFM) has a relatively better removal efficiency for nitrogen. The addition of wood chips in the system can significantly improve the system efficiency for nitrogen removal. Between the two configurations of layered and distributed wood chips, configurations of distributed wood chips reach higher COD, phosphorus and nitrogen pollutants removal efficiencies since they can reduce the release of wood chips dissolution.

  19. Impact of the rainfall pattern on synthetic pesticides and copper runoff from a vineyard catchment

    Science.gov (United States)

    Payraudeau, Sylvain; Meite, Fatima; Wiegert, Charline; Imfeld, Gwenaël

    2017-04-01

    Runoff is a major process of pesticide transport from agricultural land to downstream aquatic ecosystems. The impact of rainfall characteristics on the transport of runoff-related pesticide is rarely evaluated at the catchment scale. Here, we evaluate the influence of rainfall pattern on the mobilization of synthetic pesticides and copper fungicides in runoff from a small vineyard catchment, both at the plot and catchment scales. During two vineyard growing seasons in 2015 and 2016 (from March to October), we monitored rainfall, runoff, and concentrations of copper and 20 fungicides and herbicides applied by winegrowers at the Rouffach vineyard catchment (France, Alsace; 42.5 ha). Rainfall data were recorded within the catchment while runoff measurement and flow-proportional water sampling were carried out at the outlet of the plot (1486 m2; 87.5 × 17 m) and the catchment. In total, discharges of the 14 runoff events were continuously monitored between March and October 2015 using bubbler flow modules combined with Venturi channels. Detailed and distributed dataset on pesticide applications were extracted from survey (copper formulations and type of pesticides, amount and application dates). Pools of copper and synthetic pesticides were quantified weekly in the topsoil (0-3 cm) by systematic sampling across the catchment. The concentrations of copper (10 mg.kg-1 dried soil) and synthetic pesticides (close to the quantification limit, i.e. 0.05 µg.L-1) available in the top soil for off-site transport largely differed over time. Between March and October, an accumulation of copper of 10% was observed in the top-soil while pesticide concentration decreased below the quantification limits after a few days or weeks following application, depending of the compounds. The average runoff generated at the plot scale was very low (0.13% ± 0.30). The maximum runoff reached 1.37% during the storm of July 22, 2015. Synthetic pesticides exported by runoff was less than 1‰ of

  20. Transient runoff-runon model for a 1-D slope with random infiltrability: flow statistics and connectivity

    Science.gov (United States)

    Harel, Marie-Alice; Mouche, Emmanuel

    2015-04-01

    Despite the recent research focused on runoff pattern connectivity in hydrology, there is a surprising lack of theoretical knowledge regarding hillslope runoff generation and dynamics during a rainfall event. The transient problem is especially unaddressed. In this paper we propose a model based on queueing theory formalism for the infiltration-excess overland flow generation on soils with random infiltration properties. The influence of rainfall intensity and duration on runoff dynamics and connectivity is studied thanks to this model, numerical simulation and available steady-state results. We limit our study to a rainfall intensity that is a rectangular function of time. Exact solutions for the case of spatially random exponential distributions of soil infiltrability and rainfall intensity are developed. Simulations validate these analytical results and allow for the study the rising and recession limbs of the hydrograph for different rainfall characteristics. The case of a deterministic uniform rainfall rate and different infiltrability distributions is also discussed in light of runoff connectivity. We show that the connectivity framework contributes to a better understanding and prediction of runoff pattern formation and evolution with time. A fragmented overland flow is shown to have shorter charge and discharge periods after the onset and offset of rainfall compared to well connected runoff fields. These results demonstrate that the transient regime characteristics are linked with connectivity parameters, rainstorm properties and scale issues.

  1. 大学生极端心理危机的心理特征分析%Analysis of Psychological Characteristics of College Stu-dents' Extreme Psychological Crisis

    Institute of Scientific and Technical Information of China (English)

    刘锟

    2014-01-01

    Students' cruel extreme psychological crisis events have occurred, which have brought serious harm to the individ-ual, family, school, society. This study attempts to study psy-chological characteristics of cognition, emotion, motivation, the character of university students in terms of extreme psychologi-cal crisis of college students, and provide basis for the study of prevention of extreme psychological crisis and coping strate-gies.%大学生残忍的极端心理危机事件时有发生,给个人、家庭、学校、社会带来了严重的危害。本研究试图通过认知、情感、动机、性格等角度分析大学生极端心理危机的心理特征,为大学生极端心理危机的预防及应对策略提供研究基础。

  2. Modeling runoff and erosion risk in a~small steep cultivated watershed using different data sources: from on-site measurements to farmers' perceptions

    Science.gov (United States)

    Auvet, B.; Lidon, B.; Kartiwa, B.; Le Bissonnais, Y.; Poussin, J.-C.

    2015-09-01

    This paper presents an approach to model runoff and erosion risk in a context of data scarcity, whereas the majority of available models require large quantities of physical data that are frequently not accessible. To overcome this problem, our approach uses different sources of data, particularly on agricultural practices (tillage and land cover) and farmers' perceptions of runoff and erosion. The model was developed on a small (5 ha) cultivated watershed characterized by extreme conditions (slopes of up to 55 %, extreme rainfall events) on the Merapi volcano in Indonesia. Runoff was modelled using two versions of STREAM. First, a lumped version was used to determine the global parameters of the watershed. Second, a distributed version used three parameters for the production of runoff (slope, land cover and roughness), a precise DEM, and the position of waterways for runoff distribution. This information was derived from field observations and interviews with farmers. Both surface runoff models accurately reproduced runoff at the outlet. However, the distributed model (Nash-Sutcliffe = 0.94) was more accurate than the adjusted lumped model (N-S = 0.85), especially for the smallest and biggest runoff events, and produced accurate spatial distribution of runoff production and concentration. Different types of erosion processes (landslides, linear inter-ridge erosion, linear erosion in main waterways) were modelled as a combination of a hazard map (the spatial distribution of runoff/infiltration volume provided by the distributed model), and a susceptibility map combining slope, land cover and tillage, derived from in situ observations and interviews with farmers. Each erosion risk map gives a spatial representation of the different erosion processes including risk intensities and frequencies that were validated by the farmers and by in situ observations. Maps of erosion risk confirmed the impact of the concentration of runoff, the high susceptibility of long steep

  3. Glacier melt buffers river runoff in the Pamir Mountains

    Science.gov (United States)

    Pohl, Eric; Gloaguen, Richard; Andermann, Christoff; Knoche, Malte

    2017-03-01

    Newly developed approaches based on satellite altimetry and gravity measurements provide promising results on glacier dynamics in the Pamir-Himalaya but cannot resolve short-term natural variability at regional and finer scale. We contribute to the ongoing debate by upscaling a hydrological model that we calibrated for the central Pamir. The model resolves the spatiotemporal variability in runoff over the entire catchment domain with high efficiency. We provide relevant information about individual components of the hydrological cycle and quantify short-term hydrological variability. For validation, we compare the modeled total water storages (TWS) with GRACE (Gravity Recovery and Climate Experiment) data with a very good agreement where GRACE uncertainties are low. The approach exemplifies the potential of GRACE for validating even regional scale hydrological applications in remote and hard to access mountain regions. We use modeled time series of individual hydrological components to characterize the effect of climate variability on the hydrological cycle. We demonstrate that glaciers play a twofold role by providing roughly 35% of the annual runoff of the Panj River basin and by effectively buffering runoff both during very wet and very dry years. The modeled glacier mass balance (GMB) of -0.52 m w.e. yr-1 (2002-2013) for the entire catchment suggests significant reduction of most Pamiri glaciers by the end of this century. The loss of glaciers and their buffer functionality in wet and dry years could not only result in reduced water availability and increase the regional instability, but also increase flood and drought hazards.Plain Language SummaryGlaciers store large amounts of water in the form of ice. They grow and shrink dominantly in response to climatic conditions. In Central Asia, where rivers originate in the high mountains, glaciers are an important source for sustainable water availability. Thus, understanding the link between climate, hydrology, and

  4. Event-based rainfall-runoff modelling of the Kelantan River Basin

    Science.gov (United States)

    Basarudin, Z.; Adnan, N. A.; Latif, A. R. A.; Tahir, W.; Syafiqah, N.

    2014-02-01

    Flood is one of the most common natural disasters in Malaysia. According to hydrologists there are many causes that contribute to flood events. The two most dominant factors are the meteorology factor (i.e climate change) and change in land use. These two factors contributed to floods in recent decade especially in the monsoonal catchment such as Malaysia. This paper intends to quantify the influence of rainfall during extreme rainfall events on the hydrological model in the Kelantan River catchment. Therefore, two dynamic inputs were used in the study: rainfall and river discharge. The extreme flood events in 2008 and 2004 were compared based on rainfall data for both years. The events were modeled via a semi-distributed HEC-HMS hydrological model. Land use change was not incorporated in the study because the study only tries to quantify rainfall changes during these two events to simulate the discharge and runoff value. Therefore, the land use data representing the year 2004 were used as inputs in the 2008 runoff model. The study managed to demonstrate that rainfall change has a significant impact to determine the peak discharge and runoff depth for the study area.

  5. Influence of vegetation, soil and antecedent soil moisture on the variability of surface runoff coefficients at the plot scale in the eastern alps

    Science.gov (United States)

    Chifflard, P.; Kohl, B.; Markart, G.; Kirnbauer, R.

    2009-04-01

    Modelling the runoff of a catchment in a high spatial resolution, you need to know the potential of a single plot to generate surface runoff. The portion of surface runoff is highly significant for storm runoff events, accordingly, it mainly forms the hydrograph. In this study, the influence of vegetation, soil features and antecedent soil moisture on generating surface runoff at the plot scale have been analysed. To achieve an appropriate fit of the plots, a plot sizes between 50 and 400 m² were chosen. The rainfall intensities ranged between 10 mm/h and 100 mm/h. Based on 260 rain simulations with a transportable sprinkling instrumentation on representative plots in the eastern Alps (Austria, Italy, Germany), including investigations on land-use, vegetation cover and soil physical characteristics, various soil-vegetation complexes and their surface runoff processes have been be analysed. Additionally, we investigated flow paths, travel distance, infiltration hindrance, flow resistance and overland flow velocity. The soil water status was monitored by using TDR-probes, which had been installed in two profiles within the plot in different depths ranging from 5 cm to 40 cm. For every sprinkling experiment, a surface runoff coefficient was calculated as the ratio between total rainfall amount and surface runoff. With this substantial dataset, the regression analysis was used to examine the influence of the hydrological key factors as soil, vegetation and initial soil moisture condition on the distribution functions of the surface runoff coefficient. The first results show that the vegetation cover is very important for the surface runoff. If initial soils are covered by alpine or sub-alpine pioneering vegetation surface runoff can be found very scarce. If these initial soils are covered i.e. by subalpine nardus grasslands the surface runoff coefficients range from 0.1 up to 0.8. On the other hand it can be shown that soils with a high bulk density mainly generate

  6. Comparing flow duration curve and rainfall-runoff modelling for predicting daily runoff in ungauged catchments

    Science.gov (United States)

    Zhang, Yongqiang; Vaze, Jai; Chiew, Francis H. S.; Li, Ming

    2015-06-01

    Predicting daily runoff time series in ungauged catchments is both important and challenging. For the last few decades, the rainfall-runoff (RR) modelling approach has been the method of choice. There have been very few studies reported in literature which attempt to use flow duration curve (FDC) to predict daily runoff time series. This study comprehensively compares the two approaches using an extensive dataset (228 catchments) for a large region of south-eastern Australia and provides guidelines for choosing the suitable method. For each approach we used the nearest neighbour method and two weightings - a 5-donor simple mathematical average (SA) and a 5-donor inverse-distance weighting (5-IDW) - to predict daily runoff time series. The results show that 5-IDW was noticeably better than a single donor to predict daily runoff time series, especially for the FDC approach. The RR modelling approach calibrated against daily runoff outperformed the FDC approach for predicting high flows. The FDC approach was better at predicting medium to low flows in traditional calibration against the Nash-Sutcliffe-Efficiency or Root Mean Square Error, but when calibrated against a low flow objective function, both the FDC and rainfall-runoff models performed equally well in simulating the low flows. These results indicate that both methods can be further improved to simulate daily hydrographs describing the range of flow metrics in ungauged catchments. Further studies should be carried out for improving the accuracy of predicted FDC in ungauged catchments, including improving the FDC model structure and parameter fitting.

  7. Runoff production on a slope with randomly distributed infiltrabilities

    Science.gov (United States)

    Mouche, E.; Harel, M.

    2013-12-01

    Runoff generated on one- and two-dimensional slopes with randomly distributed infiltrability is studied in the queuing theory and connectivity frameworks. The equivalence between the runoff-runon equation and the customers waiting time in a single server queue provides a theoretical link between the statistical descriptions of infiltrability and that of runoff flow rate. Different distributions of infiltrability, representing soil heterogeneities at different scales, are considered. Numerical simulations validate these results and improve our understanding of runoff-runon process. All of the quantities describing the generation of runoff (runoff one-point statistics) and its organization into patterns (patterns statistics and connectivity) are studied as functions of rainfall rate and runoff dimensionality.

  8. Characterizing dry deposition of mercury in urban runoff

    Science.gov (United States)

    Fulkerson, M.; Nnadi, F.N.; Chasar, L.S.

    2007-01-01

    Stormwater runoff from urban surfaces often contains elevated levels of toxic metals. When discharged directly into water bodies, these pollutants degrade water quality and impact aquatic life and human health. In this study, the composition of impervious surface runoff and associated rainfall was investigated for several storm events at an urban site in Orlando, Florida. Total mercury in runoff consisted of 58% particulate and 42% filtered forms. Concentration comparisons at the start and end of runoff events indicate that about 85% of particulate total mercury and 93% of particulate methylmercury were removed from the surface before runoff ended. Filtered mercury concentrations showed less than 50% reduction of both total and methylmercury from first flush to final flush. Direct comparison between rainfall and runoff at this urban site indicates dry deposition accounted for 22% of total inorganic mercury in runoff. ?? 2007 Springer Science+Business Media B.V.

  9. RUNOFF POTENTIAL OF MUREŞ RIVER UPPER BASIN TRIBUTARIES

    Directory of Open Access Journals (Sweden)

    V. SOROCOVSCHI

    2012-03-01

    Full Text Available Runoff Potential of Mureş River Upper Basin Tributaries. The upper basin of the Mureş River includes a significant area of the Eastern Carpathians central western part with different runoff formation conditions. In assessing the average annual runoff potential we used data from six gauging stations and made assessments on three distinct periods. Identifying the appropriate areas of the obtained correlations curves (between specific average runoff and catchments mean altitude allowed the assessment of potential runoff at catchment level and on geographical units. The potential average runoff is also assessed on altitude intervals of the mentioned areas. The runoff potential analysis on hydrographic basins, geographical units and altitude intervals highlights the variant spatial distribution of this general water resources indicator in the different studied areas.

  10. Runoff generation through ephemeral streams in south-east Italy

    Science.gov (United States)

    Doglioni, A.; Simeone, V.; Giustolisi, O.

    2012-04-01

    Ephemeral streams are morphological elements, typical of karst areas, characterized by relatively large and flat bottom transects (Camarasa & Tilford, 2002). These occasionally drain runoff generated by extreme rainfall events, characterized by high return periods. The activation of these streams was investigated by several authors for the Mediterranean regions, and in particular for south Spain and north Africa (Camarasa & Segura, 2001; De Vera, 1984). However, there are few analyses for karst areas of south-east of Italy (Cotecchia, 2006; Polemio, 2010). South-east of Italy, in particular the central part of Apulia, is characterized by a karst morphology, with a moderately elevated plateau, namely Murgia, which is drained by a network of ephemeral streams. These are normally dry, relatively short-length and straights, and their main outlets are on the coast. They normally drain water after extraordinary rainfall events, which can generate very high discharges, which can potentially flood the areas close to the streams. For this reason, the definition of an activation threshold for ephemeral streams is a paramount problem, even if this constitutes a complex problem, since the dynamics of the catchment drained by these streams in highly non-linear and biased by multiple variables (e.g. urbanization, land use, etc.). The main problem affecting the analysis and prediction of flood events in karst semi-arid regions is the almost complete absence of discharge time-series, measured at the outlets of the ephemeral streams. This prevents from the identification of accurate statistics of flood events and on the determination of rainfall events, which may potentially generate floods. Indeed, floods and in general flash floods are relatively rare events for semi-arid karst regions, however they can be really severe and disruptive, causing serious damages to people and infrastructures. This work presents an analysis of the ephemeral stream activation in karst semi-arid areas

  11. Comparing the Selected Transfer Functions and Local Optimization Methods for Neural Network Flood Runoff Forecast

    Directory of Open Access Journals (Sweden)

    Petr Maca

    2014-01-01

    Full Text Available The presented paper aims to analyze the influence of the selection of transfer function and training algorithms on neural network flood runoff forecast. Nine of the most significant flood events, caused by the extreme rainfall, were selected from 10 years of measurement on small headwater catchment in the Czech Republic, and flood runoff forecast was investigated using the extensive set of multilayer perceptrons with one hidden layer of neurons. The analyzed artificial neural network models with 11 different activation functions in hidden layer were trained using 7 local optimization algorithms. The results show that the Levenberg-Marquardt algorithm was superior compared to the remaining tested local optimization methods. When comparing the 11 nonlinear transfer functions, used in hidden layer neurons, the RootSig function was superior compared to the rest of analyzed activation functions.

  12. Characterising water balance dynamics and different runoff components in a poorly gauged tropical catchment, Nicaragua

    Science.gov (United States)

    Calderon, Heyddy; Uhlenbrook, Stefan

    2014-05-01

    The water balance dynamics, groundwater flow systems and the runoff components of a tropical forested small catchment (46 km2) is the southwestern Pacific coast of Nicaragua were studied by a combination of hydrometry (observation of rainfall, runoff, evaporation and groundwater levels), geological characterisation (hydrogeological mapping, flow systems, characterization and Piper diagrams) and hydrochemical and isotopic tracers (chemograph analysis, 2- and 3-component hydrograph separation, discharge-hydrochemical hysteresis effects, and MWL). Although some methods can be considered standard in runoff generation research in temperate climate regions; to the best of our knowledge, this is one of the few studies that used the combination of these techniques in a tropical catchment of Central America. Runoff components were studied at different spatial and temporal scales, finding that different sources and temporal contributions are controlled by geology, catchment size, and dominant landscape elements. Two major groundwater flow systems were identified with different chemical and isotopic characteristics. Indication of moisture recycling in the upper catchment area was found based on d-excess analysis. Runoff components were studied at different spatial and temporal scales, demonstrating that different sources and temporal contributions are controlled by dominant landscape elements and precipitation distribution. Evidence of strong river-aquifer interactions in the lower part of the catchment was found. The results provide an in-depth understanding of the surface and groundwater contributions to stream flow and its temporal and spatial distribution, which indicate the importance of runoff generation areas upstream in the catchment and also the vulnerability of the alluvial aquifer to contamination. This provides the basis to develop realistic, evidence-based water management plans for this developing region.

  13. Influence of land development on stormwater runoff from a mixed land use and land cover catchment.

    Science.gov (United States)

    Paule-Mercado, M A; Lee, B Y; Memon, S A; Umer, S R; Salim, I; Lee, C-H

    2017-12-01

    Mitigating for the negative impacts of stormwater runoff is becoming a concern due to increased land development. Understanding how land development influences stormwater runoff is essential for sustainably managing water resources. In recent years, aggregate low impact development-best management practices (LID-BMPs) have been implemented to reduce the negative impacts of stormwater runoff on receiving water bodies. This study used an integrated approach to determine the influence of land development and assess the ecological benefits of four aggregate LID-BMPs in stormwater runoff from a mixed land use and land cover (LULC) catchment with ongoing land development. It used data from 2011 to 2015 that monitored 41 storm events and monthly LULC, and a Personalized Computer Storm Water Management Model (PCSWMM). The four aggregate LID-BMPs are: ecological (S1), utilizing pervious covers (S2), and multi-control (S3) and (S4). These LID-BMPs were designed and distributed in the study area based on catchment characteristics, cost, and effectiveness. PCSWMM was used to simulate the monitored storm events from 2014 (calibration: R(2) and NSE>0.5; RMSE 0.5; RMSE land and impervious cover, soil alteration, and high amount of precipitation influenced the stormwater runoff variability during different phases of land development. The four aggregate LID-BMPs reduced runoff volume (34%-61%), peak flow (6%-19%), and pollutant concentrations (53%-83%). The results of this study, in addition to supporting local LULC planning and land development activities, also could be applied to input data for empirical modeling, and designing sustainable stormwater management guidelines and monitoring strategies. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Fate of endogenous steroid hormones in steer feedlots under simulated rainfall-induced runoff.

    Science.gov (United States)

    Mansell, D Scott; Bryson, Reid J; Harter, Thomas; Webster, Jackson P; Kolodziej, Edward P; Sedlak, David L

    2011-10-15

    Steroid hormones pose potential risks to fish and other aquatic organisms at extremely low concentrations. To assess the factors affecting the release of endogenous estrogenic and androgenic steroids from feedlots during rainfall, runoff, and soil samples were collected after simulated rainfall on a 14-steer feedlot under different rainfall rates and aging periods and analyzed for six steroid hormones. While only 17α-estradiol, testosterone, and progesterone were detected in fresh manure, 17β-estradiol, estrone, and androstenedione were present in the surficial soil after two weeks. In the feedlot surficial soil, concentrations of 17α-estradiol decreased by approximately 25% accompanied by an equivalent increase in estrone and 17β-estradiol. Aging of the feedlot soils for an additional 7 days had no effect on estrogen and testosterone concentrations, but androstenedione concentrations decreased substantially, and progesterone concentrations increased. Androstenedione and progesterone concentrations in the surficial soil were much higher than could be accounted for by excretion or conversion from testosterone, suggesting that other potential precursors, such as sterols, were converted after excretion. The concentration of androgens and progesterone in the soil were approximately 85% lower after simulated rainfall, but the estrogen concentrations remained approximately constant. The decreased masses could not be accounted for by runoff, suggesting the possibility of rapid microbial transformation upon wetting. All six steroids in the runoff, with the exception of 17β-estradiol, were detected in both the filtered and particle-associated phases at concentrations well above thresholds for biological responses. Runoff from the aged plots contained less 17α-estradiol and testosterone, but more estrone, androstenedione, and progesterone relative to the runoff from the unaged plots, and most of the steroids had a lower particle-associated fraction.

  15. SIZE AND SHAPE FACTOR EXTREMES OF SPHEROIDS

    Directory of Open Access Journals (Sweden)

    Daniel Hlubinka

    2011-05-01

    Full Text Available In the paper we consider random prolate (oblate spheroids and their random profiles. The limiting distribution of the extremal characteristics of the spheroids is related to the limiting distribution of the corresponding extremal characteristics of the profiles. The difference between the analysis of the prolate and oblate spheroids is discussed. We propose the possible application of the theoretical results.

  16. HYDROSCAPE: A SCAlable and ParallelizablE Rainfall Runoff Model for Hydrological Applications

    Science.gov (United States)

    Piccolroaz, S.; Di Lazzaro, M.; Zarlenga, A.; Majone, B.; Bellin, A.; Fiori, A.

    2015-12-01

    In this work we present HYDROSCAPE, an innovative streamflow routing method based on the travel time approach, and modeled through a fine-scale geomorphological description of hydrological flow paths. The model is designed aimed at being easily coupled with weather forecast or climate models providing the hydrological forcing, and at the same time preserving the geomorphological dispersion of the river network, which is kept unchanged independently on the grid size of rainfall input. This makes HYDROSCAPE particularly suitable for multi-scale applications, ranging from medium size catchments up to the continental scale, and to investigate the effects of extreme rainfall events that require an accurate description of basin response timing. Key feature of the model is its computational efficiency, which allows performing a large number of simulations for sensitivity/uncertainty analyses in a Monte Carlo framework. Further, the model is highly parsimonious, involving the calibration of only three parameters: one defining the residence time of hillslope response, one for channel velocity, and a multiplicative factor accounting for uncertainties in the identification of the potential maximum soil moisture retention in the SCS-CN method. HYDROSCAPE is designed with a simple and flexible modular structure, which makes it particularly prone to massive parallelization, customization according to the specific user needs and preferences (e.g., rainfall-runoff model), and continuous development and improvement. Finally, the possibility to specify the desired computational time step and evaluate streamflow at any location in the domain, makes HYDROSCAPE an attractive tool for many hydrological applications, and a valuable alternative to more complex and highly parametrized large scale hydrological models. Together with model development and features, we present an application to the Upper Tiber River basin (Italy), providing a practical example of model performance and

  17. 北京1960-2008年气候变暖及极端气温指数变化特征%Characteristics of Climate Warming and Extreme Temperature Indices in Beijing over 1960-2008

    Institute of Scientific and Technical Information of China (English)

    郑祚芳; 丁海燕; 范水勇

    2011-01-01

    应用均一化逐日气象观测资料,分析了北京地区1960-2008年气候变暖及主要极端气温指数的统计特征.结果表明:近49年来北京年平均气温增温速率约为0.39℃/10a,最高,最低气温变化具有明显的非对称性.霜冻日数和气温年较差呈现下降趋势,暖夜指数及热浪指数呈现上升趋势,除气温年较差外,其他极端气温指数的气候变率均在加大.北京年平均气温及极端气温指数主要存在21年、15~17年及准10年周期特征.年平均气温与极端气温指数之间存在较强相关性,气候变暖突变发生前后某些极端气温指数发生频率表现出明显差异.自1980年起,北京市区极端最高气温及其增温率明显高于近郊和远郊,高温日数市区多于近郊,近郊多于远郊,近、远郊极端最低气温温差高于城、近郊温差.%Using the homogenized temperature data series in the period 1960-2008, the characteristics of climate warming and variations of extreme temperature indices in Beijing were analyzed.Results indicate that the increase rate of annual mean temperature were 0.39℃/10a, and the mean maximum and minimum temperatures changed asymmetrically, indicating that the climate warming were mainly caused by minimum temperature increasing.The climate base state indices of frost days (FD) and extreme temperature range (ETR) declined, warm nights (TN90) and heat wave duration index (HWDI) increased, and most of extreme temperature indices exhibited high variability except for the ETR index.Morlet wavelet transform shows that the main periods for mean annual temperature and extreme temperature indices were about 21, 15-17, and 10 years.There were a close correlation between annual mean temperature and extreme temperature indices.Since 1980, extreme high temperature, and high temperature days have increased more in urban areas than in suburbs and exurbs, while extreme low temperature and low temperature days have decreased more in

  18. 胃肠外科围手术期下肢深静脉血栓形成的临床分析%Clinical characteristics and risk factors of deep venous thrombosis of lower extremities in patients of gastrointestinal surgery

    Institute of Scientific and Technical Information of China (English)

    郜永顺; 黄晶晶; 陈鹏; 张云飞; 闫西忠; 孙建刚

    2016-01-01

    Objective To study the clinical characteristics and risk factors of lower extremity deep venous thrombosis (DVT) during perioperative period of gastrointestinal surgery.Methods Color Doppler ultrasound was used for detecting lower extremity deep venous thrombosis in 120 patients undergoing gastrointestinal surgery from November 2014 to August 2015 in the First Affiliated Hospital of Zhengzhou University.Results There were 49 cases (40.8%) of lower extremity DVT after operation,including 24 cases (49%) of left lower extremity,10 cases (20.4%) of right lower extremity,and 15 cases (30.6%) of both lower extremities.48 cases (98%) were asymptomatic muscular venous thrombosis.73.5% (36 cases) DVT occurred within 2 hours postoperatively.Multiple logistic regression analysis showed that age over 60 years,malignant tumor,overweight (BMI ≥ 24 kg/m2),D-dimer increment > 1 mg/L,postoperative infection were closely related to the occurence of deep venous thrombosis of the lower extremities.Conclusion Asymptomatic muscular venous thrombosis within 2 hours after surgery is the main type of lower limb thrombosis in the perioperative gastrointestinal surgery.Age over 60 years,malignant tumor,postoperative infection,D-dimer increment > 1 mg/L,overweight are independent risk factors for lower extremity DVT after gastrointestinal surgery.%目的 探讨胃肠外科围手术期下肢深静脉血栓(deep venous thrombosis,DVT)形成的临床特点和危险因素.方法 应用彩色多普勒超声动态监测2014年1 1月至2015年8月郑州大学第一附属医院胃肠外科收治的所有符合入组标准的120例胃肠道疾病手术患者围手术期下肢深静脉血栓形成情况,统计所有患者手术前后DVT相关临床指标,并分析其对下肢DVT形成的影响.结果 在120例患者中,术后出现下肢DVT的有49例(40.8%),其中左下肢24例(49.0%),右下肢10例(20.4%),双下肢15例(30.6%),以无症状型肌间静

  19. Sensitivity of runoff behaviour of Alpine catchments to system conditions - looking at the current and future situation

    Science.gov (United States)

    Meißl, Gertraud; Klebinder, Klaus; Kerl, Florian; Dobler, Christian; Geitner, Clemens; Schöberl, Friedrich; Kohl, Bernhard; Markart, Gerhard; Sotier, Bernadette; Formayer, Herbert; Goler, Robert; Gorgas, Theresa; Bürger, Gerd; Bronstert, Axel

    2014-05-01

    Alpine settlements are often situated on alluvial fans at the outlet of small catchments. Thus they are - due to the short response time - exposed to a high risk in case of flash floods. Within the project "Sensitivity of the runoff characteristics of small Alpine catchments to climate change" we aim at identifying the critical combinations of event characteristics (intensity and duration of rain) and system conditions (soil moisture, state of vegetation and land use, snow cover) producing flash floods in order to improve the predictability of such events. We have investigated three Alpine catchments in western Austria with different altitudes and precipitation regimes. On the plot scale, field measurements, especially irrigation experiments, revealed that the rainfall-runoff reaction of slopes producing a high or low amount of surface runoff is relatively independent of the actual soil moisture content. However, plots producing a medium amount of surface runoff at dry conditions may generate significantly increased surface runoff volumes at moist conditions. Intensive grazing raises the amount of surface runoff with the duration of pasture season. Event analysis and mapping of the catchment inventories showed that the catchments with low (Ruggbachtal, 400 - 1000 m a.s.l, Vorarlberg) and medium altitude (Brixenbachtal, 800 - 2000 m a.s.l., Tyrol) tend to be sensitive to antecedent precipitation. Due to the high amount of pastured areas, the Brixenbach catchment shows a seasonal variation of runoff behaviour with a maximum of surface runoff in the late summer. The highly situated catchment (Längental, 2000 - 3000 m a.s.l., Tyrol) may show an increased runoff response at rain-on-snow-events. Because of its high portion of rock and talus slopes the runoff reaction of the catchment is quite insensitive to antecedent soil moisture content and grazing intensity. Currently ongoing hydrological modelling will show how seasonal system conditions (duration of snow cover

  20. Basin Zoning Characteristics of Sanyanyu Extremely Big Debris Flow Gully%三眼峪特大泥石流沟流域分区特征

    Institute of Scientific and Technical Information of China (English)

    黎志恒; 朱立峰; 胡向德; 于国强; 贾贵义; 李瑞冬

    2011-01-01

    三眼峪"8.8"特大泥石流属典型的沟谷型泥石流,整个沟域具有明显的形成区、流通区及堆积区.通过野外调查,竹塔沟一桥子沟以上的大、小眼峪上游沟脑为雨洪产流汇流区域,产流区与罐子坪--峪支沟一线之间为主要的固体物源区,大、小眼峪口至三眼峪口之间以过流为主,峪口至白龙江之间为堆积区.通过分析三眼峪流域分区特征和泥石流在不同分区的沿程冲淤变化.以期为建立三眼峪泥石流监测预警体系提供依据.%"8. 8" extremely big debris flow in Sanyanyu belongs to typical gully debris flow with obvious forming zone, transportation zone and accumulation zone. Based on site investigation, it is found that the gully head of upstream Dayanyu and Xiaoyanyu, situating at the up streams of Zhuta gully and Qiaozi gully, is the forming and accumulation zone of flood. It is also noted that the area between the forming zone and Guanziping-Yuzhi gully is the main solid source area. Area between Dayanyu-Xiaoyanyu and Sanyanyu is dominated by transportation channel. Finally, the accumulation area is situated between the mouth of Sanyanyu and Bailong River. By analyzing the zoning charateristics of Sanyanyu basin and erosion and siltation variation of debris flow in different zones, this paper can provide the basis for the establishment of Sanyanyu debris flow monitoring and warning system.

  1. Characteristics and formation mechanism of continuous extreme hazes in China: a case study in autumn of 2014 in the North China Plain

    Directory of Open Access Journals (Sweden)

    Y. R. Yang

    2015-04-01

    Full Text Available Four extreme haze episodes occurred in October 2014 in the North China Plain (NCP. To clarify the formation mechanism of hazes in the autumn, strengthened observations were conducted in Beijing from 5 October to 2 November. The meteorological parameters, satellite data, chemical compositions and optical properties of aerosols were obtained. The hazes originated from NCP, developing in the southwest and northeast directions, with the highest concentration of PM2.5 of 469 μg m−3 in Beijing. NCP was dominated by a weak high pressure system during the haze episode, which resulted in low surface wind speed and relatively stagnant weather. Moreover, the wind slowed down around Beijing city. The secondary aerosols NO3− was always higher than that of SO42−, which indicated the motor vehicles played a more important part in the hazes in October 2014, even though the oxidation rate from SO2 to SO42− was faster than that of NOx to NO3−. Sudden increases of the concentrations of organic matter, Cl− and BC (Black carbon before each haze episode implied that regional transport of pollutants by biomass burning was important for haze formation during the autumn. A satellite map of fire points and the backward trajectories of the air masses also indicated this pollution source. The distinct decrease in the PBL (planetary boundary layer height during four haze episodes restrained the vertical dispersion of the air pollutants. Water vapor also played a vital role in the formation of hazes by accelerating the chemical transformation of secondary pollutants, leading to hygroscopic growth of aerosols and altering the thermal balance of the atmosphere.

  2. Characteristics of the Extreme Low Temperature Events in Winter Half Year in China and Its Relationship to East Asian Winter Monsoon

    Science.gov (United States)

    Han, Yongqiu; Zhou, Lian-Tong

    2017-04-01

    Based on daily minimum temperature dataset from 553 stations from 1961 to 2012 in China, extreme low temperature (ELT) thresholds are determined for different stations and occurrence frequency of ELT events in winter half year for each station is estimated and analyzed. And then several partitions in China are divided by empirical orthogonal function and it is verified to be credible by correlation analysis. Meanwhile, the spatial and temporal distribution of ELT events in each sub-region is diagnosed. Finally, the relationship between ELT events and East Asian winter monsoon (EAWM) circulation is studied by doing some correlation analysis. The results suggest that: the ELT events in winter half year in China are remarkably decreased in recent 51 years, but there are some differences between southern and northern areas. From 1964 to 1980, the ELT events in northeast, north and northwest of China are more than average and that are less than average in south, east and southwest of China, while it is just the reverse from 1981 to 1996. Moreover, the distribution of ELT events also shows a longitudinal oscillation. The correlation analysis between the frequency of ELT events in winter half year and EAWM index indicates that the two has good correlation with each other. And meanwhile, the correlation analysis between the frequency of ELT events in winter half year and sea level pressure shows that the former has a good positive correlation with Siberian High. Besides, the distribution of the difference between two period mean sea level pressure, from 1961 to 1979 and from 1980 to 2011, shows that Siberian High has an obviously southwardly movement and a trend of weakening after 1980, which go against the outbreak of the cold, that is why the ELT events in winter half year in most areas of China have an abrupt decrease.

  3. Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention

    Science.gov (United States)

    Mikkelsen, Andreas Bech; Hubbard, Alun; MacFerrin, Mike; Box, Jason Eric; Doyle, Sam H.; Fitzpatrick, Andrew; Hasholt, Bent; Bailey, Hannah L.; Lindbäck, Katrin; Pettersson, Rickard

    2016-05-01

    It has been argued that the infiltration and retention of meltwater within firn across the percolation zone of the Greenland ice sheet has the potential to buffer up to ˜ 3.6 mm of global sea-level rise (Harper et al., 2012). Despite evidence confirming active refreezing processes above the equilibrium line, their impact on runoff and proglacial discharge has yet to be assessed. Here, we compare meteorological, melt, firn stratigraphy and discharge data from the extreme 2010 and 2012 summers to determine the relationship between atmospheric forcing and melt runoff at the land-terminating Kangerlussuaq sector of the Greenland ice sheet, which drains into the Watson River. The 6.8 km3 bulk discharge in 2012 exceeded that in 2010 by 28 %, despite only a 3 % difference in net incoming melt energy between the two years. This large disparity can be explained by a 10 % contribution of runoff originating from above the long-term equilibrium line in 2012 caused by diminished firn retention. The amplified 2012 response was compounded by catchment hypsometry; the disproportionate increase in area contributing to runoff as the melt-level rose high into the accumulation area.Satellite imagery and aerial photographs reveal an extensive supraglacial network extending 140 km from the ice margin that confirms active meltwater runoff originating well above the equilibrium line. This runoff culminated in three days with record discharge of 3100 m3 s-1 (0.27 Gt d-1) that peaked on 11 July and washed out the Watson River Bridge. Our findings corroborate melt infiltration processes in the percolation zone, though the resulting patterns of refreezing are complex and can lead to spatially extensive, perched superimposed ice layers within the firn. In 2012, such layers extended to an elevation of at least 1840 m and provided a semi-impermeable barrier to further meltwater storage, thereby promoting widespread runoff from the accumulation area of the Greenland ice sheet that contributed

  4. Runoff nutrient and suspended sediment fluxes, cycling, and management in southern Kaneohe Bay, Hawaii

    Science.gov (United States)

    Ringuet, S.; Young, C. W.; Hoover, D. J.; de Carlo, E. H.; MacKenzie, F. T.

    2003-12-01

    -limitation that has been confirmed by nutrient-enrichment experiments. Elevated DIN:DIP values for storm runoff (25) change significantly the proportion of dissolved nutrients available for biological uptake. Significant increases in Chl-a concentrations in the bay a few days after storms suggest that phytoplankton growth was stimulated by the excess nutrients. The extremely low phosphate levels combined with the very high DIN:DIP values in Bay waters imply that phosphorus was the ultimate limiting-nutrient. Therefore, stream runoff has the potential of shifting the "normal" nitrogen-limited environment into a phosphorus-limited ecosystem. This shift has consequences for the management of fluvial nutrient inputs to Kaneohe Bay.

  5. Integration of Volterra model with artificial neural networks for rainfall-runoff simulation in forested catchment of northern Iran

    Science.gov (United States)

    Kashani, Mahsa H.; Ghorbani, Mohammad Ali; Dinpashoh, Yagob; Shahmorad, Sedaghat

    2016-09-01

    Rainfall-runoff simulation is an important task in water resources management. In this study, an integrated Volterra model with artificial neural networks (IVANN) was presented to simulate the rainfall-runoff process. The proposed integrated model includes the semi-distributed forms of the Volterra and ANN models which can explore spatial variation in rainfall-runoff process without requiring physical characteristic parameters of the catchments, while taking advantage of the potential of Volterra and ANNs models in nonlinear mapping. The IVANN model was developed using hourly rainfall and runoff data pertaining to thirteen storms to study short-term responses of a forest catchment in northern Iran; and its performance was compared with that of semi-distributed integrated ANN (IANN) model and lumped Volterra model. The Volterra model was applied as a nonlinear model (second-order Volterra (SOV) model) and solved using the ordinary least square (OLS) method. The models performance were evaluated and compared using five performance criteria namely coefficient of efficiency, root mean square error, error of total volume, relative error of peak discharge and error of time for peak to arrive. Results showed that the IVANN model performs well than the other semi-distributed and lumped models to simulate the rainfall-runoff process. Comparing to the integrated models, the lumped SOV model has lower precision to simulate the rainfall-runoff process.

  6. Run-off studies demonstrate parallel transport behaviour for a marker of poultry fecal contamination and Staphylococcus aureus.

    Science.gov (United States)

    Weidhaas, J; Garner, E; Basden, T; Harwood, V J

    2014-08-01

    To determine whether poultry litter marker gene LA35 is correlated with pathogens and fecal indicator bacteria (FIB) in run-off from poultry litter-amended plots. A rainfall simulator with various vegetative filter strip lengths was employed to evaluate the correlation of a microbial source tracking (MST) marker for poultry feces/litter (the 16S rRNA gene of Brevibacterium sp. LA35 [LA35] measured by quantitative PCR) with pathogens and FIB in run-off. LA35 was correlated with Staphylococcus aureus, Escherichia coli, Enterococcus spp. and Bacteroidales levels. Salmonella was present at low concentration in litter, but became undetectable by qPCR in run-off. Escherichia coli, LA35 and Staph. aureus exhibited mass-based first flush behaviour in the run-off. Correlation of LA35 with FIB and pathogens in run-off from poultry litter-amended fields suggest comparable transport mechanisms and that LA35 is a useful tracer for harmful bacteria in the environment released from poultry litter. To protect human health, an effective marker for poultry fecal contamination should exhibit similar fate and transport characteristics compared to pathogens. This study is among the first to demonstrate such a relationship in run-off for a MST marker. © 2014 The Society for Applied Microbiology.

  7. From runoff to rainfall: inverse rainfall–runoff modelling in a high temporal resolution

    Directory of Open Access Journals (Sweden)

    M. Herrnegger

    2014-12-01

    Full Text Available This paper presents a novel technique to calculate mean areal rainfall in a high temporal resolution of 60 min on the basis of an inverse conceptual rainfall–runoff model and runoff observations. Rainfall exhibits a large spatio-temporal variability, especially in complex alpine terrain. Additionally, the density of the monitoring network in mountainous regions is low and measurements are subjected to major errors, which lead to significant uncertainties in areal rainfall estimates. The most reliable hydrological information available refers to runoff, which in the presented work is used as input for a rainfall–runoff model. Thereby a conceptual, HBV-type model is embedded in an iteration algorithm. For every time step a rainfall value is determined, which results in a simulated runoff value that corresponds to the observation. To verify the existence, uniqueness and stability of the inverse rainfall, numerical experiments with synthetic hydrographs as inputs into the inverse model are carried out successfully. The application of the inverse model with runoff observations as driving input is performed for the Krems catchment (38.4 km2, situated in the northern Austrian Alpine foothills. Compared to station observations in the proximity of the catchment, the inverse rainfall sums and time series have a similar goodness of fit, as the independent INCA rainfall analysis of Austrian Central Institute for Meteorology and Geodynamics (ZAMG. Compared to observations, the inverse rainfall estimates show larger rainfall intensities. Numerical experiments show, that cold state conditions in the inverse model do not influence the inverse rainfall estimates, when considering an adequate spin-up time. The application of the inverse model is a feasible approach to obtain improved estimates of mean areal rainfall. These can be used to enhance interpolated rainfall fields, e.g. for the estimation of rainfall correction factors, the parameterisation of

  8. A model for simulating the response of runoff from the mountainous watersheds of inland river basins in the arid area of northwest China to climatic changes

    Institute of Scientific and Technical Information of China (English)

    康尔泗; 程国栋; 蓝永超; 金会军

    1999-01-01

    A model for simulating the response of monthly runoff from the mountainous watersheds to climatic changes is developed.The model is based on the modifications to the HBV runoff model, and therefore represents the characteristics and runoff generation processes of inland river basins in the arid area of northwest China. Taking the mountainous watershed of an inland river, the Heihe River originating from the Qilian Mountains and running through the Hexi Corridor as an example, the monthly runoff changes under different climate scenarios are simulated. The simulation indicates that, during the years from 1994 to 2030, if the annual mean air temperature increases by 0.5℃, and precipitation keeps unchanged, then the runoff of May and October will increase because of the increase of the snow melt runoff, but the runoff of July and August will decrease to some extent because of the increase of evaporation, and as a result, the annual runoff will decrease by 4%. If the precipitation still keeps unchanged, an

  9. A Synopsis of Technical Issues for Monitoring Sediment in Highway and Urban Runoff

    Science.gov (United States)

    Bent, Gardner C.; Gray, John R.; Smith, Kirk P.; Glysson, G. Douglas

    2000-01-01

    Accurate and representative sediment data are critical for assessing the potential effects of highway and urban runoff on receiving waters. The U.S. Environmental Protection Agency identified sediment as the most widespread pollutant in the Nation's rivers and streams, affecting aquatic habitat, drinking water treatment processes, and recreational uses of rivers, lakes, and estuaries. Representative sediment data are also necessary for quantifying and interpreting concentrations, loads, and effects of trace elements and organic constituents associated with highway and urban runoff. Many technical issues associated with the collecting, processing, and analyzing of samples must be addressed to produce valid (useful for intended purposes), current, complete, and technically defensible data for local, regional, and national information needs. All aspects of sediment data-collection programs need to be evaluated, and adequate quality-control data must be collected and documented so that the comparability and representativeness of data obtained for highway- and urban-runoff studies may be assessed. Collection of representative samples for the measurement of sediment in highway and urban runoff involves a number of interrelated issues. Temporal and spatial variability in runoff result from a combination of factors, including volume and intensity of precipitation, rate of snowmelt, and features of the drainage basin such as area, slope, infiltration capacity, channel roughness, and storage characteristics. In small drainage basins such as those found in many highway and urban settings, automatic samplers are often the most suitable method for collecting samples of runoff for a variety of reasons. Indirect sediment-measurement methods are also useful as supplementary and(or) surrogate means for monitoring sediment in runoff. All of these methods have limitations in addition to benefits, which must be identified and quantified to produce representative data. Methods for

  10. 1819年黄河中游极端降水:史实、特征及气候背景%Extreme precipitation in the Middle Reaches of Yellow River in 1819: Historical facts, characteristics and climate background

    Institute of Scientific and Technical Information of China (English)

    张健; 满志敏; 张俊辉

    2011-01-01

    In this paper, the situation and space-time differentiation picture of extreme precipitation happened in more than one river valley over the Middle Reaches of the Yellow River in 1819 A. D. Is re produced by means of historical literature records, weather character, accompanied disasters, social im pact ( e. G. Houses collapsed, fields deserted, population casualties, river runoff overflowing etc. ) and the external affecting factors in this year have been discussed, and they were extreme climatic events and serious meteorological disaster in the cold background of little Ice Age during Ming and Qing Dynasties. The researchers found the summer rain lasted long ( overcast and rainy) , the main types of rain were heavy rain, and even rainstorm. From June to September, it was more than 40 days to the rainfall dura tion in the secondary river basin such as Fen River and Wei River in the Middle Reaches of Yellow River in 1819. With comparison, the rainfall change nearly keeps in step with the water level change process records of the Wanjintan in the Middle Reaches of Yellow River at the same time. Therefore, it is obvious that the floods in the Lower Reaches of Yellow River was caused by the extreme precipitation in the Middle Reaches of the Yellow River. In addition, the records of water level change process of the Wan Jin Tan are tested on the Pearson-El model of hydrologic distribution curve. The results indicate that the highest water level in flood in that year is once in a hundred year. By this measure, we can also infer that it pro duced extreme precipitation events in the Middle Reaches of theYellow River in 1819. The research shows three rainy centers: (1) from Hequ county to Jiazhou in the Middle Reaches of theYellow River main stream; (2) the upstream of Jing River and Wei River; (3) the Middle and Lower Reaches of Fen river and the triangular areas among the Wei, Luo and Yellow Rivers. Precipitation anomalies and the charac teristic feature of the years of

  11. Comparing bottom-up and top-down parameterisations of a process-based runoff generation model tailored on floods

    Science.gov (United States)

    Antonetti, Manuel; Scherrer, Simon; Margreth, Michael; Zappa, Massimiliano

    2016-04-01

    Information about the spatial distribution of dominant runoff processes (DRPs) can improve flood predictions on ungauged basins, where conceptual rainfall-runoff models usually appear to be limited due to the need for calibration. For example, hydrological classifications based on DRPs can be used as regionalisation tools assuming that, once a model structure and its parameters have been identified for each DRP, they can be transferred to other areas where the same DRP occurs. Here we present a process-based runoff generation model as an event-based spin-off of the conceptual hydrological model PREVAH. The model is grid-based and consists of a specific storage system for each DRP. To unbind the parameter values from catchment-related characteristics, the runoff concentration and the flood routing are uncoupled from the runoff generation routine and simulated separately. For the model parameterisation, two contrasting approaches are applied. First, in a bottom-up approach, the parameters of the runoff generation routine are determined a priori based on the results of sprinkling experiments on 60-100 m2 hillslope plots at several grassland locations in Switzerland. The model is, then, applied on a small catchment (0.5 km2) on the Swiss Plateau, and the parameters linked to the runoff concentration are calibrated on a single heavy rainfall-runoff event. The whole system is finally verified on several nearby catchments of larger sizes (up to 430 km2) affected by different heavy rainfall events. In a second attempt, following a top-down approach, all the parameters are calibrated on the largest catchment under investigation and successively verified on three sub-catchments. Simulation results from both parameterisation techniques are finally compared with results obtained with the traditional PREVAH.

  12. Diagnostic evaluation of distributed physically based model at the REW scale (THREW) using rainfall-runoff event analysis

    Science.gov (United States)

    Tian, F.; Sivapalan, M.; Li, H.; Hu, H.

    2007-12-01

    The importance of diagnostic analysis of hydrological models is increasingly recognized by the scientific community (M. Sivapalan, et al., 2003; H. V. Gupta, et al., 2007). Model diagnosis refers to model structures and parameters being identified not only by statistical comparison of system state variables and outputs but also by process understanding in a specific watershed. Process understanding can be gained by the analysis of observational data and model results at the specific watershed as well as through regionalization. Although remote sensing technology can provide valuable data about the inputs, state variables, and outputs of the hydrological system, observational rainfall-runoff data still constitute the most accurate, reliable, direct, and thus a basic component of hydrology related database. One critical question in model diagnostic analysis is, therefore, what signature characteristic can we extract from rainfall and runoff data. To this date only a few studies have focused on this question, such as Merz et al. (2006) and Lana-Renault et al. (2007), still none of these studies related event analysis with model diagnosis in an explicit, rigorous, and systematic manner. Our work focuses on the identification of the dominant runoff generation mechanisms from event analysis of rainfall-runoff data, including correlation analysis and analysis of timing pattern. The correlation analysis involves the identification of the complex relationship among rainfall depth, intensity, runoff coefficient, and antecedent conditions, and the timing pattern analysis aims to identify the clustering pattern of runoff events in relation to the patterns of rainfall events. Our diagnostic analysis illustrates the changing pattern of runoff generation mechanisms in the DMIP2 test watersheds located in Oklahoma region, which is also well recognized by numerical simulations based on TsingHua Representative Elementary Watershed (THREW) model. The result suggests the usefulness of

  13. RUNON a hitherto little noticed factor - Field experiments comparing RUNOFF/RUNON processes

    Science.gov (United States)

    Kohl, Bernhard; Achleitner, Stefan; Lumassegger, Simon

    2017-04-01

    covered plots. At the same time, a similar variety in the characteristics of the infiltration behavior between rainfall and runoff could be observed. This extension of artificial rainfall simulations with concurrent and successive runon tests will enhance our process understanding.

  14. How runoff begins (and ends): characterizing hydrologic response at the catchment scale

    Science.gov (United States)

    Mirus, Benjamin B.; Loague, Keith

    2013-01-01

    Improved understanding of the complex dynamics associated with spatially and temporally variable runoff response is needed to better understand the hydrology component of interdisciplinary problems. The objective of this study was to quantitatively characterize the environmental controls on runoff generation for the range of different streamflow-generation mechanisms illustrated in the classic Dunne diagram. The comprehensive physics-based model of coupled surface-subsurface flow, InHM, is employed in a heuristic mode. InHM has been employed previously to successfully simulate the observed hydrologic response at four diverse, well-characterized catchments, which provides the foundation for this study. The C3 and CB catchments are located within steep, forested terrain; the TW and R5 catchments are located in gently sloping rangeland. The InHM boundary-value problems for these four catchments provide the corner-stones for alternative simulation scenarios designed to address the question of how runoff begins (and ends). Simulated rainfall-runoff events are used to systematically explore the impact of soil-hydraulic properties and rainfall characteristics. This approach facilitates quantitative analysis of both integrated and distributed hydrologic responses at high-spatial and temporal resolution over the wide range of environmental conditions represented by the four catchments. The results from 140 unique simulation scenarios illustrate how rainfall intensity/depth, subsurface permeability contrasts, characteristic curve shapes, and topography provide important controls on the hydrologic-response dynamics. The processes by which runoff begins (and ends) are shown, in large part, to be defined by the relative rates of rainfall, infiltration, lateral flow convergence, and storage dynamics within the variably saturated soil layers.

  15. 1961~2010年内蒙古地区极端气候事件变化特征%Variable Characteristics of Extreme Climate Events During 1961-2010 in Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    白美兰; 郝润全; 李喜仓; 杨晶

    2014-01-01

    Based on daily maximum and minimum temperature and precipitation of 71 weather stations in Inner Mongolia during 1961-2010,according to the extreme indexes of temperature and precipitation,the variable characteristics of extreme climate events were an-alyzed by using homogeneity test and revisal,the polynomial method,linear tendency estimation,Mann-Kendall test. The results are as follows:(1)In recent 50 years,the annual and seasonal average temperatures occurred mutations in Inner Mongolia,but the muta-tion time of them had difference. The annual temperature had an abrupt change in 1988. The mutation of temperature in spring was ear-liest,and in summer was latest. (2)The indexes of extreme high temperature such as maximum and minimum temperature,high tem-perature days,warm night days and warm daytime days increased obviously,while the extreme low temperature indexes such as low temperature days,cold night days and cold daytime days decreased significantly especially after mutation. However,the fluctuation of extreme temperature increased after mutation. (3)The indexes of the extreme precipitation events reduced significantly except for the extreme snowfall especially after mutation in Inner Mongolia.%基于内蒙古地区71个地面气象站1961~2010年逐日最高气温、最低气温以及逐日降水资料,结合温度和降水极端值和极端事件指标,采用气温资料均一性检验和订正、多项式法、线性倾向、Mann-Kendall法等统计学方法诊断分析其变化特征。结果表明:(1)近50 a内蒙古地区年和四季平均气温均发生了突变,1987年为年平均气温突变转折点,四季气温突变时间春季最早,夏季最晚;(2)内蒙古地区表征极端气温增暖的极端最高气温、极端最低气温、高温日数、暖夜日数和暖日日数等指数均呈明显增加趋势;极端低温事件指标如低温日数、冷夜日数和冷日日数等均呈现出减少趋势,尤其在气温

  16. Testing the Runoff Tool in Sicilian vineyards: adopting best management practices to prevent agricultural surface runoff

    Science.gov (United States)

    Singh, Manpriet; Dyson, Jeremy; Capri, Ettore

    2016-04-01

    Over the last decades rainfall has become more intense in Sicily, making large proportions of steeply sloping agricultural land more vulnerable to soil erosion, mainly orchards and vineyards (Diodato and Bellocchi 2010). The prevention of soil degradation is indirectly addressed in the European Union's Water Framework Directive (2000/60/EC) and Sustainable Use Directive (2009/128/EC). As a consequence, new EU compliance conditions for food producers requires them to have tools and solutions for on-farm implementation of sustainable practices (Singh et al. 2014). The Agricultural Runoff and Best Management Practice Tool has been developed by Syngenta to help farm advisers and managers diagnose the runoff potential from fields with visible signs of soil erosion. The tool consists of 4 steps including the assessment of three key landscape factors (slope, topsoil permeability and depth to restrictive horizon) and 9 mainly soil and crop management factors influencing the runoff potential. Based on the runoff potential score (ranging from 0 to 10), which is linked to a runoff potential class, the Runoff Tool uses in-field and edge-of-the-field Best Management Practices (BMPs) to mitigate runoff (aligned with advice from ECPA's TOPPS-prowadis project). The Runoff tool needs testing in different regions and crops to create a number of use scenarios with regional/crop specific advice on BMPs. For this purpose the Tool has been tested in vineyards of the Tasca d'Almerita and Planeta wineries, which are large family-owned estates with long-standing tradition in viticulture in Sicily. In addition to runoff potential scores, Visual Soil Assessment (VSA) scores have been calculated to allow for a comparison between different diagnostic tools. VSA allows for immediate diagnosis of soil quality (a higher score means a better soil quality) including many indicators of runoff (Shepherd 2008). Runoff potentials were moderate to high in all tested fields. Slopes were classified as

  17. Study on Catchment Runoff Variations and Possible Responds to Climate Change and Human Activities

    Science.gov (United States)

    Qin, J.; Chen, Y.

    2016-12-01

    Under the influence of global climate change and human activities,the spatial-temporal distribution of precipitation has changed significantly which drives catchment hydrological processes changes.To better understand the characteristic and causes of runoff variations at different periods which would impacts catchment flood disaster risk, the Utaphao catchment is studied whichis a typical catchment in southern Thailand.Based on daily hydrological data from 1971 to 2014,selecting representative raingauges and stream gauging stations from the catchment as research stations. Using the methods of Mann-Kendall test and serial cluster analysis, this paper studied the characteristics and laws of historical hydrological process in Utaphao catchment, detects the impact of changing environment to watershed hydrological processes,the results show that the runoff and precipitation havesome kinds of changes.

  18. Estimation of parameters in a distributed precipitation-runoff model for Norway

    Directory of Open Access Journals (Sweden)

    S. Beldring

    2003-01-01

    Full Text Available A distributed version of the HBV-model using 1 km2 grid cells and daily time step was used to simulate runoff from the entire land surface of Norway for the period 1961-1990. The model was sensitive to changes in small scale properties of the land surface and the climatic input data, through explicit representation of differences between model elements, and by implicit consideration of sub-grid variations in moisture status. A geographically transferable set of model parameters was determined by a multi-criteria calibration strategy, which simultaneously minimised the residuals between model simulated and observed runoff from 141 Norwegian catchments located in areas with different runoff regimes and landscape characteristics. Model discretisation units with identical landscape classification were assigned similar parameter values. Model performance was evaluated by simulating discharge from 43 independent catchments. Finally, a river routing procedure using a kinematic wave approximation to open channel flow was introduced in the model, and discharges from three additional catchments were calculated and compared with observations. The model was used to produce a map of average annual runoff for Norway for the period 1961-1990. Keywords: distributed model, multi-criteria calibration, global parameters, ungauged catchments.

  19. Estimation of parameters in a distributed precipitation-runoff model for Norway

    Science.gov (United States)

    Beldring, Stein; Engeland, Kolbjørn; Roald, Lars A.; Roar Sælthun, Nils; Voksø, Astrid

    A distributed version of the HBV-model using 1 km2 grid cells and daily time step was used to simulate runoff from the entire land surface of Norway for the period 1961-1990. The model was sensitive to changes in small scale properties of the land surface and the climatic input data, through explicit representation of differences between model elements, and by implicit consideration of sub-grid variations in moisture status. A geographically transferable set of model parameters was determined by a multi-criteria calibration strategy, which simultaneously minimised the residuals between model simulated and observed runoff from 141 Norwegian catchments located in areas with different runoff regimes and landscape characteristics. Model discretisation units with identical landscape classification were assigned similar parameter values. Model performance was evaluated by simulating discharge from 43 independent catchments. Finally, a river routing procedure using a kinematic wave approximation to open channel flow was introduced in the model, and discharges from three additional catchments were calculated and compared with observations. The model was used to produce a map of average annual runoff for Norway for the period 1961-1990.

  20. Numerical study of water age influenced by tide and runoff in Daliaohe Estuary in China

    Institute of Scientific and Technical Information of China (English)

    WANG Peng-cheng; ZHANG Xue-qing; ZHAO Qian; SHI Ming-zhu

    2013-01-01

    Based on the concept of the age,the water transport characteristics as the response to the runoff and the tide in Daliaohe Estuary in China are studied under different hydrodynamic conditions using a three-dimensional convection-diffusion model.The results show that the relationship between the average age at a specific position and the runoff could be expressed by a power function approximately.In the river channel,the runoff controls the water transport:it might take about 52 d,27 d and 15 d for the water parcel to be transported from Sanchahe to the mouth during the dry,normal and rainy seasons,respectively.Outside the mouth,the tide is dominant even though the difference between the spring tide and the neap tide is less than 5 d,and the water parcel transports mainly along the northwest direction through the West Waterway and the southeast direction through the East Waterway.A significant age stratification emerges in the vicinity of the mouth,in which there exists a strong interaction between the tide and the runoff,and the age differences between the surface and the bottom could reach 7 d.

  1. Comparative evaluation of runoff and water quality using HSPF and SWMM.

    Science.gov (United States)

    Lee, Sae-Bom; Yoon, Chun-Gyeong; Jung, Kwang Wook; Hwang, Ha Sun

    2010-01-01

    Stormwater pollution is the untreated contaminated water that drains into natural waterways from land uses within an urban catchment. Several studies have demonstrated the deterioration of water quality in receiving bodies of water caused by stormwater runoff. The data have reported that urban runoff play primary roles in degrading water quality in adjacent aquatic systems. The accurate estimation of non-pollutant loads from urban runoff and the prediction of water quality in receiving waters are important. The objective of this paper is to assess the applicability of the watershed scale hydrologic and water quality simulation models SWMM and HSPF to simulate the hydrology of a small watershed in the Han River Basin. Monitoring was performed in small scale watersheds, which is homogeneous land use. The applicability of SWMM and HSPF model was examined for small watersheds using hourly monitoring data. The results of SWMM were reasonably reflected with observed data in small scale urban area. HSPF model was effective at specifying parameters related to runoff and water quality when using hourly monitoring data. The watershed models used in this study adequately simulated watershed characteristics and are recommended to support watershed management.

  2. Rainwater utilization and storm pollution control based on urban runoff characterization.

    Science.gov (United States)

    Zhang, Mulan; Chen, Hao; Wang, Jizhen; Pan, Gang

    2010-01-01

    The characteristics of urban runoffs and their impact on rainwater utilization and storm pollution control were investigated in three different functional areas of Zhengzhou City, China. The results showed that in the same rain event the pollutant loads (chemical oxygen demand (COD) and total suspended solids (TSS)) in the sampling areas were in the order of industrial area > commercial area > residential area, and within the same area the COD and TSS concentrations of road runoffs were higher than those of roof runoffs. The first flush effects in roof and road runoffs were observed, hence the initial rainwater should be treated separately to reduce rainwater utilization cost and control storm pollution. The initial roof rainfall of 2 mm in residential area, 5 mm in commercial area and 10 mm in industrial area, and the initial road rainfall of 4 mm in residential area and all the road rainfall in commercial and industrial areas should be collected and treated accordingly before direct discharge or utilization. Based on the strong correlation between COD and TSS (R2, 0.87-0.95) and the low biodegradation capacity (biochemical oxygen demand BOD5/COD system composed of soil and slag were designed to treat the initial rainwater, which could remove over 90% of the pollutant loads. The above results may help to develop better rainwater utilization and pollution control strategies for cities with water shortages.

  3. Partial Least Squares Regression for Determining the Control Factors for Runoff and Suspended Sediment Yield during Rainfall Events

    Directory of Open Access Journals (Sweden)

    Nufang Fang

    2015-07-01

    Full Text Available Multivariate statistics are commonly used to identify the factors that control the dynamics of runoff or sediment yields during hydrological processes. However, one issue with the use of conventional statistical methods to address relationships between variables and runoff or sediment yield is multicollinearity. The main objectives of this study were to apply a method for effectively identifying runoff and sediment control factors during hydrological processes and apply that method to a case study. The method combines the clustering approach and partial least squares regression (PLSR models. The case study was conducted in a mountainous watershed in the Three Gorges Area. A total of 29 flood events in three hydrological years in areas with different land uses were obtained. In total, fourteen related variables were separated from hydrographs using the classical hydrograph separation method. Twenty-nine rainfall events were classified into two rainfall regimes (heavy Rainfall Regime I and moderate Rainfall Regime II based on rainfall characteristics and K-means clustering. Four separate PLSR models were constructed to identify the main variables that control runoff and sediment yield for the two rainfall regimes. For Rainfall Regime I, the dominant first-order factors affecting the changes in sediment yield in our study were all of the four rainfall-related variables, flood peak discharge, maximum flood suspended sediment concentration, runoff, and the percentages of forest and farmland. For Rainfall Regime II, antecedent condition-related variables have more effects on both runoff and sediment yield than in Rainfall Regime I. The results suggest that the different control factors of the two rainfall regimes are determined by the rainfall characteristics and thus different runoff mechanisms.

  4. Surface-water hydrology and runoff simulations for three basins in Pierce County, Washington

    Science.gov (United States)

    Mastin, M.C.

    1996-01-01

    The surface-water hydrology in Clear, Clarks, and Clover Creek Basins in central Pierce County, Washington, is described with a conceptual model of the runoff processes and then simulated with the Hydrological Simulation Program-FORTRAN (HSPF), a continuous, deterministic hydrologic model. The study area is currently undergoing a rapid conversion of rural, undeveloped land to urban and suburban land that often changes the flow characteristics of the streams that drain these lands. The complex interactions of land cover, climate, soils, topography, channel characteristics, and ground- water flow patterns determine the surface-water hydrology of the study area and require a complex numerical model to assess the impact of urbanization on streamflows. The U.S. Geological Survey completed this investigation in cooperation with the Storm Drainage and Surface Water Management Utility within the Pierce County Department of Public Works to describe the important rainfall-runoff processes within the study area and to develop a simulation model to be used as a tool to predict changes in runoff characteristics resulting from changes in land use. The conceptual model, a qualitative representation of the study basins, links the physical characteristics to the runoff process of the study basins. The model incorporates 11 generalizations identified by the investigation, eight of which describe runoff from hillslopes, and three that account for the effects of channel characteristics and ground-water flow patterns on runoff. Stream discharge was measured at 28 sites and precipitation was measured at six sites for 3 years in two overlapping phases during the period of October 1989 through September 1992 to calibrate and validate the simulation model. Comparison of rainfall data from October 1989 through September 1992 shows the data-collection period beginning with 2 wet water years followed by the relatively dry 1992 water year. Runoff was simulated with two basin models-the Clover

  5. Investigation of the direct runoff generation mechanism for the analysis of the SCS-CN method applicability to a partial area experimental watershed

    Directory of Open Access Journals (Sweden)

    K. X. Soulis

    2009-05-01

    Full Text Available The Soil Conservation Service Curve Number (SCS-CN method is widely used for predicting direct runoff volume for a given rainfall event. The applicability of the SCS-CN method and the direct runoff generation mechanism were thoroughly analysed in a Mediterranean experimental watershed in Greece. The region is characterized by a Mediterranean semi-arid climate. A detailed land cover and soil survey using remote sensing and GIS techniques, showed that the watershed is dominated by coarse soils with high hydraulic conductivities, whereas a smaller part is covered with medium textured soils and impervious surfaces. The analysis indicated that the SCS-CN method fails to predict runoff for the storm events studied, and that there is a strong correlation between the CN values obtained from measured runoff and the rainfall depth. The hypothesis that this correlation could be attributed to the existence of an impermeable part in a very permeable watershed was examined in depth, by developing a numerical simulation water flow model for predicting surface runoff generated from each of the three soil types of the watershed. Numerical runs were performed using the HYDRUS-1D code. The results support the validity of this hypothesis for most of the events examined where the linear runoff formula provides better results than the SCS-CN method. The runoff coefficient of this formula can be taken equal to the percentage of the impervious area. However, the linear formula should be applied with caution in case of extreme events with very high rainfall intensities. In this case, the medium textured soils may significantly contribute to the total runoff and the linear formula may significantly underestimate the runoff produced.

  6. Runoff of copper and zinc caused by atmospheric corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Leuenberger-Minger, A.U.; Faller, M.; Richner, P. [Swiss Federal Labs. for Materials Testing and Research (EMPA), Duebendorf (Switzerland)

    2002-03-01

    Runoff and total corrosion loss for copper and zinc were investigated at seven sites in Switzerland. The exposure sites were chosen near the stations of the national air pollution monitoring network (NABEL), where climatic and air pollution data are measured. Runoff and corrosion rates were investigated after 0.5, 1, 2 and 4 years of exposure. Runoff rates differ from corrosion rates depending on the material, the exposure time and the sampling site. (orig.)

  7. Pollutants in stormwater runoff in Shanghai (China): Implications for management of urban runoff pollution

    Institute of Scientific and Technical Information of China (English)

    Siaka Ballo; Min Liu; Lijun Hou; Jing Chang

    2009-01-01

    Runoff samples were collected from four functional areas (traffic, residential, commercial and industrial) and four roof types (old con-crete, new concrete, old clay and new clay) in central Shanghai, China, during rain events. The event mean concentrations (EMCs) of three forms of nitrogen (NH4+-N,NO3--N,NO2--N) and the temporal variations of total phosphorus (TP) were then measured to evaluate the effects of runoff from different areas on water quality management. The results revealed that the TP levels varied significantly in the samples collected from different functional areas and roof types during rain events. In addition, although the NO3--N and NO2--N concentrations in runoff remained well below the fifth class values of the national surface water quality standards, the NH4+-N levels were 1.36, 1.17, 1.10 and 0.85 times higher than the standard value in samples collected from commercial, traffic, indus-trial, and residential areas, respectively. Similarly, the concentrations of NH4+-N in samples collected from old concrete, new concrete, old clay and new clay roofs exceeded the fifth class standard by 6.66, 5.72, 4.32 and 3.32 times, respectively. And the NO3--N levels were 1.86 and 1.53 times higher than the standard values in runoff samples collected from new and old concrete roofs, respectively.

  8. 石羊河流域极端干旱事件的时空变化特征%The Spatial and Temporal Characteristics of Extreme Drought Events in Shiyang River Basin

    Institute of Scientific and Technical Information of China (English)

    王兴梅; 张勃; 张凯; 张调风; 戴声佩; 王亚敏; 李丹

    2011-01-01

    本文借助ArcGIS9.2和Matlab7.0数据软件平台,运用复值Morlet小波分析和数理统计方法对石羊河流域极端干旱事件在时空上的变化特征进行分析,结果表明:①石羊河流域的平均湿润指数自北向南逐渐增大,其湿润指数与年均降水和海拔高度具有显著正相关性(在0.01置信水平),而与年均蒸发具有显著负相关性(在0.05置信水平).②在时间尺度上来说,极端干旱事件的频数具有19a、9a、6a、4a、15a的周期,可能是受南亚高压的准3年周期的影响;在空间尺度上来说,极端干旱事件频数与湿润指数的空间分布大体相似,略有不同是两者的最小值不同:即地表湿润指数最小值在民勤,而极端干旱事件发生频数最小值在武威.7-9月份发生极端干旱频数占年极端干旱总频数的60.62%.③年极端干旱总频数和7-9月份极端干旱总频数都呈略微上升趋势,且年极端干旱频数的线性倾向率较大,即将达到0.3/10a.通过Pettitt突变检验法对年极端干旱总频数和7-9月份极端干旱总频数进行检测,结果检验到突变点分别为2000年和1983年(在0.01置信水平).%With global warming, hot days and warm nights have significantly increased, but cold days and cold nights have decreased, and the frequency of extreme weather and climate events has significantly increased. Climate warming has four major challenges for our economy to face, of which the first challenge is the extreme weather events. The frequency of extreme weather events is getting bigger, with a tendency of getting stronger.Drought in global wanning becomes more prominent and sensitive, and is one of the key and hot issues in climate change research. This paper analyzes the spatial and temporal characteristics of extreme drought events in Shiyang River Basin, combining ArcGIS 9.2 and Matlab 7.0 data software platform and using complex Morlet wavelet analysis and mathematical statistical theory. The results

  9. 黄河源区降水与径流过程对ENSO 事件的响应特征%On the Characteristics of Response of Precipitation and Runoff to the ENSO Events in the Source Regions of the Yellow River

    Institute of Scientific and Technical Information of China (English)

    王根绪; 沈永平; 刘时银

    2001-01-01

    In the source regions of the Yellow River (above the Tangnag Section), runoff is mainly nourished by precipitation, accounting for 64. 1% of the total. Owing to climate change, variation in precipitation would result in runoff change in the source regions. According to a new ENSO index, which has a seasonal resolving ability, 20 ENSO events are identified from the spring 1952 through the spring 1998. There are 13 warm phase events and 7 cold phase events recognized. The strength and influence duration of each ENSO event is confirmed. Comparing the precipitation and runoff changing processes with the relative ENSO events, a statistical responsive relationship of precipitation and runoff to ENSO events in the source regions of the Yellow River are worked out in this paper. It is found that the annual fluctuation of precipitation and runoff in the source regions are obviously inter related to ENSO events. The interrelationship was associated to the features, strength, occurring season and duration of the event. Generally, a warm phase event occurring in the summer and autumn may decrease the precipitation in the influence duration no matter how the strength of the ENSO event is. A warm phase event with middle strength occurring in the spring season would decrease the precipitation in the occurring duration, but would increase the precipitation in the influence duration. On the contrary, the cold phase event may increase the precipitation in the source regions. A warm phase event would decrease the runoff in the source regions. On the contrary, a cold phase event can increase the runoff. Because the occurring rate of the warm phase event has increased since the 1990s, runoff has a decrease trend in the source regions of the Yellow River.%根据最新季分辨率ENSO指数序列所确认的近40多年来所发生的20次ENSO事件,并确定了每次ENSO事件强度及其影响年,通过对相应年份黄河源区降水与径流距平变化值的对比

  10. Evaluative Characteristic of Extreme Minimum Temperature of Northwest China in Recent 49 Years%近49年中国西北地区极端低温事件的演变特征

    Institute of Scientific and Technical Information of China (English)

    陈少勇; 王劲松; 任燕; 乔立

    2011-01-01

    The low temperature events were analyzed based on the NCEP/NCAR data and the daily minimum temperature observation data from 135 meteorological stations in the Northwest China during 1961-2009,using the methods of linear regression analysis,Mann-Kendall,running T-test,wavelet analysis,power spectrum and composite analysis.The results show that:(1) The spatial distribution of the extreme minimum temperature in Northwest China presents the distributed tendencies of two high and low interactions.The areas with minimum temperature value are located in northern Xinjiang and Qinghai Plateau.And the threshold value of extreme minimum temperature in these places are below-20 ℃;(2) The frequency of annual extreme minimum temperature has obviously reducing at a rate of 3.7 d·(10 a)-1,majority places remarkably reduced at a rate of 3~5 d·(10 a)-1.There is an abrupt change in 1985,the minimum temperature frequency has the remarkable 3 year periods.(3) The values of extreme minimum temperature are between-49.8 to-8.6 ℃,the maximum value appears in Fuyun of Xinjiang.There is a same geographic distribution between minimum temperature intensity and extreme minimum temperature. The intenser the extreme minimum temperature is,the longer the day number of duration is. The phase of frequently occurring of minimum temperature is also the phase of the strongest minimum temperature.The global warming causes the extreme minimum temperature events reducing and intensity weakening.(4) From the circulation characteristic quantity analysis, the extreme minimum temperature in Xinjiang related with zonal circulation,polar vortex characteristic quantity and Atlantic-Europe circulation,but the extreme minimum temperature in other places related with subtropical high and QinghaiXizang Plateau height field.The composited analysis indicated that the polar vorticity center is located the Eastern Hemisphere.The Arctic region is the positive anomalous.The middle latitude

  11. Extreme Precipitation and Emergency Room Visits for Gastrointestinal Illness in Areas With and Without Combined Sewer Systems: An Analysis of Massachusetts Data, 2003-2007

    Science.gov (United States)

    Background: Combined sewer overflows (CSOs) occur in combined sewer systems when sewage and stormwater runoff discharge into waterbodies potentially contaminating water sources. CSOs are often caused by heavy precipitation and are expected to increase with increasing extreme pre...

  12. Extreme Precipitation and Emergency Room Visits for Gastrointestinal Illness in Areas With and Without Combined Sewer Systems: An Analysis of Massachusetts Data, 2003-2007

    Science.gov (United States)

    Background: Combined sewer overflows (CSOs) occur in combined sewer systems when sewage and stormwater runoff discharge into waterbodies potentially contaminating water sources. CSOs are often caused by heavy precipitation and are expected to increase with increasing extreme pre...

  13. Impact of forest disturbance on the runoff response in headwater catchments. Case study: Sumava mountains, Czech republic

    Science.gov (United States)

    Langhammer, Jakub; Hais, Martin; Bartunkova, Kristyna; Su, Ye

    2013-04-01

    The forest disturbance and stream modifications are important phenomenon affecting the natural dynamics of erosion and sedimentation processes on montane and submontane streams. The changes in land use, land cover structure, forest cover and stream modifications, occurring in the cultural landscape have significant effect on the dynamics of fluvial processes, especially in relation to the extreme runoff events. The contribution discusses the relations between forest disturbance and fluvial dynamics, stemming from the research in Sumava Mountains, located at the border between Czech Republic and Germany, Central Europe. The study area is located in headwater region, affected by different types of forest disturbance in past three decades - bark beetle outbreak, repeated windstorms and clear-cut forest management. The streams in experimental catchments here displayed extensive dynamics of erosion and sedimentation after the extreme floods in 2002 and 2009 and were affected by artificial modifications. The analysis is based on the combination of different research techniques, including remote sensed data processing, network of automated high frequency rainfall-runoff monitoring or field survey of stream modifications and geomorphologic changes on riverbeds after extreme events. Using landsat satellite data and aerial photographs we created model of Bark beetle dispersion and clear-cutting between 1985 and 2007. This model enables to describe disturbance dynamic, which is needed for understanding of nature those processes. Next analysis of Landsat satellite data was used to detect the effect of forest disturbance on the wetness and temperature properties of land cover, affected by two significant different types of forest disturbance - bark beetle outbreak and clear cut. The rainfall-runoff analysis using multivariate geostatistical techniques was focused on experimental catchments with similar conditions of climate, physiography and topography but different type

  14. Distribution Characteristics of Salinity in Elaeagnus angustifolia Shelterbelts in Extreme Arid Area%滴灌沙枣防护林土壤盐分分布特征

    Institute of Scientific and Technical Information of China (English)

    赵新风; 徐海量; 张鹏; 刘新华

    2012-01-01

    利用3年(2008-2011年)的野外对比试验与长期实地监测数据,分析喀拉米吉绿洲滴灌沙枣(Elaeagnus angustifolia)防护林地的土壤盐分及动态情况。结果表明:(1)林地在滴灌与不滴灌条件下,土壤盐分含量差异显著(p〈0.05)。在不同灌水量条件(单株单次灌水18,30,48L)下的林地土壤盐分含量与分布特征不相同,其中单株单次灌水48L处理与对照相比,土壤盐分含量差异达极显著水平(p〈0.01);3种不同灌水量处理(18,30,48L)分别使30cm以上土层、50cm以上土层、整个根系土层的盐度值低于1.4mS/cm;(2)在沙枣生育期内,土壤盐分呈现逐渐上升的趋势,且通过了显著性水平;不同深度(20,40,60cm)的土壤盐分上升趋势有差异,其中40cm深处土壤盐分上升趋势最显著,20cm与60cm深处趋势水平差异不大;(3)在1个灌溉周期内(20d),林地土壤盐分动态表现为集中-均匀-集中的过程。停水后第2天,上层土壤盐分含量明显下降,滴灌将盐分压于30cm以下,并集中于40-60cm土层;停水后第4~8天,整个观测范围内的剖面土壤盐分明显下降,原聚集于中土层的盐分基本消失,从而使停水后第4~8天土壤盐分淋洗效果最显著;停水后第12天,剖面高盐分土层又重新出现,然后随着时间的延续高盐分土层愈加明显。因此,随着1个灌溉周期的结束,高含盐量土层的位置逐渐上移,其范围逐步扩大;(4)本试验中,在种植的第2~3年,水分供给不足是沙枣成活率低、生长量低的主要原因,而影响沙枣第1年成活率的是土壤次生盐渍化(盐分高达5~9mS/cm)。滴灌洗盐只是局部,建议滴灌防护林1年采取1次大水漫灌。%Based on three years of field test from 2008 to 2010, distribution characteristics of salinity in Elaeagnus angustifolia shelterbelts was checked in Kalami oasis in the lower reaches of Tarim river. The main

  15. "Wishful thinking" - how much rainfall information can be inferred from soil moisture and runoff?

    Science.gov (United States)

    Pan, M.; Zhan, W.; Wanders, N.; Wood, E. F.

    2014-12-01

    In a land surface hydrologic system, rainfall is a major forcing (input) to drive the moisture and energy dynamics and the soil moisture and runoff are the result (output) of such dynamics. Land surface models (LSMs) have long been used to simulate such a dynamic system given the forcing input. The question here is whether, how much, and how the soil moisture and runoff (output) data can be used to recover rainfall (input) information or help improve our existing rainfall estimates. This is essentially to perform an inverse estimation of LSM. Such an inverse operation can help us optimally combine information (e.g. remote sensing observations) gathered across both input and output variables and improve our quantification of different components of the land surface hydrologic system and the consistency among them. However, this is seemingly and indeed no easy task and some consider it more "wishful thinking" than practically meaningful, given the extremely complicated structure and behavior of the land surface hydrologic system. Here we explore two methods for solving the inverse LSM estimation problem (1) the Wiener Filter (WF) based deconvolution approach where the land surface is treated as a stationary linear system with fixed Impulse Response Function (IRF) w.r.t rainfall input and (2) the Particle Filter (PF) based Bayesian approach. The results suggest that while there is a limit of how much such inverse estimation can do under different conditions it is possible to recover a very significant amount of rainfall information from soil moisture and runoff.

  16. [Impact of changes in land use and climate on the runoff in Liuxihe Watershed based on SWAT model].

    Science.gov (United States)

    Yuan, Yu-zhi; Zhang, Zheng-dong; Meng, Jin-hua

    2015-04-01

    SWAT model, an extensively used distributed hydrological model, was used to quantitatively analyze the influences of changes in land use and climate on the runoff at watershed scale. Liuxihe Watershed' s SWAT model was established and three scenarios were set. The calibration and validation at three hydrological stations of Wenquan, Taipingchang and Nangang showed that the three factors of Wenquan station just only reached the standard in validated period, and the other two stations had relative error (RE) 0.8 and Nash-Sutcliffe efficiency valve (Ens) > 0.75, suggesting that SWAT model was appropriate for simulating runoff response to land use change and climate variability in Liuxihe watershed. According to the integrated scenario simulation, the annual runoff increased by 11.23 m3 x s(-1) from 2001 to 2010 compared with the baseline period from 1991 to 2000, among which, the land use change caused an annual runoff reduction of 0.62 m3 x s(-1), whereas climate variability caused an annual runoff increase of 11.85 m3 x s(-1). Apparently, the impact of climate variability was stronger than that of land use change. On the other hand, the scenario simulation of extreme land use showed that compared with the land use in 2000, the annual runoff of the farmland scenario and the grassland scenario increased by 2.7% and 0.5% respectively, while that of the forest land scenario were reduced by 0.7%, which suggested that forest land had an ability of diversion closure. Furthermore, the scenario simulation of climatic variability indicated that the change of river runoff correlated positively with precipitation change (increase of 11.6% in annual runoff with increase of 10% in annual precipitation) , but negatively with air temperature change (reduction of 0.8% in annual runoff with increase of 1 degrees C in annual mean air temperature), which showed that the impact of precipitation variability was stronger than that of air temperature change. Therefore, in face of climate

  17. Observing and predicting the spatial-temporal pattern of runoff generation processes from the watershed to the regional scale

    Science.gov (United States)

    Weiler, M.

    2012-12-01

    Runoff generation processes are the key to understand and predict watershed dynamics and behaviour under current as well as under changing conditions. A variety of approaches have been developed to observe these processes at the plot scale (e.g. infiltration and sprinkling experiments), the hillslope scale (soil moisture and piezometer networks and trenching) and the watershed scale (hydrograph separation with stable isotopes and natural tracers). However, predicting the four major runoff generation mechanisms (infiltration excess, saturation excess, subsurface flow and deep percolation) without detailed observation in ungauged watershed is still a challenge, but a prerequisite to track water flow pathways and to make adequate prediction for hydrological extremes. Methods have been developed to map dominant runoff generation processes in the field and with digital maps, however, these methods are often static and do not consider the temporal dynamics of runoff generation processes frequently observed with the various experimental approaches. The recently developed parsimonious rainfall-runoff model DROGen can bridge the gap between across spatial scales in ungauged watersheds since parameters are not calibrated. The model incorporates high-resolution GIS data (1m resolution DEM, land-use, impervious surfaces), hydro-geological and pedological data as well as information about the effect of macropores and preferential flow pathways on runoff generation processes with a comprehensive knowledge base from various field observations and experiments. The model was applied to over 6500 meso-scale watershed in the State of Baden-Württemberg in Germany and 15 gauged watersheds were selected for detailed model evaluation. The evaluation was done with field-mapping of runoff generation processes for direct comparison with the simulated pattern of runoff processes for different types of precipitation (high intensity and short duration / low intensity and long duration) and

  18. 近50年西南地区极端干旱气候变化特征%Climate Characteristics of the Extreme Drought Events in Southwest China during Recent 50 Years

    Institute of Scientific and Technical Information of China (English)

    贺晋云; 张明军; 王鹏; 王圣杰; 王兴梅

    2011-01-01

    利用中国气象局整编的1960-2009年西南地区108站逐日气温、降水等资料,计算年、月地表湿润指数,并进行标准化,统计极端干旱发生频率,对年际、年代际、季风期和非季风期的极端干旱变化特征进行分析,得出结论:(1)整体上,四川盆地西南部、横断山区南端、广西南部沿海和贵州北部是近50年来年极端干旱发生频率明显增加的地区;年代际变化上,20世纪60-80年代极端干旱呈逐渐减少趋势,高发区交替出现在东南—西北—东,90年代下降明显,整个地区都转湿,进入21世纪后,极端干旱距平呈现正距平,且增幅较大,区域间差异却显著减小.(2)季风期与非季风期的极端干旱变化有很大差异,季风期极端干旱频率在不断增加,多发生在四川盆地周边海拔较高的山区、广西大部和“帚形山脉”地带,海拔对季风期极端干旱发生频率有一定影响;非季风期缓慢下降,整体偏湿.(3)通过滑动t检验和小波分析发现,季风期西南极端干旱在2003年发生突变,非季风期在1989年突变,年极端干旱发生频率是季风期和非季风期的突变叠加的结果;年极端干旱存在准5年和准12年的周期变化.%Based on the daily data of temperature and precipitation of 108 meteorological stations in Southwest China from 1960 to 2009, we calculated the surface humid indexes of months and years, as well as the extreme drought frequency. According to the data, the temporal and spatial characteristics of the extreme drought frequency in inter-annual, inter-decadal, summer monsoon and winter monsoon has been analyzed. The results are indicated as follows: (1) In general, the southwest of Sichuan Basin, the southern part of Hengduan Mountains, southern coast of Guangxi and north of Guizhou are the areas in which the extreme drought frequency has significantly increased in the past 50 years. For the decadal change, from the 1960s to the 1980s the

  19. Extremely Preterm Birth

    Science.gov (United States)

    ... Events Advocacy For Patients About ACOG Extremely Preterm Birth Home For Patients Search FAQs Extremely Preterm Birth ... Spanish FAQ173, June 2016 PDF Format Extremely Preterm Birth Pregnancy When is a baby considered “preterm” or “ ...

  20. Anomaly in the rainfall-runoff behaviour of the Meuse catchment. Climate, land-use, or land-use management?

    NARCIS (Netherlands)

    Fenicia, F.; Savenije, H.H.G.; Avdeeva, Y.

    2009-01-01

    OA-Fund TU Delft The objective of this paper is to investigate the time variability of catchment characteristics in the Meuse basin through its effect on catchment response. The approach uses a conceptual model to represent rainfall-runoff behaviour of this catchment, and evaluates possible

  1. A study of non-linearity in rainfall-runoff response using 120 UK catchments

    Science.gov (United States)

    Mathias, Simon A.; McIntyre, Neil; Oughton, Rachel H.

    2016-09-01

    This study presents a catchment characteristic sensitivity analysis concerning the non-linearity of rainfall-runoff response in 120 UK catchments. Two approaches were adopted. The first approach involved, for each catchment, regression of a power-law to flow rate gradient data for recession events only. This approach was referred to as the recession analysis (RA). The second approach involved calibrating a rainfall-runoff model to the full data set (both recession and non-recession events). The rainfall-runoff model was developed by combining a power-law streamflow routing function with a one parameter probability distributed model (PDM) for soil moisture accounting. This approach was referred to as the rainfall-runoff model (RM). Step-wise linear regression was used to derive regionalization equations for the three parameters. An advantage of the RM approach is that it utilizes much more of the observed data. Results from the RM approach suggest that catchments with high base-flow and low annual precipitation tend to exhibit greater non-linearity in rainfall-runoff response. In contrast, the results from the RA approach suggest that non-linearity is linked to low evaporative demand. The difference in results is attributed to the aggregation of storm-flow and base-flow into a single system giving rise to a seemingly more non-linear response when applying the RM approach to catchments that exhibit a strongly dual storm-flow base-flow response. The study also highlights the value and limitations in a regionlization context of aggregating storm-flow and base-flow pathways into a single non-linear routing function.

  2. Impacts of climate change scenarios on runoff regimes in the southern Alps

    Directory of Open Access Journals (Sweden)

    S. Barontini

    2009-04-01

    the smaller Lys basin, where the glaciated area is 8% of the total area, the annual runoff is foreseen to decrease by about 3% (for the 2050 scenario and 14% at the end of this century. Also the runoff regime changes are significant, with an increase of spring melt and a decrease of summer and autumn runoff. No clear evidence is found for changes in the precipitation extremes and in the fraction of rainy days.

  3. Climate change of the Sardinian hydrology: the NAO impact on the precipitation and runoff regimes

    Science.gov (United States)

    Sarigu, Alessio; Montaldo, Nicola

    2015-04-01

    the Mediterranean basin is also performed, for analysing the correlation between storm tracks and extreme events in Sardinia. We found high negative correlations between NAO and precipitation and runoff during the winter season, and the correlations decrease with the increase of rain station longitudes. The results show a strong negative correlation at the stations and basins of the Sardinian west coast, which is due to the exposure to the mistral winds and the storm track dynamics. Instead a less negative correlation has been estimated for the east coast stations and basins due to the impact of the horography which attenuate the large scale atmospheric dynamics.

  4. Hydrology in a mediterranean mountain environment. The Vallcebre research catchment (north eastern Spain) II. Rainfall-runoff relationships and runoff processes; Hidrologia de un ambiente Mediterraneo de montana. Las cuencas de Vallcebre (Pirineo Oriental) II. Relaciones precipitacion-escorrentia y procesos hidrologicos

    Energy Technology Data Exchange (ETDEWEB)

    Latron, J.; Solar, M.; Nord, G.; Llorens, P.; Gallart, F.

    2009-07-01

    Hydrological response and runoff processes have been studied in the Vallcebre research basins (North Eastern Spain) for almost 20 years. Results obtained allowed to build a more complete perceptual model of the hydrological functioning of Mediterranean mountains basins. On a seasonal and monthly scale, there was no simple relationship between rainfall and runoff depths. Monthly rainfall and runoff values revealed the existence of a threshold in the relationship between rainfall and runoff depths. At the event scale, the storm-flow coefficient had a clear seasonal pattern. The effect of the water table position on how rainfall and runoff volumes relate was observed. Examination of soil water potential and water table dynamics during representative floods helped to identify 3 types of characteristic hydrological behaviour during the year. Under dry conditions, runoff was generated essentially as infiltration excess runoff in low permeable areas, whereas saturation excess runoff dominated during wetting-up and wet conditions. During wetting-up transition, saturated areas resulted from the development of scattered perched water tables, whereas in wet conditions they were linked to the rise of the shallow water table. (Author) 8 refs.

  5. Simulating pesticide transport in urbanized catchments: a new spatially-distributed dynamic pesticide runoff model

    Science.gov (United States)

    Tang, Ting; Seuntjens, Piet; van Griensven, Ann; Bronders, Jan

    2016-04-01

    depression storage (including degradation, infiltration and runoff). Processes on hard surfaces employs the conceptualization described in the paragraph above. The WetSpa-PST model can account for various spatial details of the urban features in a catchment, such as asphalt, concrete and roof areas. The distributed feature also allows users to input detailed pesticide application data of both non-point and point origins. Thanks to the Python modelling framework prototype used in the WetSpa-Python model, processes in the WetSpa-PST model can be simulated at different time steps depending on data availability and the characteristic temporal scale of each process. This helps to increase the computational accuracy during heavy rainfall events, especially for the associated fast transport of pesticides into surface water. Overall, the WetSpa-PST model has good potential in predicting effects of management options on pesticide releases from heavily urbanized catchments.

  6. How useful are Green-Ampt parameters derived from small rainfall simulation plots for modelling runoff at different plot lengths?

    Science.gov (United States)

    Langhans, Christoph; Engels, Lien; Tegenbos, Lize; Govers, Gerard; Diels, Jan

    2010-05-01

    Rainfall simulation on small field plots is an invaluable method to derive effective field parameters for infiltration models such as Green-Ampt. Plot scales of ca. 1m² integrate much of the micro-scale variability and processes, which ring-infiltrometers or soil core measurements cannot capture. However, these parameters have to be used with caution on larger scales, because processes such as run-on infiltration can be considerable. The Green-Ampt parameters suction across the wetting front (psi) and effective hydraulic conductivity (Ke) were estimated from rainfall simulations on two ridged fields in Togo, West Africa. Additionally, rainfall events were recorded, and on plots of 1m width and lengths of 1, 4 and 16m, total runoff volume and sediment concentration were measured. The storm runoff hydrographs of the plots were modelled with Chu's Green-Ampt variable rainfall intensity infiltration model, using the field-average parameters derived from the simulations. Potential effects of runoff lag time were assumed negligible. Calculated total runoff volumes were compared to measured runoff volumes. For the 1m plots, runoff was underestimated, as patches of seal in the furrows produced runoff already at rainfall intensities much lower than the average infiltration capacity. For the longer plots, no run-on infiltration or other scale dependent processes were assumed, so the relative error due to scale effects was proportional to the average difference or runoff depth. In contrast to the 1m plots, runoff was overestimated by a factor of 1.2 and 2 for the 4m and 16m plots, respectively. It appears that the application of the Green-Ampt effective hydraulic conductivity derived from rainfall simulations faces two main problems, which are their dependence on one single rainfall intensity and scale-effects by run-on infiltration. Errors necessarily propagate into the scale dependency of erosion and sediment transport, as these processes are directly dependent on runoff

  7. Urban Runoff and Nutrients Loading Control from Sustainable BMPs (Invited)

    Science.gov (United States)

    Xiao, Q.

    2009-12-01

    Climate change alters hydrodynamic and nutrient dynamic in both large and small geographic scales. These changes in our freshwater system directly affect drinking water, food production, business, and all aspects of our life. Along with climate change is increasing urbanization which alters natural landscape. Urban runoff has been identified as one of many potential drivers of the decline of pelagic fishes in san Francisco Bay-Delta region. Recent found of Pyrethroids in American River has increased scientists, public, and policy makers’ concern about our fresh water system. Increasing our understanding about the fundamental hydrodynamic, nutrient dynamics, and the transport mechanics of runoff and nutrients are important for future water resource and ecosystem management. Urbanization has resulted in significantly increasing the amount of impervious land cover. Most impervious land covers are hydrophobic that alters surface runoff because of the effects on surface retention storage, rainfall interception, and infiltration. Large volumes of excess storm runoff from urbanized areas cause flooding, water pollution, groundwater recharge deficits, destroyed habitat, beach closures, and toxicity to aquatic organisms. Parking lot alone accounts for more than 11% of these impervious surfaces. Contrast to impervious parking lot, turfgrass can accouter for 12% of urban land in California. Irrigated urban landscapes create considerable benefits to our daily living. However, the use of fertilizers and pesticides has caused environmental problems. Preventing fertilizers and pesticides from entering storm drains is an important goal for both landscape and storm runoff managers. Studies of urban runoff have found that the most fertilizers and pesticides are from dry weather runoff which conveys pollutants to sidewalks, streets, and storm drains. Controlling surface runoff is critical to preventing these pollutants from entering storm drains and water bodies. Large scale

  8. 麦田降雨产流过程的影响因素%Influence Factors of Rainfall Runoff in the Winter Wheat Field

    Institute of Scientific and Technical Information of China (English)

    刘战东; 高阳; 段爱旺; 巩文军

    2012-01-01

    In order to study effects of several influence factors on rainfall runoff and the corresponding quantitative relationships in the winter wheat field,effects of some main factors on rainfall runoff characteristics,including rainfall intensity(RI),canopy cover(leaf area index,LAI) and initial water content of soil layers of 0-40 cm soil(θ40),were studied with experiments of artificial rainfall simulations.Results indicated that as the other influencing factors were fixed,the runoff intensity cumulative runoff had the obvious negative exponent function with the rainfall duration(P0.01);as RI increasing,the time started of surface flow was advanced,runoff intensity,the accumulative runoff and runoff coefficient increased.As LAI decreasing,runoff began earlier,runoff intensity,the accumulative runoff and runoff coefficient increased.When RI increased,influences of LAI on rainfall runoff process diminished.When the value of RI and LAI was fixed,the initial time of runoff was advanced with the increase of θ40,and the runoff intensity,runoff and runoff coefficient were also increased,but the stable runoff intensity were basically similar.Through the statistical analysis of the measured data of simulated rainfall,the runoff intensity,cumulative runoff could finally be fitted to four factor functions of t,RI,LAI and θ40.Runoff coefficient regression calculation model was established.%为探讨多种因素对麦田降雨产流的影响及其相应的定量关系,通过人工模拟降雨试验,研究麦田降雨强度(RI)、冠层覆盖度(用叶面积指数表示,LAI)及0-40cm土壤初始含水量(θ40)对降雨产流特征的影响。结果表明:在其他影响因素一定条件下,径流强度和累积径流量与降雨历时分别具有显著的负指数函数和幂函数关系(P〈0.01);产流时间随RI增大而提前,径流强度、累积径流量和径流系数随RI增大而增大;产流时间随LAI的减少而提前,径流强度

  9. Evolution Characteristics of the Extreme High Temperature Event in Northwest China from 1961 to 2009%中国西北地区1961—2009年极端高温事件的演变特征

    Institute of Scientific and Technical Information of China (English)

    陈少勇; 王劲松; 郭俊庭; 芦旭东

    2012-01-01

    利用中国西北地区135个测站1961—2009年历年逐日地面最高气温和NCEP/NCAR资料,采用线性趋势分析、Mann-Kendall、子波分析、合成分析等方法,分析了近49 a西北地区高温事件的演变特征。结果表明:西北地区极端高温的高值区在新疆大部分地区、河西走廊西部、甘肃中北部、陇东南、宁夏北部和陕西,这些地方的高温阈值在30℃以上;区域年极端高温频率以1.8 d/10 a的速率显著增多,1970年代中期高温日数发生由少至多的转型,1994年有突变,高温频数有显著的3-5 a周期,目前仍处于高温频发阶段;极端最高气温介于22.5-47.8℃之间,最大值出现在吐鲁番盆地。4—10月皆可出现高温,但主要出现在6—8月,其中7月最多。6月高温频率增加最显著,其他月份增加不明显;高温越强,持续日数越长,高温频发的时段也是高温最强的时段。气候变暖导致极端高温事件增多,强度增强。从大气环流合成分析表明,乌山脊、巴尔喀什湖低槽和蒙古脊中高层位置稳定,大气为准正压状态,西北地区在蒙古高脊控制下,有利于形成大范围持续性高温天气。%Using over years daily surface extreme air temperature and NCEP/NCAR data of 135 meteorological observation stations in Northwest China from 1961 to 2009, and adopting the meth- ods of linear regression analysis, Mann-Kendall, moving t-examination, wavelet analysis, power spectrum and composite analysis, we analyzed the evolution characteristics of high temperature e- vent in recent 49 years of Northwest China. The results show that spatial distribution of the ex- treme high temperature in Northwest China presents high value in the western and eastern parts, and low value in the central part. The main areas with extreme high temperature value are located in most part of Xinjiang, the western Hexi Corridor, the central and northern Gansu, southeastern Gansu, northern Ningxia and Shaanxi

  10. Investigation of Rainfall-Runoff Processes and Soil Moisture Dynamics in Grassland Plots under Simulated Rainfall Conditions

    Directory of Open Access Journals (Sweden)

    Nana Zhao

    2014-09-01

    Full Text Available The characteristics of rainfall-runoff are important aspects of hydrological processes. In this study, rainfall-runoff processes and soil moisture dynamics at different soil depths and slope positions of grassland with two different row spacings (5 cm and 10 cm, respectively, referred to as R5 and R10 were analyzed, by means of a solution of rainfall simulation experiments. Bare land was also considered as a comparison. The results showed that the mechanism of runoff generation was mainly excess infiltration overland flow. The surface runoff amount of R5 plot was greater than that of R10, while the interflow amount of R10 was larger than that of R5 plot, although the differences of the subsurface runoff processes between plots R5 and R10 were little. The effects of rainfall intensity on the surface runoff were significant, but not obvious on the interflow and recession curve, which can be described as a simple exponential equation, with a fitting degree of up to 0.854–0.996. The response of soil moisture to rainfall and evapotranspiration was mainly in the 0–20 cm layer, and the response at the 40 cm layer to rainfall was slower and generally occurred after the rainfall stopped. The upper slope generally responded fastest to rainfall, and the foot of the slope was the slowest. The results presented here could provide insights into understanding the surface and subsurface runoff processes and soil moisture dynamics for grasslands in semi-arid regions.

  11. Effects of Rainfall Intensity and Slope Gradient on Runoff and Soil Moisture Content on Different Growing Stages of Spring Maize

    Directory of Open Access Journals (Sweden)

    Wenbin Mu

    2015-06-01

    Full Text Available The rainfall-runoff process (RRP is an important part of hydrologic process. There is an effective measure to study RRP through artificial rainfall simulation. This paper describes a study on three growing stages (jointing stage, tasseling stage, and mature stage of spring maize in which simulated rainfall events were used to study the effects of various factors (rainfall intensity and slope gradient on the RRP. The RRP was tested with three different rainfall intensities (0.67, 1.00, and 1.67 mm/min and subjected to three different slopes (5°, 15°, and 20° so as to study RRP characteristics in semiarid regions. Regression analysis was used to study the results of this test. The following key results were obtained: (1 With the increase in rainfall intensity and slope, the increasing relationship with rainfall duration, overland flow, and cumulative runoff, respectively, complied with logarithmic and quadratic functions before reaching stable runoff in each growing stage of spring maize; (2 The runoff coefficient increased with the increase in rainfall intensity and slope in each growing stages of spring maize. The relationship between runoff coefficient, slope, rainfall intensity, rainfall duration, antecedent soil moisture, and vegetation coverage was multivariate and nonlinear; (3 The runoff lag time decreased with the increase in rainfall intensity and slope within the same growing stage. In addition, the relationship between runoff lag time, slope, rainfall intensity, antecedent soil moisture, and vegetation coverage could also be expressed by a multivariate nonlinear equation; (4 The descent rate of soil infiltration rate curve increased with the increased rainfall intensity and slope in the same growing stage. Furthermore, by comparing the Kostiakov, Horton, and Philip models, it was found that the Horton infiltration model was the best for estimating soil infiltration rate and cumulative infiltration under the condition of test.

  12. Geometric dependency of Tibetan lakes on glacial runoff

    NARCIS (Netherlands)

    Phan Hien, V.; Lindenbergh, R.C.; Menenti, M.

    2013-01-01

    The Tibetan plateau is an essential source of water for South-East Asia. The run-off from its ~ 34 000 glaciers, which occupy an area of ~ 50 000 km2, feed Tibetan lakes and major Asian rivers like Indus and Brahmaputra. Reported glacial shrinkage likely has its impact on the run-off. Unfortunately,

  13. Geometric dependency of Tibetan lakes on glacial runoff

    NARCIS (Netherlands)

    Phan Hien, V.; Lindenbergh, R.C.; Menenti, M.

    2013-01-01

    The Tibetan Plateau is an essential source of water for Southeast Asia. The runoff from its ~34 000 glaciers, which occupy an area of ~50 000 km2, feeds Tibetan lakes and major Asian rivers like the Indus and Brahmaputra. Reported glacial shrinkage likely has an impact on the runoff. Unfortunately,

  14. Runoff Characterization and Variations at McMurdo Station, Antarctica

    Science.gov (United States)

    2014-05-13

    can potentially migrate into the permeable thawed ground and into the drainage channels during runoff. A review of the runoff data collection and...sensors. 7. We used long nails /stakes to center the sensor in the ditch as best as pos- sible (Figure A4a). 8. We installed stake upstream and

  15. Curve number estimation from Brazilian Cerrado rainfall and runoff data

    Science.gov (United States)

    The Curve Number (CN) method has been widely used to estimate runoff from rainfall events in Brazil, however, CN values for use in the Brazilian savanna (Cerrado) are poorly documented. In this study we used experimental plots to measure natural rainfall-driven rates of runoff under undisturbed Cerr...

  16. Modeling tropical river runoff:A time dependent approach

    Institute of Scientific and Technical Information of China (English)

    Rashmi Nigam; Sudhir Nigam; Sushil K.Mittal

    2014-01-01

    Forecasting of rainfall and subsequent river runoff is important for many operational problems and applications related to hydrol-ogy. Modeling river runoff often requires rigorous mathematical analysis of vast historical data to arrive at reasonable conclusions. In this paper we have applied the stochastic method to characterize and predict river runoff of the perennial Kulfo River in south-ern Ethiopia. The time series analysis based auto regressive integrated moving average (ARIMA) approach is applied to mean monthly runoff data with 10 and 20 years spans. The varying length of the input runoff data is shown to influence the forecasting efficiency of the stochastic process. Preprocessing of the runoff time series data indicated that the data do not follow a seasonal pattern. Our forecasts were made using parsimonious non seasonal ARIMA models and the results were compared to actual 10-year and 20-year mean monthly runoff data of the Kulfo River. Our results indicate that river runoff forecasts based upon the 10-year data are more accurate and efficient than the model based on the 20-year time series.

  17. Specifics of surface runoff contents and treatment in large cities

    Directory of Open Access Journals (Sweden)

    V.N. Chechevichkin

    2014-10-01

    Full Text Available The degree of surface runoff pollution in large cities has been assessed in modern conditions in the case study of production sites of St. Petersburg. Increased content of petroleum derivatives and heavy metal ions both in rainwater runoff and especially in snowmelt runoff has been revealed. It has been established that the composition of infiltration runoff from the newly built-up sites within the city limits commonly depends on their background, especially in the places of former unauthorized dumps, which are usually buried under the building sites. The content of petroleum derivatives in such surface runoff can exceed significantly their content in the runoff of landfills. Most petroleum derivatives appear in the surface runoff as emulsified and associated with suspended matters forms, which are a source of secondary pollution of waste water as it is accumulated in settlers and traps of local waste water treatment plants. Filtrational-sorptive technologies of surface runoff treatment are the most effective and simple in terms of both treatment and waste disposal.

  18. Herbicide volatilization trumps runoff losses, a multi-year investigation

    Science.gov (United States)

    Surface runoff and volatilization are two processes critical to herbicide off-site transport. To determine the relevance of these off-site transport mechanisms, runoff and turbulent vapor fluxes were simultaneously monitored on the same site for eight years. Site location, herbicide formulations, ...

  19. CONTROLLING EXCESS STORM WATER RUNOFF WITH TRADABLE CREDITS

    Science.gov (United States)

    Development that increases the impervious surface in a watershed causes excess storm water runoff (SWR) that has been identified as a major contributor to stream and riparian habitat degradation. Reduction of storm water runoff can be achieved through establishment of a number of...

  20. Separation of drainage runoff during rainfall-runoff episodes using the stable isotope method and drainage water temperature

    Science.gov (United States)

    Zajíček, Antonín; Kvítek, Tomáš; Pomije, Tomáš

    2014-05-01

    Stabile isotopes of 2H 18O and drainage water temperature were used as natural tracers for separation rainfall-runoff event hydrograph on several tile drained catchments located in Bohemian-Moravian Highland, Czech Republic. Small agricultural catchments with drainage systems built in slopes are typical for foothill areas in the Czech and Moravian highland. Often without permanent surface runoff, the drainage systems represent an important portion of runoff and nitrogen leaching out of the catchment. The knowledge of the drainage runoff formation and the origin of its components are prerequisites for formulation of measures leading to improvement of the drainage water quality and reduction of nutrient leaching from the drained catchments. The results have proved presence of event water in the drainage runoff during rainfall-runoff events. The proportion of event water observed in the drainage runoff varied between 15 - 60 % in the summer events and 0 - 50 % in winter events, while the sudden water temperature change was between 0,1 - 4,2 °C (2 - 35 %). The comparison of isotope separation of the drainage runoff and monitoring the drainage water temperature have demonstrated that in all cases of event water detected in the runoff, a rapid change in the drainage water temperature was observed as well. The portion of event water in the runoff grows with the growing change in water temperature. Using component mixing model, it was demonstrated that water temperature can be successfully used at least as a qualitative and with some degree of inaccuracy as a quantitative tracer as well. The drawback of the non-conservative character of this tracer is compensated by both its economic and technical accessibility. The separation results also resemble results of separations at small streams. Together with a similarly high speed of the discharge reaction to beginning of precipitation, it is obvious that the mechanism of surface runoff formation and drainage runoff formation

  1. A comparative analysis of projected impacts of climate change on river runoff from global and catchment-scale hydrological models

    Directory of Open Access Journals (Sweden)

    S. N. Gosling

    2011-01-01

    . However, they are relatively small in comparison to the range of projections across the seven GCMs. Hence, for the six catchments and seven GCMs we considered, climate model structural uncertainty is greater than the uncertainty associated with the type of hydrological model applied. Moreover, shifts in the seasonal cycle of runoff with climate change are represented similarly by both hydrological models, although for some catchments the monthly timing of high and low flows differs. This implies that for studies that seek to quantify and assess the role of climate model uncertainty on catchment-scale runoff, it may be equally as feasible to apply a GHM (Mac-PDM.09 here as it is to apply a CHM, especially when climate modelling uncertainty across the range of available GCMs is as large as it currently is. Whilst the GHM is able to represent the broad climate change signal that is represented by the CHMs, we find however, that for some catchments there are differences between GHMs and CHMs in mean annual runoff due to differences in potential evapotranspiration estimation methods, in the representation of the seasonality of runoff, and in the magnitude of changes in extreme (Q5, Q95 monthly runoff, all of which have implications for future water management issues.

  2. Hillslope soil erosion and runoff model for natural rainfall events

    Institute of Scientific and Technical Information of China (English)

    Zhanyu Zhang; Guohua Zhang; Changqing Zuo; Xiaoyu Pi

    2008-01-01

    By using the momentum theorem and water balance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soil erosion processes. The numerical solution of the model was obtained by adopting the Preissmann format and considering the common solution-determining conditions, from which not only the runoff and soil erosion but also their processes can be described. The model was validated by ten groups of observation data of Soil Conservation Ecological Science and Technology Demonstration Park of Jiangxi Province. Comparisons show that the maximum relative error between simulation and experimental data is about 10.98% for total runoff and 15% for total erosion, 5.2% for runoff process and 6.1% for erosion process, indicating that the model is conceptually realistic and reliable and offers a feasible approach for further studies on the soil erosion process.

  3. MODELING OF STORM WATER RUNOFF FROM GREEN ROOFS

    Directory of Open Access Journals (Sweden)

    Ewa Burszta-Adamiak

    2014-10-01

    Full Text Available Apart from direct measurements, modelling of runoff from green roofs is valuable source of information about effectiveness of this type of structure from hydrological point of view. Among different type of models, the most frequently used are numerical models. They allow to assess the impact of green roofs on decrease and attenuation of runoff, reduction of peak runoff and value of water retention. This paper presents preliminary results of research on computing the rate of runoff from green roofs using GARDENIA model. The analysis has been carried out for selected rainfall events registered during measuring campaign on pilot-scale green roofs. Obtained results are promising and show good fit between observed and simulated runoff.

  4. Extreme Rivers for Future Climates - Simulation Using Spatial Weather Generator

    Science.gov (United States)

    Kuchar, Leszek; Kosierb, Ryszard; Iwański, Sławomir; Jelonek, Leszek

    2014-05-01

    In this paper an application of spatial weather generator for estimation of probability distributions changes of river flows for selected climate change scenarios and different time horizons are presented. The main studies for the Kaczawa river basin located in Southwest region of Poland are carried out. For the estimation of probability distribution river flow, daily data of SR solar radiation, maximum and minimum air temperature, and total precipitation were obtained for sixteen stations of hydrological network from Institute of Meteorology and Water Management. In addition, daily data of flows from 6 closing water-gauges (partial catchments) were collected. Idea of flow simulation in the Kaczawa river catchment for future climate conditions given by different scenario shall be presented in the paper. First, on the basis of 25-years data series (1981-2005) for 16 stations of meteorological network within or around the Kaczawa river catchment basic climatology characteristics required by weather generator are computed. Then, spatial correlations between variables and stations are added to the characteristics. Next, on the basis of information coming from three climate change scenarios (GISS, GFDL and CCCM) for years 2040, 2060 and 2080 basic climatology characteristics are modified. Then, spatial weather generator SWGEN is used to produce 500 years of synthetic data for 16 stations, given time horizon and scenario. The year 2000 as the background of potential changes in river flow is used together with 500 years of synthetic data. Next, generated data are applied to hydrological model Mike SHE to simulate daily flows for closing water-gauges. The flow are evaluated with different temporal step and characterized by pdf functions. The application of spatial weather generator SWGEN combined with hydrological rainfall-runoff model (Mike SHE Ed. 2008) and climate change scenario, gives various possibilities to study changes in the river catchment coming up to 60

  5. Comparison of the treatment performance of hybrid constructed wetlands treating stormwater runoff.

    Science.gov (United States)

    Choi, J Y; Maniquiz-Redillas, M C; Hong, J S; Lee, S Y; Kim, L H

    2015-01-01

    This study was conducted to compare the treatment performance of two hybrid constructed wetlands (CWs) in treating stormwater runoff. The hybrid CWs were composed of a combination of free water surface (FWS) and horizontal subsurface flow (HSSF) CWs. Based on the results, strong correlation exists between potential runoff impacts and stormwater characteristics; however, the low correlations also suggest that not only the monitored parameters contribute to stormwater event mean concentrations (EMC) of pollutants, but other factors should also be considered as well. In the hydraulic and treatment performance of the hybrid CWs, a small surface area to catchment area (SA/CA) ratio, receiving a high concentration of influent EMC, will find it hard to achieve great removal efficiency; also a large SA/CA ratio, receiving low concentration of influent EMC, will find it hard to achieve great removal efficiency. With this, SA/CA ratio and influent characteristics such as EMC or load should be considered among the design factors of CWs. The performance data of the two CWs were used to consider the most cost-effective design of a hybrid CW. The optimum facility capacity (ratio of total runoff volume to storage volume) that is applicable for a target volume reduction and removal efficiency was provided in this study.

  6. Runoff and sediment transport in a degraded area

    Directory of Open Access Journals (Sweden)

    Edivaldo Lopes Thomaz

    2012-02-01

    Full Text Available Gully erosion occurs by the combined action of splash, sheetwash and rill-wash (interrill and rill erosion. These erosion processes have a great capacity for both sediment production and sediment transport. The objectives of this experiment were to evaluate hydrological and sediment transport in a degraded area, severely dissected by gullies; to assess the hydraulic flow characteristics and their aggregate transport capacity; and to measure the initial splash erosion rate. In the study area in Guarapuava, State of Paraná, Brazil (lat 25º 24' S; long 51º24' W; 1034 m asl, the soil was classified as Cambissolo Húmico alumínico, with the following particle-size composition: sand 0.116 kg kg-1; silt 0.180 kg kg-1; and clay 0.704 kg kg-1. The approach of this research was based on microcatchments formed in the ground, to study the hydrological response and sediment transport. A total of eight rill systems were simulated with dry and wet soil. An average rainfall of 33.7 ± 4.0 mm was produced for 35 to 54 min by a rainfall simulator. The equipment was installed, and a trough was placed at the end of the rill to collect sediments and water. During the simulation, the following variables were measured: time to runoff, time to ponding, time of recession, flow velocity, depth, ratio of the initial splash and grain size. The rainsplash of dry topsoil was more than twice as high as under moist conditions (5 g m-2 min-1 and 2 g m-2 min-1, respectively. The characteristics of the flow hydraulics indicate transition from laminar to turbulent flow [Re (Reynolds number 1000-2000]. In addition, it was observed that a flow velocity of 0.12 m s-1 was the threshold for turbulent flow (Re > 2000, especially at the end of the rainfall simulation. The rill flow tended to be subcritical [Fr (Froude Number < 1.0]. The variation in hydrological attributes (infiltration and runoff was lower, while the sediment yield was variable. The erosion in the rill systems was

  7. Mapping dominant runoff processes: an evaluation of different approaches using similarity measures and synthetic runoff simulations

    Science.gov (United States)

    Antonetti, Manuel; Buss, Rahel; Scherrer, Simon; Margreth, Michael; Zappa, Massimiliano

    2016-07-01

    The identification of landscapes with similar hydrological behaviour is useful for runoff and flood predictions in small ungauged catchments. An established method for landscape classification is based on the concept of dominant runoff process (DRP). The various DRP-mapping approaches differ with respect to the time and data required for mapping. Manual approaches based on expert knowledge are reliable but time-consuming, whereas automatic GIS-based approaches are easier to implement but rely on simplifications which restrict their application range. To what extent these simplifications are applicable in other catchments is unclear. More information is also needed on how the different complexities of automatic DRP-mapping approaches affect hydrological simulations. In this paper, three automatic approaches were used to map two catchments on the Swiss Plateau. The resulting maps were compared to reference maps obtained with manual mapping. Measures of agreement and association, a class comparison, and a deviation map were derived. The automatically derived DRP maps were used in synthetic runoff simulations with an adapted version of the PREVAH hydrological model, and simulation results compared with those from simulations using the reference maps. The DRP maps derived with the automatic approach with highest complexity and data requirement were the most similar to the reference maps, while those derived with simplified approaches without original soil information differed significantly in terms of both extent and distribution of the DRPs. The runoff simulations derived from the simpler DRP maps were more uncertain due to inaccuracies in the input data and their coarse resolution, but problems were also linked with the use of topography as a proxy for the storage capacity of soils. The perception of the intensity of the DRP classes also seems to vary among the different authors, and a standardised definition of DRPs is still lacking. Furthermore, we argue not to use

  8. Integration of UAV photogrammetry and SPH modelling of fluids to study runoff on real terrains.

    Science.gov (United States)

    Barreiro, Anxo; Domínguez, Jose M; C Crespo, Alejandro J; González-Jorge, Higinio; Roca, David; Gómez-Gesteira, Moncho

    2014-01-01

    Roads can experience runoff problems due to the intense rain discharge associated to severe storms. Two advanced tools are combined to analyse the interaction of complex water flows with real terrains. UAV (Unmanned Aerial Vehicle) photogrammetry is employed to obtain accurate topographic information on small areas, typically on the order of a few hectares. The Smoothed Particle Hydrodynamics (SPH) technique is applied by means of the DualSPHysics model to compute the trajectory of the water flow during extreme rain events. The use of engineering solutions to palliate flood events is also analysed. The study case simulates how the collected water can flow into a close road and how precautionary measures can be effective to drain water under extreme conditions. The amount of water arriving at the road is calculated under different protection scenarios and the efficiency of a ditch is observed to decrease when sedimentation reduces its depth.

  9. Integration of UAV photogrammetry and SPH modelling of fluids to study runoff on real terrains.

    Directory of Open Access Journals (Sweden)

    Anxo Barreiro

    Full Text Available Roads can experience runoff problems due to the intense rain discharge associated to severe storms. Two advanced tools are combined to analyse the interaction of complex water flows with real terrains. UAV (Unmanned Aerial Vehicle photogrammetry is employed to obtain accurate topographic information on small areas, typically on the order of a few hectares. The Smoothed Particle Hydrodynamics (SPH technique is applied by means of the DualSPHysics model to compute the trajectory of the water flow during extreme rain events. The use of engineering solutions to palliate flood events is also analysed. The study case simulates how the collected water can flow into a close road and how precautionary measures can be effective to drain water under extreme conditions. The amount of water arriving at the road is calculated under different protection scenarios and the efficiency of a ditch is observed to decrease when sedimentation reduces its depth.

  10. What Controls Runoff Ratios in the Congo Basin?

    Science.gov (United States)

    Durand, M. T.; Wei, R.

    2014-12-01

    As the second-largest river globally, the Congo is a critical part of large-scale water, energy, and carbon cycles, and thus has a significant influence on regional climate. The runoff ratio is a coefficient relating runoff to precipitation; it is a parameter that integrates and summarizes upstream hydrologic processes. The Budyko equation depicts the expected partitioning of precipitation (P) into evapotranspiration (E) and runoff (R): P=R+E. It is hypothesized that radiation and precipitation are primary controls of the partitioning process; the effects of the surface control (e.g. soil and slope) are implicitly assumed to be minor. In this study, we explored thirty years of data in the Congo River basin. We will correlate the runoff ratio to a variety of factors, including precipitation, radiation and surface controls (e.g. soil, slope). Global Precipitation Climatology Project (GPCP) by pentad precipitation was used as primary precipitation data, and Climatic Research Unit (CRU) by data was used for comparison. For discharge and drainage area were derived from Global Runoff Data Centre (GRDC), and net radiation is from NASA Earth Observatory. Congo sub basins are analyzed as well. Interannual variability in the runoff ratio for the Congo basin ranged from 0.2 to 0.3, but was generally uncorrelated with precipitation. Runoff is generally uncorrelated with precipitation, whereas evapotranspiration calculated as residual (P-R) is highly correlated with precipitation, with E ranging from 1000 to 1300 mm per year, and P explaining 85% of the variance. Spatial variability was explored by analysis of long-term mean runoff ratio for 10 sub-basins. Spatially, both R and runoff ratio are highly correlated with P, with P explaining 59% of the variance in the runoff ratio. Physical mechanisms to explain these results are explored, and the implications for the Congo's role in partitioning rainfall over sub-Saharan Africa are discussed.

  11. Multidimensional extremal dependence coefficients

    OpenAIRE

    2017-01-01

    Extreme values modeling has attracting the attention of researchers in diverse areas such as the environment, engineering, or finance. Multivariate extreme value distributions are particularly suitable to model the tails of multidimensional phenomena. The analysis of the dependence among multivariate maxima is useful to evaluate risk. Here we present new multivariate extreme value models, as well as, coefficients to assess multivariate extremal dependence.

  12. Analysis of Wave Characteristics in Extreme Seas

    Science.gov (United States)

    1991-01-01

    hydrodynamic ’memory’ which complicate the usual analysis are automatically accounted for." With respect to the basic concepts of this methology , Chapter 4...12 - CHESTER A. POLING - FN FAIR WIND II. Episodic Waves: a. Steep Long- Recurring as every 7th * Observations by officers crested or 9th large wave...Grouped waves in seaway. Second CV-62, SEA-LAND Waves wave frequently largest in McLEAN, LST-1193 group. * Observations by officers from ocean weather

  13. Improving forecasting accuracy of medium and long-term runoff using artificial neural network based on EEMD decomposition.

    Science.gov (United States)

    Wang, Wen-chuan; Chau, Kwok-wing; Qiu, Lin; Chen, Yang-bo

    2015-05-01

    Hydrological time series forecasting is one of the most important applications in modern hydrology, especially for the effective reservoir management. In this research, an artificial neural network (ANN) model coupled with the ensemble empirical mode decomposition (EEMD) is presented for forecasting medium and long-term runoff time series. First, the original runoff time series is decomposed into a finite and often small number of intrinsic mode functions (IMFs) and a residual series using EEMD technique for attaining deeper insight into the data characteristics. Then all IMF components and residue are predicted, respectively, through appropriate ANN models. Finally, the forecasted results of the modeled IMFs and residual series are summed to formulate an ensemble forecast for the original annual runoff series. Two annual reservoir runoff time series from Biuliuhe and Mopanshan in China, are investigated using the developed model based on four performance evaluation measures (RMSE, MAPE, R and NSEC). The results obtained in this work indicate that EEMD can effectively enhance forecasting accuracy and the proposed EEMD-ANN model can attain significant improvement over ANN approach in medium and long-term runoff time series forecasting.

  14. The European Extreme Right and Religious Extremism

    Directory of Open Access Journals (Sweden)

    Jean-Yves Camus

    2007-12-01

    Full Text Available The ideology of the Extreme Right in Western Europe is rooted in Catholic fundamentalism and Counter-Revolutionary ideas. However, the Extreme Right, like all other political families, has had to adjust to an increasingly secular society. The old link between religion and the Extreme Right has thus been broken and in fact already was when Fascism overtook Europe: Fascism was secular, sometimes even anti-religious, in its essence. Although Catholic fundamentalists still retain strong positions within the apparatus of several Extreme Right parties (Front National, the vote for the Extreme Right is generally weak among regular churchgoers and strong among non-believers. In several countries, the vote for the Extreme Right is stronger among Protestant voters than among Catholics, since while Catholics may support Christian-Democratic parties, there are very few political parties linked to Protestant churches. Presently, it also seems that Paganism is becoming the dominant religious creed within the Extreme Right. In a multicultural Europe, non-Christian forms of religious fundamentalism such as Islamism also exist with ideological similarities to the Extreme Right, but this is not sufficient to categorize Islamism as a form of Fascism. Some Islamist groups seek alliances with the Extreme Right on the basis of their common dislike for Israel and the West, globalization and individual freedom of thought.

  15. Extreme skin depth waveguides

    CERN Document Server

    Jahani, Saman

    2014-01-01

    Recently, we introduced a paradigm shift in light confinement strategy and introduced a class of extreme skin depth (e-skid) photonic structures (S. Jahani and Z. Jacob, "Transparent sub-diffraction optics: nanoscale light confinement without metal," Optica 1, 96-100 (2014)). Here, we analytically establish that figures of merit related to light confinement in dielectric waveguides are fundamentally tied to the skin depth of waves in the cladding. We contrast the propagation characteristics of the fundamental mode of e-skid waveguides and conventional waveguides to show that the decay constant in the cladding is dramatically larger in e-skid waveguides, which is the origin of sub-diffraction confinement. Finally, we propose an approach to verify the reduced skin depth in experiment using the decrease in the Goos-H\\"anchen phase shift.

  16. Longitudinal Inter-Comparison of Modeled and Measured West Greenland Ice Sheet Meltwater Runoff Losses (2004-2014)

    Science.gov (United States)

    Moustafa, S.; Rennermalm, A. K.; Tedesco, M.; Mote, T. L.; Koenig, L.; Smith, L. C.; Hagedorn, B.; Overeem, I.; Sletten, R. S.; Mikkelsen, A. B.; Hasholt, B.; Hall, D. K.

    2015-12-01

    Increased surface meltwater runoff, that exits the Greenland ice sheet (GrIS) margin via supra-, en-, and sub-glacial drainage networks into fjords, pro-glacial lakes and rivers, accounts for half or more of total mass loss. Despite its importance, modeled meltwater runoff fluxes are poorly constrained, primarily due to a lack of direct in situ observations. Here, we present the first ever longitudinal (north-south) inter-comparison of a multi-year dataset (2004-2014) of discharge for four drainage basins - Watson, Akuliarusiarsuup Kuua, Naujat Kuat, and North Rivers - along West Greenland. These in situ hydrologic measurements are compared with modeled runoff output from Modèle Atmosphérique Régional (MAR) regional climate model, and the performance of the model is examined. An analysis of the relationship between modeled and actual ice sheet runoff patterns is assessed, and provides insight into the model's ability to capture inter-annual and intra-annual variability, spatiotemporal patterns, and extreme melt events. This study's findings will inform future development and parameterization of ice sheet surface mass balance models.

  17. Rainfall and runoff regime trends in mountain catchments (Case study area: the upper Hron River basin, Slovakia

    Directory of Open Access Journals (Sweden)

    Blahušiaková Andrea

    2015-09-01

    Full Text Available This paper presents an analysis of trends and causes of changes of selected hydroclimatic variables influencing the runoff regime in the upper Hron River basin (Slovakia. Different methods for identifying trends in data series are evaluated and include: simple mass curve analysis, linear regression, frequency analysis of flood events, use of the Indicators of Hydrological Alteration software, and the Mann-Kendall test. Analyses are performed for data from two periods (1931-2010 and 1961-2010. The changes in runoff are significant, especially in terms of lower QMax and 75 percentile values. This fact is also confirmed by the lower frequency and extremity of flood events. The 1980s are considered a turning point in the development of all hydroclimatic variables. The Mann-Kendall test shows a significant decrease in runoff in the winter period. The main causes of runoff decline are: the considerable increase in air temperature, the decrease in snow cover depth and changes in seasonal distribution of precipitation amounts.

  18. Runoff prediction in ungauged basins: synthesis across processes, places and scales

    National Research Council Canada - National Science Library

    Blöschl, Günter

    2013-01-01

    "Predicting water runoff in ungauged water catchment areas is vital to practical applications such as the design of drainage infrastructure and flooding defences, runoff forecasting, and for catchment...

  19. 北京极端气温变化特征及其对城市化的响应%Characteristics of Extreme Temperature Variation and Their Response to Urbanization in Beijing

    Institute of Scientific and Technical Information of China (English)

    郑祚芳

    2011-01-01

    High quality data series are not only the base of our study on climate change, but also the base of the diagnosing, forecasting and valuating climate. Becanse of sites moving and observation method changing, the climate data have been inhomogeneity for a long time. The original data applied in this paper sourced from Beijing meteorological information center, and were homogenized by the method of MASH (Multiple Analysis of Series for Homogenization). The MASH package consists of an interative procedure designed to detect possible break points through mutual comparisons of a number of climate data series, in which each series is not necessarily homogeneous. Possible break points and shifts were detected and adjusted through mutual comparisons among all available series. It can be seen from historical records that, since 1960, the site of Beijing meteorological observatory has been moved for five times, and the moving was taken place in 1965, 1969, 1970, 1981 and 1997 respectively. This paper describes annual mean yearly temperature time series before and after homogenized correction. It can be found that the difference between them is obvious. The discontinuity points in the series are in 1964, 1980 and 1996 respectively. As can be seen that they are all near the year when the site was moved. It illuminates that it is necessary to homogenize the original data. Based on the homogenized daily maximum and minimum temperature in meteorological stations of Beijing during 1960 -2009, the temporal characteristics of extreme temperature variation and the response of extreme temperature to urbanization during 1960 -2009 were studied. The results show that, in Beijing, the wanning rate of annual average temperature was 0.39℃ per 10 a in recent 50 a, and 0.22℃ per 10a higher than the national average level. But the wanning rate was unsymmetrical. The warming rate of annual average minimum temperature was much higher than that of annual average maximum temperature over the

  20. Global sequential design for multi-extreme quality characteristics process%面向多极值质量特性的全局式序贯性实验设计方法

    Institute of Scientific and Technical Information of China (English)

    崔庆安

    2012-01-01

    For the global modeling and parameter optimization of manufacturing process feat