Variation in MERRA-2 aerosol optical depth over the Yangtze River Delta from 1980 to 2016

Science.gov (United States)

Sun, Enwei; Che, Huizheng; Xu, Xiaofeng; Wang, Zhenzhu; Lu, Chunsong; Gui, Ke; Zhao, Hujia; Zheng, Yu; Wang, Yaqiang; Wang, Hong; Sun, Tianze; Liang, Yuanxin; Li, Xiaopan; Sheng, Zhizhong; An, Linchang; Zhang, Xiaoye; Shi, Guangyu

2018-05-01

In this study, 765 instantaneous MERRA-2 (second Modern-Era Retrospective analysis for Research and Applications) aerosol optical depth (AOD) values at 550 nm were compared with those of a sky radiometer in Hefei (31.90° N, 117.17° E) for the different seasons from March 2007 to February 2010. The correlation coefficients (R) were 0.88, 0.83, 0.88, and 0.80 in spring, summer, autumn, and winter, respectively. The MERRA-2 AOD is also compared with MODIS Aqua AOD in the entire Yangtze River Delta, and good agreement has been obtained. The MERRA-2 AOD product was used to analyze the spatial distribution and temporal variation of the annual, seasonal and monthly means of the AOD over the Yangtze River Delta region from 1980 to 2016 (37 years). The mean values of the MERRA-2 AOD during the study period show that the AOD (between 0.45 and 0.55) in the northern area of the Yangtze River Delta was higher than that (between 0.30 and 0.45) of the southern area. The northwest part of the Yangtze River Delta had the highest mean AOD values (between 0.50 and 0.55). The AOD increased slowly in the 1980s and 1990s, followed by a rapid increase between 2001 and 2010. An AOD decrease can be seen from 2011 to 2016. The mean AOD in each month is discussed. High AOD was observed in March, April, and June, while low AOD could be seen in September, October, November, and December. Three different area types (large cities, medium-sized cities, and remote areas) had nearly the same annual AOD variation. Large cities had the highest AOD (about 0.48), while remote areas had the lowest (about 0.42). In summer, the AOD in remote areas was much lower than that in cities. The AOD variational trend over the Yangtze River Delta was studied during two periods. The increasing trend could be seen over the entire Yangtze River Delta in each month from 1980 to 2009. A decreasing trend was found all over the Yangtze River Delta in January, February, March, July, October, and November, whereas in

Tidal controls on river delta morphology

NARCIS (Netherlands)

Hoitink, A.J.F.; Wang, Z.B.; Vermeulen, B.; Huismans, Y.; Kästner, K.

2017-01-01

River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world's largest deltas intensifies. Harbour development, construction of flood defences, sand mining and

Tidal controls on river delta morphology

NARCIS (Netherlands)

Hoitink, A.J.F.; Wang, Zhengbing; Vermeulen, B.; Huismans, Y; Kästner, K

River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and

Community-based restoration of desert wetlands: the case of the Colorado River delta

Science.gov (United States)

Osvel Hinojosa-Huerta; Mark Briggs; Yamilett Carrillo-Guerroro; Edward P. Glenn; Miriam Lara-Flores; Martha Roman-Rodriguez

2005-01-01

Wetland areas have been drastically reduced through the Pacific Flyway and the Sonoran Desert, with severe consequences for avian populations. In the Colorado River delta, wetlands have been reduced by 80 percent due to water management practices in the Colorado River basin. However, excess flows and agricultural drainage water has restored some areas, providing...

Morphodynamics of a cyclic prograding delta: the Red River, Vietnam

NARCIS (Netherlands)

Maren, D.S. van

2004-01-01

River deltas are inhabited by over 60% of the world population, and are, consequently, of paramount agricultural and economical importance. They constitute unique wetland envi ronments which gives river deltas ecological importance as well. Additionally, many deltas contain large accumulations of

Shallow stratigraphy of the Skagit River Delta, Washington, derived from sediment cores

Science.gov (United States)

Grossman, Eric E.; George, Douglas A.; Lam, Angela

2011-01-01

Sedimentologic analyses of 21 sediment cores, ranging from 0.4 to 9.6 m in length, reveal that the shallow geologic framework of the Skagit River Delta, western Washington, United States, has changed significantly since 1850. The cores collected from elevations of 3.94 to -2.41 m (relative to mean lower low water) along four cross-shore transects between the emergent marsh and delta front show relatively similar environmental changes across an area spanning ~75 km2. Offshore of the present North Fork Skagit River and South Fork Skagit River mouths where river discharge is focused by diked channels through the delta, the entire 5–7-km-wide tidal flats are covered with 1–2 m of cross-bedded medium-to-coarse sands. The bottoms of cores, collected in these areas are composed of mud. A sharp transition from mud to a cross-bedded sand unit indicates that the tidal flats changed abruptly from a calm environment to an energetic one. This is in stark contrast to the Martha's Bay tidal flats north of the Skagit Bay jetty that was completed in the 1940s to protect the newly constructed Swinomish Channel from flooding and sedimentation. North of the jetty, mud ranging from 1 to 2 m thick drapes a previously silt- and sand-rich tidal flat. The silty sand is a sediment facies that would be expected there where North Fork Skagit River sedimentation occurred prior to jetty emplacement. This report describes the compositional and textural properties of the sediment cores by using geophysical, photographic, x-radiography, and standard sediment grain-size and carbon-analytical methods. The findings help to characterize benthic habitat structure and sediment transport processes and the environmental changes that have occurred across the nearshore of the Skagit River Delta. The findings will be useful for quantifying changes to nearshore marine resources, including impacts resulting from diking, river-delta channelization, shoreline development, and natural variations in fluvial

Assessing impact of urbanization on river water quality in the Pearl River Delta Economic Zone, China.

Science.gov (United States)

Ouyang, Tingping; Zhu, Zhaoyu; Kuang, Yaoqiu

2006-09-01

The Pearl River Delta Economic Zone is one of the most developed regions in China. It has been undergoing a rapid urbanization since the reformation and opening of China in 1978. This process plays a significant impact on the urban environment, particularly river water quality. The main goal of this present study is to assess the impact of urban activities especially urbanization on river water quality for the study area. Some Landsat TM images from 2000 were used to map the areas for different pollution levels of urban river sections for the study area. In addition, an improved equalized synthetic pollution index method was utilized to assess the field analytical results. The results indicate that there is a positive correlation between the rapidity of urbanization and the pollution levels of urban river water. Compared to the rural river water, urban river water was polluted more seriously. During the urban development process, urbanization and urban activities had a significant negative impact on the river water quality.

Human influence on the sedimentation in the delta of the river Kyroenjoki, western Finland

International Nuclear Information System (INIS)

Heikkilae, R.

1999-01-01

Human activities in the drainage basin of the river Kyroenjoki, Western Finland, have greatly influenced the hydrology and sediment load of the river. The main factors have been agriculture, forestry, peat mining and watercourse works. Also sewage from towns and small-scale industry has increased the nutrient transport to the delta of the river. The aim of this study was to assess factors influencing the sedimentary conditions, sediment accumulation rates and sediment quality in the delta of the river. The sediment studies were carried out in 1983-1988 in the delta. The drainage basin of the river Kyroenjoki covers 5030 km 2 in the middle boreal vegetation zone. The river channel has been cleared many times since the 1600s to prevent floods and to allow agriculture on the adjoining land. Extensive cultivation of the paludified Litorina clay plains along the river has also continued for centuries. Forestry drainage of mires covered almost all the mires of the basin in 1960s and 1970s. Since 1963, four reservoirs and four hydroelectric power stations with daily regulation of water have been built. The estuary of the river was echo sounded, and on the basis of the results the delta was delimited, and areas of accumulation and erosion were separated. Samples of the sediment surface from 65 sites and long cores from 8 sites in the delta of the river Kyroenjoki were analysed for water content, organic content, C, N, P, Ca, Fe, Mn, Pb, Cu, Zn, Cd and Hg. The sediment from Nabbviken Bay in the delta was dated on the basis of annual laminae. The chemical analyses showed that the organic matter and heavy metal content have increased during recent decades. The heavy metal content was clearly lower than in areas polluted by industrial works. The phosphorus content of the sediment was very high. The sedimentation rate in the delta increased from the 1930s to the 1950s, due to increased land reclamation for agriculture and forestry drainage, and then decreased in the beginning

Soil Organic Carbon Stocks in Arctic Deltaic Sediments: Investigations in the Lena River Delta.

Science.gov (United States)

Zubrzycki, S.; Kutzbach, L.; Desyatkin, A.; Pfeiffer, E.-M.

2012-04-01

The soil organic carbon stock (SSOC) of deltaic sediments in arctic permafrost regions is known to be significant but is insufficiently investigated so far. Previous SSOC studies were conducted mainly in the comparatively well studied Mackenzie River Delta (area: 13,000 km2) in Canada. The few studies from other arctic delta regions report only the gravimetric carbon (C) contents and are limited to the active layer depth at the time of sampling. Since C deposits in permafrost regions are likely to become a future C source, more detailed investigations of the presently frozen likely carbon-rich sediment and soil layers in other arctic delta regions are of importance. Our investigations were performed on Samoylov Island in the southern-central part of the Lena River Delta (32,000 km2) which is the largest arctic delta and the fifth largest delta worldwide. Samoylov Island is representative for the Lena River Delta's first terrace and the active floodplains. Within this study a new portable Snow-Ice-Permafrost-Research-Establishment (SIPRE) auger was used during a spring field session to obtain 1 m deep frozen soil cores (n = 37) distributed over all known soil and vegetation units. These cores are analyzed for bulk contents of nitrogen (N) and C, ice content and bulk density (BD) and to determine the SSOC including the rarely investigated currently permanently frozen layers up to 1 m depth on Samoylov Island. Our study provides evidence for high SSOC for a depth of 1 m for the investigated area ranging between 6 kg m2 and 54 kg m2. Considering the spatial extent of different soil units on the two geomorphological units of Samoylov Island, the area-weighted average SSOC were 31 kg m2 (n = 31) for the first terrace and 15 kg m2 (n = 6) for the active floodplain. For the correspondent soil units of Turbels and Orthels in circumpolar permafrost regions, Tarnocai et al. 2009 reported a mean SSOC of 27 kg m2 (min: 0.1 kg m2, max: 126 kg m2) for a depth of 1 m. For up

Magnitude of arsenic pollution in the Mekong and Red River Deltas - Cambodia and Vietnam

International Nuclear Information System (INIS)

Berg, Michael; Stengel, Caroline; Trang, Pham Thi Kim; Hung Viet, Pham; Sampson, Mickey L.; Leng, Moniphea; Samreth, Sopheap; Fredericks, David

2007-01-01

Large alluvial deltas of the Mekong River in southern Vietnam and Cambodia and the Red River in northern Vietnam have groundwaters that are exploited for drinking water by private tube-wells, which are of increasing demand since the mid-1990s. This paper presents an overview of groundwater arsenic pollution in the Mekong delta: arsenic concentrations ranged from 1-1610 μg/L in Cambodia (average 217 μg/L) and 1-845 μg/L in southern Vietnam (average 39 μg/L), respectively. It also evaluates the situation in Red River delta where groundwater arsenic concentrations vary from 1-3050 μg/L (average 159 μg/L). In addition to rural areas, the drinking water supply of the city of Hanoi has elevated arsenic concentrations. The sediments of 12-40 m deep cores from the Red River delta contain arsenic levels of 2-33 μg/g (average 7 μg/g, dry weight) and show a remarkable correlation with sediment-bound iron. In all three areas, the groundwater arsenic pollution seem to be of natural origin and caused by reductive dissolution of arsenic-bearing iron phases buried in aquifers. The population at risk of chronic arsenic poisoning is estimated to be 10 million in the Red River delta and 0.5-1 million in the Mekong delta. A subset of hair samples collected in Vietnam and Cambodia from residents drinking groundwater with arsenic levels > 50 μg/L have a significantly higher arsenic content than control groups (< 50 μg/L). Few cases of arsenic related health problems are recognized in the study areas compared to Bangladesh and West Bengal. This difference probably relates to arsenic contaminated tube-well water only being used substantially over the past 7 to 10 years in Vietnam and Cambodia. Because symptoms of chronic arsenic poisoning usually take more than 10 years to develop, the number of future arsenic related ailments in Cambodia and Vietnam is likely to increase. Early mitigation measures should be a high priority

Optimal location of dry ports in the Pan-Pearl River Delta

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Wu Qitao

2017-01-01

Full Text Available Dry ports have become a very important part of globalization and a cornerstone in port competitiveness. Based on the analytic hierarchy process, this paper established the dry port index system to evaluate the potential location of dry ports linked to the port system in the Pearl River Delta, in a case study covering 115 cities in the Pan - Pearl River Delta. The results show that it is optimal to locate 21 dry ports in the research region, and each dry port serves different areas. There are 4 optimal transport corridors for the dry port logistic network, including Guangzhou- Kunming transport corridor, Guangzhou-Chengdu transport corridor, Guangzhou-Changsha transport corridor and Shenzhen-Nanchang transport corridor.

Experimental river delta size set by multiple floods and backwater hydrodynamics.

Science.gov (United States)

Ganti, Vamsi; Chadwick, Austin J; Hassenruck-Gudipati, Hima J; Fuller, Brian M; Lamb, Michael P

2016-05-01

River deltas worldwide are currently under threat of drowning and destruction by sea-level rise, subsidence, and oceanic storms, highlighting the need to quantify their growth processes. Deltas are built through construction of sediment lobes, and emerging theories suggest that the size of delta lobes scales with backwater hydrodynamics, but these ideas are difficult to test on natural deltas that evolve slowly. We show results of the first laboratory delta built through successive deposition of lobes that maintain a constant size. We show that the characteristic size of delta lobes emerges because of a preferential avulsion node-the location where the river course periodically and abruptly shifts-that remains fixed spatially relative to the prograding shoreline. The preferential avulsion node in our experiments is a consequence of multiple river floods and Froude-subcritical flows that produce persistent nonuniform flows and a peak in net channel deposition within the backwater zone of the coastal river. In contrast, experimental deltas without multiple floods produce flows with uniform velocities and delta lobes that lack a characteristic size. Results have broad applications to sustainable management of deltas and for decoding their stratigraphic record on Earth and Mars.

Holocene evolution of the Liaohe Delta, a tide-dominated delta formed by multiple rivers in Northeast China

Science.gov (United States)

He, Lei; Xue, Chunting; Ye, Siyuan; Laws, Edward Allen; Yuan, Hongming; Yang, Shixiong; Du, Xiaolei

2018-02-01

The Liaohe Delta in Northeast China is one of the ecologically important estuarine deltas in China. It has been formed via the accumulation of sediment discharged by four rivers in the Liaohe Plain that enter Liaodong Bay. Twenty-seven 30-40 m long cores recovered from the Liaohe Plain and Liaodong Bay were analyzed for sedimentary characteristics, grain size, foraminifera species, and ages determined by accelerator mass spectrometry (AMS) 14C to document the stratigraphical sequence and the spatio-temporal evolution of the Liaohe Delta. Our results revealed that the sedimentary environments have evolved from fluvial, tidal flat/estuarine, to neritic and finally to a deltaic environment since the Late Pleistocene. The Holocene transgression arrived at the present coastline at ∼8500 cal a BP and flooded the maximum area of land at ∼7000 cal a BP. A deltaic environment prevailed in this area after 7000 cal a BP. Bounded by the modern Liaohe River mouth, the present deltaic sedimentary system can be divided into the eastern and western components. The rate of seaward progradation of the eastern paleocoastline was estimated to be ∼8.6 m/a since 7000 cal a BP; the eastern cores in the present coastline began receiving the deltaic sediments at ∼5000 cal a BP. The rate of seaward progradation of the western paleocoastline was estimated to be only ∼2.8 m/a since 7000 cal a BP. The coastline on the western side began accumulating deltaic sediments about 2000 years later than the eastern coastline. Depocenter shifting was hypothesized to be the reason for the spatial differences in the sedimentary processes. However, the change of sediment fluxes of the western rivers due to climate changes and ancient human impacts might be the reason for the differences of the temporal evolution of the eastern and western sedimentary systems in the Liaohe Delta.

Recent Niger Delta shoreline response to Niger River hydrology: Conflict between forces of Nature and Humans

Science.gov (United States)

Dada, Olusegun A.; Li, Guangxue; Qiao, Lulu; Asiwaju-Bello, Yinusa Ayodele; Anifowose, Adeleye Yekini Biodun

2018-03-01

The Niger River Delta is a prolific hydrocarbon province and a mega-delta of economic and environmental relevance. To understand patterns of its recent shoreline evolution (1923-2013) in response to the Niger River hydrology, and establish the role played by forces of Nature and Human, available topographic and satellite remote sensing data, combined with hydro-climatic (rainfall and runoff) data were analyzed. Results indicate that the entire delta coastline dramatically receded: 82% of the >400 km-long coast retreated, during the period 1950-1987; and 69% between 2007 and 2012. Prior to 1950, there was a continuation of seaward advancement along 53-74% of the delta coast. The 1950-1987 shoreline recession coincided with occurrences of two major events in the Niger River basin; these are downward trends in hydro-climatic conditions (the great droughts of the 1970s-1980s), and dam construction on the Lower Niger River at Kainji (1964-1968). The 2007-2012 event corresponded with the extensive channel dredging during 2009-2012 in the Lower Niger River from the coastal town of Warri in the south to Baro in the north. Remarkably, the largest net shoreline advancement recorded in 74% of the entire delta area occurred within a year (2012-2013), which we link to increased sediment supply to the coast caused by the '2012' floods, adjudged the worst floods in the entire Niger River Basin in the last few decades. With both anthropogenic and environmental factors inducing delta evolution, only innovative river and coastal management can determine the fortune of the future coastal development of the Niger Delta.

Contamination of persistent organochlorines in sediments from Mekong River Delta, South Vietnam

Energy Technology Data Exchange (ETDEWEB)

Hung, Minh Nguyen; Kajiwara, Natsuko; Kunisue, Tatsuya; Subramanian, A.; Iwata, Hisato; Tanabe, Shinsuke [Ehime Univ., Matsuyama (Japan). Center for Marine Environmental Studies; Hung, Viet Pham [Hanoi National Univ., Hanoi (Viet Nam); Cach, Tuyen Bui [Univ. for Agriculture and Forestry, Hochiminh (Viet Nam)

2004-09-15

Mekong River is the longest river in southeastern Asia, which flows a distance of almost 4800 km from China through Myanmar, Thailand, Laos, Cambodia and Vietnam. The Mekong River basin with an area of nearly 800 thousand square kilometers is an important habitat for approximately 60 million people. Mekong River delta in South Vietnam, which is inhabited by about 20 million people, is one of the most highly productive agriculture lands in the world. Rice production is major economical sector in Mekong delta contributing half of the rice production in Vietnam - approximately 35 million tons annually. On the other hand, development of agriculture in Mekong delta raised some concern on environmental quality and disturbance on ecosystem. For example, intensive use of organochlorine (OC) insecticides such as DDTs, chlordanes, HCHs may lead to considerable residues in the agriculture land. Moreover, relative persistence of such chemicals together with natural processes like evaporation and run-off, might enhance their ubiquitous distribution in environment, food chains and eventually bio-accumulate in humans. In Vietnam, despite official ban on the usage of OCs on 1995, there have been evidences of recent uses of such chemicals, particularly DDT, throughout the country. It can be anticipated that similar situation may occur in Mekong River delta due to high population density and intensive agriculture activities in this region. Despite this fact, no comprehensive study, to evaluate the status of contamination by persistent OCs in this region, has been made in recent years. In this study, we collected sediments from different locations along Mekong River and determined the concentrations of persistent OCs such as DDTs, HCHs, CHLs, HCB and PCBs in order to elucidate the recent contamination status, their usage pattern as well as to evaluate potential pollution sources of these chemicals to the river.

Distribution and Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in Forest Soils from Urban to Rural Areas in the Pearl River Delta of Southern China

Science.gov (United States)

Xiao, Yihua; Tong, Fuchun; Kuang, Yuanwen; Chen, Bufeng

2014-01-01

The upper layer of forest soils (0–20 cm depth) were collected from urban, suburban, and rural areas in the Pearl River Delta of Southern China to estimate the distribution and the possible sources of polycyclic aromatic hydrocarbons (PAHs). Total concentrations of PAHs in the forest soils decreased significantly along the urban–suburban–rural gradient, indicating the influence of anthropogenic emissions on the PAH distribution in forest soils. High and low molecular weight PAHs dominated in the urban and rural forest soils, respectively, implying the difference in emission sources between the areas. The values of PAH isomeric diagnostic ratios indicated that forest soil PAHs were mainly originated from traffic emissions, mixed sources and coal/wood combustion in the urban, suburban and rural areas, respectively. Principal component analysis revealed that traffic emissions, coal burning and residential biomass combustion were the three primary contributors to forest soil PAHs in the Pearl River Delta. Long range transportation of PAHs via atmosphere from urban area might also impact the PAHs distribution in the forest soils of rural area. PMID:24599040

The evolution of a subaqueous delta in the Anthropocene: A stratigraphic investigation of the Brazos River delta, TX USA

Science.gov (United States)

Carlin, Joseph A.; Dellapenna, Timothy M.

2015-12-01

Globally, deltas are increasingly threatened by anthropogenic activities. As a result, deltas now evolve through the combined effects of natural and human-induced processes occurring throughout the fluvial-deltaic system. The Brazos River delta, located along the Texas coast in the northwestern Gulf of Mexico, and its watershed have been impacted by direct and indirect human activities since the late 19th century. This provides an opportunity to investigate how such alterations have shaped the evolution of a delta in the Anthropocene, a time when humans are drivers of geological change. Historic alteration to the delta and watershed include extensive agricultural activity, jetty construction at the mouth in the late 1890s, mouth diversion ~10 km to the southwest in 1929, and reservoir construction throughout the early and mid 20th Century. Three subaerial deltaic geometries provided the framework to connect subaerial deltaic responses, to the anthropogenic alterations, to the resulting stratigraphic characteristics observed in the subaqueous delta. This study utilized high-resolution geophysical data (swath bathymetry, side scan sonar, CHIRP subbottom profiling) on the subaqueous delta to investigate the subaqueous delta stratigraphy and infer the processes that shaped the deltaic record over time. The results showed distinct areas across the subaqueous delta that were dominated by erosion and deposition. Erosional areas corresponded to earlier growth phase depocenters being exposed at the surface, while the depositional areas corresponded to areas with the most recent growth phase depocenter overlying the earlier depocenters. These results highlight that the subaqueous depocenter has migrated westward over time, consistent with the observed changes to the subaerial delta. Additionally, the data showed that evidence for these past growth phases and depocenters may be preserved within the subaqueous delta, even after subaerial portions of the delta returned to pre

Outbreaks of the brown planthopper Nilaparvata lugens (Stål) in the Yangtze River Delta: immigration or local reproduction?

Science.gov (United States)

Hu, Gao; Lu, Fang; Zhai, Bao-Ping; Lu, Ming-Hong; Liu, Wan-Cai; Zhu, Feng; Wu, Xiang-Wen; Chen, Gui-Hua; Zhang, Xiao-Xi

2014-01-01

An effective control strategy for migratory pests is difficult to implement because the cause of infestation (i.e., immigration or local reproduction) is often not established. In particular, the outbreak mechanisms of the brown planthopper, Nilaparvata lugens (Stål), an insect causing massive losses in rice fields in the Yangtze River Delta in China, are frequently unclear. Field surveys of N. lugens were performed in Jiangsu and Zhejiang Provinces in 2008 to 2010 and related historical data from 2003 onwards were collected and analyzed to clarify the cause of these infestations. Results showed that outbreaks of N. lugens in the Yangtze River Delta were mostly associated with an extremely high increase in population. Thus, reproduction rather than immigration from distant sources were the cause of the infestations. Although mass migration occurred late in the season (late August and early September), the source areas of N. lugens catches in the Yangtze River Delta were mainly located in nearby areas, including the Yangtze River Delta itself, Anhui and northern Jiangxi Provinces. These regions collectively form the lower-middle reaches of the Yangtze River, and the late migration can thus be considered as an internal bioflow within one population.

Outbreaks of the Brown Planthopper Nilaparvata lugens (Stål) in the Yangtze River Delta: Immigration or Local Reproduction?

Science.gov (United States)

Zhai, Bao-Ping; Lu, Ming-Hong; Liu, Wan-Cai; Zhu, Feng; Wu, Xiang-Wen; Chen, Gui-Hua; Zhang, Xiao-Xi

2014-01-01

An effective control strategy for migratory pests is difficult to implement because the cause of infestation (i.e., immigration or local reproduction) is often not established. In particular, the outbreak mechanisms of the brown planthopper, Nilaparvata lugens (Stål), an insect causing massive losses in rice fields in the Yangtze River Delta in China, are frequently unclear. Field surveys of N. lugens were performed in Jiangsu and Zhejiang Provinces in 2008 to 2010 and related historical data from 2003 onwards were collected and analyzed to clarify the cause of these infestations. Results showed that outbreaks of N. lugens in the Yangtze River Delta were mostly associated with an extremely high increase in population. Thus, reproduction rather than immigration from distant sources were the cause of the infestations. Although mass migration occurred late in the season (late August and early September), the source areas of N. lugens catches in the Yangtze River Delta were mainly located in nearby areas, including the Yangtze River Delta itself, Anhui and northern Jiangxi Provinces. These regions collectively form the lower-middle reaches of the Yangtze River, and the late migration can thus be considered as an internal bioflow within one population. PMID:24558459

Analysis of relationships between land surface temperature and land use changes in the Yellow River Delta

Science.gov (United States)

Ning, Jicai; Gao, Zhiqiang; Meng, Ran; Xu, Fuxiang; Gao, Meng

2018-06-01

This study analyzed land use and land cover changes and their impact on land surface temperature using Landsat 5 Thematic Mapper and Landsat 8 Operational Land Imager and Thermal Infrared Sensor imagery of the Yellow River Delta. Six Landsat images comprising two time series were used to calculate the land surface temperature and correlated vegetation indices. The Yellow River Delta area has expanded substantially because of the deposited sediment carried from upstream reaches of the river. Between 1986 and 2015, approximately 35% of the land use area of the Yellow River Delta has been transformed into salterns and aquaculture ponds. Overall, land use conversion has occurred primarily from poorly utilized land into highly utilized land. To analyze the variation of land surface temperature, a mono-window algorithm was applied to retrieve the regional land surface temperature. The results showed bilinear correlation between land surface temperature and the vegetation indices (i.e., Normalized Difference Vegetation Index, Adjusted-Normalized Vegetation Index, Soil-Adjusted Vegetation Index, and Modified Soil-Adjusted Vegetation Index). Generally, values of the vegetation indices greater than the inflection point mean the land surface temperature and the vegetation indices are correlated negatively, and vice versa. Land surface temperature in coastal areas is affected considerably by local seawater temperature and weather conditions.

Cohesive Sedimentary Processes on River-Dominated Deltas: New Perspectives from the Mississippi River Delta Front, Gulf of Mexico

Science.gov (United States)

Bentley, S. J.; Keller, G. P.; Obelcz, J.; Maloney, J. M.; Xu, K.; Georgiou, I. Y.; Miner, M. D.

2016-12-01

On river deltas dominated by proximal sediment accumulation (Mississippi, Huang He, others), the delta front region is commonly dominated by rapid accumulation of cohesive fluvial sediments, and mass-wasting processes that remobilize recently deposited sediments. Mass transport is preconditioned in sediments by high water content, biogenic gas production, over steepening, and is commonly triggered by strong wave loading and other processes. This understanding is based on extensive field studies in the 1970's and 80's. Recent studies of the Mississippi River Delta Front are yielding new perspectives on these processes, in a time of anthropogenically reduced sediment loads, rising sea level, and catastrophic deltaic land loss. We have synthesized many industry data sets collected since ca. 1980, and conducted new pilot field and modeling studies of sedimentary and morphodynamic processes. These efforts have yielded several key findings that diverge from historical understanding of this dynamic setting. First, delta distributary mouths have ceased seaward progradation, ending patterns that have been documented since the 18th century. Second, despite reduced sediment supply, offshore mass transport continues, yielding vertical displacements at rates of 1 m/y. This displacement is apparently forced by wave loading from storm events of near-annual return period, rather than major hurricanes that have been the focus of most previous studies. Third, core analysis indicates that this vertical displacement is occurring along failure planes >3 m in the seabed, rather than in more recently deposited sediments closer to the sediment-water interface. These seabed morphodynamics have the potential to destabilize both nearshore navigation infrastructure, and seabed hydrocarbon infrastructure offshore. As well, these findings raise more questions regarding the future seabed evolution offshore of major river deltas, in response to anthropogenic and climatic forcing.

Dendroclimatology of the Slave River Delta, Northwest Territories, Canada

Science.gov (United States)

Jarvis, S.; Buhay, W. M.; Blair, D.; Tardif, J.; Bailey, D.

2004-05-01

It is well documented that changing hydrological conditions impact delta ecosystems. Such changes can also affect local inhabitants who have historical connections to the area and its resources. During the summer of 2003 a multifaceted paleo-environmental project was initiated to reconstruct the frequencies of floods and droughts in the Slave River Delta (SRD), Northwest Territories, Canada. The project goal is to forecast future hydrological and ecological conditions in the SRD in light of anticipated climate change and increasing demand on water resources. With the intent of expanding the climate history of the SRD, this particular aspect of the project will employ white spruce tree-ring chronologies constructed from six sites visited within the delta. Work is currently in progress to build a master chronology estimated to span over 300 years. In addition, a climate model for the SRD is also being developed and will be highlighted.

Practicality of marine protected areas - Can there be solutions for the River Indus delta?

Science.gov (United States)

Kidwai, Samina; Fanning, Paul; Ahmed, Waqar; Tabrez, Mohsin; Zhang, Jing; Khan, Muhammad Wasim

2016-12-01

The River Indus delta is the most prominent feature on the Pakistan coast. Owing to its prominence, mangrove ecosystem, historical, ecological and economic significance it is also a proposed Marine Protected Area (MPA). Currently there are no designated MPAs in Pakistan. This paper presents findings of the Fishery Resource Appraisal Project of Pakistan (FRAPP) a fishery stock assessment carried out for the pelagic and demersal fishery resource of Pakistan from 2009 to 2015 and the Creek Survey Program (CSP) which was part of FRAPP. And discusses how the delta suffers from physical stress. The observations from FRAPP indicates deterioration in the mangrove ecosystem, that are evident in the form of loss of biodiversity and biological productivity. The 600 observations from 10 major creeks showed that trawl catches were a mix of generally small size fish and shrimp. Catches averaged less than 1 kg per tow in all the creeks sampled. Catch weights were somewhat higher in Isaro, WadiKhuddi, Paitiani, Dabbo, Richaal Creeks all of which were near mangrove areas and open sea. The most frequently occurring species of shrimps caught in the trawls belonged to 7 major taxa. The Khobar Creek and Upper Wari Creek are notable for the high rates of occurrence of every group except the Caridea. They are also the only two creeks where the freshwater family Paleomonidae is common. The size composition of the important penaeid family of shrimps in all study areas combined suggests that the smallest shrimps (0.5-1.5 cm carapace length CL) enter the creeks in February/March and adults (5-6 cm CL) move out again 6-12 months later. Four species of Penaeus (monodon, japonicus, semisulcatus, merguiensis), two species of Metapenaeus (monoceros, affinis), Parapeneoposis stylifera and Solenosera sp. were caught, all in low abundance, less than 0.5 Kg tow-1. The shrimp catches in the area off the Sindh coast, the catches averaged 4.30 ± 13.40 kg h-1 on the inner shelf (20-50 m) and 1.7 ± 6

Effect of tides, river flow, and gate operations on entrainment of juvenile salmon into the interior Sacramento–San Joaquin River Delta

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Perry, Russell W.; Brandes, Patricia L.; Burau, Jon R.; Sandstrom, Philip T.; Skalski, John R.

2015-01-01

Juvenile Chinook Salmon Oncorhynchus tshawytscha emigrating from natal tributaries of the Sacramento River, California, must negotiate the Sacramento-San Joaquin River Delta (hereafter, the Delta), a complex network of natural and man-made channels linking the Sacramento River with San Francisco Bay. Fish that enter the interior and southern Delta—the region to the south of the Sacramento River where water pumping stations are located—survive at a lower rate than fish that use alternative migration routes. Consequently, total survival decreases as the fraction of the population entering the interior Delta increases, thus spurring management actions to reduce the proportion of fish that are entrained into the interior Delta. To better inform management actions, we modeled entrainment probability as a function of hydrodynamic variables. We fitted alternative entrainment models to telemetry data that identified when tagged fish in the Sacramento River entered two river channels leading to the interior Delta (Georgiana Slough and the gated Delta Cross Channel). We found that the probability of entrainment into the interior Delta through both channels depended strongly on the river flow and tidal stage at the time of fish arrival at the river junction. Fish that arrived during ebb tides had a low entrainment probability, whereas fish that arrived during flood tides (i.e., when the river's flow was reversed) had a high probability of entering the interior Delta. We coupled our entrainment model with a flow simulation model to evaluate the effect of nighttime closures of the Delta Cross Channel gates on the daily probability of fish entrainment into the interior Delta. Relative to 24-h gate closures, nighttime closures increased daily entrainment probability by 3 percentage points on average if fish arrived at the river junction uniformly throughout the day and by only 1.3 percentage points if 85% of fish arrived at night. We illustrate how our model can be used to

Monitoring of Deep Foundation Pit Support and Construction Process in Soft Soil Area of Pearl River Delta

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Weiyi, Xie; Pengcheng

2018-03-01

The deep foundation pit supporting technology in the soft soil area of the Pearl River Delta is more complicated, and many factors influence and restrict it. In this project as an example, according to the geological conditions and the surrounding circumstances, the main foundation using bored piles and pre-stressed anchor cable supporting structure + five axis cement mixing pile curtain supporting form; partial use of double row piles supporting structure + five axis cement mixing pile curtain support type. Through the monitoring results of construction show that the foundation pit, the indicators of environmental changes are in the design range, the supporting scheme of deep foundation pit technology is feasible and reliable.

Entropy and optimality in river deltas

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Tejedor, Alejandro; Longjas, Anthony; Edmonds, Douglas A.; Zaliapin, Ilya; Georgiou, Tryphon T.; Rinaldo, Andrea; Foufoula-Georgiou, Efi

2017-10-01

The form and function of river deltas is intricately linked to the evolving structure of their channel networks, which controls how effectively deltas are nourished with sediments and nutrients. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding maintenance strategies of these highly stressed systems from a range of anthropogenic activities. To date, however, a unified theory explaining how deltas self-organize to distribute water and sediment up to the shoreline remains elusive. Here, we provide evidence for an optimality principle underlying the self-organized partition of fluxes in delta channel networks. By introducing a suitable nonlocal entropy rate (nER) and by analyzing field and simulated deltas, we suggest that delta networks achieve configurations that maximize the diversity of water and sediment flux delivery to the shoreline. We thus suggest that prograding deltas attain dynamically accessible optima of flux distributions on their channel network topologies, thus effectively decoupling evolutionary time scales of geomorphology and hydrology. When interpreted in terms of delta resilience, high nER configurations reflect an increased ability to withstand perturbations. However, the distributive mechanism responsible for both diversifying flux delivery to the shoreline and dampening possible perturbations might lead to catastrophic events when those perturbations exceed certain intensity thresholds.

Carbon storage in the Mississippi River delta enhanced by environmental engineering

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Shields, Michael R.; Bianchi, Thomas S.; Mohrig, David; Hutchings, Jack A.; Kenney, William F.; Kolker, Alexander S.; Curtis, Jason H.

2017-11-01

River deltas have contributed to atmospheric carbon regulation throughout Earth history, but functioning in the modern era has been impaired by reduced sediment loads, altered hydrologic regimes, increased global sea-level rise and accelerated subsidence. Delta restoration involves environmental engineering via river diversions, which utilize self-organizing processes to create prograding deltas. Here we analyse sediment cores from Wax Lake delta, a product of environmental engineering, to quantify the burial of organic carbon. We find that, despite relatively low concentrations of organic carbon measured in the cores (about 0.4%), the accumulation of about 3 T m-2 of sediment over the approximate 60 years of delta building resulted in the burial of a significant amount of organic carbon (16 kg m-2). This equates to an apparent organic carbon accumulation rate of 250 +/- 23 g m-2 yr-1, which implicitly includes losses by carbon emissions and erosion. Our estimated accumulation rate for Wax Lake delta is substantially greater than previous estimates based on the top metre of delta sediments and comparable to those of coastal mangrove and marsh habitats. The sedimentation of carbon at the Wax Lake delta demonstrates the capacity of engineered river diversions to enhance both coastal accretion and carbon burial.

A Regional Survey of River-plume Sedimentation on the Mississippi River Delta Front

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Courtois, A. J.; Bentley, S. J.; Xu, K.; Georgiou, I. Y.; Maloney, J. M.; Miner, M. D.; Chaytor, J. D.; Smith, J.

2017-12-01

Many studies of the Mississippi River and Delta (MRD) have shown historic declines in sediment load reaching the main river distributaries over the last few decades. Recent studies also reported that 50% of the suspended load during floods is sequestered within the delta. While the impact of declining sediment load on wetland loss is well documented, submarine sedimentary processes on the delta front during this recent period of declining sediment load are understudied. To better understand modern sediment dispersal and deposition across the Mississippi River Delta Front, 31 multicores were collected in June 2017 from locations extending offshore from Southwest Pass, South Pass, and Pass a Loutre (the main river outlets) in water depths of 25-280 m. Core locations were selected based on multibeam bathymetry and morphology collected by the USGS in May 2017; the timing of collection coincided with the end of annual peak discharge on the Mississippi River. This multi-agency survey is the first to study delta-front sedimentary processes regionally with such a wide suite of tools. Target locations for coring included the dominant depositional environments: mudflow lobes, gullies, and undisturbed prodelta. Cores were subsampled at 2 cm intervals and analyzed for Beryllium-7 activity via gamma spectrometry; in such settings, Be-7 can be used as a tracer of sediment recently delivered from fluvial origin. Results indicate a general trend of declining Be-7 activity with increasing distance from source, and in deeper water. Inshore samples near Southwest Pass show the deepest penetration depth of Be-7 into the sediment (24-26 cm), which is a preliminary indicator of rapid seasonal sedimentation. Nearshore samples from South Pass exhibited similar Be-7 penetration depths, with results near Pass a Loutre to 14-16 cm depth. Be-7 remains detectable to 2 cm in water 206 m deep, approximately 20 km from South Pass. Sediment dispersal remains impressive offshore from all three

Linking rapid erosion of the Mekong River delta to human activities.

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Anthony, Edward J; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

2015-10-08

As international concern for the survival of deltas grows, the Mekong River delta, the world's third largest delta, densely populated, considered as Southeast Asia's most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river's discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams.

Challenges and Approaches in River Delta Planning - report on training workshop

NARCIS (Netherlands)

Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

2012-01-01

River delta’s, like the Mekong Delta (Vietnam), Ganges-Brahmaputra Delta (Bangladesh), Irrawady (Myanmar) and Ciliwung Delta (Indonesia) are developing rapidly and characterized by large-scale urbanization and industrialization processes. They are facing serious planning challenges related to issues

Hydrology and morphology of two river mouth regions (temperate Vistula Delta and subtropical Red River Delta

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Zbigniew Pruszak

2005-09-01

Full Text Available The paper presents a comparative analysis of two different river mouths from two different geographical zones (subtropical and temperate climatic regions. One is the multi-branch and multi-spit mouth of the Red River on the Gulf of Tonkin (Vietnam, the other is the smaller delta of the river Vistula on a bay of the Baltic Sea (Poland. The analysis focuses on the similarities and differences in the hydrodynamics between these estuaries and the adjacent coastal zones, the features of sediment transport, and the long-term morphodynamics of the river outlets. Salinity and water level are also discussed, the latter also in the context of the anticipated global effect of accelerated sea level rise. The analysis shows that the climatic and environmental conditions associated with geographical zones give rise to fundamental differences in the generation and dynamic evolution of the river mouths.

Remote Sensing of River Delta Inundation: Exploiting the Potential of Coarse Spatial Resolution, Temporally-Dense MODIS Time Series

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Claudia Kuenzer

2015-07-01

Full Text Available River deltas belong to the most densely settled places on earth. Although they only account for 5% of the global land surface, over 550 million people live in deltas. These preferred livelihood locations, which feature flat terrain, fertile alluvial soils, access to fluvial and marine resources, a rich wetland biodiversity and other advantages are, however, threatened by numerous internal and external processes. Socio-economic development, urbanization, climate change induced sea level rise, as well as flood pulse changes due to upstream water diversion all lead to changes in these highly dynamic systems. A thorough understanding of a river delta’s general setting and intra-annual as well as long-term dynamic is therefore crucial for an informed management of natural resources. Here, remote sensing can play a key role in analyzing and monitoring these vast areas at a global scale. The goal of this study is to demonstrate the potential of intra-annual time series analyses at dense temporal, but coarse spatial resolution for inundation characterization in five river deltas located in four different countries. Based on 250 m MODIS reflectance data we analyze inundation dynamics in four densely populated Asian river deltas—namely the Yellow River Delta (China, the Mekong Delta (Vietnam, the Irrawaddy Delta (Myanmar, and the Ganges-Brahmaputra (Bangladesh, India—as well as one very contrasting delta: the nearly uninhabited polar Mackenzie Delta Region in northwestern Canada for the complete time span of one year (2013. A complex processing chain of water surface derivation on a daily basis allows the generation of intra-annual time series, which indicate inundation duration in each of the deltas. Our analyses depict distinct inundation patterns within each of the deltas, which can be attributed to processes such as overland flooding, irrigation agriculture, aquaculture, or snowmelt and thermokarst processes. Clear differences between mid

Is there a self-organization principle of river deltas?

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Tejedor, Alejandro; Longjas, Anthony; Foufoula-Georgiou, Efi

2017-04-01

River deltas are known to possess a complex topological and flux-partitioning structure which has recently been quantified using spectral graph theory [Tejedor et al., 2015a,b]. By analysis of real and simulated deltas it has also been shown that there is promise in formalizing relationships between this topo-dynamic delta structure and the underlying delta forming processes [e.g., Tejedor et al., 2016]. The question we pose here is whether there exists a first order organizational principle behind the self-organization of river deltas and whether this principle can be unraveled from the co-evolving topo-dynamic structure encoded in the delta planform. To answer this question, we introduce a new metric, the nonlocal Entropy Rate (nER) that captures the information content of a delta network in terms of the degree of uncertainty in delivering fluxes from any point of the network to the shoreline. We hypothesize that if the "guiding principle" of undisturbed deltas is to efficiently and robustly build land by increasing the diversity of their flux pathways over the delta plane, then they would exhibit maximum nonlocal Entropy Rate at states at which geometry and flux dynamics are at equilibrium. At the same time, their nER would be non-optimal at transient states, such as before and after major avulsions during which topology and dynamics adjust to each other to reach a new equilibrium state. We will present our results for field and simulated deltas, which confirm this hypothesis and open up new ways of thinking about self-organization, complexity and robustness in river deltas. One particular connection of interest might have important implications since entropy rate and resilience are related by the fluctuation theorem [Demetrius and Manke, 2005], and therefore our results suggest that deltas might in fact self-organize to maximize their resilience to structural and dynamic perturbations. References: Tejedor, A., A. Longjas, I. Zaliapin, and E. Foufoula

A brief history and summary of the effects of river engineering and dams on the Mississippi River system and delta

Science.gov (United States)

Alexander, Jason S.; Wilson, Richard C.; Green, W. Reed

2012-01-01

rich fish community and remains relatively intact. Nevertheless, the widespread and long history of human intervention in river discharge has contributed to the declines of about 25 percent of the species. The Mississippi River Delta Plain is built from six delta complexes composed of a massive area of coastal wetlands that support the largest commercial fishery in the conterminous United States. Since the early 20th century, approximately 4,900 km2 of coastal lands have been lost in Louisiana. One of the primary mechanisms of wetland loss on the Plaquemines-Balize complex is believed to be the disconnection of the river distributary network from the delta plain by the massive system of levees on the delta top, which prevent overbank flooding and replenishment of the delta top by sediment and nutrient deliveries. Efforts by Federal and State agencies to conserve and restore the Mississippi River Delta Plain began over three decades ago and have accelerated over the past decade. Regardless of these efforts, however, land losses are expected to continue because the reduced upstream sediment supplies are not sufficient to keep up with the projected depositional space being created by the combined forces of delta plain subsidence and global sea-level rise.

Variability Matters: New Insights into Mechanics of River Avulsions on Deltas and Their Deposits

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Ganti, V.

2015-12-01

River deltas are highly dynamic, often fan-shaped depositional systems that form when rivers drain into a standing body of water. They host over a half billion people and are currently under threat of drowning and destruction by relative sea-level rise, subsidence, and anthropogenic interference. Deltas often develop planform fan shapes through avulsions, whereby major river channel shifts occur via "channel jumping" about a spatial node, thus determining their fundamental length scale. Emerging theories suggest that the size of delta lobes is set by backwater hydrodynamics; however, these ideas are difficult to test on natural deltas, which evolve on centennial to millennial timescales. In this presentation, I will show results from the first laboratory delta built through successive deposition of lobes that maintain a constant size that scales with backwater hydrodynamics. The characteristic size of deltas emerges because of a preferential avulsion node that remains fixed spatially relative to the prograding shoreline, and is a consequence of multiple river floods that produce persistent morphodynamic river-bed adjustment within the backwater zone. Moreover, river floods cause erosion in the lowermost reaches of the alluvial river near their coastline, which may leave erosional boundaries in the sedimentary record that may appear similar to those previously interpreted to be a result of relative sea-level fall. I will discuss the implications of these findings in the context of sustainability management of deltas, decoding their stratigraphic record, and identifying ancient standing bodies of water on other planets such as Mars. Finally, I will place this delta study in a broader context of recent work that highlights the importance of understanding and quantifying variability in sedimentology and geomorphology.

[Integrated assessment of eco-environmental vulnerability in Pearl River Delta based on RS and GIS].

Science.gov (United States)

Xu, Qing-Yong; Huang, Mei; Liu, Hong-Sheng; Yan, Hui-Min

2011-11-01

Based on the remote sensing data and with the help of geographic information system, an integrated assessment was conducted on the eco-environmental vulnerability of Pearl River Delta in 2004-2008. Spatial principal component analysis was used to generate the evaluation indicators, and analytic hierarchy process (AHP) was applied to determine the weights of the evaluation factors. The reasons causing the vulnerability of the eco- environment in Pearl River Delta were discussed. In the study area, its middle part was the most vulnerable region, occupying 34.0% of the total, eastern part was the moderately vulnerable region, accounting for 25.5%, and western part was the lightly and slightly vulnerable areas, accounting for 28.7 and 11.8%, respectively. Totally, the moderately and lightly vulnerable areas occupied 54.2%, indicating that a majority of the Delta was under moderate and light vulnerability. The natural factors affecting the eco-environmental vulnerability of the Delta were altitude, heavy rain days, water and soil erosion rate, flooded infield rate, normalized difference vegetation index (ND VI) and landscape diversity index, whereas the human factors were population density, waste discharge per unit area, exhaust emission per unit area, land use change, chemical fertilization intensity, pesticide application intensity, amount of motor vehicles possessed by ten thousands people, and index of environmental protection investment. The main characteristics of the extremely and heavily vulnerable regions were low altitude, high frequency of flood disaster, large flooded infield, serious vegetation degradation, high pollution level and low environment protection investment index.

Evaluation of Eco-economy Harmony and Spatial Evolution of the Urban Agglomeration Area in The Great Pearl River Delta

Science.gov (United States)

Wang, Xiuming; Xu, Min; Zhang, Yong; Xu, Naizhong; Zhang, Yuhuan

2018-05-01

Based on the land use data of the study area during 1990 to 2016, the coordination between ecological environment and economy was estimated according to the ESV (ecosystem services value) and EEH (eco-economy harmony) index. The results showed that large amount of farmland and forests were changed to construction land in the study area, due to the rapid urbanization and industrialization. The ESV showed an overall downward trend, the ESV in per hectare was decreased from 1554,000Yuan to 14513,000Yuan. The economic development speed was decreased from 1990 to 2016, the area with high GDP growth rate is changed from the core area of the pearl river delta to the periphery area. The ecology-economy relation in the study area experienced a transformation of “low grade coordination-low grade conflict -further conflict”. Shenzhen, Dongguan, Huizhou, Jiangmen, the central city of Foshan and Guangzhou became the most high-grade conflict areas.

What Role do Hurricanes Play in Sediment Delivery to Subsiding River Deltas?

Science.gov (United States)

Smith, J. E., IV

2016-02-01

James E. Smith IV1, Samuel J. Bentley, Sr.1, Gregg A. Snedden2, Crawford White1 Department of Geology and Geophysics and Coastal Studies Institute, Louisiana State University, Baton Rouge, LA 70803 USA United States Geological Survey, National Wetlands Research Center, Baton Rouge LA 70803 USA The Mississippi River Delta has undergone tremendous land loss over the past century due to natural and anthropogenic influences, a fate shared by many river deltas globally. A globally unprecedented effort to restore and sustain the remaining subaerial portions of the delta is now underway, an endeavor that is expected to cost $50-100B over the next 50 yr. Success of this effort requires a thorough understanding of natural and anthropogenic controls on sediment supply, accumulation, and delta geomorphology. In the Mississippi River Delta, hurricanes have been paradoxically identified as both agents of widespread land loss, and positive influences for marsh vertical sediment accretion. We present the first multi-decadal chronostratigraphic assessment of sediment supply for a major coastal basin of the Mississippi River Delta that assesses both fluvial and hurricane-induced contributions to sediment accumulation in deltaic wetlands. Twenty seven cores have been analyzed for radioisotope geochronology and organic content to establish the chronology of mineral sediment supply to the wetlands over the past 70 years. Our findings indicate that over multidecadal timescales, hurricane-induced sediment delivery may be an important contributor for deltaic wetland vertical accretion, but the contribution from hurricanes to long-term sediment accumulation is substantially less than sediment delivery supplied by existing and planned river-sediment diversions at present-day river-sediment loads.

Mackenzie River Delta morphological change based on Landsat time series

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Vesakoski, Jenni-Mari; Alho, Petteri; Gustafsson, David; Arheimer, Berit; Isberg, Kristina

2015-04-01

Arctic rivers are sensitive and yet quite unexplored river systems to which the climate change will impact on. Research has not focused in detail on the fluvial geomorphology of the Arctic rivers mainly due to the remoteness and wideness of the watersheds, problems with data availability and difficult accessibility. Nowadays wide collaborative spatial databases in hydrology as well as extensive remote sensing datasets over the Arctic are available and they enable improved investigation of the Arctic watersheds. Thereby, it is also important to develop and improve methods that enable detecting the fluvio-morphological processes based on the available data. Furthermore, it is essential to reconstruct and improve the understanding of the past fluvial processes in order to better understand prevailing and future fluvial processes. In this study we sum up the fluvial geomorphological change in the Mackenzie River Delta during the last ~30 years. The Mackenzie River Delta (~13 000 km2) is situated in the North Western Territories, Canada where the Mackenzie River enters to the Beaufort Sea, Arctic Ocean near the city of Inuvik. Mackenzie River Delta is lake-rich, productive ecosystem and ecologically sensitive environment. Research objective is achieved through two sub-objectives: 1) Interpretation of the deltaic river channel planform change by applying Landsat time series. 2) Definition of the variables that have impacted the most on detected changes by applying statistics and long hydrological time series derived from Arctic-HYPE model (HYdrologic Predictions for Environment) developed by Swedish Meteorological and Hydrological Institute. According to our satellite interpretation, field observations and statistical analyses, notable spatio-temporal changes have occurred in the morphology of the river channel and delta during the past 30 years. For example, the channels have been developing in braiding and sinuosity. In addition, various linkages between the studied

[Shifting path of industrial pollution gravity centers and its driving mechanism in Pan-Yangtze River Delta].

Science.gov (United States)

Zhao, Hai-Xia; Jiang, Xiao-Wei; Cui, Jian-Xin

2014-11-01

Shifting path of industrial pollution gravity centers is the response of environmental special formation during the industry transfer process, in order to prove the responding of industrial pollution gravity centers to industry transfer in economically developed areas, this paper calculates the gravity centers of industrial wastewater, gas and solid patterns and reveals the shifting path and its driving mechanism, using the data of industrial pollution in the Pan-Yangtze River Delta from 2000 to 2010. The results show that the gravity center of the industrial waste in Pan-Yangtze River Delta shifts for sure in the last 10 years, and gravity center of solid waste shifts the maximum distance within the three wastes, which was 180.18 km, and shifting distances for waste gas and waste water were 109.51 km and 85.92 km respectively. Moreover, the gravity center of the industrial waste in Pan-Yangtze River Delta shifts westwards, and gravity centers of waste water, gas and solid shift for 0.40 degrees, 0.17 degrees and 0.03 degrees respectively. The shifting of industrial pollution gravity centers is driven by many factors. The rapid development of the heavy industry in Anhui and Jiangxi provinces results in the westward shifting of the pollutions. The optimization and adjustment of industrial structures in Yangtze River Delta region benefit to alleviating industrial pollution, and high-polluting industries shifted to Anhui and Jiangxi provinces promotes pollution gravity center shifting to west. While the development of massive clean enterprise, strong environmental management efforts and better environmental monitoring system slow the shifting trend of industrial pollution to the east in Yangtze River Delta. The study of industrial pollution gravity shift and its driving mechanism provides a new angle of view to analyze the relationship between economic development and environmental pollution, and also provides academic basis for synthetical management and control of

Influence of habitat heterogeneity on anuran diversity in Restinga landscapes of the Parnaíba River delta, northeastern Brazil.

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Araújo, Kássio C; Guzzi, Anderson; Ávila, Robson W

2018-01-01

Anurans have close associations with environmental conditions and therefore represent an interesting vertebrate group for examining how resource availability and environmental variables influence species diversity. Associations between habitat heterogeneity and anuran species diversity were tested in the Restinga landscapes of the Parnaíba River delta in northeastern Brazil. Twenty-one anuran species were sampled in the rainy season during monthly excursions (December 2015 to June 2016) into areas of Restinga on two islands in the Parnaíba River delta. The fourth highest anuran diversity was found in this type of environment in Brazil and is the third in northeastern Brazil. Microenvironments, characterized by a combination of vernal pools with different vegetational and physical structures, better explained anuran species composition in the Parnaíba River delta.

DEVELOPMENT ELECTRONIC MAPS OF ECOLOGICAL STATUS OF WATER OBJECTS OF THE VOLGA RIVER DELTA

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Z. N. Isenalieva

2016-01-01

Full Text Available Abstract. Aim. The aim of this work was the comprehensive study of the ecological state of water objects of the Volga River delta. Methods. The following methods were used: field (collection, observation, organoleptic, uniform chemical analysis techniques are based on colorimetric, settlement, photometric, spectrometric measurement methods. Results. On the basis of results of researches for 2010-2014 performed a comparative analysis of the dynamics of the content of hydro-chemical indicators of environmental quality in waters of the Volga River delta and the residential areas of the background. Applying an integrated approach to the study of biological indicators of water quality. Created digitized map of the quality of aquatic ecosystems of the Volga River delta. Displaying modern ecological condition of watercourses investigated, determined the degree of contamination, the overall trophic and saprobic. Main conclusions. The work has identified adverse environmental situation in water objects of the Astrakhan and the surrounding areas. Average annual concentrations of toxicological substances water objects in the background zone 10 times less than in the water objects of settlements. As a result of work on the basis of ArcGis 10.2.2 created information environment "Eco-monitor", which is a systematic set of information, and quantitatively characterizing the ecological status of water objects. Created on the basis of ArcGis 10.2.2 information environment monitoring system of waterways allows for a temporary and spatial analysis, to assess the quality of different streams in the control sections.

Flood Damage Assessment in Pearl River Delta Rural Area Application in Huashan Town, Huadu District,Guanghzou during the 2017 5.7 Heavy Rain Storm

Science.gov (United States)

Wang, X.

2017-12-01

The Pearl River Delta (PRD) in China, the summer rain storm occurs frequently, the flood damage is very serious. Damage assessment is the basis of scientific decision-making in disaster mitigation. All approaches of flood damage analysis contain uncertainties due to the inaccuracies and generalisations used, the lack of data aggravates this problem, making methods very rough. This study presents a detailed flood damage assessment framework in Pearl River Delta rural area, using 2017 "5.7" heavy rain storm event to simulate the process and estimate the flood loss in resident building and property, agriculture production. The framework integrates four modules,1) utilize the remote sensing and statistical yearbook and so on to construct the disaster bearing bodies GIS database; 2) using hydraulics model to simulate the flood extent and depth spatial distribution;3)through field investigation to obtain the flood loss data for all kinds of hazard-affected body, using statistical analysis method to get the damage curves;4)Integrate flood scenarios, disaster bearing bodies GIS database and damage curves to calculate the flood loss estimation value. Using this methodology, in the 2017 "5.7" heavy rain storm event, Huashan Town flood damage loss is underestimate compared with the government report, because of not considering the damage of water conservancy facilities. But the disaster loss value on the spatial distribution is consistent with actual situation. In terms of aggregated values in the whole town, the model is capable of obtaining figures that are within the same order of magnitude. This study produce a flood damage assessment framework taking into account the regional characteristics of PRD rural area, provide a template for future practice. This study only considers the current impacts, the framework should be improved by taking into account socio-economic and climatic changes, as well as implementing adaptation measures to be applied to assess the potential

Challenges and Approaches in River Delta Planning - Annexes to report on training workshop

NARCIS (Netherlands)

Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

2012-01-01

Programme, participants and all powerpoint presentations of the Delta Alliance Training Workshop: Challenges and approaches in river delta planning, sharing experiences from SE Asian Deltas and the Rhine-Meuse Delta. 22-26 October 2012, WACC, Vietnam National University, Ho Chi Minh City, Vietnam

Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Sather, NK; Johnson, GE; Storch, AJ [Pacific Northwest National Laboratory

2009-07-06

The tidal freshwater monitoring (TFM) project reported herein is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, the U.S. Army Corps of Engineers [USACE], and the U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act (ESA) as a result of operation of the Federal Columbia River Power System. The project is being performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program (Project No. 2005-001-00). The research is a collaborative effort among the Pacific Northwest National Laboratory, the Oregon Department of Fish and Wildlife, the National Marine Fisheries Service, and the University of Washington. The overarching goal of the TFM project is to bridge the gap in knowledge between tidal freshwater habitats and the early life history attributes of migrating salmon. The research questions include: In what types of habitats within the tidal freshwater area of the Columbia River are juvenile salmon found, when are they present, and under what environmental conditions? What is the ecological contribution of shallow (0-5 m) tidal freshwater habitats to the recovery of ESA-listed salmon in the Columbia River basin? Field data collection for the TFM project commenced in June 2007 and since then has continued monthly at six to nine sites in the vicinity of the Sandy River delta (river kilometer 192-208). While this report includes summary data spanning the 19-month period of study from June 2007 through December 2008, it highlights sampling conducted during calendar year 2008. Detailed data for calendar year 2007 were reported previously. The 2008 research objectives were as follows: (1) Characterize the vegetation composition and percent cover, conventional water quality, water surface elevation, substrate composition, bathymetry, and beach slope at the study sites within the vicinity of the Sandy

Geochemical behaviour of heavy metals in a sedimentation area of the rivers Rhine and Meuse

NARCIS (Netherlands)

van den Berg, G.A.

1998-01-01

The Biesbosch, situated in the delta of the rivers Rhine and Meuse in The Netherlands, is considered an important freshwater tidal area, although the tidal amplitude has decreased as a result of the implementation of the Delta Worles. Due to the decrease in flow rates since the closure ofthe area by

Geochemical behaviour of heavy metals in a sedimentation area of the rivers Rhine and Meuse

NARCIS (Netherlands)

Berg, G.A. van den

1998-01-01

The Biesbosch, situated in the delta of the rivers Rhine and Meuse in The Netherlands, is considered an important freshwater tidal area, although the tidal amplitude has decreased as a result of the implementation of the Delta Worles. Due to the decrease in flow rates since the closure ofthe area

Conceptual model of sedimentation in the Sacramento-San Joaquin River Delta

Science.gov (United States)

Schoellhamer, David H.; Wright, Scott A.; Drexler, Judith Z.

2012-01-01

Sedimentation in the Sacramento–San Joaquin River Delta builds the Delta landscape, creates benthic and pelagic habitat, and transports sediment-associated contaminants. Here we present a conceptual model of sedimentation that includes submodels for river supply from the watershed to the Delta, regional transport within the Delta and seaward exchange, and local sedimentation in open water and marsh habitats. The model demonstrates feedback loops that affect the Delta ecosystem. Submerged and emergent marsh vegetation act as ecosystem engineers that can create a positive feedback loop by decreasing suspended sediment, increasing water column light, which in turn enables more vegetation. Sea-level rise in open water is partially countered by a negative feedback loop that increases deposition if there is a net decrease in hydrodynamic energy. Manipulation of regional sediment transport is probably the most feasible method to control suspended sediment and thus turbidity. The conceptual model is used to identify information gaps that need to be filled to develop an accurate sediment transport model.

Morphodynamics and Sediment Transport on the Huanghe (Yellow River) Delta: Work in Progress

Science.gov (United States)

Kineke, G. C.; Calson, B.; Chadwick, A. J.; Chen, L.; Hobbs, B. F.; Kumpf, L. L.; Lamb, M. P.; Ma, H.; Moodie, A. J.; Mullane, M.; Naito, K.; Nittrouer, J. A.; Parker, G.

2017-12-01

Deltas are perhaps the most dynamic of coastal landforms with competing processes that deliver and disperse sediment. As part of the NSF Coastal SEES program, an interdisciplinary team of scientists from the US and China are investigating processes that link river and coastal sediment transport responsible for morphodynamic change of the Huanghe delta- an excellent study site due to its high sediment load and long history of natural and engineered avulsions, that is, abrupt shifts in the river course. A fundamental component of the study is a better understanding of sediment transport physics in a river system that transports mostly silt. Through theory and data analysis, we find that fine-grained rivers fail to develop full scale dunes, which results in faster water flow and substantially larger sediment fluxes as compared to sandy rivers (e.g. the Mississippi River). We also have developed new models for sediment-size dependent entrainment that are needed to make longer term predictions of river sedimentation patterns. On the delta front, we are monitoring the high sediment flux to the coast, which results in steep foresets and ideal conditions for off-shore sediment delivery via gravity flows. These constraints on sediment transport are being used to develop new theory for where and when rivers avulse - including the effects of variable flood discharge, sediment supply, and sea level rise -and how deltas ultimately grow through repeated cycles of lobe development. Flume experiments and field observations are being used to test these models, both in the main channel of the Huanghe and in channels abandoned after historic avulsions. Abandoned channels and floodplains are now dominated by coastal sediment transport through a combination of wave resuspension and tidal transport, settling lag and reverse estuarine circulation. Finally, the field and laboratory tested numerical models are being used as inputs to define a cost curve for efficient avulsion management of

What role do hurricanes play in sediment delivery to subsiding river deltas?

Science.gov (United States)

Smith, James E.; Bentley, Samuel J.; Snedden, Gregg; White, Crawford

2015-01-01

The Mississippi River Delta (MRD) has undergone tremendous land loss over the past century due to natural and anthropogenic influences, a fate shared by many river deltas globally. A globally unprecedented effort to restore and sustain the remaining subaerial portions of the delta is now underway, an endeavor that is expected to cost $50–100B over the next 50 yr. Success of this effort requires a thorough understanding of natural and anthropogenic controls on sediment supply and delta geomorphology. In the MRD, hurricanes have been paradoxically identified as both substantial agents of widespread land loss, and vertical marsh sediment accretion. We present the first multi-decadal chronostratigraphic assessment of sediment supply for a major coastal basin of the MRD that assesses both fluvial and hurricane-induced contributions to sediment accumulation in deltaic wetlands. Our findings indicate that over multidecadal timescales, hurricane-induced sediment delivery may be an important contributor for deltaic wetland vertical accretion, but the contribution from hurricanes to long-term sediment accumulation is substantially less than sediment delivery supplied by existing and planned river-sediment diversions at present-day river-sediment loads.

What Role do Hurricanes Play in Sediment Delivery to Subsiding River Deltas?

Science.gov (United States)

Smith, James E; Bentley, Samuel J; Snedden, Gregg A; White, Crawford

2015-12-02

The Mississippi River Delta (MRD) has undergone tremendous land loss over the past century due to natural and anthropogenic influences, a fate shared by many river deltas globally. A globally unprecedented effort to restore and sustain the remaining subaerial portions of the delta is now underway, an endeavor that is expected to cost $50-100B over the next 50 yr. Success of this effort requires a thorough understanding of natural and anthropogenic controls on sediment supply and delta geomorphology. In the MRD, hurricanes have been paradoxically identified as both substantial agents of widespread land loss, and vertical marsh sediment accretion. We present the first multi-decadal chronostratigraphic assessment of sediment supply for a major coastal basin of the MRD that assesses both fluvial and hurricane-induced contributions to sediment accumulation in deltaic wetlands. Our findings indicate that over multidecadal timescales, hurricane-induced sediment delivery may be an important contributor for deltaic wetland vertical accretion, but the contribution from hurricanes to long-term sediment accumulation is substantially less than sediment delivery supplied by existing and planned river-sediment diversions at present-day river-sediment loads.

Spatio-temporal patterns and predictions of phytoplankton assemblages in a subtropical river delta system

DEFF Research Database (Denmark)

Wang, Chao; Li, Xinhui; Wang, Xiangxiu

2016-01-01

Spatial and seasonal sampling within a subtropical river delta system, the Pearl River Delta (China), provided data to determine seasonal phytoplankton patterns and develop prediction models. The high nutrient levels and frequent water exchanges resulted in a phytoplankton community with greatest...

Stepwise morphological evolution of the active Yellow River (Huanghe) delta lobe (1976-2013): Dominant roles of riverine discharge and sediment grain size

Science.gov (United States)

Wu, Xiao; Bi, Naishuang; Xu, Jingping; Nittrouer, Jeffrey A.; Yang, Zuosheng; Saito, Yoshiki; Wang, Houjie

2017-09-01

The presently active Yellow River (Huanghe) delta lobe has been formed since 1976 when the river was artificially diverted. The process and driving forces of morphological evolution of the present delta lobe still remain unclear. Here we examined the stepwise morphological evolution of the active Yellow River delta lobe including both the subaerial and the subaqueous components, and illustrated the critical roles of riverine discharge and sediment grain size in dominating the deltaic evolution. The critical sediment loads for maintaining the delta stability were also calculated from water discharge and sediment load measured at station Lijin, the last gauging station approximately 100 km upstream from the river mouth. The results indicated that the development of active delta lobe including both subaerial and subaqueous components has experienced four sequential stages. During the first stage (1976-1981) after the channel migration, the unchannelized river flow enhanced deposition within the channel and floodplain between Lijin station and the river mouth. Therefore, the critical sediment supply calculated by the river inputs obtained from station Lijin was the highest. However, the actual sediment load at this stage (0.84 Gt/yr) was more than twice of the critical sediment load ( 0.35 Gt/yr) for sustaining the active subaerial area, which favored a rapid seaward progradation of the Yellow River subaerial delta. During the second stage (1981-1996), the engineering-facilitated channelized river flow and the increase in median grain size of suspended sediment delivered to the sea resulted in the critical sediment load for keeping the delta stability deceasing to 0.29 Gt/yr. The active delta lobe still gradually prograded seaward at an accretion rate of 11.9 km2/yr at this stage as the annual sediment load at Lijin station was 0.55 Gt/yr. From 1996 to 2002, the critical sediment load further decreased to 0.15 Gt/yr with the sediment grain size increased to 22.5 �

Potential Activity of Subglacial Microbiota Transported to Anoxic River Delta Sediments

DEFF Research Database (Denmark)

Cameron, Karen A.; Stibal, Marek; Olsen, Nikoline S.

2017-01-01

-related organisms. Later, a reduction in methane was observed to be paired with the depletion of sulphate, and we hypothesise that sulphate reduction out competed hydrogenotrophic methanogenesis. The structure and diversity of the original CO2/H2-amended incubation communities changed dramatically with a major......The Watson River drains a portion of the SW Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers...... of sediments within the river delta. A long-term (12-month) incubation experiment was established using Watson River delta sediment under anaerobic conditions, with and without CO2/H2 enrichment. Within CO2/H2-amended incubations, sulphate depletion and a shift in the microbial community to a 52% predominance...

Flood mitigation strategies for the Red River Delta

International Nuclear Information System (INIS)

Hansson, K.; Ekenberg, L.

2002-01-01

The increase of natural disasters and especially floods are escalating economical losses. Governments of both developed and developing countries are therefore concerned with increasing post-disaster liabilities in aiding recovery, repairing infrastructure damage and compensation of victims. In particular, governments of developing countries are ill prepared to cover the financial losses of disasters. Moreover, they often experience difficulties in raising funds for the recovery process. In this article, we identify possible policy strategies for coping with complex environmental and social decisions with flood risk involved; using The Red River Delta in Vietnam as a case for investigating various strategies. The paper is concluded with an outline of a model used for policy scenario simulations as well as some very preliminary results from evaluation of three possible policy strategies for The Red River Delta. (author)

Assessment and potential sources of metals in the surface sediments of the Yellow River Delta, Eastern China.

Science.gov (United States)

Cheng, Qingli; Lou, Guangyan; Huang, Wenhai; Li, Xudong

2017-07-01

The Yellow River Delta is the most intact estuary wetland in China and suffers from great pressure of metals. Seventy-seven surface sediment samples were collected in the delta, and contents of Cu, Pb, Cd, Cr, Zn, Ni, and Mn were analyzed by inductively coupled plasma spectrometry and those of Hg and As by atomic fluorescence spectrometry. The results showed that means of metal contents (ppm, dry weight) were as follows: Hg, 0.04; Cr, 61.72; Cu, 20.97; Zn, 60.73; As, 9.47; Pb, 21.91; Cd, 0.12; Ni, 27.24; and Mn, 540.48. 43.8% of Hg and 14.3% of Cd were from the allogenic source while others from the authigenic source. The results of the geoaccumulation indexes appeared that 6.5% of sites from the estuarine and the Gudao areas were moderately polluted by Hg. All ecological risk index values of Hg and 37.7% of Cd were more than 40, which were the main factors of strongly and moderately potential ecological risks of 37.7% of sites in the delta. High Cd contents may be due to the alkaline conditions of the delta and the unreasonable management of the farmland, while the abnormal distribution of Hg to the wet or dry deposition and the erosion of the seawater. It was suggested to monitor Hg content in the atmosphere of the Yellow River Delta. The results were expected to update the pollution status of metals in the delta and created awareness of preserving the sound condition of the Yellow River Delta.

Changes to subaqueous delta bathymetry following a high river flow event, Wax Lake Delta, LA, USA

Science.gov (United States)

Whaling, A. R.; Shaw, J.

2017-12-01

Sediment transport capacity is increased during high river flow (flood) events which are characterized by discharges that exceed the 15 year median daily statistic. The Wax Lake Delta (WLD) in coastal Louisiana has experienced 19 of these high flow events in the past 20 years, yet the depositional patterns of single floods are rarely measured in a field-scale deltaic setting. We characterize flood deposition and erosion patterns on the subaqueous portion of the WLD by differencing two Digital Elevation Models (DEMs) constructed from bathymetric surveys before and after the third largest flood in the WLD's recorded history. The total suspended sediment discharge for the 496 day inter-survey period was 2.14x107 cubic meters measured 21 km upstream of the delta apex. The difference map showed 1.06x107 cubic meters of sediment was deposited and 8.2x106 cubic meters was eroded, yielding 2.40x106 cubic meters of net deposition in the survey area ( 79.7 km2 ). Therefore the average deposition rate was 0.061 mm/day. Channel planform remained relatively unchanged for five out of six distributary passes however Gadwall Pass experienced a maximum channel displacement of 166 m ( 1 channel width) measured from the thalweg centerline. Channel tip extension was negligible. In addition, channel displacement was not concentrated at any portion along the channel centerline. Maximum erosion occurred within channel margins and increased upstream whereas maximum deposition occurred immediately outside the channel margins. Sediment eroded from the survey area was either subsequently re-deposited or transported out of the system. Our results show that up to 77.4% of deposition in the survey area originated from sediment eroded during the flood. Surprisingly, only 11.2% of the total suspended sediment discharge was retained in the subaqueous portion of the delta after the flood. We conclude that a high flow event does not produce channel progradation. Rather, high flow causes delta

Late Quaternary Stratigraphic Architecture of the Santee River Delta, South Carolina, U.S.A.

Science.gov (United States)

Long, J. H.; Hanebuth, T. J. J.

2017-12-01

The Santee River of South Carolina is the second largest river in terms of drainage area and discharge in the eastern United States and forms the only river-fed delta on the country's Atlantic coast. Significant anthropogenic modifications to this system date back to the early 18th century with the extensive clearing of coastal wetland forest for rice cultivation. In the 1940's the construction of large upstream dams permanently altered the discharge of the Santee River. These modifications are likely documented within the sedimentary record of the Santee Delta as episodes of major environmental changes. The Piedmont-sourced Santee River system incised its valley to an estimated depth of 20 m during lower glacial sea level. Sedimentation during the subsequent Holocene transgression and highstand has filled much of this accommodation. The Santee system remains largely under-investigated with only a handful of studies completed in the 1970's and 1980's based on sediment cores and cuttings. Through the use of high frequency seismic profiles (0.5 - 24 kHz), sediment cores, and other field data, we differentiate depositional units, architectural elements, and bounding surfaces with temporal and spatial distributions reflecting the changing morphodynamics of this complex system at multiple scales. These lithosomes are preserved within both modern inshore and offshore settings and were deposited within a range of paralic environments by processes active on fluvial/estuarine bars, floodplains, marshes, tidal flats, spits, beach ridges, and in backbarrier settings. They are bound by surfaces ranging from diastems to regional, polygenetic, low-angle and channel-form erosional surfaces. Detailed descriptions of cores taken from within the upper 6 m of the modern lower delta plain document heterolithic, mixed-energy, organic-rich, largely aggradational sedimentation dating back to at least 5 ka cal BP. Offshore, stacked, sand-rich, progradational packages sit atop heterolithic

Surficial sediments of the wave-dominated Orange River Delta and ...

African Journals Online (AJOL)

The textural and compositional characteristics of the surficial shelf sediments north and south of the Orange River Delta are reviewed and compared. Sediments are fractionated and dispersed both north- and southwards of the Orange River mouth by wave action, longshore drift and subsurface currents. The mean grain ...

The influence of delta formation mechanism on geotechnical property sequence of the late Pleistocene–Holocene sediments in the Mekong River Delta

Directory of Open Access Journals (Sweden)

Truong Minh Hoang

2016-11-01

Full Text Available The aim of the study was to characterize a variety of microstructure development-levels and geotechnical property sequences of the late Pleistocene–Holocene deposits in the Mekong River delta (MRD, and the paper furthermore discusses the influences of delta formation mechanisms on them. The survey associated the geotechnical engineering and the sedimentary geology of the late Pleistocene–Holocene deposits at five sites and also undifferentiated Pleistocene sediments. A cross-section which was rebuilt in the delta progradation-direction and between the Mekong and Bassac rivers represents the stratigraphy. Each sedimentary unit was formed under a different delta formation mechanism and revealed a typical geotechnical property sequence. The mechanical behaviors of the sediment succession in the tide-dominated delta with significant fluvial-activity and material source tend to be more cohesionless soils and strengths than those in the tide- and wave-dominated delta and even the coast. The particular tendency of the mechanical behavior of the deposit succession can be reasonably estimated from the delta formation mechanism. The characteristics of the clay minerals from the Mekong River produced the argillaceous soil which does not have extremely high plasticity. The microstructure development-levels are low to very high indicating how to choose hydraulic conductivity value, k, for estimating overconsolidation ratio, OCR, by the piezocone penetration tests (CPTU. The OCR of sediments in the delta types strangely change with depth but none less than 1. The post-depositional processes significantly influenced the microstructure development, particularly the dehydrating and oxidizing processes.

Fractionation and ecological risk of metals in urban river sediments in Zhongshan City, Pearl River Delta.

Science.gov (United States)

Cai, Jiannan; Cao, Yingzi; Tan, Haijian; Wang, Yanman; Luo, Jiaqi

2011-09-01

Surface sediments collected from nine urban rivers located in Zhongshan City, Pearl River Delta, were analyzed for total concentration of metals with digestion and chemical fractionation adopting the modified European Community Bureau of Reference (BCR) sequential extraction procedure. The results showed that concentration and fractionation of metals varied significantly among the rivers. The total concentration of eight metals in most rivers did not exceed the China Environmental Quality Standard for Soil, Grade III. The potential ecological risk of metals to rivers were related to the land use patterns, in the order of manufacturing areas > residential areas > agriculture areas. The concentration of Pb in the reducible fraction was relatively high (60.0-84.3%). The dominant proportions of Cd, Zn and Cu were primary in the non-residual fraction (67.0%, 71.8% and 81.4% on average respectively), while the percentages of the residual fractions of Cr and Ni varied over a wide range (43-85% and 24-71% respectively). The approaches of the Håkanson ecological risk index and Secondary Phase Enrichment Factor were applied for ecological risk assessment and metal enrichment calculation. The results indicated Hg and Cd had posed high potential ecological risk to urban rivers in this region. Meanwhile, there was widespread pollution and high enrichment of Cu in river sediments in this region. Multiple regression analysis showed that five water quality parameters (pH, DO, COD(Mn), NH(4)(+)-N, TP) had little influence on the distribution of metal fractionation. This result revealed that the ecological risk of metals was not eliminated along with the improvement in water quality. Correlation studies showed that among the metals, Group A (Cd, As, Pb, Zn Hg, r = 0.730-0.924) and Group B (Cr, Cu, Ni, r = 0.815-0.948) were obtained, and the metal contaminations were from industrial activities rather than residential.

Biogeochemical features of aquatic plants in the Selenga River delta

Science.gov (United States)

Shinkareva, Galina; Lychagin, Mikhail

2014-05-01

The Selenga River system provides more than a half of the Lake Baikal total inflow. The river collects a significant amount of pollutants (e.g. heavy metals) from the whole basin. These substances are partially deposited within the Selenga delta, and partially are transported further to the lake. A generous amount of aquatic plants grow in the delta area according to its favorable conditions. This vegetation works as a specific biofilter. It accumulates suspended particles and sorbs some heavy metals from the water. The study aimed to reveal the species of macrophytes which could be mostly important for biomonitoring according to their chemical composition. The field campaign took place in the Selenga River delta in July-August of 2011 (high water period) and in June of 2012 (low water period). 14 species of aquatic plants were collected: water starwort Callitriche hermaphroditica, small yellow pond lily Nuphar pumila, pondweeds Potamogeton crispus, P. pectinatus, P. friesii, broadleaf cattail Typha latifolia, hornwort or coontail Ceratophyllum demersum, arrowhead Sagittaria natans, flowering rush (or grass rush) Butomus umbellatus, reed Phragmites australis, parrot's feather Myriophyllum spicatum, the common mare's tail Hippuris vulgaris, Batrachium trichophyllum, canadian waterweed Elodea canadensis. The samples were dried, grinded up and digested in a mixture of HNO3 and H2O2. The chemical composition of the plant material was defined using ICP-MS and ICP-AES methods. Concentrations of Fe, Mn, Cr, Ni, Cu, B, Zn, V, Co, As, Mo, Pb, and U were considered. The study revealed that Potamogeton pectinatus and Myriophyllum spicatum concentrate elements during both high and low water periods. Conversely the Butomus umbellatus and Phragmites australis contain small amount of heavy metals. The reed as true grasses usually accumulates fewer amounts of elements than other macrophytes. To compare biogeochemical specialization of different species we suggest to use

An Object-Based Classification Approach for Mapping Migrant Housing in the Mega-Urban Area of the Pearl River Delta (China

Directory of Open Access Journals (Sweden)

Sebastian D’Oleire-Oltmanns

2011-08-01

Full Text Available Urban areas develop on formal and informal levels. Informal development is often highly dynamic, leading to a lag of spatial information about urban structure types. In this work, an object-based remote sensing approach will be presented to map the migrant housing urban structure type in the Pearl River Delta, China. SPOT5 data were utilized for the classification (auxiliary data, particularly up-to-date cadastral data, were not available. A hierarchically structured classification process was used to create (spectral independence from single satellite scenes and to arrive at a transferrable classification process. Using the presented classification approach, an overall classification accuracy of migrant housing of 68.0% is attained.

Circuitous to single thread: post-dam geomorphic transformation of the Colorado River in its delta

Science.gov (United States)

Mueller, E. R.; Schmidt, J. C.

2017-12-01

The Colorado River in its delta has transformed from a maze of secondary and distributary channels to an intermittent or ephemeral stream largely disconnected from formerly active channels and floodplains. Periodic post-dam floods have demonstrated that channel migration and shifting during floods increased the extent and diversity of riparian vegetation, and suggested that restoration of fluvial processes that promote re-activation of these former channels may enhance ecosystem rehabilitation. But restoration efforts in the delta are complicated by the fact that the Colorado River has the largest reservoir size in relation to its mean annual flow of any large river in North America and most of its sediment supply is completely blocked in upstream reservoirs. As a result, small controlled floods intended to inundate formerly active channels and rejuvenate riparian vegetation must consider the new relationship between stream flow and the delta's transformed geomorphology. Post-dam channel change has been dominated by the abandonment of secondary and distributary channels, with 3 to 4 meters of bed incision in the upstream part of the delta that diminishes downstream. Initial bed incision of 2 to 3 meters occurred rapidly following completion of Hoover Dam in 1936, before further upstream water development reduced delta flows to near zero by the mid-1960s. The largest post-dam floods occurred in the 1980s, which resulted in 10s to 100s of meters of lateral migration, channel switching, and the reactivation of secondary channels and floodplains rarely inundated since dam completion. Smaller flow pulses in the 1990s and 2000s further incised the thalweg to its minimum elevation, resulting in a narrow single-thread channel inset within the multi-channel surface active during the 1980s. In 2014, an experimental pulse flow was released to the river channel with a peak discharge approximately 5% of the typical pre-dam flood peak. Topographic change was confined to the main

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

Directory of Open Access Journals (Sweden)

Manon Besset

2017-09-01

Full Text Available The Mediterranean basin (including the Black Sea is characterized by a plethora of deltas that have developed in a wave-influenced setting. Many of these deltas are sourced in sediments by river catchments that have been variably dammed. The vulnerability status of a selection of ten deltas subject to different levels of reduction in fluvial sediment supply following damming was analysed by quantifying changes in delta protrusion area and protrusion angle over the last 30 years. The rationale for choosing these two metrics, which do not require tricky calculations of longshore bedload transport volumes and river ‘influence’, is that as sediment supply wanes, increasing relative efficiency of waves leads to longshore redistribution of reworked sediments and progressive ‘flattening’ of the delta protrusion. The results show that eight of the ten deltas (Nile, Rhône, Ebro, Ceyhan, Arno, Ombrone, Moulouya, Medjerda are in erosion, whereas two (Danube, Po show stability, but the statistical relationship between change in delta protrusion area and sediment flux reduction is poor, thus suggesting that the role of dams in causing delta shoreline erosion may have been over-estimated. But this poor relationship could also be due to a long temporal lag between dam construction and bedload removal and transport to the coast downstream of dams, and, where the delta protrusion is being eroded, to bedload trapping by shoreline engineering structures and by elongating delta-flank spits. Other potential influential factors in shoreline change include subsidence, sea-level rise, storminess, exceptional river floods, and managed sediment releases downstream of dams. A longer observation period and high-resolution sediment-budget studies will be necessary to determine more definitively to which extent continued trapping of sediment behind dams will impact overall delta stability in the Mediterranean and Black Seas. Mitigation of delta erosion is likely to

Sectorial Water Use Trends in the Urbanizing Pearl River Delta, China

NARCIS (Netherlands)

Yao, M.; Werners, S.E.; Hutjes, R.W.A.; Kabat, P.; Huang, H.Q.

2015-01-01

Assessing and managing water use is crucial for supporting sustainable river basin management and regional development. The first consistent and comprehensive assessment of sectorial water use in the Pearl River Delta (PRD) is presented by analysing homogenized annual water use data from 2000 to

[Prediction and simulation of urban area expansion in Pearl River Delta Region under the RCPs climate scenarios].

Science.gov (United States)

Jiang, Oun-ou; Deng, Xiang-zheng; Ke, Xin-li; Zhao, Chun-hong; Zhang, Wei

2014-12-01

The sizes and number of cities in China are increasing rapidly and complicated changes of urban land use system have occurred as the social economy develops rapidly. This study took the urban agglomeration of Pearl River Delta Region as the study area to explore the driving mechanism of dynamic changes of urban area in the urbanization process under the joint influence of natural environment and social economic conditions. Then the CA (cellular automata) model was used to predict and simulate the urban area changes until 2030 under the designed scenarios of planning and RCPs (representative concentration pathways). The results indicated that urbanization was mainly driven by the non-agricultural population growth and social-economic development, and the transportation had played a fundamental role in the whole process, while the areas with high elevation or steep slope restricted the urbanization. Besides, the urban area would keep an expanding trend regardless of the scenarios, however, the expanding speed would slow down with different inflection points under different scenarios. The urban expansion speed increased in the sequence of the planning scenario, MESSAGE scenario and AIM scenario, and that under the MESSAGE climate scenario was more consistent with the current urban development trend. In addition, the urban expansion would mainly concentrate in regions with the relatively high urbanization level, e.g., Guangzhou, Dongguan, Foshan, Shenzhen, Zhanjiang and Chaoshan.

River, delta and coastal morphological response accounting for biological dynamics

Science.gov (United States)

Goldsmith, W.; Bernardi, D.; Schippa, L.

2015-03-01

Management and construction can increase resilience in the face of climate change, and benefits can be enhanced through integration of biogenic materials including shells and vegetation. Rivers and coastal landforms are dynamic systems that respond to intentional and unintended manipulation of critical factors, often with unforeseen and/or undesirable resulting effects. River management strategies have impacts that include deltas and coastal areas which are increasingly vulnerable to climate change with reference to sea level rise and storm intensity. Whereas conventional assessment and analysis of rivers and coasts has relied on modelling of hydrology, hydraulics and sediment transport, incorporating additional biological factors can offer more comprehensive, beneficial and realistic alternatives. Suitable modelling tools can provide improved decision support. The question has been whether current models can effectively address biological responses with suitable reliability and efficiency. Since morphodynamic evolution exhibits its effects on a large timescale, the choice of mathematical model is not trivial and depends upon the availability of data, as well as the spatial extent, timelines and computation effort desired. The ultimate goal of the work is to set up a conveniently simplified river morphodynamic model, coupled with a biological dynamics plant population model able to predict the long-term evolution of large alluvial river systems managed through bioengineering. This paper presents the first step of the work related to the application of the model accounting for stationary vegetation condition. Sensitivity analysis has been performed on the main hydraulic, sedimentology, and biological parameters. The model has been applied to significant river training in Europe, Asia and North America, and comparative analysis has been used to validate analytical solutions. Data gaps and further areas for investigation are identified.

Contamination profiles of perfluoroalkyl substances in five typical rivers of the Pearl River Delta region, South China.

Science.gov (United States)

Pan, Chang-Gui; Ying, Guang-Guo; Liu, You-Sheng; Zhang, Qian-Qian; Chen, Zhi-Feng; Peng, Feng-Jiao; Huang, Guo-Yong

2014-11-01

A survey on contamination profiles of eighteen perfluoroalkyl substances (PFASs) was performed via high performance liquid chromatography-tandem mass spectrometry for surface water and sediments from five typical rivers of the Pearl River Delta region, South China in summer and winter in 2012. The total concentrations of the PFASs in the water phase of the five rivers ranged from 0.14 to 346.72 ng L(-1). The PFAS concentrations in the water phase were correlated positively to some selected water quality parameters such as chemical oxygen demand (COD) (0.7913) and conductivity (0.5642). The monitoring results for the water samples showed significant seasonal variations, while those for the sediment samples showed no obvious seasonal variations. Among the selected 18 PFASs, perfluorooctane sulfonic acid (PFOS) was the dominant PFAS compound both in water and sediment for two seasons with its maximum concentration of 320.5 ng L(-1) in water and 11.4 ng g(-1) dry weight (dw) in sediment, followed by perfluorooctanoic acid (PFOA) with its maximum concentration of 26.48 ng L(-1) in water and 0.99 ng g(-1) dw in sediment. PFOS and PFOA were found at relatively higher concentrations in the Shima River and Danshui River than in the other three rivers (Xizhijiang River, Dongjiang River and Shahe River). The principal component analysis for the PFASs concentrations in water and sediment separated the sampling sites into two groups: rural and agricultural area, and urban and industrial area, suggesting the PFASs in the riverine environment were mainly originated from industrial and urban activities in the region. Copyright © 2014 Elsevier Ltd. All rights reserved.

More than 100 Years of Background-Level Sedimentary Metals, Nisqually River Delta, South Puget Sound, Washington

Science.gov (United States)

Takesue, Renee K.; Swarzenski, Peter W.

2011-01-01

The Nisqually River Delta is located about 25 km south of the Tacoma Narrows in the southern reach of Puget Sound. Delta evolution is controlled by sedimentation from the Nisqually River and erosion by strong tidal currents that may reach 0.95 m/s in the Nisqually Reach. The Nisqually River flows 116 km from the Cascade Range, including the slopes of Mount Rainier, through glacially carved valleys to Puget Sound. Extensive tidal flats on the delta consist of late-Holocene silty and sandy strata from normal river streamflow and seasonal floods and possibly from distal sediment-rich debris flows associated with volcanic and seismic events. In the early 1900s, dikes and levees were constructed around Nisqually Delta salt marshes, and the reclaimed land was used for agriculture and pasture. In 1974, U.S. Fish and Wildlife Service established the Nisqually National Wildlife Refuge on the reclaimed land to protect migratory birds; its creation has prevented further human alteration of the Delta and estuary. In October 2009, original dikes and levees were removed to restore tidal exchange to almost 3 km2 of man-made freshwater marsh on the Nisqually Delta.

Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Sobocinski, Kathryn; Johnson, Gary; Sather, Nichole [Pacific Northwest National Laboratory

2008-03-17

This document is the first annual report for the study titled 'Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River'. Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program. The goal of the 2007-2009 Tidal Freshwater Monitoring Study is to answer the following questions: In what types of habitats within the tidal freshwater area of the lower Columbia River and estuary (LCRE; Figure 1) are yearling and subyearling salmonids found, when are they present, and under what environmental conditions?1 And, what is the ecological importance2 of shallow (0-5 m) tidal freshwater habitats to the recovery of Upper Columbia River spring Chinook salmon and steelhead and Snake River fall Chinook salmon? Research in 2007 focused mainly on the first question, with fish stock identification data providing some indication of Chinook salmon presence at the variety of habitat types sampled. The objectives and sub-objectives for the 2007 study were as follows: (1) Habitat and Fish Community Characteristics-Provide basic data on habitat and fish community characteristics for yearling and subyearling salmonids at selected sites in the tidal freshwater reach in the vicinity of the Sandy River delta. (1a) Characterize vegetation assemblage percent cover, conventional water quality, substrate composition, and beach slope at each of six sampling sites in various tidal freshwater habitat types. (1b

Tides Stabilize Deltas until Humans Interfere

Science.gov (United States)

Hoitink, T.; Zheng Bing, W.; Vermeulen, B.; Huismans, Y.; Kastner, K.

2017-12-01

Despite global concerns about river delta degradation caused by extraction of natural resources, sediment retention by reservoirs and sea-level rise, human activity in the world's largest deltas intensifies. In this review, we argue that tides tend to stabilize deltas until humans interfere. Under natural circumstances, delta channels subject to tides are more stable than their fluvial-dominated counterparts. The oscillatory tidal flow counteracts the processes responsible for bank erosion, which explains why unprotected tidal channels migrate only slowly. Peak river discharges attenuate the tides, which creates storage space to accommodate the extra river discharge during extreme events and as a consequence, reduce flood risk. With stronger tides, the river discharge is being distributed more evenly over the various branches in a delta, preventing silting up of smaller channels. Human interference in deltas is massive. Storm surge barriers are constructed, new land is being reclaimed and large-scale sand excavation takes place, to collect building material. Evidence from deltas around the globe shows that in human-controlled deltas the tidal motion often plays a destabilizing role. In channels of the Rhine-Meuse Delta, some 100 scour holes are identified, which relates to the altered tidal motion after completion of a storm surge barrier. Sand mining has led to widespread river bank failures in the tidally-influenced Mekong Delta. The catastrophic flood event in the Gauges-Brahmaputra Delta by Cyclone Aila, which caused the inundation of an embanked polder area for over two years, was preceded by river bank erosion at the mouths of formal tidal channels that were blocked by the embankment. Efforts to predict the developments of degrading deltas are few. Existing delta models are capable of reproducing expanding deltas, which is essentially a matter of simulating the transport of sediment from source in a catchment to the sink in a delta. Processes of soil

Delta Vegetation and Land Use [ds292

Data.gov (United States)

California Natural Resource Agency — Vegetation and land use are mapped for the approximately 725,000 acres constituting the Legal Delta portion of the Sacramento and San Joaquin River Delta area....

Antibiotics in riverine runoff of the Pearl River Delta and Pearl River Estuary, China: Concentrations, mass loading and ecological risks

International Nuclear Information System (INIS)

Xu, Weihai; Yan, Wen; Li, Xiangdong; Zou, Yongde; Chen, Xiaoxiang; Huang, Weixia; Miao, Li; Zhang, Ruijie; Zhang, Gan; Zou, Shichun

2013-01-01

Ten antibiotics belonging to three groups (macrolides, fluoroquinolones and sulfonamides) were investigated in riverine runoff of the Pearl River Delta (PRD) and Pearl River Estuary (PRE), South China for assessing the importance of riverine runoff in the transportation of contaminants from terrestrial sources to the open ocean. All antibiotics were detected in the eight outlets with concentrations ranging from 0.7 to 127 ng L −1 . The annual mass loadings of antibiotics from the PRD to the PRE and coast were 193 tons with 102 tons from the fluoroquinolone group. It showed that antibiotics decreased from the riverine outlets to the PRE and open ocean. Risk assessment showed that most of these antibiotics showed various ecological risks to the relevant aquatic organisms, in which ofloxacin (OFL), erythromycin (ETM) and ciprofloxacin (CIP) posed high ecological risks to the studied aquatic environments. -- Highlights: •Antibiotics were ubiquitous in the river water and costal water in the Pearl River Delta. •Antibiotics exhibited distinct temporal and spatial trends in the riverine runoff outlets. •Annual outflows of antibiotics were 193 tons from the Pearl River to coastal ocean. •Some antibiotics posed high risks to some organisms in the PRD environments. -- Antibiotics were ubiquitous in the river and coastal water in the Pearl River Delta and posed various ecological risks to the relevant aquatic organisms

An appraisal of river erosion mitigation in the Niger Delta

International Nuclear Information System (INIS)

Aban, T. K. S.; Omuso, W. O.

1999-01-01

River erosion processes in the Niger Delta and the effectiveness of locally applied remedial measures is appraised, using information on channel geometry, flow velocity distribution, soil type, stratification, bank height and steepness, state of compaction, together with pool level variation in river channels. High flow velocity and bank height were identified as the major erosion causative factors. Local responses towards erosion mitigation have involved structural methods to varying degree of success. River training has been recommended as a long - term regional approach to mitigate river bank erosion. However, in the short -term revetments, concrete and sheets piles may be applied cautiously

River, delta and coastal morphological response accounting for biological dynamics

Directory of Open Access Journals (Sweden)

W. Goldsmith

2015-03-01

Full Text Available Management and construction can increase resilience in the face of climate change, and benefits can be enhanced through integration of biogenic materials including shells and vegetation. Rivers and coastal landforms are dynamic systems that respond to intentional and unintended manipulation of critical factors, often with unforeseen and/or undesirable resulting effects. River management strategies have impacts that include deltas and coastal areas which are increasingly vulnerable to climate change with reference to sea level rise and storm intensity. Whereas conventional assessment and analysis of rivers and coasts has relied on modelling of hydrology, hydraulics and sediment transport, incorporating additional biological factors can offer more comprehensive, beneficial and realistic alternatives. Suitable modelling tools can provide improved decision support. The question has been whether current models can effectively address biological responses with suitable reliability and efficiency. Since morphodynamic evolution exhibits its effects on a large timescale, the choice of mathematical model is not trivial and depends upon the availability of data, as well as the spatial extent, timelines and computation effort desired. The ultimate goal of the work is to set up a conveniently simplified river morphodynamic model, coupled with a biological dynamics plant population model able to predict the long-term evolution of large alluvial river systems managed through bioengineering. This paper presents the first step of the work related to the application of the model accounting for stationary vegetation condition. Sensitivity analysis has been performed on the main hydraulic, sedimentology, and biological parameters. The model has been applied to significant river training in Europe, Asia and North America, and comparative analysis has been used to validate analytical solutions. Data gaps and further areas for investigation are identified.

Geomorphic change and sediment transport during a small artificial flood in a transformed post-dam delta: The Colorado River delta, United States and Mexico

Science.gov (United States)

Mueller, Erich R.; Schmidt, John C.; Topping, David J.; Shafroth, Patrick B.; Rodríguez-Burgueño, Jesús Eliana; Ramírez-Hernández, Jorge; Grams, Paul E.

2017-01-01

The Colorado River delta is a dramatically transformed landscape. Major changes to river hydrology and morpho-dynamics began following completion of Hoover Dam in 1936. Today, the Colorado River has an intermittent and/or ephemeral channel in much of its former delta. Initial incision of the river channel in the upstream ∼50 km of the delta occurred in the early 1940s in response to spillway releases from Hoover Dam under conditions of drastically reduced sediment supply. A period of relative quiescence followed, until the filling of upstream reservoirs precipitated a resurgence of flows to the delta in the 1980s and 1990s. Flow releases during extreme upper basin snowmelt in the 1980s, flood flows from the Gila River basin in 1993, and a series of ever-decreasing peak flows in the late 1990s and early 2000s further incised the upstream channel and caused considerable channel migration throughout the river corridor. These variable magnitude post-dam floods shaped the modern river geomorphology. In 2014, an experimental pulse-flow release aimed at rejuvenating the riparian ecosystem and understanding hydrologic dynamics flowed more than 100 km through the length of the delta’s river corridor. This small artificial flood caused localized meter-scale scour and fill of the streambed, but did not cause further incision or significant bank erosion because of its small magnitude. Suspended-sand-transport rates were initially relatively high immediately downstream from the Morelos Dam release point, but decreasing discharge from infiltration losses combined with channel widening downstream caused a rapid downstream reduction in suspended-sand-transport rates. A zone of enhanced transport occurred downstream from the southern U.S.-Mexico border where gradient increased, but effectively no geomorphic change occurred beyond a point 65 km downstream from Morelos Dam. Thus, while the pulse flow connected with the modern estuary, deltaic sedimentary processes were not

Losses of Sacramento River Chinook Salmon and Delta Smelt to Entrainment in Water Diversions in the Sacramento–San Joaquin Delta

Directory of Open Access Journals (Sweden)

Wim J. Kimmerer

2008-06-01

Full Text Available Pumping at the water export facilities in the southern Sacramento-San Joaquin Delta kills fish at and near the associated fish-salvage facilities. Correlative analyses of salvage counts with population indices have failed to provide quantitative estimates of the magnitude of this mortality. I estimated the proportional losses of Sacramento River Chinook salmon (Oncorhynchus tshawytscha and delta smelt (Hypomesus transpacificus to place these losses in a population context. The estimate for salmon was based on recoveries of tagged smolts released in the upper Sacramento River basin, and recovered at the fish-salvage facilities in the south Delta and in a trawling program in the western Delta. The proportion of fish salvaged increased with export flow, with a mean value around 10% at the highest export flows recorded. Mortality was around 10% if pre-salvage losses were about 80%, but this value is nearly unconstrained. Losses of adult delta smelt in winter and young delta smelt in spring were estimated from salvage data (adults corrected for estimated pre-salvage survival, or from trawl data in the southern Delta (young. These losses were divided by population size and accumulated over the respective seasons. Losses of adult delta smelt were 1–50% (median 15% although the highest value may have been biased upward. Daily losses of larvae and juveniles were 0–8%, and seasonal losses accumulated were 0–25% (median 13%. The effect of these losses on population abundance was obscured by subsequent 50-fold variability in survival from summer to fall.

Mixing state of oxalic acid containing particles in the rural area of Pearl River Delta, China: implication for seasonal formation mechanism of Secondary Organic Aerosol (SOA)

OpenAIRE

Cheng, Chunlei; Li, Mei; Chan, Chak K.; Tong, Haijie; Chen, Changhong; Chen, Duohong; Wu, Dui; Li, Lei; Cheng, Peng; Gao, Wei; Huang, Zhengxu; Li, Xue; Fu, Zhong; Bi, Yanru; Zhou, Zhen

2016-01-01

The formation of oxalic acid and its mixing state in atmospheric particulate matter (PM) were studied using a single particle aerosol mass spectrometer (SPAMS) in the summer and winter of 2014 in Heshan, a supersite in the rural area of the Pearl River Delta (PRD) region in China. Oxalic acid-containing particles accounted for 2.5 % and 2.7 % in total detected ambient particles in summer and winter, respectively. Oxalic acid was measured in particles classified as elemental carb...

The response of grain production to changes in quantity and quality of cropland in Yangtze River Delta, China.

Science.gov (United States)

Liu, Guilin; Zhang, Luocheng; Zhang, Qian; Musyimi, Zipporah

2015-02-01

Cropland in Yangtze River Delta has declined drastically since economic reforms in 1978 that led to rapid economic development. Such cropland loss due to population growth has led to a decline in grain production. This study aimed at analyzing the impact of land use changes on grain production. To achieve this, the spatiotemporal dynamics of cropland during 1980-2010 were analyzed. Irrigation and soil fertility data were used as additional lines of evidence. Cropland loss had negative impacts on grain production. About 80 and 66% of grain production decreased during 1980-2005 and 2005-2010 respectively. This decline was attributed to the conversion of cropland to built-up areas. Abandoned cropland areas were mainly concentrated in regions with high irrigation capability and high soil fertility, while cropland reclamation was mainly in areas with low irrigation and soil fertility, implying that, although cropland was reclaimed, production remained low. The decline in cropland area has reinforced the chronic food insecurity in Yangtze River Delta. This study demonstrated the response of grain production to the changes in cropland quantity and quality. It also provides scientific evidence for decision makers to protect cropland and enhance grain production. © 2014 Society of Chemical Industry.

A GIS based estimation of loss of particulate nitrogen and phosphorus in typical drainage area of Pearl River Delta

Science.gov (United States)

Liu, Xiaonan; Wu, Zhifeng; Cheng, Jiong; Liu, Ping

2008-10-01

The output of nitrogen and phosphorus from agricultural activities is the main source for water eutrophication. The fully developed agriculture in vegetables, fruits and flowers in Pearl River Delta gives rise to excessive use of chemical matter such as fertilizer and pesticide and thus bring about the serious water pollution because of the loss of nitrogen (N) and phosphorus (P) from the farmland in the region. Based on Geographic Information System (GIS) and soil pollution data, Universal Soil Loss Equation (USLE) and source type method are used to estimate the loads of particulate N and P from the soil of different land use types in the drainage area of Liuxi River in Guangzhou, China. So the key regions those the NPS pollution occurred can be confirmed and the technical support for the pollution control target and the capital flow concentration can be provided by the results. The study shows that, (1) The total loss of particulate N and P in the drainage area is 582.49 t/a and 424.74 t/a respectively. Among them the loss of particulate N from paddy soil occupies 40.02% and that of forest 6.31%, while the loss of particulate P from the soil of dry-land accounts for 28.75% and that of paddy soil 26.31%. (2) There are significantly different losses of particulate N and P per unit area from the soils of different source land use types in the drainage area. The losses of particulate N and P per unit area are both the highest from the soil of dry-land, which is 7.72 kg/hm2 and 9.50 kg/hm2 respectively, followed by those of orchard, which is 7.20 kg/hm2 and 6.56 kg/hm2 respectively. The causes are excessive use of chemical matter, unreasonable cultivation pattern, and the soil erosion of different land use. (3) The excessive N and P come from the loss of particulate N and P from the fertilization in agricultural production, and they are the main source of the pollutants in Liuxi River water.

Experimental investigation of channel avulsion frequency on river deltas under rising sea levels

Science.gov (United States)

Silvestre, J.; Chadwick, A. J.; Steele, S.; Lamb, M. P.

2017-12-01

River deltas are low-relief landscapes that are socioeconomically important; they are home to over half a billion people worldwide. Many deltas are built by cycles of lobe growth punctuated by abrupt channel shifts, or avulsions, which often reoccur at a similar location and with a regular frequency. Previous experimental work has investigated the effect of hydrodynamic backwater in controlling channel avulsion location and timing on deltas under constant sea level conditions, but it is unclear how sea-level rise impacts avulsion dynamics. We present results from a flume experiment designed to isolate the role of relative sea-level rise on the evolution of a backwater-influenced delta. The experiment was conducted in the river-ocean facility at Caltech, where a 7m long, 14cm wide alluvial river drains into a 6m by 3m "ocean" basin. The experimental delta grew under subcritical flow, a persistent backwater zone, and a range of sea level rise rates. Without sea level rise, lobe progradation produced in-channel aggradation and periodic avulsions every 3.6 ± 0.9 hours, which corresponded to when channels aggraded to approximately one-half of their flow depth. With a modest rate of sea-level rise (0.25 mm/hr), we observed enhanced aggradation in the backwater zone, causing channels to aggrade more quickly and avulse more frequently (every 2.1 ± 0.6 hours). In future work, we expect further increases in the rate of relative sea-level rise to cause avulsion frequency to decrease as the delta drowns and the backwater zone retreats upstream. Experimental results can serve as tests of numerical models that are needed for hazard mitigation and coastal sustainability efforts on drowning deltas.

Urbanization effect on precipitation over the Pearl River Delta based on CMORPH data

Directory of Open Access Journals (Sweden)

Sheng Chen

2015-03-01

Full Text Available Based on the satellite data from the Climate Prediction Center morphing (CMORPH at very high spatial and temporal resolution, the effects of urbanization on precipitation were assessed over the Pearl River Delta (PRD metropolitan regions of China. CMORPH data well estimates the precipitation features over the PRD. Compared to the surrounding rural areas, the PRD urban areas experience fewer and shorter precipitation events with a lower precipitation frequency (ratio of rainy hours, about 3 days per year less; however, short-duration heavy rain events play a more significant role over the PRD urban areas. Afternoon precipitation is much more pronounced over the PRD urban areas than the surrounding rural areas, which is probably because of the increase in short-duration heavy rain over urban areas.

Future Deltas Utrecht University research focus area: towards sustainable management of sinking deltas

Science.gov (United States)

Stouthamer, E.; van Asselen, S.

2015-11-01

Deltas are increasingly under pressure from human impact and climate change. To deal with these pressures that threat future delta functioning, we need to understand interactions between physical, biological, chemical and social processes in deltas. This requires an integrated approach, in which knowledge on natural system functioning is combined with knowledge on spatial planning, land and water governance and legislative frameworks. In the research focus area Future Deltas of Utrecht University an interdisciplinary team from different research groups therefore works together. This allows developing integrated sustainable and resilient delta management strategies, which is urgently needed to prevent loss of vital delta services.

Heavy metals and polychlorinated biphenyls (PCBs) sedimentation in the Lianhua Mountain Reservoir, Pearl River Delta, China.

Science.gov (United States)

Huang, Jingyu; Amuzu-Sefordzi, Basil; Li, Ming

2015-05-01

The Pearl River Delta is one of the biggest electronics manufacturing regions in the world. Due to the presence of abandoned industrial sites and the proliferation of large-scale electronics companies in the past four decades, it is therefore imperative to investigate the extent of heavy metals and polychlorinated biphenyls (PCBs) contamination in the region. Spatial and temporal distribution of heavy metals (Cr, Cu, Ni, Pb, and Zn) and PCBs (PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) in the Lianhua Mountain reservoir in the Pearl River Delta, Dongguan City, China were examined based on a sedimentary profile analysis. Higher concentrations of the heavy metals detected were recorded in bottom sediments whereas 70% of the detected PCBs recorded maximum concentrations in top sediments. The geo-accumulation indices (Igeo) indicate that the study area is uncontaminated to moderately contaminated. Also, the integrated pollution indices (IPI) were above 1, except Pb, which shows that the study area is contaminated with heavy metals from anthropogenic sources. The concentrations of individual heavy metals and PCBs over a period of 60 years were also analyzed in order to establish a historical trend of pollution in the study area. This study provides baseline information on the level and historical trend of heavy metals and PCBs pollution in the study area.

Drones on the delta | CRDI - Centre de recherches pour le ...

International Development Research Centre (IDRC) Digital Library (Canada)

25 nov. 2016 ... Waves wash ashore at Fuvemeh, a town in Ghana's Volta River delta that's threatened by coastal erosion and flooding. Brian Owens, Canadian Geographic. Ghana's Volta River delta is an area vulnerable to climate change, with rising seas and increasingly powerful storms driving flooding and erosion, ...

Passive air sampling of organochlorine pesticides and polychlorinated biphenyls in the Yangtze River Delta, China: Concentrations, distributions, and cancer risk assessment

International Nuclear Information System (INIS)

Zhang, Lifei; Dong, Liang; Yang, Wenlong; Zhou, Li; Shi, Shuangxin; Zhang, Xiulan; Niu, Shan; Li, Lingling; Wu, Zhongxiang; Huang, Yeru

2013-01-01

The Yangtze River Delta (YRD) has been quickly industrialized and urbanized. Passive air sampling of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) was carried out in the YRD in 2010–2011 to investigate their spatiotemporal distributions and estimate the risk of cancer from their inhalation. Annual concentrations were 151, 168, 18.8, 110, 17.9, and 35.0 pg m −3 for HCB, ∑DDTs, ∑HCHs, ∑chlordane, mirex, and PCBs, respectively. The highest OCP and PCB concentrations were generally detected in the autumn and winter. The average concentrations of OCPs and PCBs for the different site groups followed the order urban ≈ urban–rural transition > rural. The lifetime excess cancer risks from the inhalation of OCPs and PCBs were −6 . The predicted cancer cases per lifetime associated with the inhalation of OCPs and PCBs are 12, 7, and 4 per ten thousand people for urban, urban–rural transition, and rural areas, respectively. Highlights: •Organochlorine pollutants were measured in the air in the Yangtze River Delta area. •Air PCB concentration declined in recent years comparing with previous results. •HCB and DDEs predominated, with the highest values in winter and autumn, respectively. •OCPs and PCBs followed the order: urban ≈ urban–rural transition > rural. -- A detailed study of organochlorine pesticides and polychlorinated biphenyls in air across the Yangtze River Delta area using passive air samplers

Distribution and Joint Fish-Tag Survival of Juvenile Chinook Salmon Migrating through the Sacramento-San Joaquin River Delta, California, 2008

Science.gov (United States)

Holbrook, Christopher M.; Perry, Russell W.; Adams, Noah S.

2009-01-01

Acoustic telemetry was used to obtain the movement histories of 915 juvenile fall-run Chinook salmon (Oncorhynchus tshawytscha) through the lower San Joaquin River and Sacramento-San Joaquin Delta, California, in 2008. Data were analyzed within a release-recapture framework to estimate survival, route distribution, and detection probabilities among three migration pathways through the Delta. The pathways included the primary route through the San Joaquin River and two less direct routes (Old River and Turner Cut). Strong inferences about survival were limited by premature tag failure, but estimates of fish distribution among migration routes should be unaffected by tag failure. Based on tag failure tests (N = 66 tags), we estimated that only 55-78 percent of the tags used in this study were still functioning when the last fish was detected exiting the study area 15 days after release. Due to premature tag failure, our 'survival' estimates represent the joint probability that both the tag and fish survived, not just survival of fish. Low estimates of fish-tag survival could have been caused by fish mortality or fish travel times that exceeded the life of the tag, but we were unable to differentiate between the two. Fish-tag survival through the Delta (from Durham Ferry to Chipps Island by all routes) ranged from 0.05 +or- 0.01 (SE) to 0.06 +or- 0.01 between the two weekly release groups. Among the three migration routes, fish that remained in the San Joaquin River exhibited the highest joint fish-tag survival (0.09 +or- 0.02) in both weeks, but only 22-33 percent of tagged fish used this route, depending on the week of release. Only 4-10 percent (depending on week) of tagged fish traveled through Turner Cut, but no tagged fish that used this route were detected exiting the Delta. Most fish (63-68 percent, depending on week of release) migrated through Old River, but fish-tag survival through this route (0.05 +or- 0.01) was only about one-half that of fish that

The feeding ecology of schilbeid catfishes in river Ase, Niger delta ...

African Journals Online (AJOL)

The feeding ecology of schilbeid catfishes in river Ase, Niger delta, Southern Nigeria. ... Open Access DOWNLOAD FULL TEXT ... in feeding intensity were described for Eutropius niloticus and Schilbe mystus which had adequate data.

Quantification of Multiple Climate Change and Human Activity Impact Factors on Flood Regimes in the Pearl River Delta of China

Directory of Open Access Journals (Sweden)

Yihan Tang

2016-01-01

Full Text Available Coastal flood regimes have been irreversibly altered by both climate change and human activities. This paper aims to quantify the impacts of multiple factors on delta flood. The Pearl River Delta (PRD, with dense river network and population, is one of the most developed coastal areas in China. The recorded extreme water level (m.s.l. in flood season has been heavily interfered with by varied income flood flow, sea-level rise, and dredged riverbeds. A methodology, composed of a numerical model and the index R, has been developed to quantify the impacts of these driving factors in the the PRD. Results show that the flood level varied 4.29%–53.49% from the change of fluvial discharge, 3.35%–38.73% from riverbed dredging, and 0.12%–16.81% from sea-level rise. The variation of flood flow apparently takes the most effect and sea-level rise the least. In particular, dense river network intensifies the impact of income flood change and sea-level rise. Findings from this study help understand the causes of the the PRD flood regimes and provide theoretical support for flood protection in the delta region.

Ecological Vulnerability Assessment Based on Fuzzy Analytical Method and Analytic Hierarchy Process in Yellow River Delta.

Science.gov (United States)

Wu, Chunsheng; Liu, Gaohuan; Huang, Chong; Liu, Qingsheng; Guan, Xudong

2018-04-25

The Yellow River Delta (YRD), located in Yellow River estuary, is characterized by rich ecological system types, and provides habitats or migration stations for wild birds, all of which makes the delta an ecological barrier or ecotone for inland areas. Nevertheless, the abundant natural resources of YRD have brought huge challenges to the area, and frequent human activities and natural disasters have damaged the ecological systems seriously, and certain ecological functions have been threatened. Therefore, it is necessary to determine the status of the ecological environment based on scientific methods, which can provide scientifically robust data for the managers or stakeholders to adopt timely ecological protection measures. The aim of this study was to obtain the spatial distribution of the ecological vulnerability (EV) in YRD based on 21 indicators selected from underwater status, soil condition, land use, landform, vegetation cover, meteorological conditions, ocean influence, and social economy. In addition, the fuzzy analytic hierarchy process (FAHP) method was used to obtain the weights of the selected indicators, and a fuzzy logic model was constructed to obtain the result. The result showed that the spatial distribution of the EV grades was regular, while the fuzzy membership of EV decreased gradually from the coastline to inland area, especially around the river crossing, where it had the lowest EV. Along the coastline, the dikes had an obviously protective effect for the inner area, while the EV was higher in the area where no dikes were built. This result also showed that the soil condition and groundwater status were highly related to the EV spatially, with the correlation coefficients −0.55 and −0.74 respectively, and human activities had exerted considerable pressure on the ecological environment.

The impact of Cyclone Nargis on the Ayeyarwady (Irrawaddy) River delta shoreline and nearshore zone (Myanmar): Towards degraded delta resilience?

Science.gov (United States)

Besset, Manon; Anthony, Edward J.; Dussouillez, Philippe; Goichot, Marc

2017-10-01

The Ayeyarwady River delta (Myanmar) is exposed to tropical cyclones, of which the most devastating has been cyclone Nargis (2-4 May 2008). We analysed waves, flooded area, nearshore suspended sediments, and shoreline change from satellite images. Suspended sediment concentrations up to 40% above average during the cyclone may reflect fluvial mud supply following heavy rainfall and wave reworking of shoreface mud. Massive recession of the high-water line resulted from backshore flooding by cyclone surge. The shoreline showed a mean retreat of 47 m following Nargis. Erosion was stronger afterwards (-148 m between August 2008 and April 2010), largely exceeding rates prior to Nargis (2000-2005: -2.14 m/year) and over 41 years (1974-2015: -0.62 m/year). This implies that resilience was weak following cyclone impact. Consequently, the increasingly more populous Ayeyarwady delta, rendered more and more vulnerable by decreasing fluvial sediment supply, could, potentially, become more severely impacted by future high-energy events.

Suspended sediment data analysis: Mackenzie Delta, NWT 1992-93 update [and] Westbank Tributaries, Mackenzie River, NWT

Energy Technology Data Exchange (ETDEWEB)

Carson, M A

1993-03-01

A full analysis and review of sediment data collected in 1991 as part of a program dealing with sediment-related aspects of northern hydrocarbon development is presented. The data were collected at two delta-head stations, three mid-delta stations, and three outer-delta stations. The primary purpose of the program is to obtain mathematical relationships that will allow prediction of sediment concentration at delta stations in the absence of actual sampling. This task is a prerequisite to the development of a sediment adjunct to the one-dimensional hydraulic model being developed for the delta. Preliminary analysis indicates strong correlations between sediment concentrations at different stations in the delta. It is tentatively proposed that sediment concentrations at all east-central stations in the delta could be predicted from samples concentrations at Inuvik, and that concentrations on the west side could be predictable from Peel River Station. The second part of this report deals with suspended sediment data analysis for the westbank tributaries of the Mackenzie River. 19 refs., 36 figs., 29 tabs.

Distribution of human papilloma virus genotype prevalence in invasive cervical carcinomas and precancerous lesions in the Yangtze River Delta area, China.

Science.gov (United States)

Wang, Hongyun; Cheng, Xiaodong; Ye, Jing; Xu, Xiuyun; Hong, Ying; Sui, Long; You, Zhixue; Xie, Xing

2018-04-27

This study aimed to provide more information for cancer prevention strategies by determining the distribution of human papilloma virus (HPV) genotype prevalence in invasive cervical carcinoma (ICC) and precancerous lesion patients in the Yangtze River Delta area in China. This multi-centre descriptive cross-sectional study involves four university hospitals in the Jiangzhehu area. Women with histologically confirmed cervical intraepithelial neoplasia (CIN) 1, CIN2, CIN3 or ICC who were diagnosed and treated in the four selected hospitals between February 2012 and April 2014 were eligible for recruitment. The average age of the patients was 40.93 ± 11.87 years old, among whom the youngest was 17 years old and the oldest was 76 years old.Those with immunodeficiency diseases or a previous history of cancer or CIN were excluded. HPV genotyping was performed by a central laboratory. The distribution and age and disease specificity of the HPV genotype prevalence were analysed. Of the 2181 collected samples, 251 were ICC and 1930 were CIN. The mean age of cervical cancer and CIN patients was 40.93 ± 11.8 years (range, 17-76 years). The five most commonly identified HPV types in each lesion class were as follows: CIN1: 52, 58, 16, 33, and CP; CIN2: 16, 58, 52, 33, and 31; CIN3: 16, 58, 33, 52, and 31; and ICC: 16, 58, 18, 52, and 33. CIN1 had an earlier age of onset (30-40 years) than CIN2, CIN3, and cervical cancer. The age of onset of cervical cancer exhibited two peaks at 40-44 and 50-54 years of age. In all infected patients, the frequency of HPV infection with a single type was 62.9%, and with multiple types, it was 38.1%. There was no difference in the frequencies of multiple types amongst the different cervical lesions. The most prevalent genotypes in the investigated area (52, 58, 16 and 18) justify the necessity of anti-HPV vaccination in teenagers and young girls under 24 years old in the Yangtze River Delta area in China. Infection with

Controls of {delta}{sup 34}S and {delta}{sup 18}O in dissolved sulphate: Learning from a detailed survey in the Llobregat River (Spain)

Energy Technology Data Exchange (ETDEWEB)

Otero, Neus [Departament Cristal . lografia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Marti i Franques, s/n, 08028 Barcelona (Spain); Grup d' Hidrogeoquimica, Departament de Geologia Ambiental, Institut de Ciencies de la Terra ' Jaume Almera' , CSIC, Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain)], E-mail: notero@ub.edu; Soler, Albert; Canals, Angels [Departament Cristal . lografia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Marti i Franques, s/n, 08028 Barcelona (Spain)

2008-05-15

The S and O isotopic composition of dissolved SO{sub 4}, used as a tracer for SO{sub 4} sources, was applied to the water of the Llobregat River system (NE Spain). The survey was carried out at 30 sites where surface water was sampled on a monthly basis over a period of 2a. The concentration of dissolved SO{sub 4} varied from 20 to 1575 mg L{sup -1}. Sulphur isotopic compositions clustered in two populations: one - 93% of the samples - had positive values with a mode of +9 per mille ; the other had negative values and a mode of -5 per mille . Data for {delta}{sup 18}O{sub SO{sub 4}} showed a mean value of +11 per mille , with no bi-modal distribution, though lower values of {delta}{sup 18}O corresponded to samples with negative {delta}{sup 34}S. These values can not be explained solely by the contribution of bedrock SO{sub 4} sources: that is, sulphide oxidation and the weathering of outcrops of sulphates, though numerous chemical sediments exist in the basin. Even in a river with a high concentration of natural sources of dissolved SO{sub 4}, such as the Llobregat River, the {delta}{sup 34}S values suggest that dissolved SO{sub 4} is controlled by a complex mix of both natural and anthropogenic sources. The main anthropogenic sources in this basin are fertilizers, sewage, potash mine effluent and power plant emissions. Detailed river water sampling, together with the chemical and isotopic characterisation of the main anthropogenic inputs, allowed determination of the influence of redox processes, as well as identification of the contribution of natural and anthropogenic SO{sub 4} sources and detection of spatial variations and seasonal changes among these sources. For instance, in the Llobregat River the input of fertilisers is well marked seasonally. Minimum values of {delta}{sup 34}S are reported during fertilization periods - from January to March - indicating a higher contribution of this source. The dual isotope approach, {delta}{sup 34}S and {delta}{sup 18}O

Holocene evolution of a wave-dominated fan-delta: Godavari delta, India

Science.gov (United States)

Saito, Y.; Nageswara Rao, K.; Nagakumar, K.; Demudu, G.; Rajawat, A.; Kubo, S.; Li, Z.

2013-12-01

The Godavari delta is one of the world's largest wave-dominated deltas. The Godavari River arises in the Western Ghats near the west coast of India and drains an area of about 3.1x10^5 km^2, flowing about 1465 km southeast across the Indian peninsula to the Bay of Bengal. The Godavari delta consists of a gentle seaward slope from its apex (12 m elevation) at Rajahmundry and a coastal beach-ridge plain over a distance of about 75 km and covers ~5200 km^2 as a delta plain. The river splits into two major distributary channels, the Gautami and the Vasishta, at a barrage constructed in the mid-1800s. The coastal environment of the deltaic coast is microtidal (~1 m mean tidal range) and wave-dominated (~1.5 m mean wave height in the June-September SW monsoon season, ~0.8 m in the NE monsoon season). Models of the Holocene evolution of the Godavari delta have changed from a zonal progradation model (e.g. Nageswara Rao & Sadakata, 1993) to a truncated cuspate delta model (Nageswara Rao et al., 2005, 2012). Twelve borehole cores (340 m total length), taken in the coastal delta plain during 2010-2013, yielded more than 100 C-14 dates. Sediment facies and C-14 dates from these and previous cores and remote-sensing data support a new delta evolution model. The Holocene coastal delta plain is divided into two parts by a set of linear beach ridges 12-14 km landward from the present shoreline in the central part of the delta. The location of the main depocenter (lobe) has shifted during the Holocene from 1) the center to 2) the west, 3) east, 4) center, 5) west, and 6) east. The linear beach ridges separate the first three from the last three stages. These lobe shifts are controlled by river channel shifts near the apex. Just as the current linear shoreline of the central part of the delta and the concave-up nearshore topography are the result of coastal erosion of a cuspate delta, the linear beach ridges indicate a former eroded shoreline. An unconformity within the deltaic

Sedimentology of Fraser River delta peat deposits: a modern analogue for some deltaic coals

Energy Technology Data Exchange (ETDEWEB)

Styan, W B; Bustin, R M

1984-01-01

On the Recent lobe of the Fraser River delta, peat accumulation has actively occurred on the distal lower delta plain, the transition between upper and lower delta plains, and the alluvial plain. Distal lower delta plain peats developed from widespread salt and brackish marshes and were not influenced appreciably by fluvial activity. Lateral development of the marsh facies were controlled by compaction and eustatic sea-level rise. The resulting thin, discontinuous peat network contains numerous silty clay partings and high concentrations of sulphur. Freshwater marsh facies formed but were later in part eroded and altered by transgressing marine waters. Peats overlie a thin, fluvial, fining-upward sequence which in turn overlies a thick, coarsening-upward, prodelta-delta front succession. Lower- upper delta plain peats initially developed from interdistributary brackish marshes and were later fluvially influenced as the delta prograded. Thickest peats occur in areas where distributary channels were abandoned earliest. Sphagnum biofacies replace sedge-grass-dominated communities except along active channel margins, where the sedge-grass facies is intercalated with overbank and splay deposits. Peats are underlain by a relatively thin sequence of fluvial deposits which in turn is underlain by a major coarsening-upward delta front and pro-delta sequence. Alluvial plain peats accumulated in back swamp environments of the flood plain. Earliest sedge-clay and gyttja peats developed over thin fining-upward fluvial cycles or are interlaminated with fine-grained flood deposits. Thickest accumulations occur where peat fills small avulsed flood channels. Overlying sedge-grass and sphagnum biofacies are horizontally stratified and commonly have sharp boundaries with fine-grained flood sediments. At active channel margins, however, sedge-grass peats are intercalated with natural levee deposits consisting of silty clay.

How Rapid Change Affects Deltas in the Arctic Region

Science.gov (United States)

Overeem, I.; Bendixen, M.

2017-12-01

Deltas form where the river drains into the ocean. Consequently, delta depositional processes are impacted by either changes in the respective river drainage basin or by changes in the regional marine environment. In a warming Arctic region rapid change has occurred over the last few decades in both the terrestrial domain as well as in the marine domain. Important terrestrial controls include 1) change in permafrost possibly destabilizing river banks, 2) strong seasonality of river discharge due to a short melting season, 3) high sediment supply if basins are extensively glaciated, 4) lake outbursts and ice jams favoring river flooding. Whereas in the Arctic marine domain sea ice loss promotes wave and storm surge impact, and increased longshore transport. We here ask which of these factors dominate any morphological change in Arctic deltas. First, we analyze hydrological data to assess change in Arctic-wide river discharge characteristics and timing, and sea ice concentration data to map changes in sea ice regime. Based on this observational analysis we set up a number of scenarios of change. We then model hypothetical small-scale delta formation considering change in these primary controls by setting up a numerical delta model, and combining it dynamically with a permafrost model. We find that for typical Greenlandic deltas changes in river forcing due to ice sheet melt dominate the morphological change, which is corroborated by mapping of delta progradation from aerial photos and satellite imagery. Whereas in other areas, along the North Slope and the Canadian Arctic small deltas are more stable or experienced retreat. Our preliminary coupled model allows us to further disentangle the impact of major forcing factors on delta evolution in high-latitude systems.

Ground-level ozone in the Pearl River Delta and the roles of VOC and NO(x) in its production.

Science.gov (United States)

Shao, Min; Zhang, Yuanhang; Zeng, Limin; Tang, Xiaoyan; Zhang, Jing; Zhong, Liuju; Wang, Boguang

2009-01-01

In many regions of China, very rapid economic growth has been accompanied by air pollution caused by vehicle emissions. In one of these regions, the Pearl River Delta, the variations of ground-level ozone and its precursors were investigated. Overall, the ambient concentrations of NO(2) increased quickly between 1995 and 1996, but then slightly decreased due to stringent nitrogen oxide (NO(x)) emission controls. Nonetheless, ambient NO(2) levels in the Pearl River Delta remained high. The regional average concentrations of volatile organic compounds (VOCs) were 290 ppbC in summer and 190 ppbC in autumn. Local emissions and long-distance transportation of pollutants play important roles in the regional distribution of VOCs. Ambient O(3) production is significant in urban areas and also downwind of cities. The relative incremental reactivities (RIRs), determined by an observation-based model, showed that ground-level ozone formation in the Guangzhou urban area is generally limited by the concentrations of VOCs, but there are also measurable impacts of NO(x).

Nitrogen Leaching in Intensive Cropping Systems in Tam Duong District, Red River Delta of Vietnam

OpenAIRE

Trinh, M.V.; Keulen, van, H.; Roetter, R.P.

2010-01-01

The environmental and economic consequences of nitrogen (N) lost in rice-based systems in Vietnam is important but has not been extensively studied. The objective of this study was to quantify the amount of N lost in major cropping systems in the Red River Delta. An experiment was conducted in the Red River Delta of Vietnam, on five different crops including rose, daisy, cabbage, chili, and a rice–rice–maize rotation during 2004 and 2005. Core soil samples were taken periodically in 20-cm inc...

Surface-ground water interactions and hydrogeochemical evolution in a fluvio-deltaic setting: The case study of the Pinios River delta

Science.gov (United States)

Matiatos, Ioannis; Paraskevopoulou, Vasiliki; Lazogiannis, Konstantinos; Botsou, Fotini; Dassenakis, Manos; Ghionis, George; Alexopoulos, John D.; Poulos, Serafim E.

2018-06-01

River deltas sustain important ecosystems with rich biodiversity and large biomass, as well as human populations via the availability of water and food sources. Anthropogenic activities, such as urbanization, tourism and agriculture, may pose threats to river deltas. The knowledge of the factors controlling the regional water quality regime in these areas is important for planning sustainable use and management of the water resources. Here, hydrochemical methods and multivariate statistical techniques were combined to investigate the shallow aquifer of the Pinios River (Thessaly) deltaic plain with respect to water quality, hydrogeochemical evolution and interactions between groundwater and surface water bodies. Water quality assessment indicated that most of the river and groundwater samples fully comply with the criteria set by the Drinking Water Directive (98/83/EC). The river is recharged mainly from springs of the Tempi valley and the shallow aquifer, and to a lesser degree from precipitation, throughout the year. The hydrogeochemical characteristics indicated a cation (Ca, Mg, and Na) bicarbonate water type, which evolves to calcium-chloride, sodium-bicarbonate and sodium-chloride water type, in the northern part of the delta. Calcite and dolomite dissolution determined the major ion chemistry, but other processes, such as silicate weathering and cation exchange reactions, also contributed. In the northern part of the plain, the interaction with the deeper aquifer enriched the shallow aquifer with Na and Cl ions. Principal Component Analysis showed that five components (PCs) explain 77% of the total variance of water quality parameters; these are: (1) salinity; (2) water-silicate rocks interaction; (3) hardness due to calcite dissolution, and cation exchange processes; (4) nitrogen pollution; and (5) non-N-related artificial fertilizers. This study demonstrated that the variation of water hydrochemistry in the deltaic plain could be attributed to natural and

Rice-planted area extraction by time series analysis of ENVISAT ASAR WS data using a phenology-based classification approach: A case study for Red River Delta, Vietnam

Science.gov (United States)

Nguyen, D.; Wagner, W.; Naeimi, V.; Cao, S.

2015-04-01

Recent studies have shown the potential of Synthetic Aperture Radars (SAR) for mapping of rice fields and some other vegetation types. For rice field classification, conventional classification techniques have been mostly used including manual threshold-based and supervised classification approaches. The challenge of the threshold-based approach is to find acceptable thresholds to be used for each individual SAR scene. Furthermore, the influence of local incidence angle on backscatter hinders using a single threshold for the entire scene. Similarly, the supervised classification approach requires different training samples for different output classes. In case of rice crop, supervised classification using temporal data requires different training datasets to perform classification procedure which might lead to inconsistent mapping results. In this study we present an automatic method to identify rice crop areas by extracting phonological parameters after performing an empirical regression-based normalization of the backscatter to a reference incidence angle. The method is evaluated in the Red River Delta (RRD), Vietnam using the time series of ENVISAT Advanced SAR (ASAR) Wide Swath (WS) mode data. The results of rice mapping algorithm compared to the reference data indicate the Completeness (User accuracy), Correctness (Producer accuracy) and Quality (Overall accuracies) of 88.8%, 92.5 % and 83.9 % respectively. The total area of the classified rice fields corresponds to the total rice cultivation areas given by the official statistics in Vietnam (R2  0.96). The results indicates that applying a phenology-based classification approach using backscatter time series in optimal incidence angle normalization can achieve high classification accuracies. In addition, the method is not only useful for large scale early mapping of rice fields in the Red River Delta using the current and future C-band Sentinal-1A&B backscatter data but also might be applied for other rice

Development of a global river-coastal coupling model and its application to flood simulation in Asian mega-delta regions

Science.gov (United States)

Ikeuchi, Hiroaki; Hirabayashi, Yukiko; Yamazaki, Dai; Muis, Sanne; Ward, Philip; Verlaan, Martin; Winsemius, Hessel; Kanae, Shinjiro

2017-04-01

The world's mega-delta regions and estuaries are susceptible to various water-related disasters, such as river flooding and storm surge. Moreover, simultaneous occurrence of them would be more devastating than a situation where they occur in isolation. Therefore, it is important to provide information about compound risks of fluvial and coastal floods at a large scale, both their statistical dependency as well as their combined resulting flooding in delta regions. Here we report on a first attempt to address this issue globally by developing a method to couple a global river model (CaMa-Flood) and a global tide and surge reanalysis (GTSR) dataset. A state-of-the-art global river routing model, CaMa-Flood, was modified to represent varying sea levels due to tides and storm surges as downstream boundary condition, and the GTSR dataset was post-processed to serve as inputs to the CaMa-Flood river routing simulation and a long-term simulation was performed to incorporate the temporal dependency between coastal tide and surge on the one hand, and discharge on the other. The coupled model was validated against observations, showing better simulation results of water levels in deltaic regions than simulation without GTSR. For example in the Ganges Delta, correlation coefficients were increased by 0.06, and root mean square errors were reduced by 0.22 m. Global coupling simulations revealed that storm surges affected river water levels in coastal regions worldwide, especially in low-lying flat areas with increases in water level larger than 0.5 m. By employing enhanced storm surge simulation with tropical storm tracks, we also applied the model to examine impacts of past hurricane and cyclone storm events on river flood inundation.

Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam

Science.gov (United States)

Unverricht, Daniel; Szczuciński, Witold; Stattegger, Karl; Jagodziński, Robert; Le, Xuan Thuyen; Kwong, Laval Liong Wee

2013-11-01

The Mekong River Delta is among the Asian mega-deltas and is influenced by various factors including tides (meso-tidal system), waves, coastal currents, monsoon-driven river discharge and human impact (agriculture, fishing, sand dredging, tourism). The present study aims to document the seafloor relief, sediment distribution and sediment accumulation rates to interpret modern sediment transport directions and main sedimentation processes in the subaqueous Mekong Delta. The major results of this investigation include the detection of two delta fronts 200 km apart, one at the mouth of the Bassac River (the biggest branch of the Mekong Delta) and the other around Cape Ca Mau (most south-western end of the Mekong Delta). Additionally, a large channel system runs in the subaqueous delta platform parallel to the shore and between the two fronts. The sediment accumulation rates vary greatly according to the location in the subaqueous delta and have reached up to 10 cm/yr for the last century. A cluster analysis of surface sediment samples revealed two different sediment types within the delta including a well-sorted sandy sediment and a poorly sorted, silty sediment. In addition, a third end member with medium to coarse sand characterised the distant parts of the delta at the transition to the open shelf. The increase of organic matter and carbonate content to the bottom set area and other sedimentary features such as shell fragments, foraminiferas and concretions of palaeo-soils that do not occur in delta sediments, supported grain size-based classification. Beginning in front of the Bassac River mouth, sedimentary pattern indicates clockwise sediment transport alongshore in the western direction to a broad topset area and the delta front around Cape Ca Mau. Our results clearly show the large lateral variability of the subaqueous Mekong Delta that is further complicated by strong monsoon-driven seasonality. River, tidal and wave forcing vary at local and seasonal scales

Effects of the proposed California WaterFix North Delta Diversion on survival of juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Sacramento-San Joaquin River Delta, northern California

Science.gov (United States)

Perry, Russell W.; Pope, Adam C.

2018-05-11

The California Department of Water Resources and Bureau of Reclamation propose new water intake facilities on the Sacramento River in northern California that would convey some of the water for export to areas south of the Sacramento-San Joaquin River Delta (hereinafter referred to as the Delta) through tunnels rather than through the Delta. The collection of water intakes, tunnels, pumping facilities, associated structures, and proposed operations are collectively referred to as California WaterFix. The water intake facilities, hereinafter referred to as the North Delta Diversion (NDD), are proposed to be located on the Sacramento River downstream of the city of Sacramento and upstream of the first major river junction where Sutter Slough branches from the Sacramento River. The NDD can divert a maximum discharge of 9,000 cubic feet per second (ft3 /s) from the Sacramento River, which reduces the amount of Sacramento River inflow into the Delta. In this report, we conduct four analyses to investigate the effect of the NDD and its proposed operation on survival of juvenile Chinook salmon (Oncorhynchus tshawytscha). All analyses used the results of a Bayesian survival model that allowed us to simulate travel time, migration routing, and survival of juvenile Chinook salmon migrating through the Delta in response to NDD operations, which affected both inflows to the Delta and operation of the Delta Cross Channel (DCC). For the first analysis, we evaluated the effect of the NDD bypass rules on salmon survival. The NDD bypass rules are a set of operational rule curves designed to provide adaptive levels of fish protection by defining allowable diversion rates as a function of (1) Sacramento River discharge as measured at Freeport, and (2) time of year when endangered runs requiring the most protection are present. We determined that all bypass rule curves except constant low-level pumping (maximum diversion of 900 ft3 /s) could cause a sizeable decrease in survival by as

Reservoir impacts downstream in highly regulated river basins: the Ebro delta and the Guadalquivir estuary in Spain

Directory of Open Access Journals (Sweden)

M. J. Polo

2016-05-01

Full Text Available Regulation by reservoirs affects both the freshwater regime and the sediment delivery at the area downstream, and may have a significant impact on water quality in the final transitional water bodies. Spain is one the countries with more water storage capacity by reservoirs in the world. Dense reservoir networks can be found in most of the hydrographic basins, especially in the central and southern regions. The spatial redistribution of the seasonal and annual water storage in reservoirs for irrigation and urban supply, mainly, has resulted in significant changes of water flow and sediment load regimes, together with a fostered development of soil and water uses, with environmental impacts downstream and higher vulnerability of these areas to the sea level rise and drought occurrence. This work shows these effects in the Guadalquivir and the Ebro River basins, two of the largest regulated areas in Spain. The results show a 71 % decrease of the annual freshwater input to the Guadalquivir River estuary during 1930–2014, an increase of 420 % of the irrigated area upstream the estuary, and suspended sediment loads up to 1000 % the initial levels. In the Ebro River delta, the annual water yield has decreased over a 30 % but, on the contrary, the big reservoirs are located in the main stream, and the sediment load has decreased a 99 %, resulting in a delta coastal regression up to 10 m per year and the massive presence of macrophytes in the lower river. Adaptive actions proposed to face these impacts in a sea level rise scenario are also analyzed.

Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

DEFF Research Database (Denmark)

Gilbert, Graham L.; Cable, Stefanie; Thiel, Christine

2017-01-01

The Zackenberg River delta is located in northeast Greenland (74 degrees 30' N, 20 degrees 30' E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2) formed during relative sea-level (RSL) fall. We investigated the depo......The Zackenberg River delta is located in northeast Greenland (74 degrees 30' N, 20 degrees 30' E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2) formed during relative sea-level (RSL) fall. We investigated...... the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL) dating. We identify four facies associations in sections (4 to 22 m in height) exposed along the modern Zackenberg River and coast. Facies associations relate to (I) overriding glaciers......, (II) retreating glaciers and quiescent glaciomarine conditions, (III) delta progradation in a fjord valley, and (IV) fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together...

Distribution and pollution, toxicity and risk assessment of heavy metals in sediments from urban and rural rivers of the Pearl River delta in southern China.

Science.gov (United States)

Xiao, Rong; Bai, Junhong; Huang, Laibin; Zhang, Honggang; Cui, Baoshan; Liu, Xinhui

2013-12-01

Sediments were collected from the upper, middle and lower reaches of both urban and rural rivers in a typical urbanization zone of the Pearl River delta. Six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) were analyzed in all sediment samples, and their spatial distribution, pollution levels, toxicity and ecological risk levels were evaluated to compare the characteristics of heavy metal pollution between the two rivers. Our results indicated that the total contents of the six metals in all samples exceeded the soil background value in Guangdong province. Based on the soil quality thresholds of the China SEPA, Cd levels at all sites exceeded class III criteria, and other metals exhibited pollution levels exceeding class II or III criteria at both river sites. According to the sediment quality guidelines of the US EPA, all samples were moderately to heavily polluted by Cr, Cu, Ni, Pb and Zn. Compared to rural river sites, urban river sites exhibited heavier pollution. Almost all sediment samples from both rivers exhibited moderate to serious toxicity to the environment, with higher contributions from Cr and Ni. A "hot area" of heavy metal pollution being observed in the upper and middle reaches of the urban river area, whereas a "hot spot" was identified at a specific site in the middle reach of the rural river. Contrary metal distribution patterns were also observed along typical sediment profiles from urban and rural rivers. However, the potential ecological risk indices of rural river sediments in this study were equal to those of urban river sediments, implying that the ecological health issues of the rivers in the undeveloped rural area should also be addressed. Sediment organic matter and grain size might be important factors influencing the distribution profiles of these heavy metals.

Recent coarsening of sediments on the southern Yangtze subaqueous delta front: A response to river damming

Science.gov (United States)

Yang, H. F.; Yang, S. L.; Meng, Y.; Xu, K. H.; Luo, X. X.; Wu, C. S.; Shi, B. W.

2018-03-01

After more than 50,000 dams were built in the Yangtze basin, especially the Three Gorges Dam (TGD) in 2003, the sediment discharge to the East China Sea decreased from 470 Mt/yr before dams to the current level of 140 Mt/yr. The delta sediment's response to this decline has interested many researchers. Based on a dataset of repeated samplings at 44 stations in this study, we compared the surficial sediment grain sizes in the southern Yangtze subaqueous delta front for two periods: pre-TGD (1982) and post-TGD (2012). External factors of the Yangtze River, including water discharge, sediment discharge and suspended sediment grain size, were analysed, as well as wind speed, tidal range and wave height of the coastal ocean. We found that the average median size of the sediments in the delta front coarsened from 8.0 μm in 1982 to 15.4 μm in 2012. This coarsening was accompanied by a decrease of clay components, better sorting and more positive skewness. Moreover, the delta morphology in the study area changed from an overall accretion of 1.0 cm/yr to an erosion of - 0.6 cm/yr. At the same time, the riverine sediment discharge decreased by 70%, and the riverine suspended sediment grain size increased from 8.4 μm to 10.5 μm. The annual wind speed and wave height slightly increased by 2% and 3%, respectively, and the tidal range showed no change trend. Considering the increased wind speed and wave height, there was no evidence that the capability of the China Coastal Current to transport sediment southward has declined in recent years. The sediment coarsening in the Yangtze delta front was thus mainly attributed to the delta's transition from accumulation to erosion which was originally generated by river damming. These findings have important implications for sediment change in many large deltaic systems due to worldwide human impacts.

Data on abiotic (nutrients and biotic (phytoplankton quality elements in Fortuna ecologically reconstructed area (Danube Delta Biosphere Reserve - Romania

Directory of Open Access Journals (Sweden)

TÖRÖK Liliana

2013-12-01

Full Text Available The impact of inorganic nutrient enrichment on reophillic ecosystems has been observed and intensively studied in many rivers. Due to the scarcity of information on ecological conditions in the channel-network of the Danube Delta it is very important to have reliable information on the trend of the abiotic and biotic quality elements in the Danube River and channel system – in order to fulfill the Water Framework Directive objectives and to implement the rehabilitation projects in area affected by nutrient pollution. The purpose of this paper is to present, analyze and discuss the results of evaluation of nutrient variation and phytoplankton quantification obtained in Fortuna area - one of the seven reconstructed areas of the Danube Delta Biosphere Reserve. In order to improve the quality of data on phytoplankton biomass distribution from Fortuna area, in the summer of 2008 there has been used a submersible spectrofluorometer with automatic algae class determination and chlorophyll analysis (bbe Fluoro Probe. According to the results of analyses on relation between phytoplankton communities and water-column, the phytoplankton development in the channel network of the Fortuna reconstructed area seems to be influenced mainly by nitrogen concentration than by phosphorus concentration, as in case of phytoplankton development in Danube Delta’s lakes

River-plume sedimentation and 210Pb/7Be seabed delivery on the Mississippi River delta front

Science.gov (United States)

Keller, Gregory; Bentley, Samuel J.; Georgiou, Ioannis Y.; Maloney, Jillian; Miner, Michael D.; Xu, Kehui

2017-06-01

To constrain the timing and processes of sediment delivery and submarine mass-wasting events spanning the last few decades on the Mississippi River delta front, multi-cores and gravity cores (0.5 and water depth in 2014. The cores were analyzed for radionuclide activity (7Be, 210Pb, 137Cs), grain size, bulk density, and fabric (X-radiography). Core sediments are faintly bedded, sparsely bioturbated, and composed mostly of clay and fine silt. Short-term sedimentation rates (from 7Be) are 0.25-1.5 mm/day during river flooding, while longer-term accumulation rates (from 210Pb) are 1.3-7.9 cm/year. In most cores, 210Pb activity displays undulatory profiles with overall declining activity versus depth. Undulations are not associated with grain size variations, and are interpreted to represent variations in oceanic 210Pb scavenging by river-plume sediments. The 210Pb profile of one gravity core from a mudflow gully displays uniform basal excess activity over a zone of low and uniform bulk density, interpreted to be a mass-failure event that occurred 9-18 years before core collection. Spatial trends in sediment deposition (from 7Be) and accumulation (from 210Pb) indicate that proximity to the river mouth has stronger influence than local facies (mudflow gully, depositional lobe, prodelta) over the timeframe and seabed depth represented by the cores (sediment deposition from river plumes coupled with infrequent tropical cyclone activity near the delta in the last 7 years (2006-2013), and by the location of most sediment failure surfaces (from mass flows indicated by parallel geophysical studies) deeper than the core-sampling depths of the present study.

Dispersion Mechanisms of a Tidal River Junction in the Sacramento–San Joaquin Delta, California

Directory of Open Access Journals (Sweden)

Karla T. Gleichauf

2014-12-01

Full Text Available doi: http://dx.doi.org/10.15447/sfews.2014v12iss4art1In branching channel networks, such as in the Sacramento–San Joaquin River Delta, junction flow dynamics contribute to dispersion of ecologically important entities such as fish, pollutants, nutrients, salt, sediment, and phytoplankton. Flow transport through a junction largely arises from velocity phasing in the form of divergent flow between junction channels for a portion of the tidal cycle. Field observations in the Georgiana Slough junction, which is composed of the North and South Mokelumne rivers, Georgiana Slough, and the Mokelumne River, show that flow phasing differences between these rivers arise from operational, riverine, and tidal forcing. A combination of Acoustic Doppler Current Profile (ADCP boat transecting and moored ADCPs over a spring–neap tidal cycle (May to  June 2012 monitored the variability of spatial and temporal velocity, respectively. Two complementary drifter studies enabled assessment of local transport through the junction to identify small-scale intrajunction dynamics. We supplemented field results with numerical simulations using the SUNTANS model to demonstrate the importance of phasing offsets for junction transport and dispersion. Different phasing of inflows to the junction resulted in scalar patchiness that is characteristic of MacVean and Stacey’s (2011 advective tidal trapping. Furthermore, we observed small-scale junction flow features including a recirculation zone and shear layer, which play an important role in intra-junction mixing over time scales shorter than the tidal cycle (i.e., super-tidal time scales. The study period spanned open- and closed-gate operations at the Delta Cross Channel. Synthesis of field observations and modeling efforts suggest that management operations related to the Delta Cross Channel can strongly affect transport in the Delta by modifying the relative contributions of tidal and riverine flows, thereby

Top-down estimates of benzene and toluene emissions in Pearl River Delta and Hong Kong, China

OpenAIRE

X. Fang; M. Shao; A. Stohl; Q. Zhang; J. Zheng; H. Guo; C. Wang; M. Wang; J. Ou; R. L. Thompson; R. G. Prinn

2015-01-01

Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and tolu...

Relationship of urinary arsenic metabolites to intake estimates in residents of the Red River Delta, Vietnam

Energy Technology Data Exchange (ETDEWEB)

Agusa, Tetsuro [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Department of Legal Medicine, Shimane University Faculty of Medicine, Enya 89-1, Izumo 693-8501 (Japan); Kunito, Takashi [Department of Environmental Sciences, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621 (Japan); Minh, Tu Binh [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Department of Biology and Chemistry (BCH), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Pham Thi Kim Trang [Center for Environmental Technology and Sustainable Development (CETASD), Hanoi National University, 334 Nguyen Trai Street, Thanh Xuan, Hanoi (Viet Nam); Iwata, Hisato [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Pham Hung Viet [Center for Environmental Technology and Sustainable Development (CETASD), Hanoi National University, 334 Nguyen Trai Street, Thanh Xuan, Hanoi (Viet Nam); Tanabe, Shinsuke [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan)], E-mail: shinsuke@agr.ehime-u.ac.jp

2009-02-15

This study investigated the status of arsenic (As) exposure from groundwater and rice, and its methylation capacity in residents from the Red River Delta, Vietnam. Arsenic levels in groundwater ranged from <1.8 to 486 {mu}g/L. Remarkably, 86% of groundwater samples exceeded WHO drinking water guideline of 10 {mu}g/L. Also, estimated inorganic As intake from groundwater and rice were over Provisional Tolerable Weekly Intake (15 {mu}g/week/kg body wt.) by FAO/WHO for 92% of the residents examined. Inorganic As and its metabolite (monomethylarsonic acid and dimethylarsinic acid) concentrations in human urine were positively correlated with estimated inorganic As intake. These results suggest that residents in these areas are exposed to As through consumption of groundwater and rice, and potential health risk of As is of great concern for these people. Urinary concentration ratios of dimethylarsinic acid to monomethylarsonic acid in children were higher than those in adults, especially among men, indicating greater As methylation capacity in children. - Positive correlations between estimated arsenic intake and urinary inorganic arsenic and its metabolites were observed in human from the Red River Delta, Vietnam.

Relationship of urinary arsenic metabolites to intake estimates in residents of the Red River Delta, Vietnam

International Nuclear Information System (INIS)

Agusa, Tetsuro; Kunito, Takashi; Minh, Tu Binh; Pham Thi Kim Trang; Iwata, Hisato; Pham Hung Viet; Tanabe, Shinsuke

2009-01-01

This study investigated the status of arsenic (As) exposure from groundwater and rice, and its methylation capacity in residents from the Red River Delta, Vietnam. Arsenic levels in groundwater ranged from <1.8 to 486 μg/L. Remarkably, 86% of groundwater samples exceeded WHO drinking water guideline of 10 μg/L. Also, estimated inorganic As intake from groundwater and rice were over Provisional Tolerable Weekly Intake (15 μg/week/kg body wt.) by FAO/WHO for 92% of the residents examined. Inorganic As and its metabolite (monomethylarsonic acid and dimethylarsinic acid) concentrations in human urine were positively correlated with estimated inorganic As intake. These results suggest that residents in these areas are exposed to As through consumption of groundwater and rice, and potential health risk of As is of great concern for these people. Urinary concentration ratios of dimethylarsinic acid to monomethylarsonic acid in children were higher than those in adults, especially among men, indicating greater As methylation capacity in children. - Positive correlations between estimated arsenic intake and urinary inorganic arsenic and its metabolites were observed in human from the Red River Delta, Vietnam

Coastal processes of the Elwha River delta: Chapter 5 in Coastal habitats of the Elwha River, Washington--biological and physical patterns and processes prior to dam removal

Science.gov (United States)

Warrick, Jonathan A.; Stevens, Andrew W.; Miller, Ian M.; Gelfenbaum, Guy; Duda, Jeffrey J.; Warrick, Jonathan A.; Magirl, Christopher S.

2011-01-01

To understand the effects of increased sediment supply from dam removal on marine habitats around the Elwha River delta, a basic understanding of the region’s coastal processes is necessary. This chapter provides a summary of the physical setting of the coast near the Elwha River delta, for the purpose of synthesizing the processes that move and disperse sediment discharged by the river. One fundamental property of this coastal setting is the difference between currents in the surfzone with those in the coastal waters offshore of the surfzone. Surfzone currents are largely dictated by the direction and size of waves, and the waves that attack the Elwha River delta predominantly come from Pacific Ocean swell from the west. This establishes surfzone currents and littoral sediment transport that are eastward along much of the delta. Offshore of the surfzone the currents are largely influenced by tidal circulation and the physical constraint to flow provided by the delta’s headland. During both ebbing and flooding tides, the flow separates from the coast at the tip of the delta’s headland, and this produces eddies on the downstream side of the headland. Immediately offshore of the Elwha River mouth, this creates a situation in which the coastal currents are directed toward the east much more frequently than toward the west. This suggests that Elwha River sediment will be more likely to move toward the east in the coastal system.

Mapping Soil Carbon in the Yukon Kuskokwim River Delta Alaska

Science.gov (United States)

Natali, S.; Fiske, G.; Schade, J. D.; Mann, P. J.; Holmes, R. M.; Ludwig, S.; Melton, S.; Sae-lim, N.; Jardine, L. E.; Navarro-Perez, E.

2017-12-01

Arctic river deltas are hotspots for carbon storage, occupying 10% of carbon stored in arctic permafrost. The Yukon Kuskokwim (YK) Delta, Alaska is located in the lower latitudinal range of the northern permafrost region in an area of relatively warm permafrost that is particularly vulnerable to warming climate. Active layer depths range from 50 cm on peat plateaus to >100 cm in wetland and aquatic ecosystems. The size of the soil organic carbon pool and vulnerability of the carbon in the YK Delta is a major unknown and is critically important as climate warming and increasing fire frequency may make this carbon vulnerable to transport to aquatic and marine systems and the atmosphere. To characterize the size and distribution of soil carbon pools in the YK Delta, we mapped the land cover of a 1910 km2 watershed located in a region of the YK Delta that was impacted by fire in 2015. The map product was the result of an unsupervised classification using the Weka K Means clustering algorithm implemented in Google's Earth Engine. Inputs to the classification were Worldview2 resolution optical imagery (1m), Arctic DEM (5m), and Sentinel 2 level 1C multispectral imagery, including NDVI, (10 m). We collected 100 soil cores (0-30 cm) from sites of different land cover and landscape position, including moist and dry peat plateaus, high and low intensity burned plateaus, fens, and drained lakes; 13 lake sediment cores (0-50 cm); and 20 surface permafrost cores (to 100 cm) from burned and unburned peat plateaus. Active layer and permafrost soils were analyzed for organic matter content, soil moisture content, and carbon and nitrogen pools (30 and 100 cm). Soil carbon content varied across the landscape; average carbon content values for lake sediments were 12% (5- 17% range), fens 26% (9-44%), unburned peat plateaus 41% (34-44%), burned peat plateaus 19% (7-34%). These values will be used to estimate soil carbon pools, which will be applied to the spatial extent of each

Challenges, Approaches and Experiences from Asian Deltas and the Rhine-Meuse Delta : Regional Training Workshop on Delta Planning and Management

NARCIS (Netherlands)

Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

2013-01-01

River delta's, like the Mekong Delta (Vietnam), Ganges-Brahmaputra Delta (Bangladesh), Ayeyarwady Delta (Myanmar), Nile (Egypt) and Ciliwung Delta (Indonesia) are developing rapidly and are characterised by large-scale urbanisation and industrialization processes. They are facing serious planning

Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China

Directory of Open Access Journals (Sweden)

Y. Wang

2011-12-01

Full Text Available Seven-year measurements of precipitation, lightning flashes, and visibility from 2000 to 2006 have been analyzed in the Pearl River Delta (PRD region, China, with a focus on the Guangzhou megacity area. Statistical analysis shows that the occurrence of heavy rainfall (>25 mm per day and frequency of lightning strikes are reversely correlated to visibility during this period. To elucidate the effects of aerosols on cloud processes, precipitation, and lightning activity, a cloud resolving – Weather Research and Forecasting (CR-WRF model with a two-moment bulk microphysical scheme is employed to simulate a mesoscale convective system occurring on 28 Match 2009 in the Guangzhou megacity area. The model predicted evolutions of composite radar reflectivity and accumulated precipitation are in agreement with measurements from S-band weather radars and automatic gauge stations. The calculated lightning potential index (LPI exhibits temporal and spatial consistence with lightning flashes recorded by a local lightning detection network. Sensitivity experiments have been performed to reflect aerosol conditions representative of polluted and clean cases. The simulations suggest that precipitation and LPI are enhanced by about 16% and 50%, respectively, under the polluted aerosol condition. Our results suggest that elevated aerosol loading suppresses light and moderate precipitation (less than 25 mm per day, but enhances heavy precipitation. The responses of hydrometeors and latent heat release to different aerosol loadings reveal the physical mechanism for the precipitation and lightning enhancement in the Guangzhou megacity area, showing more efficient mixed phase processes and intensified convection under the polluted aerosol condition.

Regional dynamics of persistent organic pollutants (POPs) in the Pearl River Delta, China: Implications and perspectives

International Nuclear Information System (INIS)

Zhang Kai; Zhang Baozhong; Li Shaomeng; Zeng, Eddy Y.

2011-01-01

The mass transport budgets of 1,1,1-trichloro-2,2-bis(chlorophenyl)ethane (p,p'-DDT) and decabromodiphenyl ether (BDE-209) in the Pearl River Delta, South China were calculated based on previously collected data. Residual p,p'-DDT, mostly related to historical use, has largely settled into soil (780,000 kg), while the soil BDE-209 inventory (44,000 kg) is considerably smaller. Conversely, large amounts of BDE-209 currently used in numerous commercial products have resulted in a much higher atmospheric depositional flux of BDE-209 (28,100 kg/yr) relative to p,p'-DDT (310 kg/yr). The soil inventory of p,p'-DDT is predicted to decrease to half of its current value after 22 years, and the percent area containing soil p,p'-DDT at levels exceeding the effects range-medium (27 ng/g) will decrease from 40% to 20%. Finally, soil BDE-209 inventory will reach an equilibrium value of 940 tons in ∼60 years, when BDE-209 levels in 50% of soil will be above an equivalent risk guideline value (125 ng/g). - Highlights: → Transport budgets of p,p'-DDT and BDE-209 in the Pearl River Delta were built. → Dry aerial deposition is the dominant route to transport p,p'-DDT and BDE-209. → Soil inventory of p,p'-DDT is much larger than that of BDE-209. → Soil inventory of p,p'-DDT would decline to half of its current value in 22 years. → Soil BDE-209 inventory is expected to reach an equilibrium value in ∼60 years. - Regional dynamics of p,p'-DDT and BDE-209 in the Pearl River Delta (South China) are examined and used to predict temporal variances.

Human induced discharge diversion in a tropical delta and its environmental implications: The Patía River, Colombia

Science.gov (United States)

Restrepo, Juan D.; Kettner, Albert

2012-03-01

SummaryThe Patía River, the number one in terms of sediment yield ˜1500 t km-2 yr-1 draining the western South America, has the most extensive and well developed delta on the Pacific coast, measuring 1700 km2. During the Holocene, nature forced the Patía delta to the south; however, a major water diversion, starting in 1972, diverted the Patía flow to the Sanguianga River, the latter, a small stream draining internal lakes from the Pacific lowlands. This human induced discharge diversion shifted the active delta plain back to the north and changed the northern estuarine system into an active delta plain. Overall, major environmental consequences of this discharge diversion in terms of morphological changes along the delta coast and distributary channels, are evidenced by: (1) coastal retreat along the abandoned delta lobe; 63% of the southern shoreline is retreating at maximum rates of 7 m yr-1, with a corresponding coastal land loss of 106 m yr-1; (2) transgressive barrier islands with exposed peat soils in the surf zone; (3) abandonment of former active distributaries in the southern delta plain with associated closing of inlets and formation of ebb tidal deltas; (4) breaching events on barrier islands; and (5) distributary channel accretion in the northern delta plain by morphological processes such as sedimentation (also in crevasses), overbank flow, increasing width of levees, interdistributary channel fill, and colonization of pioneer mangrove. The Sanguianga Mangrove National Park (SMNP), the largest mangrove reserve in Colombia, measuring 800 km2, lies in this former estuary, where major hydrologic and sedimentation changes are occurring. Observed environmental changes in the SMNP, include (1) seaward advance of the sub-aqueous delta front at the Sanquianga inlet evidenced by an increase in tidal flat area from 5.4 Mm2 in 1986 to 14 Mm2 in 2001; (2) freshening conditions in the Sanguianga distributary channel, a hydrologic change that has shifted the

Process connectivity in a naturally prograding river delta

Science.gov (United States)

Sendrowski, Alicia; Passalacqua, Paola

2017-03-01

River deltas are lowland systems that can display high hydrological connectivity. This connectivity can be structural (morphological connections), functional (control of fluxes), and process connectivity (information flow from system drivers to sinks). In this work, we quantify hydrological process connectivity in Wax Lake Delta, coastal Louisiana, by analyzing couplings among external drivers (discharge, tides, and wind) and water levels recorded at five islands and one channel over summer 2014. We quantify process connections with information theory, a branch of mathematics concerned with the communication of information. We represent process connections as a network; variables serve as network nodes and couplings as network links describing the strength, direction, and time scale of information flow. Comparing process connections at long (105 days) and short (10 days) time scales, we show that tides exhibit daily synchronization with water level, with decreasing strength from downstream to upstream, and that tides transfer information as tides transition from spring to neap. Discharge synchronizes with water level and the time scale of its information transfer compares well to physical travel times through the system, computed with a hydrodynamic model. Information transfer and physical transport show similar spatial patterns, although information transfer time scales are larger than physical travel times. Wind events associated with water level setup lead to increased process connectivity with highly variable information transfer time scales. We discuss the information theory results in the context of the hydrologic behavior of the delta, the role of vegetation as a connector/disconnector on islands, and the applicability of process networks as tools for delta modeling results.

Fingerprinting analysis and characterization of hydrocarbons in sediments of the Pearl River Delta in China

International Nuclear Information System (INIS)

Yang, C.; Wang, Z.; Hollebone, B.; Yang, Z.; Brown, C.; Landriault, M.; Peng, X.

2009-01-01

This paper reported on a study that used gas chromatography-mass spectrometry (GC-MS) and gas chromatography flame ionization detection (GC-FID) to investigate and characterize the contamination in southern China's Pearl River Delta, with particular reference to contamination from petroleum,n-alkanes, polycyclic aromatic hydrocarbons (PAHs), biomarkers and diamondoid compounds. Forensic analysis of sediments was necessary in order to decode the contamination history and evaluate the contamination level of the aquatic ecosystem. The contamination of the Pearl River Delta sediment was derived from various inputs, including petrogenic, biogenic and pyrogenic sources. However, in addition to identifying PAHs and biomarker terpanes and steranes, the detection of trace diamondoid compounds in the sediments demonstrated that the pollution in the river was derived partially from petroleum sources. Diamondoids are a class of saturated hydrocarbons that consist of three-dimensionally fused cyclohexane rings. They occur naturally in source rocks, crude oils, intermediate petroleum distillates, and finished petroleum products. They are more resistant to biodegradation than most other petroleum compounds such as n-alkanes. As such, they can play an important role in identifying and characterizing petroleum contamination in the environment. It was concluded that the petroleum contamination in the Pearl River Delta is attributed to the mixture of medium to heavy petroleum residues. 31 refs., 6 tabs., 4 figs

Study on Spatial Spillover Effects of Logistics Industry Development for Economic Growth in the Yangtze River Delta City Cluster Based on Spatial Durbin Model.

Science.gov (United States)

Xu, Xinxing; Wang, Yuhong

2017-12-04

The overall entropy method is used to evaluate the development level of the logistics industry in the city based on a mechanism analysis of the spillover effect of the development of the logistics industry on economic growth, according to the panel data of 26 cities in the Yangtze River delta. On this basis, the paper uses the spatial durbin model to study the direct impact of the development of the logistics industry on economic growth and the spatial spillover effect. The results show that the direct impact coefficient of the development of the logistics industry in the Yangtze River Delta urban agglomeration on local economic growth is 0.092, and the significant spatial spillover effect on the economic growth in the surrounding area is 0.197. Compared with the labor force input, capital investment and the degree of opening to the world, and government functions, the logistics industry's direct impact coefficient is the largest, other than capital investment; the coefficient of the spillover effect is higher than other control variables, making it a "strong engine" of the Yangtze River Delta urban agglomeration economic growth.

Polybrominated diphenyl ethers in surface sediments of the Yangtze River Delta: Levels, distribution and potential hydrodynamic influence

International Nuclear Information System (INIS)

Chen Shejun; Gao Xiaojiang; Mai Bixian; Chen Zhuomin; Luo Xiaojun; Sheng Guoying; Fu Jiamo; Zeng, Eddy Y.

2006-01-01

A total of 32 surface sediments collected from the Yangtze River Estuary, Hangzhou Bay and the Qiantang River were analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of ΣPBDEs (sum of 12 PBDE congeners without BDE 209) and BDE 209 varied from n.d. to 0.55 and from 0.16 to 94.6 ng/g, respectively. The spatial variability of ΣPBDEs concentrations indicated that waste discharge from the urban areas might been the main source of PBDEs in the Yangtze River Delta. BDE 209 was the predominant congener (∼90-100%) detected among the 13 congeners, consistent with the fact that technical deca-BDE mixtures are presently the dominant technical PBDE mixtures used in China. Compared to published data acquired from other locales, PBDE congeners with less than four bromines were more abundant in the present study area. The hydrodynamic conditions may likely be a significant factor in dictating the observed levels and congener distribution patterns of PBDEs. - This study discussed the possible effects of hydrodynamic conditions on the distribution of PBDEs in estuarine and marine boundary

Distribution of polycyclic aromatic hydrocarbons in thirty typical soil profiles in the Yangtze River Delta region, east China

International Nuclear Information System (INIS)

Ping, L.F.; Luo, Y.M.; Zhang, H.B.; Li, Q.B.; Wu, L.H.

2007-01-01

Polycyclic aromatic hydrocarbons (PAHs) were quantified in 30 soil profiles from the Yangtze River Delta Region, in east China. Relative concentrations of PAH compounds with different benzene rings and ratios of fluoranthene to fluoranthene plus pyrene and benz(a)anthracene to benz(a)anthracene plus chrysene were used to identify the possible sources of soil PAHs. Total concentrations of 15 PAHs in topsoils ranged from 8.6 to 3881 μg kg -1 with an average of 397 μg kg -1 . Half of the soil samples were considered to be contaminated with PAHs (>200 μg kg -1 ) and two sampling sites were heavily polluted by PAHs with concentrations >1000 μg kg -1 . Phenanthrene was found in soils below a depth of 100 cm in half of the sampling sites, but the detectable ratio of benzo(a)pyrene decreased sharply from 100% in topsoil to 0 in the 4th horizon. - The information was provided on levels, distributions, and possible sources of PAHs in the soils of Yangtze River Delta area

Suitability of river delta sediment as proppant, Missouri and Niobrara Rivers, Nebraska and South Dakota, 2015

Science.gov (United States)

Zelt, Ronald B.; Hobza, Christopher M.; Burton, Bethany L.; Schaepe, Nathaniel J.; Piatak, Nadine

2017-11-16

Sediment management is a challenge faced by reservoir managers who have several potential options, including dredging, for mitigation of storage capacity lost to sedimentation. As sediment is removed from reservoir storage, potential use of the sediment for socioeconomic or ecological benefit could potentially defray some costs of its removal. Rivers that transport a sandy sediment load will deposit the sand load along a reservoir-headwaters reach where the current of the river slackens progressively as its bed approaches and then descends below the reservoir water level. Given a rare combination of factors, a reservoir deposit of alluvial sand has potential to be suitable for use as proppant for hydraulic fracturing in unconventional oil and gas development. In 2015, the U.S. Geological Survey began a program of researching potential sources of proppant sand from reservoirs, with an initial focus on the Missouri River subbasins that receive sand loads from the Nebraska Sand Hills. This report documents the methods and results of assessments of the suitability of river delta sediment as proppant for a pilot study area in the delta headwaters of Lewis and Clark Lake, Nebraska and South Dakota. Results from surface-geophysical surveys of electrical resistivity guided borings to collect 3.7-meter long cores at 25 sites on delta sandbars using the direct-push method to recover duplicate, 3.8-centimeter-diameter cores in April 2015. In addition, the U.S. Geological Survey collected samples of upstream sand sources in the lower Niobrara River valley.At the laboratory, samples were dried, weighed, washed, dried, and weighed again. Exploratory analysis of natural sand for determining its suitability as a proppant involved application of a modified subset of the standard protocols known as American Petroleum Institute (API) Recommended Practice (RP) 19C. The RP19C methods were not intended for exploration-stage evaluation of raw materials. Results for the washed samples are

Assessing subaqueous mudslide hazard on the Mississippi River delta front, Part 2: Insights revealed through high-resolution geophysical surveying

Science.gov (United States)

Obelcz, J.; Xu, K.; Bentley, S. J.; Georgiou, I. Y.; Maloney, J. M.; Miner, M. D.; Hanegan, K.; Keller, G.

2014-12-01

The northern Gulf of Mexico, including the subaqueous Mississippi River delta front (MRDF), has been productive for oil and gas development since the early 1900s. In 1969 cyclic seafloor wave loading associated with the passage of Hurricane Camille triggered subaqueous mudflows across the MRDF, destroying several offshore oil platforms. This incident spurred geophysical and geotechnical studies of the MRDF, which found that the delta front is prone to mass failures on gentle gradients (gas production, and (3) the frequent passage of tropical cyclones. In June 2014, a geophysical pilot study was conducted 8 km southwest of Southwest Pass, the distributary that currently receives the largest fraction of Mississippi River sediment supply. The resultant dataset encompasses 216 km of subbottom Chirp seismic profiles and a 60 km2 grid of bathymetry and sidescan data. Preliminary interpretation of these data shows the survey area can be classified into four primary sedimentary facies: mudflow gullies, mudflow lobes, undisturbed prodelta, and undisturbed delta front. Subbottom profiles reveal extensive biogenic gas from 20 to about 80 m water depths on the delta front; sidescan data show a variety of bottleneck slides, mudflow gullies and mudflow noses. Previous studies have attempted to constrain the periodicity and magnitude of subaqueous mudslides on the MRDF. However, large age gaps and varied resolution between datasets result in ambiguity regarding the cause and magnitude of observed bathymetric changes. We present high-temporal resolution MRDF bathymetric variations from 2005 (post Hurricane Katrina), 2009 (relatively quiescent storm period), and 2014 (post 2011 Mississippi River flood). These data yield better magnitude and timing estimates of mass movements. This exercise represents a first step towards (1) assembling a comprehensive geologic dataset upon which future MRDF geohazard assessments can be founded, and (2) understanding the dynamics of a massive

Temporal changes of land use in Asi river delta (Hatay, Southern Turkey).

Science.gov (United States)

Korkmaz, Hüseyin; Cetin, Bayram; Kuscu, Veysel; Ege, Ismail; Bom, Ahmet; Ozsahin, Emre; Karatas, Atilla

2012-04-01

Increasing non-ecological land use necessitates more efficient using and utilization of land by man. Therefore, in recent years studies on sustainable land use have gained momentum. In this study, temporal change in land use, mainly between years 1940 and 2010, in Asi river delta on Southern Turkey was covered. To this end, in addition to literature, topographical maps and satellite images from year 1940 and after were used. Also, data were collected through field studies and interviews. Collected data were evaluated from geographical viewpoint using Geographical information system (GIS) and Remote sensing (RS) methods. Unplanned settlement in delta has reached levels high enough to threaten agricultural fields. Especially, greattendencyshown by Samandag city and the villages around it towards expanding into delta is an indicatorof this threat In additon, uncontrolled sand mining and touristic facilities on the coastline are also indicators of wrong land use. In future, direction of settlement to slopes around the delta rather than lowlands will be a much more ecological approach.

Niger Delta Development Commission and Sustainable ...

African Journals Online (AJOL)

Niger Delta Development Commission and Sustainable Development of Niger Delta Region of Nigeria: The Case of Rivers State. Goddey Wilson. Abstract. The study is on Niger Delta Development Commission and sustainable development of Niger Delta region of Nigeria, the case of Rivers State. The main objective of the ...

South Local Government Area, Delta S

African Journals Online (AJOL)

ADOWIE PERE

environs, Aniocha- South Local Government Area of Delta State, Nigeria was carried out with a view to determining the ... supply for physical industrial development to achieve maximum human .... the Schlumberger O' Neil software package.

Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

OpenAIRE

Fang, Xuekun; Shao, Min; Stohl, Andreas; Zhang, Qiang; Zheng, Junyu; Guo, Hai; Wang, Chen; Wang, Ming; Ou, Jiamin; Thompson, Rona L.; Prinn, Ronald G.

2016-01-01

Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and ...

Study on Remote Sensing Image Characteristics of Ecological Land: Case Study of Original Ecological Land in the Yellow River Delta

Science.gov (United States)

An, G. Q.

2018-04-01

Takes the Yellow River Delta as an example, this paper studies the characteristics of remote sensing imagery with dominant ecological functional land use types, compares the advantages and disadvantages of different image in interpreting ecological land use, and uses research results to analyse the changing trend of ecological land in the study area in the past 30 years. The main methods include multi-period, different sensor images and different seasonal spectral curves, vegetation index, GIS and data analysis methods. The results show that the main ecological land in the Yellow River Delta included coastal beaches, saline-alkaline lands, and water bodies. These lands have relatively distinct spectral and texture features. The spectral features along the beach show characteristics of absorption in the green band and reflection in the red band. This feature is less affected by the acquisition year, season, and sensor type. Saline-alkali land due to the influence of some saline-alkaline-tolerant plants such as alkali tent, Tamarix and other vegetation, the spectral characteristics have a certain seasonal changes, winter and spring NDVI index is less than the summer and autumn vegetation index. The spectral characteristics of a water body generally decrease rapidly with increasing wavelength, and the reflectance in the red band increases with increasing sediment concentration. In conclusion, according to the spectral characteristics and image texture features of the ecological land in the Yellow River Delta, the accuracy of image interpretation of such ecological land can be improved.

STUDY ON REMOTE SENSING IMAGE CHARACTERISTICS OF ECOLOGICAL LAND: CASE STUDY OF ORIGINAL ECOLOGICAL LAND IN THE YELLOW RIVER DELTA

Directory of Open Access Journals (Sweden)

G. Q. An

2018-04-01

Full Text Available Takes the Yellow River Delta as an example, this paper studies the characteristics of remote sensing imagery with dominant ecological functional land use types, compares the advantages and disadvantages of different image in interpreting ecological land use, and uses research results to analyse the changing trend of ecological land in the study area in the past 30 years. The main methods include multi-period, different sensor images and different seasonal spectral curves, vegetation index, GIS and data analysis methods. The results show that the main ecological land in the Yellow River Delta included coastal beaches, saline-alkaline lands, and water bodies. These lands have relatively distinct spectral and texture features. The spectral features along the beach show characteristics of absorption in the green band and reflection in the red band. This feature is less affected by the acquisition year, season, and sensor type. Saline-alkali land due to the influence of some saline-alkaline-tolerant plants such as alkali tent, Tamarix and other vegetation, the spectral characteristics have a certain seasonal changes, winter and spring NDVI index is less than the summer and autumn vegetation index. The spectral characteristics of a water body generally decrease rapidly with increasing wavelength, and the reflectance in the red band increases with increasing sediment concentration. In conclusion, according to the spectral characteristics and image texture features of the ecological land in the Yellow River Delta, the accuracy of image interpretation of such ecological land can be improved.

CMS: LiDAR Data for Mangrove Forests in the Zambezi River Delta, Mozambique, 2014

Data.gov (United States)

National Aeronautics and Space Administration — This data set provides high-resolution LiDAR point cloud data collected during surveys over mangrove forests in the Zambezi River Delta in Mozambique in May 2014....

Measuring urban agglomeration using a city-scale dasymetric population map: A study in the Pearl River Delta, China

OpenAIRE

Wei, Chunzhu; Taubenböck, Hannes; Blaschke, Thomas

2017-01-01

The rates of urbanization and increase in urban sprawl that have occurred in China over the past thirty years have been unprecedented. This article presents a new city-scale dasymetric modelling approach that incorporates historical census data for 28 cities in the Pearl River Delta area of southern China. It combines Landsat imagery (from 2000, 2005, 2010, and 2015) with a ‘limiting variable’ estimation al-gorithm to generate a gridded estimate of population density. These gridded population...

Changing Course - the Baird Team Solution: a Delta for All

Science.gov (United States)

Nairn, R. B.

2016-02-01

The Changing Course Design competition was initiated to evaluate options for re-positioning the mouth of the Mississippi River and modifying the management of the Lower Mississippi River to support the 2017 Master Plan for the Louisiana coast. This paper will present the findings of one of the selected competitors: the Baird Team and their "Delta for All" approach. A key to success in the future management of the lower Mississippi River is the development of an integrated, holistic approach to management that recognizes the need to harness the full land/wetland building and restorative potential of the river at the same time as improving flood protection and navigation. Fundamentally the Baird solution recognized the underlying geomorphic challenges of the Delta: it receives three to four times less sediment from the Mississippi River than it did historically and sea level is rising two to three times faster than it did historically and is predicted to rise much faster in the future. The result will be a smaller delta in the future. Our approach seeks to harness as close to 100% of the land building potential of the river to make the smaller future delta as large as possible. This compares to the 2012 State Master Plan which would harness approximately 50% of the land-building potential. Our approach also recognizes that the further inland new distributary mouths and associated sub-deltas are located, the greater the delta building potential. Our approach builds with the river by creating and managing new river distributaries that are opened and closed every 50 years or so to build new sub-deltas within a defined sustainable delta footprint. By placing the last outlet somewhere in the vicinity of English Turn the lower Mississippi River would become a tidal channel. These two simple concepts of harnessing 100% of the river and placing the last outlet near English Turn result in immediate and significant benefits for flood protection and navigation. Through the

Environmental flows and its evaluation of restoration effect based on LEDESS model in Yellow River Delta wetlands

NARCIS (Netherlands)

Wang, X.G.; Lian, Y.; Huang, C.; Wang, X.J.; Wang, R.L.; Shan, K.; Pedroli, B.; Eupen, van M.; Elmahdi, A.; Ali, M.

2012-01-01

Due to freshwater supplement scarcity and heavy human activities, the fresh water wetland ecosystem in Yellow River Delta is facing disintegrated deterioration, and it is seriously affecting the health of the Yellow River ecosystem. This paper identifies the restoration objectives of wetland aiming

Spatial and temporal variation of nutrients in groundwater and associated processes in the coastal zone of the Pearl River Delta, China

Science.gov (United States)

Chen, J.

2017-12-01

Rapid urbanization has occurred in the Pearl River Delta since 1980s, resulting in tremendous accumulation of population and material in an area of around 1.1x104 km2. Massive nutrients were released to the coastal zone either via the Pearl River or the aquifer, and effects of these nutrients on ecosystem and drinking water supply are a big public concern. Field campaigns to collect groundwater samples were implemented in rainy (April- September) and dry seasons (October - March) during the period of 2005-2016, and samples were analyzed for major ions, nutrients, multiple isotopes, N2O and microbiological DNA. Seasonal and spatial pattern of nutrients from the recharge to the discharge zone in two case study areas were identified and compared regarding relevant N transformation processes. Main sources of nutrients in groundwater and major mechanisms, e.g. denitrification, nitrification and etc., involved in these processes were raised by integrating microbiological, isotopic and geochemical evidences. Driven forces of the change in nutrients in the past 10 years were investigated based on statistical data, and total nutrient load in groundwater in the delta was estimated.

Hydraulic survey and scour assessment of Bridge 524, Tanana River at Big Delta, Alaska

Science.gov (United States)

Heinrichs, Thomas A.; Langley, Dustin E.; Burrows, Robert L.; Conaway, Jeffrey S.

2007-01-01

Bathymetric and hydraulic data were collected August 26–28, 1996, on the Tanana River at Big Delta, Alaska, at the Richardson Highway bridge and Trans-Alaska Pipeline crossing. Erosion along the right (north) bank of the river between the bridge and the pipeline crossing prompted the data collection. A water-surface profile hydraulic model for the 100- and 500-year recurrence-interval floods was developed using surveyed information. The Delta River enters the Tanana immediately downstream of the highway bridge, causing backwater that extends upstream of the bridge. Four scenarios were considered to simulate the influence of the backwater on flow through the bridge. Contraction and pier scour were computed from model results. Computed values of pier scour were large, but the scour during a flood may actually be less because of mitigating factors. No bank erosion was observed at the time of the survey, a low-flow period. Erosion is likely to occur during intermediate or high flows, but the actual erosion processes are unknown at this time.

Shoreline Changes on the Wave-Influenced Senegal River Delta, West Africa: The Roles of Natural Processes and Human Interventions

OpenAIRE

Sadio , Mamadou; Anthony , Edward ,; Diaw , Amadou ,; DUSSOUILLEZ , Philippe; FLEURY , Jules; Kane , Alioune; Almar , Rafael; Kestenare , Élodie

2017-01-01

International audience; The Senegal River delta in West Africa, one of the finest examples of " wave-influenced " deltas, is bounded by a spit periodically breached by waves, each breach then acting as a shifting mouth of the Senegal River. Using European Re-Analysis (ERA) hindcast wave data from 1984 to 2015 generated by the Wave Atmospheric Model (WAM) of the European Centre for Medium-Range Weather Forecasts (ECMWF), we calculated longshore sediment transport rates along the spit. We also ...

Changes in sediment and organic carbon accumulation in a highly-disturbed ecosystem: The Sacramento-San Joaquin River Delta (California, USA)

International Nuclear Information System (INIS)

Canuel, Elizabeth A.; Lerberg, Elizabeth J.; Dickhut, Rebecca M.; Kuehl, Steven A.; Bianchi, Thomas S.; Wakeham, Stuart G.

2009-01-01

We used the Sacramento-San Joaquin River Delta CA (Delta, hereafter) as a model system for understanding how human activities influence the delivery of sediment and total organic carbon (TOC) over the past 50-60 years. Sediment cores were collected from sites within the Delta representing the Sacramento River (SAC), the San Joaquin River (SJR), and Franks Tract (FT), a flooded agricultural tract. A variety of anthropogenic tracers including 137 Cs, total DDE (ΣDDE) and brominated diphenyl ether (BDE) congeners were used to quantify sediment accumulation rates. This information was combined with total organic carbon (TOC) profiles to quantify rates of TOC accumulation. Across the three sites, sediment and TOC accumulation rates were four to eight-fold higher prior to 1972. Changes in sediment and TOC accumulation were coincident with completion of several large reservoirs and increased agriculture and urbanization in the Delta watershed. Radiocarbon content of TOC indicated that much of the carbon delivered to the Delta is 'pre-aged' reflecting processing in the Delta watershed or during transport to the sites rather than an input of predominantly contemporary carbon (e.g., 900-1400 years BP in surface sediments and 2200 yrs BP and 3610 yrs BP at the base of the SJR and FT cores, respectively). Together, these data suggest that human activities have altered the amount and age of TOC accumulating in the Delta since the 1940s.

Large-Scale Land Concessions, Migration, and Land Use: The Paradox of Industrial Estates in the Red River Delta of Vietnam and Rubber Plantations of Northeast Cambodia

Directory of Open Access Journals (Sweden)

Jefferson Fox

2018-06-01

Full Text Available This study investigated the implications of large-scale land concessions in the Red River Delta, Vietnam, and Northeast Cambodia with regard to urban and agricultural frontiers, agrarian transitions, migration, and places from which the migrant workers originated. Field interviews conducted near large-scale land concessions for industrial estates in the Red River Delta and rubber plantations in Northeast Cambodia suggest that these radically different concessions are paradoxically leading to similar reconfigurations of livelihoods, labor patterns, and landscapes despite basic differences in these forms of land use. Both the Red River Delta and Northeast Cambodia are frontier environments undergoing extensive agrarian change with migration to work in the large-scale land concessions leading to a shortage of farm labor that anticipates changes in farming practices and farm livelihoods. These population movements will lead to further land-use changes as governments invest in the infrastructure and services needed to support increased population density in the receiving areas. In addition, labor migrations associated with these investments affect land-use practices both at the site of the concession and the places from where the migrants originate.

Depositional System Transition from Braided River to Tide Dominated Delta-A Case Study of the MPE3 Block in the Eastern Venezuelan Basin

Science.gov (United States)

Huang, Wensong; Chen, Heping; Xu, Fang; Meng, Zheng; Li, Yonghao

2017-04-01

The Eastern Venezuelan basin is a world-class petroliferous area, with the sedimentary environment controlled by the interaction between the Caribbean plate and the American plate. Based on interpretation of 3D seismic data, description of electrical well-logging facies and analysis of the sedimentary phenomena on the cores, we distinguished different types of sedimentary associations and clarified the evolution progress of the sedimentary system in the study area, the MPE3 Block. We put forward that depositional system in the study area changed from braided river in the early Miocene to tide dominated delta in the middle Miocene. Paralleled with sedimentary progress, the depositional hydrodynamic mechanism altered from the inertia dominated setting into the buoyancy dominated setting. During the middle Miocene, the tidal effect obviously reworked and formed tidal bars and tidal channels, both severing as the sedimentary framework. From the perspective of the tectonic movement, the study area varied from the foreland stage during the early Miocene to the compression and inverse stage during the middle Miocene. At the same time, the study area located in the southern part of the foreland basin began to extend and marine transgression occurred due to the tectonic extensional movement. We pointed out that critical factors influencing the transition from braided river to tidal dominate delta include palaeogeomorphology, sea level fluctuation, feeder system and the distance to catchment area.

The Atchafalaya River Delta. Report 7. Analytical Analysis of the Development of the Atchafalaya River Delta.

Science.gov (United States)

1985-09-01

responsible for the abrupt increases in subaerial delta growth. 64. Through using satellite imagery, color infrared photog- raphy, and digital current...w RO CF = HO/A/BO/(2.-D) w (HH wo (2.-D) - 1.) + O.5/AA X2 = BO m 2.m AA a HHow(D-1.) o CF AREA = (2.wAAwB~ ww2 ) im (CKI*(1. + AmBO/HOwRO) ww2 &+ CK2 a

Relevance of the Paraná River hydrology on the fluvial water quality of the Delta Biosphere Reserve.

Science.gov (United States)

Puig, Alba; Olguín Salinas, Héctor F; Borús, Juan A

2016-06-01

The increasing frequency of extreme events in large rivers may affect not only their flow, but also their water quality. In the present study, spatial and temporal changes in fluvial physico-chemical variables were analyzed in a mega-river delta during two extreme hydrological years (La Niña-El Niño) and related to potential explanatory factors. Basic water variables were evaluated in situ at 13 points (distant 2-35 km from each other) in watercourses of the Delta Biosphere Reserve (890 km(2)) in the Lower Paraná River (Argentina) in nine surveys (October 2008-July 2010) without meteorological tides. Samples for laboratory analyses were collected from each main river. Multivariate tests by permutations were applied. The period studied was influenced by a drought, within a long period dominated by low flows combined with dry weather and wildfires, and a large (10 years of recurrence) and prolonged (7 months) flood. The hydrological phase, followed by the season and the hydrological year (according to the ENSO event) were the principal explanatory factors of the main water quality changes, whereas the drainage sub-basin and the fluvial environment (river or stream) were secondary explanatory factors. During the drought period, conductivity, turbidity, and associated variables (e.g., major ions, silicon, and iron concentrations) were maximal, whereas real color was minimal. In the overbanking flood phase, pH and dissolved oxygen concentration were minimal, whereas real color was maximal. Dissolved oxygen saturation was also low in the receding flood phase and total major ion load doubled after the arrival of the overbanking stage. The water quality of these watercourses may be affected by the combination of several influences, such as the Paraná River flow, the pulses with sediments and solutes from the Bermejo River, the export of the Delta floodplain properties mainly by the flood, the season, and the saline tributaries to the Lower Paraná River. The high

A survey of sport fish use on the Copper River Delta, Alaska.

Science.gov (United States)

Dirk W. Lang

2010-01-01

Aerial counts, in-person interviews, and mail-in questionnaires were used to survey sport fish use during the coho salmon (Oncorhynchus kisutch Walbaum) season on the Copper River Delta, Alaska from 2002 through 2006. Angler counts provided an index of use on individual streams and were used to develop a spatial database exhibiting patterns of use...

Landscape controls and vertical variability of soil organic carbon storage in permafrost-affected soils of the Lena River Delta

DEFF Research Database (Denmark)

Siewert, Matthias Benjamin; Hugelius, Gustaf; Heim, Birgit

2016-01-01

To project the future development of the soil organic carbon (SOC) storage in permafrost environments, the spatial and vertical distribution of key soil properties and their landscape controls needs to be understood. This article reports findings from the Arctic Lena River Delta where we sampled 50...... in the permafrost. The major geomorphological units of a subregion of the Lena River Delta were mapped with a land form classification using a data-fusion approach of optical satellite imagery and digital elevation data to upscale SOC storage. Landscape mean SOC storage is estimated to 19.2 ± 2.0 kg C m− 2. Our...... results show that the geomorphological setting explains more soil variability than soil taxonomy classes or vegetation cover. The soils from the oldest, Pleistocene aged, unit of the delta store the highest amount of SOC per m2 followed by the Holocene river terrace. The Pleistocene terrace affected...

Impacts of the dam-orientated water-sediment regulation scheme on the lower reaches and delta of the Yellow River (Huanghe): A review

Science.gov (United States)

Wang, Houjie; Wu, Xiao; Bi, Naishuang; Li, Song; Yuan, Ping; Wang, Aimei; Syvitski, James P. M.; Saito, Yoshiki; Yang, Zuosheng; Liu, Sumei; Nittrouer, Jeffrey

2017-10-01

The water-sediment regulation scheme (WSRS), beginning in 2002, is an unprecedented engineering effort to manage the Yellow River with the aims to mitigate the siltation both in the lower river channel and within the Xiaolangdi Reservoir utilizing the dam-regulated flood water. Ten years after its initial implementation, multi-disciplinary indicators allow us to offer a comprehensive review of this human intervention on a river-coastal system. The WSRS generally achieved its objective, including bed erosion in the lower reaches with increasing capacity for flood discharge and the mitigation of reservoir siltation. However, the WSRS presented unexpected disturbances on the delta and coastal system. Increasing grain size of suspended sediment and decreasing suspended sediment concentration at the river mouth resulted in a regime shift of sediment transport patterns that enhanced the disequilibrium of the delta. The WSRS induced an impulse delivery of nutrients and pollutants within a short period ( 20 days), which together with the altered hydrological cycle, impacted the estuarine and coastal ecosystem. We expect that the sediment yield from the loess region in the future will decrease due to soil-conservation practices, and the lower channel erosion will also decrease as the riverbed armors with coarser sediment. These, in combination with uncertain water discharge concomitant with climate change, increasing water demands and delta subsidence, will put the delta and coastal ocean at high environmental risks. In the context of global change, this work depicts a scenario of human impacts in the river basin that were transferred along the hydrological pathway to the coastal system and remotely transformed the different components of coastal environment. The synthesis review of the WSRS indicates that an integrated management of the river-coast continuum is crucially important for the sustainability of the entire river-delta system. The lessons learned from the WSRS in

Effects of middle-term land reclamation on nickel soil-water interaction: a case study from reclaimed salt marshes of Po River Delta, Italy.

Science.gov (United States)

Di Giuseppe, Dario; Melchiorre, Massimiliano; Faccini, Barbara; Ferretti, Giacomo; Coltorti, Massimo

2017-09-26

Reclaimed salt marshes are fragile environments where water salinization and accumulation of heavy metals can easily occur. This type of environment constitutes a large part of the Po River Delta (Italy), where intensive agricultural activities take place. Given the higher Ni background of Po River Delta soils and its water-soluble nature, the main aim of this contribution is to understand if reclamation can influence the Ni behavior over time. In this study, we investigated the geochemical features of 40 soils sampled in two different localities from the Po River Delta with different reclamation ages. Samples of salt marsh soils reclaimed in 1964 were taken from Valle del Mezzano while soils reclaimed in 1872 were taken nearby Codigoro town. Batch solubility tests and consecutive determination of Ni in pore-water were compared to bulk physicochemical compositions of soils. Bulk Ni content of the studied soils is naturally high, since these soils originated from Po River sediments derived from the erosion of ultramafic rocks. Moreover, it seems that Ni concentration increases during soil evolution, being probably related to the degradation of serpentine. Instead, the water-soluble Ni measured in the leaching tests is greater in soils recently reclaimed compared to the oldest soils. Soil properties of two soil profiles from a reclaimed wetland area were examined to determine soil evolution over one century. Following reclamation, pedogenic processes of the superficial horizons resulted in organic matter mineralization, pH buffer, and a decrease of Ni water solubility from recently to evolved reclaimed soil.

Geochemical Dataset of the Rhone River Delta (Lake Geneva) Sediments - Disentangling Human Impacts from Climate Change

Science.gov (United States)

Silva, T. A.; Girardclos, S.; Loizeau, J. L.

2016-12-01

Lake sediment records are often the most complete continental archives. In the last 200 years, in addition to climatic variability, humans have strongly impacted lake watersheds around the world. During the 20th century the Rhone River and its watershed upstream Lake Geneva (Switzerland/France) have been subject to river channelization, dam construction, water flow regulation, water and sediment abstraction as well as various land use changes. Under the scope of the SEDFATE project (Swiss National Science Foundation nº147689) we address human and climatic impact on the sediment transfer from the Rhone River watershed to Lake Geneva. Nineteen short sediment cores were collected in the Rhone River delta area in May 2014. Cores have been scanned with MSCL and XRF, sub-sampled every 1cm and 8 cores were dated by radiometric methods (137Cs and 210Pb). Photographs taken right after core opening were used for lithological description and in addition to MSCL data were used to correlate cores. Core dating shows that mass accumulation rates decreased in the 1964-1986 interval and then increased again in the interval between 1986-2014. XRF elements and ratios, known to indicate detrital sources (Al, Al/Si, Fe, K, Mn, Rb, Si, Ti, Ti/Ca), show that clastic input diminished from 1964 to 1986 and re-increased to the present. Other elemental (Zr/Rb, Zr/K, Si/Ti) and geophysical data (magnetic susceptibility) combined with lithology identify density flow deposits vs hemipelagic sedimentation. Changes in frequency of these event deposits indicate changes in the sedimentation patterns in the Rhone River sublacustrine delta during the last century. From these results we hypothesize that a significant sediment amount was abstracted from the system after the major dam constructions in the 1950's and that, since the 1990's, a contrary signal is due to increased sediment loads that follows glacial melting due to global warming.

Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

Directory of Open Access Journals (Sweden)

G. L. Gilbert

2017-05-01

Full Text Available The Zackenberg River delta is located in northeast Greenland (74°30′ N, 20°30′ E at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2 formed during relative sea-level (RSL fall. We investigated the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL dating. We identify four facies associations in sections (4 to 22 m in height exposed along the modern Zackenberg River and coast. Facies associations relate to (I overriding glaciers, (II retreating glaciers and quiescent glaciomarine conditions, (III delta progradation in a fjord valley, and (IV fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together with low overall ground-ice content, indicates that permafrost is predominately epigenetic in these deposits. Fourteen OSL ages constrain the deposition of the cored deposits to between approximately 13 and 11 ka, immediately following deglaciation. The timing of permafrost aggradation was closely related to delta progradation and began following the subaerial exposure of the delta plain (ca. 11 ka. Our results reveal information concerning the interplay between deglaciation, RSL change, sedimentation, permafrost aggradation, and the timing of these events. These findings have implications for the timing and mode of permafrost aggradation in other fjord valleys in northeast Greenland.

Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

Science.gov (United States)

Gilbert, Graham L.; Cable, Stefanie; Thiel, Christine; Christiansen, Hanne H.; Elberling, Bo

2017-05-01

The Zackenberg River delta is located in northeast Greenland (74°30' N, 20°30' E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2) formed during relative sea-level (RSL) fall. We investigated the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL) dating. We identify four facies associations in sections (4 to 22 m in height) exposed along the modern Zackenberg River and coast. Facies associations relate to (I) overriding glaciers, (II) retreating glaciers and quiescent glaciomarine conditions, (III) delta progradation in a fjord valley, and (IV) fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together with low overall ground-ice content, indicates that permafrost is predominately epigenetic in these deposits. Fourteen OSL ages constrain the deposition of the cored deposits to between approximately 13 and 11 ka, immediately following deglaciation. The timing of permafrost aggradation was closely related to delta progradation and began following the subaerial exposure of the delta plain (ca. 11 ka). Our results reveal information concerning the interplay between deglaciation, RSL change, sedimentation, permafrost aggradation, and the timing of these events. These findings have implications for the timing and mode of permafrost aggradation in other fjord valleys in northeast Greenland.

Polycyclic aromatic hydrocarbons in upstream riverine runoff of the Pearl River Delta, China: An assessment of regional input sources

International Nuclear Information System (INIS)

Zhang Kai; Liang Bo; Wang Jizhong; Guan Yufeng; Zeng, Eddy Y.

2012-01-01

Water samples collected from upstream tributaries of the Pearl River Delta (PRD) and from locations within the PRD (South China) were analyzed for 27 polycyclic aromatic hydrocarbons (PAHs). Average concentrations (aqueous plus particulate) of total 27 PAHs (Σ 27 PAH), 16 priority PAHs designated by the United States Environmental Protection Agency (USEPA) except naphthalene (Σ 15 PAH), and the seven carcinogenic PAHs (Σ 7 PAH) classified by the USEPA were 260 ± 410, 130 ± 310, and 15 ± 12 ng/L, respectively. Riverine PAHs were predominantly generated from coal and vegetation combustion, coke production, vehicle exhausts, and petroleum residues, accounting for 28%, 25%, 22% and 21%, respectively, on average. Upstream riverine fluxes of Σ 27 PAH and Σ 15 PAH amounted to 38.9 and 12.9 tons/year, respectively. The net contributions of Σ 27 PAH and Σ 15 PAH from sources within the PRD were estimated at 21.4 and 21.0 tons/year, respectively. - Highlights: ► Upstream PAH levels were lower than downstream PAHs and pose low ecological risk. ► Riverine PAHs are predominantly pyrogenic. ► Parent PAHs in Pearl River are mainly derived from within the PRD. ► The 15 priority PAHs were mainly generated within the Pearl River Delta. - The 15 priority PAHs are mainly generated within the PRD while the other 12 PAHs from upstream areas.

Late quaternary evolution of the Orinoco Delta, Venezuela

Science.gov (United States)

Warne, A.G.; Guevara, E.H.; Aslan, A.

2002-01-01

The modern Orinoco Delta is the latest of a series of stacked deltas that have infilled the Eastern Venezuelan Basin (EVB) since the Oligocene. During the late Pleistocene sea-level lowstand (20,000 to 16,000 yrs BP), bedrock control points at the position of the present delta apex prevented the river channel from incising as deeply as many other major river systems. Shallow seismic data indicate that the late Pleistocene Orinoco incised into the present continental shelf, where it formed a braided-river complex that transported sediment to a series of shelf-edge deltas. As sea level rose from 16,000 to 9,500 yrs BP, the Orinoco shoreline shifted rapidly landward, causing shallow-marine waves and currents to form a widespread transgressive sand unit. Decelerating sea-level rise and a warmer, wetter climate during the early Holocene (9,500 to 6,000 yrs BP) induced delta development within the relatively quiet-water environment of the EVB embayment. Sea level approached its present stand in the middle Holocene (6,000 to 3,000 yrs BP), and the Orinoco coast prograded, broadening the delta plain and infilling the EVB embayment. Significant quantities of Amazon sediment began to be transported to the Orinoco coast by littoral currents. Continued progradation in the late Holocene caused the constriction at Boca de Serpientes to alter nearshore and shelf hydrodynamics and subdivide the submarine delta into two distinct areas: the Atlantic shelf and the Gulf of Paria. The increased influence of littoral currents along the coast promoted mudcape development. Because most of the water and sediment were transported across the delta plain through the Rio Grande distributary in the southern delta, much of the central and northwestern delta plain became sediment starved, promoting widespread accumulation of peat deposits. Human impacts on the delta are mostly associated with the Volca??n Dam on Can??o Manamo. However, human activities have had relatively little effect on the

Rapid Urbanization and Implications for Flood Risk Management in Hinterland of the Pearl River Delta, China: The Foshan Study

Directory of Open Access Journals (Sweden)

Xiang-rong Wang

2008-03-01

Full Text Available The purpose of this paper is to examine the linkage between rapid urbanization and flood risk in the hinterlands of the Pearl River Delta, P.R. China. Foshan, a typical hinterland city in the Pearl River Delta region, was selected as a case study. Land use and cover change in Foshan during 1988-2003 was analyzed using remote sensing and geographic information system (GIS techniques. Furthermore, analysis on historical hydrological data during 1962-2005 was performed. Results show that rapid urbanization has resulted in losses of farmland, forest and shrub since 1988. In addition, in order to compensate or offset the loss of farmland due to rapid urban expansion, more than 30 % of the forest and 20 % of the shrub areas were transformed into farmlands. Inevitably, both the urban and agricultural lands increased the pressure on the drainage systems. Furthermore, over the past decades human activities such as dredging up the floodways, excavating sand and building water facilities in the rivers, significantly changed the hydrological conditions, and therefore impaired the rivers’ capacity to buffer floods. Lessons from the Foshan case implied that, in addition to natural processes, human activities driven by socio-economic factors should be considered responsible for the recently increasing level of flood risks. Both economically and environmentally, it is irrational and impractical to encourage encroachment of lands vulnerable to floods. It is also realistic and urgent to effectively prevent and control the adverse ecological consequences of urbanization and economic activities for building their wealth and prominence.

Rapid Urbanization and Implications for Flood Risk Management in Hinterland of the Pearl River Delta, China: The Foshan Study.

Science.gov (United States)

Zhang, Hao; Ma, Wei-Chun; Wang, Xiang-Rong

2008-03-28

The purpose of this paper is to examine the linkage between rapid urbanization and flood risk in the hinterlands of the Pearl River Delta, P.R. China. Foshan, a typical hinterland city in the Pearl River Delta region, was selected as a case study. Land use and cover change in Foshan during 1988-2003 was analyzed using remote sensing and geographic information system (GIS) techniques. Furthermore, analysis on historical hydrological data during 1962-2005 was performed. Results show that rapid urbanization has resulted in losses of farmland, forest and shrub since 1988. In addition, in order to compensate or offset the loss of farmland due to rapid urban expansion, more than 30 % of the forest and 20 % of the shrub areas were transformed into farmlands. Inevitably, both the urban and agricultural lands increased the pressure on the drainage systems. Furthermore, over the past decades human activities such as dredging up the floodways, excavating sand and building water facilities in the rivers, significantly changed the hydrological conditions, and therefore impaired the rivers' capacity to buffer floods. Lessons from the Foshan case implied that, in addition to natural processes, human activities driven by socio-economic factors should be considered responsible for the recently increasing level of flood risks. Both economically and environmentally, it is irrational and impractical to encourage encroachment of lands vulnerable to floods. It is also realistic and urgent to effectively prevent and control the adverse ecological consequences of urbanization and economic activities for building their wealth and prominence.

Groundwater Flow Model of Göksu Delta Coastal Aquifer System

Science.gov (United States)

Erdem Dokuz, Uǧur; Çelik, Mehmet; Arslan, Şebnem; Engin, Hilal

2016-04-01

Like many other coastal areas, Göksu Delta (Mersin-Silifke, Southern Turkey) is a preferred place for human settlement especially due to its productive farmlands and water resources. The water dependent ecosystem in Göksu delta hosts about 332 different plant species and 328 different bird species besides serving for human use. Göksu Delta has been declared as Special Environmental Protection Zone, Wildlife Protection Area, and RAMSAR Convention for Wetlands of International Importance area. Unfortunately, rising population, agricultural and industrial activities cause degradation of water resources both by means of quality and quantity. This problem also exists for other wetlands around the world. It is necessary to prepare water management plans by taking global warming issues into account to protect water resources for next generations. To achieve this, the most efficient tool is to come up with groundwater management strategies by constructing groundwater flow models. By this aim, groundwater modeling studies were carried out for Göksu Delta coastal aquifer system. As a first and most important step in all groundwater modeling studies, geological and hydrogeological settings of the study area have been investigated. Göksu Delta, like many other deltaic environments, has a complex structure because it was formed with the sediments transported by Göksu River throughout the Quaternary period and shaped throughout the transgression-regression periods. Both due to this complex structure and the lack of observation wells penetrating deep enough to give an idea of the total thickness of the delta, it was impossible to reveal out the hydrogeological setting in a correct manner. Therefore, six wells were drilled to construct the conceptual hydrogeological model of Göksu Delta coastal aquifer system. On the basis of drilling studies and slug tests that were conducted along Göksu Delta, hydrostratigraphic units of the delta system have been obtained. According to

Extraction and Analysis of Impervious Surfaces Based on a Spectral Un-Mixing Method Using Pearl River Delta of China Landsat TM/ETM+ Imagery from 1998 to 2008

Directory of Open Access Journals (Sweden)

Renrong Chen

2012-02-01

Full Text Available Impervious surface area (ISA is considered as an indicator of environment change and is regarded as an important input parameter for hydrological cycle simulation, water management and area pollution assessment. The Pearl River Delta (PRD, the 3rd most important economic district of China, is chosen in this paper to extract the ISA information based on Landsat images of 1998, 2003 and 2008 by using a linear spectral un-mixing method and to monitor impervious surface change by analyzing the multi-temporal Landsat-derived fractional impervious surface. Results of this study were as follows: (1 the area of ISA in the PRD increased 79.09% from 1998 to 2003 and 26.88% from 2003 to 2008 separately; (2 the spatial distribution of ISA was described according to the 1998/2003 percentage respectively. Most of middle and high percentage ISA was located in northwestern and southeastern of the whole delta, and middle percentage ISA was mainly located in the city interior, high percentage ISA was mainly located in the suburban around the city accordingly; (3 the expanding direction and trend of high percentage ISA was discussed in order to understand the change of urban in this delta; High percentage ISA moved from inner city to edge of urban area during 1998–2003 and moved to the suburban area that far from the urban area mixed with jumpily and gradually during 2003–2008. According to the discussion of high percentage ISA spatial expanded direction, it could be found out that high percentage ISA moved outward from the centre line of Pearl River of the whole delta while a high ISA percentage in both shores of the Pearl River Estuary moved toward the Pearl River; (4 combining the change of ISA with social conditions, the driving relationship was analyzed in detail. It was evident that ISA percentage change had a deep relationship with the economic development of this region in the past ten years. Contemporaneous major sport events (16th Asia Games of

Impact on water quality of land uses along Thamalakane-Boteti River: An outlet of the Okavango Delta

Science.gov (United States)

Masamba, Wellington R. L.; Mazvimavi, Dominic

Botswana is a semiarid country and yet has one of the world’s famous wetlands: the Okavango Delta. The Thamalakane-Boteti River is one of the Delta’s outlets. The water quality of the Thamalakane-Boteti River was determined and related to its utilisation. The major land uses along the Thamalakane River within Maun are residential areas, lodges, hotels, and grazing by cattle and donkeys. The water is used as a source of water for livestock, wildlife in a game park, horticulture and domestic applications including drinking. The river is also used for fishing. To check whether these activities negatively impact on the water quality, pH, electrical conductivity, dissolved oxygen, temperature, total dissolved nitrogen and phosphorus, Faecal coliforms and Faecal streptococci and selected metals were determined from July 2005 to January 2006. The pH was near neutral except for the southern most sampling sites where values of up to 10.3 were determined. Dissolved oxygen varied from 2 mg/l to 8 mg/l. Sodium (range 0.6-3.2 mg/l), K (0.3-3.6 mg/l), Fe (1.6-6.9 mg/l) conductivity (56-430 μS/cm) and Mg (0.2-6.7 mg/l) increased with increased distance from the Delta, whereas lead showed a slight decline. Total dissolved phosphorus was low (up to 0.02 mg/l) whereas total dissolved nitrogen was in the range 0.08-1.5 mg/l. Faecal coliform (range 0-48 CFU/100 ml) and Faecal streptococci (40-260 CFU/100 ml) were low for open waters with multiple uses. The results indicate that there is possibility of pollution with organic matter and nitrogen. It is recommended that more monitoring of water quality needs to be done and the sources of pollution identified.

Deforestation and sedimentation in Uraba Gulf mangroves; a synthesis of the impacts on macrobenthos and fishes in the Turbo River Delta

International Nuclear Information System (INIS)

Blanco Libreros, Juan Felipe; Taborda Marin, Alexander; Amortegui Torres, Viviana; Arroyave Rincon, Andrea; Sandoval, Alejandro; Estrada, Edgar Andres; Leal Florez, Jenny; Vasquez Arango, Jairo Guillermo; Vivas Narvaez, Alberto

2013-01-01

This synthesis relates deforestation and land use change in coastal plain of the Turbo River watershed and impacts upon estuarine fauna in its delta. This watershed is shown within the context of hidroclimatological (rainfall and discharge) variability across the eastern margin of Uraba Gulf. Coastal-plain forest conversion rate to crops were quantified, as a possible explanation of increased sediment transport to the river and the near shore. Despite of the expansion of the delta, mangrove area was reduced as a consequence of conversion to crops and pastures. The dominant mangrove snail Neritina virginea was reduced in density in anthropogenic forest gaps and edges, as well as in pastures, due to altered microhabitats, and can be therefore used as a bio-indicator. The high sedimentation rates seem to be responsible for the faunistic poverty of the benthos, but do not seem responsible of deleterious effects on the dominant species. The diversity and abundance of fishes was greatly altered by high sedimentation near the river mouth. Finally, social features of the human communities were related to landscape changes. Herewith, we reported on the current ecosystem status, as the baseline for proposing management and conservation guidelines in order to prevent and restore impacts on mangroves and the coastal zone in this region.

Risks of Coastal Storm Surge and the Effect of Sea Level Rise in the Red River Delta, Vietnam

OpenAIRE

Neumann, James; Ludwig, Lindsay; Verly, Caroleen; Emanuel, Kerry Andrew; Ravela, Srinivas

2015-01-01

This paper considers the impact of sea level rise and storm surge on the Red River delta region of Vietnam an area already known to be highly vulnerable to coastal risks. By combining a range of sea level rise scenarios for 2050 with the simulated storm surge level for the 100-year storm surge, we analyze permanently inundated lands and temporary flood zones. As is well-established in the literature, sea level rise will increase the risk of storms by raising the base sea level from which surg...

Response of benthic foraminifera to 4.2 ka cooling event in the Nakdong River delta, southeast Korea

Science.gov (United States)

Takata, H.; Khim, B. K.; Cheong, D.; Shin, S.

2016-02-01

Here we report the change of benthic foraminifera in response to 4.2 ka cooling event in the Nakdong River delta (southeastern Korea). It has been known that this cooling event caused climatic deteriorations in the world, which is closely related to the decline/development of the civilizations (e.g., Kawahata et al., 2009). This event was also correlated to one of Bond Events in the North Atlantic. Because coastal sediment depositions have been influenced by both oceanographic and terrestrial climatic changes, the study may provide us clue to understand the possible teleconnection of the cooling event between the North Atlantic and the East Asian margin. We investigated fossil benthic foraminiferal faunas and planktonic/total foraminiferal ratio (P/T ratio) at two borehole cores, ND-01 and ND-02 (landward and seaward sites, respectively). Common constituents are taxa from bay to shelf environments in the East Asian margin. Biotic response of benthic foraminifera partly changed after 4.2 ka showing that Haynesina sp. A (opportunistic species?) decreased significantly at core ND-01. In addition, P/T ratio at both core sites showed temporal decline at 4.2 ka. This suggests the decreasing influence of the seawater relative to the coastal water. Holocene fluctuations of the Tsushima Warm Current, a branch of Kuroshio, flowing off the Nakdong River delta, have been documented. The decline pattern of P/T ratio in this area is similar to that of total sulfur content in Lake Tougou-ike, southwestern Japan at 4 ka which was interpreted as the influence of the small sea-level falling (Kato et al., 2003). According to the similar stratigraphic variation patterns between our and their studies, our finding suggests that this event was not regional but related to the fluctuations of the Tsushima Warm Current. Thus, biotic response of benthic foraminifera in the Nakdong River delta recorded 4.2 ka cooling event related to temporal weakening of the Tsushima Warm Current.

Sandy River Delta Habitat Restoration : Annual Report, January 2008 - March 2009.

Energy Technology Data Exchange (ETDEWEB)

Dobson, Robin [USDA Forest Service, Columbia River Gorge National Scenic Area

2009-09-11

During the period 2008-2009, there were 2 contracts with BPA. One (38539) was dealing with the restoration work for 2007 and the other (26198) was an extension on the 2006 contract including the NEPA for Dam removal on the old channel of the Sandy River. For contract 38539, the Sandy River Delta Habitat Restoration project continued its focus on riparian hardwood reforestation with less emphasis on wetlands restoration. Emphasis was placed on Sundial Island again due to the potential removal of the dike and the loss of access in the near future. AshCreek Forest Management was able to leverage additional funding from grants to help finance the restoration effort; this required a mid year revision of work funded by BPA. The revised work not only continued the maintenance of restored hardwood forests, but was aimed to commence the restoration of the Columbia River Banks, an area all along the Columbia River. This would be the final restoration for Sundial Island. The grant funding would help achieve this. Thus by 2011, all major work will have been completed on Sundial Island and the need for access with vehicles would no longer be required. The restored forests continued to show excellent growth and development towards true riparian gallery forests. Final inter-planting was commenced, and will continue through 2010 before the area is considered fully restored. No new wetland work was completed. The wetlands were filled by pumping in early summer to augment the water levels but due to better rainfall, no new fuel was required to augment existing. Monitoring results continued to show very good growth of the trees and the restoration at large was performing beyond expectations. Weed problems continue to be the most difficult issue. The $100,000 from BPA planned for forest restoration in 2008, was augmented by $25,000 from USFS, $120,000 from OR150 grant, $18,000 from LCREP, and the COE continued to add $250,000 for their portion. Summary of the use of these funds are

The Colorado river delta (Mexico: ecological importance and management = O delta do rio Colorado (Mexico: importância ecológica e gerenciamento

Directory of Open Access Journals (Sweden)

José Luis Fermán Almada

2008-10-01

Full Text Available The Colorado river delta is a unique coastal system in the world, as it combines two important systems: the Colorado river and the Gulf of California. Consequently, the delta is dominated by bilateral interests, and influenced by administrative, political and natural processes, which involve the countries of the United States and Mexico. Located in the northern part of the Gulf of California, under a condition of natural isolation, a series of environmental attributeshave been developed (biotic and abiotic that are only observed in is region. In this work, the development of the bilateral political relations and the most important ecological characteristicsare presented, as well as the management instruments that have been developed for over 80 years. From these issues, the possible scenario for the region is defined, and the development of methodologies for monitoring the effects of these possible tendencies on the natural components of the delta is proposed.O delta do rio Colorado é uma zona costeira única em todo o mundo, porassociar dois importantes sistemas: o próprio rio Colorado e o Golfo da Califórnia. Conseqüentemente, o delta é dominado por interesses bi-nacionais e influenciado por processos administrativos, políticos e naturais, envolvendo os Estados Unidos e o México. Localizado no norte do Golfo da Califórnia, sob uma condição de isolamento natural,desenvolveu-se uma série de atributos ambientais (bióticos e abióticos que só podem ser vistos nessa região. Neste trabalho, são apresentados o desenvolvimento das relações políticas bilaterais e as características ecológicas mais importantes, bem como osmecanismos de gerenciamento que vêm sido desenvolvidos por mais de 80 anos. A partir dessas questões, é definido um cenário tendencial possível para a região, e o desenvolvimento de metodologias para o acompanhamento dos efeitos dessas possíveis tendências sobre os componentes naturais do delta é proposto.

[Microbial community in nitrogen cycle of aquaculture water of the Pearl River Delta].

Science.gov (United States)

Cai, Xiaolong; Luo, Jianfei; Lin, Weitie; Tian, Guoliang

2012-05-04

In order to study the characteristic of nitrogen transport, the community structure and diversity of related microorganisms in aquaculture water of the Pearl River Delta. We established an artificial aquaculture ecosystem to study the microbial community of 15N-stable isotope probing (15N-SIP) labeled nitrogen transport microorganisms. The 15N-labeled DNA was separated by CsCl-ethidium bromide density gradient centrifugation, and was used to construct 16S rRNA gene clone libraries of bacteria and archaea. Phylogenetic analysis shows that 19 Operational Taxonomic Units (OTUs) from bacterial library were clustered in Proteobacteria and Planctomycetes. Proteobacteria (99.2%) was the dominant group, mainly consisted of Comamonas (15.7%), Nitrosomonas (12.4%), Enterobacteriaceae (11.5%) and Nitrobacter (11.5%). From archaeal library 9 OTUs were divided into 3 phyla: Thaumarchaeota, Crenarchaeota and Euryarchaeota. We successfully elucidated the microbial community of nitrogen transport microorganisms in aquaculture water of Pearl River Delta by using 15N-SIP. The data of the community will provide essential information for isolating nitrogen degrading microorganism, and provide scientific basis for creating a healthy aquaculture environment.

Quantitative analysis and simulation of land use changes in the Pearl River Delta, China

Science.gov (United States)

Zhang, Honghui; Zeng, Yongnian; Zou, Bin; Xiao, Pengfeng; Hu, Deyong; Peng, Jianchao

2007-06-01

This paper analyzes and simulates the land use changes in the Pearl River Delta, China, using Longgang City as a case study. The region has pioneered the nation in economic development and urbanization process. Tremendous land use changes have been witnessed since the economic reform in 1978. Land use changes are analyzed and simulated by using stochastic cellular automata model, land use trajectories analysis, spatial indices and multi-temporal TM images of Longgang City (TM1987, TM1991, TM1995, TM1999, TM2003, TM2005) in order to understand how urbanization has transformed the non-urban land to urban land and estimate the consequent environment and ecological impacts in this region. The analysis and simulation results show that urban land continues to sprawl along road and fringe of towns, and concomitant to this development is the loss of agricultural land, orchards and fish ponds. This study provides new evidence with spatial details about the uneven land development in the Pearl River Delta.

Establishing a sediment budget in the newly created "Kleine Noordwaard" wetland area in the Rhine-Meuse delta

Science.gov (United States)

Christien van der Deijl, Eveline; van der Perk, Marcel; Middelkoop, Hans

2018-03-01

Many deltas are threatened by accelerated soil subsidence, sea-level rise, increasing river discharge, and sediment starvation. Effective delta restoration and effective river management require a thorough understanding of the mechanisms of sediment deposition, erosion, and their controls. Sediment dynamics has been studied at floodplains and marshes, but little is known about the sediment dynamics and budget of newly created wetlands. Here we take advantage of a recently opened tidal freshwater system to study both the mechanisms and controls of sediment deposition and erosion in newly created wetlands. We quantified both the magnitude and spatial patterns of sedimentation and erosion in a former polder area in which water and sediment have been reintroduced since 2008. Based on terrestrial and bathymetric elevation data, supplemented with field observations of the location and height of cut banks and the thickness of the newly deposited layer of sediment, we determined the sediment budget of the study area for the period 2008-2015. Deposition primarily took place in channels in the central part of the former polder area, whereas channels near the inlet and outlet of the area experienced considerable erosion. In the intertidal area, sand deposition especially takes place at low-lying locations close to the channels. Mud deposition typically occurs further away from the channels, but sediment is in general uniformly distributed over the intertidal area, due to the presence of topographic irregularities and micro-topographic flow paths. Marsh erosion does not significantly contribute to the total sediment budget, because wind wave formation is limited by the length of the fetch. Consecutive measurements of channel bathymetry show a decrease in erosion and deposition rates over time, but the overall results of this study indicate that the area functions as a sediment trap. The total contemporary sediment budget of the study area amounts to 35.7×103 m3 year-1, which

Channel Evolution Following Avulsion: an Example from the Yellow River Delta

Science.gov (United States)

Zheng, S.

2017-12-01

Long-term field observation of morphological adjustments of rivers following avulsions is lacked when studying the evolution of avulsive channel on deltas. Avulsion at the Yellow River Delta (YRD) is frequent with average lifespan of channels of only about a decade. The Qing-shui-gou channel, the recent lobe on the YRD, provides a rare opportunity for investigating channel evolution following artificial avulsion. The reasons for its longer lifespan also needs investigation of the channel evolution. In this study, we comprehensively analyzed the geomorphic adjustment of the channel based on filed survey data during 1976-2014. The evolution of the channel was impacted by anthropogenic activities, including artificial avulsion at the downstream channel reaches in 1996, alteration of runoff and sediment load through Water and Sediment Regulation Scheme (WSRS), construction of levees and dikes. Analysis on channel geometry showed that avulsions in 1976 and in 1996 both caused short-term (1 2 years) erosion at the upstream channel reaches. Following the avulsion in 1976, massive aggradation occurred at the channel reaches at the downstream of the avulsion point. A single-thread channel gradually formed, widened and enlarged as channel bed under-cut on the deposition material. As delta extended seaward and the longitudinal slope decreased with time, aggradation occurred and an alluvial ridge formed. The ratio of lateral slope to the longitudinal slope (i.e. gradient advantage) and the relative super-elevation of the channel were calculated to estimate the possibility of avulsion at the channel in the late 1990. Results showed that the slope ratio was greater than 20 locally and super-elevation near its critical value for avulsion. The fact, that natural avulsion did not occurred despite of high values of gradient advantage and super elevation, may indicate that they are not sufficient conditions for avulsion at highly human-controlled rivers, where channel boundaries are

Assessment of Environmental Flows for the Rivers of Western Ganges Delta with Special Reference to Indian Sundarban

Science.gov (United States)

Bhadra, T.; Hazra, S.; Ghosh, S.; Barman, B. C.

2016-12-01

The Indian Sundarban, situated on the western tide-dominated part of the Ganges delta was formed by the sedimentation of the Ganges and its tributaries. Freshwater is a scarce resource in the Sundarban though it is traversed by rivers. Most of the rivers of Western Ganges Delta, which used to nourish the Sundarban, have become defunct with the passage of time. To ensure sustainable flow and to enhance the flow-dependent ecosystem services in this region, assessment of environmental flows within the system is required. A pilot assessment of environment flows, supported by IUCN has been carried out in some specific river reaches of Western Ganges Delta under the present study. The holistic Building Block Methodology (BBM) has been modified and used for the assessment of environmental flows. In the modified BBM, three distinctive blocks namely Hydro-Morphology, Ecology and Socio-Economy have been selected and indicators like Ganges Dolphin (Platanista gangetica), Sundari tree (Heritiera fomes) and Hilsa fish (Tenualosa ilisha) etc. have been determined to assess the environmental flows. As the discharge data of the selected rivers are restricted in the public domain, the SWAT model has been run to generate the discharge data of the classified rivers. The Hydraulic model, HEC-RAS has been calibrated in the selected River reaches to assess the habitat availability and its changes for indicator species under different flow condition. The study reveals that River Bhagirathi-Hugli requires 150-427 cumec additional water in monsoon and 850-1127 cumec additional water in post-monsoon months for Hilsa migration, whereas 327-486 cumec additional water in pre-monsoon and dry season and 227-386 cumec additional water in post-monsoon months are required for Dolphin movement. Flow requirement of river Ichhamati has also been estimated under the present study. The total required flow for the Sundarban ecosystem to reduce the salinity level from 30ppt to 14ppt during the dry and pre

Channel-Island Connectivity Affects Water Exposure Time Distributions in a Coastal River Delta

Science.gov (United States)

Hiatt, Matthew; Castañeda-Moya, Edward; Twilley, Robert; Hodges, Ben R.; Passalacqua, Paola

2018-03-01

The exposure time is a water transport time scale defined as the cumulative amount of time a water parcel spends in the domain of interest regardless of the number of excursions from the domain. Transport time scales are often used to characterize the nutrient removal potential of aquatic systems, but exposure time distribution estimates are scarce for deltaic systems. Here we analyze the controls on exposure time distributions using a hydrodynamic model in two domains: the Wax Lake delta in Louisiana, USA, and an idealized channel-island complex. In particular, we study the effects of river discharge, vegetation, network geometry, and tides and use a simple model for the fractional removal of nitrate. In both domains, we find that channel-island hydrological connectivity significantly affects exposure time distributions and nitrate removal. The relative contributions of the island and channel portions of the delta to the overall exposure time distribution are controlled by island vegetation roughness and network geometry. Tides have a limited effect on the system's exposure time distribution but can introduce significant spatial variability in local exposure times. The median exposure time for the WLD model is 10 h under the conditions tested and water transport within the islands contributes to 37-50% of the network-scale exposure time distribution and 52-73% of the modeled nitrate removal, indicating that islands may account for the majority of nitrate removal in river deltas.

Mapping the change of Phragmites australis live biomass in the lower Mississippi River Delta marshes

Science.gov (United States)

Ramsey, Elijah W.; Rangoonwala, Amina

2017-07-28

Multiyear remote sensing mapping of the normalized difference vegetation index (NDVI) was carried out as an indicator of live biomass composition of the Phragmites australis (hereafter Phragmites) marsh in the lower Mississippi River Delta (hereafter delta) from 2014 to 2017. Maps of NDVI change showed that the Phragmites condition was fairly stable between May 2014 and July 2015. From July 2015 to April 2016 NDVI change indicated Phragmites suffered a widespread decline in the live biomass proportion.  Between April and September 2016, most marsh remained unchanged from the earlier period or showed improvement; although there were pockets of continued decline scattered throughout the lower delta. From September 2016 to May 2017 a pronounced and widely exhibited decline in the condition of Phragmites marsh again occurred throughout the lower delta. This final NDVI change mapping supported field observations of Phragmites decline during the same period.

Sedimentation patterns in floodplains of the Mekong Delta - Vietnam

Science.gov (United States)

Van Manh, Nguyen; Merz, Bruno; Viet Dung, Nguyen; Apel, Heiko

2013-04-01

Quantification of floodplain sedimentation during the flood season in the Mekong Delta (MD) plays a very important role in the assessment of flood deposits for a sustainable agro-economic development. Recent studies on floodplain sedimentation in the region are restricted to small pilot sites because of the large extend of the Delta, and the complex channel. This research aims at a quantification of the sediment deposition in floodplains of the whole Mekong Delta, and to access the impacts of the upstream basin development on the sedimentation in the Delta quantitatively. To achieve this, a suspended sediment transport model is developed based on the quasi-2D hydrodynamic model of the whole Mekong Delta developed by Dung et al. (2011). The model is calibrated and validated using observed data derived from several sediment measurement campaigns in channel networks and floodplains. Measured sediment data and hydrodynamic model quantify the spatio-temporal variability of sediment depositions in different spatial units: individual dyke compartments, and the sub-regions Plain of Reeds, Long Xuyen Quadrangle and the area between Tien River and Hau River. It is shown that the distribution of sediment deposition over the delta is highly depended on the flood magnitude, that in turn drives the operation policy of flood control systems in floodplains of the Mekong Delta. Thus, the sedimentation distribution is influenced by the protection level of the dyke systems in place and the distance to the Tien River and Hau River, the main branches of the Mekong in the Delta. This corroborates the main findings derived from data analysis obtained from a small scale test site by Hung et al, (2011, 2012a). Moreover, the results obtained here underlines the importance of the main channels for the sediment transport into the floodplains, and the deposition rate in floodplains is strongly driven by the intake locations and the distance from these to the main channels as well.

2008 USGS/NPS/NASA Experimental Advanced Airborne Research Lidar (EAARL): Pearl River Delta, LA and MS

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A bare earth elevation map (also known as a Digital Elevation Model or DEM) of the Pearl River Delta in Louisiana and Mississippi was produced from remotely sensed,...

Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

Directory of Open Access Journals (Sweden)

Ziliang Liu

Full Text Available A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km. The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front

Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

Science.gov (United States)

Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

2015-01-01

A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front" character.

Behavior and reproductive success of Rock Sandpipers breeding on the Yukon-Kuskokwim River Delta, Alaska

NARCIS (Netherlands)

Johnson, Matthew; Conklin, J.R.; Johnson, Branden; McCaffery, Brian J.; Haig, Susan M.; Walters, Jeffrey R.

2009-01-01

We studied Rock Sandpiper (Calidris ptilocnemis) breeding behavior and monitored reproductive success from 1998 to 2005 on the Yukon-Kuskokwim River Delta, Alaska, USA. We banded 24 adults and monitored 45 nests. Annual return rate of adults ranged between 67 and 100%. Six pairs of Rock Sandpipers

The Impacts of Climate Change in Hong Kong and the Pearl River Delta

International Nuclear Information System (INIS)

Tracy, A.; Trumbull, K.; Loh, C.

2006-11-01

Civic Exchange added climate change to their research agenda some time ago, recognising that it is a cross-cutting issue that will have substantial impact, not only on Hong Kong but on the entire Pearl River Delta. The Hong Kong region is the wealthiest part of China. Along with growing material wealth, Hong Kong's ecological footprint and particularly it's greenhouse gas emissions - have increased exponentially. Therefore, there exists a special responsibility to contribute to finding effective mitigation measures that can help to slow the process; as well as a pressing need to find ways to adapt to those effects of climate change that cannot be forestalled. This paper represents a first attempt to pull together the relevant materials, with the aim of providing a broad-brush view of how climate change may affect Hong Kong, Macao and the Pearl River Delta. The key recommendation is that more region-specific research must be carried out. Civic Exchange has also taken note of the recently published Stern Review, which was commissioned by the United Kingdom government, to assess the economics of climate change. The report calls for urgent action. In this respect, this report therefore doubles as a funding proposal

[Estimation of urban non-point source pollution loading and its factor analysis in the Pearl River Delta].

Science.gov (United States)

Liao, Yi-Shan; Zhuo, Mu-Ning; Li, Ding-Qiang; Guo, Tai-Long

2013-08-01

In the Pearl Delta region, urban rivers have been seriously polluted, and the input of non-point source pollution materials, such as chemical oxygen demand (COD), into rivers cannot be neglected. During 2009-2010, the water qualities at eight different catchments in the Fenjiang River of Foshan city were monitored, and the COD loads for eight rivulet sewages were calculated in respect of different rainfall conditions. Interesting results were concluded in our paper. The rainfall and landuse type played important roles in the COD loading, with greater influence of rainfall than landuse type. Consequently, a COD loading formula was constructed that was defined as a function of runoff and landuse type that were derived SCS model and land use map. Loading of COD could be evaluated and predicted with the constructed formula. The mean simulation accuracy for single rainfall event was 75.51%. Long-term simulation accuracy was better than that of single rainfall. In 2009, the estimated COD loading and its loading intensity were 8 053 t and 339 kg x (hm2 x a)(-1), and the industrial land was regarded as the main source of COD pollution area. The severe non-point source pollution such as COD in Fenjiang River must be paid more attention in the future.

Geochronology of priority pollutants in sedimentation zones of the Volga and Danube delta in comparison with the Rhine delta

International Nuclear Information System (INIS)

Winkels, H.J.; Kroonenberg, S.B.; Lychagin, M.Y.; Marin, G.; Rusakov, G.V.; Kasimov, N.S.

1998-01-01

Six sediment cores were taken in sedimentation zones of the Volga river (located in the southern part of the Russian Federation) and, additionally, 6 sediment cores were taken in several lakes (sedimentation zones) in the central and western part of the Danube delta in Romania. Priority pollutants (8 metals, 7 polychlorinated biphenyls and 10 polycyclic aromatic hydrocarbons) were determined in all samples of all cores. Present-day and historical levels of pollutants since the late 1930s were established through the use of radionuclide time tracers ( 137 Cs, 134 Cs). For the persistent metals and polycyclic aromatic hydrocarbons, trends in the concentration profiles during the last 5 decades are described. Low and hardly changing concentrations of As, Cu, Zn and all studied PAHs were observed during the last five decades in the sediments of the Volga river. Recently deposited sediments show slightly increasing levels for the heavy metals Zn and Cr and As in the Volga delta. For the studied metals and PAHs, maximum concentrations were found around 1987 in the sediments of the Danube delta. Sediments deposited around 1940 and recently deposited sediments in the Danube delta showed lower pollutant levels. If the contents of heavy metals, PAHs and PCBs in the aquatic sediments in the deltas of the rivers Rhine, Danube and Volga are compared, it is clear that the Volga delta is and was the cleanest delta during the last 5 decades. Nowadays the contents of heavy metals (except Cu and Ni), PAHs and PCBs in the aquatic sediments of the river Rhine are still highest compared to the other two rivers. The recent load of heavy metals (except Cd and Zn) in the sediments of the river Danube is the highest compared to the other two rivers. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

The changing hydro-ecological dynamics of rivers and deltas of the Western Indian Ocean: Anthropogenic and environmental drivers, local adaptation and policy response

Science.gov (United States)

Duvail, Stéphanie; Hamerlynck, Olivier; Paron, Paolo; Hervé, Dominique; Nyingi, Wanja D.; Leone, Michele

2017-10-01

The rivers flowing into the Western Indian Ocean have steep headwater gradients and carry high sediment loads. In combination with strong tides and seasonal rainfall, these rivers create dynamic deltas with biodiversity-rich and productive ecosystems that, through flooding, have sustained indigenous use systems for centuries. However, river catchments are rapidly changing due to deforestation. Hydropower dams also increasingly alter flood characteristics, reduce sediment supply and contribute to coastal erosion. These impacts are compounded by climate change. Altogether, these changes affect the livelihoods of the delta users. Here, based on prior works that we and others have conducted in the region, we analyse the drivers of these hydro-ecological changes. We then provide recommendations for improved dam design and operations to sustain the underlying delta-building processes, the ecosystem values and the needs of the users.

Urbanization signatures in strong versus weak precipitation over the Pearl River Delta metropolitan regions of China

International Nuclear Information System (INIS)

Li Weibiao; Chen Sheng; Wen Zhiping; Wang Baomin; Chen Guixing; Sha Weimin; Luo Cong; Feng Yerong

2011-01-01

We assess the issues of urban effects on the precipitation over the Pearl River Delta (PRD) metropolitan regions of China. The spatial and temporal variations of strong versus weak precipitation over the PRD and surrounding nonurban areas are investigated. The results show that the urbanization signatures in strong precipitation are significantly different from those in weak precipitation over the urban areas. The PRD experiences more strong precipitation but less weak precipitation compared to surrounding nonurban regions. In addition, the strong precipitation over the PRD displays a pronounced seasonal variation. The seasonality of weak precipitation, however, is much weaker over the PRD compared to the surrounding nonurban regions. Moreover, a strengthening in the precipitation intensity, a reduction in the rainfall frequency and an increase in the convective precipitation as well as the afternoon precipitation are found over the urban areas, which are probably associated with the abundance in strong precipitation and the deficit in weak precipitation over the PRD.

Aspectos do licenciamento ambiental da carcinicultura na APA do Delta do Parnaíba Aspects of environmental licensing for carciniculture in EPA of the Delta of Parnaíba River

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Hamilton Gondim de Alencar Araripe

2006-12-01

Full Text Available O presente trabalho tem como foco uma análise do valor do licenciamento ambiental da carcinicultura na APA do Delta do Parnaíba. Realizou-se visitas técnicas a todos empreendimentos instalados até o primeiro semestre de 2004, levantou-se a legislação pertinente, avaliou-se estudos ambientais e relatórios de vistorias técnicas realizadas pelo IBAMA. Concluiu-se que o enquadramento feito pelo IBAMA no processo de licenciamento do que seja área de preservação permanente (APP no manguezal é o ponto crítico para a atividade de carcinicultura.The present research examines the environmental matter in the Environmental Protection Area (EPA of the Delta of the Parnaíba River, focusing on the ambient licensing value. Technical visits to all companies installed in the area until the first semester of 2004 and non-structured interviews were carried out; the existing legislation was raised; and the environmental studies and reports of technical inspections performed by IBAMA were evaluated. The conclusion was that the adjustment made by IBAMA in the ambient licensing process of what is an Area of Permanent Preservation (APP in the mangrove is the critical point to the carciniculture activity.

Soil properties of mangroves in contrasting geomorphic settings within the Zambezi River Delta, Mozambique

Science.gov (United States)

Christina E. Stringer; Carl C. Trettin; Stan Zarnoch

2016-01-01

Mangroves are well-known for their numerous ecosystem services, including sequestering a significant carbon stock, with soils accounting for the largest pool. The soil carbon pool is dependent on the carbon content and bulk density. Our objective was to assess the spatial variability of mangrove soil physical and chemical properties within the Zambezi River Delta and...

2010-2015 Juvenile fish ecology in the Nisqually River Delta and Nisqually Reach Aquatic Reserve

Science.gov (United States)

Hodgson, Sayre; Ellings, Christopher S.; Rubin, Steve P.; Hayes, Michael C.; Duval, Walker; Grossman, Eric E.

2017-01-01

The return of tidal inundation to over 750 acres of the U. S. Fish and Wildlife Service Billy Frank Jr. Nisqually National Wildlife Refuge (NNWR) in fall of 2009 was the crowning moment in the effort to protect and restore the Nisqually Delta. The Nisqually NWR project complemented three earlier restoration projects completed by the Nisqually Indian Tribe (Tribe) on tribal property to restore over 900 acres of the estuary, representing the largest estuary restoration project in the Pacific Northwest and one of the most significant advances to date towards the recovery of Puget Sound (USFWS 2005). In 2011 the Washington Department of Natural Resources (WADNR established the over 14000 acre Nisqually Reach Aquatic Reserve (Reserve), complementing the protection and restoration successes in the Nisqually Delta. The Reserve includes all state-owned aquatic lands around Anderson, Ketron and Eagle islands and part of McNeil Island (Figure 1, WDNR 2011). The Reserve also includes a diverse assemblage of nearshore and offshore habitats important to resident and migratory fish including federal endangered species act listed fish like Chinook salmon (Oncorynchus tshawytscha) and steelhead (O. mykiss). Studies in the Nisqually Estuary (Ellings and Hodgson 2007, David et al. 2014, Ellings et al. 2016) and South Puget Sound (Duffy 2003) have summarized fish use of the area. However, the fish ecology of the reserve had not been systematically surveyed. The Tribe, U.S. Geological Survey (USGS), NNWR, Nisqually River Foundation (NRF), and others are currently conducting a multi-year, interdisciplinary, hypothesis-based research and monitoring study investigating the impact of delta restoration on estuarine processes, habitat structures, and functions. Our interdisciplinary monitoring framework enables us to link key estuarine processes with habitat development and biological response at multiple scales across the restored footprint, reference marshes, and throughout the Nisqually

Spatial Pattern of Soil Salinity in Area Around the Yellow River Delta and Its Seasonal Dynamics over a 3-year Period

Science.gov (United States)

Lai, J.; Ouyang, Z.

2017-12-01

Salt-affected land varies spatially and seasonally in terms of soil salinity. "Bohai Granary" is a newly proposed national-level program which was aimed to improve soil quality and mining grain production potential of the salt-affected land in east China. In this work, soil samples were monthly taken at 11 sites within Wudi county in the Yellow river delta. The spatial distribution pattern of soil salinity were investigated and its seasonal variation over 36 months were discussed. Our findings indicate that the vertical distribution type of soil salinity was bottom-accumulating in the near coastal area while its gradually turned into a type of surface-accumulating as the sampling site moving towards the inner land. The peak of the soil salinity along the soil profile alternately moved upwards and downwards during the growing seasons. However, there was no evidence for the increasing of the total salt amount within the upper 100cm of soil. Moreover, the salt was mostly accumulated in the upper soil (0-40cm) during the late spring and early summer season; and winter wheat was tend to be affected severely at this stage. Therefore, special field practices (e.g. regular irrigation to leach salt, good maintenance of drainage system) should be taken to minimize the threat of soil salinity.

Retrieval of High-Resolution Atmospheric Particulate Matter Concentrations from Satellite-Based Aerosol Optical Thickness over the Pearl River Delta Area, China

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Lili Li

2015-06-01

Full Text Available Satellite remote sensing offers an effective approach to estimate indicators of air quality on a large scale. It is critically significant for air quality monitoring in areas experiencing rapid urbanization and consequently severe air pollution, like the Pearl River Delta (PRD in China. This paper starts with examining ground observations of particulate matter (PM and the relationship between PM10 (particles smaller than 10 μm and aerosol optical thickness (AOT by analyzing observations on the sampling sites in the PRD. A linear regression (R2 = 0.51 is carried out using MODIS-derived 500 m-resolution AOT and PM10 concentration from monitoring stations. Data of atmospheric boundary layer (ABL height and relative humidity are used to make vertical and humidity corrections on AOT. Results after correction show higher correlations (R2 = 0.55 between extinction coefficient and PM10. However, coarse spatial resolution of meteorological data affects the smoothness of retrieved maps, which suggests high-resolution and accurate meteorological data are critical to increase retrieval accuracy of PM. Finally, the model provides the spatial distribution maps of instantaneous and yearly average PM10 over the PRD. It is proved that observed PM10 is more relevant to yearly mean AOT than instantaneous values.

Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007

Energy Technology Data Exchange (ETDEWEB)

Sobocinski, Kathryn L.; Johnson, Gary E.; Sather, Nichole K.; Storch, Adam; Jones, Tucker A.; Mallette, Christine; Dawley, Earl M.; Skalski, John R.; Teel, David; Moran, Paul

2008-03-18

This document is the first annual report for the study titled “Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River.” Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council’s Columbia Basin Fish and Wildlife Program.

Amphibian and reptile records from around the Betsiboka Delta area in North-Western Madagascar

NARCIS (Netherlands)

Rakotoarison, Andolalao; Erens, Jesse; Ratsoavina, Fanomezana M.; Vences, Miguel

2015-01-01

This study summarises amphibian and reptile records from ad hoc surveys in a series of localities in the North-West of Madagascar, largely centred on the delta of the Betsiboka River. Eleven amphibian and approximately 32 reptile species were found, with taxonomic uncertainties remaining for some

Aerosol profiles determined with lidar and sun-photometer over the Pearl River Delta, China.

Science.gov (United States)

Heese, B.; Althausen, D.; Bauditz, M.; Deng, R.; Bao, R.; Li, Z.

2012-04-01

The priority program "Megacities-Megachallenge - Informal Dynamics of Global Change" is a large interdisciplinary project funded by the German Research Foundation (DFG). One of the subproject deals with mega-urbanisation in the Pearl River Delta, South-China, with special respect to particulate air pollution and public health. In the frame of this subproject the vertical distribution of aerosol optical properties are investigated by measurements with the multiwavelength-Raman-polarization lidar PollyXT of the IfT. The instrument can measure the particle backscatter coefficient at 355 nm, 532 nm, and 1064 nm, the particle extinction coefficients at 355 nm and 532 nm, and the particle linear depolarization ratio at 532 nm. These measurements are supported by a dual-polar sun photometer that provides height integrated data as the aerosol optical depth and the degree of linear depolarization. These instruments are placed at the East campus of the Sun Yat-sen University in Guangzhou, China. Guangzhou and the Pearl River Delta is a developing area with currently around 11 Million inhabitants. The measurements started in November 2011 and are supposed to continue for at least half a year covering the late autumn and winter season and parts of the spring season. Extensions of the measurements towards a whole seasonal cycle are planned. Thus, different meteorological conditions will lead to particle transport from several source regions. Different aerosol types are expected to be observed during the measurement period: urban particles from local and regional sources as well as dust from the deserts in Central Asia. The observed particles can be distinguished by analyzing their optical properties at several wavelengths. In particular, the depolarization measurements from both instruments promise a better determination of the particle shape.

Crustal structure revealed by a deep seismic sounding profile of Baijing-Gaoming-Jinwan in the Pearl River Delta

Science.gov (United States)

Zhang, Xiang; Ye, Xiuwei; Lv, Jinshui; Sun, Jinlong; Wang, Xiaona

2018-02-01

The Pearl River Estuary area, located in the middle part of the southern China coastal seismic belt, has long been considered a potential source of strong earthquakes above magnitude 7.0. To scientifically assess the potential strong earthquake risk in this area, a three-dimensional artificial seismic sounding experiment, consisting of a receiving array and seabed seismograph, was performed to reveal the deep crustal structure in this region. We used artificial ship-borne air-gun excitation shots as sources, and fixed and mobile stations as receivers to record seismic data from May to August 2015. This paper presents results along a line from the western side of the Pearl River Estuary to the western side of the Baijing-Gaoming-Jinwan profile. A two-dimensional velocity structure was constructed using seismic travel-time tomography. The inversion results show that the Moho depth is 27 km in the coastal area and 30 km in the northwest of the Pearl River Estuary area, indicating that the crust thins from land to sea. Two structural discontinuities and multiple low-velocity anomalies appear in the crustal section. Inside both discontinuity zones, a low-velocity layer, with a minimum velocity of 6.05 km s-1, exists at a depth of about 15 km, and another, with a minimum velocity of 6.37 km s-1, exists at a depth of about 21.5 km between the middle and lower crust. These low velocities suggest that the discontinuities may consist of partly molten material. Earthquakes with magnitudes higher than 5.0 occurred in the low-velocity layer along the profile. The deep Kaiping-Enping fault, rooted in the crust, may be one of the most important channels for deep material upwelling and is related to tectonic movement since the Cretaceous in the Pearl River Delta tectonic rift basin.

Harmful algae records in Venice lagoon and in Po River Delta (northern Adriatic Sea, Italy).

Science.gov (United States)

Facca, Chiara; Bilaničovà, Dagmar; Pojana, Giulio; Sfriso, Adriano; Marcomini, Antonio

2014-01-01

A detailed review of harmful algal blooms (HAB) in northern Adriatic Sea lagoons (Po River Delta and Venice lagoon) is presented to provide "updated reference conditions" for future research and monitoring activities. In the study areas, the high mollusc production requires the necessity to identify better methods able to prevent risks for human health and socioeconomical interests. So, an integrated approach for the identification and quantification of algal toxins is presented by combining microscopy techniques with Liquid Chromatography coupled with High Resolution Time of Flight Mass Spectrometry (HPLC-HR-TOF-MS). The method efficiency was first tested on some samples from the mentioned coastal areas, where Dinophysis spp. occurred during summer in the sites directly affected by seawaters. Although cell abundance was always <200 cells/L, the presence of Pectenotoxin-2 (PTX2), detected by HPLC-HR-TOF-MS, indicated the potential release of detectable amounts of toxins even at low cell abundance.

River Basin Water Assessment and Balance in fast developing areas in Viet Nam

Science.gov (United States)

Le, Van Chin; Ranzi, Roberto

2010-05-01

Uneven precipitation in space and time together with mismanagement and lack of knowledge about quantity and quality of water resources, have caused water shortages for water supply to large cities and irrigation areas in many regions of Viet Nam in the dry season. The rainy season (from June to October) counts for 80% of the total annual rainfall, while the water volume of dry season (from November to May of the following year) accounts for 20% only. Lack of sufficient water volumes occurs in some areas where the pressure of a fast increasing population (1.3% per year on average in the last decade in Viet Nam), intensive agricultural and industrial uses is one of the major problems facing sustainable development. For those areas an accurate water assessment and balance at the riverbasin scale is needed to manage the exploitation and appropriate use of water resources and plan future development. The paper describes the preliminary phase of the pilot development of the river basin water balance for the Day River Basin in the Red River delta in Viet Nam. The Day river basin includes a 7,897 km² area in the south-western part of the Red River in Viet Nam. The total population in the Day river basin exceeds 8 millions inhabitants, including the Hanoi capital, Nam Dinh and other large towns. Agricultural land covered 390,294 ha in 2000 and this area is going to be increased by 14,000 ha in 2010 due to land reclamation and expansion toward the sea. Agricultural uses exploit about 90% of surface water resources in the Day river basin but have to compete with industrial and civil needs in the recent years. At the background of the brief characterization of the Day River Basin, we concentrate on the application of a water balance model integrated by an assessment of water quality after consumptive uses for civil, agricultural and industrial needs to assist water management in the basin. In addition, future development scenarios are taken into account, considering less

A retrospective analysis of trace metals, C, N and diatom remnants in sediments from the Mississippi River delta shelf

International Nuclear Information System (INIS)

Turner, R. Eugene; Milan, C.S.; Rabalais, N.N.

2004-01-01

The development of oil and gas recovery offshore of the Mississippi River delta began in shallow water in the 1950s, expanded into deeper waters, and peaked in the 1990s. This area of the outer continental shelf (OCS) is the historical and present location of >90% of all US OCS oil and gas production and reserves. The juxtaposition of its 4000 producing platforms, recovering $10 billion yr -1 of oil, gas and produced water in the same area where about 28% of the US fisheries catch (by weight) is made and near 40% of the US coastal wetlands, makes this an area worth monitoring for regional pollutant loading. This loading may come from several sources, including sources related to OCS development, but also from the Mississippi River watershed. In this context, any contaminant loading on this shelf may be neither detectable nor significant against a background of climatic or biological variability. We examined the sedimentary record for indicators of industrial byproducts from OCS oil and gas development and of industrial products entering via the Mississippi River, primarily using vanadium (V) and barium (Ba) concentrations normalized for aluminum (Al). Barium is primarily used in drilling muds in the form of barite, whereas V is an important strengthening component of metal alloys, including steel. The fluctuations in the accumulation of Ba, but not V, were coincidental with the presumed use of barite. The fluctuations in V concentration in the sediments were coincidental with the national consumption of V. Copper (Cu), cadmium (Cd) and zinc (Zn) concentrations in sediments fluctuate coincidentally with V, not Ba, thus indicating that the dominant source of these trace metals in offshore sediments were derived from riverine sources, and were not primarily from in situ industrial processes releasing them on the shelf. This is not to suggest that local site-specific contamination is not a significant management or health concern. The low oxygen (hypoxia; ≤2 mg l -1

Optimality and self-organization in river deltas

Science.gov (United States)

Tejedor, A.; Longjas, A.; Edmonds, D. A.; Zaliapin, I. V.; Georgiou, T. T.; Rinaldo, A.; Foufoula-Georgiou, E.

2017-12-01

Deltas are nourished by channel networks, whose connectivity constrains, if not drives, the evolution, functionality and resilience of these systems. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding maintenance strategies of these highly stressed systems from a range of anthropogenic activities. However, in contrast to tributary channel networks, to date, no theory has been proposed to explain how deltas self-organize to distribute water and sediment to the delta top and the shoreline. Here, we hypothesize the existence of an optimality principle underlying the self-organized partition of fluxes in delta channel networks. Specifically, we hypothesize that deltas distribute water and sediment fluxes on a given delta topology such as to maximize the diversity of flux delivery to the shoreline. By introducing the concept of nonlocal Entropy Rate (nER) and analyzing ten field deltas in diverse environments, we present evidence that supports our hypothesis, suggesting that delta networks achieve dynamically accessible maxima of their nER. Furthermore, by analyzing six simulated deltas using the Delf3D model and following their topologic and flux re-organization before and after major avulsions, we further study the evolution of nER and confirm our hypothesis. We discuss how optimal flux distributions in terms of nER, when interpreted in terms of resilience, are configurations that reflect an increased ability to withstand perturbations.

Sedimentary architecture and depositional controls of a Pliocene river-dominated delta in the semi-isolated Dacian Basin, Black Sea

Science.gov (United States)

Jorissen, Elisabeth L.; de Leeuw, Arjan; van Baak, Christiaan G. C.; Mandic, Oleg; Stoica, Marius; Abels, Hemmo A.; Krijgsman, Wout

2018-06-01

Sedimentological facies models for (semi-)isolated basins are less well developed than those for marine environments, but are critical for our understanding of both present-day and ancient deltaic sediment records in restricted depositional environments. This study considers an 835 m thick sedimentary succession of mid-Pliocene age, which accumulated in the Dacian Basin, a former embayment of the Black Sea. Detailed sedimentological and palaeontological analyses reveal a regression from distal prodelta deposits with brackish water faunas to delta-top deposits with freshwater faunas. Sediments contain frequent hyperpycnal plumes and an enrichment in terrestrial organic material, ichnofossils and in situ brackish and freshwater faunas. Deltaic progradation created thin, sharply-based sand bodies formed by multiple terminal distributary channels, covering a wide depositional area. The system experienced frequent delta-lobe switching, resulting in numerous thin parasequences. Parasequences are overlain by erosive reddish oxidized sand beds, enriched in broken, abraded brackish and freshwater shells. These beds were formed after sediment starvation, on top of abandoned delta lobes during each flooding event. A robust magnetostratigraphic time frame allowed for comparison between the observed sedimentary cyclicity and the amplitude and frequency of astronomical forcing cycles. Our results indicate that parasequence frequencies are significantly higher than the number of time equivalent astronomical cycles. This suggests that delta-lobe switching was due to autogenic processes. We consider the observed facies architecture typical for a delta prograding on a low-gradient slope into a shallow, brackish, protected, semi-isolated basin. Furthermore, in the absence of significant wave and tidal influence, sediment progradation in such a protected depositional setting shaped a delta, strongly river-dominated.

Combining L- and X-Band SAR Interferometry to Assess Ground Displacements in Heterogeneous Coastal Environments: The Po River Delta and Venice Lagoon, Italy

Directory of Open Access Journals (Sweden)

Luigi Tosi

2016-04-01

Full Text Available From leveling to SAR-based interferometry, the monitoring of land subsidence in coastal transitional environments significantly improved. However, the simultaneous assessment of the ground movements in these peculiar environments is still challenging. This is due to the presence of relatively small built-up zones and infrastructures, e.g., coastal infrastructures, bridges, and river embankments, within large natural or rural lands, e.g., river deltas, lagoons, and farmland. In this paper we present a multi-band SAR methodology to integrate COSMO-SkyMed and ALOS-PALSAR images. The method consists of a proper combination of the very high-resolution X-band Persistent Scatterer Interferometry (PSI, which achieves high-density and precise measurements on single structures and constructed areas, with L-band Short-Baseline SAR Interferometry (SBAS, properly implemented to raise its effectiveness in retrieving information in vegetated and wet zones. The combined methodology is applied on the Po River Delta and Venice coastland, Northern Italy, using 16 ALOS-PALSAR and 31 COSMO-SkyMed images covering the period between 2007 and 2011. After a proper calibration of the single PSI and SBAS solution using available GPS records, the datasets have been combined at both the regional and local scales. The measured displacements range from ~0 mm/yr down to −35 mm/yr. The results reveal the variable pattern of the subsidence characterizing the more natural and rural environments without losing the accuracy in quantifying the sinking of urban areas and infrastructures. Moreover, they allow improving the interpretation of the natural and anthropogenic processes responsible for the ongoing subsidence.

Geomorphology of the Elwha River and its Delta: Chapter 3 in Coastal habitats of the Elwha River, Washington--biological and physical patterns and processes prior to dam removal

Science.gov (United States)

Warrick, Jonathan A.; Draut, Amy E.; McHenry, Michael L.; Miller, Ian M.; Magirl, Christopher S.; Beirne, Matthew M.; Stevens, Andrew Stevens; Logan, Joshua B.; Duda, Jeffrey J.; Warrick, Jonathan A.; Magirl, Christopher S.

2011-01-01

The removal of two dams on the Elwha River will introduce massive volumes of sediment to the river, and this increase in sediment supply in the river will likely modify the shapes and forms of the river and coastal landscape downstream of the dams. This chapter provides the geologic and geomorphologic background of the Olympic Peninsula and the Elwha River with emphasis on the present river and shoreline. The Elwha River watershed was formed through the uplift of the Olympic Mountains, erosion and movement of sediment throughout the watershed from glaciers, and downslope movement of sediment from gravitational and hydrologic forces. Recent alterations to the river morphology and sediment movement through the river include the two large dams slated to be removed in 2011, but also include repeated bulldozing of channel boundaries, construction and maintenance of flood plain levees, a weir and diversion channel for water supply purposes, and engineered log jams to help enhance river habitat for salmon. The shoreline of the Elwha River delta has changed in location by several kilometers during the past 14,000 years, in response to variations in the local sea-level of approximately 150 meters. Erosion of the shoreline has accelerated during the past 80 years, resulting in landward movement of the beach by more than 200 meters near the river mouth, net reduction in the area of coastal wetlands, and the development of an armored low-tide terrace of the beach consisting primarily of cobble. Changes to the river and coastal morphology during and following dam removal may be substantial, and consistent, long-term monitoring of these systems will be needed to characterize the effects of the dam removal project.

Bi-objective analysis of water-sediment regulation for channel scouring and delta maintenance: A study of the lower Yellow River

Science.gov (United States)

Kong, D.; Miao, C.; Duan, Q.

2016-12-01

Long-term hydrological data and remotely-sensed satellite images were used to analyze the effects of the water-sediment regulation scheme (WSRS) implemented in the lower Yellow River (LYR), China, between 1983 and 2013. The WSRS aimed to control channel scouring in the LYR and maintain the Yellow River Delta (YRD). Channel erosion in the LYR has primarily depended on the incoming sediment concentration at Xiaolangdi, where the concentration must be lower than approximately 9.17 × 10-3 t m-3 to avoid rising of the riverbed. In 1996, an artificial diversion altered the evolution of the YRD. To maintain delta equilibrium, an average sediment load of about 441 × 106 t year-1 was required before 1996, after which this value decreased to 167 × 106 t year-1. We provide a preliminary estimate of the incoming water and sediment conditions required at the Xiaolangdi station to guarantee both LYR channel scouring and maintenance of the YRD. Our results show that it is feasible to transport sediment originally deposited in the LYR to the river mouth to maintain the delta, which is of great significance for the future management and environmental protection of the LYR.

A magnetic record of heavy metal pollution in the Yangtze River subaqueous delta.

Science.gov (United States)

Dong, Chenyin; Zhang, Weiguo; Ma, Honglei; Feng, Huan; Lu, Honghua; Dong, Yan; Yu, Lizhong

2014-04-01

The rapid industrial development in the Yangtze River watershed over the last several decades has drawn great attention with respect to heavy metal pollution to the Yangtze River estuary and nearby coastal areas. In this study, a 236 cm long sediment core was retrieved from the Yangtze River subaqueous delta (122°36' E, 31°00' N) in 2008 and analyzed for magnetic properties and geochemical compositions to investigate heavy metal pollution history. The activity of (137)Cs peaked at depth 140 cm, with a broad plateau between 120 cm and 140 cm, suggesting an average sedimentation rate of 3.11 cm yr(-1) for the upper 140 cm layer. Magnetic susceptibility (χ), saturation isothermal remanent magnetization (SIRM), anhysteretic remanent magnetization (χARM) and heavy metal enrichment factors (EF) all showed an upward increase trend above depth 140 cm, suggesting that increased ferrimagnetic mineral concentration was accompanied by heavy metal enrichment in the sediment. Geochemical and granolumetric analyses showed that sediment sources and particle sizes played minor roles in the variations of magnetic properties. The effect of diagenesis, which can lead to the selective removal of magnetic minerals, was noticeable in the lower part of the core (140-236 cm). Co-variation between magnetic properties (χ, SIRM and χARM) and EF of Cu and Pb suggests that the elevated ferrimagnetic mineral concentration can be used as an indicator of heavy metal pollution in the reconstruction of environmental changes in estuarine and coastal settings. Copyright © 2014. Published by Elsevier B.V.

A magnetic record of heavy metal pollution in the Yangtze River subaqueous delta

International Nuclear Information System (INIS)

Dong, Chenyin; Zhang, Weiguo; Ma, Honglei; Feng, Huan; Lu, Honghua; Dong, Yan; Yu, Lizhong

2014-01-01

The rapid industrial development in the Yangtze River watershed over the last several decades has drawn great attention with respect to heavy metal pollution to the Yangtze River estuary and nearby coastal areas. In this study, a 236 cm long sediment core was retrieved from the Yangtze River subaqueous delta (122°36′ E, 31°00′ N) in 2008 and analyzed for magnetic properties and geochemical compositions to investigate heavy metal pollution history. The activity of 137 Cs peaked at depth 140 cm, with a broad plateau between 120 cm and 140 cm, suggesting an average sedimentation rate of 3.11 cm yr −1 for the upper 140 cm layer. Magnetic susceptibility (χ), saturation isothermal remanent magnetization (SIRM), anhysteretic remanent magnetization (χ ARM ) and heavy metal enrichment factors (EF) all showed an upward increase trend above depth 140 cm, suggesting that increased ferrimagnetic mineral concentration was accompanied by heavy metal enrichment in the sediment. Geochemical and granolumetric analyses showed that sediment sources and particle sizes played minor roles in the variations of magnetic properties. The effect of diagenesis, which can lead to the selective removal of magnetic minerals, was noticeable in the lower part of the core (140–236 cm). Co-variation between magnetic properties (χ, SIRM and χ ARM ) and EF of Cu and Pb suggests that the elevated ferrimagnetic mineral concentration can be used as an indicator of heavy metal pollution in the reconstruction of environmental changes in estuarine and coastal settings. - Highlights: • Magnetic parameters can be used as heavy metal pollution proxy. • Heavy metal contents in the Yangtze River estuary increase since the 1960s. • Heavy metal pollution is largely driven by population growth in the catchment

A magnetic record of heavy metal pollution in the Yangtze River subaqueous delta

Energy Technology Data Exchange (ETDEWEB)

Dong, Chenyin [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China); Zhang, Weiguo, E-mail: wgzhang@sklec.ecnu.edu.cn [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China); Ma, Honglei [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China); Feng, Huan [Department of Earth and Environmental Studies, Montclair State University, NJ 07043 (United States); Lu, Honghua [Department of Geography, College of Resources and Environmental Science, East China Normal University, Shanghai 200241 (China); Dong, Yan [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China); Institute of Geographic Engineering Technology, School of Geographical Science, Nantong University, Nantong 226007 (China); Yu, Lizhong [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China)

2014-04-01

The rapid industrial development in the Yangtze River watershed over the last several decades has drawn great attention with respect to heavy metal pollution to the Yangtze River estuary and nearby coastal areas. In this study, a 236 cm long sediment core was retrieved from the Yangtze River subaqueous delta (122°36′ E, 31°00′ N) in 2008 and analyzed for magnetic properties and geochemical compositions to investigate heavy metal pollution history. The activity of {sup 137}Cs peaked at depth 140 cm, with a broad plateau between 120 cm and 140 cm, suggesting an average sedimentation rate of 3.11 cm yr{sup −1} for the upper 140 cm layer. Magnetic susceptibility (χ), saturation isothermal remanent magnetization (SIRM), anhysteretic remanent magnetization (χ{sub ARM}) and heavy metal enrichment factors (EF) all showed an upward increase trend above depth 140 cm, suggesting that increased ferrimagnetic mineral concentration was accompanied by heavy metal enrichment in the sediment. Geochemical and granolumetric analyses showed that sediment sources and particle sizes played minor roles in the variations of magnetic properties. The effect of diagenesis, which can lead to the selective removal of magnetic minerals, was noticeable in the lower part of the core (140–236 cm). Co-variation between magnetic properties (χ, SIRM and χ{sub ARM}) and EF of Cu and Pb suggests that the elevated ferrimagnetic mineral concentration can be used as an indicator of heavy metal pollution in the reconstruction of environmental changes in estuarine and coastal settings. - Highlights: • Magnetic parameters can be used as heavy metal pollution proxy. • Heavy metal contents in the Yangtze River estuary increase since the 1960s. • Heavy metal pollution is largely driven by population growth in the catchment.

Drowning of the Mississippi Delta due to insufficient sediment supply and global sea-level rise

Science.gov (United States)

Blum, Michael D.; Roberts, Harry H.

2009-07-01

Over the past few centuries, 25% of the deltaic wetlands associated with the Mississippi Delta have been lost to the ocean. Plans to protect and restore the coast call for diversions of the Mississippi River, and its associated sediment, to sustain and build new land. However, the sediment load of the Mississippi River has been reduced by 50% through dam construction in the Mississippi Basin, which could affect the effectiveness of diversion plans. Here we calculate the amount of sediment stored on the delta plain for the past 12,000 years, and find that mean storage rates necessary to construct the flood plain and delta over this period exceed modern Mississippi River sediment loads. We estimate that, in the absence of sediment input, an additional 10,000-13,500km2 will be submerged by the year 2100 owing to subsidence and sea-level rise. Sustaining existing delta surface area would require 18-24billiontons of sediment, which is significantly more than can be drawn from the Mississippi River in its current state. We conclude that significant drowning is inevitable, even if sediment loads are restored, because sea level is now rising at least three times faster than during delta-plain construction.

The Dokka delta - consequences of water power development in the River Dokka

International Nuclear Information System (INIS)

Halvorsen, Gunnar; Sloreid, Svein-Erik; Walseng, Bjoern

1997-11-01

The report concerns an investigation done in Norway on environmental consequences of hydroelectric power development in the Dokka river. This development has reduced the water flow through the Dokka delta to about 50% of its natural level. The biological effect of the reduction has been studied in the period from 1987 to 1990, comprising two years before and two years after the reduction. Sedimentation, water chemistry, planktonic and littoral crustaceans and bottom fauna have been studied. 223 refs., 58 figs., 9 tabs

Associated fauna to the mangroves and other marshes in the Delta-estuary of the River Magdalena, Colombia

International Nuclear Information System (INIS)

Moreno Bejarano, Luz Myriam; Alvarez Leon, Ricardo

2003-01-01

A synthesis of observations and collections of fauna associated with different vegetative communities and bodies of water present in the estuarine-delta of Magdalena river, with emphasis in the Via Park Isla Salamanca (56.200 acres) and National Reserve Flora and Fauna Sanctuary of the Cienaga Grande de Santa Marta (23.000 acres), between 1978-1985. The information was gathered through samplings and manual captures affected during 1978 and period 1981-1985, as well as accomplished direct observations sporadically in the period 1986-1998. The records of 10 species of amphibians, 40 species of reptiles, 194 species of birds and 46 species of mammals show the great variety of fauna in this Caribbean area of Colombia

Drones on the delta | IDRC - International Development Research ...

International Development Research Centre (IDRC) Digital Library (Canada)

2016-11-25

Nov 25, 2016 ... Ghana's Volta River delta is an area vulnerable to climate change, with rising seas and increasingly powerful storms driving flooding and erosion, leaving authorities there questioning whether the best response involves solutions such as sea walls or migration. A group of researchers is using drones to ...

Urban Household Carbon Emission and Contributing Factors in the Yangtze River Delta, China

Science.gov (United States)

Xu, Xibao; Tan, Yan; Chen, Shuang; Yang, Guishan; Su, Weizhong

2015-01-01

Carbon reduction at the household level is an integral part of carbon mitigation. This study analyses the characteristics, effects, contributing factors and policies for urban household carbon emissions in the Yangtze River Delta of China. Primary data was collected through structured questionnaire surveys in three cities in the region – Nanjing, Ningbo, and Changzhou in 2011. The survey data was first used to estimate the magnitude of household carbon emissions in different urban contexts. It then examined how, and to what extent, each set of demographic, economic, behavioral/cognitive and spatial factors influence carbon emissions at the household level. The average of urban household carbon emissions in the region was estimated to be 5.96 tonnes CO2 in 2010. Energy consumption, daily commuting, garbage disposal and long-distance travel accounted for 51.2%, 21.3%, 16.0% and 11.5% of the total emission, respectively. Regulating rapidly growing car-holdings of urban households, stabilizing population growth, and transiting residents’ low-carbon awareness to household behavior in energy saving and other spheres of consumption in the context of rapid population aging and the growing middle income class are suggested as critical measures for carbon mitigation among urban households in the Yangtze River Delta. PMID:25884853

Occurrence of estrogenic activities in second-grade surface water and ground water in the Yangtze River Delta, China

International Nuclear Information System (INIS)

Shi, Wei; Hu, Guanjiu; Chen, Sulan; Wei, Si; Cai, Xi; Chen, Bo; Feng, Jianfang; Hu, Xinxin; Wang, Xinru; Yu, Hongxia

2013-01-01

Second-grade surface water and ground water are considered as the commonly used cleanest water in the Yangtze River Delta, which supplies centralized drinking water and contains rare species. However, some synthetic chemicals with estrogenic disrupting activities are detectable. Estrogenic activities in the second-grade surface water and ground water were surveyed by a green monkey kidney fibroblast (CV-1) cell line based ER reporter gene assay. Qualitative and quantitative analysis were further conducted to identify the responsible compounds. Estrogen receptor (ER) agonist activities were present in 7 out of 16 surface water and all the ground water samples. Huaihe River and Yangtze River posed the highest toxicity potential. The highest equivalent (2.2 ng E 2 /L) is higher than the predicted no-effect-concentration (PNEC). Bisphenol A (BPA) contributes to greater than 50% of the total derived equivalents in surface water, and the risk potential in this region deserves more attention and further research. -- Highlights: •Estrogenic activities were present in second-grade surface water and ground water. •Most of the detected equivalents were higher than the predicted no-effect-concentration of E 2 . •ER-EQ 20–80 ranges showed that samples in Huaihe River and Yangtze River posed the highest toxicity. •Bisphenol A contributes to most of the instrumentally derived equivalents in surface water. -- Estrogenic activities were observed in second-grade surface water and ground water in Yangtze River Delta, and BPA was the responsible contaminant

Vulnerability of the Nile Delta coastal areas to inundation by sea level rise.

Science.gov (United States)

Hassaan, M A; Abdrabo, M A

2013-08-01

Sea level changes are typically caused by several natural phenomena, including ocean thermal expansion, glacial melt from Greenland and Antarctica. Global average sea level is expected to rise, through the twenty-first century, according to the IPCC projections by between 0.18 and 0.59 cm. Such a rise in sea level will significantly impact coastal area of the Nile Delta, consisting generally of lowland and is densely populated areas and accommodates significant proportion of Egypt's economic activities and built-up areas. The Nile Delta has been examined in several previous studies, which worked under various hypothetical sea level rise (SLR) scenarios and provided different estimates of areas susceptible to inundation due to SLR. The paper intends, in this respect, to identify areas, as well as land use/land cover, susceptible to inundation by SLR based upon most recent scenarios of SLR, by the year 2100 using GIS. The results indicate that about 22.49, 42.18, and 49.22 % of the total area of coastal governorates of the Nile Delta would be susceptible to inundation under different scenarios of SLR. Also, it was found that 15.56 % of the total areas of the Nile Delta that would be vulnerable to inundation due to land subsidence only, even in the absence of any rise in sea level. Moreover, it was found that a considerable proportion of these areas (ranging between 32.32 and 53.66 %) are currently either wetland or undeveloped areas. Furthermore, natural and/or man-made structures, such as the banks of the International Coastal Highway, were found to provide unintended protection to some of these areas. This suggests that the inundation impact of SLR on the Nile Delta is less than previously reported.

Establishing a sediment budget in the newly created “Kleine Noordwaard” wetland area in the Rhine–Meuse delta

Directory of Open Access Journals (Sweden)

E. C. van der Deijl

2018-03-01

Full Text Available Many deltas are threatened by accelerated soil subsidence, sea-level rise, increasing river discharge, and sediment starvation. Effective delta restoration and effective river management require a thorough understanding of the mechanisms of sediment deposition, erosion, and their controls. Sediment dynamics has been studied at floodplains and marshes, but little is known about the sediment dynamics and budget of newly created wetlands. Here we take advantage of a recently opened tidal freshwater system to study both the mechanisms and controls of sediment deposition and erosion in newly created wetlands. We quantified both the magnitude and spatial patterns of sedimentation and erosion in a former polder area in which water and sediment have been reintroduced since 2008. Based on terrestrial and bathymetric elevation data, supplemented with field observations of the location and height of cut banks and the thickness of the newly deposited layer of sediment, we determined the sediment budget of the study area for the period 2008–2015. Deposition primarily took place in channels in the central part of the former polder area, whereas channels near the inlet and outlet of the area experienced considerable erosion. In the intertidal area, sand deposition especially takes place at low-lying locations close to the channels. Mud deposition typically occurs further away from the channels, but sediment is in general uniformly distributed over the intertidal area, due to the presence of topographic irregularities and micro-topographic flow paths. Marsh erosion does not significantly contribute to the total sediment budget, because wind wave formation is limited by the length of the fetch. Consecutive measurements of channel bathymetry show a decrease in erosion and deposition rates over time, but the overall results of this study indicate that the area functions as a sediment trap. The total contemporary sediment budget of the study area amounts to 35.7�

Determining the contributions of urbanisation and climate change to NPP variations over the last decade in the Yangtze River Delta, China.

Science.gov (United States)

Wu, Shaohua; Zhou, Shenglu; Chen, Dongxiang; Wei, Zongqiang; Dai, Liang; Li, Xingong

2014-02-15

Terrestrial net primary production (NPP) is an important measure of global change, and identifying the relative contributions of urbanisation and climate change to NPP is important for understanding the impact of human and natural influences on terrestrial systems and the carbon cycle. The objective of this study was to reveal how urbanisation and climate drive changes in NPP. Satellite-based estimates of NPP collected over a 12-year period (1999-2010) were analysed to identify NPP variations in the Yangtze River Delta. Temporal and spatial analysis methods were used to identify the relationships among NPP, nighttime light urbanisation index values, and climatic factors from pixel to regional scales. The NPP of the entire Yangtze River Delta decreased slightly at a rate of -0.5 g C m(-2)a(-1) from 1999 to 2010, but this change was not significant. However, in the urban region, NPP decreased significantly (pclimate change to NPP variation. The results revealed that the urbanisation factor is the main driving force for NPP change in high-speed urbanisation areas, and the factor accounted for 47% of the variations. However, in the forest and farm regions, the NPP variation was mainly controlled by climate change and residual factors. Copyright © 2013 Elsevier B.V. All rights reserved.

Identifying hotspots and management of critical ecosystem services in rapidly urbanizing Yangtze River Delta Region, China.

Science.gov (United States)

Cai, Wenbo; Gibbs, David; Zhang, Lang; Ferrier, Graham; Cai, Yongli

2017-04-15

Rapid urbanization has altered many ecosystems, causing a decline in many ecosystem services, generating serious ecological crisis. To cope with these challenges, we presented a comprehensive framework comprising five core steps for identifying and managing hotspots of critical ecosystem services in a rapid urbanizing region. This framework was applied in the case study of the Yangtze River Delta (YRD) Region. The study showed that there was large spatial heterogeneity in the hotspots of ecosystem services in the region, hotspots of supporting services and regulating services aggregately distributing in the southwest mountainous areas while hotspots of provisioning services mainly in the northeast plain, and hotspots of cultural services widespread in the waterbodies and southwest mountainous areas. The regionalization of the critical ecosystem services was made through the hotspot analysis. This study provided valuable information for environmental planning and management in a rapid urbanizing region and helped improve China's ecological redlines policy at regional scale. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simulation of the Impacts of Urbanization on Winter Meteorological Fields over the Pearl River Delta Region

Directory of Open Access Journals (Sweden)

Naixing Luo

2017-01-01

Full Text Available The influences of urbanization on weather in Guangdong Province, China, were studied using the Weather Research and Forecasting model from 31 December 2009 through 3 January 2010. Model outputs were compared with extensive monitoring of meteorological data to examine the simulation ability. Model results between tests (with and without land-use change show that the urbanization had major effects on meteorological fields across nearly the entire Pearl River Delta region and particularly in urban areas. Studied fields (wind speed, temperature, precipitation, and sensible and latent heat fluxes were affected by the urbanization of the PRD region. The major influences occurred in urban areas, where wind speeds decreased greatly, while the daytime surface upward sensible heat flux clearly increased. Unlike the sensible heat flux, the latent heat flux had a nonmonotonic increase or decrease. As a consequence of the two heat fluxes, 2-m temperature varied with location and time. Change of precipitation was complex. The main rain band became more concentrated, while precipitation decreased upwind of the urban area and increased downwind.

Remote identification of maternal polar bear (Ursus maritimus) denning habitat on the Colville River Delta, Alaska

Science.gov (United States)

Blank, Justin J.

High resolution digital aerial photographs (1 foot pixel size) of the Colville River Delta, Alaska were examined in 3D, with the use of a digital photogrammetric workstation. Topographic features meeting the criteria required for adequate snow accumulation, and subsequent construction of terrestrial polar bear maternal dens, were identified and digitized into an ArcGIS line shapefile. Effectiveness, efficiency, and accuracy were improved when compared to previous polar bear denning habitat efforts which utilized contact photo prints and a pocket stereoscope in other geographic areas of northern Alaska. Accuracy of photograph interpretation was systematically evaluated visually from the air with the use of a helicopter and physically on the ground. Results show that the mapping efforts were successful in identifying den habitat 91.3% of the time. Knowledge denning habitat can improve and inform decision making by managers and regulators when considering travel and development in the study area. An understanding of polar bear denning habitat extent and location will be a crucial tool for planning activities within the study area in a way that minimizes conflicts with maternal dens.

[Transport characteristics of air pollutants over the Yangtze Delta].

Science.gov (United States)

Wang, Yan; Chai, Fa-He; Wang, Yong-Hong; Liu, Ming

2008-05-01

Meteorological field of January, April, July and October in 2004 was obtained by running MM5 with NCEP datasets. Then we used HYSPLIT 4.8 model to calculate the backward and forward trajectories of representative cities. Distributions of trajectories and the affected areas vary with seasons. Transport current affecting Yangtze River Delta is mainly from Mongolia, North China or Northeast region, via Yellow Sea area, Shandong, Jiangsu province or Shanghai. Another important transport path is current from southwest because of the Southwest monsoon. A movement of East Asia monsoon plays an important part in the mesoscale transport of pollutants in Yangtze Delta. Winter monsoon is a main mechanism which moves the air pollutants in Yangtze Delta to South China and West Pacific ocean. Another important transport system is the subtropical anticyclone over the western Pacific Ocean which controls the east coast of our country in spring and summer. This circulation system mainly affects the inland area of our country.

Laboratory investigation on effects of flood intermittency on river delta dynamics

Science.gov (United States)

Miller, K. L.; Kim, W.

2015-12-01

In order to simplify the complex hydrological variability of flow conditions, experiments modeling delta evolution are often conducted using a representative "channel-forming" flood flow and then relate results to field settings using an intermittency factor, defined as the fraction of total time at flood conditions. Although this intermittency factor makes it easier to investigate how variables, such as relative base level and/or sediment supply, affect delta dynamics, little is known about how this generalization to a single flow condition affects delta processes. We conducted a set of laboratory experiments with periodic flow conditions to determine the effects of intermittent discharges on delta evolution. During the experiment, flood with a set water discharge and sediment supply, cycles between periods of normal flow where the water flux is halved and the sediment discharge is turned off. For each run, the magnitude of the flood is held constant, but the duration is assigned differently, thus varying the intermittency between 1 and 0.2. We find that as the intermittency factor decreases (duration of each flood period decreases), the delta topset has a larger, more elongated area with a shallower slope as a result of reworking on the delta topset during normal flow conditions. During periods of normal flow, the system adjusts towards a new equilibrium state that then in turn acts as the initial condition for the subsequent flood period. Furthermore, the natural delta avulsion cycle becomes obscured by the flood cycles as the flood duration becomes shorter than the autogenic behavior. These results suggest that the adjustment timescale for differing flow conditions is a factor in determining the overall shape of the delta and behavior of the fluviodeltaic channels. We conclude, periods of normal flow when topset sediment is reworked, may be just as important to delta dynamics as periods of flood when sediment is supplied to the system.

Organochlorine pesticides and polychlorinated biphenyls in riverine runoff of the Pearl River Delta, China: Assessment of mass loading, input source and environmental fate

International Nuclear Information System (INIS)

Guan Yufeng; Wang Jizhong; Ni Honggang; Zeng, Eddy Y.

2009-01-01

A large-scale sampling program was conducted to simultaneously collect water samples at the eight major riverine runoff outlets of the Pearl River Delta (PRD), South China to assess the importance of riverine runoff in transporting anthropogenic pollutants from terrestrial sources to the coastal ocean. The concentrations of Σ 21 OCPs (sum of 21 OCP components) and Σ 20 PCBs (sum of 20 PCB congeners) were 2.57-41.2 and 0.12-1.47 ng/L, respectively. Compositional distributions of DDTs suggested the possibility of new input sources in the study area, but contributions from dicofol seemed considerably low. The annual inputs of Σ 21 OCPs and Σ 20 PCBs were 3090 and 215 kg, with those of total HCHs and DDTs being 1110 and 1020 kg, respectively. A mass balance consideration indicated that riverine runoff is the major mode carrying OCPs from the PRD to the coastal ocean, and the majority of OCPs is further dissipated to open seas. - Mass loadings, input sources and environmental fate of organochlorine pesticides and polychlorinated biphenyls in riverine runoff of the Pearl River Delta, China are assessed

Potential plant species distribution in the Yellow River Delta under the influence of groundwater level and soil salinity

NARCIS (Netherlands)

Fan Xiaomei,; Pedroli, B.; Liu Gaohuan,; Liu Hongguang,; Song Chuangye,; Shu Longcang,

2011-01-01

This article describes a multidisciplinary approach to assessing potential vegetation types. The relation between vegetation distribution as derived from field survey and habitat characteristics in the Yellow River Delta (YRD) was analyzed using detrended canonical correspondence analysis (DCCA).

Using Fishers Knowledge in Community Based Fisheries Management in the River Nun Estuary, Niger Delta

Directory of Open Access Journals (Sweden)

Ngodigha Sabina

2018-02-01

Full Text Available A study of fishers’ knowledge in community based fisheries management practices in the Nun River estuary were conducted to assess the contribution of fishers’ knowledge to fisheries resources conservation. The total number of fishers that operated in the area were 390, and 221 fishers were interviewed based on a minimum of 10 years fishing experience using the socio-ecological approach. The laws introduced are banned on the use of mesh size less than five cm and banned on chemical fishing. Fishers caught using chemicals to fish were arrested and handed over to the police for prosecution. The management method has enhanced conservation of fisheries’ resources, which is a major source of livelihood for the people. It is therefore pertinent to introduce community based laws to check over exploitation of fisheries’ resources in fishing communities in the Niger Delta.

Linking River Basin Modifications and Rural Soil and Water Management Practices in Tropical Deltas to Sea Level Rise Vulnerability

Science.gov (United States)

Rogers, K. G.; Brondizio, E.; Roy, K.; Syvitski, J. P.

2015-12-01

The increased vulnerability of deltaic communities to coastal flooding as a result of upstream engineering has been acknowledged for decades. What has received less attention is the sensitivity of deltas to the interactions between river basin modifications and local scale cultivation and irrigation. Combined with reduced river and sediment discharge, soil and water management practices in coastal areas may exacerbate the risk of tidal flooding, erosion of arable land, and salinization of soils and groundwater associated with sea level rise. This represents a cruel irony to smallholder subsistence farmers whose priorities are food, water and economic security, rather than sustainability of the environment. Such issues challenge disciplinary approaches and require integrated social-biophysical models able to understand and diagnose these complex relationships. This study applies a new conceptual framework to define the relevant social and physical units operating on the common pool resources of climate, water and sediment in the Bengal Delta (Bangladesh). The new framework will inform development of a nested geospatial analysis and a coupled model to identify multi-scale social-biophysical feedbacks associated with smallholder soil and water management practices, coastal dynamics, basin modification, and climate vulnerability in tropical deltas. The framework was used to create household surveys for collecting data on climate perceptions, land and water management, and governance. Test surveys were administered to rural farmers in 14 villages during a reconnaissance visit to coastal Bangladesh. Initial results demonstrate complexity and heterogeneity at the local scale in both biophysical conditions and decision-making. More importantly, the results illuminate how national and geopolitical-level policies scale down to impact local-level environmental and social stability in communities already vulnerable to coastal flooding. Here, we will discuss components of the

[Distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta].

Science.gov (United States)

Dong, Hong-Fang; Yu, Jun-Bao; Guan, Bo

2013-01-01

Applying the method of physical fractionation, distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta were studied. The results showed that the heavy fraction organic carbon was the dominant component of soil organic carbon in the studied region. There was a significantly positive relationship between the content of heavy fraction organic carbon, particulate organic carbon and total soil organic carbon. The ranges of soil light fraction organic carbon ratio and content were 0.008% - 0.15% and 0.10-0.40 g x kg(-1), respectively, and the range of particulate organic carbon ratio was 8.83% - 30.58%, indicating that the non-protection component of soil organic carbon was low and the carbon pool was relatively stable in Suaeda salsa wetland of the Yellow River delta.

LiDAR data for the Delta Area of California

Data.gov (United States)

California Natural Resource Agency — LiDAR data for the Delta Area of California from the California Department of Water Resources. Bare earth grids from LiDAR.This data is in ESRI Grid format with 2...

Spatial and temporal characteristics of warm season convection over Pearl River Delta region, China, based on 3 years of operational radar data

Science.gov (United States)

Chen, Xingchao; Zhao, Kun; Xue, Ming

2014-11-01

This study examines the temporal and spatial characteristics and distributions of convection over the Pearl River Delta region of Guangzhou, China, during the May-September warm season, using, for the first time for such a purpose, 3 years of operational Doppler radar data in the region. Results show that convective features occur most frequently along the southern coast and the windward slope of the eastern mountainous area of Pearl River Delta, with the highest frequency occurring in June and the lowest in September among the 5 months. The spatial frequency distribution pattern also roughly matches the accumulated precipitation pattern. The occurrence of convection in this region also exhibits strong diurnal cycles. During May and June, the diurnal distribution is bimodal, with the maximum frequency occurring in the early afternoon and a secondary peak occurring between midnight and early morning. The secondary peak is much weaker in July, August, and September. Convection near the coast is found to occur preferentially on days when a southerly low-level jet (LLJ) exists, especially during the Meiyu season. Warm, moist, and unstable air is transported from the ocean to land by LLJs on these days, and the lifting along the coast by convergence induced by differential surface friction between the land and ocean is believed to be the primary cause for the high frequency along the coast. In contrast, the high frequency over mountainous area is believed to be due to orographic lifting of generally southerly flows during the warm season.

Spatial and Temporal Patterns of Land Loss in Mississippi River Delta

Science.gov (United States)

Roy, S.; Edmonds, D. A.; Robeson, S. M.; Ortiz, A. C.; Nienhuis, J.

2017-12-01

Land loss across the Louisiana coast is predicted to exceed 10,000 km2 by 2100. An estimated 18-24 billion tons of sediment is needed to offset land loss, but available sediment supply from the Mississippi River falls short. As a result, coastal restoration plans must target certain areas, which highlight the importance of understanding the processes and patterns of land loss. In this study, we use remote sensing to investigate and quantify land loss patterns, as well as the corresponding morphology of the land segments that are lost. Using Google Earth Engine, we combined over 10,000 time-series Landsat imagery in the Mississippi River Delta to create twelve, three-year composites from 1983 to 2016. We then spectrally unmixed each pixel into land and water percentages, and create land-water binaries. Stratifying by hydrologic unit code boundaries and local subsidence rates, we analyze the land loss pixels using landscape metrics. Our results show that the total loss from 1983-2016 for our area of interest was 908.02 km2 (loss of 5.84%) and total land area was 6855.63 km2 (49.97 % of total area) in 2016 compared to 7763.65 km2 (44.13%) in 1983 consistent with previous estimates for our study area. Land loss pixels have a low patch density (mean of 4.80 patches/ha) and high aggregation indices (mean of 47.15), which indicates that land-loss pixels tend to clump together. The shape index of these clumped pixels are also low (mean of 2.32), which points towards long, narrow patches and edges. Local indicator of spatial autocorrelation (LISA) areas was applied to determine areas of high positive autocorrelation within the loss pixels which reinforced loss across edges. Based on spatial metrics and subsidence grid based analysis on the temporal pattern of land loss pixels we find that i) land change (both growth and loss pixels) occurs along the marsh, lake and coastal edges rather than inland; ii) subsidence, though positively correlated with landloss, is no longer the

Innovation in monitoring: The U.S. Geological Survey Sacramento–San Joaquin River Delta, California, flow-station network

Science.gov (United States)

Burau, Jon; Ruhl, Cathy; Work, Paul A.

2016-01-29

The U.S. Geological Survey (USGS) installed the first gage to measure the flow of water into California’s Sacramento–San Joaquin River Delta from the Sacramento River in the late 1800s. Today, a network of 35 hydro-acoustic meters measure flow throughout the delta. This region is a critical part of California’s freshwater supply and conveyance system. With the data provided by this flow-station network—sampled every 15 minutes and updated to the web every hour—state and federal water managers make daily decisions about how much freshwater can be pumped for human use, at which locations, and when. Fish and wildlife scientists, working with water managers, also use this information to protect fish species affected by pumping and loss of habitat. The data are also used to help determine the success or failure of efforts to restore ecosystem processes in what has been called the “most managed and highly altered” watershed in the country.

Contamination characteristics and source apportionment of methylated PAHs in agricultural soils from Yangtze River Delta, China

International Nuclear Information System (INIS)

Chen, Weixiao; Wu, Xinyi; Zhang, Haiyun; Sun, Jianteng; Liu, Wenxin; Zhu, Lizhong; Li, Xiangdong; Tsang, Daniel C.W.; Tao, Shu; Wang, Xilong

2017-01-01

Alkylated PAHs (APAHs) have been shown to be more toxic and persistent than their non-alkylated parent compounds. However, little is known about the extent of soil contamination by these pollutants. To help understand agricultural soil pollution by these compounds at a regional scale, a total of 18 methylated PAHs (MPAHs, a major class of APAHs) in 243 soil samples were analyzed. These soil samples were collected from 11 sites in the Yangtze River Delta (YRD) region, a representative fast developing area in China. The total concentration of MPAHs (∑18MPAHs) ranged from 5.5 to 696.2 ng/g dry soil, with methylnaphthalenes (M-NAPs) and methylphenanthrenes (M-PHEs) accounting for more than 70% of the compositional profile. Relatively high concentrations of ∑18MPAHs were found in Jiaxing and Huzhou areas of Zhejiang province, as well as on the border between the cities of Wuxi and Suzhou. Different MPAH groups showed dissimilar spatial distribution patterns. The spatial distribution of lower molecular weight MPAHs was related to agricultural straw burning and emissions/depositions from industrial activities, whereas that of higher molecular weight MPAHs was much more a function of the total organic carbon (TOC) content of soil. Although coal, biomass (crop straw and wood), and petroleum combustion were identified to be the major emission sources for most of the sampling sites, the areas with relatively severe pollution with ∑18MPAHs resulted from the localized hotspots of petroleum leakage. Isomeric MPAHs with methyl group substituted at 2- (β) position exhibited significantly higher concentrations than those substituted at 1- (α) position. Results of this work help to understand soil pollution by MPAHs, and are useful for designing effective strategies for pollution control so as to ensure food safety in areas with fast economic growth. - Highlights: • Several 2–4 rings methyl-PAHs were investigated in soils from Yangtze River Delta. • Higher levels of �

Soil salinization processes in rice irrigation schemes in the Senegal River Delta

International Nuclear Information System (INIS)

Ceuppens, J.; Wopereis, M.C.S.; Miezan, K.M.

1997-01-01

Soil salinization constitutes a major threat to irrigated agriculture (mainly rice, Oryza sativa L.) in the Senegal River Delta. It is generally hypothesized that salinization is caused by (i) capillary rise from a saline water table and (ii) concentration of salts in the field due to lack of adequate drainage facilities. The impact of field water management and rice cropping intensity on salinization in the Delta was determined using an electromagnetic conductivity meter (Geonics EM38). More than 4000 measurements were made in 40 rice fields on a typical heavy clay soil (Vertic Xerofluvent). Thirty EM38 measurements per field (0.25 ha) estimated average field soil salinity with a relative error of 20%. A multiple linear regression model based on EM38 readings explained 60 to 75% of the variability in conductivity of 1:5 saturation extracts at 0- to 5-, 10- to 15-, and 30- to 35-cm depths. Higher cropping intensity limited upward salt transport from the water table. Average horizontal and vertical EM38 measurements increased in the following order two rice crops per year with drainage: 0.73 and 0.98 dS m -1 ; one rice crop per year with drainage: 1.26 and 1.76 dS m -1 ; one rice crop per year without drainage: 2.23 and 2.98 dS m -1 ; and abandoned fields: 4.77 and 4.29 dS m -1 . Results indicate a beneficial effect of flooded rice on salinity for this type of heavy clay soil. Irrigation development in the area needs to be accompanied by monitoring of water table depth. (author)

Supply Chain Management for Sustainable Development: Perspective from the Greater Pearl River Delta (China)

OpenAIRE

Tsoi, Joyce

2006-01-01

This thesis was submitted for the degree of Doctor of Philosophy and awarded by the University of Hong Kong. This thesis investigates the application and implications of supply chain management as a modern management model in regulating corporate outsourcing activities within the Greater Pearl River Delta. Globalisation has accelerated the application of supply chain management as a mechanism to enhance corporate performance. At the same time this rapid economic development has also accele...

A new seamless, high-resolution digital elevation model of the San Francisco Bay-Delta Estuary, California

Science.gov (United States)

Fregoso, Theresa A.; Wang, Rueen-Fang; Ateljevich, Eli; Jaffe, Bruce E.

2017-06-14

Climate change, sea-level rise, and human development have contributed to the changing geomorphology of the San Francisco Bay - Delta (Bay-Delta) Estuary system. The need to predict scenarios of change led to the development of a new seamless, high-resolution digital elevation model (DEM) of the Bay – Delta that can be used by modelers attempting to understand potential future changes to the estuary system. This report details the three phases of the creation of this DEM. The first phase took a bathymetric-only DEM created in 2005 by the U.S. Geological Survey (USGS), refined it with additional data, and identified areas that would benefit from new surveys. The second phase began a USGS collaboration with the California Department of Water Resources (DWR) that updated a 2012 DWR seamless bathymetric/topographic DEM of the Bay-Delta with input from the USGS and modifications to fit the specific needs of USGS modelers. The third phase took the work from phase 2 and expanded the coverage area in the north to include the Yolo Bypass up to the Fremont Weir, the Sacramento River up to Knights Landing, and the American River up to the Nimbus Dam, and added back in the elevations for interior islands. The constant evolution of the Bay-Delta will require continuous updates to the DEM of the Delta, and there still are areas with older data that would benefit from modern surveys. As a result, DWR plans to continue updating the DEM.

The Effect of Urban Heat Island on Climate Warming in the Yangtze River Delta Urban Agglomeration in China

Directory of Open Access Journals (Sweden)

Qunfang Huang

2015-07-01

Full Text Available The Yangtze River Delta (YRD has experienced rapid urbanization and dramatic economic development since 1978 and the Yangtze River Delta urban agglomeration (YRDUA has been one of the three largest urban agglomerations in China. We present evidence of a significant urban heat island (UHI effect on climate warming based on an analysis of the impacts of the urbanization rate, urban population, and land use changes on the warming rate of the daily average, minimal (nighttime and maximal (daytime air temperature in the YRDUA using 41 meteorological stations observation data. The effect of the UHI on climate warming shows a large spatial variability. The average warming rates of average air temperature of huge cities, megalopolises, large cities, medium-sized cities, and small cities are 0.483, 0.314 ± 0.030, 0.282 ± 0.042, 0.225 ± 0.044 and 0.179 ± 0.046 °C/decade during the period of 1957–2013, respectively. The average warming rates of huge cities and megalopolises are significantly higher than those of medium-sized cities and small cities, indicating that the UHI has a significant effect on climate warming (t-test, p < 0.05. Significantly positive correlations are found between the urbanization rate, population, built-up area and warming rate of average air temperature (p < 0.001. The average warming rate of average air temperature attributable to urbanization is 0.124 ± 0.074 °C/decade in the YRDUA. Urbanization has a measurable effect on the observed climate warming in the YRD aggravating the global climate warming.

Geomorphic change in the Limitrophe reach of the Colorado River in response to the 2014 delta pulse flow, United States and Mexico

Science.gov (United States)

Mueller, Erich R.; Schmidt, John C.; Topping, David; Grams, Paul E.

2015-01-01

A pulse of water was released from Morelos Dam into the dry streambed of the Colorado River in its former delta on March 23, 2014. Although small in relation to delta floods of a century ago, this was the first flow to reach the sea in nearly two decades. The pulse flow was significant in that it resulted from an international agreement, Minute 319, which allowed Colorado River water to be used for environmental restoration. Here we present a historical perspective of channel change and the results of geomorphic and sediment transport monitoring during the pulse flow between Yuma, Arizona and San Luis Rio Colorado, Sonora. This reach is known as the Limitrophe, because the river channel is the legal border between the United States and Mexico. Peak discharge of the pulse flow was 120 m3/s at Morelos Dam, but decreased to 71 m3/s at the southern border because of infiltration losses to the dry streambed. In contrast, flood flows in the 1980s and 1990s peaked above 600 m3/s at the southern border, and high flows above 200 m3/s were common. The sustained high flows in the 1980s caused widening and reworking of the river channel downstream through the delta. In the Limitrophe, flooding in 1993 from the Gila River basin dissected the 1980s flood surfaces, and smaller floods in the late 1990s incised the modern “active” channel within these higher surfaces. Field observations show that most geomorphic change during the pulse flow was confined to this pre-pulse, active channel. Relatively little bank erosion was evident, particularly in upstream reaches where vegetation is most dense, but new sandbars formed in areas of flow expansion. Farther downstream, localized bed scour and deposition ranged from 10s of centimeters to more than a meter, and fluvial dunes aggraded the bed in several locations. Measurable suspended-sediment transport occurred throughout the Limitrophe. Sediment concentrations peaked during the rising limb, and suspended sand concentrations suggest

Analysis of macrobenthic assemblages and ecological health of Yellow River Delta, China, using AMBI & M-AMBI assessment method

NARCIS (Netherlands)

Li, B.; Li, X.; Bouma, T.J.; Soissons, L.M.; Cozzoli, F.; Wang, Q.; Zhou, Z.; Chen, L.

2017-01-01

Yellow River delta (YRD) is a typical example of a valuable coastal ecosystem that is under increasing anthropogenic threat in China. To understand the current health status of this region, three surveys in 2011 for the abiotic conditions and macrobenthic assemblages were performed. The

Implementation of Ecological Policies in Danube Delta Area

Directory of Open Access Journals (Sweden)

Trifon Belacurencu

2007-04-01

Full Text Available Public authorities and the local community have become lately increasingly aware of the complex relationship between the environment and the economic activity and of the need for integrating environmental requirements into economic activities. Therefore, a strategy that aims at a sustained development which takes into account the environmental aspects is imperative. Environmental policies represent a set of measures and tools with the objective of controlling and limiting the process of deterioration of environment quality. The design of environmental policies for the Danube Delta is not an easy task, due primarily to the major changes that affect the deltaic ecosystem, the patterns of behavior and consumption, poverty and isolation of the local communities, etc. The environmental policies in the Danube Delta have no longer an auxiliary role, rather reactive, but instead they are meant to set objectives at the economic, legal, educational and social levels and to guide the strategy for their achievement. In this paper I have outlined both the objectives of the environmental policies and the types of measures (general, direct and indirect for their implementation in the area of the Danube Delta.

Isotopic composition of Danube water in the pre-delta section from the years 2009 - 2012

Directory of Open Access Journals (Sweden)

RANK Dieter

2013-12-01

Full Text Available The isotopic composition of river water in the Danube Basin is mainly governed by the isotopic composition of precipitation in the catchment area, evaporation effects play only a minor role. Short-term and long-term isotope signals from precipitation are thus transmitted through the whole catchment. The isotopic composition of Danube water in the Delta region so provides an integrated isotope signal for climatic/hydrological conditions and changes in the whole catchment. The aim of this investigation was to establish a representative isotope monitoring near the Danube Delta. The results showed that the Danube River is regarding isotope content fully mixed at the bifurcation of the Danube Delta arms. Therefore routine sampling at only one location in the pre-delta region should be sufficient to obtain a representative isotope record for the whole Danube Basin. The δ 18 O time series from November 2009 to May 2012 (sampling twice a month shows seasonal variations in the range of -9.8 ‰ ± 0.7 ‰ with a minimum in spring and a maximum in autumn. The tritium results exhibit the influence of short term contaminations due to human activities. The expected “environmental” tritium content of river water in Central Europe would be about 10 TU. During this investigation 3 H values up to 100 TU were observed in the pre-delta section. This indicates short terms releases of tritium from local sources such as nuclear power plants in the Danube river system.

Benthic sediment data from eleven stations in the Mobile-Tensaw River Delta, Alabama on 17 June 1981 (NODC Accession 0118497)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic sediment samples were collected from eleven stations in the Mobile-Tensaw River Delta on 17 June 1981. Samples were analyzed for particle size distribution...

Hydrodynamic modelling of a tidal delta wetland using an enhanced quasi-2D model

Science.gov (United States)

Wester, Sjoerd J.; Grimson, Rafael; Minotti, Priscilla G.; Booija, Martijn J.; Brugnach, Marcela

2018-04-01

Knowledge about the hydrological regime of wetlands is key to understand their physical and biological properties. Modelling hydrological and hydrodynamic processes within a wetland is therefore becoming increasingly important. 3D models have successfully modelled wetland dynamics but depend on very detailed bathymetry and land topography. Many 1D and 2D models of river deltas highly simplify the interaction between the river and wetland area or simply neglect the wetland area. This study proposes an enhanced quasi-2D modelling strategy that captures the interaction between river discharge and moon tides and the resulting hydrodynamics, while using the scarce data available. The water flow equations are discretised with an interconnected irregular cell scheme, in which a simplification of the 1D Saint-Venant equations is used to define the water flow between cells. The spatial structure of wetlands is based on the ecogeomorphology in complex estuarine deltas. The islands within the delta are modelled with levee cells, creek cells and an interior cell representing a shallow marsh wetland. The model is calibrated for an average year and the model performance is evaluated for another average year and additionally an extreme dry three-month period and an extreme wet three-month period. The calibration and evaluation are done based on two water level measurement stations and two discharge measurement stations, all located in the main rivers. Additional calibration is carried out with field water level measurements in a wetland area. Accurate simulations are obtained for both calibration and evaluation with high correlations between observed and simulated water levels and simulated discharges in the same order of magnitude as observed discharges. Calibration against field measurements showed that the model can successfully simulate the overflow mechanism in wetland areas. A sensitivity analysis for several wetland parameters showed that these parameters are all

Sediment-hosted contaminants and distribution patterns in the Mississippi and Atchafalaya River Deltas

Science.gov (United States)

Flocks, James G.; Kindinger, Jack G.; Ferina, Nicholas; Dreher, Chandra

2002-01-01

The Mississippi and Atchafalaya Rivers transport very large amounts of bedload and suspended sediments to the deltaic and coastal environments of the northern Gulf of Mexico. Absorbed onto these sediments are contaminants that may be detrimental to the environment. To adequately assess the impact of these contaminants it is first necessary to develop an understanding of sediment distribution patterns in these deltaic systems. The distribution patterns are defined by deltaic progradational cycles. Once these patterns are identified, the natural and industrial contaminant inventories and their depositional histories can be reconstructed. Delta progradation is a function of sediment discharge, as well as channel and receiving-basin dimensions. Fluvial energy controls the sediment distribution pattern, resulting in a coarse grained or sandy framework, infilled with finer grained material occupying the overbank, interdistributary bays, wetlands and abandoned channels. It has been shown that these fine-grained sediments can carry contaminants through absorption and intern them in the sediment column or redistribute them depending on progradation or degradation of the delta deposit. Sediment distribution patterns in delta complexes can be determined through high-resolution geophysical surveys and groundtruthed with direct sampling. In the Atchafalaya and Mississippi deltas, remote sensing using High-Resolution Single-Channel Seismic Profiling (HRSP) and Sidescan Sonar was correlated to 20-ft vibracores to develop a near-surface geologic framework that identifies variability in recent sediment distribution patterns. The surveys identified bedload sand waves, abandoned-channel back-fill, prodelta and distributary mouth bars within the most recently active portions of the deltas. These depositional features respond to changes in deltaic processes and through their response may intern or transport absorbed contaminants. Characterizing these features provides insight into the

An ozone episode over the Pearl River Delta in October 2008

Science.gov (United States)

Shen, Jin; Zhang, Yuanhang; Wang, Xuesong; Li, Jinfeng; Chen, Hao; Liu, Run; Zhong, Liuju; Jiang, Ming; Yue, Dingli; Chen, Duohong; Lv, Wei

2015-12-01

The north and east Pearl River Delta (PRD) is usually a clean, upwind area in autumn. Serious ozone pollution there in mid-late October 2008 was first discovered and then analyzed. Trajectory analysis, process analysis, ozone source apportionment technology, and sensitivity analysis were used to study this episode. Under the influence of a weak south wind, the precursors emitted in Guangzhou and Foshan were transported to the north and northeast PRD and formed ozone there, which resulted in high ozone concentration (>100 ppb). As the wind direction later transited to northerly, the precursors in the northeast PRD that originated from the central and west PRD were transported to the south, and caused severe ozone pollution in the southeast PRD. The ozone contributed by chemical processes reached >20 ppb/h in Jinguowan. More than 40 ppb ozone was contributed by the precursor emission in the central and west PRD during the episode. The ozone concentration was highly sensitive to the precursor emission in the PRD region in the high-ozone situations. This episode showed the complexity of regional pollution in the PRD. When the PRD is controlled by a low air pressure system and then cold air moves from northern China to the south, the risk of ozone pollution in the north and southeast PRD increases.

Permafrost Organic Carbon Mobilization From the Watershed to the Colville River Delta: Evidence From 14C Ramped Pyrolysis and Lignin Biomarkers

Science.gov (United States)

Zhang, Xiaowen; Bianchi, Thomas S.; Cui, Xingqian; Rosenheim, Brad E.; Ping, Chien-Lu; Hanna, Andrea J. M.; Kanevskiy, Mikhail; Schreiner, Kathryn M.; Allison, Mead A.

2017-11-01

The deposition of terrestrial-derived permafrost particulate organic carbon (POC) has been recorded in major Arctic river deltas. However, associated transport pathways of permafrost POC from the watershed to the coast have not been well constrained. Here we utilized a combination of ramped pyrolysis-oxidation radiocarbon analysis (RPO 14C) along with lignin biomarkers, to track the linkages between soils and river and delta sediments. Surface and deep soils showed distinct RPO thermographs which may be related to degradation and organo-mineral interaction. Soil material in the bed load of the river channel was mostly derived from deep old permafrost. Both surface and deep soils were transported and deposited to the coast. Hydrodynamic sorting and barrier island protection played important roles in terrestrial-derived permafrost POC deposition near the coast. On a large scale, ice processes (e.g., ice gauging and strudel scour) and ocean currents controlled the transport and distribution of permafrost POC on the Beaufort Shelf.

Report on technological achievements in fiscal 1999. Survey on geological structures in overseas countries, 'Japan-Vietnam joint coal exploration project on Red River delta'; 1999 nendo kaigai chishitsu kozo nado chosa hokokusho. Nippon Vietnam sekitan kyodo tansa Red River delta project

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-06-01

With an objective to identify stratigraphy, geological structures, coal bed existing status, and coal quality of major coal beds in the north and central district of the area to be surveyed in the Red River delta, test well drilling, physical and seismic exploration, and coal composition analyses were performed. The area to be surveys is a typical delta where irrigation canals are running in all directions. Three test wells were drilled with drilling lengths of 640 m for TD3, 700 m for TD4 and 900 m for TD5. Coring was performed to depths greater than the Tertiary deposit. The seismic exploration was executed along three exploration lines. Total distance was 25 km. In addition, the VSP investigation was carried out on TD3 and TD5. The stratigraphy is composed from below of the Phu Cu bed (Neogene period: marine deposit) , the Tien Hung bed (Neogene period: continental deposit), and the Tai Doung bed (quaternary deposit), in which the bed that holds coal beds is the Tien Hung bed. The beds are very stable as the geological structure, but the constituting rocks are soft and fragile. Anticipated coal beds exist in depths greater than 1000 m. The coal quality is of low ash, low sulfur, medium in calorific power, and contains little gas. (NEDO)

Delta Evolution at Røde Elv, Disko Island, Greenland

Science.gov (United States)

Kroon, A.; Arngrimson, J.; Bendixen, M.; Sigsgaard, C.

2017-12-01

Ice, snow and freezing temperatures have a large impact on coastal morphodynamics in Arctic polar environments. A recent warming of the Arctic climate induces many changes along the arctic shorelines. Sea-levels are rising due to thermal expansion and due to an increased fresh water flux from the glaciers and land ice masses. At the same time, the ice coverage of the coastal waters reduces and the open water periods in summer extend. There is a strong seasonal variation with open waters and active rivers in summer and ice-covered coastal waters and inactive rivers in winter. Coastal processes by waves and tides are thus limited to the summer and early fall. Besides, there is also a strong daily variation in fluvial discharges due to the daily variations in glacier melt with maximum melt in the afternoon and minimum values at night. At the same time, the actual flux of the river to the coastal bay is influenced by the tidal phase. Low tides will enhance the transport to the delta front, while high tides will create stagnant waters over the delta plain. The delta of the Røde Elv is located in southwestern Disko Island in west Greenland. It has a relatively small (ca. 101 km2) and partly glaciated drainage basin (ca. 20%) and its sediments consist of a mixture of basaltic sands and gravels. The Røde Elv delta is located at the end of a pro-glacial and fluvial valley at about 20 km from the glacier. The shores of the delta are reworked by waves, predominantly from southwestern, southern (largest fetch, over 50 km), and southeastern directions. The environment has a micro- to meso- tidal range with a spring tidal range of 2.7 m. The morphologic changes on the delta over the last decades clearly showed a seaward extension of the delta and a periodic shift in the location of the main delta channel. In this presentation, we focus on quantification of water discharges and suspended sediment fluxes to the Røde Elv delta in western Greenland, and on the morphological

The Central Role of the Mississippi River and its Delta in the Oceanography, Ecology and Economy of the Gulf of Mexico: A Synthesis

Science.gov (United States)

Kolker, A.; Chu, P. Y.; Taylor, C.; Roberts, B. J.; Renfro, A. A.; Peyronnin, N.; Fitzpatrick, C.

2017-12-01

While it has long been recognized that the Mississippi River is the largest source of freshwater, nutrients and sediments to the Gulf of Mexico, many questions remain unanswered about the impacts of the material on oceanography of the system. Here we report on the results of a regional synthesis study that examined how the Mississippi River and its delta influence the oceanography, ecology and the economy of the Gulf of Mexico. By employing a series of expert-opinion working groups, and using multi-dimensional numerical physical oceanographic models coupled to in-situ environmental data, this project is working to quantify how variability in discharge, meteorological forcings, and seasonal conditions influence the spatial distribution of the Mississippi River plume and its influence. Results collected to date indicate that the dimensions of the river plume are closely coupled to discharge, but in a non-linear fashion, that incorporates fluxes, flow distributions, offshore and meteorological forcings in the context of the local bathymetry. Ongoing research is using these human and numerical tools to help further elucidate the impacts of this river on the biogeochemistry of the region, and the distribution of key macrofauna. Further work by this team is examining how the delta's impacts on the ecology of the region, and the role that the delta plays as both a source of material for key offshore fauna, and a barrier to dispersal. This information is being used to help further the development of a research agenda for the northern Gulf of Mexico that will be useful through the mid-21st century.

Container cargo simulation modeling for measuring impacts of infrastructure investment projects in Pearl River Delta

Science.gov (United States)

Li, Jia-Qi; Shibasaki, Ryuichi; Li, Bo-Wei

2010-03-01

In the Pearl River Delta (PRD), there is severe competition between container ports, particularly those in Hong Kong, Shenzhen, and Guangzhou, for collecting international maritime container cargo. In addition, the second phase of the Nansha terminal in Guangzhou’s port and the first phase of the Da Chang Bay container terminal in Shenzhen opened last year. Under these circumstances, there is an increasing need to quantitatively measure the impact these infrastructure investments have on regional cargo flows. The analysis should include the effects of container terminal construction, berth deepening, and access road construction. The authors have been developing a model for international cargo simulation (MICS) which can simulate the movement of cargo. The volume of origin-destination (OD) container cargo in the East Asian region was used as an input, in order to evaluate the effects of international freight transportation policies. This paper focuses on the PRD area and, by incorporating a more detailed network, evaluates the impact of several infrastructure investment projects on freight movement.

River capture and sediment redistribution in northern Tunisia: The doom of Utica

Science.gov (United States)

Booth-Rea, Guillermo; Camafort, Miquel; Pérez-Peña, J. Vicente; Melki, Fetheddine; Ranero, César; Azañón, José Miguel; Gracia, Eulalia; Ouadday, Mohamed

2016-04-01

Utica was a flourishing port city in northern Tunisia since the Phoenician times, 12-9th century B.C., until the 4th century A.D.. However, at present it is located 10 km from the coastline after very fast late Holocene progradation of the Mejerda River delta into the bay of Utica. This fast delta progradation occurred after Mejerda River captured Tine River increasing 140 % the river catchment area. Charcoal fragments present in the youngest Tine river terrace at the wind gap give a conventional radiocarbon age of 3240 +/- 30yr BP, indicating that the capture occurred after this date. Quaternary fluvial terraces located in the Tine River paleovalley have been folded and uplifted above a fold related to the active El Alia Tebousouk reverse fault (ETF). Continued uplift of the Tine River valley above the ETF favoured headward erosion of the Medjerda river tributaries creating a transverse drainage that captured Tine River. This capture produced an important change in sediment discharge along the northern Tunisia coast driving sediments to the Gulf of Tunis instead of feeding the Tyrrhenian Sea through the Ichkeul and Bizerte lakes. Although anthropogenic derived degradation of northern Tunisia land for agricultural purposes probably influenced the increase in sediment into the Utica bay, the main cause of rapid progradation of the Medjerda River delta during the late Holocene is related to its increase in drainage area after capturing the Tine River. This process was mostly driven by local contractive tectonics linked to the seismogenic Alia Tebousouk reverse fault.

Effects of the proposed California WaterFix North Delta Diversion on flow reversals and entrainment of juvenile Chinook salmon (Oncorhynchus tshawytscha) into Georgiana Slough and the Delta Cross Channel, northern California

Science.gov (United States)

Perry, Russell W.; Romine, Jason G.; Pope, Adam C.; Evans, Scott D.

2018-02-27

The California Department of Water Resources and Bureau of Reclamation propose new water intake facilities on the Sacramento River in northern California that would convey some of the water for export to areas south of the Sacramento-San Joaquin River Delta (hereinafter referred to as the Delta) through tunnels rather than through the Delta. The collection of water intakes, tunnels, pumping facilities, associated structures, and proposed operations are collectively referred to as California WaterFix. The water intake facilities, hereinafter referred to as the North Delta Diversion (NDD), are proposed to be located on the Sacramento River downstream of the city of Sacramento and upstream of the first major river junction where Sutter Slough branches from the Sacramento River. The NDD can divert a maximum discharge of 9,000 cubic feet per second (ft3/s) from the Sacramento River, which reduces the amount of Sacramento River inflow into the Delta.In this report, we conducted three analyses to investigate the effect of the NDD and its proposed operation on entrainment of juvenile Chinook salmon (Oncorhynchus tshawytscha) into Georgiana Slough and the Delta Cross Channel (DCC). Fish that enter the interior Delta (the network of channels to the south of the Sacramento River) through Georgiana Slough and the DCC survive at lower rates than fish that use other migration routes (Sacramento River, Sutter Slough, and Steamboat Slough). Therefore, fisheries managers were concerned about the extent to which operation of the NDD would increase the proportion of the population entering the interior Delta, which, all else being equal, would lower overall survival through the Delta by increasing the fraction of the population subject to lower survival rates. Operation of the NDD would reduce flow in the Sacramento River, which has the potential to increase the magnitude and duration of reverse flows of the Sacramento River downstream of Georgiana Slough.In the first analysis, we

Long-term trend of haze pollution and impact of particulate matter in the Yangtze River Delta, China

International Nuclear Information System (INIS)

Cheng, Zhen; Wang, Shuxiao; Jiang, Jingkun; Fu, Qingyan; Chen, Changhong; Xu, Bingye; Yu, Jianqiao; Fu, Xiao; Hao, Jiming

2013-01-01

Haze pollution caused by heavy particulate matter (PM) loading brings significant damage in eastern China. Long-term monitoring from 1980 to 2011 and 1-year field measurement in 2011–2012 are used for investigating visibility variation and the impact of PM pollution for the Yangtze River Delta (YRD). It was found that visual range in the YRD endured a sharp reduction from 13.2 km to 10.5 km during 1980–2000. Average mass extinction efficiency (MEE) for inhalable PM (PM 10 ) is 2.25 m 2 /g in 2001–2011, and extinction coefficient due to PM 10 is 207 Mm −1 , accounting for 36.2% of total extinction coefficient. MEE of PM 2.5 and PM 2.5–10 are 4.08 m 2 /g and 0.58 m 2 /g, respectively. Extinction coefficient due to PM 2.5 and PM 2.5–10 is 198 Mm −1 (39.6%) and 20 Mm −1 (4.0%) in 2011–2012. Maximum daily concentration of PM 10 and PM 2.5 is estimated to be 63 μg/m 3 (RH: 73%) and 38 μg/m 3 (RH: 70%) to keep visual range above 10 km. Fine particulate matter is the key factor for haze pollution improvement in the YRD area. -- Highlights: •Long-term visual range variation and its causes in the Yangtze River Delta are analyzed. •Quantitative contribution of particulate matter to haze pollution is estimated. •Mass extinction efficiency of PM 10 , PM 2.5 , and PM 2.5–10 is estimated. -- The long-term variation of haze pollution in the YRD and its cause is investigated and the quantitative contribution of particulate matter to haze pollution is estimated

Shoreline dynamics of the active Yellow River delta since the implementation of Water-Sediment Regulation Scheme: A remote-sensing and statistics-based approach

Science.gov (United States)

Fan, Yaoshen; Chen, Shenliang; Zhao, Bo; Pan, Shunqi; Jiang, Chao; Ji, Hongyu

2018-01-01

The Active Yellow River (Huanghe) Delta (AYRD) is a complex landform in which rapid deposition takes place due to its geologic formation and evolution. Continuous monitoring of shoreline dynamics at high-temporal frequency is crucial for understanding the processes and the driving factors behind this rapidly changing coast. Great efforts have been devoted to map the changing shoreline of the Yellow River delta and explain such changes through remote sensing data. However, the temporal frequency of shoreline in the obtained datasets are generally not fine enough to reflect the detailed or subtly variable processes of shoreline retreat and advance. To overcome these limitations, we continuously monitored the dynamics of this shoreline using time series of Landsat data based on tidal-level calibration model and orthogonal-transect method. The Abrupt Change Value (ACV) results indicated that the retreat-advance patterns had a significant impact regardless of season or year. The Water-Sediment Regulation Scheme (WSRS) plays a dominant role in delivering river sediment discharge to the sea and has an impact on the annual average maximum ACV, especially at the mouth of the river. The positive relationship among the average ACV, runoff and sediment load are relatively obvious; however, we found that the Relative Exposure Index (REI) that measures wave energy was able to explain only approximately 20% of the variation in the data. Based on the abrupt change at the shoreline of the AYRD, river flow and time, we developed a binary regression model to calculate the critical sediment load and water discharge for maintaining the equilibrium of the active delta from 2002 to 2015. These values were approximately 0.48 × 108 t/yr and 144.37 × 108 m3/yr. If the current water and sediment proportions released from the Xiaolangdi Reservoir during the WSRS remain stable, the erosion-accretion patterns of the active delta will shift from rapid accretion to a dynamic balance.

Environmental Degradation in Oil Producing Areas of Niger Delta ...

African Journals Online (AJOL)

Due to oil exploration and other human activities in the Niger Delta region, there is evidence of environmental degradation all over the area (Oronto, 1998). Environmental degradation is occasioned by consistent flow of industrial waste, oil spills, gas flares, fire disaster, acid rain, flooding erosion, etc., which has led to the ...

Role of photoexcited nitrogen dioxide chemistry on ozone formation and emission control strategy over the Pearl River Delta, China

Science.gov (United States)

A new hydroxyl radical formation pathway via photo-excited nitrogen dioxide chemistry is incorporated into a chemistry-only box model as well as a 3D air quality model to examine its potential role on ozone formation and emission control strategy over the Pearl River Delta region...

DELTAS: A new Global Delta Sustainability Initiative (Invited)

Science.gov (United States)

Foufoula-Georgiou, E.

2013-12-01

Deltas are economic and environmental hotspots, food baskets for many nations, home to a large part of the world population, and hosts of exceptional biodiversity and rich ecosystems. Deltas, being at the land-water interface, are international, regional, and local transport hubs, thus providing the basis for intense economic activities. Yet, deltas are deteriorating at an alarming rate as 'victims' of human actions (e.g. water and sediment reduction due to upstream basin development), climatic impacts (e.g. sea level rise and flooding from rivers and intense tropical storms), and local exploration (e.g. sand or aggregates, groundwater and hydrocarbon extraction). Although many efforts exist on individual deltas around the world, a comprehensive global delta sustainability initiative that promotes awareness, science integration, data and knowledge sharing, and development of decision support tools for an effective dialogue between scientists, managers and policy makers is lacking. Recently, the international scientific community proposed to establish the International Year of Deltas (IYD) to serve as the beginning of such a Global Delta Sustainability Initiative. The IYD was proposed as a year to: (1) increase awareness and attention to the value and vulnerability of deltas worldwide; (2) promote and enhance international and regional cooperation at the scientific, policy, and stakeholder level; and (3) serve as a launching pad for a 10-year committed effort to understand deltas as complex socio-ecological systems and ensure preparedness in protecting and restoring them in a rapidly changing environment. In this talk, the vision for such an international coordinated effort on delta sustainability will be presented as developed by a large number of international experts and recently funded through the Belmont Forum International Opportunities Fund. Participating countries include: U.S., France, Germany, U.K., India, Japan, Netherlands, Norway, Brazil, Bangladesh

Delta progradation in Greenland driven by increasing glacial mass loss

DEFF Research Database (Denmark)

Bendixen, Mette; Iversen, Lars Lonsmann; Bjork, Anders Anker

2017-01-01

imagery. We find that delta progradation was driven by high freshwater runoff from the Greenland Ice Sheet coinciding with periods of open water. Progradation was controlled by the local initial environmental conditions (that is, accumulated air temperatures above 0 degrees C per year, freshwater runoff...... of erosion and accretion along the large deltas of the main rivers in the Arctic5-7. Our results improve the understanding of Arctic coastal evolution in a changing climate, and reveal the impacts on coastal areas of increasing ice mass loss and the associated freshwater runoff and lengthening of open-water...

[Seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value in rainwater in Yangtze River Delta].

Science.gov (United States)

Xie, Ying-Xin; Zhang, Shu-Li; Zhao, Xu; Xiong, Zheng-Qin; Xing, Guang-Xi

2008-09-01

By using a customized manual rainwater sampler made of polyvinyl chloride plastic, the molar ratio of NH4(+) -N/NO3(-) -N and the natural 15N abundance of NH4(+) (delta 15 NH4(+) in rainwater was monitored all year round from June 2003 to July 2005 at three observation sites (Changshu, Nanjing, and Hangzhou) in the Yangtze River Delta. The results indicated that at the three sites, the NH4(+) -N/NO3(-) -N ratio and the delta 15 NH4(+) value in rainwater had the similar seasonal variation trend, being more obvious in Changshu (rural monitoring type) site than in Nanjing (urban monitoring type) and Hangzhou (urban-rural monitoring type) sites. The NH4(+) -N/NO3(-) -N ratio peaked from early June to early August, declined gradually afterwards, and reached the bottom in winter; while the delta 15 NH4(+) value was negative from late June to mid-August, turned positive from late August to mid or late November, became negative again when winter dominated from December to March, but turned positive again in next May and negative again in next July. These seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value were found in relation to the application of chemical nitrogen fertilizers during different crop growth periods, and also, the alternation of seasons and the NH3 volatilization from other NH3 emission sources (including excrements of human and animals, nitrogen- polluted water bodies, and organic nitrogen sources, etc.), which could be taken as an indicator of defining the sources and form composition of NH4(+) in atmospheric wet deposition and the intensity of various terrestrial NH3 emission sources.

New High-Resolution Multibeam Mapping and Seismic Reflection Imaging of Mudflows on the Mississippi River Delta Front

Science.gov (United States)

Chaytor, J. D.; Baldwin, W. E.; Danforth, W. W.; Bentley, S. J.; Miner, M. D.; Damour, M.

2017-12-01

Mudflows (channelized and unconfined debris flows) on the Mississippi River Delta Front (MRDF) are a recognized hazard to oil and gas infrastructure in the shallow Gulf of Mexico. Preconditioning of the seafloor for failure results from high sedimentation rates coupled with slope over-steepening, under-consolidation, and abundant biogenic gas production. Cyclical loading of the seafloor by waves from passing major storms appears to be a primary trigger, but the role of smaller (more frequent) storms and background oceanographic processes are largely unconstrained. A pilot high-resolution seafloor mapping and seismic imaging study was carried out across portions of the MRDF aboard the R/V Point Sur from May 19-26, 2017, as part of a multi-agency/university effort to characterize mudflow hazards in the area. The primary objective of the cruise was to assess the suitability of seafloor mapping and shallow sub-surface imaging tools in the challenging environmental conditions found across delta fronts (e.g., variably-distributed water column stratification and wide-spread biogenic gas in the shallow sub-surface). More than 600 km of multibeam bathymetry/backscatter/water column data, 425 km of towed chirp data, and > 500 km of multi-channel seismic data (boomer/mini-sparker sources, 32-channel streamer) were collected. Varied mudflow (gully, lobe), pro-delta morphologies, and structural features, some of which have been surveyed more than once, were imaged in selected survey areas from Pass a Loutre to Southwest Pass. The present location of the SS Virginia, which has been moving with one of the mudflow lobes since it was sunk in 1942, was determined and found to be 60 m SW of its 2006 position, suggesting movement not linked to hurricane-induced wave triggering of mudflows. Preliminary versions these data were used to identify sediment sampling sites visited on a cruise in early June 2017 led by scientists from LSU and other university/agency partners.

Impact of water diversion on the hydrogeochemical characterization of surface water and groundwater in the Yellow River Delta

International Nuclear Information System (INIS)

Liu, Qiang; Li, Fadong; Zhang, Qiuying; Li, Jing; Zhang, Yan; Tu, Chun; Ouyang, Zhu

2014-01-01

Highlights: • We assess the response of different ecosystems to the water diversion. • We characterized the interaction between surface water and groundwater. • We use the Piper and HFE-D to illustrate the salinization process. - Abstract: The Yellow River Delta is undergoing severe ecosystem degradation through salinization caused mainly by seawater intrusion. The Yellow River diversion project, in operation since 2008, aims to mitigate a projected ecosystem disaster. We conducted field investigations across three ecosystems (Farmland, Wetland and Coast) in the delta to assess the effectiveness of the annual water pulse and determine the relationships between surface water and groundwater. The chemical characteristics of the groundwater in Farmland exclude the possibility of seawater intrusion. The Wetland is vulnerable to pollution by groundwater discharge from Farmland and to secondary salinization caused by rising water tables. The salinity values of groundwater at Coast sites likely reflect the presence of seawater trapped in the clay sediments, a premise corroborated through measurements of groundwater levels, stable isotopes and major ion signatures. Our δD–δ 18 O two-dimensional graphic plot demonstrated that groundwaters of Farmland and Wetland changed toward more depleted isotopic compositions following water diversion, but this was not the case in the Coast sites, where the water table varied little year-round. A hydrochemical facies evolution diagram (HFE-D) demonstrated that freshening is taking place in the largest portions of the aquifers and that, without sustained water diversion recharge, these underground water bodies may switch from freshening to salinization on a seasonal time scale. Thus, the qualities of waters in coastal aquifers in the Yellow River Delta are substantially influenced by the process of ecological water diversion, and also by land use practices and by the lithological properties of the drainage landscape

Recent Advances in Understanding Flow Dynamics and Transport of Water-Quality Constituents in the Sacramento–San Joaquin River Delta

Directory of Open Access Journals (Sweden)

David H. Schoellhamer

2016-12-01

Full Text Available doi: https://doi.org/10.15447/sfews.2016v14iss4art1This paper, part of the collection of research comprising the State of Bay–Delta Science 2016, describes advances during the past decade in understanding flow dynamics and how water-quality constituents move within California’s Sacramento–San Joaquin River Delta (Delta. Water-quality constituents include salinity, heat, oxygen, nutrients, contaminants, organic particles, and inorganic particles. These constituents are affected by water diversions and other human manipulations of flow, and they greatly affect the quantity and quality of benthic, pelagic, and intertidal habitat in the Delta. The Pacific Ocean, the Central Valley watershed, human intervention, the atmosphere, and internal biogeochemical processes are all drivers of flow and transport in the Delta. These drivers provide a conceptual framework for presenting recent findings. The tremendous expansion of acoustic and optical instruments deployed in the Delta over the past decade has greatly improved our understanding of how tidal variability affects flow and transport. Sediment is increasingly viewed as a diminishing resource needed to sustain pelagic habitat and tidal marsh, especially as sea level rises. Connections among the watershed, Delta, and San Francisco Bay that have been quantified recently highlight that a landscape view of this system is needed, rather than consideration of each region in isolation. We discuss interactions of multiple drivers and information gaps.

A Bio-economic Model of a Shrimp Hatchery in the Mekong River Delta of Vietnam

OpenAIRE

Sinh, L.X.; MacAulay, T. Gordon; Brennan, Donna C.

2003-01-01

Shrimp culture areas and production of the Mekong Delta cover about 60 percent of the total shrimp areas and production of Vietnam. Especially, the Delta contributes about 80 percent of the total shrimp production for export. Rapid development of the shrimp industry is raising a number of serious problems that need to be solved. Shrimp seed supply (post larvae production) plays an essential role in the shrimp industry and it is one of the most important constraints to the development of the s...

Human factors and tidal influences on water quality of an urban river in Can Tho, a major city of the Mekong Delta, Vietnam.

Science.gov (United States)

Ozaki, Hirokazu; Co, Thi Kinh; Le, Anh Kha; Pham, Viet Nu; Nguyen, Van Be; Tarao, Mitsunori; Nguyen, Huu Chiem; Le, Viet Dung; Nguyen, Hieu Trung; Sagehashi, Masaki; Ninomiya-Lim, Sachi; Gomi, Takashi; Hosomi, Masaaki; Takada, Hideshige

2014-02-01

In this study, we focused on water quality in an urban canal and the Mekong River in the city of Can Tho, a central municipality of the Mekong Delta region, southern Vietnam. Water temperature, pH, electrical conductivity, BOD5, CODCr, Na(+), Cl(-), NH4 (+)-N, SO4 (2-)-S, NO3 (-)-N, and NO2 (-)-N for both canal and river, and tide level of the urban canal, were monitored once per month from May 2010 to April 2012. The urban canal is subject to severe anthropogenic contamination, owing to poor sewage treatment. In general, water quality in the canal exhibited strong tidal variation, poorer at lower tides and better at higher tides. Some anomalies were observed, with degraded water quality under some high-tide conditions. These were associated with flow from the upstream residential area. Therefore, it was concluded that water quality in the urban canal changed with a balance between dilution effects and extent of contaminant supply, both driven by tidal fluctuations in the Mekong River.

A comparative study of golf industry between Yangtze River Delta, China and Central Japan

Science.gov (United States)

Yang, Yangfan; Jin, Pingbin; Gong, Huiwen

2018-03-01

As a competition event of the 2016 Olympic Game, golf sport has aroused great attention around the world. And the Yangtze River Delta(YRD) in China, has already got certain basis and qualifications of developing golf industry, but somehow far from meeting the great potential demand of the market. This research selects the Yangtze River Delta (YRD) and Central Japan (CJ), which are indifferent golf developing stages, as the objectives. Comparative studies are being carried out with an aim of revealing the discrepancies of golf industry in selected regions. The correlations between golf industry and regional economic developing level have been explored as well. Mainly based on a geographical perspective, this research presents an initial effort to combine approaches of setting comparative indexes and spatial analysis, so that golf industry of selected regions will be compared in all directions. The results reveal that great gaps exist in YRD and CJ in terms of golf construction, service, and golf consumption. Problems in developing golf industry in YRD are identified based on the empirical results. A long-term golf development in YRD that deviating from the realistic demand is attributed to both government policies and the operational principles that the market subjects hold. Based on a comparative empirical study, suggestions relating to the government as well as the market players are put forward, with an aim of guiding the golf industry to develop in a sustainable way.

Assessing Niger-Delta Wetland Resources: A Case-Study of Mangrove Ecosystem

Science.gov (United States)

Anwan, R. H.; Ndimele, P. E.; Whenu, O. O.; Anetekhai, M. A.; Essien-Ibok, M. A.; Erondu, E. S.

2016-02-01

The Niger Delta is located in the Atlantic coast of Southern Nigeria and is the world's second largest delta with a coastline of about 450km. The Niger Delta region occupies a surface area of about 112,110km2, representing about 12% of Nigeria's total surface area. The Delta's environment can be broken down into four ecological zones: coastal barrier islands, mangrove swamp forests, freshwater swamps, and lowland rainforests. The mangrove swamps of Niger Delta, which is the largest delta in Africa constitute the dominant wetland ecosystem in the Niger Delta region and covers an area of about 1,900km2. Mangroves constitute important nurseries for fishes, crustaceans, sponges, algae and other invertebrates, and also acts as a sink, retaining pollutants from contaminated tidal water. The Niger Delta mangrove together with the creeks and rivers are a major source of food and livelihood for about 30 million people, which represents more than 17% of Nigeria's population. Other ecosystem services provided by this unique environment are flood control, ground water re-fill, reservoir of biodiversity, fuel wood, cultural values etc. This ecosystem also plays important role in climate change mitigation because of its high blue carbon sequestration potential. This is particularly important because of continuous gas flaring in Niger Delta from petroleum operations, which releases carbon dioxide among other gases into the atmosphere. This wetland is potentially a good site for ecotourism and also qualifies to be a world heritage site and Ramsar site if proper steps are taken. The benefits derivable from this fragile ecosystem are under severe threat by anthropogenic stressors. These include the installation of pipelines and seismic exploration by oil companies, crude oil pollution, deforestation, urbanization etc. This paper discusses the extent of depletion and loss of mangrove ecosystem in the Niger Delta region and the value of its goods and services.

Tide-Dominated Tract (TDT) as a key sedimentary zone characterizing tide-dominated large-river delta and estuary systems

Science.gov (United States)

Saito, Y.

2017-12-01

Large rivers in continents have a characteristic of slow rise and fall in water levels during floods or the wet season due to a wide drainage basin. A gentle river gradient and large water discharge have relatively large tidal ranges at the river mouth, resulting in large backwater effects further upstream. The result of the Mekong River survey (386 riverbed sediments, river topography, CTD, and biofacies) shows that the distributary channels of the Mekong River delta in Vietnam are divided into two parts: the landward river-dominated tract (RDT) and seaward tide-dominated tract (TDT). The RDT is characterized by a highly variable and deepening trend in water depth and coarse-grained sediments with a fining trend downstream. The TDT is characterized by a shallowing trend in water depth with river-widening, smooth riverbeds, a straight shape, and heterolithic f- to vf-sand and mud alternation (tidal thythmite). The boundary of both tracts is sharply identified by sediment facies and river morphology. Sediment facies indicates that the dominant sedimentary process of bottom sediments is "bedload" in the RDT and "suspension" in the TDT. Daily tidal changes are observed through the year, while water-level changes during the flood/wet season are limited in the TDT. Saltwater intrusion is limited within the seaward part of the TDT alone ( 50 km), close to final bifurcation points. However, brackish-water biofacies is observed in the TDT mainly due to diluted brackish water and/or tolerance to the freshwater environment. These characteristics are also found in the Yangtze; the distance of the TDT/RDT boundary from the river mouth is ca. 100 km in the Mekong, and 200 km in the Yangtze. The preservation potential of sediments in a TDT is low in a progradational system, and high in abandoned channels. The early Holocene transgressive estuary system in the incised valley of the Yangtze formed during the Last Glacial Maximum was composed of 20 m-thick fine-grained heterolithic

Peat or no peat: Why do the Rajang and Mahakam Deltas differ?

Energy Technology Data Exchange (ETDEWEB)

Gastaldo, Robert A. [Department of Geology, Colby College, 5807 Mayflower Hill Drive, Waterville, ME 04901 (United States)

2010-08-01

Coastal and deltaic Holocene peat accumulations around the equatorial island of Borneo, Southeast Asia, have served as models for economic coal-bearing sequences in the stratigraphic record. Although climatic conditions, vegetational communities, and sedimentary regimes are comparable, peat accumulations are not found on both the western and eastern sides of the island. The Rajang River delta and coastal plain, Sarawak, East Malaysia, are covered in areally extensive, thick peat deposits that have attained at least a thickness of > 13 m in ombrogenous peat domes (Marudi, Baram River). Peat-swamp biomass began to accumulate over Pleistocene podzols when sea level stabilized {proportional_to} 7.5 ka and delta progradation was initiated. The Mahakam River delta and coastal plain, East Kalimantan, Indonesia, also began progradation at this time, but there is no evidence in any part of the coastal region for peat accumulation. Rather, poorly developed organic-rich gleysols occur throughout the delta plain. Both the Rajang River and Mahakam River deltas are tidally influenced, fine-grained systems, with a sediment provenance in the Central Massif. Sediment transported through the Rajang River delta differs in that as much as 60% of the clay minerals deposited in the system are mixed layer (I/S) and expandable (K/E) clays that act to restrict pore water flow in the tidal and overbank deposits that comprise the delta plain. These result in the development of an aquiclude above which paludal conditions develop, promoting accumulation of organic matter. In contrast, there is a low proportion of mixed layer and expandable clays transported in the Mahakam River system. This precludes the development of a stilted water table within the delta, allowing for organic matter recycling without peat accumulation. The presence of a high proportion of expandable clay minerals on the western side of Borneo is a reflection of the weathering and eroding source rocks on this side of the

Assessing the Environmental Condition of Minor Rivers in Urban Areas

Directory of Open Access Journals (Sweden)

Vladimir Sergeevich Kuznetsov

2017-11-01

Full Text Available This article is devoted to the study of water and sediment pollution in the channel of the Neva delta. Spectrophotometry was used to determine the concentration of pollutants in water. In the chemical analysis of the precipitate, atomic absorption spectroscopy and infrared spectroscopy were used. Analysis of the hydrochemical composition and sediment of the Smolenka River showed high concentrations of heavy metals and petroleum products. At the same time, the hydrochemical composition of the Smolenka River is highly unstable, but the concentration of oil products and lead in the sediments indicates the presence of local pollution sources. Based on our findings, we are guided by the restoration of the aquatic environment.

Blood lead level is associated with non-alcoholic fatty liver disease in the Yangtze River Delta region of China in the context of rapid urbanization.

Science.gov (United States)

Zhai, Hualing; Chen, Chi; Wang, Ningjian; Chen, Yi; Nie, Xiaomin; Han, Bing; Li, Qin; Xia, Fangzhen; Lu, Yingli

2017-08-31

China has undergone rapid urbanization in the past three decades. We aimed to report blood lead level (B-Pb) in the most rapidly urbanized Yangtze River Delta Region of China, and explore the association B-Pb and non-alcoholic fatty liver disease (NAFLD). Our data source was the SPECT-China study. We enrolled 2011 subjects from 6 villages in the Yangtze River Delta Region. Lead was measured by atomic absorption spectrometry. According to abdominal ultrasound, residents were divided into normal and NAFLD groups. In total, 824 (41.0%) were diagnosed with NAFLD. Medians (interquartile range) of B-Pb were 5.29 μg/dL (3.60-7.28) [0.25 μmol/L (0.17-0.35)] for men and 4.49 μg/dL (2.97-6.59) [0.22 μmol/L (0.14-0.32)] for women. In both genders, the NAFLD group had significantly greater B-Pb than normal group (both P Yangtze River Delta Region were much higher than in developed countries. Elevated B-Pb was associated with an increased risk of NAFLD, especially in women.

Mixing state of oxalic acid containing particles in the rural area of Pearl River Delta, China: implications for the formation mechanism of oxalic acid

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C. Cheng

2017-08-01

Full Text Available The formation of oxalic acid and its mixing state in atmospheric particulate matter (PM were studied using a single-particle aerosol mass spectrometer (SPAMS in the summer and winter of 2014 in Heshan, a supersite in the rural area of the Pearl River Delta (PRD region in China. Oxalic-acid-containing particles accounted for 2.5 and 2.7 % in total detected ambient particles in summer and winter, respectively. Oxalic acid was measured in particles classified as elemental carbon (EC, organic carbon (OC, elemental and organic carbon (ECOC, biomass burning (BB, heavy metal (HM, secondary (Sec, sodium-potassium (NaK, and dust. Oxalic acid was found predominantly mixing with sulfate and nitrate during the whole sampling period, likely due to aqueous-phase reactions. In summer, oxalic-acid-containing particle number and ozone concentration followed a very similar trend, which may reflect the significant contribution of photochemical reactions to oxalic acid formation. The HM particles were the most abundant oxalic acid particles in summer and the diurnal variations in peak area of iron and oxalic acid show opposite trends, which suggests a possible loss of oxalic acid through the photolysis of iron oxalato-complexes during the strong photochemical activity period. In wintertime, carbonaceous particles contained a substantial amount of oxalic acid as well as abundant carbon clusters and BB markers. The general existence of nitric acid in oxalic-acid-containing particles indicates an acidic environment during the formation process of oxalic acid. The peak areas of nitrate, sulfate and oxalic had similar temporal change in the carbonaceous type oxalic acid particles, and the organosulfate-containing oxalic acid particles correlated well with total oxalic acid particles during the haze episode, which suggests that the formation of oxalic acid is closely associated with the oxidation of organic precursors in the aqueous phase.

[Study on the content and carbon isotopic composition of water dissolved inorganic carbon from rivers around Xi'an City].

Science.gov (United States)

Guo, Wei; Li, Xiang-Zhong; Liu, Wei-Guo

2013-04-01

In this study, the content and isotopic compositions of water dissolved inorganic carbon (DIC) from four typical rivers (Chanhe, Bahe, Laohe and Heihe) around Xi'an City were studied to trace the possible sources of DIC. The results of this study showed that the content of DIC in the four rivers varied from 0.34 to 5.66 mmol x L(-1) with an average value of 1.23 mmol x L(-1). In general, the content of DIC increased from the headstream to the river mouth. The delta13C(DIC) of four rivers ranged from -13.3 per thousand to -7.2 per thousand, with an average value of -10.1 per thousand. The delta13C(DIC) values of river water were all negative (average value of -12.6 per thousand) at the headstream of four rivers, but the delta13C(DIC) values of downstream water were more positive (with an average value of -9.4 per thousand). In addition, delta13C(DIC) of river water showed relatively negative values (the average value of delta13C(DIC) was -10.5 per thousand) near the estuary of the rivers. The variation of the DIC content and its carbon isotope suggested that the DIC sources of the rivers varied from the headstream to the river mouth. The negative delta13C(DIC) value indicated that the DIC may originate from the soil CO2 at the headstream of the rivers. On the other hand, the delta13C(DIC) values of river water at the middle and lower reaches of rivers were more positive, and it showed that soil CO2 produced by respiration of the C4 plants (like corn) and soil carbonates with positive delta13C values may be imported into river water. Meanwhile, the input of pollutants with low delta13C(DIC) values may result in a decrease of delta13C(DIC) values in the rivers. The study indicated that the DIC content and carbon isotope may be used to trace the sources of DIC in rivers around Xi'an City. Our study may provide some basic information for tracing the sources of DIC of rivers in the small watershed area in the Loess Plateau of China.

To what extent can China’s near-term air pollution control policy protect air quality and human health? A case study of the Pearl River Delta region

International Nuclear Information System (INIS)

Jiang, Xujia; Hong, Chaopeng; Zheng, Yixuan; Zheng, Bo; Guan, Dabo; Zhang, Qiang; Gouldson, Andy; He, Kebin

2015-01-01

Following a series of extreme air pollution events, the Chinese government released the Air Pollution Prevention and Control Action Plan in 2013 (China’s State Council 2013). The Action Plan sets clear goals for key regions (i.e. cities above the prefecture level, Beijing-Tianjin-Hebei Province, the Yangtze River Delta and the Pearl River Delta) and establishes near-term control efforts for the next five years. However, the extent to which the Action Plan can direct local governments’ activities on air pollution control remains unknown. Here we seek to evaluate the air quality improvement and associated health benefits achievable under the Action Plan in the Pearl River Delta (PRD) area from 2012 to 2017. Measure-by-measure quantification results show that the Action Plan would promise effective emissions reductions of 34% of SO 2 , 28% of NO x , 26% of PM 2.5 (particulate matter less than 2.5 μm in diameter), and 10% of VOCs (volatile organic compounds). These emissions abatements would lower the PM 2.5 concentration by 17%, surpassing the 15% target established in the Action Plan, thereby avoiding more than 2900 deaths and 4300 hospital admissions annually. We expect the implementation of the Action Plan in the PRD would be productive; the anticipated impacts, however, fall short of the goal of protecting the health of local residents, as there are still more than 33 million people living in places where the annual mean ambient PM 2.5 concentrations are greater than 35 μg m −3 , the interim target-3 of the World Health Organization (WHO). We therefore propose the next steps for air pollution control that are important not only for the PRD but also for all other regions of China as they develop and implement effective air pollution control policies. (letter)

To what extent can China’s near-term air pollution control policy protect air quality and human health? A case study of the Pearl River Delta region

Science.gov (United States)

Jiang, Xujia; Hong, Chaopeng; Zheng, Yixuan; Zheng, Bo; Guan, Dabo; Gouldson, Andy; Zhang, Qiang; He, Kebin

2015-10-01

Following a series of extreme air pollution events, the Chinese government released the Air Pollution Prevention and Control Action Plan in 2013 (China’s State Council 2013). The Action Plan sets clear goals for key regions (i.e. cities above the prefecture level, Beijing-Tianjin-Hebei Province, the Yangtze River Delta and the Pearl River Delta) and establishes near-term control efforts for the next five years. However, the extent to which the Action Plan can direct local governments’ activities on air pollution control remains unknown. Here we seek to evaluate the air quality improvement and associated health benefits achievable under the Action Plan in the Pearl River Delta (PRD) area from 2012 to 2017. Measure-by-measure quantification results show that the Action Plan would promise effective emissions reductions of 34% of SO2, 28% of NOx, 26% of PM2.5 (particulate matter less than 2.5 μm in diameter), and 10% of VOCs (volatile organic compounds). These emissions abatements would lower the PM2.5 concentration by 17%, surpassing the 15% target established in the Action Plan, thereby avoiding more than 2900 deaths and 4300 hospital admissions annually. We expect the implementation of the Action Plan in the PRD would be productive; the anticipated impacts, however, fall short of the goal of protecting the health of local residents, as there are still more than 33 million people living in places where the annual mean ambient PM2.5 concentrations are greater than 35 μg m-3, the interim target-3 of the World Health Organization (WHO). We therefore propose the next steps for air pollution control that are important not only for the PRD but also for all other regions of China as they develop and implement effective air pollution control policies.

Temporal fluctuation of multidrug resistant salmonella typhi haplotypes in the mekong river delta region of Vietnam.

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Kathryn E Holt

2011-01-01

Full Text Available typhoid fever remains a public health problem in Vietnam, with a significant burden in the Mekong River delta region. Typhoid fever is caused by the bacterial pathogen Salmonella enterica serovar Typhi (S. Typhi, which is frequently multidrug resistant with reduced susceptibility to fluoroquinolone-based drugs, the first choice for the treatment of typhoid fever. We used a GoldenGate (Illumina assay to type 1,500 single nucleotide polymorphisms (SNPs and analyse the genetic variation of S. Typhi isolated from 267 typhoid fever patients in the Mekong delta region participating in a randomized trial conducted between 2004 and 2005.the population of S. Typhi circulating during the study was highly clonal, with 91% of isolates belonging to a single clonal complex of the S. Typhi H58 haplogroup. The patterns of disease were consistent with the presence of an endemic haplotype H58-C and a localised outbreak of S. Typhi haplotype H58-E2 in 2004. H58-E2-associated typhoid fever cases exhibited evidence of significant geo-spatial clustering along the Sông H u branch of the Mekong River. Multidrug resistance was common in the established clone H58-C but not in the outbreak clone H58-E2, however all H58 S. Typhi were nalidixic acid resistant and carried a Ser83Phe amino acid substitution in the gyrA gene.the H58 haplogroup dominates S. Typhi populations in other endemic areas, but the population described here was more homogeneous than previously examined populations, and the dominant clonal complex (H58-C, -E1, -E2 observed in this study has not been detected outside Vietnam. IncHI1 plasmid-bearing S. Typhi H58-C was endemic during the study period whilst H58-E2, which rarely carried the plasmid, was only transient, suggesting a selective advantage for the plasmid. These data add insight into the outbreak dynamics and local molecular epidemiology of S. Typhi in southern Vietnam.

Natural and anthropogenic processes that concentrate Mn in rural and urban environments of the lower Mississippi River Delta

International Nuclear Information System (INIS)

Mielke, H.W.; Gonzales, C.R.; Powell, E.; Shah, A.; Mielke, P.W.

2002-01-01

This study evaluated natural processes and projected ethyl cyclopentadienyl manganese tricarbonyl fuel additives as sources of Mn accumulation in the environment. Data sets include fresh alluvium and sediments from the lower Mississippi River Delta and a soil metal survey of metropolitan New Orleans. The (1) railroad Mn, (2) industrial Mn, and (3) dynamic aquifer-stream transfer of Mn hypotheses were tested with the Mississippi River Delta data. Friction between Mn-rich steel wheels and rails contributes Mn (P=0.017) to the environment, supporting (1). Sediment loads of Mn were similar (P=0.77) upstream and downstream from the Louisiana industrial corridor, not supporting (2). The median Mn on the alluvium surface (59 mg/kg), in the aquifer (159 mg/kg), and in the riverbank aquifer discharge zone (513 mg/kg) support (3) as a mechanism for Mn enrichment of lay. The New Orleans soil metal survey data set shows a rural to urban increase of fourfold for Mn and three orders of magnitude for Pb. At 1999 .S. highway fuel use, 8.3 mg of Mn per L would yield 5000 metric tons of Mn annually. If 13% of Mn were emitted, 650 tons of Mn would become aerosols annually, while 87% or 4350 tons would remain in engines. The 1999 toxic release inventory for Mn shows 370 tons as total emissions compared to the potential of 390 and 260 tons from vehicles, respectively, in urban and rural areas. A precautionary lesson from the use of Pb as a fuel additive is that the use of Mn as a fuel additive would be associated with an increased risk or neonates exceeding the estimated total tolerable daily intake of .1-16.5μg Mn (especially in urban inner city environments) because neonates lack fully functional hepatic clearance for Mn

Investigating the Impacts of Landuse-landcover (LULC Change in the Pearl River Delta Region on Water Quality in the Pearl River Estuary and Hong Kong’s Coast

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Hongyan Xi

2009-11-01

Full Text Available Water quality information in the coastal region of Hong Kong and the Pearl River Estuary (PRE is of great concern to the local community. Due to great landuse-landcover (LULC changes with rapid industrialization and urbanization in the Pearl River Delta (PRD region, water quality in the PRE has worsened during the last 20 years. Frequent red tide and harmful algal blooms have occurred in the estuary and its adjacent coastal waters since the 1980s and have caused important economic losses, also possibly threatening to the coastal environment, fishery, and public health in Hong Kong. In addition, recent literature shows that water nutrients in Victoria Harbor of Hong Kong have been proven to be strongly influenced by both the Pearl River and sewage effluent in the wet season (May to September, but it is still unclear how the PRE diluted water intrudes into Victoria Harbor. Due to the cloudy and rainy conditions in the wet season in Hong Kong, ASAR images will be used to monitor the PRE river plumes and track the intruding routes of PRE water nutrients. In this paper, we first review LULC change in the PRD and then show our preliminary results to analyze water quality spatial and temporal information from remote observations with different sensors in the coastal region and estuary. The study will also emphasizes on time series of analysis of LULC trends related to annual sediment yields and critical source areas of erosion for the PRD region since the 1980s.

Large-scale dam removal on the Elwha River, Washington, USA: coastal geomorphic change

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Gelfenbaum, Guy R.; Stevens, Andrew W.; Miller, Ian M.; Warrick, Jonathan A.; Ogston, Andrea S.; Eidam, Emily

2015-01-01

Two dams on the Elwha River, Washington State, USA trapped over 20 million m3 of mud, sand, and gravel since 1927, reducing downstream sediment fluxes and contributing to erosion of the river's coastal delta. The removal of the Elwha and Glines Canyon dams, initiated in September 2011, induced massive increases in river sediment supply and provided an unprecedented opportunity to examine the geomorphic response of a coastal delta to these increases. Detailed measurements of beach topography and nearshore bathymetry show that ~ 2.5 million m3 of sediment was deposited during the first two years of dam removal, which is ~ 100 times greater than deposition rates measured prior to dam removal. The majority of the deposit was located in the intertidal and shallow subtidal region immediately offshore of the river mouth and was composed of sand and gravel. Additional areas of deposition include a secondary sandy deposit to the east of the river mouth and a muddy deposit west of the mouth. A comparison with fluvial sediment fluxes suggests that ~ 70% of the sand and gravel and ~ 6% of the mud supplied by the river was found in the survey area (within about 2 km of the mouth). A hydrodynamic and sediment transport model, validated with in-situ measurements, shows that tidal currents interacting with the larger relict submarine delta help disperse fine sediment large distances east and west of the river mouth. The model also suggests that waves and currents erode the primary deposit located near the river mouth and transport sandy sediment eastward to form the secondary deposit. Though most of the substrate of the larger relict submarine delta was unchanged during the first two years of dam removal, portions of the seafloor close to the river mouth became finer, modifying habitats for biological communities. These results show that river restoration, like natural changes in river sediment supply, can result in rapid and substantial coastal geomorphological

Dynamic controls on shallow clinoform geometry: Mekong Delta, Vietnam

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Eidam, E. F.; Nittrouer, C. A.; Ogston, A. S.; DeMaster, D. J.; Liu, J. P.; Nguyen, T. T.; Nguyen, T. N.

2017-09-01

Compound deltas, composed of a subaerial delta plain and subaqueous clinoform, are common termini of large rivers. The transition between clinoform topset and foreset, or subaqueous rollover point, is located at 25-40-m water depth for many large tide-dominated deltas; this depth is controlled by removal of sediment from the topset by waves, currents, and gravity flows. However, the Mekong Delta, which has been classified as a mixed-energy system, has a relatively shallow subaqueous rollover at 4-6-m depth. This study evaluates dynamical measurements and seabed cores collected in Sep 2014 and Mar 2015 to understand processes of sediment transfer across the subaqueous delta, and evaluate possible linkages to geometry. During the southwest rainy monsoon (Sep 2014), high river discharge, landward return flow under the river plume, and regional circulation patterns facilitated limited sediment flux to the topset and foreset, and promoted alongshore flux to the northeast. Net observed sediment fluxes in Sep 2014 were landward, however, consistent with hypotheses about seasonal storage on the topset. During the northeast rainy monsoon, low river discharge and wind-driven currents facilitated intense landward and southwestward fluxes of sediment. In both seasons, bed shear velocities frequently exceeded the 0.01-0.02 m/s threshold of motion for sand, even in the absence of strong wave energy. Most sediment transport occurred at water depths 4 cm/yr at energy-limited, and thus rollover depths cannot be predicted solely by bed-stress distributions. In systems like the subaqueous Mekong Delta, direction of transport may have a key impact on morphology.

Drainage areas of the Potomac River basin, West Virginia

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Wiley, Jeffrey B.; Hunt, Michelle L.; Stewart, Donald K.

1996-01-01

This report contains data for 776 drainage-area divisions of the Potomac River Basin, from the headwaters to the confluence of the Potomac River and the Shenandoah River. Data, compiled in downstream order, are listed for streams with a drainage area of approximately 2 square miles or larger within West Virginia and for U.S. Geological Survey streamflow-gaging stations. The data presented are the stream name, the geographical limits in river miles, the latitude and longitude of the point, the name of the county, and the 7 1/2-minute quadrangle in which the point lies, and the drainage area of that site. The total drainage area of the Potomac River Basin downstream of the confluence of the Shenandoah River at the State boundary is 9,367.29 square miles.

Process analysis and sensitivity study of regional ozone formation over the Pearl River Delta, China, during the PRIDE-PRD2004 campaign using the Community Multiscale Air Quality modeling system

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X. Wang

2010-05-01

Full Text Available In this study, the Community Multiscale Air Quality (CMAQ modeling system is used to simulate the ozone (O₃ episodes during the Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, China, in October 2004 (PRIDE-PRD2004. The simulation suggests that O₃ pollution is a regional phenomenon in the Pearl River Delta (PRD. Elevated O₃ levels often occurred in the southwestern inland PRD, Pearl River estuary (PRE, and southern coastal areas during the 1-month field campaign. Three evolution patterns of simulated surface O₃ are summarized based on different near-ground flow conditions. More than 75% of days featured interactions between weak synoptic forcing and local sea-land circulation. Integrated process rate (IPR analysis shows that photochemical production is a dominant contributor to O₃ enhancement from 09:00 to 15:00 local standard time in the atmospheric boundary layer over most areas with elevated O₃ occurrence in the mid-afternoon. The simulated ozone production efficiency is 2–8 O₃ molecules per NO_x molecule oxidized in areas with high O₃ chemical production. Precursors of O₃ originating from different source regions in the central PRD are mixed during the course of transport to downwind rural areas during nighttime and early morning, where they then contribute to the daytime O₃ photochemical production. The sea-land circulation plays an important role on the regional O₃ formation and distribution over PRD. Sensitivity studies suggest that O₃ formation is volatile-organic-compound-limited in the central inland PRD, PRE, and surrounding coastal areas with less chemical aging (NO_x/NO_y>0.6, but is NO_x-limited in the rural southwestern PRD with aged air (NO_x/NO_y<0.3.

COMPLEX NETWORK SIMULATION OF FOREST NETWORK SPATIAL PATTERN IN PEARL RIVER DELTA

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Y. Zeng

2017-09-01

Full Text Available Forest network-construction uses for the method and model with the scale-free features of complex network theory based on random graph theory and dynamic network nodes which show a power-law distribution phenomenon. The model is suitable for ecological disturbance by larger ecological landscape Pearl River Delta consistent recovery. Remote sensing and GIS spatial data are available through the latest forest patches. A standard scale-free network node distribution model calculates the area of forest network’s power-law distribution parameter value size; The recent existing forest polygons which are defined as nodes can compute the network nodes decaying index value of the network’s degree distribution. The parameters of forest network are picked up then make a spatial transition to GIS real world models. Hence the connection is automatically generated by minimizing the ecological corridor by the least cost rule between the near nodes. Based on scale-free network node distribution requirements, select the number compared with less, a huge point of aggregation as a future forest planning network’s main node, and put them with the existing node sequence comparison. By this theory, the forest ecological projects in the past avoid being fragmented, scattered disorderly phenomena. The previous regular forest networks can be reduced the required forest planting costs by this method. For ecological restoration of tropical and subtropical in south China areas, it will provide an effective method for the forest entering city project guidance and demonstration with other ecological networks (water, climate network, etc. for networking a standard and base datum.

Source Identification and Apportionment of Trace Elements in Soils in the Yangtze River Delta, China.

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Shao, Shuai; Hu, Bifeng; Fu, Zhiyi; Wang, Jiayu; Lou, Ge; Zhou, Yue; Jin, Bin; Li, Yan; Shi, Zhou

2018-06-12

Trace elements pollution has attracted a lot of attention worldwide. However, it is difficult to identify and apportion the sources of multiple element pollutants over large areas because of the considerable spatial complexity and variability in the distribution of trace elements in soil. In this study, we collected total of 2051 topsoil (0⁻20 cm) samples, and analyzed the general pollution status of soils from the Yangtze River Delta, Southeast China. We applied principal component analysis (PCA), a finite mixture distribution model (FMDM), and geostatistical tools to identify and quantitatively apportion the sources of seven kinds of trace elements (chromium (Cr), cadmium (Cd), mercury (Hg), copper (Cu), zinc (Zn), nickel (Ni), and arsenic (As)) in soil. The PCA results indicated that the trace elements in soil in the study area were mainly from natural, multi-pollutant and industrial sources. The FMDM also fitted three sub log-normal distributions. The results from the two models were quite similar: Cr, As, and Ni were mainly from natural sources caused by parent material weathering; Cd, Cu, and Zu were mainly from mixed sources, with a considerable portion from anthropogenic activities such as traffic pollutants, domestic garbage, and agricultural inputs, and Hg was mainly from industrial wastes and pollutants.

Emergy Synthesis and Regional Sustainability Assessment: Case Study of Pan-Pearl River Delta in China

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Guomin Li

2014-08-01

Full Text Available In this paper, emergy analysis is used in association with the ternary diagrams and geographic information system (GIS tools to improve the evaluation of sustainability for the Pan-Pearl River Delta (PPRD region. Emergy accounting of PPRD is estimated, and various emergy-based indicators are reported. Ternary diagrams are drawn to provide a graphical representation of the emergy accounting data. Finally, the GIS tools are employed to assist in the emergy-based spatial analysis, and emergy density based on flat land area is mapped to reflect the intensity of emergy use in human activity areas. Results show the following: (1 the current development path of the PPRD region, with the value of emergy sustainability index (ESI = 0.227 significantly lower than one, is unsustainable in the long run; (2 Guangdong has the lowest ESI value (0.071, and the ESI values of Fujian, Guangxi, Hunan and Jiangxi are lower than 0.5, indicating that the economy in these provinces overly relies on non-renewable and imported resources; (3 Guizhou has a high emergy yield rate and is thus the main energy supplier in PPRD; and (4 among the nine provinces in PPRD, only Hainan has an ESI value (2.145 higher than one.

The Legal Status of the Danube Delta Biosphere Reservation

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Florica Brasoveanu

2012-05-01

Full Text Available In recent years the world has become aware that natural resources are not inexhaustible, that manyspecies are threatened with extinction and that is is necessary to strive for judicious use of natural resources tofulfill the needs of the present without compromising the ability of future generations to meet their needs(principle of sustainable development. To conserve species and habitats protected areas have beenestablished worldwide. The protected area is a geographically defined area, with rare natural elements and / orendangered species, regulated and managed in order to achieve specific conservation objectives. Althoughranked Europe's second in size (after the Volga River and the 20th in the world, because of the rich landscapeand wildlife, with the birds ranked most important, the Danube Delta has a very special interest scientificallyas it is a natural laboratory of forming delta, tourism and economic ecosystems, through its renewable naturalresources of which the most important resources are living aquatic resources.

Teaching High School Students Machine Learning Algorithms to Analyze Flood Risk Factors in River Deltas

Science.gov (United States)

Rose, R.; Aizenman, H.; Mei, E.; Choudhury, N.

2013-12-01

High School students interested in the STEM fields benefit most when actively participating, so I created a series of learning modules on how to analyze complex systems using machine-learning that give automated feedback to students. The automated feedbacks give timely responses that will encourage the students to continue testing and enhancing their programs. I have designed my modules to take the tactical learning approach in conveying the concepts behind correlation, linear regression, and vector distance based classification and clustering. On successful completion of these modules, students will learn how to calculate linear regression, Pearson's correlation, and apply classification and clustering techniques to a dataset. Working on these modules will allow the students to take back to the classroom what they've learned and then apply it to the Earth Science curriculum. During my research this summer, we applied these lessons to analyzing river deltas; we looked at trends in the different variables over time, looked for similarities in NDVI, precipitation, inundation, runoff and discharge, and attempted to predict floods based on the precipitation, waves mean, area of discharge, NDVI, and inundation.

Restoring the longitudinal connectivity of the Rur Delta into the river Meuse; Herstellung der Durchgaengigkeit des Muendungsdeltas der Rur in die Maas

Energy Technology Data Exchange (ETDEWEB)

Hermens, Gereon; Keuneke, Rita [Ingenieurbuero Floecksmuehle, Aachen (Germany)

2012-07-01

The delta where the Eifelrur (NL:Roer) flows into the river Meuse is located in the Dutch city of Roermond and divides into two branches. While the branch that flows through the city runs the hydro power plant ECI-Centrale, the second branch - called Hambeek - is used mainly for flood protection. Until the year 2007, the only existing upstream migration facility was installed in the Hambeek branch, but its traceability was unsatisfactory. In addition, biological studies revealed a constrained passability at the spot. The hydro power plant, which carries the highest discharge for the greatest part of the year, had no upstream migration facility. Since the Rur is an important tributary to the river Meuse, an ambitious project was launched to equip both branches with large migration facilities that meet current Dutch standards and now ensure connectivity in the delta. (orig.)

The Lower Danube River-Danube Delta-North West Black Sea: A pivotal area of major interest for the past, present and future of its fish fauna--A short review.

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Bănăduc, Doru; Rey, Sonia; Trichkova, Teodora; Lenhardt, Mirjana; Curtean-Bănăduc, Angela

2016-03-01

The complex Danube-Black Sea geoecosystem, created by a unique combination of integrated biotopes and biocoenoses related forces and counter-forces in time and space, forms a rich "ichthyosystem". The equilibrium among the fish species captured in the Danube Delta reveals its structural and functional roles in the connectivity of the Danube and Black Sea. The key role of the delta is evidenced by the fact that 57.26% of the Lower Danube-Danube Delta-North West Black Sea fish species use two or three of the subsystems in terms of habitats. Therefore, this convergence area can be considered to be a dynamic and rich "ichthyosystem", with three subsystems. All three evolved interdependently, which permits their flexibility and adaptation in an interdependent way. The habitat heterogeneity, native economic and conservation priority fish species of the Lower Danube-Danube Delta-North Western Black Sea have decreased significantly, and there are no indications that this trend will be halted soon. The Danube "sub-ichtyosystem" seems to be more directly affected than the others. The Lower Danube-Danube Delta-North Western Black Sea "ichthyosystem" exhibits a significant level of flexibility, resilience and adaptation over geological time, but has become much more sensitive to environmental perturbations due to the last century of human impact. This "ichthyosystem" is affected by non-native fish species. The study area represents an interdependent ecological net, without which the specific "ichthyosystem" formed over geological time will disappear. The studied ecological net fish fauna is an accurate indicator of various human pressures. The Lower Danube-Danube Delta-North West Black Sea geoecosystem, in which the Danube Delta provides the pivotal habitat element, is the matrix for a unique "ichthyosystem." However, human impacts decrease its resilience and can induce its extinction. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrological and Mineralogical Factors Influencing Paradoxical Groundwater Arsenic Release in the Red River Delta, Vietnam

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Nghiem, A.; Bostick, B. C.

2017-12-01

In South and Southeast Asia, the widespread contamination of groundwater arsenic (As) via microbial reduction of As-bearing iron (Fe) minerals in the subsurface results in toxic levels of arsenic above the World Health Organization (WHO) drinking water standard of 10 ug/L. High groundwater arsenic levels are generally found in gray Holocene aquifers whereas orange-sanded Pleistocene aquifers are typically a safer, lower As alternative. In the Red River Delta of Vietnam and elsewhere, Pleistocene aquifers can also have elevated arsenic levels, often due to increased groundwater pumping from the growing Hanoi area drawing high As water from Holocene aquifers, or from reduction induced by advected groundwater and organic carbon from the Red River. To determine which factors threaten the Pleistocene aquifers, we critically examine the hydrological and geochemical factors that could influence arsenic levels in the area. Exploiting an asymmetry in the region just south of Hanoi, yearlong spatiotemporal measurements of dissolved arsenic levels reveals a paradox between a Pleistocene aquifer site in Yen My (west bank) with higher As concentrations than a Holocene site in Van Duc (east bank). We monitor the influence of local and regional hydrology via water table measurements, stable water isotopes and conservative anion concentrations linked to the release of aqueous As. Preliminary x-ray absorption spectroscopy (XAS) data point to As(V)/arsenic sulfide minerals in Yen My versus As(III) minerals in Van Duc. Coupled to hydrology, downcore Fe Extended X-Ray Absorption Fine Structure (EXAFS) and As X-ray Absorption Near Edge Structure (XANES) stratigraphy and spatiotemporal dissolved organic carbon data serve to narrow down the possible sources of carbon and reductive processes that affect As speciation and transport. Overall, understanding sources that endanger the Pleistocene aquifers may elucidate important As cycling mechanisms at play that threatens water quality for

SEAWARD DRIFT OF THE PONTIC SHAD LARVAE (ALOSA PONTICA AND THE INFLUENCE OF DANUBE RIVER HYDROLOGY ON THEIR TRAVEL PATH THROUGH THE DANUBE DELTA SYSTEM.

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NAVODARU I.

2001-07-01

Full Text Available The Pontic shad lives in the northwestern part of the Black Sea. It migrates in the Danube River for spawning. The larvae drift passively towards the sea when they reach the life stage ranging from pre-larvae to post-larvae. During the larval stage the Pontic shad is floating, mainly in the 0-50 cm upper layer of river. Upstream of the Danube Delta, in the straight sector of the river, alosids are distributed mostly towards the middle of the river, where the water velocity is higher. In the curved section of the river, upstream of the location of the Danube River splitting in the delta’s branches, the water current is outwardly pushing the shad larvae to the right shore, the Romanian, respectively. Therefore, Tulcea branch (Romanian takes over 60-80 % from the total of Danubian larvae, even its water flow is smaller (40 % than Chilia branch (the border of Romania and Ukraine. The distribution of larvae at the splitting point influences the repartition of adult migratory catch, at return for spawning, between Saint George branch (Romania and Chilia branch. Consequently, the topography and hydrology of the river at the splitting point of the branceh which form the delta decide on the distribution of larvae, and later, when the shads are homing on the same way for spawning the sharing catch between Romania and Ukraine.

Seasonal changes in particulate and dissolved organic matter composition and quality in the Lena River Delta

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Mollenhauer, G.; Winterfeld, M.; Hefter, J.; Bodenstab, L.; Morgenstern, A.; Eulenburg, A.; Heim, B.; Koch, B.; Schefuss, E.; Moerth, C. M.; Rethemeyer, J.

2016-12-01

Arctic rivers are known to export large quantities of carbon by discharge of dissolved and particulate organic carbon (DOC, POC), and in a warming and progressively moister Arctic, these exports may increase resulting in a reduction of arctic continental carbon stocks. These rivers have highly variable discharge rates with a pronounced maximum during the spring freshet associated with highest concentrations of DOC and POC. Most studies investigating the isotopic composition and quality of carbon exported by Arctic rivers rely on samples taken in summer during base flow, which is due to the logistical challenges associated with sampling in the remote Arctic permafrost regions. Here we present a record of δ13C and Δ14C of DOC and POC collected between late May during the freshet and late August 2014 in the Lena River Delta. POC Δ14C shows an initial trend towards older values in the spring samples, which is reversed in summer, associated with a shift towards more depleted δ13C values. We interpret this aging trend as reflecting progressive thawing throughout the ice-free season, resulting in mobilization of progressively older carbon from deeper thawed layers. The summer reversal indicates admixture of aquatic organic matter. DOC Δ14C, in contrast, remains at relatively modern levels with rather constant δ13C values throughout the sampling period. We furthermore analysed the biomarker composition of Lena Delta particulate OM collected in spring and summer. From spring to summer, we observe trends in abundance of individual leaf-wax derived biomarkers indicating higher abundance of algal biomass in the summer particles. Trends in soil microbial biomarkers and compound-specific δD of leaf-wax lipids suggest a shift in sources towards higher contributions from the southern catchment in summer. DOC composition investigated with FT-ICR-MS changes from spring with higher abundances of compounds with high H/C and low O/C ratios to late summer, when fewer compounds

77 FR 67563 - Regulated Navigation Area-New Haven Harbor, Quinnipiac River, Mill River, New Haven, CT; Pearl...

Science.gov (United States)

2012-11-13

... 1625-AA11 Regulated Navigation Area--New Haven Harbor, Quinnipiac River, Mill River, New Haven, CT... Haven Harbor, Quinnipiac River and Mill River. The current RNA pertains only to the operation of tugs...) entitled Regulated Navigation Area--New Haven Harbor, Quinnipiac River, Mill River, New Haven, CT; Pearl...

Regional contribution to PM1 pollution during winter haze in Yangtze River Delta, China.

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Tang, Lili; Yu, Hongxia; Ding, Aijun; Zhang, Yunjiang; Qin, Wei; Wang, Zhuang; Chen, Wentai; Hua, Yan; Yang, Xiaoxiao

2016-01-15

To quantify regional sources contributing to submicron particulate matter (PM1) pollution in haze episodes, on-line measurements combining two modeling methods, namely, positive matrix factorization (PMF) and backward Lagrangian particle dispersion modeling (LPDM), were conducted for the period of one month in urban Nanjing, a city located in the western part of Yangtze River Delta (YRD) region of China. Several multi-day haze episodes were observed in December 2013. Long-range transport of biomass burning from the southwestern YRD region largely contributed to PM1 pollution with more than 25% of total organics mass in a lasting heavy haze. The LPDM analysis indicates that regional transport is a main source contributing to secondary low-volatility production. The high-potential source regions of secondary low-volatility production are mainly located in areas to the northeast of the city. High aerosol pollution was mainly contributed by regional transport associated with northeastern air masses. Such regional transport on average accounts for 46% of total NR-PM1 with sulfate and aged low-volatility organics being the largest fractions (>65%). Copyright © 2015 Elsevier B.V. All rights reserved.

Coordinated Development between Urban Tourism Economy and Transport in the Pearl River Delta, China

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Qiuxia Zheng

2016-12-01

Full Text Available By selecting the panel data from 2005 to 2014 of 9 cities in the Pearl River Delta (PRD in China, this paper respectively establishes the evaluation index system of tourism economy and transport. It also applies a synthetic evaluation model and coupling coordination model to estimate comprehensive indices of tourism economy and transport system and their coordinated relationships. The results show that: (1 during 2005–2014, the synthetic indices of tourism economy generally presented constantly upward tendency and the synthetic indices of transport represented wave-like raising trend in the PRD region; (2 during 2005–2014, the 9 cities in the PRD region gradually tended to have coordinated development between tourism economy and transport, and the central area of the PRD region developed faster than the flanks; (3 the correlations between the tourism economy and transport of the cities with abundant tourism resources, developed economy, and advanced transport facilities were more remarkable, and the coordination degrees were higher. Besides, macro-policies, mega-events, and locations also impacted on coordinated development between the tourism economy and transport in the PRD region.

Seed bank composition in a secondary forest in the Lower Delta of the Paraná River (Argentina

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Fábio Kalesnik

2013-03-01

Full Text Available The native forests once occupying the coastal levees of the Lower Delta islands of the Paraná River (in Argentina have been replaced by commercial forests. Many of those forests have been abandoned, resulting in secondary forest formation that is subject to numerous invasive exotic species. A priori observations suggest that successional trends do not lead to recovery of the original forest. The aim of the present study was to analyze the role of invasive exotic species in these environments and the likelihood of recovery of the original forest cover. Therefore, we examined the composition of the seed bank and of the standing vegetation, as well as the population structure of tree species. Secondary forests are described as being in an intermediate successional stage, with few exotic species (mainly trees but with a high abundance of standing vegetation and seed banks. These exotic species will likely continue to successfully predominate in different forest strata over the next stages. Because of the low density of native tree species, it is difficult to predict their future persistence. In conclusion, ecological restoration strategies will be needed in order to increase native tree species richness and biodiversity of the forests in the Lower Delta of the Paraná River.

Severe petrol contamination in the aquifer of the Llobregat river delta

International Nuclear Information System (INIS)

Garcia Gonzalez, E.

1993-01-01

On 16-09-91 an attack on an oil pipeline led to some 70 tons of petrol spilling out and catching fire. About 20 tons filtered down into the aquifer of the river Llobregat delta. On 08-12-91 the presence of petrol was detected in a well used for supplying water about 1 km downstream. A system was set up for monitoring and extracting the polluted ground water. The volume affected had now reached 3.5 hm''3. The decontamination costs came to 245 million pesetas in comparison to only 10 millions pesetas for the petrol spill. The cost of extracting the water was 70 pta/m''3. Finally the importance of regional planning and the need to prevent such accidents is pointed out. The means necessary to deal with them should be available. (Author)

Sustainable Urban Development and Land Use Change—A Case Study of the Yangtze River Delta in China

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Haiyan Zhang

2011-07-01

Full Text Available This paper introduces a sustainability assessment method for the rapidly urbanizing Yangtze River Delta in China addressing the role of land use pattern. We first calculated the sustainability component scores of 16 cities in the area in 2000 and 2005. The results showed that socioeconomic and environmental conditions improved while the performance of resource-use degraded from 2000 to 2005. We then made a spatial analysis of land use change (LUC using geographic information systems during 1990–2000. We found that diverse spatiotemporal transformation occurred among the cities and identified urban development cluster patterns and profiles based on development density. Finally, we examined the impact of LUC on sustainable urban development (SUD. Using regression techniques, we demonstrated that urbanization, infrastructure development, industrial structure and income significantly affected environmental performance and resource-use. These results suggest a moderate pace of LUC with steady economic growth being key to SUD.

Volatile Organic Compound (VOC) measurements in the Pearl River Delta (PRD) region, China

Science.gov (United States)

Liu, Ying; Shao, Min; Lu, Sihua; Chang, Chih-Chung; Wang, Jia-Lin; Chen, Gao

2008-03-01

We measured levels of ambient volatile organic compounds (VOCs) at seven sites in the Pearl River Delta (PRD) region of China during the Air Quality Monitoring Campaign spanning 4 October to 3 November 2004. Two of the sites, Guangzhou (GZ) and Xinken (XK), were intensive sites at which we collected multiple daily canister samples. The observations reported here provide a look at the VOC distribution, speciation, and photochemical implications in the PRD region. Alkanes constituted the largest percentage (>40%) in mixing ratios of the quantified VOCs at six sites; the exception was one major industrial site that was dominated by aromatics (about 52%). Highly elevated VOC levels occurred at GZ during two pollution episodes; however, the chemical composition of VOCs did not exhibit noticeable changes during these episodes. We calculated the OH loss rate to estimate the chemical reactivity of all VOCs. Of the anthropogenic VOCs, alkenes played a predominant role in VOC reactivity at GZ, whereas the contributions of reactive aromatics were more important at XK. Our preliminary analysis of the VOC correlations suggests that the ambient VOCs at GZ came directly from local sources (i.e., automobiles); those at XK were influenced by both local emissions and transportation of air mass from upwind areas.

Volatile Organic Compound (VOC measurements in the Pearl River Delta (PRD region, China

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Chih-chung Chang

2008-03-01

Full Text Available We measured levels of ambient volatile organic compounds (VOCs at seven sites in the Pearl River Delta (PRD region of China during the Air Quality Monitoring Campaign spanning 4 October to 3 November 2004. Two of the sites, Guangzhou (GZ and Xinken (XK, were intensive sites at which we collected multiple daily canister samples. The observations reported here provide a look at the VOC distribution, speciation, and photochemical implications in the PRD region. Alkanes constituted the largest percentage (>40% in mixing ratios of the quantified VOCs at six sites; the exception was one major industrial site that was dominated by aromatics (about 52%. Highly elevated VOC levels occurred at GZ during two pollution episodes; however, the chemical composition of VOCs did not exhibit noticeable changes during these episodes. We calculated the OH loss rate to estimate the chemical reactivity of all VOCs. Of the anthropogenic VOCs, alkenes played a predominant role in VOC reactivity at GZ, whereas the contributions of reactive aromatics were more important at XK. Our preliminary analysis of the VOC correlations suggests that the ambient VOCs at GZ came directly from local sources (i.e., automobiles; those at XK were influenced by both local emissions and transportation of air mass from upwind areas.

USING delta15N OF CHIRONOMIDAE TO HELP ASSESS CONDITION AND STRESSORS IN LAKES, RIVERS AND STREAMS OF THE UNITED STATES.

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To assess large-scale ecological conditions efficiently, indicators that can be collected quickly at many sites need to be developed. We explore the utility of delta 15N from basal food chain organisms to provide information on N loading and processing in lakes, rivers and stream...

Monitoring Population Evolution in the Pearl River Delta from 2000 TO 2010

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Yu, S.; Liu, F.; Zhang, Z.

2018-04-01

On behalf of more populous and developed regions in China, urban agglomerations have become important carries loading active economic activities and generous social benefits, and experienced sharper population increase, which results in great threat on local eco-environment construction. Therefore, exact and detailed population monitoring and analyzing, especially on the long sequence and multi frequency, is of great significance. The nighttime light time-series (NLT) products has been proven to be one of the most useful remotely sensed imagery to acquire persons at 1 km × 1 km scales. However, the existed problems, such as light saturation and blooming, greatly limit the accuracy of estimated results. Furthermore, it's difficult to spatialize population at km2 level due to the lack of basic data in non-census years. In order to solve all problems mentioned above, the populous Pearl River Delta was selected as the study area. A new residential extent extraction index (REEI) was proposed to solve light saturation and blooming problems. Population spatialization methods in census and non-census years were applied to acquire detailed population distribution from 2000 to 2010. Results showed the feasibility of the proposed methods in this work. During the decade, population was denser in the central PRD and sparser in the eastern, western and northern PRD. The speed of population increase was various in nine cities, but faster in 2000-2005 than 2005-2010.

Otolith analysis of pre-restoration habitat use by Chinook salmon in the delta-flats and nearshore regions of the Nisqually River Estuary

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Lind-Null, Angie; Larsen, Kim

2010-01-01

The Nisqually Fall Chinook population is one of 27 salmon stocks in the Puget Sound (Washington) evolutionarily significant unit listed as threatened under the federal Endangered Species Act (ESA). Extensive restoration of the Nisqually River delta ecosystem is currently taking place to assist in recovery of the stock as juvenile Fall Chinook salmon are dependent on the estuary. A pre-restoration baseline that includes the characterization of life history strategies, estuary residence times, growth rates, and habitat use is needed to evaluate the potential response of hatchery and natural origin Chinook salmon to restoration efforts and to determine restoration success. Otolith analysis was selected as a tool to examine Chinook salmon life history, growth, and residence in the Nisqually River estuary. Previously funded work on samples collected in 2004 (marked and unmarked) and 2005 (unmarked only) partially established a juvenile baseline on growth rates and length of residence associated with various habitats (freshwater, forested riverine tidal, emergent forested transition, estuarine emergent marsh, delta-flats and nearshore). However, residence times and growth rates for the delta-flats (DF) and nearshore (NS) habitats have been minimally documented due to small sample sizes. The purpose of the current study is to incorporate otolith microstructural analysis using otoliths from fish collected within the DF and NS habitats during sampling years 2004-08 to increase sample size and further evaluate between-year variation in otolith microstructure. Our results from this analysis indicated the delta-flats check (DFCK) on unmarked and marked Chinook samples in 2005-08 varied slightly in appearance from that seen on samples previously analyzed only from 2004. A fry migrant life history was observed on otoliths of unmarked Chinook collected in 2005, 2007, and 2008. Generally, freshwater mean increment width of unmarked fish, on average, was smaller compared to marked

Behaviour of wintering Tundra Swans Cygnus columbianus columbianus at the Eel River delta and Humboldt Bay, California, USA

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Black, Jeffrey M.; Gress, Carol; Byers, Jacob W.; Jennings, Emily; Ely, Craig R.

2010-01-01

Tundra Swan Cygnus columbianus columbinanus phenology and behaviour at the Eel River delta and southern Humboldt Bay in northern California, USA, is described. Counts made each January from 1963 onwards peaked at 1,502 swans in 1988. Monthly counts recorded during the 2006/07 and 2008/09 winters peaked in February, at 1,033 and 772 swans respectively. Swans roosted on ephemeral ponds at the Humboldt Bay National Wildlife Refuge, on ephemeral ponds within grassland pastures in the vicinity of the Refuge, and perhaps also used the Eel River as a roost. Flights between Refuge roosts and the pastures and ponds occurred in the two hours after sunrise and before dark. In winters 2008/09 and 2009/10, the percentage of cygnets in the flocks was 10.6% and 21.4% respectively, and increased to =31% cygnets each year after most swans had departed from the area in March. Average brood size in 2009/10 was 2.1 cygnets. Daily activities consisted of foraging (44.9% of activities recorded), comfort behaviour (22.1%), locomotion (16.2%) and vigilance (15.5%). Eight neck-collared swans identified in the wintering flock were marked at four locations in different parts of Alaska, up to 1,300 km apart.

SEAWARD DRIFT OF THE PONTIC SHAD LARVAE (ALOSA PONTICA) AND THE INFLUENCE OF DANUBE RIVER HYDROLOGY ON THEIR TRAVEL PATH THROUGH THE DANUBE DELTA SYSTEM.

OpenAIRE

NAVODARU I.

2001-01-01

The Pontic shad lives in the northwestern part of the Black Sea. It migrates in the Danube River for spawning. The larvae drift passively towards the sea when they reach the life stage ranging from pre-larvae to post-larvae. During the larval stage the Pontic shad is floating, mainly in the 0-50 cm upper layer of river. Upstream of the Danube Delta, in the straight sector of the river, alosids are distributed mostly towards the middle of the river, where the water velocity is higher. In the c...

Erosion of the Mekong delta: the role of human activities

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Anthony, E.; Dussouillez, P.; Goichot, M.; Brunier, G.; Dolique, F.; Nguyen, V.; Loisel, H.; Mangin, A.; Vantrepotte, V.

2013-12-01

River deltas are threatened by dams, dykes, flow channelling, and aggregate extraction. These activities outweigh climate change and sea-level rise in causing delta vulnerability1, and will aggravate the impacts to be expected from these effects2. We show here from analysis of: (1) delta channel morphology and sediment budgets, and (2) satellite imagery, that the Mekong delta, considered as the world's third largest, and hitherto strongly prograding, is now in a phase of large-scale erosion. We discuss the mechanistic links involved in erosion and the way these are related to human activities. High-resolution (2.5 m) SPOT 5 images for the years 2003, 2007, 2011/12 covering 405 km of the delta shoreline show an overall retreat rate of over 8 m a year. 75% of the analysed shoreline, i.e., the muddy western sector, is now retreating at rates exceeding 50 m a year in places. The sandy river-mouth sector maintains a semblance of stability, but with strong variations. We attribute erosion to a cascade of morphosedimentary changes linked to sediment mining from the deltaic channels and upstream dam interception. We estimated from Meris satellite imagery an annual 5% decrease in surface suspended concentrations exiting at the mouths of the Mekong over the period 2003-2011 that may reflect increased trapping of mud behind dams in China. We also infer modification of river-mouth and coastal mud storage patterns resulting from a loss of ca. 200 million m3 of delta channel sediments between 1998 and 2008 from aggregate extraction. Dykes have been shown to result in increased channel flow velocities during the high-discharge monsoon season, favouring further channel deepening3. Stronger river-mouth outflow velocities during this season may be leading to export of a greater proportion of mud far offshore of the coastal longshore transport corridor that ensured mud supply to, and past progradation of, the muddy western coast. In contrast, greater seawater penetration in the

Research on the Synergy Degree of China Yangtze River Delta Region Technology Innovation System Evolution from the Perspective of Technology Innovation Chain

Directory of Open Access Journals (Sweden)

Xu Bin Feng

2014-08-01

Full Text Available Abstract: This paper divides technology innovation system into research and development input subsystem, technology research and development subsystem and technology application subsystem from the perspective of technology innovation chain, combining with the system theory. Then selects the corresponding ordinal variables, makes an empirical analysis to the synergy degree of Yangtze River delta regional technology innovation system evolution by complex system synergy degree model which based on the data of 2002-2009. The results show that the development of synergy degree of the technology innovation system appears a rising trend and the technology application subsystem is the key factor of direction and degree of synergy development in the evolution process of regional technology innovation system in the Yangtze River Delta of China. Finally, this paper analyzes the characteristics and causes of synergy degree’s evolution, and puts forward the corresponding policy recommendations to different problems.

Evolution of the Parnaíba Delta (NE Brazil) during the late Holocene

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Szczygielski, Agata; Stattegger, Karl; Schwarzer, Klaus; da Silva, André Giskard Aquino; Vital, Helenice; Koenig, Juliane

2015-04-01

Sedimentary processes and the evolution of the wave- and tide-dominated, asymmetric Parnaíba Delta during the late Holocene were investigated based on geochemical and sedimentological analyses of sediment cores collected in 2010, as well as satellite images and historical maps. This is a rare case of pristine deltas essentially unaffected by human activities worldwide. The lowermost part of the main Parnaíba River distributary exhibits several low-sinuosity bends and several anastomosing bifurcation patterns in the east, whereas three NW-SE-oriented tidal channels drain a large mangrove area in the west. Dating of various materials in sediment cores from the tidal flats, tidal channels and supratidal marshes revealed that the oldest sediment (4,853 to 4,228 cal. years BP) is paleo-mangrove soil from the main river distributary. Present-day mangroves and marshes up to 200 years old exhibit high sedimentation rates reaching 3.4 cm/year. The asymmetry of the delta is explained not only by the wind- and wave-induced westward-directed longshore drift but also by neotectonic processes, as revealed by satellite images. Faulting and eastward tilting may have triggered delta lobe switching from west to east. This would explain the erosional character and unusual updrift orientation of the main river-mouth channel. Consistent with existing knowledge on mangrove ecosystems worldwide, sediment carbon and nitrogen signatures lie in the range of freshwater or marine dissolved organic carbon and C3 terrestrial plants. In the western tidal channels, the low Corg/Ntot ratios (16-21) of young mangrove soil (deposited in the last 16 years) reflect a stronger influence of marine plants compared to older mangroves (1,390-1,525 cal. years BP; ratios of 20-37). Thus, there would have been a greater influence of the Parnaíba River on tidal-channel sedimentology 1,400 to 1,500 years ago, entailing a natural connection between the present-day tidal channels and the river in ancient times

Connecting large-scale coastal behaviour with coastal management of the Rhône delta

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Sabatier, François; Samat, Olivier; Ullmann, Albin; Suanez, Serge

2009-06-01

The aim of this paper is to connect the Large Scale Coastal Behaviour (LSCB) of the Rhône delta (shoreface sediment budget, river sediment input to the beaches, climatic change) with the impact and efficiency of hard engineering coastal structures. The analysis of the 1895 to 1974 bathymetric maps as well as 2D modelling of the effect of wave blocking on longshore transport allows us to draw up a conceptual model of the LSCB of the Rhône delta. The river sand input, settled in the mouth area (prodeltaic lobe), favours the advance of adjacent beaches. There is however a very weak alongshore sand feeding of the non-adjacent beaches farther off the mouth. After a mouth shift, the prodelta is eroded by aggressive waves and the sand is moved alongshore to build spits. This conceptual model suggests that there is a "timeshift" between the input of river sediments to the sea and the build up of a beach (nonadjacent to the mouth). Nowadays, as the river channels are controlled by dykes and human interventions, a river shift is not possible. It thus appears unlikely that the river sediments can supply the beaches of the Rhône delta coast. Under these conditions, we must expect that the problems of erosion will continue at Saintes-Maries-de-la-Mer and on the Faraman shore, in areas with chronic erosion where the shoreline retreat has been partially stopped by hard engineering practices in the 1980s. Therefore, these artificially stabilised sectors remain potentially under threat because of profile steepening and downdrift erosion evidenced in this paper by bathymetric profile measurements. In the long-term (1905 to 2003), the temporal analysis of the storm surges and the sea level show very weak but reliable increasing trends. Thus, these climatic agents will be more aggressive on the beaches and on the coastal structures calling their efficiency into question. We also evidence that the hard engineering structures were built in a favourable climatic context during the

Influence of agricultural practice on trace metals in soils and vegetation in the water conservation area along the East River (Dongjiang River), South China

Energy Technology Data Exchange (ETDEWEB)

Luo, Chunling, E-mail: clluo@gig.ac.cn [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Yang, Renxiu [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Wang, Yan; Li, Jun; Zhang, Gan [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Li, Xiangdong [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

2012-08-01

Dongjiang (East River) is the key resource of potable water for the Pearl River Delta region, South China. Although industrial activities are limited in the water conservation area along this river, agriculture is very intensive. The present study evaluated trace metals in four soils under different cultivation. The total concentrations of trace metals decreased in the order orchard soil > vegetable soil > paddy soil > natural soil, reflecting decreasing inputs of agrochemicals to soils. Relatively high concentrations of Cd were recorded in the 60-cm soil profiles. The {sup 206}Pb/{sup 207}Pb ratio in the above-ground tissues of plant was significantly lower than their corresponding soils. In combination with the low transfer factor of Pb from soil to plant shoots, atmospheric deposition is probably a major pathway for Pb to enter plant leaves. Regular monitoring on the soil quality in this area is recommended for the safety of water resource and agricultural products. - Highlights: Black-Right-Pointing-Pointer Soil Cd exceeded the upper limit of Chinese standard for agricultural soils. Black-Right-Pointing-Pointer Relatively high concentrations of Cd were recorded in the 60-cm soil profiles. Black-Right-Pointing-Pointer Agricultural soil had higher concentrations of metals and lower {sup 206}Pb/{sup 207}Pb ratios. Black-Right-Pointing-Pointer Pb in above-ground tissues of plant was more anthropogenic than soil. Black-Right-Pointing-Pointer Atmospheric deposition may be a major pathway for Pb to enter plant leaves.

Quantification of surface water volume changes in the Mackenzie Delta using satellite multi-mission data

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Normandin, Cassandra; Frappart, Frédéric; Lubac, Bertrand; Bélanger, Simon; Marieu, Vincent; Blarel, Fabien; Robinet, Arthur; Guiastrennec-Faugas, Léa

2018-02-01

Quantification of surface water storage in extensive floodplains and their dynamics are crucial for a better understanding of global hydrological and biogeochemical cycles. In this study, we present estimates of both surface water extent and storage combining multi-mission remotely sensed observations and their temporal evolution over more than 15 years in the Mackenzie Delta. The Mackenzie Delta is located in the northwest of Canada and is the second largest delta in the Arctic Ocean. The delta is frozen from October to May and the recurrent ice break-up provokes an increase in the river's flows. Thus, this phenomenon causes intensive floods along the delta every year, with dramatic environmental impacts. In this study, the dynamics of surface water extent and volume are analysed from 2000 to 2015 by combining multi-satellite information from MODIS multispectral images at 500 m spatial resolution and river stages derived from ERS-2 (1995-2003), ENVISAT (2002-2010) and SARAL (since 2013) altimetry data. The surface water extent (permanent water and flooded area) peaked in June with an area of 9600 km2 (±200 km2) on average, representing approximately 70 % of the delta's total surface. Altimetry-based water levels exhibit annual amplitudes ranging from 4 m in the downstream part to more than 10 m in the upstream part of the Mackenzie Delta. A high overall correlation between the satellite-derived and in situ water heights (R > 0.84) is found for the three altimetry missions. Finally, using altimetry-based water levels and MODIS-derived surface water extents, maps of interpolated water heights over the surface water extents are produced. Results indicate a high variability of the water height magnitude that can reach 10 m compared to the lowest water height in the upstream part of the delta during the flood peak in June. Furthermore, the total surface water volume is estimated and shows an annual variation of approximately 8.5 km3 during the whole study period, with

Effects of drought on birds and riparian vegetation in the Colorado River Delta, Mexico

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Hinojosa-Huerta, Osvel; Nagler, Pamela L.; Carrillo-Guererro, Yamilett K.; Glenn, Edward P.

2013-01-01

The riparian corridor in the delta of the Colorado River in Mexico supports internationally important bird habitat. The vegetation is maintained by surface flows from the U.S. and Mexico and by a high, non-saline aquifer into which the dominant phreatophytic shrubs and trees are rooted. We studied the effects of a regional drought on riparian vegetation and avian abundance and diversity from 2002 to 2007, during which time surface flows were markedly reduced compared to the period from 1995 to 2002. Reduced surface flows led to a reduction in native tree cover but an increase in shrub cover, mostly due to an increase in Tamarix spp., an introduced halophytic shrub, and a reduction in Populus fremontii and Salix gooddingii trees. However, overall vegetation cover was unchanged at about 70%. Overall bird density and diversity were also unchanged, but riparian-obligate species tended to decrease in abundance, and generalist species increased. Although reduction in surface flows reduced habitat value and negatively impacted riparian-obligate bird species, portions of the riparian zone exhibited resilience. Surface flows are required to reduce soil salt levels and germinate new cohorts of native trees, but the main source of water supporting this ecosystem is the aquifer, derived from underflows from irrigated fields in the U.S. and Mexico. The long-term prospects for delta riparian habitats are uncertain due to expected reduced flows of river water from climate change, and land use practices that will reduce underflows to the riparian aquifer and increase salinity levels. Active restoration programs would be needed if these habitats are to be preserved for the future.

Connectivity of Multi-Channel Fluvial Systems: A Comparison of Topology Metrics for Braided Rivers and Delta Networks

Science.gov (United States)

Tejedor, A.; Marra, W. A.; Addink, E. A.; Foufoula-Georgiou, E.; Kleinhans, M. G.

2016-12-01

Advancing quantitative understanding of the structure and dynamics of complex networks has transformed research in many fields as diverse as protein interactions in a cell to page connectivity in the World Wide Web and relationships in human societies. However, Geosciences have not benefited much from this new conceptual framework, although connectivity is at the center of many processes in hydro-geomorphology. One of the first efforts in this direction was the seminal work of Smart and Moruzzi (1971), proposing the use of graph theory for studying the intricate structure of delta channel networks. In recent years, this preliminary work has precipitated in a body of research that examines the connectivity of multiple-channel fluvial systems, such as delta networks and braided rivers. In this work, we compare two approaches recently introduced in the literature: (1) Marra et al. (2014) utilized network centrality measures to identify important channels in a braided section of the Jamuna River, and used the changes of bifurcations within the network over time to explain the overall river evolution; and (2) Tejedor et al. (2015a,b) developed a set of metrics to characterize the complexity of deltaic channel networks, as well as defined a vulnerability index that quantifies the relative change of sediment and water delivery to the shoreline outlets in response to upstream perturbations. Here we present a comparative analysis of metrics of centrality and vulnerability applied to both braided and deltaic channel networks to depict critical channels in those systems, i.e., channels where a change would contribute more substantially to overall system changes, and to understand what attributes of interest in a channel network are most succinctly depicted in what metrics. Marra, W. A., Kleinhans, M. G., & Addink, E. A. (2014). Earth Surface Processes and Landforms, doi:10.1002/esp.3482Smart, J. S., and V. L. Moruzzi (1971), Quantitative properties of delta channel networks

The fate of river organic carbon in coastal areas: A study in the Rhône River delta using multiple isotopic (δ13C, Δ14C) and organic tracers

Science.gov (United States)

Cathalot, C.; Rabouille, C.; Tisnérat-Laborde, N.; Toussaint, F.; Kerhervé, P.; Buscail, R.; Loftis, K.; Sun, M.-Y.; Tronczynski, J.; Azoury, S.; Lansard, B.; Treignier, C.; Pastor, L.; Tesi, T.

2013-10-01

A significant fraction of the global carbon flux to the ocean occurs in River-dominated Ocean Margins (RiOMar) although large uncertainties remain in the cycle of organic matter (OM) in these systems. In particular, the OM sources and residence time have not been well clarified. Surface (0-1 cm) and sub-surface (3-4 cm) sediments and water column particles (bottom and intermediate depth) from the Rhône River delta system were collected in June 2005 and in April 2007 for a multi-proxy study. Lignin phenols, black carbon (BC), proto-kerogen/BC mixture, polycyclic aromatic hydrocarbons (PAHs), carbon stable isotope (δ13COC), and radiocarbon measurements (Δ14COC) were carried out to characterize the source of sedimentary organic material and to address degradation and transport processes. The bulk OM in the prodelta sediment appears to have a predominantly modern terrigenous origin with a significant contribution of modern vascular C3 plant detritus (Δ14COC = 27.9‰, δ13COC = -27.4‰). In contrast, the adjacent continental shelf, below the river plume, seems to be dominated by aged OM (Δ14COC = -400‰, δ13COC = -24.2‰), and shows no evidence of dilution and/or replacement by freshly produced marine carbon. Our data suggest an important contribution of black carbon (50% of OC) in the continental shelf sediments. Selective degradation processes occur along the main dispersal sediment system, promoting the loss of a modern terrestrial OM but also proto-kerogen-like OM. In addition, we hypothesize that during the transport across the shelf, a long term resuspension/deposition loop induces efficient long term degradation processes able to rework such refractory-like material until the OC is protected by the mineral matrix of particles.

Changes in sediment volume in Alder Lake, Nisqually River Basin, Washington, 1945-2011

Science.gov (United States)

Czuba, Jonathan A.; Olsen, Theresa D.; Czuba, Christiana R.; Magirl, Christopher S.; Gish, Casey C.

2012-01-01

The Nisqually River drains the southwest slopes of Mount Rainier, a glaciated stratovolcano in the Cascade Range of western Washington. The Nisqually River was impounded behind Alder Dam when the dam was completed in 1945 and formed Alder Lake. This report quantifies the volume of sediment deposited by the Nisqually and Little Nisqually Rivers in their respective deltas in Alder Lake since 1945. Four digital elevation surfaces were generated from historical contour maps from 1945, 1956, and 1985, and a bathymetric survey from 2011. These surfaces were used to compute changes in sediment volume since 1945. Estimates of the volume of sediment deposited in Alder Lake between 1945 and 2011 were focused in three areas: (1) the Nisqually River delta, (2) the main body of Alder Lake, along a 40-meter wide corridor of the pre-dam Nisqually River, and (3) the Little Nisqually River delta. In each of these areas the net deposition over the 66-year period was 42,000,000 ± 4,000,000 cubic meters (m3), 2,000,000 ± 600,000 m3, and 310,000 ± 110,000 m3, respectively. These volumes correspond to annual rates of accumulation of 630,000 ± 60,000 m3/yr, 33,000 ± 9,000 m3/yr, and 4,700 ± 1,600 m3/yr, respectively. The annual sediment yield of the Nisqually (1,100 ± 100 cubic meters per year per square kilometer [(m3/yr)/km2]) and Little Nisqually River basins [70 ± 24 (m3/yr)/km2] provides insight into the yield of two basins with different land cover and geomorphic processes. These estimates suggest that a basin draining a glaciated stratovolcano yields approximately 15 times more sediment than a basin draining forested uplands in the Cascade Range. Given the cumulative net change in sediment volume in the Nisqually River delta in Alder Lake, the total capacity of Alder Lake since 1945 decreased about 3 percent by 1956, 8 percent by 1985, and 15 percent by 2011.

Enhancing mud supply from the Lower Missouri River to the Mississippi River Delta USA: Dam bypassing and coastal restoration

Science.gov (United States)

Kemp, G. Paul; Day, John W.; Rogers, J. David; Giosan, Liviu; Peyronnin, Natalie

2016-12-01

Sand transport to the Mississippi River Delta (MRD) remains sufficient to build wetlands in shallow, sheltered coastal bays fed by engineered diversions on the Mississippi River (MR) and its Atchafalaya River (AR) distributary. But suspended mud (silt & clay) flux to the coast has dropped from a mean of 390 Mt y-1 in the early 1950s, to 100 Mt y-1 since 1970. This fine-grained sediment travels deeper into receiving estuarine basins and plays a critical role in sustaining existing marshes. Virtually all of the 300 Mt y-1 of missing mud once flowed from the Missouri River (MOR) Basin before nearly 100 dams were built as part of the Pick-Sloan water development project. About 100 Mt y-1 is now intercepted by main-stem Upper MOR dams closed in 1953. But the remaining 200 Mt y-1 is trapped by impoundments built on tributaries to the Lower MOR in the 1950s and 1960s. Sediment flux during the post-dam high MOR discharge years of 1973, 1993 and 2011 approached pre-dam levels when tributaries to the Lower MOR, including the Platte and Kansas Rivers, contributed to flood flows. West bank tributaries drain a vast, arid part of the Great Plains, while those entering from the east bank traverse the lowlands of the MOR floodplain. Both provinces are dominated by highly erodible loess soils. Staunching the continued decline in MR fine-grained sediment flux has assumed greater importance now that engineered diversions are being built to reconnect the Lowermost MR to the MRD. Tributary dam bypassing in the Lower MOR basin could increase mud supply to the MRD by 100-200 Mt y-1 within 1-2 decades. Such emergency measures to save the MRD are compatible with objectives of the Missouri River Restoration and Platte River Recovery Programs to restore MOR riparian habitat for endangered species. Rapid mobilization to shunt fine-grained sediments past as many as 50 Lower MOR tributary dams in several U.S. states will undoubtedly require as much regional coordination and funding in the 21st

New evidence of Yangtze delta recession after closing of the Three Gorges Dam

Science.gov (United States)

Luo, X. X.; Yang, S. L.; Wang, R. S.; Zhang, C. Y.; Li, P.

2017-01-01

Many deltas are likely undergoing net erosion because of rapid decreases in riverine sediment supply and rising global sea levels. However, detecting erosion in subaqueous deltas is usually difficult because of the lack of bathymetric data. In this study, by comparing bathymetric data between 1981 and 2012 and surficial sediment grain sizes from the Yangtze subaqueous delta front over the last three decades, we found severe erosion and significant sediment coarsening in recent years since the construction of Three Gorges Dam (TGD), the largest dam in the world. We attributed these morphological and sedimentary variations mainly to the human-induced drastic decline of river sediment discharge. Combined with previous studies based on bathymetric data from different areas of the same delta, we theorize that the Yangtze subaqueous delta is experiencing overall (net) erosion, although local accumulation was also noted. We expect that the Yangtze sediment discharge will further decrease in the near future because of construction of new dams and delta recession will continue to occur. PMID:28145520

Delta Morphodynamics Matters! Ecosystem Services, Poverty and Morphodynamic Change in the Ganges-Brahmaputra Mega-Delta

Science.gov (United States)

Nicholls, R. J.; Adger, N.; Allan, A.; Darby, S. E.; Hutton, C.; Matthews, Z.; Rahman, M.; Whitehead, P. G.; Wolf, J.

2013-12-01

The world's deltas are probably the most vulnerable type of coastal environment, and they face multiple stresses in the coming decades. These stresses include, amongst others, local drivers due to land subsidence, population growth and urbanisation within the deltas, regional drivers due to changes in catchment management (e.g. upstream land use and dam construction), as well as global climate change impacts such as sea-level rise. At the same time, the ecosystem services of river deltas support high population densities, with around 14% of the global population inhabiting deltas. A large proportion of these people experience extremes of poverty and they are therefore severely exposed to vulnerability from environmental and ecological stress and degradation. In areas close to or below the poverty boundary, both subsistence and cash elements of the economy tend to rely disproportionately heavily on ecosystem services which underpin livelihoods. Therefore, to sustainably manage delta environments they must be viewed as complex social-environmental systems where change is only partially driven by physical drivers such as sea level rise and climate change, and human-induced development activities are also critical. Here we outline a new conceptual framework for the development of methods to understand and characterise the key drivers of change in ecosystem services that affect the environment and economic status of populous deltas, focusing specifically on the Ganges-Brahmaputra-Meghna (GBM) mega-delta. The GBM delta is characterised by densely populated coastal lowlands with significant poverty, with livelihoods supported to a large extent by natural ecosystems such as the Sunderbahns (the largest mangrove forest in the world). However, the GBM delta is under severe development pressure due to many growing cities. At present the importance of ecosystems services to poverty and livelihoods is poorly understood. This is due to due to the complexity of interactions

Improving Aquatic Plant Management in the California Sacramento-San Joaquin Delta

Science.gov (United States)

Bubenheim, David L.; Potter, Chris

2018-01-01

Management of aquatic weeds in complex watersheds and river systems present many challenges to assessment, planning and implementation of management practices for floating and submerged aquatic invasive plants. The Delta Region Areawide Aquatic Weed Project (DRAAWP), a USDA sponsored area-wide project, is working to enhance planning, decision-making and operational efficiency in the California Sacramento-San Joaquin Delta. Satellite and airborne remote sensing are used map (area coverage and biomass), direct operations, and assess management impacts on plant communities. Archived satellite records going are used to review results from previous climate and management events and aide in developing long-term strategies. Modeling at local and watershed scales provides insight into land-use effects on water quality. Plant growth models informed by remote sensing are being applied spatially across the Delta to balance location and type of aquatic plant, growth response to altered environments, phenology, environmental regulations, and economics in selection of management practices. Initial utilization of remote sensing tools developed for mapping of aquatic invasive weeds improved operational efficiency by focusing limited chemical use to strategic areas with high plant-control impact and incorporating mechanical harvesting when chemical use is restricted. These assessment methods provide a comprehensive and quantitative view of aquatic invasive plants communities in the California Delta, both spatial and temporal, informed by ecological understanding with the objective of improving management and assessment effectiveness.

CONTAMINATION STATUS OF CADMIUM IN DIFFERENT BIOTIC AND ABIOTIC COMPONENTS AROUND THE BIDHYADHARI RIVER OF INDIAN SUNDARBAN DELTA

Directory of Open Access Journals (Sweden)

Shivaji Bhattacharya

2014-12-01

Full Text Available This study has been conducted to estimate the concentration of total Cadmium (Cd in different biotic and abiotic substrates including human in and around the Bidyadhari river of Sundarban delta. Bidyadhari river presently serves as a sewage and excess rainwater outlet from Kolkata metropolitan and adjacent area, which ultimately empties at the Bay of Bengal. The study reveals that the Cd content in surface water of the river and ponds as well as ground water was generally high up to 0.294 µg/ml and 0.205 µg/ml respectively during most of the seasons, which was above the maximum permissible level for drinking water as per various national and international standards like Indian Standard Specification, European Union, WHO, USEPA etc. Though, range of Cd in sediment of the river and ponds was 0.025 to 0.281µg/g and 0.018 to 0.317µg/g respectively but that was considerably higher in grasses up to 0.324µg/g. Backyard hen demonstrated considerably high levels of Cd in their egg up to 0.247µg/g in albumen and 0.272 µg/g in yolk. Goat and cattle demonstrated Cd content in meat up to 0.295µg/g and milk up to 0.295µg/ml respectively which crosses the permissible levels recommended by different international standards. High Cd content in human hairs up to 1.11µg/g indicated considerably bioaccumulation of the metal in local inhabitants resides in the northern part of Sundarban mangrove eco-region. This whole observation may be considered as base line study to know the present status of Cd contamination and bioaccumulation in flora and fauna including humans in Sundarban mangrove eco-region to prepare mitigation planning against this carcinogen from the biota immediately.

Which Triggers Produce the Most Erosive, Frequent, and Longest Runout Turbidity Currents on Deltas?

Science.gov (United States)

Hizzett, J. L.; Hughes Clarke, J. E.; Sumner, E. J.; Cartigny, M. J. B.; Talling, P. J.; Clare, M. A.

2018-01-01

Subaerial rivers and turbidity currents are the two most voluminous sediment transport processes on our planet, and it is important to understand how they are linked offshore from river mouths. Previously, it was thought that slope failures or direct plunging of river floodwater (hyperpycnal flow) dominated the triggering of turbidity currents on delta fronts. Here we reanalyze the most detailed time-lapse monitoring yet of a submerged delta; comprising 93 surveys of the Squamish Delta in British Columbia, Canada. We show that most turbidity currents are triggered by settling of sediment from dilute surface river plumes, rather than landslides or hyperpycnal flows. Turbidity currents triggered by settling plumes occur frequently, run out as far as landslide-triggered events, and cause the greatest changes to delta and lobe morphology. For the first time, we show that settling from surface plumes can dominate the triggering of hazardous submarine flows and offshore sediment fluxes.

The origins and behaviour of carbon in a major semi-arid river, the Murray River, Australia, as constrained by carbon isotopes and hydrochemistry

Energy Technology Data Exchange (ETDEWEB)

Cartwright, Ian, E-mail: ian.cartwright@monash.edu [School of Geosciences, Monash University, Clayton, Vic. 3800 (Australia)] [National Centre for Groundwater Research and Training, Flinders University, Adelaide SA 5001 (Australia)

2010-11-15

Research highlights: {yields} {delta}{sup 13}C and concentrations of DIC in Murray River controlled by mineralisation of organic carbon and evasion. {yields} Murray River is source of atmospheric CO{sub 2}. {yields} In-river processing of carbon results in difficulties in determining carbon sources. - Abstract: {delta}{sup 13}C values of dissolved inorganic C (DIC), dissolved organic C (DOC), and particulate organic C (POC) together with {delta}{sup 18}O and {delta}{sup 2}H values of water, {delta}{sup 34}S values of dissolved SO{sub 4}, and major ion concentrations were measured in the Murray River and its tributaries between November 2005 and April 2007 to constrain the origins and behaviour of riverine C. {delta}{sup 13}C{sub DIC} values in the Murray River vary between -9.5 and -4.7 per mille with a range of <3 per mille within any sampling round. {delta}{sup 13}C{sub DIC} values of the tributaries are -11.0 per mille to -5.1 per mille. DIC concentrations of the Murray River increase from {approx}25 mg/L in the middle and upper reaches of the river to 45-55 mg/L in the lower reaches. However, the mass ratio of DIC as a proportion of the total dissolved solids (TDS) decreases from {approx}0.6-0.7 in the headwaters to {approx}0.2-0.3 in the lower reaches of the river, with similar downstream changes in DIC/Cl ratios. This precludes simple evaporative concentration of DIC and is interpreted as the river evading CO{sub 2}; this interpretation is consistent with pCO{sub 2} values that are in the range 550-11,200 ppm volume (ppmv), which are far higher than those in equilibrium with the atmosphere ({approx}360 ppmv). The {delta}{sup 13}C{sub DIC} values are similar to those that would be produced by the weathering of marine limestone ({delta}{sup 13}C {approx} 0 per mille). However, the lack of marine limestones cropping out in the Murray-Darling Basin and the relatively uniform {delta}{sup 13}C{sub DIC} values of the Murray River (even in upland reaches where the

Future Change to Tide-Influenced Deltas

Science.gov (United States)

Nienhuis, Jaap H.; Hoitink, A. J. F. (Ton); Törnqvist, Torbjörn E.

2018-04-01

Tides tend to widen deltaic channels and shape delta morphology. Here we present a predictive approach to assess a priori the effect of fluvial discharge and tides on deltaic channels. We show that downstream channel widening can be quantified by the ratio of the tide-driven discharge and the fluvial discharge, along with a second metric representing flow velocities. A test of our new theory on a selection of 72 deltas globally shows good correspondence to a wide range of environments, including wave-dominated deltas, river-dominated deltas, and alluvial estuaries. By quantitatively relating tides and fluvial discharge to delta morphology, we offer a first-order prediction of deltaic change that may be expected from altered delta hydrology. For example, we expect that reduced fluvial discharge in response to dam construction will lead to increased tidal intrusion followed by enhanced tide-driven sediment import into deltas, with implications for navigation and other human needs.

33 CFR 334.570 - Banana River near Orsino, Fla.; restricted area.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Banana River near Orsino, Fla... THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.570 Banana River near Orsino, Fla.; restricted area. (a) The area. That part of Banana River N of the NASA Banana River...

Hydrochemistry of surface water and groundwater in the shale bedrock, Cross River Basin and Niger Delta Region, Nigeria

Science.gov (United States)

Nganje, T. N.; Hursthouse, A. S.; Edet, Aniekan; Stirling, D.; Adamu, C. I.

2017-05-01

Water chemistry in the shale bedrock of the Cretaceous-Tertiary of the Cross River and Niger Delta hydrological basins has been investigated using major ions. To carry out a characterization of the water bearing units, 30 and 16 representatives surface and groundwater samples were collected. The evolution of the water is characterized by enhanced content of sodium, calcium and sulphate as a result of leaching of shale rock. The spatial changes in groundwater quality of the area shows an anomalous concentrations of ions in the central parts, while lower values characterize the eastern part of the basin covering Ogoja, Ikom and Odukpani areas. The values of total dissolved solids (TDS) and ions increases down gradient in the direction of groundwater flow. The dissolution of halite and gypsum explains part of the contained Na+, Ca2+, Cl- and SO4 2-, but other processes such as ion exchange, silicate weathering and pyrite oxidation also contribute to water composition. The assessment with contamination indicators such as TDS, hardness, chloride, nitrate and sulphate indicates that the water in area is suitable for human consumption in some locations. Modelling using MINTEQA2 program shows that the water from all the shale water bearing units are under saturated with respect to gypsum.

Towards a Comprehensive Framework for Adaptive Delta Management

NARCIS (Netherlands)

Marchand, M.; Ludwig, F.

2014-01-01

Deltas are dynamic landforms at the boundary of land and sea, involving intricate mazes of rivers and small waterways, wetlands, estuaries and coastal barrier islands. They are home to over half a billion people. Deltas are also home to rich ecosystems, such as mangroves and marshes. They are

River and river-related drainage area parameters for site investigation program

Energy Technology Data Exchange (ETDEWEB)

Blomqvist, P.; Brunberg, A.K. [Uppsala Univ. (Sweden). Dept. of Limnology; Brydsten, L. [Umeaa Univ. (Sweden). Dept. of Ecology and Environmental Science

2001-05-01

In this paper, a number of parameters of importance to a determination of the function of running waters as transport channels for material from the continents to the sea are presented. We have assumed that retention mechanisms of material in the river and in the riparian zone will be covered by special investigations but tried to create a platform for such investigations by quantification of the extension of different main habitats. The choice of parameters has been made so that also the nature conservation value of the river can be preliminary established, and includes a general description of the river type and the inherent ecosystem. The material links directly to that presented in a previous report concerning site investigation programmes for lakes. The parameters have been divided into five groups: 1) The location of the object relative important gradients in the surrounding nature; 2) The river catchment area and its major constituents; 3) The river morphometry; 4) The river ecosystem; 5) Human-induced damages to the river ecosystem. The first two groups, principally based on the climate, hydrology, geology and vegetation of the catchment area, represent parameters that can be used to establish the rarity and representativity of the system, and will in the context of site investigation program be used as a basis for generalisation of the results. The third group, the river morphometry parameters, are standard parameters for the outline of sampling programmes and for calculations of the physical extension of key habitats in the system. The fourth group, the ecosystem of the river, includes physical, chemical and biological parameters required for determination of the influence from the terrestrial ecosystem of the catchment area, nutrient status, distribution of different habitats, and presence of fish in the system. In the context of site investigation program, the parameters in these two groups will be used for budget calculations of the flow of energy and

River and river-related drainage area parameters for site investigation program

International Nuclear Information System (INIS)

Blomqvist, P.; Brunberg, A.K.; Brydsten, L.

2001-05-01

In this paper, a number of parameters of importance to a determination of the function of running waters as transport channels for material from the continents to the sea are presented. We have assumed that retention mechanisms of material in the river and in the riparian zone will be covered by special investigations but tried to create a platform for such investigations by quantification of the extension of different main habitats. The choice of parameters has been made so that also the nature conservation value of the river can be preliminary established, and includes a general description of the river type and the inherent ecosystem. The material links directly to that presented in a previous report concerning site investigation programmes for lakes. The parameters have been divided into five groups: 1) The location of the object relative important gradients in the surrounding nature; 2) The river catchment area and its major constituents; 3) The river morphometry; 4) The river ecosystem; 5) Human-induced damages to the river ecosystem. The first two groups, principally based on the climate, hydrology, geology and vegetation of the catchment area, represent parameters that can be used to establish the rarity and representativity of the system, and will in the context of site investigation program be used as a basis for generalisation of the results. The third group, the river morphometry parameters, are standard parameters for the outline of sampling programmes and for calculations of the physical extension of key habitats in the system. The fourth group, the ecosystem of the river, includes physical, chemical and biological parameters required for determination of the influence from the terrestrial ecosystem of the catchment area, nutrient status, distribution of different habitats, and presence of fish in the system. In the context of site investigation program, the parameters in these two groups will be used for budget calculations of the flow of energy and

A multi-disciplinary approach for the integrated assessment of multiple risks in delta areas.

Science.gov (United States)

Sperotto, Anna; Torresan, Silvia; Critto, Andrea; Marcomini, Antonio

2016-04-01

The assessment of climate change related risks is notoriously difficult due to the complex and uncertain combinations of hazardous events that might happen, the multiplicity of physical processes involved, the continuous changes and interactions of environmental and socio-economic systems. One important challenge lies in predicting and modelling cascades of natural and man -made hazard events which can be triggered by climate change, encompassing different spatial and temporal scales. Another regard the potentially difficult integration of environmental, social and economic disciplines in the multi-risk concept. Finally, the effective interaction between scientists and stakeholders is essential to ensure that multi-risk knowledge is translated into efficient adaptation and management strategies. The assessment is even more complex at the scale of deltaic systems which are particularly vulnerable to global environmental changes, due to the fragile equilibrium between the presence of valuable natural ecosystems and relevant economic activities. Improving our capacity to assess the combined effects of multiple hazards (e.g. sea-level rise, storm surges, reduction in sediment load, local subsidence, saltwater intrusion) is therefore essential to identify timely opportunities for adaptation. A holistic multi-risk approach is here proposed to integrate terminology, metrics and methodologies from different research fields (i.e. environmental, social and economic sciences) thus creating shared knowledge areas to advance multi risk assessment and management in delta regions. A first testing of the approach, including the application of Bayesian network analysis for the assessment of impacts of climate change on key natural systems (e.g. wetlands, protected areas, beaches) and socio-economic activities (e.g. agriculture, tourism), is applied in the Po river delta in Northern Italy. The approach is based on a bottom-up process involving local stakeholders early in different

Holocene Flexural Deformation over the Nile Delta: Evidence from Radar Interferometry

Science.gov (United States)

Gebremichael, E.; Sultan, M.; Becker, R.

2017-12-01

Isostatic adjustment and subsequent subsidence and uplift due to sediment and water loading and unloading mechanisms is one of the major factors that produce regional deformational patterns across river deltas. Using 84 Envisat ASAR scenes that were acquired (2004 - 2010) along three tracks and applying Persistent scatterer (PS) radar interferometric techniques, we documented flexural deformational patterns over the entire Nile Delta (length: 186 km; width: 240 km) of Egypt. The passive continental margin of Africa subsided from Jurassic time onwards due to isostatic loading creating an accommodation space and consequently, the deposition of relatively younger sediments on the oceanic crust. In river deltas, the flexural isostasy model dictates that a subsidence in the oceanic crust side should be balanced by a bulge (uplift) in the flanking regions. Using radar interferometry, we were able to identify the flexural deformation pattern and map its spatial extent over the northern and central Nile Delta region. Findings include: (1) the northern Nile Delta region (block) is separated from the southern delta region by an east-west trending, extensively faulted, hinge line that signifies the boundary between two deformational patterns (subsidence and uplift). It separates the highly subsiding (up to 9.8 mm/yr) northern delta block (up to 85 km long) from the nearly stable (0.4 mm/yr; averaged) southern delta block (up to 91 km long). The hinge line marks the end of the passive continental margin of Africa and the beginning of the oceanic crust of the Mediterranean. (2) We mapped the extent of a 20-40 km wide flexural uplift zone to the south of the hinge line. Within the flexural uplift zone (2.5 mm/yr; averaged), there is a gradual increase in uplift rate reaching peak value (up to 7 mm/yr) near the midpoint of the zone. (3) The uplift rate gradually decreases south of the flexure boundary reaching 0.3 mm/yr at the southern periphery of the delta. (4) The flexural

Recent changes (1973-2014 versus 1903-1972) in the flow regime of the Lower Paraná River and current fluvial pollution warnings in its Delta Biosphere Reserve.

Science.gov (United States)

Puig, Alba; Olguín Salinas, Héctor F; Borús, Juan A

2016-06-01

Alterations in flow regimes of large rivers may originate or increase risks to ecosystems and humans. The Paraná River basin (South America) undergoes human pressures (e.g., heavy damming in the upper basin, deforestation, and mixed pollution) that may affect the water quantity and quality of its terminal Delta (Argentina). In this study, after applying univariate and multivariate change-point detection and trend analyses to the daily data series of flows incoming to the Delta (Paraná-Santa Fe section), flow characteristics were compared by Indicators of Hydrologic Alteration (IHA) and Environmental Flow Components (EFC). Some flood characteristics were also compared from hydrometric levels in the middle Delta (San Pedro station). Chemical and microbiological water variables in the main rivers of the "Paraná Delta" Biosphere Reserve were examined during two extreme hydrologic years (October 2008 to July 2010) to detect potential risk factors in association with hydrologic conditions. In the Lower Paraná River, a historical period (1903-1972) and two more altered periods (1973-1999 wet period and 2000-2014 dry period) were identified. Flow duration curves evidenced different changes in both altered periods, reflecting the joint effect of climatic variability and human influence. The most evident alterations in the flow regime were the lack of record of the extreme-low-flow component, the attenuation of monthly flow seasonality, and the increase in the number of reversals (dry period) and in the variability of maximum and minimum flow dates. These alterations are consistent with the monthly and daily flow regulation by upstream dams evidenced by available data from the current dry period. In the middle Delta, the marked monthly seasonality in flood days decreased only in the wet period. The proportion between the number of flood days exceeding the evacuation level and that of those exceeding the warning level doubled in the wet period but decreased only

Distribution of polybrominated diphenyl ethers in sediments of the Pearl River Delta and adjacent South China Sea.

Science.gov (United States)

Mai, Bixian; Chen, Shejun; Luo, Xiaojun; Chen, Laiguo; Yang, Qingshu; Sheng, Guoying; Peng, Pingan; Fu, Jiamo; Zeng, Eddy Y

2005-05-15

Spatial and temporal distributions of polybrominated diphenyl ethers (PBDEs) in sediments of the Pearl River Delta (PRD) and adjacent South China Sea (SCS) of southern China were examined. A total of 66 surface sediment samples were collected and analyzed to determine the concentrations of 10 PBDE congeners (BDE-28, -47, -66, -100, -99, -154, -153, -138, -183, and -209). The concentrations of BDE-209 and SigmaPBDEs (defined as the sum of all targeted PBDE congeners except for BDE-209) ranged from 0.4 to 7340 and from 0.04 to 94.7 ng/g, respectively. The SigmaPBDEs concentrations were mostly transportation. The PBDE patterns in the SCS and Pearl River Estuary sediments were similar to those in sediments of the Zhujiang and Dongjiang Rivers, reflecting the widespread influence from local inputs. Analyses of two short sediment cores collected from the Pearl River Estuary showed that concentrations of BDE-209 rapidly increased in the upper layers of both cores, coincident with the growth of the electronics manufacturing capacities in the PRD region. The major sources of PBDEs were probably waste discharges from the cities of Guangzhou, Dongguan, and Shenzhen, the three fastest growing urban centers in the PRD.

Distribution, Health, and Development of Larval and Juvenile Lost River and Shortnose Suckers in the Williamson River Delta Restoration Project and Upper Klamath Lake, Oregon: 2008 Annual Data Summary

Science.gov (United States)

Burdick, Summer M.; Ottinger, Christopher; Brown, Daniel T.; VanderKooi, Scott P.; Robertson, Laura; Iwanowicz, Deborah

2009-01-01

Federally endangered Lost River sucker Deltistes luxatus and shortnose sucker Chasmistes brevirostris were once abundant throughout their range but populations have declined; they have been extirpated from several lakes, and may no longer reproduce in others. Poor recruitment into the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species, and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable rearing habitat. Within Upper Klamath Lake, a lack of marshes also may allow larval suckers to be swept from suitable rearing areas downstream into the seasonally anoxic waters of the Keno Reservoir. The Nature Conservancy (TNC) flooded about 3,600 acres to the north of the Williamson River mouth (Tulana Unit) in October 2007, and about 1,400 acres to the south and east of the Williamson River mouth (Goose Bay Unit) a year later, to retain larval suckers in Upper Klamath Lake, create nursery habitat for suckers, and improve water quality. In collaboration with TNC, the Bureau of Reclamation, and Oregon State University, we began a long-term collaborative research and monitoring program in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. Our approach includes two equally important aspects. One component is to describe habitat use and colonization processes by larval and juvenile suckers and non-sucker fish species. The second is to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report contains a summary of the first year of data collected as a part of this monitoring effort.

Use of stable nitrogen isotope signatures of riparian macrophytes as an indicator of anthropogenic N inputs to river ecosystems.

Science.gov (United States)

Kohzu, Ayato; Miyajima, Toshihiro; Tayasu, Ichiro; Yoshimizu, Chikage; Hyodo, Fujio; Matsui, Kiyoshi; Nakano, Takanori; Wada, Eitaro; Fujita, Noboru; Nagata, Toshi

2008-11-01

Deterioration of aquatic ecosystems resulting from enhanced anthropogenic N loading has become an issue of increasing concern worldwide, and methods are needed to trace sources of N in rivers. Because nitrate from sewage is enriched in 15N relative to nitrate from natural soils, delta(15)N values of stream nitrate (delta(15)Nnitrate) should be an appropriate index of anthropogenic N loading to rivers, as should the delta(15)N values of riparian plants (delta(15)Nplant) because they are consumers of nitrate. We determined the delta(15)N values of stream nitrate and six species of riparian macrophytes in 31 rivers in the Lake Biwa Basin in Japan. We then tested the correlation between these values and various land-use parameters, including the percentage of land used for residential and agricultural purposes as well as for natural areas. These delta(15)N values were significantly positively correlated with land use (%) that had a high N load (i.e., residential or agricultural use) and significantly negatively correlated with forest (%). These findings indicate that delta(15)N values of stream nitrate and riparian plants might be good indicators of anthropogenic inputs of nitrogen.

Water quality assessment of the rivers in bauxite mining area at ...

African Journals Online (AJOL)

Water quality assessment of the rivers in bauxite mining area at Kuantan Pahang. ... mining area. Water samples were collected at Kuantan River, Riau River, Pinang River and Pandan Rivers. ... All these rivvers were classified into class II based on INWQS and required conventional treatment for water supply purposes.

Hydrogeologic reconnaissance of the Mekong Delta in South Vietnam and Cambodia

Science.gov (United States)

Anderson, Henry R.

1978-01-01

The present report describes the results of a hydrogeologic reconnaissance in the Mekong Delta region by the writer, a hydrogeologist of the U.S. Geological Survey, while on assignment as an adviser to the Vietnamese Directorate of Water Supply from October 1968 to April 1970 under the auspices of the U.s. Agency for International Development. The delta of the Mekong River, comprising an area of about 70,000 square kilometres in South Vietnam and Cambodia, is an almost featureless plain rising gradually from sea level to about 5 metres above sea level at its apex 300 kilometres inland. Most of the shallow ground water in the Holocene Alluvium of the delta in Vietnam is brackish or saline down to depths of 50 to 100 metres. Moreover, in the Dong Thap Mu?oi (Plain of Reeds) the shallow ground water is alum-bearing. Locally, however, perched bodies of fresh ground water occur in ancient beach and dune ridges and are tapped by shallow dug wells or pits for village and domestic water supply. The Old Alluvium beneath the lower delta contains freshwater in some areas, notably in the Ca Mau Peninsula and adjacent areas, in the viciniy of Bau Xau near Saigon, and in the Tinh Long An area. Elsewhere in the lower delta both the Holocene and Old Alluvium may contain brackish or saline water from the land surface to depths of as much as 568 metres, as for example in Tinh Vinh Binh. Ground water in the outcrop area of Old Alluvium northwest of Saigon is generally fresh and potable, but high iron and low pH are locally troublesome. Although considerable exploratory drilling for ground water down to depths of as much as 568 metres has already been completed, large areas of the delta remain yet to be explored before full development of the ground-water potential can be realized. With careful development and controlled management to avoid saltwater contamination, however, it is estimated that freshwater aquifers could provide approximately 80 percent of existing needs for village

Mercury profiles in sediments of the Pearl River Estuary and the surrounding coastal area of South China

International Nuclear Information System (INIS)

Shi Jianbo; Ip, Carman C.M.; Zhang Gan; Jiang Guibin; Li Xiangdong

2010-01-01

The spatial and temporal variations of mercury (Hg) in sediments of the Pearl River Estuary (PRE) and the surrounding coastal area (South China Sea) were studied. In surface sediments, the concentrations of Hg ranged from 1.5 to 201 ng/g, with an average of 54.4 ng/g, displaying a decreasing trend with the distance from the estuary to the open sea. This pattern indicates that the anthropogenic emissions from the Pearl River Delta (PRD) region are probably the main sources of Hg in this coastal region. Using the 210 Pb dating technique, the historical changes in the concentrations and influxes of Hg in the last 100 years were also investigated. The variations in Hg influxes in sediment cores obviously correlate with the economic development and urbanization that has occurred the PRD region, especially in the last three decades. - The spatial and historical changes of Hg in sediment reflect the industrial development and urbanization of the region in south China.

Comparative Influences of Precipitation and River Stage on Groundwater Levels in Near-River Areas

Directory of Open Access Journals (Sweden)

Incheol Kim

2015-12-01

Full Text Available The sustainable performance of foundations of various urban buildings and infrastructures is strongly affected by groundwater level (GWL, as GWL causes changes in the stress state within soil. In the present study, the components affecting GWL were investigated, focusing on the effects of precipitation and river stage. These components were analyzed using a six-year database established for hydrological and groundwater monitoring data. Five study regions for which daily measured precipitation, river stage, and GWL data were available were compared. Different periods of precipitation, geographical characteristics, and local surface conditions were considered in the analysis. The results indicated that key influence components on GWL are different depending on the hydrological, geological, and geographical characteristics of the target regions. River stage had the strongest influence on GWL in urban areas near large rivers with a high ratio of paved surface. In rural areas, where the paved surface area ratio and soil permeability were low, the moving average showed a closer correlation to GWL than river stage. A moving average-based method to predict GWL variation with time was proposed for regions with a low ratio of paved surface area and low permeability soils.

The Relationship between Urban Sprawl and Farmland Displacement in the Pearl River Delta, China

Directory of Open Access Journals (Sweden)

Shiqiang Du

2013-12-01

Full Text Available China is rapidly urbanizing and will inevitably face trade-offs between promoting economic growth through further urbanization and protecting fertile farmland against accelerated urban expansion. This paper presents how this dilemma is being addressed in one of the most rapidly urbanizing regions in China, the Pearl River Delta (PRD, by means of assessing urban growth and farmland dynamic, as well as their complex relationships. Land use maps derived from Landsat imagery for 1990, 2000 and 2010 show a process of accelerated urban sprawl whereby built-up lands have more than quadrupled and scattered centers have merged into megacities. Nonetheless, the land use efficiency is considerably low and is declining relative to Hong Kong and Macau with respect to urban population density. On the other hand, the spreading of urban areas on farmlands causes new farmland reclamation and accelerated deforestation in the hilly surroundings. In addition, the displaced farmlands do not ensure food production because of both reclaiming farmlands on infertile lands and diversifying farming activities from grain production to market-oriented ones. The accelerated urbanization and farmland displacement are driven by profit-oriented development strategy and ineffective land use planning. Our findings demonstrate how spatial analysis can help to investigate the integrated effects of land policies on landscape.

Paleolimnological assessment of riverine and atmospheric pathways and sources of metal deposition at a floodplain lake (Slave River Delta, Northwest Territories, Canada)

Energy Technology Data Exchange (ETDEWEB)

MacDonald, Lauren A., E-mail: L7macdon@uwaterloo.ca [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Wiklund, Johan A. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Elmes, Matthew C.; Wolfe, Brent B. [Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, ON N2L 3C5 (Canada); Hall, Roland I., E-mail: rihall@uwaterloo.ca [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

2016-02-15

Growth of natural resource development in northern Canada has raised concerns about the effects on downstream aquatic ecosystems, but insufficient knowledge of pre-industrial baseline conditions continues to undermine ability of monitoring programs to distinguish industrial-derived contaminants from those supplied by natural processes. Here, we apply a novel paleolimnological approach to define pre-industrial baseline concentrations of 13 priority pollutant metals and vanadium and assess temporal changes, pathways and sources of these metals at a flood-prone lake (SD2) in the Slave River Delta (NWT, Canada) located ~ 500 km north of Alberta's oil sands development and ~ 140 km south of a former gold mine at Yellowknife, NWT. Results identify that metal concentrations, normalized to lithium concentration, are not elevated in sediments deposited during intervals of high flood influence or low flood influence since onset of oil sands development (post-1967) relative to the 1920–1967 baseline established at SD2. When compared to a previously defined baseline for the upstream Athabasca River, several metal-Li relations (Cd, Cr, Ni, Zn, V) in post-1967 sediments delivered by floodwaters appear to plot along a different trajectory, suggesting that the Peace and Slave River watersheds are important natural sources of metal deposition at the Slave River Delta. However, analysis revealed unusually high concentrations of As deposited during the 1950s, an interval of very low flood influence at SD2, which corresponded closely with emission history of the Giant Mine gold smelter indicating a legacy of far-field atmospheric pollution. Our study demonstrates the potential for paleolimnological characterization of baseline conditions and detection of pollution from multiple pathways in floodplain ecosystems, but that knowledge of paleohydrological conditions is essential for interpretation of contaminant profiles. - Highlights: • We examine metal depositional history at a

Linear alkylbenzenes in riverine runoff of the Pearl River Delta (China) and their application as anthropogenic molecular markers in coastal environments

International Nuclear Information System (INIS)

Ni Honggang; Lu Fenghui; Wang Jizhong; Guan Yufeng; Luo Xianlin; Zeng, Eddy Y.

2008-01-01

The average concentrations of ΣLABs (sum of C 10 -C 13 -LABs) in runoff samples collected from the eight major riverine outlets of the Pearl River Delta (PRD) of China ranged from 1.4 to 6124 ng/L in the dissolved phase and from 0.01 to 11.4 μg/g dry weight in the particulate phase during March 2005-February 2006. The annual riverine flux of ΣLABs from the PRD to the coastal ocean was estimated at approximately 14 tons/yr. The inventories of ΣLABs in agricultural lands of Guangdong Province ranged from 313 to 1825 kg/yr. The early and late rice fields were the major sink of LABs, accounting for approximately 68% of total LABs inventory in agricultural lands. The social-economically estimated annual discharge of LABs from household detergents in the PRD was ∼696 tons/yr, more than an order of magnitude higher than that estimated from field measurements (about 14 tons/yr), which was attributed to several factors. - Occurrence of LABs in riverine runoff of the Pearl River Delta (China) was examined

Tissue distribution of organochlorine pesticides in fish collected from the Pearl River Delta, China: Implications for fishery input source and bioaccumulation

International Nuclear Information System (INIS)

Guo Ying; Meng Xiangzhou; Tang Honglei; Zeng, Eddy Y.

2008-01-01

Fish tissues from different fishery types (freshwater farmed, seawater farmed and seawater wild) were analyzed for organochlorine pesticides (OCPs), with the aim to further our understanding of bioaccumulation, and reflect the state of different fishery environments. Significantly higher ΣOCP levels were found in seawater farmed fish than others, and among three freshwater farmed species, the lowest levels occurred in filter-feeding fish (bighead carp). Liver contained the highest ΣOCP levels, while no significant differences were found among other tissues. Among DDT components, p,p'-DDT was abundant in seawater fish, while for freshwater fish, p,p'-DDE was the predominant congeners, except for northern snakehead (34% for p,p'-DDE and 30% for p,p'-DDT). The new source of DDTs to freshwater fish ponds was partly attributed to dicofol, whereas sewage discharged from the Pearl River Delta and anti-fouling paint were likely the DDTs sources to seawater farmed fish. - Occurrence of organochlorine pesticides in fish tissues was examined to assess input sources and modes of bioaccumulation in the Pearl River Delta, China

Using Remote Sensing Data to Parameterize Ice Jam Modeling for a Northern Inland Delta

Directory of Open Access Journals (Sweden)

Fan Zhang

2017-04-01

Full Text Available The Slave River is a northern river in Canada, with ice being an important component of its flow regime for at least half of the year. During the spring breakup period, ice jams and ice-jam flooding can occur in the Slave River Delta, which is of benefit for the replenishment of moisture and sediment required to maintain the ecological integrity of the delta. To better understand the ice jam processes that lead to flooding, as well as the replenishment of the delta, the one-dimensional hydraulic river ice model RIVICE was implemented to simulate and explore ice jam formation in the Slave River Delta. Incoming ice volume, a crucial input parameter for RIVICE, was determined by the novel approach of using MODIS space-born remote sensing imagery. Space-borne and air-borne remote sensing data were used to parameterize the upstream ice volume available for ice jamming. Gauged data was used to complement modeling calibration and validation. HEC-RAS, another one-dimensional hydrodynamic model, was used to determine ice volumes required for equilibrium jams and the upper limit of ice volume that a jam can sustain, as well as being used as a threshold for the volumes estimated by the dynamic ice jam simulations using RIVICE. Parameter sensitivity analysis shows that morphological and hydraulic properties have great impacts on the ice jam length and water depth in the Slave River Delta.

Investing for upgrading: the emergence of financial system of science and technology in China’s Pearl River Delta

OpenAIRE

XIAODONG WANG; CHRISTOF MORSCHER

2016-01-01

This article discusses the recent reform policy in China on setting up new financial system for supporting science and technology innovation. Based on the financial sector development in the Pearl River Delta in China’s Guangdong Province, especially Guangzhou, one pilot city of Chinese Science and Technology Financial System Reform, the article analyses the problems in financial system and makes some suggestion on how to restructure the financial system to meet the financial need of local em...

A gradient analysis on urban sprawl and urban landscape pattern between 1985 and 2000 in the Pearl River Delta, China

Science.gov (United States)

Dai, Erfu; Wu, Zhuo; Du, Xiaodian

2017-04-01

Urbanization is an irreversible trend worldwide, especially in rapidly developing China. Accelerated urbanization has resulted in rapid urban sprawl and urban landscape pattern changes. Quantifying the spatiotemporal dynamics of urban land use and landscape pattern not only can reveal the characteristics of social transfer and economic development, but also can provide insights into the driving mechanisms of land use changes. In this study, we integrated remote sensing (RS), geographic information system (GIS), landscape metrics, and gradient analysis to quantitatively compare the spatiotemporal dynamics of land use, urban sprawl, and landscape pattern for nine cities in the Pearl River Delta from 1985‒2000. For the whole study region, urbanization was obvious. The results show an increase in urban buildup land and shrinkage of cropland in the Pearl River Delta. However, the nine cities differed greatly in terms of the process and magnitude of urban sprawl for both the spatial and temporal dimensions. This was most evident for the cities of Guangzhou and Shenzhen. Gradient analysis on urban landscape changes could deepen understanding of the stages of urban development and provide a scientific foundation for future urban planning and land management strategies in China.

Passive microwave observations of inundation area and the area/stage relation in the Amazon River floodplain

International Nuclear Information System (INIS)

Sippel, S.J.; Hamilton, S.K.; Melack, J.M.; Novo, E.M.M.

1998-01-01

Inundation patterns in Amazon River floodplains are revealed by analysis of the 37GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer on the Nimbus-7 satellite. Flooded area is estimated at monthly intervals for January 1979 through August 1987 using mixing models that account for the major landscape units with distinctive microwave emission characteristics. Results are presented separately for 12 longitudinal reaches along the Amazon River main stem in Brazil as well as for three major tributaries (the Jurua, Purus and Madeira rivers). The total area along the Amazon River main stem that was flooded (including both floodplain and open water) varied between 19 000 and 91 000 km 2 . The correlation between flooded area and river stage is used to develop a predictive relationship and reconstruct regional inundation patterns in the floodplain of the Amazon River main stem over the past 94 years of stage records (1903± 1996). The mean flooded area along the Amazon River during this 94-year period was 46 800 km 2 , of which the openwater surfaces of river channels and floodplain lakes comprised about 20 700 km 2 . (author)

Integrated Socio-Environmental Assessment of Deltas to Support Strategic Planning and Management

Science.gov (United States)

Nicholls, R. J.; Lázár, A. N.; Hutton, C.; Adams, H.; Salehin, M.; Rahman, M. M.

2016-12-01

Deltas are some of the most densely populated areas in the world, as exemplified by the coastal zone of Bangladesh which has a rural population densities of >1,000 people/km2. These people's livelihoods and food security are strongly dependent on natural resources which are influenced by multiple drivers. These include climate variability and change, subsidence, upstream river flow modifications, and land use changes such as polderisation and conversion of rice to shrimp production. Hydro-environmental changes, such as saline water intrusion and natural disasters (e.g. river flooding, cyclones and storm surges) have negative impacts that severely affect land use and livelihood opportunities of the coastal population. These changes can be especially detrimental for the well-being of the poorest households that are highly dependent on natural resources. These multiple drivers raise fundamental policy questions about how we might develop the delta over the coming decades. The Delta Dynamic Integrated Emulator (ΔDIEM) model has been developed to examine these interactions between the coupled bio-physical environment and the livelihoods of these poor populations in coastal Bangladesh. ΔDIEM allows the long-term analysis of the possible changes in this system by linking projected changes in physical processes (e.g. river flows, nutrients), with productivity (e.g. fish, rice), social processes (e.g. access, property rights, migration) and governance/management (e.g. fisheries, agriculture, water and land use management). A range of proposed interventions can be simulated. This integrated approach is designed to provide Bangladeshi policy makers with science-based evidence of possible development trajectories within the coastal delta plain over timescales up to 50 years, including comprehensive analysis of their different choices in terms of natural resource conservation, poverty, etc. This presentation will focus on key results and insights from the analysis.

Emission inventory of anthropogenic air pollutants and VOC species in the Yangtze River Delta region, China

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C. Huang

2011-05-01

Full Text Available The purpose of this study is to develop an emission inventory for major anthropogenic air pollutants and VOC species in the Yangtze River Delta (YRD region for the year 2007. A "bottom-up" methodology was adopted to compile the inventory based on major emission sources in the sixteen cities of this region. Results show that the emissions of SO₂, NO_x, CO, PM₁₀, PM_2.5, VOCs, and NH₃ in the YRD region for the year 2007 are 2392 kt, 2293 kt, 6697 kt, 3116 kt, 1511 kt, 2767 kt, and 459 kt, respectively. Ethylene, mp-xylene, o-xylene, toluene, 1,2,4-trimethylbenzene, 2,4-dimethylpentane, ethyl benzene, propylene, 1-pentene, and isoprene are the key species contributing 77 % to the total ozone formation potential (OFP. The spatial distribution of the emissions shows the emissions and OFPs are mainly concentrated in the urban and industrial areas along the Yangtze River and around Hangzhou Bay. The industrial sources, including power plants other fuel combustion facilities, and non-combustion processes contribute about 97 %, 86 %, 89 %, 91 %, and 69 % of the total SO₂, NO_x, PM₁₀, PM_2.5, and VOC emissions. Vehicles take up 12.3 % and 12.4 % of the NO_x and VOC emissions, respectively. Regarding OFPs, the chemical industry, domestic use of paint & printing, and gasoline vehicles contribute 38 %, 24 %, and 12 % to the ozone formation in the YRD region.

Climatic change in Mediterranean area

International Nuclear Information System (INIS)

Manos, A.

1991-01-01

United Nations Environmental Program (UNEP) studies on forecasted greenhouse climatic effects on the Mediterranean coastal and marine ecosystems and regional socio-economic framework have indicated the need for a concerted plan of protective and remedial action. The studies considered rises of 1.5 degrees in ambient temperature and 20 centimeters in sea level occurring before the year 2025. A regional, as opposed to a global area, study approach was adopted since the severity of climatic effects is expected to vary greatly from one part of the world to another. The specific areas investigated were the Po River Delta and Venezia Lagoon in Italy, the Nile Delta, Camargue, the Ebro Delta, the Tunisian National Park area, and the Thermaicos Gulf in Greece. The rise in average temperature is expected to negatively effect Mediterranean agricultural production and the coastal and marine ecosystems due to prolonged periods of drought and exceptional rainfall. It is suggested that a system of dikes be constructed to protect the coastal areas which are heavily dependent on tourism and agriculture

Sand transport, shear stress, and the building of a delta

Science.gov (United States)

Wagner, W.; Miller, K. L.; Hiatt, M. R.; Mohrig, D. C.

2017-12-01

River deltas distribute sediment to the coastal sea through a complex branching network of channels; however, the routing and storage of this sediment in and through the delta is poorly understood. We present results from field studies of the sediment and water transport through the branching Wax Lake Delta on the coast of Louisiana. Two channels studied, Main Pass and East Pass, maintain a near-equal total partitioning of flow and sediment. However, East Pass is narrower and has higher river velocities, lower tidal velocity fluctuations, less alluvial bed cover, and more sediment flux per unit width than Main Pass. We connect these differences to small differences in the geometry of the two channels and feedbacks between these differences. We link trends in measured sediment deposits to both measured and modeled shear velocities in Wax Lake Delta's channels and open water `islands' to understand how hydrologic processes shaped the sedimentary architecture of the delta. These connections define the sediment transport and deposition regimes in the WLD. We extend the results herein to suggest that the relationships between the available sediment and shear stress determines the basic planform of the Wax Lake Delta and cross-sectional geometries of its channels.

Heavy Metal Pollution Delineation Based on Uncertainty in a Coastal Industrial City in the Yangtze River Delta, China

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Bifeng Hu

2018-04-01

Full Text Available Assessing heavy metal pollution and delineating pollution are the bases for evaluating pollution and determining a cost-effective remediation plan. Most existing studies are based on the spatial distribution of pollutants but ignore related uncertainty. In this study, eight heavy-metal concentrations (Cr, Pb, Cd, Hg, Zn, Cu, Ni, and Zn were collected at 1040 sampling sites in a coastal industrial city in the Yangtze River Delta, China. The single pollution index (PI and Nemerow integrated pollution index (NIPI were calculated for every surface sample (0–20 cm to assess the degree of heavy metal pollution. Ordinary kriging (OK was used to map the spatial distribution of heavy metals content and NIPI. Then, we delineated composite heavy metal contamination based on the uncertainty produced by indicator kriging (IK. The results showed that mean values of all PIs and NIPIs were at safe levels. Heavy metals were most accumulated in the central portion of the study area. Based on IK, the spatial probability of composite heavy metal pollution was computed. The probability of composite contamination in the central core urban area was highest. A probability of 0.6 was found as the optimum probability threshold to delineate polluted areas from unpolluted areas for integrative heavy metal contamination. Results of pollution delineation based on uncertainty showed the proportion of false negative error areas was 6.34%, while the proportion of false positive error areas was 0.86%. The accuracy of the classification was 92.80%. This indicated the method we developed is a valuable tool for delineating heavy metal pollution.

Heavy Metal Pollution Delineation Based on Uncertainty in a Coastal Industrial City in the Yangtze River Delta, China.

Science.gov (United States)

Hu, Bifeng; Zhao, Ruiying; Chen, Songchao; Zhou, Yue; Jin, Bin; Li, Yan; Shi, Zhou

2018-04-10

Assessing heavy metal pollution and delineating pollution are the bases for evaluating pollution and determining a cost-effective remediation plan. Most existing studies are based on the spatial distribution of pollutants but ignore related uncertainty. In this study, eight heavy-metal concentrations (Cr, Pb, Cd, Hg, Zn, Cu, Ni, and Zn) were collected at 1040 sampling sites in a coastal industrial city in the Yangtze River Delta, China. The single pollution index (PI) and Nemerow integrated pollution index (NIPI) were calculated for every surface sample (0-20 cm) to assess the degree of heavy metal pollution. Ordinary kriging (OK) was used to map the spatial distribution of heavy metals content and NIPI. Then, we delineated composite heavy metal contamination based on the uncertainty produced by indicator kriging (IK). The results showed that mean values of all PIs and NIPIs were at safe levels. Heavy metals were most accumulated in the central portion of the study area. Based on IK, the spatial probability of composite heavy metal pollution was computed. The probability of composite contamination in the central core urban area was highest. A probability of 0.6 was found as the optimum probability threshold to delineate polluted areas from unpolluted areas for integrative heavy metal contamination. Results of pollution delineation based on uncertainty showed the proportion of false negative error areas was 6.34%, while the proportion of false positive error areas was 0.86%. The accuracy of the classification was 92.80%. This indicated the method we developed is a valuable tool for delineating heavy metal pollution.

Heavy Metal Pollution Delineation Based on Uncertainty in a Coastal Industrial City in the Yangtze River Delta, China

Science.gov (United States)

Zhao, Ruiying; Chen, Songchao; Zhou, Yue; Jin, Bin; Li, Yan

2018-01-01

Assessing heavy metal pollution and delineating pollution are the bases for evaluating pollution and determining a cost-effective remediation plan. Most existing studies are based on the spatial distribution of pollutants but ignore related uncertainty. In this study, eight heavy-metal concentrations (Cr, Pb, Cd, Hg, Zn, Cu, Ni, and Zn) were collected at 1040 sampling sites in a coastal industrial city in the Yangtze River Delta, China. The single pollution index (PI) and Nemerow integrated pollution index (NIPI) were calculated for every surface sample (0–20 cm) to assess the degree of heavy metal pollution. Ordinary kriging (OK) was used to map the spatial distribution of heavy metals content and NIPI. Then, we delineated composite heavy metal contamination based on the uncertainty produced by indicator kriging (IK). The results showed that mean values of all PIs and NIPIs were at safe levels. Heavy metals were most accumulated in the central portion of the study area. Based on IK, the spatial probability of composite heavy metal pollution was computed. The probability of composite contamination in the central core urban area was highest. A probability of 0.6 was found as the optimum probability threshold to delineate polluted areas from unpolluted areas for integrative heavy metal contamination. Results of pollution delineation based on uncertainty showed the proportion of false negative error areas was 6.34%, while the proportion of false positive error areas was 0.86%. The accuracy of the classification was 92.80%. This indicated the method we developed is a valuable tool for delineating heavy metal pollution. PMID:29642623

Human impacts on river water quality- comparative research in the catchment areas of the Tone River and the Mur River-

Science.gov (United States)

Kogure, K.

2013-12-01

Human activities in river basin affect river water quality as water discharges into river with pollutant after we use it. By detecting pollutants source, pathway, and influential factor of human activities, it will be possible to consider proper river basin management. In this study, material flow analysis was done first and then nutrient emission modeling by MONERIS was conducted. So as to clarify land use contribution and climate condition, comparison of Japanese and European river basin area has been made. The model MONERIS (MOdelling Nutrient Emissions in RIver Systems; Behrendt et al., 2000) was applied to estimate the nutrient emissions in the Danube river basin by point sources and various diffuse pathways. Work for the Mur River Basin in Austria was already carried out by the Institute of Water Quality, Resources and Waste Management at the Vienna University of Technology. This study treats data collection, modelling for the Tone River in Japan, and comparative analysis for these two river basins. The estimation of the nutrient emissions was carried out for 11 different sub catchment areas covering the Tone River Basin for the time period 2000 to 2006. TN emissions into the Tone river basin were 51 kt/y. 67% was via ground water and dominant for all sub catchments. Urban area was also important emission pathway. Human effect is observed in urban structure and agricultural activity. Water supply and sewer system make urban water cycle with pipeline structure. Excess evapotranspiration in arable land is also influential in water cycle. As share of arable land is 37% and there provides agricultural products, it is thought that N emission from agricultural activity is main pollution source. Assumption case of 10% N surplus was simulated and the result was 99% identical to the actual. Even though N surplus reduction does not show drastic impact on N emission, it is of importance to reduce excess of fertilization and to encourage effective agricultural activity

Rise and Fall of one of World's largest deltas; the Mekong delta in Vietnam

Science.gov (United States)

Minderhoud, P. S. J.; Eslami Arab, S.; Pham, H. V.; Erkens, G.; van der Vegt, M.; Oude Essink, G.; Stouthamer, E.; Hoekstra, P.

2017-12-01

The Mekong delta is the third's largest delta in the world. It is home to almost 20 million people and an important region for the food security in South East Asia. As most deltas, the Mekong delta is the dynamic result of a balance of sediment supply, sea level rise and subsidence, hosting a system of fresh and salt water dynamics. Ongoing urbanization, industrialization and intensification of agricultural practices in the delta, during the past decades, resulted in growing domestic, agricultural and industrial demands, and have led to a dramatic increase of fresh water use. Since the year 2000, the amount of fresh groundwater extracted from the subsurface increased by 500%. This accelerated delta subsidence as the groundwater system compacts, with current sinking rates exceeding global sea level rise up to an order of magnitude. These high sinking rates have greatly altered the sediment budget of the delta and, with over 50% of the Mekong delta surface elevated less than 1 meter above sea level, greatly increase vulnerability to flooding and storm surges and ultimately, permanent inundation. Furthermore, as the increasingly larger extractions rapidly reduce the fresh groundwater reserves, groundwater salinization subsequently increases. On top of that, dry season low-flows by the Mekong river cause record salt water intrusion in the delta's estuarine system, creating major problems for rice irrigation. We present the work of three years research by the Dutch-Vietnamese `Rise and Fall' project on land subsidence and salinization in both groundwater and surface water in the Vietnamese Mekong delta.

Oxygen and Hydrogen Isotopic Characteristics of the Kaveri River Surface Waters, Southern Peninsular India

International Nuclear Information System (INIS)

Achyuthan, Hema; Michelini, Marzia; Sengupta, Somasis D.; Kale, Vishwas S.; Stenni, Barbara; Flora, Onelio

2010-12-01

We present in this paper the spatial distribution of stable isotopic composition (δ 18 O and δD) of Kaveri River surface waters to understand how the evaporation and precipitation affect the isotopic signature and dynamics of surface river waters. In the southern peninsular India, Kaveri River is one of the longest tropical river. Our stable isotope data indicate that the upper Kaveri region is influenced strongly by the SW monsoon. There is a narrow range between the δ 18 O values found from the origin of the Kaveri River to its delta, and there is no significant orographic impact of the Western Ghats. A decreasing trend of d values is found along the course of the river. This is attributed to evaporation effects, which nevertheless are not very strong. This difference in deuterium excess due to evaporation is also an indication of the moisture recycling in the lower Kaveri area, which is primarily controlled by evaporation from the wetlands in the delta plain but also from the surface waters and as such from the rivers. (author)

Compliance of the Savannah River Site D-Area cooling system with environmental regulations

Energy Technology Data Exchange (ETDEWEB)

Specht, W.L.; Mackey, H.E.; Paller, M.H.; Wike, L.D.; Wilde, E.W. (eds.)

1990-08-01

This document presents information relating to a demonstration under Section 316(a) of the Clean Water Act for the 400-D Area cooling system at the Savannah River Site (SRS) near Aiken, South Carolina. The demonstration was mandated because the National Pollution Discharge Elimination System (NPDES) permit for SRS (SC0000175), granted on January 1, 1984, specified in-stream temperature limits in SRS streams of 32.2{degree}C and a {Delta}T limit of 2.8{degree}C above ambient. To achieve compliance with in-stream temperature limits, the Department of Energy (DOE) and the South Carolina Department of Health and Environmental Control (SCDHEC) entered into a Consent Order (84-4-W) which temporarily superseded the temperature requirements and identified a process for attaining compliance. The preferred option for achieving thermal compliance in Beaver Dam Creek consisted of increased flow, with mixing of the raw water basin overflow with the cooling water discharge during the summer months. Although this action can achieve instream temperatures of less than 32.2{degree}C, {Delta}T's still exceed 2.8{degree}C. Therefore, a 316 (a) Demonstration was initiated to determine whether a balanced indigenous biological community can be supported in the receiving stream with {Delta}T's in excess of 2.8{degree}C. A Biological Monitoring Program for Beaver Dam Creek was approved by SCDHEC in June 1988 and implemented in September 1988. The program monitored the water quality, habitat formers, zooplankton, macroinvertebrates, fish, other vertebrate wildlife and threatened and endangered species in Beaver Dam Creek for an 18-month period (September 1988-February 1990). This document summarizes information collected during the monitoring program and evaluates the data to determine whether Beaver Dam Creek presently supports a balanced indigenous biological community. 97 refs., 32 figs., 51 tabs.

77 FR 47331 - Regulated Navigation Area-New Haven Harbor, Quinnipiac River, Mill River, New Haven, CT; Pearl...

Science.gov (United States)

2012-08-08

...-AA11 Regulated Navigation Area--New Haven Harbor, Quinnipiac River, Mill River, New Haven, CT; Pearl... navigable waters of New Haven Harbor, Quinnipiac River and Mill River. The current RNA pertains only to the..., Quinnipiac River, and Mill River RNA. The proposed amendment would give the Captain of the Port Sector Long...

A Literature Review of Archaeological, Historical, and Paleontological Resources of the Sheyenne River Basin in North Dakota

Science.gov (United States)

1977-01-01

description of the Red River valley area was derived from Shay (1967: 231-237) and Scoby et. al. (1973). The Red River valley per se is flat except where...it is inter- rupted by the Sheyenne delta escarpment and the glacial Lake Agassiz shorelines ( Scoby et. al. 1973: 16). Surface drainage in the area is...very poor with runoff tending to collect in low lying areas ( Scoby et. al. 1973: 23). Prior to inten- sive drainage the area may have possessed many

Changing Course - The Moffatt & Nichol Team Solution- A "Systems Approach" to a consolidated and sustainable Lower Mississippi River Delta.

Science.gov (United States)

Hird, J. P.; Twilley, R.; Shelden, J.; Carney, J.; Georgiou, I. Y.; Agre, C.

2016-02-01

In response to the Changing Course Design Competition a bold, innovative "systems approach" to link the specific needs of the region's ecosystem, economy and community is proposed. "The Giving Delta" plan empowers the Mississippi River's seasonal natural flood pulse to maximized sediment capture in order to build and maintain wetlands, mitigate the effects of climate change and subsidence, and to slow the inevitable marine transgression of the Delta. Sediment capture is optimized by a series of sediment retention strategies and passive sediment diversion structures, as well as establishing a new deep draft navigation channel connected to the Barataria Bay shoreline littoral zone 40 miles north of the current channel.This paradigm shift from "flood control" to "controlled floods", connects the River's natural flood pulse to the coastal landscape. Using hydraulic residence time in the basin as a design and operational criteria for these controlled and passive structures, balances estuarine recovery and system response tolerance in order to determine the magnitude of the peak flows possible without intolerable salinity suppression in the receiving basins. Seasonal salinity gradients can be established that enable the diversion program to operate in harmony with and promote regional fisheries. On an annual basis, fisheries, communities and ecosystems will adapt to seasonally changing conditions. This plan is not designed to completely rebuild the wetlands that have been lost over the last century. Instead, the design encourages wetland adaptation to accelerated sea level rise in the coastal basins. With this plan, the basin ecologies would "self-organize" in parallel to the human settlement's natural ability to adapt and change to this long-term vision, as a new, consolidated and sustainable Delta emerges. By establishing a framework of implementation over 100 years, incremental adaptation minimizes individual uncertainty and costs within each human generation.

Investigation of isotopes and hydrological processes in Indus river system, Pakistan

International Nuclear Information System (INIS)

Manzoor Ahmad, M; Latif, Z.; Tariq, J.A.; Akram, W.; Rafique, M.

2009-11-01

Indus River, one of the longest rivers in the World, has five major eastern tributaries viz. Bias, Sutlej, Ravi, Chenab and Jhelum) while many small rivers join it from the right side among which Kabul River is the biggest with its main tributaries, the Swat, Panjkora and Kunar. All these main rivers are perennial and originate from the mountains. Basic sources of these rivers are snow melt, rainfall and under certain conditions seepage from the formations. Different water sources are labeled with different isotope signatures which are used as fingerprints for identifying source and movement of water, geochemical and/or hydrological processes, and dynamics (age of water). Monitoring of isotopes in rivers can also enhance understanding of the water cycle of large river basins and to assess impacts of environmental and climatic changes on the water cycle. Therefore, a national network of suitable stations was established for isotopic monitoring of river waters in Indus Basin with specific objectives to study temporal variations of isotopes (/sup 2/H, /sup 18/O and /sup 3/H), understand water cycles and hydrological processes in the catchments of these rivers, and to develop comprehensive database to support future isotope-based groundwater studies in the basin on recharge mechanism, water balance and monitoring of ongoing environmental changes. Water samples were collected during 2002-2006 on monthly basis from more than 20 stations at the major rivers and analyzed for /sup 18/O, /sup 2/H and /sup 3/H isotopes. Headwaters of main Indus River (Hunza, Gilgit and Kachura tributaries), which are generally snow melt, have the most depleted values of delta /sup 18/O (-14.5 to -11.0%) and delta /sup 2/H ( 106.1 to -72.6%) due to precipitation at very high altitude and very low temperatures. Generally these waters have low d-excess showing that the moisture source is from Indian Ocean. High d-excess of some winter (November-February) samples from Hunza and Gilgit indicates

The history and source of particulate 137Cs and 239,240Pu deposition in sediments of the Ob River Delta, Siberia

International Nuclear Information System (INIS)

Sayles, F.L.; Livingston, H.D.; Panteleyev, G.P.

1997-01-01

This paper presents the first results of a project designed to examine the transfer of particle-associated artificial radionuclides down the Ob River in Siberia to its delta over the past 5 decades. The main sources include fallout from atmospheric nuclear weapons tests and weapons complexes and test sites of the Former Soviet Union in or near the Ob watershed. The approach is to measure the accumulation of the radionuclides in undisturbed delta sediments - obtaining a record of their deposition over time. These records were found in sediments of shallow lakes apart from, and connected to, the main channel. Sediment cores were collected in the summer of 1994 using a shallow draft catamaran to reach these lakes from a support ship in the main channel. Measurements are presented on the depth distributions of 137 Cs and Pu isotopes and their inventories in a series of dated sediment cores - including one from a location in the Taz Estuary (which does not receive Ob River sediments). Sediment dating was carried out using the excess 210 Pb technique. The results obtained are compared with known information on the temporal history of releases from the various sources and characteristics of the isotopic composition of the sources. The results show that good records of radionuclide deposition indicate that the major fraction of 137 Cs and Pu isotopes deposited in these delta sediments comes from atmospheric nuclear weapons test fallout - both delivered directly from the atmosphere and from downstream transport of watershed sediments. No more than 25% of the observed inventories could be derived from other sources

Source apportionment of VOCs and the contribution to photochemical ozone formation during summer in the typical industrial area in the Yangtze River Delta, China

Science.gov (United States)

Shao, Ping; An, Junlin; Xin, Jinyuan; Wu, Fangkun; Wang, Junxiu; Ji, Dongsheng; Wang, Yuesi

2016-07-01

Volatile organic compounds (VOCs) were continuously observated in a northern suburb of Nanjing, a typical industrial area in the Yangtze River Delta, in a summer observation period from 15th May to 31st August 2013. The average concentration of total VOCs was (34.40 ± 25.20) ppbv, including alkanes (14.98 ± 12.72) ppbv, alkenes (7.35 ± 5.93) ppbv, aromatics (9.06 ± 6.64) ppbv and alkynes (3.02 ± 2.01) ppbv, respectively. Source apportionment via Positive Matrix Factorization was conducted, and six major sources of VOCs were identified. The industry-related sources, including industrial emissions and industrial solvent usage, occupied the highest proportion, accounting for about 51.26% of the VOCs. Vehicular emissions occupied the second highest proportion, accounting for about 34.08%. The rest accounted for about 14.66%, including vegetation emission and liquefied petroleum gas/natural gas usage. Contributions of VOCs to photochemical O3 formation were evaluated by the application of a detailed chemical mechanism model (NCAR MM). Alkenes were the dominant contributors to the O3 photochemical production, followed by aromatics and alkanes. Alkynes had a very small impact on photochemical O3 formation. Based on the outcomes of the source apportionment, a sensitivity analysis of relative O3 reduction efficiency (RORE), under different source removal regimes such as using the reduction of VOCs from 10% to 100% as input, was conducted. The RORE was the highest (~ 20%-40%) when the VOCs from solvent-related sources decreased by 40%. The highest RORE values for vegetation emissions, industrial emissions, vehicle exhaust, and LPG/NG usage were presented in the scenarios of 50%, 80%, 40% and 40%, respectively.

Modeling pesticide loadings from the San Joaquin watershed into the Sacramento-San Joaquin Delta using SWAT

Science.gov (United States)

Chen, H.; Zhang, M.

2016-12-01

The Sacramento-San Joaquin Delta is an ecologically rich, hydrologically complex area that serves as the hub of California's water supply. However, pesticides have been routinely detected in the Delta waterways, with concentrations exceeding the benchmark for the protection of aquatic life. Pesticide loadings into the Delta are partially attributed to the San Joaquin watershed, a highly productive agricultural watershed located upstream. Therefore, this study aims to simulate pesticide loadings to the Delta by applying the Soil and Water Assessment Tool (SWAT) model to the San Joaquin watershed, under the support of the USDA-ARS Delta Area-Wide Pest Management Program. Pesticide use patterns in the San Joaquin watershed were characterized by combining the California Pesticide Use Reporting (PUR) database and GIS analysis. Sensitivity/uncertainty analyses and multi-site calibration were performed in the simulation of stream flow, sediment, and pesticide loads along the San Joaquin River. Model performance was evaluated using a combination of graphic and quantitative measures. Preliminary results indicated that stream flow was satisfactorily simulated along the San Joaquin River and the major eastern tributaries, whereas stream flow was less accurately simulated in the western tributaries, which are ephemeral small streams that peak during winter storm events and are mainly fed by irrigation return flow during the growing season. The most sensitive parameters to stream flow were CN2, SOL_AWC, HRU_SLP, SLSUBBSN, SLSOIL, GWQMN and GW_REVAP. Regionalization of parameters is important as the sensitivity of parameters vary significantly spatially. In terms of evaluation metric, NSE tended to overrate model performance when compared to PBIAS. Anticipated results will include (1) pesticide use pattern analysis, (2) calibration and validation of stream flow, sediment, and pesticide loads, and (3) characterization of spatial patterns and temporal trends of pesticide yield.

The first hop: Use of Beaufort Sea deltas by hatch-year semipalmated sandpipers

Science.gov (United States)

Churchwell, Roy T.; Kendall, Steve J.; Brown, Stephen C.; Blanchard, Arny L.; Hollmen, Tuula E.; Powell, Abby

2018-01-01

River deltas along Alaska’s Beaufort Sea coast are used by hatch-year semipalmated sandpipers (Calidris pusilla) after leaving their terrestrial natal sites, but the drivers of their use of these stopover sites on the first “hop” of fall migration are unknown. We quantified sandpiper temporal distribution and abundance as related to food resources at three river deltas during the beginning of their fall migration (post-breeding period) to compare the habitat quality among these deltas. We conducted population counts, sampled invertebrates, and captured birds to collect blood samples from individuals for triglyceride and stable isotope analyses to determine fattening rates and diet. Patterns of sandpiper and invertebrate abundance were complex and varied among deltas and within seasons. River deltas were used by sandpipers from late July to late August, and peak sandpiper counts ranged from 1000 to 4000 individuals, of which 98% were hatch-year semipalmated sandpipers. Isotopic signatures from blood plasma samples indicated that birds switched from a diet of upland tundra to delta invertebrate taxa as the migration season progressed, suggesting a dependence on delta invertebrates. Despite differences in diet among deltas, we found no differences in fattening rates of juvenile sandpipers as indicated by triglyceride levels. The number of sandpipers was positively associated with abundance of Amphipoda and Oligochaeta at the Jago and Okpilak-Hulahula deltas; an isotopic mixing model indicated that sandpipers consumed Amphipoda and Oligochaeta at Jago, mostly Chironomidae at Okpilak-Hulahula and Spionidae at Canning. Regardless of the difference in sandpiper diets at the Beaufort Sea deltas, their similar fattening rates throughout the season indicate that all of these stopover sites provide a critical food resource for hatch-year sandpipers beginning their first migration.

Bioassay responses and effects on benthos after pilot remediations in the delta of the rivers Rhine and Meuse

International Nuclear Information System (INIS)

Besten, Pieter J. den; Brink, Paul J. van den

2005-01-01

Chemical and biological monitoring was carried out for 5 years following pilot remediations at two locations in the Rhine-Meuse delta. The remediations consisted of partial excavation of the contaminated sediments, followed by applying a clean layer of sandy material on top. After the remediation, a new silty sediment top layer was formed exhibiting a lower toxicity in five sediment/sediment pore water bioassays. Compared to the unremediated sites, lower metal and PAH concentrations were found at the remediated sites, but in one location at the same time elevated HCH, PCB and HCB levels were recorded. One year after the remediation, the differences became smaller, although effects-based classification showed that the remediated site showed a higher quality up to the last year. In both remediated sites a rapid recolonization of nematodes, oligochaetes and chironomids was observed, while the recolonization by bivalves was slower. A few years after the remediation the differences decrease. - Capping contaminated sediments can be an effective remediation measure in two large river deltas

Bioassay responses and effects on benthos after pilot remediations in the delta of the rivers Rhine and Meuse

Energy Technology Data Exchange (ETDEWEB)

Besten, Pieter J. den [Institute for Inland Water Management and Waste Water Treatment (RIZA), Ministry of Transport, Public Works and Water Management, PO Box 17, 8200 AA Lelystad (Netherlands)]. E-mail: p.dbesten@riza.rws.minvenw.nl; Brink, Paul J. van den [Alterra Green World Research, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen (Netherlands)

2005-07-15

Chemical and biological monitoring was carried out for 5 years following pilot remediations at two locations in the Rhine-Meuse delta. The remediations consisted of partial excavation of the contaminated sediments, followed by applying a clean layer of sandy material on top. After the remediation, a new silty sediment top layer was formed exhibiting a lower toxicity in five sediment/sediment pore water bioassays. Compared to the unremediated sites, lower metal and PAH concentrations were found at the remediated sites, but in one location at the same time elevated HCH, PCB and HCB levels were recorded. One year after the remediation, the differences became smaller, although effects-based classification showed that the remediated site showed a higher quality up to the last year. In both remediated sites a rapid recolonization of nematodes, oligochaetes and chironomids was observed, while the recolonization by bivalves was slower. A few years after the remediation the differences decrease. - Capping contaminated sediments can be an effective remediation measure in two large river deltas.

Multi-tracer investigation of river and groundwater interactions: a case study in Nalenggele River basin, northwest China

Science.gov (United States)

Xu, Wei; Su, Xiaosi; Dai, Zhenxue; Yang, Fengtian; Zhu, Pucheng; Huang, Yong

2017-11-01

Environmental tracers (such as major ions, stable and radiogenic isotopes, and heat) monitored in natural waters provide valuable information for understanding the processes of river-groundwater interactions in arid areas. An integrated framework is presented for interpreting multi-tracer data (major ions, stable isotopes (2H, 18O), the radioactive isotope 222Rn, and heat) for delineating the river-groundwater interactions in Nalenggele River basin, northwest China. Qualitative and quantitative analyses were undertaken to estimate the bidirectional water exchange associated with small-scale interactions between groundwater and surface water. Along the river stretch, groundwater and river water exchange readily. From the high mountain zone to the alluvial fan, groundwater discharge to the river is detected by tracer methods and end-member mixing models, but the river has also been identified as a losing river using discharge measurements, i.e. discharge is bidirectional. On the delta-front of the alluvial fan and in the alluvial plain, in the downstream area, the characteristics of total dissolved solids values, 222Rn concentrations and δ18O values in the surface water, and patterns derived from a heat-tracing method, indicate that groundwater discharges into the river. With the environmental tracers, the processes of river-groundwater interaction have been identified in detail for better understanding of overall hydrogeological processes and of the impacts on water allocation policies.