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Sample records for nile river delta

  1. Nile River Delta, Egypt

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The Nile River Delta of Egypt (30.0N, 31.0E) irrigated by the Nile River and its many distributaries, is some of the richest farm land in the world and home to some 45 million people, over half of Egypt's population. The capital city of Cairo is at the apex of the delta. Just across the river from Cairo can be seen the ancient three big pyramids and sphinx at Giza and the Suez Canal is just to the right of the delta.

  2. Nile Delta

    Atmospheric Science Data Center

    2013-04-15

    article title:  The Nile River Delta     View Larger Image ... of eastern Africa. At the apex of the fertile Nile River Delta is the Egyptian capital city of Cairo. To the west are the Great Pyramids ...

  3. Determining the Palaeodrainage of the Nile River from a Provenance Study of the Nile Delta Cone Sediments

    NASA Astrophysics Data System (ADS)

    Fielding, L.; Najman, Y.; Millar, I.; Butterworth, P.; Garzanti, E.; Kneller, B. C.

    2014-12-01

    This study documents the palaeodrainage history of the Nile River, in particular the time of its transition from a small locally sourced drainage network to the initiation of an extensive catchment. Today, the Nile drains as far south as Lake Victoria, with the White Nile draining largely cratonic rocks of Archean to Proterozoic age and the Blue Nile draining Cenozoic Ethiopian Continental Flood Basalts and Neoproterozoic basement. However, the timing of catchment expansion to the river's current extent is highly debated. Two end member models are: A) The Blue Nile did not connect with the lower Nile until the Late Messinian, and the White Nile not until 0.5 Ma. In this model, the pre-Messinian Nile delta sediments are locally derived from the Red Sea Hills (RSH) (Issawi and McCauley 1992). B) The Blue Nile has been connected to the lower Nile since the Oligocene (Burke and Wells 1989). Onshore fieldwork characterised each possible source area (Ethiopian flood basalts, Archean craton, and Neoproterozoic basement and Phanerozoic cover sequences of the RSH) using petrography, geochemistry and isotope studies. Tertiary-aged Nile delta sediments provide a unique archive of the river's palaeodrainage history, which were analysed from conventional core from exploration and appraisal wells in order to identify the occurrence (if any) of these sources in the delta geological record. Heavy mineral, petrographic, U/Pb rutile and Lu/Hf zircon analyses indicate Blue Nile and/or RSH input to the Nile delta since at least the Oligocene with very little input from the White Nile. Sr and Nd whole-rock analyses of mud samples allow discrimination between the Blue Nile and RSH sources and may, subject to further analyses, confirm Blue Nile input to the delta since the Oligocene. U-Pb zircon analyses reveal the presence of 20-30 Ma zircons in both the modern river sediments from the Ethiopian Highlands and the Nile Delta core from the early Miocene to present day indicating a

  4. Determining the palaeodrainage of the Nile river from a provenance study of the Nile delta cone sediments

    NASA Astrophysics Data System (ADS)

    Fielding, Laura; Najman, Yani; Millar, Ian; Butterworth, Peter; Garzanti, Eduardo; Kneller, Ben

    2014-05-01

    This study documents the palaeodrainage history of the Nile River, in particular the time of its transition from a small locally sourced drainage network to the initiation of an extensive catchment. Today, the Nile drains as far south as Lake Victoria, with the White Nile draining largely cratonic rocks of Archean to Proterozoic age and the Blue Nile draining Cenozoic Ethiopian Continental Flood Basalts and Neoproterozoic basement. However, the timing of catchment expansion to the river's current extent is highly debated. Two end member models are: A) The Blue Nile did not connect with the lower Nile until the Late Messinian, and the White Nile not until 0.5 Ma. In this model, the pre-Messinian Nile delta sediments are locally derived from the Red Sea Hills (RSH) (Issawi and McCauley 1992). B) The Blue Nile has been connected to the lower Nile since the Oligocene (Burke and Wells 1989). Onshore fieldwork characterised each possible source area (Ethiopian flood basalts, Archean craton, and Neoproterozoic basement and Phanerozoic cover sequences of the RSH) using petrography, geochemistry and isotope studies. Tertiary-aged Nile delta sediments provide a unique archive of the river's palaeodrainage history, which were analysed from conventional core from exploration and appraisal wells in order to identify the occurrence (if any) of these sources in the delta geological record. Heavy mineral, petrographic, U/Pb rutile and Lu/Hf zircon analyses indicate Blue Nile and/or RSH input to the Nile delta since at least the Oligocene with very little input from the White Nile. Sr and Nd whole-rock analyses of mud samples allow discrimination between the Blue Nile and RSH sources and may, subject to further analyses, confirm Blue Nile input to the delta since the Oligocene. U-Pb zircon analyses reveal the presence of 20-30 Ma zircons in both the modern river sediments from the Ethiopian Highlands and the Nile Delta core from the early Miocene to present day indicating a

  5. Nile Delta, Egypt

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The Nile Delta of Egypt (30.0N, 31.0E) irrigated by the Nile River and its many distributaries, is some of the richest farm land in the world and home to some 45 million people, over half of Egypt's population of 57 million. The capital city of Cairo is at the apex of the delta in the middle of the scene. Across the river from Cairo can be seen the three big pyramids and sphinx at Giza and the Suez Canal is just to the right of the delta.

  6. Nile Delta

    Atmospheric Science Data Center

    2013-04-16

    ... Mediterranean Sea. The Nile provides a year-round source of water as well as fertile silt deposits that have supported agricultural ... waterway, although in the twentieth century that role became less important. The false color image uses the infrared, red, ...

  7. SAR Interferometry as a Tool for Monitoring Coastal Changes in the Nile River Delta of Egypt

    NASA Technical Reports Server (NTRS)

    Aly, Mohamed H.; Klein, Andrew G.; Giardino, John R.

    2005-01-01

    The Nile River Delta is experiencing rapid rates of coastal change. The rate of both coastal retreat and accretion in the Eastern Nile Delta requires regular, accurate detection and measurement. Current techniques used to monitor coastal changes in the delta are point measurements and, thus, they provide a spatially limited view of the ongoing coastal changes. SAR interferometry can provide measurements of subtle coastal change at a significantly improved spatial resolution and over large areas (100 sq km). Using data provided by the ERS-1&2 satellites, monitoring can be accomplished as frequently as every 35 days when needed. Radar interferometry is employed in this study to detect segments of erosion and accretion during the 1993-2000 period. The average rates of erosion and accretion in the Eastern Nile Delta are measured to be -11.64 m/yr and +5.12 m/yr, respectively. The results of this interferometric study can be used effectively for coastal zone management and integrated sustainable development for the Nile River Delta.

  8. Hydro-environmental status and soil management of the River Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Elewa, H. H.; El Nahry, A. H.

    2009-04-01

    The sea level rise has its own-bearing on the coastal recession and hydro-environmental degradation of the River Nile Delta. Attempts are made here to use remote sensing to detect the coastal recession in some selected parts and delineating the chemistry of groundwater aquifers and surface water, which lie along south-mid-northern and coastal zone of the Nile Delta. Eight water samples from groundwater monitoring wells and 13 water samples from surface water were collected and analyzed for various hydrochemical parameters. The groundwater samples are classified into five hydrochemical facies on Hill-Piper trilinear diagram based on the dominance of different cations and anions: facies 1: Ca-Mg-Na-HCO3-Cl-SO4 type I; facies 2: Na-Cl-HCO3 type II; facies 3: Na-Ca-Mg-Cl type III, facies 4: Ca-Na-Mg-Cl-HCO3 type IV and facies 5: Na-Mg-Cl type V. The hydrochemical facies showed that the majority of samples were enriched in sodium, bicarbonate and chloride types and, which reflected that the sea water and tidal channel play a major role in controlling the groundwater chemical composition in the Quaternary shallow aquifers, with a severe degradation going north of Nile Delta. Also, the relationship between the dissolved chloride (Cl, mmol/l), as a variable, and other major ion combinations (in mmol/l) were considered as another criterion for chemical classification system. The low and medium chloride groundwater occurs in southern and mid Nile Delta (Classes A and B), whereas the high and very high chloride (classes D and C) almost covers the northern parts of the Nile Delta indicating the severe effect of sea water intrusion. Other facets of hydro-environmental degradation are reflected through monitoring the soil degradation process within the last two decades in the northern part of Nile Delta. Land degradation was assessed by adopting new approach through the integration of GLASOD/FAO approach and Remote Sensing/GIS techniques. The main types of human induced soil

  9. The Nile River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image of the northern portion of the Nile River was captured by MISR's nadir camera on January 30, 2001 (Terra orbit 5956). The Nile is the longest river in the world, extending for about 6700 kilometers from its headwaters in the highlands of eastern Africa. At the apex of the fertile Nile River Delta is the Egyptian capital city of Cairo. To the west are the Great Pyramids of Giza. North of here the Nile branches into two distributaries, the Rosetta to the west and the Damietta to the east. Also visible in this image is the Suez Canal, a shipping waterway connecting Port Said on the Mediterranean Sea with the Gulf of Suez. The Gulf is an arm of the Red Sea, and is located on the righthand side of the picture. Image credit: NASA/GSFC/LaRC/JPL, MISR Team.

  10. An Integrated Hydrological and Water Management Study of the Entire Nile River System - Lake Victoria to Nile Delta

    NASA Technical Reports Server (NTRS)

    Habib, Shahid; Zaitchik, Benjamin; Alo, Clement; Ozdogan, Mutlu; Anderson, Martha; Policelli, Fritz

    2011-01-01

    The Nile basin River system spans 3 million km(exp 2) distributed over ten nations. The eight upstream riparian nations, Ethiopia, Eretria, Uganda, Rwanda, Burundi, Congo, Tanzania and Kenya are the source of approximately 86% of the water inputs to the Nile, while the two downstream riparian countries Sudan and Egypt, presently rely on the river's flow for most of the their needs. Both climate and agriculture contribute to the complicated nature of Nile River management: precipitation in the headwaters regions of Ethiopia and Lake Victoria is variable on a seasonal and inter-annual basis, while demand for irrigation water in the arid downstream region is consistently high. The Nile is, perhaps, one of the most difficult trans-boundary water issue in the world, and this study would be the first initiative to combine NASA satellite observations with the hydrologic models study the overall water balance in a to comprehensive manner. The cornerstone application of NASA's Earth Science Research Results under this project are the NASA Land Data Assimilation System (LDAS) and the USDA Atmosphere-land Exchange Inverse (ALEXI) model. These two complementary research results are methodologically independent methods for using NASA observations to support water resource analysis in data poor regions. Where an LDAS uses multiple sources of satellite data to inform prognostic simulations of hydrological process, ALEXI diagnoses evapotranspiration and water stress on the basis of thermal infrared satellite imagery. Specifically, this work integrates NASA Land Data Assimilation systems into the water management decision support systems that member countries of the Nile Basin Initiative (NBI) and Regional Center for Mapping of Resources for Development (RCMRD, located in Nairobi, Kenya) use in water resource analysis, agricultural planning, and acute drought response to support sustainable development of Nile Basin water resources. The project is motivated by the recognition that

  11. Prevalence and characterization of Cryptosporidium spp. in dairy cattle in Nile River delta provinces, Egypt.

    PubMed

    Amer, Said; Zidan, Shereif; Adamu, Haileeyesus; Ye, Jianbin; Roellig, Dawn; Xiao, Lihua; Feng, Yaoyu

    2013-11-01

    Molecular characterizations of Cryptosporidium spp. in dairy cattle in industrialized nations have mostly shown a dominance of Cryptosporidium parvum, especially its IIa subtypes in pre-weaned calves. Few studies, however, have been conducted on the distribution of Cryptosporidium species and C. parvum subtypes in various age groups of dairy cattle in developing countries. In this study, we examined the prevalence and molecular characteristics of Cryptosporidium in dairy cattle in four Nile River delta provinces in Egypt. Modified Ziehl-Neelsen acid-fast microscopy was used to screen for Cryptosporidium oocysts in 1974 fecal specimens from animals of different ages on 12 farms. Positive fecal specimens were identified from all studied farms with an overall prevalence of 13.6%. By age group, the infection rates were 12.5% in pre-weaned calves, 10.4% in post-weaned calves, 22.1% in heifers, and 10.7% in adults. PCR-RFLP and DNA sequence analyses of microscopy-positive fecal specimens revealed the presence of four major Cryptosporidium species. In pre-weaned calves, C. parvum was most common (30/69 or 43.5%), but Cryptosporidium ryanae (13/69 or 18.8%), Cryptosporidium bovis (7/69 or 10.2%), and Cryptosporidium andersoni (7/69 or 10.2%) were also present at much higher frequencies seen in most industrialized nations. Mixed infections were seen in 12/69 (17.4%) of genotyped specimens. In contrast, C. andersoni was the dominant species (193/195 or 99.0%) in post-weaned calves and older animals. Subtyping of C. parvum based on sequence analysis of the 60kDa glycoprotein gene showed the presence of subtypes IIdA20G1 in nine specimens, IIaA15G1R1 in 27 specimens, and a rare subtype IIaA14G1R1r1b in one specimen. The common occurrence of non-C. parvum species and IId subtypes in pre-weaned calves is a distinct feature of cryptosporidiosis transmission in dairy cattle in Egypt. The finding of the same two dominant IIa and IId C. parvum subtypes recently found in humans in

  12. Prevalence and characterization of Cryptosporidium spp. in dairy cattle in Nile River delta provinces, Egypt.

    PubMed

    Amer, Said; Zidan, Shereif; Adamu, Haileeyesus; Ye, Jianbin; Roellig, Dawn; Xiao, Lihua; Feng, Yaoyu

    2013-11-01

    Molecular characterizations of Cryptosporidium spp. in dairy cattle in industrialized nations have mostly shown a dominance of Cryptosporidium parvum, especially its IIa subtypes in pre-weaned calves. Few studies, however, have been conducted on the distribution of Cryptosporidium species and C. parvum subtypes in various age groups of dairy cattle in developing countries. In this study, we examined the prevalence and molecular characteristics of Cryptosporidium in dairy cattle in four Nile River delta provinces in Egypt. Modified Ziehl-Neelsen acid-fast microscopy was used to screen for Cryptosporidium oocysts in 1974 fecal specimens from animals of different ages on 12 farms. Positive fecal specimens were identified from all studied farms with an overall prevalence of 13.6%. By age group, the infection rates were 12.5% in pre-weaned calves, 10.4% in post-weaned calves, 22.1% in heifers, and 10.7% in adults. PCR-RFLP and DNA sequence analyses of microscopy-positive fecal specimens revealed the presence of four major Cryptosporidium species. In pre-weaned calves, C. parvum was most common (30/69 or 43.5%), but Cryptosporidium ryanae (13/69 or 18.8%), Cryptosporidium bovis (7/69 or 10.2%), and Cryptosporidium andersoni (7/69 or 10.2%) were also present at much higher frequencies seen in most industrialized nations. Mixed infections were seen in 12/69 (17.4%) of genotyped specimens. In contrast, C. andersoni was the dominant species (193/195 or 99.0%) in post-weaned calves and older animals. Subtyping of C. parvum based on sequence analysis of the 60kDa glycoprotein gene showed the presence of subtypes IIdA20G1 in nine specimens, IIaA15G1R1 in 27 specimens, and a rare subtype IIaA14G1R1r1b in one specimen. The common occurrence of non-C. parvum species and IId subtypes in pre-weaned calves is a distinct feature of cryptosporidiosis transmission in dairy cattle in Egypt. The finding of the same two dominant IIa and IId C. parvum subtypes recently found in humans in

  13. Tracking Nile Delta vulnerability to Holocene change.

    PubMed

    Marriner, Nick; Flaux, Clément; Morhange, Christophe; Stanley, Jean-Daniel

    2013-01-01

    Understanding deltaic resilience in the face of Holocene climate change and human impacts is an important challenge for the earth sciences in characterizing the full range of present and future wetland responses to global warming. Here, we report an 8000-year mass balance record from the Nile Delta to reconstruct when and how this sedimentary basin has responded to past hydrological shifts. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the 'monsoon pacemaker', attested throughout the mid-latitude tropics. Following the early to mid-Holocene growth of the Nile's deltaic plain, sediment losses and pronounced erosion are first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. Against the backcloth of the Saharan 'depeopling', reduced river flow underpinned by a weakening of monsoonal precipitation appears to have been particularly conducive to the expansion of human activities on the delta by exposing productive floodplain lands for occupation and irrigation agriculture. The reconstruction suggests that the Nile Delta has a particularly long history of vulnerability to extreme events (e.g. floods and storms) and sea-level rise, although the present sediment-starved system does not have a direct Holocene analogue. This study highlights the importance of the world's deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction.

  14. West Nile Virus Transmission in Sentinel Chickens and Potential Mosquito Vectors, Senegal River Delta, 2008–2009

    PubMed Central

    Fall, Assane Gueye; Diaïté, Amadou; Seck, Momar Talla; Bouyer, Jérémy; Lefrançois, Thierry; Vachiéry, Nathalie; Aprelon, Rosalie; Faye, Ousmane; Konaté, Lassana; Lancelot, Renaud

    2013-01-01

    West Nile virus (WNV) is an arthropod-borne Flavivirus usually transmitted to wild birds by Culex mosquitoes. Humans and horses are susceptible to WNV but are dead-end hosts. WNV is endemic in Senegal, particularly in the Senegal River Delta. To assess transmission patterns and potential vectors, entomological and sentinel serological was done in Ross Bethio along the River Senegal. Three sentinel henhouses (also used as chicken-baited traps) were set at 100 m, 800 m, and 1,300 m from the river, the latter close to a horse-baited trap. Blood samples were taken from sentinel chickens at 2-week intervals. Seroconversions were observed in sentinel chickens in November and December. Overall, the serological incidence rate was 4.6% with 95% confidence interval (0.9; 8.4) in the sentinel chickens monitored for this study. Based on abundance pattern, Culex neavei was the most likely mosquito vector involved in WNV transmission to sentinel chickens, and a potential bridge vector between birds and mammals. PMID:24084679

  15. Tracking Nile Delta Vulnerability to Holocene Change

    PubMed Central

    Marriner, Nick; Flaux, Clément; Morhange, Christophe; Stanley, Jean-Daniel

    2013-01-01

    Understanding deltaic resilience in the face of Holocene climate change and human impacts is an important challenge for the earth sciences in characterizing the full range of present and future wetland responses to global warming. Here, we report an 8000-year mass balance record from the Nile Delta to reconstruct when and how this sedimentary basin has responded to past hydrological shifts. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the ‘monsoon pacemaker’, attested throughout the mid-latitude tropics. Following the early to mid-Holocene growth of the Nile’s deltaic plain, sediment losses and pronounced erosion are first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. Against the backcloth of the Saharan ‘depeopling’, reduced river flow underpinned by a weakening of monsoonal precipitation appears to have been particularly conducive to the expansion of human activities on the delta by exposing productive floodplain lands for occupation and irrigation agriculture. The reconstruction suggests that the Nile Delta has a particularly long history of vulnerability to extreme events (e.g. floods and storms) and sea-level rise, although the present sediment-starved system does not have a direct Holocene analogue. This study highlights the importance of the world’s deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction. PMID:23922692

  16. Discover the Nile River

    ERIC Educational Resources Information Center

    Project WET Foundation, 2009

    2009-01-01

    Bordering on the Fantastic. As the longest river on earth, the Nile passes through 10 countries. Presented through a wide range of activities and a winning array of games, it's also unsurpassed at taking young minds into exploring the world of water, as well as natural and man made wonders.

  17. Ocean-color remote sensing of the Nile delta shelf and SE Levantine basin and possible linkage to some mesoscale circulation features and Nile river run-off

    NASA Astrophysics Data System (ADS)

    Moufaddal, Wahid; Lavender, Samantha

    To date, and despite the passage of more than 30 years since the launch of the first satellite based ocean-color sensor, no systematic study of the variability of chlorophyll in the Egyptian Mediterranean coast off the Nile delta has been undertaken using this kind of data. Meantime, available in-situ measurements on chlorophyll and other nutrient parameters along this coast are indeed very modest and scarce. The lack of data has in turn created a large gap in our knowledge on the biogeochemical characteristics of the coastal water and impacts of the Aswan High Dam and other land-use changes on the marine ecosystems and nutrient budget in the Nile delta shelf and the SE Mediterranean. The present study aims to fill part of this gap through application of ocean-color remote sensing and satellite retrieval of phytoplankton chlorophyll. For this purpose a 10-year (1997-2006) monthly satellite dataset from ESA Globcolour project (an ESA Data User Element project: http://www.globcolour.info) was retrieved and subjected to time-series analysis. Results of this analysis revealed that the oceanic and coastal parts off the Nile delta coast and SE Mediterranean manifest from time to time some of the most interesting and dynamical marine features including meso-scale gyres, coastal filaments, localized algal blooms and higher concentration of phytoplankton chlorophyll. These features together with certain physical pro-cesses and surface run-off from Nile mouthes and other land-based sources were found to exert pronounced effects on the nutrient supply and quality of the coastal and oceanic surface waters in this region. Results reveled also that there has been a general upward trend in concentration of surface chlorophyll during the 10-year period from 1997 to 2006 with a coincident rise of the coastal fisheries implying that improvement of nutrient supply is most likely responsible for this rise. Results confirmed also shift of the Nile phytoplankton bloom in space and time

  18. Geochemistry of sediments and surface soils from the Nile Delta and lower Nile valley studied by epithermal neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Arafa, Wafaa M.; Badawy, Wael M.; Fahmi, Naglaa M.; Ali, Khaled; Gad, Mohamed S.; Duliu, Octavian G.; Frontasyeva, Marina V.; Steinnes, Eiliv

    2015-07-01

    The distributions of 36 major and trace elements in 40 surface soil and sediment samples collected from the Egyptian section of the river Nile were determined by epithermal neutron activation analysis and compared with corresponding data for the Upper Continental Crust and North American Shale Composite. Their relative distributions indicate the presence of detrital material of igneous origin, most probably resulting from weathering on Ethiopian highlands and transported by the Blue Nile, the Nile main tributary. The distributions of the nickel, zinc, and arsenic contents suggest that the lower part of the Nile and its surroundings including the Nile Delta is not seriously polluted with metals from local human activity. The geographical distributions of Na, Cl, and I as well as results of principal component analysis suggest atmospheric supply of these elements from the ocean. In general the present data may contribute to a better understanding of the geochemistry of the Nile sediments.

  19. Nile River, Lake Nasser, Aswan Dam, Egypt

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Egypt's High Aswan Dam on the Nile River at the first cataracts, Nile River, (24.0N, 33.0E) was completed in 1971 to provide cheap hydroelectric power and to regulate the historically uneven flow of the Nile River. The contrast between the largely base rock desert east of the Nile versus the sand covered desert west of the river and the ancient irrigated floodplain downstream from the damsite is clearly shown.

  20. Impact of climate change on water and agriculture: Challenges and possible solutions for the Nile Delta

    NASA Astrophysics Data System (ADS)

    Mabrouk, Badr; Arafa, Salah; Farahat, Hany; Badr, Marmar; Gampe, David; Ludwig, Ralf

    2013-04-01

    The Nile-Delta is subjected to continuous changes; including shoreline changes either erosion or accretion, subsidence of the delta, as well as sea level rise due to climate change. The impacts of climate change on the Nile Delta have been addressed on local and international level as the Nile Delta coastal zones are vulnerable to sea level rise. The poster presents recent research activities and findings from the CLIMB project in the Nile Delta and costal zones of Egypt. Lots of field data have been collected such as aquifer geometry data, soil properties data, well data and contamination sources. All of these data support a coupled modeling approach of the land surface hydrological model WASIM-ETH and the hydrological model MOD-Flow to simulate and project the future impact translation of climate projections into hydrological impacts. Results confirm intensified threads to water security. Increasing potential evaporation (in response to increasing temperature) in combination with decreasing water levels in the Nile river, reduced precipitation and groundwater recharge and deteriorating groundwater quality, imposes great challenges to ensure the supply of drinking water and irrigation. Current irrigation strategies are highly inefficient and must be replaced by new and adapted systems. Based on the results of the coupled modeling approach, various scenarios can be evaluated. The vision is to develop a road map for climate change and green economy that maximizes wellbeing of the Egyptian citizens, operates with environmental limits, and is capable of adapting to global environmental change.

  1. Modeling river delta formation.

    PubMed

    Seybold, Hansjörg; Andrade, José S; Herrmann, Hans J

    2007-10-23

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  2. Nile Delta vegetation response to Holocene climate variability

    USGS Publications Warehouse

    Bernhardt, Christopher E.; Horton, Benjamin P.; Stanley, Jean-Daniel

    2012-01-01

    A 7000 yr palynologic record from Burullus Lagoon, Nile Delta, Egypt, is assessed to investigate changes in terrestrial vegetation in response to Nile flow. Previous studies in this region have shown that sea-level rise in the early to mid-Holocene, and markedly increased human land use during the past several centuries, altered vegetation in and around the lagoon. The pollen record from this study documents changes in delta vegetation that likely reflect variations in Nile flow. We suggest that Cyperaceae pollen is a sensitive marker of precipitation over the Nile headwaters and the resultant Nile flow. Decreases in Cyperaceae pollen, interpreted as a marker for diminished Nile flow, as well as the increase in relative abundance of microscopic charcoal, occurred at ca. 6000–5500, ca. 5000, ca. 4200, and ca. 3000 cal. yr B.P. (calibrated years before present). These correspond to extreme regional and global aridity events associated with a more southerly mean position of the Intertropical Convergence Zone. These changes, also recorded by other proxy studies, indicate that several marked regional drought events affected the Nile Delta region and impacted ancient Egyptian and Middle Eastern civilizations.

  3. Lake Borullus of the Nile Delta: a short history and an uncertain future.

    PubMed

    Dumont, Henri J; El-Shabrawy, Gamal M

    2007-12-01

    Borullus, the most centrally situated of the Nile Delta lakes, probably evolved around the eighth century AD from a preexisting salt marsh by fluviatile deposition of sand dunes north of the lake and subsidence of the preexisting tidal swamp behind this barrier. It was flooded yearly (September-December) by the Sebennytic branch of the Nile, and evacuated water through an exit, Bughaz. At low river levels, this process reversed and Bughaz functioned as a marine inlet. Because of this switch, its fauna and flora contained a mix of marine, freshwater, and brackish-water species. Around the mid-nineteenth century, damming of the Nile began, culminating with the high Aswan Dam (1964) that brought the yearly flood fully under control. As a result, a steady flow of Nile water, used for irrigated delta agriculture, began to drain to the lake and became a constant evacuator to the Mediterranean. It turned almost fresh, and its fishery, formerly marine and mullet-based, became cichlid-catfish based. However, rice and other new delta crops caused huge amounts of nutrients to wash down the drains, and currently the lake is eutrophied and only resists hypertrophication because of the low residence time of its water. Finally, the damming of the Nile terminated the influx to the delta of a yearly sediment layer, but subsidence and coastal erosion continue and are now consuming the sand bar that separates the lake from the sea.

  4. Pre-Pliocene history and depositional facies, Nile Delta, Egypt

    SciTech Connect

    Harms, J.C.; Wray, J.L.

    1988-08-01

    The Nile delta area has a long history of subsidence and deposition that is inferred to extend back to Jurassic or earlier times. Depositional environments, rates of subsidence, and structural events are quite varied during this time span. Deposition was dominated by platform-to-basin carbonate facies from Jurassic to Eocene time and by detrital sediments from the Oligocene onward. Deposits are truly deltaic, in the sense of representing focused deposition at the shoreline by a large integrated river, only from latest Miocene time onward. A probable transition from continental to oceanic crust typical of the southern Mediterranean margin is overlain in the delta area by Mesozoic platform carbonates that appear to change in seismic data northward into slope and basinal facies. This platform margin, which trends east-west through the central delta, is reflected in later stratigraphic and structural characteristics; very thick Tertiary deposits, bathyal facies of Oligocene to Pliocene age, and large rotated fault blocks of Miocene strata occur only north of this margin.

  5. A review of seawater intrusion in the Nile Delta groundwater system - the basis for assessing impacts due to climate changes and water resources development

    NASA Astrophysics Data System (ADS)

    Mabrouk, M. B.; Jonoski, A.; Solomatine, D.; Uhlenbrook, S.

    2013-08-01

    Serious environmental problems are emerging in the River Nile basin and its groundwater resources. Recent years have brought scientific evidence of climate change and development-induced environmental impacts globally as well as over Egypt. Some impacts are subtle, like decline of the Nile River water levels, others are dramatic like the salinization of all coastal land in the Nile Delta - the agricultural engine of Egypt. These consequences have become a striking reality causing a set of interconnected groundwater management problems. Massive population increase that overwhelmed the Nile Delta region has amplified the problem. Many researchers have studied these problems from different perspectives using different methodologies, following different objectives and, consequently, arrived at different findings. However, they all confirmed that significant groundwater salinization has affected the Nile Delta and this is likely to become worse rapidly in the future. This article presents, categorizes and critically analyses and synthesizes the most relevant research regarding climate change and development challenges in relation to groundwater resources in the Nile Delta. It is shown that there is a gap in studies that focus on sustainable groundwater resources development and environmentally sound protection as an integrated regional process in Nile Delta. Moreover, there is also a knowledge gap related to the deterioration of groundwater quality. The article recommends further research that covers the groundwater resources and salinization in the whole Nile Delta based on integrated three-dimensional groundwater modelling of the Nile delta aquifer.

  6. Nile delta: Recent geological evolution and human impact

    SciTech Connect

    Stanley, D.J.; Warne, A.G. )

    1993-04-30

    Few countries in the world are as dependent on water from a single source as Egypt. The natural Nile cycle of flow and sediment discharge has been disrupted by human intervention, including closure of the High Aswan Dam; this intervention has resulted in a series of responses that now threaten the northern Nile delta. Erosion, salinization, and pollution are inducing a marked decline in agricultural productivity and loss of land and coastal lagoons at a time when the population is expanding exponentially. Geological analyses of radiocarbon-dated cores across the northern delta are used to interpret the interaction of sea-level changes, climatic oscillations, subsidence, and transport processes during the past 35,000 years. Recognition of long-term trends of these natural factors provides a basis to evaluate the profound impact of human activity and to assess future changes in the Nile delta ecosystem.

  7. Measurements of Land Subsidence Rates on the North-western Portion of the Nile Delta Using Radar Interferometry Techniques

    NASA Astrophysics Data System (ADS)

    Fugate, Joseph M.

    The Nile Delta is home to around 75 million people and most of Egypt's farmland and agricultural production. This area is currently threatened by Mediterranean Sea waters due to factors such as sediment starvation, climate change, and sea level fluctuations as well as subsidence. The low elevation and relief of the Nile Delta exposes many coastal communities, including the city of Alexandria, to potential inundation. This situation has become a concern for the area's residents but a better understanding of the processes occurring there can aid in deciding a suitable response. Recent studies have documented Holocene subsidence rates in the northeast part of the Nile Delta that average up to 8mm/year. In this study, PS-InSAR techniques are used to measure modern land subsidence rates on the north-central and north-western Nile Delta. Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques were applied to 23 ESA radar scenes from 2 orbital tracks spanning from 1992 to 2000 in the north-central and north-west portions of the Nile Delta. The area includes the cities of Alexandria, Greater Mahala, and Mansoura as well as the Rosetta promontory and lake Burullus, Idku Lagoon, and Maryut Lagoon. Results indicate that modern average-vertical ground motion velocities for the north-western and north-central Nile Delta range from emergent to subsidence of 8.5 mm/yr. The range of velocities measured are spatially varied in a complex way across the study area. Patterns of subsidence correlate closely to areas of most recent sediment deposition such as along coastlines and rivers, as well as in lagoons and lakes. Average subsidence velocities are also lower across the western sections of the Nile Delta than in the northeastern delta.

  8. Community-based prevalence profile of arboviral, rickettsial, and Hantaan-like viral antibody in the Nile River Delta of Egypt.

    PubMed

    Corwin, A; Habib, M; Watts, D; Darwish, M; Olson, J; Botros, B; Hibbs, R; Kleinosky, M; Lee, H W; Shope, R

    1993-06-01

    To determine the current prevalence of antibody to arboviruses, rickettsiae, and hantaan-like viruses, a survey was carried out in the Nile River Valley of Egypt, one of the principal foci of the 1977-1978 Rift Valley fever (RVF) outbreak. Blood specimens were obtained from 915 persons representing 190 study households. Enzyme immunoassay testing showed that the overall prevalence of IgG antibody was 4% to sand fly fever Sicilian (SFS), 2% to sandfly fever Naples (SFN), 15% to RVF, 20% to West Nile, and 4% to Hantaan (HTN) viruses. Antibody was demonstrated among 32% of the same study subjects to Coxiella burnetii, 58% to Rickettsia typhi, and 32% to R. conorii. The prevalence of agent-specific antibody tended to increase with age. Particularly notable was the low prevalence of RVF infection in children born after the height of the RVF outbreak. No detectable antibodies were found in the population less than seven years of age and in only 3% of those 7-12 years old. In contrast, 26% of the study population 13-19 years old, who were young children and infants at the time of the outbreak, were found to have RVF antibodies, suggesting that the level of intensity associated with transmission decreased considerably following the documented 1977-1978 outbreak. Geometric mean titers (GMT) ranged from 139 for C. burnetii to 1,305 for RVF, and did not vary significantly by age, except for high titers for RVF in the 20-49-year-old age group. A significant upward trend in GMT was also noted when antibody was detected in the specimen for more than one phlebovirus.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Monitoring the urbanization of the Nile Delta, Egypt.

    SciTech Connect

    Sultan, M.; Fiske, M.; Stein, T.; Gamal, M.; El Araby, H.; Madani, A.; Mehanee, S.; Becker, R.; Environmental Research; Washington Univ.; Cairo Univ. Center for Environmental Hazard Mitigation

    1999-11-01

    Comparisons of satellite images of the Nile Delta, acquired in 1972, 1984 and 1990, indicate that urban growth is endangering Egypt's agricultural productivity. Urban areas occupied a minimum of 3.6%, 4.7% and 5.7% of the Delta in 1972, 1984 and 1990, respectively, an increase of 58% in 18 years. Approximately half of this increase occurred between 1984 and 1990. If this trend continues, Egypt could lose 12% of its total agricultural area to urbanization by 2010. Despite the fact that growth is pronounced around the cities, it is the growth around the thousands of small villages that poses the largest threat to the agricultural productivity of the Nile Delta. The cumulative growth rate for the cities and large villages between 1972 and 1990 is 37%, and that for the small villages is 77% for the same time period.

  10. Ganges River Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Ganges River forms an extensive delta where it empties into the Bay of Bengal. The delta is largely covered with a swamp forest known as the Sunderbans, which is home to the Royal Bengal Tiger. It is also home to most of Bangladesh, one of the world's most densely populated countries. Roughly 120 million people live on the Ganges Delta under threat of repeated catastrophic floods due to heavy runoff of meltwater from the Himalayas, and due to the intense rainfall during the monsoon season. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on February 28, 2000. This is a false-color composite image made using green, infrared, and blue wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  11. The Nile Delta: climate pacing and vulnerability to Holocene change

    NASA Astrophysics Data System (ADS)

    Marriner, Nick; Flaux, Clément; Morhange, Christophe; Stanley, Jean-Daniel

    2014-05-01

    Deltas are potentially important sentinels to investigate climate-driven changes in palaeohydrology and human impacts, but, paradoxically, have often been overlooked as palaeoclimate records. In this paper, we present two time-series from the Nile Delta to probe both millennial and centennial-scale changes in deltaic hydrogeomorphology over the past 8000 years. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the 'monsoon pacemaker', attested throughout the mid-latitude tropics. Using a second record we suggest that, at shorter timescales, many of the major phases of deltaic modification were mediated by climate events linked to El Niño Southern Oscillation- type (ENSO) variability. In the final part of the paper, we propose that following the early to mid-Holocene growth of the Nile's deltaic plain pronounced deltaic erosion is first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. The study highlights the importance of the world's deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction.

  12. Mackenzie River Delta, Canada

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Mackenzie River in the Northwest Territories, Canada, with its headstreams the Peace and Finley, is the longest river in North America at 4241 km, and drains an area of 1,805,000 square km. The large marshy delta provides habitat for migrating Snow Geese, Tundra Swans, Brant, and other waterfowl. The estuary is a calving area for Beluga whales. The Mackenzie (previously the Disappointment River) was named after Alexander Mackenzie who travelled the river while trying to reach the Pacific in 1789.

    The image was acquired on August 4, 2005, covers an area of 55.8 x 55.8 km, and is located at 68.6 degrees north latitude, 134.7 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  13. ITCZ and ENSO-like pacing of Nile delta hydro-geomorphology during the Holocene

    NASA Astrophysics Data System (ADS)

    Marriner, Nick; Flaux, Clément; Kaniewski, David; Morhange, Christophe; Leduc, Guillaume; Moron, Vincent; Chen, Zhongyuan; Gasse, Françoise; Empereur, Jean-Yves; Stanley, Jean-Daniel

    2012-06-01

    The Nile valley accommodates the world's longest river and shaped the development of numerous complex societies, providing a reliable source of water for farming and linking populations to sub-Saharan Africa and the Mediterranean Sea. Its fertile delta lay at the heart of ancient Egyptian civilization, however little is known of its morpho-sedimentary response to basin-wide changes in Holocene hydrology. Here, we present two well-resolved records from the Nile delta (based on ˜320 radiocarbon dates) to reconstruct the timing and rhythm of catchment-scale modifications during the past 8000 years. On the orbital timescale, we demonstrate that Nilotic hydrology and sedimentation have responded to low-latitude insolation forcing while, on sub-millennial timescales, many of the major phases of deltaic modification were mediated by climate events linked to El Niño Southern Oscillation-type (ENSO) variability.

  14. Mississippi River Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    As the Mississippi River enters the Gulf of Mexico, it loses energy and dumps its load of sediment that it has carried on its journey through the mid continent. This pile of sediment, or mud, accumulates over the years building up the delta front. As one part of the delta becomes clogged with sediment, the delta front will migrate in search of new areas to grow. The area shown on this image is the currently active delta front of the Mississippi. The migratory nature of the delta forms natural traps for oil. Most of the land in the image consists of mud flats and marsh lands. There is little human settlement in this area due to the instability of the sediments. The main shipping channel of the Mississippi River is the broad stripe running northwest to southeast.

    This image was acquired on May 24, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping

  15. Natural equilibria and anthropic effects on sediment transport in big river systems: The Nile case

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo; Andò, Sergio; Padoan, Marta; Vezzoli, Giovanni; Villa, Igor

    2014-05-01

    The Nile River flows for ~ 6700 km, from Burundi and Rwanda highlands south of the Equator to the Mediterranean Sea at northern subtropical latitudes. It is thus the longest natural laboratory on Earth, a unique setting in which we are carrying out a continuing research project to investigate changes in sediment composition associated with a variety of chemical and physical processes, including weathering in equatorial climate and hydraulic sorting during transport and deposition. Petrographic, mineralogical, chemical, and isotopic fingerprints of sand and mud have been monitored along all Nile branches, from the Kagera and White Nile draining Archean, Paleoproterozoic and Mesoproterozoic basements uplifted along the western branch of the East African rift, to the Blue Nile and Atbara Rivers sourced in Ethiopian volcanic highlands made of Oligocene basalt. Downstream of the Atbara confluence, the Nile receives no significant tributary water and hardly any rainfall across the Sahara. After construction of the Aswan High Dam in 1964, the Nile ceased to be an active conveyor-belt in Egypt, where the mighty river has been tamed to a water canal; transported sediments are thus chiefly reworked from older bed and levee deposits, with minor contributions from widyan sourced in the Red Sea Hills and wind-blown desert sand and dust. Extensive dam construction has determined a dramatic sediment deficit at the mouth, where deltaic cusps are undergoing ravaging erosion. Nile delta sediments are thus recycled under the effect of dominant waves from the northwest, the longest Mediterranean fetch direction. Nile sands, progressively enriched in more stable minerals such as quartz and amphiboles relative to volcanic rock fragments and pyroxene, thus undergo multistep transport by E- and NE-directed longshore currents all along the coast of Egypt and Palestine, and are carried as far as Akko Bay in northern Israel. Nile mud reaches the Iskenderun Gulf in southern Turkey. A full

  16. Natural equilibria and anthropic effects on sediment transport in big river systems: The Nile case

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo; Andò, Sergio; Padoan, Marta; Vezzoli, Giovanni; Villa, Igor

    2014-05-01

    The Nile River flows for ~ 6700 km, from Burundi and Rwanda highlands south of the Equator to the Mediterranean Sea at northern subtropical latitudes. It is thus the longest natural laboratory on Earth, a unique setting in which we are carrying out a continuing research project to investigate changes in sediment composition associated with a variety of chemical and physical processes, including weathering in equatorial climate and hydraulic sorting during transport and deposition. Petrographic, mineralogical, chemical, and isotopic fingerprints of sand and mud have been monitored along all Nile branches, from the Kagera and White Nile draining Archean, Paleoproterozoic and Mesoproterozoic basements uplifted along the western branch of the East African rift, to the Blue Nile and Atbara Rivers sourced in Ethiopian volcanic highlands made of Oligocene basalt. Downstream of the Atbara confluence, the Nile receives no significant tributary water and hardly any rainfall across the Sahara. After construction of the Aswan High Dam in 1964, the Nile ceased to be an active conveyor-belt in Egypt, where the mighty river has been tamed to a water canal; transported sediments are thus chiefly reworked from older bed and levee deposits, with minor contributions from widyan sourced in the Red Sea Hills and wind-blown desert sand and dust. Extensive dam construction has determined a dramatic sediment deficit at the mouth, where deltaic cusps are undergoing ravaging erosion. Nile delta sediments are thus recycled under the effect of dominant waves from the northwest, the longest Mediterranean fetch direction. Nile sands, progressively enriched in more stable minerals such as quartz and amphiboles relative to volcanic rock fragments and pyroxene, thus undergo multistep transport by E- and NE-directed longshore currents all along the coast of Egypt and Palestine, and are carried as far as Akko Bay in northern Israel. Nile mud reaches the Iskenderun Gulf in southern Turkey. A full

  17. Using Persistent Scatterers Interferometry to create a subsidence map of the Nile Delta in Egypt

    NASA Astrophysics Data System (ADS)

    Bouali, E. Y.; Sultan, M.; Becker, R.; Cherif, O.

    2013-12-01

    subsidence rates vary widely across the Nile Delta, with the highest rates occurring in cities near the mouth of the Damietta branch of the Nile River and around the Mansala Lagoon, such as Ras El Bar (up to 15 mm/year), Damietta (up to 10 mm/year), and Port Said (up to 7 mm/year). The complexity of these subsidence rates is spatially evident: many cities display a wide range of subsidence rates - for example Port Said, where a majority of the city is undergoing minimal to no subsidence (< 1 mm/year) there are two regions - near the Mediterranean coast and near the Mansala Lagoon - where subsidence rates are quite high (5-7 mm/year). There are also a few overall trends observed across the delta: (1) subsidence rates are greatest in the northeast region of the delta (average: > 5 mm/year) than anywhere else (e.g., average western subsidence: 1-4 mm/year) and (2) cities generally more proximal to the Mediterranean coast exhibit greater subsidence rates (average subsidence rates: Ras El Bar: 8 mm/year, Port Said: 5 mm/year, and Damietta: 6 mm/year)than cities in the middle (e.g., Mansoura and Al Mahallah: 4 mm/year) or south regions (e.g., Tanta: <4 mm/year) of the delta.

  18. Polychlorinated Biphenyls Water Pollution along the River Nile, Egypt.

    PubMed

    Megahed, Ayman Mohamed; Dahshan, Hesham; Abd-El-Kader, Mahdy A; Abd-Elall, Amr Mohamed Mohamed; Elbana, Mariam Hassan; Nabawy, Ehab; Mahmoud, Hend A

    2015-01-01

    Ten polychlorinated biphenyl (PCB) congeners were determined in water samples collected along the River Nile using gas chromatography-electron capture detector (GC-ECD). PCB concentrations ranged from 14 to 20 μg/L, which were higher than those reported in previous studies, indicating serious PCB pollution in the River Nile. PCB congener profiles varied depending on the sampling sties. PCB-138 was the predominant congener accounting for more than 18% of total PCBs. The composition of PCB congeners in the water revealed that highly chlorinated PCB technical mixtures such as Aroclor 1254 was the main PCB production historically used in Egypt. An increasing trend in PCB levels from the upper stream to the Nile estuaries was observed. The calculated flux of PCBs indicated that 6.8 tons of PCBs is dumped into the Mediterranean Sea each year from the River Nile. The hazard quotients and carcinogenic risk caused by PCB pollution in the River Nile were above the acceptable level indicating that PCBs in the River Nile water pose adverse health effects for all age groups. Our findings revealed that PCBs possess a serious risk to the Egyptian population that depends mainly on the River Nile as a source of water. Thus, stricter legislation and regulatory controls should be applied to reduce the risk of PCBs in Egypt. PMID:26798844

  19. Polychlorinated Biphenyls Water Pollution along the River Nile, Egypt

    PubMed Central

    Megahed, Ayman Mohamed; Dahshan, Hesham; Abd-El-Kader, Mahdy A.; Abd-Elall, Amr Mohamed Mohamed; Elbana, Mariam Hassan; Nabawy, Ehab; Mahmoud, Hend A.

    2015-01-01

    Ten polychlorinated biphenyl (PCB) congeners were determined in water samples collected along the River Nile using gas chromatography-electron capture detector (GC-ECD). PCB concentrations ranged from 14 to 20 μg/L, which were higher than those reported in previous studies, indicating serious PCB pollution in the River Nile. PCB congener profiles varied depending on the sampling sties. PCB-138 was the predominant congener accounting for more than 18% of total PCBs. The composition of PCB congeners in the water revealed that highly chlorinated PCB technical mixtures such as Aroclor 1254 was the main PCB production historically used in Egypt. An increasing trend in PCB levels from the upper stream to the Nile estuaries was observed. The calculated flux of PCBs indicated that 6.8 tons of PCBs is dumped into the Mediterranean Sea each year from the River Nile. The hazard quotients and carcinogenic risk caused by PCB pollution in the River Nile were above the acceptable level indicating that PCBs in the River Nile water pose adverse health effects for all age groups. Our findings revealed that PCBs possess a serious risk to the Egyptian population that depends mainly on the River Nile as a source of water. Thus, stricter legislation and regulatory controls should be applied to reduce the risk of PCBs in Egypt. PMID:26798844

  20. STS-56 view of freeflying SPARTAN-201 and Earth observation of Nile River,Egypt

    NASA Technical Reports Server (NTRS)

    1993-01-01

    During STS-56, the Shuttle Pointed Autonomous Research Tool for Astronomy 201 (SPARTAN-201), a freeflying payload, is captured as it orbits the Earth above the Nile River Valley in Egypt. This synoptic view taken aboard Discovery, Orbiter Vehicle (OV) 103, reveals the landscapes of the Sinai and the Gulf of Suez on the left and the Qatara Depression on the right. The Nile River Valley and the base of the delta feature are in the center. The leaf-like appearance of El Fayum is clearly seen. The city of Cairo is also easily recognized at the base of the delta. SPARTAN-201 was later captured by OV-103's remote manipulator system (RMS) and returned to Earth with the astronaut crew.

  1. Parana River Delta in Argentina

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Parana River delta is a huge forested marshland about 20 miles northeast of Buenos Aires, Argentina. The area is a very popular tour destination. Guided boat tours can be taken into this vast labyrinth of marsh and trees. The Parana River delta is one of the world's greatest bird-watching destinations. This image highlights the striking contrast between dense forest and wetland marshes, and the deep blue ribbon of the Parana River. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on May 26, 2000. This is a false-color composite image made using shortwave infrared, near infrared, and green wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch.

  2. Use of Persistent Scatterer Interferometry to Assess Land Deformation in the Nile Delta and its Controlling Factors

    NASA Astrophysics Data System (ADS)

    Gebremichael, E.; Sultan, M.; Becker, R.; Emil, M.; Ahmed, M.; Chouinard, K.

    2015-12-01

    We applied Persistent scatterer interferometry (PSInSAR) to assess land deformation (subsidence and uplift) across the entire Nile delta and its surroundings and to identify possible causes of the observed deformation. For the purpose of the present study, 100 Envisat Advanced Synthetic Aperture Radar (ASAR; level 0) scenes that were acquired along four tracks and covering a time span of seven years (2004 to 2010) were used. The scenes extend from the Mediterranean coast in the north to Cairo city in the south. These scenes were focused using Repeat Orbit Interferometry PACkage (ROI_PAC) software and the subsequent PSI processing was done using the Stanford Method for Persistent Scatterers (StaMPS) method. A low coherence threshold (0.2) was used to decrease the impact of vegetation-related poor coherence and decorrelation of the scenes over the investigated time span. Subsidence was observed over: (1) the Demietta Nile River branch (3 to 14 mm/yr) where it intersects the Mediterranean coastline, (2) thick (~ 40 m) Holocene sediments in lake Manzala (up to 9 mm/yr), (3) reclaimed desert areas (west of Nile Delta; up to 12 mm/yr) of high groundwater extraction, (4) along parts of a previously proposed flexure line (up to 10 mm/yr), and (5) along the eastern sections of the Mediterranean coastline (up to 15.7 mm/yr). The city of Alexandria (underlain by carbonate platform) and the terminus of the Rosetta branch of the Nile River seem to experience almost no ground movement (mean subsidence of 0.28 mm/yr and 0.74 mm/yr respectively) while the cities of Ras Elbar and Port Said (underlain by thick Holocene sediment) exhibit the highest subsidence values (up to 14 mm/yr and 8.5 mm/yr respectively). The city of Cairo has also experienced subsidence in limited areas of up to 7.8 mm/yr. High spatial correlation was also observed between the subsiding areas and the Abu Madi incised valley; the largest gas field in the Nile Delta. Most of the area undergoing subsidence in the

  3. Effect of regulation of the Nile River on the bioproductivity of Southeastern Mediterranean Sea

    SciTech Connect

    Wadia, W.

    1982-01-01

    The Nile River previously brought a large quantity of dissolved nutrients and organic matter into the Southeastern Mediterranean Sea. Since completion of the Aswan hydrocomplex, reduction in the river flow has caused significant change in the distribution of the physico-chemical indices of the sea water as well as in the formation and distribution of the water masses in the region located north of the Nile delta. In recent years changes have been recorded in the dynamics and distribution of water temperature. From 1966 the sediment runoff of the Nile began dropping sharply due not only to reduction in the volume of river water reaching the sea, but also due to a significant reduction in the suspended particles in the flow. This has had a harmful effect on the formation and dynamics of grounds and banks near the delta and north of it. The reproduction of the shrimp in the area has changed significantly in timing and the food supplies for the young shrimp have deteriorated. Shrimp catches in 1966 were half what they had been in 1963. Commercial fishes have also decreased in numbers. Thus all links of the trophic chain have been affected from the phytoplankton to the pelagic and benthic fishes. 11 references, 3 tables.

  4. Effect of Kima drain wastewaters on Nile river waters

    SciTech Connect

    Soltan, M.E.

    1995-09-01

    The influence of industrial and domestic wastewaters discharged from the Kima drain (Aswan, Egypt) on the quality of the Nile River waters is described by measuring the concentrations of inorganic nonmetals (free CO{sub 2}, CO{sub 3}{sup 2-}, HCO{sub 3}{sup {minus}}, OH{sup -}, Cl{sup -}, SO{sub 4}{sup 2-}, PO{sub 4}{sup 3-}, NO{sub 2}{sup -}, NO{sub 2}{sup -}, NO{sub 3}{sup -}, SiO{sub 2}, COD, DO and pH value), metals (Al, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Pb, and Zn), and the physical parameters (cond., T{degrees}C, SS, and DS). Kima drain wastewaters exhibit high concentrations of dissolved salts, particularly close to where the waste of the Kima factory enters, but decrease substantially near the end of the Kima drain. The reason is the dilution factor, aeration, sedimentation, oxidation reductions, and the biochemical effects. A slight increase of the dissolved solids (DS) in the Nile river water at the Kima drain does not effect the Nile river water quality, as the regeneration of the Nile water continuously (the Nile River receives 200 Mm{sup 3}/d of fresh water from the High Dam Lake) prevents the accretion of the concentrations of metals and anions. Statistical analysis of the database exhibits positive, good, and interesting correlation coefficient values. 28 refs., 2 figs.

  5. Mosquitoes and the Environment in Nile Delta Villages with Previous Rift Valley Fever Activity.

    PubMed

    Zayed, Abdelbaset B; Britch, Seth C; Soliman, Mohamed I; Linthicum, Kenneth J

    2015-06-01

    Egypt is affected by serious human and animal mosquito-borne diseases such as Rift Valley fever (RVF). We investigated how potential RVF virus mosquito vector populations are affected by environmental conditions in the Nile Delta region of Egypt by collecting mosquitoes and environmental data from 3 key governorates before and after 2012 seasonal flooding. We found that environmental effects varied among species, life stages, pre- and postflood groupings, and geographic populations of the same species, and that mosquito community composition could change after flooding. Our study provides preliminary data for modeling mosquitoes and mosquito-borne diseases in the Nile Delta region.

  6. Mosquitoes and the Environment in Nile Delta Villages with Previous Rift Valley Fever Activity.

    PubMed

    Zayed, Abdelbaset B; Britch, Seth C; Soliman, Mohamed I; Linthicum, Kenneth J

    2015-06-01

    Egypt is affected by serious human and animal mosquito-borne diseases such as Rift Valley fever (RVF). We investigated how potential RVF virus mosquito vector populations are affected by environmental conditions in the Nile Delta region of Egypt by collecting mosquitoes and environmental data from 3 key governorates before and after 2012 seasonal flooding. We found that environmental effects varied among species, life stages, pre- and postflood groupings, and geographic populations of the same species, and that mosquito community composition could change after flooding. Our study provides preliminary data for modeling mosquitoes and mosquito-borne diseases in the Nile Delta region. PMID:26181689

  7. Confluence of the White and Blue Nile Rivers at Khartoum, Sudan

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Blue Nile River flowing from Lake Tana to the east and the larger White Nile River flowing from the Rift Valley region combine to form the Nile River at Khartoum, the capital city of Sudan (15.5N, 33.0E). The rivers normally flow out of phase as a result of the differing maximum precipitation periods of their watersheds. The differing flow periods allows longer use of the river for agriculture irrigation in the fields south of the city.

  8. Decadal biogeochemical history of the south east Levantine basin: Simulations of the river Nile regimes

    NASA Astrophysics Data System (ADS)

    Suari, Yair; Brenner, Steve

    2015-08-01

    The south eastern Mediterranean is characterized by antiestuarine circulation which leads to extreme oligotrophic conditions. The Nile river that used to transport fresh water and nutrients into the basin was dammed in 1964 which led to a drastic reduction of fresh water fluxes, and later, changes in Egyptian agriculture and diet led to increased nutrient fluxes. In this paper we present the results of simulations with a biogeochemical model of the south eastern Mediterranean. Four experiments were conducted: (1) present day without riverine inputs; (2) Nile before damming (pre-1964); (3) post-damming 1995 Nile; and (4) fresh water and nutrient discharges of Israeli coastal streams. The present day input simulation (control run) successfully reproduced measured nutrient concentrations, with the exception of simulated chlorophyll concentrations which were slightly higher than observed. The pre-1964 Nile simulation showed a salinity reduction of 2 psu near the Egyptian coast and 0.5 psu along the Israeli coast, as well as elevated chlorophyll a concentrations mostly east of the Nile delta and north to Cyprus. The spring bloom extended from its present peak during February-March to a peak during February-May. The 1995 Nile simulation showed increased chlorophyll a concentrations close to the Egyptian coast. The Israeli coastal stream simulation showed that the effect of the Israeli coastal stream winter flow on chlorophyll converged to control concentrations within about one month, demonstrating the stability and sensitivity of the model to external forcing. The results of this study demonstrate the significance of fresh water fluxes in maintaining marine productivity, which may have large scale effects on the marine ecosystem.

  9. Possible adaptation measures of agriculture sector in the Nile Delta to climate change impacts

    NASA Astrophysics Data System (ADS)

    Attaher, S. M.; Medany, M. A.; Abou-Hadid, A. F.

    2009-10-01

    The overall agricultural system in the Nile Delta region is considered as one of the highest intensive and complicated agriculture systems in the world. According to the recent studies, the Nile Delta region is one of the highly vulnerable regions in the world to climate change. Sea level rise, soil and water degradation, undiversified crop-pattern, yield reduction, pests and disease severity, and irrigation and drainage management were the main key factors that increased vulnerability of the agriculture sector in that region. The main objective of this study is to conduct a community-based multi-criteria adaptation assessment in the Nile Delta using a preset questionnaire. A list of possible adaptation measures for agriculture sector was evaluated. The results indicated that the Nile Delta growers have strong perceptions to act positively to reduce the impacts of climate change. They reflected the need to improve the their adaptive capacity based on clear scientific message with adequate governmental support to coop with the negative impacts of climate change.

  10. Assessment of Undiscovered Oil and Gas Resources of the Nile Delta Basin Province, Eastern Mediterranean

    USGS Publications Warehouse

    Kirschbaum, Mark A.; Schenk, Christopher J.; Charpentier, Ronald R.; Klett, Timothy R.; Brownfield, Michael E.; Pitman, Janet K.; Cook, Troy A.; Tennyson, Marilyn E.

    2010-01-01

    The U.S. Geological Survey estimated means of 1.8 billion barrels of recoverable oil, 223 trillion cubic feet of recoverable gas, and 6 billion barrels of natural gas liquids in the Nile Delta Basin Province using a geology-based assessment methodology.

  11. Dynamics of Wind Setdown at Suez and the Eastern Nile Delta

    PubMed Central

    Drews, Carl; Han, Weiqing

    2010-01-01

    Background Wind setdown is the drop in water level caused by wind stress acting on the surface of a body of water for an extended period of time. As the wind blows, water recedes from the upwind shore and exposes terrain that was formerly underwater. Previous researchers have suggested wind setdown as a possible hydrodynamic explanation for Moses crossing the Red Sea, as described in Exodus 14. Methodology/Principal Findings This study analyzes the hydrodynamic mechanism proposed by earlier studies, focusing on the time needed to reach a steady-state solution. In addition, the authors investigate a site in the eastern Nile delta, where the ancient Pelusiac branch of the Nile once flowed into a coastal lagoon then known as the Lake of Tanis. We conduct a satellite and modeling survey to analyze this location, using geological evidence of the ancient bathymetry and a historical description of a strong wind event in 1882. A suite of model experiments are performed to demonstrate a new hydrodynamic mechanism that can cause an angular body of water to divide under wind stress, and to test the behavior of our study location and reconstructed topography. Conclusions/Significance Under a uniform 28 m/s easterly wind forcing in the reconstructed model basin, the ocean model produces an area of exposed mud flats where the river mouth opens into the lake. This land bridge is 3–4 km long and 5 km wide, and it remains open for 4 hours. Model results indicate that navigation in shallow-water harbors can be significantly curtailed by wind setdown when strong winds blow offshore. PMID:20827299

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

    PubMed

    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.

  13. Wetland vegetation in Manzala lagoon, Nile Delta coast, Egypt: Rapid responses of pollen to altered nile hydrology and land use

    USGS Publications Warehouse

    Bernhardt, C.E.; Stanley, J.-D.; Horton, B.P.

    2011-01-01

    The pollen record in a sediment core from Manzala lagoon on the Nile delta coastal margin of Egypt, deposited from ca. AD 1860 to 1990, indicates rapid coastal wetland vegetation responses to two primary periods of human activity. These are associated with artificially altered Nile hydrologic regimes in proximal areas and distal sectors located to ???1200 km south of Manzala. Freshwater wetland plants that were dominant, such as Typha and Phragmites, decreased rapidly, whereas in the early 1900s, brackish water wetland species (e.g., Amaranthaceae) increased. This change occurred after closure of the Aswan Low Dam in 1902. The second major modification in the pollen record occurred in the early 1970s, after Aswan High Dam closure from 1965 to 1970, when Typha pollen abundance increased rapidly. Massive population growth occurred along the Nile during the 130 years represented by the core section. During this time, the total volume of lagoon water decreased because of conversion of wetland areas to agricultural land, and input of organic-rich sediment, sewage (municipal, agricultural, industrial), and fertilizer in Manzala lagoon increased markedly. Although the wetland plant community has continued to respond to increasingly intensified and varied human-induced pressures in proximal sectors, the two most marked changes in Manzala pollen best correlate with distal events (i.e., closure of the two dams at Aswan). The study also shows that the two major vegetation changes in Manzala lagoon each occurred less than 10 years after closure upriver of the Low and High dams that markedly altered the Nile regime from Upper Egypt to the coast. ?? 2011, the Coastal Education & Research Foundation (CERF).

  14. Incorporating the concept of equivalent freshwater head in successive horizontal simulations of seawater intrusion in the Nile Delta aquifer, Egypt

    NASA Astrophysics Data System (ADS)

    Sherif, Mohsen; Sefelnasr, Ahmed; Javadi, Akbar

    2012-09-01

    SummaryA new approach to study seawater intrusion problems in coastal aquifers is presented. The approach is demonstrated for the case of the Nile Delta aquifer in Egypt. FEFLOW, a 3D finite element variable density model, is employed, however, because of the lack of 3D data, and to demonstrate the proposed approach, the simulations are performed in 2D horizontal views. The concept of equivalent freshwater head (usually implemented in 2D vertical simulations) is adapted in the horizontal (areal) simulations. After calibration against field observations, the simulations are conducted at four horizontal sections located at different levels (100, 200, 300 and 400 m) below the mean seawater level. The depth of the horizontal section is identified through assigning an appropriate pressure “equivalent freshwater” head at the boundaries. The study domain is modified for the horizontal sections at 300 and 400 m, respectively, to account for the aquifer geometry at these depths. The effect of freshwater recharge from the Nile River on the seawater intrusion is observed in the upper layer around its two main branches. The results of the horizontal simulations clearly demonstrate the variation of water concentration in the vertical direction. As the depth increases, the transition zone (in which the concentration varies from the seawater to the freshwater concentration) is shifted toward the landside and become more extensive. At the lower levels of the Nile Delta aquifer, the seawater migrates much further inland as compared to the shallower levels. The concept of horizontal simulations at different levels is further developed to produce meaningful concentration distributions in the vertical sections. This approach allows for a better realization of seawater intrusion in coastal aquifers.

  15. 20,000 years of Nile River dynamics and environmental changes in the Nile catchment area as inferred from Nile upper continental slope sediments

    NASA Astrophysics Data System (ADS)

    Revel, Marie; Ducassou, E.; Skonieczny, C.; Colin, C.; Bastian, L.; Bosch, D.; Migeon, S.; Mascle, J.

    2015-12-01

    Multi-proxy analysis of two marine sediment cores (MS27PT and MD04-2726) from the Nile continental slope provides evidence of changes in Nile sediment discharge related to changes in Ethiopian African Monsoon (EAM) precipitation, and allows us to reconstruct changes in Nile River runoff, vegetation and erosion in the Nile headwaters. Sediment element composition and neodymium isotopic composition reveal significant changes in clastic sediment provenance, with sources oscillating between a Saharan aeolian contribution during the Last Glacial Maximum/deglacial transition and during the Late Holocene, and a Blue/Atbara Nile fluvial contribution during the African Humid Period (AHP). This study provides a new understanding of past environmental changes. Between 14.6 and 14.13 ka there was a major input of sediments from the Ethiopian Highlands, consistent with a stronger EAM at that time. Climate in the Nile basin was wetter between 14.8 and 8.4 ka, with a corresponding increase in Blue Nile water and sediment discharge via the main Nile into the Eastern Mediterranean. The gradual climatic transition from the AHP to the present-day dry climate was reflected in a decrease in Blue Nile sediment deposition and flood discharge between 8.4 and 3.7 ka, with aridity at a maximum between 3.7 and 2.6 ka. The onset of drier conditions in the Blue Nile basin seems to have begun before the 8.2 ka cooling event in the North Atlantic. We speculate that the climatic change from the wet AHP to the dry late Holocene may have been a result of a break in the low latitude dynamic equilibrium between climate, vegetation and erosion, which may in turn have affected the climate in higher latitudes. Reduced Nile flow may also have had an impact on Levantine Intermediate Water originating in the Eastern Mediterranean through an increase in intermediate water formation.

  16. Measurement of radioactivity levels in soil in the Nile Delta and middle Egypt.

    PubMed

    Ibrahiem, N M; Abd el Ghani, A H; Shawky, S M; Ashraf, E M; Farouk, M A

    1993-06-01

    Concentrations of radionuclides in surface soil across the Nile Delta, the north coast of Egypt, and Middle Egypt have been measured using a hyperpure germanium spectrometer. The concentrations obtained for 40K, the 232Th series, and the 226Ra series are expressed in Bq kg-1 of dry weight, and the exposure rates are expressed in nGy h-1 of wet weight. The activity concentrations of 137Cs in soil are expressed in Bq m-2.

  17. A 7500-year strontium isotope record from the northwestern Nile delta (Maryut lagoon, Egypt)

    NASA Astrophysics Data System (ADS)

    Flaux, Clément; Claude, Christelle; Marriner, Nick; Morhange, Christophe

    2013-10-01

    During the Holocene, delta evolution has been collectively mediated by relative sea-level changes, continental hydrology and human impacts. In this paper, we present a strontium isotope record from the Maryut lagoon (northwestern Nile delta) to quantify the interplay between relative sea-level variations and Nile flow changes during the past 7500 years. 87Sr/86Sr stratigraphy allows five hydrological stages to be defined. (1) The marine transgression of the area is dated to ˜7.5 ka cal. BP, with a clear marine 87Sr/86Sr signature (0.70905-0.7091). (2) Between ˜7 and ˜5.5 ka, in the context of the so-called African Humid Period (AHP), freshwater inputs became progressively predominant in the Maryut's hydrology. Deceleration of sea-level rise coupled with high Nile discharge induced coastal progradation which led to the progressive closure of the Maryut lagoon. (3) Between ˜5.5 and ˜3.8 ka, the end of the AHP is translated by a progressive hydrological shift from a Nile-dominated to a marine-dominated lagoon (87Sr/86Sr shifts from 0.70865 to 0.7088 to 0.70905-0.70915). (4) From ˜2.8 to ˜1.7 ka, 87Sr/86Sr ratios shift towards lower values (0.7084). Although this change is not precisely resolved because of a hiatus in the Maryut's sedimentary record, the 87Sr/86Sr transition from sea-like to Nile-dominated values is attributed to irrigation practices since the early Ptolemaic period (i.e. since ˜2.3 ka), including the Alexandria canal which played a key role in isolating the Maryut from the Mediterranean sea. (5) The final phase of the record covers the period between ˜1.7 and ˜0.2 ka. 87Sr/86Sr ratios indicate high freshwater inputs (from 0.7080 to 0.7085), except between 1.2 and 1.1 to ˜0.7 ka, when a Maryut lowstand and seawater intrusion are attested. In modern times, the Nile's coastal lagoons have been increasingly supplied by freshwater linked to the diversion of waters from the two Nile branches into the irrigation system. It is suggested that this

  18. Metal pollution loading, Manzalah lagoon, Nile delta, Egypt: Implications for aquaculture

    SciTech Connect

    Siegel, F.R.; Slaboda, M.L.; Stanley, D.J.

    1994-03-01

    High cultural enrichment factors are found for Hg (13 x), Pb (22.1 x), and other potentially toxic metals (e.g., Sn, Zn, Cu, Ag) in the upper 20 cm of sediment cores from the southeastern Ginka subbasin of Manzalah lagoon, Nile delta, Egypt. Cores from other areas of the lagoon show little metal loading. Metal loading followed the closure of the Aswan High Dam, the availability of abundant cheap electricity, and the development of major power-based industries. Industrial wastes containing potentially toxic metals are dumped into the Nile delta drain system. The load carried by Bahr El-Baqar drain discharges into the Ginka subbasin, which acts as a sink and results in metal loading of the sediment deposited there. Further development of aquaculture in this subbasin, of food-stuff agriculture on recently reclaimed lagoon bottom, or where irrigation waters come from Bahr El-Baqar drain or its discharge should be halted or strictly limited until potentially toxic metals in the drain waters and sediment are removed and polluted input drastically reduced. This environmental assessment of heavy metals in aquaculture or agriculture development should extend to other waterbodies in the northern Nile delta, particularly Idku lagoon and Lake Mariut, where industrial metal-bearing wastes discharge into the waterbodies. 21 refs., 7 figs., 3 tabs.

  19. Metal pollution loading, Manzalah lagoon, Nile delta, Egypt: Implications for aquaculture

    NASA Astrophysics Data System (ADS)

    Siegel, F. R.; Slaboda, M. L.; Stanley, D. J.

    1994-03-01

    High cultural enrichment factors are found for Hg (13×), Pb (22.1×), and other potentially toxic metals (e.g., Sn, Zn, Cu, Ag) in the upper 20 cm of sediment cores from the southeastern Ginka subbasin of Manzalah lagoon, Nile delta, Egypt. Cores from other areas of the lagoon show little metal loading. Metal loading followed the closure of the Aswan High Dam, the availability of abundant cheap electricity, and the development of major power-based industries. Industrial wastes containing potentially toxic metals are dumped into the Nile delta drain system. The load carried by Bahr El-Baqar drain discharges into the Ginka subbasin, which acts as a sink and results in metal loading of the sediment deposited there. Further development of aquaculture in this subbasin, of food-stuff agriculture on recently reclaimed lagoon bottom, or where irrigation waters come from Bahr El-Baqar drain or its discharge should be halted or strictly limited until potentially toxic metals in the drain waters and sediment are removed and polluted input drastically reduced. This environmental assessment of heavy metals in aquaculture or agriculture development should extend to other waterbodies in the northern Nile delta, particularly Idku lagoon and lake Mariut, where industrial metal-bearing wastes discharge into the waterbodies.

  20. From Natural to Design River Deltas

    NASA Astrophysics Data System (ADS)

    Giosan, Liviu

    2016-04-01

    Productive and biologically diverse, deltaic lowlands attracted humans since prehistory and may have spurred the emergence of the first urban civilizations. Deltas continued to be an important nexus for economic development across the world and are currently home for over half a billion people. But recently, under the double whammy of sea level rise and inland sediment capture behind dams, they have become the most threatened coastal landscape. Here I will address several deceptively simple questions to sketch some unexpected answers using example deltas from across the world from the Arctic to the Tropics, from the Danube to the Indus, Mississippi to Godavari and Krishna, Mackenzie to Yukon. What is a river delta? What is natural and what is not in a river delta? Are the geological and human histories of a delta important for its current management? Is maintaining a delta the same to building a new one? Can we design better deltas than Nature? These answers help us see clearly that survival of deltas in the next century depends on human intervention and is neither assured nor simple to address or universally applicable. Empirical observations on the hydrology, geology, biology and biochemistry of deltas are significantly lagging behind modeling capabilities endangering the applicability of numerical-based reconstruction solutions and need to be ramped up significantly and rapidly across the world.

  1. High resolution sequence stratigraphic analysis of the Late Miocene Abu Madi Formation, Northern Nile Delta Basin

    NASA Astrophysics Data System (ADS)

    Sarhan, Mohammad Abdelfattah

    2015-12-01

    Abu Madi Formation represents the Upper Miocene Messinian age in the Nile Delta basin. It consists mainly of sandstones and shale intercalations and because of its richness in hydrocarbon, it has been subdivided by the petroleum companies into Level-I, Level-II and Level-III, respectively according to the increase in the sandstone to the shale ratio. The Miocene cycle in the northern subsurface section of the Nile Delta encompasses three main formations namely from the base; Sidi Salim formation, Qawasim Formation and Abu Madi Formation at the top. The high resolution sequence stratigraphic analysis, using gamma ray responses, has been done for the Late Miocene formation in the northern part of the Nile delta subsurface section. For this purpose, the gamma-ray logs of ten deep wells, arranged in four cross-sections trending in almost north-south direction throughout the northern region of the Nile Delta, were analyzed. The analysis has revealed that the interpreted 4th order depositional cycles within Abu Madi Formation display great variations in both number and gamma ray responses in each investigated well, and cannot be traced laterally, even in the nearest well. These variations in the interpreted 4th order depositional sequences could be attributed to the presence of normal faults buried in the inter-area laying between the investigated wells. This finding matches with the conclusion of that Abu Madi Formation represents a part of the Upper Miocene Nile Delta syn-rift megasequence, developed during the Upper Miocene rift phase of the Red Sea - Gulf of Suez province in Egypt. Accordingly, in the sequence stratigraphic approach, the depositional history of Abu Madi Formation was strongly overprinted by the tectonic controls rather than the relative sea-level changes which are assumed to be of a secondary influence. Regarding the hydrocarbon aspects of the Abu Madi Formation, the present work recommends to direct the drilling efforts into the stratigraphic traps

  2. Water Management Strategy in Assessing the Water Scarcity in Northern Western Region of Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Mabrouk, Badr; Arafa, Salah; Gemajl, Khaled

    2015-04-01

    Sustainable development in the Nile Delta of Egypt is retarded by serious environmental problems, where land-use and land-cover of the region are subjected to continuous changes; including shoreline changes either by erosion or accretion, subsidence of the delta, as well as by sea level rise due to climate change. The current research attempts to; (1) study the vulnerability of the northern western region of the Nile Delta coastal zone to climate change/sea level rise while setting basic challenges, review adaptation strategies based on adaptation policy framework, and highlight recommended programs for preparedness to climate change, (2) study the scarcity of water resources in the area of study with review of the socioeconomic impacts and the critical need of establishing desalination plants with new standards assessing the environmental situation and population clusters, and (3) monitor of the brine water extracted from the desalination plants and injected to subsurface strata. This monitoring process is divided into 3 main directions: 1) studying the chemical characteristics of water extracted from the water desalinations plants qualitatively and quantitatively. 2) mapping the subsurface of which that brine water will be injected to it and the flow directions and effects using resistivity data, and 3) using GIS and suitable numerical models in order to study the effect, volume, flow of the brine water and its long term environmental impacts on the area. The results indicate that the area is particularly vulnerable to the impact of SLR, salt water intrusion, the deterioration of coastal tourism and the impact of extreme dust storms. This in turn will directly affect the agricultural productivity and human settlements in coastal zones. The paper presents different scenarios for water management and recommends the most suitable scenarios in order to establish a core for water management strategy in the region according to existing socio-economic and environmental

  3. Spectroscopic analyses of soil samples outside Nile Delta of Egypt.

    PubMed

    Fakhry, Ahmed; Osman, Osama; Ezzat, Hend; Ibrahim, Medhat

    2016-11-01

    Soil in Egypt, especially around Delta is exposed to various pollutants which are affecting adversely soil fertility and stability. Humic Acids (HA) as a main part of soil organic matter (SOM) represent the heart of the interaction process of inorganic pollutants with soil. Consequently, Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonances (NMR) were used to characterize soil, sediment and extracted HA. Resulting data confirmed that the HA was responsible for transporting inorganic pollutants from surface to subsurface reaching the ground water, which may represent a high risk on public health. The transport process is coming as carboxyl in surface soil changed into metal carboxylate then transferred into the carboxyl in bottom soil.

  4. Spectroscopic analyses of soil samples outside Nile Delta of Egypt

    NASA Astrophysics Data System (ADS)

    Fakhry, Ahmed; Osman, Osama; Ezzat, Hend; Ibrahim, Medhat

    2016-11-01

    Soil in Egypt, especially around Delta is exposed to various pollutants which are affecting adversely soil fertility and stability. Humic Acids (HA) as a main part of soil organic matter (SOM) represent the heart of the interaction process of inorganic pollutants with soil. Consequently, Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonances (NMR) were used to characterize soil, sediment and extracted HA. Resulting data confirmed that the HA was responsible for transporting inorganic pollutants from surface to subsurface reaching the ground water, which may represent a high risk on public health. The transport process is coming as carboxyl in surface soil changed into metal carboxylate then transferred into the carboxyl in bottom soil.

  5. Spectroscopic analyses of soil samples outside Nile Delta of Egypt.

    PubMed

    Fakhry, Ahmed; Osman, Osama; Ezzat, Hend; Ibrahim, Medhat

    2016-11-01

    Soil in Egypt, especially around Delta is exposed to various pollutants which are affecting adversely soil fertility and stability. Humic Acids (HA) as a main part of soil organic matter (SOM) represent the heart of the interaction process of inorganic pollutants with soil. Consequently, Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonances (NMR) were used to characterize soil, sediment and extracted HA. Resulting data confirmed that the HA was responsible for transporting inorganic pollutants from surface to subsurface reaching the ground water, which may represent a high risk on public health. The transport process is coming as carboxyl in surface soil changed into metal carboxylate then transferred into the carboxyl in bottom soil. PMID:27294554

  6. A new model of river dynamics, hydroclimatic change and human settlement in the Nile Valley derived from meta-analysis of the Holocene fluvial archive

    NASA Astrophysics Data System (ADS)

    Macklin, Mark G.; Toonen, Willem H. J.; Woodward, Jamie C.; Williams, Martin A. J.; Flaux, Clément; Marriner, Nick; Nicoll, Kathleen; Verstraeten, Gert; Spencer, Neal; Welsby, Derek

    2015-12-01

    In the Nile catchment, a growing number of site- and reach-based studies employ radiocarbon and, more recently, OSL dating to reconstruct Holocene river histories, but there has been no attempt to critically evaluate and synthesise these data at the catchment scale. We present the first meta-analysis of published and publically available radiocarbon and OSL dated Holocene fluvial units in the Nile catchment, including the delta region, and relate this to changing climate and river dynamics. Dated fluvial units are separated both geographically (into the Nile Delta and White, Blue, and Desert Nile sub-regions) and into depositional environment (floodplain and palaeochannel fills). Cumulative probability density frequency (CPDF) plots of floodplain and palaeochannel units show a striking inverse relationship during the Holocene, reflecting abrupt (<100 years) climate-related changes in flooding regime. The CPDF plot of dated floodplain units is interpreted as a record of over-bank river flows, whilst the CPDF plot of palaeochannel units reflect periods of major flooding associated with channel abandonment and contraction, as well as transitions to multi-centennial length episodes of greater aridity and low river flow. This analysis has identified major changes in river flow and dynamics in the Nile catchment with phases of channel and floodplain contraction at c. 6150-5750, 4400-4150, 3700-3450, 2700-2250, 1350-900, 800-550 cal. BC and cal. AD 1600, timeframes that mark shifts to new hydrological and geomorphological regimes. We discuss the impacts of these changing hydromorphological regimes upon riverine civilizations in the Nile Valley.

  7. Serum Cadmium Levels in Pancreatic Cancer Patients from the East Nile Delta Region of Egypt

    PubMed Central

    Kriegel, Alison M.; Soliman, Amr S.; Zhang, Qing; El-Ghawalby, Nabih; Ezzat, Farouk; Soultan, Ahmed; Abdel-Wahab, Mohamed; Fathy, Omar; Ebidi, Gamal; Bassiouni, Nadia; Hamilton, Stanley R.; Abbruzzese, James L.; Lacey, Michelle R.; Blake, Diane A.

    2006-01-01

    The northeast Nile Delta region exhibits a high incidence of early-onset pancreatic cancer. It is well documented that this region has one of the highest levels of pollution in Egypt. Epidemiologic studies have suggested that cadmium, a prevalent pollutant in the northeast Nile Delta region, plays a role in the development of pancreatic cancer. Objective: We aimed to assess serum cadmium levels as markers of exposure in pancreatic cancer patients and noncancer comparison subjects from the same region in Egypt. Design and Participants: We assessed serum cadmium levels of 31 newly diagnosed pancreatic cancer patients and 52 hospital comparison subjects from Mansoura, Egypt. Evaluation/Measurements: Serum cadmium levels were measured using a novel immunoassay procedure. Results: We found a significant difference between the mean serum cadmium levels in patients versus comparison subjects (mean ± SD, 11.1 ± 7.7 ng/mL vs. 7.1 ± 5.0 ng/mL, respectively; p = 0.012) but not in age, sex, residence, occupation, or smoking status. The odds ratio (OR) for pancreatic cancer risk was significant for serum cadmium level [OR = 1.12; 95% confidence interval (CI), 1.04–1.23; p = 0.0089] and farming (OR = 3.25; 95% CI, 1.03–11.64; p = 0.0475) but not for age, sex, residence, or smoking status. Conclusions: The results from this pilot study suggest that pancreatic cancer in the East Nile Delta region is significantly associated with high levels of serum cadmium and farming. Relevance to Clinical Practice/Public Health: Future studies should further investigate the etiologic relationship between cadmium exposure and pancreatic carcinogenesis in cadmium-exposed populations. PMID:16393667

  8. Ecological implications of heavy metal concentrations in the sediments of Burullus Lagoon of Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Chen, Zhongyuan; Salem, Alaa; Xu, Zhuang; Zhang, Weiguo

    2010-02-01

    This paper examines the spatial and temporal distribution of heavy metals (Fe, Al, Cu, Zn, Mn, Cd, Pb and Ni) from three short sediment cores collected from Burullus lagoon of the Nile delta, Egypt. 210Pb and 137Cs measurement is applied to understand sedimentation rate and related chronology. Remarkably low isotopic activities and intensive bioturbation in the lagoonal sediments rendered age determination difficult. Samples with detectable 137Cs in the upper core sediments together with sediment lithology could help infer a sedimentation rate of about 2.0 mm yr -1, thereby indicating post-dam (after 1964) sedimentation of the upper 10-cm core sediments. Our results demonstrate that most heavy metals in the surficial sediments after normalization to Al decrease seaward, showing a function of distance to the sewerage outlet on the inland lake coast. Also, there is an upwardly increasing trend of normalized heavy metals, especially in the upper 10-cm core sediments. Relevancy analysis has identified Mn, Pb and Cd as the diagnostic heavy metals in Burullus lagoon, most likely derived from Tanta and Kafrelsheihk, the major downtowns in the central Nile delta plain, from where wastewaters are directly discharging into the lake via canal networks. Although Burullus lagoon is presently least affected by pollution as compared to other major lagoons of the Nile delta, the increasing quantities of diagnostic metals, especially Mn, are extremely toxic, as they are potentially linked to the risks of digestive issues and pancreatic cancer reportedly. The situation calls for a rational planning for sewerage treatment in the protected Burullus coast.

  9. Lead levels in whole blood of sheep from different areas of the Nile delta.

    PubMed

    Takla, P G; Mohamed, H A; Wright, J; Fahmy, F

    1989-03-25

    The concentration of lead has been determined in samples of whole blood from Osimi and Rahmani sheep grazing near main highways in three areas of the Nile delta region of Egypt. Between 117 and 200 blood samples were collected from each area. The mean values for the blood lead content were 0.062, 0.067 and 0.083 micrograms/ml, and were low in all the locations. The value of 0.083 micrograms/ml obtained for the samples taken from the partly industralised Enshass region was significantly higher than the mean values from the other sites. PMID:2728270

  10. Investigation of potential sea level rise impact on the Nile Delta, Egypt using digital elevation models.

    PubMed

    Hasan, Emad; Khan, Sadiq Ibrahim; Hong, Yang

    2015-10-01

    In this study, the future impact of Sea Level Rise (SLR) on the Nile Delta region in Egypt is assessed by evaluating the elevations of two freely available Digital Elevation Models (DEMs): the SRTM and the ASTER-GDEM-V2. The SLR is a significant worldwide dilemma that has been triggered by recent climatic changes. In Egypt, the Nile Delta is projected to face SLR of 1 m by the end of the 21th century. In order to provide a more accurate assessment of the future SLR impact on Nile Delta's land and population, this study corrected the DEM's elevations by using linear regression model with ground elevations from GPS survey. The information for the land cover types and future population numbers were derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover and the Gridded Population of the Worlds (GPWv3) datasets respectively. The DEM's vertical accuracies were assessed using GPS measurements and the uncertainty analysis revealed that the SRTM-DEM has positive bias of 2.5 m, while the ASTER-GDEM-V2 showed a positive bias of 0.8 m. The future inundated land cover areas and the affected population were illustrated based on two SLR scenarios of 0.5 m and 1 m. The SRTM DEM data indicated that 1 m SLR will affect about 3900 km(2) of cropland, 1280 km(2) of vegetation, 205 km(2) of wetland, 146 km(2) of urban areas and cause more than 6 million people to lose their houses. The overall vulnerability assessment using ASTER-GDEM-V2 indicated that the influence of SLR will be intense and confined along the coastal areas. For instance, the data indicated that 1 m SLR will inundate about 580 Km(2) (6%) of the total land cover areas and approximately 887 thousand people will be relocated. Accordingly, the uncertainty analysis of the DEM's elevations revealed that the ASTER-GDEM-V2 dataset product was considered the best to determine the future impact of SLR on the Nile Delta region. PMID:26410824

  11. Investigation of potential sea level rise impact on the Nile Delta, Egypt using digital elevation models.

    PubMed

    Hasan, Emad; Khan, Sadiq Ibrahim; Hong, Yang

    2015-10-01

    In this study, the future impact of Sea Level Rise (SLR) on the Nile Delta region in Egypt is assessed by evaluating the elevations of two freely available Digital Elevation Models (DEMs): the SRTM and the ASTER-GDEM-V2. The SLR is a significant worldwide dilemma that has been triggered by recent climatic changes. In Egypt, the Nile Delta is projected to face SLR of 1 m by the end of the 21th century. In order to provide a more accurate assessment of the future SLR impact on Nile Delta's land and population, this study corrected the DEM's elevations by using linear regression model with ground elevations from GPS survey. The information for the land cover types and future population numbers were derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover and the Gridded Population of the Worlds (GPWv3) datasets respectively. The DEM's vertical accuracies were assessed using GPS measurements and the uncertainty analysis revealed that the SRTM-DEM has positive bias of 2.5 m, while the ASTER-GDEM-V2 showed a positive bias of 0.8 m. The future inundated land cover areas and the affected population were illustrated based on two SLR scenarios of 0.5 m and 1 m. The SRTM DEM data indicated that 1 m SLR will affect about 3900 km(2) of cropland, 1280 km(2) of vegetation, 205 km(2) of wetland, 146 km(2) of urban areas and cause more than 6 million people to lose their houses. The overall vulnerability assessment using ASTER-GDEM-V2 indicated that the influence of SLR will be intense and confined along the coastal areas. For instance, the data indicated that 1 m SLR will inundate about 580 Km(2) (6%) of the total land cover areas and approximately 887 thousand people will be relocated. Accordingly, the uncertainty analysis of the DEM's elevations revealed that the ASTER-GDEM-V2 dataset product was considered the best to determine the future impact of SLR on the Nile Delta region.

  12. Lena River Delta formation during the Holocene

    NASA Astrophysics Data System (ADS)

    Bolshiyanov, D.; Makarov, A.; Savelieva, L.

    2014-03-01

    The Lena River Delta, the largest delta of the Arctic Ocean, differs from other deltas because it consists mainly of organomineral sediments, commonly called peat, that contain a huge organic carbon reservoir. The analysis of Delta sediment radiocarbon ages showed that they could not have formed as peat during floodplain bogging, but accumulated when Laptev Sea water level was high and green mosses and sedges grew and were deposited on the surface of flooded marshes. The Lena River Delta formed as organomineral masses and layered sediments accumulated during transgressive phases when sea level rose. In regressive phases, the islands composed of these sediments and other, more ancient islands were eroded. Each new sea transgression led to further accumulation of layered sediments. As a result of alternating transgressive and regressive phases the first alluvial-marine terrace formed, consisting of geological bodies of different ages. Determining the formation age of different areas of the first terrace and other marine terraces on the coast allowed the periods of increasing (8-6 Ka, 4.5-4 Ka, 2.5-1.5 Ka, 0.4-0.2 Ka) and decreasing (5 Ka, 3 Ka, 0.5 Ka) Laptev Sea levels to be distinguished in the Lena Delta area.

  13. Lena River delta formation during the Holocene

    NASA Astrophysics Data System (ADS)

    Bolshiyanov, D.; Makarov, A.; Savelieva, L.

    2015-01-01

    The Lena River delta, the largest delta of the Arctic Ocean, differs from other deltas because it consists mainly of organomineral sediments, commonly called peat, that contain a huge organic carbon reservoir. The analysis of delta sediment radiocarbon ages showed that they could not have formed as peat during floodplain bogging; rather, they accumulated when Laptev Sea water level was high and green mosses and sedges grew and were deposited on the surface of flooded marshes. The Lena River delta formed as organomineral masses and layered sediments accumulated during transgressive phases when sea level rose. In regressive phases, the islands composed of these sediments and other, more ancient islands were eroded. Each new sea transgression led to further accumulation of layered sediments. As a result of alternating transgressive and regressive phases, the first alluvial-marine terrace formed, consisting of geological bodies of different ages. Determining the formation age of different areas of the first terrace and other marine terraces on the coast allowed the periods of increasing (8000-6000 BP (years before present), 4500-4000, 2500-1500, and 400-200 BP) and decreasing (5000, 3000, and 500 BP) Laptev Sea levels to be distinguished in the Lena Delta area.

  14. Lake Nasser on Nile River in Egypt as seen from the Apollo 7 spacecraft

    NASA Technical Reports Server (NTRS)

    1968-01-01

    Lake Nasser on the Nile River in southeastern United Arab Republic (Egypt) as seen from the Apollo 7 spacecraft during its 10th revolution of the earth. Photographed from an altitude of 130 nautical miles, at ground elapsed time of 14 hours and 56 minutes. Lake Nasser was created by the contruction of the Aswan Dam on the Nile.

  15. Tidal river dynamics: Implications for deltas

    NASA Astrophysics Data System (ADS)

    Hoitink, A. J. F.; Jay, D. A.

    2016-03-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity intrusion, a realm that can extend inland hundreds of kilometers. One key phenomenon resulting from this interaction is the emergence of large fortnightly tides, which are forced long waves with amplitudes that may increase beyond the point where astronomical tides have become extinct. These can be larger than the linear tide itself at more landward locations, and they greatly influence tidal river water levels and wetland inundation. Exploration of the spectral redistribution and attenuation of tidal energy in rivers has led to new appreciation of a wide range of consequences for fluvial and coastal sedimentology, delta evolution, wetland conservation, and salinity intrusion under the influence of sea level rise and delta subsidence. Modern research aims at unifying traditional harmonic tidal analysis, nonparametric regression techniques, and the existing understanding of tidal hydrodynamics to better predict and model tidal river dynamics both in single-thread channels and in branching channel networks. In this context, this review summarizes results from field observations and modeling studies set in tidal river environments as diverse as the Amazon in Brazil, the Columbia, Fraser and Saint Lawrence in North America, the Yangtze and Pearl in China, and the Berau and Mahakam in Indonesia. A description of state-of-the-art methods for a comprehensive analysis of water levels, wave propagation, discharges, and inundation extent in tidal rivers is provided. Implications for lowland river deltas are also discussed in terms of sedimentary deposits, channel bifurcation, avulsion, and salinity intrusion, addressing contemporary research challenges.

  16. Explaining and Forecasting Interannual Variability in the Flow of the Nile River

    NASA Astrophysics Data System (ADS)

    Eltahir, E. A.; Siam, M.

    2013-12-01

    The natural interannual variability in the flow of Nile River had a significant impact on the ancient civilizations and cultures that flourished on the banks of the river. Here, we analyze extensive data sets collected during the 20th century and define four modes of natural variability in the flow of Nile River, identifying a new significant potential for improving predictability of floods and droughts. Previous studies have identified a significant teleconnection between the Nile flow and the Eastern Pacific Ocean. El Niño-Southern Oscillation (ENSO) explains about 25% of the interannual variability in the Nile flow. Here, we identify, for the first time, a region in the southern Indian Ocean with similarly strong teleconnection to the Nile flow. Sea Surface Temperature (SST) in the region (60oE-90oE and 25oS-35oS) explains 28% of the interannual variability in the Nile flow. During those years with anomalous SST conditions in both Oceans, we estimate that indices of the SSTs in the Pacific and Indian Oceans can collectively explain up to 84% of the interannual variability in the flow of Nile. Building on these findings, we use classical Bayesian theorem to develop a new hybrid forecasting algorithm that predicts the Nile flow based on indices of the SST in the Eastern Pacific and Southern Indian Oceans.

  17. Explaining and forecasting interannual variability in the flow of the Nile River

    NASA Astrophysics Data System (ADS)

    Siam, M. S.; Eltahir, E. A. B.

    2014-05-01

    The natural interannual variability in the flow of Nile River had a significant impact on the ancient civilizations and cultures that flourished on the banks of the river. This is evident from stories in the Bible and Koran, and from the numerous Nilometers discovered near ancient temples. Here, we analyze extensive data sets collected during the 20th century and define four modes of natural variability in the flow of Nile River, identifying a new significant potential for improving predictability of floods and droughts. Previous studies have identified a significant teleconnection between the Nile flow and the Eastern Pacific Ocean. El Niño-Southern Oscillation (ENSO) explains about 25% of the interannual variability in the Nile flow. Here, we identify, for the first time, a region in the southern Indian Ocean with similarly strong teleconnection to the Nile flow. Sea Surface Temperature (SST) in the region (50-80° E and 25-35° S) explains 28% of the interannual variability in the Nile flow. During those years with anomalous SST conditions in both Oceans, we estimate that indices of the SSTs in the Pacific and Indian Oceans can collectively explain up to 84% of the interannual variability in the flow of Nile. Building on these findings, we use classical Bayesian theorem to develop a new hybrid forecasting algorithm that predicts the Nile flow based on global models predictions of indices of the SST in the Eastern Pacific and Southern Indian Oceans.

  18. Quantitative Metrics of Robustness in River Deltas

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, E.; Tejedor, A.; Longjas, A.; Zaliapin, I. V.

    2014-12-01

    Deltas are landforms with channels that deliver water, sediment and nutrient fluxes from rivers to oceans or inland water bodies via multiple pathways. We conceptualize a delta channel network as a rooted acyclic directed graph where channels are modeled by edges and junctions by vertices. We use spectral graph theory - mainly the geometry of the null space of the directed weighted graph Laplacian - to establish a quantitative framework for extracting important structural and dynamics-related information from river deltas. Using this information, we introduce refined metrics of system complexity, such as entropy. Entropy has been proven to be an important measure of the amount of uncertainty in stochastic systems, and therefore a surrogate of the capacity of the system to undergo changes. Here we present an entropic approach to evaluate the robustness of deltas, showing how the two components of entropy: mutual information and conditional entropy can be interpreted in this framework. We also present other metrics that include, among others, resistance distance and number of alternative paths, which quantify the structural complexity of the system. We use these metrics to better classify deltaic systems, quantify their resilience and propose possible management scenarios.

  19. A Journey on Three Rivers: The Nile, The Rhine, The Mississippi.

    ERIC Educational Resources Information Center

    Allen, Anita

    1996-01-01

    Focuses on the Nile, the Rhine, and the Mississippi, the greatest rivers of Africa, Europe, and North America, respectively. Highlights the rich diversity of subjects associated with rivers including geography, history, literature, and art. Includes 12 learning activities for each river. (MJP)

  20. Holocene palaeo-environments on the western coast of the Nile Delta: local and basin-wide forcing factors

    NASA Astrophysics Data System (ADS)

    Flaux, Clément; Véron, Alain; Marriner, Nick; el-Assal, Mena; Claude, Christelle; Morhange, Christophe

    2014-05-01

    The Canopic branch, which is today either silted up and cultivated or re-used in the modern drainage network, was the main channel for the western Nile Delta during Antiquity. Ancient Canopic flow used to supply the water network on the deltaic margin, including secondary tributaries, the Maryut lake, and irrigation agriculture and urban needs. We present new data obtained from a sediment core taken close to the palaeo-Canopic channel. Lead (Pb) isotopic analyses of bulk sediments, together with sedimentology, macro- and micro-fauna assemblages, magnetic susceptibility and radiocarbon dates provide evidence for environmental changes at the Canopic mouth in addition to changes in Nile sediment sources during the last 6000 years. Alternation of estuarine to lagoonal and peaty biofacies have recorded stages of transgression and progradation. 206Pb/207Pb analyses suggest a change in dominant sediment load from the White Nile to Blue Nile between 6000 and 5000 years cal. BP. The dataset is then compared and contrasted with previous studies, including: (1) a dense grid of dated bio-sedimentological cores data from the northwestern Nile Delta; (2) strontium isotope records of water and sediment fluxes on the delta; and (3) geochemical records from offshore sediment cores. Our analysis attempts to date and discriminate between basin-wide and regional to local forcing agents driving environmental changes at the mouth of the Canopic. The three main factors discussed will include climatic forcing of Nile flow and load changes, relative sea-level variations, and human impacts on the Canopic flow.

  1. Shifting sediment sources in the world's longest river: A strontium isotope record for the Holocene Nile

    NASA Astrophysics Data System (ADS)

    Woodward, Jamie; Macklin, Mark; Fielding, Laura; Millar, Ian; Spencer, Neal; Welsby, Derek; Williams, Martin

    2015-12-01

    We have reconstructed long-term shifts in catchment sediment sources by analysing, for the first time, the strontium (Sr) and neodymium (Nd) isotope composition of dated floodplain deposits in the Desert Nile. The sediment load of the Nile has been dominated by material from the Ethiopian Highlands for much of the Holocene, but tributary wadis and aeolian sediments in Sudan and Egypt have also made major contributions to valley floor sedimentation. The importance of these sources has shifted dramatically in response to global climate changes. During the African Humid Period, before c. 4.5 ka, when stronger boreal summer insolation produced much higher rainfall across North Africa, the Nile floodplain in northern Sudan shows a tributary wadi input of 40-50%. Thousands of tributary wadis were active at this time along the full length of the Saharan Nile in Egypt and Sudan. As the climate became drier after 4.5 ka, the valley floor shows an abrupt fall in wadi inputs and a stronger Blue Nile/Atbara contribution. In the arid New Kingdom and later periods, in palaeochannel fills on the margins of the valley floor, aeolian sediments replace wadi inputs as the most important secondary contributor to floodplain sedimentation. Our sediment source data do not show a measurable contribution from the White Nile to the floodplain deposits of northern Sudan over the last 8500 years. This can be explained by the distinctive hydrology and sediment delivery dynamics of the upper Nile basin. High strontium isotope ratios observed in delta and offshore records - that were previously ascribed to a stronger White Nile input during the African Humid Period - may have to be at least partly reassessed. Our floodplain Sr records also have major implications for bioarchaeologists who carry out Sr isotope-based investigations of ancient human remains in the Nile Valley because the isotopic signature of Nile floodplain deposits has shifted significantly over time.

  2. An approach for delineating drinking water wellhead protection areas at the Nile Delta, Egypt.

    PubMed

    Fadlelmawla, Amr A; Dawoud, Mohamed A

    2006-04-01

    In Egypt, production has a high priority. To this end protecting the quality of the groundwater, specifically when used for drinking water, and delineating protection areas around the drinking water wellheads for strict landuse restrictions is essential. The delineation methods are numerous; nonetheless, the uniqueness of the hydrogeological, institutional as well as social conditions in the Nile Delta region dictate a customized approach. The analysis of the hydrological conditions and land ownership at the Nile Delta indicates the need for an accurate methodology. On the other hand, attempting to calculate the wellhead protected areas around each of the drinking wells (more than 1500) requires data, human resources, and time that exceed the capabilities of the groundwater management agency. Accordingly, a combination of two methods (simplified variable shapes and numerical modeling) was adopted. Sensitivity analyses carried out using hypothetical modeling conditions have identified the pumping rate, clay thickness, hydraulic gradient, vertical conductivity of the clay, and the hydraulic conductivity as the most significant parameters in determining the dimensions of the wellhead protection areas (WHPAs). Tables of sets of WHPAs dimensions were calculated using synthetic modeling conditions representing the most common ranges of the significant parameters. Specific WHPA dimensions can be calculated by interpolation, utilizing the produced tables along with the operational and hydrogeological conditions for the well under consideration. In order to simplify the interpolation of the appropriate dimensions of the WHPAs from the calculated tables, an interactive computer program was written. The program accepts the real time data of the significant parameters as its input, and gives the appropriate WHPAs dimensions as its output.

  3. Morphodynamics of River Lowlands and Deltas: Combining Historical Maps with Satellite Data

    NASA Astrophysics Data System (ADS)

    Syvitski, J. P.; Hannon, M.; Kettner, A. J.; Jenkins, C. J.; Hutton, E. W.

    2007-12-01

    Cartographers have for centuries documented the courses of rivers and their delta's distributary channels. Yet these valuable historical maps have not often been placed into a Global Information System, and verified for their cartographic accuracy. We have obtained between 6 and 15 historical maps (17th - 20th century) for a set of global deltas (Indus, Ganges, Godavari, Krishna, Mahanadi, Brahmani, Yellow, Vistula Danube, Po, Rhone, Niger, Nile, Orinoco, Magdalena, Amazon, and Mississippi). The maps were examined for their registration accuracy, using the location of between 8 and 15 cities or towns. Those maps with RMS errors of less than 5 km had shape files established for the pathways of their rivers and distributary channels. Geolocated Space Shuttle Radar data were binned into 1 m topographic units (? 90 m horizontal footprint) for each river-delta system and used in combination with LANDSAT ETM+ (15-30 m horizontal footprint), as an underlay to each of the historical maps. The satellite data proved useful in verifying the historical courses of these channels, many of which are no longer active. Together the data provide valuable insight to the time dependent dynamics of distributary channel switching and migration, before the heavy anthropogenic footprint of the 20th century (river diversions through barrages, upstream damming of the sediment supply, mitigation of the seasonal flood wave, levee development and stabilization, human-affected delta subsidence, and agricultural infrastructure).

  4. Impacts of seawater rise on seawater intrusion in the Nile Delta Aquifer, Egypt.

    PubMed

    Sefelnasr, Ahmed; Sherif, Mohsen

    2014-01-01

    Several investigations have recently considered the possible impacts of climate change and seawater level rise on seawater intrusion in coastal aquifers. All have revealed the severity of the problem and the significance of the landward movement of the dispersion zone under the condition of seawater level rise. Most of the studies did not consider the possible effects of the seawater rise on the inland movement of the shoreline and the associate changes in the boundary conditions at the seaside and the domain geometry. Such effects become more evident in flat, low land, coastal alluvial plans where large areas might be submerged with seawater under a relatively small increase in the seawater level. None of the studies combined the effect of increased groundwater pumping, due to the possible decline in precipitation and shortage in surface water resources, with the expected landward shift of the shore line. In this article, the possible effects of seawater level rise in the Mediterranean Sea on the seawater intrusion problem in the Nile Delta Aquifer are investigated using FEFLOW. The simulations are conducted in horizontal view while considering the effect of the shoreline landward shift using digital elevation models. In addition to the basic run (current conditions), six different scenarios are considered. Scenarios one, two, and three assume a 0.5 m seawater rise while the total pumping is reduced by 50%, maintained as per the current conditions and doubled, respectively. Scenarios four, five, and six assume a 1.0 m seawater rise and the total pumping is changed as in the first three scenarios. The shoreline is moved to account for the seawater rise and hence the study domain and the seaside boundary are modified accordingly. It is concluded that, large areas in the coastal zone of the Nile Delta will be submerged by seawater and the coast line will shift landward by several kilometers in the eastern and western sides of the Delta. Scenario six represents

  5. Impacts of seawater rise on seawater intrusion in the Nile Delta Aquifer, Egypt.

    PubMed

    Sefelnasr, Ahmed; Sherif, Mohsen

    2014-01-01

    Several investigations have recently considered the possible impacts of climate change and seawater level rise on seawater intrusion in coastal aquifers. All have revealed the severity of the problem and the significance of the landward movement of the dispersion zone under the condition of seawater level rise. Most of the studies did not consider the possible effects of the seawater rise on the inland movement of the shoreline and the associate changes in the boundary conditions at the seaside and the domain geometry. Such effects become more evident in flat, low land, coastal alluvial plans where large areas might be submerged with seawater under a relatively small increase in the seawater level. None of the studies combined the effect of increased groundwater pumping, due to the possible decline in precipitation and shortage in surface water resources, with the expected landward shift of the shore line. In this article, the possible effects of seawater level rise in the Mediterranean Sea on the seawater intrusion problem in the Nile Delta Aquifer are investigated using FEFLOW. The simulations are conducted in horizontal view while considering the effect of the shoreline landward shift using digital elevation models. In addition to the basic run (current conditions), six different scenarios are considered. Scenarios one, two, and three assume a 0.5 m seawater rise while the total pumping is reduced by 50%, maintained as per the current conditions and doubled, respectively. Scenarios four, five, and six assume a 1.0 m seawater rise and the total pumping is changed as in the first three scenarios. The shoreline is moved to account for the seawater rise and hence the study domain and the seaside boundary are modified accordingly. It is concluded that, large areas in the coastal zone of the Nile Delta will be submerged by seawater and the coast line will shift landward by several kilometers in the eastern and western sides of the Delta. Scenario six represents

  6. Hydroclimate variability in the Nile River Basin during the past 28,000 years

    NASA Astrophysics Data System (ADS)

    Castañeda, Isla S.; Schouten, Stefan; Pätzold, Jürgen; Lucassen, Friedrich; Kasemann, Simone; Kuhlmann, Holger; Schefuß, Enno

    2016-03-01

    It has long been known that extreme changes in North African hydroclimate occurred during the late Pleistocene yet many discrepancies exist between sites regarding the timing, duration and abruptness of events such as Heinrich Stadial (HS) 1 and the African Humid Period (AHP). The hydroclimate history of the Nile River is of particular interest due to its lengthy human occupation history yet there are presently few continuous archives from the Nile River corridor, and pre-Holocene studies are rare. Here we present new organic and inorganic geochemical records of Nile Basin hydroclimate from an eastern Mediterranean (EM) Sea sediment core spanning the past 28 ka BP. Our multi-proxy records reflect the fluctuating inputs of Blue Nile versus White Nile material to the EM Sea in response to gradual changes in local insolation and also capture abrupt hydroclimate events driven by remote climate forcings, such as HS1. We find strong evidence for extreme aridity within the Nile Basin evolving in two distinct phases during HS1, from 17.5 to 16 ka BP and from 16 to 14.5 ka BP, whereas peak wet conditions during the AHP are observed from 9 to 7 ka BP. We find that zonal movements of the Congo Air Boundary (CAB), and associated shifts in the dominant moisture source (Atlantic versus Indian Ocean moisture) to the Nile Basin, likely contributed to abrupt hydroclimate variability in northern East Africa during HS1 and the AHP as well as to non-linear behavior of hydroclimate proxies. We note that different proxies show variable gradual and abrupt responses to individual hydroclimate events, and thus might have different inherent sensitivities, which may be a factor contributing to the controversy surrounding the abruptness of past events such as the AHP. During the Late Pleistocene the Nile Basin experienced extreme hydroclimate fluctuations, which presumably impacted Paleolithic cultures residing along the Nile corridor.

  7. Elwha River Delta: Geomorphology of a Mixed-Sediment Beach

    NASA Astrophysics Data System (ADS)

    George, D. A.; Warrick, J. J.

    2007-12-01

    The Elwha River drains the Olympic Peninsula of Washington and forms a mixed grain-size delta in the Strait of Juan de Fuca. The Elwha River has been dammed for almost a century, and a pending dam removal project is expected to reconnect upstream sediment sources to the river mouth. Topographic and grain-size mapping of the delta during 1939-2007 is synthesized and the geomorphology and shoreline changes of this system are described. Data sources include historical aerial photographs, airborne LIDAR, semiannual RTK DGPS topographic surveys and grain-size analyses from digital photographs. The delta is divided into three geomorphic regions: west delta, river mouth and east delta. The river mouth is the most complex region due to the river channel movement, side-channels, and bars immediately offshore of the mouth. The east and west delta differ in beach profile and shoreline change rates. The west delta is steep, cuspate and lacks a low-tide terrace. Further, the west delta has exhibited little semi-annual or inter-annual shoreline change. In contrast, the east delta has a steep foreshore, flat low tide terrace that is dominated by cobble, and a consistent trend of erosion during the surveys. These observations can be used to track coastal changes following dam removal on the Elwha River..

  8. The Influence of Atmospheric Aerosols on Air Quality Status of the Egyptian Nile Delta

    NASA Astrophysics Data System (ADS)

    El-Askary, H. M.; Zakey, A.

    2014-12-01

    Due to the combination of natural and anthropogenic sources of emission over the Nile Delta region, the air quality status is very poor and has a significant health hazards impacts on the population. Here we focused on the optical and chemical characterizations of atmospheric aerosols in the Nile Delta using the online integrated Environmental-Climate Aerosols model (EnvClimA) during a 10 year period 2000-2010. Observations from MODIS and SeaWiFS measurements supplemented by CALIPSO and some ground-based data from AERONET, are used to validate the EnvClimA model and to illustrate the aerosol characteristics and their sources. CALIPSO measurements were used to characterize the vertical structure of aerosols and their shapes (spherical and non-spherical) for major dust storms and biomass burning events. In this study we discussed the synoptic patterns and features, which are associated with either the dust storm or high pollution events. We used MODIS derived aerosol parameters to study seasonal changes in aerosol parameters due to the influence of dust storms, anthropogenic pollution and biomass (crop residue) burning. MODIS derived deep blue AOD provided better representation of aerosol loading over north Africa (Sahara region) along with dark-target AOD and related parameters. AERONET data provided aerosol optical depth, angstrom, fine mode fraction, size fraction, volume, effective radius, refractive index, single scattering albedo, and radiative forcing during different seasons dominated by dust storms, anthropogenic pollution and biomass burning (black cloud phenomena). The results indicated that the observed AOD decreases in the summer and increases again in the fall due to agricultural burning events. Ground-based AERONET data support the "Dark Product" MODIS retrievals, as they typically show a fall peak in the 500 nm region. The number of dust distribution frequencies over Egypt has more frequency in the southeast and northwest of Egypt (5-7.5 days

  9. 3-D Seismic Images of Mud Volcano North Alex, West-Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Bialas, Joerg; Klaeschen, Dirk; Papenberg, Cord; Gehrmann, Romina; Sommer, Malte

    2010-05-01

    Mud volcanoes within shelf areas are the bathymetric expression of mobilized overpressured sediments causing a feature of possible instability within the slope. Such a scene is given in the West-Nile Delta offshore Alexandria, Egypt at 700 m water depth, ,which was studied during a RWE Dea funded research project. The West Nile Delta forms part of the source of the large turbiditic Nile Deep Sea Fan. Since the late Miocene sediments have formed an up to 10 km thick pile, which includes about 1 - 3 km of Messinian evaporates. The sediment load of the overburden implies strong overpressures and salt-related tectonic deformation. Both are favourable for fluid migration towards the seafloor guided by the fractured margin. Deep-cutting channel systems like the Rosetta channel characterize the continental slope. Bathymetric expressions of slides and numerous mud volcanoes in the area are expressions of active processes, which contribute to the ongoing modification of the slope. The western deltaic system, Rosetta branch, has formed an 80 km wide continental shelf. Here at 700 m water depth the mud volcano North Alex developed his circular bathymetric feature, which proved to be an active gas and mud-expelling structure. A grid of 2-D seismic profiles did reveal a large set of faults located within the main mud volcano as well as surrounding the structure. Internal faults are mainly related to episodic mud expulsion processes and continuous gas and fluid production. Deep cutting external faults surround the structure in a half circle shape. They can be tracked up to the seafloor indicating ongoing tectonic activity of the slope area. A recently build 3-D acquisition system (funded by RWE Dea) suitable for mid-size research vessels was applied to collect an active seismic cube of the mud volcano. Based on the P-Cable design 11 parallel streamers (each 12.5 m long with 1.5 m group interval) were used to record shots of a single 210 cinch GI airgun. Based on GPS positions of

  10. Near infrared spectroscopy techniques for soil contamination assessment in the Nile Delta

    NASA Astrophysics Data System (ADS)

    Mohamed, E. S.; Ali, A. M.; El Shirbeny, M. A.; Abd El Razek, Afaf A.; Savin, I. Yu.

    2016-06-01

    Heavy metals concentration is considered one of the factors directly affecting soil and crop quality and, thus, human health. The objective of the current work was to critically examine the suitability of Vis- NIR (350-2500 nm) measurements for calibration procedures and methods to predict contaminated soil. 25 different sites were selected adjacent to drain Bahr El-Baqar east of Nile Delta. Spectroradiometer ASD was used to measure the spectral reflectance profile of each soil site. The concentrations of three heavy metals (Cr, Mn and Cu) were determined in the studied samples. Stepwise multiple linear regression (SMLR) was used to construct calibration models subjected to the independent validation. The obtained regression models were of good quality ( R 2 = 0.82, 0.75, and 0.65 for Cr, Mn, and Cu, respectively). Thus, Visible and Nearinfrared (Vis-NIR) reflection spectroscopy is cost- and time-effective procedure that can be used as an alternative to the traditional methods of determination of heavy metals in soils.

  11. Egyptian propolis: 2. Chemical composition, antiviral and antimicrobial activities of East Nile Delta propolis.

    PubMed

    Abd El Hady, Faten K; Hegazi, Ahmed G

    2002-01-01

    Three propolis samples from East Nile Delta, Egypt were collected. Propolis samples were investigated by GC/MS,103 compounds were identified, 20 being new for propolis. Dakahlia propolis was a typical poplar propolis but it contained two new caffeate esters and two new triterpenoids. Ismailia propolis was characterized by the presence of new triterpenic acid methyl esters and it did not contain any aromatic acids, esters and flavonoids. Sharkia propolis was characterized by the presence of caffeate esters only, some di- and triterpenoids. The antiviral (Infectious Bursal Disease Virus and Reo-Virus) and antimicrobial (Staphylococcus aureus; Escherichia coli and Candida albicans) activities of propolis samples were investigated. Dakahlia propolis showed the highest antiviral activity against Infectious Bursal Disease Virus (IBDV) and the highest antibacterial activity against Escherichia coli and the highest antifungal activity against Candida albicans. While Ismailia propolis had the highest antiviral activity against Reo-virus. Sharkia propolis showed the highest antibacterial activity against Staphylococcus aureus and moderate antiviral activity against infectious bursal disease virus and reovirus.

  12. Holocene sequences distributed across the northern Nile delta, Egypt, as a function of tectonic, eustatic, and climatic controls

    SciTech Connect

    Stanley, D.J.; Arbouille, D.; Howa, H. )

    1991-03-01

    Analysis of the laterally variable lithofacies distributions in the Nile delta, Egypt, in recent time provides an opportunity to model the evolution of a very active depocenter, the largest on the North African margin. Of particular interest is the interplay of major factors controlling sedimentation. The changes of Holocene facies in time and space across the northern Nile delta have been mapped by means of sediment cores. This study is based on extensive petrological, geochemical, and biogenic analyses of more than 2000 samples in 65 cores. Most cores (length to 60 m) are radiocarbon dated, indicating that Holocene deltaic progradational sequences began to accumulate about 7500 years ago. The delta plain has been subsiding (from 0.04 to 0.50 cm/yr) and also tilting toward the northeast during this period. As a consequence, sediments have accumulated at long-term averaged rates of 0.1 to 0.5 cm/year, from west to east. Marked variations in temporal and lateral lithofacies distributions and sequence thicknesses are in part a direct consequence of asymmetric lowering of the delta plain surface during the period of sediment accumulation. On the one hand, classic complete deltaic coarsening-upward sequences consisting of open marine prodelta to coastal facies are restricted to the northeastern delta; this is largely a response to accelerated subsidence in this region. In contrast, sediment sections are reduced in thickness and comprise lithologically more irregular successions of delta plain deposits (distributary channel, marsh, lagoon) over most of the tectonically more stable north-central sector of the delta.

  13. Shoreline change in 48 river deltas: towards indexing erosion as a criterion of delta vulnerability

    NASA Astrophysics Data System (ADS)

    Besset, Manon; Anthony, Edward; Dussouillez, Philippe; Sabatier, François

    2016-04-01

    River deltas are considered as increasingly vulnerable to environmental modifications resulting from climate change and human activities. Delta vulnerability is associated with a number of drivers, chief among which are depleted sediment supply, changes in water discharge, and pumping of underground fluids. These activities lead to accelerated subsidence and erosion, the twin mechanisms of delta destruction. A lot of attention has been focused on vulnerability resulting from accelerated subsidence. Here, we address the problem of delta erosion based on the analysis of 48 deltas, including 30 of the world's largest deltas. Using satellite images (Landsat, Spot 5, Spot 6) and aerial photographs, we determined for each delta, the change in delta protruberance area over a 30-year period, this being defined as the area of delta protrusion relative to a straight shoreline running across the delta plain and linking the delta to the adjacent non-protruding non-deltaic shoreline. We classified the deltas in terms of net area loss, gain, or stability, the last corresponding to an uncertainty threshold of _0.3% of the delta's protruberance over the 30-year period. The results show that 25 (52%) of the studied set of deltas show area loss, 11 (23%) stability, and 12 (25%) gain. Area loss is more important in deltas with a protruberance area <500 km2 (67% of small deltas) than in the largest deltas (23%), with a protruberance area >500 km2. Besides sediment supply conditions, which are a primary factor in delta erosion, eroding deltas tend to be more commonly subjected to relatively significant levels of wave energy.

  14. Adaptation to the impact of sea level rise in the Northeastern Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Mabrouk, Badr; Farhat Abd-Elhamid, Hany; Badr, Marmar; Ludwig, Ralf

    2013-04-01

    Northeastern Delta is one of the most promising developmental areas in Egypt. This area is characterized by a prominent watershed having abundant water resources (especially groundwater). Currently, this area undergoes a rapid environmental degradation, such as land subsidence, water and soil salinaization. It accommodates about 60% of the total arable lands of the Delta, and inhabited by about 45 % of its total population. In addition, the northern part of this area comprises about 25% of the total Mediterranean wetlands. In this area a number of desalination plants were installed to desalinate brackish water and inject the brine to the aquifer using deep wells. This work aims to evaluate the environmental impact of injecting brine water on groundwater quality. Also, the impact of climate change and sea level rise are considered. The work is a combination of field work and simulation processes of groundwater flow and seawater intrusion using numerical models. The field work was used to collect and analyze data, information pertaining to the groundwater resources, interpretation of aerial photos and satellite images and preparation of ground water potential maps has. This was followed by detailed test boring wells as chemical analysis of seawater intrusion detection and pollution flow mapping were done. Numerical models (MODFLOW and MT3D) were used to evaluate both current and future situation of the groundwater flow and seawater intrusion in the Nile Delta aquifer in the studied area. The aquifer in the studied area is divided into five barrier beds according to its hydrological characteristics. The increase in extraction rates of brackish water and increasing the salinity of groundwater were experienced in details. Different scenarios to mitigate the severe salinity effect of injected brine water of high salinity rejected from desalination process. The brine water is assumed to be injected into deep wells to different depths and observation of changes in salinity

  15. Quantifying Knick Point Migration Rates Related to the Messinian Crisis. The Case of the Nile River

    NASA Astrophysics Data System (ADS)

    Stüwe, Kurt; Pucher, Christoph; Robl, Jörg; Hergarten, Stefan

    2016-04-01

    The Messinian crisis is a temporally well-constrained period between 5.3 my and 5.9 my, when the strait of Gibraltar was tectonically closed and the Mediterranean Sea had consequently desiccated. This dramatic base level drop by about 1500 vertical meters had a profound influence on the geomorphic evolution of the major drainages surrounding the Mediterranean basin. In particular, it caused substantial knickpoints in the major rivers including the Rhone, the Ebro, the Po and the Nile. While the knickpoints of the Rhone and Ebro have been studied previously and the knickpoints created by the Po may lie today underneath the Po plains, the knickpoint and its migration along the Nile has not been studied and would have migrated along its current river channel. In this contribution we focus on numerical modelling of the knickpoint migration in the Nile and use our modelling results in comparison with the present day morphological analyses of the river to constrain absolute migration rates. We suspect that the first Nile cataract near Assuan, some 1000 km upstream of today's river mouth may be the relict of the Messinian salinity crisis making it to one of the fastest migrating knickpoints in the world.

  16. Tradeoff Analysis Between Economic Development and Climate Change Adaptation Strategies for River Nile Basin Water Resources

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent Intergovernmental Panel on Climate Change (IPCC) briefings have declared that the growing population in the Nile river basin region (about 160 million, or 57% of the entire population of the basin’s ten riparian countries) is at risk of water scarcity. Adjustment strategies in response to cl...

  17. Rapid subsidence in the Nile delta and the effects of a mobile depositional surface on stratigraphic facies development

    SciTech Connect

    Stanley, D.J.

    1988-01-01

    Radiocarbon-dated late Quaternary sedimentary sections serve as a base to quantify high rates of subsidence in the northern Nile delta of Egypt. Measurements of recent vertical shifts of land relative to the sea, coupled with eustatic changes, are used to interpret temporal and spatial facies distribution patterns and delta lobe migration in the major recent depocenter in the eastern Mediterranean. The study is based largely on cores, collected during two drilling expeditions, which recovered material deposited during the past 30,000 years. These borings, plus an additional 50 core logs, allow good correlation for the region around Lake Manzala. There, variable thicknesses of Holocene marine and fluvio-marine units lie above transgressive coastal sands (upper Pleistocene to lower Holocene) and older alluvial delta-plain deposits. Mapping of these facies shows that the top of the transgressive sand becomes younger (to -- 7,000 years ago) and shallower toward the south of the present coastline. Progradation of delta lobes began about 8,000 years ago, and the coastline has advanced northward at a rate of approximately 1 km/100 years. Lake Manzala lies almost directly above, and is clearly related to, a 60-km long, narrow, linear northwest-southeast region of rapid subsidence; its axis trends parallel to, but is 10-15 km inland of, the present coastline. Holocene coastal and marine sediments lie at depths of 50 m, suggesting a lowering of land relative to the sea of about 40 cm per century. This linear zone, probably the surface expression of a growth fault, has been highly active during deposition. Similar neotectonic dislocation of sedimentary sections underlying the other lakes and lagoons in the northern delta is postulated. Facies patterns have been more extensively affected by rapid subsidence in the Nile delta than previously indicated.

  18. Is Solar Variability Reflected in the Nile River?

    NASA Technical Reports Server (NTRS)

    Ruzmaikin, Alexander; Feynman, Joan; Yung, Yuk L.

    2006-01-01

    We investigate the possibility that solar variability influences North African climate by using annual records of the water level of the Nile collected in 622-1470 A.D. The time series of these records are nonstationary, in that the amplitudes and frequencies of the quasi-periodic variations are time-dependent. We apply the Empirical Mode Decomposition technique especially designed to deal with such time series. We identify two characteristic timescales in the records that may be linked to solar variability: a period of about 88 years and one exceeding 200 years. We show that these timescales are present in the number of auroras reported per decade in the Northern Hemisphere at the same time. The 11-year cycle is seen in the Nile's high-water level variations, but it is damped in the low-water anomalies. We suggest a possible physical link between solar variability and the low-frequency variations of the Nile water level. This link involves the influence of solar variability on the atmospheric Northern Annual Mode and on its North Atlantic Ocean and Indian Ocean patterns that affect the rainfall over the sources of the Nile in eastern equatorial Africa.

  19. Geographic information systems and the distribution of Schistosoma mansoni in the Nile delta.

    PubMed

    Malone, J B; Abdel-Rahman, M S; El Bahy, M M; Huh, O K; Shafik, M; Bavia, M

    1997-03-01

    New computer-based sensor technology and geographic methods have led to emerging interest in use of satellite environmental assessment tools for design of disease control programs, especially for those that are vector borne. The long-range goal of work reported here by John Malone and colleagues on behalf of this Egyptian Ministry of Health-USAID Schistosomiasis Research Project team (Box 1) is to utilize data from sensor systems on board earth-observing satellites to develop more-sensitive disease-prediction and -control models. If successful, methods developed may provide a potentially vital capability for use by disease control program managers, particularly in less-developed countries, where mapping resources are not well advanced. Longer term, broader basic questions on the interaction of environment and disease in anticipation of predicted global climate change may be addressed. These studies focused on the lower Nile river basin of Egypt. The specific objective was to link data on environmental requirements for propagation and transmission of schistosomiasis with parameters measurable from space.

  20. The burden of trachoma in the rural Nile Delta of Egypt: a survey of Menofiya governorate

    PubMed Central

    al, A; Tawfik, N.; El Gendy, R.; Anwar, W.; Courtright, P.

    2001-01-01

    BACKGROUND—Evidence of widespread distribution of trachoma in Egypt had not been clarified as previous surveys were limited to individual communities which may not have been representative of the general population. The Nile Delta of Egypt presents a unique environment for trachoma to persist. Economic improvements in the past decade have affected even the poorest rural environments; availability of electricity is now found in many rural communities. Availability of water in Nile Delta has always been good but poor hygienic conditions have been the primary factor in trachoma transmission. A survey of trachoma was undertaken in Menofiya governorate to determine if Egypt should be identified as trachoma endemic and targeted for trachoma control efforts.
METHODS—A multistage random cluster study design was used with the target population defined as adults aged 50 and over and children aged 2-6 years from throughout the governorate. Among preschool children only trachoma was graded while among adults presenting visual acuity and cause of vision loss or blindness were also recorded. Adults were interviewed regarding past trichiasis surgery; those currently with trichiasis or a history of trichiasis surgery were also interviewed regarding outcome of surgery.
RESULTS—A total of 3272 children aged 2-6 and 3322 adults age 50+ were enumerated. Among the children 81.3% were examined and among the adults 73.0% were examined. Active trachoma (follicles (TF) and/or intense inflammation (TI)) was found among 36.5% (95% confidence interval (CI) 34.7-38.3%) of the children. TI was 1.89 (95% CI 1.22-2.94) times more common in rural children compared to urban children. The prevalence of trichiasis (TT) in adults was 6.5%; women had an age adjusted odds of trichiasis of 1.68 (95% CI 1.18-2.39) compared to men. Trichiasis was 2.11 times (95% CI 1.33-3.37) more common in rural Menofiya compared to urban Menofiya. TT accounts for blindness (presenting vision <3/60) in 8

  1. Human-induced changes in the geomorphology of the northeastern coast of the Nile delta, Egypt

    NASA Astrophysics Data System (ADS)

    El Banna, Mahmoud M.; Frihy, Omran E.

    2009-06-01

    Landsat Enhanced Thematic Mapper imagery (ETM) of 2002 and aerial photography of 1955, combined with published charts and field observations were used to interpret geomorphological changes in the coastal zone between Kitchener drain and Damietta spit in the northeastern Nile delta previously recognized as a vulnerable zone to the effects of any sea-level rise resulting from global warming. The interpretation resulted in recognition of several changes in nine identified geomorphological land types: beach and coastal flat, coastal dunes, agricultural deltaic land, sabkhas, fish farms, Manzala lagoon, saltpans, marshes and urban centers. Reclamation of vast areas of the coastal dunes and of Manzala lagoon added about 420 km 2 to the agricultural deltaic land. About 48 km 2 of sand dunes, marshes, sabkhas and salt pans have been converted to productive fish farms. The main urban centers have expanded, and new urban centers (Damietta harbor and the New Damietta city) have been constructed at the expense of vast areas of Manzala lagoon, coastal dunes, and backshore flats. As the consequence of human activities the size of Manzala lagoon has been reduced to less than 50%. Short-term shoreline changes along the coast of the study area established from beach profile survey, spanning the years of 1990 to 2000, reveal longshore patterns of erosion versus accretion. The rate of shoreline retreat has increased in the downdrift side of Damietta harbor (- 14 m/year), whereas areas of accretion exist within the embayment of Gamasa and in the shadow of Ras El Bar detached breakwater system, with a maximum shoreline advance of ~ 15 m/year. A sandy spit, 12 km long, has developed southeast of Damietta promontory. These erosion/accretion patterns denote the natural processes of wave-induced longshore currents and sediment transport, in addition, the impact of man-made coastal protection structures.

  2. 23. OWENS RIVER DELTA JUST NORTH OF CROWLEY LAKE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. OWENS RIVER DELTA JUST NORTH OF CROWLEY LAKE - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

  3. Ecosystem Services Assessment of the Nemunas River Delta

    EPA Science Inventory

    The concept of ecosystem services recognizes the services, and benefits, provided to people by ecosystems. The Nemunas River Delta, in Lithuania, provides many ecosystem services to the people of the area, including food, fuel, transportation, climate regulation, water purificati...

  4. Altamaha River Delta, Georgia Sea Islands

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The history of sea islands in the Altamaha River delta on the coast of Georgia is revealed in this image produced from data acquired by the Airborne Synthetic Aperture Radar (AIRSAR), developed and operated by NASA's Jet Propulsion Laboratory, Pasadena, Calif. The outlines of long-lost plantation rice fields, canals, dikes and other inlets are clearly defined. Salt marshes are shown in red, while dense cypress and live oak tree canopies are seen in yellow-greens.

    Agricultural development of the Altamaha delta began soon after the founding of the Georgia Colony in 1733. About 25 plantations were located on the low-lying islands and shores by the 19th century, taking advantage of the rich alluvial flow and annual inundation of water required by some crops. The first major crop was indigo; when demand for that faded, rice and cotton took its place. A major storm in 1824 destroyed much of the town of Darien (upper right) and put many of the islands under 20 feet of water. The Civil War ended the plantation system, and many of the island plantations disappeared under heavy brush and new growth pine forests. Some were used as tree farms for paper and pulp industries, while the Butler Island (center left) plantation became a wildlife conservation site growing wild sea rice for migrating ducks and other waterfowl. Margaret Mitchell is reputed to have used the former owner of the Butler Plantation as a basis for the Rhett Butler character in her novel 'Gone With The Wind,' taking the first name from Rhett's Island (lower right).

    These data were obtained during a 1994-95 campaign along the Georgia coast. AIRSAR's ability to detect vegetation canopy density, hydrological features and other topographic characteristics is a useful tool in landscape archaeology. AIRSAR flies aboard a NASA DC-8 based at NASA's Dryden Flight Research Center, Edwards, Calif. The analysis on the data shown was accomplished by Dr. Gary Mckay, Department of Archaeology and Geography, and Ian

  5. Hydraulic conductivity estimation using direct current (DC) sounding data: a case study in East Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Attwa, M.; Basokur, A. T.; Akca, I.

    2014-08-01

    Automated vertical electrical sounding (VES) inversion schemes were applied for hydrogeological characterisation at a semi-arid area in the southeastern part of the East Nile Delta, Egypt. The apparent resistivity measurements were integrated with borehole, hydrogeological and structural information for a better description of the subsurface conditions. The final results were presented in the form of cross-sections, maps and 3D diagrams to visualise the geological and hydrogeological situations. The resistivity values derived from the VES data were used to predict the hydraulic conductivity ( K) values by using two empirical relations, which depend on the direct relation between K and the aquifer transverse resistance ( T) and the power relation between K and the aquifer resistivity ( ρ). The estimated values were compared with the observed K values obtained from the pumping tests. The power law relation produces more reliable predicted K values that show a good correlation with the data compiled for the hydraulic gradient of the main Pleistocene aquifer in the East Nile Delta. The results also indicate that the joint use of an automated 1D interpretation algorithm and the power law empirical relationship constitute a valuable tool to characterise the hydrogeophysical properties of aquifers in the study area.

  6. Soil Degradation Assessment in North Nile Delta Using Remote Sensing and GIS Techniques

    NASA Astrophysics Data System (ADS)

    El Nahry, A. H.; Ibraheim, M. M.; El Baroudy, A. A.

    2015-04-01

    The present work aims at monitoring soil degradation process within the last two decades in the northern part of Nile Delta. The investigated area lies between longitudes 31° 00- & 31° 15- E and latitudes 31° 00' & 31° 37' N., covering an area of about 161760 feddans. Detecting soil degradation and recognizing its various types is a necessity to take the practical measures for combating it as well as conserving and keeping the agricultural soil healthy. Land degradation was assessed by adopting new approach through the integration of GLASOD/FAO approach and Remote Sensing / GIS techniques .The main types of human induced soil degradation that observed in the studied area are salinity, alkalinity (sodicity), compaction and water logging .On the other hand water erosion because of sea rise is assessed. The obtained data showed that, areas that were affected by compaction increment have been spatially enlarged by 40.9 % and those affected by compaction decrease have been spatially reduced by 22.6 % of the total area ,meanwhile areas that have been unchanged were estimated by 36.5% of the total area. The areas that were affected by water logging increase have been spatially enlarged by 52.2 % and those affected by water logging decrease have been spatially reduced by 10.1 % of the total area, meanwhile the areas which have been unchanged were represented by 37.7 % of the total area. Areas that were affected by salinity increase have been spatially enlarged by 31.4 % of the total area and those affected by salinity decrease have been reduced by 43.3 % of the total area. An area represented by 25.2 % of the total area has been unchanged. Alkalinization (sodicity) was expressed by the exchangeable sodium percentage (ESP).Areas that were affected by sodicity increase have been spatially enlarged by 33.7 %, meanwhile those affected by sodicity decrease have been spatially reduced by 33.6 % of the total area. An area represented by 32.6 % of the total area has been

  7. Natural and anthropogenic influences in the northeastern coast of the Nile delta, Egypt

    NASA Astrophysics Data System (ADS)

    El Banna, Mahmoud M.; Frihy, Omran E.

    2009-06-01

    Landsat enhanced thematic mapper imagery (ETM) of 2002 and aerial photography of 1955, combined with published charts and field observations were used to interpret coastal changes in the zone between Kitchener drain and Damietta spit in the northeastern Nile delta, previously recognized as a vulnerable zone to the effects of any sea level rise resulting from global warming. The interpretation resulted in recognition of several changes in nine identified geomorphological land types: beach and coastal flat, coastal dunes, agricultural deltaic land, sabkhas, fish farms, Manzala lagoon, saltpans, marshes and urban centers. Reclamation of vast areas of the coastal dunes and of Manzala lagoon added about 420 km² to the agricultural deltaic land. About 48 km² of backshore flats, marshes, salt pans and Manzala lagoon have been converted to productive fish farms. The main urban centers have expanded; nearly 12.1 km2 have been added to their areas, and new urban centers (Damietta harbor and the New Damietta city) with total area reach of ~35.3 km2 have been constructed at the expense of vast areas of Manzala lagoon, coastal dunes, and backshore flats. As a consequence of human activities, the size of Manzala lagoon has been reduced to more than 65%. Shoreline changes have been determined from beach profile survey (1990-2000), and comparison of 1955 aerial photographs and ETM satellite image of 2002 reveal alongshore patterns of erosion versus accretion. The short-term rate of shoreline retreat (1990-2000) has increased in the downdrift side of Damietta harbor (≃14 m/year), whereas areas of accretion exist within the embayment of Gamasa and in the shadow of Ras El Bar detached breakwaters system, with a maximum shoreline advance of ~15 m/year. A sandy spit, 12 km long, has developed southeast of Damietta promontory. These erosion/accretion patterns denote the natural processes of wave-induced longshore currents and sediment transport, in addition, the impact of man

  8. Incentive compatibility and conflict resolution in international river basins: A case study of the Nile Basin

    NASA Astrophysics Data System (ADS)

    Wu, Xun; Whittington, Dale

    2006-02-01

    Nation-states rarely go to war over water, but it is equally rare that water conflicts in an international river basin are resolved through cooperation among the riparian countries that use the shared resources. Gains from cooperation will mean little to individual riparians unless the required cooperative behaviors are incentive compatible. Cooperative game theory offers useful insights for assessing cooperative solutions for water conflicts in international river basins. Applying cooperative game theory concepts such as core, nucleolus, and Shapley value to Nile water conflicts, we examine the incentive structure of both cooperative and noncooperative strategies for different riparian countries and establish some baseline conditions for incentive-compatible cooperation in the Nile basin.

  9. Rapid subsidence in the Nile delta and the effects of a mobile depositional surface on stratigraphic facies development

    SciTech Connect

    Stanley, D.J.

    1988-02-01

    Radiocarbon-data late Quaternary sedimentary sections serve as a base to quantify high rates of subsidence in the northern Nile delta of Egypt. Measurements of recent vertical shifts of land relative to the sea, coupled with eustatic changes, are used to interpret temporal and spatial facies distribution patterns and delta lobe migration in the major recent depocenter in the eastern Mediterranean. The study is based largely on cores, collected during two drilling expeditions, which recovered material deposited during the past 30,000 years. These borings, plus an additional 50 core logs, allow good correlation for the region around Lake Manzala. There, variable thicknesses of Holocene marine and fluvio-marine units lie above transgressive coastal sands (upper Pleistocene to lower Holocene) and older alluvial delta-plain deposits. Mapping of these facies shows that the top of the transgressive sand becomes younger (to /approximately/ 7000 years ago) and shallower toward the south of the present coastline. Progradation of delta lobes began about 8000 years ago, and the coastline has advanced northward at a rate of approximately 1 km/100 years.

  10. Age and origin of the Gezira alluvial fan between the Blue and White Nile rivers

    NASA Astrophysics Data System (ADS)

    Williams, martin

    2014-05-01

    The Gezira is a low-angle alluvial fan bounded by the Blue Nile to the east and the White Nile to the west. It is the main agricultural region of Sudan and produces high quality long-staple cotton for export. Dark cracking clays (vertisols) cover much of the Gezira and range in age from 50 kyr to Holocene. The Gezira is traversed by a series of defunct sandy channels that originate between Sennar and Wad Medani on the present-day Blue Nile. With a radius of 300 km and an area of 40,000 km2 the Gezira is a mega-fan. The younger channels range in age from early Holocene to 100 kyr, while near surface channels filled with rolled quartz and carbonate gravels have ages back to >250 kyr. Boreholes in the Gezira reveal coarse alluvial sands and gravels in now buried channels overlain by alluvial clays, forming a repetitive sequence of fining-upwards alluvial units. that probably extend back to Pliocene times. The fan is up to 180 m thick with a volume of ~1,800 km3. The sandy or gravelly bed-load channels coincide with colder drier climates and sparse vegetation in the Ethiopian headwaters of the Blue Nile and the alluvial clays denote widespread flooding during times of stronger summer monsoon. The early stages of such flood events were often accompanied by mass burial of Nile oyster (Etheria elliptica) beds, such as the 45-50 kyr floods that deposited up to 5 m of clay in the northern Gezira. A unique feature of the eastern Gezira is a former Blue Nile channel at least 80 km long running parallel to the present river and entirely filled with volcanic ash. The channel was only 3-4 m deep and 20-30 m wide. Very fine laminations and cross-beds, together with locally abundant phytoliths and sponge spicules, suggest slow-moving water, with flow dispersed across many distributary channels. The ash geochemistry is similar to that in the lower part of the Kibish Formation in the lower Omo valley of southern Ethiopia and points to a minimum age of 100 kyr and a maximum age of

  11. Petrology of Nile River sands (Ethiopia and Sudan): Sediment budgets and erosion patterns

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo; Andò, Sergio; Vezzoli, Giovanni; Ali Abdel Megid, Ada; El Kammar, Ahmed

    2006-12-01

    Detrital modes of modern Nile sands, together with estimates of sediment volumes trapped in Sudanese reservoirs, allow us to calculate sediment loads of major tributaries (Blue Nile, White Nile, Atbara) and erosion rates in the Nile catchment. A tridimensional array of high-resolution bulk-petrography and heavy-mineral data was obtained on both levee (suspended load) and bar (bedload) deposits, analysed separately for each grain-size subclass at 0.5 Φ intervals. From available information on sediments stored in the Roseires, Khashm el Girba and Lake Nasser reservoirs between 1964 and 1990, the total Nile load is reassessed at 230 ± 20 10 6 t/a, an estimate two to four times higher than figures reported so far, on which previous estimates of sediment yields and erosion rates were based. Of such huge amount of detritus, 82 ± 10 10 6 t/a are contributed by River Atbara, which carries more volcanic rock fragments, brown augite and olivine from basaltic rocks, and 140 ± 20 10 6 t/a by the Blue Nile, which carries more K-feldspar and hornblende from amphibolite-facies basement rocks. The additional ≤ 10 7 t/a of almost purely quartzose sediments supplied by the rest of the Nile catchment, corresponding to insignificant average yields and erosion rates, represent the stable residue which survived extreme subequatorial weathering in southern Sudan swamps (White Nile, Bahr ez Zeraf, and Sobat sands) or fluvial and eolian recycling of ancient quartzarenites in hyperarid climates (Nubian sands). Sediment production is thus markedly focused on Ethiopian rift highlands, where rainfall is concentrated in a single July-August peak. High average yields and erosion rates (800 ± 150 t/km 2 a, 0.29 ± 0.05 mm/a) partly reflect anthropically-accelerated erosion caused by deforestation and intensive land use, and cannot be extrapolated far in the past. Erosion patterns may have changed repeatedly during Quaternary climatic oscillations, and possibly also in the longer term

  12. Using ENSO Indices to Enhance Long-Range Ensemble Streamflow Forecasts in The Blue Nile River

    NASA Astrophysics Data System (ADS)

    Habib, M. A.; Bradley, A.

    2012-12-01

    River forecasting centers around the globe have been using hydrologic ensemble forecast systems operationally. Better-enhanced forecasting systems are the ultimate need of the decision maker. This study proposes an enhancement technique for Long-Range Ensemble Streamflow Forecasts in The Blue Nile River. Many studies showed the link between summer rainfall and the large scale climate oscillations. Strong correlation is found between the El-Nino Southern Oscillations (ENSO) and annual flows in the Nile River at Diem on the Sudanese-Ethiopian boarders. Long-range streamflow forecasts produced by The Nile Forecast System at Ministry of Public Works and Irrigation in Egypt are used. Traditionally, baseline forecast weights each trace of the ensemble equally. In this study, we add an enhancement process to the forecasts by changing their weights depending on the correlation between the Streamflow and the ENSO indices (e.g. SST3.4, SOI). Weighting techniques using different distributions of the ENSO indices (e.g. Kernel, Gaussian) are examined. Diagnostic verification measures are used to evaluate this enhancement process.

  13. Assessing and managing water scarcity within the Nile River Transboundary Basin

    NASA Astrophysics Data System (ADS)

    Butts, M. B.; Wendi, D.; Jessen, O. Z.; Riegels, N. D.

    2012-04-01

    The Nile Basin is the main source of water in the North Eastern Region of Africa and is perhaps one of the most critical river basins in Africa as the riparian countries constitute 40% of the population on the continent but only 10% of the area. This resource is under considerable stress with rising levels of water scarcity, high population growth, watershed degradation, and loss of environmental services. The potential impacts of climate change may significantly exacerbate this situation as the water resources in the Nile Basin are critically sensitive to climate change (Conway, Hanson, Doherty, & Persechino, 2007). The motivation for this study is an assessment of climate change impacts and adaptation potential for floods and droughts within the UNEP project "Adapting to climate change induced water stress in the Nile River Basin", supported by SIDA. This project is being carried out as collaboration between DHI, the UK Met Office, and the Nile Basin Initiative (NBI). The Nile Basin exhibits highly diverse climatological and hydrological characteristics. Thus climate change impacts and adaptive capacity must be addressed at both regional and sub-basin scales. While the main focus of the project is the regional scale, sub-basin scale modelling is required to reflect variability within the basin. One of the major challenges in addressing this variability is the scarcity of data. This paper presents an initial screening modelling study of the water balance of the Nile Basin along with estimates of expected future impacts of climate change on the water balance. This initial study is focussed on the Ethiopian Highlands and the Lake Victoria regions, where the impact of climate change on rainfall is important. A robust sub-basin based monthly water balance model is developed and applied to selected sub-basins. The models were developed and calibrated using publicly available data. One of the major challenges in addressing this variability within the basin is the

  14. Use of the subsurface thermal regime as a groundwater-flow tracer in the semi-arid western Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Salem, Zenhom E.; Bayumy, Dina A.

    2016-06-01

    Temperature profiles from 25 boreholes were used to understand the spatial and vertical groundwater flow systems in the Western Nile Delta region of Egypt, as a case study of a semi-arid region. The study area is located between the Nile River and Wadi El Natrun. The recharge areas, which are located in the northeastern and the northwestern parts of the study area, have low subsurface temperatures. The discharge areas, which are located in the western (Wadi El Natrun) and southern (Moghra aquifer) parts of the study area, have higher subsurface temperatures. In the deeper zones, the effects of faults and the recharge area in the northeastern direction disappear at 80 m below sea level. For that depth, one main recharge and one main discharge area are recognized. The recharge area is located to the north in the Quaternary aquifer, and the discharge area is located to the south in the Miocene aquifer. Two-dimensional groundwater-flow and heat-transport models reveal that the sealing faults are the major factor disturbing the regional subsurface thermal regime in the study area. Besides the main recharge and discharge areas, the low permeability of the faults creates local discharge areas in its up-throw side and local recharge areas in its down-throw side. The estimated average linear groundwater velocity in the recharge area is 0.9 mm/day to the eastern direction and 14 mm/day to the northwest. The average linear groundwater discharge velocities range from 0.4 to 0.9 mm/day in the southern part.

  15. Impact of rehabilitation of Assiut barrage, Nile River, on groundwater rise in urban areas

    NASA Astrophysics Data System (ADS)

    Dawoud, Mohamed A.; El Arabi, Nahed E.; Khater, Ahmed R.; van Wonderen, Jan

    2006-08-01

    To make optimum use of the most vital natural resource of Egypt, the River Nile water, a number of regulating structures (in the form of dams and barrages) for control and diversion of the river flow have been constructed in this river since the start of the 20th century. One of these barrages is the Assiut barrage which will require considerable repairs in the near future. The design of the rehabilitation of the barrage includes a headpond with water levels maintained at a level approximately 0.60 m higher than the highest water level in the headpond of the present barrage. This development will cause an increase of the seepage flow from the river towards the adjacent agricultural lands, Assiut Town and villages. The increased head pond level might cause a rise of the groundwater levels and impedance of drainage outflows. The drainage conditions may therefore be adversely affected in the so-called impacted areas which comprise floodplains on both sides of the Nile for about 70 km upstream of the future barrage. A rise in the groundwater table, particularly when high river levels impede drainage, may result in waterlogging and secondary salinization of the soil profile in agricultural areas and increase of groundwater into cellars beneath buildings in the urban areas. In addition, a rise in the groundwater table could have negative impact on existing sanitation facilities, in particular in the areas which are served with septic tanks. The impacts of increasing the headpond level were assessed using a three-dimensional groundwater model. The mechanisms of interactions between the Nile River and the underlying Quaternary aquifer system as they affect the recharge/discharge processes are comprehensively outlined. The model has been calibrated for steady state and transient conditions against historical data from observation wells. The mitigation measures for the groundwater rise in the urban areas have been tested using the calibrated mode.

  16. Morphology of river deltas on Titan and Earth

    NASA Astrophysics Data System (ADS)

    Witek, Piotr; Czechowski, Leszek

    2016-07-01

    The Cassini-Huygens mission is entering its final phase. The landing of Huygens on Titan and flybys performed by the Cassini probe during the last ten years revolutionized our knowledge about that moon, revealing a complex fluvio-lacustrine environment. Despite significant differences in composition, temperature and gravity, the processes of sediment transport and deposition are similar on Earth and Titan. We performed numerical simulations of development of river deltas in Titanian and terrestrial conditions, under various discharges and with different dominant grain sizes. We found that evolution of deltaic deposits is more rapid on Titan due to higher efficiency of transport, but the flat, lobate river deltas may form in narrower range of parameters than on Earth. Our results help in understanding the evolution of sedimentary deposits and may partially explain the paucity of river deltas in Titan's lakes.

  17. Sequence Stratigraphic Analysis for Delineating the Sedimentation Characteristic and Modeling of Nidoco Area, Off-Shore Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El Deen, Ahmed; Abu El-Ata, Ahmed; El-Gendy, Nader

    2014-05-01

    The Egyptian Nile Delta has recognized over the different human civilizations, as the source of life/ basket of wheat. In the recent time, the Nile Delta revealed another hidden treasure that hidden below the Mediterranean Sea within its sediments. This treasure reflects a number of giant gas reservoirs that require only the suitable technology and the assured ideas to commence injecting gas into the industrial veins of the growing Egyptian economy. The current study is aiming to discuss the Messinian Prospectivity of the concerned area, which is located in the offshore of the Nile Delta, about 25 Km from the Mediterranean Sea shoreline. An integrated exploration approach applied for a selected area, using a variety of subsurface borehole geologic and log data of the selected wells distributed in the study area, as well as biostratigraphic data. The well data comprise well markers, and electric logs (e.g. gamma ray, density, neutron and sonic logs), where the geological data represented by litho-stratigraphic information, as well as ditch samples analysis of the studied interval. Biostratigraphic data include biozones, benthonic to planktonic ratios, nannofossils and foraminiferal data. Different methods and techniques were applied by using different softwares such as Petrel and Interactive petrophysical software. Four missing times were identified intra-Pleistocene, Late Pliocene, Late Pliocene-Early Pliocene and Messinian. It has concluded that, the depositional environments ranged from shallow marine to middle nerritic and may reach upper bathyal toward the northern part of the study area. The top of Abu Madi Formation dated with the calcareous nannofossils zone NN12a, while the base dated with NN11c, and its age varied from 5.2 Ma to 5.7 Ma. The maximum flooding surface is dated with the calcareous nannofossils zone NN13 and the planktonic foraminiferal zone SN18 at 5 Ma (the acme presence of the Sphaeroidinellopsis sp.). From the utility of wireline logs for

  18. The Role of Sequence Stratigraphic Analysis in the Messinian crisis at Baltim Area, Off-Shore Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El-Deen Badawy, A. M.; Abu El-Ata, A. S.; El-Gendy, N. H.

    2013-12-01

    The Egyptian Nile Delta has recognized over the different human civilizations, as the source of life/ basket of wheat. In the recent time, the Nile Delta revealed another hidden treasure that hidden below the Mediterranean Sea within its sediments. This treasure reflects a number of giant gas reservoirs that require only the suitable technology and the assured ideas to commence injecting gas into the industrial veins of the growing Egyptian economy. The current study is aiming to discuss the Messinian Prospectivity of the concerned area, which is located in the offshore of the Nile Delta, about 25 Km from the Mediterranean Sea shoreline. An integrated exploration approach applied for a selected area, using a variety of subsurface borehole geologic and log data of the selected wells distributed in the study area, as well as biostratigraphic data. The well data comprise well markers, and electric logs (e.g. gamma ray, density, neutron and sonic logs), where the geological data represented by litho-stratigraphic information, as well as ditch samples analysis of the studied interval. Biostratigraphic data include biozones, benthonic to planktonic ratios, nannofossils and foraminiferal data. Different methods and techniques were applied by using different softwares such as Petrel and Interactive petrophysical software. Four missing times were identified intra-Pleistocene, Late Pliocene, Late Pliocene-Early Pliocene and Messinian. It has concluded that, the depositional environments ranged from shallow marine to middle nerritic and may reach upper bathyal toward the northern part of the study area. The top of Abu Madi Formation dated with the calcareous nannofossils zone NN12a, while the base dated with NN11c, and its age varied from 5.2 Ma to 5.7 Ma. The maximum flooding surface is dated with the calcareous nannofossils zone NN13 and the planktonic foraminiferal zone SN18 at 5 Ma (the acme presence of the Sphaeroidinellopsis sp.). From the utility of wireline logs for

  19. Quantitative metrics that describe river deltas and their channel networks

    NASA Astrophysics Data System (ADS)

    Edmonds, Douglas A.; Paola, Chris; Hoyal, David C. J. D.; Sheets, Ben A.

    2011-12-01

    Densely populated river deltas are losing land at an alarming rate and to successfully restore these environments we must understand the details of their morphology. Toward this end we present a set of five metrics that describe delta morphology: (1) the fractal dimension, (2) the distribution of island sizes, (3) the nearest-edge distance, (4) a synthetic distribution of sediment fluxes at the shoreline, and (5) the nourishment area. The nearest-edge distance is the shortest distance to channelized or unchannelized water from a given location on the delta and is analogous to the inverse of drainage density in tributary networks. The nourishment area is the downstream delta area supplied by the sediment coming through a given channel cross section and is analogous to catchment area in tributary networks. As a first step, we apply these metrics to four relatively simple, fluvially dominated delta networks. For all these deltas, the average nearest-edge distances are remarkably constant moving down delta suggesting that the network organizes itself to maintain a consistent distance to the nearest channel. Nourishment area distributions can be predicted from a river mouth bar model of delta growth, and also scale with the width of the channel and with the length of the longest channel, analogous to Hack's law for drainage basins. The four delta channel networks are fractal, but power laws and scale invariance appear to be less pervasive than in tributary networks. Thus, deltas may occupy an advantageous middle ground between complete similarity and complete dissimilarity, where morphologic differences indicate different behavior.

  20. Hydro-economic Risk Assessment in the Eastern Nile River Basin

    NASA Astrophysics Data System (ADS)

    Arjoon, D.; Tilmant, A.; Mohamed, Y.

    2013-12-01

    In 2011, the Ethiopian government announced plans for the construction of the Grand Renaissance Dam (GRD) on the Blue Nile, just east of its border with Sudan, at a cost of almost 5 billion dollars. The project is expected to generate over 15 TWh of energy and will include a reservoir of more than 60 km3 capacity, which roughly corresponds to the average annual flow of the Blue Nile. This project is part of a larger scheme, by the government, to expand its hydroelectric power capacity, however, the scheme faces strong opposition from downstream Egypt and Sudan. Egypt and Sudan are highly dependent on flows that originate in Ethiopia (it has been estimated that 86% of Nile flow originates in the Ethiopian highlands). The Ethiopian government argues that the dam would supply electricity for Ethiopians as well as generate surplus energy for export to neighboring countries. The Ethiopians also argue that the huge reservoir would generate positive externalities downstream by reducing floods and providing more constant and predictable lows. This study attempts to provide an independent analysis of the hydrologic and economic risks faced by downstream countries when GRD will be online. To achieve this, an integrated, stochastic hydro-economic model of the entire Eastern Nile basin is used to analyze various development and management scenarios. The results indicate that if countries agree to co- operative management of the Eastern Nile River basin, GRD would indeed significantly increase basin-wide benefits, especially in Ethiopia and in Sudan. An alternative management scenario, whereby GRD would be operated by Sudan and Egypt, does not yield significant economic gains in these countries. However, massive unilateral irrigation developments in Ethiopia will be detrimental for all countries, including Ethiopia itself, due to the huge opportunity costs involved.

  1. Revisiting the Tectono-Stratigraphic Evolution of the Eastern Mediterranean Offshore Levant and Nile Delta

    NASA Astrophysics Data System (ADS)

    Al-Balushi, Abdulaziz; Fraser, Alastair; A-L Jackson, Christopher; Bell, Rebecca; Kusznir, Nick

    2015-04-01

    Although the Eastern Mediterranean has become the focus for increased oil and gas exploration following significant discoveries in the pre-Messinian succession offshore Egypt and the Levant Margin, understanding its tectono-stratigraphic evolution is the first and most important step towards building reliable geological models that underpin petroleum play assessment. The Eastern Mediterranean Basin has evolved through a complex and poorly understood tectonic history. Disagreement within the scientific community relates to the age of rifting, the orientation of the crustal stretching direction and the type of crust underlying the Levant Basin and, by proxy, the magnitude of stretching. We present, for the first time, an interpretation of deep (i.e. 12-20 sec TWT) regional 2D seismic lines covering the entire Levant Basin. We have interpreted nine seismic surfaces (from top basement to seabed) from which depth and isopach maps for key surfaces and intervals have been generated. To constrain the rifting age, we have used a reverse subsidence modelling technique and restored the Middle Jurassic and the Late Cretaceous basin geometry along a NW-trending seismic profile from the Levant Basin. The restorations, for a specific rifting age, that meet geological constraints on water depth that are obtained from well data and seismic stratigraphy, are considered as viable solutions. The type of crust that underlies the Levant Margin has been inferred from the magnitude of the lithospheric stretching derived from gravity inversion and crustal thinning. Our interpretation of top basement and the Middle Jurassic depth-structure maps suggests that rifting in the Levant Basin led to the development of two main depocentres; in the northern Levant and the southern Levant, in the vicinity of the Nile Delta. These depocentres are separated by a series of NE-trending, fault- bound structural highs (i.e. Jonah and Leviathan). The orientation of the faults suggests they formed in

  2. Underground and Previously Undiscovered Rivers in the Mississippi Delta

    NASA Astrophysics Data System (ADS)

    Kolker, A.; Breaux, A.; Coleman, D.; Inniss, L. V.; Telfeyan, K.; Kim, J.; Schneider, A.; Allison, M. A.; Cable, J. E.; Johannesson, K. H.

    2013-12-01

    In this study we show that there are large, and previously undiscovered, groundwater pathways by which water from the Mississippi River is transported to the wetlands and estuaries of the Mississippi River Delta. Results from multiple methodologies suggest that the total flux of groundwater to the coastal zone in the Mississippi River Delta averages 1,000 m3 s-1, and can reach 5,000 m3 s-1 at high flow. We suggest that flow preferentially occurs through paleo-crevasse channels, relict bayous, and other buried deposits of permeable and coarse grained material. These conduits were formed during the present and previous stages of the delta cycle, which occurred in historical (102 y) and late Holocene(103 y) times, respectively. Flow is driven by the hydrological head difference between the river and the estuary, which is seasonally variable in magnitudeand can reach 5-8 m during peak river floods. This talk will present data from hydrological budgets that show a missing fraction in the Mississippi River water budget, and a missing source of fresh water to a large estuary. We will show that water levels in wells in New Orleans fluctuate with the stage of the Mississippi River. Data of Rn concentration indicate advective submarine groundwater flow, whereas Ba concentrations suggest geochemical leachates are entering the estuary. Furthermore, seismic data indicate the prevalence of paleochannels and other buried features that could carry flow. Given the importance of deltas to global geochemical budgets, we suggest that these results may be generalizable: submarine groundwater discharge in deltas may prove to be an important but understudied pathway by which dissolved materials are transported from the continents to the ocean.

  3. Sandy River Delta Habitat Restoration Project, Annual Report 2001.

    SciTech Connect

    Kelly, Virginia; Dobson, Robin L.

    2002-11-01

    The Sandy River Delta is located at the confluence of the Sandy and Columbia Rivers, just east of Troutdale, Oregon. It comprises about 1,400 land acres north of Interstate 84, managed by the USDA Forest Service, and associated river banks managed by the Oregon Division of State Lands. Three islands, Gary, Flag and Catham, managed by Metro Greenspaces and the State of Oregon lie to the east, the Columbia River lies to the north and east, and the urbanized Portland metropolitan area lies to the west across the Sandy River. Sandy River Delta was historically a wooded, riparian wetland with components of ponds, sloughs, bottomland woodland, oak woodland, prairie, and low and high elevation floodplain. It has been greatly altered by past agricultural practices and the Columbia River hydropower system. Restoration of historic landscape components is a primary goal for this land. The Forest Service is currently focusing on restoration of riparian forest and wetlands. Restoration of open upland areas (meadow/prairie) would follow substantial completion of the riparian and wetland restoration. The Sandy River Delta is a former pasture infested with reed canary grass, blackberry and thistle. The limited over story is native riparian species such as cottonwood and ash. The shrub and herbaceous layers are almost entirely non-native, invasive species. Native species have a difficult time naturally regenerating in the thick, competing reed canary grass, Himalayan blackberry and thistle. A system of drainage ditches installed by past owners drains water from historic wetlands. The original channel of the Sandy River was diked in the 1930's, and the river diverted into the ''Little Sandy River''. The original Sandy River channel has subsequently filled in and largely become a slough. The FS acquired approximately 1,400 acres Sandy River Delta (SRD) in 1991 from Reynolds Aluminum (via the Trust for Public Lands). The Delta had been grazed for many years but shortly after FS

  4. A reduced-complexity model for river delta formation - Part 1: Modeling deltas with channel dynamics

    NASA Astrophysics Data System (ADS)

    Liang, M.; Voller, V. R.; Paola, C.

    2014-07-01

    We develop a reduced-complexity model (RCM) delta formation model, in contrast to reductionist models based on high-resolution computational fluid dynamics. The basic framework of this model (referred in this paper as "DeltaRCM") consists of stochastic parcel-based cellular routing schemes for water and sediment and a set of phenomenological rules for sediment deposition and erosion. The outputs of the model include flow field, water surface topography and bed topography that evolves in time. Results show that DeltaRCM is able to: (1) resolve a wide range of channel dynamics, including elongation, bifurcation, avulsion and migration; (2) in response to the changes in input parameters, produce different types of deltas such as alluvial fan deltas at experimental scale. We also identify three key areas of particular model sensitivity, even at the RCM level: (1) avulsion dynamics is sensitive to dynamic free-surface topography; (2) channel network structure is sensitive to instability at channel mouths which creates bars; and (3) out-of-channel sedimentation is sensitive to water surface slope along channel margins. We also demonstrate a simple stratigraphy tracking component which can display the structure of the deposit in terms of distribution of coarse and fine materials along with the age of the deposit. DeltaRCM is a useful tool for understanding the dynamics of river deltas within a relatively simple cellular representation of water and sediment transport.

  5. Seismic stability of the Duwamish River Delta, Seattle, Washington

    USGS Publications Warehouse

    Kayen, Robert E.; Barnhardt, Walter A.

    2007-01-01

    The delta front of the Duwamish River valley near Elliott Bay and Harbor Island is founded on young Holocene deposits shaped by sea-level rise, episodic volcanism, and seismicity. These river-mouth deposits are highly susceptible to seismic soil liquefaction and are potentially prone to submarine landsliding and disintegrative flow failure. A highly developed commercial-industrial corridor, extending from the City of Kent to the Elliott Bay/Harbor Island marine terminal facilities, is founded on the young Holocene deposits of the Duwamish River valley. The deposits of this Holocene delta have been shaped not only by relative sea-level rise but also by episodic volcanism and seismicity. Ground-penetrating radar (GPR), cores, in situ testing, and outcrops are being used to examine the delta stratigraphy and to infer how these deposits will respond to future volcanic eruptions and earthquakes in the region. A geotechnical investigation of these river-mouth deposits indicates high initial liquefaction susceptibility during earthquakes, and possibly the potential for unlimited-strain disintegrative flow failure of the delta front.

  6. Ecosystem Services Assessment of the Nemunas River Delta

    EPA Science Inventory

    The concept of ecosystem services recognizes the services, and benefits, provided to people by ecosystems. The Nemunas River Delta, in Lithuania, is a valued area that can provide a range of services. We conducted a meta-analysis of existing studies done on the region to identify...

  7. Schistosomiasis among Recreational Users of Upper Nile River, Uganda, 2007

    PubMed Central

    Brunette, Gary; Kapella, Bryan K.; McAuliffe, Isabel; Katongole-Mbidde, Edward; Li, Wenkai; Marano, Nina; Okware, Sam; Olsen, Sonja J.; Secor, W. Evan; Tappero, Jordan W.; Wilkins, Patricia P.; Montgomery, Susan P.

    2010-01-01

    After recreational exposure to river water in Uganda, 12 (17%) of 69 persons had evidence of schistosome infection. Eighteen percent self-medicated with praziquantel prophylaxis immediately after exposure, which was not appropriate. Travelers to schistosomiasis-endemic areas should consult a travel medicine physician. PMID:20409387

  8. Pen Branch Delta and Savannah River Swamp Hydraulic Model

    SciTech Connect

    Chen, K.F.

    1999-05-13

    The proposed Savannah River Site (SRS) Wetlands Restoration Project area is located in Barnwell County, South Carolina on the southwestern boundary of the SRS Reservation. The swamp covers about 40.5 km2 and is bounded to the west and south by the Savannah River and to the north and east by low bluffs at the edge of the Savannah River floodplain. Water levels within the swamp are determined by stage along the Savannah River, local drainage, groundwater seepage, and inflows from four tributaries, Beaver Dam Creek, Fourmile Branch, Pen Branch, and Steel Creek. Historic discharges of heated process water into these tributaries scoured the streambed, created deltas in the adjacent wetland, and killed native vegetation in the vicinity of the delta deposits. Future releases from these tributaries will be substantially smaller and closer to ambient temperatures. One component of the proposed restoration project will be to reestablish indigenous wetland vegetation on the Pen Branch delta that covers about 1.0 km2. Long-term predictions of water levels within the swamp are required to determine the characteristics of suitable plants. The objective of the study was to predict water levels at various locations within the proposed SRS Wetlands Restoration Project area for a range of Savannah River flows and regulated releases from Pen Branch. TABS-MD, a United States Army Corps of Engineer developed two-dimensional finite element open channel hydraulic computer code, was used to model the SRS swamp area for various flow conditions.

  9. Urban growth and environmental impacts in Jing-Jin-Ji, the Yangtze, River Delta and the Pearl River Delta

    NASA Astrophysics Data System (ADS)

    Haas, Jan; Ban, Yifang

    2014-08-01

    This study investigates land cover changes, magnitude and speed of urbanization and evaluates possible impacts on the environment by the concepts of landscape metrics and ecosystem services in China's three largest and most important urban agglomerations: Jing-Jin-Ji, the Yangtze River Delta and the Pearl River Delta. Based on the classifications of six Landsat TM and HJ-1A/B remotely sensed space-borne optical satellite image mosaics with a superior random forest decision tree ensemble classifier, a total increase in urban land of about 28,000 km2 could be detected alongside a simultaneous decrease in natural land cover classes and cropland. Two urbanization indices describing both speed and magnitude of urbanization were derived and ecosystem services were calculated with a valuation scheme adapted to the Chinese market based on the classification results from 1990 and 2010 for the predominant land cover classes affected by urbanization: forest, cropland, wetlands, water and aquaculture. The speed and relative urban growth in Jing-Jin-Ji was highest, followed by the Yangtze River Delta and Pearl River Delta, resulting in a continuously fragmented landscape and substantial decreases in ecosystem service values of approximately 18.5 billion CNY with coastal wetlands and agriculture being the largest contributors. The results indicate both similarities and differences in urban-regional development trends implicating adverse effects on the natural and rural landscape, not only in the rural-urban fringe, but also in the cities' important hinterlands as a result of rapid urbanization in China.

  10. A Comparative Study Environmental and Radiological Causes Of Cancer In River Nile State, Sudan

    NASA Astrophysics Data System (ADS)

    Hamid, Eyad; Khair, Hatim

    The causes of cancer in River Nile state are differ between environmental and radiological, this paper tried to make comparison between the two causes, to determine the real cause behind the large rising of cancer cases in this state, considering the daily habits for the patients and the possible contamination in the natural resources around them. The noticeable thing that most of cancer cases are might be due to the high concentration of nitrate pollutant detected in natural resources such as drinking water; also by looking to the radioactive elements we see there's high concentration of some radioactive elements specially the K-40 which found in Portulaca Oleracea.

  11. [Forest biomass and its dynamics in Pearl River Delta].

    PubMed

    Yang, Kun; Guan, Dong-Sheng

    2007-04-01

    Based on the observation data obtained from 69 sampling sites of different age class forests, and by using biomass expansion factor function, the regression equations of stand biomass and volume of the main forest types in Pearl River Delta were built, and the regional forest biomass and its dynamics were estimated on the basis of forest inventory data. The results showed that most of the forests in Pearl River Delta were of young-medium age, which occupied 80% or more of the total forest area, and their undergrowth biomass accounted for about 33% of the total forest biomass, indicating that the regional forest biomass could be estimated more exactly if undergrowth biomass was fully concerned. In the periods of 1989-1993, 1994-1998 and 1999-2003, the forest biomass in Pearl River Delta increased by 14. 67 x 10(6) t in total, among which, Pinus massoniana forest, evergreen broadleaf forest, and conifer and deciduous mixed forest contributed about 80%. Young-medium age forest biomass accounted for 90% of the total, but the proportion was decreased gradually. The forest area in the Delta almost kept unvaried, and the forest biomass was increasing year after year, with an annual increment of about 1.2%. Better fostering and managing the existing forests is very important to have more forest biomass and better environmental effect that regional forests offered.

  12. Coastal eutrophication near the Mississippi river delta

    NASA Astrophysics Data System (ADS)

    Turner, R. Eugene; Rabalais, Nancy N.

    1994-04-01

    CHANGES in delivery of river-borne nutrients such as dissolved phosphate, nitrate and silicate, owing to land-use changes and anthropogenic emissions, are known to result in eutrophication1- enhanced phytoplankton blooms-and more severe hypoxic events2-1 in many enclosed bays and seas. Although similar ecological effects might be expected on continental shelves, the occurrence of such eutrophication has remained unresolved5. Here we present evidence of eutrophication of the continental shelf near the outflow of the Mississippi river, obtained by quantifying biologically bound silica (BSi) in diatom remnants within dated sediment cores. BSi accumulation rates are greatest in water depths of 20 to 50 m within 100 km of the river mouth, and have increased by as much as 100% this century. The increases were substantial by 1980, by which time riverine nitrogen loading had doubled relative to the beginning of the century, even though the silica loading had declined by 50% over the same period. Thus changes in river-borne nutrient loadings can modify coastal food webs and affect the amount and distribution of oxygen in bottom waters on the scale of continental shelves.

  13. Ecological Risk Assessment of Metal Pollution along Greater Cairo Sector of the River Nile, Egypt, Using Nile Tilapia, Oreochromis niloticus, as Bioindicator

    PubMed Central

    Omar, Wael A.; Mikhail, Wafai Z. A.; Abdo, Hanaa M.; Abou El Defan, Tarek A.; Poraas, Mamdouh M.

    2015-01-01

    The present work aims to evaluate seasonal metal pollution along Greater Cairo sector of the River Nile, Egypt, using wild Nile tilapia, Oreochromis niloticus, as bioindicator and to conduct a risk assessment for human consumers. Greater Cairo is the largest populated area along the whole course of River Nile with a wide range of anthropogenic activities. Effects of metal pollution on fish body indices were studied using condition factor (CF) and scaled mass index (SMI). Metal pollution index (MPI) showed that the total metal load in fish organs followed the follwoing order: kidney > liver > gill > muscle which gives a better idea about the target organs for metal accumulation. Metal concentrations in fish muscle (edible tissue) showed the following arrangement: Fe > Zn > Cu > Mn > Pb > Cd. Metal's bioaccumulation factor (BAF) in fish muscle showed the following arrangement: Zn > Cu > Fe > Mn > Cd and Pb. The hazard index (HI) as an indicator of human health risks associated with fish consumption showed that adverse health effects are not expected to occur in most cases. However, the metals' cumulative risk effects gave an alarming sign specifically at high fish consumption rates. PMID:26617637

  14. Interdisciplinary assessment of sea-level rise and climate change impacts on the lower Nile delta, Egypt.

    PubMed

    Sušnik, Janez; Vamvakeridou-Lyroudia, Lydia S; Baumert, Niklas; Kloos, Julia; Renaud, Fabrice G; La Jeunesse, Isabelle; Mabrouk, Badr; Savić, Dragan A; Kapelan, Zoran; Ludwig, Ralf; Fischer, Georg; Roson, Roberto; Zografos, Christos

    2015-01-15

    CLImate-induced changes on WAter and SECurity (CLIWASEC) was a cluster of three complementary EC-FP7 projects assessing climate-change impacts throughout the Mediterranean on: hydrological cycles (CLIMB - CLimate-Induced changes on the hydrology of Mediterranean Basins); water security (WASSERMed - Water Availability and Security in Southern EuRope and the Mediterranean) and human security connected with possible hydro-climatic conflicts (CLICO - CLImate change hydro-COnflicts and human security). The Nile delta case study was common between the projects. CLIWASEC created an integrated forum for modelling and monitoring to understand potential impacts across sectors. This paper summarises key results from an integrated assessment of potential challenges to water-related security issues, focusing on expected sea-level rise impacts by the middle of the century. We use this common focus to illustrate the added value of project clustering. CLIWASEC pursued multidisciplinary research by adopting a single research objective: sea-level rise related water security threats, resulting in a more holistic view of problems and potential solutions. In fragmenting research, policy-makers can fail to understand how multiple issues can materialize from one driver. By combining efforts, an integrated assessment of water security threats in the lower Nile is formulated, offering policy-makers a clearer picture of inter-related issues to society and environment. The main issues identified by each project (land subsidence, saline intrusion - CLIMB; water supply overexploitation, land loss - WASSERMed; employment and housing security - CLICO), are in fact related. Water overexploitation is exacerbating land subsidence and saline intrusion, impacting on employment and placing additional pressure on remaining agricultural land and the underdeveloped housing market. All these have wider implications for regional development. This richer understanding could be critical in making better

  15. Assessing the Effects of Climate Change on Drought Risk for the Nile River Basin

    NASA Astrophysics Data System (ADS)

    Strzepek, K. M.; Boehlert, B. B.; Vogel, R. M.

    2012-12-01

    Approximately 90 percent of the Nile River runoff is generated within two regions—the Ethiopian highlands and the Lake Victoria and Equatorial Lakes—that have historically contrasting precipitation regimes. As a result of uncorrelated interannual rainfall variability, meteorological droughts in one region are typically offset by wetter periods in the other, thus having a moderating effect on downstream Nile river flow to Sudan and Egypt. Under climate change, the drivers of these contrasting rainfall regimes (including the annual migration of the Inter Tropical Convergence Zone) may be fundamentally altered such that droughts become correlated between these regions, leading to unprecedented low flows in the downstream Nile. The water management challenges that would result are likely to be exacerbated if climate change increases drought occurrence and intensity across the basin. In this research, we first assess the effect of climate change on drought frequency and intensity across eight Nile subbasins by applying the Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI) to the full suite of 22 Intergovernmental Panel on Climate Change General Circulation Models for three IPCC-SRES emissions scenarios (B1, A1B, and A2 from the Special Report on Emissions Scenarios (SRES)). We then use these outputs to evaluate how climate change affects the correlation of drought occurrence and intensity between the Ethiopian highlands and the Lake Victoria and Equatorial Lakes regions. In the first inquiry, we find that the frequency of drought over the next century based on precipitation alone (SPI) is projected to increase in the northern Nile basin, and decrease in the southern regions. Drought frequencies based on both precipitation and temperature (PDSI) are projected to increase across most of the Nile basin, however, with almost universally experienced increases in drought risk by the late 21st century. For both measures, the Ethiopia

  16. Two Myxobolus spp. infecting the kidney of Nile tilapia (Oreochromis niloticus) in the River Nile at Beni-Suef governorate, Egypt, and the associated renal changes.

    PubMed

    Abdel-Baki, Abdel-Azeem S; Abdel-Haleem, Heba M; Sakran, Thabet; Zayed, Eman; Ibrahim, Khalid E; Al-Quraishy, Saleh

    2015-03-01

    Two Myxobolus spp. are described from the kidney of the Nile tilapia (Oreochromis niloticus) collected from the River Nile, Egypt. The prevalence of infection was 61 % (47/77), with the infected fish in each case parasitized by the two Myxobolus species simultaneously. The infection was exhibited as free spores in Bowman capsules and renal glomeruli, which makes their original structures difficult to discern. In some cases, the infection appeared as a fibrous plasmodia-like structure containing degenerated developmental stages and spores in the interstitium. The paper identifies each species based on the morphological characteristics of its spores and identifies the histological impacts of Myxobolus infection in this species of fish. PMID:25566769

  17. Mackenzie River Delta morphological change based on Landsat time series

    NASA Astrophysics Data System (ADS)

    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

  18. Fluvial transport on Titan: formation and evolution of river deltas

    NASA Astrophysics Data System (ADS)

    Witek, Piotr Przemyslaw; Czechowski, Leszek

    2016-10-01

    The Cassini-Huygens mission provided numerous observations indicating that processes of sediment transport are currently operating on the surface of Titan. We performed numerical simulations of flow and sediment transport on Titan with particular emphasis on formation of sedimentary landforms in Titan's lakes. We compared the morphology and evolution of landforms formed in Titanian and terrestrial conditions, under various discharges and with different dominant grain sizes. The processes are similar in both environments; in some cases we observed bifurcation of the flow and switching of the active distributaries. Such processes may lead to abandonment of some delta lobes, as hypothesized for the delta observed in Ontario Lacus on Titan. The lower gravity of Titan and higher buoyancy of the most plausible kinds of sediment result in higher efficiency of transport and generally faster evolution of the deltaic deposits. Our results suggest also that the flat, lobate river deltas may form in narrower range of parameters than on Earth.

  19. Mineralogy and source rock evaluation of the marine Oligo-Miocene sediments in some wells in the Nile Delta and North Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    El sheikh, Hassan; Faris, Mahmoud; Shaker, Fatma; Kumral, Mustafa

    2016-06-01

    This paper aims to study the mineralogical composition and determine the petroleum potential of source rocks of the Oligocene-Miocene sequence in the Nile Delta and North Sinai districts. The studied interval in the five wells can be divided into five rock units arranged from the top to base; Qawasim, Sidi Salem, Kareem, Rudeis, and Qantara formations. The bulk rock mineralogy of the samples was investigated using X-Ray Diffraction technique (XRD). The results showed that the sediments of the Nile Delta area are characterized by the abundance of quartz and kaolinite with subordinate amounts of feldspars, calcite, gypsum, dolomite, and muscovite. On the other hand, the data of the bulk rock analysis at the North Sinai wells showed that kaolinite, quartz, feldspar and calcite are the main constituents associated with minor amounts of dolomite, gypsum, mica, zeolite, and ankerite. Based on the organic geochemical investigations (TOC and Rock-Eval pyrolysis analyses), all studied formations in both areas are thermally immature but in the Nile delta area, Qawasim, Sidi Salem and Qantara formations (El-Temsah-2 Well) are organically-rich and have a good petroleum potential (kerogen Type II-oil-prone), while Rudeis Formation is a poor petroleum potential source rock (kerogen Type III-gas-prone). In the North Sinai area, Qantara Formation has a poor petroleum potential (kerogen Type III-gas-prone) and Sidi Salem Formation (Bardawil-1 Well) is a good petroleum potential source rock (kerogen Type II-oil-prone).

  20. Delta Morphodynamics from River Sediment Input: Dam Removal, Elwha River, Washington, USA.

    NASA Astrophysics Data System (ADS)

    Warrick, J. A.; Gelfenbaum, G. R.; Stevens, A. W.; Miller, I. M.; Kaminsky, G. M.; Ritchie, A.

    2015-12-01

    Sediment supply plays an important role in river delta morphodynamics and sustainability, and it is important to evaluate how deltas respond to the restoration or enhancement of sediment supplies. Here we report on the morphodynamic responses of the Elwha River delta to large increases in river sediment loads from the removal of two large dams beginning in 2011. The dam removal project exposed ~30 million tonnes of sediment stored within the former reservoirs to natural erosion by the river, and roughly half of this reservoir sediment was eroded during the first four years of the project. Coastal surveys with GPS-based mapping systems, sonar, and aerial photography have revealed that the Elwha River mouth has expanded seaward by ~500 m with the introduction of new supplies of sediment. Approximately 3.5 million cubic meters (or ~5 million tonnes) of sediment were deposited at the river mouth delta between 2011 and 2015. This newly deposited sediment has been shaped by waves and currents into a series of dynamic bars that have greatly expanded the estuarine habitats of the delta.

  1. Oscillatory modes of extended Nile River records (A.D. 622-1922)

    NASA Astrophysics Data System (ADS)

    Kondrashov, D.; Feliks, Y.; Ghil, M.

    2005-05-01

    The historical records of the low- and high-water levels of the Nile River are among the longest climatic records that have near-annual resolution. There are few gaps in the first part of the records (A.D. 622-1470) and larger gaps later (A.D. 1471-1922). We apply advanced spectral methods, Singular-Spectrum Analysis (SSA) and the Multi-Taper Method (MTM), to fill the gaps and to locate interannual and interdecadal periodicities. The gap filling uses a novel, iterative version of SSA. Our analysis reveals several statistically significant features of the records: a nonlinear, data-adaptive trend that includes a 256-year cycle, a quasi-quadriennial (4.2-year) and a quasi-biennial (2.2-year) mode, as well as additional periodicities of 64, 19, 12, and, most strikingly, 7 years. The quasi-quadriennial and quasi-biennial modes support the long-established connection between the Nile River discharge and the El-Niño/Southern Oscillation (ENSO) phenomenon in the Indo-Pacific Ocean. The longest periods might be of astronomical origin. The 7-year periodicity, possibly related to the biblical cycle of lean and fat years, seems to be due to North Atlantic influences.

  2. Relationship between heavy metals in mud sediments and beach soil of the River Nile

    SciTech Connect

    Awadallah, R.M.; Soltan, M.E.; Rashed, M.N.

    1996-08-01

    the chemical partitioning of selected inorganic ions was investigated in mud sediments taken from the bottom of the main stream of the River Nile by means of sediment sampler and beach soil samples collected from seven sectors (three subsamples from each location) between Aswan and Giza (Aswan, Qena, Sohag, Assiut, El Menya, Beni Suef, and Giza). These samples were analyzed by an atomic absorption spectrophotometer. The results showed that iron and lead were found at higher levels in beach soil than in the river sediments at all sites except for iron sediments of Aswan where the region was subjected to volcanic activities in the ancient geological eras (granites,.....etc.). At some sites, some heavy-metal concentrations seemed to be higher in sediment than in beach soil as a result of weathering of beach soil by the effect of wind and currents of water. In other sites, sediment pollution by these metals might be attributed to inputs from industrial effluents and domestic wastewater drained directly into the Nile. Statistical analysis of data shows significant correlation coefficient values (r= up to 0.915) 30 refs., 1 fig., 2 tabs.

  3. Isolation and characterization of microcystins from a river nile strain of Oscillatoria tenuis Agardh ex Gomont.

    PubMed

    Brittain, S; Mohamed, Z A; Wang, J; Lehmann, V K; Carmichael, W W; Rinehart, K L

    2000-12-01

    The River Nile is the major source of drinking water in Egypt, however, increased eutrophication due to agricultural, municipal and industrial runoff has contributed to the growth of toxin producing cyanobacteria. This study describes the isolation and characterization of microcystins (MCYSTs), cyclic heptapeptide hepatotoxins, from a rare strain of Oscillatoria tenuis, isolated from the River Nile at Sohag province in July 1995. The MCYST concentration of laboratory-cultured O. tenuis strain E6 was found to be 0.3 mg/g freeze-dried weight determined by enzyme-linked immunosorbent assay (ELISA). Two microcystins, 1 and 2, were isolated from lyophilized cells using solid phase extraction and reversed-phase high performance liquid chromatography (HPLC). Structures were assigned based upon their amino acid analyses, electrospray ionization mass spectrometry (ESIMS, ESIMS-CID-MS), high resolution fast atom bombardment mass spectrometry, and nuclear magnetic resonance data ((1)H and (1)H COSY NMR). Toxin 1 was identified as MCYST-LR, and toxin 2, a new MCYST, as MCYST-LHArg ([L-homoarginine(4)]). Previous studies indicate that Oscillatoria agardhii strains produce demethylated MCYSTs (containing D-Asp and/or dehydroalanine). This is the first report of a toxic O. tenuis, strain E6, one which produces a fully methylated MCYST, MCYST-LR and a new L-homoarginine containing MCYST, MCYST-LHArg.

  4. Tide and river influences on distributary channels of the Mekong River delta

    NASA Astrophysics Data System (ADS)

    Saito, Y.; Nguyen, V. L.; Ta, T. K. O.; Tamura, T.; Kanai, Y.; Nakashima, R.

    2015-12-01

    The Mekong River delta, one of the world's largest deltas, has extended from Phnom Penh in Cambodia (apex) to the coast from the Saigon River mouth to Cape Camau in Vietnam with a triangular-shape area of more than 60,000 km2. The delta has prograded more than 200 km over at least the last 6-7 ka. The river-mouth area of the delta is meso-tidal with the mean tidal range of 2.5 ± 0.1 m and the maximum tidal range is 3.2-3.8 m. The mean wave height is 0.9 m. Its water discharge is 470 km3/y and its sediment discharge is 160 million t/y, or tenth and ninth largest in the world, respectively. The water discharge varies by season because most of the drainage area is under a monsoonal tropical regime. The flow at Phnom Penh, Cambodia, reaches a maximum in October (typically 39,000 m3/s) and a minimum in May (about 1700 m3/s). Tidal water-level changes are observed in Cambodia, more than 200 km upstream from the river mouth. To understand the combined influenced of river and tide on river bottom sediments, we have collected ~210 surface samples from river bottoms of the whole Mekong River delta in Vietnam, covering five distributaries during dry season from January to May 2015. Sediment characteristics show clearly tide- and river-influenced areas, which are closely linked with river morphology.

  5. Asynchronous changes in vegetation, runoff and erosion in the nile river watershed during the holocene.

    PubMed

    Blanchet, Cécile L; Frank, Martin; Schouten, Stefan

    2014-01-01

    The termination of the African Humid Period in northeastern Africa during the early Holocene was marked by the southward migration of the rain belt and the disappearance of the Green Sahara. This interval of drastic environmental changes was also marked by the initiation of food production by North African hunter-gatherer populations and thus provides critical information on human-environment relationships. However, existing records of regional climatic and environmental changes exhibit large differences in timing and modes of the wet/dry transition at the end of the African Humid Period. Here we present independent records of changes in river runoff, vegetation and erosion in the Nile River watershed during the Holocene obtained from a unique sedimentary sequence on the Nile River fan using organic and inorganic proxy data. This high-resolution reconstruction allows to examine the phase relationship between the changes of these three parameters and provides a detailed picture of the environmental conditions during the Paleolithic/Neolithic transition. The data show that river runoff decreased gradually during the wet/arid transition at the end of the AHP whereas rapid shifts of vegetation and erosion occurred earlier between 8.7 and ∼6 ka BP. These asynchronous changes are compared to other regional records and provide new insights into the threshold responses of the environment to climatic changes. Our record demonstrates that the degradation of the environment in northeastern Africa was more abrupt and occurred earlier than previously thought and may have accelerated the process of domestication in order to secure sustainable food resources for the Neolithic African populations. PMID:25551633

  6. Asynchronous Changes in Vegetation, Runoff and Erosion in the Nile River Watershed during the Holocene

    PubMed Central

    Blanchet, Cécile L.; Frank, Martin; Schouten, Stefan

    2014-01-01

    The termination of the African Humid Period in northeastern Africa during the early Holocene was marked by the southward migration of the rain belt and the disappearance of the Green Sahara. This interval of drastic environmental changes was also marked by the initiation of food production by North African hunter-gatherer populations and thus provides critical information on human-environment relationships. However, existing records of regional climatic and environmental changes exhibit large differences in timing and modes of the wet/dry transition at the end of the African Humid Period. Here we present independent records of changes in river runoff, vegetation and erosion in the Nile River watershed during the Holocene obtained from a unique sedimentary sequence on the Nile River fan using organic and inorganic proxy data. This high-resolution reconstruction allows to examine the phase relationship between the changes of these three parameters and provides a detailed picture of the environmental conditions during the Paleolithic/Neolithic transition. The data show that river runoff decreased gradually during the wet/arid transition at the end of the AHP whereas rapid shifts of vegetation and erosion occurred earlier between 8.7 and ∼6 ka BP. These asynchronous changes are compared to other regional records and provide new insights into the threshold responses of the environment to climatic changes. Our record demonstrates that the degradation of the environment in northeastern Africa was more abrupt and occurred earlier than previously thought and may have accelerated the process of domestication in order to secure sustainable food resources for the Neolithic African populations. PMID:25551633

  7. Asynchronous changes in vegetation, runoff and erosion in the nile river watershed during the holocene.

    PubMed

    Blanchet, Cécile L; Frank, Martin; Schouten, Stefan

    2014-01-01

    The termination of the African Humid Period in northeastern Africa during the early Holocene was marked by the southward migration of the rain belt and the disappearance of the Green Sahara. This interval of drastic environmental changes was also marked by the initiation of food production by North African hunter-gatherer populations and thus provides critical information on human-environment relationships. However, existing records of regional climatic and environmental changes exhibit large differences in timing and modes of the wet/dry transition at the end of the African Humid Period. Here we present independent records of changes in river runoff, vegetation and erosion in the Nile River watershed during the Holocene obtained from a unique sedimentary sequence on the Nile River fan using organic and inorganic proxy data. This high-resolution reconstruction allows to examine the phase relationship between the changes of these three parameters and provides a detailed picture of the environmental conditions during the Paleolithic/Neolithic transition. The data show that river runoff decreased gradually during the wet/arid transition at the end of the AHP whereas rapid shifts of vegetation and erosion occurred earlier between 8.7 and ∼6 ka BP. These asynchronous changes are compared to other regional records and provide new insights into the threshold responses of the environment to climatic changes. Our record demonstrates that the degradation of the environment in northeastern Africa was more abrupt and occurred earlier than previously thought and may have accelerated the process of domestication in order to secure sustainable food resources for the Neolithic African populations.

  8. Volga River Delta and Caspian Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color MODIS image from May 10, 2002, captures Russia's Volga River (running south through the center) emptying into the northern portion of the Caspian Sea. The waters of the Caspian Sea are quite murky in this image, highlighting the water quality problems plaguing the sea. The sea is inundated with sewage and industrial and agricultural waste, which is having measurable impact on human health and wildlife. According reports from the Department of Energy, in less than a decade the sturgeon catch dropped from 30,000 tons to just over 2,000 tons. National and international groups are currently joining together to find strategies of dealing with the environmental problems of the Caspian Sea. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  9. Changes in the areal extents of the Athabasca River, Birch River, and Cree Creek Deltas, 1950-2014, Peace-Athabasca Delta, Canada

    NASA Astrophysics Data System (ADS)

    Timoney, Kevin; Lee, Peter

    2016-04-01

    Deltas form where riverborne sediment accumulates at the interface of river mouths and their receiving water bodies. Their areal extent is determined by the net effect of processes that increase their extent, such as sediment accumulation, and processes that decrease their extent, such as erosion and subsidence. Through sequential mapping and construction of river discharge and sediment histories, this study examined changes in the subaerial extents of the Cree Creek and Athabasca River Deltas (both on the Athabasca River system) and the Birch River Delta in northern Canada over the period 1950-2014. The purpose of the study was to determine how, when, and why the deltas changed in areal extent. Temporal growth patterns were similar across the Athabasca and Birch River systems indicative of a climatic signal. Little or no areal growth occurred from 1950 to 1968; moderate growth occurred between 1968 and the early to mid-1980s; and rapid growth occurred between 1992 and 2012. Factors that affected delta progradation included dredging, sediment supply, isostatic drowning, delta front bathymetry, sediment capture efficiency, and storms. In relation to sediment delivered, areal growth rates were lowest in the Athabasca Delta, intermediate in the Birch Delta, and highest in the Cree Creek Delta. Annual sediment delivery is increasing in the Cree Creek Delta; there were no significant trends in annual sediment delivery in the Birch and Athabasca Deltas. There was a lag of up to several years between sediment delivery events and progradation. Periods of delta progradation were associated with low water levels of the receiving basins. Predicted climate-change driven declines in river discharge and lake levels may accelerate delta progradation in the region. In the changing ecosystems of northeastern Alberta, inadequate monitoring of vegetation, landforms, and sediment regimes hampers the elucidation of the nature, rate, and causality of ecosystem changes.

  10. Fluvial geoarchaeology in Avaris, the Hyksos capital in the Eastern Nile Delta (2nd Mill. B.C.)

    NASA Astrophysics Data System (ADS)

    Schmitt, Laurent; Goiran, Jean-Philippe; Tronchère, Hervé; Forstner-Muller, Irene

    2014-05-01

    Tell el-Dab'a, the ancient city of Avaris, is a key site for understanding the complex alluvial environment of the Nile delta in northern Egypt which is characterized by a palaeo-network of anastomosing branches. Avaris, the capital of the Hyksos kings, is located on the Pelusiac palaeo-branch, near the eastern margin of the delta. Avaris was an important harbour town from the late 12th Dynasty until the end of the Hyksos Period and then again in the Ramesside Period. For the first time, OSL, radiocarbon and archaeological datings have been combined on the fluvial archives. This database helps us to understand better the chrono-stratigraphy and the evolution of the palaeo-environments. Sedimentary analyses have been conducted on (i) the stratigraphy on the main harbour basin revealed by an excavation in spring 2013 (ii) the sediments that gradually silted in the pelusiac branch: coarse bedload at the bottom and sands to fine silts above. A complete bankfull cross section of the Pelusiac branch has been obtained. Thus, we get 3 important characteristics of the main branch: (1) the width, (2) the depth (3) and the palaeo-discharge has been computed. In order to get an idea of the palaeo-processes, C/M diagrams have been done thanks to the micro-granulometric data. By combining these results, a 5 millennium diachronic cartography of the evolution of the Pelusiac palaeo-branch near Avaris has been produced, providing new insights into the natural landscape evolution that may have accelerated the demise of the great city.

  11. A preliminary disease survey in the wild Nile crocodile (Crocodylus niloticus) population in the Okavango Delta, Botswana.

    PubMed

    Leslie, A J; Lovely, C J; Pittman, J M

    2011-09-01

    The objective of this study was to conduct a preliminary survey of diseases that might be present in the wild Nile crocodile population in the Okavango Delta, Botswana. Blood samples were collected from crocodiles ranging in size from 34.0 cm to 463.0 cm total length. Samples were examined for blood parasites and underwent a haematological analysis. Before release the crocodiles were examined for various clinical abnormalities. Of the 144 crocodiles examined, none were visibly sick or displayed any signs of disease. No antibodies to Mycoplasma crocodyli were detected. Hepatozoon pettiti was present in 55.3% of blood smears examined, but there was no significant difference in any of the haematological values between the infected and uninfected crocodiles, and a high prevalence of Hepatozoon infection is not uncommon in other species. Only 7.6% of the examined crocodiles were infested with leeches. Further research is required for several of the crocodilian diseases, in particular to elucidate the role of wild crocodilians as reservoirs of infection.

  12. Stratigraphic framework, sedimentology and structural setting of Miocene-Pliocene sediments of the Abu Qir area, offshore Nile delta

    SciTech Connect

    Ince, D.M.; Deibis, S.; McSherry, A.; Seymour, W.P.

    1988-08-01

    The offshore Nile delta contains significant gas resources which are currently undergoing both production and appraisal in the Abu Qir field and adjacent areas. The principal reservoir occurs in sandstones of the upper Abu Madi Member (upper Miocene), but excellent potential reservoirs exist in the lower Abu Madi Member (upper Miocene), Sidi Salem (middle-upper Miocene), and Moghra (middle Miocene) Formations. Gas is trapped in fault-bounded anticlinal structures sealed by shales of the Pliocene Kafr el Sheikh Formation. Early wells in the Abu Qir field revealed an apparently simple stratigraphic picture. More recently, however, drilled wells have revealed a more complex stratigraphic situation. Integrated biostratigraphic and sedimentologic studies demonstrate the existence of a fault block or horst structure beneath part of the field, giving rise to the observed stratigraphic complexity. Such a structure was not visible on seismic data due to inhibited reflection quality beneath the overlying Messinian anhydrite but has since been demonstrated by reprocessing and reinterpreting seismic data. The presence of a structural style of this type provides a new concept for hydrocarbon exploration in the area. Reservoir sandstones of the Abu Madi, Sidi Salem, and Moghra Formations are interpreted as sediment gravity flow deposits whose distribution is strongly influenced by syndepositional tectonics. This interpretation, supported by microfossil assemblages, provides important constraints for both reservoir modeling and further exploration.

  13. Shifting Sediment Sources in the Quaternary Nile

    NASA Astrophysics Data System (ADS)

    Woodward, Jamie; Macklin, Mark; Fielding, Laura; Millar, Ian; Williams, Martin

    2016-04-01

    Invited Paper The Nile basin contains the longest river channel system in the world and drains about one tenth of the African continent. A dominant characteristic of the modern Nile is the marked spatial and temporal variability in the flux of water and sediment. Because the major headwater basins of the Nile are linked to key elements of the global climate system, the sedimentary records in the basin have attracted good deal of attention from the Quaternary palaeoclimate and palaeohydrology communities. Various approaches (from heavy minerals to strontium isotopes) have been employed to examine present and past patterns of sediment yield in the basin. A good deal of work has been carried out on the long sediment records in the delta and offshore which provide high resolution archives of hydrological changes in the upstream basin as well fluctuations in the input of dust from the desert. The sediment load of the modern desert Nile (downstream of Khartoum) is dominated by sediment inputs from the Blue Nile (61 +/- 5%) and Atbara (35 +/- 4%), whilst the White Nile contribution is meagre (3 +/- 2%) (Padoan et al. 2011). Recent work has shown that these values were very different during humid phases of the Quaternary when stronger Northern Hemisphere summer insolation produced wetter conditions across North Africa. In the early Holocene, for example, the Nile floodplain in Northern Sudan shows a tributary wadi input of 40-50%. This paper will review three decades of work on the sediment delivery dynamics of the Quaternary Nile and explore their palaeoclimatic implications. Padoan, M., Garzanti, E., Harlavan, Y., Villa, I.M. (2011) Tracing Nile sediment sources by Sr and Nd isotope signatures (Uganda, Ethiopia, Sudan). Geochim. Cosmochim. Acta 75 (12), 3627-3644.

  14. Mosquitoes and West Nile virus along a river corridor from prairie to montane habitats in eastern Colorado.

    PubMed

    Barker, Christopher M; Bolling, Bethany G; Black, William C; Moore, Chester G; Eisen, Lars

    2009-12-01

    We conducted studies on mosquitoes and West Nile virus (WNV) along a riparian corridor following the South Platte River and Big Thompson River in northeastern Colorado and extending from an elevation of 1,215 m in the prairie landscape of the eastern Colorado plains to 1,840 m in low montane areas at the eastern edge of the Rocky Mountains in the central part of the state. Mosquito collection during June-September 2007 in 20 sites along this riparian corridor yielded a total of 199,833 identifiable mosquitoes of 17 species. The most commonly collected mosquitoes were, in descending order: Aedes vexans, Culex tarsalis, Ae. dorsalis, Ae. trivittatus, Ae. melanimon, Cx. pipiens, and Culiseta inornata. Species richness was higher in the plains than in foothills-montane areas, and abundances of several individual species, including the WNV vectors Cx. tarsalis and Cx. pipiens and the nuisance-biter and potential secondary WNV vector Ae. vexans, decreased dramatically from the plains (1,215-1,487 m) to foothills-montane areas (1,524-1,840 m). Ae. vexans and Cx. tarsalis had a striking pattern of uniformly high abundances between 1,200-1,450 m followed by a gradual decrease in abundance above 1,450 m to reach very low numbers above 1,550 m. Culex species were commonly infected with WNV in the plains portion of the riparian corridor in 2007, with 14 of 16 sites yielding WNV-infected Cx. tarsalis and infection rates for Cx. tarsalis females exceeding 2.0 per 1,000 individuals in ten of the sites. The Vector Index for abundance of WNV-infected Cx. tarsalis females during June-September exceeded 0.5 in six plains sites along the South Platte River but was uniformly low (0-0.1) in plains, foothills and montane sites above 1,500 m along the Big Thompson River. A population genetic analysis of Cx. tarsalis revealed that all collections from the ≈190 km riparian transect in northeastern Colorado were genetically uniform but that these collections were genetically distinct from

  15. Nile River

    Atmospheric Science Data Center

    2013-04-15

    ... of which occurred north of Khartoum. According to the Food and Agriculture Organization of the United Nations, tens of thousands of ... fled their homes, and the number of people in need of urgent food assistance in Sudan, estimated at three million earlier in the year, was ...

  16. Optimal operation of a multipurpose multireservoir system in the Eastern Nile River Basin

    NASA Astrophysics Data System (ADS)

    Goor, Q.; Halleux, C.; Mohamed, Y.; Tilmant, A.

    2010-07-01

    The upper Blue Nile River Basin in Ethiopia is a largely untapped resource despite its huge potential for hydropower generation and irrigated agriculture. Controversies exist as to whether the numerous infrastructural development projects that are on the drawing board in Ethiopia will generate positive or negative externalities downstream in Sudan and Egypt. This study attempts at 1) examining the (re-)operation of infrastructures, in particular the proposed reservoirs in Ethiopia and the High Aswan Dam and 2) assessing the economic benefits and costs associated with the storage infrastructures in Ethiopia and their spatial and temporal distribution. To achieve this, a basin-wide integrated hydro-economic model has been developed. The model integrates essential hydrologic, economic and institutional components of the river basin in order to explore both the hydrologic and economic consequences of various policy options and planned infrastructural projects. Unlike most of the deterministic economic-hydrologic models reported in the literature, a stochastic programming formulation has been adopted in order to: i) understand the effect of the hydrologic uncertainty on management decisions, ii) determine allocation policies that naturally hedge against the hydrological risk, and iii) assess the relevant risk indicators. The study reveals that the development of four mega dams in the upper part of the Blue Nile Basin would change the drawdown refill cycle of the High Aswan Dam. Should the operation of the reservoirs be coordinated, they would enable an average annual saving of at least 2.5 billion m3 through reduced evaporation losses from the Lake Nasser. Moreover, the new reservoirs (Karadobi, Beko-Abo, Mandaya and Border) in Ethiopia would have significant positive impacts on hydropower generation and irrigation in Ethiopia and Sudan: at the basin scale, the annual energy generation is boosted by 38.5 TWh amongst which 14.2 TWh due to storage. Moreover, the

  17. Optimal operation of a multipurpose multireservoir system in the Eastern Nile River Basin

    NASA Astrophysics Data System (ADS)

    Goor, Q.; Halleux, C.; Mohamed, Y.; Tilmant, A.

    2010-10-01

    The upper Blue Nile River Basin in Ethiopia is a largely untapped resource despite its huge potential for hydropower generation and irrigated agriculture. Controversies exist as to whether the numerous infrastructural development projects that are on the drawing board in Ethiopia will generate positive or negative externalities downstream in Sudan and Egypt. This study attempts at (1) examining the (re-)operation of infrastructures, in particular the proposed reservoirs in Ethiopia and the High Aswan Dam and (2) assessing the economic benefits and costs associated with the storage infrastructures in Ethiopia and their spatial and temporal distribution. To achieve this, a basin-wide integrated hydro-economic model has been developed. The model integrates essential hydrologic, economic and institutional components of the river basin in order to explore both the hydrologic and economic consequences of various policy options and planned infrastructural projects. Unlike most of the deterministic economic-hydrologic models reported in the literature, a stochastic programming formulation has been adopted in order to: (i) understand the effect of the hydrologic uncertainty on management decisions, (ii) determine allocation policies that naturally hedge against the hydrological risk, and (iii) assess the relevant risk indicators. The study reveals that the development of four mega dams in the upper part of the Blue Nile Basin would change the drawdown refill cycle of the High Aswan Dam. Should the operation of the reservoirs be coordinated, they would enable an average annual saving of at least 2.5 billion m3 through reduced evaporation losses from the Lake Nasser. Moreover, the new reservoirs (Karadobi, Beko-Abo, Mandaya and Border) in Ethiopia would have significant positive impacts on hydropower generation and irrigation in Ethiopia and Sudan: at the basin scale, the annual energy generation is boosted by 38.5 TWh amongst which 14.2 TWh due to storage. Moreover, the

  18. Morphology of river deltas on Earth and Titan

    NASA Astrophysics Data System (ADS)

    Witek, Piotr; Czechowski, Leszek

    2016-04-01

    Presently volatile cycles are known to operate on surfaces of two planetary bodies in the Solar System, Earth and Titan. Fluvial erosion, transport and deposition of rocky material modify parts of the surface. Numerous indications of geologically recent sediment transport have been discovered on Titan by the Cassini-Huygens mission. Theoretical calculations suggest greater mobility of Titanian sediments in comparison to terrestrial, due to lower gravity and lower density of typical crustal material. Using numerical model of flow and sediment transport, we compare the development and morphology of deposits forming in lakes in terrestrial and Titanian conditions. We explore the range of possible river discharges, including natural variability, and several dominant grain sizes. We consider several compositions of sediments on Titan, on Earth we model the transport of quartz grains by water. We perform simulations for the same initial geometry of river channel and lake basin, for a given discharge and dominant grain diameter in each environment. Morphology and evolution of the deltaic deposits are compared. We observe that the erosion has dominant role for the smallest grains, and the effect is more pronounced on Titan than on Earth. The largest grains usually form steep-sloped fan-like deltas on both planetary bodies. The processes of formation and development of the sedimentary landforms are generally similar in both environments. Particular types of deposits may however form in different ranges of discharge and grain size, due to differences in environmental parameters. Greater mobility of sediments on Titan result in easier displacement of loose granular material, especially for smallest considered grains. The flat, lobate deltas can form in narrower range of discharges and grain sizes than on Earth. This fact might be partially responsible for scarcity of river deltas on that active moon, where other signs of fluvial processes are widespread.

  19. Biogeochemical features of aquatic plants in the Selenga River delta

    NASA Astrophysics Data System (ADS)

    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

  20. Ruminant Brucellosis in the Kafr El Sheikh Governorate of the Nile Delta, Egypt: Prevalence of a Neglected Zoonosis

    PubMed Central

    Hegazy, Yamen M.; Moawad, Amgad; Osman, Salama; Ridler, Anne; Guitian, Javier

    2011-01-01

    Background Brucellosis is a neglected tropical zoonosis allegedly reemerging in Middle Eastern countries. Infected ruminants are the primary source of human infection; consequently, estimates of the frequency of ruminant brucellosis are useful elements for building effective control strategies. Unfortunately, these estimates are lacking in most Middle East countries including Egypt. Our objectives are to estimate the frequency of ruminant brucellosis and to describe its spatial distribution in Kafr El Sheikh Governorate, Nile Delta, Egypt. Methodology/Principal Findings We conducted a cross-sectional study in which 791 sheep, 383 goats, 188 cattle milk tanks and 173 buffalo milk tanks were randomly selected in 40 villages and tested for the presence of antibodies against Brucella spp. The seroprevalence among different species was estimated and visualized using choropleth maps. A spatial scanning method was used to identify areas with significantly higher proportions of seropositive flocks and milk tanks. We estimated that 12.2% of sheep and 11.3% of goats in the study area were seropositive against Brucella spp. and that 12.2% and 12% of cattle and buffalo milk tanks had antibodies against Brucella spp. The southern part of the governorate had the highest seroprevalence with significant spatial clustering of seropositive flocks in the proximity of its capital and around the main animal markets. Conclusions/ Significance Our study revealed that brucellosis is endemic at high levels in all ruminant species in the study area and questions the efficacy of the control measures in place. The high intensity of infection transmission among ruminants combined with high livestock and human density and widespread marketing of unpasteurized milk and dairy products may explain why Egypt has one of the highest rates of human brucellosis worldwide. An effective integrated human-animal brucellosis control strategy is urgently needed. If resources are not sufficient for nationwide

  1. Effects of Bahir Dar Textile Factory Effluents on the Water Quality of the Head Waters of Blue Nile River, Ethiopia

    PubMed Central

    Mehari, Abrehet Kahsay; Gebremedhin, Shewit; Ayele, Belayneh

    2015-01-01

    The study was conducted in 2013/14 with the objective of determining the effects of Bahir Dar textile factory effluents on the head of Blue Nile River water quality. Dissolve oxygen was higher at the upstream site of the river, whereas BOD5, TDS, and total alkalinity values were higher at wastewater outlet of the factory site. The mean values of dissolved oxygen, BOD5, and total alkalinity were above maximum permissible limits set by WHO for drinking water at head of Blue Nile River. The mean value of BOD5 was above permissible limit of IFC for textile effluents to be discharged to surface water. A total of 836 aquatic macroinvertebrate individuals belonging to 21 families were collected. The Shannon-Wiener Diversity Index, the Hilsenhoff family-level biotic index, family richness, and percent dipterans were calculated. Hilsenhoff family-level biotic index and percent dipterans metrics differed significantly among sampling sites (P < 0.05). Hilsenhoff family-level biotic index was higher at the most downstream site but percent dipterans were higher at site of discharge of effluent to the head of Blue Nile River. Therefore, there is indication that effluent demands frequent control and proper treatment before being discharged to the environment. PMID:26688685

  2. Effects of Bahir Dar Textile Factory Effluents on the Water Quality of the Head Waters of Blue Nile River, Ethiopia.

    PubMed

    Mehari, Abrehet Kahsay; Gebremedhin, Shewit; Ayele, Belayneh

    2015-01-01

    The study was conducted in 2013/14 with the objective of determining the effects of Bahir Dar textile factory effluents on the head of Blue Nile River water quality. Dissolve oxygen was higher at the upstream site of the river, whereas BOD5, TDS, and total alkalinity values were higher at wastewater outlet of the factory site. The mean values of dissolved oxygen, BOD5, and total alkalinity were above maximum permissible limits set by WHO for drinking water at head of Blue Nile River. The mean value of BOD5 was above permissible limit of IFC for textile effluents to be discharged to surface water. A total of 836 aquatic macroinvertebrate individuals belonging to 21 families were collected. The Shannon-Wiener Diversity Index, the Hilsenhoff family-level biotic index, family richness, and percent dipterans were calculated. Hilsenhoff family-level biotic index and percent dipterans metrics differed significantly among sampling sites (P < 0.05). Hilsenhoff family-level biotic index was higher at the most downstream site but percent dipterans were higher at site of discharge of effluent to the head of Blue Nile River. Therefore, there is indication that effluent demands frequent control and proper treatment before being discharged to the environment.

  3. Bathymetry of the Hong and Luoc River Junction, Red River Delta, Vietnam, 2010

    USGS Publications Warehouse

    Kinzel, Paul J.; Nelson, Jonathan M.; Toan, Duong Duc; Thanh, Mung Dinh; Shimizu, Yasuyuki

    2012-01-01

    The U.S. Geological Survey, in collaboration with the Water Resources University in Hanoi, Vietnam, conducted a bathymetric survey of the junction of the Hong and Luoc Rivers. The survey was done to characterize the channel morphology of this delta distributary network and provide input for hydrodynamic and sediment transport models. The survey was carried out in December 2010 using a boat-mounted multibeam echo sounder integrated with a global positioning system. A bathymetric map of the Hong and Luoc River junction was produced which was referenced to the datum of the Trieu Duong tide gage on the Luoc River.

  4. River, delta and coastal morphological response accounting for biological dynamics

    NASA Astrophysics Data System (ADS)

    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.

  5. Impacts of the Indian Rivers Inter-link Project on Sediment Transport to River Deltas

    NASA Astrophysics Data System (ADS)

    Higgins, S.; Overeem, I.; Syvitski, J. P.

    2015-12-01

    The Indian Rivers Inter-link project is a proposal by the Indian government to link several of India's major rivers via a network of reservoirs and canals. Variations of the IRI have been discussed since 1980, but the current plan has recently received increased support from the Indian government. Construction on three canals has controversially begun. If the Inter-link project moves forward, fourteen canals will divert water from tributaries of the Ganges and Brahmaputra rivers to areas in the west, where fresh water is needed for irrigation. Additional canals would transport Himalayan sediments 500 km south to the Mahanadi delta and more than 1000 km south to the Godavari and Krishna deltas. We investigate the impacts of the proposed diversions on sediment transport to the Mahanadi/Brahmani, Godavari, and Krishna deltas in India and the Ganges-Brahmaputra Delta in Bangladesh. We map the entire river network and the proposed new nodes and connections. Changing watersheds are delineated using the Terrain Analysis Using Digital Elevation Models (TauDEM) Suite. Climate data comes from interpolation between observed precipitation stations located in China, Nepal, India, Bhutan and Bangladesh. Changes in water discharge due to the proposed canals are simulated using HydroTrend, a climate-driven hydrological water balance and transport model that incorporates drainage area, discharge, relief, temperature, basin-average lithology, and anthropogenic influences. Simulated river discharge is validated against observations from gauging stations archived by the Global Runoff Data Center (GRDC). HydroTrend is then used to investigate sediment transport changes that may result from the proposed canals. We also quantify changes in contributing areas for the outlets of nine major Indian rivers, showing that more than 50% of the land in India will contribute a portion of its runoff to a new outlet should the entire canal system be constructed.

  6. Research on vulnerability assessments of the Huanghe (Yellow River) delta

    NASA Astrophysics Data System (ADS)

    qiao, shuqing; shi, xuefa

    2014-05-01

    Coastal zone located at the juncture of the sea, river and land, and under the influence of both land and ocean (including atmosphere), especially the sea-level rise and human activities, are vulnerable to environment and ecology. At highest risk are coastal zone of South, Southeast and East Asia with dense populations, low elevations and inadequate adaptive capacity. In China, more than 40% of the population live on the 15% of the land in coastal area and more than 70% cities located around the coastal area. The Chinese coastal region, especially river delta area has been experienced erosion, seawater intrusion and decrease in biodiversity under the combined influence of sea-level rise, tectonic subsidence and flooding. Furthermore, some kinds of human activity, such as land use, building, dam construction, reclamation from the sea and waste dumping strengthen the vulnerability of environment and ecosystem in coastal region. The coastal hazards (e.g. coastal erosion, seawater intrusion, land subsidence) and vulnerability of the Huanghe (Yelllow River) delta area are studied during the past several years. A systematic coastal assessment index is built and an evaluation model is developed using the development platform of Visual studio.Net 2005. The assessment index system includes two parts, inherent (sea level rise rate, elevation, morphology, water and sediment discharge, mean tidal range, mean wave height etc) and specific vulnerability index (population density, GDP, land utilization, protection structures etc). The assessment index are determined the weight using Analytic hierarchy process (AHP) method. Based on the research results, we better understand the current status and future change of coastal vulnerability and hazards, discuss the impact of the natural possess and human activities. Furthermore, we provide defending strategies for coastal zone vulnerability and typical coastal hazards.

  7. Hydrologic Modeling of a Tropical River Delta by Applying Remote Sensing Data: the Niger Delta and its Distributaries.

    NASA Astrophysics Data System (ADS)

    Hannon, M. T.; Syvitski, J. P.; Kettner, A. J.

    2008-12-01

    Delta regions offer rich resources to coastal human populations with their large upstream freshwater sources. Tropical deltas such as the Niger, Nigeria, whose drainage basin incorporates arid regions, receive a significant portion of their runoff from precipitation falling directly on the delta. Between 1970 and 2006, the Niger discharged (Lokoja station) 5000 ± 890 m3/s into upper delta. Here we apply Tropical Rainfall Measurement Mission (TRMM) based precipitation estimates (SB42), with a 0.25° x 0.25° spatial resolution (~100 grid points across the Niger Delta at 3 hourly intervals 1998-2008), and MODIS evapotranspiration (ET) estimates (MOD16), to determine the impact of massive local precipitation events on the routing of water and sediment flux through the Niger Delta's distributaries. The Niger delta receives 2275 mm/y ± 264 mm/y of rainfall with the SE area exceeding 3500 mm/y. The delta's ET varies seasonally between 45 and 65 mm/mo. The in situ generated hydrological runoff is 1675 mm/y, or an equivalent of a discharge 73% the size of the river flux entering the delta. With maximum annual daily discharge from the Niger often exceeding 15,000 m3/s, in combination with the significant in situ runoff, much of the delta's surface is seasonally under floodwaters. LandSat7 imagery indicates delta distributaries that are disconnected from the Niger River, and only drain local precipitation events. This disconnection plays into the discharge and sediment fluxes of these distributaries.

  8. The Riverbed Evolution, Avulsions and Backwater Hydrodynamics on the Huanghe River Delta

    NASA Astrophysics Data System (ADS)

    Chu, Z.; Ganti, V.; Lamb, M. P.

    2013-12-01

    The Huanghe River is known for high suspended sediment concentration and resultant heavy sedimentation and frequent channel-shifting among major rivers in the world. This plain coastal river is the main contributor of terrestrial sediment to the Bohai Sea and the Yellow Sea. Since 1855, there have been 11 major avulsions (versus 4 avulsions on the Mississippi River during the Holocene) on the lower reach with an recurrence interval of ~10 years, developing individual lobes that build up the modern Huanghe River delta. We summarize the main features of riverbed evolution on the delta with a database of measured data. The observed avulsions on the delta often occurred along a persistent spatial node, whose distance from the shoreline scales with the computed backwater length. In order to explain the avulsion locations on the delta, and meanwhile to test the viewpoint of river backwater controls on avulsion locations on deltas, we simulate the long profile evolution of the riverbed on the delta considering river discharge, river plume spreading, land subsidence and sea level rise, with a 1D fluvial morphodynamic model. The main results from the numerical simulations provide insights into how the long profile of the river on the delta evolves at the time scales of flood events and avulsions.

  9. Contribution of geoelectrical resistivity sounding for paleoenvironment assessment at Saft El-Henna and Tell El-Dab'a archaeological sites, eastern Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    El-Kenawy, Abeer 1Metwaly, Mohamed 2345Gemail, Khalid 1El-Raouf, Amr Abd

    2013-09-01

    Vertical electrical sounding (VES), a resistivity sounding technique, has been applied at two important archaeological sites in the eastern part of the Nile Delta to trace the paleoenvironment, particularly the defunct canals. Like many other archaeological sites in the Nile Delta of Egypt, these two sites have been subjected to urbanisation and agricultural invasion from the local farmers. Therefore, studying the paleoenvironment is an important task for guiding the excavation process and highlighting the importance of these two archaeological sites. The VES stations were arranged to cover the two sites, in the form of traverse profiles for tracing the subsurface sand and gravel facies that intercalated with clay deposits. The acquired VES data were processed based on the available borehole lithological information for the purpose of establishing the resistivity-depth models. Both 1D and 2D processing schemes were applied to the VES data sets to increase the confidence of the obtained results. The clay and silt deposits are characterised by low resistivity values, whereas the sand facies has a relatively high resistivity character. From the constructed cross-sections at the two sites, it was possible to define a consistent character for the clay deposits, which can be inferred as the defunct canals that supplied water to the two sites.

  10. An application of remotely derived climatological fields for risk assessment of vector-borne diseases : a spatial study of filariasis prevalence in the Nile Delta, Egypt.

    SciTech Connect

    Crombie, M. K.; Gillies, R. R.; Arvidson, R. E.; Brookmeyer, P.; Weil, G. J.; Sultan, M.; Harb, M.; Environmental Research; Washington Univ.; Utah State Univ.; Egyptian Ministry of Health

    1999-12-01

    This paper applies a relatively straightforward remote sensing method that is commonly used to derive climatological variables. Measurements of surface reflectance and surface radiant temperature derived from Landsat Thematic Mapper data were used to create maps of fractional vegetation and surface soil moisture availability for the southern Nile delta in Egypt. These climatological variables were subsequently used to investigate the spatial distribution of the vector borne disease Bancroftian filariasis in the Nile delta where it is focally endemic and a growing problem. Averaged surface soil moisture values, computed for a 5-km border area around affected villages, were compared to filariasis prevalence rates. Prevalence rates were found to be negligible below a critical soil moisture value of 0.2, presumably because of a lack of appropriate breeding sites for the Culex Pipiens mosquito species. With appropriate modifications to account for local conditions and vector species, this approach should be useful as a means to map, predict, and control insect vector-borne diseases that critically depend on wet areas for propagation. This type of analysis may help governments and health agencies that are involved in filariasis control to better focus limited resources to identifiable high-risk areas.

  11. Surveillance of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in Dairy Cattle Farms in the Nile Delta, Egypt

    PubMed Central

    Braun, Sascha D.; Ahmed, Marwa F. E.; El-Adawy, Hosny; Hotzel, Helmut; Engelmann, Ines; Weiß, Daniel; Monecke, Stefan; Ehricht, Ralf

    2016-01-01

    Introduction: Industrial livestock farming is a possible source of multi-resistant Gram-negative bacteria, including producers of extended spectrum beta-lactamases (ESBLs) conferring resistance to 3rd generation cephalosporins. Limited information is currently available on the situation of ESBL producers in livestock farming outside of Western Europe. A surveillance study was conducted from January to May in 2014 in four dairy cattle farms in different areas of the Nile delta, Egypt. Materials and Methods: In total, 266 samples were collected from 4 dairy farms including rectal swabs from clinically healthy cattle (n = 210), and environmental samples from the stalls (n = 56). After 24 h pre-enrichment in buffered peptone water, all samples were screened for 3rd generation cephalosporin-resistant Escherichia coli using Brilliance™ ESBL agar. Suspected colonies of putatively ESBL-producing E. coli were sub-cultured and subsequently genotypically and phenotypically characterized. Susceptibility testing using the VITEK-2 system was performed. All suspect isolates were genotypically analyzed using two DNA-microarray based assays: CarbDetect AS-1 and E. coli PanType AS-2 kit (ALERE). These tests allow detection of a multitude of genes and their alleles associated with resistance toward carbapenems, cephalosporins, and other frequently used antibiotics. Serotypes were determined using the E. coli SeroGenotyping AS-1 kit (ALERE). Results: Out of 266 samples tested, 114 (42.8%) ESBL-producing E. coli were geno- and phenotypically identified. 113 of 114 phenotypically 3rd generation cephalosporin-resistant isolates harbored at least one of the ESBL resistance genes covered by the applied assays [blaCTX-M15 (n = 105), blaCTX-M9 (n = 1), blaTEM (n = 90), blaSHV (n = 1)]. Alarmingly, the carbapenemase genes blaOXA-48 (n = 5) and blaOXA-181 (n = 1) were found in isolates that also were phenotypically resistant to imipenem and meropenem. Using the array-based serogenotyping

  12. Groundwater quality assessment of the shallow aquifers west of the Nile Delta (Egypt) using multivariate statistical and geostatistical techniques

    NASA Astrophysics Data System (ADS)

    Masoud, Alaa A.

    2014-07-01

    Extensive urban, agricultural and industrial expansions on the western fringe of the Nile Delta of Egypt have exerted much load on the water needs and lead to groundwater quality deterioration. Documenting the spatial variation of the groundwater quality and their controlling factors is vital to ensure sustainable water management and safe use. A comprehensive dataset of 451 shallow groundwater samples were collected in 2011 and 2012. On-site field measurements of the total dissolved solids (TDS), electric conductivity (EC), pH, temperature, as well as lab-based ionic composition of the major and trace components were performed. Groundwater types were derived and the suitability for irrigation use was evaluated. Multivariate statistical techniques of factor analysis and K-means clustering were integrated with the geostatistical semi-variogram modeling for evaluating the spatial hydrochemical variations and the driving factors as well as for hydrochemical pattern recognition. Most hydrochemical parameters showed very wide ranges; TDS (201-24,400 mg/l), pH (6.72-8.65), Na+ (28.30-7774 mg/l), and Cl- (7-12,186 mg/l) suggesting complex hydrochemical processes of multiple sources. TDS violated the limit (1200 mg/l) of the Egyptian standards for drinking water quality in many localities. Extreme concentrations of Fe2+, Mn2+, Zn2+, Cu2+, Ni2+, are mostly related to their natural content in the water-bearing sediments and/or to contamination from industrial leakage. Very high nitrate concentrations exceeding the permissible limit (50 mg/l) were potentially maximized toward hydrologic discharge zones and related to wastewater leakage. Three main water types; NaCl (29%), Na2SO4 (26%), and NaHCO3 (20%), formed 75% of the groundwater dominated in the saline depressions, sloping sides of the coastal ridges of the depressions, and in the cultivated/newly reclaimed lands intensely covered by irrigation canals, respectively. Water suitability for irrigation use clarified that the

  13. 78 FR 39314 - Notice of Availability of the Decision Record for the Delta River Special Recreation Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-01

    ... Bureau of Land Management Notice of Availability of the Decision Record for the Delta River Special... the availability of the Decision Record (DR) for the Delta River Special Recreation Management Area... Assessment (EA) for the Delta River Special Recreation Management Area (SRMA) Plan and East Alaska...

  14. Reliability characteristics of a platform in the Mississippi River delta

    SciTech Connect

    Bea, R.G.

    1998-08-01

    In August 1995, the Energy Development Corporation installed a conventional drilling and production platform in South Pass Block 47. Due to its proximity to the delta of the Mississippi River, this platform is exposed to the environmental forces developed by hurricanes and movements of the seafloor. This paper summarizes results from probability-based study of the oceanographic, geotechnical, and structural reliability characteristics of a conventional platform installed in South Pass Block 47. Experience with other structures installed in this area that have failed due to seafloor slides is correlated with results from these analyses. The analyses indicated that a conventional platform could be safely installed at the proposed location. The platform has experienced several severe hurricanes without signs of distress.

  15. Microbial communities of alluvial soils in the Volga River delta

    NASA Astrophysics Data System (ADS)

    Sal'Nikova, N. A.; Polyanskaya, L. M.; Tyugai, Z. N.; Sal'Nikov, A. N.; Egorov, M. A.

    2009-01-01

    The number and biomass of the microbial community in the upper humus horizon (0-20 cm) were determined in the main types of alluvial soils (mucky gley, desertified soddy calcareous, hydrometamorphic dark-humus soils) in the Volga River delta. Fungal mycelium and alga cells predominate in the biomass of the microorganisms (35-50% and 30-47%, respectively). The proportion of prokaryotes in the microbial biomass of the alluvial soils amounts to 2-6%. No significant seasonal dynamics in the number and biomass of microorganisms were revealed in the alluvial soils. The share of carbon of the microbial biomass in the total carbon content of the soil organic matter is 1.4-2.3% in the spring. High coefficients of microbial mineralization and oligotrophy characterize the processes of organic matter decomposition in the alluvial soils of the mucky gley, desertified soddy calcareous, and hydrometamorphic dark humus soil types.

  16. Water management in the Senegal River Delta: a continuing uncertainty

    NASA Astrophysics Data System (ADS)

    Mietton, M.; Dumas, D.; Hamerlynck, O.; Kane, A.; Coly, A.; Duvail, S.; Pesneaud, F.; Baba, M. L. O.

    2007-11-01

    Water management is the driving force behind the productivity of the ecosystems of the Senegal River Estuary and floodplains. It is dependent on human decision-making, but has been separated from the River's flooding since the building of the Diama Dam. The current objectives of the Office de Mise en Valeur du fleuve Sénégal (OMVS: Senegal River Development Agency) are mainly turned towards the development of irrigated agriculture on the former floodplains and since 2002 the production of hydroelectric power at Manantali. In October 2003, a four-metre-wide runoff canal, which quickly widened into a breach several hundred metres across, was dug in the Barbary Spit area to protect the city of Saint-Louis from heavy flooding. The hydraulic quality of the area downstream from the dam has improved to the extent that there is no longer any flooding there, but as the management of the dams concerns only the section of the river between Manantali and Diama, a certain amount of flood risk probably still persists. The intrusion of seawater into the estuary is also threatening ecosystems and fresh water supplies, and abruptly altering agricultural practices such as fruit and vegetable growing in the Gandiolais district. When added to the tentative efforts to coordinate the management of the two dams, with no management objective downstream from Diama, such permanent modifications impose serious constraints on the managers and residents of the lower delta. This paper presents an overview of the constraints and uncertainties at different levels and scales. This wholly human-wrought environment can be considered as a learning experience, where a large number of variables need to be monitored closely and an ongoing process of participatory analysis should be backed up by multidisciplinary research.

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

    PubMed

    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.

  18. Natural and Human Impacts on Recent Development of Asian Large Rivers and Deltas

    NASA Astrophysics Data System (ADS)

    Liu, P.; Lu, C.

    2014-12-01

    Most recent data analysis indicates sediment loads in most of Asian large rivers (like, Yellow, Yangtze, Pearl, Chao Phraya, Indus, Krishna, Godavari, etc) have decreased up to 80-90% in the past 60 years. Correspondingly, most of Asian large river deltas are facing severe sediment starving; delta shoreline comparisons indicate that some are under strong coastal erosion. For examples, the Yellow River Delta has been retreating since 1990s when its annual sediment load has kept below 300 million tons. The Yangtze River delta kept growing before Three Gorges Dams was operating, and began to be eroded from the year 2003 to 2009, and then prograded locally due to the Deep Water Navigation Project. The Mekong Delta shoreline has also been dynamically changing with the sediment flux variation, eroding from 1989 to 1996 and prograding from 1996 to 2002. More information is available at http://www.meas.ncsu.edu/sealevel

  19. Phenotypic and molecular characteristics of an Aeromonas hydrophila strain isolated from the River Nile.

    PubMed

    Furmanek-Blaszk, Beata

    2014-01-01

    Aeromonas hydrophila, an inhabitant of aquatic ecosystems found in most parts of the world, has considerable virulence potential. The polymerase chain reaction technique was used to assay for the presence of five virulence factor genes: haemolytic toxins aerA and ahh1, elastase ahyB, the enterotoxin act, and the polar flagella flaA/flaB in the A. hydrophila strain isolated from the River Nile. Drug screening showed high levels of resistance to β-lactam antibiotics and tetracycline. Slime production was determined by the Congo red agar plate test. The isolate produced two restriction enzymes named AehI and AehII which are isoschizomers of XhoI and StuI respectively. The complete nucleotide sequence of the cryptic plasmid pAhy2.5 (2524 bp) from this strain was determined. Sequence analysis revealed the presence of two open reading frames (ORFs) encoding putative proteins. The protein coded by ORF1 is homologous with Rep proteins of plasmids belonging to the pC194 family, which are known to replicate by the rolling-circle mechanism. The putative double-strand origin of replication and a region with palindromic sequences that could function as a single-strand origin were detected in pAhy2.5.

  20. Integrating Delta Building Physics & Economics: Optimizing the Scale of Engineered Avulsions in the Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Kenney, M. A.; Mohrig, D.; Hobbs, B. F.; Parker, G.

    2011-12-01

    Land loss in the Mississippi River Delta caused by subsidence and erosion has resulted in habitat loss, interference with human activities, and increased exposure of New Orleans and other settled areas to storm surge risks. Prior to dam and levee building and oil and gas production in the 20th century, the long term rates of land building roughly balanced land loss through subsidence. Now, however, sediment is being deposited at dramatically lower rates in shallow areas in and adjacent to the Delta, with much of the remaining sediment borne by the Mississippi being lost to the deep areas of the Gulf of Mexico. A few projects have been built in order to divert sediment from the river to areas where land can be built, and many more are under consideration as part of State of Louisiana and Federal planning processes. Most are small scale, although there have been some proposals for large engineered avulsions that would divert a significant fraction of the remaining available sediment (W. Kim, et al. 2009, EOS). However, there is debate over whether small or large diversions are the economically optimally and socially most acceptable size of such land building projects. From an economic point of view, the optimal size involves tradeoffs between scale economies in civil work construction, the relationship between depth of diversion and sediment concentration in river water, effects on navigation, and possible diminishing returns to land building at a single location as the edge of built land progresses into deeper waters. Because land building efforts could potentially involve billions of dollars of investment, it is important to gain as much benefit as possible from those expenditures. We present the result of a general analysis of scale economies in land building from engineered avulsions. The analysis addresses the question: how many projects of what size should be built at what time in order to maximize the amount of land built by a particular time? The analysis

  1. Holocene Floods and Sediment Sources in the Desert Nile: a Strontium Isotope Record from Northern Sudan

    NASA Astrophysics Data System (ADS)

    Woodward, Jamie; Macklin, Mark; Millar, Ian; Williams, Martin; Welsby, Derek; Duller, Geoff; Williams, Frances

    2014-05-01

    Strontium isotope ratios can be used to explore changes in Nile sediment sources and flood regime because the Blue Nile/Atbara and White Nile headwater catchments lie in markedly contrasting geological settings. Most of the existing Sr isotope data for the Holocene Nile has been obtained from lagoonal/lacustrine environments rather than directly from the fluvial sediments of the desert Nile. Northern Sudan contains some of the best preserved Holocene river deposits and landforms in the desert Nile. Using Optically Stimulated Luminescence (OSL) and radiocarbon dating, we have compiled a detailed record of Holocene river history in the Northern Dongola Reach (NDR) that spans the last c. 8500 years. This period includes major changes in global climate and Nile hydrological regime. In the palaeochannel fills and floodplain deposits of the NDR, we have sampled sedimentary units that represent discrete flood events. We have measured Sr and Nd isotopes on the fine-grained fraction of dated alluvial units. The Sr isotope signature of the NDR fluvial sediments is discussed and compared to published datasets for the Nile delta.

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

    NASA Astrophysics Data System (ADS)

    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

  3. The Potential of Time Series Based Earth Observation for the Monitoring of Large River Deltas

    NASA Astrophysics Data System (ADS)

    Kuenzer, C.; Leinenkugel, P.; Huth, J.; Ottinger, M.; Renaud, F.; Foufoula-Georgiou, E.; Vo Khac, T.; Trinh Thi, L.; Dech, S.; Koch, P.; Le Tissier, M.

    2015-12-01

    Although river deltas only contribute 5% to the overall land surface, nearly six hundred million people live in these complex social-ecological environments, which combine a variety of appealing locational advantages. In many countries deltas provide the major national contribution to agricultural and industrial production. At the same time these already very dynamic environments are exposed to a variety of threats, including the disturbance and replacement of valuable ecosystems, increasing water, soil, and air pollution, human induced land subsidence, sea level rise, as well upstream developments impacting water and sediment supplies. A constant monitoring of delta systems is thus of utmost relevance for understanding past and current land surface change and anticipating possible future developments. We present the potential of Earth Observation based analyses and derived novel information products that can play a key role in this context. Along with the current trend of opening up numerous satellite data archives go increasing capabilities to explore big data. Whereas in past decades remote sensing data were analysed based on the spectral-reflectance-defined 'finger print' of individual surfaces, we mainly exploit the 'temporal fingerprints' of our land surface in novel pathways of data analyses at differing spatial-, and temporally-dense scales. Following our results on an Earth Observation based characterization of large deltas globally, we present in depth results from the Mekong Delta in Vietnam, the Yellow River Delta in China, the Niger Delta in Nigeria, as well as additional deltas, focussing on the assessment of river delta flood and inundation dynamics, river delta coastline dynamics, delta morphology dynamics including the quantification of erosion and accretion processes, river delta land use change and trends, as well as the monitoring of compliance to environmental regulations.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27386534

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

    PubMed

    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.

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

    PubMed

    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. PMID:27386534

  7. Barrier island arcs along abandoned Mississippi River deltas

    USGS Publications Warehouse

    Penland, S.; Suter, J.R.; Boyd, Ron

    1985-01-01

    Generation of transgressive barrier island arcs along the Mississippi River delta plain and preservation of barrier shoreline facies in their retreat paths on the inner shelf is controlled by: (1) shoreface translation; (2) age of the transgression; and (3) the thickness of the barrier island arc sediment package. Barrier island arcs experience an average relative sea level rise of 0.50-1.00 cm yr-1 and shoreface retreat rates range from 5-15 m yr-1. Young barrier island arc sediment packages (Isles Dernieres) are thin and have experienced limited landward retreat of the shoreface. Older barrier island arcs (Chandeleur Islands) are thicker and have experienced significant landward movement of the shoreface because of the greater time available for retreat. If the transgressed barrier shoreline sediment package lies above the advancing ravinement surface, the entire sequence is truncated. A thin reworked sand sheet marks the shoreface retreat path. The base of the transgressive sediment package can lie below the ravinement surface in older barrier shorelines. In this setting, the superstructure of the barrier shoreline is truncated, leaving the basal portion of the transgressive sequence preserved on the inner shelf. A variety of transgressive stratigraphic sequences from sand sheets to truncated barrier islands to sand-filled tidal inlet scars have been identified by high resolution seismic profiling across the shoreface retreat paths of Mississippi delta barrier island arcs. One of these examples, the Isles Dernieres, represents a recently detached barrier island arc in the early stages of transgression. An older example, the Chandeleur Islands, represents a barrier island arc experiencing long-term shoreface retreat. This paper describes the stratigraphic character and preserved transgressive facies for the Isles Dernieres and Chandeleur Islands. ?? 1985.

  8. The Selenga River delta - a geochemical barrier for the waters of Lake Baikal

    NASA Astrophysics Data System (ADS)

    Chalov, Sergey; Thorslund, Josefin; Pietron, Jan; Jarsjö, Jerker

    2016-04-01

    Delta systems play an important role in retention of sediments and contaminants to downstream recipients, through processes such as gravitational sedimentation, flocculation and biofiltration. The Selenga river delta is one of the world's largest inland deltas, providing a huge buffer zone between Lake Baikal and upstream waters of the Selenga river basin. Understanding the delta functioning is critical for the planning of water management measures in the Selenga River Basin and for protection of the waters of Lake Baikal. We here study the current state and functioning of the delta's ecosystem and hydrogeochemical processes. More specifically, we considered spatio-temporal changes in water flow, morphology and transport of sediments and metals within the delta and what potential impacts these changes may have on the delta functions. Results show that the delta network has a large influence on the mass of metals reaching the Lake Baikal at the delta outlet. Regions with high density of wetlands and small channels, in contrast to main channel regions, show a consistent pattern of considerable contaminant filtering and removal (between 77-99% for key metals), during both high and low flow conditions, following with a significant increase (2-3 times) of bottom sediment pollution. Geomorphological processes also governs the barrier function of the delta, due to partitioning of flow between different channel systems. These results are particularly relevant in the light of recent and expected future changes involving both the hydrology and water quality in the Lake Baikal basin. Taken together, this emphasizes the importance of understanding the interface between flow partitioning, delta morphology, and sediment and metal patterns and storage rates for fully capturing and quantifying the variety in delta functions. This is particularly relevant coupled to hydroclimatic changes in the region, which could lead to significant decline in barrier functions of the delta due to

  9. Seasonal variation and enrichment of metals in sediments of Rosetta branch, Nile River, Egypt.

    PubMed

    Redwan, Mostafa; Elhaddad, Engy

    2016-06-01

    This study investigated heavy metal pollution in sediments of the Rosetta branch of the River Nile of Egypt to quantify the toxic distribution potential of metals into the surrounding environment. Sediment samples were collected at 9 sites during in four seasons. Organic matter and total metal concentrations were determined using loss on ignition and inductively coupled plasma spectrometry, respectively. Principal component analysis has been applied to evaluate the metal sources and the relationships between metals in sediments. Metal concentrations showed the following order: winter > autumn > spring > summer. Mean concentrations of Cu, Zn, Cd, and Pb in sediments were above the average background value of metals in shale. Pb and Cd showed higher enrichment during all seasons at stations N3/N4, Zn at stations N1 to N4, and Cu at stations N6/N8. The variations in heavy metal total concentration and organic matter are due to different input sources, physico-chemical conditions, and adsorption/precipitation/redox conditions in sediments. Mean values of Geo-accumulation index (Igeo) for Fe, Mn, and Cu were below 0 which were classified as unpolluted during spring, summer, and autumn, except Cu increased from unpolluted to moderately polluted during winter. Igeo values for Cd, Pb, and Zn increased from unpolluted-moderately polluted to highly-very highly polluted during autumn and winter. Pollution Load Index was recorded in highest values during winter, especially at Fuwwah/Basioun and in lowest values during summer at after the Edfina Barrage/before Kafer El-Zayat due to industrial/human activities. Both natural and anthropogenic sources contributed to the metal accumulations in sediments, and industrial, agricultural, and municipal sewage effluents discharged from non-point sources may be the main anthropogenic sources for metals in the Rosetta branch. PMID:27194230

  10. Plant community succession in modern Yellow River Delta, China*

    PubMed Central

    Zhang, Gao-sheng; Wang, Ren-qing; Song, Bai-min

    2007-01-01

    Data were collected in different successional stages using a simultaneous sampling method and analyzed through quantitative classification method. Three large groups and 12 classes were made to represent the community patterns of three succession stages and 12 succession communities. The succession series of plant community in the study area was as follows: saline bare land→community Suaeda salsa→community Tamarix chinensis→grassland. Succession degree and succession process of 12 succession communities were calculated. Most of these communities were in the lower succession stage, however, community Phragmites communis+Glycine soja and community Imperata cylindrica+G. soja were close to the succession stage of grassland climax. Five species diversity indices were used to study the changes in species richness, species evenness and diversity during succession of community. Heterogeneity index and richness index increased gradually during the community succession process, but species evenness tended to decrease with succession development. The relation between succession and environment was studied by ordination technique, and the results showed that the soil salt content was an important factor to halarch succession of the modern Yellow River Delta. It affected community structure, species composition and succession process. PMID:17657854

  11. Latest Quaternary stratigraphic framework of the Mississippi River delta region

    USGS Publications Warehouse

    Kulp, Mark; Howell, Paul; Adiau, Sandra; Penland, Shea; Kindinger, Jack; Williams, S. Jeffress

    2002-01-01

    Previous researchers separated the uppermost Quaternary stratigraphy of the Mississippi River delta region into two major lithofacies. The stratigraphically lower of these, "substratum," primarily consists of coarse-grained sediment deposited within lowstand-incised stream valleys. Relatively finer-grained "topstratum" overlies substratum; above interfluves, topstratum directly overlies weathered late Pleistocene sediments. However, the onshore to offshore distribution and architecture of these lithofacies was not well constrained. This study integrates published and unpublished lithostratigraphic data with high-resolution seismic profiles from the continental shelf to aid in mapping the regional distribution of major substratum deposits and thickness of topstratum sediments. A transgressive sand sheet commonly marks the base of the topstratum deposits, providing a stratigraphic marker to aid in regional lithostratigraphic correlations. Radiocarbondated deposits and boreholes tied to oxygen isotope chronologies provide chronostratigraphic control. Excellent correlation between these multiple datasets has been found to exist, enabling construction of regional isopachous and structural elevation maps and cross sections detailing elements of the Late Quaternary stratigraphy.

  12. [Numerical simulation study of SOA in Pearl River Delta region].

    PubMed

    Cheng, Yan-li; Li, Tian-tian; Bai, Yu-hua; Li, Jin-long; Liu, Zhao-rong; Wang, Xue-song

    2009-12-01

    Secondary organic aerosols (SOA) is an important component of the atmospheric particle pollution, thus, determining the status and sources of SOA pollution is the premise of deeply understanding the occurrence, development law and the influence factors of the atmospheric particle pollution. Based on the pollution sources and meteorological data of Pearl River Delta region, the study used the two-dimensional model coupled with SOA module to stimulate the status and source of SOA pollution in regional scale. The results show: the generation of SOA presents obvious characteristics of photochemical reaction, and the high concentration appears at about 14:00; SOA concentration is high in some areas of Guangshou and Dongguan with large pollution source-emission, and it is also high in some areas of Zhongshan, Zhuhai and Jiangmen which are at downwind position of Guangzhou and Dongguan. Contribution ratios of several main pollution sources to SOA are: biogenic sources 72.6%, mobile sources 30.7%, point sources 12%, solvent and oil paint sources 12%, surface sources less than 5% respectively. PMID:20187369

  13. First phenotypic description of Fasciola hepatica/Fasciola gigantica intermediate forms from the human endemic area of the Nile Delta, Egypt.

    PubMed

    Periago, M V; Valero, M A; El Sayed, M; Ashrafi, K; El Wakeel, A; Mohamed, M Y; Desquesnes, M; Curtale, F; Mas-Coma, S

    2008-01-01

    Fasciola gigantica is the main fasciolid species in Africa; however, F. hepatica and F. gigantica overlap in some countries. Egypt deserves mentioning because of the emerging situation of human fascioliasis in the Nile Delta area. The morphometric characteristics of fasciolid adults infecting the main livestock species present in the Nile Delta human endemic area are analyzed through a computer image analysis system (CIAS) on the basis of standardized measurements known to be useful for the differentiation of both fasciolid species. This is the first time that such a study is performed in an African country and, therefore, the results are compared to (i) F. hepatica (European Mediterranean area) and F. gigantica (Burkina Faso) standard populations, i.e. geographical areas where both species do not co-exist, and (ii) F. hepatica and F. gigantica populations from geographical areas where both species do co-exist, including the presence of intermediate forms (Iran). Results indicate the presence of F. hepatica, F. gigantica and intermediate forms (Fasciola sp.) in Egypt for the first time, and demonstrate the usefulness of CIAS for the phenotypic characterization of liver fluke adults from a concrete fascioliasis endemic area. Body roundness, body length over body width, and distance between the ventral sucker and the posterior end of the body provide useful tools for studying inter- and intraspecific morphological diversity in Fasciola adults. The application of these markers to specimens from geographical areas where F. hepatica and F. gigantica co-exist, such as in Egypt and Iran, suggest a strong population-level variation in Fasciola adult morphology. PMID:18006385

  14. Sediment and water chemistry of the San Juan River and Escalante River deltas of Lake Powell, Utah, 2010-2011

    USGS Publications Warehouse

    Hornewer, Nancy J.

    2014-01-01

    Recent studies have documented the presence of trace elements, organic compounds including polycyclic aromatic hydrocarbons, and radionuclides in sediment from the Colorado River delta and from sediment in some side canyons in Lake Powell, Utah and Arizona. The fate of many of these contaminants is of significant concern to the resource managers of the National Park Service Glen Canyon National Recreation Area because of potential health impacts to humans and aquatic and terrestrial species. In 2010, the U.S. Geological Survey began a sediment-core sampling and analysis program in the San Juan River and Escalante River deltas in Lake Powell, Utah, to help the National Park Service further document the presence or absence of contaminants in deltaic sediment. Three sediment cores were collected from the San Juan River delta in August 2010 and three sediment cores and an additional replicate core were collected from the Escalante River delta in September 2011. Sediment from the cores was subsampled and composited for analysis of major and trace elements. Fifty-five major and trace elements were analyzed in 116 subsamples and 7 composited samples for the San Juan River delta cores, and in 75 subsamples and 9 composited samples for the Escalante River delta cores. Six composited sediment samples from the San Juan River delta cores and eight from the Escalante River delta cores also were analyzed for 55 low-level organochlorine pesticides and polychlorinated biphenyls, 61 polycyclic aromatic hydrocarbon compounds, gross alpha and gross beta radionuclides, and sediment-particle size. Additionally, water samples were collected from the sediment-water interface overlying each of the three cores collected from the San Juan River and Escalante River deltas. Each water sample was analyzed for 57 major and trace elements. Most of the major and trace elements analyzed were detected at concentrations greater than reporting levels for the sediment-core subsamples and composited

  15. The sediment-starved Yellow River Delta as remotely controlled by human activities in the river basin

    NASA Astrophysics Data System (ADS)

    Wang, H.; Bi, N.

    2015-12-01

    Human presented significant disturbances on the natural processes of land-ocean interactions in context of global change. Here we illustrate how the signals of human activities in the river basin have been transferred to the coastal ocean along the hydrological pathway and remotely controlled the Yellow River Delta. Dam-orientated water and sediment regulation scheme (WSRS) has resulted in effective erosion of the lower channel and mitigation of siltation within the reservoirs. However, significant impacts have been identified on the delta morphology and coastal ecosystem ten years after the WSRS, which was unexpected at the beginning of engineering efforts. The coarser sediment derived from the channel erosion during the first phase of WSRS was directly contributed to the rapid accretion of present river mouth, whereas the delta was starved and declined due to insufficient sediment supply and regime shift of sediment transport. The fine-grained sediment exported from the Xiaolangdi Reservoir during the second phase of WSRS seemed to be a critical carrier for the nutrients and pollutants. The human-altered hydrological cycle, enhanced delivery of nutrient and pollutants and the changing estuarine environment present unpredictable impacts on both terrestrial and aquatic ecosystem in the delta region. These confirm that humans are modifying the river-coast system in ways that go well beyond climate change, and an integrated management of the river-coast continuum is crucially important for the sustainability of the river-delta system.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. A new record of Myxobolus brachysporus and M. israelensis in the tilapia (Oreochromis niloticus) collected from the Nile River, Egypt

    PubMed Central

    Abdel-Baki, Abdel-Azeem S.; Zayed, Eman; Sakran, Thabet; Al-Quraishy, Saleh

    2015-01-01

    The present study was carried out as part of an ongoing general survey for myxosporean parasites infecting tilapias in the River Nile, Egypt. In the present study, 77 Nile tilapia (Oreochromis niloticus) were collected from boat landing sites at Beni-Suef governorate, Egypt and examined for the myxosporean infection. The infection was encountered as a huge number of free spores in the kidney and the spleen. The infection showed a prevalence of 51.9% (40/77) for Myxobolus brachysporus while it was 25.9% (20/77) for Myxobolus israelensis. Mature spores of M. brachysporus were ellipsoidal and measured 8.6 × 13.2 μm. The polar capsules were subcircular with 5–6 filament turns and measured 4.7 × 3.6 μm. Spores of M. israelensis were ellipsoidal in the frontal view and fusiform in the lateral view. Spore measurements were 13.4 μm long and 8.7 μm wide. The polar capsules were elongated with 6–7 filament coils and measured 8.6 × 3.1 μm. The findings presented here proved that tilapia fishes in the Nile River are still suffering from infections with Myxobolus species. Therefore, further studies should be carried out to survey the Myxobolus infection among tilapias under culture conditions to clarify the pathological impacts of this parasite in tilapias aquaculture. PMID:26286347

  18. Morphology and Sediment Transport Dynamics of the Selenga River Delta, Lake Baikal, Russia

    NASA Astrophysics Data System (ADS)

    Dong, T. Y.; Il'icheva, L.; Nittrouer, J. A.; Pavolv, M.

    2013-12-01

    The Selenga River fan delta is a lacustrine system located in southeastern Siberia, Russia, where Selenga River flows into Lake Baikal. The Selenga River is the largest source of sediment and water entering Lake Baikal. Covering ~550 km2, the Selenga delta is one of the largest freshwater deltas in the world. Evaluating the Selenga delta and its morphology is very important for local residents who rely upon the delta for both ecological and agricultural welfare. However, a sediment budget remains poorly constrained, as do estimates for the partitioning of water and sediment amongst the numerous bifurcating delta channels. This information is critical for addressing how the delta morphology evolves and influences the stratigraphic composition of the delta. To investigate the morphological characteristics of the delta, a field expedition was undertaken during July 2013 in collaboration with Russian scientists. The overall goal of the field work was to constrain delta dynamics through data collection. Field measurements included single-beam bathymetry data and sidescan sonar data to characterize: 1) channel geometries of the delta; 2) bedform sizes and distribution; and 3) grain-size composition of the channel bed. Flow velocity measurements were collected within the bifurcating channels to measure water discharge. Bedload samples were obtained within the active distributary channels to measure downstream sediment fining. Additionally, channel island cores were collected in order to analyze the internal architecture of the delta. The data reveal a systematic downstream sediment fining, from a predominantly gravel bed near the delta apex, to a fine-sand bed at the delta-lake interface (~40 km total distance). Bathymetry data document how width-to-depth ratios systematically decrease downstream in association with increasing channel bifurcations and decreasing channel-bed grain size. Furthermore, the investigations reveal that the delta is actively terraced, with the

  19. 3D Depositional Model in a Complex Incised Valley Fill: An Example from the Late Messinian Abu Madi Formation, Nile Delta Basin, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El-Deen Badawy, A. M. E. S.

    2015-12-01

    The study area lies in the Central Marine Delta, which is located in the Baltim offshore concession, about 25 kms from the shoreline and 40 kms North Abu Madi-El Qara fields. The current study is aiming to give a comprehensive combined and conjugated study between well data and seismic survey interpretations. The former includes well logging data, acquired results of actual drilling and biostratigraphic study, to give an integrated picture for the considered area in a true attempt to visualize the geological and geophysical data given from both wells and seismic reflection surveys, and hence introduce an updated sequence stratigraphic framework for the Messinian sequence at the offshore Nile Delta area. The 3D geological model, based on all the available well data (faunal contents, litho-facies, log signatures…...etc.) and the seismic expressions (facies and geometry), has been constructed for the study area. This model shows that, the study area was changed from shelf (considered as erosional), to delta channels and then directed to the north. It changed to delta front mouth bars on the shoreface and affected by the main Rosetta fault to collect deposits as sand bars in the southern part on the downthrown side of the fault. Most deposits on this face were highstand system tracts. This deduced from the sequence stratigraphy study. The area was then sloped to the north, as shelf slope with the deposition of slumps, which was formed during erosions and mass flows. Some mud diapers also formed upon this slope. After dropping the sea level with the activity of some syn-sedimentary faults, some channels with sediment supply started their activities to dig their ways to the north.

  20. Network topology, Transport dynamics, and Vulnerability Analysis in River Deltas: A Graph-Theoretic Approach

    NASA Astrophysics Data System (ADS)

    Tejedor, A.; Foufoula-Georgiou, E.; Longjas, A.; Zaliapin, I. V.

    2014-12-01

    River deltas are intricate landscapes with complex channel networks that self-organize to deliver water, sediment, and nutrients from the apex to the delta top and eventually to the coastal zone. The natural balance of material and energy fluxes which maintains a stable hydrologic, geomorphologic, and ecological state of a river delta, is often disrupted by external factors causing topological and dynamical changes in the delta structure and function. A formal quantitative framework for studying river delta topology and transport dynamics and their response to change is lacking. Here we present such a framework based on spectral graph theory and demonstrate its value in quantifying the complexity of the delta network topology, computing its steady state fluxes, and identifying upstream (contributing) and downstream (nourishment) areas from any point in the network. We use this framework to construct vulnerability maps that quantify the relative change of sediment and water delivery to the shoreline outlets in response to possible perturbations in hundreds of upstream links. This enables us to evaluate which links (hotspots) and what management scenarios would most influence flux delivery to the outlets, paving the way of systematically examining how local or spatially distributed delta interventions can be studied within a systems approach for delta sustainability.

  1. The Challenges and Opportunities of Hydrologic Remote Sensing in Data-Poor Regions: Case Study of Nile River Basin

    NASA Astrophysics Data System (ADS)

    Hasan, E.; Kirstetter, P.; Zhang, K.; Hong, Y.

    2015-12-01

    The Nile River Basin (NRB) is one of the largest trans-boundary watercourses; it is the lifeline for more than 300 million people belonging to 11 African nations sharing the NRB. The riparian countries are challenged by their infirm relationships, lack of information sharing and insufficient monitoring stations. Thus, to understand the water future along the NRB under the changing climate, reliable, and sufficient information are needed. This to assess and understand: whether will be more rainfall and induced flooding events, or the drought conditions with less surface runoff will be dominant over the Nile Basin? In addition, to what extent the available remote sensing and model reanalysis data can substitute the lack of detailed ground information, and help to determine the size and risk associated to the climatic impact on the Nile Basin? In the current study, we utilizing multi-scale remote sensing, and model reanalysis datasets for hydrologic monitoring along the NRB in Africa. The list of remote sensing, and model reanalysis datasets that implemented: several MODIS satellite products such as the NDVI, LAI, LST, and LULC datasets. Three GRACE satellite derivative products: TWS, EWT, and DTWS, and TRMM satellite precipitation product. In addition to number of model reanalysis datasets including Global Precipitation Climatological Center (GPCC) datasets, Global Land Data Assimilation System (GLDAS) products, Climate Research Unit (CRU) datasets, Physical Science Division (PSD) gridded climate dataset, and in situ Global Runoff Data Centre (GRDC) datasets. The main objective of our research is to monitor the hydrological changes and the variation in water balance along the NRB. The study approach accomplished through: (1) developing a distributed storage changes based grid, (2) trend analysis and inter-annual variability shift detections using regime shift analysis, (3) define the water stress and water deficit periods along the Nile Basins, (4) applying multi

  2. Morphologic and stratigraphic evolution of muddy ebb-tidal deltas along a subsiding coast: Barataria Bay, Mississippi River delta

    USGS Publications Warehouse

    FitzGerald, D.M.; Kulp, M.; Penland, S.; Flocks, J.; Kindinger, J.

    2004-01-01

    The Barataria barrier coast formed between two major distributaries of the Mississippi River delta: the Plaquemines deltaic headland to the east and the Lafourche deltaic headland to the west. Rapid relative sea-level rise (1??03 cm year-1) and other erosional processes within Barataria Bay have led to substantial increases in the area of open water (> 775 km2 since 1956) and the attendant bay tidal prism. Historically, the increase in tidal discharge at inlets has produced larger channel cross-sections and prograding ebb-tidal deltas. For example, the ebb delta at Barataria Pass has built seaward > 2??2 km since the 1880s. Shoreline erosion and an increasing bay tidal prism also facilitated the formation of new inlets. Four major lithofacies characterize the Barataria coast ebb-tidal deltas and associated sedimentary environments. These include a proximal delta facies composed of massive to laminated, fine grey-brown to pale yellow sand and a distal delta facies consisting of thinly laminated, grey to pale yellow sand and silty sand with mud layers. The higher energy proximal delta deposits contain a greater percentage of sand (75-100%) compared with the distal delta sediments (60-80%). Associated sedimentary units include a nearshore facies consisting of horizontally laminated, fine to very fine grey sand with mud layers and an offshore facies that is composed of grey to dark grey, laminated sandy silt to silty clay. All facies coarsen upwards except the offshore facies, which fines upwards. An evolutionary model is presented for the stratigraphic development of the ebb-tidal deltas in a regime of increasing tidal energy resulting from coastal land loss and tidal prism growth. Ebb-tidal delta facies prograde over nearshore sediments, which interfinger with offshore facies. The seaward decrease in tidal current velocity of the ebb discharge produces a gradational contact between proximal and distal tidal delta facies. As the tidal discharge increases and the inlet

  3. Numerical investigation of surface water-groundwater interactions in a river-dominated delta

    NASA Astrophysics Data System (ADS)

    Sawyer, Audrey; Edmonds, Douglas; Knights, Deon

    2015-04-01

    Deltas are fragile coastal wetland systems that are rapidly vanishing due to subsidence and sea level rise. In most wetland environments, groundwater plays a central role in carbon and nutrient cycles, vegetation community structure, and contaminant transport, yet little is known about groundwater in vanishing delta wetlands. Here, we characterize the basic patterns, rates, and residence times of groundwater flow in a model delta wetland. Delta topography was simulated by growing the delta in Delft3D, a morphodynamic flow and sediment transport model. Water surface elevations under mean annual discharge conditions were used to drive a steady groundwater flow model. Under these average hydrologic conditions, surface water-groundwater exchange represents a small fraction (<1%) of river discharge to the coast, but storm surge, waves, and tides likely increase exchange rates periodically. Groundwater residence times range widely from hours to years. The residence time distribution exhibits power-law tailing that is characteristic of surface water-groundwater exchange in single-threaded river channels. The patterns of groundwater residence times within delta networks are likely to control redox chemistry and may therefore influence the community structure of microbes, benthic invertebrates, and plants. This study illustrates the tremendous potential for numerical approaches to characterizing groundwater flow in delta wetlands. Continued efforts are needed to understand the role of groundwater in delta wetlands, particularly in light of growing initiatives to restore deltas and their ecosystems.

  4. [Community structure of planktonic rotifers in the Pearl River Delta].

    PubMed

    Gao, Yuan; Li, Xin-Hui; Lai, Zi-Ni; Yu, Jing; Wang, Chao; Zeng, Yan-Yi; Liu, Qian-Fu; Yang, Wan-Ling

    2014-07-01

    Four ecological investigations were carried out on planktonic rotifers in Pearl River Delta in 2012. The community structure, including spatial and temporal patterns of species composition, dominant species, biomass and biodiversity, was investigated. The correlation between the community structure of rotifers and the environmental factors was discussed. Moreover, the aggregation structures of rotifers were analyzed. A total of 53 rotifer species were found. Dominant species changed markedly with season and space. Polyarthra trigla had higher dominance. In terms of seasonal changes, the density and biomass were higher in dry season than in wet season, while the biodiversity and evenness indices were vice versa. The biomass and biodiversity of rotifers showed highly significant differences among seasons. In terms of spatial distribution, the average density and the average biomass showed an increase from the southwest to the northeast. The highest density and biomass were recorded in Shiqiao. The biodiversity and evenness indices had an opposite spatial distribution, with the highest values being recorded in Qingqi. The rotifer density was significantly different among the investigated sites, while the biomass and biodiversity were not significantly different. Correlation analysis demonstrated a highly significant positive correlation between rotifer density and biomass, as well as between biodiversity and evenness indices, and a highly negative correlation between biodiversity and biomass. The biodiversity and evenness indices both decreased markedly with the increase of biomass. Principal component analysis indicated that the rotifer density was closely correlated with environment factors, such as water temperature, pH, dissolved oxy- gen, chlorophyll a content, total phosphorus, and total nitrogen, in different seasons. Aggregation analysis based on rotifer density revealed five aggregation structures in the investigated sites, indicating significant differences

  5. Reconstructing the late-Holocene fluvial dynamics of the River Nile in central Egypt

    NASA Astrophysics Data System (ADS)

    Verstraeten, G.; Willems, H.; Notebaert, B.; Dusar, B.; de Laet, V.; Marinova, E.; Kaniewski, D.

    2009-04-01

    From 2004 on, geoarchaeological research is being carried out in the Nile floodplain near Dayr al Bershah, an important ancient Egyptian funeral site in central Egypt covering burial sites from the Old to the New Kingdom. The reconstruction of the ancient Nilotic landscape and human-environment interactions alongside the transition from the lower desert to the Nile floodplain was approached multidisciplinarily. On the one hand, in the floodplain more than 300 detailed hand augerings up to 6 m depth were made, and compared with electrical resistivity imaging profiles with lengths up to 1200 m and depths from 20-45 m. These data were complemented with information obtained from historical map analysis, remote sensing imagery (ASTER, Quickbird, Corona) and digital elevation models (SRTM). Preliminary results show good correspondence between the sedimentological analysis of the hand augerings and the electrical resistivity values: sandy paleochannel deposits show high resistivity values, whereas silty to clay-rich floodplain deposits show very low ER-values. All information sources show several Nile branches being active prior to the closure of the Aswan Dam in 1964, and most branches can also be traced applying topographical analysis, confirming the sedimentological and ER analyses. However, one major branch relatively close to the eastern edge of the floodplain and the current village of Dayr al Bershah could only be traced by coring and ER as it is no longer topographically visible. First dating results suggest this Nile branch being at least 600 years old and some parts being active up to 2000 years ago. Moreover, several radiocarbon dates from the Nile floodplain show there is no clear age-depth relationship present within the floodplain sediments, as a strong negative exponential relationship between the sedimentation rate in mm.a-1 and the sediment age has been proven. This indicates large parts of the floodplain near Dayr al Bershah have been reworked over the

  6. Recent morphodynamic evolution of coastline of Mekong river Delta, towards an increased vulnerability

    NASA Astrophysics Data System (ADS)

    Besset, Manon; Brunier, Guillaume; Anthony, Edward

    2015-04-01

    Key words: Mekong river delta - Coastal deltaic morphodynamic - Deltaic vulnerability The complexity of coastal river deltas lies in part in aspects of sediment supply and redistribution, trapping and readjustment. The sediment supply and involved processes are governed by river-marine forcing, weather and climate, increasingly affected by humans, all within a frame of interactivity and morphodynamic equilibrium/disequilibrium that determine the evolution of the delta. The Mekong river delta is the third largest delta in the world. It is subject to important tidal influence, alluvial contribution from the fourth largest Asian river, seasonal monsoons and associated swell and other high-energy events. After a strong advance of over 200 km from 6.0 ka to near present (Tamura et al., 2012), the delta shoreline is rapidly and irregularly retreating, constraining the 20 million people living off the delta to suffer or adapt. This study documents changes over the last 50 years affecting the 700 km-long shoreline of the delta based on analysis of USGS topographic maps (1965), low-resolution Landsat (1973-2014) and very high-resolution SPOT 5 (2003-2011) satellite imagery. The results show widespread erosion of nearly 10 m/year over the period corresponding to the Second Indochinese conflict (1962-1972). Then followed a multi-decadal phase of accretion of about 8 m/yr, with spatial fluctuations of up to nearly -20 m/yr. This variability could reflect alternation of periods of resilience and self-organization in coastal sediment cells. A deceleration of accretion in the 2000s (+0.63 m/yr) and even a shift to erosion since 2011 (-1 m/s) are observed in parallel with the intensification of land-use changes, exploitation of the river-bed by sand mining, and hydropower dams (Brunier et al., 2014), and deforestation of deltaic wetlands for agriculture and fisheries(Thu et al., 2007). These erosion trends and their spatiotemporal disparities exacerbate the vulnerability of the

  7. Sand as a stable and sustainable resource for nourishing the Mississippi River delta

    NASA Astrophysics Data System (ADS)

    Nittrouer, Jeffrey A.; Viparelli, Enrica

    2014-05-01

    The Mississippi River delta is undergoing a catastrophic drowning, whereby 5,000 km2 of low-lying wetlands have converted to open water over at least the past eight decades, as a result of many anthropogenic and natural factors. Continued net land loss has been thought inevitable due to a decline in the load of total suspended sediment--both sand and mud--carried by the river. However, sand--which accounts for ~50-70% of modern and ancient Mississippi delta deposits but comprises only ~20% of the sampled portion of the total load--could be more important than mud for subaerial delta growth. Historically, half of the Mississippi River sediment load is supplied by the Missouri River. Here we analyse suspended sediment load data from two locations downstream from the lowest Missouri River dam to show that the measured sand load in the lower 1,100 km of the Mississippi River has not significantly diminished since dam construction. A one-dimensional numerical model of river morphodynamics predicts that the sand load feeding the delta will decrease only gradually over the next several centuries, with an estimated decline from current values of no more than about 17% within the coming six centuries. We conclude that the lower Mississippi River channel holds a significant reservoir of sand that is available to replenish diminished loads via bed scour and substantially mitigate land loss.

  8. Establishing river basin organisations inVietnam: Red River, Dong Nai River and Lower Mekong Delta.

    PubMed

    Taylor, P; Wright, G

    2001-01-01

    River basin management is receiving considerable attention at present. Part of the debate, now occurring worldwide, concerns the nature of the organisations that are required to manage river basins successfully, and whether special-purpose river basin organisations (RBOs) are always necessary and in what circumstance they are likely to (i) add to the management of the water resources and (ii) be successful. The development of river basin management requires a number of important elements to be developed to a point where the river basin can be managed successfully. These include the relevant laws, the public and non-government institutions, the technical capabilities of the people, the understanding and motivation of people, and the technical capacity and systems, including information. A river basin organisation (or RBO) is taken to mean a special-purpose organisation charged with some part of the management of the water resources of a particular river basin. Generally speaking, such organisations are responsible for various functions related to the supply, distribution, protection and allocation of water, and their boundaries follow the watershed of the river in question. However, the same functions can be carried out by various organisations, which are not configured on the geographical boundaries of a river basin. This paper outlines recent work on river basin organisation in Vietnam, and makes some comparisons with the situation in Australia.

  9. Grain size controls on the morphology and stratigraphy of river-dominated deltas

    NASA Astrophysics Data System (ADS)

    Burpee, Alex; Parsons, Daniel; Slingerland, Rudy; Edmonds, Doug; Best, Jim; Cederberg, James; McGuffin, Andrew; Caldwell, Rebecca; Nijhuis, Austin

    2015-04-01

    The proportions of sand and mud that make up a river-dominated delta strongly determine its topset morphology, which in turn controls its internal facies and clinoform geometry. These relationships allow prediction of the stratigraphy of a delta using the character of its topset and reconstruction of deltaic planform from measures of clinoform geometry. This paper presents results from the Delft3D modeling system which was used to simulate nine self-formed deltas that possess different sediment loads and critical shear stresses that are required for re-entrainment of mud. The simulated deltas were set to prograde into a shallow basin without waves, tides, Coriolis forcing, and buoyancy. Model results indicate that sand-dominated deltas are more fan-shaped whilst mud-dominated deltas are more birdsfoot in planform, because the sand-dominated deltas have more active distributaries, a smaller variance of topset elevations, and thereby experience a more equitable distribution of sediment to their perimeters. This results in a larger proportion of channel facies in sand-dominated deltas, and more uniformly-distributed clinoform dip directions, steeper dips, and greater clinoform concavity. These conclusions are consistent with data collected from the Goose River Delta, a coarse-grained fan delta prograding into Goose Bay, Labrador, Canada and also allow us to undertake a re-interpretation of the Kf-1 parasequence set of the Cretaceous Last Chance Delta, a unit of the Ferron Sandstone near Emery, Utah, USA. We argue that the Last Chance delta likely possessed numerous distributaries with at least five orders of bifurcation.

  10. Mercury in the Mackenzie River delta and estuary: concentrations and fluxes during open-water conditions.

    PubMed

    Graydon, Jennifer A; Emmerton, Craig A; Lesack, Lance F W; Kelly, Erin N

    2009-04-01

    Estimates of mercury (Hg) loadings to the Arctic Ocean from circumpolar rivers have not considered biogeochemical changes that occur when river water is temporarily stored in large deltas (delta effect). There are also few data describing Hg changes across the freshwater-saltwater transition zone (FSTZ) of these rivers. We assessed temporal changes in unfiltered total mercury (THg) and methylmercury (MeHg) concentrations during open-water 2004 in the Mackenzie River upstream of the Mackenzie River delta, and in 6 floodplain lakes across an elevation gradient. These data were used to calculate Hg fluxes from the Mackenzie River and to evaluate a delta effect on Hg using an estimate of delta river water storage and a mixing analysis. Mean THg concentrations were highest in river water (9.17+/-5.51 ng/L) and decreased up the lake elevation gradient. Mean MeHg concentrations were highest in lakes periodically connected to the river (0.213+/-0.122 ng/L) and MeHg concentrations in elevated lakes showed a mid-summer peak. Results from the mixing analysis showed that the delta effect may be large enough to affect Hg loadings to the Arctic Ocean. THg concentrations exiting the delta (10.2 ng/L) were 16% lower than those entering (12.1 ng/L), whereas MeHg showed little change. We calculated 2.5-month (open-water) THg and MeHg fluxes from the Mackenzie River of 1208 and 8.4 kg. These fluxes are similar in magnitude to previous annual estimates in the arctic literature suggesting that previously published annual Hg fluxes from the Mackenzie River may be large underestimates. We also assessed changes in Mackenzie River water THg and MeHg concentrations as it crossed the FSTZ during an open-water cruise. THg decreased non-conservatively across the estuary from 3.8-0.6 ng/L, possibly due to mixing and particle settling. MeHg concentrations were variable and near detection. Our results show that the Mackenzie River estuary is a dynamic environment and may have important controls

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

    PubMed

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

    2015-01-01

    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. PMID:26446752

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

    PubMed

    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.

  13. Sediment transport dynamics linked to morphological evolution of the Selenga River delta, Lake Baikal, Russia

    NASA Astrophysics Data System (ADS)

    Dong, T. Y.; Nittrouer, J.; McElroy, B. J.; Czapiga, M. J.; Il'icheva, E.; Pavolv, M.; Parker, G.

    2014-12-01

    The Selenga River delta, Lake Baikal, Russia, is approximately 700 km2 in size and contains three active lobes that receive varying amounts of water and sediment discharge. This delta represents a unique end-member in so far that the system is positioned along the deep-water (~1500 m) margin of Lake Baikal and therefore exists as a shelf-edge delta. In order to evaluate the morphological dynamics of the Selenga delta, field expeditions were undertaken during July 2013 and 2014, to investigate the morphologic, sedimentologic, and hydraulic nature of this delta system. Single-beam bathymetry data, sidescan sonar data, sediment samples, and aerial survey data were collected and analyzed to constrain: 1) channel geometries within the delta, 2) bedform sizes and spatial distributions, 3) grain size composition of channel bed sediment as well as bank sediment, collected from both major and minor distributary channels, and 4) elevation range of the subaerial portion of the delta. Our data indicate that the delta possesses downstream sediment fining, ranging from predominantly gravel and sand near the delta apex to silt and sand at the delta-lake interface. Field surveys also indicate that the Selenga delta has both eroding and aggrading banks, and that the delta is actively incising into some banks that consist of terraces, which are defined as regions that are not inundated by typical 2- to 4-year flood discharge events. Therefore the terraces are distinct from the actively accreting regions of the delta that receive sedimentation via water inundation during regular river floods. We spatially constrain the regions of the Selenga delta that are inundated during floods versus terraced using a 1-D water-surface hydrodynamic model that produces estimates of stage for flood water discharges, whereby local water surface elevations produced with the model are compared to the measured terrestrial elevations. Our analyses show that terrace elevations steadily decrease downstream

  14. Quantifying the signature of sediment composition on the topologic and dynamic complexity of river delta channel networks and inferences toward delta classification

    NASA Astrophysics Data System (ADS)

    Tejedor, Alejandro; Longjas, Anthony; Caldwell, Rebecca; Edmonds, Douglas A.; Zaliapin, Ilya; Foufoula-Georgiou, Efi

    2016-04-01

    Deltas contain complex self-organizing channel networks that nourish the surface with sediment and nutrients. Developing a quantitative understanding of how controlling physical mechanisms of delta formation relate to the channel networks they imprint on the landscape remains an open problem, hindering further progress on quantitative delta classification and understanding process from form. Here we isolate the effect of sediment composition on network structure by analyzing Delft3D river-dominated deltas within the recently introduced graph-theoretic framework for quantifying complexity of delta channel networks. We demonstrate that deltas with coarser incoming sediment tend to be more complex topologically (increased number of pathways) but simpler dynamically (reduced flux exchange between subnetworks) and that once a morphodynamic steady state is reached, complexity also achieves a steady state. By positioning simulated deltas on the so-called TopoDynamic complexity space and comparing with field deltas, we propose a quantitative framework for exploring complexity toward systematic inference and classification.

  15. Cyclone Nargis survey in Myanmar's Ayeyarwady River delta

    NASA Astrophysics Data System (ADS)

    Fritz, H. M.; Blount, C.; Thwin, S.; Thu, M. K.; Chan, N.

    2008-12-01

    Tropical cyclone Nargis (Cat. 4) made landfall on May 2, 2008, causing the worst natural disaster in Myanmar's recorded history. Official death toll estimates exceed 130,000 fatalities making it the 7th deadliest cyclone ever recorded worldwide. Nargis took a rare nearly eastern track over the Bay of Bengal while developing sustained winds over 210 km/h with gusts up to 260 km/h hours prior to landfall in Myanmar at untypically low latitude near 16°N. It then proceeded northeast and approximately 12 hours later weakened to a Category 1 storm with sustained wind speeds of 130 km/h as it passed over Yangon. The first independent storm surge reconnaissance team was deployed to Myanmar from 9 to 23 August 2008. Cyclone Nargis struck low-lying coastal plains particularly vulnerable to storm surge flooding due to the lack of effective barriers. The team surveyed coastal and inland villages from Pyapon to Purian Point, encompassing the Bogale and Ayeyarwady River mouths. The survey by boat spanned more than 150 km parallel to the cyclone track between Pyapon and Pyinkhayan encompassing 20 hardest hit settlements such as Pyinsalu. More than 1m vertical erosion and 150 m land loss were measured at various coastal locations such as Aya. Massive deforestation of mangroves and land use were documented. Maximum storm surge elevations and overland flow depths were measured based on water marks on buildings, scars on trees, and rafted debris. The storm surge peaked in the landfall area south of Pyinkhayan and eastwards in Pyinsalu exceeding 5m. Storm waves more than 2m high were superimposed on the storm surge level in most areas according to eyewitnesses. Inundation distances reached beyond 50 km inland. Catastrophic peak fatality rates exceeded 80% in hardest hit villages with the majority being children and women. The high water marks and fatality rates significantly exceeded corresponding 2004 Indian Ocean tsunami values at every location. Eyewitnesses were interviewed to

  16. EAARL Coastal Topography-Pearl River Delta 2008: First Surface

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Miner, Michael D.; Michael, D.; Yates, Xan; Bonisteel, Jamie M.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the University of New Orleans (UNO), Pontchartrain Institute for Environmental Sciences (PIES), New Orleans, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March 9-11, 2008. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the

  17. EAARL Coastal Topography-Pearl River Delta 2008: Bare Earth

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Miner, Michael D.; Yates, Xan; Bonisteel, Jamie M.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the University of New Orleans (UNO), Pontchartrain Institute for Environmental Sciences (PIES), New Orleans, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March 9-11, 2008. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the

  18. First account on the sedimentological, geochemical and petrophysical record of the Messinian Salinity Crisis in the subsurface of onshore Nile Delta, Egypt.

    NASA Astrophysics Data System (ADS)

    Leila, Mahmoud; Moscariello, Andrea

    2016-04-01

    The giant Cenozoic Nile Delta system in the extreme northern part of Egypt occupies the southeastern part of the Eastern Mediterranean Basin and represents the most prolific gas province in Egypt with estimates more than 62 tcf of proven reserves (Niazi and Dahi, 2004). Despite the importance of the Messinian sediments in the Nile Delta hosting excellent petroleum reservoirs and seals (Dolson et al., 2001), they are still poorly studied. A multidisciplinary sedimentological, geochemical and petrophysical study is being carried out to unravel the depositional environment and tectonic setting before, during and after the important Messinian Salinity Crisis (MSC) period in the Eastern Mediterranean, and how this affected the eastern part of the onshore Nile Delta. The Lower Messinian Qawasim Formation consists of high to low-density turbiditic sandstones displaying several vertical stacked patterns of coarsening and fining upwards trends reflecting different pulses of sedimentation suggesting a sedimentation in a submarine fan developed at the base of shelf slope. The deeply incised valley infill, dating the Upper Messinian consists of the Abu Madi Formation made of lowstand braided and meandering fluvial sandstone interbedded with fine-grained floodplain sandstones and siltstones. The base of this unit is erosional and contains large mud clasts embedded in a fine-grained matrix. The Upper Miocene lowstand fluvial sandstones are capped by estuarine fine-grained cross laminated sandstones, siltstones/mudstones followed by an open marine mudstones of the Early Pliocene Kafr El-Sheikh Formation representing the end of the MSC and the subsequent transgression episode after the re-establishment of the connection between the Mediterranean and the Atlantic Ocean. Both the Qawasim and Abu Madi Formations display similar geochemical fingerprints from the clastic components. Recycled Cretaceous and Eocene sedimentary and granodioritic to intermediate igneous rocks located in

  19. Subaquatic soils in the Volga, Don and Kuban Rivers deltas.

    NASA Astrophysics Data System (ADS)

    Tkachenko, Anna; Gerasimova, Maria; Lychagin, Mikhail

    2015-04-01

    River deltas occupy a special interface position in the environment and are characterized by contrasting hydrological and landscape-geochemical regimes. Small depth of water and weak currents contribute to suspended matter deposition. Significant spread of aquatic plants provides the enrichment of subaquatic soils in organic matter. All these factors contribute to the formation of different subaquatic soils. Possibility of including them in the classification systems is discussed by many authors (Demas and Rabenhorst, 2001; Stolt et al., 2011); there is also a special subaquatic qualifier for submerged soils in WRB; however, they are still absent in many national classification systems, as well as in the recent Russian one (2008). The purpose of this research is to reveal the properties of the subaquatic soils in the Volga, Don and Kuban Rivers deltaic areas and to propose pedogenetic approaches to categorize AQUAZEMS. Investigations of deltaic areas were performed in 2010-2012 in deltaic lagoons, fresh-water bays, small channels, oxbow lakes, and also in the part of deltaic near-shore zone. Morphological descriptions of distinguishable layers (colour, texture, thickness, boundaries, consistence, plant residues and shell debris) were made in columns obtained by augering as it is done by other researchers (Stolt et al., 2011), and supplemented with analytical data (pH, Eh, TDS, particle-size composition, and Corg). It is suggested to name the horizons in aquazems in the same way as in terrestrial soils in the recent Russian soil classification system, and apply symbols starting with the combination of caps - AQ. Most typical for aquazems is their aquagley AQG horizon that has features similar to terrestrial gleys - homogeneity in color and consistence, permeation by clay, predominance of dove grey colour. The AQG horizon gradually merges into parent material - stratified bottom sediments. The "topsoil" is usually enriched in organic matter and may be different in

  20. A graph-theoretic approach to River Deltas: Studying complexity, universality, and vulnerability to change.

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    River deltas are landforms with complex channel networks that deliver water, sediment and nutrient fluxes from rivers to oceans or inland water bodies via multiple pathways. Most of the deltas are subject to anthropogenic and natural perturbations causing topological and dynamical changes in the delta structure and function. We present a quantitative framework based on spectral graph theory within which a systematic study of the topology, transport dynamics and response to change of river deltas can be performed, as well as computation of sub-networks (from apex to shoreline outlets), and contributing/nourishing areas. We introduce metrics of topologic and dynamic complexity and define a multidimensional complexity space where each delta projects. By analysis of seven deltas of different morphodynamic and environmental settings, we report a surprising power law relationship between sub-network size and its dynamic exchange with surrounding sub-networks within the deltaic system. The exponent of the relationship is universal (predicting that a sub-network twice as large leaks out to other sub-networks only 1.3 times its total flux) and the pre-exponent depends on the topologic complexity of the delta network as a whole, i.e., the ensemble of the interacting sub-sub-networks. We also use the developed framework to construct vulnerability maps that quantify the relative change of sediment and water delivery to the shoreline outlets in response to possible perturbations in hundreds of upstream links. This enables us to evaluate which links (hotspots) and what management scenarios would most influence flux delivery to the outlets, paving the way for systematically examining how local or spatially distributed delta interventions can be studied within a systems approach for delta sustainability.

  1. River delta network hydraulic residence time distributions and their role in coastal nutrient biogeochemistry

    NASA Astrophysics Data System (ADS)

    Hiatt, M. R.; Castaneda, E.; Twilley, R.; Hodges, B. R.; Passalacqua, P.

    2015-12-01

    River deltas have the potential to mitigate increased nutrient loading to coastal waters by acting as biofilters that reduce the impact of nutrient enrichment on downstream ecosystems. Hydraulic residence time (HRT) is known to be a major control on biogeochemical processes and deltaic floodplains are hypothesized to have relatively long HRTs. Hydrological connectivity and delta floodplain inundation induced by riverine forces, tides, and winds likely alter surface water flow patterns and HRTs. Since deltaic floodplains are important elements of delta networks and receive significant fluxes of water, sediment, and nutrients from distributary channels, biogeochemical transformations occurring within these zones could significantly reduce nutrient loading to coastal receiving waters. However, network-scale estimates of HRT in river deltas are lacking and little is known about the effects of tides, wind, and the riverine input on the HRT distribution. Subsequently, there lacks a benchmark for evaluating the impact of engineered river diversions on coastal nutrient ecology. In this study, we estimate the HRT of a coastal river delta by using hydrodynamic modeling supported by field data and relate the HRT to spatial and temporal patterns in nitrate levels measured at discrete stations inside a delta island at Wax Lake Delta. We highlight the control of the degree of hydrological connectivity between distributary channels and interdistributary islands on the network HRT distribution and address the roles of tides and wind on altering the shape of the distribution. We compare the observed nitrate concentrations to patterns of channel-floodplain hydrological connectivity and find this connectivity to play a significant role in the nutrient removal. Our results provide insight into the potential role of deltaic wetlands in reducing the nutrient loading to near-shore waters in response to large-scale river diversions.

  2. Retrospective Montioring of Ecosystem Changes Using Published Data, Lessons Learned from Egypt's Nile River Delta

    EPA Science Inventory

    Monitoring programs for riverine and wetland ecosystems often do not begin until some substantial shift in ecosystem structure or loss of ecosystem service has taken place. Sometimes a lack of resources or interest may impede monitoring efforts. In the case of the large brackis...

  3. A river mouth submarine channel and failure complex, Fraser Delta, Canada

    NASA Astrophysics Data System (ADS)

    Hart, B. S.; Prior, D. B.; Barrie, J. V.; Currie, R. G.; Luternauer, J. L.

    1992-11-01

    High-resolution seismic and side-scan sonar surveying, combined with coring, of the Fraser Delta slope seaward of the main fluvial distributary has revealed a complex suite of morphologic units which include undisturbed delta slope sediments, shallow rotational slides, relict and active slope channels, debris accumulations and ponded turbidites. Sediment transport through the main submarine channel is thought to be primarily by debris flows, rather than by turbidity currents. Although this is a seismically active region, the instability related features described here are probably due primarily to rapid sediment deposition on the upper delta slope at the river mouth.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26446752

  6. Birds of the Indigirka River Delta, Russia: Historical and biogeographic comparisons

    USGS Publications Warehouse

    Pearce, J.M.; Esler, Daniel; Degtyarev, A.G.

    1998-01-01

    We documented the breeding status and relative abundance of all avian species on the coastal portion of the Indigirka River Delta during spring and summer 1993-95. Data on avifaunal composition were then compared to data from adjacent areas from Eastern Siberia to the Chukotka Peninsula to evaluate how species composition changes longitudinally within the arctic and typical tundra zones of northern Russia. We recorded 63 species on the Indigirka River Delta, 37 (58.7 %) of which were confirmed breeders during at least one of the three years. Five new species were recorded breeding (Arenaria interpres, Calidris acuminata, Limnodromus scolopaceus, Stercorarius parasiticus, and Asio flammeus), and 13 previously unrecorded species were observed during this study. We also identified several species of rare or threatened status in Russia and North America, including Branta bernicla, Somateria fischeri, Polysticta stelleri, and Rhodostethia rosea. We used parsimony and distance matrix methods to compare the breeding species richness on the Indigirka River Delta to that of six other Russian Arctic areas. Biogeographic comparisons revealed the presence of two clades in the Russian Arctic: the Lena River Delta east to Chaun Delta and the Chukotka Peninsula.

  7. River Delta Subsidence Measured with Interferometric Synthetic Aperture Radar (InSAR)

    NASA Astrophysics Data System (ADS)

    Higgins, Stephanie

    This thesis addresses the need for high-resolution subsidence maps of major world river deltas. Driven by a combination of rising water, sediment compaction, and reduced sediment supply due to damming and flood control, many deltas are sinking relative to sea level. A lack of data constraining rates and patterns of subsidence has made it difficult to determine the relative contributions of each factor in any given delta, however, or to assess whether the primary drivers of land subsidence are natural or anthropogenic. In recent years, Interferometric Synthetic Aperture Radar (InSAR) has emerged as a satellite-based technique that can map ground deformation with mm-scale accuracy over thousands of square kilometers. These maps could provide critical insight into the drivers of subsidence in deltas, but InSAR is not typically applied to non-urban delta areas due to the difficulties of performing the technique in wet, vegetated settings. This thesis addresses those difficulties and achieves high-resolution measurements of ground deformation in rural deltaic areas. Chapter 1 introduces the processes that drive relative sea level rise in river deltas and investigates open questions in delta subsidence research. Chapter 2 assesses the performance of InSAR in delta settings and reviews interferogram generation in the context of delta analysis, presenting delta-specific processing details and guiding interpretation in these challenging areas. Chapter 3 applies Differential (D-) InSAR to the coast of the Yellow River Delta in China. Results show that subsidence rates are as high as 250 mm/y due to groundwater extraction at aquaculture facilities, a rate that exceeds local and global average sea level rise by nearly two orders of magnitude and suggests a significant hazard for Asian megadeltas. Chapter 4 applies interferometric stacking and Small Baseline Subset (SBAS)-InSAR to the Ganges-Brahmaputra Delta, Bangladesh. Results show that stratigraphy controls subsidence in

  8. Estimating sediment budgets at the interface between rivers and estuaries with application to the Sacramento-San Joaquin River Delta

    USGS Publications Warehouse

    Wright, S.A.; Schoellhamer, D.H.

    2005-01-01

    [1] Where rivers encounter estuaries, a transition zone develops where riverine and tidal processes both affect sediment transport processes. One such transition zone is the Sacramento-San Joaquin River Delta, a large, complex system where several rivers meet to form an estuary (San Francisco Bay). Herein we present the results of a detailed sediment budget for this river/estuary transitional system. The primary regional goal of the study was to measure sediment transport rates and pathways in the delta in support of ecosystem restoration efforts. In addition to achieving this regional goal, the study has produced general methods to collect, edit, and analyze (including error analysis) sediment transport data at the interface of rivers and estuaries. Estimating sediment budgets for these systems is difficult because of the mixed nature of riverine versus tidal transport processes, the different timescales of transport in fluvial and tidal environments, and the sheer complexity and size of systems such as the Sacramento-San Joaquin River Delta. Sediment budgets also require error estimates in order to assess whether differences in inflows and outflows, which could be small compared to overall fluxes, are indeed distinguishable from zero. Over the 4 year period of this study, water years 1999-2002, 6.6 ?? 0.9 Mt of sediment entered the delta and 2.2 ?? 0.7 Mt exited, resulting in 4.4 ?? 1.1 Mt (67 ?? 17%) of deposition. The estimated deposition rate corresponding to this mass of sediment compares favorably with measured inorganic sediment accumulation on vegetated wetlands in the delta.

  9. Geoarcheological investigations on the development of the Neva River delta (Gulf of Finland) during the Holocene

    NASA Astrophysics Data System (ADS)

    Kulkova, M. A.; Gusentsova, T. M.; Sapelko, T. V.; Nesterov, E. M.; Sorokin, P. E.; Ludikova, A. V.; Ryabchuk, D. V.; Markova, M. A.

    2014-01-01

    The article is devoted to the formation of the Neva River in the context of geoarcheological investigations carried out on the archeological site Okhta 1, which is located at the mouth of the Okhta River in the St. Petersburg city region (NW Russia). The site is multilayered and includes cultural layers from the Neolithic, Early Metal Age, Iron Age, and the Landskrona 13th century and Nienschanz 17th century fortresses. The Neva River's formation has long been a controversial question. The transgression of Ladoga Lake around 5950-2950 cal BP had an effect on the formation of the Neva River. By reviewing the complex investigations of the deposits and artifacts by geological and archeological methods, we may reconstruct the developmental stages of the Litorina Sea Bay and Neva River delta in this area. The formation of delta river sediments occurred from 3589 to 3078 cal BP. The end of the delta river formation can be associated with the appearance of ancient Early Iron Age people in the region in 2750-2350 cal BP.

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

    USGS Publications Warehouse

    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

  11. Increasing nutrient concentrations and the rise and fall of a coastal fishery; a review of data from the Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Oczkowski, Autumn; Nixon, Scott

    2008-04-01

    There is a conceptual basis, and some empirical evidence, that increasing nutrient loads to coastal waterbodies will initially increase ecosystem productivity up to a threshold, beyond which secondary productivity and fishery yields will decline. Here we have compiled data from the Egyptian and international literature for fish landings and inorganic nutrient (nitrogen and phosphorus) data from four large coastal lagoons (63-500 km 2) on Egypt's Nile Delta to provide evidence for the initially positive, but then negative, response of fishery yields to increased nutrient supply across a very wide range of enrichment (up to 1 mM dissolved organic nitrogen, DIN). Taking the data from the four lagoons as an aggregate, fish landings increase with increased nutrients up to a peak in landings at approximately 100 μM DIN, beyond which there was an exponential decline in landings. It appears that pesticide and heavy metal contamination and overfishing played only minor roles in the lowered fishery yield at highest DIN concentrations. We do not have sufficient evidence about the specific mechanisms that led to the decline of the fishery, but suspect that some feature of eutrophication—low oxygen, for example, may have been involved.

  12. LIS-HYMAP coupled Hydrological Modeling in the Nile River Basin and the Greater Horn of Africa

    NASA Astrophysics Data System (ADS)

    Jung, H. C.; Getirana, A.; Policelli, F. S.

    2015-12-01

    Water scarcity and resources in Africa have been exacerbated by periodic droughts and floods. However, few studies show the quantitative analysis of water balance or basin-scale hydrological modeling in Northeast Africa. The NASA Land Information System (LIS) is implemented to simulate land surface processes in the Nile River Basin and the Greater Horn of Africa. In this context, the Noah land surface model (LSM) and the Hydrological Modeling and Analysis Platform (HYMAP) are used to reproduce the water budget and surface water (rivers and floodplains) dynamics in that region. The Global Data Assimilation System (GDAS) meteorological dataset is used to force the system . Due to the unavailability of recent ground-based observations, satellite data are considered to evaluate first model outputs. Water levels at 10 Envisat virtual stations and water discharges at a gauging station are used to provide model performance coefficients (e.g. Nash-Sutcliffe, delay index, relative error). We also compare the spatial and temporal variations of flooded areas from the model with the Global Inundation Extent from Multi-Satellites (GIEMS) and the Alaska Satellite Facility (ASF)'s MEaSUREs Wetland data. Finally, we estimate surface water storage variations using a hypsographic curve approach with Shuttle Radar Topography Mission (SRTM) topographic data and evaluate the model-derived water storage changes in both river and floodplain. This study demonstrates the feasibility of using LIS-HYMAP coupled modeling to support seasonal forecast methods for prediction of decision-relevant metrics of hydrologic extremes.

  13. Origin of the Sinai-Negev erg, Egypt and Israel: mineralogical and geochemical evidence for the importance of the Nile and sea level history

    USGS Publications Warehouse

    Muhs, Daniel R.; Roskin, Joel; Tsoar, Haim; Skipp, Gary; Budahn, James R.; Sneh, Amihai; Porat, Naomi; Stanley, Jean-Daniel; Katra, Itzhak; Blumberg, Dan G.

    2013-01-01

    The Sinai–Negev erg occupies an area of 13,000 km2 in the deserts of Egypt and Israel. Aeolian sand of this erg has been proposed to be derived from the Nile Delta, but empirical data supporting this view are lacking. An alternative source sediment is sand from the large Wadi El Arish drainage system in central and northern Sinai. Mineralogy of the Negev and Sinai dunes shows that they are high in quartz, with much smaller amounts of K-feldspar and plagioclase. Both Nile Delta sands and Sinai wadi sands, upstream of the dunes, also have high amounts of quartz relative to K-feldspar and plagioclase. However, Sinai wadi sands have abundant calcite, whereas Nile Delta sands have little or no calcite. Overall, the mineralogical data suggest that the dunes are derived dominantly from the Nile Delta, with Sinai wadi sands being a minor contributor. Geochemical data that proxy for both the light mineral fraction (SiO2/10–Al2O3 + Na2O + K2O–CaO) and heavy mineral fraction (Fe2O3–MgO–TiO2) also indicate a dominant Nile Delta source for the dunes. Thus, we report here the first empirical evidence that the Sinai–Negev dunes are derived dominantly from the Nile Delta. Linkage of the Sinai–Negev erg to the Nile Delta as a source is consistent with the distribution of OSL ages of Negev dunes in recent studies. Stratigraphic studies show that during the Last Glacial period, when dune incursions in the Sinai–Negev erg began, what is now the Nile Delta area was characterized by a broad, sandy, minimally vegetated plain, with seasonally dry anastomosing channels. Such conditions were ideal for providing a ready source of sand for aeolian transport under what were probably much stronger glacial-age winds. With the post-glacial rise in sea level, the Nile River began to aggrade. Post-glacial sedimentation has been dominated by fine-grained silts and clays. Thus, sea level, along with favorable climatic conditions, emerges as a major influence on the timing of dune

  14. STS-65 Earth observation of Omo River Delta, Lake Turkana in Ethiopia / Kenya

    NASA Technical Reports Server (NTRS)

    1994-01-01

    STS-65 Earth observation taken aboard Columbia, Orbiter Vehicle (OV) 102, is of Omo River Delta and Lake Turkana in Ethiopia / Kenya. The Omo Delta at the north end of Lake Turkana (Rudolph) is one of the long-term environmental study sites of the Space Shuttle program. The environmental interest in this instance is the documentation of the delta's extension into the lake. This delta extension, or aggradation, is felt to be the result of large-scale soil erosion in the recently deforested areas of Ethiopia in the watershed of the Omo River. Using digitized, rectified, machine-classified, and mensurated NASA photography, it has been determined that the Omo Delta has increased in area by approximately 400% to about 1,800 square kilometers since it was first photographed during the Gemini program in 1965. This photograph documents the long-term and increasing turbidity of Lake Turkana and the continuing delta extension southward by both the northwest and northeast distributaries of the Om

  15. Integration of Seismic Sequence Analysis and High Resolution Sequence Stratigraphy for Delineating the Sedimentation Characteristics and Modeling of Baltim Area, Off-Shore Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El-Deen Badawy, A. M. E. S.; Abu El-Ata, A. S. A.; El-Gendy, N. H.

    2014-12-01

    The current study is aiming to discuss the Messinian Prospectivity of the concerned area, which is located in the offshore Nile Delta, about 25 Km from the Mediterranean Sea shoreline. An integrated exploration approach applied, using a variety of the 2D/3D seismic data, subsurface borehole geologic and log data of the selected wells distributed in the study area, as well as the geophysical and biostratigraphic data. The well data comprise well markers, and electric logs, where the geological data represented by litho-stratigraphic information, as well as ditch samples analysis of the studied interval. The geophysical data include check shots, VSP, velocity cubes and 3D seismic lines. Biostratigraphic data include biozones, benthonic to planktonic ratios, nannofossils and foraminiferal data. Seismic interpretation and seismic stratigraphic analysis, in the form of seismic sequence analysis, seismic facies analysis, seismic unit analysis and geologic confirmation have been done by the aid of Petrel and Kingdom computer softwares. The seismic lines were interpreted for defining the different parasequences and picking the various smaller sequences for mapping, after picking each sequence from the seismic correlation, it is facilitated the mapping of every sequence laterally. In addition, the interpretation of structures and isopach of every sequence has been carried out, and the seismic attributes for every sequence were possible, to extract the sands present in each sequence, and to study the extensions of these sands that act as a reservoir. The integration of all results was taken as a base to produce the various models for the study area. The first one was the depositional environmental model, which showed that, the area varies from intertidal-littoral southward at Nidoco wells to inner-middle neritic at Baltim East wells then to outer neritic, and changes to bathyal and then to abyssal at the extreme north. The geologic model for the area was constructed

  16. HABITAT ASSESSMENT USING A RANDOM PROBABILITY BASED SAMPLING DESIGN: ESCAMBIA RIVER DELTA, FLORIDA

    EPA Science Inventory

    Smith, Lisa M., Darrin D. Dantin and Steve Jordan. In press. Habitat Assessment Using a Random Probability Based Sampling Design: Escambia River Delta, Florida (Abstract). To be presented at the SWS/GERS Fall Joint Society Meeting: Communication and Collaboration: Coastal Systems...

  17. Dead delta's former productivity: Two trillion shells at the mouth of the Colorado River

    NASA Astrophysics Data System (ADS)

    Kowalewski, Michal; Avila Serrano, Guillermo E.; Flessa, Karl W.; Goodfriend, Glenn A.

    2000-12-01

    The diversion of the Colorado River by dams and irrigation projects, started in the 1930s, triggered the collapse of the Colorado delta ecosystem. Paleontological, ecological, geochronological, stable isotope, field, and satellite image data provide estimates of the delta's benthic productivity during the 1 k.y. directly preceding the artificial shutdown of the river. At least 2 × 1012 shells of bivalve mollusks make up the current beaches and islands of the delta. The 125 individual valves dated using 14C-calibrated amino acid racemization indicate that these shells range in age from A.D. 950 to 1950. Seasonal intrashell cycles in δ180 values indicate that average-sized bivalves lived at least 3 yr. The most conservative calculation based on these numbers indicates that during the time of natural river flow, an average standing population of ˜6 × 109 bivalve mollusks (population density ˜50/m2) thrived on the delta. In contrast, the present abundance of shelly benthic macroinvertebrates is ˜94% lower (3/m2 in 1999 2000). The dramatic decrease in abundance testifies to the severe loss of benthic productivity resulting from diversion of the river's flow and the inadequacy of its partial resumption (1981 to present). An integration of paleontological records with geomorphological, geochemical, and geochronological data can provide quantitative insights into human impact on coastal ecosystems.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

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

    PubMed

    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.

  20. Private Challenges to Public Dominance: The Resurgence of Private Education in the Pearl River Delta.

    ERIC Educational Resources Information Center

    Mok, Ka-Ho

    1997-01-01

    Examines the policy context in which private education has emerged in post-Mao China. Uses three case studies of private schools/colleges to explore how intellectuals and educators in the Pearl River Delta (Guangdong province) have persevered to assert their academic independence, offer a new agenda for education, and redefine the private-public…

  1. Research Spotlight: What controls the shape of sediment channels in river deltas?

    NASA Astrophysics Data System (ADS)

    Tretkoff, Ernie

    2011-03-01

    When turbulent, sediment-filled rivers empty into oceans and lakes, the channels often divide repeatedly to form triangular deltas. Some channels, however, travel long distances before bifurcating, creating elongated channels. Understanding how these patterns arise could be useful for designing wetland restoration schemes on river deltas. Seeking to explain the conditions under which elongated channels form, Falcini and Jerolmack considered an analogy with cold filaments in ocean currents, in which high potential vorticity (a measure that combines the rotation of a flow with its thermal gradient) helps a filament hold a coherent structure over long distances. The researchers introduced a model that incorporates sediment concentration and fluid vorticity, to derive a new “potential vorticity” equation that describes sedimentation patterns at the river mouth. Their model shows that a high potential vorticity is needed for the creation of elongated channels, and their comparison to modeling, laboratory, and field studies confirms that potential vorticity is a primary control on channel morphology. The new model could help to understand the shape of the iconic Mississippi River delta and may aid in the design of proposed channel diversions there and in other deltas. (Journal of Geophysical Research-Earth Surface, doi:10.1029/2010JF001802, 2010)

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

    USGS Publications Warehouse

    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.

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

    PubMed

    Smith, James E; Bentley, Samuel J; Snedden, Gregg A; 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. PMID:26628104

  4. Sources of excess urban carbonaceous aerosol in the Pearl River delta region, China

    EPA Science Inventory

    Carbonaceous aerosol is one of the important constituents of fine particulate matter (PM2.5) in Southern China, including the Pearl River Delta (PRD) region and Hong Kong (HK). During the study period (October and December of 2002, and March and June of 2003), the monthly average...

  5. Sediment consolidation settlement of Chengbei Sea area in the northern Huanghe River subaqueous delta, China

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Feng, Xiuli; Liu, Xiao

    2016-06-01

    One of the most important factors controlling the morphology of the modern Huanghe (Yellow) River delta is consolidation settlement, which is impacted by fast deposition, high water content, and low density of seafloor sediment. Consolidation settlement of the Huanghe River subaqueous delta was studied based on field data, laboratory experiments on 12 drill holes, and the one-dimensional consolidation theory. Results show that vertical sediment characteristics varied greatly in the rapidly forming sedimentary bodies of the modern Huanghe River subaqueous delta. Sediments in the upper parts of drill holes were coarser than those in the deeper parts, and other physical and mechanical properties changed accordingly. On the basis of the one-dimensional consolidation theory and drilling depth, the final consolidation settlement of drill holes was between 0.6 m and 2.8 m, and the mean settlement of unit depth was at 1.5-3.5 cm/m. It takes about 15-20 years for the consolidation degree to reach 90% and the average sedimentation rate within the overlying 50 m strata was at 5 cm/a to 12 cm/a. This study helps to forecast the final consolidation settlement and settlement rate of the modern Huanghe River subaqueous delta, which provides key geotechnical information for marine engineers.

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

    PubMed Central

    Smith, James E.; Bentley, Samuel J.; Snedden, Gregg A.; 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. PMID:26628104

  7. Biological assessment: water hyacinth control program for the Sacramento/ San Joaquin River Delta of California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A detailed Biological Assessment was developed for the proposed Areawide Water Hyacinth Control Program to outline the procedures that will be used to control this invasive aquatic plant in the Sacramento/ San Joaquin River Delta, and to help determine if this action is expected to threaten endanger...

  8. Recent morphological changes in the Mekong and Bassac river channels, Mekong delta: The marked impact of river-bed mining and implications for delta destabilisation

    NASA Astrophysics Data System (ADS)

    Brunier, Guillaume; Anthony, Edward J.; Goichot, Marc; Provansal, Mireille; Dussouillez, Philippe

    2014-11-01

    The Mekong delta, in Vietnam, is the world's third largest delta. Densely populated, the delta has been significantly armoured with engineering works and dykes to protect populations and infrastructure from storms, and shrimp farms from saltwater intrusion. Considerable development pressures in Vietnam and in the upstream countries have resulted in the construction of several dams in China and in important channel-bed aggregate extractions especially in Cambodia. The effects of these developments impact the delta dynamics in various ways. In this study, changes in the channel morphology of the Mekong proper and the Bassac, the two main distributaries in the 250 km-long deltaic reach from the Cambodian border to the coast, were analysed using channel depth data for 1998 and 2008. The channels display important and irregular bed changes over the 10-year comparison period, including significant incision and expansion and deepening of numerous pools. The mean depth of both channels increased by more than 1.3 m. Both channels also showed correlative significant bed material losses: respectively 90 million m3 in the Mekong and 110 million m3 in the Bassac over the 10-year period. These important losses over a relatively short period, and weak correlations between bed incision and hydraulic parameters suggest that the marked morphological changes are not in equilibrium with flow and sediment entrainment conditions, and are therefore not related to changes in river hydrology. We claim that aggregate extraction, currently practised on a very large scale in the Mekong delta channels and upstream of the delta, is the main cause of these recent morphological changes. These changes are deemed to contribute actively to rampant bank erosion in the delta as well as to erosion of the Mekong delta shoreline. Other contributory activities include the numerous dykes and embankments. The role of existing dams in bed losses remains unclear in the absence of reliable data on the Mekong

  9. Detection of Area Changes in River Mouthbars at the Mekong River Delta using ALOS/PALSAR data

    NASA Astrophysics Data System (ADS)

    Tanaka, A.; Uehara, K.; Tamura, T.; Saito, Y.

    2011-12-01

    Projected sea-level rise by the year 2100 would be ~1m recently and its negative impact on the coastal zone has been pointed out, particularly for mega-deltas in Asia by the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2007). The relative sea-level rise varies with specific conditions and processes over broad spatial and temporal scales. Therefore, long-term monitoring of geomorphological changes in coastal areas over wide areas is of highly interest and importance for coastal management. However, due to limited data availability and accessibility in developing countries, there is not enough systematic coastal monitoring. The Mekong River Delta is one of typical mega-deltas in Asia, which has a low-lying wide delta-plain located in Cambodia to South Vietnam. Sediment and water discharges of the Mekong River are controlled by the monsoon with high and low discharge in summer (wet season) and winter (dry season), respectively. Therefore, technologies such as SAR (Synthetic Aperture Radar) not affected by the cloud conditions offer potential for monitoring in the monsoon Asia region. In this study, ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) data acquired over a period from December 2006 to January 2011 are analyzed to investigate the relation between the sea level and the shape of mouthbars in the Mekong River. Level-1.0 PALSAR data were processed, coregistered, and geocoded to make SAR backscatter intensity images. River mouthbars with strong backscatter, which is surrounded by the water with weak backscatter, are successfully extracted using a histogram thresholding algorithm. Estimated areas of river mouthbars, which are located at the central part of the delta and openly faced to the South China Sea, gradually increase on an annual time scale. These river mouthbars are growing to the seaward. Besides this overall increasing trend, seasonal variations of areas are observed; these correlate with

  10. Long-term NO2 monitoring by satellite in the Pearl River Delta

    NASA Astrophysics Data System (ADS)

    Li, Long; Shi, Runhe; Liu, Pudong; Zhang, Jie

    2013-09-01

    Recently, the air quality has been continuing to deteriorate and threaten public health in the Pearl River Delta. China, the host country for the 2010 Asian Games, faced the great challenge of air quality issues, particularly in the Pearl River Delta, where the Asian Games were held. The major aim of this study is to reveal the spatial and temporal characteristics of NO2 in the Pearl River Delta during October 2004 to December 2010. The long-term characteristics and variations of the NO2 column concentration before and during the 2010 Asian Games were analyzed by using the NO2 product OMNO2e from the Ozone Monitoring Instrument (OMI). Results show that the annual average of the NO2 column concentration has a significant downward trend from 2005 to 2010 in the Pearl River Delta: the total column concentration of NO2 (TotNO2) in the atmosphere decreased from 9.207×1015 molec/cm2 to 8.173×1015 molec/cm2, with an average annual rate of -2.247%; the tropospheric column concentration of NO2 (TropNO2)decreased from 6.685×1015 molec/cm2 to 5.646×1015 molec/cm2, with an average annual rate of -3.109%. The ratio TropNO2/TotNO2 indicating the amount of NO2 exhausted by human activities also decreased from 0.726 in 2005 to 0.691 in 2010. During the 2010 Asian Games, the weekly average of the TropNO2 in Pearl River Delta was maintained at a low level. The NO2 average distribution in the Pearl River Delta is characterized by the maximum in the geometric center, outwardly smaller, and the shrinking areas with high TropNO2 concentration from 2005 to 2010. Foshan, Jiangmen and Kwangchowan were severely polluted cities during the Games. However, the air quality of the Pearl River Delta was improved compared to its historical periods due to governmental preventive/control measures during the 2010 Asian Games.

  11. [Distribution and sources of polycyclic aromatic hydrocarbons in sediments from rivers of Pearl River Delta and its nearby South China Sea].

    PubMed

    Luo, Xiao-Jun; Chen, She-Jun; Mai, Bi-Xian; Zeng, Yong-Ping; Sheng, Guo-Ying; Fu, Jia-Mo

    2005-07-01

    Polycyclic aromatic hydrocarbons (PAHs) are measured in surface sediments from rivers and estuary of Pearl River Delta and its nearby South China Sea. Total PAH concentration varied from 255.9 - 16 670.3 ng/g and a moderate to low level compare to relevant areas worldwide. The order of PAHs concentration in sediments was: rivers of Pearl River Delta > estuary > South China Sea, and the most significant PAH contamination was at Guangzhou channel of Zhujiang river. A decrease trend for PAHs concentration with distance from estuary to open sea can be sees in South China Sea. Coal and biomass combustion is the major source of PAHs in nearshore of South China Sea, and petroleum combustion is the main source of pyrolytic PAHs in rivers and estuary of Pearl River Delta according to PAHs diagnostic ratios. Petroleum PAHs are revealed have a high contribution to PAHs in Xijiang River, estuary and some stations in Zhujiang River. A comparison of data from study in 1997 with data from present study indicates that there is no clear change in the PAH concentration over time but the source of PAHs in Pearl River Delta have been change from a main coal combustion to petroleum combustion and being reflect in the sediments in rivers and estuary of Pearl River Delta where there have high sedimentation rate.

  12. Hydrological response to climate change for Gilgel Abay River, in the Lake Tana Basin -Upper Blue Nile Basin of Ethiopia.

    PubMed

    Dile, Yihun Taddele; Berndtsson, Ronny; Setegn, Shimelis G

    2013-01-01

    Climate change is likely to have severe effects on water availability in Ethiopia. The aim of the present study was to assess the impact of climate change on the Gilgel Abay River, Upper Blue Nile Basin. The Statistical Downscaling Tool (SDSM) was used to downscale the HadCM3 (Hadley centre Climate Model 3) Global Circulation Model (GCM) scenario data into finer scale resolution. The Soil and Water Assessment Tool (SWAT) was set up, calibrated, and validated. SDSM downscaled climate outputs were used as an input to the SWAT model. The climate projection analysis was done by dividing the period 2010-2100 into three time windows with each 30 years of data. The period 1990-2001 was taken as the baseline period against which comparison was made. Results showed that annual mean precipitation may decrease in the first 30-year period but increase in the following two 30-year periods. The decrease in mean monthly precipitation may be as much as about -30% during 2010-2040 but the increase may be more than +30% in 2070-2100. The impact of climate change may cause a decrease in mean monthly flow volume between -40% to -50% during 2010-2040 but may increase by more than the double during 2070-2100. Climate change appears to have negligible effect on low flow conditions of the river. Seasonal mean flow volume, however, may increase by more than the double and +30% to +40% for the Belg (small rainy season) and Kiremit (main rainy season) periods, respectively. Overall, it appears that climate change will result in an annual increase in flow volume for the Gilgel Abay River. The increase in flow is likely to have considerable importance for local small scale irrigation activities. Moreover, it will help harnessing a significant amount of water for ongoing dam projects in the Gilgel Abay River Basin.

  13. Hydrological Response to Climate Change for Gilgel Abay River, in the Lake Tana Basin - Upper Blue Nile Basin of Ethiopia

    PubMed Central

    Dile, Yihun Taddele; Berndtsson, Ronny; Setegn, Shimelis G.

    2013-01-01

    Climate change is likely to have severe effects on water availability in Ethiopia. The aim of the present study was to assess the impact of climate change on the Gilgel Abay River, Upper Blue Nile Basin. The Statistical Downscaling Tool (SDSM) was used to downscale the HadCM3 (Hadley centre Climate Model 3) Global Circulation Model (GCM) scenario data into finer scale resolution. The Soil and Water Assessment Tool (SWAT) was set up, calibrated, and validated. SDSM downscaled climate outputs were used as an input to the SWAT model. The climate projection analysis was done by dividing the period 2010-2100 into three time windows with each 30 years of data. The period 1990-2001 was taken as the baseline period against which comparison was made. Results showed that annual mean precipitation may decrease in the first 30-year period but increase in the following two 30-year periods. The decrease in mean monthly precipitation may be as much as about -30% during 2010-2040 but the increase may be more than +30% in 2070-2100. The impact of climate change may cause a decrease in mean monthly flow volume between -40% to -50% during 2010-2040 but may increase by more than the double during 2070-2100. Climate change appears to have negligible effect on low flow conditions of the river. Seasonal mean flow volume, however, may increase by more than the double and +30% to +40% for the Belg (small rainy season) and Kiremit (main rainy season) periods, respectively. Overall, it appears that climate change will result in an annual increase in flow volume for the Gilgel Abay River. The increase in flow is likely to have considerable importance for local small scale irrigation activities. Moreover, it will help harnessing a significant amount of water for ongoing dam projects in the Gilgel Abay River Basin. PMID:24250755

  14. Geomorphic evolution of the Lilas River fan delta (Central Evia, Greece), during the Quaternary

    NASA Astrophysics Data System (ADS)

    Karymbalis, Efthimios; Valkanou, Kanella; Tsironis, Giorgos; Tsodoulos, Ioannis; Iliopoulos, George; Tsanakas, Konstantinos; Batzakis, Vasilis

    2015-04-01

    This study deals with the geomorphic evolution of the Lilas river fan delta, which is a late Holocene fan delta with an area of about 25 km2, extended mainly towards the south Evoikos Gulf and a secondary extension of approximately 5 km2 towards the north Evoikos Gulf (Central Evia Isl., Greece). This work has combined field geomorphological mapping with the study of the stratigraphy of late Pleistocene - Holocene deltaic sediments. A detailed geomorphic map at the scale of 1:5,000 has been prepared showing both the deltaic plain and the coastal zone features using GIS techniques. Comparative interpretation of aerial photographs taken in different dates and reliable maps of the last two centuries along with field observations depict recent changes of the delta morphology. Profiles of seven drill cores up to the depth of 70 m, provided by the municipality authorities, were considered in order to study the late Pleistocene - Holocene stratigraphy of the broader fan delta plain. Additionally, two boreholes reaching the depth of 4.75 m were drilled with a portable drilling set. The stratigraphy of the late Holocene sediments was studied in detail and 41 sediment samples, collected from selected sedimentary layers, were analyzed using micropaleontological and grain size analysis methods, while samples were dated using OSL. The study of the stratigraphy of the late Holocene deltaic sediments showed that during this period the sea invaded the area of the northwestern delta and created a shallow open marine environment which at times was disturbed by multiple quiet lagoonal phases of fine sediment deposition. Geomorphological mapping showed that among the most important factor for the recent development of the delta is fluvial sedimentation. The dominant landforms in the deltaic plain are the numerous abandoned palaeochannels. The main channel of the river changed its course several times leading to the building and subsequent abandonment of at least four fan delta lobes

  15. Sediment Bypassing of River Mouths: Mechanisms and Effects on Delta Evolution

    NASA Astrophysics Data System (ADS)

    Nienhuis, J.; Ashton, A. D.; Giosan, L.; Nardin, W.; Fagherazzi, S.

    2014-12-01

    Wave-influenced deltas are shaped by wave-driven transport of river-borne sediments. Near the river mouth, combined jet and wave dynamics, along with morphodynamic feedbacks, control the fraction of sediment transported alongshore by littoral currents that can bypass the river channel. Here we study how different bypassing rates influence large-scale delta evolution and examine the effect of waves and the river mouth jet on alongshore sediment bypassing. First, we use a modified version of the Coastline Evolution Model (CEM) to look at the effects of wave climate, fluvial sediment supply, and alongshore sediment bypassing rates on channel orientation. This modified version of CEM progrades the channel in a direction perpendicular to the local shoreline orientation at the river mouth, allowing feedbacks between alongshore sediment transport and fluvial sediment delivery to steer the river channel. Additionally, we allow a prescribed fraction of littoral sediment to bypass the river mouth. We find that deltas that have a large fluvial sediment flux can orient themselves into the direction of dominant wave approach. Lower fluvial inputs result in channels that are deflected downdrift, with increasing deflection as bypassing is reduced. In contrast, channels do not deflect downdrift (but can reorient themselves updrift for large fluvial fluxes) when full bypassing is allowed. These results demonstrate the importance of river mouth sediment bypassing on delta growth patterns, but, as we explore arbitrary bypassing laws, the simulations cannot help us constrain natural bypassing fluxes. To further investigate the natural extent and mechanisms of bypassing, we use the coupled hydrodynamic and morphodynamic model Delft3D-SWAN. With a simplified shoreface and river channel, the model is able to construct river mouth morphology from the combined action of alongshore transport and a river mouth jet. Exploring river mouth morphology and sediment bypassing under various wave

  16. Estimation of evaporation over the upper Blue Nile basin by combining observations from satellites and river flow gauges

    NASA Astrophysics Data System (ADS)

    Allam, Mariam M.; Jain Figueroa, Anjuli; McLaughlin, Dennis B.; Eltahir, Elfatih A. B.

    2016-02-01

    Reliable estimates of regional evapotranspiration are necessary to improve water resources management and planning. However, direct measurements of evaporation are expensive and difficult to obtain. Some of the difficulties are illustrated in a comparison of several satellite-based estimates of evapotranspiration for the Upper Blue Nile (UBN) basin in Ethiopia. These estimates disagree both temporally and spatially. All the available data products underestimate evapotranspiration leading to basin-scale mass balance errors on the order of 35 percent of the mean annual rainfall. This paper presents a methodology that combines satellite observations of rainfall, terrestrial water storage as well as river-flow gauge measurements to estimate actual evapotranspiration over the UBN basin. The estimates derived from these inputs are constrained using a one-layer soil water balance and routing model. Our results describe physically consistent long-term spatial and temporal distributions of key hydrologic variables, including rainfall, evapotranspiration, and river-flow. We estimate an annual evapotranspiration over the UBN basin of about 2.55 mm per day. Spatial and temporal evapotranspiration trends are revealed by dividing the basin into smaller subbasins. The methodology described here is applicable to other basins with limited observational coverage that are facing similar future challenges of water scarcity and climate change.

  17. Assessment of climate change impact on hydrological extremes in two source regions of the Nile River Basin

    NASA Astrophysics Data System (ADS)

    Taye, M. T.; Ntegeka, V.; Ogiramoi, N. P.; Willems, P.

    2011-01-01

    The potential impact of climate change was investigated on the hydrological extremes of Nyando River and Lake Tana catchments, which are located in two source regions of the Nile River basin. Climate change scenarios were developed for rainfall and potential evapotranspiration (ETo), considering 17 General Circulation Model (GCM) simulations to better understand the range of possible future change. They were constructed by transferring the extracted climate change signals to the observed series using a frequency perturbation downscaling approach, which accounts for the changes in rainfall extremes. Projected changes under two future SRES emission scenarios A1B and B1 for the 2050s were considered. Two conceptual hydrological models were calibrated and used for the impact assessment. Their difference in simulating the flows under future climate scenarios was also investigated. The results reveal increasing mean runoff and extreme peak flows for Nyando catchment for the 2050s while unclear trend is observed for Lake Tana catchment for mean volumes and high/low flows. The hydrological models for Lake Tana catchment, however, performed better in simulating the hydrological regimes than for Nyando, which obviously also induces a difference in the reliability of the extreme future projections for both catchments. The unclear impact result for Lake Tana catchment implies that the GCM uncertainty is more important for explaining the unclear trend than the hydrological models uncertainty. Nevertheless, to have a better understanding of future impact, hydrological models need to be verified for their credibility of simulating extreme flows.

  18. Dispersal of larval suckers at the Williamson River Delta, Upper Klamath Lake, Oregon, 2006-09

    USGS Publications Warehouse

    Wood, Tamara M.; Hendrixson, Heather A.; Markle, Douglas F.; Erdman, Charles S.; Burdick, Summer M.; Ellsworth, Craig M.; Buccola, Norman L.

    2012-01-01

    An advection/diffusion modeling approach was used to simulate the transport of larval suckers from spawning areas in the Williamson River, through the newly restored Williamson River Delta, to Upper Klamath Lake. The density simulations spanned the years of phased restoration, from 2006/2007 prior to any levee breaching, to 2008 when the northern part of the delta was reconnected to the lake, and 2009 when levees on both sides of the delta had been breached. Model simulation results from all four years were compared to field data using rank correlation. Spearman ρ correlation coefficients were usually significant and in the range 0.30 to 0.60, providing moderately strong validation of the model. The correlation coefficients varied with fish size class in a way that suggested that the model best described the distribution of smaller fish near the Williamson River channel, and larger fish away from the channel. When Lost River and shortnose/Klamath largescale suckers were simulated independently, the correlation results suggested that the model better described the transport and dispersal of the latter species. The incorporation of night-time-only drift behavior in the Williamson River channel neither improved nor degraded correlations with field data. The model showed that advection by currents is an important factor in larval dispersal.

  19. Chlorinated and polycyclic aromatic hydrocarbons in riverine and estuarine sediments from Pearl River Delta, China.

    PubMed

    Mai, Bi-Xian; Fu, Jia-Mo; Sheng, Guo-Ying; Kang, Yue-Hui; Lin, Zheng; Zhang, Gan; Min, Yu-Shuan; Zeng, Eddy Y

    2002-01-01

    Spatial distribution of chlorinated hydrocarbons [chlorinated pesticides (CPs) and polychlorinated biphenyls (PCBs)] and polycyclic aromatic hydrocarbons (PAHs) was measured in riverine and estuarine sediment samples from Pearl River Delta, China, collected in 1997. Concentrations of CPs of the riverine sediment samples range from 12 to 158 ng/g, dry weight, while those of PCBs range from 11 to 486 ng/g. The CPs concentrations of the estuarine sediment samples are in the range 6-1658 ng/g, while concentrations of PCBs are in the range 10-339 ng/g. Total PAH concentration ranges from 1168 to 21,329 ng/g in the riverine sediment samples, whereas the PAH concentration ranges from 323 to 14,812 ng/g in the sediment samples of the Estuary. Sediment samples of the Zhujiang River and Macao harbor around the Estuary show the highest concentrations of CPs, PCBs, and PAHs. Possible factors affecting the distribution patterns are also discussed based on the usage history of the chemicals, hydrologic condition, and land erosion due to urbanization processes. The composition of PAHs is investigated and used to assess petrogenic, combustion and naturally derived PAHs of the sediment samples of the Pearl River Delta. In addition, the concentrations of a number of organic compounds of the Pearl River Delta samples indicate that sediments of the Zhujiang river and Macao harbor are most likely to pose biological impairment.

  20. Changing river courses in the western part of the Ganga-Brahmaputra delta

    NASA Astrophysics Data System (ADS)

    Rudra, Kalyan

    2014-12-01

    The Ganga-Brahmaputra delta is the largest on Earth, the product of two of the world's largest and siltiest rivers. It is formed in a basin located over the zone where the Indian plate subducts beneath the Himalaya to the north and the Indo-Burman ranges to the east. The distributaries in the south-western part of the delta remain disconnected from the Ganga-Padma during the lean season, although they are still active in bank erosion and sediment transport during the monsoon. Four distributaries of the Bhagirathi-Hugli (the westernmost branch of the Ganga) have gone dry during known historical period. In many cases, the natural decay of rivers has been exacerbated by the human intervention, especially where rivers are embanked and no allowance made for their migration through meandering and avulsion. In the coastal zone where mangroves were cleared and creeks were embanked since the late 18th century, decay of channels, and advancement of the sea towards inland have been aggravated. The subsequent attempt of flushing the sediment load to the sea from the estuary to improve the status of navigation in the Bhagirathi-Hugli River was not successful to the level of expectation. This paper deals with the decay and changing courses of rivers in the western part of the Ganga-Brahmaputra delta.

  1. Land use/land cover change in Yellow River Delta, China during fast development period

    NASA Astrophysics Data System (ADS)

    Zhou, Wenzuo; Tian, Yongzhong; Zhu, Lifen

    2007-09-01

    Terrestrial eco-system in coastal zones is unstable and land-use and Land-cover of its land resource are crucial for its sustainability. Therefore it is necessary to understand distribution of land use/cover changes in those tender areas. This paper was to analyze changes of land use/cover in Yellow River Delta in China during recent ten years, which was its fast development period, by remote sensing monitoring. Two Landsat TM images in October of 1995 and 2004 were processed using ERDAS software and supervised classification method in study for the land use and land cover of those two years. The two land use/cover maps were overlaid to discover the changes. It was showed that lots of land use/cover changes in the Yellow River Delta had taken place in past ten years. Because abundant sand that carried by river water filled up at estuary of the Yellow River, new land increased fleetly. The rates that foreshore were turned into fishery land was high for aquaculture with salt water had been developed quickly. Another important effect of human activity was that part of waste land and grassland had been cultivated for crops. With industry and economy development, land for urbanization had been outspreaded. Although fast exploitation had been carried out in Yellow River Delta going though those years, some human activities on land use were inharmonious for sustainable development of land resource in this area. This must be pay attention to by local government and people.

  2. Delta distributary dynamics in the Skagit River Delta (Washington, USA): Extending, testing, and applying avulsion theory in a tidal system

    NASA Astrophysics Data System (ADS)

    Hood, W. Gregory

    2010-11-01

    Analysis of historical aerial photos shows that Skagit Delta (Washington, USA) distributary dynamics are consistent with the Slingerland and Smith model of avulsion dynamics where the ratio of the water surface slopes of the two branches of a bifurcation predicts avulsion stability. This model was extended to predict distributary inlet (upstream) width and bankfull cross-sectional area. The water surface gradient ratio for a bifurcation pair predicted distributary width well; the lowest R2 was 0.61 for the 1937 data points, but R2 ranged from 0.83 to 0.90 for other year-specific regression lines. Gradient ratios were not constant over the historical record; from 1937 to 1972 the mainstem river channel lengthened by 1250 m in the course of marsh progradation, while distributary lengthening was comparatively negligible. Consequently, the gradient advantage of the distributaries increased and their channels widened. After the mainstem river terminus stabilized from 1972 to the present, the distributaries continued to lengthen with marsh progradation, so that distributary gradient advantage steadily declined and the distributaries narrowed. While distributary cross sections were not available for the historical period, they were surveyed in 2007 near the distributary inlets. Gradient ratio was more closely related to distributary inlet bankfull cross-sectional area ( R2 = 0.95) than to minimum distributary width for any photo year examined. Applying this form of analysis to Skagit Delta distributaries that have been dammed in the course of agricultural development suggests that their restoration to stabilize eroding marshes at their outlets and recover salmon migration pathways would be feasible without significant risk of full river avulsion.

  3. Sources, bioavailability, and photoreactivity of dissolved organic carbon in the Sacramento-San Joaquin River Delta

    USGS Publications Warehouse

    Stepanauskas, R.; Moran, M.A.; Bergamaschi, B.A.; Hollibaugh, J.T.

    2005-01-01

    We analyzed bioavailability, photoreactivity, fluorescence, and isotopic composition of dissolved organic carbon (DOC) collected at 13 stations in the Sacramento-San Joaquin River Delta during various seasons to estimate the persistence of DOC from diverse shallow water habitat sources. Prospective large-scale wetland restorations in the Delta may change the amount of DOC available to the food web as well as change the quality of Delta water exported for municipal use. Our study indicates that DOC contributed by Delta sources is relatively refractory and likely mostly the dissolved remnants of vascular plant material from degrading soils and tidal marshes rather than phytoplankton production. Therefore, the prospective conversion of agricultural land into submerged, phytoplankton-dominated habitats may reduce the undesired export of DOC from the Delta to municipal users. A median of 10% of Delta DOC was rapidly utilizable by bacterioplankton. A moderate dose of simulated solar radiation (286 W m-2 for 4 h) decreased the DOC bioavailability by an average of 40%, with a larger relative decrease in samples with higher initial DOC bioavailability. Potentially, a DOC-based microbial food web could support ???0.6 ?? 109 g C of protist production in the Delta annually, compared to ???17 ?? 109 g C phytoplankton primary production. Thus, DOC utilization via the microbial food web is unlikely to play an important role in the nutrition of Delta zooplankton and fish, and the possible decrease in DOC concentration due to wetland restoration is unlikely to have a direct effect on Delta fish productivity. ?? Springer 2005.

  4. Heavy Metals and Biogenic Elements in Aquatic Systems of the Don River Delta

    NASA Astrophysics Data System (ADS)

    Tkachenko, Anna; Tkachenko, Oleg

    2014-05-01

    River deltas are located in the lower parts of the cascade landscape-geochemical systems of the river basins, so their geochemical conditions often characterize the anthropogenic impact on whole river system. The Don River runs through the one of the most agriculturally developed and densely populated area of Russia, and flows into the Azov Sea - the smallest and shallowest sea in the world. These factors determine the geochemical features of aquatic systems of the Don River mouth area and the specificity of the "river-sea" geochemical barrier zone. The paper presents results of the field studies of the geochemical structure of the Don River mouth area, which were conducted in frames of the RFBR project in 2012-2013. Major types of the deltaic water streams and bodies were studied in different hydrological seasons: spring floods, summer, autumn and winter low water periods. About 50 samples of water, suspended matter and 60 samples of bottom sediments have been collected and analyzed for heavy metals (Fe, Mn, Zn, Cu, Ni, Co, Pb, Cr, Cd etc.) and biogenic elements (nitrate, nitrite, ammonium, phosphates, silica, total nitrogen and phosphorus, dissolved oxygen and chlorophyll) content. To assess the toxicity degree and nutrient potential of water, bioassay test conducted by growing daphnia in water samples were held. The study shows that the Don River delta water is characterized by the relatively low values of dissolved heavy metal content. Significantly higher values of heavy metals were determined in the vicinity of settlements only. Metal accumulation in bottom sediments can be associated mainly with the rate of water flow. Higher values were found in sediments of small channels with weak flow velocity and prevailing processes of the suspended matter deposition. The data on the seasonal dynamics of nutrients and spatial variability of their forms have been obtained. The maximum concentration of nitrogen, phosphorus, silicon, and other biogenic elements are

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

    USGS Publications Warehouse

    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.

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

    USGS Publications Warehouse

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

    2012-01-01

    The U.S. Geological Survey Forecast Mekong project is providing technical assistance and information to aid management decisions and build science capacity of institutions in the Mekong River Basin. A component of this effort is to produce a synthesis of the effects of dams and other engineering structures on large-river hydrology, sediment transport, geomorphology, ecology, water quality, and deltaic systems. The Mississippi River Basin (MRB) of the United States was used as the backdrop and context for this synthesis because it is a continental scale river system with a total annual water discharge proportional to the Mekong River, has been highly engineered over the past two centuries, and the effects of engineering have been widely studied and documented by scientists and engineers. The MRB is controlled and regulated by dams and river-engineering structures. These modifications have resulted in multiple benefits including navigation, flood control, hydropower, bank stabilization, and recreation. Dams and other river-engineering structures in the MRB have afforded the United States substantial socioeconomic benefits; however, these benefits also have transformed the hydrologic, sediment transport, geomorphic, water-quality, and ecologic characteristics of the river and its delta. Large dams on the middle Missouri River have substantially reduced the magnitude of peak floods, increased base discharges, and reduced the overall variability of intraannual discharges. The extensive system of levees and wing dikes throughout the MRB, although providing protection from intermediate magnitude floods, have reduced overall channel capacity and increased flood stage by up to 4 meters for higher magnitude floods. Prior to major river engineering, the estimated average annual sediment yield of the Mississippi River Basin was approximately 400 million metric tons. The construction of large main-channel reservoirs on the Missouri and Arkansas Rivers, sedimentation in dike

  7. Flooding the Colorado River Delta: A Landscape-Scale Experiment

    NASA Astrophysics Data System (ADS)

    Flessa, Karl W.; Glenn, Edward P.; Hinojosa-Huerta, Osvel; Parra-Rentería, Carlos A.; Ramírez-Hernández, Jorge; Schmidt, John C.; Zamora-Arroyo, Francisco A.

    2013-12-01

    A large pulse of water is planned to be released into the dry Colorado River channel in Mexico. This engineered experimental spring flood, which will flow from Lake Mead and pass through downstream reservoirs, is the culmination of decades of applied research. The pulse flow is a rare opportunity for research at the landscape scale [Glenn et al., 2013].

  8. Land subsidence at aquaculture facilities in the Yellow River delta, China

    NASA Astrophysics Data System (ADS)

    Higgins, Stephanie; Overeem, Irina; Tanaka, Akiko; Syvitski, James P. M.

    2013-08-01

    Differential Interferometric Synthetic Aperture Radar is applied to the coast of the Yellow River delta (YRD) in China. Like many deltas, the coastline of the YRD is dominated by aquaculture. Advanced Land Observation Satellite Phased Array L-Band Synthetic Aperture Radar (SAR) and Envisat Advanced SAR data acquired between 2007 and 2011 show that subsidence rates are as high as 250 mm/y at aquaculture facilities, likely due to groundwater pumping. These rates exceed local and global average sea level rise by nearly 2 orders of magnitude and suggest that subsidence and associated relative sea level rise may present a significant hazard for Asian megadeltas.

  9. 2500 years of changing shoreline accretion rates at the mouths of the Mekong River delta

    NASA Astrophysics Data System (ADS)

    Besset, Manon; Tamura, Toru; Anthony, Edward; Brunier, Guillaume; Saito, Yoshiki; Dussouillez, Philippe; Lap Nguyen, Van; Ta, Oahn

    2016-04-01

    The Mekong River delta prograded rapidly in a relatively sheltered bight in the South China Sea under the influence of high fluvial sediment supply 5300 to 3500 years ago, developing from an estuary into a delta. This >200 km seaward growth resulted in increasing exposure of the delta to ocean waves that led to a more wave-influenced mode of progradation characterized by the construction of numerous sets of beach ridges in the eastern sector of the delta, which shows a system of multiple distributary mouths. The growth pattern of this river-mouth sector over the last 2500 years has been determined from OSL dating of these beach-ridge deposits, while the most up-to-date trends (1950-2014) have been highlighted from the analysis of maps and satellite images. The OSL ages show that the area of the delta in the mouths sector remained nearly constant till about 500 yr BP, following which significant accretion occurred, possibly in response to changes in catchment land-use and monsoon rainfall and attendant river water and sediment discharge. A fine-tuned analysis of changes since 1950 shows dominant but fluctuating accretion, with two periods of erosion. The first (1965-1973) occurred in the course of the second Indochina war, and the second more recently from 2003 to 2011, followed by mild recovery between 2011 and 2014. These fluctuations most likely reflect changes in sediment supply caused by the vicissitudes of war and its effect on vegetation cover, as well as variations in monsoon rainfall and discharge, and, for the most recent period, massive sand mining in the river and deltaic channels. Accretion of the mouths sector has gone apace, over the same recent multi-decadal period, with large-scale erosion of the muddy shores of the delta in the western South China Sea and the Gulf of Thailand, thus suggesting that the mouths sector may be increasingly sequestering sediment to the detriment of the rest of the delta shoreline. The accretion in the mouths sector is

  10. Quantifying the transition from fluvial- to wave-dominance for river deltas with multiple active channels

    NASA Astrophysics Data System (ADS)

    Nienhuis, J.; Ashton, A. D.; Giosan, L.

    2012-12-01

    The plan-view morphologies of fluvial- and wave-dominated deltas are clearly distinctive, but transitional forms are numerous. A quantitative, process-based description of this transition remains unexplored, particularly for river deltas with multiple active channels. Previous studies focused on general attributes of the fluvial and marine environment, such as the balance between wave energy and river discharge. Here, we propose that the transition between fluvial and wave dominance is directly related to the magnitude of the fluvial bedload flux to the nearshore region versus the alongshore sediment transport capacity of waves removing sediment away from the mouth. In the case of a single-channel delta, this balance can be computed for a given distribution of waves approaching shore. Fluvial dominance occurs when fluvial sediment input exceeds the wave-sustained maximum alongshore sediment transport for all potential shoreline orientations both up- and downdrift of the river mouth. However, deltaic channels have the tendency to bifurcate with increasing fluvial strength. Initial bifurcation splits the fluvial sediment flux among individual channels, while the potential sediment transport by waves remains constant for both river mouths. At higher bifurcation orders, multiple channels interact with each other alongshore, a situation more complicated than the single channel case and one that cannot be simple addressed analytically. We apply a model of plan-view shoreline evolution to simulate the evolution of a deltaic environment with multiple active channels. A highly simplified fluvial domain is represented by deposition of sediment where channels meet the coast. We investigate two scenarios of fluvial delivery. The first scenario deposits fluvial sediment alongshore on a self-similar predefined network of channels. We analyze the effects of different network geometrical parameters, such as bifurcation length, bifurcation angle, and sediment partitioning. In the

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

    USGS Publications Warehouse

    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

  12. Dam Removal as Nearshore Restoration - Patterns and Processes of the Elwha River Delta

    NASA Astrophysics Data System (ADS)

    Warrick, J. A.; Gelfenbaum, G.; Johannessen, J.; Beirne, M.; Winter, B.

    2005-12-01

    Dams on the Elwha River of the Olympic Peninsula have reduced sediment transport in the river for almost a century. Following dam removal, which is slated to begin in 2008, over 14 million cubic meters of mixed grain-size sediments will be exposed in the former reservoirs, much of which will erode and transport to the Strait of Juan de Fuca. Increased supply of sediment to the strait, may end, or perhaps reverse, the current trend of erosion along the river delta and adjacent shoreline. Here we describe the history of shoreline evolution along the Elwha River delta and detail monitoring plans to track nearshore changes following dam removal. Historic data document a general trend of erosion along the delta resulting in a net loss of approx. 65,000 sq. meters of land between 1926 and 1995, although variability in erosion rates is observed over both space and time. Continued monitoring of the shoreface is planned by both U.S. Geological Survey (USGS) and Lower Elwha Klallam Tribe (LEKT) scientists. USGS scientists have also implemented a research program that includes beach and nearshore mapping, process (wave and current) monitoring, and numerical modeling of sediment dispersal. Here we will present preliminary results of this work including high-resolution seabed maps of bathymetry and sediment type and changes in the nearshore bathymetry and beach topography from semi-annual mapping using RTK GPS technologies.

  13. Impacts of urbanization on hydrology in the Yangtze River Delta, China.

    PubMed

    Youpeng, Xu; Jintao, Xu; Jinjia, Ding; Ying, Chen; Yixing, Yin; Xingqi, Zhang

    2010-01-01

    The Yangtze River Delta is one of the most developed regions in China and the rapid development of urbanization have greatly influenced regional hydrology and water resources. Taking several typical urbanizing areas in the Yangtze River Delta as examples, this paper probes into the impacts of urbanization on hydrologic cycle and hydrological process with the support of RS, GIS and hydrological model. The research centers on the impacts of urbanization on precipitation, hydrological process, river networks, and water environment in some typical cities. The results show that: (1) Urban rain island effect is not evident when the process of urbanization is slow, while the differences of annual precipitation and flood season precipitation between urban and suburban areas increased to a certain extent in the booming stage of urbanization. (2) The annual runoff depth and the runoff coefficient increased with the development of urbanization, and the effect will be more notable when the urban areas expand to a certain size; (3) River network systems, especially low-grade rivers have been greatly destroyed in the process of urbanization, which increases the risk of flood and water degradation, so it is very important to protect natural river systems. Based on the results, some proposals of sustainable utilization and protection of water resources is also addressed.

  14. How Does the Morphology of Shelf-Margin Deltas Relate to Sea-Level Elevation? Clues From the Modern Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Ghoshal, S.; Bart, P. J.

    2005-12-01

    Scientists have attempted to precisely determine eustatic changes using various techniques. One of these is the sequence stratigraphic technique which relies on vertical changes in the position of coastal onlap (Vail et al, 1977). In subsequent years, several authors have recognized many limitations in this approach (Christie-Blick et al., 1990). Our ongoing study focuses on the possibility of using the morphology of modern and ancient shelf-margin deltas as sea-level indicators to determine past sea-level elevations. The Mississippi River Delta provides an excellent opportunity to study the precise relationship between shelf-edge delta morphology and sea-level elevation. A morphological analysis of the modern Mississippi River Delta suggests that there may be a direct relationship between the sea-level and the offlap break features of the delta. The offlap break is defined at the intersection of topset and foreset at the location of a marked increase in slope. At this point, the bathymetric curvature (i.e. second derivative of sea-floor) is highest. This is analogous to O'Grady and Syvitski (2002) definition of shelf break offshore Greenland. More than a hundred bathymetric cross sections were made across the modern Balize lobe of the Mississippi River Delta using Rivertools software. The geomorphic analysis showed that there were two distinct morphologic types of the delta. In one type, there is a sharp transition from the topset to the foreset, whereas in a second type, the topset-foreset transition is gradual. It was observed that sharp offlap breaks characterize the eastern part of the delta at water depths of 1 ± 0.3 m. The southern and southwestern parts of the delta are characterized by gradual offlap breaks at water depths of 4 ± 2 m.

  15. Basin-Scale Exports vs. Coastal Delivery of Carbon, Nutrients and Particulates Above and Below Arctic River Deltas

    NASA Astrophysics Data System (ADS)

    Striegl, R. G.; Tank, S. E.; Weeks, G.; Holmes, R. M.; McClelland, J. W.

    2014-12-01

    Recent studies have substantially improved our understanding of water, sediment and materials exports by arctic rivers. Seasonality of exports, particularly during the spring freshet, is better quantified, as are the inland sources of water and sediment discharge and the source and chemical character of other material exports, including carbon and nutrients. Measurements on small rivers discharging directly to the Arctic Ocean and lacking complex deltas can accurately quantify local inputs to coastal regions. However, the majority of hydrologic inputs to the Arctic Ocean derive from 6 major Eurasian and North American rivers. Water, sediment, and chemical exports from these rivers are typically measured above head of tide, far inland, and commonly above large river deltas. These deltas settle particles and provide favorable environments for deposition, storage, and biogeochemical consumption, production, and transformation of aquatic carbon and nutrients. Consequently, basin exports measured above river deltas likely misrepresent actual delivery to coastal regions. In addition to accumulating sediment, observed and modeled arctic delta effects include enrichment of the organic content of suspended solids, increased dissolved organic carbon and nitrogen (DOC; DON) concentration, decreased inorganic nutrient concentration, and settling and likely increased bioavailability of particle associated contaminants, such as mercury. Increased DOC concentration in the Mackenzie River delta has also been associated with a change in DOC quality, with increased potential for biodegradation of DOC and decreased potential for photodegradation of DOC from head of tide to within the delta. For the most part, assessments of differences between head of tide basin exports and coastal delivery tend to be qualitative rather than quantitative, largely because of difficulties quantifying tidally affected flow. This points to the need to resolve data gaps, improve quantitative assessments

  16. The combined impact on the flooding in Vietnam's Mekong River delta of local man-made structures, sea level rise, and dams upstream in the river catchment

    NASA Astrophysics Data System (ADS)

    Le, Thi Viet Hoa; Nguyen, Huu Nhan; Wolanski, Eric; Tran, Thanh Cong; Haruyama, Shigeko

    2007-01-01

    The Mekong River delta plays an important role in the Vietnamese economy and it has been severely impacted during this century by a series of unusually large floods. In the dry season the delta is also impacted by salinity intrusion and tides. These effects have caused severe human hardship. To mitigate these impacts, a large number of engineering structures, primarily dykes and weirs, have been built in the delta in recent years and are still being built, mainly to control floods and saltwater intrusion. These control measures are still being upgraded. A GIS-linked numerical model shows that the flood levels in the delta depend on the combined impacts of high river flows in the Mekong River, storm surges, sea level rise, and the likely, future siltation of the Mekong Estuary resulting from the construction of dams in China as well as many other dams proposed throughout the remaining river catchment. The model suggests that the engineering structures in the delta increase the flow velocities in the rivers and canals, increasing bank erosion, and cause the water to be deeper in the rivers and canals. This increases flooding in the non-protected areas of the delta and increases the risk of catastrophic failure of the dykes in the protected areas. The model also predicts that a sea level rise induced by global warming will enhance flooding in the Mekong River delta in Vietnam, and that flooding may worsen in the long term as a result of estuarine siltation resulting from the construction of dams. At the scale of the Mekong River basin, a multinational water resources management plan is needed that includes the hydrological needs of the delta. At the scale of the delta, a compromise is needed between allowing some flooding necessary for agriculture and preventing catastrophic flooding to alleviate human suffering.

  17. DELTAE

    SciTech Connect

    Ward, W.C. )

    1993-11-01

    In thermoacoustic engines and refrigerators, and in many simple acoustic systems, a one dimensional wave equation determines the spatial dependence of the acoustic pressure and velocity. DELTAE numerically integrates such wave equations in the acoustic approximation, in gases or liquids, in user-defined geometries. Boundary conditions can include conventional acoustic boundary conditions of geometry and impedance, as well as temperature and thermal power in thermoacoustic systems. DELTAE can be used easily for apparatus ranging from simple duct networks and resonators to thermoacoustic engines refrigerators and combinations thereof. It can predict how a given apparatus will perform, or can allow the user to design an apparatus to achieve desired performance. DELTAE views systems as a series of segments; twenty segment types are supported. The purely acoustic segments include ducts and cones, and lumped impedances including compliances, series impedances, and endcaps. Electroacoustics tranducer segments can be defined using either frequency-independent coefficients or the conventional parameters of loudspeaker-style drivers: mass, spring constant, magnetic field strength, etc. Tranducers can be current driven, voltage driven, or connected to an electrical load impedance. Thermoacoustic segment geometries include parallel plates, circular and rectangular pores, and pin arrays. Side branches can be defined with fixed impedances, frequency-dependent radiation impedances, or as an auxiliary series of segments of any types. The user can select working fluids from among air, helium, neon, argon, hydrogen, deuterium, carbon dioxide, nitrogen, helium-argon mixtures, helium-xenon mixtures, liquid sodium, and eutectic sodium-potassium. Additional fluids and solids can be defined by the user.

  18. Decades of Change on the Ganges-Brahmaputra Delta; Rivers, Coastlines, Agriculture and Development

    NASA Astrophysics Data System (ADS)

    Small, C.; Sousa, D.; Chiu, S.; Mondal, D. R.; Steckler, M. S.; Akhter, S. H.; Mia, B.; Goodbred, S. L., Jr.; Wilson, C.; Seeber, L.

    2014-12-01

    The Ganges-Brahmaputra delta (GBD) is formed by the convergence of two great rivers, superlative in both size and geologic activity. The GBD is home to > 150 million people with a mean population density of more than 1000 people/km2. The fertile soils, abundant water and favorable climate also make the delta one of the most agriculturally diverse and productive areas on Earth. We seek to better understand the coupled natural and anthropogenic dynamics of the delta through a number of cross-disciplinary field studies of the contributing geophysical, biophysical and anthropogenic processes. To provide a synoptic multitemporal perspective for these studies, we use a variety of remotely sensed observations collected over the delta since 1988. In this overview we provide a synthesis of recent results from studies of 4 interrelated processes; river channel migration, coastal erosion and deposition, co-evolution of agriculture and aquaculture, and economic development. In each study we use multi-sensor spatiotemporal analysis of remotely sensed imagery spanning more than 2 decades to observe and quantify a variety of processes at multiple spatial and temporal scales. MODIS Enhanced Vegetation Index (EVI) composites provide 16 day temporal and 250m spatial resolution of the entire delta from 2000 to present. This image time series captures not only agricultural phenology over the entire delta but also the development of aquaculture on the lower delta and interannual fluvial dynamics on both the Ganges and Brahmaputra rivers. Landsat TM, ETM+ and OLI allow us to represent land cover as continuous fields of soil and sediment substrate, vegetation and dark surfaces (water and shadow) throughout the delta since 1988. Despite its irregular temporal sampling, Landsat's 30 m pixels better resolve both natural and anthropogenic land cover units and its longer time series extends retrospective analyses back to 1988. More recent sensors like Ikonos, Quickbird, GeoEye and World

  19. Late Pleistocene and Holocene environments in the Nile basin

    NASA Astrophysics Data System (ADS)

    Williams, Martin A. J.

    2009-10-01

    Owing to the very gently sloping nature of the flood plain in the lower White Nile valley, which is underlain by a former lake-bed, the depositional record in that area is unusually well preserved. In Egypt and along the Blue Nile phases of erosion have destroyed segments of the sedimentary record, but the White Nile sequence is a good proxy for both the main Nile and the Blue Nile. During the last 15 ka, at least, times of high flow in the Blue Nile and main Nile were synchronous with those in the White Nile. Not all the White Nile flood deposits have been preserved but calibrated radiocarbon dates obtained on fossil freshwater and amphibious Pila shells and fish bones indicate that White Nile levels were high around 14.7-13.1 ka, 9.7-9.0 ka, 7.9-7.6 ka, 6.3 ka and 3.2-2.8 ka. The Blue Nile record is more fragmentary and that of the main Nile even more so except for the Holocene Nile delta. Calibrated radiocarbon ages for high Blue Nile flows indicate very high flood levels towards 13.9-13.2 ka, 8.6 ka, 7.7 ka and 6.3 ka. Incision by the Blue Nile and main Nile has caused progressive incision in the White Nile amounting to at least 4 m since the terminal Pleistocene ˜ 15 ka ago and at least 2 m over the past 9 ka. The Blue Nile seems to have cut down at least 10 m since ˜ 15 ka and at least 4 m since 9 ka. The time-transgressive and relatively late inception of plant domestication in the Nile valley may partly reflect this history of incision. Nile incision would propagate upstream into the White Nile valley, draining previously swampy areas along the valley floor, which would then become accessible to cultivation.

  20. Assessing Subaqueous Mudflow Hazard on the Mississippi River Delta Front, Part 1: A Historical Perspective on Mississippi River Delta Front Sedimentation

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Subaqueous mudflows are known to be ubiquitous across the Mississippi River delta front (MRDF) and have been identified as a hazard to offshore infrastructure. Among other factors, sediment accumulation rates and patterns play an important role in governing the stability of delta front sediment. High sedimentation rates result in underconsolidation, slope steepening, and increased biogenic gas production, which are all known to decrease stability. Sedimentation rates are highly variable across the MRDF, but are highest near the mouth of Southwest Pass, which carries the largest percentage of Mississippi River sediment into the Gulf of Mexico. Since the 1950s, the sediment load of the Mississippi River has decreased by ~50% due to dam construction upstream. The impact of this decreased sediment load on MRDF mudflow dynamics has yet to be examined. We compiled MRDF bathymetric datasets, including historical charts, industry and academic surveys, and NOAA data, collected between 1764 and 2009, in order to identify historic trends in sedimentation patterns. The progradation of Southwest Pass (measured at 10 m depth contour) has slowed from ~66 m/yr between 1764 and 1940 to ~25 m/yr between 1940 and 1979, with evidence of further deceleration from 1979-2009. Decreased rates of progradation are also observed at South Pass and Pass A Loutre. Advancement of the delta also decelerated in deeper water (15-90 m) offshore from Southwest Pass. In this area, from 1940-1979, depth contours advanced seaward ~25 m/yr, but did not advance from 1979-2005. Furthermore, over the same area and time ranges, the sediment accumulation rate decreased by ~82%. We expect these sedimentation trends are occurring across the delta front, with potential impacts on spatial and temporal patterns of subaqueous mudflows. The MRDF appears to be entering a phase of decline, which will likely be accelerated by future upstream sediment diversion projects. New geophysical data will be required to assess

  1. The evolution of the River Nile. The buried saline rift lakes in Sudan—I. Bahr El Arab Rift, the Sudd buried saline lake

    NASA Astrophysics Data System (ADS)

    Salama, Ramsis B.

    The River Nile in Sudan, was during the Tertiary, a series of closed lake basins. Each basin occupying one of the major Sudanese rift systems (Salama, 1985a). In this paper evidence is presented for the presence of the buried saline Sudd Lake in Bahr El Arab rift. The thick Tertiary sediments filling the deep grabens were eroded from the elevated blocks; Jebel Marra, Darfur Dome, Nuba Mountains and the Nile-Congo Divide. The thick carbonate deposits existing at the faulted boundaries of Bahr El Arab defines the possible boundaries between the fresh and saline water bodies. The widespread presence of kanker nodules in the sediments was a result of continuous efflorescence, leaching and evaporative processes. The highly saline zone in the central part of the Sudd was formed through the same processes with additional sulphate being added by the oxidation of the hydrogen sulphide gases emanating from the oil fields.

  2. Environmental and eelgrass response to dike removal: Nisqually River Delta (2010–14)

    USGS Publications Warehouse

    Takesue, Renee K.

    2016-10-03

    Restoration of tidal flows to formerly diked marshland can alter land-to-sea fluxes and patterns of accumulation of terrestrial sediment and organic matter, and these tidal flows can also affect existing nearshore habitats. Dikes were removed from 308 hectares (ha) of the Nisqually National Wildlife Refuge on the Nisqually River Delta in south Puget Sound, Washington, in fall 2009 to improve habitat for wildlife, such as juvenile salmon. Ecologically important intertidal and subtidal eelgrass (Zostera marina) beds grow on the north and west margins of the delta. The goal of this study was to understand long-term changes in eelgrass habitat and their relation to dike removal. Sediment and eelgrass properties were monitored annually in May from 2010 to 2014 at two sites on the west side of the Nisqually River Delta along McAllister Creek, a spring-fed creek near two restored tidal channels. In May 2014, the mean canopy height of eelgrass was the same as in previous years in an 8-ha bed extending to the Nisqually River Delta front, but mean canopy height was 20 percent lower in a 0.3-ha eelgrass bed closer to the restored marsh when compared to mean canopy height of eelgrass in May 2010, 6 months after dike removal was completed. Over 5 years, the amount of eelgrass leaf area per square meter (m2) in the 8-ha bed increased slightly, and surface-sediment grain size became finer. In contrast, in the 0.3-ha bed, eelgrass leaf area per m2 decreased by 45 percent, and surface sediment coarsened. Other potential stressors, including sediment pore water reduction-oxidation potential (redox) and hydrogen sulfide (H2S) concentration in the eelgrass rhizosphere, or root zone, were below levels that negatively affect eelgrass growth and therefore did not appear to be environmental stressors on plants. Eelgrass biomass partitioning, though less favorable in the 8-ha eelgrass bed compared to the 0.3-ha one, was well above the critical above-ground to below-ground biomass ratio of

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

    PubMed

    Berg, Michael; Stengel, Caroline; Pham, Thi Kim Trang; Pham, Hung Viet; 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 microg/L in Cambodia (average 217 microg/L) and 1-845 microg/L in southern Vietnam (average 39 microg/L), respectively. It also evaluates the situation in Red River delta where groundwater arsenic concentrations vary from 1-3050 microg/L (average 159 microg/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 microg/g (average 7 microg/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 microg/L have a significantly higher arsenic content than control groups (<50 microg/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.

  4. Environmental and Eelgrass Response to Dike Removal: Nisqually River Delta (2010–14)

    USGS Publications Warehouse

    Takesue, Renee K.

    2016-10-03

    Restoration of tidal flows to formerly diked marshland can alter land-to-sea fluxes and patterns of accumulation of terrestrial sediment and organic matter, and these tidal flows can also affect existing nearshore habitats. Dikes were removed from 308 hectares (ha) of the Nisqually National Wildlife Refuge on the Nisqually River Delta in south Puget Sound, Washington, in fall 2009 to improve habitat for wildlife, such as juvenile salmon. Ecologically important intertidal and subtidal eelgrass (Zostera marina) beds grow on the north and west margins of the delta. The goal of this study was to understand long-term changes in eelgrass habitat and their relation to dike removal. Sediment and eelgrass properties were monitored annually in May from 2010 to 2014 at two sites on the west side of the Nisqually River Delta along McAllister Creek, a spring-fed creek near two restored tidal channels. In May 2014, the mean canopy height of eelgrass was the same as in previous years in an 8-ha bed extending to the Nisqually River Delta front, but mean canopy height was 20 percent lower in a 0.3-ha eelgrass bed closer to the restored marsh when compared to mean canopy height of eelgrass in May 2010, 6 months after dike removal was completed. Over 5 years, the amount of eelgrass leaf area per square meter (m2) in the 8-ha bed increased slightly, and surface-sediment grain size became finer. In contrast, in the 0.3-ha bed, eelgrass leaf area per m2 decreased by 45 percent, and surface sediment coarsened. Other potential stressors, including sediment pore water reduction-oxidation potential (redox) and hydrogen sulfide (H2S) concentration in the eelgrass rhizosphere, or root zone, were below levels that negatively affect eelgrass growth and therefore did not appear to be environmental stressors on plants. Eelgrass biomass partitioning, though less favorable in the 8-ha eelgrass bed compared to the 0.3-ha one, was well above the critical above-ground to below-ground biomass ratio of

  5. Modeling the hydrologic effects of land and water development interventions: a case study of the upper Blue Nile river basin

    NASA Astrophysics Data System (ADS)

    Haregeweyn, Nigussie; Tsunekawa, Atsushi; Tsubo, Mitsuru; Meshesha, Derege; Adgo, Enyew; Poesen, Jean; Schütt, Brigitta

    2014-05-01

    Over 67% of the Ethiopian landmass has been identified as very vulnerable to climate variability and land degradation. These problems are more prevalent in the Upper Blue Nile (UBN, often called Abay) river basin covering a drainage area of about 199,800 km2. The UBN River runs from Lake Tana (NW Ethiopia) to the Ethiopia-Sudan border. To enhance the adaptive capacity to the high climate variability and land degradation in the basin, different land and water management measures (stone/soil bunds, runoff collector trenches, exclosures) have been extensively implemented, especially since recent years. Moreover, multipurpose water harvesting schemes including the Grand Ethiopian Renaissance Dam (GERD, reservoir area of ca. 4000 km2) and 17 other similar projects are being or to be implemented by 2025. However, impact studies on land and water management aspects rarely include detailed hydrological components especially at river basin scale, although it is generally regarded as a major determinant of hydrological processes. The main aim of this study is therefore to model the significance of land and water management interventions in surface runoff response at scale of UBN river basin and to suggest some recommendations. Spatially-distributed annual surface runoff was simulated for both present-day and future (2025) land and water management conditions using calibrated values of the proportional loss model in ArcGIS environment. Average annual rainfall map (1998-2012) was produced from calibrated TRMM satellite source and shows high spatial variability of rainfall ranging between ca. 1000 mm in the Eastern part of the basin to ca. 2000 mm in the southern part of the basin. Present-day land use day condition was obtained from Abay Basin Master Plan study. The future land use map was created taking into account the land and water development interventions to be implemented by 2025. Under present-day conditions, high spatial variability of annual runoff depth was observed

  6. Is It Feasible to Build New Land in the Mississippi River Delta?

    NASA Astrophysics Data System (ADS)

    Kim, Wonsuck; Mohrig, David; Twilley, Robert; Paola, Chris; Parker, Gary

    2009-10-01

    What if the Mississippi River levees were cut below New Orleans? What if much of the water and sediment were allowed to flow out and build new deltas? Could deltaic land loss be reversed, and indeed restored? Using a conservative sediment supply rate and a range of rates of sea level rise and subsidence, a physically based model of deltaic river sedimentation [Kim et al., 2009] predicts that approximately 700-1200 square kilometers of new land (exposed surface and in-channel freshwater habitat) could be built over a century (Figure 1).

  7. Arsenic in benthic bivalves of San Francisco Bay and the Sacramento/San Joaquin River Delta

    USGS Publications Warehouse

    Johns, C.; Luoma, S.N.

    1990-01-01

    Arsenic concentrations were determined in fine-grained, oxidized, surface sediments and in two benthic bivalves, Corbicula sp. and Macoma balthica, within San Francisco Bay, the Sacramento/San Joaquin River Delta, and selected rivers not influenced by urban or industrial activity. Arsenic concentrations in all samples were characteristic of values reported for uncontaminated estuaries. Small temporal fluctuations and low arsenic concentrations in bivalves and sediments suggest that most inputs of arsenic are likely to be minor and arsenic contamination is not widespread in the Bay.

  8. Dispersion mechanisms of a tidal river junction in the Sacramento–San Joaquin Delta, California

    DOE PAGES

    Gleichauf, Karla T.; Wolfram, Philip J.; Monsen, Nancy E.; Fringer, Oliver B.; Monismith, Stephen G.

    2014-12-17

    In 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 Dopplermore » 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). Thus, 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 changing the junction flow phasing.« less

  9. Dispersion mechanisms of a tidal river junction in the Sacramento–San Joaquin Delta, California

    SciTech Connect

    Gleichauf, Karla T.; Wolfram, Philip J.; Monsen, Nancy E.; Fringer, Oliver B.; Monismith, Stephen G.

    2014-12-17

    In 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). Thus, 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 changing the junction flow phasing.

  10. Modern Pearl River Delta and Permian Huainan coalfield, China: A comparative sedimentary facies study

    USGS Publications Warehouse

    Suping, P.; Flores, R.M.

    1996-01-01

    Sedimentary facies types of the Pleistocene deposits of the Modern Pearl River Delta in Guangdong Province, China and Permian Member D deposits in Huainan coalfield in Anhui Province are exemplified by depositional facies of anastomosing fluvial systems. In both study areas, sand/sandstone and mud/mudstone-dominated facies types formed in diverging and converging, coeval fluvial channels laterally juxtaposed with floodplains containing ponds, lakes, and topogenous mires. The mires accumulated thin to thick peat/coal deposits that vary in vertical and lateral distribution between the two study areas. This difference is probably due to attendant sedimentary processes that affected the floodplain environments. The ancestral floodplains of the Modern Pearl River Delta were reworked by combined fluvial and tidal and estuarine processes. In contrast, the floodplains of the Permian Member D were mainly influenced by freshwater fluvial processes. In addition, the thick, laterally extensive coal zones of the Permian Member D may have formed in topogenous mires that developed on abandoned courses of anastomosing fluvial systems. This is typified by Seam 13-1, which is a blanket-like body that thickens to as much as 8 in but also splits into thinner beds. This seam overlies deposits of diverging and converging, coeval fluvial channels of the Sandstone D, and associated overbank-floodplain deposits. The limited areal extent of lenticular Pleistocene peat deposits of the Modern Pearl River Delta is due to their primary accumulation in topogenous mires in the central floodplains that were restricted by contemporaneous anastomosing channels.

  11. Measurement comparison of gas phase pollutants during field campaign in Pearl River Delta, China

    NASA Astrophysics Data System (ADS)

    Shao, M.; Zeng, L.; Hu, M.; Zhang, Y.

    2005-12-01

    Pearl River delta, an economically developed region in Guangdong province China, has been suffering from serious ground-level ozone pollution. To understand the formation mechanisms of the photochemical smog in this area, a field measurement campaign involving 12 separate institutes, was performed from Oct. 1 to Nov. 4, 2004. Measurements of gas phase pollutants, performed by the different research groups using several different methods, were inter-compared. Ambient SO2, O3 and NO were measured by Peking University and Hong Kong Polytechnic University using the same methods: chemiluminescence for NOx, pulsed fluorescence for SO2, and UV photometric method for O3. VOC speciation was accomplished using canister sampling followed by GC-MS measurement by Peking University and on-line GC-FID technology by National Central University in Taiwan. Ambient concentrations of HONO, the photolysis of which is the most important source of OH radical in Pearl River delta, was measured by two wet chemical methods: one from Energy Research Foundation of the Netherlands and one developed in Peking University. Based on these inter-comparisons, the co-variation of O3, NO and VOCs at an urban site and one rural site in Pearl River delta and estimates of the relative contributions to OH production from photolysis of O3, HONO and HCHO will be presented.

  12. Holocene evolution of the Song Hong (Red River) delta system, northern Vietnam

    NASA Astrophysics Data System (ADS)

    Tanabe, Susumu; Saito, Yoshiki; Lan Vu, Quang; Hanebuth, Till J. J.; Lan Ngo, Quang; Kitamura, Akihisa

    2006-05-01

    The Song Hong (Red River) delta, located on the western coast of the Gulf of Bac Bo (Tonkin) in the South China Sea, formed as a result of the Song Hong sediment discharge throughout the Holocene. The river's sedimentary basin upstream from the delta plain is not large. The delta plain comprises emerged tidal/mangrove flats formed during the sea-level highstand at + 2-3 m (6-4 cal. kyr BP) and a beach-ridge strandplain, with straight-to-lobate beach ridges, on the landward and seaward sides of the delta plain, respectively. The delta affords us the opportunity to examine river-mouth morphodynamics comprehensively in relation to sediment discharge and sea-level changes. In this paper, we describe the Holocene evolution of the Song Hong delta system and the river-mouth morphodynamics on the basis of seven sediment cores, each 30-70 m long, taken from the delta plain during 1999-2001 and 101 radiocarbon dates obtained from the core sediments. Sediments from the seven cores, consisting of incised-valley fills since the last glacial maximum, can be divided, in ascending order, into fluvial sediments composed of gravelly sand and mottled clay, tide-influenced estuarine sediments containing shell and wood fragments, and deltaic sediments composed of tide-influenced sand and mud deposits, in which the contents of sand and wood fragments increase upward. By applying sequence stratigraphic concepts, a transgressive surface can be identified at the gravelly sand-mottled clay boundary, and the maximum flooding surface can be identified at the estuarine-deltaic sediments boundary. The lowstand systems tract, transgressive systems tract, and highstand systems tract record ˜15, 15-9, and 9-0 cal. kyr BP, respectively. During the past 9 kyr, the majority of the sediment discharged by the Song Hong accumulated in the incised valley and enhanced progradation at the river mouth. The river mouth prograded from the bay head toward the gulf, and its morphology changed from funnel

  13. Chiral profiling of azole antifungals in municipal wastewater and recipient rivers of the Pearl River Delta, China.

    PubMed

    Huang, Qiuxin; Wang, Zhifang; Wang, Chunwei; Peng, Xianzhi

    2013-12-01

    Enantiomeric compositions and fractions (EFs) of three chiral imidazole (econazole, ketoconazole, and miconazole) and one chiral triazole (tebuconazole) antifungals were investigated in wastewater, river water, and bed sediment of the Pearl River Delta, South China. The imidazole pharmaceuticals in the untreated wastewater were racemic to weakly nonracemic (EFs of 0.450-0.530) and showed weak enantioselectivity during treatment in the sewage treatment plant. The EFs of the dissolved azole antifungals were usually different from those of the sorbed azoles in the suspended particulate matter, suggesting different behaviors for the enantiomers of the chiral azole antifungals in the dissolved and particulate phases of the wastewater. The azole antifungals were widely present in the rivers. The bed sediment was a sink for the imidazole antifungals. The imidazoles were prevalently racemic, whereas tebuconazole was widely nonracemic in the rivers. Seasonal effects were observed on distribution and chirality of the azole antifungals. Concentrations of the azole antifungals in the river water were relatively higher in winter than in spring and summer while the EF of miconazole in the river water was higher in summer. The mechanism of enantiomeric behavior of the chiral azole antifungals in the environment warrants further research.

  14. Connecting the historic 2011 Mississippi River flood to marsh sedimentation on the Delta

    NASA Astrophysics Data System (ADS)

    Lutken, C.; D'Emidio, M.; Falcini, F.; Horton, B. P.; Jerolmack, D. J.; Khan, N. S.; Li, C.; Macelloni, L.; McKee, K. L.

    2011-12-01

    The 2011 Mississippi River flood was arguably the largest in history. Although the massive inundation resulting from the flood was devastating for residents on the Delta, sediment carried to sea by the swollen river had the potential to combat wetland loss in some areas. There is currently much debate regarding how, and to what degree, sediment from the Mississippi and Atchafalaya Rivers contributes to maintaining and building fragile coastal marshes. This historic flood presented a rare and time-sensitive opportunity to determine the impact of a geologically-significant flood event on coastal sedimentation patterns and rates. We present a multi-disciplinary and multi-institutional effort to use the 2011 Mississippi flood to connect the dots between river dynamics, coastal dynamics, and marsh maintenance. We performed a coupled satellite analysis, boat survey and surface sediment sampling approach to characterize if and how sediments from this historic flood contributed to deposition and maintenance of Mississippi Delta coastal marshes. Sea surface temperature, height and color from satellite data have been used to track mixing and transport of river plume sediments; the boat survey measured the currents and sediment concentrations of the Mississippi plume in-situ during the peak of the flood; and a helicopter survey sampled marsh sediments after the flood subsided, allowing determination of flood-induced deposition rates and also sediment provenance. Preliminary results show that the Mississippi River injected sediment into the Gulf and did not contribute greatly to wetland development because of its narrow, focused jet. The Atchafalaya River plume spread diffusely across the landscape, and sediments reaching the sea were trapped within the coastal zone because the weak jet was incapable of penetrating the coastal current. Significant sedimentation occurred around the Atchafalaya, demonstrating that the flood contributed to wetland maintenance.

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

    PubMed

    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.

  16. Sediment infilling and wetland formation dynamics in an active crevasse splay of the Mississippi River delta

    USGS Publications Warehouse

    Cahoon, Donald R.; White, David A.; Lynch, James C.

    2011-01-01

    Crevasse splay environments provide a mesocosm for evaluating wetland formation and maintenance processes on a decadal time scale. Site elevation, water levels, vertical accretion, elevation change, shallow subsidence, and plant biomass were measured at five habitats along an elevation gradient to evaluate wetland formation and development in Brant Pass Splay; an active crevasse splay of the Balize delta of the Mississippi River. The processes of vertical development (vertical accretion, elevation change, and shallow subsidence) were measured with the surface elevation table–marker horizon method. There were three distinct stages to the accrual of elevation capital and wetland formation in the splay: sediment infilling, vegetative colonization, and development of a mature wetland community. Accretion, elevation gain, and shallow subsidence all decreased by an order of magnitude from the open water (lowest elevation) to the forest (highest elevation) habitats. Vegetative colonization occurred within the first growing season following emergence of the mud surface. An explosively high rate of below-ground production quickly stabilized the loosely consolidated sub-aerial sediments. After emergent vegetation colonization, vertical development slowed and maintenance of marsh elevation was driven both by sediment trapping by the vegetation and accumulation of plant organic matter in the soil. Continued vertical development and survival of the marsh then depended on the health and productivity of the plant community. The process of delta wetland formation is both complex and nonlinear. Determining the dynamics of wetland formation will help in understanding the processes driving the past building of the delta and in developing models for restoring degraded wetlands in the Mississippi River delta and other deltas around the world.

  17. Sediment infilling and wetland formation dynamics in an active crevasse splay of the Mississippi River delta

    NASA Astrophysics Data System (ADS)

    Cahoon, Donald R.; White, David A.; Lynch, James C.

    2011-08-01

    Crevasse splay environments provide a mesocosm for evaluating wetland formation and maintenance processes on a decadal time scale. Site elevation, water levels, vertical accretion, elevation change, shallow subsidence, and plant biomass were measured at five habitats along an elevation gradient to evaluate wetland formation and development in Brant Pass Splay; an active crevasse splay of the Balize delta of the Mississippi River. The processes of vertical development (vertical accretion, elevation change, and shallow subsidence) were measured with the surface elevation table-marker horizon method. There were three distinct stages to the accrual of elevation capital and wetland formation in the splay: sediment infilling, vegetative colonization, and development of a mature wetland community. Accretion, elevation gain, and shallow subsidence all decreased by an order of magnitude from the open water (lowest elevation) to the forest (highest elevation) habitats. Vegetative colonization occurred within the first growing season following emergence of the mud surface. An explosively high rate of below-ground production quickly stabilized the loosely consolidated sub-aerial sediments. After emergent vegetation colonization, vertical development slowed and maintenance of marsh elevation was driven both by sediment trapping by the vegetation and accumulation of plant organic matter in the soil. Continued vertical development and survival of the marsh then depended on the health and productivity of the plant community. The process of delta wetland formation is both complex and nonlinear. Determining the dynamics of wetland formation will help in understanding the processes driving the past building of the delta and in developing models for restoring degraded wetlands in the Mississippi River delta and other deltas around the world.

  18. Wetland loss due to land use change in the Lower Paraná River Delta, Argentina.

    PubMed

    Sica, Y V; Quintana, R D; Radeloff, V C; Gavier-Pizarro, G I

    2016-10-15

    Wetland loss is a global concern because wetlands are highly diverse ecosystems that provide important goods and services, thus threatening both biodiversity and human well-being. The Paraná River Delta is one of the largest and most important wetland ecosystems of South America, undergoing expanding cattle and forestry activities with widespread water control practices. To understand the patterns and drivers of land cover change in the Lower Paraná River Delta, we quantified land cover changes and modeled associated factors. We developed land cover maps using Landsat images from 1999 and 2013 and identified main land cover changes. We quantified the influence of different socioeconomic (distance to roads, population centers and human activity centers), land management (area within polders, cattle density and years since last fire), biophysical variables (landscape unit, elevation, soil productivity, distance to rivers) and variables related to extreme system dynamics (flooding and fires) on freshwater marsh conversion with Boosted Regression Trees. We found that one third of the freshwater marshes of the Lower Delta (163,000ha) were replaced by pastures (70%) and forestry (18%) in only 14years. Ranching practices (represented by cattle density, area within polders and distance to roads) were the most important factors responsible for freshwater marsh conversion to pasture. These rapid and widespread losses of freshwater marshes have potentially large negative consequences for biodiversity and ecosystem services. A strategy for sustainable wetland management will benefit from careful analysis of dominant land uses and related management practices, to develop an urgently needed land use policy for the Lower Delta. PMID:27369090

  19. Wetland loss due to land use change in the Lower Paraná River Delta, Argentina.

    PubMed

    Sica, Y V; Quintana, R D; Radeloff, V C; Gavier-Pizarro, G I

    2016-10-15

    Wetland loss is a global concern because wetlands are highly diverse ecosystems that provide important goods and services, thus threatening both biodiversity and human well-being. The Paraná River Delta is one of the largest and most important wetland ecosystems of South America, undergoing expanding cattle and forestry activities with widespread water control practices. To understand the patterns and drivers of land cover change in the Lower Paraná River Delta, we quantified land cover changes and modeled associated factors. We developed land cover maps using Landsat images from 1999 and 2013 and identified main land cover changes. We quantified the influence of different socioeconomic (distance to roads, population centers and human activity centers), land management (area within polders, cattle density and years since last fire), biophysical variables (landscape unit, elevation, soil productivity, distance to rivers) and variables related to extreme system dynamics (flooding and fires) on freshwater marsh conversion with Boosted Regression Trees. We found that one third of the freshwater marshes of the Lower Delta (163,000ha) were replaced by pastures (70%) and forestry (18%) in only 14years. Ranching practices (represented by cattle density, area within polders and distance to roads) were the most important factors responsible for freshwater marsh conversion to pasture. These rapid and widespread losses of freshwater marshes have potentially large negative consequences for biodiversity and ecosystem services. A strategy for sustainable wetland management will benefit from careful analysis of dominant land uses and related management practices, to develop an urgently needed land use policy for the Lower Delta.

  20. Migration patterns of Neolithic settlements on the abandoned Yellow and Yangtze River deltas of China

    NASA Astrophysics Data System (ADS)

    Chen, Zhongyuan; Zong, Yongqiang; Wang, Zhanghua; Wang, Hui; Chen, Jing

    2008-09-01

    Archaeological records of the Neolithic settlements on the eastern China coast between 35°N and 30°N, an area covering the abandoned Yellow River and the Yangtze River delta plains, reveal that Neolithic people moved from the Yellow River basin onto the northern coast for fishing, hunting and dry-land agriculture ~ 7000 yr ago. Marine transgression interrupted their activities on the low-lying (2-5 m in elevation) coastal wetlands between 6000 and 5000 yr ago, after which they reclaimed their land near the river mouths. Their migration routes on the southern Yangtze delta plain indicate another scenario: early Neolithic communities moved onto the plain for wet-rice cultivation. Despite relative sea-level rise from 7000 to 4000 yr ago, a large number of settlements were established on the lowlands between the eastern Chenier Ridges and the western Taihu Lake depression. The Chenier Ridges, with ~ 1.0 m higher topography than the adjacent coastal area, played a role in sheltering the Neolithic people. Subsequently, settlements waned considerably, possibly due to further marine inundation combined with cold climate. The present study shows that migration patterns of the Neolithic settlements are closely associated with a gradually rising sea level between 7000 and 4000 yr ago.

  1. Seasonal sediment transport and deposition in the Rajang River delta, Sarawak, East Malaysia

    NASA Astrophysics Data System (ADS)

    Staub, J. R.; Among, H. L.; Gastaldo, R. A.

    2000-06-01

    The Holocene Rajang River delta plain, which covers an area of 6500 km 2, has developed in a tropical, ever-wet climatic setting. Peat deposits, up to 15 m thick, occur in this delta plain. The tributary system to the delta is about 50,000 km 2 in area. Elevations exceed 2000 m in the drainage basin and hill slopes are steep. Rainfall in the region exceeds 370 cm/year, with highest rainfall levels or the "wet" season being coincident with the December-March monsoon. The monthly drainage-basin discharge is calculated to average about 3600 m 3/s, and the discharge normally ranges from 1000 to 6000 m 3/s. Spring tides in coastal areas range from 2.9 to 5.8 m. Tide data indicate that the tides are semidiurnal with a noticeable diurnal inequality. Vibracores recovered from bar forms in tidally influenced distributary channels contain laminated silts and sand-silt couplets that show evidence of rhythmic heterolithic stratification. Grain-size data indicate that these preserved delta plain siliciclastic sediments are the result of estuarine depositional processes that occur during intervals of reduced rainfall or the "dry" season (April-November). The number of laminae preserved per neap-spring cycle is the highest (≅18-20), and the average thickness is the greatest in the middle part of the delta plain. Distributary channels in this region normally contain low-salinity brackish water to freshwater. Vibracores recovered from delta front and prodelta sediments show evidence of heterolithic stratification, but rhythmicity is absent. Grain-size data indicate that preserved delta front and prodelta sediments are implaced by "wet" season processes (December-March) when fluvial flux and delta-plain erosion are at their maxima. Individual silt laminae and/or silt and sand interbeds are sometimes many centimeters thick, but average about 1 cm. These silt laminae and silt and sand interbeds or varves represent annual sedimentation events. These varves demonstrate that about 24

  2. From the Mountains of the Moon to the Grand Renaissance: misinformation, disinformation and, finally, information for cooperation in the Nile River basin

    NASA Astrophysics Data System (ADS)

    Zaitchik, B. F.; Habib, S.; Anderson, M. C.; Ozdogan, M.

    2012-12-01

    The Nile River basin is shared by 11 nations and approximately 200 million people. Eight of the riparian States are defined as Least Developed Countries by the United Nations, and about 50% of the total basin population lives below the international poverty line. In addition, eight of the eleven countries have experienced internal or external wars in the past 20 years, six are predicted to be water scarce by 2025, and, at present, major water resource development projects are moving forward in the absence of a fully recognized basin-wide water sharing agreement. Nevertheless, the Nile basin presents remarkable opportunities for transboundary water cooperation, and today—notwithstanding significant substantive and perceived disagreements between stakeholders in the basin—this cooperation is beginning to be realized in topics ranging from flood early warning to hydropower optimization to regional food security. This presentation will provide an overview of historic and present challenges and opportunities for transboundary water management in the Nile basin and will present several case studies in which improved hydroclimatic information and communication systems are currently laying the groundwork for advanced cooperation. In this context climate change acts as both stress and motivator. On one hand, non-stationary hydrology is expected to tax water resources in the basin, and it undermines confidence in conventionally formulated water sharing agreements. On the other, non-stationarity is increasingly understood to be an exogenous threat to regional food and water security that will require informed, flexible cooperation between riparian states.

  3. Sea-Floor Mapping and Benthic Habitat GIS for the Elwha River Delta Nearshore, Washington

    USGS Publications Warehouse

    Cochrane, Guy R.; Warrick, Jonathan A.; Sagy, Yael; Finlayson, David; Harney, Jodi

    2008-01-01

    From March 1531, 2005, more than 252 km (19.5 km2) of seafloor offshore of the Elwha River Delta in the central Strait of Juan de Fuca was mapped by the USGS Coastal and Marine Geology Program. The purpose of this nearshore mapping was to (1) obtain high resolution bathymetry and acoustic reflectance properties of the seabed, (2) examine and record geologic characteristics of the seafloor, and (3) construct maps of sea-floor geomorphology and habitat. Substrate distribution was characterized with video-supervised statistical classification of the sonar data. Substrate of the survey was dominated by mixed sand-gravel and sand. Numerous boulder reefs were observed west of the river mouth within Freshwater Bay, whereas the sea-floor immediately adjacent to the river mouth was dominated by sand.

  4. Modern sediment characteristics and accumulation rates from the delta front to prodelta of the Yellow River (Huanghe)

    NASA Astrophysics Data System (ADS)

    Zhou, Liangyong; Liu, Jian; Saito, Yoshiki; Gao, Maosheng; Diao, Shaobo; Qiu, Jiandong; Pei, Shaofeng

    2016-08-01

    Since 1976, the main channel of the Yellow River (Huanghe) has been on the east side of the delta complex, and the river has prograded a broad new delta lobe in Laizhou Bay of the Bohai Sea. In 2012, extensive bathymetric and high-resolution seismic profiles were conducted and sediment cores were collected off the new delta lobe. This study examined delta sedimentation and morphology along a profile across the modern subaqueous Yellow River delta and into Laizhou Bay, by analyzing sediment radionuclides (137Cs, 210Pb and 7Be), sedimentary structure, grain-size composition, organic carbon content, and morphological changes between 1976 and 2012. The change in the bathymetric profile, longitudinal to the river's course, reveals subaqueous delta progradation during this period. The subbottom boundary between the new delta lobe sediment and the older seafloor sediment (before the 1976 course shift) was identified in terms of lithology and radionuclide distributions, and recognized as a downlap surface in the seismic record. The accumulation rate of the new delta lobe sediment is estimated to be 5-18.6 cm year-1 on the delta front slope, 2 cm year-1 at the toe of the slope, and 1-2 cm year-1 in the shelf areas of Laizhou Bay. Sediment facies also change offshore, from alternations of gray and brown sediment in the proximal area to gray bioturbated fine sediment in the distal area. Based on 7Be distribution, the shorter-term deposition rate was at least 20 cm year-1 in the delta front.

  5. Association between annual river flood pulse and paediatric hospital admissions in the Mekong Delta area.

    PubMed

    Phung, Dung; Huang, Cunrui; Rutherford, Shannon; Chu, Cordia; Wang, Xiaoming; Nguyen, Minh

    2014-11-01

    The Mekong Delta is the most vulnerable region to extreme climate and hydrological conditions however the association between these conditions and children's health has been little studied. We examine the association between annual river flood pulse and paediatric hospital admissions in a Vietnam Mekong Delta city. Daily paediatric hospital admissions (PHA) were collected from the City Paediatric Hospital, and daily river water level (RWL) and meteorological data were retrieved from the Southern Regional Hydro-Meteorological Centre from 2008 to 2011. We evaluated the association between annual river flood pulse (>=90th percentile of RWL) and PHA using the Poisson distributed lag model, controlling for temperature, relative humidity, day of week, seasonal and long-term trends. The seasonal pattern of PHA was examined using harmonic and polynomial regression models. The cumulative risk ratios estimated for a 15-day period following an extreme RWL was 1.26 (95%CI, 1.2-1.38) for all age groups, 1.27 (95%CI, 1.23-1.30) for under five-years and 1.15 (95%CI, 1.07-1.20) for school-aged children, 1.24 (95%CI, 1.21-1.27) for all-causes, 1.18 (95%CI, 1.12-1.21) for communicable infection, 1.66 (95%CI, 1.57-1.74) for respiratory infection and 1.06 (95%CI, 1.01-1.1) for other diseases. The peak PHA risk is in the September-October period corresponding to the highest RWL, and the PHA-RWL association was modified by temperature. An increase in PHA is significantly associated with annual river flood, and the pattern of PHA is seasonally correspondent to the RWL. These findings combined with projected changes in climate conditions suggest important implications of climate change for human health in the Mekong Delta region. PMID:25282279

  6. Association between annual river flood pulse and paediatric hospital admissions in the Mekong Delta area.

    PubMed

    Phung, Dung; Huang, Cunrui; Rutherford, Shannon; Chu, Cordia; Wang, Xiaoming; Nguyen, Minh

    2014-11-01

    The Mekong Delta is the most vulnerable region to extreme climate and hydrological conditions however the association between these conditions and children's health has been little studied. We examine the association between annual river flood pulse and paediatric hospital admissions in a Vietnam Mekong Delta city. Daily paediatric hospital admissions (PHA) were collected from the City Paediatric Hospital, and daily river water level (RWL) and meteorological data were retrieved from the Southern Regional Hydro-Meteorological Centre from 2008 to 2011. We evaluated the association between annual river flood pulse (>=90th percentile of RWL) and PHA using the Poisson distributed lag model, controlling for temperature, relative humidity, day of week, seasonal and long-term trends. The seasonal pattern of PHA was examined using harmonic and polynomial regression models. The cumulative risk ratios estimated for a 15-day period following an extreme RWL was 1.26 (95%CI, 1.2-1.38) for all age groups, 1.27 (95%CI, 1.23-1.30) for under five-years and 1.15 (95%CI, 1.07-1.20) for school-aged children, 1.24 (95%CI, 1.21-1.27) for all-causes, 1.18 (95%CI, 1.12-1.21) for communicable infection, 1.66 (95%CI, 1.57-1.74) for respiratory infection and 1.06 (95%CI, 1.01-1.1) for other diseases. The peak PHA risk is in the September-October period corresponding to the highest RWL, and the PHA-RWL association was modified by temperature. An increase in PHA is significantly associated with annual river flood, and the pattern of PHA is seasonally correspondent to the RWL. These findings combined with projected changes in climate conditions suggest important implications of climate change for human health in the Mekong Delta region.

  7. Morphodynamics and Sedimentology of a Falling Stage Sandy Fjord Delta, Goose River, Labrador

    NASA Astrophysics Data System (ADS)

    Slingerland, R.; Edmonds, D. A.; Parsons, D. R.; Best, J. L.; Royce, J.; Burpee, A.; Cederberg, J.; Caldwell, R.; Nijhuis, A.; McGuffin, A.

    2012-12-01

    Sediment size and degree of cohesion are thought to exert a strong control on the morphodynamic processes, planform shape and clinoform stratigraphy of deltas. To test model predictions concerning these two parameters, we present a morphometric and stratigraphic analysis of a sandy delta formed where the Goose River flows into Goose Bay at the western end of Lake Melville, Labrador. Goose River delta sediments consist of arkosic, heavy-mineral-rich sand (D50 = 225 to 600 microns) with very little silt and clay, placing this delta at the coarser-grained, non-cohesive end of the spectrum. The delta started to form approx. 7000 years ago as the Laurentide ice sheet retreated and post-glacial rebound created a relative base level fall of approximately 4 mm/yr. The current tidal range in Goose Bay averages 0.5 m, and the average wave height is negligible. Results from our 2012 field season show that the delta planform consists of two moribund lobes at elevations of ~ 5 m and ~ 2 m and a presently active delta at sea level. Aerial photography from 1951 to 2012 show there has been surprisingly little progradation despite active channel change at the six-month timescale and an assumed base level fall of 244 mm during that period. A topographic section along a dipline consists of three treads and two clinoform risers. The bottomset tread is a virtually featureless fjord bottom at ~35 m from which a first clinoform rises to a second tread at ~-15 m. The second tread is a sandy platform onto which an upper clinoform downlaps. This upper sandy clinoform ranges in dip from 9 to 17 dg. and passes into the topset at an elevation of ~ -1 m. The topset consists of braid-like trapezoidal unit bars that in GPR show little evidence of wave, alongshore current, or ice reworking, even though they are submerged at higher high tides. The planform, bar geometries and facies, and clinoform dips and dip-directions are remarkably consistent with model predictions from Delft3d.

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

    USGS Publications Warehouse

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

    2016-01-01

    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

  9. Geochemical Flows of Heavy Metals in Aquatic Systems of the Volga River Delta

    NASA Astrophysics Data System (ADS)

    Lychagin, Mikhail; Tkachenko, Anna; Kasimov, Nikolay

    2014-05-01

    The paper presents the results of the long-term environmental-geochemical studies of aquatic systems of the Volga River mouth area. It occupies a special place among the world's largest river deltas. The strong interest of researchers from different fields of science in the problems of the Volga River delta is associated with the high rate of periodic fluctuations of the Caspian Sea level, and also many factors of the technogenic geochemical impact on the aquatic systems. They range from the local impact of pollution sources in the delta to the regional impact of pollution sources located upstream. Aquatic systems of the Volga delta are highly diverse in morphology, hydrodynamic regime, lithology, sediments, and biota. This diversity determines the considerable spatial and temporal variability of the conditions of migration of heavy metals (HM) and other chemical elements. The study showed that the present contamination of the aquatic systems is manifested mainly in excess of heavy metals (Cu, Pb, Cd) in suspended matter over the global background values, most notably, in the flood period. In general the content of HM in the water and sediments during the last decades remains low; pollution of the bottom sediments is largely insignificant and of local character. We have identified the significant role of the water plants due to migration and accumulation of heavy metals in the shallow near-shore zones. Higher aquatic plants may serve as biogeochemical indicators of aquatic systems pollution. The metal content in macrophytes varies substantially depending on the ecological and morphological characteristics of species, as well as on conditions of their habitat. The difference between the minimal and maximal HM content may reach two to three orders of magnitude. Thickets of hornweed (Ceratophyllum demersum) and of other macrophytes in the mouths of the watercourses at the near-shore mouth area play the role of the biofilters precipitating a significant part of the

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

    PubMed

    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.

  11. Bioanalytical and instrumental analysis of estrogenic activities in drinking water sources from Yangtze River Delta.

    PubMed

    Hu, Xinxin; Shi, Wei; Cao, Fu; Hu, Guanjiu; Hao, Yingqun; Wei, Si; Wang, Xinru; Yu, Hongxia

    2013-02-01

    The estrogenic activities of source water from Yangtze River, Huaihe River, Taihu Lake and groundwater in Yangtze River Delta in the dry and wet season were determined by use of reporter gene assays based on African green monkey kidney (CV-1) cell lines. Higher estrogenic activities were observed in the dry season, and the estrogenic potentials in water samples from Taihu Lake were greater than other river basins. None of the samples from groundwater showed estrogen receptor (ER) agonist activity. The 17β-Estradiol (E2) equivalents (EEQs) of water samples in the dry season ranged from 9.41×10(-1) to 1.20×10(1) ng E2 L(-1). In the wet season, EEQs of all the water samples were below the detection limit as 9.00×10(-1) ng E2 L(-1) except for one sample from Huaihe River. The highest contribution of E2 was detected in Yangtze River as 99% of estrogenic activity. Nonylphenol (NP, 100% detection rate) and octylphenol (OP, 100% detection rate) might also be responsible for the estrogenic activities in water sources. Potential health risk induced by the estrogenic chemicals in source water may be posed to the residents through water drinking.

  12. Distribution of alkylphenols in the Pearl River Delta and adjacent northern South China Sea, China.

    PubMed

    Chen, Bing; Duan, Jing-Chun; Mai, Bi-xian; Luo, Xiao-Jun; Yang, Qing-Shu; Sheng, Guo-Ying; Fu, Jia-Mo

    2006-04-01

    The occurrence of alkylphenols (APs) was investigated in surface water and sediments from the Pearl River Delta and adjacent northern South China Sea. Most of the water samples contained detectable amounts of APs, ranging up to 0.628 microg l(-1) for nonylphenol (NP) and 0.068 microg l(-1) for octylphenol (OP). APs were found in all of the sediment samples with concentrations ranging from 59 to 7808 microg kg(-1) for NP and from 1 to 93 microg kg(-1) for OP. The Zhujiang River showed the highest concentrations of APs in both water and sediments. Significant decrease of APs concentrations going from the Zhujiang River to the Shiziyang River was observed. The Xijiang River contained concentrations of APs slightly higher in water but relatively lower in sediments than the Lingding Bay, which might be attributed to their different hydrodynamic and sedimentary characteristics. There was a decreasing trend of APs in water from the rivers to the estuary and further to the sea on the whole. In the Lingding Bay and its outer waters, concentrations of APs in sediments increased to a maximum and then decrease seaward, which was consistent with the distribution trend of the sediment organic carbon contents. Linear regression analyses showed the concentrations of APs were markedly correlated with the sediment organic carbon contents, indicating that the sediment organic carbon is an important factor controlling the levels of APs in sediments.

  13. Endocrine-disrupting chemicals in the Pearl River Delta and coastal environment: sources, transfer, and implications.

    PubMed

    Xu, Weihai; Yan, Wen; Huang, Weixia; Miao, Li; Zhong, Lifeng

    2014-12-01

    A study was conducted to investigate the occurrence and behavior of six endocrine-disrupting chemicals (EDCs) in sewage, river water, and seawater from the Pearl River Delta (PRD). The six EDCs under study were 4-nonylphenol (NP), bisphenol A (BPA), 17α-ethynylestradiol (EE2), estrone (E2), 17β-estradiol (E2), and estriol (E3). These EDCs, predominated by BPA, were found in high levels in the influents and the effluents of sewage treatment plants in the area. The relatively high concentrations (0.23-625 ng/L) of the EDCs detected in the receiving river water suggested that the untreated sewage discharge was a major contributor. The EDCs detected in eight outlets of the Pear River and the Pear River Estuary were in the ranges of 1.2-234 and 0.2-178 ng/L, respectively. The estrogen equivalents in the aquatic environments under study ranged from 0.08 to 4.5 ng/L, with E1 and EE2 being the two predominant contributors. As the fluxes of the EDCs from the PRD region to the nearby ocean are over 500 tons each year, the results of this study point to the potential that Pearl River is a significant source of the EDCs to the local environment there.

  14. On the control of climate- and human-modulated fluvial sediment delivery on river delta development: The Indus

    NASA Astrophysics Data System (ADS)

    Giosan, L.; Clift, P. D.; Blusztajn, J.; Tabrez, A.; Constantinescu, S.; Filip, F.

    2006-12-01

    Deltas are particularly vulnerable coasts, affected by changes in both continental and coastal ocean processes. The currently accelerated loss of deltaic lands across the world is primarily due to fluvial sediment starvation following the pandemic construction of river dams and water diversions. However, the influence on deltas of human- or even climate-modulated changes in fluvial sediment discharge has been studied less comprehensively than other controls e.g., the sea-level rise. We examined the Indus delta to understand how the sediment source (i.e., available fluvial sediment) has affected the development of the sediment sink (i.e., the subaerial and subaqueous delta evolution). With an elevated topography and generally arid climate in the watershed, the Indus has been, in natural conditions (i.e., before dams reduced its flow and sediment discharge by over 80%), one of the most important sediment-producing rivers in the world. Bathymetric data show that the Indus shelf morphology exhibits a compound clinoform morphology. Whereas the inner shoreface-connected clinoform has clearly developed as the subaqueous part of the modern Indus delta, the offshore clinoform is either a relict or a contemporaneous prodelta clinoform. Following the reduction in sediment discharge after the late 1950's, the deltaic shoreline in the central part of the delta coast started to recede providing sediment for the southeastern and northwestern coast sectors that remained largely progradational. This differential behavior of the delta shoreline indicates that even a drastic loss of fluvial sediment is initially buffered by an erosional smoothing of the delta coast. New data from onland drilling shows that unlike most Holocene deltas, the Indus delta prograded through the later part of the deglacial sea level rise, starting no later than 12,000 cal. years BP. Neodymium isotope data indicate that sediments comprising the entire Holocene delta originated predominantly in the monsoon

  15. Beach morphodynamics of the mixed grain-size delta of the dammed Elwha River, Washington

    NASA Astrophysics Data System (ADS)

    Warrick, J. A.; Gelfenbaum, G. R.; George, D. A.; Ruggiero, P.; Kaminsky, G. M.; Beirne, M.; Miller, I. M.

    2009-12-01

    Sediment supply provides a fundamental control on the morphology of river deltas, and humans have significantly modified these supplies for centuries. Here we examine the effects of almost a century of sediment supply reduction from the damming of the Elwha River in Washington on shoreline position and beach morphology of its wave-dominated delta. The mean rate of shoreline erosion during 1939-2006 is ~0.6 m/yr. Shoreline change and morphology differ spatially, however. Negligible shoreline change has occurred updrift (west) of the river mouth, where the beach is mixed sand to cobble, cuspate, and reflective. The beach downdrift (east) of the river mouth has had significant and persistent erosion, but this beach differs in that it has a reflective foreshore with a dissipative low-tide terrace. Erosion of the downdrift beach results from foreshore retreat, which broadens the low-tide terrace with time, and the rate of this kind of erosion has increased significantly from ~0.8 m/yr during 1939-1990 to ~1.4 m/yr during 1990-2006. Erosion rates for the downdrift beach derived from 2004-2007 topographic surveys vary between 0 and 13 m/yr, with an average of 3.8 m/yr. The 2004-2007 surveys also show that most erosion occurs during the winter with lower rates of change in the summer. We note that the low-tide terrace is significantly coarser (mean grain size ~100 mm) than the foreshore (mean grain size ~30 mm), a pattern contrary to the typical observation of fining low-tide terraces in the region and worldwide. Because this cobble low-tide terrace is created by foreshore erosion, has been steady over intervals of at least years, is predicted to have negligible longshore transport compared to the foreshore portion of the beach, and is inconsistent with oral history of abundant shellfish collections from the low-tide beach, we suggest that it is an armored layer of cobble clasts that are not generally competent in the physical setting of the delta. Thus, the cobble low

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

    USGS Publications Warehouse

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

    2012-01-01

    The U.S. Geological Survey Forecast Mekong project is providing technical assistance and information to aid management decisions and build science capacity of institutions in the Mekong River Basin. A component of this effort is to produce a synthesis of the effects of dams and other engineering structures on large-river hydrology, sediment transport, geomorphology, ecology, water quality, and deltaic systems. The Mississippi River Basin (MRB) of the United States was used as the backdrop and context for this synthesis because it is a continental scale river system with a total annual water discharge proportional to the Mekong River, has been highly engineered over the past two centuries, and the effects of engineering have been widely studied and documented by scientists and engineers. The MRB is controlled and regulated by dams and river-engineering structures. These modifications have resulted in multiple benefits including navigation, flood control, hydropower, bank stabilization, and recreation. Dams and other river-engineering structures in the MRB have afforded the United States substantial socioeconomic benefits; however, these benefits also have transformed the hydrologic, sediment transport, geomorphic, water-quality, and ecologic characteristics of the river and its delta. Large dams on the middle Missouri River have substantially reduced the magnitude of peak floods, increased base discharges, and reduced the overall variability of intraannual discharges. The extensive system of levees and wing dikes throughout the MRB, although providing protection from intermediate magnitude floods, have reduced overall channel capacity and increased flood stage by up to 4 meters for higher magnitude floods. Prior to major river engineering, the estimated average annual sediment yield of the Mississippi River Basin was approximately 400 million metric tons. The construction of large main-channel reservoirs on the Missouri and Arkansas Rivers, sedimentation in dike

  17. Environmental Assessments in the Riparian Corridor of the Colorado River Delta

    NASA Technical Reports Server (NTRS)

    2001-01-01

    We will develop remote sensing methods to conduct environmental assessments in the riparian corridor of the Colorado River delta, shared by the United States and Mexico. This important regional ecosystem is dependent upon US water flows, yet the most important wildlife habitats are in Mexico. The delta region is poorly known and difficult to monitor on the ground. We will use ground-validated, aerial and satellite methods to develop accurate vegetation and habitat maps and predictive hydrological and vegetation models of this ecosystem in response to US flood releases. The work products will advance our understanding of water resource issues in dryland climates and provide a specific application tool for a critical binational natural resource area.

  18. Hydrogeological and hydrochemical framework of Upper Awash River basin, Ethiopia: With special emphasis on inter-basins groundwater transfer between Blue Nile and Awash Rivers

    NASA Astrophysics Data System (ADS)

    Yitbarek, Andarge; Razack, Moumtaz; Ayenew, Tenalem; Zemedagegnehu, Engida; Azagegn, Tilahun

    2012-04-01

    Integrated approach has been used to investigate the hydrogeological framework of a complex fractured volcanic aquifer system in the Upper Awash River basin located at the western shoulder of the Ethiopian Rift. The groundwater flow system and mechanism of recharge of different aquifers have been studied using conventional hydrogeological field investigations, hydrochemistry, and isotope hydrology. Litho-hydrostratigraphic relationships were constructed from lithologic logs obtained from exploratory drilling of deep boreholes. The result indicates quite complex flow pattern and hydraulic characteristics of the different volcanic aquifers. The litho-hydrostratigraphic correlation indicates that the permeable and porous scoraceous lower basaltic aquifer is extended laterally all the way from the Blue Nile Plateau to the study area. New evidences have also emerged on the inter-basin groundwater transfer. Two distinct regional basaltic aquifers (upper and lower) are identified showing distinct hydrochemical and isotopic signatures. In the southern part of the study area the upper and lower aquifers form one unconfined regional aquifer system. In the northern and central part of the basin, it appears that the two systems are separated by regional aquiclude forming confined aquifers, in places with artesian wells. The groundwater from the deep exploratory wells (>250 m) tapping the lower basaltic aquifer and wells located in the south were found to be moderately mineralized (TDS: 400-600 mg/l), with relatively depleted stable isotope composition and with almost zero tritium. In contrast, the upper shallow aquifer has lesser ionic concentration, more isotopically enriched. Evidences from the different methods clearly indicate inter-basin groundwater transfer from the Blue Nile basin to the Upper Awash basin. The evidences also converge to testify common origin of recharge, presence of hydraulic connectivity for systems tapping the lower basaltic aquifer. This has enormous

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

    PubMed

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

    2013-11-01

    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.

  20. Hydraulic Survey and Scour Assessment of Bridge 524, Tanana River at Big Delta, Alaska

    USGS Publications Warehouse

    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.

  1. Environmental change in the Yangtze River delta since 12,000 years B.P.

    NASA Astrophysics Data System (ADS)

    Liu, Kam-Biu; Sun, Shuncai; Jiang, Xinhe

    1992-07-01

    A 52-m core from Qidong at the tip of the Yangtze River (Chang Jiang) delta provides a history of sea-level change, deltaic development, and vegetational and climatic changes during the last 12,000 yr. About 12,000 yr ago, when sea level was about 60 m below the present level, the coring site was situated in the innermost part of the exposed continental shelf. The late-Pleistocene vegetation on the uplands of the Lower Yangtze River valley was a mixed forest of deciduous and broadleaved evergreen trees in which Betula, Ulmus, Tsuga, and Cupressaceae were slightly more abundant than at present. Abies and Picea were probably present as relict populations on mountains bordering the region. Rapidly rising sea level converted the Qidong area to a coastal or estuarine environment between 11,000 and 10,800 yr B.P., leading to widespread development of wetlands dominated by Gramineae and Cyperaceae. During the next 2500 yr coastal erosion due to marine transgression obliterated the sedimentary record. Deltaic sedimentation predominated from 8300 to 3800 yr B.P., as the Yangtze River delta prograded by successively building a series of estuarine sand bars. During the mid-Holocene, the climate was slightly warmer and more humid than at present, allowing the subtropical broadleaved evergreen trees to increase their populations. Pinus and Quercus became more abundant after 3800 yr B.P. in response to climatic cooling. The present deltaic plain in Qidong formed less than 200 yr ago.

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

    PubMed

    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.

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

    USGS Publications Warehouse

    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.

  4. Refining the link between the Holocene development of the Mississippi River Delta and the geologic evolution of Cat Island, MS: implications for delta-associated barrier islands

    USGS Publications Warehouse

    Miselis, Jennifer L.; Buster, Noreen A.; Kindinger, Jack G.

    2014-01-01

    The geologic evolution of barrier islands is profoundly influenced by the nature of the deposits underlying them. Many researchers have speculated on the origin and evolution of Cat Island in Mississippi, but uncertainty remains about whether or not the island is underlain completely or in part by deposits associated with the past growth of the Mississippi River delta. In part, this is due to a lack of comprehensive geological information offshore of the island that could augment previous stratigraphic interpretations based on terrestrial borings. An extensive survey of Cat Island and its surrounding waters was conducted, including shallow-water geophysics (e.g., high-resolution chirp seismic, side-scan sonar, and swath and single-beam bathymetry) and both terrestrial and marine vibracoring. High-resolution seismic data and vibracores from south and east of the island show two horizontally laminated silt units; marine radiocarbon dates indicate that they are St. Bernard delta complex (SBDC) deposits. Furthermore, seismic data reveal that the SBDC deposits taper off toward the southern shoreline of Cat Island and to the west, morphology consistent with the distal edge of a delta complex. The sedimentology and extent of each unit suggest that the lower unit may have been deposited during an earlier period of continuous river flow while the upper unit may represent reduced or sporadic river flow. OSL dates from the island platform (beneath beach ridge complexes) indicate three stages of terrestrial evolution: island emergence resulting from relative sea-level rise (~ 5400 ybp) island aggradation via littoral transport (~ 2500–4000 ybp) and island degradation due to delta-mediated changes in wave direction (present– ~ 3600 ybp). Finally, the combination of terrestrial and marine data shows that portions of Cat Island that are lower in elevation than the central part of the island are younger and are likely underlain by a thin layer of deltaic sediments. This

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

    USGS Publications Warehouse

    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

  6. Sediment facies, depositional environments, and distribution of phytoclasts in the recent Mahakam River delta, Kalimantan, Indonesia

    SciTech Connect

    Gastaldo, R.A. ); Huc, A.Y. )

    1992-12-01

    The Mahakam River delta is a tide- and wave-dominated delta located on the edge of the Kutei basin, eastern Kalimantan, Borneo. It is a coastal deltaic sequence, Neogene to Holocene in age, from which all recoverable hydrocarbons (crude oil and natural gas) are considered to be derived from kerogen III predecessors. However, a complete understanding of the types of sediments sourcing the hydrocarbons has not yet been achieved. A vibracoring program sampled the principal fine-grained depositional environments in two transects; one within the fluvially-dominated regime, one within the tidally-dominated regime. Ten sedimentary facies are distinguished and phytoclasts have been recovered from all environments of deposition. Canopy parts from the mixed tropical forest community are preserved throughout the delta, whereas dicotyledonous angiosperm mangroves are restricted to the subtidal zone and delta front. Nypa parts are preserved in most depositional environments. In sites where there appears to be an absence of macrodetritus, dispersed cuticle is recoverable. Identifiable plant parts include wood and fibrous tissues, Nypa petioles and leaf laminae, dicotyledonous angiosperm leaves and isolated cuticles, fruits and seeds, roots and rootlets, and moss. Dammar is found either as dispersed resin ducts or amorphous clasts. Additional biotic components found in bedded plant litters include insects, gastropods, bivalves, sand dollars, ostracods, and crabs. Fluvial channels and depositional sites associated with these systems in the delta front can be differentiated from Nypa swamps and mixed tropical hardwood-palm swamps based on their phytological components and accessory biotic elements. 39 refs., 10 figs., 3 tabs.

  7. LANDSCAPE ECOLOGY ASSESSMENT OF THE TENSAS RIVER BASIN, MISSISSIPPI RIVER DELTA REGION, AND GULF OF MEXICO

    EPA Science Inventory

    A group of landscape ecological indicators were applied to biophysical data masked to the Tensas River Basin. The indicators were use to identify and prioritize sources of nutrients in a
    Mississippi River System sub-basin. Remotely sensed data were used for change detection a...

  8. Nesting ecology of Spectacled Eiders Somateria fischeri on the Indigirka River Delta, Russia

    USGS Publications Warehouse

    Pearce, J.M.; Esler, Daniel; Degtyarev, A.G.

    1998-01-01

    In 1994 and 1995 we investigated breeding biology and nest site habitat of Spectacled Eiders on two study areas within the coastal fringe of the Indigirka River Delta, Russia (71??20' N, 150??20' E). Spectacled Eiders were first observed on 6 June in both years and nesting commenced by mid-June. Average clutch size declined with later nest initiation dates by 0.10 eggs per day; clutches were larger in 1994 than 1995 and were slightly larger on a coastal island study area compared to an interior area. Nesting success varied substantially between years, with estimates of 1.6% in 1994 and 27.6% in 1995. Total egg loss, through avian or mammalian predation, occurred more frequently than partial egg loss. Partial egg loss was detected in 16 nests and appeared unrelated to nest initiation date or clutch size. We found no difference among survival rates of nests visited weekly, biweekly, and those at which the hen was never flushed, suggesting that researcher presence did not adversely affect nesting success. A comparison of nine habitat variables within each study area revealed little difference between nest sites and a comparable number of randomly located sites, leading us to conclude that Spectacled Eiders nest randomly with respect to most small scale habitat features. We propose that large scale landscape features are more important indicators of nesting habitat as they may afford greater protection from land-based predators, such as the Arctic Fox. Demographic data collected during this study, along with recent conservation measures implemented by the Republic of Sakha (Yakutia), lead us to conclude that there are few threats to the Indigirka River Delta Spectacled Eider population. Presently, the Indigirka River Delta contains the largest concentration of nesting Spectacled Eiders and deserves continued monitoring and conservation.

  9. Epidemiological investigation of Clonorchis sinensis infection in freshwater fishes in the Pearl River Delta.

    PubMed

    Chen, Daixiong; Chen, Jieyun; Huang, Ji; Chen, Xueying; Feng, Dana; Liang, Baofang; Che, Yuchuan; Liu, Xiaodan; Zhu, Cuihua; Li, Xiaomin; Shen, Haoxian

    2010-09-01

    Pearl River Delta region is a high clonorchiasis-endemic area in China. However, no complete epidemiological data exist regarding its infection in freshwater fishes, an important epidemic factor for Clonorchis sinensis. The present study collected freshwater fishes and shrimps from 32 sites of nine cities in the Pearl River Delta, and the encysted metacercariae of C. sinensis were detected by digesting these specimens with artificial gastric juice. The mean infection rate of freshwater fishes was 37.09% (2,160/5,824) with a mean number of 14.269 encysted metacercariae in every infected fish and 0.460 encysted metacercariae in every gram of fish meat. Of these freshwater fishes, 5,219 were domesticated, and the infection rate was 36.69% with a mean number of 10.743 encysted metacercariae in every infected fish and 0.312 encysted metacercariae in every gram of fish meat; the other 605 were wild, and the infection rate was 40.50% with a mean number of 41.829 encysted metacercariae in every infected fish and 8.812 encysted metacercariae in every gram of fish meat. A total of 228 shrimps were examined, and 3.07% of them were infected with a mean number of 1.00 encysted metacercariae in every infected shrimp. Pseudorasbora parva and Ctenopharyngodon idellus had the highest infection rate and degree of infection in the fishes studied. The results demonstrated a high incidence of C. sinensis infection in freshwater fishes and shrimps within Pearl River Delta region and a great difference in the infection rate among different collection sites and different fish species.

  10. [Regional distribution and ecological risk evaluation of heavy metals in surface sediments from coastal wetlands of the Yellow River Delta].

    PubMed

    Liu, Zhi-Jie; Li, Pei-Ying; Zhang, Xiao-Long; Li, Ping; Zhu, Long-Hai

    2012-04-01

    Characteristics of heavy metal distributions in surface sediments of different areas in the Yellow River Delta coastal wetland are analyzed, and the influences of sediment environment on heavy metal distributions are discussed. Heavy metal pollution and potential ecological risk in surface sediments of the Yellow River Delta coastal wetland are estimated by using Hakanson potential ecological risk (PER) factors method. The analyzed results indicate that the average contents of Hg, Cu, Pb, Zn, Cd and Cr are 0.034, 18.733, 19.393, 65.317, 0.235 and 62.940 microg x g(-1), respectively. The heavy metal distributions vary with regional environment changes. The accumulating index of heavy metals in the current outfall area is the highest of the three regions assigned by author,the second is that of the ancient Yellow River Delta in the north of Shandong province, and the lowest is that of the abandoned delta. Heavy metal distributions in the Yellow River Delta coastal wetland are affected significantly by hydrodynamic system. In addition, the content of clay in surface sediments plays an important role in the distribution and accumulation of heavy metals. The results also suggest that the heavy metal pollution in the Yellow River Delta coastal wetland is in a low pollution level, with a comprehensive pollution index varying from 0.10 to 4.14. And element Cr is the major pollution factor and its average of single pollution index is 0.63. The order of pollution extents of six typical pollutants is Cr > Cu > Zn > Cd > Pb > Hg. The comprehensive potential ecological risk index is between 0.46 and 51.88, indicating a low potential ecological risk. The order of potential ecological risk parameter is Cd > Hg > Cu > Cr > Pb > Zn. Element Cd is also the major factor of potential ecological risks in the Yellow River Delta coastal wetland.

  11. Mississippi River delta mudslides: techniques allow for continued development with reduced risk

    NASA Astrophysics Data System (ADS)

    Handley, Lawrence R.

    1982-09-01

    The Mississippi River delta environment provides all the necessary ingredients to make sediment instability a critical geohazard to be dealt with in a productive oil and gas region. Some of the early development has encountered problems with the unstable sediments as pipelines have been ruptured and platform foundations have been damaged. From experience and surveys, the government agencies and industry involved on the continental shelf are aware of the nature of instability, mechanism of movement, rate of movement and structural failure that can result, and are applying that knowledge to oil and gas exploration, development and to leasing and permitting.

  12. Nature of decadal-scale sediment accumulation on the western shelf of the Mississippi River delta

    NASA Astrophysics Data System (ADS)

    Reide Corbett, D.; McKee, Brent; Allison, Mead

    2006-11-01

    Sediment delivered to coastal systems by rivers (15×10 9 tons) plays a key role in the global carbon and nutrient cycles, as deltas and continental shelves are considered to be the main repositories of organic matter in marine sediments. The Mississippi River, delivering more than 60% of the total dissolved and suspended materials from the conterminous US, dominates coastal and margin processes in the northern Gulf of Mexico. Draining approximately 41% of the conterminous US, the Mississippi and Atchafalaya river system deliver approximately 2×10 8 tons of suspended matter to the northern Gulf shelf each year. Unlike previous work, this study provides a comprehensive evaluation of sediment accumulation covering majority of the shelf (<150 m water depth) west of the Mississippi Delta from 92 cores collected throughout the last 15 years. This provides a unique and invaluable data set of the spatial and modern temporal variations of the sediment accumulation in this dynamic coastal environment. Three types of 210Pb profiles were observed from short cores (15-45 cm) collected on the shelf. Proximal to Southwest Pass in 30-100 m water depths, non-steady-state profiles were observed indicating rapid accumulation. Sediment accumulation rates in this area are typically >2.5 cm yr -1 (>1.8 g cm -2 yr -1). Kasten cores (˜200 cm in length) collected near Southwest Pass also indicate rapid deposition (>4 cm yr -1; >3 g cm -2 yr -1) on a longer timescale than that captured in the box cores. Near shore (<20 m), profiles are dominated by sediments reworked by waves and currents with no accumulation (the exception is an area just south of Barataria Bay where accumulation occurs). The remainder of the shelf (distal of Southwest Pass) is dominated by steady-state accumulation beneath a ˜10-cm thick mixed layer. Sediment accumulation rates for the distal shelf are typically <0.7 cm yr -1 (<0.5 g cm -2 yr -1). A preliminary sediment budget based on the distribution of 210Pb

  13. Impacts of urbanization on river system structure: a case study on Qinhuai River Basin, Yangtze River Delta.

    PubMed

    Ji, Xiaomin; Xu, Youpeng; Han, Longfei; Yang, Liu

    2014-01-01

    Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers. PMID:25116497

  14. Impacts of urbanization on river system structure: a case study on Qinhuai River Basin, Yangtze River Delta.

    PubMed

    Ji, Xiaomin; Xu, Youpeng; Han, Longfei; Yang, Liu

    2014-01-01

    Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers.

  15. Dependence of flow and transport through the Williamson River Delta, Upper Klamath Lake, Oregon, on wind, river inflow, and lake elevation

    USGS Publications Warehouse

    Wood, Tamara M.

    2012-01-01

    The hydrodynamic model of Upper Klamath and Agency Lakes, Oregon, was used to run 384 realizations of a numerical tracer experiment in order to understand the relative effects of wind, lake elevation, and Williamson River inflow on flow and transport (the movement of water and passively transported constituents) through the Williamson River Delta. Significant findings from this study include: * The replacement rate of water increased in Tulana and Goose Bay with increasing lake elevation, Williamson River inflow, and wind speed. * The fraction of Williamson River inflow passing through either side of the Delta increased with lake elevation and Williamson River inflow. * The partial replacement rate of water in Goose Bay with water from the Williamson River increased with wind speed. * The partial replacement rate of water in Tulana with water from the Williamson River decreased with wind speed. * Strong wind forcing at the water surface caused more of the Williamson River inflow to pass through Goose Bay than through Tulana. * Westerly to northwesterly winds result in more of the Williamson River inflow passing through the Goose Bay side of the Delta than through the Tulana side. * Regression models developed from the tracer experiments can be used to quantify the dependencies between transport and the independent variables to obtain rough estimates of useful quantities such as residence time and steady-state solute concentrations.

  16. Spatial distribution and partition of perfluoroalkyl acids (PFAAs) in rivers of the Pearl River Delta, southern China.

    PubMed

    Liu, Baolin; Zhang, Hong; Xie, Liuwei; Li, Juying; Wang, Xinxuan; Zhao, Liang; Wang, Yanping; Yang, Bo

    2015-08-15

    This study investigated the occurrence of perfluoroalkyl acids (PFAAs) in surface water from 67 sampling sites along rivers of the Pearl River Delta in southern China. Sixteen PFAAs, including perfluoroalkyl carboxylic acids (PFCAs, C5-14, C16 and C18) and perfluoroalkyl sulfonic acids (PFSAs, C4, C6, C8 and C10) were determined by high performance liquid chromatography-negative electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS). Total PFAA concentrations (∑ PFAAs) in the surface water ranged from 1.53 to 33.5 ng·L(-1) with an average of 7.58 ng·L(-1). Perfluorobutane sulfonic acid (PFBS), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS) were the three most abundant PFAAs and on average accounted for 28%, 16% and 10% of ∑ PFAAs, respectively. Higher concentrations of ∑ PFAAs were found in the samples collected from Jiangmen section of Xijiang River, Dongguan section of Dongjiang River and the Pearl River flowing the cities which had very well-developed manufacturing industries. PCA model was employed to quantitatively calculate the contributions of extracted sources. Factor 1 (72.48% of the total variance) had high loading for perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), PFBS and PFOS. For factor 2 (10.93% of the total variance), perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUdA) got high loading. The sorption of PFCAs on suspended particulate matter (SPM) increased by approximately 0.1 log units for each additional CF2 moiety and that on sediment was approximately 0.8 log units lower than the SPM logKd values. In addition, the differences in the partition coefficients were influenced by the structure discrepancy of absorbents and influx of fresh river water. These data are essential for modeling the transport and environmental fate of PFAAs.

  17. Trans-African drainage system of the Sahara: Was it the Nile?

    NASA Astrophysics Data System (ADS)

    Burke, Kevin; Wells, Gordon L.

    1989-08-01

    An exciting result of the first spaceborne radar scans of the eastern Sahara has been the recognition of drainage channels buried at depths of several metres below the dry desert sand. We relate these observations to the megageomorphological evolution of Africa and conclude that the"radar river" valleys may have been parts of an old Nile River system rather than courses cut by a postulated westward-flowing trans-African drainage system (TADS) extending from the Red Sea Hills to the Niger Delta.

  18. Distribution, sources, and fluxes of heavy metals in the Pearl River Delta, South China.

    PubMed

    Geng, Junjie; Wang, Yiping; Luo, Hanjin

    2015-12-30

    Riverine samples were collected at various locations in the Pearl River Delta (PRD) to determine the concentrations of heavy metals (Cr, Ni, Cu, Mn, Zn, Cd, and Pb) in time and space and to estimate the fluxes of heavy metals to the coastal waters off South China. Most of the elements exhibit clear temporal and spatial trends. Principal component analysis shows that surface erosion is the major factor affecting metal concentrations in particulates in the PRD. Natural geology is an important source of these heavy metals. The annual fluxes of Cr, Ni, Cu, Mn, Zn, Cd, and Pb in upstream and downstream were 445, 256, 241, 3293, 1279, 12, and 317 t/year and 1823, 1144, 1786, 15,634, 6183, 74, and 2017 t/year, respectively. A comparison indicated that the annual fluxes of Mn accounted for 1.3% of the global river fluxes, whereas other elements contribute <1%. PMID:26555797

  19. Hydrogeochemical assessment of groundwater quality in a river delta using multivariate statistical techniques

    NASA Astrophysics Data System (ADS)

    Matiatos, Ioannis; Paraskevopoulou, Vasiliki; Botsou, Fotini; Dassenakis, Manolis; Lazogiannis, Konstantinos; Ghionis, George; Poulos, Serafim

    2016-04-01

    The knowledge of the factors controlling the regional groundwater quality regime is important for planning and management of the groundwater resources. This work applies conventional hydrogeochemical and multivariate statistical techniques to identify the main factors and mechanisms controlling the hydrogeochemistry of groundwater in the deltaic environment of River Pinios (Thessaly) as well as possible areas of interactions between groundwater and surface water bodies. Hierarchical Cluster Analysis (HCA) and Principal Components Analysis (PCA) are performed using a data set of physical-chemical parameters from surface water and groundwater sites. Through HCA the paper's objective is to group together surface water and groundwater monitoring sites based on similarities in hydrochemistry in order to indicate areas of groundwater-surface water interaction. On the other hand, PCA aims at indicating factors responsible for the hydrogeochemical characteristics of the water bodies in the river delta (e.g., water-rock interaction, seawater intrusion, anthropogenic activities).

  20. Functional Carbon Processing and Its Linkage to Hydrology in Lakes of the Mackenzie River Delta

    NASA Astrophysics Data System (ADS)

    Lesack, L.; Tank, S. E.; Gareis, J.; Chateauvert, C. A.; Squires, M.; Marsh, P.

    2011-12-01

    The circumpolar arctic contains a number of large river deltas that are lake-rich because of thermokarst effects. The Mackenzie Delta is the second largest, containing 45,000 lakes within a floodplain area 1/3rd the size of Switzerland. A 20-year case study has placed the biogeochemistry of these lakes into context via analysis of 40 years of water level records, river-to-lake connectivities, and estimates of annual river-water renewal. The lakes collectively represent gradients from turbid waters to transparent, high dissolved-nutrients to low, low total dissolved organic matter (DOM) to high, high chromophoric-DOM (CDOM) to low, high inorganic content of lake sediments to high organic sediment, and low under-water ultraviolet-irradiance to higher irradiances. Super imposed on these are biotic community production gradients respectively ranging from low production of aquatic bacteria to high, low macrophytes to high, low epiphyton to high, high phytoplankton and epipelon at intermediate flooding-frequencies, low small-bodied zooplankton to high large-bodied, high fish to no fish, and moderate aquatic birds to high. All the above correspond with a gradient of lake flooding regimes with average river-to-lake connection times ranging from >150 days per year in the lowest elevation lakes maintaining near continuous connection with the river over the open-water period to <4.5 days per year in the highest elevation lakes with long and variable disconnection periods from the river. Thermokarst lakes and lake-chain systems represent special cases where lake behaviors may depart from patterns otherwise strongly linked to river-to-lake connection times. Based on work in this system thus far, we propose a new conceptual model of overall carbon processing based on functional groups of organisms and abiotic processes that govern the overall balance between recycling of carbon to the atmosphere as CO2 or CH4, or the accumulation and storage of carbon in lake biomasses, and

  1. Water quality in select regions of Cauvery Delta River basin, southern India, with emphasis on monsoonal variation.

    PubMed

    Solaraj, Govindaraj; Dhanakumar, Selvaraj; Murthy, Kuppuraj Rutharvel; Mohanraj, Rangaswamy

    2010-07-01

    Delta regions of the Cauvery River basin are one of the significant areas of rice production in India. In spite of large-scale utilization of the river basin for irrigation and drinking purposes, the lack of appropriate water management has seemingly deteriorated the water quality due to increasing anthropogenic activities. To assess the extent of deterioration, physicochemical characteristics of surface water were analyzed monthly in select regions of Cauvery Delta River basin, India, during July 2007 to December 2007. Total dissolved solids, chemical oxygen demand, and phosphate recorded maximum levels of 1,638, 96, and 0.43 mg/l, respectively, exceeding the permissible levels at certain sampling stations. Monsoonal rains in Cauvery River basin and the subsequent increase in river flow rate influences certain parameters like dissolved solids, phosphate, and dissolved oxygen. Agricultural runoff from watershed, sewage, and industrial effluents are suspected as probable factors of water pollution. PMID:19496010

  2. Water quality in select regions of Cauvery Delta River basin, southern India, with emphasis on monsoonal variation.

    PubMed

    Solaraj, Govindaraj; Dhanakumar, Selvaraj; Murthy, Kuppuraj Rutharvel; Mohanraj, Rangaswamy

    2010-07-01

    Delta regions of the Cauvery River basin are one of the significant areas of rice production in India. In spite of large-scale utilization of the river basin for irrigation and drinking purposes, the lack of appropriate water management has seemingly deteriorated the water quality due to increasing anthropogenic activities. To assess the extent of deterioration, physicochemical characteristics of surface water were analyzed monthly in select regions of Cauvery Delta River basin, India, during July 2007 to December 2007. Total dissolved solids, chemical oxygen demand, and phosphate recorded maximum levels of 1,638, 96, and 0.43 mg/l, respectively, exceeding the permissible levels at certain sampling stations. Monsoonal rains in Cauvery River basin and the subsequent increase in river flow rate influences certain parameters like dissolved solids, phosphate, and dissolved oxygen. Agricultural runoff from watershed, sewage, and industrial effluents are suspected as probable factors of water pollution.

  3. Geoarchaeological research for Roman waterworks in the Rhine-Meuse river delta, the Netherlands

    NASA Astrophysics Data System (ADS)

    Verhagen, Jan; Kluiving, Sjoerd; van Leeuwen, Liz; Anker, Emiel

    2015-04-01

    It is known that Romans in the Low Countries at the northern margin of their empire were practicing diverse systems of water state management to maintain economic and above all strategic stability. In early Roman period Romans created a shipping route from the Rhine towards the north by digging canals and constructing dams. This was done in order to submit the northern part of Germania through the Waddenzee and the German rivers Eems, Weser and Elbe. During the middle Roman period the Romans had canceled their efforts to submit Germania. In that period we know the River Rhine as the limes, which not only was a borderline of the Roman empire, but can also be seen as a guarded transport route. The research area is situated in the eastern part of the Rhine-Meuse river valley/delta system. The area represents a highly dynamic geological history of erosion and deposition close to the river system's equilibrium point. In order to reconstruct the former landscape and investigate whether traces of Roman waterworks could be indicated or disproved geoarchaeological coring campaigns have been carried out with lithological, textural and palaeoecological analyses. The results of the research presented in this poster will be: 1) Assessment of the condition of the covered Pleistocene sediments in the area, 2) Identification of the buried gullies and levees in the vicinity of the remains of the Roman castellum 'Carvium ad molem', which should have been built at the bifurcation of the delta branches of Rhine and Waal, 3) Chronological control of gullies and levees, 4) Landscape reconstruction in different time periods. Finally based on the geoarchaeological results a comment will be made on the location of the Drusus dam in the study area, the landscape context of the castellum and its position on the apex of the Insula Batavorum.

  4. Hydrogeochemical characteristics of groundwater from the two main aquifers in the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Nguyen, Thuy Thanh; Kawamura, Akira; Tong, Thanh Ngoc; Nakagawa, Naoko; Amaguchi, Hideo; Gilbuena, Romeo

    2014-10-01

    In the Red River Delta, situated in the northern part of Vietnam, nearly its entire population depends solely on groundwater for daily water consumptions. For this reason, groundwater quality assessments must be carefully carried out using hydrogeochemical properties, to ensure effective groundwater resource planning for the Delta’s present and future groundwater use. In this study, the spatial and seasonal changes in the hydrogeochemical characteristics of groundwater in the two main aquifers of the RRD were investigated by analyzing the physicochemical data obtained in 2011 from 31 conjunctive wells in the Delta’s Holocene unconfined aquifer (HUA) and Pleistocene confined aquifer (PCA) using the Piper diagram and the Gibbs diagram. Results of the data analysis show that the groundwater in both aquifers in the upstream area of the delta is dominated by the [Ca2+-HCO3-] water-type, while the [Na+-Cl-] dominates along the middle-stream and downstream areas. Seasonal changes in the hydrogeochemical facies in both aquifers, comparing the results for the dry and the rainy seasons, were detected in about one third of the sampling wells, which were mainly located at the upstream portion of the Delta. The hydrogeochemical facies of HUA were different from that of PCA by about 45% of the sampling wells in both the dry and the rainy seasons, which were found mostly in the upstream and middle-stream areas.

  5. [Relationships between typical vegetations, soil salinity, and groundwater depth in the Yellow River Delta of China].

    PubMed

    Ma, Yu-Lei; Wang, De; Liu, Jun-Min; Wen, Xiao-Hu; Gao, Meng; Shao, Hong-Bo

    2013-09-01

    Soil salinity and groundwater depth are the two important factors affecting the vegetation growth and distribution in the Yellow River Delta. Through field investigation and statistical analysis, this paper studied the relationships between the typical vegetations (Suaeda heteroptera-Tamarix chinensis, Robinia pseudoacacia, Phragmites australis, and cotton) , soil salinity, and groundwater depth in the Delta. In the study area, groundwater depth had significant effects on soil salinity, with the average influence coefficient being 0.327. When the groundwater depth was 0.5-1.5 m, soil salinization was most severe. The vegetation growth in the Delta was poorer, with the NDVI in 78% of the total area being less than 0.4. Groundwater depth and soil salinity had significant effects on the vegetation distribution. Soil salinity had significant effects on the NDVI of R. pseudoacacia, S. heteroptera-T. chinensis, P. australis, and cotton, while groundwater depth had significant effects on the NDVI of S. heteroptera - T. chinensis, but lesser effects on the NDVI of P. australis, cotton and R. pseudoacacia.

  6. Environmental changes monitoring by remote sensing for Danube River Delta, Romania

    NASA Astrophysics Data System (ADS)

    Zoran, Maria

    2003-03-01

    Danube delta, one of the largest European wetlands left, lies predominantly in Romania, being considered a Biosphere Reservation. Environmental impact assessment and detection of spatio-temporal changes is needed for protection, conservation and restoration of the biological diversity specific to this area. Danube Delta wetlands and aquatic ecosystem are increasingly endangered by global or regional environmental changes due to the discharges or deposition of excess nutrients and/or harmful substances, to the reclamation of lands for agriculture, forestry, and engineering of water flows. A multitemporal data set consisting of LANDSAT MSS, TM and SAR-ERS1 images for Romanian Danube River Delta was used for comparing and mapping landcover change via change detection. The main aim of this paper is to conduct a comprehensive analysis based on existing historical and more recent data to establish the link between phytoplankton bloom development and related harmful phenomena in the North-Western part of Black Sea and changes in the Danube watershed (landuse, fertilizer utilization, waste water treatments). Based on satellite data were analyzed some test areas in the vicinity of the Danube mouths where the nutrient concentration were highest, being assimilated with an expected oxygen depletion, sulfate reduction and methanogenesis in the bottom waters and the superficial sediments.

  7. Detection of the Three Gorges Dam influence on the Changjiang (Yangtze River) submerged delta.

    PubMed

    Dai, Zhijun; Liu, James T; Wei, Wen; Chen, Jiyu

    2014-01-01

    While most large river-deltas in the world are facing the risk of subsidence and erosion in the Anthropocene, it is suspected that the Changjiang submerged delta (CSD) could be subjected to the impacts of the world's largest dam, the Three Gorges Dam (TGD). Here we firstly indicate that the CSD went through high accumulation (1958-1978); slight accumulation (1978-1997), slight erosion (1997-2002); and high accumulation (2002-2009), despite the 70% reduction of the sediment load from upstream since the operation of the TGD in 2003. Meanwhile, at the depocenter of the submerged delta, the accumulation maintained a high rate of 10 cm/yr during 1958-2009. This suggests on a longer term, the distal sediment source from the upstream had little effect on the CSD. Within this time frame the changes in the partition of sediment load among the branching channels of the Changjiang Estuary could likely control the shifting of the depocenter of the CSD on a decadal time scale. Episodic extreme floods and storm surges also increased the magnitude of deposition and erosion of the CSD on short-term scales. A re-evaluation of the impacts of TGD on the CSD is urgently needed. PMID:25321660

  8. Constraining rates and trends of historical wetland loss, Mississippi River Delta Plain, south-central Louisiana

    USGS Publications Warehouse

    Bernier, Julie C.; Morton, Robert A.; Barras, John A.

    2006-01-01

    The timing, magnitude, and rate of wetland loss were described for five wetland-loss hotspots in the Terrebonne Basin of the Mississippi River delta plain. Land and water areas were mapped for 34 dates between 1956 and 2004 from historical National Wetlands Inventory (NWI) datasets, aerial photographs, and Landsat Thematic Mapper (TM) satellite images. Since 1956, the emergent land area at the five study areas in south-central Louisiana has decreased by about 50%. Comparison of the water-area curve derived from the 29 TM images with water-level records from the nearby Grand Isle, Louisiana tide gauge (NOS #8761724) clearly shows that changes in land and water areas fluctuate in response to variations in regional water levels. The magnitude of water-area fluctuations decreased from the 1980s to the 1990s as former areas of wet marsh within and immediately adjacent to the wetland-loss hotspots became permanently submerged. The most rapid wetland loss occurred during the late 1960s and 1970s. Peak wetland-loss rates during this period were two to four times greater than both the pre-1970s background rates and the most recent wetland-loss rates. These results provide constraints on predicting future delta-plain wetland losses and identify Landsat TM imagery as an important source for analyzing land- and water-area changes across the entire delta plain.

  9. Detection of the Three Gorges Dam influence on the Changjiang (Yangtze River) submerged delta

    NASA Astrophysics Data System (ADS)

    Dai, Zhijun; Liu, James T.; Wei, Wen; Chen, Jiyu

    2014-10-01

    While most large river-deltas in the world are facing the risk of subsidence and erosion in the Anthropocene, it is suspected that the Changjiang submerged delta (CSD) could be subjected to the impacts of the world's largest dam, the Three Gorges Dam (TGD). Here we firstly indicate that the CSD went through high accumulation (1958-1978) slight accumulation (1978-1997), slight erosion (1997-2002) and high accumulation (2002-2009), despite the 70% reduction of the sediment load from upstream since the operation of the TGD in 2003. Meanwhile, at the depocenter of the submerged delta, the accumulation maintained a high rate of 10 cm/yr during 1958-2009. This suggests on a longer term, the distal sediment source from the upstream had little effect on the CSD. Within this time frame the changes in the partition of sediment load among the branching channels of the Changjiang Estuary could likely control the shifting of the depocenter of the CSD on a decadal time scale. Episodic extreme floods and storm surges also increased the magnitude of deposition and erosion of the CSD on short-term scales. A re-evaluation of the impacts of TGD on the CSD is urgently needed.

  10. Detection of the Three Gorges Dam influence on the Changjiang (Yangtze River) submerged delta.

    PubMed

    Dai, Zhijun; Liu, James T; Wei, Wen; Chen, Jiyu

    2014-10-16

    While most large river-deltas in the world are facing the risk of subsidence and erosion in the Anthropocene, it is suspected that the Changjiang submerged delta (CSD) could be subjected to the impacts of the world's largest dam, the Three Gorges Dam (TGD). Here we firstly indicate that the CSD went through high accumulation (1958-1978); slight accumulation (1978-1997), slight erosion (1997-2002); and high accumulation (2002-2009), despite the 70% reduction of the sediment load from upstream since the operation of the TGD in 2003. Meanwhile, at the depocenter of the submerged delta, the accumulation maintained a high rate of 10 cm/yr during 1958-2009. This suggests on a longer term, the distal sediment source from the upstream had little effect on the CSD. Within this time frame the changes in the partition of sediment load among the branching channels of the Changjiang Estuary could likely control the shifting of the depocenter of the CSD on a decadal time scale. Episodic extreme floods and storm surges also increased the magnitude of deposition and erosion of the CSD on short-term scales. A re-evaluation of the impacts of TGD on the CSD is urgently needed.

  11. Paleocurrent evidence for lateral displacement of the Pliocene Colorado River delta by the San Andreas fault system, southeastern California

    NASA Astrophysics Data System (ADS)

    Winker, Charles D.; Kidwell, Susan M.

    1986-09-01

    More than 600 paleocurrent measurements from fluvial paleochannels of the early Colorado River delta plain, preserved in the Palm Spring Formation in the Fish Creek Vallecito (FCV) section of southern California, indicate that the FCV section was on the Gulf of California (southeastern) flank of the delta plain as recently as 2.8 Ma. These measurements imply ˜130 km of tectonic translation to the northwest since 2.8 Ma, which can be accounted for by the displacement histories of Baja California and component faults of the San Andreas system. Stratigraphic data from the FCV section and other Neogene localities, when plotted on a palinspastic base, indicate (1) marine transgression of a narrow Gulf of California rift basin and Bouse embayment (site of modern lower Colorado River) by 5.5 Ma, and (2) uplift of the Bouse embayment, initiation of the: lower Colorado River, and southward progradation of the delta to essentially its present position by 4 Ma.

  12. Effects of tectonic deformation and sea level on river path selection: Theory and application to the Ganges-Brahmaputra-Meghna River Delta

    NASA Astrophysics Data System (ADS)

    Reitz, Meredith D.; Pickering, Jennifer L.; Goodbred, Steven L.; Paola, Chris; Steckler, Michael S.; Seeber, Leonardo; Akhter, Syed H.

    2015-04-01

    The set of active rivers of the Ganges-Brahmaputra-Meghna (GBM) Delta in Bangladesh overlies an active plate boundary that continually modifies the landscape of the delta by deformation. The response of rivers to spatially variable subsidence, from tectonic tilting or other causes, has been thought to include preferred occupation of regions of higher subsidence. In this paper, we develop further the theoretical framework for analysis of the interplay of tectonics and river dynamics, and apply this model to conditions in the GBM Delta. First, we examine the overall competition between variable subsidence and channel dynamics, and find that tilting in Bangladesh should be strong enough to influence river path selection. We then present new theory for the effect of subsidence that is spatially (not temporally) variable. We find a constant residence timescale on different parts of the delta, and differing frequencies of avulsion to these locations, and describe the effects of incision or floodplain deposition on these quantities. We present estimates of the channel residence timescale of the Jamuna (Brahmaputra) River reconstructed from the lithology, provenance, and dating of sediment cores. We apply our framework to a map of regional subsidence to predict the effects on avulsion for the Jamuna River. Comparison between our predicted (2150 years) and our stratigraphically based estimates of avulsion timescale (1800 years) shows encouraging consistency.

  13. 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

    USGS Publications Warehouse

    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.

  14. Risks posed by trace organic contaminants in coastal sediments in the Pearl River Delta, China.

    PubMed

    Fung, C N; Zheng, G J; Connell, D W; Zhang, X; Wong, H L; Giesy, J P; Fang, Z; Lam, P K S

    2005-10-01

    Local marine environments in China's Pearl River Delta (PRD), the most rapidly developing region in one of the world's fastest growing economies, have been experiencing significant environmental stress during the past decades. This investigation was conducted to determine the status and trends of persistence organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbons (PHCs), polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and dioxin-related compounds in marine sediments collected from sixteen coastal stations in the Pearl River Delta (PRD) in March 2003. Elevated concentrations of PAHs (94-4300 ng/g), PCBs (6.0-290 ng/g), PHCs (14-150 microg/g), and DDTs (1.4-600 ng/g) were detected in sediment samples. In addition, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like activities in the sediment samples were estimated to range from 0.3 to 440 pg TCDD-EQ/g. Sediments collected from Xiashan contained the greatest concentrations of trace organic contaminations amongst all the sampling stations in the present study. The degree of trace organic contamination was, in general, more severe at stations situated along the west shores of the PRD than their counterparts in the east. A preliminary assessment was performed to examine the probable risks to the marine ecosystem due to POPs. The results showed that OC pesticide contamination in the PRD was particularly serious and might pose a threat to the health of the marine inhabitants. PMID:16199239

  15. Natural selection in a bangladeshi population from the cholera-endemic ganges river delta.

    PubMed

    Karlsson, Elinor K; Harris, Jason B; Tabrizi, Shervin; Rahman, Atiqur; Shlyakhter, Ilya; Patterson, Nick; O'Dushlaine, Colm; Schaffner, Stephen F; Gupta, Sameer; Chowdhury, Fahima; Sheikh, Alaullah; Shin, Ok Sarah; Ellis, Crystal; Becker, Christine E; Stuart, Lynda M; Calderwood, Stephen B; Ryan, Edward T; Qadri, Firdausi; Sabeti, Pardis C; Larocque, Regina C

    2013-07-01

    As an ancient disease with high fatality, cholera has likely exerted strong selective pressure on affected human populations. We performed a genome-wide study of natural selection in a population from the Ganges River Delta, the historic geographic epicenter of cholera. We identified 305 candidate selected regions using the composite of multiple signals (CMS) method. The regions were enriched for potassium channel genes involved in cyclic adenosine monophosphate-mediated chloride secretion and for components of the innate immune system involved in nuclear factor κB (NF-κB) signaling. We demonstrate that a number of these strongly selected genes are associated with cholera susceptibility in two separate cohorts. We further identify repeated examples of selection and association in an NF-κB/inflammasome-dependent pathway that is activated in vitro by Vibrio cholerae. Our findings shed light on the genetic basis of cholera resistance in a population from the Ganges River Delta and present a promising approach for identifying genetic factors influencing susceptibility to infectious diseases.

  16. Strain accumulation across the Denali fault in the Delta River canyon, Alaska.

    USGS Publications Warehouse

    Savage, J.C.; Lisowski, M.; Prescott, W.H.

    1981-01-01

    Deformation along the Denali fault in the Delta River canyon was determined from geodetic surveys in 1941/1942, 1970, 1975, and 1979. The data were best for the 1975-79 interval; in that period the average strain accumulation was essentially pure right lateral shear at a rate of 0.6+-0.1 murad/a (a is years) (engineering shear) across a vertical plane striking N87oE. The plane of maximum shear is rotated about 30o countercloskwise from the local strike of the Denali fault but closely coincides with the strike of a major linear segment of the fault that begins 50 km farther W. The deformation between 1941-42 and 1970 is consistent with a similar rate of strain accumulation if one removes the coseismic strain step contributed by the 1964 Alaska earthquake. The 1970-75 deformation is poorly defined owing to uncertainties in the 1970 survey, but the strain accumulation during that period is certainly much less than during the 1975-79 interval. The 1975-79 strain accumulation is interpreted by means of a dislocation model which suggests that the Denali fault in the vicinity of the Delta River Canyon behaves as a leaky transform fault.-Authors

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

    PubMed Central

    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

  18. Inequality and polarization analysis of urban water use in the Yangtze River Delta area, China.

    PubMed

    Zhang, Zhiguo; Shao, Yisheng

    2010-01-01

    Inequality and polarization are terms usually used to describe the overall dispersion of income distribution and the phenomenon of a divided society with a disappearing middle class and increasing rich and poor populations. However, these terms have seldom been used in water sciences. In this paper, the concepts of inequality and polarization are employed to analyze the distribution of urban water use of different cities. Using for reference the conception of Gini coefficient, the EUWU (Equality of Urban Water Use) model is built to analyze the equality of urban water use. And, the PUWU (Polarization of Urban Water Use) model based on exponential functions, which can limit the index of polarization to the range (0, 1) effectively, is built to analyze the polarization of urban water use. Inequality and polarization of resident, industrial and commercial water use in 16 cities in the Yangtze River Delta, the fastest growing region of China, are evaluated using the EUWU model and PUWU model, respectively. The results show that inequality of residential, industrial and commercial water use has decreased by 6.5%, 11.2% and 8.4%, while the index of polarization has increased by 3.9%, 3.8% and 0.1% in Yangtze River Delta area from 2001 to 2006.

  19. Transfer of cadmium from soil to vegetable in the Pearl River Delta area, South China.

    PubMed

    Zhang, Huihua; Chen, Junjian; Zhu, Li; Yang, Guoyi; Li, Dingqiang

    2014-01-01

    The purpose of this study was to investigate the regional Cadmium (Cd) concentration levels in soils and in leaf vegetables across the Pearl River Delta (PRD) area; and reveal the transfer characteristics of Cadmium (Cd) from soils to leaf vegetable species on a regional scale. 170 paired vegetables and corresponding surface soil samples in the study area were collected for calculating the transfer factors of Cadmium (Cd) from soils to vegetables. This investigation revealed that in the study area Cd concentration in soils was lower (mean value 0.158 mg kg(-1)) compared with other countries or regions. The Cd-contaminated areas are mainly located in west areas of the Pearl River Delta. Cd concentrations in all vegetables were lower than the national standard of Safe vegetables (0.2 mg kg(-1)). 88% of vegetable samples met the standard of No-Polluted vegetables (0.05 mg kg(-1)). The Cd concentration in vegetables was mainly influenced by the interactions of total Cd concentration in soils, soil pH and vegetable species. The fit lines of soil-to-plant transfer factors and total Cd concentration in soils for various vegetable species were best described by the exponential equation (y = ax(b)), and these fit lines can be divided into two parts, including the sharply decrease part with a large error range, and the slowly decrease part with a low error range, according to the gradual increasing of total Cd concentrations in soils.

  20. Urban household carbon emission and contributing factors in the Yangtze River Delta, China.

    PubMed

    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.

  1. [Spatiotemporal pattern of carbon sources and sinks in Yangtze River Delta region, China].

    PubMed

    Yi, Bai-lu; Han, Ji; Zhou, Xiang; Yang, Fang; Meng, Xing; Cao, Wu-xing; Huang, Lu-xia; Xiang, Wei-ning

    2015-04-01

    Yangtze River Delta region is the world's sixth and China's largest urban agglomeration. Its rapid and massive urbanization has also caused a series of ecological and environmental impacts. This paper accounted the inventory of carbon sources and sinks in Yangtze River Delta region during 1995-2010 and analyzed their spatiotemporal patterns. It was found that the carbon sinks increased by 9.43 million tons from 1995 to 2010, in which forest ecosystem net production in Zhejiang Province was the largest contributor. The "grain for green" policy implemented since 2003 in China played a significant role in increasing the forest area and the carbon sinks. The carbon sources increased by 327 million tons, and energy consumption and industrial processes based emissions accounted for 96% of total carbon sources in 2010. Due to the large share of manufacturing and heavy industries in economy and their dependence on the high carbon intensity energy, either the amount or the growth speed of carbon emissions in Jiangsu Province was the top one in the whole region. Moreover, because the growth speed of net carbon emissions that occurred upon the built-up land was much faster than the sprawl speed of urban built-up land, the net carbon emission intensity kept increasing in the whole region, in which Jiangsu Province demonstrated the fastest increase.

  2. Natural Selection in a Bangladeshi Population from the Cholera-Endemic Ganges River Delta

    PubMed Central

    Karlsson, Elinor K.; Harris, Jason B.; Tabrizi, Shervin; Rahman, Atiqur; Shlyakhter, Ilya; Patterson, Nick; O'Dushlaine, Colm; Schaffner, Stephen F.; Gupta, Sameer; Chowdhury, Fahima; Sheikh, Alaullah; Shin, Ok Sarah; Ellis, Crystal; Becker, Christine E.; Stuart, Lynda M.; Calderwood, Stephen B.; Ryan, Edward T.; Qadri, Firdausi; Sabeti, Pardis C.; LaRocque, Regina C.

    2015-01-01

    As an ancient disease with high fatality, cholera has likely exerted strong selective pressure on affected human populations. We performed a genome-wide study of natural selection in a population from the Ganges River Delta, the historic geographic epicenter of cholera. We identified 305 candidate selected regions using the Composite of Multiple Signals (CMS) method. The regions were enriched for potassium channel genes involved in cyclic AMP-mediated chloride secretion and for components of the innate immune system involved in NF-κB signaling. We demonstrate that a number of these strongly selected genes are associated with cholera susceptibility in two separate cohorts. We further identify repeated examples of selection and association in an NF-kB / inflammasome-dependent pathway that is activated in vitro by Vibrio cholerae. Our findings shed light on the genetic basis of cholera resistance in a population from the Ganges River Delta and present a promising approach for identifying genetic factors influencing susceptibility to infectious diseases. PMID:23825302

  3. [Spatiotemporal pattern of carbon sources and sinks in Yangtze River Delta region, China].

    PubMed

    Yi, Bai-lu; Han, Ji; Zhou, Xiang; Yang, Fang; Meng, Xing; Cao, Wu-xing; Huang, Lu-xia; Xiang, Wei-ning

    2015-04-01

    Yangtze River Delta region is the world's sixth and China's largest urban agglomeration. Its rapid and massive urbanization has also caused a series of ecological and environmental impacts. This paper accounted the inventory of carbon sources and sinks in Yangtze River Delta region during 1995-2010 and analyzed their spatiotemporal patterns. It was found that the carbon sinks increased by 9.43 million tons from 1995 to 2010, in which forest ecosystem net production in Zhejiang Province was the largest contributor. The "grain for green" policy implemented since 2003 in China played a significant role in increasing the forest area and the carbon sinks. The carbon sources increased by 327 million tons, and energy consumption and industrial processes based emissions accounted for 96% of total carbon sources in 2010. Due to the large share of manufacturing and heavy industries in economy and their dependence on the high carbon intensity energy, either the amount or the growth speed of carbon emissions in Jiangsu Province was the top one in the whole region. Moreover, because the growth speed of net carbon emissions that occurred upon the built-up land was much faster than the sprawl speed of urban built-up land, the net carbon emission intensity kept increasing in the whole region, in which Jiangsu Province demonstrated the fastest increase. PMID:26259436

  4. Transfer of Cadmium from Soil to Vegetable in the Pearl River Delta area, South China

    PubMed Central

    Zhang, Huihua; Chen, Junjian; Zhu, Li; Yang, Guoyi; Li, Dingqiang

    2014-01-01

    The purpose of this study was to investigate the regional Cadmium (Cd) concentration levels in soils and in leaf vegetables across the Pearl River Delta (PRD) area; and reveal the transfer characteristics of Cadmium (Cd) from soils to leaf vegetable species on a regional scale. 170 paired vegetables and corresponding surface soil samples in the study area were collected for calculating the transfer factors of Cadmium (Cd) from soils to vegetables. This investigation revealed that in the study area Cd concentration in soils was lower (mean value 0.158 mg kg−1) compared with other countries or regions. The Cd-contaminated areas are mainly located in west areas of the Pearl River Delta. Cd concentrations in all vegetables were lower than the national standard of Safe vegetables (0.2 mg kg−1). 88% of vegetable samples met the standard of No-Polluted vegetables (0.05 mg kg−1). The Cd concentration in vegetables was mainly influenced by the interactions of total Cd concentration in soils, soil pH and vegetable species. The fit lines of soil-to-plant transfer factors and total Cd concentration in soils for various vegetable species were best described by the exponential equation (), and these fit lines can be divided into two parts, including the sharply decrease part with a large error range, and the slowly decrease part with a low error range, according to the gradual increasing of total Cd concentrations in soils. PMID:25247431

  5. Urban household carbon emission and contributing factors in the Yangtze River Delta, China.

    PubMed

    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

  6. Multibeam Mapping of Active Slope Instability Features: Examples from the Fraser River and Squamish River Deltas, British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Hill, P. R.

    2004-12-01

    Multibeam mapping of the coastal waters of British Columbia has immensly improved our ability to identify and assess submarine landslide and tsunami hazard. This paper will present analysis of high-resolution images of slope instability features from two delta slopes where recent slope failure can be documented through repetitive multibeam mapping and/or comparison with previous single-beam hydrographic soundings. Numerous mass movement features characterize the slope of the Fraser River delta, all the recent features being located at the mouths of distributary channels. Engineering works have maintained the main channel in a fixed position since the 1930's, contributing to over-steepening of the slope and development of a network of submarine channels. Repetitive multibeam mapping shows that recent slope failures have occurred in numerous locations around the main channel lobe, some at the head of a large submarine channel system and others as isolated small failures that form the headwalls of small submarine channels. The scalloped morphology and association with channels, together with volume estimates derived from repetitive multibeam mapping, indicate that these features result from shallow, small volume liquefaction failures. Smaller scale, shallow slides are present on the very shallow water slope area adjacent to the channels, raising the possibility of groundwater seepage as an influence on slope stability. The slide masses from these failures are rapidly transformed into gravity flows that carve the submarine channels. Slides and channels of a similar scale are found at the mouth of a secondary distributary channel and an abandoned distributary channel. The multibeam imagery allows discrimination between recent slide features and relict features, the latter showing infilling or reworking by bottom currents. An area of undulatory seafloor, located on the flank of the main distributary channel lobe, has been cited as a possible creep displacement feature

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

    PubMed

    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

  8. Cryosols of the Northeast Siberian Lena River Delta and its hinterland - genesis and diversity

    NASA Astrophysics Data System (ADS)

    Zubrzycki, Sebastian; Kutzbach, Lars; Pfeiffer, Eva-Maria

    2016-04-01

    The North-Siberian Lena River Delta (LRD) is the largest Arctic delta and an important interface between the Arctic Ocean in the North and the large Siberian land masses in the South. LRD consists not only of Holocene deltaic sediment deposits as a river terrace and the modern active floodplains but also of remnants of the former Pleistocene mainland including large islands of ice-complex sediments and the Arga-Muora-Sise Island, which is composed of pure sand sediments of still debated origin. The highly diverse landscape structure of LRD is reflected by a great variety of permafrost-affected soils (cryosols). This study aims at describing this great cryosol diversity and at analysing the dominant soil-forming processes in this comparatively scarcely studied soil region. The soil development in the investigated continuous permafrost region is limited by the short thawing period of around three months (June to September) and takes place in the shallow (below 1 m) seasonally thawed active layer. The geological parent material plays an important role for the development of soils in the LRD region. The distribution of the various soil types closely follows the pattern of the geomorphic units characterised by differing sedimentation conditions. The properties and genesis of the soils on the Holocene river terrace and the modern floodplains are strongly affected by the enormous amounts of fluvial sediments (about 12 x 106 tons per year) brought by the Lena River into its delta. The fluvial sedimentation together with the also pronounced aeolian sedimentation results in a fast vertical growth of soils. The upward rise of the soil surface leads to an upward movement of the permafrost table resulting in fast incorporation of soil material formed in the supra-permafrost zone into the permafrost. Due to the morphodynamics of ice-wedge polygons and resulting formation of patterned ground with elevated rims and depressed and water-saturated centres, the Holocene river terrace

  9. In situ Detection and Habitat Characteristics Analysis of Anammox Bacteria in Sediments from River-network Area, Yangtze River Delta

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Ruan, X.; Ao, J.; Ma, T.

    2010-12-01

    Anammox (anaerobic ammonium oxidation) is the conversation of NO2-and NH4+ to N2 in anaerobic condition processed by anammox bacteria. Recently, anammox bacteria has been identified in many different freshwater systems around the world. However, Many reports have only focused on the distribution and diversity of anammox bacteria in freshwater systems, little is known about the habitat characteristics of sediments suitable for anammox bacteria. Yangtze River Delta, located in the east of China, has many shallow lakes and river networks. In this study, 41 sediment samples were collected from three typical study areas (shallow lake, regional river and urban rivers) for in situ detection of anammox bacteria and physical-chemical analysis of deposital environment of sediments. Anammox specified sequences were analyzed by PCR amplification of the 16S rRNA from the sediments. Phylogentic analysis revealed that sequences from shallow lakes and regional rivers were related to 'Candidatus Brocadia fulgida', 'Candidatus Brocadia anammoxidans' and 'Candidatus Scalindua', and most of the sequences were affiliated to'Candidatus Brocadia'. No sequence was amplified from urban river's sediments. Principal Components and Classification Analysis (PCCA) of all samples shows that, 13 sites from shallow lake fell in the same set, and 28 samples from the rivers differed from each other. The nitrogen concentration of porewater from the sediments where anammox bacteria were detected in situ are: NH4+-N 6.5~33.71mg/L, NO2--N 0~0.22 mg/L, NO3--N 0.08~3.27mg/L, and the ammonium is the main form of inorganic nitrogen. The total organic carbon (TOC) in porewater varied from 15.07 mg/L to 500.49 mg/L, and the loss on ignition (LOI) in sediments is 3.9%~10.0%. The physical-chemical parameters of deposital environment of urban rivers fell in the former range, but no anammox bacteria was detected from the samples. Further study of the biological characteristics of the bacteria is needed.

  10. Effects of in-channel sand excavation on the hydrology of the Pearl River Delta, China

    NASA Astrophysics Data System (ADS)

    Luo, Xian-Lin; Zeng, Eddy Y.; Ji, Rong-Yao; Wang, Chao-Pin

    2007-09-01

    SummaryThe hydrology and morphology of the Pearl River Delta (PRD; South China) water system has been predominantly dictated by human activities over the last 20 years. Uncontrolled sand excavation occurred in all 324 tributaries, largely to meet the construction needs arising from the rapid economic growth and urbanization in the region. It was estimated that >8.7 × 10 8 m 3 of sand were excavated from 1986 to 2003 based on field surveys of excavating activities and the river hypsography, resulting in average downcutting depths of 0.59-1.73 m, 0.34-4.43 m, and 1.77-6.48 m in the main channels of the West River, North River, and East River (three major water networks in the PRD), respectively. Consequently, the water levels in upstream of the PRD were decreased by 1.59-3.12 m (Sanshui Station). Uneven sand dredging also caused changes in the divided flow ratio (DFR) between various water courses. For example, the DFR increased by 8.8% at the Sanshui Station on the upper part of the North River network from the early 1980s to 1999. DFRs also increased almost 7.7% at the four major runoff outlets in the eastern side of the PRD. As a result, present brackish-water has intruded upward 10-20 km more than in the 1980s. Apparently, there are two sides to the effects of sand excavation. The positive effects are decreased chances of flooding damages, improved navigating conditions, and more water inputs to rapid economically growing regions. The negative effects include increased grade slope and instability of the riverbank, disruption of navigation in upstream dredging pits during dry seasons, and brackish-water intrusion.

  11. Estimating suspended sediment loads in the Pearl River Delta region using sediment rating curves

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wei, Xiaoyan; Jinhai, Zheng; Yuliang, Zhu; Zhang, Yanjing

    2012-04-01

    In this study, sediment rating curves are employed to study the variations in relationships between water discharge and suspended sediment concentration based on the recent 50 years of monthly data set in the three major rivers of the Pearl River Delta. Results show that sediment rating parameters vary with time. The lowest rating coefficient, ln(a), and the highest rating exponent, b, mostly occur in the 1980s, indicating that sediment transport reached its peak in this decade at the same level as water discharge. This upward shift of sediment load is probably caused by exacerbated karst rocky desertification in the upper reaches of the Pearl River. However, since the beginning of the 1990s sediment loads from the Pearl River to its estuary began to show a dramatically decreasing trend, which is attributed mainly to deposition in the reservoirs, leading to an increase of ln(a) and a decrease of b. Furthermore, the sediment rating curve in 1957 to1970 is applied to estimate potential sediment load (1971 to 2006) in the absence of human influences. It is also estimated quantitatively by the sediment rating curves that in the 1980s, the annual sediment load decreased by 7.59×106 t/yr because of natural factors, while sediment increase induced by human activities was 20.07×106 t/yr, which resulted in an actual increased sediment load of 12.47×106 t/yr compared with the reference level in 1957 to 1970. In the last two decades, the difference between measured and estimated sediment loads became considerable, and the annual deficit sharply increased to 26.80×106 t/yr in the 1990s, and 50.46×106 t/yr in the 2000s, indicating that human activities, mainly referring to dam and reservoir construction, play a dominant role in the decrease of sediment load. The decrease in sediment supply from the Pearl River should be paid special attention because it may cause serious impacts on the river delta and the coastal ocean.

  12. A methodological approach to rapid assessment of a river flood in coastal waters. First test in the Po River delta

    NASA Astrophysics Data System (ADS)

    Campanelli, Alessandra; Bellafiore, Debora; Bensi, Manuel; Bignami, Francesco; Caccamo, Giuseppe; Celussi, Mauro; Del Negro, Paola; Ferrarin, Christian; Marini, Mauro; Paschini, Elio; Zaggia, Luca

    2014-05-01

    As part of the actions of the flagship project RITMARE (Ricerca ITaliana per il MARE) a daily oceanographic survey was performed on 29th November 2013 in front of the Po River delta (Northern Adriatic Sea). The Po river affects a large part of the Northern Adriatic Sea with strong implications on the circulation and functionality of the basin. Physical-chemical and biological properties of coastal waters were investigated after a moderate flood occurred around 25th-27th November. The cruise activities, carried out using a small research boat, were mainly focused on the test of a methodological approach to investigate the environment variability after a flood event in the framework of rapid assessment. The effects of the flood on the coastal waters, have been evaluated in the field using operational forecasts and real-time satellite imagery to assist field measurements and samplings. Surface satellite chlorophyll maps and surface salinity and current maps obtained from a numerical model forced by meteorological forecast and river data were analyzed to better identify the Po plume dispersion during and after the event in order to better locate offshore monitoring stations at the sea. Profiles of Temperature, Salinity, Turbidity, Fluorescence and Colored Dissolved Organic Matter (CDOM) throughout the water column were collected at 7 stations in front of the Po River delta. Sea surface water samples were also collected for the analysis of nutrients, Dissolved Organic Carbon (DOC) and CDOM (surface and bottom). The CDOM regulates the penetration of UV light throughout the water column and mediates photochemical reactions, playing an important role in many marine biogeochemical processes. Satellite images showed a strong color front that separates the higher-chlorophyll coastal water from the more oligotrophic mid-basin and eastern boundary Adriatic waters. In front of the river mouth, the surface layer was characterized by low salinity (14-15), high turbidity (8-11 NTU

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

    PubMed Central

    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

  14. Methane concentrations and oxidation in nearshore waters of the Lena River Delta

    NASA Astrophysics Data System (ADS)

    Joye, S. B.; Samarkin, V.; Shakhova, N. E.; Semiletov, I. P.

    2014-12-01

    The Arctic is warming dramatically, with potentially catastrophic impacts on climate change through rapid mobilization of labile carbon reservoirs sequestered presently in permafrost. Increasingly, Arctic feedbacks are recognized as key contributors to climate change, including cycles associated with the powerful greenhouse gas methane, whose atmospheric concentration has more than doubled since the pre-industrial epoch. Sustained methane release to the atmosphere from thawing Arctic permafrost and delivery to the coastal ocean through groundwater or riverine discharge or expulsion from the seabed is a positive and likely highly significant feedback to climate warming. Microbially-mediated methane oxidation provides a key sink and effective biofilter that can limit methane fluxes from coastal environments to the atmosphere. We examined methane dynamics on the East Siberian Arctic Shelf by determining concentrations and oxidation rates at a series of stations near the Lena River Delta and moving offshore. Methane concentrations and oxidation rates were highly elevated in and near the river mouth compared to offshore waters, except when the offshore waters were impacted by seabed methane seepage. The regulation of methane oxidation in Arctic waters appears two-fold: first, rates are strongly related to methane availability and second, in the presence of methane, nutrient availability strongly regulates methane consumption. Along the Lena river delta, elevated concentrations of both nutrients and methane create ideal conditions to support high rates of pelagic methanotrophy. Offshore, where nutrient concentrations are lower and more limiting, methane oxidation rates are considerably lower. These data suggest that, at present, nearshore waters are fairly efficient methane sinks while in offshore waters, pelagic methanotrophy is inefficient, allowing methane to escape to the atmosphere.

  15. Evolution and structure of a coastal squirt off the Mississippi River delta: Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Walker, Nan D.; Huh, Oscar K.; Rouse, Lawrence J.; Murray, Stephen P.

    1996-09-01

    In early October 1992, satellite-derived sea surface temperature data revealed a 200 km long and 10- to 30-km-wide stream of cool water flowing toward the southwest from the Mississippi River delta region. Satellite imagery and in situ measurements have enabled a detailed study of the squirt's kinematics and subsurface characteristics over a 2-week period. In its early stages, the squirt appeared as a narrow, high-speed (>75 cm/s) jet of water which flowed westward over the Mississippi Canyon, forcing a semi-submersible drilling rig to suspend operations from October 2 to 4. After crossing back onto the shelf, the squirt spread laterally, yielding a mushroom-shaped feature, 75 km wide, which consisted of counter-rotating vortices. Northeasterly wind forcing (averaging 10-15 m/s) and water level setup east of the delta appear to have been the primary mechanisms for evolution of the high-velocity currents. Satellite and in situ measurements demonstrate that the dipole eddy was comprised of a cool, low-salinity, low-density water mass at least 26 m deep in the center and 16 m deep along its margins. This event demonstrates that strong northeasterly winds over the northern Gulf of Mexico can initiate along-shelf and off-shelf flows of cooler coastal waters, contributing significantly to seasonal cooling and freshening of the continental shelf and to shelf/slope exchanges of water. During this event, approximately 100 km3 of inner shelf and river water was transported off the continental shelf, a volume equivalent to 17% of the average annual discharge of the Mississippi and Atchafalaya Rivers.

  16. Radon and radium isotope assessment of submarine groundwater discharge in the Yellow River delta, China

    NASA Astrophysics Data System (ADS)

    Peterson, Richard N.; Burnett, William C.; Taniguchi, Makoto; Chen, Jianyao; Santos, Isaac R.; Ishitobi, Tomotoshi

    2008-09-01

    Naturally occurring chemical tracers were used to assess the magnitude of submarine groundwater discharge (SGD) during two different sampling periods at a coastal site south of the Yellow River delta, China. We used salinity and pH as indicators of the terrestrial and recirculated seawater components of discharging groundwater and radium isotopes to quantify offshore transport rates. We then used an hourly time series of multiple radium isotopes (224Ra, 223Ra, and 226Ra) to quantify SGD rates and also used 222Rn and seepage meters to independently quantify SGD rates as a comparison to the radium results. Offshore transport rates were found to range from 3.3 to 4.7 cm s-1. Modeled time series radium activities indicated average SGD rates ranging from 4.5 to 13.9 cm d-1 in September 2006 and from 5.2 to 11.8 cm d-1 in July 2007. Temporal trends associated with the radium approach agree with SGD patterns revealed by automated seepage meters deployed nearby, but the absolute fluxes are about 70% lower than those determined by the seepage meters. Modeled SGD rates based on 222Rn (mean = 13.8 cm d-1 in 2006 and 8.4 cm d-1 in 2007) agree with those determined by the radium analysis. Differences in derived SGD rates between the different radium isotopes (226Ra highest; 224Ra lowest) are likely results of uncertainties in the background activities and our limited selection of appropriate groundwater/pore water end-member values. Scaling our results to the entire Yellow River delta, we find SGD fluxes (and corresponding nitrate fluxes) 2-3 times that of the Yellow River.

  17. Quantitative tolerance values for common stream benthic macroinvertebrates in the Yangtze River Delta, Eastern China.

    PubMed

    Qin, Chun-Yan; Zhou, Jin; Cao, Yong; Zhang, Yong; Hughes, Robert M; Wang, Bei-Xin

    2014-09-01

    Aquatic organisms' tolerance to water pollution is widely used to monitor and assess freshwater ecosystem health. Tolerance values (TVs) estimated based on statistical analyses of species-environment relationships are more objective than those assigned by expert opinion. Region-specific TVs are the basis for developing accurate bioassessment metrics particularly in developing countries, where both aquatic biota and their responses to human disturbances have been poorly documented. We used principal component analysis to derive a synthetic gradient for four stressor variables (total nitrogen, total phosphorus, dissolved oxygen, and % silt) based on 286 sampling sites in the Taihu Lake and Qiantang River basins (Yangtze River Delta), China. We used the scores of taxa on the first principal component (PC1), which explained 49.8% of the variance, to estimate the tolerance values (TV(r)) of 163 macroinvertebrates taxa that were collected from at least 20 sites, 81 of which were not included in the Hilsenhoff TV lists (TV(h)) of 1987. All estimates were scaled into the range of 1-10 as in TV(h). Of all the taxa with different TVs, 46.3% of TV(r) were lower and 52.4% were higher than TV(h). TV(r) were significantly (p < 0.01, Fig. 2), but weakly (r(2) = 0.34), correlated with TVh. Seven biotic metrics based on TVr were more strongly correlated with the main stressors and were more effective at discriminating references sites from impacted sites than those based on TV(h). Our results highlight the importance of developing region-specific TVs for macroinvertebrate-based bioassessment and to facilitate assessment of streams in China, particularly in the Yangtze River Delta. PMID:24865385

  18. Quantitative tolerance values for common stream benthic macroinvertebrates in the Yangtze River Delta, Eastern China.

    PubMed

    Qin, Chun-Yan; Zhou, Jin; Cao, Yong; Zhang, Yong; Hughes, Robert M; Wang, Bei-Xin

    2014-09-01

    Aquatic organisms' tolerance to water pollution is widely used to monitor and assess freshwater ecosystem health. Tolerance values (TVs) estimated based on statistical analyses of species-environment relationships are more objective than those assigned by expert opinion. Region-specific TVs are the basis for developing accurate bioassessment metrics particularly in developing countries, where both aquatic biota and their responses to human disturbances have been poorly documented. We used principal component analysis to derive a synthetic gradient for four stressor variables (total nitrogen, total phosphorus, dissolved oxygen, and % silt) based on 286 sampling sites in the Taihu Lake and Qiantang River basins (Yangtze River Delta), China. We used the scores of taxa on the first principal component (PC1), which explained 49.8% of the variance, to estimate the tolerance values (TV(r)) of 163 macroinvertebrates taxa that were collected from at least 20 sites, 81 of which were not included in the Hilsenhoff TV lists (TV(h)) of 1987. All estimates were scaled into the range of 1-10 as in TV(h). Of all the taxa with different TVs, 46.3% of TV(r) were lower and 52.4% were higher than TV(h). TV(r) were significantly (p < 0.01, Fig. 2), but weakly (r(2) = 0.34), correlated with TVh. Seven biotic metrics based on TVr were more strongly correlated with the main stressors and were more effective at discriminating references sites from impacted sites than those based on TV(h). Our results highlight the importance of developing region-specific TVs for macroinvertebrate-based bioassessment and to facilitate assessment of streams in China, particularly in the Yangtze River Delta.

  19. Heavy metals in oysters, mussels and clams collected from coastal sites along the Pearl River Delta, South China.

    PubMed

    Fang, Zhan-Qiang; Cheung, R Y H; Wong, M H

    2003-01-01

    Concentrations of 8 heavy metals: cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), chromium (Cr), antimony (Sb) and tin (Sn) were examined in 3 species of bivalves ( Perna viridis, Crassostrea rivularis and Ruditapes philippinarum) collected from 25 sites along the Pearl River Delta coastal waters in the South China Sea from July to August 1996. In general, Cd, Cu, Zn and Sn concentrations in the three bivalve species collected from the Estuarine Zone were significantly higher than those collected from the Western and Eastern Zones of the Pearl River Delta, which are related to the existence of various anthropogenic activities in the catchment of the Pearl River Delta. The Western Estuarine Zone is mainly impacted hy Cr, Ni and Cu contamination. In Victoria Harbor, heavy metal contamination is mainly due to Cu and Pb, Cd, Cu and Zn concentrations in oysters were significantly higher than those in mussels and clams. This could be explained by the fact that oysters live mainly in the Estuarine Zone of the Pearl River Delta which receives most of the polluting discharges from the catchment of the Delta. During turbid condition, heavy metals( soluble or adsorbed on suspended particulates) discharged from the Delta are filtered from the water column and subsequently accumulated into the soft body tissues of oysters. Heavy metal concentrations in the three bivalve species were compared with the maximum permissible levels of heavy metals in seafood regulated by the Public Health and Municipal Services Ordinance, Laws of Hong Kong, and it was revealed that Cd and Cr concentrations in the three bivalve species exceeded the upper limits. At certain hotspots in the Delta, the maximum acceptable daily load for Cd was also exceeded.

  20. Georelational analysis of soil type, soil salt content, landform, and land use in the Yellow River Delta, China.

    PubMed

    Fang, Hongliang; Liu, Gaohuan; Kearney, Michael

    2005-01-01

    The Yellow River Delta, one of China's three major river deltas, is becoming a major region for the development of agriculture and fisheries. Protecting the delicate ecology of newly formed aquatic systems as well as the evolution of soils, natural vegetation, and fauna on older upland environments in the delta is a priority in planning for the wise use of the delta's resources for future agricultural development. In this article, we use a Geographic Information System (GIS) to analyze relationships between land-use/ land-cover characteristics in the Dongying municipality, one of the most intensely developed areas of the delta, and spatial variations in soil salinity and landforms. This analysis reveals that soil salt content decreases from regionally high values in isolated depressions to relatively moderate values in embanked former back swamps, with the lowest values occurring in abandoned river courses. Comparing the present land use on this soil salinity-landform pattern shows that it is basically at odds with general concepts of land suitability for agricultural utilization of saline soils. Crop-based agriculture in the region is probably overdeveloped, whereas more appropriate agricultural development, like cattle and forest production, is underrepresented. Future development should focus on converting farmland in embanked former back swamps and abandoned river courses into grasslands and forests. Crop-based agriculture (up to 151,000 ha) could be planned at the low-salinity terrace uplands and flood plains. The article provides guidelines for decision-makers regarding agricultural land use and wetland protection in the Yellow River Delta.

  1. Characterization of elements in the irrigated water in the Changjiang River Delta Region

    NASA Astrophysics Data System (ADS)

    Yuan, X.

    2009-12-01

    Introduction The river networks are dominated in the Changjiang River Delta Region. Most agricultural areas are irrigated with these small rivers. Rivers also receive the effluence from point and nonpoint sources. It is significative to recognize the distribution and potential hazard of irrigated water in this populated area. Study area and sampling The study area covers about 1.1×106 km2, including 16 cities from the northside of Changjiang River in Jiangsu to the middle Zhejiang. Ninety samples were collected in rural irrigated rivers. And the major cations, anions and trace elements of water were determined. Results We observe that Ca2+ is obviously higher in cations, and Cl-, SO42- higher in anions. The southern Jiangsu and coast of middle Zhejiang show high Na+, the hill area of southern Jiangsu and northern Zhejiang show high Ca2+. HCO3- is relatively uniform distributed in these areas. The high SO42- in a few samples occour in industrial spots of Jiangsu and Zhejiang. Cl- increases in waters along the coast. NO3- fluctuates and disperses in samples. Trace elements in waters are unevenly distributed. The two sides of Changjiang River have high As and Cr. Mercury is higher in southern Jiangsu than in other areas. Iron shows an enrichment in the middle Zhejiang. Compared with the background concentrations of trace elements in the lower Changjiang River, Pb, Cu and Cd are much higher in middle Zhejiang than in other areas. But Zn of most samples are lower than the background value.Cu is associated with organic matter in water. Dicussion The research area consists of hill, plain and coast, where farms, industries and houses distribute. In the hilly area of carbonate-dominated, the waters show high Ca2+ and HCO3-, rivers have high Cl- in vicinity of sea. NO3- and SO42- are strongly influenced by anthopogenic input. NO3- shows a high concentration in areas of fertilizer usage. SO42- increases in areas with a lot of industrial discharge. The distribution of trace

  2. Estuarine science and decision-support tools to restore Puget Sound delta and estuarine ecosystems: The Skagit River Delta

    NASA Astrophysics Data System (ADS)

    Grossman, E. E.; Rosenbauer, R. J.; Takesue, R. K.; Gelfenbaum, G.; Reisenbichler, R.; Paulson, A.; Sexton, N. R.; Labiosa, B.; Beamer, E. M.; Hood, G.; Wyllie-Echeverria, S.

    2006-12-01

    Historic land use, ongoing resource extraction, and population expansion throughout Puget Sound have scientists and managers rapidly seeking effective restoration strategies to recover salmon (a cultural icon, as well as, a host of other endangered species and threatened habitats. Of principal concern is the reduction of salmon (Oncorhynchus spp.) and diminished carrying capacity of critical habitat in deltaic regions. Delta habitats, essential to salmon survival, have lost 70 to 80 % area since ~1850 and are now adjusting to a new suite of environmental changes associated with land use practices, including wetland restoration, and regional climate change. The USGS Coastal Habitats in Puget Sound Project, in collaboration with partners from the Skagit River System Cooperative, University of Washington, and other federal, state, and local agencies, is integrating geologic, biologic, hydrologic, and socioeconomic information to quantify changes in the distribution and function of deltaic-estuarine nearshore habitats and better predict "possible futures". We are combining detailed geologic and geochemical analyses of sedimentary environments, plant biomarkers (n-alkanes, PAHs, fatty-acids, and sterols), and compound-specific isotopes to estimate historic habitat coverage, eelgrass (Zostera marina) abundance and modern characteristics of nutrient cycling. Hydrologic and sediment transport processes are being measured to characterize physical processes shaping modern habitats including sediment transport and freshwater mixing that control the temporal and spatial pattern of substrate and water column conditions available as habitat. We are using geophysical, remote sensing, and modeling techniques to determine large-scale coastal morphologic and land-use change and characterize how alteration of physical, hydrologic, and biogeochemical processes influence the dynamics of freshwater mixing, and sediment and nutrient transport in the nearshore. To assist restoration

  3. The Science and Policy of the First Environmental Flows to the Colorado River Delta

    NASA Astrophysics Data System (ADS)

    Flessa, K. W.; Kendy, E.; Schlatter, K.

    2014-12-01

    The first transboundary flow of water for the environment was delivered to the Colorado River Delta in spring of 2014. This engineered mini-spring flood of 130 million cubic meters (105,000 acre-feet) was implemented as part of Minute 319, an addition to the 1944 U.S.-Mexico Water Treaty. Minute 319 is a temporary agreement, expiring in 2017. Teams of scientists from government agencies, universities, and environmental NGOs from both the U.S. and Mexico are measuring the surface flow rates, inundation, ground water recharge, ground water levels and subsurface flows, geomorphic change, recruitment, survival and health of vegetation, and avian response to the environmental flow. Monitoring includes on-the-ground observations and measurements and remote sensing. Surface water from the pulse flow reached restoration sites, prompted germination of both native and non-native vegetation, recharged groundwater and reached the Gulf of California - the first reconnection of the Colorado River and the sea in 16 years. People in local communities joyously welcomed the return of the river; extensive media coverage was overwhelmingly positive - despite widespread drought in the West. After about ten weeks, most of the pulse flow had infiltrated the subsurface, ponded in a few cut-off meanders, or run to the sea. The river no longer flows. Monitoring of seedling survival, groundwater, vegetation and wildlife will continue through 2017. Results of this landscape-scale experiment will play a role in negotiations to renew the agreement, help model and design future flows and guide the efficient use of water for restoration in semi-arid river systems.

  4. Geomorphological and geotechnical issues affecting the seismic slope stability of the Duwamish River Delta, Port of Seattle, Washington

    USGS Publications Warehouse

    Kayen, Robert E.; Barnhardt, Walter A.; Palmer, Stephen P.

    1999-01-01

    Young Holocene deposits of the Duwamish River valley underlie a highly developed transportation-industrial corridor, extending from the City of Kent to the Elliott Bay-Harbor Island marine terminal facilities. The deposits have been shaped by relative sea-level rise, but also by episodic volcanism and seismicity. A geologic and geotechnical investigation of these river-mouth deposits indicates high initial liquefaction susceptibility during earthquakes, and possibly the potential for unlimited-strain disintegrative flow failure of the delta front.

  5. Thyroid hormone disrupting activities associated with phthalate esters in water sources from Yangtze River Delta.

    PubMed

    Shi, Wei; Zhang, Feng-Xian; Hu, Guan-Jiu; Hao, Ying-Qun; Zhang, Xiao-Wei; Liu, Hong-Ling; Wei, Si; Wang, Xin-Ru; Giesy, John P; Yu, Hong-Xia

    2012-07-01

    Thyroid hormone disrupting compounds in water sources is a concern. Thyroid hormone (TH) agonist and antagonist activities of water sources from the Yangtze River, Huaihe River, Taihu Lake and ground water in the Yangtze River Delta region were evaluated by use of a TH reporter gene assay based on the green monkey kidney fibroblast (CV-1). While weak TH receptor (TR) agonist potency was observed in only one of 15 water sources, antagonist potency was present in most of the water sources. TR antagonist equivalents could be explained by the presence of dibutyl phthalate (DBP), with concentrations ranging from 2.8×10(1) to 1.6×10(3) μg DBP /L (ATR-EQ(50)s). None of the ground waters exhibited TH agonist potencies while all of the samples from Taihu Lake displayed notable TR antagonist potencies. To identify the responsible thyroid active compounds, instrumental analysis was conducted to measure a list of potential thyroid-disrupting chemicals, including organochlorine (OC) pesticides and phthalate esters. Combining the results of the instrumental analysis with those of the bioassay, DBP was determined to account for 17% to 144% of ATR-EQ(50)s in water sources. Furthermore, ATR-EQ(20-80) ranges for TR antagonist activities indicated that samples from locations WX-1 and WX-2 posed the greatest health concern and the associated uncertainty may warrant further investigation.

  6. Large-river delta-front estuaries as natural "recorders" of global environmental change.

    PubMed

    Bianchi, Thomas S; Allison, Mead A

    2009-05-19

    Large-river delta-front estuaries (LDE) are important interfaces between continents and the oceans for material fluxes that have a global impact on marine biogeochemistry. In this article, we propose that more emphasis should be placed on LDE in future global climate change research. We will use some of the most anthropogenically altered LDE systems in the world, the Mississippi/Atchafalaya River and the Chinese rivers that enter the Yellow Sea (e.g., Huanghe and Changjiang) as case-studies, to posit that these systems are both "drivers" and "recorders" of natural and anthropogenic environmental change. Specifically, the processes in the LDE can influence ("drive") the flux of particulate and dissolved materials from the continents to the global ocean that can have profound impact on issues such as coastal eutrophication and the development of hypoxic zones. LDE also record in their rapidly accumulating subaerial and subaqueous deltaic sediment deposits environmental changes such as continental-scale trends in climate and land-use in watersheds, frequency and magnitude of cyclonic storms, and sea-level change. The processes that control the transport and transformation of carbon in the active LDE and in the deltaic sediment deposit are also essential to our understanding of carbon sequestration and exchange with the world ocean--an important objective in global change research. U.S. efforts in global change science including the vital role of deltaic systems are emphasized in the North American Carbon Plan (www.carboncyclescience.gov). PMID:19435849

  7. Large-river delta-front estuaries as natural "recorders" of global environmental change.

    PubMed

    Bianchi, Thomas S; Allison, Mead A

    2009-05-19

    Large-river delta-front estuaries (LDE) are important interfaces between continents and the oceans for material fluxes that have a global impact on marine biogeochemistry. In this article, we propose that more emphasis should be placed on LDE in future global climate change research. We will use some of the most anthropogenically altered LDE systems in the world, the Mississippi/Atchafalaya River and the Chinese rivers that enter the Yellow Sea (e.g., Huanghe and Changjiang) as case-studies, to posit that these systems are both "drivers" and "recorders" of natural and anthropogenic environmental change. Specifically, the processes in the LDE can influence ("drive") the flux of particulate and dissolved materials from the continents to the global ocean that can have profound impact on issues such as coastal eutrophication and the development of hypoxic zones. LDE also record in their rapidly accumulating subaerial and subaqueous deltaic sediment deposits environmental changes such as continental-scale trends in climate and land-use in watersheds, frequency and magnitude of cyclonic storms, and sea-level change. The processes that control the transport and transformation of carbon in the active LDE and in the deltaic sediment deposit are also essential to our understanding of carbon sequestration and exchange with the world ocean--an important objective in global change research. U.S. efforts in global change science including the vital role of deltaic systems are emphasized in the North American Carbon Plan (www.carboncyclescience.gov).

  8. Distribution of organophosphorus flame retardants in sediments from the Pearl River Delta in South China.

    PubMed

    Tan, Xiao-Xin; Luo, Xiao-Jun; Zheng, Xiao-Bo; Li, Zong-Rui; Sun, Run-Xia; Mai, Bi-Xian

    2016-02-15

    Twelve organophosphorus flame retardants (PFRs) were identified in the sediments and the sediment core collected from the rivers and the estuary in the Pearl River Delta, with the aim of investigating their spatial and vertical distributions. The concentrations of PFRs ranged from 8.3 to 470 ng/g dry weight with high levels of PFRs in the urban area and the e-waste recycling region. Generally, TPhP, TCPP, TEHP, TCEP, and TBEP were the dominant compounds of the PFRs, the composition of which varied across the different regions, reflecting the different sources of PFRs. In the estuary, the PFRs mainly derived from the Xijiang River and the Shunde sections. Increased concentrations of halogen-containing PFRs have been observed in the upper layers of the sediment core. Conversely, relatively high concentrations of halogen-free PFRs were observed in the lower layers of the sediment core, indicating different usage patterns or environmental behaviors between the halogen and the non-halogen PFRs in the study area. PMID:26657357

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

    PubMed

    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.

  10. Recent human impacts on the morphological evolution of the Yangtze River delta foreland: A review and new perspectives

    NASA Astrophysics Data System (ADS)

    Du, Jing-Long; Yang, Shi-Lun; Feng, Huan

    2016-11-01

    This paper reviews the morphological change in the Yangtze River delta due to increasing human impacts from three major aspects. The first is the reduction of sediment supply to the ocean due to dam construction, soil conservation, and sand mining within the Yangtze River basin. The reduced sediment supply has decreased the progradation rate of the delta and triggered erosion in the front of the delta. The second impact relates to the reclamation of intertidal wetlands by human activities. Since the 1950s, approximately 1100 km2 of intertidal land has been embanked, resulting in the disappearance of salt marshes and even the entire intertidal zone along some sections of the coastline. The third change in the delta due to human interference is the construction of deep-waterway structures at the mouth bar, which has greatly modified the local hydrodynamics and morphology. Sediment accretion has increased significantly in these areas as a result of sheltering by these deep-waterway structures. This review shows that human activities have severely altered the natural balance among the hydrodynamics and sediment supply, affecting the morphological features of the Yangtze River watershed and delta. Human impacts on the morphological evolution of deltaic coasts in general are becoming an increasingly concern, and more attention should be paid to the management and mitigation of these effects.

  11. Carbon Sequestration in Mediterranean Tidal Wetlands: San Francisco Bay and the Ebro River Delta (Invited)

    NASA Astrophysics Data System (ADS)

    Callaway, J.; Fennessy, S.; Ibanez, C.

    2013-12-01

    Tidal wetlands accumulate soil carbon at relatively rapid rates, in large part because they build soil to counteract increases in sea-level rise. Because of the rapid rates of carbon sequestration, there is growing interest in evaluating carbon dynamics in tidal wetlands around the world; however, few measurements have been completed for mediterranean-type tidal wetlands, which tend to have relatively high levels of soil salinity, likely affecting both plant productivity and decomposition rates. We measured sediment accretion and carbon sequestration rates at tidal wetlands in two mediterranean regions: the San Francisco Bay Estuary (California, USA) and the Ebro River Delta (Catalonia, Spain). Sampling sites within each region represented a range of conditions in terms of soil salinity and plant communities, and these sites serve as potential analogs for long-term carbon sequestration in restored wetlands, which could receive credits under emerging policies for carbon management. Within San Francisco Bay, we collected six sediment cores per site at four salt marshes and two brackish tidal wetlands (two transects with three stations per transect at each site) in order to identify spatial variation both within and among wetlands in the Estuary. At the Ebro Delta, individual sediment cores were collected across 14 tidal wetland sites, including salt and brackish marshes from impounded areas, river mouths, coastal lagoon, and open bay settings. Cores were collected to 50 cm, and cores were dated using 137Cs and 210Pb. Most sites within San Francisco accreted 0.3-0.5 cm/yr, with slightly higher rates of accretion at low marsh stations; accretions rates based on 137Cs were slightly higher than those based on 210Pb, likely because of the shorter time frame covered by 137Cs dating. Accretion rates from the Ebro Delta sites were similar although more variable, with rates based on 137Cs ranging from 0.1 to 0.9 cm/yr and reflecting the wide range of conditions and management

  12. Employee Training Needs and Perceived Value of Training in the Pearl River Delta of China: A Human Capital Development Approach

    ERIC Educational Resources Information Center

    Au, Alan Kai Ming; Altman, Yochanan; Roussel, Josse

    2008-01-01

    Purpose: This paper aims to explore Hong Kong firms' training needs in the Pearl River Delta, a booming region in the fast growing People Republic of China economy, by resorting to a human capital approach. Also, to identify the training policies selected by those firms in order to cater for those needs. Design/methodology/approach: A survey based…

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

    EPA Science Inventory

    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...

  14. Wave-induced seepage and its possible contribution to the formation of pockmarks in the Huanghe (Yellow) River delta

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Liu, Hongjun; Zhang, Minsheng; Wang, Xiuhai

    2016-01-01

    Wave-induced seepage and its possible contribution to the formation of pockmarks in the Huanghe (Yellow) River delta were investigated experimentally and numerically. Laboratory experiments were carried out to explore the response of a layered silty seabed with various saturation conditions under cyclic wave loads, in which the pore pressure and seepage-related phenomena were particularly monitored. Numerical models to simulate wave-induced seepage in the seabed were presented and evaluated, then applied to the Huanghe River delta. The experimental results show that the excess pore pressure decreases more rapidly at the surface layer, while the seepage-related phenomena are more pronounced when large cyclic loads are applied and the underlying layer is less saturated. The proposed numerical models were verified by comparing with the experiments. The calculated seepage depth agreed well with the depth of the pockmarks in the Huanghe River delta. The experimental and numerical results and the existing insitu investigations indicate that the wave-induced seepage may be a direct cause of the pockmarks in the Huanghe River delta. Extreme storm waves and the dual-layered structure of hard surface layer and weak underlying layer are essential external and internal factors, respectively. Wave- or current-induced scour and transport are possible contributors to the reformation of pockmarks at a later stage.

  15. Biological assessment:Egeria densa control program for the Sacramento/San Joaquin River Delta of California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A detailed Biological Assessment was developed for the proposed Area wide Egeria densa Control Program to outline the procedures that will be used to control this submerged invasive aquatic plant in the Sacramento/ San Joaquin River Delta, and to help determine if this action is expected to threaten...

  16. Examining the Impact of Nitrous Acid Chemistry on Ozone and PM over the Pearl River Delta Region

    EPA Science Inventory

    The impact of nitrous acid (HONO) chemistry on regional ozone and particulate matter in Pearl River Delta region was investigated using the community multiscale air quality (CMAQ) modeling system and the CB05 mechanism. Model simulations were conducted for a ten-day period in Oct...

  17. Soil Phosphorus Forms and Profile Distributions in the Tidal River Network Region in the Yellow River Delta Estuary

    PubMed Central

    Yu, Junbao; Qu, Fanzhu; Wu, Huifeng; Meng, Ling; Du, Siyao; Xie, Baohua

    2014-01-01

    Modified Hedley fraction method was used to study the forms and profile distribution in the tidal river network region subjected to rapid deposition and hydrologic disturbance in the Yellow River Delta (YRD) estuary, eastern China. The results showed that the total P (Pt) ranged from 612.1 to 657.8 mg kg−1. Dilute HCl extractable inorganic P (Pi) was the predominant form in all profiles, both as absolute values and as a percentage of total extracted Pi. The NaOH extractable organic P (Po) was the predominant form of total extracted Po, while Bicarb-Pi and C.HCl-Po were the lowest fractions of total extracted Pi and Po in all the P forms. The Resin-P concentrations were high in the top soil layer and decreased with depth. The Pearson correlation matrix indicated that Resin-P, Bicarb-Pi, NaOH-Pi, and C.HCl-Pi were strongly positively correlated with salinity, TOC, Ca, Al, and Fe but negatively correlated with pH. The significant correlation of any studied form of organic P (Bicarb-Po, NaOH-Po, and C.HCl-Po) with geochemical properties were not observed in the study. Duncan multiple-range test indicated that the P forms and distribution heterogeneity in the profiles could be attributed to the influences of vegetation cover and hydrologic disturbance. PMID:24971393

  18. Shallow Groundwater Movement in the Skagit River Delta Area, Skagit County, Washington

    USGS Publications Warehouse

    Savoca, Mark E.; Johnson, Kenneth H.; Fasser, Elisabeth T.

    2009-01-01

    Shallow groundwater movement in an area between the lower Skagit River and Puget Sound was characterized by the U.S. Geological Survey to assist Skagit County and the Washington State Department of Ecology with the identification of areas where water withdrawals from existing and new wells could adversely affect streamflow in the Skagit River. The shallow groundwater system consists of alluvial, lahar runout, and recessional outwash deposits composed of sand, gravel, and cobbles, with minor lenses of silt and clay. Upland areas are underlain by glacial till and outwash deposits that show evidence of terrestrial and shallow marine depositional environments. Bedrock exposures are limited to a few upland outcrops in the southwestern part of the study area, and consist of metamorphic, sedimentary, and igneous rocks. Water levels were measured in 47 wells on a quarterly basis (August 2007, November 2007, February 2008, and May 2008). Measurements from 34 wells completed in the shallow groundwater system were used to construct groundwater-level and flow-direction maps and perform a linear-regression analysis to estimate the overall, time averaged shallow groundwater-flow direction and gradient. Groundwater flow in the shallow groundwater system generally moves in a southwestward direction away from the Skagit River and toward the Swinomish Channel and Skagit Bay. Local groundwater flow towards the river was inferred during February 2008 in areas west and southwest of Mount Vernon. Water-level altitudes varied seasonally, however, and generally ranged from less than 3 feet (August 2007) in the west to about 15 feet (May 2008) in the east. The time-averaged, shallow groundwater-flow direction derived from regression analysis, 8.5 deg south of west, was similar to flow directions depicted on the quarterly water-level maps. Seasonal changes in groundwater levels in most wells in the Skagit River Delta follow a typical pattern for shallow wells in western Washington. Water

  19. Extreme saline water advection into the Don River delta and ice advections into Kerch Strait

    NASA Astrophysics Data System (ADS)

    Matishov, G. G.

    2015-11-01

    Analysis of such extreme natural phenomena as inflow of saline transformed waters from the Black Sea into the Don River delta, ice drift, and some others, which have been observed in the Sea of Azov in the recent years, is performed. The process and consequences of the ice movement from the Sea of Azov into Kerch Strait under the effect of hurricane-force NE winds is characterized. Data on the salinity and water level changes during the intensive westerly winds are given. The relationship between salinity and water level during episodes of the surges and downsurges is found. Recommendations for organizing the monitoring measures, intended to increase the accuracy of forecasting emergency situations in the Gulf of Taganrog, Sea of Azov, are presented.

  20. Vegetation, substrate and hydrology in floating marshes in the Mississippi river delta plain wetlands, USA

    USGS Publications Warehouse

    Sasser, C.E.; Gosselink, J.G.; Swenson, E.M.; Swarzenski, C.M.; Leibowitz, N.C.

    1996-01-01

    In the 1940s extensive floating marshes (locally called 'flotant') were reported and mapped in coastal wetlands of the Mississippi River Delta Plain. These floating marshes included large areas of Panicum hemitomon-dominated freshwater marshes, and Spartina patens/Scirpus olneyi brackish marshes. Today these marshes appear to be quite different in extent and type. We describe five floating habitats and one non-floating, quaking habitat based on differences in buoyancy dynamics (timing and degree of floating), substrate characteristics, and dominant vegetation. All floating marshes have low bulk density, organic substrates. Nearly all are fresh marshes. Panicum hemitomon floating marshes presently occur within the general regions that were reported in the 1940's by O'Neil, but are reduced in extent. Some of the former Panicum hemitomon marshes have been replaced by seasonally or variably floating marshes dominated, or co-dominated by Sagittaria lancifolia or Eleocharis baldwinii. ?? 1996 Kluwer Academic Publishers.

  1. Harmful Algae Records in Venice Lagoon and in Po River Delta (Northern Adriatic Sea, Italy)

    PubMed Central

    Bilaničovà, Dagmar; 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. PMID:24683360

  2. Spatio-temporal analysis of recent groundwater-level trends in the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Bui, Duong Du; Kawamura, Akira; Tong, Thanh Ngoc; Amaguchi, Hideo; Nakagawa, Naoko

    2012-12-01

    A groundwater-monitoring network has been in operation in the Red River Delta, Vietnam, since 1995. Trends in groundwater level (1995-2009) in 57 wells in the Holocene unconfined aquifer and 63 wells in the Pleistocene confined aquifer were determined by applying the non-parametric Mann-Kendall trend test and Sen's slope estimator. At each well, 17 time series (e.g. annual, seasonal, monthly), computed from the original data, were analyzed. Analysis of the annual groundwater-level means revealed that 35 % of the wells in the unconfined aquifer showed downward trends, while about 21 % showed upward trends. On the other hand, confined-aquifer groundwater levels experienced downward trends in almost all locations. Spatial distributions of trends indicated that the strongly declining trends (>0.3 m/year) were mainly found in urban areas around Hanoi where there is intensive abstraction of groundwater. Although the trend results for most of the 17 time series at a given well were quite similar, different trend patterns were detected in several. The findings reflect unsustainable groundwater development and the importance of maintaining groundwater monitoring and a database in the Delta, particularly in urban areas.

  3. Sequence stratigraphy of the subaqueous Changjiang (Yangtze River) delta since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Xu, Taoyu; Wang, Guoqing; Shi, Xuefa; Wang, Xin; Yao, Zhengquan; Yang, Gang; Fang, Xisheng; Qiao, Shuqing; Liu, Shengfa; Wang, Xuchen; Zhao, Quanhong

    2016-01-01

    This study focuses on sedimentary research at the subaqueous Changjiang (Yangtze River) delta, based on five high-resolution seismic profiles and seven borehole cores with accurate AMS 14C datings. Three distinct seismic units were identified from the seismic profiles according to seismic reflection characteristics, and five sedimentary facies were recognized from borehole cores. These facies constituted a fining upward sedimentary sequence in relation to postglacial sea-level transgression. Three sequence surfaces (sequence boundary (SB), transgressive surface (TS), and maximum flooding surface (MFS)) demarcate the boundaries between early transgressive system tract (E-TST), late transgressive system tract (L-TST), early highstand system tract (E-HST) and late highstand system tract (L-HST), which constitute the sixth order sequence. These system tracts were developed coevally with postglacial sea-level rise. E-TST (~ 19-12 ka BP) corresponds to an incised-valley infilling in the early stages of postglacial transgression whereas L-TST (~ 12-7.5 ka BP) was formed during the last stage of postglacial transgression. The progradational structure of L-TST reflected in seismic profiles is possibly related to the intensification of the East Asian summer monsoon. E-HST (~ 7.5-2 ka BP) was deposited in response to the highstand after maximum postglacial transgression was reached, while L-HST (~ 2 ka BP-present) was initiated by accelerated progradation of the Changjiang delta.

  4. Biology of Amur sleeper (Perccottus glehni) in the Delta of the Selenga River, Buryatia, Russia

    USGS Publications Warehouse

    Litvinov, Alexander G.; O'Gorman, Robert

    1996-01-01

    We determined the fecundity, growth, diet, and density of the Amur sleeper (Perccottus glehni) in the Selenga River Delta on Lake Baikal during 1986-1991 to better understand how this invading exotic will affect Baikal's endemic fishes. We also compared the Amur sleeper's diet with that of other fishes living in the delta. The largest Amur sleepers were about 200 mm long and weighed 200 g; the oldest were age 7. All females were mature at age 2. Fecundity ranged from 884 eggs at age 1 to 37,056 eggs at age 7. Highest densities of Amur sleepers were found in oxbow lakes where densities sometimes exceeded 4,000 fish per ha. The bulk of the diet of Amur sleeper age 2 and older was chironomids, fish, and fish eggs. Chironomids were also important in the diet of the commercially valuable Siberian roach (Rutilus rutilus lacustris) and Siberian dace (Leuciscus leuciscus baicalensis). Thus the Amur sleeper may cause population declines of these important endemic fishes through resource competition and predation on their juvenile life stages. However, Amur sleepers were the species of fish most frequently eaten by Eurasian perch (Perca fluviatilis) and northern pike (Esox lucius). So, maintaining vigorous populations of these two predators may well be an effective strategy for limiting the size of Amur sleeper populations.

  5. Trace Gas Emissions from Extensive Aquaculture Systems in the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Beman, J.; Seto, K. C.

    2002-12-01

    The Red River Delta of Vietnam is an area undergoing rapid land use change. Aquaculture development is among the most significant of these transformations, with important economic, social and environmental effects. We explored the potential for managed mangrove' and `converted paddy' aquaculture systems in the Delta to produce and/or consume greenhouse gasses. We measured dissolved concentrations of the radiatively-important trace gasses methane (CH4) and nitrous oxide (N2O), as well as associated parameters. All ponds were super-saturated with CH4, with concentrations ranging from 132-1203 nM, (mean 561 nM) in managed mangrove, and 28-521 nM (mean 110 nM) in converted paddy. Surprisingly, none of the ponds was measurably supersaturated with N2O. Methane fluxes were calculated for all ponds using five well-accepted models of gas flux based on wind speed. Mean flux values ranged from 1.04 to 17.09 mg CH4 m-2 d-1 for managed mangrove, falling somewhere between fluxes reported for natural systems and those receiving sewage inputs. Further measurements should be made in more intensive systems to better understand the potential for trace gas production-particularly N2O-in aquaculture systems.

  6. Concentration of contaminants in breeding bird eggs from the Colorado River Delta, Mexico.

    PubMed

    García-Hernández, Jaqueline; Sapozhnikova, Yelena V; Schlenk, Daniel; Mason, Andrew Z; Hinojosa-Huerta, Osvel; Rivera-Díaz, Juan José; Ramos-Delgado, Norma Alicia; Sánchez-Bon, Gerardo

    2006-06-01

    Organic contaminants (organochlorine [OC], organophosphorus [OP] pesticides and polychlorinated biphenyls [PCBs]), and metals (As, Cd, Hg, Pb, and Se) are a concern to avian health in the Colorado River delta, Mexico. We determined concentrations of contaminants in eggs of three breeding species of birds from the delta (mourning doves [Zenaida macroura], burrowing owls [Athene cunicularia], and marsh wrens [Cistothorus palustris]). We collected 27 eggs of mourning doves, eight eggs of burrowing owls, and 18 eggs of marsh wrens for analyses. Polychlorinated biphenyls, OC, and OP pesticides were analyzed by gas chromatography equipped with an electron capture detector, and metals were analyzed by inductively coupled plasma mass spectrometry. The non-ortho PCB congeners (PCB 77 and 126) were found in mourning dove and burrowing owl eggs at concentrations in which hatchability can be affected. Mean selenium concentration found in marsh wren eggs (5.6 microg/g dry wt) exceeded the level of concern. Arsenic and Cd were found at higher than normal concentrations, Hg concentrations did not exceed the level of concern in any of the species, and Pb concentrations were higher in eggs of species subject to hunting. With the exception of lead, marsh wren eggs contained the highest metal concentrations. PMID:16764484

  7. Concentration of contaminants in breeding bird eggs from the Colorado River Delta, Mexico.

    PubMed

    García-Hernández, Jaqueline; Sapozhnikova, Yelena V; Schlenk, Daniel; Mason, Andrew Z; Hinojosa-Huerta, Osvel; Rivera-Díaz, Juan José; Ramos-Delgado, Norma Alicia; Sánchez-Bon, Gerardo

    2006-06-01

    Organic contaminants (organochlorine [OC], organophosphorus [OP] pesticides and polychlorinated biphenyls [PCBs]), and metals (As, Cd, Hg, Pb, and Se) are a concern to avian health in the Colorado River delta, Mexico. We determined concentrations of contaminants in eggs of three breeding species of birds from the delta (mourning doves [Zenaida macroura], burrowing owls [Athene cunicularia], and marsh wrens [Cistothorus palustris]). We collected 27 eggs of mourning doves, eight eggs of burrowing owls, and 18 eggs of marsh wrens for analyses. Polychlorinated biphenyls, OC, and OP pesticides were analyzed by gas chromatography equipped with an electron capture detector, and metals were analyzed by inductively coupled plasma mass spectrometry. The non-ortho PCB congeners (PCB 77 and 126) were found in mourning dove and burrowing owl eggs at concentrations in which hatchability can be affected. Mean selenium concentration found in marsh wren eggs (5.6 microg/g dry wt) exceeded the level of concern. Arsenic and Cd were found at higher than normal concentrations, Hg concentrations did not exceed the level of concern in any of the species, and Pb concentrations were higher in eggs of species subject to hunting. With the exception of lead, marsh wren eggs contained the highest metal concentrations.

  8. Source apportionment of surface ozone in the Yangtze River Delta, China in the summer of 2013

    NASA Astrophysics Data System (ADS)

    Li, L.; An, J. Y.; Shi, Y. Y.; Zhou, M.; Yan, R. S.; Huang, C.; Wang, H. L.; Lou, S. R.; Wang, Q.; Lu, Q.; Wu, J.

    2016-11-01

    We applied ozone source apportionment technology (OSAT) with tagged tracers coupled within the Comprehensive Air Quality Model with Extensions (CAMx) to study the region and source category contribution to surface ozone in the Yangtze River Delta area in summer of 2013. Results indicate that the daytime ozone concentrations in the YRD region are influenced by emissions both locally, regionally and super-regionally. At urban Shanghai, Hangzhou and Suzhou receptors, the ozone formation is mainly VOC-limited, precursor emissions form Zhejiang province dominate their O3 concentrations. At the junction area among two provinces and Shanghai city, the ozone is usually influenced by all the three areas. The daily max O3 at the Dianshan Lake in July are contributed by Zhejiang (48.5%), Jiangsu (11.7%), Anhui (11.6%) and Shanghai (7.4%), long-range transport constitutes around 20.9%. At Chongming site, the BVOC emissions rate is higher than urban region. Regional contribution results show that Shanghai constitutes 15.6%, Jiangsu contributes 16.2% and Zhejiang accounts for 25.5% of the daily max O3. The analysis of the source category contribution to high ozone in the Yangtze River Delta region indicates that the most significant anthropogenic emission source sectors contributing to O3 pollution include industry, vehicle exhaust, although the effects vary with source sector and selected pollution episodes. Emissions of NOx and VOCs emitted from the fuel combustion of industrial boilers and kilns, together with VOCs emissions from industrial process contribute a lot to the high concentrations in urban Hangzhou, Suzhou and Shanghai. The contribution from regional elevated power plants cannot be neglected, especially to Dianshan Lake. Fugitive emissions of volatile pollution sources also have certain contribution to regional O3. These results indicate that the regional collaboration is of most importance to reduce ambient ozone pollution, particularly during high ozone episodes.

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

    USGS Publications Warehouse

    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.

  10. Dissolved and colloidal trace elements in the Mississippi River delta outflow after Hurricanes Katrina and Rita

    NASA Astrophysics Data System (ADS)

    Shim, Moo-Joon; Swarzenski, Peter W.; Shiller, Alan M.

    2012-07-01

    The Mississippi River delta outflow region is periodically disturbed by tropical weather systems including major hurricanes, which can terminate seasonal bottom water hypoxia and cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, Hurricanes Katrina and Rita passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we collected water samples in the Mississippi River delta outflow, examining the distributions of trace elements to study the effect of Hurricanes Katrina and Rita. We observed limited stratification on the shelf and bottom waters that were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn-O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 μm) from colloidal (0.02-0.45 μm) phase, revealed significant colloidal fractions for Fe and Zn, only. For Fe, the colloidal phase was the dominant fraction and was rapidly removed at low salinity. Dissolved Fe, in contrast, persisted out to mid-salinities, being removed in a similar fashion to nitrate. This ability to distinguish the smaller Fe (likely dominantly organically complexed) from larger colloidal suspensates may be useful in better interpreting the bioavailablity

  11. [HALOTOLERANCE OF ENTEROBACTERIA ISOLATED FROM WATER AND FISH IN THE VOLGA RIVER DELTA].

    PubMed

    Obukhova, O V; Lartseva, L V

    2015-01-01

    In the article there are presented the results of a study of halotolerance of enterobacteria isolated from water and fish in the Volga River delta, which were dominant in the microbial landscape of these biotopes. Their halotolerance was studied by means of inoculation of daily pure cultures of meat--peptone broth with 3, 7 and 10% of sodium chloride and incubation at 37°C. At that all studied microflora was found to have significant indices of halotolerance with a predominance of aquatic isolates. At that in 3,0 and 7,0 % NaCl concentrations were very similar, but in 10% NaCl broth the halotolerance of water strain was almost 2.0 times higher than the in fish ones. Among isolated Enterobacteriaceae most halophilic bacteria were from the Proteus group, Citrobacteria and Enterobacteria. The halotolerance of isolated enterobacteria in hydroecosystem of the Volga River delta had seasonal specificity and dynamics. There was established the dynamic growth of this sign in the water and fish strains from spring to autumn. Thus, the analysis of the obtained results of the long-term conducted study has shown the wide dissemination of conditionally pathogenic enterobacteria in water and fish, and their high halotolerance and the ability of some of them to remain viable up to salt production. It gives grounds to recommend the necessity of the introduction of them into the normative documentation in the implementation ofthe sanitary-microbiological control of not only raw materials but also ready salted fish production.

  12. Vegetative Ecological Characteristics of Restored Reed ( Phragmites australis) Wetlands in the Yellow River Delta, China

    NASA Astrophysics Data System (ADS)

    Wang, Xuehong; Yu, Junbao; Zhou, Di; Dong, Hongfang; Li, Yunzhao; Lin, Qianxin; Guan, Bo; Wang, Yongli

    2012-02-01

    In this study, we compared ecological characteristics of wetland vegetation in a series of restoration projects that were carried out in the wetlands of Yellow River Delta. The investigated characteristics include plant composition structure, species diversity and community similarity in three kinds of Phragmites australis wetlands, i.e. restored P. australis wetlands (R1, R2, R3 and R4: restored in 2002, 2005, 2007 and 2009, respectively), natural P. australis wetland (N) and degraded P. australis wetland (D) to assess the process of wetlands restoration. The coverage of the R1 was 99%, which was similar to natural wetland. Among all studied wetlands, the highest and lowest stem density was observed in R1 and R2, respectively, Plant height and stem diameter show the same trend as N > R2 > R1 > R3 > D > R4. Species diversity of restored P. australis wetlands became closed to natural wetland. Both species richness and Shannon-Wiener index had similar tendency: increased first and then decreased with restored time. The highest species richness and species diversity were observed in R2, while the lowest values of those parameters were found in natural P. australis wetland. Similarity indexes between restored wetlands and natural wetland increased with the restoration time, but they were still less than 50%. The results indicate that the vegetation of P. australis wetlands has experienced a great improvement after several years' restoration, and it is feasible to restored degraded P. australis wetlands by pouring fresh water into those wetlands in the Yellow River Delta. However, it is notable that costal degraded P. australis wetland in this region may take years to decades to reach the status of natural wetland.

  13. Dissolved and colloidal trace elements in the Mississippi River Delta outflow after Hurricanes Katrina and Rita

    USGS Publications Warehouse

    Shim, Moo-Joon; Swarzenski, Peter W.; Shiller, Alan M.

    2012-01-01

    The Mississippi River delta outflow region is periodically disturbed by tropical weather systems including major hurricanes, which can terminate seasonal bottom water hypoxia and cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, Hurricanes Katrina and Rita passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we collected water samples in the Mississippi River delta outflow, examining the distributions of trace elements to study the effect of Hurricanes Katrina and Rita. We observed limited stratification on the shelf and bottom waters that were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn–O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 μm) from colloidal (0.02–0.45 μm) phase, revealed significant colloidal fractions for Fe and Zn, only. For Fe, the colloidal phase was the dominant fraction and was rapidly removed at low salinity. Dissolved Fe, in contrast, persisted out to mid-salinities, being removed in a similar fashion to nitrate. This ability to distinguish the smaller Fe (likely dominantly organically complexed) from larger colloidal suspensates may be useful in better interpreting the

  14. Presence of pyrethroid pesticides in water and sediments of Ebro River Delta

    NASA Astrophysics Data System (ADS)

    Feo, M. L.; Ginebreda, A.; Eljarrat, E.; Barceló, D.

    2010-11-01

    SummaryThe distribution of pyrethroid insecticides of the Ebro River Delta (NE Spain) was assessed by measuring concentrations in surface water and sediment samples. Pyrethroid extraction from water was carried out by ultrasound-assisted emulsification-extraction (UAEE), while the sediment was sonicated and cleaned up using Florisil cartridge. Method detection of limits (MLODs) for the 12 pyrethroids analyzed by gas chromatography-mass spectrometer in negative chemical ionization (GC-NCI-MS) ranged from 0.03 to 35.8 ng L -1 for water and 2.6 to 62.4 pg g -1 for sediment. Recoveries values were in the range of 47-105% for water and 51-105% for sediments, showing satisfactory robustness of the method for analyzing pyrethroids in water and sediment samples. Cypermethrin was detected in 22 water samples collected from Ebro River Delta, while deltamethrin was present only in three water samples at concentrations ranging from 0.73 ng L -1 to 57.2 ng L -1 and 2 ng L -1 to 58.8 ng L -1 for cypermethrin and deltamethrin, respectively. These concentration levels were higher than median lethal concentration (LC50) values found for deltamethrin and lower than LC50 values found for cypermethrin when short time toxic effects are considered. In sediment samples only cypermethrin was detected at concentration levels ranged from 8.27 ng g -1 to 71.9 ng g -1. These levels were higher than its LC50 values. Environmental dynamic behaviour and fate were also evaluated for cypermethrin measuring the sediment/water partition coefficient (ranging from 5.0 to 6.3) and kinetic data (half-life ranging between 13 and 50 days). Results were in good agreement to those reported in literature

  15. [HALOTOLERANCE OF ENTEROBACTERIA ISOLATED FROM WATER AND FISH IN THE VOLGA RIVER DELTA].

    PubMed

    Obukhova, O V; Lartseva, L V

    2015-01-01

    In the article there are presented the results of a study of halotolerance of enterobacteria isolated from water and fish in the Volga River delta, which were dominant in the microbial landscape of these biotopes. Their halotolerance was studied by means of inoculation of daily pure cultures of meat--peptone broth with 3, 7 and 10% of sodium chloride and incubation at 37°C. At that all studied microflora was found to have significant indices of halotolerance with a predominance of aquatic isolates. At that in 3,0 and 7,0 % NaCl concentrations were very similar, but in 10% NaCl broth the halotolerance of water strain was almost 2.0 times higher than the in fish ones. Among isolated Enterobacteriaceae most halophilic bacteria were from the Proteus group, Citrobacteria and Enterobacteria. The halotolerance of isolated enterobacteria in hydroecosystem of the Volga River delta had seasonal specificity and dynamics. There was established the dynamic growth of this sign in the water and fish strains from spring to autumn. Thus, the analysis of the obtained results of the long-term conducted study has shown the wide dissemination of conditionally pathogenic enterobacteria in water and fish, and their high halotolerance and the ability of some of them to remain viable up to salt production. It gives grounds to recommend the necessity of the introduction of them into the normative documentation in the implementation ofthe sanitary-microbiological control of not only raw materials but also ready salted fish production. PMID:26625611

  16. Vegetative ecological characteristics of restored reed (Phragmites australis) wetlands in the Yellow River Delta, China.

    PubMed

    Wang, Xuehong; Yu, Junbao; Zhou, Di; Dong, Hongfang; Li, Yunzhao; Lin, Qianxin; Guan, Bo; Wang, Yongli

    2012-02-01

    In this study, we compared ecological characteristics of wetland vegetation in a series of restoration projects that were carried out in the wetlands of Yellow River Delta. The investigated characteristics include plant composition structure, species diversity and community similarity in three kinds of Phragmites australis wetlands, i.e. restored P. australis wetlands (R1, R2, R3 and R4: restored in 2002, 2005, 2007 and 2009, respectively), natural P. australis wetland (N) and degraded P. australis wetland (D) to assess the process of wetlands restoration. The coverage of the R1 was 99%, which was similar to natural wetland. Among all studied wetlands, the highest and lowest stem density was observed in R1 and R2, respectively, Plant height and stem diameter show the same trend as N > R2 > R1 > R3 > D > R4. Species diversity of restored P. australis wetlands became closed to natural wetland. Both species richness and Shannon-Wiener index had similar tendency: increased first and then decreased with restored time. The highest species richness and species diversity were observed in R2, while the lowest values of those parameters were found in natural P. australis wetland. Similarity indexes between restored wetlands and natural wetland increased with the restoration time, but they were still less than 50%. The results indicate that the vegetation of P. australis wetlands has experienced a great improvement after several years' restoration, and it is feasible to restored degraded P. australis wetlands by pouring fresh water into those wetlands in the Yellow River Delta. However, it is notable that costal degraded P. australis wetland in this region may take years to decades to reach the status of natural wetland.

  17. Historical trace element distribution in sediments from the Mississippi River delta

    USGS Publications Warehouse

    Swarzenski, P.W.; Baskaran, M.; Rosenbauer, R.J.; Orem, W.H.

    2006-01-01

    Five sediment cores were collected on the shelf of the inner Mississippi Bight in June 2003 for a suite of radionuclides to establish geochronologies and trace elements to examine patterns of contaminant deposition and accumulation. Core sites were chosen to reflect a matrix of variable water depths, proximity to the Mississippi River mouth as the primary source for terrigenous particles, and extent and duration of summertime water column hypoxia. The vertical distribution of 239,240Pu and 210Pbxs (= 210Pbtotal - 226Ra) provided reliable geochronological age constraints to develop models for mass accumulation rates and historic trace element inputs and variations. Mass accumulation rates ranged from 0.27 to 0.87 g cm-2 yr-1 and were internally consistent using either 210Pbxs or 239,240Pu. Measured inventories of 137Cs, 239,240Pu, and 210Pbxs were compared to atmospheric deposition rates to quantify potential sediment focusing or winnowing. Observed variability in calculated mass accumulation rates may be attributed foremost to site-specific proximity to the river mouth (i.e., sediment source), variability in water depth, and enhanced sediment focusing at the Mississippi River canyon site. Trace element concentrations were first normalized to Al, and then Al-normalized enrichment factors (ANEF) were calculated based on preanthropogenic and crustal trace element abundances. These ANEFs were typically > 1 for V and Ba, while for most other elements studied, either no enrichment or depletion was observed. The enrichment of Ba may be related, in part, to the seasonal occurrence of oxygen-depleted subsurface waters off the Mississippi River delta, as well as being an ubiquitous by-product of the petroleum industry. ?? 2006 Estuarine Research Federation.

  18. Polycyclic aromatic hydrocarbons in riverine runoff of the Pearl River Delta (China): concentrations, fluxes, and fate.

    PubMed

    Wang, Ji-Zhong; Guan, Yu-Feng; Ni, Hong-Gang; Luo, Xian-Lin; Zeng, Eddy Y

    2007-08-15

    On the basis of a monthly sampling effort from March 2005 to February 2006, the total concentrations of the sums of 27 and 15 polycyclic aromatic hydrocarbons (defined as sigma27PAHs and sigma15PAHs, respectively) in riverine runoff of the Pearl River Delta (PRD), China, and associated fluxes were determined. No clear temporal and spatial trends of PAH concentrations were found at all eight riverine runoff outlets where the samples were collected. The annual fluxes of sigma27PAHs and sigma15PAHs from the PRD to the coastal ocean were 60.2 and 33.9 metric tons, respectively. Assuming that riverine flux was positively related to the regional emission of PAHs, the annual riverine fluxes from five major rivers in China to the global oceans were estimated, which are quite significant relative to other major rivers of the world. On the basis of mass balance considerations, approximately 87% of sigma15PAHs inputting to the Pearl River Estuary and northern South China Sea was derived from riverine runoff from the PRD. In addition, approcimately 22.3 metric tons of sigma15PAHs annually outflow to open seas, which is equivalent to a concentration of 0.34 pg/L in the global oceans if the PAHs are evenly distributed in the upper 200 m of the water column. A comparison with the global background level of PAHs indicated that approximately 0.4% of PAHs in the open oceans may have been contributed by 1-year discharge from the PRD.

  19. Historical Reconstruction of Organic Carbon Inputs to Sediments in the Colville River Delta, Alaska: The Application of Biomarker Proxies

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Bianchi, T. S.; Allison, M. A.

    2014-12-01

    Arctic permafrost represents about 50% of the total belowground global carbon pool, and thus the fate of this pool, as it thaws in the wake of global warming, warrants close attention. Large-river delta-front estuaries (LDEs) have been shown to be important recorders of natural and human-induced changes in watersheds, as they are critical zones for the exchange of organic carbon between the continents and the ocean. The Colville River is the largest North American Arctic River with a continuous permafrost watershed. Simpson's Lagoon, an eastward distal component of the Colville River Delta is an excellent location for historical reconstruction work since it is an area well protected from intense ice grounding and has minimal bioturbation. Sediment cores were collected from the mouth of the river and the lagoon in August of 2010, and analyzed for bulk organic carbon and nitrogen proxies, biomarkers (including lignin phenols, fatty acids), and compound-specific 13C isotope analysis (CSIA) of fatty acids. Downcore sediment data from CSIA of short-chain fatty acids (C14-C18) to the delta over the past ca. 50 years were found to be more depleted and had a wider isotopic range (-17.0~-33.2‰) than long-chain fatty acids (C22-C30, -30.3~-36.8‰). This possibly reflects alterations of inputs of freshwater flow to the delta which could have resulted in isotopic changes that caused corresponding changes in marine versus freshwater phytoplankton inputs. Downcore short-chain saturated and monounsaturated fatty acid profiles reflected differences in the abundance of bacteria and post-depositional decay of algal inputs across different regions of the delta. Ongoing analyses will also focus on compound-specific radiocarbon analyses (CSRA) of fatty acids and lignin phenols to better understand the changes of organic inputs from terrestrially-derived organic-rich horizons in surface soils vs. old deep permafrost-derived organic horizons.

  20. Distribution, source apportionment, and transport of PAHs in sediments from the Pearl River Delta and the northern South China Sea

    SciTech Connect

    Luo, X.J.; Chen, S.J.; Mai, B.X.; Sheng, G.Y.; Fu, J.M.; Zeng, E.Y.

    2008-07-15

    Polycyclic aromatic hydrocarbons (PAHs) were measured in 59 surface sediments from rivers in the Pearl River Delta and the northern continental shelf of the South China Sea. Total PAH concentrations varied from 138 to 6,793 ng/g dry weight. The sources of PAH inputs to sediments in the Pearl River Delta were qualitatively and quantitatively determined by diagnostic ratios and principal components analysis with multiple linear regression. The results showed that on average coal and wood combustion, petroleum spills, vehicle emissions, and nature sources contributed 36%, 27%, 25%, and 12% of total PAHs, respectively. Coal and biomass combustion was the main source of PAHs in sediments of the South China Sea, whereas petroleum combustion was the main source of pyrolytic PAHs in riverine and estuarine sediments of the Pearl River Delta. Perylene was formed in situ in river sediments and then transported to coastal areas along with other PAHs. The relative abundance of perylene from five-ring PAHs can be used to estimate the contribution of riverine-discharged PAHs to coastal sediments.

  1. Distribution, source apportionment, and transport of PAHs in sediments from the Pearl River Delta and the Northern South China Sea.

    PubMed

    Luo, Xiao-Jun; Chen, She-Jun; Mai, Bi-Xian; Sheng, Guo-Ying; Fu, Jia-Mo; Zeng, Eddy Y

    2008-07-01

    Polycyclic aromatic hydrocarbons (PAHs) were measured in 59 surface sediments from rivers in the Pearl River Delta and the northern continental shelf of the South China Sea. Total PAH concentrations varied from 138 to 6,793 ng/g dry weight. The sources of PAH inputs to sediments in the Pearl River Delta were qualitatively and quantitatively determined by diagnostic ratios and principal components analysis with multiple linear regression. The results showed that on average coal and wood combustion, petroleum spills, vehicle emissions, and nature sources contributed 36%, 27%, 25%, and 12% of total PAHs, respectively. Coal and biomass combustion was the main source of PAHs in sediments of the South China Sea, whereas petroleum combustion was the main source of pyrolytic PAHs in riverine and estuarine sediments of the Pearl River Delta. Perylene was formed in situ in river sediments and then transported to coastal areas along with other PAHs. The relative abundance of perylene from five-ring PAHs can be used to estimate the contribution of riverine-discharged PAHs to coastal sediments.

  2. Institutional and legal arrangements in the Nile river basin: suggestions to improve the current situation toward adaptive integrated water resources management.

    PubMed

    Abdalla, Khalid Mohamed El Hassan

    2008-01-01

    A comparative study was conducted in this work in order to investigate the current situation in the Nile river basin (NRB) regarding the institutional and legal arrangements needed to support the adaptive integrated water resources management (AIWRM) strategy. Two similar river basins were selected to achieve this comparison and to introduce suggestions to reform the current situation in the basin. Before that, the ideal situation is investigated to be as a yardstick for the desired situation. The study indicated that the necessary AIWRM criteria may include regulatory as well as implementation organizations that support shared-vision reaching with its all necessary features (cooperation, stakeholders' participation, subsidiarity, and information and knowledge exchange). Thus the main features of the desired situations regarding AIWRM in river basins are stakeholders' participation, learning-driven ability, quick response to risks and uncertainties, and finally a legal framework that could support these criteria. Although the AIWRM criteria seem to be satisfied in NRB, the basin lacks the necessary regulatory institutions as well as the legal framework. According to this, this study recommends to reform the current situation in NRB by creating regulator institutions (policy and decision making level) as well a legal framework to legitimate them.

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

    PubMed

    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.

  4. Emission inventory of anthropogenic air pollutants and VOC species in the Yangtze River Delta region, China

    NASA Astrophysics Data System (ADS)

    Huang, C.; Chen, C. H.; Li, L.; Cheng, Z.; Wang, H. L.; Huang, H. Y.; Streets, D. G.; Wang, Y. J.; Zhang, G. F.; Chen, Y. R.

    2011-05-01

    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, NOx, CO, PM10, PM2.5, 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, NOx, PM10, PM2.5, and VOC emissions. Vehicles take up 12.3 % and 12.4 % of the NOx 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.

  5. Arsenic in groundwater and sediment in the Mekong River delta, Vietnam.

    PubMed

    Hoang, Thi Hanh; Bang, Sunbaek; Kim, Kyoung-Woong; Nguyen, My Hoa; Dang, Duy Minh

    2010-08-01

    A study of groundwater and sediment during 2007-2008 in the Mekong River delta in Vietnam (MDVN) revealed that 26%, 74%, and 50% of groundwater samples were above the US EPA drinking water guidelines for As (10 microg/L), Mn (0.05 mg/L), and Fe (0.3 mg/L). The range of As, Fe, and Mn concentrations in the MDVN were <0.1-1351 microg/L, <0.01-38 mg/L, and <0.01-14 mg/L, respectively. Elevated levels of As were found in groundwater at sampling sites close to the Mekong River and in wells less than 60-70 m deep. An inverse relationship was found between As and Mn concentrations in groundwater. Sediment samples from An Giang and Dong Thap had the highest As concentrations (18 mg/kg and 38 mg/kg, respectively). Arsenic sediment occurred mainly in the poorly crystalline Fe oxide phases. Reductive dissolution of the Fe oxide phase is not necessarily the dominant mechanism of As release to groundwater.

  6. Recent decadal growth of the Atchafalaya River Delta complex: Effects of variable riverine sediment input and vegetation succession

    NASA Astrophysics Data System (ADS)

    Rosen, Timothy; Xu, Y. Jun

    2013-07-01

    The Mississippi River Delta Plain has experienced substantial wetland loss from subsidence, erosion, and sea level rise, threatening coastal communities and the ecosystems that support them. The Atchafalaya River, the largest distributary of the Mississippi River, has one of the few prograding delta features along the ~ 200-km deltaic coastline. Understanding changes in the Atchafalaya River Delta complex (ARDC) development has critical implications for future prediction and management strategy for the Mississippi River Delta Plain. This study was organized to answer two major questions: (1) how did development of the ARDC respond to fluctuation in riverine sediment supply over the period 1989-2010, and (2) has vegetation succession helped stabilize subaerial land? The study quantified annual total suspended sediment yields to the two ARDC subdeltas—Atchafalaya River subdelta (ARSD) and Wax Lake outlet subdelta (WLSD)—classified delta land cover using satellite imagery over ~ 5-year intervals into three classes: barren land, vegetation, and open water and investigated the relationship of delta land change with sediment yield and vegetation succession. Over the entire 21-year study period, we found a net land gain of 59 km2, with the ARSD accounting for 58% of this gain and WLSD 42%. Sediment yield to the subdeltas decreased from an average annual of 38 megatonnes (MT) for ARSD and 18 MT for WLSD during 1989-1995 to an average annual of 24 MT for ARSD and 17 MT for WLSD during 2004-2010, corresponding to the decrease in riverine suspended sediment concentration. Concurrently, total land growth rate decreased from 2.4 km2 y- 1 to 1.6 km2 y- 1 for ARSD and 3.2 km2 y- 1 to 0.6 km2 y- 1 for WLSD. However, the ARDC had a net land loss of 2.1 km2 during 1999-2004 because of tropical system effects in conjunction with the lack of large river floods (defined as discharge > 13,800 m3 s- 1). On average, more than 60% of newly vegetated land remained vegetated in

  7. Remote sensing applications: Environmental assessment of the Colorado River delta in Mexico

    NASA Astrophysics Data System (ADS)

    Nagler, Pamela Lynn

    The extent of revegetation in the Colorado River delta in Mexico is described, with emphasis on the return of native cottonwood (Populus fremontii ) and willow (Salix gooddingii) trees. Low-level aerial and satellite remote sensing methods were combined with ground surveys to census the vegetation in a 100 km reach of riparian corridor in Mexico. Although the invasive plant, saltcedar (Tamarix ramosissima), still dominates the riparian zone, native trees now account for 23% of the vegetation in the delta. Multi-band digital camera images obtained by aircraft were used to calculate the Normalized Difference Vegetation Index (NDVI) and scored for percent vegetation cover (NDVI:%C has r = 0.91***). A Thematic Mapper (TM) image taken concurrently with the aerial survey was similarly classified, and by comparing scenes on the TM and aerials, it was possible to calibrate NDVI with percent vegetation on the TM image. This information was used to conduct a change analysis relating flows in the Colorado River with summer vegetation patterns on TM images for the years 1992--1999. The results support the importance of pulse floods in restoring the ecological integrity of arid-zone rivers. This dissertation also compared transpiration rates of three Sonoran Desert riparian trees using sap flow and leaf temperature methods using constructed canopies (two of each species: Populus fremontii (cottonwood), Salix gooddingii (willow) and Tamarix ramosissima (saltcedar)) in an outdoor experiment in Tucson, Arizona. Canopies were measured over 11 days for both sap flow and canopy and air temperature differential (Tc-Ta) under non stressed and stressed conditions. Objective 1: to determine the strength of the relationship between transpiration (Et) and Tc-Ta to determine if Tc-Ta can be a useful remote sensing method to measure Et for these species. Objective 2: to compare Et rates among species, to determine if the invasive species, saltcedar, has higher Et rates or ecophysiological

  8. Architecture analysis of a river flood-dominated delta during an overall sea-level rise (early Pliocene, SE Spain)

    NASA Astrophysics Data System (ADS)

    García-García, F.; Corbí, H.; Soria, J. M.; Viseras, C.

    2011-05-01

    The sedimentary record of delta-front to prodelta transition that developed during the early Pliocene (Bajo Segura Basin, peri-Mediterranean Betic Cordillera Basin) represents an unusual infilling of an incised valley cutting downwards into late Messinian pelagic marls. The complete delta succession, less than 65 m thick, consists of four upwardly fining and thinning sequences several metres thick. Each sequence consists of basal conglomeratic and coarse-grained sandstone beds (delta-front deposits) evolving upwards to alternating sandstones and silty-marl beds (prodelta deposits). The retrogradational stratal succession pattern is interpreted as having been deposited during an overall sea-level rise. Facies association is characterised by quasi- to planar-laminated sandstones and pebbly sandstones alternating with clast-supported boulders to pebbles, sheet-like climbing cross-laminated sandstones with abundant plant remains, and epsilon cross-stratified and channelized gravels and sandstones. These are interpreted as having been deposited by highly concentrated flows interpreted as hyperpycnal turbidity flows from high (cohesionless debris flows and sinuous submarine channels) to moderate (sheet-like climbing cross-laminated sandstones) discharge river-flood events. Slabs of sediment from unstable banks, outsized clasts which roll onto thin beds from channel mouths, slumps and intraformational breccias in delta front are other signatures (including a lack of bored clasts) which indicate high-energy and rapid deposition at the river mouth, encouraging the delta-front gravitational instability failures. Major changes in the discharge of the river-fed delta could have been caused by brief catastrophic, heavy-precipitation events coupled with quasi-stationary convective orographic rainfall typical of the modern Mediterranean.

  9. Dynamic Emulation Modeling of irrigation water deficit in the Red-Thai Binh River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Dinh, Q.; Cassaro, L.; Micotti, M.; Soncini-Sessa, R.

    2013-12-01

    real-world case study: the Red-Thai Binh River Delta in Vietnam. It is a large and complex river system, supplied by five unregulated rivers and four large multi-purpose reservoirs, the operating rules of which have to be designed. In order to ascertain the effects of their regulation on the WD in the Delta, a Mike11 model was calibrated and validated. It describes 320 rivers and canals for a total length of 4200 km, 11 irrigation districts and many structures, among which 88 sluice gates and 302 irrigation water intakes (simulated as controlled pumps). Its inputs are the four reservoirs releases, the non-regulated flows of the five rivers, the sea levels at the nine river mouths, the water demand at each one of the irrigation water intakes. The considered outputs are the daily WD in the 11 districts. The dimension of the state vector of the model is of the order of 16,000. From the high dimensional Mike11, a low dimensional (11 dimension) DEMo model was identified that mimics very well (R2=0.95) the WDs as computed by the Mike11 model. The DEMo model will be later on embedded within a large multi-objective optimal control problem to design the operating rules of the four reservoirs.

  10. Large-river delta-front estuaries as natural “recorders” of global environmental change

    PubMed Central

    Bianchi, Thomas S.; Allison, Mead A.

    2009-01-01

    Large-river delta-front estuaries (LDE) are important interfaces between continents and the oceans for material fluxes that have a global impact on marine biogeochemistry. In this article, we propose that more emphasis should be placed on LDE in future global climate change research. We will use some of the most anthropogenically altered LDE systems in the world, the Mississippi/Atchafalaya River and the Chinese rivers that enter the Yellow Sea (e.g., Huanghe and Changjiang) as case-studies, to posit that these systems are both “drivers” and “recorders” of natural and anthropogenic environmental change. Specifically, the processes in the LDE can influence (“drive”) the flux of particulate and dissolved materials from the continents to the global ocean that can have profound impact on issues such as coastal eutrophication and the development of hypoxic zones. LDE also record in their rapidly accumulating subaerial and subaqueous deltaic sediment deposits environmental changes such as continental-scale trends in climate and land-use in watersheds, frequency and magnitude of cyclonic storms, and sea-level change. The processes that control the transport and transformation of carbon in the active LDE and in the deltaic sediment deposit are also essential to our understanding of carbon sequestration and exchange with the world ocean—an important objective in global change research. U.S. efforts in global change science including the vital role of deltaic systems are emphasized in the North American Carbon Plan (www.carboncyclescience.gov). PMID:19435849

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

    SciTech Connect

    Dobson, Robin

    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

  12. High-resolution (spatial and temporal) Hydrodynamic Modeling in the Lower Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Karadogan, E.; Danchuk, S.; Berger, C.; Brown, G.; Willson, C.

    2007-12-01

    The lower Mississippi River is a highly engineered system existing in one of the world's largest deltas. This system is subject to a variety of spatial and temporal forcings due to its large watershed (drains about 41% of the continental U.S.) and from the Gulf of Mexico. Future perturbations on this system are anticipated due to the impacts of global climate change (e.g., rising eustatic sea level, changes in weather patterns) and from proposed modifications to the system such as diversion structures aimed at providing freshwater nutrients and sediments to the rapidly degrading coastal wetlands. Numerical modeling will play a large role in improving our understanding and management of the system and the ability to properly design future structural features. These models will need to have the necessary spatial and temporal resolution to account for the many important processes in the river, the Gulf of Mexico, and in the wetland areas where small distributary channels will form and wetting/drying must be accounted for. This paper will investigate the ability of a 2D shallow water and sediment model to reproduce the complex distributary development associated with flow diversions into quiescent bays. A reach of the Lower Mississippi River from Point a la Hache to the Gulf of Mexico was used as a test domain to evaluate the performance and capabilities of the U.S. Army Corps of Engineers ADaptive Hydraulics (ADH) model. ADH is an unstructured finite element modeling system that includes unsaturated Richards' equations for groundwater, Navier Stokes for nonhydrostatic flow calculations, and Shallow Water equations. ADH conducts automated refinement and coarsening of the mesh based upon flow characteristics. In this case the 2D shallow water model is being used. It includes coupled flow and sedimentation. An unstructured mesh was developed for the study area which includes detailed bathymetry and topography from available survey data. The mesh is fine enough to capture

  13. High Frequency Time-series of the Dynamic Sedimentation Processes on the Western Shelf of the Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Dail, M. B.; Corbett, D. R.; McKee, B.; Duncan, D.

    2004-12-01

    Rivers annually transport billions of tons of organic and inorganic sediment to coastal environments, making them an extremely important part of global biogeochemical cycles. However, the majority of the freshwater and suspended materials are delivered to the coastal ocean by only a few rivers. In these river-dominated ocean margins (RiOMar), sediments are deposited and re-suspended repeatedly before stable deposition. This sediment cycling is poorly understood and is critical to understanding how deltas and continental shelves, considered to be major repositories of organic carbon in marine sediments, manipulate the global carbon cycle and biogeochemical processes affecting coastal environments. During six cruises in the fall of 2003 (October, November, and December) and spring of 2004 (March, April, and May), on the shelf west of the Mississippi River Delta, sediment samples collected from cores were analyzed for particle reactive radionuclides (210Pb, 137Cs, and 234Th) to create a quantitative high frequency time-series of sediment deposition and erosion processes and evaluate the transport and fate of material on the shelf. Based on previous work completed by Corbett et al. (2004), seasonal variations in short-lived tracers could be explained by river flow and weather conditions. Inventories of the tracers collected during the fall cruises suggest increased deposition during the late summer months and that most sediment reworking and export occurs during the winter months, typically a period of low/increasing river discharge and increased weather forcing.

  14. Sustainability of massively anthropic deltas via dispersal of sediment to manage land building: results from two unique case studies, the Mississippi River (U.S.A.) and the Yellow River (China) deltas

    NASA Astrophysics Data System (ADS)

    Nittrouer, Jeffrey

    2016-04-01

    studies of both the Mississippi and Yellow rivers have been used to inform and validate numerical modeling efforts that seek to replicate the morphodynamics of the two diversions. The aim is to evaluate best practices for building deltaic landscape. Based on these research efforts, there are key similarities found for the delta systems: 1) coarse (sandy) sediment is the primary contributor to subaerial delta development, despite the abundance of mud for both rivers; 2) the influx of freshwater into estuarine regions of deltas has tremendous impact on vegetation development, and therefore the cohesion of the deltaic sediment deposit; and 3) it is feasible to produce efficient diversions that maximize sediment delivery and still provide for continued use of the riverine resource (for example, navigation of the channel by vessels). These findings are critical when considering future plans that seek sustainable management practices of other large, anthropic fluvial deltaic systems.

  15. Groundwater response to the 2014 pulse flow in the Colorado River Delta

    USGS Publications Warehouse

    Kennedy, Jeffrey; Rodriguez-Burgueno, Eliana; Ramirez-Hernandez, Jorge

    2016-01-01

    During the March-May 2014 Colorado River Delta pulse flow, approximately 102 × 106 m3 (82,000 acre-feet) of water was released into the channel at Morelos Dam, with additional releases further downstream. The majority of pulse flow water infiltrated and recharged the regional aquifer. Using groundwater-level and microgravity data we mapped the spatial and temporal distribution of changes in aquifer storage associated with pulse flow. Surface-water losses to infiltration were greatest around the Southerly International Boundary, where a lowered groundwater level owing to nearby pumping created increased storage potential as compared to other areas with shallower groundwater. Groundwater levels were elevated for several months after the pulse flow but had largely returned to pre-pulse levels by fall 2014. Elevated groundwater levels in the limitrophe (border) reach extended about 2 km to the east around the midway point between the Northerly and Southerly International Boundaries, and about 4 km to the east at the southern end. In the southern part of the delta, although total streamflow in the channel was less due to upstream infiltration, augmented deliveries through irrigation canals and possible irrigation return flows created sustained increases in groundwater levels during summer 2014. Results show that elevated groundwater levels and increases in groundwater storage were relatively short lived (confined to calendar year 2014), and that depressed water levels associated with groundwater pumping around San Luis, Arizona and San Luis Rio Colorado, Sonora cause large, unavoidable infiltration losses of in-channel water to groundwater in the vicinity.

  16. Coastal Vulnerability and Load Induced Subsidence of the Modern Mississippi River Delta and Environs

    NASA Astrophysics Data System (ADS)

    Dokka, R. K.; Ivins, E. R.; Blom, R. G.

    2006-12-01

    The disasters wrought by Hurricanes Katrina and Rita along the northern Gulf coast have heightened our awareness of the vulnerability of this low-lying landscape to storm surge. Although topographically subdued, the surface is the product of the dynamic interplay between the processes of subsidence, sediment accretion, and eustasy. Quantification and determination of causative processes of subsidence are thus essential as Society rebuilds and protects communities and contemplates restoration of the coastal ecosystem. Previous models for subsidence have emphasized the roles of shallow compaction and anthropomorphic effects. We agree that these processes are important, but also note that the isostatic impact of both the load of the delta sediments and the effects of water loading following glacial intervals have never been integrated into landscape models. It is thus not surprising that previous models cannot explain the recent geodetic measurements that show that subsidence is geographically more extensive and has been occurring at rates faster than previously anticipated. Here, we explore the combined 3-D physical implications of both sediment loading (delta) and water loading (eustasy) in south Louisiana and Mississippi over the course of the last several glacial cycles. Our models are based on a viscoelastic Earth and successfully explain the gross magnitude of modern subsidence measured by GPS, leveling, InSAR, and mareographs throughout the region. In areas of significant anomalies (spikes in observed subsidence rates that cannot be explained by load models), most can be explained as consequences of local processes such as faulting, fluid withdrawal (generally water), and drainage projects. The models suggest the possibility that additional loads (alluvial valley of the Mississippi River and offshore deposits) also play a role in subsidence.

  17. Distribution and condition of larval and juvenile Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Burdick, Summer M.; Brown, Daniel T.

    2010-01-01

    Federally endangered Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were once abundant throughout their range but populations have declined. They were extirpated from several lakes in the 1920s and may no longer reproduce in others. Poor recruitment to 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 or high quality rearing habitat. In addition, larval suckers may be swept downstream from suitable rearing areas in Upper Klamath Lake into Keno Reservoir, which is seasonally anoxic. The Nature Conservancy flooded about 3,600 acres (1,456 hectares) to the north of the Williamson River mouth (Tulana Unit) in October 2007 and about 1,400 acres (567 hectares) 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, and improve water quality. The U.S. Geological Survey joined a long-term research and monitoring program in collaboration with The Nature Conservancy, the Bur