WorldWideScience

Sample records for gorges dam affects

  1. The Three Gorges Dam Affects Regional Precipitation

    Science.gov (United States)

    Wu, Liguang; Zhang, Qiang; Jiang, Zhihong

    2006-01-01

    Issues regarding building large-scale dams as a solution to power generation and flood control problems have been widely discussed by both natural and social scientists from various disciplines, as well as the policy-makers and public. Since the Chinese government officially approved the Three Gorges Dam (TGD) projects, this largest hydroelectric project in the world has drawn a lot of debates ranging from its social and economic to climatic impacts. The TGD has been partially in use since June 2003. The impact of the TGD is examined through analysis of the National Aeronautics and Space Administration (NASA) Tropical Rainfall Measuring Mission (TRMM) rainfall rate and Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature and high-resolution simulation using the Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) fifth-generation Mesoscale Model (MM5). The independent satellite data sets and numerical simulation clearly indicate that the land use change associated with the TGD construction has increased the precipitation in the region between Daba and Qinling mountains and reduced the precipitation in the vicinity of the TGD after the TGD water level abruptly rose from 66 to 135 m in June 2003. This study suggests that the climatic effect of the TGD is on the regional scale (approx.100 km) rather than on the local scale (approx.10 km) as projected in previous studies.

  2. After Three Gorges Dam: What have we learned?

    Science.gov (United States)

    Natali, J.; Williams, P.; Wong, R.; Kondolf, G. M.

    2013-12-01

    China is at a critical point in its development path. By investing heavily in large-scale infrastructure, the rewards of economic growth weigh against long-term environmental and social costs. The construction of Three Gorges Dam, the world's largest hydroelectric project, began in 1994. Between 2002 and 2010, its 660 kilometer reservoir filled behind a 181 meter dam, displacing at least 1.4 million people and transforming Asia's longest river (the Yangtze) while generating nearly 100 billion kWh/yr of electricity -- 2.85% of China's current electric power usage. As the mega-project progenitor in a cascade of planned dams, the Three Gorges Dam emerges as a test case for how China will plan, execute and mitigate its development pathway and the transformation of its environment. Post-Project Assessments (PPA) provide a systematic, scientific method for improving the practice of environmental management - particularly as they apply to human intervention in river systems. In 2012, the Department of Landscape Architecture and Environmental Planning at University of California, Berkeley organized a symposium-based PPA for the Three Gorges Dam on the Yangtze River. Prior to this symposium, the twelve invited Chinese scientists, engineers and economists with recent research on Three Gorges Dam had not had the opportunity to present their evaluations together in an open, public forum. With a 50-year planning horizon, the symposium's five sessions centered on impacts on flows, geomorphology, geologic hazards, the environment and socioeconomic effects. Three Gorges' project goals focused on flood control, hydropower and improved navigation. According to expert research, major changes in sediment budget and flow regime from reservoir operation have significantly reduced sediment discharge into the downstream river and estuary, initiating a series of geomorphic changes with ecological and social impacts. While the dam reduces high flow stages from floods originating above the

  3. Assessment of the Physicochemical Quality of Challawa Gorge Dam ...

    African Journals Online (AJOL)

    Dr Maimuna

    Water and sediment samples were collected from Challawa Gorge dam during the wet and dry seasons and analyzed for some physicochemical parameters, heavy metals (Cd, Cr, Mn, Pb, Zn) and minerals (Na and K) using Atomic Absorption Spectrophotometric and Flame Photometric techniques. The results showed the.

  4. Assessment of the Physicochemical Quality of Challawa Gorge Dam ...

    African Journals Online (AJOL)

    Water and sediment samples were collected from Challawa Gorge dam during the wet and dry seasons and analyzed for some physicochemical parameters, heavy metals (Cd, Cr, Mn, Pb, Zn) and minerals (Na and K) using Atomic Absorption Spectrophotometric and Flame Photometric techniques. The results showed the ...

  5. Linking Three Gorges Dam and downstream hydrological regimes along the Yangtze River, China

    NARCIS (Netherlands)

    Mei, X.; Dai, Z.; Van Gelder, P.H.A.J.M.; Gao, J.

    2015-01-01

    The magnitude of anthropogenic influence, especially dam regulation, on hydrological system is of scientific and practical value for large river management. As the largest dam in the world by far, Three Gorges Dam (TGD) is expected to be a strong evidence on dam impacts on downstream hydrological

  6. Channel evolution under changing hydrological regimes in anabranching reaches downstream of the Three Gorges Dam

    Science.gov (United States)

    Han, Jianqiao; Zhang, Wei; Yuan, Jing; Fan, Yongyang

    2018-03-01

    Elucidating the influence of dams on fluvial processes can benefit river protection and basin management. Based on hydrological and topographical data, we analyzed channel evolution in anabranching reaches under changing hydrological regimes influenced by the Three Gorges Dam. The main conclusions are as follows: 1) the channels of specific anabranching reaches were defined as flood trend channels or low-flow trend channels according to the distribution of their flow characteristics. The anabranching reaches were classified as T1 or T2. The former is characterized by the correspondence between the flood trend and branch channels, and the latter is characterized by the correspondence between the flood trend and main channels; 2) on the basis of the new classification, the discrepant patterns of channel evolution seen in anabranching reaches were unified into a pattern that showed flood trend channels shrinking and low-flow trend channels expanding; 3) flood abatement and the increased duration of moderate flow discharges are the main factors that affect channel adjustments in anabranching reaches after dam construction; and 4) in the next few decades, the pattern of channel evolution will remain the same as that of the Three Gorges Dam operation. That is, the morphology will fully adapt to a flow with a low coefficient of variation. Our results are of interest in the management of the Yangtze River and other rivers influenced by dams.

  7. Accumulation of floating microplastics behind the Three Gorges Dam.

    Science.gov (United States)

    Zhang, Kai; Gong, Wen; Lv, Jizhong; Xiong, Xiong; Wu, Chenxi

    2015-09-01

    We investigated the occurrence and distribution of microplastics in surface water from the Three Gorges Reservoir. Nine samples were collected via trawl sampling with a 112 μmmesh net. The abundances of microplastics were from 3407.7 × 10(3) to 13,617.5 × 10(3) items per square kilometer in the main stream of the Yangtze River and from 192.5 × 10(3) to 11,889.7 × 10(3) items per square kilometer in the estuarine areas of four tributaries. The abundance of microplastics in the main stream of the Yangtze River generally increased as moving closer to the Three Gorges Dam. The microplastics are made exclusively of polyethylene (PE), polypropylene (PP), and polystyrene (PS). Together with microplastics, high abundance of coal/fly ash was also observed in the surface water samples. Comparing with previously reported data, microplastics in the TGR were approximately one to three orders of magnitudes greater, suggesting reservoirs as potential hot spot for microplastic pollution. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Downstream Yangtze River levels impacted by Three Gorges Dam

    International Nuclear Information System (INIS)

    Wang, Jida; Sheng, Yongwei; Gleason, Colin J; Wada, Yoshihide

    2013-01-01

    Changes in the Yangtze River level induced by large-scale human water regulation have profound implications on the inundation dynamics of surrounding lakes/wetlands and the integrity of related ecosystems. Using in situ measurements and hydrological simulation, this study reveals an altered Yangtze level regime downstream from the Three Gorges Dam (TGD) to the Yangtze estuary in the East China Sea as a combined result of (i) TGD’s flow regulation and (ii) Yangtze channel erosion due to reduced sediment load. During the average annual cycle of TGD’s regular flow control in 2009–2012, downstream Yangtze level variations were estimated to have been reduced by 3.9–13.5% at 15 studied gauging stations, manifested as evident level decrease in fall and increase in winter and spring. The impacts on Yangtze levels generally diminished in a longitudinal direction from the TGD to the estuary, with a total time lag of ∼9–12 days. Chronic Yangtze channel erosion since the TGD closure has lowered water levels in relation to flows at most downstream stations, which in turn counteracts the anticipated level increase by nearly or over 50% in winter and spring while reinforcing the anticipated level decrease by over 20% in fall. Continuous downstream channel erosion in the near future may further counteract the benefit of increased Yangtze levels during TGD’s water supplement in winter and accelerate the receding of inundation areas/levels of downstream lakes in fall. (letter)

  9. Simulation analysis of within-day flow fluctuation effects on trout below flaming Gorge Dam.

    Energy Technology Data Exchange (ETDEWEB)

    Railsback, S. F.; Hayse, J. W.; LaGory, K. E.; Environmental Science Division; EPRI

    2006-01-01

    In addition to being renewable, hydropower has the advantage of allowing rapid load-following, in that the generation rate can easily be varied within a day to match the demand for power. However, the flow fluctuations that result from load-following can be controversial, in part because they may affect downstream fish populations. At Flaming Gorge Dam, located on the Green River in northeastern Utah, concern has been raised about whether flow fluctuations caused by the dam disrupt feeding at a tailwater trout fishery, as fish move in response to flow changes and as the flow changes alter the amount or timing of the invertebrate drift that trout feed on. Western Area Power Administration (Western), which controls power production on submonthly time scales, has made several operational changes to address concerns about flow fluctuation effects on fisheries. These changes include reducing the number of daily flow peaks from two to one and operating within a restricted range of flows. These changes significantly reduce the value of the power produced at Flaming Gorge Dam and put higher load-following pressure on other power plants. Consequently, Western has great interest in understanding what benefits these restrictions provide to the fishery and whether adjusting the restrictions could provide a better tradeoff between power and non-power concerns. Directly evaluating the effects of flow fluctuations on fish populations is unfortunately difficult. Effects are expected to be relatively small, so tightly controlled experiments with large sample sizes and long study durations would be needed to evaluate them. Such experiments would be extremely expensive and would be subject to the confounding effects of uncontrollable variations in factors such as runoff and weather. Computer simulation using individual-based models (IBMs) is an alternative study approach for ecological problems that are not amenable to analysis using field studies alone. An IBM simulates how a

  10. Analysis of potential impacts of Flaming Gorge Dam hydropower operations on archaeological sites

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, K.L.; Malinowski, L.M.; Hoffecker, J.F.

    1955-12-01

    An archaeological field study was conducted along the Green River in the areas of Little Hole and Browns Park in Utah and Colorado. The purpose of the study was to measure the potential for hydropower operations at Flaming Gorge Dam to directly or indirectly affect archaeological sites in the study area. Thirty-four known sites were relocated, and six new sites were recorded. Information was collected at each site regarding location, description, geomorphic setting, sedimentary context, vegetation, slope, distance from river, elevation above river level, and site condition. Matching the hydrologic projections of river level and sediment load with the geomorphic and sedimentary context at specific site locations indicated that eight sites were in areas with a high potential for erosion.

  11. Assessment of pollutant biodegradation at the Yangtze three gorges dam, China

    Energy Technology Data Exchange (ETDEWEB)

    Kranzioch, Irene; Tiehm, Andreas [DVGW Technologiezentrum Wasser (TZW), Karlsruhe (Germany)

    2012-07-01

    The microbiological degradation of pollutants in the aquatic environment is affected by several key factors such as (1) the composition of the microbial community, (2) the oxidation-reduction-conditions, i.e. the availability of electron acceptors and electron donors, and (3) the mass transfer processes (e.g. biovailability of pollutants). As part of the joint Sino-German Yangtze project (www.yangtze-project.de), the Water Technology Centre (TZW) studies the microbial transformation processes with samples taken at the three gorges dam (TGD) area. In particular molecular microbiological methods such as the Polymerase Chain Reaction (PCR) are adapted and applied for a specific monitoring. The first studies focussed on the presence of dechlorinating bacteria and the degradation of halogenated substances. The experiments provide more insight into biodegradation processes and thus contribute to a better understanding of pollutant conversion in the Yangtze area. (org.)

  12. The Three Gorges Dam: A great leap backward for China's electricity consumers and economy

    International Nuclear Information System (INIS)

    Adams, P.; Ryder, G.

    1999-01-01

    Reasons why the Three Gorges Dam, the largest hydroelectric power project in the world, is not only an environmental disaster, but also an economically unsound undertaking for the Chinese economy are discussed. The thrust of the argument is that rapid advancement in technology, in combination with the economic reforms to decentralize electric power production in China, will allow private enterprise to be in direct competition with the Three Gorges (and other bid dam) projects. These factors, combined with the economic pressures resulting from the shutting down of money-losing state enterprises and consequently, a significant reduction in the demand for electricity, spell disaster for the big dam projects conceived during the centrally-planned, Maoist era. Because of the Three Gorges project's unusually large size, the outdated and unreliable power transmission networks in China, and because the local state transmission grids are not connected to China's national grid, the central government will have to invest some $ 30 billion over the next three years in a new national transmission grid. The aggregate result of these events will be that competition from cheaper, cleaner power producers (such as combined cycle power producers) will price the Three Gorges power out of the market by the time it is expected to go into production in 2009. Based on the assessment of reputable world economic and engineering organizations, Probe International recommends cancellation of the project to avoid environmental and economic disaster. 61 refs

  13. Will river erosion below the Three Gorges Dam stop in the middle Yangtze?

    Science.gov (United States)

    Lai, X.; Yin, D.; Finlayson, B. L.; Wei, T.; Li, M.; Yuan, W.; Yang, S.; Dai, Z.; Gao, S.; Chen, Z.

    2017-11-01

    The environmental impact of the Three Gorges Dam has been a subject of vigorous academic, political and social debate since its inception. This includes the key issue of post-dam river channel erosion, which was predicted by the feasibility study to extend to the river mouth. In this paper we examine the geomorphic response of the channel of the middle Yangtze for 660 km downstream of the dam. Using data on channel characteristics, bed material and sediment transport, we show that in the decade following the dam closure, pre-dam seasonal erosion has been replaced by year-round erosion, a pattern most marked at the upstream end of the study area. The sediment carrying capacity of the river channel has been largely reduced below the dam. The locus of bed scour has moved progressively downstream, ceasing as the bed material became too coarse to be transported (e.g. D50: 0.29 mm pre-dam coarsened to 20 mm below the dam by 2008). About 400 km below the dam there is a reduction in channel slope that changes the sediment carrying capacity from 0.25 kg m-3 to only about 0.05 kg m-3, which is insufficient to move bed sediment. The new long-term hydro-morphological equilibrium that will be established in this section of the middle Yangtze will prevent the further incision downstream initiated by the Three Gorges Dam. The results suggest that the full extent of adverse environmental impact predicted by the pre-dam studies will not eventuate.

  14. Use of aerial videography to evaluate the effects of Flaming Gorge Dam operations on natural resources of the Green River

    International Nuclear Information System (INIS)

    Snider, M.A.; Hayse, J.W.; Hlohowskyj, I.; LaGory, K.E.; Greaney, M.M.; Kuiper, J.A.; Van Lonkhuyzen, R.A.

    1993-01-01

    Peaking hydropower operations can profoundly alter natural stream flow and thereby affect the natural resources dependent on these flows. In this paper, we describe how aerial videography was used to collect environmental data and evaluate impacts of hydropower operations at Flaming Gorge Dam on natural resources of the Green River. An airborne multispectral video/radiometer remote sensing system was used to collect resource data under four different flow conditions from seven sites (each about one mile in length) located downstream from the dam. Releases from Flaming Gorge Dam during data collection ranged from approximately 800 to 4,000 cubic feet/sec (cfs), spanning most of the normal operating range for this facility. For each site a series of contiguous, non-overlapping images was prepared from the videotapes and used to quantify surface water area, backwater habitats, and areas of riparian vegetation under varying flow conditions. From this information, relationships between flow and habitat parameters were developed and used in conjunction with hydrologic modeling and ecological information to evaluate impacts of various modes of operation

  15. Diversity of microbial plankton across the Three Gorges Dam of the Yangtze River, China

    Directory of Open Access Journals (Sweden)

    Shang Wang

    2012-05-01

    Full Text Available The Three Gorges Dam (TGD of the Yangtze River, China, is one of the largest irrigation and hydroelectric engineering projects in the world. The effects of huge man-made projects like TGD on fauna and macrophyte are obvious, mainly through changes of water dynamics and flow pattern; however, it is less clear how microorganisms respond to such changes. This research was aimed to examine differences in microbial diversity at different seasons and locations (in front of and behind the TGD. In addition, differences between particle-attached and free-living communities were also examined. The community structures of total and potentially active microorganisms in the water columns behind and in front of the TGD were analyzed with the DNA- and RNA-based 16S rRNA gene phylogenetic approaches over three different seasons. Clone libraries of 16S rRNA genes were prepared after amplification from extracted DNA and, for some samples, after preparing cDNA from extracted rRNA. Differences were observed between sites at different seasons and between free-living and particle-attached communities. Both bacterial and archaeal communities were more diverse in summer than in winter, due to higher nutrient levels and warmer temperature in summer than in winter. Particle-attached microorganisms were more diverse than free-living communities, possibly because of higher nutrient levels and heterogeneous geochemical micro-environments in particles. Spatial variations in bacterial community structure were observed, i.e., the water reservoir behind the TGD (upstream hosted more diverse bacterial populations than in front of the dam (downstream, because of diverse sources of sediments and waters from upstream to the reservoir. These results have important implications for our understanding of responses of microbial communities to environmental changes in river ecosystems affected by dam construction.

  16. Impact of the Three Gorges Dam on the Hydrology and Ecology of the Yangtze River

    Directory of Open Access Journals (Sweden)

    Xiao Zhang

    2016-12-01

    Full Text Available Construction and operation of the Three Gorges Dam (TGD has significantly altered the downstream hydrological regime along the Yangtze River, which has in turn affected the environment, biodiversity and morphological configuration, and human development. The ecological and environmental systems of the middle and lower Yangtze River have been affected adversely, with the ecosystems of Poyang Lake and its deltas being among the most damaged. Besides posing a potential threat to the survival of migrant birds and aquatic species, operation of the TGD has also affected the human population, particularly with respect to water and food security. Though the above mentioned effects have been studied in previous papers, a comprehensive discussion has never been conducted. This paper provides the first ever summary of the impacts of the TGD on the downstream reaches of the Yangtze River. The costs and benefits identified provide a constructive reference that can be used in decision-making for sustainable development of water resources in other nations, especially those in the developing world.

  17. The Sasso Pizzuto landslide dam and seismically induced rockfalls along the Nera River gorge (Central Italy).

    Science.gov (United States)

    Romeo, Saverio; Di Matteo, Lucio; Melelli, Laura; Cencetti, Corrado; Dragoni, Walter; Fredduzzi, Andrea; De Rosa, Pierluigi

    2017-04-01

    The seismically induced landslides are among the most destructive and dangerous effects of an earthquake. In the Italian contest, this is also documented by a national catalogue that collects data related to earthquake-induced ground failures in the last millennium (CEDIT database). In particular, Central Italy has been affected by several historical landslides triggered by significant earthquakes, the last of which occurred in August-October 2016, representing the Italian strongest event after the 1980 Irpinia earthquake (Mw 6.9). The study presents the effects of recent seismically induced rockfalls occurred within the Central Italy seismic sequence (October 30, 2016) along the Nera River gorge between Umbria and Marche. The study area is completely included in the Monti Sibillini National Park, where the highest mountain chain in the Umbrian-Marchean Apennine is located. Most of rockfalls have affected the "Maiolica" formation, a stratified and fractured pelagic limestone dating to the Early Cretaceous. The seismic sequence produced diffuse instabilities along the SP 209 road within the Nera River gorge: boulders, debris accumulations and diffuse rockfalls have been mapped. Most of boulders have size ranging from 0.3 to 2.0 m in diameter. Although several strong quakes (Mw > 5) occurred during the August-October sequence, only the main quake triggered the Sasso Pizzuto rockfall producing a landslide dam along the Nera River. The landslide appears to have originated as a wedge failure, which evolved to free fall when the rock block lost the contact with the stable rock mass. In other words, the quake produced the "explosion" of the rock wall allowing the rockfall process. Once the rock mass reached the toe of the slope, it was broken triggering a rock avalanche that obstructed both the Nera River and SP 209 road. With the aim to estimate the total volume of involved rock, a field survey was carried out by using a laser rangefinder. Remote measures were acquired

  18. Geographical Overview of the Three Gorges Dam and Reservoir, China - Geologic Hazards and Environmental Impacts

    Science.gov (United States)

    Highland, Lynn M.

    2008-01-01

    The Three Gorges Dam and Reservoir on the Yangtze River, China, has been an ambitious and controversial project. The dam, the largest in the world as of 2008, will provide hydropower, help to manage flood conditions, and increase the navigability of the Yangtze River. However, this massive project has displaced human and animal populations and altered the stability of the banks of the Yangtze, and it may intensify the seismic hazard of the area. It has also hindered archeological investigations in the reservoir and dam area. This report, originally in the form of a Microsoft PowerPoint presentation, gives a short history and overview of the dam construction and subsequent consequences, especially geologic hazards already noted or possible in the future. The report provides photographs, diagrams, and references for the reader's further research - a necessity, because this great undertaking is dynamic, and both its problems and successes continue to evolve. The challenges and consequences of Three Gorges Dam will be closely watched and documented as lessons learned and applied to future projects in China and elsewhere.

  19. Chinese engineers and scientists urge leadership to change Three Gorges Dam operating plan

    International Nuclear Information System (INIS)

    2000-01-01

    An appeal to the Chinese Leadership by a group of senior engineers, water management experts and academics about the dire consequences of filling the Three Gorges reservoir on the Yangtze River to 175 metres, is reported. Originally, the plan was to keep water levels behind the Three Gorges Dam at 156 metres for the first ten years of operation, in order to allow for resettlement of people displaced by building the dam, and to evaluate the impact of silt deposits on navigation and ports at the upper end of the reservoir. Plans have changed in 1997; the water level is now scheduled to rise to 175 metres in the sixth year of the dam's operation in order to maximize the dam's power output. The appeal by 53 experts warned the Chinese Government that the filling of the reservoir to 175 metres would displace 1.13 million people and raise the water level in the Yangtze River more than 10 metres at Chongqing City, submerging drainage outlets and backing up the city's sewage, as well as increase silt deposits, blocking shipping traffic along the Yangtze River. A parallel is drawn with the Sanmenxia Dam on the Yellow River. It was completed in 1960; it has proven to be useless for controlling floods while producing only one-third of its expected output due to massive silt build-up in the reservoir

  20. Assessing the impacts of Three Gorges Dam on lake inundation areas across the downstream Yangtze floodplain

    Science.gov (United States)

    Wang, J.; Sheng, Y.; Wada, Y.

    2013-12-01

    China's Three Gorges Dam (TGD) has received worldwide attention due to its profound impacts on the downstream hydraulic, morphological, and ecological systems. The TGD operation results in direct alternation of the discharge to the middle and lower Yangtze reach, manifested as regulated flow and reduced sediment load. TGD's flow regulation, typically described as water storage in fall while release in winter and spring, interferes with the natural seasonality of downstream Yangtze River levels which are essentially important to the inundation dynamics of surrounding lakes/wetlands in the Yangtze floodplain. Concurrent decrease of sediment load has caused chronic downstream channel erosion which lowers Yangtze level in relation to flow and further affects the sustainability of riparian lakes and the related ecosystems. By integrating satellite observations, in situ measurement, and hydrologic simulations, this study presents a systematic assessment of the TGD impacts on the inundation areas of six major freshwater lakes across the entire Yangtze basin downstream of the TGD, during the time period from TGD's initial impoundment in June 2003 to early 2012. Despite the small number, the six targeted lakes cover a total area of ~5,000 km2 accounting for ~25% of the freshwater lake area in China, and were identified as the only natural lakes that remain in open connection to the Yangtze River across the downstream floodplain. Using daily MODIS imagery from 2000 to 2012, we revealed a significant year-round decline in the aggregated inundation area of the studied lakes by an average of ~580 km2 or 17.7% from the pre-dam to post-dam period (i.e., before and after June, 2003). To diagnose TGD's contribution to such lake area decline, we followed a two-step procedure by first quantifying the TGD impacts on the seasonal level regime along the complete longitudinal range of the Yangtze River downstream from TGD to the estuary [Wang et al., 2013], and then estimating the

  1. Impact of the Three-Gorges Dam and water transfer project on Changjiang floods

    Science.gov (United States)

    Nakayama, Tadanobu; Shankman, David

    2013-01-01

    Increasing frequency of severe floods on the middle and lower Changjiang (Yangtze) River during the past few decades can be attributed to both abnormal monsoon rainfall and landscape changes that include extensive deforestation affecting river sedimentation, and shrinking lakes and levee construction that reduced the areas available for floodwater storage. The Three-Gorges Dam (TGD) and the South-to-North Water Transfer Project (SNWTP) will also affect frequency and intensity of severe floods in the Poyang Lake region of the middle Changjiang. Process-based National Integrated Catchment-based Eco-hydrology (NICE) model predicts that the TGD will increase flood risk during the early summer monsoon against the original justifications for building the dam, relating to complex river-lake-groundwater interactions. Several scenarios predict that morphological change will increase flood risk around the lake. This indicates the importance of managing both flood discharge and sediment deposition for the entire basin. Further, the authors assessed the impact of sand mining in the lake after its prohibition on the Changjiang, and clarified that alternative scenario of sand mining in lakes currently disconnected from the mainstream would reduce the flood risk to a greater extent than intensive dredging along junction channel. Because dry biomasses simulated by the model were linearly related to the Time-Integrated Normalized Difference Vegetation Index (TINDVI) estimated from satellite images, its decadal gradient during 1982-1999 showed a spatially heterogeneous distribution and generally decreasing trends beside the lakes, indicating that the increases in lake reclamation and the resultant decrease in rice productivity are closely related to the hydrologic changes. This integrated approach could help to minimize flood damage and promote better decisions addressing sustainable development.

  2. Coarse and fine sediment transportation patterns and causes downstream of the Three Gorges Dam

    Science.gov (United States)

    Li, Songzhe; Yang, Yunping; Zhang, Mingjin; Sun, Zhaohua; Zhu, Lingling; You, Xingying; Li, Kanyu

    2017-11-01

    Reservoir construction within a basin affects the process of water and sediment transport downstream of the dam. The Three Gorges Reservoir (TGR) affects the sediment transport downstream of the dam. The impoundment of the TGR reduced total downstream sediment. The sediment group d≤0.125 mm (fine particle) increased along the path, but the average was still below what existed before the reservoir impoundment. The sediments group d>0.125 mm (coarse particle) was recharged in the Yichang to Jianli reach, but showed a deposition trend downstream of Jianli. The coarse sediment in the Yichang to Jianli section in 2003 to 2007 was above the value before the TGR impoundment. However, the increase of both coarse and fine sediments in 2008 to 2014 was less than that in 2003 to 2007. The sediment retained in the dam is the major reason for the sediment reduction downstream. However, the retention in different river reaches is affected by riverbed coarsening, discharge, flow process, and conditions of lake functioning and recharging from the tributaries. The main conclusions derived from our study are as follows: 1) The riverbed in the Yichang to Shashi section was relatively coarse, thereby limiting the supply of fine and coarse sediments. The fine sediment supply was mainly controlled by TGR discharge, whereas the coarse sediment supply was controlled by the duration of high flow and its magnitude. 2) The supply of both coarse and fine sediments in the Shashi to Jianli section was controlled by the amount of total discharge. The sediment supply from the riverbed was higher in flood years than that in the dry years. The coarse sediment tended to deposit, and the deposition in the dry years was larger than that in the flood years. 3) The feeding of the fine sediment in the Luoshan to Hankou section was mainly from the riverbed. The supply in 2008 to 2014 was more than that in 2003 to 2007. Around 2010, the coarse sediments transited from depositing to scouring that was

  3. SWE-SPHysics Simulation of Dam Break Flows at South-Gate Gorges Reservoir

    Directory of Open Access Journals (Sweden)

    Shenglong Gu

    2017-05-01

    Full Text Available This paper applied a Smoothed Particle Hydrodynamics (SPH approach to solve Shallow Water Equations (SWEs to study practical dam-break flows. The computational program is based on the open source code SWE-SPHysics, where a Monotone Upstream-centered Scheme for Conservation Laws (MUSCL reconstruction method is used to improve the Riemann solution with Lax-Friedrichs flux. A virtual boundary particle method is applied to treat the solid boundary. The model is first tested on two benchmark collapses of water columns with the existence of downstream obstacle. Subsequently the model is applied to forecast a prototype dam-break flood, which might occur in South-Gate Gorges Reservoir area of Qinghai Province, China. It shows that the SWE-SPH modeling approach could provide a promising simulation tool for practical dam-break flows in engineering scale.

  4. Mosquito population dynamics during the construction of Three Gorges Dam in Yangtze River, China.

    Science.gov (United States)

    Guo, Yuhong; Lai, ShengJie; Zhang, Jing; Liu, Qiyong; Zhang, Huaiqing; Ren, Zhoupeng; Mao, Deqiang; Luo, Chao; He, Yuanyuan; Wu, Haixia; Li, Guichang; Ren, Dongsheng; Liu, Xiaobo; Chang, Zhaorui

    2018-06-01

    Mosquitoes are responsible for spreading many diseases and their populations are susceptible to environmental changes. The ecosystems in the Three Gorges Region were probably altered because of changes to the environment during the construction of the Three Gorges Dam (TGD), the world's largest hydroelectric dam by generating capacity. We selected three sites at which to monitor the mosquitoes from 1997 to 2009. We captured adult mosquitoes with battery-powered aspirators fortnightly between May and September of each year in dwellings and sheds. We identified the mosquito species, and examined changes in the species density during the TGD construction. We monitored changes in the species and density of mosquitoes in this area for 13 years during the TGD construction and collected information that could be used to support the control and prevention of mosquito-borne infections. We found that the mosquito species composition around the residential areas remained the same, and the density changed gradually during the TGD construction. The changes in the populations tended to be consistent over the years, and the densities were highest in July, and were between 3 and 5 times greater in the sheds than in the dwellings. The mosquito species and populations remained stable during the construction of the TGD. The mosquito density may have increased as the reservoir filled, and may have decreased during the clean-up work. Clean-up work may be an effective way to control mosquitoes and prevent mosquito-borne diseases. Copyright © 2018. Published by Elsevier B.V.

  5. Little impact of the Three Gorges Dam on recent decadal lake decline across China's Yangtze Plain

    Science.gov (United States)

    Wang, Jida; Sheng, Yongwei; Wada, Yoshihide

    2017-05-01

    The ubiquitous lakes across China's Yangtze Plain (YP) are indispensable freshwater resources sustaining ecosystems and socioeconomics for nearly half a billion people. Our recent survey revealed a widespread net decline in the total YP lake inundation area during 2000-2011 (a cumulative decrease of ˜10%), yet its mechanism remained contentious. Here we uncover the impacts of climate variability and anthropogenic activities including (i) Yangtze flow and sediment alterations by the Three Gorges Dam (TGD) and (ii) human water consumption in agricultural, industrial, and domestic sectors throughout the downstream Yangtze Basin. Results suggest that climate variability is the dominant driver of this decadal lake decline, whereas studied human activities, despite varying seasonal impacts that peak in fall, contribute marginal fraction (˜10-20% or less) to the interannual lake area decrease. Given that the TGD impacts on the total YP lake area and its seasonal variation are both under ˜5%, we also dismiss the speculation that the TGD might be responsible for evident downstream climate change by altering lake surface extent and thus open water evaporation. Nevertheless, anthropogenic impacts exhibited a strengthening trend during the past decade. Although the TGD has reached its full-capacity water regulation, the negative impacts of human water consumption and TGD-induced net channel erosion, which are already comparable to that of TGD's flow regulation, may continue to grow as crucial anthropogenic factors to future YP lake conservation.

  6. Effects of hydropower operations on recreational use and nonuse values at Glen Canyon and Flaming Gorge Dams

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, J.L.

    1995-03-01

    Increases in streamflows are generally positively related to the use values of angling and white-water boating, and constant flows tend to increase the use values more than fluctuating flows. In most instances, however, increases in streamflows beyond some threshold level cause the use values to decrease. Expenditures related to angling and white-water boating account for about $24 million of activity in the local economy around Glen Canyon Dam and $24.8 million in the local economy around flaming Gorge Dam. The range of operational scenarios being considered in the Western Area Power Administration`s Electric Power Marketing Environmental Impact Statement, when use rates are held constant, could change the combined use value of angling and white-water boating below Glen Canyon Dam, increasing it by as much as 50%, depending on prevailing hydrological conditions. Changes in the combined use value below Flaming Gorge Dam could range from a decrease of 9% to an increase of 26%. Nonuse values, such as existence and bequest values, could also make a significant contribution to the total value of each site included in this study; however, methodological and data limitations prevented estimating how each operational scenario could change nonuse values.

  7. Evaluation of the Three Gorges Dam project using multi-criteria analysis (MCA) based on a sustainable perspective

    Science.gov (United States)

    Han, Yue; Zheng, Wei; Guo, Junshan; Ma, Yihe; Ding, Junqi; Zhu, Lingkai; Che, Yongqiang; Zhang, Yanpeng

    2018-02-01

    Abstract . The Three Gorges dam of China is one of the largest and expensive hydropower projects of the world. The four main purposes of the project are flood control,energy production, improved navigation and fresh water supply. The dam project has been completed and running successfully with the potential benefits. However, this project is still a controversial issue among many environmentalists and socialists due to various impacts. This study focuses on the benefit and the impacts of the project, and also evaluates the performance of the project using multi-criteria analysis (MCA) approach from a sustainable perspective. Different sustainability criteria related with the dam project have been identified and used for the ranking and rating process. The final result of MCA comes with this scoring process and pairwise comparison, which evaluates the performance of the project considering different positive and negative aspects.

  8. Climate change impacts on Yangtze River discharge at the Three Gorges Dam

    Science.gov (United States)

    Birkinshaw, Steve J.; Guerreiro, Selma B.; Nicholson, Alex; Liang, Qiuhua; Quinn, Paul; Zhang, Lili; He, Bin; Yin, Junxian; Fowler, Hayley J.

    2017-04-01

    The Yangtze River basin is home to more than 400 million people and contributes to nearly half of China's food production. Therefore, planning for climate change impacts on water resource discharges is essential. We used a physically based distributed hydrological model, Shetran, to simulate discharge in the Yangtze River just below the Three Gorges Dam at Yichang (1 007 200 km2), obtaining an excellent match between simulated and measured daily discharge, with Nash-Sutcliffe efficiencies of 0.95 for the calibration period (1996-2000) and 0.92 for the validation period (2001-2005). We then used a simple monthly delta change approach for 78 climate model projections (35 different general circulation models - GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to examine the effect of climate change on river discharge for 2041-2070 for Representative Concentration Pathway 8.5. Projected changes to the basin's annual precipitation varied between -3.6 and +14.8 % but increases in temperature and consequently evapotranspiration (calculated using the Thornthwaite equation) were projected by all CMIP5 models, resulting in projected changes in the basin's annual discharge from -29.8 to +16.0 %. These large differences were mainly due to the predicted expansion of the summer monsoon north and west into the Yangtze Basin in some CMIP5 models, e.g. CanESM2, but not in others, e.g. CSIRO-Mk3-6-0. This was despite both models being able to simulate current climate well. Until projections of the strength and location of the monsoon under a future climate improve, large uncertainties in the direction and magnitude of future change in discharge for the Yangtze will remain.

  9. Potential effects of four Flaming Gorge Dam hydropower operational scenarios on riparian vegetation of the Green River, Utah and Colorado

    International Nuclear Information System (INIS)

    LaGory, K.E.; Van Lonkhuyzen, R.A.

    1995-06-01

    Four hydropower operational scenarios at Flaming Gorge Dam were evaluated to determine their potential effects on riparian vegetation along the Green River in Utah and Colorado. Data collected in June 1992 indicated that elevation above the river had the largest influence on plant distribution. A lower riparian zone occupied the area between the approximate elevations of 800 and 4,200-cfs flows--the area within the range of hydropower operational releases. The lower zone was dominated by wetland plants such as cattail, common spikerush, coyote willow, juncus, and carex. An upper riparian zone was above the elevation of historical maximum power plant releases from the dam (4,200 cfs), and it generally supported plants adapted to mesic, nonwetland conditions. Common species in the upper zone included box elder, rabbitbrush, grasses, golden aster, and scouring rush. Multispectral aerial videography of the Green River was collected in May and June 1992 to determine the relationship between flow and the areas of water and the riparian zone. From these relationships, it was estimated that the upper zone would decrease in extent by about 5% with year-round high fluctuation, seasonally adjusted high fluctuation, and seasonally adjusted moderate fluctuation, but it would increase by about 8% under seasonally adjusted steady flow. The lower zone would increase by about 13% for both year-round and seasonally adjusted high fluctuation scenarios but would decrease by about 40% and 74% for seasonally adjusted moderate fluctuation and steady flows, respectively. These changes are considered to be relatively minor and would leave pre-dam riparian vegetation unaffected. Occasional high releases above power plant capacity would be needed for long-term maintenance of this relict vegetation

  10. Potential effects of four Flaming Gorge Dam hydropower operational scenarios on riparian vegetation of the Green River, Utah and Colorado

    Energy Technology Data Exchange (ETDEWEB)

    LaGory, K.E.; Van Lonkhuyzen, R.A. [Argonne National Lab., IL (United States). Ecological Sciences Section

    1995-06-01

    Four hydropower operational scenarios at Flaming Gorge Dam were evaluated to determine their potential effects on riparian vegetation along the Green River in Utah and Colorado. Data collected in June 1992 indicated that elevation above the river had the largest influence on plant distribution. A lower riparian zone occupied the area between the approximate elevations of 800 and 4,200-cfs flows--the area within the range of hydropower operational releases. The lower zone was dominated by wetland plants such as cattail, common spikerush, coyote willow, juncus, and carex. An upper riparian zone was above the elevation of historical maximum power plant releases from the dam (4,200 cfs), and it generally supported plants adapted to mesic, nonwetland conditions. Common species in the upper zone included box elder, rabbitbrush, grasses, golden aster, and scouring rush. Multispectral aerial videography of the Green River was collected in May and June 1992 to determine the relationship between flow and the areas of water and the riparian zone. From these relationships, it was estimated that the upper zone would decrease in extent by about 5% with year-round high fluctuation, seasonally adjusted high fluctuation, and seasonally adjusted moderate fluctuation, but it would increase by about 8% under seasonally adjusted steady flow. The lower zone would increase by about 13% for both year-round and seasonally adjusted high fluctuation scenarios but would decrease by about 40% and 74% for seasonally adjusted moderate fluctuation and steady flows, respectively. These changes are considered to be relatively minor and would leave pre-dam riparian vegetation unaffected. Occasional high releases above power plant capacity would be needed for long-term maintenance of this relict vegetation.

  11. Three Gorges Dam alters the Changjiang (Yangtze) river water cycle in the dry seasons: Evidence from H-O isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Kai [School of Ocean and Earth Science, Tongji University, Shanghai, 200092 (China); State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092 (China); Yang, Shouye, E-mail: syyang@tongji.edu.cn [State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092 (China); Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061 (China); Lian, Ergang [School of Ocean and Earth Science, Tongji University, Shanghai, 200092 (China); State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092 (China); Li, Chao [State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092 (China); Yang, Chengfan; Wei, Hailun [School of Ocean and Earth Science, Tongji University, Shanghai, 200092 (China); State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092 (China)

    2016-08-15

    As the largest hydropower project in the world, the Three Gorges Dam (TGD) has attracted great concerns in terms of its impact on the Changjiang (Yangtze) River and coastal marine environments. In this study, we measured or collected the H-O isotopic data of river water, groundwater and precipitation in the mid-lower Changjiang catchment during the dry seasons of recent years. The aim was to investigate the changes of river water cycle in response to the impoundment of the TGD. Isotopic evidences suggested that the mid-lower Changjiang river water was ultimately derived from precipitation, but dominated by the mixing of different water masses with variable sources and isotopic signals as well. The isotopic parameter “deuterium excess” (d-excess) yielded large fluctuations along the mid-lower mainstream during the initial stage of the TGD impoundment, which was inherited from the upstream water with inhomogeneous isotopic signals. However, as the reservoir water level rising to the present stage, small variability of d-excess was observed along the mid-lower mainstream. This discrepancy could be explained that the TGD impoundment had significantly altered the water cycle downstream the dam, with the rising water level increasing the residence time and enhancing the mixing of reservoir water derived from upstream. This eventually resulted in the homogenization of reservoir water, and thus small fluctuations of d-excess downstream the dam after the quasi-normal stage (2008 to present). We infer that the retention effect of large reservoirs has greatly buffered the d-excess natural variability of water cycle in large river systems. Nevertheless, more research attention has to be paid to the damming effect on the water cycle in the river, estuarine and coastal areas, especially during the dry seasons. - Highlights: • Stable H-O isotopes indicate the Changjiang river water cycle in dry seasons. • The isotopic parameter “d-excess” reveals the origins of

  12. Unusual salinity conditions in the Yangtze estuary in 2006: impacts of an extreme drought or of the Three Gorges Dam?

    Science.gov (United States)

    Dai, Zhijun; Chu, Ao; Stive, Marcel; Zhang, Xiaoling; Yan, Hong

    2011-07-01

    During the extreme dry year of 2006, abnormal salinity conditions in the Changjiang Estuary of the Yangtze River occurred in partial coincidence with the second impoundment phase of the TGD (Three Gorges Dam). Analysis of discharge observations in the upper reaches of the estuary and of salinity observations in the estuary as a whole reveals that in 2006 salinity was over 100 mg/l during 275 days, over 250 mg/l during 75 days and over 400 mg/l during 48 days. It is well known that this is due to extreme low discharges from the upper catchment area into the estuary. Moreover, large amounts of water consumed along the lower reaches of the Yangtze River can also aggravate the low discharges that lead to stronger saltwater intrusion in the estuary. Of the 75 days that salinity was over 250 mg/l, the low discharge was decreased further by 10 to 20% due to water consumption. The additional impact of the impoundment phase of the TGD (lasting 37 days in autumn) was noticeable only during 7 days in 2006. During that period, the relative contributions of the TGD and the water consumption in the lower reaches of the Yangtze River amounted to 70 and 30%, respectively. It may be concluded that the impact of the second impoundment phase of the TGD on salinity intrusion in the estuary was modest, while the extreme drought of 2006 was the dominant cause.

  13. Statistical evaluation of the effects of fall and winter flows on the spring condition of rainbow and brown trout in the green river downstream of Flaming Gorge Dam.

    Energy Technology Data Exchange (ETDEWEB)

    Magnusson, A. K.; LaGory, K. E.; Hayse, J. W.; Environmental Science Division

    2009-01-09

    Flaming Gorge Dam, a hydroelectric facility operated by the Bureau of Reclamation (Reclamation), is located on the Green River in Daggett County, northeastern Utah. In recent years, single peak releases each day or steady flows have been the operational pattern during the winter period. A double-peak pattern (two flow peaks each day) was implemented during the winter of 2006-2007 by Reclamation. Because there is no recent history of double-peaking at Flaming Gorge Dam, the potential effects of double-peaking operations on the body condition of trout in the dam's tailwater are not known. A study plan was developed that identified research activities to evaluate potential effects from double-peaking operations during winter months. Along with other tasks, the study plan identified the need to conduct a statistical analysis of existing data on trout condition and macroinvertebrate abundance to evaluate potential effects of hydropower operations. This report presents the results of this analysis. We analyzed historical data to (1) describe temporal patterns and relationships among flows, benthic macroinvertebrate abundance, and condition of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) in the tailwaters of Flaming Gorge Dam and (2) to evaluate the degree to which flow characteristics (i.e., flow volumes and flow variability) and benthic macroinvertebrate abundance affect the condition of trout in this area. This information, together with further analyses of size-stratified trout data, may also serve as baseline data to which the effects of potential future double-peaking flows can be compared. The condition (length, weight and/or relative weight) of rainbow trout (Oncorhynchus mykiss) at two sites in the Green River downstream of Flaming Gorge Dam (Tailrace and Little Hole) and weight of brown trout (Salmo trutta) at the Little Hole site has been decreasing since 1990 while the abundance of brown trout has been increasing at the two sites. At

  14. Statistical evaluation of the effects of fall and winter flows on the spring condition of rainbow and brown trout in the Green River downstream of Flaming Gorge Dam

    International Nuclear Information System (INIS)

    Magnusson, A. K.; LaGory, K. E.; Hayse, J. W.

    2009-01-01

    Flaming Gorge Dam, a hydroelectric facility operated by the Bureau of Reclamation (Reclamation), is located on the Green River in Daggett County, northeastern Utah. In recent years, single peak releases each day or steady flows have been the operational pattern during the winter period. A double-peak pattern (two flow peaks each day) was implemented during the winter of 2006-2007 by Reclamation. Because there is no recent history of double-peaking at Flaming Gorge Dam, the potential effects of double-peaking operations on the body condition of trout in the dam's tailwater are not known. A study plan was developed that identified research activities to evaluate potential effects from double-peaking operations during winter months. Along with other tasks, the study plan identified the need to conduct a statistical analysis of existing data on trout condition and macroinvertebrate abundance to evaluate potential effects of hydropower operations. This report presents the results of this analysis. We analyzed historical data to (1) describe temporal patterns and relationships among flows, benthic macroinvertebrate abundance, and condition of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) in the tailwaters of Flaming Gorge Dam and (2) to evaluate the degree to which flow characteristics (i.e., flow volumes and flow variability) and benthic macroinvertebrate abundance affect the condition of trout in this area. This information, together with further analyses of size-stratified trout data, may also serve as baseline data to which the effects of potential future double-peaking flows can be compared. The condition (length, weight and/or relative weight) of rainbow trout (Oncorhynchus mykiss) at two sites in the Green River downstream of Flaming Gorge Dam (Tailrace and Little Hole) and weight of brown trout (Salmo trutta) at the Little Hole site has been decreasing since 1990 while the abundance of brown trout has been increasing at the two sites. At the

  15. Influence of Large Reservoir Operation on Water-Levels and Flows in Reaches below Dam: Case Study of the Three Gorges Reservoir.

    Science.gov (United States)

    Yang, Yunping; Zhang, Mingjin; Zhu, Lingling; Liu, Wanli; Han, Jianqiao; Yang, Yanhua

    2017-11-15

    The Three Gorges Project (TGP) is the world's largest water conservation project. The post-construction low-flow water level at the same discharge below the dam has declined, but there remains disagreement over whether the flood level has increased. Measured water levels and upstream and downstream flow data from 1955 to 2016 show that, post-construction: (1) the low-flow water level at the same discharge decreased, and the lowest water level increased due to dry-season reservoir discharge; (2) the decline of the low-flow water level below the dam was less than the undercutting value of the flow channel of the river; (3) the flood level at the same discharge below the dam was slightly elevated, although peak water levels decreased; (4) flood characteristics changed from a high discharge-high flood level to a medium discharge - high flood level; and (5) an expected decline in the flood level downstream was not observed. Channel erosion and the adjustment of rivers and lakes tend to reduce flood levels, while river bed coarsening, vegetation, and human activities downstream increase the flood level. Although the flood control benefits of the Three Gorges Dam (TGD) and the upstream reservoirs are obvious, increased elevation of the downstream flood level remains a concern.

  16. The effects of overwinter flowson the spring condition of rainbow and brown trout size classes in the Green River downstream of Flaming Gorge Dam, Utah.

    Energy Technology Data Exchange (ETDEWEB)

    Magnusson, A. K.; LaGory, K. E.; Hayse, J. W.; Environmental Science Division

    2010-06-25

    Flaming Gorge Dam, a hydroelectric facility operated by the Bureau of Reclamation (Reclamation), is located on the Green River in Daggett County, northeastern Utah. Until recently, and since the early 1990s, single daily peak releases or steady flows have been the operational pattern of the dam during the winter period. However, releases from Flaming Gorge Reservoir followed a double-peak pattern (two daily flow peaks) during the winters of 2006-2007 and 2008-2009. Because there is little recent long-term history of double-peaking at Flaming Gorge Dam, the potential effects of double-peaking operations on trout body condition in the dam's tailwater are not known. A study plan was developed that identified research activities to evaluate potential effects from winter double-peaking operations (Hayse et al. 2009). Along with other tasks, the study plan identified the need to conduct a statistical analysis of historical trout condition and macroinvertebrate abundance to evaluate the potential effects of hydropower operations. The results from analyses based on the combined size classes of trout (85-630 mm) were presented in Magnusson et al. (2008). The results of this earlier analysis suggested possible relationships between trout condition and flow, but concern that some of the relationships resulted from size-based effects (e.g., apparent changes in condition may have been related to concomitant changes in size distribution, because small trout may have responded differently to flow than large trout) prompted additional analysis of within-size class relationships. This report presents the results of analyses of three different size classes of trout (small: 200-299 mm, medium: 300-399 mm, and large: {ge}400 mm body length). We analyzed historical data to (1) describe temporal patterns and relationships among flows, benthic macroinvertebrate abundance, and condition of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) in the tailwaters of Flaming

  17. Climate-informed flood frequency analysis based on Bayesian theory and teleconnection for the Three Gorges Dam (TGD)

    Science.gov (United States)

    DONG, Q.; Zhang, X.; Lall, U.; Sang, Y. F.; Xie, P.

    2017-12-01

    With the current global climate changing and human activities intensifying, the uncertainties and danger of floods increased significantly. However, the current flood frequency analysis is still based on the stationary assumption. This assumption not only limits the benefits of the water conservancy projects, but also brings hazard because it ignores the risk of flooding under climate change. In this paper, we relax the stationary hypothesis in the flood frequency analysis model based on the teleconnection and use the intrinsic relation of flood elements to improve the annual flood frequency results by Bayesian inference approaches. Daily discharges of the the Three Gorges Dam(TGD) in 1953-2013 years are used as an example. Firstly, according to the linear correlation between the climate indices and the distribution parameters, the prior distributions of peak and volume are established with the selected large scale climate predictors. After that, by using the copula function and predictands, the conditional probability function of peak and volume is obtained. Then, the Bayesian theory links the prior distributions and conditional distributions and get the posterior distributions. We compare the difference under different prior distributions and find the optimal flood frequency distribution model. Finally, we discuss the impact of dynamic flood frequency analysis on the plan and management of hydraulic engineering. The results show that compared with the prior probability, the posterior probability considering the correlation of the flood elements is more accurate and the uncertainty is smaller. And the dynamic flood frequency model has a great impact on the management of the existing hydraulic engineering, which can improve the engineering operation benefit and reducing its flood risk, but it nearly didn't influence the plan of hydraulic engineering. The study of this paper is helpful to the dynamic flood risk management of TGD, and provide reference for the

  18. Sedimentation in the Three Gorges Dam and the future trend of Changjiang (Yangtze River sediment flux to the sea

    Directory of Open Access Journals (Sweden)

    Guogang Li

    2009-11-01

    Full Text Available The Three Gorges Dam (TGD on the upper Changjiang (Yangtze River, China, disrupts the continuity of Changjiang sediment delivery to downstream and coastal areas. In this study, which was based on 54 years of annual water and sediment data from the mainstream and major tributaries of Changjiang, sediment deposition induced by the TGD in 2003–2008 was quantified. Furthermore, we determined the theoretical trapping efficiency of the cascade reservoir upstream of the TGD. Its impact on Changjiang sediment flux in the coming decades is discussed. Results show that about 172 million tons (Mt of sediment was trapped annually by the TGD in 2003–2008, with an averaged trapping efficiency of 75%. Most of the total sediment deposition, as induced by the TGD (88%, accumulated within the region between the TGD site and Cuntan. However, significant siltation (12% of the total sediment deposition also occurred upstream of Cuntan as a consequence of the upstream extended backwater region of the TGD. Additionally, the Changjiang sediment flux entered a third downward step in 2001, prior to operation of the TGD. This mainly resulted from sediment reduction in the Jinshajiang tributary since the late 1990s. As the cascade reservoir is put into full operation, it could potentially trap 91% of the Jinshajiang sediment discharge and, therefore, the Jinshajiang sediment discharge would most likely further decrease to 14 Mt/yr in the coming decades. Consequently, the Changjiang sediment flux to the sea is expected to continuously decrease to below 90 Mt/yr in the near future, or only 18% of the amount observed in the 1950s. In the presence of low sediment discharge, profound impacts on the morphology of estuary, delta and coastal waters are expected.

  19. Potential effects of four Flaming Gorge Dam hydropower operational scenarios on the fishes of the Green River, Utah and Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Hlohowskyj, I.; Hayse, J.W.

    1995-09-01

    Aerial videography and modeling were used to evaluate the impacts of four hydropower operational scenarios at Flaming Gorge Dam, Utah, on trout and native fishes in the Green River, Utah and Colorado. The four operational scenarios studied were year-round high fluctuations, seasonally adjusted high fluctuations, seasonally adjusted moderate fluctuations, and seasonally adjusted steady flows. Impacts on trout were evaluated by examining differences among scenarios in the areas of inundated substrates that serve as spawning and feeding habitat. All scenarios would provide at least 23 acres per mile of habitat for spawning and food production; seasonally adjusted operations would provide additional areas during periods of sustained high release. Seasonally adjusted high fluctuations would increase inundated areas by 12 to 26% for a short period in winter and spring, but food production and reproduction would not be expected to increase. Seasonally adjusted moderate fluctuations and steady flows would produce similar increases in area, but the longer period of inundation could also result in increased food production and provide additional spawning sites for trout. Impacts on native fishes were assessed by examining daily changes in backwater nursery areas. Compared with year-round high fluctuations, the daily changes in backwater area would decrease by about 47, 89, and 100% under the seasonally adjusted high fluctuation, moderate fluctuation, and steady flow scenarios, respectively. Similarly, daily stage fluctuations during the nursery period would decrease by 72, 89, and 100% under the seasonally adjusted high fluctuation, moderate fluctuation, and steady flow scenarios, respectively. These reductions in daily fluctuations in backwater area and stage would improve conditions in nursery habitats and could in turn improve recruitment and overwinter survival. Introduced fish species could also benefit from the seasonally adjusted operational scenarios.

  20. Estimating Remineralized Phosphate and Its Remineralization Rate in the Northern East China Sea During Summer 1997: A Snapshot Study Before Three-Gorges Dam Construction

    Directory of Open Access Journals (Sweden)

    Hyun-Cheol Kim

    2016-01-01

    Full Text Available The northern East China Sea (a.k.a., “The South Sea” is a dynamic zone that exerts a variety of effects on the marine ecosystem due to Three-Gorges Dam construction. As the northern East China Sea region is vulnerable to climate forcing and anthropogenic impacts, it is important to investigate how the remineralization rate in the northern East China Sea has changed in response to such external forcing. We used an historical hydrographic dataset from August 1997 to obtain a baseline for future comparison. We estimate the amount of remineralized phosphate by decomposing the physical mixing and biogeochemical process effect using water column measurements (temperature, salinity, and phosphate. The estimated remineralized phosphate column inventory ranged from 0.8 to 42.4 mmol P m-2 (mean value of 15.2 ± 12.0 mmol P m-2. Our results suggest that the Tsushima Warm Current was a strong contributor to primary production during the summer of 1997 in the study area. The estimated summer (June - August remineralization rate in the region before Three-Gorges Dam construction was 18 ± 14 mmol C m-2 d-1.

  1. Four decades of wetland changes of the largest freshwater lake in China in response to the Three Gorges Dam

    Science.gov (United States)

    Feng, L.

    2017-12-01

    Wetlands provide important ecosystem functions for water alteration and conservation of bio-diversity, yet they are vulnerable to both human activities and climate changes. Using four decades of Landsat, MODIS and HJ-1A/1B satellites observations, the long-term wetland changes in Poyang Lake, the largest freshwater lake of China, have been investigated in this study. A Support Vector Machines (SVM) method was firstly developed to obtain wetland classification maps of major cover types between 1973 and 2013 using Landsat and HJ-1A/1B images. A statistically significant increasing trend of the wetland vegetation (15.9 km2 year-1) was found, where the vegetation tended to spread into the lake center in the past four decades. While the transitions from mudflat to vegetation and vice versa were comparable before 2001, vegetation area increased by 620.8 km2 (16.6% of the lake area) between 2001 and 2013. Then, a phenology-based decision tree approach was developed to classify wetland vegetation at community level, with the help of the spatial and spectral information of frequent MODIS observations between 2000 and 2014. MODIS wetland maps confirmed the replacement of water and mudflat by expanded vegetated areas since the impoundment of the Three Gorges Dam (TGD), where both the total coverage of vegetation and the area of each community showed significantly increasing trends. More importantly, results indicated that the vegetation community transitions occurred mainly from hydrophilic cover types to those adapted to dryer conditions. Hydrological analysis revealed that 1) the relationships between the water levels and vegetation coverage showed two regimes for the pre-TGD period (before 2003) and post-TGD period (after 2003); and 2) despite the significant changes in wetland cover types, the most preferable water depth for each cover type remained stable before and after the TGD. The findings here unambiguously led to the conclusion that the landscape changes seen in

  2. Relocation Stress, Coping, and Sense of Control among Resettlers Resulting from China's Three Gorges Dam Project

    Science.gov (United States)

    Xi, Juan; Hwang, Sean-Shong

    2011-01-01

    The involuntary relocation of people for development purposes has become prevalent across the world in recent decades. Depression is one of the documented negative outcomes of involuntary relocation among resettlers. Viewing the affected population simply as passive victims, past studies have largely ignored the coping strategies employed by…

  3. Synchronous response of sedimentary organic carbon accumulation on the inner shelf of the East China Sea to the water impoundment of Three Gorges and Gezhouba Dams

    Science.gov (United States)

    Lin, Jia; Zhu, Qing; Hong, Yuehui; Yuan, Lirong; Liu, Jinzhong; Xu, Xiaoming; Wang, Jianghai

    2018-01-01

    Coastal seas, located between continents and the open ocean, are an important active carbon pool. The sedimentary total organic carbon (TOC) in these areas is a mixture of terrestrial and marine sources, and can be a powerful proxy for tracing natural processes and human activities. In this study, one fine-grained sediment core (DH5-1) from the inner shelf of the East China Sea was systematically analyzed for TOC and black carbon (BC) contents and TOC stable carbon isotope ratios (δ13C). By combining these data with 210Pb dating, an improved carbon correction model and a two end-member mixing model, we reconstructed century-scale high-resolution sequences of corrected TOC, terrestrial TOC and marine TOC contents and identified two carbon depletion events in the DH5-1 record. The two events, shown as two minima in the TOC profiles, correspond temporally to 1985-1987 AD and 2003-2006 AD, which exactly matches the water impoundment of the Gezhouba Dam and Three Gorges Dam, respectively. In addition, the variations in TOC contents and δ13C values before, during or after the minima demonstrate a relationship between the depletion events and water impoundment of the dams on the Changjiang River. The TOC reductions may represent synchronous responses of sedimentary TOC and resultant ecological effects on the inner shelf of the East China Sea to the water impoundment of the dams. These new TOC records reflect the interaction between natural and anthropogenic processes and, accordingly, provide a deep insight and important references for assessing marine ecological effects resulting from water impoundment of largescale dams.

  4. Modeling the erosion risk potential induced by terraces and their condition in a highly dynamic watershed close to the Three-Gorges-Dam

    Science.gov (United States)

    Schönbrodt, S.; Behrens, T.; Imbery, S.; Scholten, T.

    2010-03-01

    Globally, the Three-Gorges Ecosystem is currently one of the most anthropogenic influenced regions. Due to the Three-Gorges Dam large areas in the upper catchment of the Yangtze and its major tributaries become inundated. Consequently, high land-use dynamic with resettlements, construction of infrastructure, and new land reclamation for smallholder agriculture and cash crops characterize this area. Therefore, ecological impacts are expected in an unforeseeable dimension. Soil loss is one of the major threats and its control an enormous challenge. Even existing erosion control measures like dry-stone walling bench terraces have to be adapted to this new situation in order to keep their effectiveness. In the highly dynamic watershed of the Xiangxi, a first class tributary to the Yangtze, this study aims to assess and predict the spatial and temporal varying dam-caused soil erosion risk potential. Using a multi-level and multi-scale approach this study seeks to develop an integrative data-based methodology for soil erosion assessment by means of GIS-based erosion modeling using relevant digital terrain data, field investigations and remote sensing. The different scales considered cover the Xiangxi watershed (3.100 km²), the highly dynamic backwater area (500 km²), and two micro-scale study sites (3 km² and 88 km²) subject to flooding and high land-use dynamic. Central features of the Xiangxi watershed are steep slopes artificially fractured by terraces. A preliminary erosion survey has shown a strong connection of the frequency and intensity of erosion and the quality of terrace-maintenance. Terraces with wall disorders and technically poor constructed design show higher soil loss and runoff than well-maintained terraces. Their condition is regarded as a driving erosion factor. Therefore, a conceptual Terrace-Condition-Erosion model (TerraCE) was developed in order to assess to what extent soil erosion depends on the quality of terraces. Central aspects are the

  5. Effects of Flaming Gorge Dam hydropower operations on sediment transport in the Browns Park reach of the Green River, Utah and Colorado

    International Nuclear Information System (INIS)

    Williams, G.P.; Tomasko, D.; Cho, H.E.; Yin, S.C.L.

    1995-05-01

    Three methods for comparing sediment transport were applied to four proposed hydropower operational scenarios under study for Flaming Gorge Dam on the Green River in Utah. These methods were effective discharge, equilibrium potential, and cumulative sediment load with flow exceedance plots. Sediment loads transported by the Green River in the Browns Park reach were calculated with the Engelund-Hansen equation for three historical water years and four hydropower operational scenarios. A model based on the Engelund-Hansen equation was developed using site-specific information and validated by comparing predictions for a moderate water year with measured historical values. The three methods were used to assess the impacts of hydropower operational scenarios on sediment resources. The cumulative sediment load method provided the most useful information for impact evaluation. Effective discharge was not a useful tool because of the limited number of discrete flows associated with synthetic hydrographs for the hydropower operational scenarios. The equilibrium potential method was relatively insensitive to the variations in operating conditions, rendering it comparatively ineffective for impact evaluation

  6. Nitrogen transport, transformation, and retention in the Three Gorges Reservoir : A mass balance approach

    NARCIS (Netherlands)

    Ran, Xiangbin; Bouwman, Lex; Yu, Zhigang; Beusen, Arthur; Chen, Hongtao; Yao, Qingzhen

    2017-01-01

    Dam construction in river systems affects the biogeochemistry of nitrogen (N), yet most studies on N cycling in reservoirs do not consider the transformations and retention of the different N species. This study addresses the N inputs, transport, transformations, and retention in the Three Gorges

  7. Quantifying the Effects of Near-Bed Concentration on the Sediment Flux after the Operation of the Three Gorges Dam, Yangtze River

    Directory of Open Access Journals (Sweden)

    Li He

    2017-12-01

    Full Text Available The regime of sediment transport in the Jingjiang Reach has significantly changed from quasi-equilibrium to sub-saturation since the impoundment of the Three Gorges Dam (TGD, and vertical profiles of suspended sediment concentration (SSC have changed accordingly. Vertical profiles of SSC data measured at three hydrological stations in the Jingjiang Reach (Zhicheng, Shaishi, and Jianli, before and after the impoundment of TGD, were collected and analyzed. Analytic results indicate a remarkably large concentration in the near-bed zone (within 10% of water depth from the river-bed in a sub-saturated channel. The maximum measured concentration was up to 15 times the vertical average concentration, while the ratio in quasi-equilibrium channel was less than four times that. Concentrations normalized with reference concentration at the same height, and may decrease with increasing values of suspension index (settling velocity over shear velocity. In addition, concentration near the water surface may be larger than concentration in the near-bed region when the suspension index is smaller than 0.01. Sediment flux transported in the near-bed zone may be up to 35% of the total sediment flux in unsaturated flows. The relationship between deviations of estimating sediment flux when ignoring the near-bed concentration and discharge in flood season and non-flood season are different in unsaturated and quasi-equilibrium channels. Analysis indicates that, in the quasi-equilibrium channel, more attention should be paid to near-bed concentration during non-flood season, the same as measurements during flood season with larger discharge.

  8. The socio-political effects of forced migrations linked to major hydraulic projects in China. The example of the Three Gorges dam - CERI Studies No. 103

    International Nuclear Information System (INIS)

    Padovani, Florence

    2004-04-01

    The study of the population movements caused by the major Chinese hydraulic projects reveals the true extent of the change which has come about in relations between the State and society in China. The construction of the Three Gorges dam - which led to considerable controversy both within China and beyond - is a prime case in point. As well as its social consequences, this infrastructure project has ramifications in the political, economic and legal domains, notably because of the forced migrations which it has entailed. The manner in which this question has been managed - both by central government, which planned the project, and by the provincial governments, which had to manage time constraints and financial and human resources at first hand - illustrates the extent to which the country has moved away from the authoritarian approach which had currency under the rule of Chairman Mao. The study of the project provides insights into the manner in which the authorities on the ground actually applied the directives received from the Centre, and into the difficulty encountered by the rulers in Beijing in ensuring that their centralised vision of the new China holds sway. The way in which the sensitive issue of forced migrations has been managed highlights what is at stake in the disputes between the various players, i.e. officials in the many ministries concerned, local and provincial authorities, displaced populations and host populations. The specific modes of justification employed by each group provide pointers towards an understanding of the complexity of China's new 'civil society'. (author)

  9. Dams

    Data.gov (United States)

    Vermont Center for Geographic Information — This dataset �is generated from from the Vermont Dam Inventory (VDI). The VDI is managed by the VT DEC's Dam Safety and Hydrology Section and contains information...

  10. Analysis of Factors Affecting Stress Solution at Concrete Gravity Dam Heel

    Science.gov (United States)

    Hung, Vu Hoang; Quoc Cong, Trinh; Tongchun, Li

    2010-05-01

    Along with Vietnam's development, various hydraulic constructions including concrete gravity dams have been being built. In some of these dams, the fractures occurred at the heel of the dams are even in small and media dams. There are various reasons cause the factures at dam heel but the main reason is the stress states at dam heel are not determined correctly while designing dam. In this paper, several factors affecting stress solution at concrete gravity dam heel such as element mesh size, crack joints of upstream foundation, execution process are investigated by using finite element model of Banve concrete gravity dam. This work is very significant when the more high concrete gravity dams will be constructed in Vietnam year after year.

  11. Itaipu, Brazil, against the 'Drieklovendam' (Three Gorges Dam), China. Brazilian hydroelectric power giant has the largest capacity; Itaipu contra de Drieklovendam. Braziliaanse waterkrachtreus levert grootste vermogen

    Energy Technology Data Exchange (ETDEWEB)

    Ypma, T.

    2008-04-15

    China and Brazil are competing over who has the largest hydropower plant. In 2009, 26 generators at the Three Gorges Dam in China will have to supply 85 billion kilowatt-hours with n installed capacity of approximately 18,200 MW. In Brazil, the Itaipu plant supplied 90 billion kilowatt-hours with 14,000MW installed capacity and 20 generators. The accompanying Chinese reservoir has a dam with a length of 2300 meters and height of 185 meters; the Brazilian Itaipu dam has a length of 7235 meters. [mk]. [Dutch] China en Brazilie wedijveren wie de grootste waterkrachtcentrale heeft. In 2009 moeten 26 generatoren bij de Drieklovendam in China jaarlijks 85 miljard kilowattuur leveren, met een geinstalleerd vermogen van 18.200 MW. In Brazilie leverde de Itaipu-centrale in 2007 met 20 generatoren 90 miljard kilowattuur, met 14.000 MW geinstalleerd vermogen. Het bijbehorende Chinese stuwmeer heeft een dam van 2300 meter lang en 185 meter hoog, de Braziliaanse Itaipu-dam heeft een lengte van 7235 meter.

  12. Types of integration and depressive symptoms: A latent class analysis on the resettled population for the Three Gorges dam project, China.

    Science.gov (United States)

    Xi, Juan

    2016-05-01

    Focusing on China's Three Gorges Project (TGP)-Induced Resettlement, the largest scale resettlement induced by a single development project, this study aims to investigate different types of integration patterns among the TGP re-settlers and how modes of integration associate with depressive symptoms. Using Latent Class Analysis, we analyzed survey data on 407 TGP re-settlers. We detected three integration patterns among these re-settlers: the fully integrated (68%), the culturally and economically integrated (21%) and the unintegrated (11%). We found that different integration types were linked to different levels of depressive symptoms. Unless fully integrated and experienced a warm feeling toward new community, re-settlers were vulnerable to elevated depressive symptoms. Our findings that culturally and economically integrated re-settlers had similar levels of depressive symptoms as the unintegrated re-settlers highlighted the importance of subjective dimension of integration and resettlement. We also found that rural re-settlers and those who move with the whole village were more likely to fall into the unintegrated category. Policy implications were discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Monitoring the ongoing deformation and seasonal behaviour affecting Mosul Dam through space-borne SAR data

    Science.gov (United States)

    Tessari, G.; Riccardi, P.; Pasquali, P.

    2017-12-01

    fields obtained from SAR data are evaluated to assess the temporal evolution of the strains affecting the structure. Obtained results represent the preliminary stage of a multidisciplinary project, finalized to assess possible damages affecting a dam through remote sensing and civil engineering surveys.

  14. Ethanol consumption by Wistar rat dams affects selenium bioavailability and antioxidant balance in their progeny.

    Science.gov (United States)

    Ojeda, María Luisa; Vázquez, Beatriz; Nogales, Fátima; Murillo, María Luisa; Carreras, Olimpia

    2009-08-01

    Ethanol consumption affects maternal nutrition, the mothers' antioxidant balance and the future health of their progeny. Selenium (Se) is a trace element cofactor of the enzyme glutathione peroxidase (GPx). We will study the effect of ethanol on Se bioavailability in dams and in their progeny. We have used three experimental groups of dams: control, chronic ethanol and pair-fed; and three groups of pups. Se levels were measured by graphite-furnace atomic absorption spectrometry. Serum and hepatic GPx activity was determined by spectrometry. We have concluded that ethanol decreased Se retention in dams, affecting their tissue Se deposits and those of their offspring, while also compromising their progeny's weight and oxidation balance. These effects of ethanol are caused by a reduction in Se intake and a direct alcohol-generated oxidation action.

  15. Ethanol Consumption by Wistar Rat Dams Affects Selenium Bioavailability and Antioxidant Balance in Their Progeny

    Directory of Open Access Journals (Sweden)

    Olimpia Carreras

    2009-07-01

    Full Text Available Ethanol consumption affects maternal nutrition, the mothers’ antioxidant balance and the future health of their progeny. Selenium (Se is a trace element cofactor of the enzyme glutathione peroxidase (GPx. We will study the effect of ethanol on Se bioavailability in dams and in their progeny. We have used three experimental groups of dams: control, chronic ethanol and pair-fed; and three groups of pups. Se levels were measured by graphite-furnace atomic absorption spectrometry. Serum and hepatic GPx activity was determined by spectrometry. We have concluded that ethanol decreased Se retention in dams, affecting their tissue Se deposits and those of their offspring, while also compromising their progeny’s weight and oxidation balance. These effects of ethanol are caused by a reduction in Se intake and a direct alcohol-generated oxidation action.

  16. Dams and transnational advocacy: Political opportunities in transnational collective action

    Science.gov (United States)

    Fu, Teng

    Possible arguments to explain the gradual decline in big dam development and its site transferring from developed to developing countries include technical, economic, and political factors. This study focuses on the political argument---the rise of transnational anti-dam advocacy and its impact on state policy-making. Under what conditions does transnational anti-dam advocacy matter? Under what conditions does transnational advocacy change state dam policies (delay, scale down, or cancel)? It examines the role of transnational anti-dam actors in big dam building in a comparative context in Asia. Applying the social movement theory of political opportunity structure (POS) and using the qualitative case-study method, the study provides both within-case and cross-case analyses. Within-case analysis is utilized to explain the changing dynamics of big dam building in China (Three Gorges Dam and proposed Nu/Salween River dam projects), and to a lesser extent, Sardar Sarovar Project in India and Nam Theun 2 Dam in Laos. Different domestic and international POS (DPOS and IPOS) impact the strategies and outcomes of anti-dam advocacies in these countries. The degree of openness of the POS directly affects the capacity of transnational efforts in influencing state dam policies. The degree of openness or closure is measured by specific laws, institutions, discourse, or elite allies (or the absence of these) for the participation of non-state actors on big dam issues at a particular moment. This degree of openness is relative, varying over time, across countries and regions. This study finds that the impact of transnational anti-dam activism is most effective when both DPOS and IPOS are relatively open. Transnational anti-dam advocacy is least effective in influencing state dam policies when both DPOS and IPOS are relatively closed. Under a relatively open DPOS and closed IPOS, transnational anti-dam advocacy is more likely to successfully change state dam policies and even

  17. Performance Survey of Inflatable Dams in Ice-Affected Waters. Ice Engineering. Number 30, October 2001

    National Research Council Canada - National Science Library

    2001-01-01

    .... Inflatable dam applications include headgates for irrigation, water supply and hydropower, flashboard replacement, raising the crest of an existing dam or reservoir spillway, tidal barriers, sewage...

  18. The Three Gorges Project: How sustainable?

    Science.gov (United States)

    Kepa Brian Morgan, Te Kipa; Sardelic, Daniel N.; Waretini, Amaria F.

    2012-08-01

    SummaryIn 1984 the Government of China approved the decision to construct the Three Gorges Dam Project, the largest project since the Great Wall. The project had many barriers to overcome, and the decision was made at a time when sustainability was a relatively unknown concept. The decision to construct the Three Gorges Project remains contentious today, especially since Deputy Director of the Three Gorges Project Construction Committee, Wang Xiaofeng, stated that "We absolutely cannot relax our guard against ecological and environmental security problems sparked by the Three Gorges Project" (Bristow, 2007; McCabe, 2007). The question therefore was posed: how sustainable is the Three Gorges Project? Conventional approaches to sustainability assessment tend to use monetary based assessment aligned to triple bottom line thinking. That is, projects are evaluated as trade-offs between economic, environmental and social costs and benefits. The question of sustainability is considered using such a traditional Cost-Benefit Analysis approach, as undertaken in 1988 by a CIPM-Yangtze Joint Venture, and the Mauri Model Decision Making Framework (MMDMF). The Mauri Model differs from other approaches in that sustainability performance indicators are considered independently from any particular stakeholder bias. Bias is then introduced subsequently as a sensitivity analysis on the raw results obtained. The MMDMF is unique in that it is based on the Māori concept of Mauri, the binding force between the physical and the spiritual attributes of something, or the capacity to support life in the air, soil, and water. This concept of Mauri is analogous to the Chinese concept of Qi, and there are many analogous concepts in other cultures. It is the universal relevance of Mauri that allows its use to assess sustainability. This research identified that the MMDMF was a strong complement to Cost-Benefit Analysis, which is not designed as a sustainability assessment tool in itself. The

  19. Enhancement and management of eel fisheries affected by hydroelectric dams in New Zealand

    Science.gov (United States)

    Boubee, J.; Chisnall, B.; Watene, E.; Williams, E.; Roper, D.; Haro, A.

    2003-01-01

    Two freshwater anguillid eel species, Anguilla australis and A. dieffenbachia, form the basis of important traditional, recreational, and commercial fisheries in New Zealand. These fisheries have been affected by the damming of many of the major waterways for hydroelectric generation. To create fisheries in reservoirs that would be otherwise inaccessible, elvers have been transferred from the base of dams into habitats upstream. Operations in three catchments: the Patea River (Lake Rotorangi), Waikato River (eight reservoirs notably the two lowermost, lakes Karapiro and Arapuni), and Rangitaiki River (lakes Matahina and Aniwhenua) are discussed. In all reservoirs, the transfers have successfully established fishable populations within six years of the first transfers and, in Lake Arapuni eels have reached the marketable size of 220 g in less than four years. In comparison, it typically takes from 13 to 17 years before eel populations are fishable in the lower Waikato River where direct access to the sea is available. Telemetry and monitoring at the screens and tailraces of several power stations have been used to determine migration timing, triggers, and pathways of mature eels. Successful downstream transfer of mature migrating adults has been achieved by spillway opening and netting in headraces during rain events in autumn, but means of preventing eels from impinging and entraining at the intakes are still required. An integrated, catchment-wide management system will be required to ensure sustainability of the fisheries. ?? Copyright by the American Fisheries Society 2003.

  20. Factors affecting route selection and survival of steelhead kelts at Snake River dams in 2012 and 2013

    Energy Technology Data Exchange (ETDEWEB)

    Harnish, Ryan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Colotelo, Alison H. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Xinya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fu, Tao [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ham, Kenneth D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deng, Zhiqun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Green, Ethan D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-03-31

    In 2012 and 2013, Pacific Northwest National Laboratory (PNNL) conducted a study that summarized the passage route proportions and route-specific survival rates of steelhead kelts that passed through Federal Columbia River Power System (FCRPS) dams. To accomplish this, a total of 811 steelhead kelts were tagged with Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters. Acoustic receivers, both autonomous and cabled, were deployed throughout the FCRPS to monitor the downstream movements of tagged kelts. Kelts were also tagged with passive integrated transponder tags to monitor passage through juvenile bypass systems (JBS) and detect returning fish. The current study evaluated data collected in 2012 and 2013 to identify environmental, temporal, operational, individual, and behavioral variables that were related to forebay residence time, route of passage, and survival of steelhead kelts at FCRPS dams on the Snake River. Multiple approaches, including 3-D tracking, bivariate and multivariable regression modeling, and decision tree analyses were used to identify the environmental, temporal, operational, individual, and behavioral variables that had the greatest effect on forebay residence time, route of passage, and route-specific and overall dam passage survival probabilities for tagged kelts at Lower Granite (LGR), Little Goose (LGS), and Lower Monumental (LMN) dams. In general, kelt behavior and discharge appeared to work independently to affect forebay residence times. Kelt behavior, primarily approach location, migration depth, and “searching” activities in the forebay, was found to have the greatest influence on their route of passage. The condition of kelts was the single most important factor affecting their survival. The information gathered in this study may be used by dam operators and fisheries managers to identify potential management actions to improve in-river survival of kelts or collection methods for kelt reconditioning programs to aid

  1. Factors Affecting Route Selection and Survival of Steelhead Kelts at Snake River Dams in 2012 and 2013

    Energy Technology Data Exchange (ETDEWEB)

    Harnish, Ryan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Colotelo, Alison HA [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Xinya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ham, Kenneth D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deng, Zhiqun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-12-01

    turbines. The side of the river in which kelts approached the dam and dam operations also affected route of passage. Dam operations and the size and condition of kelts were found to have the greatest effect on route-specific survival probabilities for fish that passed via the spillway at LGS. That is, longer kelts and those in fair condition had a lower probability of survival for fish that passed via the spillway weir. The survival of spillway weir- and deep-spill passed kelts was positively correlated with the percent of the total discharge that passed through turbine unit 4. Too few kelts passed through the traditional spill, JBS, and turbine units to evaluate survival through these routes. The information gathered in this study describes Snake River steelhead kelt passage behavior, rates, and distributions through the FCRPS as well as provide information to biologists and engineers about the dam operations and abiotic conditions that are related to passage and survival of steelhead kelts.

  2. The Short-Term Impact of Involuntary Migration in China's Three Gorges: A Prospective Study

    Science.gov (United States)

    Hwang, Sean-Shong; Cao, Yue; Xi, Juan

    2011-01-01

    The aim of this study is to measure the short-term impact of involuntary migration resulting from China's Three Gorges Dam project on the 1.3 million persons being displaced. We focus on the social, economic, and mental and physical health impact using three sets of indicators. Using a prospective research design, we gathered information about…

  3. The Multiterritorialization of the Conflict with Hidroelectrical Plants: Resettlements as Empowerment Points of the Movement of People Affected by Dams

    Directory of Open Access Journals (Sweden)

    Humberto José Da Rocha

    2016-09-01

    Full Text Available The Brazilian electrical sector, with a predominant hydric matrix, generates social and environmental impacts, among which stands out the compulsory displacement of local populations. The de-territorialization and re-territorialization caused by hydroelectric plants produce a process characterized by “multiterritorialization” of conflict. This paper discusses this conflict, which involves consortiums of construction companies and the Movement of People Affected by Dams (MAB, as a contesting movement. The objective is to analyze to what extent resettlements produced by the construction of hydroelectric dams and organized by MAB potentiate actions against future constructions. Combining qualitative research with quantitative data, we present the case of the Uruguay basin, in order to demonstrate that, although they represent empowerment points, the potential of resettlements must be relativized from the standpoint of a broader social process.

  4. Gravity inversion of deep-crust and mantle interfaces in the Three Gorges area

    Directory of Open Access Journals (Sweden)

    Wang Jian

    2012-11-01

    Full Text Available To better understand the heterogeneity of deep-crust and mantle interfaces in the region of the Three Gorges, China, we used the Parker-Oldenburg iterative inversion method to invert existing Bouguer gravity data from the Three Gorges area (1 : 500000, a new gravity map of the Three Gorges Dam (1 : 200000, and the results of deep seismic soundings. The inversion results show a Moho depth of 42 km between Badong and Zigui and the depth of the B2 lower-crustal interface beneath the Jianghan Plain and surrounding areas at 21–25 km. The morphology of crustal interfaces and the surface geology present an overpass structure. The mid-crust beneath the Three Gorges Dam is approximately 9 km thick, which is the thinnest in the Three Gorges area and may be related to the shallow low-density body near the Huangling anticline. The upper crust is seismogenic, and there is a close relationship between seismicity and the deep-crust and mantle interfaces. For example, the M5. 1 Zigui earthquake occurred where the gradients of the Moho and the B2 interface are the steepest, showing that deep structure has a very important effect on regional seismicity.

  5. Dam removal: Listening in

    Science.gov (United States)

    Foley, M. M.; Bellmore, J. R.; O'Connor, J. E.; Duda, J. J.; East, A. E.; Grant, G. E.; Anderson, C. W.; Bountry, J. A.; Collins, M. J.; Connolly, P. J.; Craig, L. S.; Evans, J. E.; Greene, S. L.; Magilligan, F. J.; Magirl, C. S.; Major, J. J.; Pess, G. R.; Randle, T. J.; Shafroth, P. B.; Torgersen, C. E.; Tullos, D.; Wilcox, A. C.

    2017-07-01

    Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus far, some general conclusions have emerged: (1) physical responses are typically fast, with the rate of sediment erosion largely dependent on sediment characteristics and dam-removal strategy; (2) ecological responses to dam removal differ among the affected upstream, downstream, and reservoir reaches; (3) dam removal tends to quickly reestablish connectivity, restoring the movement of material and organisms between upstream and downstream river reaches; (4) geographic context, river history, and land use significantly influence river restoration trajectories and recovery potential because they control broader physical and ecological processes and conditions; and (5) quantitative modeling capability is improving, particularly for physical and broad-scale ecological effects, and gives managers information needed to understand and predict long-term effects of dam removal on riverine ecosystems. Although these studies collectively enhance our understanding of how riverine ecosystems respond to dam removal, knowledge gaps remain because most studies have been short (< 5 years) and do not adequately represent the diversity of dam types, watershed conditions, and dam-removal methods in the U.S.

  6. Dam removal: Listening in

    Science.gov (United States)

    Foley, Melissa M.; Bellmore, James; O'Connor, James E.; Duda, Jeff; East, Amy E.; Grant, Gordon G.; Anderson, Chauncey; Bountry, Jennifer A.; Collins, Mathias J.; Connolly, Patrick J.; Craig, Laura S.; Evans, James E.; Greene, Samantha; Magilligan, Francis J.; Magirl, Christopher S.; Major, Jon J.; Pess, George R.; Randle, Timothy J.; Shafroth, Patrick B.; Torgersen, Christian E.; Tullos, Desiree D.; Wilcox, Andrew C.

    2017-01-01

    Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus far, some general conclusions have emerged: (1) physical responses are typically fast, with the rate of sediment erosion largely dependent on sediment characteristics and dam-removal strategy; (2) ecological responses to dam removal differ among the affected upstream, downstream, and reservoir reaches; (3) dam removal tends to quickly reestablish connectivity, restoring the movement of material and organisms between upstream and downstream river reaches; (4) geographic context, river history, and land use significantly influence river restoration trajectories and recovery potential because they control broader physical and ecological processes and conditions; and (5) quantitative modeling capability is improving, particularly for physical and broad-scale ecological effects, and gives managers information needed to understand and predict long-term effects of dam removal on riverine ecosystems. Although these studies collectively enhance our understanding of how riverine ecosystems respond to dam removal, knowledge gaps remain because most studies have been short (dam types, watershed conditions, and dam-removal methods in the U.S.

  7. Maternal high-protein or high-prebiotic-fiber diets affect maternal milk composition and gut microbiota in rat dams and their offspring.

    Science.gov (United States)

    Hallam, Megan C; Barile, Daniela; Meyrand, Mickael; German, J Bruce; Reimer, Raylene A

    2014-11-01

    Maternal gut microbiota and milk composition could modify offspring microbiota and therefore disease susceptibility. The effect of maternal high-protein (HP) or prebiotic diets on maternal milk composition and gut microbiota in rat dams and offspring was examined. Wistar rat dams were fed a control, HP (40% wt/wt), or high-prebiotic-fiber (21.6% wt/wt) (HF) diet throughout pregnancy and lactation. Pups were challenged with a high-fat/sucrose diet from 14.5 to 22.5 weeks of age. Dam milk was analyzed for fat, protein, and oligosaccharides (OS). Fecal microbiota was analyzed in dams at parturition and 2 weeks post-partum and in offspring at 5 and 22 weeks along with cecal digesta at termination. Maternal milk differed only in OS content, each diet group being distinguishable. HF1 and HP1 offspring had decreased plasma lipopolysaccharide compared with C1. Offspring sex, maternal diet, and time (5 weeks vs. 22 weeks of age) affected the microbial groups examined. Bifidobacteria was higher in HF dams and offspring. Increasing protein or fiber content in maternal diet during pregnancy and lactation modifies milk OS content and gut microbiota of dams which may influence establishment of gut microbiota in offspring. © 2014 The Obesity Society.

  8. Small mammal community succession on the beach of Dongting Lake, China after the Three Gorges Project.

    Science.gov (United States)

    Zhang, Meiwen; Wang, Yong; Li, Bo; Guo, Cong; Huang, Guoxian; Shen, Guo; Zhou, Xunjun

    2014-06-01

    Although the Three Gorges Project (TGP) may have affected the population structure and distribution of plant and animal communities, few studies have analyzed the effect of this project on small mammal communities. Therefore, the present paper compares the small mammal communities inhabiting the beaches of Dongting Lake using field investigations spanning a 20-year period, both before and after the TGP was implemented. Snap traps were used throughout the census. The results indicate that the TGP caused major changes to the structure of the small mammal community at a lake downstream of the dam. First, species abundance on the beaches increased after the project commenced. The striped field mouse (Apodemus agrarius) and the Norway rat (Rattus norvegicus), which rarely inhabited the beach before the TGP, became abundant (with marked population growth) once water was impounded by the Three Gorges Reservoir. Second, dominant species concentration indices exhibited a stepwise decline, indicating that the community structure changed from a single dominant species to a more diverse species mix after TGP implementation. Third, the regulation of water discharge release by the TGP might have caused an increase in the species diversity of the animal community on the beaches. A significant difference in diversity indices was obtained before and after the TGP operation. Similarity indices also indicate a gradual increase in species numbers. Hence, a long-term project should be established to monitor the population fluctuations of the Yangtze vole (Microtus fortis), the striped field mouse and the Norway rat to safeguard against population outbreaks (similar to the Yangtze vole outbreak in 2007), which could cause crop damage to adjacent farmland, in addition to documenting the succession process of the small mammal community inhabiting the beaches of Dongting Lake. © 2013 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley

  9. Temperature changes in Three Gorges Reservoir Area and linkage with Three Gorges Project

    Science.gov (United States)

    Song, Zhen; Liang, Shunlin; Feng, Lian; He, Tao; Song, Xiao-Peng; Zhang, Lei

    2017-05-01

    The Three Gorges Project (TGP) is one of the largest hydroelectric projects throughout the world. It has brought many benefits to the society but also led to endless debates about its environmental and climatic impacts. Monitoring the spatiotemporal variations of temperature in the Three Gorges Reservoir Area (TGRA) is important for understanding the climatic impacts of the TGP. In this study, we used remote sensing-based land surface temperature (LST) and ground-measured air temperature data to investigate temperature changes in the TGRA. Results showed that during the daytime in summer, LST exhibited significant cooling (1-5°C) in the downstream region of the reservoir, whereas LST during the nighttime in winter exhibited significant warming (1-5°C) across the entire reservoir. However, these cooling and warming effects were both locally constrained within 5 km buffer along the reservoir. The changes in air temperature were consistent with those in LST, with 0.67°C cooling in summer and 0.33°C warming in winter. The temperature changes along the reservoir not only resulted from the land-water conversion induced by the dam impounding but were also related to the increase of vegetation cover caused by the ecological restoration projects. Significant warming trends were also found in the upstream of TGRA, especially during the daytime in summer, with up to 5°C for LST and 0.52°C for air temperature. The warming was caused mainly by urban expansion, which was driven in part by the population resettlement of TGP. Based on satellite observations, we investigated the comprehensive climatic impacts of TGP caused by multiple factors.

  10. Accumulation and decomposition of the herbicide propanil in the plants dominating in the littoral zone of the Three Gorges Reservoir (TGR), China

    OpenAIRE

    Chen, Zhongli

    2016-01-01

    The Three Gorges Dam is located in the upper stream of the Yangtze River (Yichang, China) and is the biggest dam in the world. Since 2008, the corresponding Three Gorges Reservoir (TGR) covers an area of 58,000 km2 in total and a water surface area of more than 1,080 km2. Anti-seasonal water flood events create water-level differences of 30 m (with 145 m in summer and 175 m in winter, sea level). These events considerably influence the distribution patterns of biotic (e.g. vegetation) and abi...

  11. Conditions and processes affecting sand resources at archeological sites in the Colorado River corridor below Glen Canyon Dam, Arizona

    Science.gov (United States)

    East, Amy E.; Collins, Brian D.; Sankey, Joel B.; Corbett, Skye C.; Fairley, Helen C.; Caster, Joshua J.

    2016-05-17

    This study examined links among fluvial, aeolian, and hillslope geomorphic processes that affect archeological sites and surrounding landscapes in the Colorado River corridor downstream from Glen Canyon Dam, Arizona. We assessed the potential for Colorado River sediment to enhance the preservation of river-corridor archeological resources through aeolian sand deposition or mitigation of gully erosion. By identifying locally prevailing wind directions, locations of modern sandbars, and likely aeolian-transport barriers, we determined that relatively few archeological sites are now ideally situated to receive aeolian sand supply from sandbars deposited by recent controlled floods. Whereas three-fourths of the 358 river-corridor archeological sites we examined include Colorado River sediment as an integral component of their geomorphic context, only 32 sites currently appear to have a high degree of connectivity (coupled interactions) between modern fluvial sandbars and sand-dominated landscapes downwind. This represents a substantial decrease from past decades, as determined by aerial-photograph analysis. Thus, we infer that recent controlled floods have had a limited, and declining, influence on archeological-site preservation.

  12. Assessment of the Physicochemical Quality of Challawa Gorge Dam ...

    African Journals Online (AJOL)

    Dr Maimuna

    analyzed for some physicochemical parameters, heavy metals (Cd, Cr, Mn, Pb, Zn) and minerals (Na and K) using Atomic Absorption Spectrophotometric and Flame Photometric techniques. The results showed the following ranges of the physicochemical parameters; pH (7.78±1.1 to 7.82±0.2), Conductivity (45.0±3.2.

  13. Critical Quality Source Diagnosis for Dam Concrete Construction Based on Quality Gain-loss Function

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2014-06-01

    Full Text Available In dam concrete construction process, it not only has quality loss arising from quality fluctuation, but also gains quality compensation effect due to the mutual cooperation and adaptation coupling between working procedures (WPs. The calculation and transmission complexity of the quality loss and quality compensation affect the quality management of dam concrete construction. As the quality compensation effect existing in the production practice cannot be described by Taguchi quality loss function, the concept of quality gain-loss function was presented in this paper, which was based on endowing the constant term in the expansion of Taylor series with physical meaning—quality compensation. Based on quality gain-loss function theory, a new quality gain-loss transmission model of dam concrete construction based on GERT network was constructed and its effective algorithm was designed. WP quality gain-loss and its impact on the final product were reasonably measured, and the critical quality routes and critical quality WPs were detected and diagnosed in dam concrete construction network. Summer temperature-controlled concrete construction in the third phase of Three Gorges Project (TGP was taken as an example to carry out the study, and the calculation results showed the validity and practicability of the presented model and algorithm.

  14. Reservoir stratification affects methylmercury levels in river water, plankton, and fish downstream from Balbina hydroelectric dam, Amazonas, Brazil.

    Science.gov (United States)

    Kasper, Daniele; Forsberg, Bruce R; Amaral, João H F; Leitão, Rafael P; Py-Daniel, Sarah S; Bastos, Wanderley R; Malm, Olaf

    2014-01-21

    The river downstream from a dam can be more contaminated by mercury than the reservoir itself. However, it is not clear how far the contamination occurs downstream. We investigated the seasonal variation of methylmercury levels in the Balbina reservoir and how they correlated with the levels encountered downstream from the dam. Water, plankton, and fishes were collected upstream and at sites between 0.5 and 250 km downstream from the dam during four expeditions in 2011 and 2012. Variations in thermal stratification of the reservoir influenced the methylmercury levels in the reservoir and in the river downstream. Uniform depth distributions of methylmercury and oxygen encountered in the poorly stratified reservoir during the rainy season collections coincided with uniformly low methylmercury levels along the river downstream from the dam. During dry season collections, the reservoir was strongly stratified, and anoxic hypolimnion water with high methylmercury levels was exported downstream. Methylmercury levels declined gradually to 200 km downstream. In general, the methylmercury levels in plankton and fishes downstream from the dam were higher than those upstream. Higher methylmercury levels observed 200-250 km downstream from the dam during flooding season campaigns may reflect the greater inflow from tributaries and flooding of natural wetlands that occurred at this time.

  15. Responses of spatial-temporal dynamics of bacterioplankton community to large-scale reservoir operation: a case study in the Three Gorges Reservoir, China

    OpenAIRE

    Li, Zhe; Lu, Lunhui; Guo, Jinsong; Yang, Jixiang; Zhang, Jiachao; He, Bin; Xu, Linlin

    2017-01-01

    Large rivers are commonly regulated by damming, yet the effects of such disruption on bacterioplankton community structures have not been adequately studied. The aim of this study was to explore the biogeographical patterns present under dam regulation and to uncover the major drivers structuring bacterioplankton communities. Bacterioplankton assemblages in the Three Gorges Reservoir (TGR) were analyzed using Illumina Miseq sequencing by comparing seven sites located within the TGR before and...

  16. Spatiotemporal Variations of Extreme Precipitation under a Changing Climate in the Three Gorges Reservoir Area (TGRA

    Directory of Open Access Journals (Sweden)

    Mingquan Lü

    2018-01-01

    Full Text Available The Three Gorges Dam (TGD is one of the largest hydroelectric projects in the world. Monitoring the spatiotemporal distribution of extreme precipitation offers valuable information for adaptation and mitigation strategies and reservoir management schemes. This study examined variations in extreme precipitation over the Three Gorges Reservoir area (TGRA in China to investigate the potential role of climate warming and Three Gorges Reservoir (TGR. The trends in extreme precipitation over the TGRA were investigated using the iterative-based Mann–Kendall (MK test and Sen’s slope estimator, based on weather station daily data series and TRMM (Tropical Rainfall Measuring Mission data series. The mean and density distribution of extreme precipitation indices between pre-dam and post-dam, pre-1985 and post-1985, and near and distant reservoir area were assessed by the Mann–Whitney test and the Kolmogorov–Smirnov test. The ratio of extreme precipitation to non-extreme precipitation became larger. The precipitation was characterized by increases in heavy precipitation as well as decreases in light and moderate rain. Comparing extreme precipitation indices between pre-1985 (cooling and post-1985 (warming indicated extreme precipitation has changed to become heavier. Under climate warming, the precipitation amount corresponding to more than the 95th percentile increased at the rate of 6.48%/°C. Results from comparing extreme precipitation for the pre- and post-dam, near reservoir area (NRA and away from the reservoir area (ARA imply an insignificant role of the TGR on rainfall extremes over the TGRA. Moreover, the impoundment of TGR did not exert detectable impacts on the surface relative humidity (RH and water vapor pressure (WP.

  17. Variations of Hydrological Regime in the Jingjiang Reach of the Yangtze River after Operation of the Three Gorges Project

    Science.gov (United States)

    Zhu, Y.-H.; Guo, X.-H.; Hu, W.; Qu, G.; He, G.-S.

    2012-04-01

    The Three Gorges Project (TGP) of China has been in operation since 2003. In October 2010 the water level at the Three Gorges Dam (TGD) rose to the normal storage water level of 175 m, indicting the realization of the integrated targets of the TGP in terms of flood protection, electricity generation, navigation, etc. The operation of the TGP has changed the flow and sediment conditions (i.e. the hydrological regime) of the river channel downstream. The 347.2 km Jingjiang Reach, part of the middle reach of the Yangtze River, is very closely dowstream of the TGD and is affected relatively earlier and significant by the project operation. Based on the measured prototype hydrological data from 1950 to 2010, variations of the hydrological regime in the Jingjiang Reach after operation of the TGP are analyzed. The results showing that the runoff of the river is of no clear variation tendency during the last 60 years. However, after the operation of the TGP, the sediment concentration of the flow in the Jingjiang Reach decreased by 75%; coarsening of the suspended load and bed load in the river is evident; the water level at the same flow rate has a tendency to decline, with the margin of decline of the upper Jingjiang Reach being larger than that of the lower Reach, and that at smaller flow rate being larger than at larger flow rate. The flow and sediment diversion from the Yangtze River to the Dongting Lake via the three outlets also has a tendency to decrease; the degree of dcrease of the sediment diversion is much larger than that of the flow diversion. After the operation of the TGP, except the 2006 is a special low flow year, in which the decrease of the ratios of flow and sediment diversion are relatively large, the ratios are of no clear unidirectional variation tendency in the other years. Due to the operation of the TGP, within one year, the flow diversion in October is decreased comparing with that before the operation. Keywords: The Three Gorges Project, the

  18. Taking a new approach to dam building

    International Nuclear Information System (INIS)

    Taylor, D.

    1999-01-01

    Problems, including corruption, dogging construction of the Three Gorges dam being built in China are discussed. The article questions whether large hydro projects can ever be completed on time and within budget. It was suggested that by operating a build-operate-transfer scheme there might be greater incentives to complete on time but the vice-president of Skanska Civil Engineering was sceptical due to the risk involved. Through the Three Gorges Project, the Chinese government has learned that the relocation of thousands of people is far from easy. From a technical aspect, there may be unexpected problems in building underground. Some problems which arose in major hydro projects in India, Turkey and Lesotho were recounted. The vice-president of Skanska offered three pieces of advice and they are listed. (UK)

  19. Perspectives on dam safety in Canada

    International Nuclear Information System (INIS)

    Halliday, R.

    2004-01-01

    Canadian dam safety issues were reviewed from the perspective of a water resources engineer who is not a dam safety practitioner. Several external factors affecting dam safety were identified along with perceived problems in dam safety administration. The author claims that the main weakness in safety practices can be attributed to provincial oversights and lack of federal engagement. Some additions to the Canadian Dam Safety Guidelines were proposed to address these weaknesses. Canada has hundreds of large dams and high hazard dams whose failure would result in severe downstream consequences. The safety of dams built on boundary waters shared with the United States have gained particular attention from the International Joint Commission. This paper also examined safety criteria for concerns such as aging dams, sabotage and global climate change that may compromise the safety of a dam. 26 refs

  20. Impacts of the Three Gorges Project on Local Climate

    Science.gov (United States)

    Song, Z.; Liang, S.; Feng, L.

    2015-12-01

    Three Gorges Project (TGP) is the largest hydroelectric project in the world and has led to significant land cover changes in Three Gorges Reservoir Area (TGRA). Since its construction the debates on its environmental and climatic impacts have never stopped, especially after the extreme drought and flood in Yangtze River Basin these years. TGP reached its final impounding water level in 2010. However, studies on systematically monitoring the long-term variations in surface and atmospheric parameters in TGRA are still lacking. In this study, three important surface parameters - surface albedo, land surface temperature (LST) and evapotranspiration (ET) and two climatic parameters - air temperature and precipitation were investigated from 2000 to 2013 by combining multiple remote sensing data and ground measurements. Results showed that along the reservoir albedo decreased significantly as a result of water impounding. Correspondingly, in the same region daytime LST decreased in spring and summer and nighttime LST increased in autumn and winter. In the western region of TGRA, albedo increased due to resettlement and LST also changed. The average ET increased by 20% in TGR but kept stable in the whole TGRA. In contrast to LST, air temperature showed less apparent spatial and temporal variability. Only in the region near the dam air temperature experienced a decrease at daytime and an increase at nighttime. Further analysis demonstrated precipitation revealed no apparent changes in TGRA and the precipitation anomaly in northwest of TGRA may not be connected with TGP. All of the findings provide a more substantial clues of local climate change caused by TGP.

  1. How does layered heterogeneity affect the ability of subsurface dams to clean up coastal aquifers contaminated with seawater intrusion?

    Science.gov (United States)

    Abdoulhalik, Antoifi; Ahmed, Ashraf A.

    2017-10-01

    The main purpose of this work was to examine how aquifer layering impacts the ability of subsurface dams to retain seawater intrusion (SWI) and to clean up contaminated coastal aquifers using both experimental and numerical techniques. Four different layering configurations were investigated, including a homogeneous case (case H), and three different layered cases where a low permeability layer was set at the top of the aquifer (case LH), at the middle part of the aquifer as interlayer (case HLH), and at the lower part of the aquifer (case HL). The subsurface dam was able to retain the saltwater wedge associated with a drop of the hydraulic gradient from 0.0158 down to 0.0095 in all the cases, thereby achieving up to 78% reduction in the saltwater toe length. In cases LH and HLH, the start of the saltwater spillage was delayed compared to the homogeneous case, and the time taken for the freshwater zone to be fully contaminated (post-spillage) was twice and three times longer, respectively. By contrast, the existence of a low K layer at the bottom of the aquifer (case HL) considerably weakened the ability of dams to retain the intrusion, allowing for quicker saltwater spillage past the wall. The natural cleanup of SWI-contaminated coastal aquifers was, for the first time, evidenced in heterogeneous settings. Depending on the stratification pattern, the presence of stratified layers however prolonged the cleanup time to various degrees, compared to the homogeneous scenario, particularly in case HL, where the cleanup time was nearly 50% longer.

  2. Urban Panorama Tourism Planning A View From River Tour Course In Post-Three Gorges Era

    Directory of Open Access Journals (Sweden)

    Wei Jia Tian

    2012-12-01

    Full Text Available The upstream cities of Yangtze River have been witnessing significant transforming since the beginning of the construction of the Three Gorges hydroelectric dam project. Chongqing Port Authority had its opportunity to alternate the river tourism strategy from being the upstream terminal of the golden route into creating a particular cruise course towards perceiving the panorama of continuous elevation of mountainous city, at the same time, promoting the renovation of the urban design so as to revival the typical mountain-river vista. This paper bases on the panoramic research of Chongqing peninsula; discusses the characteristic aspects of the three-dimension sightseeing of the mountainous city on the cruise route, which widely exists in the Three Gorges region as well. And this method is different from the two dimensional approach of skyline analysis which is more suitable for the topographic area. The achieved work can offer the tourism-related sectors a sustainable assistance to deal with “tourbanism” topics in the urban regeneration process in the Three Gorges regions.

  3. The Archdiocese of Mariana, Liberation Theology, and Emergence of the Movement of People Affected by Dams in the Alto Rio Doce region (MG

    Directory of Open Access Journals (Sweden)

    Fabrício Roberto Costa Oliveira

    2008-10-01

    Full Text Available The article analyzes the mobilization and networking of progressive religious groups in the Archdiocese of Mariana in Minas Gerais State and the influence of this process on the emergence and consolidation of the Movement of People Affected by Dams in the Alto Rio Doce and Zona da Mata regions of the state. We use the political process approach to explain ideological and institutional transformations within the Archdiocese and their influence on the organization of local populations. Documents and interview data demonstrate that a favorable political opportunity structure provided conditions which facilitated the diffusion of ideas and religious practices related to Liberation Theology. The interaction of religious activists contributed to the formation of social movement networks and mobilization structures which facilitated dissemination. Framing processes played an important role in facilitating the assimilation of these ideas by activists and applying them within a vision of building a more just society. Keywords: Archdiocese of Mariana; mobilization; people affected by dams; Liberation Theology; social movements.

  4. Geomorphic response of the Sandy River, Oregon, to removal of Marmot Dam

    Science.gov (United States)

    Major, Jon J.; O'Connor, Jim E.; Podolak, Charles J.; Keith, Mackenzie K.; Grant, Gordon E.; Spicer, Kurt R.; Pittman, Smokey; Bragg, Heather M.; Wallick, J. Rose; Tanner, Dwight Q.; Rhode, Abagail; Wilcock, Peter R.

    2012-01-01

    deposited within the sediment wedge and within the gorge, whereas eroded sand largely passed through the gorge and was broadly dispersed farther downstream. The sequence of transporting flows affected the specific trajectory of reservoir erosion and downstream sediment transport during the 2 years following breaching. However, because the overall erosion was largely a consequence of knickpoint retreat and channel widening, which in the 2 years after removal had affected most of the reservoir reach, it is unlikely that the specific sequence of flows significantly affected the overall outcome. Because the knickpoint had largely passed through the reservoir within 2 years, and the remaining reservoir sediment is mostly isolated high above armored or bedrock banks, it is unlikely that substantial additional sediment from the reservoir site will enter the system unless very large flows occur. Continued channel evolution downstream of the dam site is probable as deposits formed in the first 2 years are episodically mobilized. Below the Sandy River gorge, detection of effects related to release of reservoir sediment is challenging, especially in areas of sand deposition, because of the high background supply of sand in the river and substantial channel dynamism.

  5. Damming the rivers of the Amazon basin.

    Science.gov (United States)

    Latrubesse, Edgardo M; Arima, Eugenio Y; Dunne, Thomas; Park, Edward; Baker, Victor R; d'Horta, Fernando M; Wight, Charles; Wittmann, Florian; Zuanon, Jansen; Baker, Paul A; Ribas, Camila C; Norgaard, Richard B; Filizola, Naziano; Ansar, Atif; Flyvbjerg, Bent; Stevaux, Jose C

    2017-06-14

    More than a hundred hydropower dams have already been built in the Amazon basin and numerous proposals for further dam constructions are under consideration. The accumulated negative environmental effects of existing dams and proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin's floodplains, estuary and sediment plume. We introduce a Dam Environmental Vulnerability Index to quantify the current and potential impacts of dams in the basin. The scale of foreseeable environmental degradation indicates the need for collective action among nations and states to avoid cumulative, far-reaching impacts. We suggest institutional innovations to assess and avoid the likely impoverishment of Amazon rivers.

  6. Ecohydrology of a Dammed Amazon

    Science.gov (United States)

    Timpe, K. A.; Kaplan, D. A.

    2016-12-01

    The Amazon River watershed is the world's largest river basin and provides >US$30 billion/yr in ecosystem services to local populations, national societies and humanity at large. Construction of >30 large hydroelectric dams and >170 small dams in the Brazilian Amazon is currently underway as a result of governmental plans geared toward increased energy security, economic growth, improved living standards and industrialization. Changes in the Amazon's freshwater ecosystems from the development of hydropower will have a cascade of physical, ecological, and social effects at local to global scales. Here we demonstrate the extensive and large-scale effects of hydroelectric dams in the Amazon region on hydrologic parameters calculated using the Indicators of Hydrologic Alteration (IHA) method applied to 33 small and large dams in the Brazilian Amazon. Our analysis provides the first holistic assessment of hydrological alterations (HA) caused by Amazonian dams and offers insight on the primary physical and management drivers of dam impacts. Across sites, results show that dams have affected all ecologically important flow characteristics (i.e., magnitude, duration, timing, frequency and rate of change of pulse events). While each dam/river system are unique, some dams cause substantially greater HA. The "worst" dams were Balbina (HA=108%), Manso (HA=62%), and Serra da Mesa (HA=48%). All three are "large" dams with substantial reservoirs, however Serra da Mesa produces 6 times more electricity than either Balbina or Manso, with lower impact. The most dramatic dam-induced shifts in hydrologic regime were related to the frequency/duration and frequency/rate of change of pulse events. HA on rivers with multiple dams was only 8% higher than those with individual dams. Dam elevation and reservoir area were the best environmental predictors of HA. Results suggest that hydrological impacts from dams are similar among temperate and tropical climates (i.e., peak flows are often

  7. Raptor Use of the Rio Grande Gorge

    Energy Technology Data Exchange (ETDEWEB)

    Ponton, David A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-20

    The Rio Grande Gorge is a 115 km long river canyon located in Southern Colorado (15 km) and Northern New Mexico (100 km). The majority of the canyon is under the administration of the Bureau of Land Management {BLM), and 77 km of the canyon south of the Colorado/New Mexico border are designated Wild River under the National Wild and Scenic Rivers Act of 1968. Visits I have made to the Rio Grande Gorge over the past 15 .years disclosed some raptor utilization. As the Snake River Birds of Prey Natural Area gained publicity, its similarity to the Rio Grande Gorge became obvious, and I was intrigued by the possibility of a high raptor nesting density in the Gorge. A survey in 1979 of 20 km of the northern end of the canyon revealed a moderately high density of red-tailed hawks and prairie falcons. With the encouragement of that partial survey, and a need to assess the impact of river-running on nesting birds of prey, I made a more comprehensive survey in 1980. The results of my surveys, along with those of a 1978 helicopter survey by the BLM, are presented in this report, as well as general characterization of the area, winter use by raptors, and an assessment of factors influencing the raptor population.

  8. Flood management selections for the Yangtze River midstream after the Three Gorges Project operation

    Science.gov (United States)

    Fang, Hongwei; Han, Dong; He, Guojian; Chen, Minghong

    2012-04-01

    SummaryAfter the Yangtze River was closed by the Three Gorges Project (TGP) in 2003, erosion occurred from the dam site to the river mouth, especially in the middle and lower reaches of the Yangtze River. However, in some local areas of Chenglingji reach which holds the key position for flood management, there is actually deposition in contrast to the expected erosion. In this paper, a one dimensional mathematical model of the river network with sediment transport is used as the tool to simulate flow and fluvial processes. The calculation domain is from Yichang, which is downstream of the dam, to Hankou, the controlling node of flood management, 694 km long in total. The model is calibrated based on the field data of hydrology and sediment transport during the period from October 2003 to October 2008. Then the model is utilized to simulate the erosion and deposition of the middle and lower reaches of the Yangtze River in the next two decades, and produce the results of a new river channel after river bed deformation occurs. The typical flood processes of 1954 and 1998 in the Yangtze River basin are used to check the flood management scheme for the research area, and results show that water storage of Three Gorges Reservoir (TGR) and a flood diversion program downstream of the Yangtze River should be taken into consideration.

  9. Using a sediment budget to understand geomorphic response following dam removal

    Science.gov (United States)

    Major, J. J.; O'Connor, J. E.; Podolak, C.; Keith, M.; Spicer, K.; Pittman, S.; Bragg, H.; Wallick, J.; Grant, G.

    2013-12-01

    Dam removal provides an exceptional setting for developing tightly constrained sediment budgets linking reservoir erosion with downstream deposition. Measurements of erosion of impounded sediment can provide precise values on sediment input, and measurements of downstream flux and deposition provide potentially well-constrained estimates of output and storage. Measurements of sediment erosion, flux, deposition, and composition following the 2007 breaching of Marmot Dam, Oregon, allowed construction of size-fraction sediment budgets for the first year following dam removal, which documented the spatial distributions and fluxes of nearly 400,000 m3 of sand and gravel released from the former reservoir. The budget encompassed a ~25-km-long control-volume-reach of the Sandy River extending from about 10 km upstream of the dam site to about 15 km downstream. Budget components consisted of measurements of sediment flux into the reservoir reach, erosion from the reservoir reach, sediment flux and deposition along a 2-km-long reach immediately downstream of the dam site before the river entered a 7-km-long bedrock gorge, and sediment flux out of the gorge. Our results show that channel morphology strongly filtered the flux and distribution of released sediment. About 70-90 percent of the gravel released by reservoir erosion deposited within 2 km of the dam site, whereas sand largely passed into and through the bedrock gorge. Flux measurements ~8 km beyond the gorge exit indicate that about half the sand load that emerged from the gorge deposited in the intervening 8-km channel reach. Combining flux measurements with volumetric measurements of erosion and deposition greatly aided construction and interpretation of the sediment budget. Despite the immense effort exerted to measure sediment erosion (relatively easy; cost effective), flux (very challenging; expensive), and deposition (relatively easy above gorge; cost effective), and the tight spatial distributions of the

  10. Diet of Bryconops alburnoides and B. caudomaculatus (Osteichthyes: Characiformes in the region affected by Balbina Hydroelectric Dam (Amazon drainage, Brazil

    Directory of Open Access Journals (Sweden)

    Cylene C. da Silva

    Full Text Available The study of fish diet and its interaction with the environment provides important data on ecology and behavior, as fish face varying environmental and food availability conditions. The aim of the present study was to determine the diet of Bryconops caudomaculatus and Bryconops alburnoides, as well as to assess its seasonal variation, within the area influenced by Balbina Hydroelectric Dam (BHD, in the Uatumã River (Amazon Basin, Brazil. Collections were carried out every two months from April 2005 to February 2007, using gill nets with mesh sizes ranging from 12 to 60 mm between opposite knots. Two methods were used for determining diet: frequency of occurrence and relative volume, which were used to calculate the alimentary index (IAi. Diet similarity between species was analyzed by applying the Morisita index. Bryconops alburnoides ingested 12 items and B. caudomaculatus 10, with a 59% similarity between ingested items. Terrestrial insects for B. alburnoides and immature insects for B. caudomaculatus were the main items in their diets, and therefore, they were considered insectivorous. The seasonal composition of the diet of B. alburnoides was influenced by environmental factors, and in spite of the dominance of immature insects, it had a significant number of terrestrial insects during the heavy rainfall periods.

  11. Analyses of potential factors affecting survival of juvenile salmonids volitionally passing through turbines at McNary and John Day Dams, Columbia River

    Science.gov (United States)

    Beeman, John; Hansel, Hal; Perry, Russell; Hockersmith, Eric; Sandford, Ben

    2011-01-01

    This report describes analyses of data from radio- or acoustic-tagged juvenile salmonids passing through hydro-dam turbines to determine factors affecting fish survival. The data were collected during a series of studies designed to estimate passage and survival probabilities at McNary (2002-09) and John Day (2002-03) Dams on the Columbia River during controlled experiments of structures or operations at spillways. Relatively few tagged fish passed turbines in any single study, but sample sizes generally were adequate for our analyses when data were combined from studies using common methods over a series of years. We used information-theoretic methods to evaluate biological, operational, and group covariates by creating models fitting linear (all covariates) or curvilinear (operational covariates only) functions to the data. Biological covariates included tag burden, weight, and water temperature; operational covariates included spill percentage, total discharge, hydraulic head, and turbine unit discharge; and group covariates included year, treatment, and photoperiod. Several interactions between the variables also were considered. Support of covariates by the data was assessed by comparing the Akaike Information Criterion of competing models. The analyses were conducted because there was a lack of information about factors affecting survival of fish passing turbines volitionally and the data were available from past studies. The depth of acclimation, tag size relative to fish size (tag burden), turbine unit discharge, and area of entry into the turbine intake have been shown to affect turbine passage survival of juvenile salmonids in other studies. This study indicates that turbine passage survival of the study fish was primarily affected by biological covariates rather than operational covariates. A negative effect of tag burden was strongly supported in data from yearling Chinook salmon at John Day and McNary dams, but not for subyearling Chinook salmon or

  12. Landslide Monitoring in Three Gorges Area Using Multi-Frequency Insar Techniques

    Science.gov (United States)

    Liao, M.; Balz, T.; Tantianuparp, P.; Shi, X.; Zhang, L.; Wang, T.

    2012-12-01

    Landslide is a term describing the downslope movement of soil, rock, and organic materials under the effects of gravity. Landslides are very destructive forces. In order to decrease landslide occurrences and its impacts, landslide monitoring is applied to analyze, forecast, and control landslides. The Three Gorges Project, the largest hydroelectric project of the world, began to function in 2003. The dam site is situated at Sandouping in China's Hubei Province. The reservoir has a length of approximately 600 km along the Yangtze River. In 2001, in a statistical survey, carried out by the Ministry of Land and Resources of China, landslides were observed in all counties surrounding the Three Gorges reservoir and nearly 2500 landslide bodies were observed. There are many landslide triggering factors in this area, for example the dam was built on a geologically unstable zone, the large surface-water level change, the construction of new buildings and roads, deforestation, etc. The potential landslide hazards are threatening the lives of millions of residents in the area. The Three Gorges area has a rough topography and is heavily vegetated. In an effort to reduce the landslide risks, advanced monitoring techniques and methods, such as a GPS network and other terrestrial surveillance technologies, are used in the area. Although these techniques can acquire highly accurate results, their results are only available over sparse measurement points and it they requires high costs for manpower and rather high costs for the instrument manipulation. Synthetic Aperture Radar (SAR), an active microwave imaging system, suffers from temporal decorrelation when monitoring heavily vegetated area as the Three Gorges. In order to analysis long-term and continuous displacement trend in this area, Differential Interferometric SAR (D-InSAR) and Persistent Scatterer Interferometry (PSI) are applied. Both techniques are able to detect surface motions. We use high resolution TerraSAR-X X

  13. Dam Safety Concepts

    NARCIS (Netherlands)

    Duricic, J.

    2014-01-01

    The majority of dams constructed in the world are dams that can be categorized as embankment dams. Throughout history we can point to many failures of dams, and embankment dams in particular. Nowadays it is clear that the goal to construct stable dams has not been achieved, even with advanced

  14. Alpine dams

    Directory of Open Access Journals (Sweden)

    Alain Marnezy

    2009-03-01

    Full Text Available Les barrages-réservoirs de montagne ont été réalisés initialement dans les Alpes pour répondre à la demande d’énergie en période hivernale. Une certaine diversification des usages de l’eau s’est ensuite progressivement développée, en relation avec le développement touristique des collectivités locales. Aujourd’hui, la participation des ouvrages d’Électricité De France à la production de neige de culture représente une nouvelle étape. Dans les régions où les aménagements hydroélectriques sont nombreux, les besoins en eau pour la production de neige peuvent être résolus par prélèvements à partir des adductions EDF. Les gestionnaires de stations échappent ainsi aux inconvénients liés à la construction et à la gestion des « retenues collinaires ». Cette évolution, qui concerne déjà quelques régions alpines comme la haute Maurienne ou le Beaufortin, apparaît comme une forme renouvelée d’intégration territoriale de la ressource en eau.Mountain reservoirs were initially built in the Alps to meet energy needs in the winter. A certain diversification in the uses of water then gradually developed, related to tourism development in the local communities. Today, the use of facilities belonging to EDF (French Electricity Authority to provide water for winter resorts to make artificial snow represents a new phase. By taking water from EDF resources to supply snow-making equipment, resort managers are thus able to avoid the problems related to the construction and management of small headwater dams. This new orientation in the use of mountain water resources already affects a number of alpine regions such as the Upper Maurienne valley and Beaufortain massif and represents a renewed form of the territorial integration of water resources.

  15. Landslides in the western Columbia Gorge, Skamania County, Washington

    Science.gov (United States)

    Pierson, Thomas C.; Evarts, Russell C.; Bard, Joseph A.

    2016-11-04

    SummaryRecent light detection and ranging (lidar) imagery has allowed us to identify and map a large number of previously unrecognized landslides, or slides, in heavily forested terrain in the western Columbia Gorge, Skamania County, Washington, and it has revealed that the few previously recognized areas of instability are actually composites of multiple smaller landslides. The high resolution of the imagery further reveals that landslides in the map area have complex movement histories and span a wide range of relative ages. Movement histories are inferred from relative landslide locations and crosscutting relations of surface features. Estimated age ranges are based on (1) limited absolute dating; (2) relative fineness of landscape surface textures, calibrated by comparison with surfaces of currently active and dated landslides as interpreted from interferometric synthetic aperture radar (InSAR), global positioning system (GPS), and historical records; (3) sharpness and steepness of larger-scale surface morphologic features, calibrated by comparison with similar dated features in other regions; (4) degree of surface erosion; and (5) evidence of erosion or deposition by late Pleistocene (15–22 ka) Missoula floods at or below 200 m altitude. The relative age categories are recent (0 to ~1,000 years old), intermediate-age (~1,000 to ~15,000 years old), and old (>~15,000 years old). Within the 221.5 km2 map area, we identified 215 discrete landslides, covering 140.9 km2 (64 percent of the map area). At least 12 of the recent landslides are currently moving or have moved within the last two decades. Mapping for this study expanded the area of previously recognized unstable terrain by 56 percent. Landslide geometries suggest that more than half (62 percent) of these slope failures are translational landslides or composite landslides with translational elements, with failure occurring along gently sloping bedding planes in zones of deeply weathered, locally clay rich

  16. Bedrock gorges in the central mainland Kachchh: Implications for ...

    Indian Academy of Sciences (India)

    movements have been mapped on two scattered and eroded hillocks located north of the gorge (fig- ure 2a). Though the channel of Khari river remains dry for most of the year, the gorge-reach is perma- nently filled with stagnant subsurface water that seeps up along the various structural features men- tioned above. This is ...

  17. Three Gorges Reservoir Area: soil erosion under natural condition vs. soil erosion under current land use

    Science.gov (United States)

    Schönbrodt, Sarah; Behrens, Thorsten; Scholten, Thomas

    2010-05-01

    Apparently, the current most prominent human-induced example for large scale environmental impact is the Three Gorges Dam in China. The flooding alongside the Yangtze River, and its tributaries results in a vast loss of settlement and farmland area with productive, fertile valley soils. Due to the associated high land use dynamic on uphill-sites, the soil resources are underlying high land use pressure. Within our study, the soil erosion under natural conditions is compared to the soil erosion under current land use after the impoundment. Both were modeled using the empirical Universal Soil Loss Equation (USLE) which is able to predict long-term annual soil loss with limited data. The database consists of digital terrain data (45 m resolution DEM, erosive slope length based on Monte-Carlo-Aggregation according to Behrens et al. (2008)), field investigations of recent erosion forms, and literature studies. The natural disposition to soil erosion was calculated considering the USLE factors R, S, and K. The soil erosion under current land use was calculated taking into account all USLE factors. The study area is the catchment of the Xiangxi River in the Three Gorges Reservoir area. Within the Xiangxi Catchment (3,200 km²) the highly dynamic backwater area (580 km²), and two micro-scale study sites (Xiangjiaba with 2.8 km², and Quyuan with 88 km²) are considered more detailed as they are directly affected by the river impoundment. Central features of the Xiangxi Catchment are the subtropical monsoon climate, an extremely steep sloping relief (mean slope angle 39°, SD 22.8°) artificially fractured by farmland terraces, and a high soil erodibility (mean K factor 0.37, SD 0.13). On the catchment scale the natural disposition to soil erosion makes up to mean 518.0 t ha-1 a-1. The maximum potential soil loss of 1,730.1 t ha-1 a-1 under natural conditions is reached in the Quyuan site (mean 635.8 t ha-1 a-1) within the backwater area (mean 582.9 t ha-1 a-1). In the

  18. Assessing Risks of Mine Tailing Dam Failures

    Science.gov (United States)

    Concha Larrauri, P.; Lall, U.

    2017-12-01

    The consequences of tailings dam failures can be catastrophic for communities and ecosystems in the vicinity of the dams. The failure of the Fundão tailings dam at the Samarco mine in 2015 killed 19 people with severe consequences for the environment. The financial and legal consequences of a tailings dam failure can also be significant for the mining companies. For the Fundão tailings dam, the company had to pay 6 billion dollars in fines and twenty-one executives were charged with qualified murder. There are tenths of thousands of active, inactive, and abandoned tailings dams in the world and there is a need to better understand the hazards posed by these structures to downstream populations and ecosystems. A challenge to assess the risks of tailings dams in a large scale is that many of them are not registered in publicly available databases and there is little information about their current physical state. Additionally, hazard classifications of tailings dams - common in many countries- tend to be subjective, include vague parameter definitions, and are not always updated over time. Here we present a simple methodology to assess and rank the exposure to tailings dams using ArcGIS that removes subjective interpretations. The method uses basic information such as current dam height, storage volume, topography, population, land use, and hydrological data. A hazard rating risk was developed to compare the potential extent of the damage across dams. This assessment provides a general overview of what in the vicinity of the tailings dams could be affected in case of a failure and a way to rank tailings dams that is directly linked to the exposure at any given time. One hundred tailings dams in Minas Gerais, Brazil were used for the test case. This ranking approach could inform the risk management strategy of the tailings dams within a company, and when disclosed, it could enable shareholders and the communities to make decisions on the risks they are taking.

  19. NRC inventory of dams

    International Nuclear Information System (INIS)

    Lear, G.E.; Thompson, O.O.

    1983-01-01

    The NRC Inventory of Dams has been prepared as required by the charter of the NRC Dam Safety Officer. The inventory lists 51 dams associated with nuclear power plant sites and 14 uranium mill tailings dams (licensed by NRC) in the US as of February 1, 1982. Of the 85 listed nuclear power plants (148 units), 26 plants obtain cooling water from impoundments formed by dams. The 51 dams associated with the plants are: located on a plant site (29 dams at 15 plant sites); located off site but provide plant cooling water (18 dams at 11 additional plant sites); and located upstream from a plant (4 dams) - they have been identified as dams whose failure, and ensuing plant flooding, could result in a radiological risk to the public health and safety. The dams that might be considered NRC's responsibility in terms of the federal dam safety program are identified. This group of dams (20 on nuclear power plant sites and 14 uranium mill tailings dams) was obtained by eliminating dams that do not pose a flooding hazard (e.g., submerged dams) and dams that are regulated by another federal agency. The report includes the principal design features of all dams and related useful information

  20. Evaluation of Land Use, Land Management and Soil Conservation Strategies to Reduce Non-Point Source Pollution Loads in the Three Gorges Region, China.

    Science.gov (United States)

    Strehmel, Alexander; Schmalz, Britta; Fohrer, Nicola

    2016-11-01

    The construction of the Three Gorges Dam in China and the subsequent impoundment of the Yangtze River have induced a major land use change in the Three Gorges Reservoir Region, which fosters increased inputs of sediment and nutrients from diffuse sources into the water bodies. Several government programs have been implemented to mitigate high sediment and nutrient loads to the reservoir. However, institutional weaknesses and a focus on economic development have so far widely counteracted the effectiveness of these programs. In this study, the eco-hydrological model soil and water assessment tool is used to assess the effects of changes in fertilizer amounts and the conditions of bench terraces in the Xiangxi catchment in the Three Gorges Reservoir Region on diffuse matter releases. With this, the study aims at identifying efficient management measures, which should have priority. The results show that a reduction of fertilizer amounts cannot reduce phosphorus loads considerably without inhibiting crop productivity. The condition of terraces in the catchment has a strong impact on soil erosion and phosphorus releases from agricultural areas. Hence, if economically feasible, programmes focusing on the construction and maintenance of terraces in the region should be implemented. Additionally, intercropping on corn fields as well as more efficient fertilization schemes for agricultural land were identified as potential instruments to reduce diffuse matter loads further. While the study was carried out in the Three Gorges Region, its findings may also beneficial for the reduction of water pollution in other mountainous areas with strong agricultural use.

  1. Evaluation of Land Use, Land Management and Soil Conservation Strategies to Reduce Non-Point Source Pollution Loads in the Three Gorges Region, China

    Science.gov (United States)

    Strehmel, Alexander; Schmalz, Britta; Fohrer, Nicola

    2016-11-01

    The construction of the Three Gorges Dam in China and the subsequent impoundment of the Yangtze River have induced a major land use change in the Three Gorges Reservoir Region, which fosters increased inputs of sediment and nutrients from diffuse sources into the water bodies. Several government programs have been implemented to mitigate high sediment and nutrient loads to the reservoir. However, institutional weaknesses and a focus on economic development have so far widely counteracted the effectiveness of these programs. In this study, the eco-hydrological model soil and water assessment tool is used to assess the effects of changes in fertilizer amounts and the conditions of bench terraces in the Xiangxi catchment in the Three Gorges Reservoir Region on diffuse matter releases. With this, the study aims at identifying efficient management measures, which should have priority. The results show that a reduction of fertilizer amounts cannot reduce phosphorus loads considerably without inhibiting crop productivity. The condition of terraces in the catchment has a strong impact on soil erosion and phosphorus releases from agricultural areas. Hence, if economically feasible, programmes focusing on the construction and maintenance of terraces in the region should be implemented. Additionally, intercropping on corn fields as well as more efficient fertilization schemes for agricultural land were identified as potential instruments to reduce diffuse matter loads further. While the study was carried out in the Three Gorges Region, its findings may also beneficial for the reduction of water pollution in other mountainous areas with strong agricultural use.

  2. Key Technologies of the Hydraulic Structures of the Three Gorges Project

    Directory of Open Access Journals (Sweden)

    Xinqiang Niu

    2016-09-01

    Full Text Available To date, the Three Gorges Project is the largest hydro junction in the world. It is the key project for the integrated water resource management and development of the Changjiang River. The technology of the project, with its huge scale and comprehensive benefits, is extremely complicated, and the design difficulty is greater than that of any other hydro project in the world. A series of new design theories and methods have been proposed and applied in the design and research process. Many key technological problems regarding hydraulic structures have been overcome, such as a gravity dam with multi-layer large discharge orifices, a hydropower station of giant generating units, and a giant continual multi-step ship lock with a high water head.

  3. Impact of the Three Gorges project on ecological environment changes and snail distribution in Dongting Lake area.

    Science.gov (United States)

    Li, Feiyue; Ma, Shujuan; Li, Yiyi; Tan, Hongzhuan; Hou, Xunya; Ren, Guanghui; Cai, Kaiping

    2017-07-01

    The Three Gorges Dam (TGD) is a remarkable, far-reaching project in China. This study was conducted to assess the impact of TGD on changes in the ecological environment, snail distribution and schistosomiasis transmission in Dongting Lake area. Hydrological data were collected from 12 monitoring sites in Hunan section of Yangtze River before and after TGD was established. Data on snail distribution and human schistosomiasis infection were also collected. Correlation analyses were performed to detect the significance of snail distribution to changes in ecological environmental factors and human schistosomiasis infection. A series of ecological environmental factors have changed in Dongting Lake area following the operation of TGD. Volume of annual runoff discharged into Dongting Lake declined by 20.85%. Annual sediment volume discharged into the lake and the mean lake sedimentation rate decreased by 73.9% and 32.2%, respectively. From 2003 to 2015, occurrence rate of frames with living snails and mean density of living snails decreased overall by 82.43% and 94.35%, respectively, with annual decrements being 13.49% and 21.29%. Moreover, human infection rate of schistosomiasis had decreased from 3.38% in 2003 to 0.44% in 2015, with a reduction of 86.98%. Correlation analyses showed that mean density of living snails was significantly associated with water level (r = 0.588, p<0.001), as well as the mean elevation range of the bottomland (r = 0.374, p = 0.025) and infection rate of schistosomiasis (r = 0.865, p<0.001). Ecological environmental changes caused by the TGD were associated with distribution of snails, and might further affect the transmission and prevalence of schistosomiasis. Risk of schistosomiasis transmission still exists in Dongting Lake area and long-term monitoring is required.

  4. Spatiotemporal characteristics of the Huangtupo landslide in the Three Gorges region (China) constrained by radar interferometry

    Science.gov (United States)

    Tomás, R.; Li, Z.; Liu, P.; Singleton, A.; Hoey, T.; Cheng, X.

    2014-04-01

    The Huangtupo landslide is one of the largest in the Three Gorges region, China. The county-seat town of Badong, located on the south shore between the Xiling and Wu gorges of the Yangtze River, was moved to this unstable slope prior to the construction of the Three Gorges Project, since the new Three Gorges reservoir completely submerged the location of the old city. The instability of the slope is affecting the new town by causing residential safety problems. The Huangtupo landslide provides scientists an opportunity to understand landslide response to fluctuating river water level and heavy rainfall episodes, which is essential to decide upon appropriate remediation measures. Interferometric Synthetic Aperture Radar (InSAR) techniques provide a very useful tool for the study of superficial and spatially variable displacement phenomena. In this paper, three sets of radar data have been processed to investigate the Huangtupo landslide. Results show that maximum displacements are affecting the northwest zone of the slope corresponding to Riverside slumping mass I#. The other main landslide bodies (i.e. Riverside slumping mass II#, Substation landslide and Garden Spot landslide) exhibit a stable behaviour in agreement with in situ data, although some active areas have been recognized in the foot of the Substation landslide and Garden Spot landslide. InSAR has allowed us to study the kinematic behaviour of the landslide and to identify its active boundaries. Furthermore, the analysis of the InSAR displacement time-series has helped recognize the different displacement patterns on the slope and their relationships with various triggering factors. For those persistent scatterers, which exhibit long-term displacements, they can be decomposed into a creep model (controlled by geological conditions) and a superimposed recoverable term (dependent on external factors), which appears closely correlated with reservoir water level changes close to the river's edge. These

  5. The littoral zone in the Three Gorges Reservoir, China: challenges and opportunities.

    Science.gov (United States)

    Yuan, Xing-zhong; Zhang, Yue-wei; Liu, Hong; Xiong, Sen; Li, Bo; Deng, Wei

    2013-10-01

    For flood control purpose, the water level of the Three Gorges Reservoir (TGR) varies significantly. The annual reservoir surface elevation amplitude is about 30 m behind the dam. Filling of the reservoir has created about 349 km(2) of newly flooded riparian zone. The average flooding period lasts for more than 6 months, from mid-October to late April. The dam and its associated reservoir provide flood control, power generation, and navigation, but there are also many environmental challenges. The littoral zone is the important part of the TGR, once its eco-health and stability are damaged,which will directly endanger the ecological safety of the whole reservoir area and even the Yangtze River Basin. So, understanding the great ecological opportunities which are hidden in littoral zone of TGR (LZTGR) and putting forward approaches to solve the environmental problems are very important. LZTGR involves a wide field of problems, such as the landslides, potential water pollution, soil erosion, biodiversity loss, land cover changes, and other issues. The Three Gorges dam (TGD) is a major trigger of environmental change in the Yangtze River. The landslides, water quality, soil erosion, loss of biodiversity, dam operation, and challenge for land use are closely interrelated across spatial and temporal scales. Therefore, the ecological and environmental impacts caused by TGD are necessarily complex and uncertain. LZTGR is not only a great environmental challenge but also an ecological opportunity for us. In fact, LZTGR is an important structural unit of TGR ecosystem and has special ecosystem services function. Vegetation growing in LZTGR is therefore a valuable resource due to accumulation of carbon and nutrients. Everyone thinks that the ecological approach to the problem is needed. If properly designed, dike-pond systems, littoral woods systems, and re-created waterfowl habitats will have the capacity to capture nutrients from uplands and obstruct soil erosion

  6. "Possible impacts of climate change on the Danube river along the Iron Gate gorge

    Science.gov (United States)

    Adamovic, M.

    2009-04-01

    The research was dedicated to foreseeing the possible impacts of climate change on water resources in eastern part of Serbia, along the Danube catchment. The Danube basin is in the eastern section of the considered RCM ( Regional climate model). For this purposes, the RCM EBU-POM according to the IPCC scenario A1B, was used in its representation of the hydrological balance over the Danube river basin along Iron Gate gorge, for the time frame 1961-1990 and 2071-2100. The Danube's catchment encompasses continental climate, as it is land-dominated by advection from the surrounding land areas. This part of Danube catchment is greatly affected by the Mediterranean climate, since the Danube runoff gives a relevant contribution of freshwater flux into the Mediterranean sea and it is dependent mostly on precipitated water of Mediterranean origin. On the other, the Dinaric-Balkan mountain chains in the west and the Carpathian mountain bow in the north and east, present distinctive morphological and climatic regions and barriers. The hydrological balance has been computed in two different, but in principle equivalent ways. The first approach, which has a more hydrological nuance, relies on establishing relationships between annual averages of the hydrological balance parameters (E, P, T) in order to get relevant coefficients. The second approach, which is more typically meteorological, relies on the calculation of the E for the time frame 2071-2100 by using the previous coefficients and getting runoff depth (h) and discharge (Q) as the final outputs. The results according to this model, show that the river flow of the Danube, in this part of its basin, will decrease over 50% with a great consequences to the dams Iron Gate I and II, their accumulations and ecosystems. Furthermore, if we take into account predictions made by IPCC which say that the south-east Europe will face temperature growth of 0.2 degrees in the next two decades for the range of SRES scenarios, makes the

  7. Le barrage des trois Gorges (Chine

    Directory of Open Access Journals (Sweden)

    Luc Merchez

    1999-09-01

    Full Text Available Le barrage des Trois Gorges, en construction sur le Yangzijiang, sera le plus grand barrage au monde. Le gigantisme du projet et sa médiatisation croissante en Occident permettent d'en saisir les enjeux environnementaux et humains. On analyse les grandes caractéristiques du projet et ses conséquences premières avant d'aborder le travail de recherche de l'équipe SIG de l'IGA de Grenoble qui vise à préparer la relocalisation de plus d'un million d'habitants, et à modéliser les impacts démographiques et sociaux.

  8. The Total Risk Analysis of Large Dams under Flood Hazards

    Directory of Open Access Journals (Sweden)

    Yu Chen

    2018-02-01

    Full Text Available Dams and reservoirs are useful systems in water conservancy projects; however, they also pose a high-risk potential for large downstream areas. Flood, as the driving force of dam overtopping, is the main cause of dam failure. Dam floods and their risks are of interest to researchers and managers. In hydraulic engineering, there is a growing tendency to evaluate dam flood risk based on statistical and probabilistic methods that are unsuitable for the situations with rare historical data or low flood probability, so a more reasonable dam flood risk analysis method with fewer application restrictions is needed. Therefore, different from previous studies, this study develops a flood risk analysis method for large dams based on the concept of total risk factor (TRF used initially in dam seismic risk analysis. The proposed method is not affected by the adequacy of historical data or the low probability of flood and is capable of analyzing the dam structure influence, the flood vulnerability of the dam site, and downstream risk as well as estimating the TRF of each dam and assigning corresponding risk classes to each dam. Application to large dams in the Dadu River Basin, Southwestern China, demonstrates that the proposed method provides quick risk estimation and comparison, which can help local management officials perform more detailed dam safety evaluations for useful risk management information.

  9. Evaluation of factors affecting collection efficiency estimates of chinook salmon and steelhead smolts at McNary Dam, 1989. Final report

    International Nuclear Information System (INIS)

    Stuehrenberg, L.; Smith, D.; Johnson, O.W.

    1995-10-01

    Populations of salmonid smolts migrating through the hydropower system on the Columbia River incur some rate of mortality at each dam. To set priorities on options to minimize losses and provide safe passage of the smolts at dams, estimates of smolt survival at each dam are necessary. Two methods have been developed to obtain these survival estimates: the direct and the indirect method. With the indirect method, a test group of fish is released upstream and a-control group is released downstream from the area of interest. With the direct method, a single release of fish above the area of interest is used, with subsequent recovery below the area of interest. In 1988, the National Marine Fisheries Service (NMFS) began a 2-year study at McNary Dam to address possible sources of variation associated with the direct method of obtaining survival estimates. Five study objectives were established to determine whether (1) fish from the Columbia and Snake Rivers mixed as they migrated to McNary Dam (release-location tests); (2) collection rates for Columbia and Snake River stocks were the same (river-of-origin tests); (3) test-group release timing influenced recovery rates (time-of-release tests); (4) a collection-rate bias existed from use of test fish previously guided and collected at the recovery site (tests of previously guided fish); and (5) recovery rates obtained with PIT-tagged fish were comparable to those previously obtained with freeze-branded fish (PIT-tag vs. freeze-brand technology)

  10. How Big of an Effect Do Small Dams Have? Using Geomorphological Footprints to Quantify Spatial Impact of Low-Head Dams and Identify Patterns of Across-Dam Variation.

    Science.gov (United States)

    Fencl, Jane S; Mather, Martha E; Costigan, Katie H; Daniels, Melinda D

    2015-01-01

    Longitudinal connectivity is a fundamental characteristic of rivers that can be disrupted by natural and anthropogenic processes. Dams are significant disruptions to streams. Over 2,000,000 low-head dams (dams on geomorphology and ecology are largely untested. Progress for research and conservation is impaired by not knowing the magnitude of low-head dam impacts. Based on the geomorphic literature, we refined a methodology that allowed us to quantify the spatial extent of low-head dam impacts (herein dam footprint), assessed variation in dam footprints across low-head dams within a river network, and identified select aspects of the context of this variation. Wetted width, depth, and substrate size distributions upstream and downstream of six low-head dams within the Upper Neosho River, Kansas, United States of America were measured. Total dam footprints averaged 7.9 km (3.0-15.3 km) or 287 wetted widths (136-437 wetted widths). Estimates included both upstream (mean: 6.7 km or 243 wetted widths) and downstream footprints (mean: 1.2 km or 44 wetted widths). Altogether the six low-head dams impacted 47.3 km (about 17%) of the mainstem in the river network. Despite differences in age, size, location, and primary function, the sizes of geomorphic footprints of individual low-head dams in the Upper Neosho river network were relatively similar. The number of upstream dams and distance to upstream dams, but not dam height, affected the spatial extent of dam footprints. In summary, ubiquitous low-head dams individually and cumulatively altered lotic ecosystems. Both characteristics of individual dams and the context of neighboring dams affected low-head dam impacts within the river network. For these reasons, low-head dams require a different, more integrative, approach for research and management than the individualistic approach that has been applied to larger dams.

  11. Levels and distribution of polybrominated diphenyl ethers in Three Gorges Reservoir, China

    Directory of Open Access Journals (Sweden)

    Jingxian Wang

    2017-03-01

    Full Text Available Polybrominated diphenyl ethers (PBDEs were investigated in water, sediments, suspended sediments and biofilms in Three Gorges Reservoir (TGR, China. Results showed that dissolved bioavailable PBDEs in water of TGR collected with semipermeable membrane device (SPMD-based virtual organisms (VOs were very low in the range of n.d. to 811 pg/g lipid and the detected compounds were mainly low molecular BDEs such as BDE-15, 17, 28, 47, 49, 66, 99 and 100. The PBDE levels in the sediment core collected near the dam were also very low in the range of 84–300 pg/g dw and the detected compounds were mainly large molecular BDEs such as BDE-196, 197, 206, 207 and 208. In suspended sediments and biofilms, the levels of PBDEs ranged from 298 to 52,843 pg/g dw and the detected compounds were also mainly large molecular BDEs such as BDE- 196, 197, 201, 203, 206, 207, 208 and 209. The dominant compound was BDE-209 which accounted for more than 90% of the total BDEs. Therefore, large molecular BDEs tended to be attached on fine particles. The vertical profile of BDEs on suspended sediments (SS showed that SSs in the middle depth of water contained high level of BDE-209. The phenomenon indicated that most of BDE-209 did not settle into the sediment in front of the dam, instead transported further to downstream.

  12. Key Impact Factors on Dam Break Fatalities

    Science.gov (United States)

    Huang, D.; Yu, Z.; Song, Y.; Han, D.; Li, Y.

    2016-12-01

    Dam failures can lead to catastrophes on human society. However, there is a lack of research about dam break fatalities, especially on the key factors that affect fatalities. Based on the analysis of historical dam break cases, most studies have used the regression analysis to explore the correlation between those factors and fatalities, but without implementing optimization to find the dominating factors. In order to understand and reduce the risk of fatalities, this study has proposed a new method to select the impact factors on the fatality. It employs an improved ANN (Artificial Neural Network) combined with LOOCV (Leave-one-out cross-validation) and SFS (Stepwise Forward Selection) approach to explore the nonlinear relationship between impact factors and life losses. It not only considers the factors that have been widely used in the literature but also introduces new factors closely involved with fatalities. Dam break cases occurred in China from 1954 to 2013 are summarized, within which twenty-five cases are selected with a comprehensive coverage of geographic position and temporal variation. Twelve impact factors are taken into account as the inputs, i.e., severity of dam break flood (SF), population at risk (PR), public understanding of dam break (UB), warning time (TW), evacuation condition (EC), weather condition during dam break (WB), dam break mode (MB), water storage (SW), building vulnerability (VB), dam break time (TB), average distance from the affected area to the dam (DD) and preventive measures by government (PG).From those, three key factors of SF, MB and TB are chosen. The proposed method is able to extract the key factors, and the derived fatality model performs well in various types of dam break conditions.

  13. Modern landscape processes affecting archaeological sites along the Colorado River corridor downstream of Glen Canyon Dam, Glen Canyon National Recreation Area, Arizona

    Science.gov (United States)

    East, Amy E.; Sankey, Joel B.; Fairley, Helen C.; Caster, Joshua J.; Kasprak, Alan

    2017-08-29

    The landscape of the Colorado River through Glen Canyon National Recreation Area formed over many thousands of years and was modified substantially after the completion of Glen Canyon Dam in 1963. Changes to river flow, sediment supply, channel base level, lateral extent of sedimentary terraces, and vegetation in the post-dam era have modified the river-corridor landscape and have altered the effects of geologic processes that continue to shape the landscape and its cultural resources. The Glen Canyon reach of the Colorado River downstream of Glen Canyon Dam hosts many archaeological sites that are prone to erosion in this changing landscape. This study uses field evaluations from 2016 and aerial photographs from 1952, 1973, 1984, and 1996 to characterize changes in potential windblown sand supply and drainage configuration that have occurred over more than six decades at 54 archaeological sites in Glen Canyon and uppermost Marble Canyon. To assess landscape change at these sites, we use two complementary geomorphic classification systems. The first evaluates the potential for aeolian (windblown) transport of river-derived sand from the active river channel to higher elevation archaeological sites. The second identifies whether rills, gullies, or arroyos (that is, overland drainages that erode the ground surface) exist at the archaeological sites as well as the geomorphic surface, and therefore the relative base level, to which those flow paths drain. Results of these assessments are intended to aid in the management of irreplaceable archaeological resources by the National Park Service and stakeholders of the Glen Canyon Dam Adaptive Management Program.

  14. Hoover Dam Learning Packet.

    Science.gov (United States)

    Bureau of Reclamation (Dept. of Interior), Washington, DC.

    This learning packet provides background information about Hoover Dam (Nevada) and the surrounding area. Since the dam was built at the height of the Depression in 1931, people came from all over the country to work on it. Because of Hoover Dam, the Colorado River was controlled for the first time in history and farmers in Nevada, California, and…

  15. Canadian dam safety conference

    International Nuclear Information System (INIS)

    1991-01-01

    A conference was held on the subject of dam safety in Canada. Sessions concerned assessment of existing dam safety under seismic loading, seismic analysis of concrete and embankment dams, selection of seismic criteria, landslides, risk analysis, and floods. Separate abstracts have been prepared for 24 papers presented at the conference

  16. National dam inventory provides data for analysis

    International Nuclear Information System (INIS)

    Spragens, L.

    1992-01-01

    The Association of State Dam Safety Officials completed a dam inventory this fall. Information on approximately 90,000 state-regulated dams in the US collected during the four-year inventory is being used to build a database managed by the Federal Emergency Management Agency. In addition to ASDSO's work, the federal government conducted an inventory of federal dams. This data will be added to the state information to form one national database. The database will feature 35 data fields for each entry, including the name of the dam, its size, the name of the nearest downstream community, maximum discharge and storage volume, the date of the last inspection, and details about the emergency action plan. The program is an update of the nation's first dam inventory, required by the Dam Safety Act of 1972. The US Army Corps of Engineers completed the original inventory in 1981. The Water Resources Development Act of 1986 authorized appropriations of $2.5 million for the Corps to update the inventory. FEMA and the Corps entered into an agreement for FEMA to undertake the task for the Corps and to coordinate work on both the federal and state inventories. ASDSO compiles existing information on state-regulated dams into a common format for the database, added missing information, and established a process for continually updating data. ASDSO plans to analyze the information collected for the database. It will look at statistics for the number of dams regulated, communities that could be affected, and the number of high-hazard dams. FEMA is preparing reports for Congress on the project. The reports, which are expected to be ready by May 1993, will include information on the methodology used and facts about regulated dams under state jurisdiction

  17. Analysis of the Movement of Sanzhouxi Landslide in Three-Gorges Reservoir, China

    Science.gov (United States)

    Juan, Du; Kunlong, Yin; Yiping, Wu; Lixia, Chen

    2014-05-01

    Since the initial impoundment of the Three Gorges Reservoir in June 2003, a number of new landslides occurred and many dormant landslides were reactivated. Sanzhouxi Landslide located in Wanzhou, the city of Chongqing, 286.9 km west of the Three Gorges Dam and began to deform noticeably after the first impoundment in June 2003. Based on the collection of geological and monitoring data and field investigation, the geological conceptual model was established and the formation mechanism was studied synthetically. Firstly, the intrinsic geological condition, slope structure and material component were analyzed to obtain the geological basis of the landslide formation. Secondly, through the field investigation and analysis of monitoring data, the function of triggering factors, including rainfall and fluctuation of reservoir water level, were discussed. The result indicted that the hydrostatic pressure and buoyancy pressure caused by the rise up of reservoir water level are the main triggering factors for the deformation of landside. Finally, the formation pattern of the landslide was summarized, the formation process is the transition from retrogressive deformation caused by rainfall to the advancing sliding under the action of fluctuation of reservoir water level. The detail formation process is: (1) the top of landslide moved triggered by rainfall, (2) tension cracks occurred in the tongue and middle part of landslide caused by fluctuation of reservoir water level, (3) the tongue and middle part of landslide deformed periodically by the iterative action of rainfall and fluctuation of reservoir water level, (4) the unitive sliding plane formed and the tongue and middle part of landslide moved, (5) the top of landslide slid because of losing bottom supporting.

  18. Mechanics of slide dams

    International Nuclear Information System (INIS)

    Young, G.A.

    1970-01-01

    Studies which promote the use of nuclear energy for peaceful projects in engineering are sponsored by the Atomic Energy Commission under the Plowshare program. Specific projects being considered include the construction of harbors, canals, and dams. Of these projects, perhaps the most difficult to accomplish will be the latter. This paper which is in two parts considers the problems which are associated with the construction of slide dams with nuclear explosives. It examines first the characteristics of conventional earth and rock-fill dams which are based upon proven techniques developed after many years of experience. The characteristics of natural landslide dams are also briefly considered to identify potential problems that must be overcome by slide dam construction techniques. Second, the mechanics of slide dams as determined from small-scale laboratory studies are presented. It is concluded that slide dams can be constructed and that small-scale field tests and additional laboratory studies are justified. (author)

  19. Application of the indirect fluorescent antibody assay in the study of malaria infection in the Yangtze River Three Gorges Reservoir, China

    Directory of Open Access Journals (Sweden)

    Xiang Zheng

    2009-08-01

    Full Text Available Abstract Background China Yangtze Three Gorges Project (TGP is one of the biggest construction projects in the world. The areas around the Three Gorge Dam has a history of tertian malaria and subtertian malaria epidemic, but there are no overall data about malaria epidemics before the completion of the project. The objective of this study was to get a reliable baseline on malaria infection in the Yangtze River Three Gorges reservoir area and to provide reference data for future studies about the impact of the project on malaria epidemics. Methods Two surveys of malaria infection were carried out in area, at six-month intervals in May and October 2008. About 3,600 dual specimens blood film samples for parasite diagnosis and filter paper blood spots for serology (using the immunofluorescence antibody test were collected from the general population, including school populations, whenever possible. Results The overall percentage of positive response of the same population during post-transmission periods was about twice (1.40/0.72 of that in pre-transmission. Positive individuals under 15 years of age were detected in all the localities. Conclusion A certain extent of malaria infection existed in this area. Additional studies are needed to determine the length of malaria experience, and chemotherapeutic intervention as well as the distribution of main vectors for transmission in this area.

  20. The Dams and Monitoring Systems and Case Study: Ataturk and Karakaya Dams

    Science.gov (United States)

    Kalkan, Y.; Bilgi, S.; Gülnerman, A. G.

    2017-12-01

    Dams are among the most important engineering structures used for flood controls, agricultural purposes as well as drinking and hydroelectric power. Especially after the Second World War, developments on the construction technology, increase the construction of larger capacity dams. There are more than 150.000 dams in the world and almost 1000 dams in Turkey, according to international criteria. Although dams provide benefits to humans, they possess structural risks too. To determine the performance of dams on structural safety, assessing the spatial data is very important. These are movement, water pressure, seepage, reservoir and tail-water elevations, local seismic activities, total pressure, stress and strain, internal concrete temperature, ambient temperature and precipitation. These physical data are measured and monitored by the instruments and equipment. Dams and their surroundings have to be monitored by using essential methods at periodic time intervals in order to determine the possible changes that may occur over the time. Monitoring programs typically consist of; surveillance or visual observation. These programs on dams provide information for evaluating the dam's performance related to the design intent and expected changes that could affect the safety performance of the dam. Additionally, these programs are used for investigating and evaluating the abnormal or degrading performance where any remedial action is necessary. Geodetic and non-geodetic methods are used for monitoring. Monitoring the performance of the dams is critical for producing and maintaining the safe dams. This study provides some general information on dams and their different monitoring systems by taking into account two different dams and their structural specifications with the required information. The case study in this paper depends on a comparison of the monitoring surveys on Atatürk Dam and Karakaya Dam, which are constructed on Firat River with two different structural

  1. Tailings dams from the perspective of conventional dam engineering

    International Nuclear Information System (INIS)

    Szymanski, M.B.

    1999-01-01

    A guideline intended for conventional dams such as hydroelectric, water supply, flood control, or irrigation is used sometimes for evaluating the safety of a tailings dam. Differences between tailings dams and conventional dams are often substantial and, as such, should not be overlooked when applying the techniques or safety requirements of conventional dam engineering to tailings dams. Having a dam safety evaluation program developed specifically for tailings dams is essential, if only to reduce the chance of potential errors or omissions that might occur when relying on conventional dam engineering practice. This is not to deny the merits of using the Canadian Dam Safety Association Guidelines (CDSA) and similar conventional dam guidelines for evaluating the safety of tailings dams. Rather it is intended as a warning, and as a rationale underlying basic requirement of tailings dam emgineering: specific experience in tailings dams is essential when applying conventional dam engineering practice. A discussion is included that focuses on the more remarkable tailings dam safety practics. It is not addressed to a technical publications intended for such dams, or significantly different so that the use of conventional dam engineering practice would not be appropriate. The CDSA Guidelines were recently revised to include tailings dams. But incorporating tailings dams into the 1999 revision of the CDSA Guidelines is a first step only - further revision is necessary with respect to tailings dams. 11 refs., 2 tabs

  2. Dam break analysis and flood inundation map of Krisak dam for emergency action plan

    Science.gov (United States)

    Juliastuti, Setyandito, Oki

    2017-11-01

    The Indonesian Regulation which refers to the ICOLD Regulation (International Committee on Large Dam required have the Emergency Action Plan (EAP) guidelines because of the dams have potential failure. In EAP guidelines there is a management of evacuation where the determination of the inundation map based on flood modeling. The purpose of the EAP is to minimize the risk of loss of life and property in downstream which caused by dam failure. This paper will describe about develop flood modeling and inundation map in Krisak dam using numerical methods through dam break analysis (DBA) using hydraulic model Zhong Xing HY-21. The approaches of dam failure simulation are overtopping and piping. Overtopping simulation based on quadrangular, triangular and trapezium fracture. Piping simulation based on cracks of orifice. Using results of DBA, hazard classification of Krisak dam is very high. The nearest village affected dam failure is Singodutan village (distance is 1.45 kilometer from dam) with inundation depth is 1.85 meter. This result can be used by stakeholders such as emergency responders and the community at risk in formulating evacuation procedure.

  3. Nonlinear analysis of concrete gravity dams under normal fault motion

    Directory of Open Access Journals (Sweden)

    Mehdi Alijani Ardeshir

    2016-09-01

    Full Text Available The importance of the seismic behavior of concrete gravity dams in their safety evaluation and stability is inevitable. Many factors affect the prediction of the behavior of concrete dams such as dam-foundation-reservoir interaction, dam and foundation cracking and also displacement due to fault movement that could causes nonlinear behavior. The aim of this study is nonlinear analysis of concrete gravity dams, including displacement caused by normal fault movement in the dam foundation. For this purpose, dam-foundation-reservoir system is modeled using Lagrangian method and analysis of system is done by finite element method. The coordinate smeared crack model based on the nonlinear fracture mechanics is used for crack modeling in the dam body and foundation. Using two separate method including split node technique and contact element, the fault movement are modeled and the position and angle of fault has been studied. To verify the results, dam crest displacement and crack profile in the body of a concrete gravity dam is presented as an example. The results show that low fault movement causes the cracks in the dam body and could be jeopardizes the stability and safety of concrete dam.

  4. Rehabilitation at Olympic Dam

    International Nuclear Information System (INIS)

    Chandler, W.P.; Middleton, B.A.

    1986-01-01

    Rehabilitation work on areas denuded of vegetation during the exploration phase of the Olympic Dam project was used to test various methods for regeneration of vegetation cover in the arid zone. The test work carried out on drill pads and access tracks has indicated that, with adequate site preparation, natural regeneration is the most economical and effective method to ensure post-operational stability of the affected land-forms. An on-going monitoring regime, utilising a computer data base, has been set up to allow year-to-year comparison of rehabilitation effectiveness. The database also provides a catalogue of initial colonising plants and a measure of variations in species diversity with time

  5. Based on records of Three Gorge Telemetric Seismic Network to analyze Vibration process of micro fracture of rock landslide

    Science.gov (United States)

    WANG, Q.

    2017-12-01

    Used the finite element analysis software GeoStudio to establish vibration analysis model of Qianjiangping landslide, which locates at the Three Gorges Reservoir area. In QUAKE/W module, we chosen proper Dynamic elasticity modulus and Poisson's ratio of soil layer and rock stratum. When loading, we selected the waveform data record of Three Gorge Telemetric Seismic Network as input ground motion, which includes five rupture events recorded of Lujiashan seismic station. In dynamic simulating, we mainly focused on sliding process when the earthquake date record was applied. The simulation result shows that Qianjiangping landslide wasn't not only affected by its own static force, but also experienced the dynamic process of micro fracture-creep-slip rupture-creep-slip.it provides a new approach for the early warning feasibility of rock landslide in future research.

  6. Reconstructing the 1935 Columbia River Gorge: A Topographic and Orthophoto Experiment

    Science.gov (United States)

    Fonstad, M. A.; Major, J. H.; O'Connor, J. E.; Dietrich, J. T.

    2017-12-01

    The last decade has seen a revolution in the mapping of rivers and near-river environments. Much of this has been associated with a new type of photogrammetry: structure from motion (SfM) and multi-view stereo techniques. Through SfM, 3D surfaces are reconstructed from nonstructured image groups with poorly calibrated cameras whose locations need not be known. Modern SfM imaging is greatly improved by careful flight planning, well-planned ground control or high-precision direct georeferencing, and well-understood camera optics. The ease of SfM, however, begs the question: how well does it work on archival photos taken without the foreknowledge of SfM techniques? In 1935, the Army Corps of Engineers took over 800 vertical aerial photos for a 160-km-long stretch of the Columbia River Gorge and adjacent areas in Oregon and Washington. These photos pre-date completion of three hydroelectric dams and reservoirs in this reach, and thus provide rich information on the historic pre-dam riverine, geologic, and cultural environments. These photos have little to no metadata associated with them, such as camera calibration reports, so traditional photogrammetry techniques are exceeding difficult to apply. Instead, we apply SfM to these archival photos, and test the resulting digital elevation model (DEM) against lidar data for features inferred to be unchanged in the past 80 years. Few, if any, of the quality controls recommended for SfM are available for these 1935 photos; they are scanned paper positives with little overlap taken with an unknown optical system in high altitude flight paths. Nevertheless, in almost all areas, the SfM analysis produced a high quality orthophoto of the gorge with low horizontal errors - most better than a few meters. The DEM created looks highly realistic, and in many areas has a vertical error of a few meters. However, the vertical errors are spatially inconsistent, with some wildly large, likely because of the many poorly constrained links in

  7. Mercury bioaccumulation in the food web of Three Gorges Reservoir (China): Tempo-spatial patterns and effect of reservoir management

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jun [College of Fisheries, Huazhong Agricultural University, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070 (China); Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070 (China); Zhou, Qiong, E-mail: hainan@mail.hzau.edu.cn [College of Fisheries, Huazhong Agricultural University, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070 (China); Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070 (China); Yuan, Gailing; He, Xugang [College of Fisheries, Huazhong Agricultural University, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070 (China); Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070 (China); Xie, Ping [College of Fisheries, Huazhong Agricultural University, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070 (China); Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072 (China)

    2015-09-15

    Tempo-spatial patterns of mercury bioaccumulation and tropho-dynamics, and the potential for a reservoir effect were evaluated in the Three Gorges Reservoir (TGR, China) from 2011 to 2012, using total mercury concentrations (THg) and stable isotopes (δ{sup 13}C and δ{sup 15}N) of food web components (seston, aquatic invertebrates and fish). Hg concentrations in aquatic invertebrates and fish indicated a significant temporal trend associated with regular seasonal water-level manipulation. This includes water level lowering to allow for storage of water during the wet season (summer); a decrease of water levels from September to June providing a setting for flood storage. Hg concentrations in organisms were the highest after flooding. Higher Hg concentrations in fish were observed at the location farthest from the dam. Hg concentrations in water and sediment were correlated. Compared with the reservoirs of United States and Canada, TGR had lower trophic magnification factors (0.046–0.066), that are explained primarily by organic carbon concentrations in sediment, and the effect of “growth dilution”. Based on comparison before and after the impoundment of TGR, THg concentration in biota did not display an obvious long-term reservoir effect due to (i) short time since inundation, (ii) regular water discharge associated with water-level regulation, and/or (iii) low organic matter content in the sediment. - Highlights: • Hg concentrations were measured in biota of the main stem of 3 Gorges Reservoir. • Fish Hg concentration post-flood period > pre-flood period > flood period. • Fish Hg concentrations were the highest farthest from the dam. • THg in fish 2 years after inundation were the same as before impoundment. • Low biomagnification was ascribed to low DOC content in the sediment.

  8. Design of monitoring and early warning system for geo-hazards in Three Gorges reservoir area using infrasound

    Science.gov (United States)

    Qiu, N.; Zeng, Z. X.; Yang, Y. C.

    2009-04-01

    With the progress of the Three Gorges Dam Project, geological disasters have become increasingly prominent. The reservoir area prone to landslides, collapses, cracks, and earthquake disaster because the complex terrain and geological conditions. It is of significance to monitor and foresee geo-hazards in the reservoir area. Here we introduce our design of monitoring and early warning system for geo-hazards in Three Gorges reservoir area using infrasound. Infrasound may be abnormal during geological disasters, such as debris and earthquake occurred. The formation a d movement of debris flow in its basin will generate infrasound, and spread to the surrounding air medium. Velocity of infrasound is much larger than that of debris flow, so we can monitor and forecast debris flow using infrasound. The sudden vertical displacement brought about by earthquake will generate acoustic-gravity wave which can be observed in distance to monitor earthquake, especially to monitor earthquake precursors. So we try to monitor the geological disasters for the Three Gorges reservoir area in China by design a infrasound array monitor system. This work is supported by Chinese "985 Project". The infrasound monitor system is comprised of two observation stations arranged in Badong county inside the reservoir area and in Wuhan city, respectively. Each station has respectively arranged a kind of augmentable linear array in the form of quasi-uniform linear array and additional amending direction sensors. The linear array comprises eight sensors arranged in several different uniform intervals along a line. The amending direction sensor is situated at certain point in mid-perpendicular of linear array in order to reduce multiplicity in determine the direction of arrival. The sensors used in the system are CDC-2B capacitances infrasonic receiver which can observe frequency ranging 0~20Hz. The, measurement resolution is 750mV/LPa. Infrasonic wave signal collected by sensor is transferred from

  9. TYPOLOGY OF LARGE DAMS. A REVIEW

    Directory of Open Access Journals (Sweden)

    Gheorghe ROMANESCU

    2015-06-01

    Full Text Available The dams represent hydrotechnical constructions meant to ensure a judicious use of water resources. The international literature is extremely rich in data regarding the large dams on Earth. In this context, a hierarchy of the main dams is attempted and the role they play in the economic development of the regions they were built in is underlined. The largest dams are built on the big rivers in Asia, North America, South America and Africa. The reservoirs have multiple roles: electricity production, drinking or industrial water supply, irrigations, recreation, etc. High costs and land fragility do not allow the construction of dams in the places most affected by drought or flood. This is why they are usually built in mountainous areas, at great distance from the populated centres. On the Romanian territory, there are 246 large dams, built in the hydrographical basins of Siret, Olt, Arges, Somes, etc. The largest rivers on Earth, by discharge, (Amazon and Zair do not also include the largest dams because the landform and the type of flow have not allowed such constructions.

  10. Arthropod diversity and abundance along the Kihansi Gorge ...

    African Journals Online (AJOL)

    Arthropod diversity and abundance at the order level was investigated along the Kihansi Gorge in the southern Udzungwa Mountains between June and August 1997 by using sweep netting, timed Lepidoptera counts, malaise-traps, solar powered light-¬traps, baited pitfall-traps, sticky-traps and baited butterfly traps.

  11. Diversity of macrofungal community in Bifeng Gorge: the core giant ...

    African Journals Online (AJOL)

    Macrofungi not only play an important role in pollution control and other environmental protection measures, but also an important resource in food and pharmaceutical industries. However, the diversity of the macrofungal community in the core habitat of the giant panda in Bifeng Gorge, China is still inadequate. In the ...

  12. Rare birds of prey observations in Kresna Gorge in Bulgaria

    African Journals Online (AJOL)

    Campbell Murn

    Greater Spotted Eagle. Aquila clanga was observed over the feeding site in Kresna Gorge interacting with Griffon Vultures and. Ravens in flight on 30 Mar 2010. This is the first record of the species from the area. Lanner Falcon. Falco biarmicus feldegii. A territorial single adult bird (most probably female) was frequently.

  13. Multi-Objective Sustainable Operation of the Three Gorges Cascaded Hydropower System Using Multi-Swarm Comprehensive Learning Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Xiang Yu

    2016-06-01

    Full Text Available Optimal operation of hydropower reservoir systems often needs to optimize multiple conflicting objectives simultaneously. The conflicting objectives result in a Pareto front, which is a set of non-dominated solutions. Non-dominated solutions cannot outperform each other on all the objectives. An optimization framework based on the multi-swarm comprehensive learning particle swarm optimization algorithm is proposed to solve the multi-objective operation of hydropower reservoir systems. Through adopting search techniques such as decomposition, mutation and differential evolution, the algorithm tries to derive multiple non-dominated solutions reasonably distributed over the true Pareto front in one single run, thereby facilitating determining the final tradeoff. The long-term sustainable planning of the Three Gorges cascaded hydropower system consisting of the Three Gorges Dam and Gezhouba Dam located on the Yangtze River in China is studied. Two conflicting objectives, i.e., maximizing hydropower generation and minimizing deviation from the outflow lower target to realize the system’s economic, environmental and social benefits during the drought season, are optimized simultaneously. Experimental results demonstrate that the optimization framework helps to robustly derive multiple feasible non-dominated solutions with satisfactory convergence, diversity and extremity in one single run for the case studied.

  14. Dams: Pros and Cons

    African Journals Online (AJOL)

    Steve

    Many Dams have been constructed in different parts of the world and for different purposes. While these dams have in most cases served the reason for their construction, the resultant environmental impact have been a subject of concern. The creation of a reservoir not only changes the ecology and hydrology of the ...

  15. Inner gorges cut by subglacial meltwater during Fennoscandian ice sheet decay

    Science.gov (United States)

    Jansen, J. D.; Codilean, A. T.; Stroeven, A. P.; Fabel, D.; Hättestrand, C.; Kleman, J.; Harbor, J. M.; Heyman, J.; Kubik, P. W.; Xu, S.

    2014-05-01

    The century-long debate over the origins of inner gorges that were repeatedly covered by Quaternary glaciers hinges upon whether the gorges are fluvial forms eroded by subaerial rivers, or subglacial forms cut beneath ice. Here we apply cosmogenic nuclide exposure dating to seven inner gorges along ~500 km of the former Fennoscandian ice sheet margin in combination with a new deglaciation map. We show that the timing of exposure matches the advent of ice-free conditions, strongly suggesting that gorges were cut by channelized subglacial meltwater while simultaneously being shielded from cosmic rays by overlying ice. Given the exceptional hydraulic efficiency required for meltwater channels to erode bedrock and evacuate debris, we deduce that inner gorges are the product of ice sheets undergoing intense surface melting. The lack of postglacial river erosion in our seven gorges implicates subglacial meltwater as a key driver of valley deepening on the Baltic Shield over multiple glacial cycles.

  16. Tailings dams safety - implications for the dam safety community

    International Nuclear Information System (INIS)

    Vick, S.G.

    1999-01-01

    In the context of the impact of privatization and globalization on traditional dam safety practice and the Canadian experience of the environmental dimension of dam failures, various aspects of tailings dam safety have much to offer the wider dam safety community. General design principles for tailings dams are not described, rather an attempt is made to frame some contemporary issues of tailings dam safety in ways that bring out their relevance in a broader dam safety context. Lessons applicable to future dam safety practice in related areas are examined, and the dam safety traditions of the mining, hydroelectric and related industries in Canada are brought together by illustrating some of the common elements and concerns they share. It is becoming evident that future dam safety activities for the hydroelectric, water supply and related dams will be carried out in a more privatized and globalized context by organizations less acquainted with traditional dam safety practices than in the past. If so, then tailings dam experience can be a pathfinder for how and why dam safety needs to be addressed in a corporate setting. It shows that the perceived effects of dam failures, environmental and otherwise, influence corporate damowners in ways that can amplify manyfold the objective consequences that dam safety assessments usually address. Dam safety professionals might do well to better understand and effectively communicate the financial and organizational impacts of dam failure on the corporate entity in ways that go beyond the traditional assessment of downstream hazard and failure consequences. Dam safety efforts can come to be seen less as imposed burdens of dam ownership and more as activities consistent with shareholder accountability and corporate self-interest. The Canadian mining industry, in adopting this perspective, is confirming that support for dam safety activities from the highest corporate level is essential for implementing them throughout the

  17. Fluvial response to Holocene volcanic damming and breaching in the Gediz and Geren rivers, western Turkey

    Science.gov (United States)

    van Gorp, W.; Veldkamp, A.; Temme, A. J. A. M.; Maddy, D.; Demir, T.; van der Schriek, T.; Reimann, T.; Wallinga, J.; Wijbrans, J.; Schoorl, J. M.

    2013-11-01

    This study discusses the complex late Holocene evolution of the Gediz River north of Kula, western Turkey, when a basaltic lava flow dammed and filled this river valley. Age control was obtained using established and novel feldspar luminescence techniques on fluvial sands below and on top of the flow. This dating constrained the age of the lava flow to 3.0-2.6 ka. Two damming locations caused by the lava flow have been investigated. The upstream dam caused lake formation and siltation of the upstream Gediz. The downstream dam blocked both the Gediz and a tributary river, the Geren. The associated lake was not silted up because the upstream dam already trapped all the Gediz sediments. Backfillings of the downstream lake are found 1.5 km upstream into the Geren valley. The downstream dam breached first, after which the upstream dam breached creating an outburst flood that imbricated boulders of 10 m3 size and created an epigenetic gorge. The Gediz has lowered its floodplain level at least 15 m since the time of damming, triggering landslides, some of which are active until present. The lower reach of the Geren has experienced fast base level lowering and changed regime from meandering to a straight channel. Complex response to base level change is still ongoing in the Geren and Gediz catchments. These findings are summarized in a diagram conceptualizing lava damming and breaching events. This study demonstrates that one lava flow filling a valley floor can block a river at several locations, leading to different but interrelated fluvial responses of the same river system to the same lava flow.

  18. Olduvai Gorge, Shaded Relief and Colored Height

    Science.gov (United States)

    2004-01-01

    Three striking and important areas of Tanzania in eastern Africa are shown in this color-coded shaded relief image from the Shuttle Radar Topography Mission. The largest circular feature in the center right is the caldera, or central crater, of the extinct volcano Ngorongoro. It is surrounded by a number of smaller volcanoes, all associated with the Great Rift Valley, a geologic fault system that extends for about 4,830 kilometers (2,995 miles) from Syria to central Mozambique. Ngorongoro's caldera is 22.5 kilometers (14 miles) across at its widest point and is 610 meters (2,000 feet) deep. Its floor is very level, holding a lake fed by streams running down the caldera wall. It is part of the Ngorongoro Conservation Area and is home to over 75,000 animals. The lakes south of the crater are Lake Eyasi and Lake Manyara, also part of the conservation area. The relatively smooth region in the upper left of the image is the Serengeti National Park, the largest in Tanzania. The park encompasses the main part of the Serengeti ecosystem, supporting the greatest remaining concentration of plains game in Africa including more than 3,000,000 large mammals. The animals roam the park freely and in the spectacular migrations, huge herds of wild animals move to other areas of the park in search of greener grazing grounds (requiring over 4,000 tons of grass each day) and water. The faint, nearly horizontal line near the center of the image is Olduvai Gorge, made famous by the discovery of remains of the earliest humans to exist. Between 1.9 and 1.2 million years ago a salt lake occupied this area, followed by the appearance of fresh water streams and small ponds. Exposed deposits show rich fossil fauna, many hominid remains and items belonging to one of the oldest stone tool technologies, called Olduwan. The time span of the objects recovered dates from 2,100,000 to 15,000 years ago. Two visualization methods were combined to produce the image: shading and color coding of

  19. Does damming of the Colorado River affect the nursery area of blue shrimp Litopenaeus stylirostris (Decapoda: Penaeidae in the Upper Gulf of California?

    Directory of Open Access Journals (Sweden)

    Eugenio Alberto Aragón-Noriega

    2000-12-01

    Full Text Available After damming the Colorado River the freshwater flow was reduced to 1 % of its virgin flow to the Upper Gulf of California (UGC. The ecological effects need to be properly documented. The UGC is the nursery area for Litopenaeus stylirostris, the most profitable fishery in the zone. In order to know the relative abundance of L. stylirostris postlarval stage we conducted a sampled survey every 14 days in 1993, 1994 and 1997, plus an intensive sampling during a complete tide cycle in July 1995 and 1996. We did 10 min trawls each hour during the flood tide. Relative abundance of postlarvae was higher (pEl represamiento del Río Colorado ha ocasionado que el flujo de agua dulce sobre el Alto Golfo de California (AGC se haya reducido hasta el 1 % del flujo original. Se ha documentado el efecto de la reducción de agua dulce sobre las condiciones hidrográficas del AGC, pero las repercusiones ecológicas no se han descrito apropiadamente. El AGC ha sido área de crianza para especies comerciales como el camarón Litopenaeus stylirostris. Se hicieron recolectas de postlarvas de L. stylirostris en el AGC durante cinco años consecutivos. Los muestreos fueron catorcenalmente en los años de 1993, 1994 y 1997 y se realizó una recolecta diaria durante 15 días consecutivos en los años 1995 y 1996. Para ello se arrastró una red de plancton de 505 µ durante 10 min cada hora durante el flujo de marea. La abundancia relativa de las postlarvas de camarón en esta zona viaria considerablemente en años cuando el flujo de agua dulce incrementa. La abundancia es mayor hasta en un 200 % (p < 0.05 cuando existe descarga de agua dulce al AGC.

  20. Dam safety operating guidelines

    International Nuclear Information System (INIS)

    Elsayed, E.; Leung, T.; Kirkham, A.; Lum, D.

    1990-01-01

    As part of Ontario Hydro's dam structure assessment program, the hydraulic design review of several river systems has revealed that many existing dam sites, under current operating procedures, would not have sufficient discharge capacity to pass the Inflow Design Flood (IDF) without compromising the integrity of the associated structures. Typical mitigative measures usually considered in dealing with these dam sites include structural alterations, emergency action plans and/or special operating procedures designed for extreme floods. A pilot study was carried out for the Madawaska River system in eastern Ontario, which has seven Ontario Hydro dam sites in series, to develop and evaluate the effectiveness of the Dam Safety Operating Guidelines (DSOG). The DSOG consist of two components: the flood routing schedules and the minimum discharge schedules, the former of which would apply in the case of severe spring flood conditions when the maximum observed snowpack water content and the forecast rainfall depth exceed threshold values. The flood routing schedules would identify to the operator the optimal timing and/or extent of utilizing the discharge facilities at each dam site to minimize the potential for dam failures cased by overtopping anywhere in the system. It was found that the DSOG reduced the number of structures overtopped during probable maximum flood from thirteen to four, while the number of structures that could fail would be reduced from seven to two. 8 refs., 4 figs., 3 tabs

  1. Assessment of dam effects on streams and fish assemblages of the conterminous USA.

    Science.gov (United States)

    Cooper, Arthur R; Infante, Dana M; Daniel, Wesley M; Wehrly, Kevin E; Wang, Lizhu; Brenden, Travis O

    2017-05-15

    Despite the prevalence of damming as a global disturbance to river habitats, detailed reach-based assessments of the ecological effects of dams are lacking, particularly across large spatial extents. Using data from nearly 50,000 large dams, we assessed stream network fragmentation and flow alteration by large dams for streams of the conterminous USA. We developed 21 dam metrics characterizing a diversity of dam influences operating at both localized (e.g., distances-to-dams) and landscape scales (e.g., cumulative reservoir storage throughout stream networks) for every stream reach in the study region. We further evaluated how dams have affected stream fish assemblages within large ecoregions using more than 37,000 stream fish samples. Streams have been severely fragmented by large dams, with the number of stream segments increasing by 801% compared to free-flowing streams in the absence of dams and a staggering 79% of stream length is disconnected from their outlet (i.e., oceans and Great Lakes). Flow alteration metrics demonstrate a landscape-scale disturbance of dams, resulting in total upstream reservoir storage volumes exceeding estimated annual discharge volumes of many of the nation's largest rivers. Further, we show large-scale changes in fish assemblages with dams. Species adapted to lentic habitats increase with dams across the conterminous USA, while rheophils, lithophils, and intolerant fishes decrease with dams. Overall, fragmentation and flow alteration by dams have affected fish assemblages as much or more than other anthropogenic stressors, with dam effects generally increasing with stream size. Dam-induced stream fragmentation and flow alteration are critical natural resource issues. This study emphasizes the importance of considering dams as a landscape-scale disturbance to river habitats along with the need to assess differential effects that dams may have on river habitats and the fishes they support. Together, these insights are essential for

  2. Chemical quality and temperature of water in Flaming Gorge Reservoir, Wyoming and Utah, and the effect of the reservoir on the Green River

    Science.gov (United States)

    Bolke, E.L.; Waddell, Kidd M.

    1975-01-01

    The major tributaries to Flaming Gorge Reservoir contribute an average of about 97 percent of the total streamflow and 82 percent of the total load of dissolved solids. The Green River is the largest tributary, and for the 1957-72 water years it contributed 81 percent of the total streamflow and 70 percent of the total load of dissolved solids. The principal constituents in the tributary streamflow are calcium and sulfate during periods of lowest flow and calcium and bicarbonate during periods of highest flow.Flaming Gorge Dam was closed in November 1962, and the most significant load changes of chemical constituents due to the net effect of inflow, outflow, leaching, and chemical precipitation in the reservoir have been load changes of sulfate and bicarbonate. The average increase of dissolved load of sulfate in the reservoir for the 1969-72 water years was 110,000 tons (99,790 t) per year, which was 40,000 tons (36,287 t) per year less than for the 1963-66 water years. The average decrease of dissolved load of bicarbonate in the reservoir for 1969-72 was 40,000 tons (36,287 t) per year, which was the same as the decrease for 1963-66.Anaerobic conditions were observed in the deep, uncirculated part of the reservoir near the dam during the 1971 and 1972 water years, and anaerobic or near-anaerobic conditions were observed near the confluence of the Blacks Fork and Green River during the summers of 1971 and 1972.The water in Flaming Gorge Reservoir is in three distinct layers, and the upper two layers (the epilimnion and the metalimnion) mixed twice during each of the 1971-72 water years. The two circulation periods were in the spring and fall. The water in the deepest layer (the hypolimnion) did not mix with the waters of the upper zones because the density difference was too great and because the deep, narrow shape of the basin probably inhibits mixing.The depletion of flow in the Green River downstream from Flaming Gorge Dam between closure of the dam and the end

  3. Chemical quality of surface water in the Flaming Gorge Reservoir area, Wyoming and Utah

    Science.gov (United States)

    Madison, R.J.; Waddell, Kidd M.

    1973-01-01

    Construction of Flaming Gorge Dam on the Green River by the U.S. Bureau of Reclamation started in 1959, and storage began in November 1962. A reconnaissance study was made during the period 1966-68 to determine the effects of the reservoir on the chemical quality of the effluent water and to describe the quality of the impounded water and inflowing water.The major inflow to the reservoir is from the Green River, which contributes an average of 81 percent of the water and 59 percent of the inflow load of dissolved solids. Together, Blacks Fork and Henrys Fork contribute an average of about 16 percent of the water and about 23 percent of the dissolved-solids load, whereas minor tributaries contribute approximately 3 percent of the total inflow water to the reservoir, but about 18 percent of the total incoming load of dissolved solids.The concentration of dissolved solids in the reservoir in October 1966 was about 150 mg/l (milligrams per liter) greater than the concentration of the 1962-66 inflow and in September 1968 about 95 mg/l greater than the concentration of the 1962-68 inflow. The increased concentration is due. mostly to leaching of minerals from the reservoir bottom. For the 1963-68 water years, about 1.2 million tons of dissolved solids was leached from inundated areas. The major observable difference between the chemical composition of the inflow during 1963-66 and that of the reservoir in 1966 is an increase in the percentage of sulfate and a decrease in the percentage of bicarbonate. Impoundment of water in Flaming Gorge Reservoir during the 1963-68 water years caused the concentration of dissolved solids in the river system to increase by 130 mg/l, or about 32 percent over what would have occurred without the reservoir. Evaporation accounted for an increase of 15 mg/l, and leaching accounted for an increase of 115 mg/l.

  4. Allegheny County Dam Locations

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset shows the point locations of dams in Allegheny County. If viewing this description on the Western Pennsylvania Regional Data Center’s open data portal...

  5. Revisiting the homogenization of dammed rivers in the southeastern US

    Science.gov (United States)

    Ryan A. McManamay; Donald J. Orth; Charles A. Dolloff

    2012-01-01

    For some time, ecologists have attempted to make generalizations concerning how disturbances influence natural ecosystems, especially river systems. The existing literature suggests that dams homogenize the hydrologic variability of rivers. However, this might insinuate that dams affect river systems similarly despite a large gradient in natural hydrologic character....

  6. Impacts of large dams on the complexity of suspended sediment dynamics in the Yangtze River

    Science.gov (United States)

    Wang, Yuankun; Rhoads, Bruce L.; Wang, Dong; Wu, Jichun; Zhang, Xiao

    2018-03-01

    The Yangtze River is one of the largest and most important rivers in the world. Over the past several decades, the natural sediment regime of the Yangtze River has been altered by the construction of dams. This paper uses multi-scale entropy analysis to ascertain the impacts of large dams on the complexity of high-frequency suspended sediment dynamics in the Yangtze River system, especially after impoundment of the Three Gorges Dam (TGD). In this study, the complexity of sediment dynamics is quantified by framing it within the context of entropy analysis of time series. Data on daily sediment loads for four stations located in the mainstem are analyzed for the past 60 years. The results indicate that dam construction has reduced the complexity of short-term (1-30 days) variation in sediment dynamics near the structures, but that complexity has actually increased farther downstream. This spatial pattern seems to reflect a filtering effect of the dams on the on the temporal pattern of sediment loads as well as decreased longitudinal connectivity of sediment transfer through the river system, resulting in downstream enhancement of the influence of local sediment inputs by tributaries on sediment dynamics. The TGD has had a substantial impact on the complexity of sediment series in the mainstem of the Yangtze River, especially after it became fully operational. This enhanced impact is attributed to the high trapping efficiency of this dam and its associated large reservoir. The sediment dynamics "signal" becomes more spatially variable after dam construction. This study demonstrates the spatial influence of dams on the high-frequency temporal complexity of sediment regimes and provides valuable information that can be used to guide environmental conservation of the Yangtze River.

  7. Assessing internal biophysical vulnerability to landslide hazards - a nested catchment approach: Xiangxi Watershed / Three Gorges Reservoir

    Science.gov (United States)

    Wiegand, Matthias; Seeber, Christoph; Hartmann, Heike; Xiang, Wei; King, Lorenz

    2010-05-01

    The Three Gorges dam construction was completed in 2006. Besides the international media, also the responsible authorities and various scholarly communities pay close attention to potential and actual environmental impacts related to the impoundment and development activities. The geo-environment within the Three Gorges region is highly conducive to landslides. Consequently, a scientific monitoring and risk mitigation system was established and is still under development. Risk analysis with regard to gravity driven mass movements is highly complex and strongly site specific - several aspects hamper a universal methodology applicable for landslide risk and site assessment. The interdisciplinary Sino-German Yangtze-Project Research co-operation aims, among others, to support the sustainable cultivation of the newly developed ecosystems within the Yangtze catchments. Land use change and increasing population growth are causing severe pressure on the scarce land resources. Landslides are acknowledged as important threat, hence vulnerability of certain landscape components have to be identified, quantified and monitored. A nested quantitative approach for vulnerability analysis is developed. The applied risk and vulnerability model understands risk as the product of hazard and vulnerability. Whereas vulnerability is characterized by: mass movement intensity and susceptibility of the respective element at risk. The watershed of Xiangxi river serves as study area. In general, catchment approaches intent and proved to be a functional geographical unit for successful integrated resources management. Several limitations with regard to data accessibility, availability and accuracy have to be considered due to restrictions of feasible scales. Comprehensive large-scale site investigations are confined to training areas for model calibration and validation. Remote sensing potentials are utilised for land use/ land cover change analysis and localization of selected elements

  8. The attitude of Czech dental patients to the use of rubber dam.

    Science.gov (United States)

    Kapitan, Martin; Hodacova, Lenka; Jagelska, Julie; Kaplan, Jiri; Ivancakova, Romana; Sustova, Zdenka

    2015-10-01

    The most frequent arguments against rubber dam are that patients generally do not like it and the prolonged time of treatment. However, according to several studies, the attitude of patients towards rubber dam is rather positive. To find out the attitudes of patients to treatment with rubber dam; to determine influence of the circumstances of treatment or factors about patients; and to establish a mean time needed for rubber dam placement. A questionnaire survey. Patients of general dental practitioners, university clinical specialists and undergraduate dental students. A total of 179 questionnaires were distributed, from which 150 were returned. The mean time needed for rubber dam placement was 4 min for students and dam. A total of 77% of patients indicated a higher level of comfort during treatment with rubber dam. A preference to the future rubber dam usage was indicated by 86% of patients. The preference to the further rubber dam usage was statistically significantly affected by the level of comfort during the treatment with rubber dam (P dam usage (P dam usage. The attitude of patients to rubber dam was rather positive in our study. The time needed for rubber dam application was rather short. © 2013 John Wiley & Sons Ltd.

  9. Yangtze Three Gorges Reservoir, China: A holistic assessment of organic pollution, mutagenic effects of sediments and genotoxic impacts on fish.

    Science.gov (United States)

    Floehr, Tilman; Scholz-Starke, Björn; Xiao, Hongxia; Koch, Josef; Wu, Lingling; Hou, Junli; Wolf, Anja; Bergmann, Axel; Bluhm, Kerstin; Yuan, Xingzhong; Roß-Nickoll, Martina; Schäffer, Andreas; Hollert, Henner

    2015-12-01

    Besides obvious benefits, the Three Gorges Dam's construction resulted in new pollution scenarios with the potentials to threaten the Three Gorges Reservoir (TGR) ecosystem. In order to record organic contamination, to find links to ecotoxicological impacts and to serve as reference for ensuing monitoring, several sites in the TGR area were screened applying the triad approach with additional lines-of-evidence as a holistic assessment method. Sediments and the benthic fish species Pelteobagrus vachellii were sampled in 2011 and 2012 to determine organic pollution levels, mutagenic potentials and genotoxic impacts. Two regional hot-spots near the cities of Chongqing and Kaixian were identified and further investigated in 2013. Only polycyclic aromatic hydrocarbons (PAHs) could be detected in sediments in 2011 (165-1653ng/g), emphasizing their roles as key pollutants of the area. Their ubiquity was confirmed at Chongqing (150-433ng/g) and Kaixian (127-590ng/g) in 2013. Concentrations were comparable to other major Chinese and German rivers. However, the immense sediment influx suggested a deposition of 216-636kgPAH/day (0.2-0.6mgPAH/(m(2)·day)), indicating an ecotoxicological risk. PAH source analysis highlighted primary impacts of combustion sources on the more industrialized upper TGR section, whereas petrogenic sources dominated the mid-low section. Furthermore, sediment extracts from several sites exhibited significant activities of frameshift promutagens in the Ames fluctuation assay. Additionally, significant genotoxic impairments in erythrocytes of P. vachellii were detected (Chongqing/Kaixian), demonstrating the relevance of genotoxicity as an important mode of action in the TGR's fish. PAHs, their derivatives and non-target compounds are considered as main causative agents. Copyright © 2015. Published by Elsevier B.V.

  10. Monitoring the Dynamic of a Fluvial Channel after Lahar Disturbance: Huiloac Gorge (Popocatepetl Volcano, Mexico)

    Science.gov (United States)

    Andres, N.; Palacios, D.; Zamorano, J. J.; Tanarro, L. M.; Renschler, C.; Sanjosé, J. J.; Atkinson, A.

    2009-04-01

    Volcanic eruptions generate disturbances that affect hydrological systems (Major, 2003) by depositing large volumes of sediments in watersheds that exceed amounts common to non-volcanic river systems (Montgomery, 2005). If the eruption releases abundant melt water, the river system may respond immediately by forming hazardous flows called lahars. River system recovery following eruptive and laharic impact is an important process, but it has received little attention (Gran and Montgomery, 2005) despite the fact that Major et al. (2000) and Hayes et al. (2002) have shown that these disruptions cause long term instability and their effects persist for decades. Lahar deposits resulting from interaction between volcanic activity and the glacier located above the Huiloac Gorge on the northern slope of Popocatepetl volcano (19°02´ N, 98°62´ W, 5,424 m), have infilled the gorge (Palacios, 1995; Palacios et al., 1998 and 2001; Capra et al., 2004; Muñoz, 2007). All of the major lahars that occurred on the volcano in 1995 (4 km), 1997 (21 km), and 2001 (14 km) have channelled through Huiloac Gorge, and have dramatically altered its morphology and dynamics through erosion and deposition. The present study traces these changes in the aftermath of the laharic events that occurred from 1997-2001. A sector of the channel, located at 3200m-3240m altitude, of 500 m long and 15 to 20 m wide, in the mid-section of the gorge, was chosen as the control site. Precipitation is heaviest there and is most apt to trigger secondary post-eruptive lahars. ArcGis software was used to draw 6 geomorphic maps of the site showing spatial variations in the landforms for the period February 2002 - February 2008. In addition, 29 cross-profiles were made of the gorge for the same time interval, excluding February 2004. The volume of sediment eroded and deposited was calculated for each date by comparing variations in the height of the floor and banks of the gorge depicted in the cross-profile, and

  11. Dam safety guidelines

    International Nuclear Information System (INIS)

    Anderson, I.; Raska, C.

    1999-01-01

    The objectives of this report are (1) to define the requirements and outline the guidelines so that the safety of existing dams can be investigated and identified in a consistent and adequate manner across Canada, (2) to enable the consistent evaluation of dam safety deficiencies leading to the construction of improvements which contribute to dam safety, and (3) to provide a basis for dam safety legislation and regulation. The document contains statements of safety requirements, explanatory guidelines and commentaries. These clarify and expand upon some of the requirements and guidelines, and discuss alternative approaches to meeting the safety requirements. The report is divided into 12 sections which address criteria for earthquakes, floods and emergency preparedness. Geotechnical considerations and the effects of the reservoir environment are also discussed. These guidelines are not intended as design specifications for dam safety evaluation, design, construction or rehabilitation. From time to time, portions of these guidelines will be updated and issued to CDSA members. The user is responsible for ensuring that the most up-to-date version is being used. refs, tabs

  12. Dams and Intergovernmental Transfers

    Science.gov (United States)

    Bao, X.

    2012-12-01

    Gainers and Losers are always associated with large scale hydrological infrastructure construction, such as dams, canals and water treatment facilities. Since most of these projects are public services and public goods, Some of these uneven impacts cannot fully be solved by markets. This paper tried to explore whether the governments are paying any effort to balance the uneven distributional impacts caused by dam construction or not. It showed that dam construction brought an average 2% decrease in per capita tax revenue in the upstream counties, a 30% increase in the dam-location counties and an insignificant increase in downstream counties. Similar distributional impacts were observed for other outcome variables. like rural income and agricultural crop yields, though the impacts differ across different crops. The paper also found some balancing efforts from inter-governmental transfers to reduce the unevenly distributed impacts caused by dam construction. However, overall the inter-governmental fiscal transfer efforts were not large enough to fully correct those uneven distributions, reflected from a 2% decrease of per capita GDP in upstream counties and increase of per capita GDP in local and downstream counties. This paper may shed some lights on the governmental considerations in the decision making process for large hydrological infrastructures.

  13. Impact of socioeconomic and meteorological factors on reservoirs' air quality: a case in the Three Gorges Reservoir of Chongqing (TGRC), China over a 10-year period.

    Science.gov (United States)

    Peng, Ying; Zhou, Fengwu; Cui, Jian; Du, Ke; Leng, Qiangmei; Yang, Fumo; Chan, Andy; Zhao, Hongting

    2017-07-01

    The Three Gorges Dam's construction and industrial transfer have resulted in a new air pollution pattern with the potential to threaten the reservoir eco-environment. To assess the impact of socioeconomic factors on the pattern of air quality vairation and economical risks, concentrations of SO 2 , NO 2 , and PM 10 , industry genres, and meteorological conditions were selected in the Three Gorges Reservoir of Chongqing (TGRC) during 2006-2015. Results showed that air quality had improved to some extent, but atmospheric NO 2 showed an increased trend during 2011-2015. Spatially, higher atmospheric NO 2 extended to the surrounding area. The primary industry, especially for agriculture, had shown to be responsible for the remarkable increase of atmospheric NO 2 (p air pollutant reductions, but construction industries had inhibited the improvement of regional air quality. In the tertiary industry, the cargo industry at ports had significantly decreased atmospheric NO 2 as a result of eliminating the obsoleted small ships. Contrarily, the highway transportation had brought more air pollutants. The relative humidity was shown to be the main meteorological factor, which had an extremely remarkable relation with atmospheric SO 2 (p air quality improvement difficult, and atmospheric SO 2 , NO 2 , and PM 10 deposition would aggravate regional soil and water acidification and reactivate heavy metal in soil and sediment, further to pose a high level of ecological risk in the TGRC and other countries with reservoirs in the world.

  14. Responses of spatial-temporal dynamics of bacterioplankton community to large-scale reservoir operation: a case study in the Three Gorges Reservoir, China.

    Science.gov (United States)

    Li, Zhe; Lu, Lunhui; Guo, Jinsong; Yang, Jixiang; Zhang, Jiachao; He, Bin; Xu, Linlin

    2017-02-13

    Large rivers are commonly regulated by damming, yet the effects of such disruption on bacterioplankton community structures have not been adequately studied. The aim of this study was to explore the biogeographical patterns present under dam regulation and to uncover the major drivers structuring bacterioplankton communities. Bacterioplankton assemblages in the Three Gorges Reservoir (TGR) were analyzed using Illumina Miseq sequencing by comparing seven sites located within the TGR before and after impoundment. This approach revealed ecological and spatial-temporal variations in bacterioplankton community composition along the longitudinal axis. The community was dynamic and dominated by Proteobacteria and Actinobacteria phyla, encompassing 39.26% and 37.14% of all sequences, respectively, followed by Bacteroidetes (8.67%) and Cyanobacteria (3.90%). The Shannon-Wiener index of the bacterioplankton community in the flood season (August) was generally higher than that in the impoundment season (November). Principal Component Analysis of the bacterioplankton community compositions showed separation between different seasons and sampling sites. Results of the relationship between bacterioplankton community compositions and environmental variables highlighted that ecological processes of element cycling and large dam disturbances are of prime importance in driving the assemblages of riverine bacterioplankton communities.

  15. Dating the Naisiusiu Beds, Olduvai Gorge, by electron spin resonance

    Science.gov (United States)

    Skinner, A. R.; Hay, R. L.; Masao, F.; Blackwell, B. A. B.

    2003-05-01

    The lower beds at Olduvai Gorge are well known for containing early hominid fossils and Oldowan stone tools, and their ages have been established by 40Ar/ 39Ar dating and paleomagnetic stratigraphy. Ages are generally less certain for the upper deposits at Olduvai Gorge because of the scarcity of datable tuffs. The youngest archaeologically significant site at Olduvai is microlithic LSA, which lies in the type section of the Naisiusiu Beds. The age for the site is controversial, with 14C dates of 17,000-17,550 (Hay, R.L., 1976 Geology of Olduvai Gorge, University of California Press, Berkeley) and >42,000 BP (Manega, P.C., 1993. Geochronology, geochemistry, and isotopic study of the Plio-Pleistocene Hominid sites and the Ngorongoro Volcanic Highland in Northern Tanzania. Unpublished Ph.D. Thesis, University of Colorado, Boulder, CO). The tuff bed in the zone with artifacts does not contain materials datable by 40Ar/ 39Ar, and some other dating method was needed. In the summer of 2001, five equid teeth were collected from the type Naisiusiu site. Another tooth had previously been collected. ESR ages have been determined for three teeth from the archaeological level and their ages cluster around 62±5 ka, assuming linear uranium uptake. Another tooth from a level without artifacts and believed to be significantly younger dated to 39±5 ka, again assuming LU. These dates are considerably older than previous estimates and suggest that the East African MSA/LSA transition occurred very early.

  16. Small dams need better management

    Science.gov (United States)

    Balcerak, Ernie

    2012-03-01

    Many small dams around the world are poorly maintained and represent a safety hazard, according to Pisaniello et al. Better oversight of small dams is needed, the authors argue. The researchers reviewed literature, conducted case studies in four states in Australia, and developed policy benchmarks and best practices for small-dam management. Small dams, often just several meters high and typically privately owned by individual farmers, have historically caused major damage when they fail. For instance, in China in 1975, 230,000 people died when two large dams failed because of the cumulative failure of 60 smaller upstream dams. In the United States, in 1977 the 8-meter-high Kelly Barnes Lake dam failed, killing 39 people. Many other small-dam failures around the world have resulted in casualties and severe ecological and economic damage.

  17. Dam health diagnosis and evaluation

    Science.gov (United States)

    Wu, Zhongru; Su, Huaizhi

    2005-06-01

    Based on the bionics principle in the life sciences field, we regard a dam as a vital and intelligent system. A bionics model is constructed to observe, diagnose and evaluate dam health. The model is composed of a sensing system (nerve), central processing unit (cerebrum) and decision-making implement (organism). In addition, the model, index system and engineering method on dam health assessment are presented. The proposed theories and methods are applied to evaluate dynamically the health of one concrete dam.

  18. Introduction of an Emergency Response Plan for flood loading of Sultan Abu Bakar Dam in Malaysia

    Science.gov (United States)

    Said, N. F. Md; Sidek, L. M.; Basri, H.; Muda, R. S.; Razad, A. Z. Abdul

    2016-03-01

    Sultan Abu Bakar Dam Emergency Response Plan (ERP) is designed to assist employees for identifying, monitoring, responding and mitigation dam safety emergencies. This paper is outlined to identification of an organization chart, responsibility for emergency management team and triggering level in Sultan Abu Bakar Dam ERP. ERP is a plan that guides responsibilities for proper operation of Sultan Abu Bakar Dam in respond to emergency incidents affecting the dam. Based on this study four major responsibilities are needed for Abu Bakar Dam owing to protect any probable risk for downstream which they can be Incident Commander, Deputy Incident Commander, On-Scene Commander, Civil Engineer. In conclusion, having organization charts based on ERP studies can be helpful for decreasing the probable risks in any projects such as Abu Bakar Dam and it is a way to identify and suspected and actual dam safety emergencies.

  19. Proceedings of dam safety seminar

    International Nuclear Information System (INIS)

    1989-01-01

    A seminar was held to discuss issues of dam safety. Presentations concerned dam safety evaluation, dam monitoring, erosion protection, ice loads, spillway design, flood prediction, emergency preparedness, reservoir management, rehabilitation, and foundation design. Separate abstracts have been prepared for 16 papers from the seminar

  20. Limnology of hartbeespoort dam

    CSIR Research Space (South Africa)

    Ashton, PJ

    1985-01-01

    Full Text Available Hartbeespoort Dam is a hypertrophic, warm, monomictic impoundment. With a mean depth of 9.6 m and a surface area of 20 km2, the system demonstrates that hypertrophy is not confined to small shallow lakes as concluded by Barica (1981...

  1. Spatial and temporal assessment of driving and conditioning factors and their impact on land use / land cover change in the Xiangxi Catchment, Three Gorges Region

    Science.gov (United States)

    Seeber, Christoph; Hartmann, Heike; Xiang, Wei; King, Lorenz

    2010-05-01

    Land use / land cover change (LUCC) is the most important human alteration of the earth's surface and is primarily studied in cases where it leads to severe environmental problems. The construction of the Three Gorges Dam on the Yangtze River in China has an extensive impact on the ecosystems and the local population. To assess its impact, the Xiangxi Catchment is taken as an example. The outlet of the Xiangxi River, a northern tributary of the Yangtze River, is located about 40 km upstream of the Three Gorges Dam. Due to the loss of fertile arable land and residential land which is mainly induced by the inundation and measures of resettlement, enormous LUCC is observed in the study area by depicting the land use / land cover by classification of LandsatTM data retrieved in 1987 and 2007. LUCC in the Xiangxi Catchment during this period can generally be characterized as decrease of cultivated land, increase of woodland and fallow land, and a shift in cropping from traditional smallholder farming to the establishment of citrus orchards, which are implemented as cash crops. Not only the inundation and the resettlement have an impact on LUCC, also the newly built and improved traffic infrastructure, growth of urban structures and land use policies in terms of environmental protection are expected to play an important role concerning LUCC. To assess the spatial and temporal impact of influencing factors, a LUCC gradient is generated based on post-classification change analysis of multispectral data. Furthermore, inter-stages between 1987 and 2007 have to be examined, to reach for a higher temporal resolution, which shall help to figure out temporal relationships between LUCC and the occurrence of driving factors. Once influence factors and and their spatial and temporal impacts are identified, a basis for predicting LUCC in the future for is provided for this area.

  2. Effect of Rubber Dam on Arterial Oxygen Saturation in Children.

    Science.gov (United States)

    Nara, Asha; Chour, Rashmi; Narasimman, Jamini; Latti, Pooja; Srinidhi, P B

    2015-06-01

    The placement of rubber dam has the potential to alter the airflow through nasal and oral cavities. Pediatric dentist should be aware whether the use of a rubber dam affects the oxygen saturation (SpO2) in children. To assess the effect of rubber dam on arterial blood SpO2 in children of 6-12 years age. Totally, 60 ASA Class I patients of 6-12 years age, randomly allocated in two groups: Group A: Rubber dam isolation of maxilla and Group B: Isolation of the mandible. A pulse oximeter was used to detect SpO2. To establish a baseline, each patient's SpO2 was recorded every 30 s for 2 min. A rubber dam was then placed which extended over the nose. Class I cavity and glass ionomer cements restoration were performed. The rubber dam was cut to expose the nasal cavities SpO2 were recorded every 30 s for 5 min throughout the procedure. A two-way ANOVA test was applied. In both groups there was no significant difference in SpO2 after rubber dam placement with nose covered or uncovered (P > 0.05). There was no significant change in SpO2 after rubber dam isolation with nose covered or uncovered in children of 6-12 years age.

  3. The Political Ecology of Chinese Large Dams in Cambodia: Implications, Challenges and Lessons Learnt from the Kamchay Dam

    Directory of Open Access Journals (Sweden)

    Giuseppina Siciliano

    2016-09-01

    Full Text Available Given the opportunities offered by foreign investment in energy infrastructure mostly by Chinese firms, the Government of Cambodia is giving high priority to developing hydropower resources for reducing energy poverty and powering economic growth. Using a “Political ecology of the Asian drivers” framework, this paper assesses China’s involvement in the development of large dams’ in Cambodia and its impacts on the access of natural resources such as water and energy by dam builders, local communities and the government. This analysis is based on 61 interviews and 10 focus group discussions with affected communities, institutional actors, Chinese dam builders and financiers in relation to the first large Chinese dam built in Cambodia: the Kamchay dam. Based on the results of the analysis this paper makes recommendations on how to improve the planning, implementation and governance of future large dams in Cambodia.

  4. Tiny bubbles challenge giant turbines: Three Gorges puzzle.

    Science.gov (United States)

    Li, Shengcai

    2015-10-06

    Since the birth of the first prototype of the modern reaction turbine, cavitation as conjectured by Euler in 1754 always presents as a challenge. Following his theory, the evolution of modern reaction (Francis and Kaplan) turbines has been completed by adding the final piece of the element 'draft-tube' that enables turbines to explore water energy at efficiencies of almost 100%. However, during the last two and a half centuries, with increasing unit capacity and specific speed, the problem of cavitation has been manifested and complicated by the draft-tube surges rather than being solved. Particularly, during the last 20 years, the fierce competition in the international market for extremely large turbines with compact design has encouraged the development of giant Francis turbines of 700-1000 MW. The first group (24 units) of such giant turbines of 700 MW each was installed in the Three Gorges project. Immediately after commission, a strange erosion phenomenon appeared on the guide vane of the machines that has puzzled professionals. From a multi-disciplinary analysis, this Three Gorges puzzle could reflect an unknown type of cavitation inception presumably triggered by turbulence production from the boundary-layer streak transitional process. It thus presents a fresh challenge not only to this old turbine industry, but also to the fundamental sciences.

  5. Plugs or flood-makers? the unstable landslide dams of eastern Oregon

    Science.gov (United States)

    Safran, Elizabeth B.; O'Connor, Jim E.; Ely, Lisa L.; House, P. Kyle; Grant, Gordon E.; Harrity, Kelsey; Croall, Kelsey; Jones, Emily

    2015-01-01

    Landslides into valley bottoms can affect longitudinal profiles of rivers, thereby influencing landscape evolution through base-level changes. Large landslides can hinder river incision by temporarily damming rivers, but catastrophic failure of landslide dams may generate large floods that could promote incision. Dam stability therefore strongly modulates the effects of landslide dams and might be expected to vary among geologic settings. Here, we investigate the morphometry, stability, and effects on adjacent channel profiles of 17 former and current landslide dams in eastern Oregon. Data on landslide dam dimensions, former impoundment size, and longitudinal profile form were obtained from digital elevation data constrained by field observations and aerial imagery; while evidence for catastrophic dam breaching was assessed in the field. The dry, primarily extensional terrain of low-gradient volcanic tablelands and basins contrasts with the tectonically active, mountainous landscapes more commonly associated with large landslides. All but one of the eastern Oregon landslide dams are ancient (likely of order 103 to 104 years old), and all but one has been breached. The portions of the Oregon landslide dams blocking channels are small relative to the area of their source landslide complexes (0.4–33.6 km2). The multipronged landslides in eastern Oregon produce marginally smaller volume dams but affect much larger channels and impound more water than do landslide dams in mountainous settings. As a result, at least 14 of the 17 (82%) large landslide dams in our study area appear to have failed cataclysmically, producing large downstream floods now marked by boulder outwash, compared to a 40–70% failure rate for landslide dams in steep mountain environments. Morphometric indices of landslide dam stability calibrated in other environments were applied to the Oregon dams. Threshold values of the Blockage and Dimensionless Blockage Indices calibrated to worldwide

  6. Expansion at Olympic Dam

    International Nuclear Information System (INIS)

    Lewis, C.

    1997-01-01

    The Olympic Dam orebody is the 6th largest copper and the single largest uranium orebody in the world. Mine production commenced in June 1988, at an annual production rate of around 45,000 tonnes of copper and 1,000 tonnes of uranium. Western Mining Corporation announced in 1996 a proposed $1.25 billion expansion of the Olympic Dam operation to raise the annual production capacity of the mine to 200,000 tonnes of copper, approximately 3,700 tonnes of uranium, 75,000 ounces of gold and 950,000 ounces of silver by 2001. Further optimisation work has identified a faster track expansion route, with an increase in the capital cost to $1.487 billion but improved investment outcome, a new target completion date of end 1999, and a new uranium output of 4,600 tonnes per annum from that date

  7. Temporal variation and spatial distribution of PAH in water of Three Gorges Reservoir during the complete impoundment period.

    Science.gov (United States)

    Wang, Jingxian; Henkelmann, Bernhard; Bi, Yonghong; Zhu, Kongxian; Pfister, Gerd; Hu, Wei; Temoka, Cedrique; Westrich, Bernhard; Schramm, Karl-Werner

    2013-10-01

    Bioavailable concentrations of polycyclic aromatic hydrocarbons (PAHs) were investigated in water of Three Gorges Reservoir (TGR) using semipermeable membrane devices during the period of completely impounding water. ∑PAH concentrations in water of TGR in the period of completely impounding water were 15-381 ng L(-1). ∑PAH concentrations increased from town or counties to big industrialized cities in TGR, indicating urbanization effects on PAH pollution in the water. Tributaries in TGR have a certain contribution of PAH pollution to the mainstream of Yangtze River and their pollution could not be neglected. An obvious decrease of PAH concentration was observed after 175-m water impounding in 2011 in TGR. Several factors may account for this decrease, including execution of comprehensive treatment and management measures in TGR, less rainfall in 2011, and sedimentation effect caused by the dam. Passive sampling method has been successfully applied in the investigation of trace PAH in water of TGR and proved to be a useful and efficient tool for the management and sustainable development of the big reservoir. The results of the study provide valuable information about PAH pollution in the whole reservoir including some tributaries, and the pollution status is dynamically related with human activities. Therefore, PAH could be used as a marker compound or indicator in the network monitoring system to surveil and trace the pollution status in TGR.

  8. Dam failure analysis for the Lago El Guineo Dam, Orocovis, Puerto Rico

    Science.gov (United States)

    Gómez-Fragoso, Julieta; Heriberto Torres-Sierra,

    2016-08-09

    considered within the model. The results of the hydrologic simulations indicated that for all hydrologic conditions scenarios, the Lago El Guineo Dam would not experience overtopping. For the dam breach hydraulic analysis, failure by piping was the selected hypothetical failure mode for the Lago El Guineo Dam.Results from the simulated dam failure of the Lago El Guineo Dam using the HEC–RAS model for the 6- and 24-hour probable maximum precipitation events indicated peak discharges below the dam of 1,342.43 and 1,434.69 cubic meters per second, respectively. Dam failure during the 24-hour, 100-year recurrence rainfall event resulted in a peak discharge directly downstream from Lago El Guineo Dam of 1,183.12 cubic meters per second. Dam failure during sunny-day conditions (no precipitation) produced a peak discharge at Lago El Guineo Dam of 1,015.31 cubic meters per second assuming the initial water-surface elevation was at the morning-glory spillway invert elevation.The results of the hydraulic analysis indicate that the flood would extend to many inhabited areas along the stream banks from the Lago El Guineo Dam to the mouth of the Río Grande as a result of the simulated failure of the Lago El Guineo Dam. Low-lying regions in the vicinity of Ciales, Manatí, and Barceloneta, Puerto Rico, are among the regions that would be most affected by failure of the Lago El Guineo Dam. Effects of the flood control (levee) structure constructed in 2000 to provide protection to the low-lying populated areas of Barceloneta, Puerto Rico, were considered in the hydraulic analysis of dam failure. The results indicate that overtopping can be expected in the aforementioned levee during 6- and 24-hour probable maximum precipitation events. The levee was not overtopped during dam failure scenarios under the 24-hour, 100-year recurrence rainfall event or sunny-day conditions.

  9. Dam spills and fishes

    International Nuclear Information System (INIS)

    1996-01-01

    This short paper reports the main topics discussed during the two days of the annual colloquium of the Hydro-ecology Committee of EdF. The first day was devoted to the presentation of the joint works carried out by EdF, the Paul-Sabatier University (Toulouse), the Provence St-Charles University (Marseille), the ENSAT (Toulouse) and the CEMAGREF (Lyon and Aix-en-Provence) about the environmental impact of dam spills on the aquatic flora and fauna downstream. A synthesis and recommendations were presented for the selection and characterization of future sites. The second day was devoted to the hydro-ecology study of the dam reservoir of Petit-Saut (French Guyana): water reoxygenation, quality evolution, organic matter, plankton, invertebrates and fishes. The 134 French dams concerned by water spills have been classified according to the frequency of spills, the variations of flow rates created, and their impacts on fishing, walking, irrigation, industry, drinking water, navigation, bathing. Particular studies on different sites have demonstrated the complexity of the phenomena involved concerning the impact on the ecosystems and the water quality. (J.S.)

  10. Probing Torpedo californica acetylcholinesterase catalytic gorge with two novel bis-functional galanthamine derivatives.

    Science.gov (United States)

    Bartolucci, Cecilia; Haller, Lars A; Jordis, Ulrich; Fels, Gregor; Lamba, Doriano

    2010-01-28

    N-Piperidinopropyl-galanthamine (2) and N-saccharinohexyl-galanthamine (3) were used to investigate interaction sites along the active site gorge of Torpedo californica actylcholinesterase (TcAChE). The crystal structure of TcAChE-2 solved at 2.3 A showed that the N-piperidinopropyl group in 2 is not stretched along the gorge but is folded over the galanthamine moiety. This result was unexpected because the three carbon alkyl chain is just long enough for the bulky piperidine group to be placed above the bottleneck (Tyr121, Phe330) midway down the gorge. The crystal structure of TcAChE-3 at 2.2 A confirmed that a dual interaction with the sites at the bottom, and at the entrance of the gorge, enhances inhibitory activity: a chain of six carbon atoms has, in this class of derivatives, the correct length for optimal interactions with the peripheral anionic site (PAS).

  11. South Channel Dam Rehabilitation Project - Successfully Addressing Dam Rehabilitation Challenges

    OpenAIRE

    Graeser, M. D.; Jensen, M. C.

    2016-01-01

    The Post Falls South Channel Dam is located on the Spokane River in Post Falls, Idaho. The concrete gravity dam was constructed in 1906 and was recently rehabilitated. The rehabilitation project included several design elements; the primary objectives were the replacement of the six spillway gates and hoists and significant rehabilitation of the concrete. The South Channel Dam rehabilitation encountered several challenges due to the age and condition of the existing structure, the large scale...

  12. Resilience scales of a dammed tropical river

    Science.gov (United States)

    Calamita, Elisa; Schmid, Martin; Wehrli, Bernhard

    2017-04-01

    Artificial river impoundments disrupt the seasonality and dynamics of thermal, chemical, morphological and ecological regimes in river systems. These alterations affect the aquatic ecosystems in space and time and specifically modify the seasonality and the longitudinal gradients of important biogeochemical processes. Resilience of river systems to anthropogenic stressors enables their recovery along the flow path; however little is known about the longitudinal distance that rivers need to partially restore their physical, chemical and biological integrity. In this study, the concept of a "resilience scale" will be explored for different water quality parameters downstream of Kariba dam, the largest artificial lake in the Zambezi basin (South-East Africa). The goal of this project is to develop a modelling framework to investigate and quantify the impact of large dams on downstream water quality in tropical context. In particular, we aim to assess the degree of reversibility of the main downstream alterations (temperature, oxygen, nutrients) and consequently the quantification of their longitudinal extent. Coupling in-situ measurements with hydraulic and hydrological parameters such as travel times, will allow us to define a physically-based parametrization of the different resilience scales for tropical rivers. The results will be used for improving future dam management at the local scale and assessing the ecological impact of planned dams at the catchment scale.

  13. DAM BREACH PARAMETERS AND THEIR INFLUENCE ON FLOOD HYDROGRAPHS FOR MOSUL DAM

    Directory of Open Access Journals (Sweden)

    TALAL A. BASHEER

    2017-11-01

    Full Text Available Dams breach geometry prediction is crucial in dam break studies. The characteristics of flood hydrographs resulting from a dam breach essentially depend on the breach geometry and the required time for breach formation. To investigate the impact of breach parameters on maximum breaching outflows, five breach prediction approaches were implemented to calculate the flood hydrographs using HEC-RAS model, for Mosul dam. Numerous reservoir water levels for each approach were considered. ensitivity analysis was carried out to evaluate the effect of each parameter on the resulting flood hydrographs. The time and value of peak discharge for each scenario were analysed and discussed. Results show that the most suitable method for estimating breach parameters for Mosul dam was the Froehlich approach. Furthermore, the sensitivity analysis shows that the breach side slope does not affect the peak discharge time and has a minor influence on peak outflow values. Meanwhile, the required time for the breach to develop was highly sensitive to both peak discharge and peak discharge time.

  14. Hydraulic design of Three Gorges right bank powerhouse turbine for improvement of hydraulic stability

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Q, E-mail: qhshi@dfem.com.c [Dong Fang Electrical Machinery Co., Ltd., DEC 188, Huanghe West Road, Deyang, 618000 (China)

    2010-08-15

    This paper presents the hydraulic design of Three Gorges Right Bank Powerhouse turbine for improvement of hydraulic stability. The technical challenges faced in the hydraulic design of the turbine are given. The method of hydraulic design for improving the hydraulic stability and particularly for eliminating the upper part load pressure pulsations is clarified. The final hydraulic design results of Three Gorges Right Bank Powerhouse turbine based on modern hydraulic design techniques are presented.

  15. Hydrologic alteration affects aquatic plant assemblages in an arid-land river

    Science.gov (United States)

    Vinson, Mark; Hestmark, Bennett; Barkworth, Mary E.

    2014-01-01

    We evaluated the effects of long-term flow alteration on primary-producer assemblages. In 1962, Flaming Gorge Dam was constructed on the Green River. The Yampa River has remained an unregulated hydrologically variable river that joins the Green River 100 km downstream from Flaming Gorge Dam. In the 1960s before dam construction only sparse occurrences of two macroalgae, Cladophora and Chara, and no submerged vascular plants were recorded in the Green and Yampa rivers. In 2009–2010, aquatic plants were abundant and widespread in the Green River from the dam downstream to the confluence with the Yampa River. The assemblage consisted of six vascular species, Elodea canadensis, Myriophyllum sibiricum, Nasturtium officinale,Potamogeton crispus, Potamogeton pectinatus, and Ranunculus aquatilis, the macroalgae Chara and Cladophora, and the bryophyte, Amblystegium riparium. In the Green River downstream from the Yampa River, and in the Yampa River, only sparse patches of Chara and Cladophora growing in the splash zone on boulders were collected. We attribute the observed changes in the Green River to an increase in water transparency and a reduction in suspended and bed-load sediment and high flow disturbances. The lack of hydrophyte colonization downstream from the confluence with the Yampa River has implications for understanding tributary amelioration of dam effects and for designing more natural flow-regime schedules downstream from large dams.

  16. 1000 dams down and counting

    Science.gov (United States)

    O'Connor, James E.; Duda, Jeff J.; Grant, Gordon E.

    2015-01-01

    Forty years ago, the demolition of large dams was mostly fiction, notably plotted in Edward Abbey's novel The Monkey Wrench Gang. Its 1975 publication roughly coincided with the end of large-dam construction in the United States. Since then, dams have been taken down in increasing numbers as they have filled with sediment, become unsafe or inefficient, or otherwise outlived their usefulness (1) (see the figure, panel A). Last year's removals of the 64-m-high Glines Canyon Dam and the 32-m-high Elwha Dam in northwestern Washington State were among the largest yet, releasing over 10 million cubic meters of stored sediment. Published studies conducted in conjunction with about 100 U.S. dam removals and at least 26 removals outside the United States are now providing detailed insights into how rivers respond (2, 3).

  17. Influence of the Three Gorges Project on saltwater intrusion in the Yangtze River Estuary

    Science.gov (United States)

    An, Qiang; Wu, Yanqing; Taylor, Shauna; Zhao, Bin

    2009-02-01

    The Three Gorges Project (TGP) is a transcentury project that has aroused world attention. It is expected that the flow velocity and runoff of the Yangtze River will be changed after the project has been accomplished. Consequently, however, the ecological environment in the Yangtze River Basin, particularly in the estuary region, will be affected. Salinity intrusion into the Yangtze River estuary, in general, is mostly affected by the Yangtze River discharge and its external tidal level. This paper focuses on examining the influence of changes in runoff on salinity value. The question, to which should be paid attention is: how is the interaction between changes in runoff of the Yangtze River and salinity distribution in the Yangtze River estuary, China? In this research, a three-dimensional model has been used to identify the effects of runoff change on salinity distribution. The drawn conclusion is that the change of salinity is influenced by discharge variation. Positive and negative impacts of TGP would both turn up but in different period. In sum, TGP is in favor of restraining saltwater intrusion. Nevertheless a suitable method should be found to resolve its negative influences.

  18. Behavior and dam passage of juvenile Chinook salmon at Cougar Reservoir and Dam, Oregon, March 2011 - February 2012

    Science.gov (United States)

    Beeman, John W.; Hansel, Hal C.; Hansen, Amy C.; Haner, Philip V.; Sprando, Jamie M.; Smith, Collin D.; Evans, Scott D.; Hatton, Tyson W.

    2013-01-01

    passive integrated transponder detectors at various locations downstream of the dam, indicating some tagged fish passed the dam undetected. The rate of dam passage was affected by diel period, discharge, and reservoir elevation. Diel period was the most influential factor of those examined, with nighttime dam passage rates about 9 times greater than daytime rates, depending on the distance of fish from the dam outlet. Dam passage rates also were positively related to dam discharge, and negatively related to reservoir elevation. In the operational condition used as an example, fish approached the dam outlet at the temperature control tower from the south and east and, when most fish got near the tower, they were directly in front of it. In many cases, the results for wild and hatchery fish were similar, or the results suggested hatchery fish could be reasonable surrogates for wild fish. Hatchery-origin and wild-origin fish behaved similarly in the following ways: their general movements in the reservoir; the timing of their dam passage; and the effects of diel period, discharge, and elevation on their passage rates. Parasitic copepods were present on most wild fish examined, and the mortality of wild fish during capture, handling and tagging was much greater than that of hatchery fish. This suggests that the ability of wild fish to cope with stressors may be less than that of fish directly from the hatchery.

  19. Verifying Pressure of Water on Dams, a Case Study.

    Science.gov (United States)

    Bayrak, Temel

    2008-09-03

    Sensing and monitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the present study is to find the extent to which rising reservoir level affects the mechanism of deformation of the Yamula dam under certain changes in the reservoir level conditions during the first filling period. A new dynamic deformation analysis technique was developed to analyze four geodetic monitoring records consisting of vertical and horizontal displacements of nine object points established on the dam and six reference points surrounding it, to see whether the rising reservoir level is responsible for the vertical and horizontal deformations during the first filling period. The largest displacements were determined in the middle points of the dam construction. There is an apparent linear relationship between the dam subsidence and the reservoir level. The dynamic deformation model was developed to model this situation. The model infers a causative relationship between the reservoir level and the dam deformations. The analysis of the results determines the degree of the correlation between the change in the reservoir level and the observed structural deformation of the dam.

  20. Verifying Pressure of Water on Dams, a Case Study

    Directory of Open Access Journals (Sweden)

    Temel Bayrak

    2008-09-01

    Full Text Available Sensing and monitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the present study is to find the extent to which rising reservoir level affects the mechanism of deformation of the Yamula dam under certain changes in the reservoir level conditions during the first filling period. A new dynamic deformation analysis technique was developed to analyze four geodetic monitoring records consisting of vertical and horizontal displacements of nine object points established on the dam and six reference points surrounding it, to see whether the rising reservoir level is responsible for the vertical and horizontal deformations during the first filling period. The largest displacements were determined in the middle points of the dam construction. There is an apparent linear relationship between the dam subsidence and the reservoir level. The dynamic deformation model was developed to model this situation. The model infers a causative relationship between the reservoir level and the dam deformations. The analysis of the results determines the degree of the correlation between the change in the reservoir level and the observed structural deformation of the dam.

  1. Stability of earth dam with a vertical core

    Directory of Open Access Journals (Sweden)

    Orekhov Vyacheslav Valentinovich

    2016-01-01

    not affect the overall stability of the dam.

  2. Characteristics of transplacental lead transfer in rat dams and fetuses

    International Nuclear Information System (INIS)

    Kopfler, F.C.; Miller, R.G.; Kowal, N.E.; Kelty, K.C.; Doerger, J.U.; Mills, T.

    1987-01-01

    This study was designed to quantitate the dose resulting from lead exposure during the critical periods of brain development during gestation by determining: (1) if blood lead concentration in rat dams is affected by pregnancy status or duration of lead exposure, (2) if lead concentration in fetuses is associated with the duration of dam exposure, (3) the rates of lead absorption and elimination in pregnant and nonpregnant dams; and (4) the effect that prebreeding exposure on lead kinetics in the dam and upon fetus blood lead concentrations. The results of experiments in which the dams' drinking water contained 50 mg/L lead indicate blood lead levels (after normalizing by water consumption on a body weight basis) of pregnant rats are significantly higher than blood lead levels of non-pregnant rats. Statistical differences in blood lead levels were observed by day 15 of gestation and continue through day 20 of gestation. These blood lead differences are not due to lead treatment prior to breeding as seen when comparing Figure 1 and Figure 2. The blood lead levels of the fetuses at day 20 of gestation were 50-60% higher than that of the corresponding dams. The results from the latter two phases were ambiguous, due to large variability in individual animal absorption and elimination rates. However, the following observations can be made. Preexposure to lead does not affect the percent of lead transferred from the dams' blood to the fetuses. The rate of elimination of lead from the dams' blood does not appear to be affected by prebreeding exposure to lead or by the status of pregnancy. The fraction of the 203 Pb dose transferred to the fetus increases dramatically toward the end of gestation. The data suggest that lead absorption from the gut of pregnant rats is higher than that for nonpregnant rats

  3. Dam Break Analysis of Embankment Dams Considering Breach Characteristics

    Directory of Open Access Journals (Sweden)

    Abolfazl Shamsaei

    2004-05-01

    Full Text Available The study of dam's break, needs the definition of various parameters such as the break cause, its type, its dimension and the duration of breach development. The precise forecast for different aspects of the breach is one of the most important factors for analyzing it in embankment dam. The characteristics of the breach and determination of their vulnerability has the most effect on the waves resulting from dam break. Investigating, about the parameters of the breach in "Silveh" earth dam have been determined using the suitable model. In Silve dam a trapezoid breach with side slope z=0.01m and the average base line b=80m was computed. The duration of the breaches development is 1.9 hour. Regarding the above results and the application of DAM Break software the consequences of the probable break of the dam was determined. The analysis of the results of water covering of the city of Piranshahr located 12km from silve dam confirms that in 3 hours the water will reach the height (level of 1425 meters.

  4. Removing Dams, Constructing Science: Coproduction of Undammed Riverscapes by Politics, Finance, Environment, Society and Technology

    Directory of Open Access Journals (Sweden)

    Zbigniew J. Grabowski

    2017-10-01

    Full Text Available Dam removal in the United States has continued to increase in pace and scope, transitioning from a dam-safety engineering practice to an integral component of many large-scale river restoration programmes. At the same time, knowledge around dam removals remains fragmented by disciplinary silos and a lack of knowledge transfer between communities of practice around dam removal and academia. Here we argue that dam removal science, as a study of large restoration-oriented infrastructure interventions, requires the construction of an interdisciplinary framework to integrate knowledge relevant to decision-making on dam removal. Drawing upon infrastructure studies, relational theories of coproduction of knowledge and social life, and advances within restoration ecology and dam removal science, we present a preliminary framework of dams as systems with irreducibly interrelated political, financial, environmental, social, and technological dimensions (PFESTS. With this framework we analyse three dam removals occurring over a similar time period and within the same narrow geographic region (the Mid-Columbia Region in WA and OR, USA to demonstrate how each PFESTS dimension contributed to the decision to remove the dam, how it affected the process of removing the dam, and how those dimensions continue to operate post removal in each watershed. We conclude with a discussion of a joint research and practice agenda emerging out of the PFESTS framing.

  5. Assessing the influence of Environmental Impact Assessments on science and policy: an analysis of the Three Gorges Project.

    Science.gov (United States)

    Tullos, Desiree

    2009-07-01

    The need to understand and minimize negative environmental outcomes associated with large dams has both contributed to and benefited from the introduction and subsequent improvements in the Environmental Impact Assessment (EIA) process. However, several limitations in the EIA process remain, including those associated with the uncertainty and significance of impact projections. These limitations are directly related to the feedback between science and policy, with information gaps in scientific understanding discovered through the EIA process contributing valuable recommendations on critical focus areas for prioritizing and funding research within the fields of ecological conservation and river engineering. This paper presents an analysis of the EIA process for the Three Gorges Project (TGP) in China as a case study for evaluating this feedback between the EIA and science and policy. For one of the best-studied public development projects in the world, this paper presents an investigation into whether patterns exist between the scientific interest (via number of publications) in environmental impacts and (a) the identification of impacts as uncertain or priority by the EIA, (b) decisions or political events associated with the dam, and (c) impact type. This analysis includes the compilation of literature on TGP, characterization of ecosystem interactions and responses to TGP through a hierarchy of impacts, coding of EIA impacts as "uncertain" impacts that require additional study and "priority" impacts that have particularly high significance, mapping of an event chronology to relate policies, institutional changes, and decisions about TGP as "events" that could influence the focus and intensity of scientific investigation, and analysis of the number of publications by impact type and order within the impact hierarchy. From these analyses, it appears that the availability and consistency of scientific information limit the accuracy of environmental impact

  6. Dams and Rivers: A Primer on the Downstream Effects of Dams

    Science.gov (United States)

    Collier, Michael; Webb, Robert H.; Schmidt, John C.

    1996-01-01

    The U.S. Geological Survey is charged with monitoring the water and mineral resources of the United States. Beginning in 1889, the Survey established a network of water gaging stations across most of the country's rivers; some also measured sediment content of the water. Consequently, we now have valuable long-term data with which to track water supply, sediment transport, and the occurrence of floods. Many variables affect the flow of water from mountain brook to river delta. Some are short-term perturbations like summer thunderstorms. Others occur over a longer period of time, like the El Ninos that might be separated by a decade or more. We think of these variables as natural occurrences, but humans have exerted some of the most important changes -- water withdrawals for agriculture, inter-basin transfers, and especially the construction of an extensive system of dams. Dams have altered the flow of many of the Nation's rivers to meet societal needs. We expect floods to be contained. Irrigation is possible where deserts once existed. And water is released downstream not according to natural cycles but as dictated by a region's hour-by-hour needs for water or electricity. As a result, river channels below dams have changed dramatically. Depending on annual flow, flood peaks, and a river's sediment load, we might see changes such as sand building up in one channel, vegetation crowding into another, and extensive bank erosion in another. This Circular explores the emerging scientific arena of change in rivers below dams. This science tries first to understand and then anticipate changes to river beds and banks, and to riparian habitats and animal communities. To some degree, these downstream changes can be influenced by specific strategies of dam management. Scientists and resource managers have a duty to assemble this information and present it without bias to the rest of society. Society can then more intelligently choose a balance between the benefits and adverse

  7. Influences of local habitat, tributary position, and dam characteristics on fish assemblages within impoundments of low-head dams in the tributaries of the Qingyi River, China.

    Science.gov (United States)

    Li, Xian; Li, Yu-Ru; Chu, Ling; Zhu, Ren; Wang, Li-Zhu; Yan, Yun-Zhi

    2016-03-18

    Low-head dam impoundments modify local habitat and alter fish assemblages; however, to our knowledge, the pattern of how fish assemblages in the impoundments relate to local habitat, tributary position, and dam characteristics is still unclear. We used data collected in 62 impoundments created by low-head dams in headwater streams of the Qingyi River, China, to examine relationships between fish assemblages and local habitat, tributary position, and dam characteristics. We also assessed the relative importance of the three groups of factors in determining fish species richness and composition. Linear regression models showed that fish species richness was related to substrate heterogeneity, confluence link, and dam number upstream. Redundancy analysis showed that fish species compositions were influenced by substrate heterogeneity, confluence link, dam height, dam numbers upstream and downstream. Overall, dam characteristics were more important in affecting fish species richness but less important in determining fish species composition than local habitat (i.e., substrate heterogeneity) and tributary position. Our results suggest that low-head dam may affect fish species richness in impoundments by modifying local habitat and constraining fish movement, and the relative abundances of those fish species may depend more on species habitat presences and stream size than on impoundment size and number.

  8. War damages and reconstruction of Peruca dam

    International Nuclear Information System (INIS)

    Nonveiller, E.; Sever, Z.

    1999-01-01

    The paper describes the heavy damages caused by blasting in the Peruca rockfill dam in Croatia in January 1993. Complete collapse of the dam by overtopping was prevented through quick action of the dam owner by dumping clayey gravel on the lowest sections of the dam crest and opening the bottom outlet of the reservoir, thus efficiently lowering the water level. After the damages were sufficiently established and alternatives for restoration of the dam were evaluated, it was decided to construct a diaphragm wall through the damaged core in the central dam part as the impermeable dam element and to rebuild the central clay core at the dam abutments. Reconstruction works are described

  9. Dam construction in salt formations

    International Nuclear Information System (INIS)

    Jezierski, H.

    1984-01-01

    Dam Construction is a key task for the safety of the Gorleben repository. In order to seal a fille disposal field from the part in operation and to minimize radionuclide migration during the post-operating time a dam is to be developed and tested under certain accident conditions i.e., mainly the intrusion of brines and natural gas from either side of the dam. The development of this dam is subject of an extensive engineering project. This report summarizes the goals, problems, concepts, and first results of these systematical project studies. By analysing and characterizing special design criteria under site-specific aspects the major development priorities are investigated. First results will be presented concerning concrete based materials and their property changes due to the corrosive behavior of brines at elevated temperatures. Based on these investigations, pilot dams will be built and tested to prove their efficiency

  10. Earliest porotic hyperostosis on a 1.5-million-year-old hominin, olduvai gorge, Tanzania.

    Directory of Open Access Journals (Sweden)

    Manuel Domínguez-Rodrigo

    Full Text Available Meat-eating was an important factor affecting early hominin brain expansion, social organization and geographic movement. Stone tool butchery marks on ungulate fossils in several African archaeological assemblages demonstrate a significant level of carnivory by Pleistocene hominins, but the discovery at Olduvai Gorge of a child's pathological cranial fragments indicates that some hominins probably experienced scarcity of animal foods during various stages of their life histories. The child's parietal fragments, excavated from 1.5-million-year-old sediments, show porotic hyperostosis, a pathology associated with anemia. Nutritional deficiencies, including anemia, are most common at weaning, when children lose passive immunity received through their mothers' milk. Our results suggest, alternatively, that (1 the developmentally disruptive potential of weaning reached far beyond sedentary Holocene food-producing societies and into the early Pleistocene, or that (2 a hominin mother's meat-deficient diet negatively altered the nutritional content of her breast milk to the extent that her nursing child ultimately died from malnourishment. Either way, this discovery highlights that by at least 1.5 million years ago early human physiology was already adapted to a diet that included the regular consumption of meat.

  11. Simulating dam-breach flood scenarios of the Tangjiashan landslide dam induced by the Wenchuan Earthquake

    Directory of Open Access Journals (Sweden)

    X. Fan

    2012-10-01

    Full Text Available Floods from failures of landslide dams can pose a hazard to people and property downstream, which have to be rapidly assessed and mitigated in order to reduce the potential risk. The Tangjiashan landslide dam induced by the Mw = 7.9 2008 Wenchuan earthquake had impounded the largest lake in the earthquake affected area with an estimated volume of 3 × 108 m3, and the potential catastrophic dam breach posed a serious threat to more than 2.5 million people in downstream towns and Mianyang city, located 85 km downstream. Chinese authorities had to evacuate parts of the city until the Tangjiashan landslide dam was artificially breached by a spillway, and the lake was drained. We propose an integrated approach to simulate the dam-breach floods for a number of possible scenarios, to evaluate the severity of the threat to Mianyang city. Firstly, the physically-based BREACH model was applied to predict the flood hydrographs at the dam location, which were calibrated with observational data of the flood resulting from the artificial breaching. The output hydrographs from this model were inputted into the 1-D–2-D SOBEK hydrodynamic model to simulate the spatial variations in flood parameters. The simulated flood hydrograph, peak discharge and peak arrival time at the downstream towns fit the observations. Thus this approach is capable of providing reliable predictions for the decision makers to determine the mitigation plans. The sensitivity analysis of the BREACH model input parameters reveals that the average grain size, the unit weight and porosity of the dam materials are the most sensitive parameters. The variability of the dam material properties causes a large uncertainty in the estimation of the peak flood discharge and peak arrival time, but has little influence on the flood inundation area and flood depth downstream. The effect of cascading breaches of smaller dams downstream of the Tangjiashan dam was

  12. Advanced numerical techniques for modeling tensile crack propagation in gravity dams

    OpenAIRE

    Dias, I.F.; Oliver Olivella, Xavier; Lemos, J.V.; Lloberas Valls, Oriol

    2015-01-01

    Cracks propagating deep inside gravity dams can seriously affect their structural safety. Due to the potential catastrophic scenarios associated to the collapse of large concrete dams, it is a fundamental issue to realistically predict the eventual crack profiles and the ultimate structural resistance associated to the failure mechanisms. This work investigates tensile crack propagation in concrete gravity dams by using some new recently developed numerical techniques (crack-path field and...

  13. Initiation age and incision rates of inner gorges: Do they record multiple glacial-interglacial cycles?

    Science.gov (United States)

    Delunel, Romain; Casagrande, Jan; Schlunegger, Fritz; Akçar, Naki; Kubik, Peter W.

    2015-04-01

    Inner gorges represent some of the most conspicuous landforms in the European Alps. They form narrow and deep active-channel incisions that link hanging tributaries with trunk valleys in glacially-conditioned environments. Despite abundant research carried out on these objects, both their origin and evolution have remained unclear. In particular, the age of initiation, the rate of incision, and the respective contribution of fluvial and subglacial processes in the evolution of inner gorges have still been a matter of scientific debate. Indeed, answering these questions has been complicated by the lack of appropriate quantitative methods and/or suitable sampling strategies for studying inner gorges. Here, we report 10Be concentrations measured in alluvial sediments that have been collected along the main stream of a ~20-km2-catchment in the Swiss foreland (Central European Alps). This catchment hosts a ca. 100-m-deep and 2-km-long inner gorge that has been cut mainly in glacial till. Catchment wide denudation rates inferred from 10Be analyses (n = 15) vary from ~120 to 650 mm/ka and show a general downstream increasing trend. Additional field observations and GIS analyses reveal that the denudation rates within the catchment increase from the headwaters, characterized by relict glacial/periglacial landscapes, to the downstream end of the basin where the inner gorge has been formed. Using a 10Be-based sediment budget approach and the delineation of topographic domains from a 2-m-resolution LIDAR, we provide an estimate of erosion rates within the gorge that are higher than 2.5 m/ka and can reach up to ~ 7 m/ka. Combining these estimated erosion rates with the reconstruction of eroded volumes within the gorge, we obtain a rough initiation age in the early Holocene, in general agreement with previous studies reporting a postglacial origin for the inner gorges. Our results therefore appear contradictory with recent findings arguing for a gradual formation of inner

  14. Seismic hazard assessment of the Three Gorges Project

    Directory of Open Access Journals (Sweden)

    Yao Yunsheng

    2013-05-01

    Full Text Available Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismicity before impoundment and that the epicenters were concentrated in the east and west sides of the Zigui Basin, most of which were natural tectonic earthquakes. After impoundment, the seismic activity shifted to the segment between Badong and Zigui along the Yangtze River, mainly within 5 km of the reservoir bank. The seismogenesis was categorized into four types; Karst collapse earthquakes, earthquakes caused by Karst gas explosion, mining tunnel collapse earthquakes, and rock (terrane slip earthquakes, all of which are related to the lithology, structure, and tectonics of near-surface geological bodies of the area. Compared with the seismicity before impoundment, the seismic frequency increase was remarkable, with most of the magnitudes below Ms2. 0. Therefore, the intensity of the earthquakes remained at a low level. On November 22, 2008, a magnitude 4. 1 earthquake, the largest earthquake recorded since impoundment, occurred in Quyuan Town, Zigui County. The intensity and PGA of reservoir-induced earthquakes are higher than those of tectonic earthquakes with equal magnitude, but the peak intensity of reservoir-induced earthquakes is not likely to go beyond that of the estimated range from earlier studies.

  15. Small farm dams: impact on river flows and sustainability in a context of climate change

    Science.gov (United States)

    Habets, F.; Philippe, E.; Martin, E.; David, C. H.; Leseur, F.

    2014-10-01

    The repetition of droughts in France has led to a growing demand for irrigation water and consequently to an increase in requests for the construction of small farm dams. Although such dams are small, their accumulation in a basin affects river flows, because the water collected in these small farm dams is used for irrigation and thus does not contribute to river flow. In order to gain more insight into their impact on the annual and monthly discharges, especially during dry years, a small farm dam model was built and connected to a hydrometeorological model. Several scenarios with different volume capacities, filling catchment sizes and filling periods were tested for such dams. The results were analysed in a small basin in western France, where the pressure for building such dams is high, and then extended to the entire country. It was found that, due to the hydrometeorological conditions (mainly low precipitation compared to other regions in France), the development of small farm dams in north-western France would result in greater decreases in river flows and less efficient filling of small farm dams than in other regions. Therefore, such dams might not be as efficient as expected in supplying water to farmers when needed. Moreover, the ability to fill small farm dams is projected to decrease in a context of climate change, despite the uncertainty on the evolution of precipitation, thus worsening the situation.

  16. The Politics, Development and Problems of Small Irrigation Dams in Malawi: Experiences from Mzuzu ADD

    Directory of Open Access Journals (Sweden)

    Bryson Gwiyani Nkhoma

    2011-10-01

    Full Text Available The paper examines the progress made regarding the development of small irrigation dams in Malawi with the view of establishing their significance in improving rural livelihoods in the country. The paper adopts a political economy theory and a qualitative research approach. Evidence from Mzuzu Agricultural Development Division (ADD, where small reservoirs acquire specific relevance, shows that despite the efforts made, the development of small dams is making little progress. The paper highlights that problems of top-down planning, high investment costs, negligence of national and local interests, over-dependency on donors, and conflicts over the use of dams – which made large-scale dams unpopular in the 1990s – continue to affect the development of small irrigation dams in Malawi. The paper argues that small irrigation dams should not be simplistically seen as a panacea to the problems of large-scale irrigation dams. Like any other projects, small dams are historically and socially constructed through interests of different actors in the local settings, and can only succeed if actors, especially those from formal institutions, develop adaptive learning towards apparent conflicting relations that develop among them in the process of implementation. In the case of Mzuzu ADD, it was the failure of the government to develop this adaptive learning to the contestations and conflicts among these actors that undermined successful implementation of small irrigation dams. The paper recommends the need to consider local circumstances, politics, interests, rights and institutions when investing in small irrigation dams.

  17. Proceedings of the Canadian Dam Association's 2006 annual conference: dams: past, present and future

    International Nuclear Information System (INIS)

    2006-01-01

    This conference addressed particular technical challenges regarding the operation of dams with particular focus on best practices for improving dam management and safety. It featured 4 workshops and a technical program led by experts on dams and tailings facilities that addressed topics such as dam construction, design and rehabilitation; dam management in a hydrological uncertainty context; monitoring, instrumentation and maintenance; dam behaviour; dam safety, dam failure and practical approaches to emergency preparedness planning for dam owners; historical aspects and environmental issues and conflicting water use. Recent developments in dam construction were reviewed along with discharge and debris management, tailings dam issues, asset management, seismic issues, public safety, seepage monitoring, flow control, dam rehabilitation, concrete testing, hydrotechnical issues, risk assessment methodology, and dam safety guidelines for extreme flood analyses and their applications. All 80 presentations from this conference have been catalogued separately for inclusion in this database. refs., tabs., figs

  18. 7 CFR 1724.55 - Dam safety.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 11 2010-01-01 2010-01-01 false Dam safety. 1724.55 Section 1724.55 Agriculture... § 1724.55 Dam safety. (a) The provisions of this section apply only to RUS financed electric system... for Dam Safety,”(Guidelines), as applicable. A dam, as more fully defined in the Guidelines, is...

  19. Dam safety from theory to practice

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    These proceedings on dam safety consists of 20 papers divided into seven sessions. The first session dealt with tailings dams; sessions 2 to 5 with technology transfer as related to dam safety; the sixth session with dam rehabilitation; and the last session with environmental concerns. The conference took place at Banff, Alberta, in October 1995.refs., figs., tabs

  20. Review Article: Numerical analysis of the seismic behaviour of earth dam

    Directory of Open Access Journals (Sweden)

    Y. Parish

    2009-03-01

    Full Text Available The present study concerns analysis of the seismic response of earth dams. The behaviour of both the shell and core of the dam is described using the simple and popular non associated Mohr-Coulomb criterion. The use of this constitutive model is justified by the difficulty to obtain constitutive parameters for more advanced constitutive relations including isotropic and kinematic hardening. Analyses with real earthquake records show that the seismic loading induces plasticity in a large part of the shell and in the lower part of the core. Analysis shows that plasticity should be considered in the analysis of the seismic response of the dam, because it leads to a decrease in the natural frequencies of the dam together to energy dissipation, which could significantly affect the seismic response of the dam. Plastic analysis constitutes also a good tool for the verification of the stability of the dam under seismic loading.

  1. Potential impact of thermal effluents from Chongqing Fuling nuclear power plant to the Three Gorges Reservoir

    International Nuclear Information System (INIS)

    Han Baohua; Li Jianguo; Ma Binghui; Zhang Yue; Sun Qunli; Hu Yuping

    2012-01-01

    This study is based on the hydrological data near Chongqing Fuling Nuclear Power Plant along the Yangtze River, the present situation of the ecological environment of the Three Gorges Reservoir and the predicted results of thermal effluents from Chongqing Fuling Nuclear Power Plant. The standards of cooling water and the thermal tolerances indexes of aquatic organisms were investigated. The effects of thermal effluents on aquatic organisms were analyzed. The potential impact of Chongqing Fuling nuclear power plant to the Three Gorges Reservoir was explained. The results show that in the most adverse working conditions, the surface temperature near the outfall area is not more than 1℃, the temperature of thermal effluents do not exceed the suitable thermal range of fish breeding, growth and other thermal tolerances indexes. Thermal effluents from nuclear power plant have no influence about fish, plankton and benthic organisms in the Three Gorges Reservoir. (authors)

  2. The Ngorongoro Volcanic Highland and its relationships to volcanic deposits at Olduvai Gorge and East African Rift volcanism.

    Science.gov (United States)

    Mollel, Godwin F; Swisher, Carl C

    2012-08-01

    The Ngorongoro Volcanic Highland (NVH), situated adjacent and to the east of Olduvai Gorge in northern Tanzania, is the source of the immense quantities of lava, ignimbrite, air fall ash, and volcaniclastic debris that occur interbedded in the Plio-Pleistocene sedimentary deposits in the Laetoli and Olduvai areas. These volcanics have proven crucial to unraveling stratigraphic correlations, the age of these successions, the archaeological and paleontological remains, as well as the source materials from which the bulk of the stone tools were manufactured. The NVH towers some 2,000 m above the Olduvai and Laetoli landscapes, affecting local climate, run-off, and providing varying elevation - climate controlled ecosystem, habitats, and riparian corridors extending into the Olduvai and Laetoli lowlands. The NVH also plays a crucial role in addressing the genesis and history of East African Rift (EAR) magmatism in northern Tanzania. In this contribution, we provide age and petrochemical compositions of the major NVH centers: Lemagurut, basalt to benmorite, 2.4-2.2 Ma; Satiman, tephrite to phonolite, 4.6-3.5 Ma; Oldeani, basalt to trachyandesite, 1.6-1.5 Ma; Ngorongoro, basalt to rhyolite, 2.3-2.0 Ma; Olmoti, basalt to trachyte, 2.0-1.8 Ma; Embagai, nephelinite to phonolite, 1.2-0.6 Ma; and Engelosin, phonolite, 3-2.7 Ma. We then discuss how these correlate in time and composition with volcanics preserved at Olduvai Gorge. Finally, we place this into context with our current understanding as to the eruptive history of the NVH and relationship to East African Rift volcanism. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Dams and Levees: Safety Risks

    Science.gov (United States)

    Carter, N. T.

    2017-12-01

    The nation's flood risk is increasing. The condition of U.S. dams and levees contributes to that risk. Dams and levee owners are responsible for the safety, maintenance, and rehabilitation of their facilities. Dams-Of the more than 90,000 dams in the United States, about 4% are federally owned and operated; 96% are owned by state and local governments, public utilities, or private companies. States regulate dams that are not federally owned. The number of high-hazard dams (i.e., dams whose failure would likely result in the loss of human life) has increased in the past decade. Roughly 1,780 state-regulated, high-hazard facilities with structural ratings of poor or unsatisfactory need rehabilitation. Levees-There are approximately 100,000 miles of levees in the nation; most levees are owned and maintained by municipalities and agricultural districts. Few states have levee safety programs. The U.S. Army Corps of Engineers (Corps) inspects 15,000 miles of levees, including levees that it owns and local levees participating in a federal program to assist with certain post-flood repairs. Information is limited on how regularly other levees are inspected. The consequence of a breach or failure is another aspect of risk. State and local governments have significant authority over land use and development, which can shape the social and economic impacts of a breach or failure; they also lead on emergency planning and related outreach. To date, federal dam and levee safety efforts have consisted primarily of (1) support for state dam safety standards and programs, (2) investments at federally owned dams and levees, and (3) since 2007, creation of a national levee database and enhanced efforts and procedures for Corps levee inspections and assessments. In Public Law 113-121, enacted in 2014, Congress (1) directed the Corps to develop voluntary guidelines for levee safety and an associated hazard potential classification system for levees, and (2) authorized support for the

  4. Pilot project on the resettlement of out-migrant agricultural population in Yangtze Gorges Reservoir Area.

    Science.gov (United States)

    Zhu, W

    1992-10-01

    A brief summary is provided of the pilot project on the resettlement of the agricultural population in Yangtze Reservoir Area, China. Population needed to be resettled from the area to be flooded by the construction of the Three Gorges Hydropower Station in the middle of the Yangtze River. The submerged area included 19 cities and counties of which 2 are county level cities, 11 county seats, 140 towns and market towns, 326 townships, and 1351 villages. The population to be evacuated totaled 725,500 residents, of whom 392,90 were urban residents and 332,600 were rural residents. The amount of cultivated land lost amounted to 3573 mu (1 mu = 17.5% of an acre). While the hydropower station is being constructed, the population will rise over 20 years to 1 million. The Chinese government has developed a program of resettlement, whereby displaced population receive financial support to develop the economy; the sum appropriated equaled 50 million yuan RMB. So far, the pilot project has been successful. Within the 326 townships affected, only part of the land lying below the highest water level of the reservoir would be affected; the remaining land could be used for resettlement, albeit the land is uncultivated grassland and barren mountains and hills. Resettlement in the area is preferred over long distance migration. The government program will help farmers make full use of the available lands. Suggested crops include mulberry trees, oranges, medical herbs, and other cash crops. Effort will be made to ensure each farmer will receive one mu of economic forest or one mu of cultivated land of high and stable yields. The program aims to guarantee sufficient food supplies and the same standard of living before displacement, as well as the opportunity to create better conditions for alleviating poverty and improvement through increased productivity.

  5. The World Commission on Dams + 10: Revisiting the Large Dam Controversy

    Directory of Open Access Journals (Sweden)

    Deborah Moore

    2010-06-01

    Full Text Available The World Commission on Dams (WCD was an experiment in multi-stakeholder dialogue and global governance concerned with a subject area – large dams – that was fraught with conflict and controversy. The WCD Report, Dams and Development: A New Framework for Decision-Making, was published in 2000 and accompanied by hopes that broad-based agreements would be forged on how to better manage water and energy development. Ten years later, this special issue of Water Alternatives revisits the WCD and its impacts, exploring the question: Is the WCD still relevant? The editorial team and the Guest Editors of this special issue of Water Alternatives have selected a range of 20 papers, 6 viewpoints, and 4 book reviews that help to illustrate the evolution in the dams debate. The goal of this special issue is to examine the influence and the impacts of the WCD on the dam enterprise, in general, and on the policies and practices of key stakeholders and institutions, and on the development outcomes for affected communities and environments, in particular. In this introduction, the Guest Editors provide an overview of the special issue, exploring the new drivers of dam development that have emerged during the last decade, including climate change and new financiers of dams, and describing the themes emerging from this diverse set of papers and viewpoints. This special issue demonstrates the need for a renewed multi-stakeholder dialogue at multiple levels. This would not be a redo of the WCD, but rather a rekindling and redesigning of processes and forums where mutual understanding, information-sharing, and norm-setting can occur. One of the most promising developments of the last decade is the further demonstration, in case studies described here, that true partnership amongst key stakeholders can produce transformative resource-sharing agreements, showing that many of the WCD recommendations around negotiated decision making are working in practice. We hope

  6. Water exposure assessment of aryl hydrocarbon receptor agonists in Three Gorges Reservoir, China using SPMD-based virtual organisms.

    Science.gov (United States)

    Wang, Jingxian; Bernhöft, Silke; Pfister, Gerd; Schramm, Karl-Werner

    2014-10-15

    SPMD-based virtual organisms (VOs) were deployed at five to eight sites in the Three Gorges Reservoir (TGR), China for five periods in 2008, 2009 and 2011. The water exposure of aryl hydrocarbon receptor (AhR) agonists was assessed by the VOs. The chosen bioassay response for the extracts of the VOs, the induction of 7-ethoxyresorufin-O-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The results show that the extracts from the VOs could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) accounted for effects in the mixture. The levels of AhR agonists in VOs from upstream TGR were in general higher than those from downstream reservoir, indicating urbanization effect on AhR agonist pollution. The temporal variation showed that levels of AhR agonists in 2009 and 2011 were higher than those in 2008, and the potential non-additive effects in the area close to the dam were also obviously higher in 2009 and 2011 than in 2008, indicating big changes in the composition of pollutants in the area after water level reached a maximum of 175 m. Although the aqueous concentration of AhR agonists of 0.8-4.8 pg TCDDL(-1) in TGR was not alarming, the tendency of accumulating high concentration of AhR agonists in VO lipid and existence of possible synergism or antagonism in the water may exhibit a potential hazard to local biota being exposed to AhR agonists. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Abstracts and electronic proceedings of the Canadian Dam Association's 2008 annual conference : emerging technologies for dams

    International Nuclear Information System (INIS)

    2008-01-01

    This conference provided a national forum to explore and discuss emerging technologies which can be used to enhance dam safety and construction practices on both new and existing projects. Advancements in the fields of dam design, construction, and remedial works were reviewed as well as new techniques for dam monitoring programs. Engineers, geoscientists, dam owners and operators and other stakeholders exchanged ideas and information regarding the operation, maintenance and management of water and tailings dams. The conference sessions dealt with a variety of topics, including dam foundations; mining dams; dams and the environment; embankment dams; dams and seismicity; hydrotechnics; assessment and investigative technologies; dam instrumentation and monitoring; computational hydraulics; and dam safety. The conference featured 46 presentations, of which 37 have been catalogued separately for inclusion in this database. refs., tabs., figs

  8. Quantifying Oldowan Stone Tool Production at Olduvai Gorge, Tanzania.

    Directory of Open Access Journals (Sweden)

    Jay S Reti

    Full Text Available Recent research suggests that variation exists among and between Oldowan stone tool assemblages. Oldowan variation might represent differential constraints on raw materials used to produce these stone implements. Alternatively, variation among Oldowan assemblages could represent different methods that Oldowan producing hominins utilized to produce these lithic implements. Identifying differential patterns of stone tool production within the Oldowan has implications for assessing how stone tool technology evolved, how traditions of lithic production might have been culturally transmitted, and for defining the timing and scope of these evolutionary events. At present there is no null model to predict what morphological variation in the Oldowan should look like. Without such a model, quantifying whether Oldowan assemblages vary due to raw material constraints or whether they vary due to differences in production technique is not possible. This research establishes a null model for Oldowan lithic artifact morphological variation. To establish these expectations this research 1 models the expected range of variation through large scale reduction experiments, 2 develops an algorithm to categorize archaeological flakes based on how they are produced, and 3 statistically assesses the methods of production behavior used by Oldowan producing hominins at the site of DK from Olduvai Gorge, Tanzania via the experimental model. Results indicate that a subset of quartzite flakes deviate from the null expectations in a manner that demonstrates efficiency in flake manufacture, while some basalt flakes deviate from null expectations in a manner that demonstrates inefficiency in flake manufacture. The simultaneous presence of efficiency in stone tool production for one raw material (quartzite and inefficiency in stone tool production for another raw material (basalt suggests that Oldowan producing hominins at DK were able to mediate the economic costs associated

  9. Quantifying Oldowan Stone Tool Production at Olduvai Gorge, Tanzania.

    Science.gov (United States)

    Reti, Jay S

    2016-01-01

    Recent research suggests that variation exists among and between Oldowan stone tool assemblages. Oldowan variation might represent differential constraints on raw materials used to produce these stone implements. Alternatively, variation among Oldowan assemblages could represent different methods that Oldowan producing hominins utilized to produce these lithic implements. Identifying differential patterns of stone tool production within the Oldowan has implications for assessing how stone tool technology evolved, how traditions of lithic production might have been culturally transmitted, and for defining the timing and scope of these evolutionary events. At present there is no null model to predict what morphological variation in the Oldowan should look like. Without such a model, quantifying whether Oldowan assemblages vary due to raw material constraints or whether they vary due to differences in production technique is not possible. This research establishes a null model for Oldowan lithic artifact morphological variation. To establish these expectations this research 1) models the expected range of variation through large scale reduction experiments, 2) develops an algorithm to categorize archaeological flakes based on how they are produced, and 3) statistically assesses the methods of production behavior used by Oldowan producing hominins at the site of DK from Olduvai Gorge, Tanzania via the experimental model. Results indicate that a subset of quartzite flakes deviate from the null expectations in a manner that demonstrates efficiency in flake manufacture, while some basalt flakes deviate from null expectations in a manner that demonstrates inefficiency in flake manufacture. The simultaneous presence of efficiency in stone tool production for one raw material (quartzite) and inefficiency in stone tool production for another raw material (basalt) suggests that Oldowan producing hominins at DK were able to mediate the economic costs associated with stone tool

  10. Trading river services: optimizing dam decisions at the basin scale to improve socio-ecological resilience

    Science.gov (United States)

    Roy, S. G.; Gold, A.; Uchida, E.; McGreavy, B.; Smith, S. M.; Wilson, K.; Blachly, B.; Newcomb, A.; Hart, D.; Gardner, K.

    2017-12-01

    Dam removal has become a cornerstone of environmental restoration practice in the United States. One outcome of dam removal that has received positive attention is restored access to historic habitat for sea-run fisheries, providing a crucial gain in ecosystem resilience. But dams also provide stakeholders with valuable services, and uncertain socio-ecological outcomes can arise if there is not careful consideration of the basin scale trade offs caused by dam removal. In addition to fisheries, dam removals can significantly affect landscape nutrient flux, municipal water storage, recreational use of lakes and rivers, property values, hydroelectricity generation, the cultural meaning of dams, and many other river-based ecosystem services. We use a production possibility frontiers approach to explore dam decision scenarios and opportunities for trading between ecosystem services that are positively or negatively affected by dam removal in New England. Scenarios that provide efficient trade off potentials are identified using a multiobjective genetic algorithm. Our results suggest that for many river systems, there is a significant potential to increase the value of fisheries and other ecosystem services with minimal dam removals, and further increases are possible by including decisions related to dam operations and physical modifications. Run-of-river dams located near the head of tide are often found to be optimal for removal due to low hydroelectric capacity and high impact on fisheries. Conversely, dams with large impoundments near a river's headwaters can be less optimal for dam removal because their value as nitrogen sinks often outweighs the potential value for fisheries. Hydropower capacity is negatively impacted by dam removal but there are opportunities to meet or exceed lost capacity by upgrading preserved hydropower dams. Improving fish passage facilities for dams that are critical for safety or water storage can also reduce impacts on fisheries. Our

  11. The Influence of Dam Removal on Upland Soils

    Science.gov (United States)

    Lafrenz, M. D.; Bean, R. A.; Uthman, D.

    2011-12-01

    achieved at this location likely due to the coarse texture and corresponding low ripening value of the dewatered soils. Hence, native plants have not re-established in the new riparian area. The current resulting high levels of nitrogen in the upstream dewatered soil is anomalous for this region and could lead to colonization by non-native species in this and other newly dewatered ecosystems. Additionally, the lower sections of the dewatered upland soils are still saturated even though they stand perched several meters above the current floodplain; this evidence of reservoir "underflooding" will continue to affect soil development for an unknown amount of time and should be considered for any large dam removal project.

  12. Spatial distribution of heavy metal accumulation in the sediments after dam construction.

    Science.gov (United States)

    Shim, Moo Joon; Yang, Yun Mo; Oh, Da Yeon; Lee, Soo Hyung; Yoon, Yi Yong

    2015-12-01

    The sedimentary environment has been modified in the Geum River where an estuary dam and midstream dams were constructed. Furthermore, the Geum River tributaries deliver contaminants from the wastewater of an industrial complex. However, the influence of tributaries and dams on sedimentary metal deposition has not been extensively studied. The objectives of this study are to assess metal accumulation and to investigate the source of the metals. Sediments were collected in the main channel and two tributaries on October 2013. Abnormal accumulations of fine sediments were not observed above the midstream dams. Chromium, Ni, and Zn showed higher concentrations in above the midstream dam, but their concentrations were not related to grain size. Cadmium, Cu, Pb, and Hg were much higher upstream from the first midstream dam and came from one of the major tributaries. Arsenic was the only element found at higher concentrations downstream from the last midstream dam and was likely sourced from abandoned mines and/or agricultural activity. The pollution indexes indicated deposition of all metals, except Cr and Ni, may have been affected by anthropogenic activity. With respect to long-term accumulation of the metals, accumulation of Pb, Zn, and Cu by anthropogenic input largely increased, implying accumulation of these metals has continued due to anthropogenic activity since the estuary dam was constructed. Our results suggest that changes in river flow caused by the estuary dam and anthropogenic input from tributaries sources increased the accumulation of heavy metals (e.g., Pb, Zn, Cu, and As).

  13. Heavy metal enrichment in the riparian sediments and soils of the Three Gorges Reservoir, China

    Directory of Open Access Journals (Sweden)

    Q. Tang

    2015-03-01

    Full Text Available The Three Gorges Reservoir encompasses a riparian zone with a vertical height of 30 m and a total area of 349 km2 that has been subjected to alternate inundation and exposure due to regular impoundment. Sedimentation on the riparian landforms constitutes an important pathway for riverine contaminant redistribution. In an attempt to understand heavy metal enrichment since water inundation, riparian sediments and soils were sampled along five transects in a typical riparian zone composed of cultivated bench terraces in the middle reaches. Heavy metals (Cr, Ni, Cu, Zn, As, Cd and Pb were determined to characterize the lateral distribution and vertical transfer ratio. The results indicated that all heavy metals were enriched to varying extents both in the riparian sediments and soils, compared with regional background contents in soils and the reference levels in sediments. However, heavy metal levels in the riparian sediments were generally higher than those in the riparian soils, while those in the upper riparian soils (0–5 cm were overall slightly higher than those in the lower riparian soils (5–10 cm. There was a decreasing trend of heavy metal contents with increasing elevation. The elevated levels of heavy metals in the riparian sediments may be attributed to sediment yields from upstream anthropogenic sources, especially during major rainstorms in the wet season when large loads of contaminated sediment may be produced from diffuse source areas. Heavy metals can also be adsorbed to pure sediment in the course of mobilization or after deposition. Considering that the riparian soils are local weathering products without mobilization, the enrichment of heavy metals may principally be ascribed to chemical adsorption from dissolved fractions or vertical transfer from overlaid sediments. Heavy metal enrichment may further be affected by the specific type of hydrologic regime such that relatively long flooding duration caused by water

  14. Dam pre-release as an important operation strategy in reducing flood impact in Malaysia

    Directory of Open Access Journals (Sweden)

    Hidayah Ishak Nurul

    2018-01-01

    Full Text Available The 2014 flood was reported to be one of the worst natural disaster has ever affected several states in the northern part of Peninsular Malaysia. Overwhelming rainfall was noted as one of the main factors causing such impact, which was claimed to be unprecedented to some extent. The state of Perak, which is blessed with four cascading dams had also experienced flood damage at a scale that was considered the worst in history. The rainfall received had caused the dam to reach danger level that necessitated additional discharge to be released. Safety of the dams was of great importance and such unavoidable additional discharge was allowed to avoid catastrophic failure of the dam structures. This paper discusses the dam pre-release as a significant dam management strategy in reducing flood impact. An important balance between required dam storage to be maintained and the risk element that can be afforded is the crucial factor in such enhanced operation strategy. While further possibility in developing a carefully engineered dam pre-release strategy can be explored for dam operation in Malaysia, this has already been introduced in some developed countries. Australia and South Africa are examples where pre-release has been practiced and proven to reduce flood risk. The concept involves controlling the dam lake level throughout the year, in reference to the rainfall data and the hydrological properties for the catchment area of the dams. Plentiful data analysis need to be done in contemplation of producing the optimal pre-release model. The amount of heavy rainfalls received is beyond human control but the distribution of the discharge from the dams can be further managed with the appropriate pre-release strategy.

  15. Effects of dams and geomorphic context on riparian forests of the Elwha River, Washington

    Science.gov (United States)

    Shafroth, Patrick B.; Perry, Laura G; Rose, Chanoane A; Braatne, Jeffrey H

    2016-01-01

    Understanding how dams affect the shifting habitat mosaic of river bottomlands is key for protecting the many ecological functions and related goods and services that riparian forests provide and for informing approaches to riparian ecosystem restoration. We examined the downstream effects of two large dams on patterns of forest composition, structure, and dynamics within different geomorphic contexts and compared them to upstream reference conditions along the Elwha River, Washington, USA. Patterns of riparian vegetation in river segments downstream of the dams were driven largely by channel and bottomland geomorphic responses to a dramatically reduced sediment supply. The river segment upstream of both dams was the most geomorphically dynamic, whereas the segment between the dams was the least dynamic due to substantial channel armoring, and the segment downstream of both dams was intermediate due to some local sediment supply. These geomorphic differences were linked to altered characteristics of the shifting habitat mosaic, including older forest age structure and fewer young Populus balsamifera subsp. trichocarpa stands in the relatively static segment between the dams compared to more extensive early-successional forests (dominated by Alnus rubra and Salix spp.) and pioneer seedling recruitment upstream of the dams. Species composition of later-successional forest communities varied among river segments as well, with greater Pseudotsuga menziesii and Tsuga heterophylla abundance upstream of both dams, Acer spp. abundance between the dams, and P. balsamifera subsp. trichocarpa and Thuja plicata abundance below both dams. Riparian forest responses to the recent removal of the two dams on the Elwha River will depend largely on channel and geomorphic adjustments to the release, transport, and deposition of the large volume of sediment formerly stored in the reservoirs, together with changes in large wood dynamics.

  16. Dam pre-release as an important operation strategy in reducing flood impact in Malaysia

    Science.gov (United States)

    Hidayah Ishak, Nurul; Mustafa Hashim, Ahmad

    2018-03-01

    The 2014 flood was reported to be one of the worst natural disaster has ever affected several states in the northern part of Peninsular Malaysia. Overwhelming rainfall was noted as one of the main factors causing such impact, which was claimed to be unprecedented to some extent. The state of Perak, which is blessed with four cascading dams had also experienced flood damage at a scale that was considered the worst in history. The rainfall received had caused the dam to reach danger level that necessitated additional discharge to be released. Safety of the dams was of great importance and such unavoidable additional discharge was allowed to avoid catastrophic failure of the dam structures. This paper discusses the dam pre-release as a significant dam management strategy in reducing flood impact. An important balance between required dam storage to be maintained and the risk element that can be afforded is the crucial factor in such enhanced operation strategy. While further possibility in developing a carefully engineered dam pre-release strategy can be explored for dam operation in Malaysia, this has already been introduced in some developed countries. Australia and South Africa are examples where pre-release has been practiced and proven to reduce flood risk. The concept involves controlling the dam lake level throughout the year, in reference to the rainfall data and the hydrological properties for the catchment area of the dams. Plentiful data analysis need to be done in contemplation of producing the optimal pre-release model. The amount of heavy rainfalls received is beyond human control but the distribution of the discharge from the dams can be further managed with the appropriate pre-release strategy.

  17. A rapid method for determining chlorobenzenes in dam water systems

    African Journals Online (AJOL)

    A method using direct immersion solid phase microextraction (DI-SPME) coupled to gas chromatography equipped with a flame ionisation detector (GC-FID) was developed for the analysis of 7 chlorinated benzenes in dam water. The main parameters affecting the DI-SPME process were optimised. The optimised method ...

  18. A rapid method for determining chlorobenzenes in dam water systems

    African Journals Online (AJOL)

    2012-04-16

    Apr 16, 2012 ... A method using direct immersion solid phase microextraction (DI-SPME) coupled to gas chromatography equipped with a flame ionisation detector (GC-FID) was developed for the analysis of 7 chlorinated benzenes in dam water. The main parameters affecting the DI-SPME process were optimised.

  19. Spatial Forecast of Landslides in Three Gorges Based On Spatial Data Mining

    Directory of Open Access Journals (Sweden)

    Xianmin Wang

    2009-03-01

    Full Text Available The Three Gorges is a region with a very high landslide distribution density and a concentrated population. In Three Gorges there are often landslide disasters, and the potential risk of landslides is tremendous. In this paper, focusing on Three Gorges, which has a complicated landform, spatial forecasting of landslides is studied by establishing 20 forecast factors (spectra, texture, vegetation coverage, water level of reservoir, slope structure, engineering rock group, elevation, slope, aspect, etc. China-Brazil Earth Resources Satellite (Cbers images were adopted based on C4.5 decision tree to mine spatial forecast landslide criteria in Guojiaba Town (Zhigui County in Three Gorges and based on this knowledge, perform intelligent spatial landslide forecasts for Guojiaba Town. All landslides lie in the dangerous and unstable regions, so the forecast result is good. The method proposed in the paper is compared with seven other methods: IsoData, K-Means, Mahalanobis Distance, Maximum Likelihood, Minimum Distance, Parallelepiped and Information Content Model. The experimental results show that the method proposed in this paper has a high forecast precision, noticeably higher than that of the other seven methods.

  20. Phytogeographical analysis of the flora of Miljkovačka gorge in Eastern Serbia

    Directory of Open Access Journals (Sweden)

    Miljković, M.

    2012-12-01

    Full Text Available As a result of two-year investigation of the Miljkovacka gorge flora, carried out during the 2010. and 2011., 331 plant taxa belonging to 245 genera and 70 families were recorded and sorted into 112 floristic elements, 15 area groups and 9 area types. Phytogeographical analysis showed that the species of Eurasian area type are the most abundant ones.

  1. The Ironbridge Gorge Heritage Site and its local and regional functions

    Directory of Open Access Journals (Sweden)

    Cudny Waldemar

    2017-06-01

    Full Text Available The article is devoted to the issue of heritage and its functions. Based on the existing literature, the author presents the definition of heritage, the classification of heritage resources, and its most important impacts. The aim of the article was to show the functions that may be performed by a heritage site, locally and regionally. The example used by the author is the Ironbridge Gorge Heritage Site in the United Kingdom. Most heritage functions described by other authors are confirmed in this case study. The cultural heritage of the Ironbridge Gorge creates an opportunity to undertake various local and regional activities, having first of all an educational influence on the inhabitants, school youth and tourists. We must not ignore the economicinfluences, such as financing the activity of the Ironbridge Trust (the institution administering the site, generating income for local firms providing service to tourists, or for construction companies. This income helps to preserve and conserve the tangible heritage of the Ironbridge Gorge, as well as to generate jobs in heritage management, conservation and heritage tourism. Other effects of the Ironbridge Gorge Site include a socio-cultural impact or that related to sustainable development.

  2. Fire history reflects human history in the Pine Creek Gorge of north-central Pennsylvania

    Science.gov (United States)

    Patrick H. Brose; Richard P. Guyette; Joseph M. Marschall; Michael C. Stambaugh

    2015-01-01

    Fire history studies are important tools for understanding past fire regimes and the roles humans played in those regimes. Beginning in 2010, we conducted a fire history study in the Pine Creek Gorge area of north-central Pennsylvania to ascertain the number of fires and fire-free intervals, their variability through time, and the role of human influences. We collected...

  3. Spatial forecast of landslides in three gorges based on spatial data mining.

    Science.gov (United States)

    Wang, Xianmin; Niu, Ruiqing

    2009-01-01

    The Three Gorges is a region with a very high landslide distribution density and a concentrated population. In Three Gorges there are often landslide disasters, and the potential risk of landslides is tremendous. In this paper, focusing on Three Gorges, which has a complicated landform, spatial forecasting of landslides is studied by establishing 20 forecast factors (spectra, texture, vegetation coverage, water level of reservoir, slope structure, engineering rock group, elevation, slope, aspect, etc). China-Brazil Earth Resources Satellite (Cbers) images were adopted based on C4.5 decision tree to mine spatial forecast landslide criteria in Guojiaba Town (Zhigui County) in Three Gorges and based on this knowledge, perform intelligent spatial landslide forecasts for Guojiaba Town. All landslides lie in the dangerous and unstable regions, so the forecast result is good. The method proposed in the paper is compared with seven other methods: IsoData, K-Means, Mahalanobis Distance, Maximum Likelihood, Minimum Distance, Parallelepiped and Information Content Model. The experimental results show that the method proposed in this paper has a high forecast precision, noticeably higher than that of the other seven methods.

  4. Evolving fluvial response of the Sandy River, Oregon, following removal of Marmot Dam

    Science.gov (United States)

    Major, Jon J.; O'Connor, Jim; Podolak, Charles J.; Keith, Mackenzie K.; Spicer, Kurt R.; Wallick, J. Rose; Bragg, Heather M.; Pittman, Smokey; Wilcock, Peter R.; Rhode, Abagail; Grant, Gordon E.

    2010-01-01

    . Large stormflows in November 2008 and January 2009 eroded another 39,000 cubic meters of sediment. Thus, within 15 months of breaching, about 55 percent of the impounded sediment (390,000 cubic meters) had been eroded. Two years after breaching, only another 10,000 m3 (~400,000 m3 total) had been eroded. About 30 percent of the eroded sediment has been redeposited in a tapered wedge of sediment that extends 2 km from the former dam site to the entrance of a confined bedrock gorge. Much of the balance of the eroded sediment is distributed along and partly fills pools within the Sandy River gorge, a narrow bedrock canyon extending 2–9 km downstream of the former dam site, and along the channel farther downstream.

  5. Group prepares guidelines for documenting dam performance

    International Nuclear Information System (INIS)

    McCann, M.W. Jr.

    1993-01-01

    The Association of State Dam Safety Officials and the Center on the Performance of Dams at Stanford University later this summer expect to complete guidelines for reporting the performance of state, federal, and private dams: A working group of state and federal dam safety engineers and consultants is developing the guidelines to identify incidents that should be reported and to establish reporting requirements. The Federal Emergency Management Agency (FEMA) is funding preparation and publication of the guidelines. The guidelines are expected to expedite the process for reporting information on dam incidents in a timely and complete manner. Much the same as the health care industry compiles and evaluates data related to the incidence of disease and the benefits of treatment, a single standard for reporting the performance of dams in the US will help create a national information base on the occurrence and consequence of dam incidents. Currently, incidents involving dam performance are not reported on a regular basis. The guidelines will define dam incidents in terms of events of engineering interest that provide insights to the safety and structural or operational integrity of dams. Examples of incidents include the performance of a dam that experiences ground motion from a large earthquake, extreme spillway or dam overtopping, rehabilitations made to satisfy dam safety requirements, embankment sliding of an earthen dam, and improper operations that leads to damage downstream. When an incident occurs, the satisfactory or unsatisfactory performance of a dam will be reported, either by a state dam safety official, the owner of the dam, or the owner's engineer

  6. Spatial bedrock erosion distribution in a natural gorge

    Science.gov (United States)

    Beer, A. R.; Turowski, J. M.; Kirchner, J. W.

    2015-12-01

    Quantitative analysis of morphological evolution both in terrestrial and planetary landscapes is of increasing interest in the geosciences. In mountainous regions, bedrock channel formation as a consequence of the interaction of uplift and erosion processes is fundamental for the entire surface evolution. Hence, the accurate description of bedrock channel development is important for landscape modelling. To verify existing concepts developed in the lab and to analyse how in situ channel erosion rates depend on the interrelations of discharge, sediment transport and topography, there is a need of highly resolved topographic field data. We analyse bedrock erosion over two years in a bedrock gorge downstream of the Gorner glacier above the town of Zermatt, Switzerland. At the study site, the Gornera stream cuts through a roche moutonnée in serpentine rock of 25m length, 5m width and 8m depth. We surveyed bedrock erosion rates using repeat terrestrial laser scanning (TLS) with an average point spacing of 5mm. Bedrock erosion rates in direction of the individual surface normals were studied directly on the scanned point clouds applying the M3C2 algorithm (Lague et al., 2013, ISPRS). The surveyed erosion patterns were compared to a simple stream erosivity visualisation obtained from painted bedrock sections at the study location. Spatially distributed erosion rates on bedrock surfaces based on millions of scan points allow deduction of millimeter-scale mean annual values of lateral erosion, incision and downstream erosion on protruding streambed surfaces. The erosion rate on a specific surface point is shown to depend on the position of this surface point in the channel's cross section, its height above the streambed and its spatial orientation to the streamflow. Abrasion by impacting bedload was likely the spatially dominant erosion process, as confirmed by the observed patterns along the painted bedrock sections. However, a single plucking event accounted for the half

  7. Risk assessment for large Romanian dams situated on Bistrita and Siret Rivers

    Science.gov (United States)

    Moldovan, Iren-Adelina; Petruta Constantin, Angela; Popescu, Emilia; Toma-Danila, Dragos; Otilia Placinta, Anica

    2015-04-01

    The work will present an ongoing national Project that have as final goal to provide the local emergency services with warnings of a potential dam failure and ensuing flood as a result of a large earthquake occurrence, allowing further public training for evacuation. Probabilistic seismic hazard (PSH), vulnerability and risk studies in 6 counties from Moldova region including Izvorul Muntelui Dam, down on Bistrita and following on Siret River and theirs affluent will be accomplished during the project. A number of 5 large dams (the most vulnerable) will be studied in detail and flooding maps will be drawn to find the most exposed downstream localities both for risk assessment studies and warnings. The results will consist in local and regional seismic information, dams specific characteristics and locations, seismic hazard maps and risk classes, for all dams sites (for more than 30 dams), inundation maps (for the most vulnerable 5 dams from the region) and possible affected localities. The maps will provide the best available estimate of the general location and extent of dam failure inundation areas and will tell if a specific location lies within a dam failure inundation zone. Besides periodical technical inspections, the monitoring and the surveillance of dams' related structures and infrastructures, there are some more seismic specific requirements towards dams' safety. The most important one is the seismic risk assessment that can be accomplished by rating the dams into seismic risk classes using the theory of Bureau and Ballentine (2002), and Bureau (2003), taking into account the maximum expected peak ground motions at the dams site. In this paper we will obtain the ground motion parameters in the dams locations using probabilistic hazard assessment techniques, the structures vulnerability and the downstream risk characteristics (human, economical, historic and cultural heritage, etc) in the areas that might be flooded in the case of a dam failure, and will

  8. The effects of Herba Andrographitis hedgerows on soil erodibility and fractal features on sloping cropland in the Three Gorges Reservoir Area.

    Science.gov (United States)

    Chen, Jingjing; He, Binghui; Wang, Xiaoyan; Ma, Yun; Xi, Weimin

    2013-10-01

    To evaluate if hedgerows could improve the soil physicochemical properties and enhance the soil anti-scouring and anti-shearing capabilities, the effects of Herba Andrographitis hedgerows on soil erodibility and fractal features on sloping cropland in the Three Gorges Reservoir Area were investigated. Results showed that: (1) the clay particle accumulation around the hedgerows was significantly affected by the hedgerows; (2) the fractal dimension of soil particles was positively correlated with both silt and clay contents and had a negative linear correlation with sand content; (3) fine-grained content significantly influenced fractal dimension of the soil particles; (4) soil erodibility K was significantly and positively correlated with the sand content (correlation coefficient r=0.870), but significantly and negatively correlated with the silt content (r=-0.538), clay content (r=-0.739), organic carbon content (r=-0.603), the aggregation degree (r=-0.486), and soil fractal dimension (r=-0.538); and (5) the contents of organic matter and clay particles in the soil were found to be the effective indicators for soil erodibility at the Three Gorges Reservoir Area. The hedgerows may improve soil fractal features and decrease soil erodibility. The effective distance between hedgerows on a slope of 10° was less than 6 m.

  9. The Coupling Effect of Rainfall and Reservoir Water Level Decline on the Baijiabao Landslide in the Three Gorges Reservoir Area, China

    Directory of Open Access Journals (Sweden)

    Nenghao Zhao

    2017-01-01

    Full Text Available Rainfall and reservoir level fluctuation are two of the main factors contributing to reservoir landslides. However, in China’s Three Gorges Reservoir Area, when the reservoir water level fluctuates significantly, it comes at a time of abundant rainfall, which makes it difficult to distinguish which factor dominates the deformation of the landslide. This study focuses on how rainfall and reservoir water level decline affect the seepage and displacement field of Baijiabao landslide spatially and temporally during drawdown of reservoir water level in the Three Gorges Reservoir Area, thus exploring its movement mechanism. The monitoring data of the landslide in the past 10 years were analyzed, and the correlation between rainfall, reservoir water level decline, and landslide displacement was clarified. By the numerical simulation method, the deformation evolution mechanism of this landslide during drawdown of reservoir water level was revealed, respectively, under three conditions, namely, rainfall, reservoir water level decline, and coupling of the above two conditions. The results showed that the deformation of the Baijiabao landslide was the coupling effect of rainfall and reservoir water level decline, while the latter effect is more pronounced.

  10. Dams and Obstructions along Iowa's Canoe Routes

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This dataset represents obstruction to canoe and boat users of the canoe routes of Iowa. This may represent actual dams, rock dams (natural or man made), large...

  11. Simulation of Breach Outflow for Earthfill Dam

    International Nuclear Information System (INIS)

    Razad, Azwin Zailti Abdul; Muda, Rahsidi Sabri; Sidek, Lariyah Mohd; Azia, Intan Shafilah Abdul; Mansor, Faezah Hanum; Yalit, Ruzaimei

    2013-01-01

    Dams have been built for many reasons such as irrigation, hydropower, flood mitigation, and water supply to support development for the benefit of human. However, the huge amount of water stored behind the dam can seriously pose adverse impacts to the downstream community should it be released due to unwanted dam break event. To minimise the potential loss of lives and property damages, a workable Emergency Response Plan is required to be developed. As part of a responsible dam owner and operator, TNB initiated a study on dam breach modelling for Cameron Highlands Hydroelectric Scheme to simulate the potential dam breach for Jor Dam. Prediction of dam breach parameters using the empirical equations of Froehlich and Macdonal-Langridge-Monopolis formed the basis of the modelling, coupled with MIKE 11 software to obtain the breach outflow due to Probable Maximum Flood (PMF). This paper will therefore discuss the model setup, simulation procedure and comparison of the prediction with existing equations.

  12. Douglas County Dam Breach Inundation Areas

    Data.gov (United States)

    Kansas Data Access and Support Center — Dam breach analysis provides a prediction of the extent and timing of flooding from a catastrophic breach of the dams. These results are sufficient for developing...

  13. Marib Dam: the importance of environmental and health impact studies for development projects.

    Science.gov (United States)

    Basahi, I A

    2000-01-01

    Marib Dam was built without an environmental impact assessment study which created many conflicts. In 1995 and 1996 its impact on water quality, agriculture and groundwater recharge and socioeconomics was studied. Lake water could suffer severe eutrophication when floods are weak and algae growth is not controlled. Introducing Tilapia nilotica provided biological control of algae growth. The dam positively affected agriculture and groundwater within the designed irrigation scheme but negatively affected them beyond it. The dam also negatively affected health conditions and increased conflicts over water distribution. It positively affected women by allowing them to work in agriculture and participate in decision-making. The dam raised income levels of farmers and encouraged tourism.

  14. WinDAM C earthen embankment internal erosion analysis software

    Science.gov (United States)

    Two primary causes of dam failure are overtopping and internal erosion. For the purpose of evaluating dam safety for existing earthen embankment dams and proposed earthen embankment dams, Windows Dam Analysis Modules C (WinDAM C) software will simulate either internal erosion or erosion resulting f...

  15. Dams life; La vie des barrages

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The paper reports on the conclusions of decennial and annual inspections of French dams. Dams surveillance is performed by the operators and consists in visual examinations and measurements. Concrete dams, in particular, always have more or less developed fissures with water sweating threw the concrete mass or the foundations. Old concrete often show low swelling phenomena which are measured too. (J.S.)

  16. 76 FR 12094 - Whitman River Dam, Inc.

    Science.gov (United States)

    2011-03-04

    ... Dam, Inc. Notice of Application Tendered for Filing With the Commission and Soliciting Additional.... Project No.: 13237-002. c. Date Filed: February 14, 2011. d. Applicant: Whitman River Dam, Inc. e. Name of Project: Crocker Dam Hydro Project. f. Location: On the Whitman River, in the Town of Westminster...

  17. 78 FR 62627 - Sam Rayburn Dam Rate

    Science.gov (United States)

    2013-10-22

    ... DEPARTMENT OF ENERGY Southwestern Power Administration Sam Rayburn Dam Rate AGENCY: Southwestern... the power rate for the Sam Rayburn Dam (Rayburn) project pursuant to the Rayburn rate schedule (SRD-13..., Wholesale Rates for Hydro Power and Energy Sold to Sam Rayburn Dam Electric Cooperative, Inc. (Contract No...

  18. EVALUASI KEAMANAN DAM JATILUHUR BERBASIS INDEKS RESIKO

    Directory of Open Access Journals (Sweden)

    Avazbek Ishbaev

    2014-12-01

    Full Text Available The dams have very important roles to agricultural activities. Especially, West Java with 240,000 hectares of agricultural land, needs a good dam structure that can be used sustainably. Jatiluhur dam in Purwakarta, West Java is one of big dams in Indonesia which has important rules not only for Purwakarta but also for Jakarta, Karawang and Bekasi residents. A study and observation about safety and dam stability is needed to prevent any damage. The purpose of this research were to identify parameters that influenced dam safety and to evaluate dam reliability based on index tools. Analysis was done using risk index tools. The result showed that the condition of the dam of Jatiluhur is still satisfied with indicators, "Idam"-750. The total index risk was 127.22 and the safety factor was 83.04 out of 100. Therefore, Jatiluhur dam could be classified as safe and no need for particular treatments. Jatiluhur dam can be operated in normal condition or abnormal condition with periodic monitoring. Keywords: dam safety, evaluation, Jatiluhur Dam, risk index tools

  19. Beaver Dam Effects on Gravel Transport Patterns - a Case Study

    Science.gov (United States)

    Bunte, K.; Swingle, K. W.; Potyondy, J. P.; Abt, S. R.

    2011-12-01

    range of 120-150% Q1.55 for several weeks. During this time, gravel transport rates declined by three orders of magnitude, causing a pronounced hysteresis over the spring runoff season. The reason for the large hysteresis is attributed to the retention of gravel behind a mainly intact and impermeable beaver dam 700 ft above the study transect and subsequent limitation of bedload supply. Implications - gravel transport that is dominated by secondary flows around remnants of breached dams as well as by supply limitation below unbreached dams exhibits laterally concentrated gravel pathways and strong hysteresis effects, both of which make transport poorly predictable by conventional transport equations. Similarly, field measurements are problematic. Absent a season-long time series and full cross sectional measurements, results from occasional sampling within the highflow season probably cannot describe the relationship between flow and gravel transport rates. Given the large number of beaver-dominated streams, more studies on gravel transport and how it is affected by beaver dams would be useful.

  20. Large dams and risk management

    International Nuclear Information System (INIS)

    Cazelais, N.

    2003-01-01

    In July 1996, Quebec's Saguenay region was subjected to intensive rainfall which caused severe floods and uncontrolled release of several reservoirs, resulting in extensive damage to dam structures and reservoirs. The probability of occurrence for that disaster was 1:10,000. Following the disaster, the Quebec government established a dam management body entitled the Commission scientifique et technique sur la gestion des barrages, which pointed out several safety shortcomings of existing dams. Many were either very old or had undergone significant function change without being subsequently re-evaluated. A report by the Commission stated that damage following the floods could have been limited if the design and operating standards of the dams had been more stringent. A Dam Safety Act was adopted by the Quebec National Assembly on May 30, 2000 following recommendations to retain safer structures. The Act demands regular reporting of operating procedures. Seismic activity was noted as being a topic that requires in-depth examination since Quebec's St. Lawrence Valley, particularly the Charlevoix region, is one of Canada's largest seismic zones. The other is on the west coast in British Columbia. Earthquakes in Quebec are less intense than the ones in British Columbia, but they have higher frequency content which exerts a quasi-resonance wave effect which impacts roads, bridges, buildings and hydroelectric generating facilities. Hydro-Quebec is a public utility which owns 563 retaining structures, of which 228 are ranked as large dams that measure more than 15 metres high, 400 metres long and with a reservoir capacity of more than 1 million cubic metres of water. Hydro-Quebec addresses hydrological, seismic, technological and human risks through a dam safety procedure that includes structured plans for choosing best alternatives through staged exercises. Hazard levels are minimized through the adoption of emergency, prevention and alleviation measures. The utility

  1. In-reservoir behavior, dam passage, and downstream migration of juvenile Chinook salmon and juvenile steelhead from Detroit Reservoir and Dam to Portland, Oregon, February 2013-February 2014

    Science.gov (United States)

    Beeman, John W.; Adams, Noah S.

    2015-01-01

    than Chinook salmon. The primary factors affecting dam passage rates were seasonal dam operating conditions and diel period. Fish passage rates were much greater during the spring and summer than in the fall and winter, and the difference was attributed to the availability and use of the spillway near the top of the dam during the spring and summer. The flood-control purpose of the reservoir prevented spillway use during much of the fall and winter because of the low forebay elevation. Passage rates at night were greater than in the day during spring and summer (4.2 times) and during the fall and winter (14.9 times). Fish length, dam discharge, and forebay elevation also affected dam passage rates. Travel times from Detroit Dam passage to the downstream sites were shorter during the fall and winter than during the spring and summer, and were less than a median of 8.68 days to Portland. The estimated survival in the 11 kilometers (km) between Detroit Dam and the Minto Dam forebay was lower than in the remaining 241 km to the Portland site. Estimated survival per 100 km in the free-flowing reach from Minto Dam to Portland was 0.675–0.836, depending on species and season, and was similar to other free-flowing rivers in the Western United States. The high probability of fish in the reservoir reaching the dam, the chance for repeated presence near the dam, the fish depths, and the factors known to affect passage rates suggest that a properly designed surface passage route could be a viable downstream passage alternative for juvenile Chinook salmon and steelhead at Detroit Dam.

  2. Water Pollution Prediction in the Three Gorges Reservoir Area and Countermeasures for Sustainable Development of the Water Environment

    Science.gov (United States)

    Huang, Shuaijin; Qu, Xuexin

    2017-01-01

    The Three Gorges Project was implemented in 1994 to promote sustainable water resource use and development of the water environment in the Three Gorges Reservoir Area (hereafter “Reservoir Area”). However, massive discharge of wastewater along the river threatens these goals; therefore, this study employs a grey prediction model (GM) to predict the annual emissions of primary pollution sources, including industrial wastewater, domestic wastewater, and oily and domestic wastewater from ships, that influence the Three Gorges Reservoir Area water environment. First, we optimize the initial values of a traditional GM (1,1) model, and build a new GM (1,1) model that minimizes the sum of squares of the relative simulation errors. Second, we use the new GM (1,1) model to simulate historical annual emissions data for the four pollution sources and thereby test the effectiveness of the model. Third, we predict the annual emissions of the four pollution sources in the Three Gorges Reservoir Area for a future period. The prediction results reveal the annual emission trends for the major wastewater types, and indicate the primary sources of water pollution in the Three Gorges Reservoir Area. Based on our predictions, we suggest several countermeasures against water pollution and towards the sustainable development of the water environment in the Three Gorges Reservoir Area. PMID:29077006

  3. Water Pollution Prediction in the Three Gorges Reservoir Area and Countermeasures for Sustainable Development of the Water Environment.

    Science.gov (United States)

    Li, Yinghui; Huang, Shuaijin; Qu, Xuexin

    2017-10-27

    The Three Gorges Project was implemented in 1994 to promote sustainable water resource use and development of the water environment in the Three Gorges Reservoir Area (hereafter "Reservoir Area"). However, massive discharge of wastewater along the river threatens these goals; therefore, this study employs a grey prediction model (GM) to predict the annual emissions of primary pollution sources, including industrial wastewater, domestic wastewater, and oily and domestic wastewater from ships, that influence the Three Gorges Reservoir Area water environment. First, we optimize the initial values of a traditional GM (1,1) model, and build a new GM (1,1) model that minimizes the sum of squares of the relative simulation errors. Second, we use the new GM (1,1) model to simulate historical annual emissions data for the four pollution sources and thereby test the effectiveness of the model. Third, we predict the annual emissions of the four pollution sources in the Three Gorges Reservoir Area for a future period. The prediction results reveal the annual emission trends for the major wastewater types, and indicate the primary sources of water pollution in the Three Gorges Reservoir Area. Based on our predictions, we suggest several countermeasures against water pollution and towards the sustainable development of the water environment in the Three Gorges Reservoir Area.

  4. Water Pollution Prediction in the Three Gorges Reservoir Area and Countermeasures for Sustainable Development of the Water Environment

    Directory of Open Access Journals (Sweden)

    Yinghui Li

    2017-10-01

    Full Text Available The Three Gorges Project was implemented in 1994 to promote sustainable water resource use and development of the water environment in the Three Gorges Reservoir Area (hereafter “Reservoir Area”. However, massive discharge of wastewater along the river threatens these goals; therefore, this study employs a grey prediction model (GM to predict the annual emissions of primary pollution sources, including industrial wastewater, domestic wastewater, and oily and domestic wastewater from ships, that influence the Three Gorges Reservoir Area water environment. First, we optimize the initial values of a traditional GM (1,1 model, and build a new GM (1,1 model that minimizes the sum of squares of the relative simulation errors. Second, we use the new GM (1,1 model to simulate historical annual emissions data for the four pollution sources and thereby test the effectiveness of the model. Third, we predict the annual emissions of the four pollution sources in the Three Gorges Reservoir Area for a future period. The prediction results reveal the annual emission trends for the major wastewater types, and indicate the primary sources of water pollution in the Three Gorges Reservoir Area. Based on our predictions, we suggest several countermeasures against water pollution and towards the sustainable development of the water environment in the Three Gorges Reservoir Area.

  5. Research on Safety Factor of Dam Slope of High Embankment Dam under Seismic Condition

    Directory of Open Access Journals (Sweden)

    Li Bin

    2015-01-01

    Full Text Available With the constant development of construction technology of embankment dam, the constructed embankment dam becomes higher and higher, and the embankment dam with its height over 200m will always adopt the current design criteria of embankment dam only suitable for the construction of embankment dam lower than 200m in height. So the design criteria of high embankment dam shall be improved. We shall calculate the stability and safety factors of dam slope of high embankment dam under different dam height, slope ratio and different seismic intensity based on ratio of safety margin, and clarify the change rules of stability and safety factors of dam slope of high embankment dam with its height over 200m. We calculate the ratio of safety margin of traditional and reliable method by taking the stable, allowable and reliability index 4.2 of dam slope of high embankment dam with its height over 200m as the standard value, and conduct linear regression for both. As a result, the conditions, where 1.3 is considered as the stability and safety factors of dam slope of high embankment dam with its height over 200m under seismic condition and 4.2 as the allowable and reliability index, are under the same risk control level.

  6. Community involvement in dam breach exercises

    International Nuclear Information System (INIS)

    Cattanach, J.D.; Macdonald, E.G.; Mulligan, K.M.

    1993-01-01

    In 1986 British Columbia Hydro made a commitment to perform annual dam failure simulations based on the Emergency Preparedness Plans. Over the last 7 years nine such exercises have been completed. Each year the level of complexity of the exercises has increased, and along with it, the number of organizations outside of B.C. Hydro that participate in the exercise events has also increased. There has been a shift in attitudes, both internally and externally, towards these exercises. It is described how British Columbia Hydro was able to involve the communities downstream of its dams and encourage their participation in emergency planning and coordination. B.C. Hydro's process for involving a community in its emergency exercises starts with an invitation to the emergency coordinator in each affected community to attend an exercise planning meeting. Communities have occasionally declined to participate, the most common reasons being insufficiently developed emergency plans, budget prohibiting the cost of the exercise, or for political reasons. 2 refs., 1 tab

  7. Seismic hazard and risk assessment for large Romanian dams situated in the Moldavian Platform

    Science.gov (United States)

    Moldovan, Iren-Adelina; Popescu, Emilia; Otilia Placinta, Anica; Petruta Constantin, Angela; Toma Danila, Dragos; Borleanu, Felix; Emilian Toader, Victorin; Moldoveanu, Traian

    2016-04-01

    Besides periodical technical inspections, the monitoring and the surveillance of dams' related structures and infrastructures, there are some more seismic specific requirements towards dams' safety. The most important one is the seismic risk assessment that can be accomplished by rating the dams into seismic risk classes using the theory of Bureau and Ballentine (2002), and Bureau (2003), taking into account the maximum expected peak ground motions at the dams site - values obtained using probabilistic hazard assessment approaches (Moldovan et al., 2008), the structures vulnerability and the downstream risk characteristics (human, economical, historic and cultural heritage, etc) in the areas that might be flooded in the case of a dam failure. Probabilistic seismic hazard (PSH), vulnerability and risk studies for dams situated in the Moldavian Platform, starting from Izvorul Muntelui Dam, down on Bistrita and following on Siret River and theirs affluent will be realized. The most vulnerable dams will be studied in detail and flooding maps will be drawn to find the most exposed downstream localities both for risk assessment studies and warnings. GIS maps that clearly indicate areas that are potentially flooded are enough for these studies, thus giving information on the number of inhabitants and goods that may be destroyed. Geospatial servers included topography is sufficient to achieve them, all other further studies are not necessary for downstream risk assessment. The results will consist of local and regional seismic information, dams specific characteristics and locations, seismic hazard maps and risk classes, for all dams sites (for more than 30 dams), inundation maps (for the most vulnerable dams from the region) and possible affected localities. The studies realized in this paper have as final goal to provide the local emergency services with warnings of a potential dam failure and ensuing flood as a result of an large earthquake occurrence, allowing further

  8. Stability Analysis Of Earth Dam Slopes Subjected To Earthquake Using ERT Results Interpretation

    Directory of Open Access Journals (Sweden)

    Eko Andi Suryo

    2018-01-01

    Full Text Available Earth Dam stability can be affected significantly by the existence of excessive leakage. This is due to decreasing of shear strength of the dam material and additional overturning moment. In such scenario, the non-destructive soil investigation method is needed to analyze the stability of earth dam in current condition. This paper examines the use of Electrical Resistivity Tomography (ERT to investigate soil layers and to measure parameters of soil shear strength indirectly. First survey was carried out at dam crest and downstream using Wenner Configuration along profile lines at electrode spacing of 5 m. There were 5 profile lines of 180m long each and 10m distance of spacing. Furthermore, two profiles lines at weak cross-section based on its resistivity soil values were undertaken. Laboratory tests were conducted to determine relationship between resistivity value, moisture content, cohesion and angle of friction for each type of dam materials. From the ERT results and lab testing, a model dam can be obtained using current material parameters to perform stability analysis of dam subjected to earthquake. The lowest FOS was found at the upstream side about 1.15 and at the downstream side about 1.14 after applying seismic load of 100 years return period. Keywords: Stability Analysis, ERT,resistivity, leakage, dam

  9. Viewpoint – Brazil’s Madeira River Dams: A Setback for Environmental Policy in Amazonian Development

    Directory of Open Access Journals (Sweden)

    Philip Martin Fearnside

    2014-02-01

    Full Text Available Decisions on hydroelectric dam construction will be critical in shaping the future of Amazonia, where planned dams would convert most tributaries into chains of reservoirs. The Santo Antônio and Jirau dams, now nearing completion on the Madeira River, have created dangerous precedents in a trend towards weakening environmental protection in Brazil. Political appointees have overruled the technical staff of the Brazilian Institute for the Environment and Renewable Natural Resources (IBAMA, which is responsible for evaluating the environmental impact study (EIA and for licensing dams. Installation licences were granted without satisfying many of the 'conditions' that had been established as prerequisites. This feature and several others of the licensing process for the Madeira River dams have now been repeated in licensing the controversial Belo Monte Dam on the Xingu River. Brazil plans to build 30 large dams in its Amazon region in a decade, and others are to be financed and built by Brazil in Peru, Bolivia, Ecuador and Guyana. These plans affect virtually all water resources in an area larger than Western Europe. The Madeira River dams indicate the need to reform the decision-making process in Brazil.

  10. Self-potential investigation of moraine dam seepage

    Science.gov (United States)

    Moore, Jeffrey R.; Boleve, Alexandre; Sanders, Johnny W.; Glaser, Steven D.

    2011-08-01

    Self-potential (SP) and electrical resistivity measurements are used to investigate seepage at a remote moraine dam in the Sierra Nevada of California. The site is a small terminal moraine impounding roughly 300,000 m 3 of water at ~ 3400 m a.s.l. Suspicious fine sediment in a small lake at the dam's downstream toe prompted initial concerns that anomalous seepage may be eroding matrix material from the moraine. 235 individual SP measurements covering the surface of the dam were collected in order to investigate electrokinetic current sources resulting from seepage, while resistivity soundings probed moraine stratigraphy and suggest that the till contains interstitial ice. Contoured SP data reveal a non-uniform voltage distribution over the moraine dam and two distinct negative SP anomalies. The first, located in the central area of the moraine, shows a broad negative SP zone around the crest and increasingly positive SP moving downhill towards both the upstream and downstream toes. This anomaly can be explained by shallow gravitational groundwater flow in the near subsurface combined with upward groundwater flux through evapotranspiration; numerical simulation of the combined effect matches field data well. The second SP anomaly has a tightly localized distribution and can be explained by vertically descending flow into a bedrock fault conduit. Our conceptual seepage model suggests that flow travels from Dana Lake first at the boundary of ice-filled moraine and bedrock before converging on a concentrated channel in the subvertical fault zone. Positive SP near the dam abutments results from groundwater inflow from adjacent hillslopes. Combined analyses suggest that seepage erosion is not currently affecting the moraine dam, and that the sediment observed on the bed of the downstream toe lake is likely a remnant of past outflow events.

  11. Environmental risk assessment of a dam during construction phase

    Directory of Open Access Journals (Sweden)

    S. Rezaian

    2016-12-01

    Full Text Available The present study was conducted to assess the possible risks induced by construction of Gavi Dam in Ilam Province; western part of Iran, using MIKE-11 model and technique for order of preference by similarity to ideal solution. For this purpose, vulnerable zone of the dam site against the flooding risk of Gavi River was calculated for different return periods. The flooding zones were stimulated by MIKE-11 model. In order to check whether or not the dam construction could affect the quality of the Gavi River, the physicochemical quality of the river water was also tested. Afterwards, a questionnaire was prepared containing an inventory of possible risks supposed to be induced by construction of Gavi Dam. The questionnaires were placed at disposal of experts to score the items based on their importance. The questionnaires were then analyzed using SPSS Software, version 16. According to which, a total number of 12 risk factors were identified. The dam construction risks were qualitatively assessed by preliminary hazard analysis. Based on the results, 3 of 12 identified risks were recognized unacceptable. The shortlisted risks were prioritized at final step using technique for order of preference by similarity to ideal solution. "Habitat fragmentation" with a weight of 0.3002, "water pollution" with a weight of 0.295, and "impacts on aquatics" with a weight of 0.293 were identified as three top priority flooding risks. Among the most important corrective measures for mitigation of the risks at construction phase can be pointed to "restoration of the land cover", “conservation of areas surrounding the dam as a new wildlife habitat", “prevention of water contamination”, and "conservation of fish spawning sites".

  12. Remotely installed steam generator nozzle dam system

    International Nuclear Information System (INIS)

    Mc Donald, F.X.; Weisel, E.M.; Schukei, G.E.

    1990-01-01

    This patent describes a method for remotely installing a dam unit in a nozzle or a nuclear steam generator head, the head including a manway. It comprises: mounting an articulated manipulator to an internal surface of the head, the manipulator having a free end which carries a jaw member; positioning the manipulator so that the jaw member is adjacent the manway and substantially on the manway axis; passing a first dam segment through the manway and attaching the jaw member to the first segment; positioning the manipulator so that the jaw member holds the first dam segment on one side of the manway axis; passing a second dam segment through the manway into engagement with the first dam segment to form a dam subassembly; translating the manipulator through the head until the dam subassembly is adjacent the nozzle; advancing the jaw member toward the nozzle until the cam subassembly is positioned substantially at the desired location of the dam unit with respect to the nozzle; and deploying the manipulator to install dam support structure between the dam subassembly and the steam generator, thereby forming an installed dam unit

  13. The effect of exposure to hypergravity on pregnant rat dams, pregnancy outcome and early neonatal development

    Science.gov (United States)

    Ladd, B.; Nguon, K.; Sajdel-Sulkowska, E. M.

    2006-01-01

    We previously reported that hypergravity exposure affects food intake and mass gain during pregnancy. In the present study, we explored the hypothesis that changes in maternal body mass in hypergravity-exposed pregnant rat dams affect pregnancy outcome and early offspring development. Furthermore, we hypothesized that the changes observed at 1.5G will be magnified at higher gravity and by exposure during critical developmental periods. To test this hypothesis, we compared maternal body mass gain, food consumption, birth outcome and early offspring development between Sprague Dawley rat dams exposed to graded (1.5 1.75G) chronic hypergravity (HG) or rotation (rotational control, RC) on a 24-ft centrifuge for 22.5 h starting on gestational day (G) 10 with dams housed under identical conditions but not exposed to hypergravity (SC). We also compared maternal body mass, food consumption, birth outcome and early offspring development between rat dams exposed to 1.65G during different stages of pregnancy and nursing. Exposure to hypergravity resulted in transient loss in body mass and prolonged decrease in food consumption in HG dams, but the changes observed at 1.5G were not magnified at 1.65G or 1.75G. On the other hand RC dams gained more mass and consumed more food than SC dams. Exposure to hypergravity also affected pregnancy outcome as evidenced by decreased litter size, lowered neonatal mass at birth, and higher neonatal mortality; pregnancy outcome was not affected in RC dams. Neonatal changes evidenced by impaired righting response observed at 1.5G was magnified at higher gravity and was dependent on the period of hypergravity exposure. On the other hand, righting response was improved in RC neonates. Hypergravity exposure during early postpartum affected the food consumption of nursing mothers and affected early survival of their offspring. The changes observed in dams and neonates appear to be due to hypergravity exposure since animals exposed to the rotation

  14. Simulating potential structural and operational changes for Detroit Dam on the North Santiam River, Oregon-Interim Results

    Science.gov (United States)

    Buccola, Norman L.; Rounds, Stewart A.

    2011-01-01

    Prior to operational changes in 2007, Detroit Dam on the North Santiam River in western Oregon had a well-documented effect on downstream water temperature that was problematic for endangered salmonid fish species. In this U.S. Geological Survey study, done in cooperation with the U.S. Army Corps of Engineers, an existing calibrated CE-QUAL-W2 model of Detroit Lake (the impounded waterbody behind Detroit Dam) was used to determine how changes in dam operation or changes to the structural release points of Detroit Dam might affect downstream water temperatures under a range of historical hydrologic and meteorological conditions.

  15. Some thoughts on dam safety assessment: Small dams with not-so-small reservoirs

    International Nuclear Information System (INIS)

    Helwig, P.C.; Smith, W.L.

    1993-01-01

    There are about 300 dams in Newfoundland and Labrador of which only 9 are higher than 30 m. A significant number of these dams are less than 3 m in height yet retain appreciable volumes of water. Approaches to safety evaluations of these small dams vary considerably. Some authorities exclude such dams from mandatory inspections altogether, while others apply provisions that were clearly designed for more important structures. Neither approach is wholly satisfactory. Drawing on experience from inspection of over 100 mainly small dams, the issue is discussed and approaches to improve methods for dams safety evaluation of very small dams are suggested. Selection of design flood criteria, design guidelines, and reservoir flood standards are discussed. Newfoundland Power's dam safety assessment procedures for such dams are described. 8 refs., 2 figs., 3 tabs

  16. Study of Dam-break Due to Overtopping of Four Small Dams in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Zakaraya Alhasan

    2015-01-01

    Full Text Available Dam-break due to overtopping is one of the most common types of embankment dam failures. During the floods in August 2002 in the Czech Republic, several small dams collapsed due to overtopping. In this paper, an analysis of the dam break process at the Luh, Velký Bělčický, Melín, and Metelský dams breached during the 2002 flood is presented. Comprehensive identification and analysis of the dam shape, properties of dam material and failure scenarios were carried out after the flood event to assemble data for the calibration of a numerical dam break model. A simple one-dimensional mathematical model was proposed for use in dam breach simulation, and a computer code was compiled. The model was calibrated using the field data mentioned above. Comparison of the erodibility parameters gained from the model showed reasonable agreement with the results of other authors.

  17. Application of a Sediment Information System to the Three Gorges Project on Yangtze River, China

    Science.gov (United States)

    Cao, Shuyou; Liu, Xingnian; Yang, Kejun; Li, Changzhi

    Based on survey and analysis of a huge number of observed entrance sediment transport data and the research results of physical and numerical modeling of Three Gorges Reservoir on the Yangtze River, a sediment information system was designed. The basis of this system includes spatial data and properties of geographic elements, and various documents involved to the Three Gorges Project (TGP). Database and knowledge base are constructed as the information bank. The running environment is constructed by the general control program to realize requirements about various sediment information. The system chooses the window software as the system software. The techniques of graphical user interfaces and groupware geographic information system are applied in this system. In this phase, the emphases of the system are development of document system, map system, and presentation system. Cross-section system of the TGP was also attached. For further improvement of the system, a prepared interface of decision supporting subsystem is finished.

  18. [A survey on ecological environment of wild Adiantum reniforme var. sinense in Three Gorges Reservoir region].

    Science.gov (United States)

    Xie, Zhong-de; Jia, Han; Fu, Shao-Zhi; Gao, Wen-Yuan; Zhang, Zhi-Wei; Sun, Wei

    2017-11-01

    The study aims at investigating the ecological environment Adiantum reniforme var. sinense of in Three Gorges Reservoir region, and providing a reference basis for the protection of resources and artificial cultivation of A. reniforme var. sinense. By using the method of investigation, field survey and experimental analysis, the vegetation, natural geographical environment, climate, soil nutrients of A. reniforme var. sinense were studied and analyzed. The survey found that A. reniforme var. sinense distribution area reduced fast in Three Gorges region, a lot of distribution has diminished and vanished due to excessive digging, currently only in 3 towns of Wanzhou there exist 4 wild distribution areas. The growth of A. reniforme var. sinense needs an environment with low altitude, steep slope and thin soil, northeast slope, canopy height and warm and humid climate characteristics, and the soil in distribution has the characteristics of high organic matter, available nitrogen, available potassium, and low available phosphorus content. Copyright© by the Chinese Pharmaceutical Association.

  19. Dam methylation is required for efficient biofilm production in Salmonella enterica serovar Enteritidis.

    Science.gov (United States)

    Aya Castañeda, María del Rosario; Sarnacki, Sebastián Hernán; Noto Llana, Mariángeles; López Guerra, Adriana Gabriela; Giacomodonato, Mónica Nancy; Cerquetti, María Cristina

    2015-01-16

    The ecological success of Salmonella enterica to survive in different environments is due, in part, to the ability to form biofilms, something which is especially important for food industry. The aim of the current study was to evaluate the involvement of Dam methylation in biofilm production in S. Enteritidis strains. The ability to generate biofilms was analyzed in wild type and dam mutant strains. In S. Enteritidis, the absence of Dam affected the capacity to develop pellicles at the air-liquid interface and reduced the ability to form biofilm on polystyrene surfaces. Curli and cellulose production, determined by Congo red and calcofluor assays, were affected in dam mutant strains. Relative quantitative real-time PCR experiments showed that the expression of csgD and csgA genes is reduced in mutants lacking dam gene with respect to the wild type strains, whereas transcript levels of bcsA are not affected in the absence of Dam. To our knowledge, this is the first report on the participation of Dam methylation on biofilm production in Enteritidis or any other serovar of S. enterica. Results presented here suggest that changes in gene expression required for biofilm production are finely regulated by Dam methylation. Thus, Dam methylation could modulate csgD expression and upregulate the expression of factors related with biofilm production, including curli and cellulose. This study contributes to the understanding of biofilm regulation in Salmonella spp. and to the design of new strategies to prevent food contamination and humans and animals infections. Copyright © 2014. Published by Elsevier B.V.

  20. Safety and security monitoring of dams using nano-micromachined-based surface acoustic wave (SAW) sensors

    Science.gov (United States)

    Ross, Wayne, Jr.; Saafi, Mohamed; Romine, Peter; Xiao, Zhigang; Pett, Dave

    2006-03-01

    Concerns about the safety of concrete dams have increased during recent years, partly because the population at risk in locations downstream of major dams continues to expand and also because these old dams are experiencing long-term damage and the seismic design concepts used to build them were inadequate. Reliable techniques for continuous monitoring of certain key parameters affecting the dams' integrity are currently nonexistent and this is because of the lack of sensing technology capable to function in a hostile environment such as low temperatures and high moisture level. This paper presents new low cost, passive and wireless micro-machined SAW-based sensors to monitor the safety and security of dams. These SAW sensors are composed of MEMS transducers, Nano-polymer actuators and an antenna, and are deposited on a thin film substrate. The sensors are passive, do not require power on-board and can be interrogated wireless using a radar. When embedded into concrete dams, the devices will be able to detect and locate internal cracks and measure certain key parameters affecting the durability of dams such as temperature, moisture, pH, chloride and carbon dioxide.

  1. Effects of open mouth and rubber dam on upper airway patency and breathing.

    Science.gov (United States)

    Iwatani, Kazuhiro; Matsuo, Koichiro; Kawase, Soichiro; Wakimoto, Nina; Taguchi, Akira; Ogasawara, Tadashi

    2013-06-01

    Rubber dams increase the quality and safety of dental treatment. However, the condition of a rubber dam over an open mouth may also obstruct the route for respiration. We tested whether an open mouth with or without a rubber dam would affect upper airway patency and breathing pattern. Twenty young healthy volunteers were imaged with a magnetic resonance (MR) system under three conditions: mouth closed, mouth open, and rubber dam with mouth open. Respiration was concurrently monitored with plethysmography. MRI slices of the upper airway were obtained at 5-mm thicknesses, and the size of the cross-sectional area of the upper airway was measured by image analysis software. Respiratory cycle duration and tidal volume were also measured with digital signal analysis software. The volume of the upper airway became significantly decreased with the mouth open. Analysis of each cross-sectional area of the upper airway revealed that while the oropharyngeal area was significantly narrower with an open mouth, the retropalatal and hypopharyngeal areas were not affected. Placing a rubber dam had no additional influence on upper airway patency but was seen to significantly shorten mean respiratory duration and decrease tidal volume. Open mouth position plays the largest role in decreased upper airway patency, and open mouth position with a rubber dam may further disrupt breathing pattern. Breathing pattern may become deteriorated by airway obstruction during dental treatments requiring a rubber dam.

  2. Linking Ah receptor mediated effects of sediments and impacts on fish to key pollutants in the Yangtze Three Gorges Reservoir, China - A comprehensive perspective.

    Science.gov (United States)

    Floehr, Tilman; Scholz-Starke, Björn; Xiao, Hongxia; Hercht, Hendrik; Wu, Lingling; Hou, Junli; Schmidt-Posthaus, Heike; Segner, Helmut; Kammann, Ulrike; Yuan, Xingzhong; Roß-Nickoll, Martina; Schäffer, Andreas; Hollert, Henner

    2015-12-15

    The Three Gorges Reservoir (TGR), created in consequence of the Yangtze River's impoundment by the Three Gorges Dam, faces numerous anthropogenic impacts that challenge its unique ecosystem. Organic pollutants, particularly aryl hydrocarbon receptor (AhR) agonists, have been widely detected in the Yangtze River, but only little research was yet done on AhR-mediated activities. Hence, in order to assess effects of organic pollution, with particular focus on AhR-mediated activities, several sites in the TGR area were examined applying the "triad approach". It combines chemical analysis, in vitro, in vivo and in situ investigations to a holistic assessment. Sediments and the benthic fish species Pelteobagrus vachellii were sampled in 2011/2012, respectively, to identify relevant endpoints. Sediment was tested in vitro with the ethoxyresorufin-O-deethylase (EROD) induction assay, and in vivo with the Fish Embryo Toxicity Test and Sediment Contact Assay with Danio rerio. Activities of phase I (EROD) and phase II (glutathione-S-transferase) biotransformation enzymes, pollutant metabolites and histopathological alterations were studied in situ in P. vachellii. EROD induction was tested in vitro and in situ to evaluate possible relationships. Two sites, near Chongqing and Kaixian city, were identified as regional hot-spots and further investigated in 2013. The sediments induced in the in vitro/in vivo bioassays AhR-mediated activities and embryotoxic/teratogenic effects - particularly on the cardiovascular system. These endpoints could be significantly correlated to each other and respective chemical data. However, particle-bound pollutants showed only low bioavailability. The in situ investigations suggested a rather poor condition of P. vachellii, with histopathological alterations in liver and excretory kidney. Fish from Chongqing city exhibited significant hepatic EROD induction and obvious parasitic infestations. The polycyclic aromatic hydrocarbon (PAH) metabolite 1

  3. Impacts of Climate Change and Human Activities on the Three Gorges Reservoir Inflow

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2017-12-01

    Full Text Available Identifying changes in runoff and quantifying the impacts of climate change and human activities are of great significance for water resources planning and management in a river basin. In this study, an inflow series of the Three Gorges Reservoir observed from 1951 to 2016 is used to identify the trend and abrupt change point by using statistical methods. Based on the meteorological data, soil type data, and land use data during the same period, the Soil and Water Assessment Tool (SWAT model is established to quantitatively attribute changes in the Three Gorges Reservoir inflow to climate change and human activities separately and discuss the differences between the two-stage method, which divides the whole study period into two stages to analyze the reasons for runoff evolution, and multi-stage method, which divides the whole study period into more stages to consider the temporal and spatial variation of land use/cover (LULC. The results show: (1 During the study period, a significant decrease is detected in the Three Gorges Reservoir inflow and the decrease rate is 7.7 km3 per ten years, annual total precipitation decreases by −13.5 mm per ten years, and annual average temperature increases by 0.1 °C per ten years. (2 Contribution of climate change and human activities is around 7:3. Climate change is the main reason for the decrease in the Three Gorges Reservoir inflow. (3 Results of stages in multi-stage method are different from the result of two-stage method. Accumulative results of multi-stage method and result of two-stage method are consistent. There are some changes in results of every stage, which are different from the accumulative results.

  4. Crotch Lake dam rehabilitation project

    International Nuclear Information System (INIS)

    Brunet, G.; Dobrowolski, E.

    1999-01-01

    Replacement of the existing wood crib dam structure on Crotch Lake on the Mississippi River in eastern Ontario that provided water storage for the power production at High Falls Generating Station, became necessary when it was determined that the dam did not meet Ontario-Hydro's safety standards. This paper describes the project of replacing the existing structure with a PVC coated gabion wall with waterproofing. The entire structure was covered with three layers of wire mesh, laced together, and criss-crossed for superior strength and rigidity. The work was completed in 28 days with no environmental impact . Life expectancy of the new structure is in excess of 40 years. With periodic maintenance of the gabion mat cover, life span could be extended an additional 20 to 40 years. 5 figs

  5. The Big Data Processing Algorithm for Water Environment Monitoring of the Three Gorges Reservoir Area

    Directory of Open Access Journals (Sweden)

    Yuanchang Zhong

    2014-01-01

    Full Text Available Owing to the increase and the complexity of data caused by the uncertain environment, the water environment monitoring system in Three Gorges Reservoir Area faces much pressure in data handling. In order to identify the water quality quickly and effectively, this paper presents a new big data processing algorithm for water quality analysis. The algorithm has adopted a fast fuzzy C-means clustering algorithm to analyze water environment monitoring data. The fast clustering algorithm is based on fuzzy C-means clustering algorithm and hard C-means clustering algorithm. And the result of hard clustering is utilized to guide the initial value of fuzzy clustering. The new clustering algorithm can speed up the rate of convergence. With the analysis of fast clustering, we can identify the quality of water samples. Both the theoretical and simulated results show that the algorithm can quickly and efficiently analyze the water quality in the Three Gorges Reservoir Area, which significantly improves the efficiency of big data processing. What is more, our proposed processing algorithm provides a reliable scientific basis for water pollution control in the Three Gorges Reservoir Area.

  6. A new horned crocodile from the Plio-Pleistocene hominid sites at Olduvai Gorge, Tanzania.

    Directory of Open Access Journals (Sweden)

    Christopher A Brochu

    Full Text Available BACKGROUND: The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular "horns" over the ears and a relatively deep snout, these resemble those of the recently extinct Malagasy crocodile Voay robustus, but the new species lacks features found among osteolaemines and shares derived similarities with living species of Crocodylus. METHODOLOGY/PRINCIPAL FINDINGS: The holotype consists of a partial skull and skeleton and was collected on the surface between two tuffs dated to approximately 1.84 million years (Ma, in the same interval near the type localities for the hominids Homo habilis and Australopithecus boisei. It was compared with previously-collected material from Olduvai Gorge referable to the same species. Phylogenetic analysis places the new form within or adjacent to crown Crocodylus. CONCLUSIONS/SIGNIFICANCE: The new crocodile species was the largest predator encountered by our ancestors at Olduvai Gorge, as indicated by hominid specimens preserving crocodile bite marks from these sites. The new species also reinforces the emerging view of high crocodylian diversity throughout the Neogene, and it represents one of the few extinct species referable to crown genus Crocodylus.

  7. Seismic Analysis of Gravity Dams.

    Science.gov (United States)

    method of analysis with the results produced by the well-known program EADHI. A new simplified method of analysis was developed using the finite element method of analysis to determine the dam’s inertial response along with Chopra’s simplified procedure for estimating the hydrodynamic loading. This new approach was implemented in a user-friendly computer program. The program was tested against a wide variety of problems and found to produce acceptable results. A sample run using this

  8. Environmental monitoring at Olympic Dam

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    The environmental management and protection program at the Olympic Dam uranium/copper/gold project, Roxby Downs, South Australia, monitors eight major environmental parameters - meteorology, vegetation, mine site rehabilitation, fauna, terrain, soil salinity, hydrogeology and well fields. It came into effect with the approval of the South Australian Government in March 1987. The Great Artesian Basin, one of the world's greatest artesian basins, is the source of the water supply for the project

  9. Mitigating Dam Impacts Using Environmental Flow Releases

    Science.gov (United States)

    Richter, B. D.

    2017-12-01

    One of the most ecologically disruptive impacts of dams is their alteration of natural river flow variability. Opportunities exist for modifying the operations of existing dams to recover many of the environmental and social benefits of healthy ecosystems that have been compromised by present modes of dam operation. The potential benefits of dam "re-operation" include recovery of fish, shellfish, and other wildlife populations valued both commercially and recreationally, including estuarine species; reactivation of the flood storage and water purification benefits that occur when floods are allowed to flow into floodplain forests and wetlands; regaining some semblance of the naturally dynamic balance between river erosion and sedimentation that shapes physical habitat complexity, and arresting problems associated with geomorphic imbalances; cultural and spiritual uses of rivers; and many other socially valued products and services. Assessing the potential benefits of dam re-operation begins by characterizing the dam's effects on the river flow regime, and formulating hypotheses about the ecological and social benefits that might be restored by releasing water from the dam in a manner that more closely resembles natural flow patterns. These hypotheses can be tested by implementing a re-operation plan, tracking the response of the ecosystem, and continually refining dam operations through adaptive management. This presentation will highlight a number of land and water management strategies useful in implementing a dam re-operation plan, with reference to a variety of management contexts ranging from individual dams to cascades of dams along a river to regional energy grids. Because many of the suggested strategies for dam re-operation are predicated on changes in the end-use of the water, such as reductions in urban or agricultural water use during droughts, a systemic perspective of entire water management systems will be required to attain the fullest possible

  10. Severe situation of rural nonpoint source pollution and efficient utilization of agricultural wastes in the Three Gorges Reservoir Area.

    Science.gov (United States)

    Zhang, Tong; Ni, Jiupai; Xie, Deti

    2015-11-01

    Rural nonpoint source (NPS) pollution caused by agricultural wastes has become increasingly serious in the Three Gorges Reservoir Area (TGRA), significantly affecting the reservoir water quality. The grim situation of rural NPS pollution in the TGRA indicated that agrochemicals (chemical fertilizer and pesticide) were currently the highest contributor of rural NPS pollution (50.38%). The harmless disposal rates of livestock excrement, crop straws, rural domestic refuse, and sewage also cause severe water pollution. More importantly, the backward agricultural economy and the poor environmental awareness of farmers in the hinterland of the TGRA contribute to high levels of rural NPS pollution. Over the past decade, researchers and the local people have carried out various successful studies and practices to realize the effective control of rural NPS pollution by efficiently utilizing agricultural wastes in the TGRA, including agricultural waste biogas-oriented utilization, crop straw gasification, decentralized land treatment of livestock excrement technology, and crop straw modification. These technologies have greatly increased the renewable resource utilization of agricultural wastes and improved water quality and ecological environment in the TGRA.

  11. Accuracy Analysis of a Dam Model from Drone Surveys

    Science.gov (United States)

    Buffi, Giulia; Venturi, Sara

    2017-01-01

    This paper investigates the accuracy of models obtained by drone surveys. To this end, this work analyzes how the placement of ground control points (GCPs) used to georeference the dense point cloud of a dam affects the resulting three-dimensional (3D) model. Images of a double arch masonry dam upstream face are acquired from drone survey and used to build the 3D model of the dam for vulnerability analysis purposes. However, there still remained the issue of understanding the real impact of a correct GCPs location choice to properly georeference the images and thus, the model. To this end, a high number of GCPs configurations were investigated, building a series of dense point clouds. The accuracy of these resulting dense clouds was estimated comparing the coordinates of check points extracted from the model and their true coordinates measured via traditional topography. The paper aims at providing information about the optimal choice of GCPs placement not only for dams but also for all surveys of high-rise structures. The knowledge a priori of the effect of the GCPs number and location on the model accuracy can increase survey reliability and accuracy and speed up the survey set-up operations. PMID:28771185

  12. Accuracy Analysis of a Dam Model from Drone Surveys

    Directory of Open Access Journals (Sweden)

    Elena Ridolfi

    2017-08-01

    Full Text Available This paper investigates the accuracy of models obtained by drone surveys. To this end, this work analyzes how the placement of ground control points (GCPs used to georeference the dense point cloud of a dam affects the resulting three-dimensional (3D model. Images of a double arch masonry dam upstream face are acquired from drone survey and used to build the 3D model of the dam for vulnerability analysis purposes. However, there still remained the issue of understanding the real impact of a correct GCPs location choice to properly georeference the images and thus, the model. To this end, a high number of GCPs configurations were investigated, building a series of dense point clouds. The accuracy of these resulting dense clouds was estimated comparing the coordinates of check points extracted from the model and their true coordinates measured via traditional topography. The paper aims at providing information about the optimal choice of GCPs placement not only for dams but also for all surveys of high-rise structures. The knowledge a priori of the effect of the GCPs number and location on the model accuracy can increase survey reliability and accuracy and speed up the survey set-up operations.

  13. Accuracy Analysis of a Dam Model from Drone Surveys.

    Science.gov (United States)

    Ridolfi, Elena; Buffi, Giulia; Venturi, Sara; Manciola, Piergiorgio

    2017-08-03

    This paper investigates the accuracy of models obtained by drone surveys. To this end, this work analyzes how the placement of ground control points (GCPs) used to georeference the dense point cloud of a dam affects the resulting three-dimensional (3D) model. Images of a double arch masonry dam upstream face are acquired from drone survey and used to build the 3D model of the dam for vulnerability analysis purposes. However, there still remained the issue of understanding the real impact of a correct GCPs location choice to properly georeference the images and thus, the model. To this end, a high number of GCPs configurations were investigated, building a series of dense point clouds. The accuracy of these resulting dense clouds was estimated comparing the coordinates of check points extracted from the model and their true coordinates measured via traditional topography. The paper aims at providing information about the optimal choice of GCPs placement not only for dams but also for all surveys of high-rise structures. The knowledge a priori of the effect of the GCPs number and location on the model accuracy can increase survey reliability and accuracy and speed up the survey set-up operations.

  14. Selection of tolerable risk criteria for dam safety decision making

    International Nuclear Information System (INIS)

    Nielsen, N.M.; Hartford, D.N.D.; MacDonald, T.F.

    1994-01-01

    Risk assessment has received increasing attention in recent years as a means of aiding decision making on dams by providing systematic and rational methods for dealing with risk and uncertainty. Risk assessment is controversial and decisions affecting risk to life are the most controversial. Tolerable criteria, based on the risks that society is prepared to accept in order to avoid excessive costs, set bounds within which risk-based decisions may be made. The components of risk associated with dam safety are addressed on an individual basis and criteria established for each component, thereby permitting flexibility in the balance between component risk and avoiding the problems of placing a monetary value on life. The guiding principle of individual risk is that dams do not impose intolerable risks on any individual. A risk to life of 1 in 10 4 per annum is generally considered the maximum tolerable risk. When considering societal risk, the safety of a dam should be proportional to the consequences of its failure. Risks of financial losses beyond the corporation's ability to finance should be so low as to be considered negligible. 17 refs., 3 figs

  15. Modelling the relationship between water level and vertical displacements on the Yamula Dam, Turkey

    OpenAIRE

    Bayrak , T.

    2007-01-01

    International audience; Monitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the study is to find the extent to which rising reservoir level affects the mechanism of deformation of The Yamula Dam under certain change in the reservoir level conditions during to the first filling period. Three different deformation analysis techniques, namely static, kinematic and dynamic, were used to analyze four geodetic monit...

  16. Monitoring thermal pollution in rivers downstream of dams with Landsat ETM+ thermal infrared images

    OpenAIRE

    Ling, Feng; Foody, Giles; Du, Hao; Ban, Xuan; Li, Xiaodong; Zhang, Yihang; Du, Yun

    2017-01-01

    Dams play a significant role in altering the spatial pattern of temperature in rivers and contribute to thermal pollution, which greatly affects the river aquatic ecosystems. Understanding the temporal and spatial variation of thermal pollution caused by dams is important to prevent or mitigate its harmful effect. Assessments based on in-situ measurements are often limited in practice because of the inaccessibility of water temperature records and the scarcity of gauges along rivers. By contr...

  17. Environmental effects of the Big Rapids dam remnant removal, Big Rapids, Michigan, 2000-02

    Science.gov (United States)

    Healy, Denis F.; Rheaume, Stephen J.; Simpson, J. Alan

    2003-01-01

    The U.S. Geological Survey (USGS), in cooperation with the city of Big Rapids, investigated the environmental effects of removal of a dam-foundation remnant and downstream cofferdam from the Muskegon River in Big Rapids, Mich. The USGS applied a multidiscipline approach, which determined the water quality, sediment character, and stream habitat before and after dam removal. Continuous water-quality data and discrete water-quality samples were collected, the movement of suspended and bed sediment were measured, changes in stream habitat were assessed, and streambed elevations were surveyed. Analyses of water upstream and downstream from the dam showed that the dam-foundation remnant did not affect water quality. Dissolved-oxygen concentrations downstream from the dam remnant were depressed for a short period (days) during the beginning of the dam removal, in part because of that removal effort. Sediment transport from July 2000 through March 2002 was 13,800 cubic yards more at the downstream site than the upstream site. This increase in sediment represents the remobilized sediment upstream from the dam, bank erosion when the impoundment was lowered, and contributions from small tributaries between the sites. Five habitat reaches were monitored before and after dam-remnant removal. The reaches consisted of a reference reach (A), upstream from the effects of the impoundment; the impoundment (B); and three sites below the impoundment where habitat changes were expected (C, D, and E, in downstream order). Stream-habitat assessment reaches varied in their responses to the dam-remnant removal. Reference reach A was not affected. In impoundment reach B, Great Lakes and Environmental Assessment Section (GLEAS) Procedure 51 ratings went from fair to excellent. For the three downstream reaches, reach C underwent slight habitat degradation, but ratings remained good; reach D underwent slight habitat degradation with ratings changing from excellent to good; and, in an area

  18. Exporting dams: China's hydropower industry goes global.

    Science.gov (United States)

    McDonald, Kristen; Bosshard, Peter; Brewer, Nicole

    2009-07-01

    In line with China's "going out" strategy, China's dam industry has in recent years significantly expanded its involvement in overseas markets. The Chinese Export-Import Bank and other Chinese financial institutions, state-owned enterprises, and private firms are now involved in at least 93 major dam projects overseas. The Chinese government sees the new global role played by China's dam industry as a "win-win" situation for China and host countries involved. But evidence from project sites such as the Merowe Dam in Sudan demonstrates that these dams have unrecognized social and environmental costs for host communities. Chinese dam builders have yet to adopt internationally accepted social and environmental standards for large infrastructure development that can assure these costs are adequately taken into account. But the Chinese government is becoming increasingly aware of the challenge and the necessity of promoting environmentally and socially sound investments overseas.

  19. Automated data acquisition for dam monitoring

    International Nuclear Information System (INIS)

    Koopmans, R.; Jakubick, A.T.

    1990-01-01

    Automated data acquisition for dam monitoring is crucial to emergency response, allows frequent readings without increased labour and cost, allows monitoring of instrument response to changing environmental and physical influences, enables direct computer acquisition of data, and has numerous other advantages. The experience of Ontario Hydro, British Columbia Hydro, and other utilities with automated data acquisition systems is described. Details are provided of remote monitoring systems, instrumentation, data loggers, tape cassette backup, power sources, data transmission equipment, modems and telephone networks, computers and peripherals, and system performance. The utility's plans for future expansion of the systems are described. Utility experience with the automated systems is also described for Clarence Dam, Bath County Pumped Storage Station, Scott Dam, and Vermillion Dam in the U.S., Ajaure Dam in Sweden, and ENEL Dam in the Valtellina area of Italy. 17 refs., 2 figs

  20. In the Land of the Dammed: Assessing Governance in Resettlement of Ghana’s Bui Dam Project

    Directory of Open Access Journals (Sweden)

    Kwabena Asiama

    2017-11-01

    Full Text Available Resettlement resulting from dam construction has raised several concerns due to the negative aftermath impacts. In Ghana, the construction of three hydroelectric dams resulted in large-scale resettlements. Given the little experience that Ghana has in resettlements, it is necessary for a robust monitoring structure for resettlements. However, this was not available in the last resettlement undertaken for the Bui Dam Project. This paper aims at developing an assessment framework for monitoring resettlement activities on customary lands from a good governance perspective. Based on four good governance principles, transparency, public participation and inclusiveness, equity and rule of law and accountability, a good governance assessment framework is built and applied to the Bui Dam Project using a case study approach. Data were collected through interviews and focus group discussion with the key actors of the resettlement project. It was first found that the planning stage of the resettlement came out with a robust plan that was to prevent the impoverishment of the affected persons. However, in the implementation of the resettlement, not all good governance principles were adhered to. In conclusion, it was found that by deconstructing the resettlement process with a good governance framework, the problematic areas of the resettlement can be effectively differentiated between the planning and implementation phases.

  1. Measurement of Dam Deformations: Case Study of Obruk Dam (Turkey)

    Science.gov (United States)

    Gulal, V. Engin; Alkan, R. Metin; Alkan, M. Nurullah; İlci, Veli; Ozulu, I. Murat; Tombus, F. Engin; Kose, Zafer; Aladogan, Kayhan; Sahin, Murat; Yavasoglu, Hakan; Oku, Guldane

    2016-04-01

    In the literature, there is information regarding the first deformation and displacement measurements in dams that were conducted in 1920s Switzerland. Todays, deformation measurements in the dams have gained very different functions with improvements in both measurement equipment and evaluation of measurements. Deformation measurements and analysis are among the main topics studied by scientists who take interest in the engineering measurement sciences. The Working group of Deformation Measurements and Analysis, which was established under the International Federation of Surveyors (FIG), carries out its studies and activities with regard to this subject. At the end of the 1970s, the subject of the determination of fixed points in the deformation monitoring network was one of the main subjects extensively studied. Many theories arose from this inquiry, as different institutes came to differing conclusions. In 1978, a special commission with representatives of universities has been established within the FIG 6.1 working group; this commission worked on the issue of determining a general approach to geometric deformation analysis. The results gleaned from the commission were discussed at symposiums organized by the FIG. In accordance with these studies, scientists interested in the subject have begun to work on models that investigate cause and effect relations between the effects that cause deformation and deformation. As of the scientist who interest with the issue focused on different deformation methods, another special commission was established within the FIG engineering measurements commission in order to classify deformation models and study terminology. After studying this material for a long time, the official commission report was published in 2001. In this prepared report, studies have been carried out by considering the FIG Engineering Surveying Commission's report entitled, 'MODELS AND TERMINOLOGY FOR THE ANALYSIS OF GEODETIC MONITORING OBSERVATIONS

  2. Three Dimensional Seepage Analyses in Mollasadra Dam after Its ...

    African Journals Online (AJOL)

    Mollasadra dam is an earth fill dam with a clayey core and a height of 72 m from river bed, constructed on Kor River. pore water pressure in the dam was investigated following its construction and first and second impoundments. The dam was modeled by a finite element mesh. After the first and second dam impoundments, ...

  3. Global Reservoir and Dam Database, Version 1 (GRanDv1): Dams, Revision 01

    Data.gov (United States)

    National Aeronautics and Space Administration — The Global Reservoir and Dam Database, Version 1 (Revision 01) contains 6,862 records of reservoirs and their associated dams with a cumulative storage capacity of...

  4. Global Reservoir and Dam Database, Version 1 (GRanDv1): Dams, Revision 01

    Data.gov (United States)

    National Aeronautics and Space Administration — The Global Reservoir and Dam Database, Version 1, Revision 01 (v1.01) contains 6,862 records of reservoirs and their associated dams with a cumulative storage...

  5. Studies of water leakage in dams. Course

    International Nuclear Information System (INIS)

    Cordero-Calderon, C.F.

    1995-01-01

    With this training about the study of Water Leakage in Dams and Damming, the institutional worker will have the necessary criteria in this topic, and also an opportunity to analyze the impact of this engineering work at national level. This course permits to transmit part of the knowlege acquired by the Arcal XVIII RLA/8/018, Application of Tracer Techniques for Leakage in Dams and Damming Project, where ICE participates in agreement with Atomic Energy Commission of Costa Rica, sponsored by the International Organization of Atomic Energy. (author). 14 charts, 36 figs, 2 maps, 6 tabs

  6. Dam safety management in Victoria (Australia)

    International Nuclear Information System (INIS)

    Adem, J.

    1996-01-01

    The Victoria state government's decision to make dam owners accountable for safety and upkeep of their dams was reported. To give effect to this decision a series of guidelines have been developed which outline the required activities and skills to ensure that dams are properly managed within a framework of 'light-handed' regulation. The guidelines are also intended to ensure that dam management becomes an integral part of the business decision making process, not just a set of prescribed technical procedures. Details of the direction being taken and the proposed controls to ensure compliance with national and international standards were described. 4 refs., 2 figs

  7. Risk assessment of a hydraulic fill dam

    International Nuclear Information System (INIS)

    Cattanach, J. D.; Stewart, R. A.

    1996-01-01

    The concerns expressed about the safety of the 85 year old 29 m hydraulic Coquitlam Dam in the Greater Vancouver area were described. Because of these concerns, and despite the fact that the dam meets the Incremental Hazard Classification criteria, B.C. Hydro carried out an evaluation with risk assessment. The processes employed and the results of the evaluation were described. It was found that although the dam was safe enough, in light of experiences with other dams, further evaluations will have to be carried out to verify these results. 2 refs., 6 figs

  8. Seismic analysis of high arch dams considering contraction-peripheral joints coupled effects

    Science.gov (United States)

    Hariri-Ardebili, Mohammad; Mirzabozorg, Hasan; Kianoush, M.

    2013-09-01

    Dam-reservoir interaction is one of the classic coupled problems in which two various environments with different physical characteristics are in contact with each other on interface boundary. Consideration of such interaction is important in design of new dams as well as on safety evaluation of the existing ones. In the present study, the effect of hydrodynamic pressures at various reservoir operational levels on seismic behavior of an arch dam is investigated. Dez ultra-high arch dam in Iran was selected as case study and all contraction and peripheral joints were simulated using node-to-node contact elements which have the ability of opening/closing and tangential movement. In addition, stage construction effects including joint grouting based on available construction reports were considered. The reservoir was assumed to be compressible and the foundation rock was modeled to account for its flexibility. The TABAS earthquake record was used to excite the finite element model of dam-reservoir-foundation system. It was found that dam-reservoir interaction has significant structural effects on the system and generally, operating the considered arch dam at different water levels can highly affects the distribution of the crack prone area under the maximum credible earthquake.

  9. A simplified water temperature model for the Colorado River below Glen Canyon Dam

    Science.gov (United States)

    Wright, S.A.; Anderson, C.R.; Voichick, N.

    2009-01-01

    Glen Canyon Dam, located on the Colorado River in northern Arizona, has affected the physical, biological and cultural resources of the river downstream in Grand Canyon. One of the impacts to the downstream physical environment that has important implications for the aquatic ecosystem is the transformation of the thermal regime from highly variable seasonally to relatively constant year-round, owing to hypolimnetic releases from the upstream reservoir, Lake Powell. Because of the perceived impacts on the downstream aquatic ecosystem and native fish communities, the Glen Canyon Dam Adaptive Management Program has considered modifications to flow releases and release temperatures designed to increase downstream temperatures. Here, we present a new model of monthly average water temperatures below Glen Canyon Dam designed for first-order, relatively simple evaluation of various alternative dam operations. The model is based on a simplified heat-exchange equation, and model parameters are estimated empirically. The model predicts monthly average temperatures at locations up to 421 km downstream from the dam with average absolute errors less than 0.58C for the dataset considered. The modelling approach used here may also prove useful for other systems, particularly below large dams where release temperatures are substantially out of equilibrium with meteorological conditions. We also present some examples of how the model can be used to evaluate scenarios for the operation of Glen Canyon Dam.

  10. Modelling the relationship between water level and vertical displacements on the Yamula Dam, Turkey

    Directory of Open Access Journals (Sweden)

    T. Bayrak

    2007-01-01

    Full Text Available Monitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the study is to find the extent to which rising reservoir level affects the mechanism of deformation of The Yamula Dam under certain change in the reservoir level conditions during to the first filling period. Three different deformation analysis techniques, namely static, kinematic and dynamic, were used to analyze four geodetic monitoring records consisting of vertical displacements of nine object points established on the Dam and six reference points surrounding of it, to see whether the rising reservoir level have a role in the vertical deformations during the first filling period. The largest vertical displacements were in the middle of the dam. There is an apparent linear relationship between the dam subsidence and the reservoir level. A dynamic deformation model was developed to model this situation. The model infers a causative relationship between the reservoir level and the dam deformations. The analysis of the results determines the degree of the correlation between the change in the reservoir level and the observed structural deformation of the dam.

  11. Physicochemical Characteristics of River Water Downstream of a Large Tropical Hydroelectric Dam

    Directory of Open Access Journals (Sweden)

    Teck-Yee Ling

    2016-01-01

    Full Text Available Water quality in the downstream river of a hydroelectric dam may be affected by the structural design and operation. To date, little is known about the water quality downstream of the largest dam in Malaysia, the Bakun hydroelectric dam. Therefore, the objective of the study was to determine the water quality downstream of the dam when the spillway was closed and when it was opened. Results of the study indicate that the dam plays a significant role in regulating the water quality downstream of it. When the spillway was closed, pH and oxygen were lower in the river where DO was below 5 mg/L. When the spillway was opened, the water quality improved in terms of oxygen content (>8.0 mg/L, total sulphide (TS, and chemical oxygen demand (COD but deteriorated in terms of five-day biochemical oxygen demand (BOD5, total ammonia nitrogen (TAN, and total phosphorus (TP. Additionally, the intensity of the impacts, particularly BOD5, COD, and TAN, shows a declining trend as distance from the dam increases. This study shows that impacts on the water quality extend to a distance of 32 km from the dam particularly turbidity and DO and opening the spillway changes the water quality significantly.

  12. The Influence of an EPS Concrete Buffer Layer Thickness on Debris Dams Impacted by Massive Stones in the Debris Flow

    Directory of Open Access Journals (Sweden)

    Xianbin Yu

    2015-01-01

    Full Text Available The failure of debris dams impacted by the massive stones in a debris flow represents a difficult design problem. Reasonable materials selection and structural design can effectively improve the resistance impact performance of debris dams. Based on the cushioning properties of expanded polystyrene (EPS concrete, EPS concrete as a buffer layer poured on the surface of a rigid debris dam was proposed. A three-dimensional numerical calculation model of an EPS concrete buffer layer/rigid debris dam was established. The single-factor theory revealed change rules for the thickness of the buffer layer concerning the maximal impact force of the rigid debris dam surface through numerical simulation. Moreover, the impact force-time/history curves under different calculation conditions for the rigid debris dam surface were compared. Simulation results showed that the EPS concrete buffer layer can not only effectively extend the impact time of massive stones affecting the debris dam but also reduce the impact force of the rigid debris dam caused by massive stones in the debris flow. The research results provide theoretical guidance for transferring the energy of the massive stone impact, creating a structural design and optimizing debris dams.

  13. A ravenous river reclaims its true course: the tale of Marmot Dam''s demise

    Science.gov (United States)

    Noreen Parks; Gordon Grant

    2009-01-01

    Removing dams that are outdated, unsafe, or pose significant economic or environmental costs has emerged in the last 10 years as a major river restoration strategy. The removal of the 45-foot-high Marmot Dam on the Sandy River in 2007 resulted in the biggest sediment release accompanying any dam removal to date. It also provided an unprecedented opportunity...

  14. A review of proposed Glen Canyon Dam interim operating criteria

    Energy Technology Data Exchange (ETDEWEB)

    LaGory, K.; Hlohowskyj, I.; Tomasko, D.; Hayse, J.; Durham, L.

    1992-04-01

    Three sets of interim operating criteria for Glen Canyon Dam on the Colorado River have been proposed for the period of November 1991, to the completion of the record of decision for the Glen Canyon Dam environmental impact statement (about 1993). These criteria set specific limits on dam releases, including maximum and minimum flows, up-ramp and down-ramp rates, and maximum daily fluctuation. Under the proposed interim criteria, all of these parameters would be reduced relative to historical operating criteria to protect downstream natural resources, including sediment deposits, threatened and endangered fishes, trout, the aquatic food base, and riparian plant communities. The scientific bases of the three sets of proposed operating criteria are evaluated in the present report:(1) criteria proposed by the Research/Scientific Group, associated with the Glen Canyon Environmental Studies (GCES); (2) criteria proposed state and federal officials charged with managing downstream resources; and (3) test criteria imposed from July 1991, to November 1991. Data from Phase 1 of the GCES and other sources established that the targeted natural resources are affected by dam operations, but the specific interim criteria chosen were not supported by any existing studies. It is unlikely that irreversible changes to any of the resources would occur over the interim period if historical operating criteria remained in place. It is likely that adoption of any of the sets of proposed interim operating criteria would reduce the levels of sediment transport and erosion below Glen Canyon Dam; however, these interim criteria could result in some adverse effects, including the accumulation of debris at tributary mouths, a shift of new high-water-zone vegetation into more flood-prone areas, and further declines in vegetation in the old high water zone.

  15. Assessment of check-dam groundwater recharge with water-balance calculations

    Science.gov (United States)

    Djuma, Hakan; Bruggeman, Adriana; Camera, Corrado; Eliades, Marinos

    2017-04-01

    Studies on the enhancement of groundwater recharge by check-dams in arid and semi-arid environments mainly focus on deriving water infiltration rates from the check-dam ponding areas. This is usually achieved by applying simple water balance models, more advanced models (e.g., two dimensional groundwater models) and field tests (e.g., infiltrometer test or soil pit tests). Recharge behind the check-dam can be affected by the built-up of sediment as a result of erosion in the upstream watershed area. This natural process can increase the uncertainty in the estimates of the recharged water volume, especially for water balance calculations. Few water balance field studies of individual check-dams have been presented in the literature and none of them presented associated uncertainties of their estimates. The objectives of this study are i) to assess the effect of a check-dam on groundwater recharge from an ephemeral river; and ii) to assess annual sedimentation at the check-dam during a 4-year period. The study was conducted on a check-dam in the semi-arid island of Cyprus. Field campaigns were carried out to measure water flow, water depth and check-dam topography in order to establish check-dam water height, volume, evaporation, outflow and recharge relations. Topographic surveys were repeated at the end of consecutive hydrological years to estimate the sediment built up in the reservoir area of the check dam. Also, sediment samples were collected from the check-dam reservoir area for bulk-density analyses. To quantify the groundwater recharge, a water balance model was applied at two locations: at the check-dam and corresponding reservoir area, and at a 4-km stretch of the river bed without check-dam. Results showed that a check-dam with a storage capacity of 25,000 m3 was able to recharge to the aquifer, in four years, a total of 12 million m3 out of the 42 million m3 of measured (or modelled) streamflow. Recharge from the analyzed 4-km long river section without

  16. Olympic Dam - the first decade

    International Nuclear Information System (INIS)

    Newton, A.W.; Wilson, M.A.; Harris, J.

    1988-01-01

    Most aspects of the pre-production phase of the Olympic Dam Project, from commencement of exploration in May 1975 through to commitment to development in December 1985 are documented here. The discovery by Western Mining Corporation Ltd of copper mineralisation on Roxby Downs Station in July 1975 has led to one of the more intensive base-metal exploration programmes undertaken in Australia. Comprehensive exploration, evaluation and feasibility studies between 1975 and 1985 have delineated a probable 450 million tonnes of higher grade ore containing 2.5% copper, 0.8 kg/t uranium oxide, 0.6 g/t gold and 6.0 g/t silver. The total resource is estimated at 2 billion tonnes containing 1.6% copper, 0.6 kg/t uranium oxide, 0.6 g/t gold and 3.5 g/t silver. At 31 December 1985, over 540 km of surface and underground drilling had been completed, comprising over 700 surface drillholes totalling 234 km of core and 218 km of open-hole drilling, and about 900 underground diamond-drillholes totalling 90 km. The Whenan Shaft had been sunk to 500 m and driving on three levels totalled almost 10 km. More than one million tonnes of ore and mullock were raised during development. A pilot treatment plant commissioned on site produced concentrates, matte and blister copper, and ammonium diuranate. Following a technical study of the Olympic Dam Project, completed in March 1985, and a subsequent economic feasibility study, it was announced on 11 June 1985 that the initial project was considered to be commercially viable. On 8 December 1985, the joint venturers, Western Mining Corporation Holdings Ltd (51%) and the BP Group (49%), announced their commitment to the Project. An appendix lists the important events that occurred between January 1986 and December 1987 in bringing Olympic Dam to the production state. 26 refs., 17 figs., 5 tabs., ills

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

    Science.gov (United States)

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

    2018-03-01

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

  18. Proceedings of the Canadian dam safety conference

    International Nuclear Information System (INIS)

    1993-01-01

    A conference was held to discuss dam safety. Papers were presented concerning public policy and legislative issues, standards, guidelines and criteria, dam safety reviews, operations and maintenance, technical issues, and case histories. Separate abstracts have been prepared for 18 papers from the conference

  19. The environmental and social acceptability of dams

    OpenAIRE

    Boyé, Henri; Vivo, Michel de

    2016-01-01

    Dams are an ever more vital tool for addressing our growing water needs and the emergence of new challenges such as sustainable development and climate change. However, these infrastructures are still highly controversial around the world. Citing numerous examples, this paper goes over the main points of debate around dams, and the necessary conditions for securing their acceptability.

  20. Descriptive characteristics of the large Italian dams

    International Nuclear Information System (INIS)

    Dello Vicario, E.; Petaccia, A.; Savanella, V.

    1999-01-01

    In the present note the characteristics of the Italian dams are examined, underlining, in a statistical view, story, geographical location, types and use of the most important works. Such a review can be useful for a more detailed analysis, both for the dams characterization and for further studies relevant to water resources utilization [it

  1. Proceedings of the CDSA/CANCOLD Joint Dam Safety Conference

    International Nuclear Information System (INIS)

    1997-01-01

    The 1997 conference on large dams was co-sponsored by the Canadian Dam Safety Association and the Canadian National Committee of the International Commission on Large Dams. The conference was held in Montreal in September. A total of 31 papers were presented in seven sessions. Session One was devoted to the 1996 Saguenay Floods, while other sessions dealt with risk management in relation to dams, dam safety programs, embankment dams, and monitoring of dams. A two-part session dealt with issues related to the construction and repair of concrete dams. refs., figs

  2. The Impact of Dam-Reservoir-Foundation Interaction on Nonlinear Response of Concrete Gravity Dams

    Science.gov (United States)

    Amini, AliReza; Motamedi, Mohammad Hossein; Ghaemian, Mohsen

    2008-07-01

    To study the impact of dam-reservoir-foundation interaction on nonlinear response of concrete gravity dams, a two-dimensional finite element model of a concrete gravity dam including the dam body, a part of its foundation and a part of the reservoir was made. In addition, the proper boundary conditions were used in both reservoir and foundation in order to absorb the energy of outgoing waves at the far end boundaries. Using the finite element method and smeared crack approach, some different seismic nonlinear analyses were done and finally, we came to a conclusion that the consideration of dam-reservoir-foundation interaction in nonlinear analysis of concrete dams is of great importance, because from the performance point of view, this interaction significantly improves the nonlinear response of concrete dams.

  3. The Impact of Dam-Reservoir-Foundation Interaction on Nonlinear Response of Concrete Gravity Dams

    International Nuclear Information System (INIS)

    Amini, Ali Reza; Motamedi, Mohammad Hossein; Ghaemian, Mohsen

    2008-01-01

    To study the impact of dam-reservoir-foundation interaction on nonlinear response of concrete gravity dams, a two-dimensional finite element model of a concrete gravity dam including the dam body, a part of its foundation and a part of the reservoir was made. In addition, the proper boundary conditions were used in both reservoir and foundation in order to absorb the energy of outgoing waves at the far end boundaries. Using the finite element method and smeared crack approach, some different seismic nonlinear analyses were done and finally, we came to a conclusion that the consideration of dam-reservoir-foundation interaction in nonlinear analysis of concrete dams is of great importance, because from the performance point of view, this interaction significantly improves the nonlinear response of concrete dams

  4. Restoring Environmental Flows by Modifying Dam Operations

    Directory of Open Access Journals (Sweden)

    Brian D. Richter

    2007-06-01

    Full Text Available The construction of new dams has become one of the most controversial issues in global efforts to alleviate poverty, improve human health, and strengthen regional economies. Unfortunately, this controversy has overshadowed the tremendous opportunity that exists for modifying the operations of existing dams to recover many of the environmental and social benefits of healthy ecosystems that have been compromised by present modes of dam operation. The potential benefits of dam "re-operation" include recovery of fish, shellfish, and other wildlife populations valued both commercially and recreationally, including estuarine species; reactivation of the flood storage and water purification benefits that occur when floods are allowed to flow into floodplain forests and wetlands; regaining some semblance of the naturally dynamic balance between river erosion and sedimentation that shapes physical habitat complexity, and arresting problems associated with geomorphic imbalances; cultural and spiritual uses of rivers; and many other socially valued products and services. This paper describes an assessment framework that can be used to evaluate the benefits that might be restored through dam re-operation. Assessing the potential benefits of dam re-operation begins by characterizing the dam's effects on the river flow regime, and formulating hypotheses about the ecological and social benefits that might be restored by releasing water from the dam in a manner that more closely resembles natural flow patterns. These hypotheses can be tested by implementing a re-operation plan, tracking the response of the ecosystem, and continually refining dam operations through adaptive management. The paper highlights a number of land and water management strategies useful in implementing a dam re-operation plan, with reference to a variety of management contexts ranging from individual dams to cascades of dams along a river to regional energy grids. Because many of the

  5. Olympic Dam project: assessment of the environmental impact

    International Nuclear Information System (INIS)

    1983-11-01

    The assessment report on the Environmental Impact Statement produced for the Olympic Dam project is intended to provide the South Australian Government with a comprehensive evaluation of the potential impact of the proposal and to make recommendations concerning the project to be negotiated with the Joint Venturers prior to approval of the EIS. The project involves the mining, processing and sale of products from the copper-uranium ore body at Olympic Dam on the Roxby Downs Station, South Australia. The report includes a description of the proposal, a description of the environment likely to be affected, a discussion of the potential impacts on that environment, a discussion of the adequacy of information presented in the EIS and a discussion of the acceptability of the environmental impacts. The Department has concluded that the pre-design proposal is acceptable on environmental grounds

  6. The Production of Organic Nitrates in Portland, Oregon and the Columbia River Gorge

    Science.gov (United States)

    Neill, Holly Ann

    This work studied the production of aerosol-phase organic nitrates in both Portland and the Columbia River Gorge (CRG). Ozone and NO x species were investigated for correlation with organic nitrate aerosol, as they function as precursors to the production of organic nitrates. These ambient gas-phase measurements were collected in the same locations as high-volume (Hi-Vol) filters samples, in an urban and rural gorge setting to investigate correlations at the origin of the pollution plume and downwind. A novel Soxhlet extraction method for Hi-Vol filters was developed based on literature and EPA standard methods. Analysis for nitrate production was done by segregating data based on times when the wind blew out of Portland and down the CRG versus times when flow was not westerly. Filters were then compared to ambient gas-phase measurements and derived NO3 radical production rates to look for trends. Wind direction had a strong influence on the concentrations of precursor molecules in the CRG. On days with a westerly wind direction into the gorge, concentrations of the measure aerosol organic nitrates were similar at both sides. This suggests some contribution of a broader regional production of organic nitrates. There was some correlation between the production rate of NO3 radicals and the measured organic nitrate aerosol, suggesting a role for NO3 + VOC production of organic nitrates that later partition to the aerosol phase. This information will better illuminate the fate of nitrogen downwind of pollution sources. The information will also help to create a better understanding of the way topography and meteorological conditions can influence the flow of pollution. Understanding the downwind oxidative chemistry that happens in the CRG would better support both pollution prevention and mitigation efforts..

  7. Groundwater Forecasting Optimization Pertain to Dam Removal

    Science.gov (United States)

    Brown, L.; Berthelote, A. R.

    2011-12-01

    There is increasing interest in removing dams due to changing ecological and societal values. Groundwater recharge rate is closely connected to reservoir presence or absence. With the removal of dams and their associated reservoirs, reductions in groundwater levels are likely to impact water supplies for domestic, industrial and agricultural use. Therefore accessible economic and time effective tools to forecast groundwater level declines with acceptable uncertainty following dam removals are critical for public welfare and healthy regional economies. These tools are also vital to project planning and provide beneficial information for restoration and remediation managements. The standard tool for groundwater forecasting is 3D Numerical modeling. Artificial Neural Networks (ANNs) may be an alternative tool for groundwater forecasting pertain to dam removal. This project compared these two tools throughout the Milltown Dam removal in Western Montana over a five year period. It was determined that ANN modeling had equal or greater accuracy for groundwater forecasting with far less effort and cost involved.

  8. Research progress on dam-break floods

    KAUST Repository

    Wu, Jiansong

    2011-08-01

    Because of the catastrophic effects downstream of dam-break failure, more and more researchers around the world have been working on the study of dam-break flows to accurately forecast the downstream inundation mapping. With the rapid development of computer hardware and computing techniques, numerical study on dam-break flows has been a popular research subject. In the paper, the numerical methodologies used to solve the governing partial differential equations of dam-break flows are classified and summarized, and their characteristics and applications are discussed respectively. Furthermore, the fully-developed mathematical models developed in recent decades are reviewed, and also introduced the authors\\' on-going work. Finally, some possible future developments on modeling the dam-break flows and some solutions are presented and discussed. © 2011 IEEE.

  9. 'Dam it - it's easy!' - or is it?

    Science.gov (United States)

    Marshall, K

    2017-06-09

    Dentists the world over seem to still have issues in making rubber dam application a routine part of practice, even in situations where patients are obviously at risk. In this article, the author - who has delivered hundreds of seminars and hands on tuition in a quick and easy method of dam application (the 'Dam it - it's Easy!' series) to dentists in the UK, Europe, North America and Asia - highlights the similarity of the misconceptions existing in regard to its use by dentists the world over. The valuable advantages to the environment in the dental treatment room by dental dam application are considered underused. The protection offered by routine rubber dam application is second to none in situations that are potentially physically hazardous to patients.

  10. 3D coexisting modes of thermal convection in the faulted Lower Yarmouk Gorge

    Science.gov (United States)

    Magri, Fabien; Inbar, Nimrod; Möller, Peter; Raggad, Marwan; Rödiger, Tino; Rosenthal, Eliyahu; Siebert, Christian

    2016-04-01

    Numerical investigations of 3D modes of large-scale convection in faulted aquifers are presented with the aim to infer possible transport mechanisms supporting the formation of thermal springs in the Lower Yarmouk Gorge (LYG), at the border between Israel and Jordan. The transient finite elements models are based on a geological model of the LYG that introduces more realistic structural features of the basin, compared to previous existing models of the area (Magri et al., submitted). The sensitivity analysis of the fault permeability showed that faults cross-cutting the main regional flow direction allow groundwater to be driven laterally by convective forces within the fault planes. Therein thermal waters can either discharge along the fault traces or exit the fault through adjacent permeable aquifers. The location of springs can migrate with time, is not strictly constrained to the damage zones and reflects the interplay between the wavelength of the multicellular regime in the fault zone and the regional flow toward discharge areas in the lowlands. The results presented here suggest that in the LYG case, crossing flow paths result from the coexistence of fault convection, that can develop for example along NE-SW oriented faults within the Gorge, and additional flow fields that can be induced either by topography N-S gradients, e.g. perpendicular to the major axe of the Gorge, or by local thermal convection in permeable aquifers below Eocene aquiclude. The sensitivity analysis is consistent with the analytical solutions based on viscous-dependent Rayleigh theory. It indicates that in the LYG coexisting transport processes likely occur at fault hydraulic conductivity ranging between 2.3e-7 m/s and 9.3e- 7 m/s (i.e. 7 m/yr and 30 m/yr). The LYG numerical example and the associated Rayleigh analysis can be applied to study the onset of thermal convection and resulting flow patterns of any fractured hydrothermal basin. References Magri F, Möller S, Inbar N, M

  11. 3D Coupled Thermal-Hydraulic Model of the Lower Yarmouk Gorge, Jordan Rift Valley

    Science.gov (United States)

    Walther, M.; Magri, F.; Inbar, N.; Möller, P.; Raggad, M.; Rödiger, T.; Rosenthal, E.; Shentsis, I.; Siebert, C.; Volpi, G.

    2017-12-01

    It is supposed that the Lower Yarmouk Gorge (LYG), in the Jordan Rift Valley acts as the mixing zone of two crossing flow pathways: N-S from the Hermon Mountains and from the Ajlun Dome, and E-W from Jebel al Arab Mountain in Syria (also known as Huran Plateau or Yarmouk drainage basin). As a result, several springs can be found within the gorge. These are characterized by widespread temperatures (20 - 60 °C) which indicate that, beside the complex regional flow, also ascending thermal waters control the hydrologic behavior of the LYG. Previous simulations based on a conceptual simplified 3D model (Magri et al., 2016) showed that crossing flow paths result from the coexistence of convection, that can develop for example along NE-SW oriented faults within the gorge or in permeable aquifers below Maastrichtian aquiclude, and additional flow fields that are induced by the N-S topographic gradients. Here we present the first 3D hydrogeological model of the entire LYG that includes structural features based on actual logs and interpreted seismic lines from both Israeli and Jordanian territories. The model distinguishes seven units from upper Eocene to the Lower Triassic, accounting for major aquifers, aquicludes and deep-cutting faults. Recharges are implemented based on the numerical representation developed by Shentsis (1990) that considers relationships between mean annual rain and topographic elevation. The model reveals that topography-driven N-S and E-W flows strongly control the location of discharge areas while the anomalous spring temperature is not necessarily linked to the presence of fault convection. Local permeability anisotropy due to aquifers folding or facies changes are features sufficient for the rising of hot fluids. Shentsis, I., 1990. Mathematical models for long-term prediction of mountainous river runoff: methods, information and results, Hydrological Sciences Journal, 35:5, 487-500 Magri, F., Möller, S., Inbar, N., Möller, P., Raggad, M., R

  12. Water-quality data for the Flaming Gorge Reservoir area, Utah and Wyoming, 1969-72

    Science.gov (United States)

    Bolke, E.L.; Waddell, K.M.

    1972-01-01

    This report presents the basic data that were collected by the U.S. Geological Survey during a study of the chemical quality of water in Flaming Gorge Reservoir. An interpretive report will follow. The basic data were collected from the reservoir during six sampling runs between October 1970 and September 1972. The reservoir was sampled for chemical analyses at 17 sites. Chemical and physical data were measured in situ at 34 sites. The sites are shown in figure 1 and the data are listed in tables 1 and 3-6.

  13. Power-law statistics of a landslide inventory of Wanzhou District, Three-Gorges Reservoir, China.

    Science.gov (United States)

    Gui, Lei; Yin, Kunlong; Glade, Thomas

    2013-04-01

    Landslides with high frequency and large property loss are one of the most well-known nature hazards in the world. The area of the Three Gorges Reservoir in China has a lot of landslide distributions due to geological factors and human activities. Analysis of frequency-size distribution of landslides has been frequently applied by numerous researchers. Hereby, Power-law statistics is a widely used method to determine the frequency-area (and -volume) distribution of landslides. In this study, we perform statistical analysis for a landslide inventory of the Wanzhou District in the Three-Gorges reservoir area of China. The goal is to prove that power-law statistics method for the frequency-size distribution of landslides is also applicable in Chinese environments. As the landslide investigation data is always incomplete, we proposed a way of dealing with incomplete data in this study in order to predict the total number of landslides in the study area. This study is carried out in Wanzhou District, the Three-Gorges Reservoir, China, where landslides occurred in high frequency. The landslide data has been received from the Three Gorges Geohazard Control Headquarters, which are based on a detailed field landslide investigation in 2010. The field observations have been carried out by the staff of the local environmental monitoring station and the local geologic prospecting agency. In this study, the power-law statistics has been focused on and the frequency-size and frequency-volume distribution of landslides have been analyzed. The data set contains 711 landslides. As it is an incomplete data, at the first the power-law relationship between the frequency and the area of landslides need to be analyzed, then the total number of landslides based on the ideal equation proved by other researchers has been predicted, and the real parameters within the equation used in the last step for this study area have been calculated. Finally the results have been compared with previous

  14. The Project for Developing Countermeasures against Landslides in the Abay River Gorge, Ethiopia

    Science.gov (United States)

    Guta, H. E.

    2016-12-01

    The Blue Nile Gorge of Ethiopia is characterized by high relief landscape. The stretch of major arterial road that connects Ethiopia to Sudan passes through the Gorge. The Gorge is plagued by swarms of landslides which makes it a tremendous obstacle for travel and communication. Therefore, landside study was carried out from 2010 to 2012 by JICA and Geological survey of Ethiopia to figure out the mechanisms that trigger the swarms of landslides that occur in the area and identify appropriate countermeasures that would be best implemented. The study included geomorphologic and geologic survey, drilling survey, displacement monitoring, ground water and precipitation monitoring, geophysical exploration, and stability analysis. About 42 landslide monitoring instruments namely extensometers (both surface and borehole), inclinometers and ground water level meters were installed in four highly landslide prone areas to detect slip surface, and determine amount and direction of movement. The amount of landslide movement at the four zones is 42.4, 57.6, 294.9 and 136mm during rainy season. Ground water level rising, nature of material and intense rainfall are found to be among the major triggering factors. Stability analysis using Simple Jambu and modified Fellenus methods was conducted resulting in safety factor Fs less than one and reasonably 0.98 by adopting shear parameters of soils by back analysis. By assuming cohesion (c') to be very close to 0 due to landslide blocks active movement when ground water rises during rainy season, Shear resistance angle, ɸ, was obtained to be 10.80, 26.30, 10.20 and 16.30 in the four areas using Modified Fellenius method and 10.70, 26.60, 10.00 and 16.10 using Simple Janbu method. Effect of countermeasures was checked by trial calculation. Accordingly the factory of safety increased from 0.98 to 1.2 when ɸ=60, ground water is lowered by 6m, and steel pipe pile of ɸ500mm x t40mm at an interval of 1.9m are implemented. consequently

  15. Do we need construct more dams?

    Science.gov (United States)

    Chen, J.; Shi, H.

    2013-12-01

    This paper reviews global dam development in association with the growths of global population, economy, and energy consumption in the past several decades, and also evaluates contributions of dam development to future world sustainable development. Eventually, this paper answers whether we need more dams in the future or not. The world population has rapidly increased from 1.6 billion in 1900, 2.5 billion in 1950, 6.1 billion in 2000, to 7.0 billion in 2011, and is projected to reach 9.5 billion in 2050; similarly, the world economy has dramatically expanded. To maintain socioeconomic development, the consumption of water, food and energy has increased rapidly as well. However, the total volume of available water resource over the world is limited, the food production largely depends on water supply, and the main energy sources are still oil, coal and gas at present, which are regarded as non-renewable resources. Accordingly, it is expected that we will face serious problems to deal with the challenges of water crisis, food security and energy shortage in the near future. In order to enhance the capability of regulating water resource, a great number of global dams (and related reservoirs) have been constructed in the last one hundred years; currently, almost all large rivers over the world have been regulated by dams. The reservoirs can supply sufficient water for irrigated land to ensure food production, and the associated hydropower stations can generate electricity. This article collects the dam data from the ICOLD (International Commission on Large Dams) and GRanD (Global Reservoir and Dam) databases, and some socioeconomic data, including population, economy, and consumptions of water, food and energy over the world. Analysis of these data reveals that global dam development has a great impact on the world sustainable development. Further, it is concluded that we need further dam development to maintain our future development.

  16. Variability of Ecosystem State in Rivers Containing Natural Dams: A Chemical Analysis

    Science.gov (United States)

    Reynolds, Z. A.

    2015-12-01

    Flooding, and the resulting economic damage to roads and property, is associated with natural dams such as beaver dams or log jams. For this reason, humans often remove natural dams; however, river reaches with natural dams provide very different ecosystem services in comparison with free-flowing river reaches. Therefore, the goal of this project is to assess the differences in ecosystem state between these different river reach types in the northeastern United States. We focused on differences in basic chemistry (e.g., dissolved oxygen, pH, temperature, and organic carbon) to assess the impact of natural dams on river ecosystem state. Study sites include rivers in the White Mountains and southeastern New Hampshire at locations with beaver dams, beaver ponds, beaver meadows, log jams, and free-flowing reaches. Dissolved oxygen, ORP, pH, temperature, and conductivity were measured in the field with a YSI Professional Plus meter. Water samples were collected for subsequent laboratory analysis of total organic carbon with a Shimadzu TOC-L. Preliminary results show that the chemistry of river water varies with feature type. Most significantly, dissolved oxygen concentrations are highest in free-flowing reaches and lowest in beaver ponds. Although beaver ponds are often associated with lower pH, due the increased concentration of organic acids, some beaver ponds can increase pH when compared to free-flowing reaches on the same river. Early results also show that water chemistry returns quickly to the chemistry typical of the free-flowing river reaches after being altered by a natural dam. Overall, natural dams create a river system that has more heterogeneity, and therefore has opportunities to provide more ecosystem functions, than a purely free-flowing river; this can increase the number of supported instream and riparian species. By increasing the understanding of how natural dams affect the chemistry of river water, river engineers can improve their decisions on how

  17. Hydraulic fracturing of rock-fill dam

    Directory of Open Access Journals (Sweden)

    Jun-Jie WANG

    2016-02-01

    Full Text Available The condition in which hydraulic fracturing in core of earth-rock fill dam maybe induced, the mechanism by which the reason of hydraulic fracturing canbe explained, and the failure criterion by which the occurrence of hydraulicfracturing can be determined, were investigated. The condition dependson material properties such as, cracks in the core and low permeability ofcore soil, and “water wedging” action in cracks. An unsaturated core soiland fast impounding are the prerequisites for the formation of “waterwedging” action. The mechanism of hydraulic fracturing can be explainedby fracture mechanics. The crack propagation induced by water pressuremay follow any of mode I, mode II and mixed mode I-II. Based on testingresults of a core soil, a new criterion for hydraulic fracturing was suggested,from which mechanisms of hydraulic fracturing in the core of rock-fill damwere discussed. The results indicated that factors such as angle betweencrack surface and direction of principal stress, local stress state at thecrack, and fracture toughness KIC of core soil may largely affect theinduction of hydraulic fracturing and the mode of the propagation of thecrack.The condition in which hydraulic fracturing in core of earth-rock fill dam maybe induced, the mechanism by which the reason of hydraulic fracturing canbe explained, and the failure criterion by which the occurrence of hydraulicfracturing can be determined, were investigated. The condition dependson material properties such as, cracks in the core and low permeability ofcore soil, and “water wedging” action in cracks. An unsaturated core soiland fast impounding are the prerequisites for the formation of “waterwedging” action. The mechanism of hydraulic fracturing can be explainedby fracture mechanics. The crack propagation induced by water pressuremay follow any of mode I, mode II and mixed mode I-II. Based on testingresults of a core soil, a new criterion for hydraulic fracturing

  18. The role of dams in development

    International Nuclear Information System (INIS)

    Cakmak, C.

    2001-01-01

    Although the amounts of water resources are enough for the entire world, the distribution of them in time and space shows uneven pattern. The water need is increasing with heavy industrial and agricultural requirements, while available water in the world remains as a fixed source. Economic growth, socio-cultural, and environmental developments are being realized following these changes. In order to achieve sustainable management of water resources, these changes have to be taken into consideration in water-related development projects. Demand for water is steadily increasing through out the world, even though the fresh water resources are limited and unevenly distributed, during the past three centuries, the amount of water withdrawn from fresh water resources has increased by a factor of 35, whereas world population by a factor 8. The engineering of dams, which provides regular water from reservoirs of dams to be used in case of demand pattern, is a vital part of the civilization. Dams have played a key rote in the development since the third millennium B C when the first great civilizations evolved on major rivers, such as Tigris-Euphrates, the Nile and the Indus. From these early times dams were built for flood control, water supply, irrigation and navigation. Dams also had been built to produce motive power and electricity since the industrial revolution. Development priorities changed, experience accumulated with the construction and operation of dams. Although the importance of water is well known in the human life and civilization around the world, still various groups argue that expected economic benefits are not being produced and that major environmental, economic and social costs are not being taken into account. By the end of 20th century, there were 45000 large dams in over 150 countries. According to the same classification there are 625 large dams in Turkey. All over the world, 50 % of the large dams were built mainly for irrigation. It is estimated

  19. Deformation Monitoring and Bathymetry Analyses in Rock-Fill Dams, a Case Study at Ataturk Dam

    Science.gov (United States)

    Kalkan, Y.; Bilgi, S.

    2014-12-01

    Turkey has 595 dams constructed between 1936 and 2013 for the purposes of irrigation, flood control, hydroelectric energy and drinking water. A major portion of the dam basins in Turkey are deprived of vegetation and have slope topography on near surrounding area. However, landscaping covered with forest around the dam basin is desirable for erosion control. In fact; the dams, have basins deprived of vegetation, fill up quickly due to sediment transport. Erosion control and forestation are important factors, reducing the sediment, to protect the water basins of the dams and increase the functioning life of the dams. The functioning life of dams is as important as the investment and construction. Nevertheless, in order to provide safety of human life living around, well planned monitoring is essential for dams. Dams are very large and critical structures and they demand the use or application of precise measuring systems. Some basic physical data are very important for assessing the safety and performance of dams. These are movement, water pressure, seepage, reservoir and tail-water elevations, local seismic activities, total pressure, stress and strain, internal concrete temperature, ambient temperature and precipitation. Monitoring is an essential component of the dam after construction and during operation and must en­able the timely detection of any behavior that could deteriorate the dam, potentially result in its shutdown or failure. Considering the time and labor consumed by long-term measurements, processing and analysis of measured data, importance of the small structural motions at regular intervals could be comprehended. This study provides some information, safety and the techniques about the deformation monitoring of the dams, dam safety and related analysis. The case study is the deformation measurements of Atatürk Dam in Turkey which is the 6th largest dam of world considering the filling volume of embankment. Brief information is given about the

  20. Hydropower, social priorities and the rural–urban development divide: The case of large dams in Cambodia

    International Nuclear Information System (INIS)

    Siciliano, Giuseppina; Urban, Frauke; Kim, Sour; Dara Lonn, Pich

    2015-01-01

    Hydropower investment is a priority in many developing countries, as a means to increase electrification rates and promote national development. However, neglect of dam-affected people's needs, can make them vulnerable to the multifaceted impacts of such projects. Using the case of Cambodia's first large dam, the Kamchay dam, this paper reveals social priorities of affected communities and institutional actors linked to environmental and social implications of large hydropower projects using a preference ranking method. Qualitative research revealed concerns among dam-affected communities which included energy access, livelihood changes, environmental impacts, access to natural resources and compensation. Results also reveal divergence between national and local priorities, which in turn brings about an unequal distribution of costs and benefits of the Kamchay Dam between urban and rural areas. The paper provides recommendations to policy-makers, NGOs and international organizations regarding governance issues, consultation processes and mitigation measures. - Highlights: • We assess social priorities linked to the impacts of a large dam in Cambodia. • We examine differences between local actors in the prioritization of the impacts. • Findings show divergences between national and local priorities of dam construction. • Distribution of cost and benefit is spatially unequal between rural and urban areas.

  1. The Manantali dam. Synthesis report

    International Nuclear Information System (INIS)

    Dickmann, M.; Sieburger, Dr; Ficatier, M.; Naudet, M.; Schmidt, M.; Seve, M.

    2009-01-01

    This report proposes an ex-post assessment of the Manantali dam on the Senegal river and of the related investments in Senegal, in Mauritania and in Mali. After a presentation of the methodology adopted for this assessment study performed by several organisms, the report describes the context and the concerned sectors: project costs and funding, framework for irrigated agriculture, and framework for energy. It discusses the relevance of the project with respect to irrigated agriculture and to energy. It assesses the project performance in terms of efficiency and of viability, and with respect to environmental aspects. It presents an overview of the different direct and indirect sector-based partners which are involved in energy or rural development. The next part proposes an assessment of the global impact of the project on development as far as irrigated agriculture, the energy sector, and regional cooperation and integration are concerned. A set of lessons learned and recommendations are then formulated

  2. Dam construction in salt rock

    International Nuclear Information System (INIS)

    Stockmann, N.; Beinlich, A.; Flach, D.; Jockwer, N.; Klarr, K.; Krogmann, P.; Miehe, R.; Schmidt, M.W.; Schwaegermann, H.F.; Walter, F.; Yaramanci, U.

    1991-11-01

    Barriers are a major component of the satefy concept for the Gorleben repository. The construction and performance of dams are currently tested within the framework of a project carried out in the Asse salt mine. A measuring programme has been established to give evidence of the sealing capacities of a barrier consisting of an abatement, long-term sealing material, and a hydraulic sealing system. Tests are to be made to verify the barrier's performance for shorter of long time periods (up to about 500 years). The tests are assisted by computed models established for the project. The long-term safety aspects to be studied include such conditions as permeability changes due to mechanical impacts, circulation conditions at the roadside, and the serviceable life and efficiency of the sealing components. (DG) [de

  3. Developing Digital Image Techniques with Low-Cost Unmanned Mobile to Monitor the Safety of Dam and Affiliated Structure

    Science.gov (United States)

    Sung, Wen-Pei; Shih, Ming-Hsiang

    2016-04-01

    Global warming phenomena are increasingly serious, the El Niño and La Niña continue to occur repeatedly, causing the irregular drought and flood problem repeatedly. Mountain form of Taiwan is steep and storage ability of rainwater is insufficient to supply the livelihood of people and usage of industry which need to rely on rainwater reservoir. Thus, to ensure the water supply and self-reliance energy supply, one of ways to keep water resource is to build reservoir. Nevertheless, Taiwan is located on Pacific seismic belt; additionally, geological conditions are not fine, over-developed in the hills lead to more natural disasters in the future. Thus, strong shakes and typhoons which caused a degree of severe landslides around dam lead to reduce catchment of dam to result in affecting the safety of dam. Otherwise, the cracks and rusts in dam, induced by the defects of material, bad construction and seismic excitation respectively, thus, the mechanics phenomena of dam and its affiliated structures with crack are probing into the cause of stress concentration, induced high crack increase rate, affect the safety and usage of dam. This research is aimed at the safety evaluation technique of dam and its affiliated structures to develop three dimensional digital image correlation techniques for monitoring the safety of dam and its affiliated structures. Namely, developing the unmanned mobile on two axis of digital image correlation method is to detect the digital images from geometric scanning techniques for dam structure. This developed technique combined with Unmanned Aerial Vehicle (UAV) to develop the near filed scanning and monitoring techniques for local deformation and cracks on dam and its affiliated structures.

  4. Stratigraphy, sedimentology, and volume of sediments behind a dam relic on the Muskegon River, Big Rapids, Michigan

    Science.gov (United States)

    Westjohn, David B.

    1997-01-01

    The proposed removal of the remnants of a hydroelectric dam in the Muskegon River at Big Rapids, Michigan, will potentially affect flow of the river at the city's water intake system. Fifteen boreholes were augered in bottom sediments in the river just upstream from the dam relic, and streambottom profiles were made using ground-penetrating radar. Data from boreholes show that sediments captured by the dam foundation were deposited in two distinctly different sedimentary environments. Sediments that overlie the pre-dam channel surface consist of lacustrine clay, wood chips, silt, and sand. These lacustrine sediments are interbedded in a cyclical fashion, and they were deposited under low flow to stagnant water conditions during 1916-66, when a 17-foot-tall hydroelectric dam was in place. Demolition of the upper 13 feet of this dam in 1966 resulted in erosion of most of the lacustrine sediments, and subsequent deposition of coarser alluvium in the impoundment behind the remaining dam foundation. Lacustrine sediments are present in the active part of the stream channel and extend from the dam foundation to about 1,300 feet upstream. The composite thickness of lacustrine sediments and overlying coarser alluvium was determined from sediment cores collected from the boreholes. The volume of these sediments is estimated to be about 19,000 cubic yards.

  5. Philosopher’s Concrete: Dam Construction, Farmland Values, and Agricultural Production in the Western US, 1890–1920

    Directory of Open Access Journals (Sweden)

    Soudeh Mirghasemi

    2017-09-01

    Full Text Available Did construction of the Bureau of Reclamation dams in the early 20th century raise farm values and increase agricultural output? I construct a new county-level panel dataset from 1890 to 1920 with information on geography, climate, politics, agriculture, and major dams, and then evaluate the effect of the Bureau of Reclamation dams on the value of farms and on crop productivity. Using fixed effect panel estimation, I find that new federal dam construction increased the average value of farmland by approximately 6.4 percent. When I apply an instrument to control for potential endogeneity, the effect of Bureau dams on farmland value increases in size, although the estimate also becomes noisier and is no longer statistically significant. My results indicate that Bureau dams constructed in prior decades and the new dams constructed by other agencies did not have a statistically significant effect on the value of farms. In terms of crop output, the only crop affected by the dams was alfalfa.

  6. Environmental impact assessments of the Three Gorges Project in China: Issues and interventions

    Science.gov (United States)

    Xu, Xibao; Tan, Yan; Yang, Guishan

    2013-09-01

    The paper takes China's authoritative Environmental Impact Statement for the Yangzi (Yangtze) Three Gorges Project (TGP) in 1992 as a benchmark against which to evaluate emerging major environmental outcomes since the initial impoundment of the Three Gorges reservoir in 2003. The paper particularly examines five crucial environmental aspects and associated causal factors. The five domains include human resettlement and the carrying capacity of local environments (especially land), water quality, reservoir sedimentation and downstream riverbed erosion, soil erosion, and seismic activity and geological hazards. Lessons from the environmental impact assessments of the TGP are: (1) hydro project planning needs to take place at a broader scale, and a strategic environmental assessment at a broader scale is necessary in advance of individual environmental impact assessments; (2) national policy and planning adjustments need to react quickly to the impact changes of large projects; (3) long-term environmental monitoring systems and joint operations with other large projects in the upstream areas of a river basin should be established, and the cross-impacts of climate change on projects and possible impacts of projects on regional or local climate considered.

  7. The dynamic capacity calculation method and the flood control ability of the Three Gorges Reservoir

    Science.gov (United States)

    Zhang, Shanghong; Jing, Zhu; Yi, Yujun; Wu, Yu; Zhao, Yong

    2017-12-01

    To evaluate the flood control ability of a river-type reservoir, an accurate simulation method for the flood storage, discharge process, and dynamic capacity of the reservoir is important. As the world's largest reservoir, the storage capacity and flood control capacity of the Three Gorges Reservoir (TGR) has attracted widespread interest and academic debate for nearly 20 years. In this study, a model for calculating the dynamic capacity of a river-type reservoir is established based on data from 394 river cross sections and 2.5-m resolution digital elevation model (DEM) data of the TGR area. The storage capacity and flood control capacity of the TGR were analysed based on the scheduling procedures of a normal impoundment period. The results show that the static capacity of the TGR is 43.43 billion m3, the dynamic flood control capacity is 22.45 billion m3, and the maximum floodwater flow regulated by the dynamic capacity at Zhicheng is no more than 67,700 m3/s. This study supply new simulation method and up-to-date high-precision data to discuss the 20 years debate, and the results reveal the TGR design is conservative for flood control according to the Preliminary Design Report of the Three Gorges Project. The dynamic capacity calculation method used here can provide a reference for flood regulation of large river-type reservoirs.

  8. A Homo habilis maxilla and other newly-discovered hominid fossils from Olduvai Gorge, Tanzania.

    Science.gov (United States)

    Clarke, R J

    2012-08-01

    In 1995, a 1.8 million year old hominid maxilla with complete dentition (OH 65) was excavated from Bed I in the western part of Olduvai Gorge. The molar crowns are small relative to the long flaring roots, and the root of the canine is very long and straight. The broad maxilla with wide U-shaped palate and the form of the tooth roots closely match those of KNM-ER 1470 which, in its parietal size and morphology, matches the type specimen of Homo habilis, OH 7. Thus, OH 65 and KNM-ER 1470 group with OH 7 as representatives of H. habilis while some other Olduvai specimens, such as OH 13 and OH 24, have more in common in terms of morphology and brain size with Australopithecus africanus. Between 1995 and 2007, the OLAPP team has recovered teeth of eight other hominid individuals from various parts of Olduvai Gorge. These have been identified as belonging to H. habilis, Paranthropus boisei, and Australopithecus cf. africanus. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Preliminary small mammal taphonomy of FLK NW level 20 (Olduvai Gorge, Tanzania)

    Science.gov (United States)

    Arcos, Saleta; Sevilla, Paloma; Fernández-Jalvo, Yolanda

    2010-11-01

    The Bed-I series of Olduvai Gorge (Tanzania) is a reference site in human evolution, having yielded the holotypes of Paranthropus boisei and Homo habilis, together with manufactured artefacts and abundant large and micro-fauna. Excavations in Olduvai Gorge have been recently resumed, with new aims and new results. This paper presents the results of the taphonomic analysis carried out on a fossil small-mammal assemblage recovered from FLK NW level 20, a layer overlying Tuff C, dated from 1.84 Ma. The analysis provides good evidence of a category 1 predator, most likely a barn owl, as the predator of the bone assemblage. Trampling and sediment compression might influence postdepositional breakage of the bones. This study is especially relevant since previous taphonomic analyses carried out at levels above and below this sample led to inconclusive results due to a low number of fossils ( Fernández-Jalvo et al., 1998). The new sample provides new information to reconstruct the paleoenvironmental context in which early hominins inhabited.

  10. Vegetation Activity Trend and Its Relationship with Climate Change in the Three Gorges Area, China

    Directory of Open Access Journals (Sweden)

    Guifeng Han

    2013-01-01

    Full Text Available Based on SPOT/VGT NDVI time series images from 1999 to 2009 in the Three Gorges Area (TGA, we detected vegetation activity and trends using two methods, the Mann-Kendall and Slope tests. The relationships between vegetation activity trends and annual average temperature and annual total precipitation were analyzed using observational data in seven typical meteorological stations. Vegetation activity presents a distinctive uptrend during the study period, especially in Fengjie, Yunyang, Wushan, Wuxi, and Badong counties located in the midstream of the Three Gorges Reservoir. However, in the Chongqing major area (CMA and its surrounding areas and Fuling, Yichang, and part of Wanzhou, vegetation activity shows a decreasing trend as a result of urban expansion. The NDVI has two fluctuation troughs in 2004 and 2006. The annual mean temperature presents a slight overall upward trend, but the annual total precipitation does not present a significant trend. And they almost have no significant correlations with the NDVI. Therefore, temperature and precipitation are not major influences on vegetation activity change. Instead, increasing vegetation cover benefits from a number of environment protection policies and management, and ecological construction is a major factor resulting in the upward trend. In addition, resettlement schemes mitigate the impact of human activity on vegetation activity.

  11. The effect of rubber dam usage on the survival rate of teeth receiving initial root canal treatment: a nationwide population-based study.

    Science.gov (United States)

    Lin, Po-Yen; Huang, Shih-Hao; Chang, Hong-Ji; Chi, Lin-Yang

    2014-11-01

    It is well-known that the usage of rubber dams during root canal treatment (RCT) improves infection control and treatment efficacy and protects patients. However, the effect of rubber dam usage on endodontic outcomes remain uncertain. The aim of the present study was to investigate whether rubber dam usage affects the survival rate of initial RCT using a nationwide population-based database. A total of 517,234 teeth that received initial RCT between 2005 and 2011 met the inclusion criteria and were followed until the end of 2011. Univariate and multivariate Cox proportional hazards models were used to estimate the effects of rubber dam usage on the risk of tooth extraction after initial RCT. Of the 517,234 teeth, 29,219 were extracted, yielding a survival rate of 94.4%. The survival probability of initial RCT using rubber dams after 3.43 years (the mean observed time) was 90.3%, which was significantly greater than the 88.8% observed without the use of rubber dams (P dams was significantly lower than that observed for RCT without rubber dams (hazard ratio = 0.81; 95% confidence interval, 0.79-0.84). The use of a rubber dam during RCT could provide a significantly higher survival rate after initial RCT. This result supports that rubber dam usage improves the outcomes of endodontic treatments. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Dams and Displacement: Raising the Standards and Broadening the Research Agenda

    Directory of Open Access Journals (Sweden)

    Brooke McDonald-Wilmsen

    2010-06-01

    Full Text Available The World Commission on Dams provided an analytical overview of the cumulative effects of years of dam development. A lack of commitment or capacity to cope with displacement or to consider the civil rights of, or risks to, displaced people led to the impoverishment and suffering of tens of millions and growing opposition to dams by affected communities worldwide. However, after the WCD, little has changed for the better in terms of resettlement policies. In fact, the standards of key agencies, like the Asian Development Bank, have been lowered and diluted compared to prior policies. Dam-induced development and displacement are stifled by a 'managerialist' approach to planning, in which solutions are sought internally and subordinated to the economics that underpins the existence of the project. The aim of successful resettlement is to prevent impoverishment and to enable displaced people to share in the project’s benefits. Within the field of dam-induced resettlement, this is a lofty goal rarely achieved. However, in other fields of resettlement, such as refugee studies and adaptation to environmental change, such a goal is regarded as a minimum standard. In this paper we seek to broaden the research agenda on dam-induced resettlement and to raise the standards of development projects that entail resettlement. We do this by importing some of the considerations and concerns from practice and research from the fields of refugee studies and adaptation to environmental change.

  13. Investigation of quality of storage dam in Ilam, identifying of pollutant resources and pollutants attitude

    Directory of Open Access Journals (Sweden)

    Moayed Avazpour

    2013-12-01

    Full Text Available Water quality of dam storage is highly affected by upstream environment and basin. Regarding other conducted studies, there exist various reasons such as some studies and general monitoring of dams which cause some main problems including salinity, chemical and microbial pollution eutrophication, and sedimentation. Chame-Gerdalan storage dam in Ilam Province is one of the storages which have many environmental issues because of discharge upstream rural wastewaters, animal excreta, agricultural drainage, and leachate. The aim of this study is to signify the quality of Ilam’s storage dam and also to recognize the pollutant resources and to analyze the pollutants’ behavior at different times and sites in order to determine dam properties for agricultural and domestic usages. Regarding the importance of the topic, the present study (in the year 2012 is based on the collected information of water quality of the basin, recognition of pollutant resources and measurement of qualitative parameters such as temperature, TDS, EC, BOD5, COD, nitrogen, phosphor, and pH in seven periods of time (from May to November. The results show that the total increase in the concentration of all variables along the basin are over double, in particular, Nitrat, Sulfat, BOD, and COD. After analyzing data with some water quality indexes, we analyzed water quality of the storage and some strategies were applied in order to control the effect decrease in the dam storage which, a management program was presented to improve water quality.

  14. Intergarted geophysical investigations by GPR and ERT on the largest rock fill dam in Europe: Monte Cotugno dam (Southern Italy)

    Science.gov (United States)

    Loperte, A.; Bavusi, M.; Cerverizzo, G.; Lapenna, V.; Soldovieri, F.

    2012-04-01

    dam and then monitor these areas of infiltration. For such a task, the use of conventional geotechnical investigation methods was discarded since these techniques often requires invasive actions in the inner of the structure to be investigated (destructiveness) and only provide punctual information for small volumes. On the contrary, in this case, it was decided to use non-invasive sensing techniques, which make it possible to investigate and gain "global" information about all the structure without affecting its operability. In particular, Ground Penetrating Radar and Electrical Resistivity Tomography techniques have been exploited so to have possibility of quickly investigating large portions of dam with different spatial and resolution scales and without the need of destructive actions. The results of this survey well agree with direct surveys and the details of the survey and of the diagnostic results will be shown at the conference.

  15. Developing an integrated dam safety program

    International Nuclear Information System (INIS)

    Nielsen, N. M.; Lampa, J.

    1996-01-01

    An effort has been made to demonstrate that dam safety is an integral part of asset management which, when properly done, ensures that all objectives relating to safety and compliance, profitability, stakeholders' expectations and customer satisfaction, are achieved. The means to achieving this integration of the dam safety program and the level of effort required for each core function have been identified using the risk management approach to pinpoint vulnerabilities, and subsequently to focus priorities. The process is considered appropriate for any combination of numbers, sizes and uses of dams, and is designed to prevent exposure to unacceptable risks. 5 refs., 1 tab

  16. 3D hydrogeological model of the Lower Yarmouk Gorge, Jordan Rift Valley

    Science.gov (United States)

    Magri, Fabien; Inbar, Nimrod; Möller, Peter; Raggad, Marwan; Rödiger, Tino; Rosenthal, Eliahu; Shentsis, Izabela; Tzoufka, Kalliopi; Siebert, Christian

    2017-04-01

    The Lower Yarmouk Gorge (LYG) lies on the eastern margin of the lower Jordan Rift Valley (JRV), bounded to the south by the Ajlun and to the north by the Golan Heights. It allows the outflow of the Yarmouk drainage basin and flow into the Jordan River, a few kilometers south of Lake Tiberias. The main aquifer system of the LYG is built mostly of Cretaceous sandstones and carbonates confined by Maastrichtian aquiclude. Fissures allow hydraulic connections between the major water-bearing formations from Quaternary to Upper Cretaceous age. It is supposed that the gorge acts as the mixing zone of two crossing flow pathways: N-S from the Hermon Mountains and from the Ajlun Dome, and E-W from Jebel al Arab Mountain in Syria (also known as Huran Plateau or Yarmouk drainage basin). As a result, several springs can be found within the gorge. These are characterized by widespread temperatures (20 - 60 °C) which indicate that, beside the complex regional flow, also ascending thermal waters control the hydrologic behavior of the LYG. Previous simulations based on a conceptual simplified 3D model (Magri et al., 2016) showed that crossing flow paths result from the coexistence of convection, that can develop for example along NE-SW oriented faults within the gorge or in permeable aquifers below Maastrichtian aquiclude, and additional flow fields that are induced by the N-S topographic gradients. Here we present the first 3D hydrogeological model of the entire LYG that includes structural features based on actual logs and interpreted seismic lines from both Israeli and Jordanian territories. The model distinguishes seven units from upper Eocene to the Lower Triassic, accounting for major aquifers, aquicludes and deep-cutting faults. Recharges are implemented based on the numerical representation developed by Shentsis (1990) that considers relationships between mean annual rain and topographic elevation. The model reveals that topography-driven N-S and E-W flows strongly control

  17. The potential impact of new Andean dams on Amazon fluvial ecosystems

    Science.gov (United States)

    Melack, John M.; Dunne, Thomas; Barthem, Ronaldo B.; Goulding, Michael; Paiva, Rodrigo C. D.; Sorribas, Mino V.; Silva, Urbano L.; Weisser, Sabine

    2017-01-01

    Increased energy demand has led to plans for building many new dams in the western Amazon, mostly in the Andean region. Historical data and mechanistic scenarios are used to examine potential impacts above and below six of the largest dams planned for the region, including reductions in downstream sediment and nutrient supplies, changes in downstream flood pulse, changes in upstream and downstream fish yields, reservoir siltation, greenhouse gas emissions and mercury contamination. Together, these six dams are predicted to reduce the supply of sediments, phosphorus and nitrogen from the Andean region by 69, 67 and 57% and to the entire Amazon basin by 64, 51 and 23%, respectively. These large reductions in sediment and nutrient supplies will have major impacts on channel geomorphology, floodplain fertility and aquatic productivity. These effects will be greatest near the dams and extend to the lowland floodplains. Attenuation of the downstream flood pulse is expected to alter the survival, phenology and growth of floodplain vegetation and reduce fish yields below the dams. Reservoir filling times due to siltation are predicted to vary from 106–6240 years, affecting the storage performance of some dams. Total CO2 equivalent carbon emission from 4 Andean dams was expected to average 10 Tg y-1 during the first 30 years of operation, resulting in a MegaWatt weighted Carbon Emission Factor of 0.139 tons C MWhr-1. Mercury contamination in fish and local human populations is expected to increase both above and below the dams creating significant health risks. Reservoir fish yields will compensate some downstream losses, but increased mercury contamination could offset these benefits. PMID:28832638

  18. Impacts of beaver dams on hydrologic and temperature regimes in a mountain stream

    Science.gov (United States)

    Majerova, M.; Neilson, B. T.; Schmadel, N. M.; Wheaton, J. M.; Snow, C. J.

    2015-08-01

    Beaver dams affect hydrologic processes, channel complexity, and stream temperature in part by inundating riparian areas, influencing groundwater-surface water interactions, and changing fluvial processes within stream systems. We explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a 3-year period spanning pre- and post-beaver colonization. Using continuous stream discharge, stream temperature, synoptic tracer experiments, and groundwater elevation measurements, we documented pre-beaver conditions in the first year of the study. In the second year, we captured the initial effects of three beaver dams, while the third year included the effects of ten dams. After beaver colonization, reach-scale (~ 750 m in length) discharge observations showed a shift from slightly losing to gaining. However, at the smaller sub-reach scale (ranging from 56 to 185 m in length), the discharge gains and losses increased in variability due to more complex flow pathways with beaver dams forcing overland flow, increasing surface and subsurface storage, and increasing groundwater elevations. At the reach scale, temperatures were found to increase by 0.38 °C (3.8 %), which in part is explained by a 230 % increase in mean reach residence time. At the smallest, beaver dam scale (including upstream ponded area, beaver dam structure, and immediate downstream section), there were notable increases in the thermal heterogeneity where warmer and cooler niches were created. Through the quantification of hydrologic and thermal changes at different spatial and temporal scales, we document increased variability during post-beaver colonization and highlight the need to understand the impacts of beaver dams on stream ecosystems and their potential role in stream restoration.

  19. Biostable insect kinin analogs reduce blood meal and disrupt ecdysis in the blood-gorging Chagas’ disease vector, Rhodnius prolixus

    Science.gov (United States)

    Rhodnius prolixus is a blood-gorging hemipteran that takes blood meals that are approximately 10 times its body weight. This blood meal is crucial for growth and development and is needed to ensure a successful molt into the next instar. Kinins are a multifunctional family of neuropeptides which hav...

  20. Predictions of total deformations in Jebba main dam by finite ...

    African Journals Online (AJOL)

    This paper examined the deformations of the Jebba Main Dam, Jebba Nigeria using the finite element method. The study also evaluated the predicted deformations and compared them with the actual deformations in the dam to identify possible causes of the observed longitudinal crack at the dam crest. The Jebba dam is a ...

  1. The geomorphic legacy of small dams — An Austrian study

    NARCIS (Netherlands)

    Poeppl, R.E.; Keesstra, S.D.; Hein, T.

    2015-01-01

    Dams represent one of the most dominant forms of human impact upon fluvial systems during the Anthropocene, as they disrupt the downstream transfer of water and sediments. Removing dams restores river continuity and channel morphology. Both dam construction and dam removal induce geomorphic channel

  2. Evaluating safety of concrete gravity dam on weak rock: Scott Dam

    International Nuclear Information System (INIS)

    Goodman, R.E.; Ahlgren, C.S.

    2000-01-01

    Scott Dam is owned and operated by Pacific Gas and Electric Co. (PG and E) as part of the Potter Valley Project. Although it is an unimpressive concrete gravity dam [233 m (765 ft) long with maximum water surface 33.4 m (110 ft) above tail water], the dam has unusually complex and weak foundation rocks; thick condition caused design changes during construction, numerous subsequent special investigations, and several corrections and additions. A main stumbling block to clarification of the dam safety issue for Scott Dam has always been difficulty in characterizing the foundation material. This paper discusses an approach to this problem as well s how the safety of the dam was subsequently confirmed. Following a comprehensive program of research, investigations, and analysis from 1991 to 1997

  3. Flood Water Level Mapping and Prediction Due to Dam Failures

    Science.gov (United States)

    Musa, S.; Adnan, M. S.; Ahmad, N. A.; Ayob, S.

    2016-07-01

    Sembrong dam has undergone overflow failure. Flooding has been reported to hit the town, covering an area of up to Parit Raja, located in the district of Batu Pahat. This study aims to identify the areas that will be affected by flood in the event of a dam failure in Sembrong Dam, Kluang, Johor at a maximum level. To grasp the extent, the flood inundation maps have been generated by using the InfoWorks ICM and GIS software. By using these maps, information such as the depth and extent of floods can be identified the main ares flooded. The flood map was created starting with the collection of relevant data such as measuring the depth of the river and a maximum flow rate for Sembrong Dam. The data were obtained from the Drainage and Irrigation Department Malaysia and the Department of Survey and Mapping and HLA Associates Sdn. Bhd. Then, the data were analyzed according to the established Info Works ICM method. The results found that the flooded area were listed at Sri Lalang, Parit Sagil, Parit Sonto, Sri Paya, Parit Raja, Parit Sempadan, Talang Bunut, Asam Bubok, Tanjung Sembrong, Sungai Rambut and Parit Haji Talib. Flood depth obtained for the related area started from 0.5 m up to 1.2 m. As a conclusion, the flood emanating from this study include the area around the town of Ayer Hitam up to Parit Raja approximately of more than 20 km distance. This may give bad implication to residents around these areas. In future studies, other rivers such as Sungai Batu Pahat should be considered for this study to predict and reduce the yearly flood victims for this area.

  4. Establishment and implementation of a dam safety program

    International Nuclear Information System (INIS)

    Rogers, R.

    1993-01-01

    The reasons for implementing dam safety programs are discussed, and a model for a dam safety program is outlined. A dam safety program should consist of regular inspections, reservoir monitoring, an emergency action plan, remedial work, registration permit reports, routine maintenance, and careful water supply management. Recommendations on initiating and implementing a dam safety program include: communication with the appropriate regulatory authority; communication with maintenance crews; communication with management; a well-rounded dam inspection team; the inclusion of maintenance items in dam modification projects; visual inspection of the dam; monitoring key indicators such as monuments and piezometer readings; and keeping current with the literature. 4 refs

  5. Sediment impact assessment of check-dam removal strategies on a mountain river in Taiwan

    Science.gov (United States)

    Kuo, W.; Wang, H.; Stark, C. P.

    2011-12-01

    Dam removal is important for reconnecting river habitats and restoring the free flow of water and sediment, so managing accumulated sediments is crucial in dam removal planning as the cost and potential impacts of dam removal can vary substantially depending on local conditions. A key uncertainty in dam removal is the fate of reservoir sediment stored upstream of the dam. Release of impounded sediment could raise downstream bed elevations leading to flooding, increase lateral channel mobility leading to bank erosion, and potentially bury downstream ecologically sensitive habitats if the sediment is fine. The ability to predict the sediment impacts of dam removal in highly sediment-filled systems is thus increasingly important as the number of such dam-removal cases is growing. Due to the safety concerns and the need for habitat restoration for the Formosan landlocked salmon, the Shei-Pa National Park in Taiwan removed the 15m high Chijiawan "No. 1 Check Dam" in late May 2011. During the planning process prior to removal, we conducted field surveys, numerical simulations, and flume experiments to determine sediment impacts and to suggest appropriate dam removal strategies. We collected river-bed topography and sediment bulk samples in 2010 to establish the channel geometry and grain-size distribution for modeling input. The scaled flume experiment was designed to provide insights on how and if the position of a notch location and size would affect the rate and amount of reservoir erosion under particular discharges. Observations indicated that choices of notch location can force the river to migrate differently. For long-term prediction, we used the quasi-two-dimensional numerical model NETSTARS (Network of Stream Tube model for Alluvial River Simulation) to simulate the channel responses. These simulations indicated that high suspended sediment concentrations would be the most likely major concern in the first year, while concerns for downstream sediment deposition

  6. Negligible contribution of reservoir dams to organic and inorganic transport in the lower Mimi River, Japan

    Science.gov (United States)

    Nukazawa, Kei; Kihara, Kousuke; Suzuki, Yoshihiro

    2017-12-01

    Rivers fulfill an essential ecological role by forming networks for material transport from upland forests to coastal areas. The way in which dams affect the organic and inorganic cycles in such systems is not well understood. Herein, we investigated the longitudinal profiles of the various components of the water chemistry across three cascade dams in Japan: the Yamasubaru Dam, Saigou Dam, and Ohuchibaru Dam, which are situated along the sediment-productive Mimi River in different flow conditions. We analyzed the following water quality components: suspended solids (SS), turbidity, total iron (TFe), dissolved iron (DFe), total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), humic substance (HS), and major ionic components (Na+, Mg2+, Ca2+, Cl-, NO3-, and SO42-) in the downstream channels of the three dams during the low-intermediate-flow and high-flow events from 2012 to 2014. We estimated hourly loads of each component using hourly turbidity data and discharge data (i.e., L-Q model) separately, and the results are integrated to estimate the annual fluxes. The annual fluxes between the methods were compared to verify predictability of the conventional L-Q models. Annual flux of TOC, TN, DFe, and HS estimated by the turbidity displayed similar values, whereas the flux of SS, TFe, and TP tended to increase downstream of the dams. Among the dams, estimated flux proportions for TP and TFe were higher during high-flow events (74%-94%). Considering geographic conditions (e.g., absence of major tributary between the dams), the result implies that accumulated TP and TFe in the reservoirs may be flushed and transported downstream with SS over the short height dams during flood events. Assuming this process, the reservoir dams probably make only a fractional contribution to the organic and inorganic transport in the catchment studied. The percent flux errors for SS, TFe, and TP fluxes ranged from -7.2% to -97% (except for the TP flux in 2013), which

  7. Mystery of Mosul Dam the Most Dangerous Dam in the World:Karstification and Sinkholes

    OpenAIRE

    Al-Ansari, Nadhir; Adamo, Nasrat; Issa, Issa; Sissakian, Varoujan; Knutsson, Sven

    2015-01-01

    The Fatha (ex-Lower Fars) Formation (Middle Miocene) is the predominant stratigraphic unit in the Mosul Dam area. It is about 250 meters thick near Mosul. Marls, chalky limestone, gypsum, anhydrite, and limestone form a layered sequence of rocks under the foundation of the dam. The foundation of the dam is mainly resting on the Fatha Formation (Middle Miocene) which is highly karstified. Karstic limestone and the development of solution cavities within the gypsum and anhydrite layers are the ...

  8. 76 FR 34799 - Permanent Dam Safety Modification at Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams, TN

    Science.gov (United States)

    2011-06-14

    ... TENNESSEE VALLEY AUTHORITY Permanent Dam Safety Modification at Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams, TN AGENCY: Tennessee Valley Authority. ACTION: Notice of intent. SUMMARY: This... existing dam facilities at Cherokee, Fort Loudoun, Tellico, and Watts Bar dams in Tennessee. The level of...

  9. 33 CFR 208.19 - Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex. 208.19 Section 208.19 Navigation and Navigable Waters... Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex. The Secretary of the...

  10. Industrial design of an earth overflow dam

    Energy Technology Data Exchange (ETDEWEB)

    Pravdivets, Yu.P.

    1988-06-01

    As a result of theoretical and experimental investigations of earth overflow dams of various types and purpose conducted by the author in the past ten years, methods of calculating the stability of protective structures of riprap, reinforcement meshes, gabions, and in situ and precast reinforced concrete were substantiated; the limits of economic applicability of various types of revetments and structures were determined; and new efficient designs of dams and revetments allowing the overflow of water with large discharge intensities were proposed. An earth overflow dam with the downstream slope protected by a precast reinforced-concrete revetment was determined to be the most effective design-technological solution. Both the entire dam or a part of it can be made overflow. The design has been realized on a number of experimental water-management objects which are reviewed.

  11. Dams life; La vie des barrages

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This paper summarizes the conclusions of the annual inspections of French dams in operation (fissures, water oozing, concrete swelling etc..). Only the observations which require a special attention are reported. (J.S.)

  12. Biological - Elwha River Dam Removal Study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study examines the ecosystem response of the Elwha River to the removal of the Elwha River dams. We will measure the following attributes of ecosystem response:...

  13. Physical - Elwha River Dam Removal Study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study examines the ecosystem response of the Elwha River to the removal of the Elwha River dams. We will measure the following attributes of ecosystem response:...

  14. Seismic risks at Elsie Lake Main Dam

    International Nuclear Information System (INIS)

    McCammon, N.R.; Momenzadeh, M.; Hawson, H.H.; Nielsen, N.M.

    1991-01-01

    The Elsie Lake dams are located on Vancouver Island in an area of high seismic risk. A safety review in 1986 indicated potential deficiencies in the earthfill main dam with respect to modern earthquake design standards. A detailed field investigation program comprising drilling and penetration tests was carried out and the results used in an assessment of seismic stability. A 0.8 m thick less dense layer in the granular shell of the dam, possibly caused by wet construction conditions, would likely liquefy in a major earthquake but sufficient residual strength would likely remain to prevent catastrophic failure. The dam shell might undergo some distortion, and an assessment was initiated to determine the requirements for reservoir drawdown following an extreme earthquake to ensure the timely lowering of the reservoir for inspection and repair. It was suggested that an adequate evacuation capability would be 25% and 50% drawdown in not more than 30 and 50 days, respectively. 9 refs., 11 figs., 1 tab

  15. Environmental-impact assessment of dams and reservoir projects (review and a case study)

    International Nuclear Information System (INIS)

    Shah, S.M.

    2009-01-01

    Dams and reservoirs are among one of the most sensitive of all development Project, in terms of pervasiveness of their influence in altering the environmental conditions and resources. In the present study, major dams and reservoir projects are reviewed, from the environmental point of view. Dams and Reservoir projects bring about major changes in the immediate environment, thus affecting public health, settlements, farmlands, roads and historical sites. Impacts on human population and wildlife may be profound. Tropical diseases, involving fresh-water hosts or vectors in their transmission, are often common around new reservoirs. Large lakes create limnological changes, excessive evaporation, seepage, disturbance in water-table and increased tendencies of landslides and earthquakes. Micro climatic changes are possible, such as fog formation, increased cloudiness and modified rainfall-patterns. Retention of sediment results in silting up of reservoirs. Water shortages on mountain rivers may leave unsightly dry river-beds below a dam. Sediment deposition and growth of vegetation in reservoir affects the water-extraction for navigation power-generation and fishing. Various dams and reservoir projects in the world are critically studied, in terms of creating environmental impacts. The Kala Bagh Dam project (Pakistan), which is ready for construction, has been analysed as a case study, by matrix method. Analyses show that adverse effects of this dam are less than the benefits. It is recommended that based on the experience, appropriate lines and strategies may be drawn up to evaluate the local projects. Multidisciplinary experts need to be involved, for assessing environmental impacts and suggesting mitigation measures, to combat the adverse effects. (author)

  16. Dam regulation and riverine food-web structure in a Mediterranean river.

    Science.gov (United States)

    Mor, Jordi-René; Ruhí, Albert; Tornés, Elisabet; Valcárcel, Héctor; Muñoz, Isabel; Sabater, Sergi

    2018-06-01

    Flow regimes are a major driver of community composition and structure in riverine ecosystems, and flow regulation by dams often induces artificially-stable flow regimes downstream. This represents a major source of hydrological alteration, particularly in regions where biota is adapted to strong seasonal and interannual flow variability. We hypothesized that dam-induced hydrological stability should increase the availability of autochthonous resources at the base of the food web. This, in turn, should favour herbivorous over detritivorous strategies, increasing the diversity of primary consumers, and the food-web width and length. We tested this hypothesis by studying the longitudinal variation in food-web structure in a highly-seasonal Mediterranean river affected by an irrigation dam. We compared an unregulated reach to several reaches downstream of the dam. Hydrological and sedimentological stability increased downstream of the dam, and altered the type and quantity of available resources downstream, prompting a change from a detritus-based to an algae-based food web. The fraction of links between top and intermediate species also increased, and the food web became longer and wider at the intermediate trophic levels. Food-web structure did not recover 14km downstream of the dam, despite a partial restitution of the flow regime. Our results advance the notion that hydrologic alteration affects riverine food webs via additions/deletions of taxa and variation in the strength and distribution of food-web interactions. Thus, flow regulation by dams may not only impact individual facets of biodiversity, but also food-web level properties across river networks. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  17. Hungry Horse Dam Fisheries Mitigation Implementation Plan, 1990-2003 Progress (Annual) Report.

    Energy Technology Data Exchange (ETDEWEB)

    Montana Department of Fish, Wildlife and Parks; Confederated Salish and Kootenai Tribes

    1993-03-10

    In this document the authors present mitigation implementation activities to protect and enhance resident fish and aquatic habitat affected by the construction and operation of Hungry Horse Dam. This plan only addresses non-operational actions (mitigation measures that do not affect dam operation) described in the 'Fisheries Mitigation Plan for Losses Attributable to the Construction and Operation of Hungry Horse Dam' (Mitigation Plan) submitted to the Northwest Power Planning Council (Council) in March 1991 and in accordance with subsequent Council action on that Mitigation Plan. Operational mitigation was deferred for consideration under the Columbia Basin System Operation Review (SOR) process. This document represents an implementation plan considered and conditionally approved by the Council in March of 1993.

  18. Expectations of immortality: dam safety management into the next millennium

    International Nuclear Information System (INIS)

    Palmer, M.D.

    1999-01-01

    Topics concerning the problems associated with older and aging dams are considered including: what can be done to extent the lifetime of an old dam, the decision to decommission a dam based on a value judgment that the risk of maintaining the dam is too great for society's acceptance, the possibility of change in the level of risk tolerance with time in a technological environment, traditional surveillance methods used by dam owners in the Y2K situation, and the unreality of dam immortality. Trends and means for preserving older dams for their owner's purposes are outlined, as well as their lifetime compared to that of the downstream systems they serve. Despite the fact that we live in a throwaway society, dam owners cannot just leave their dam asset when they are through with using it. Someone has to maintain the dam, or ensure that it is safely decommissioned when the owner is finished with it. On a worldwide scale the available pool of experienced dam engineers is shrinking. This problem needs to be addressed by a shift towards operating and dam safety management skills based on a firm awareness of dam design principles. A shift in society's expectations has occurred such that dam designers and owners must now recognize the impact a dam can have both on its natural and social environments. Because of the increasing emphasis on paying attention to the impacts of people's activities on the planet, engineers more than anyone else must have a significant influence in that direction. 9 refs

  19. Walter Bouldin Dam failure and reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-09-01

    Walter Bouldin is one of several hydroelectric developments of Alabama Power Company. On February 10, 1975, an earth embankment section of Walter Bouldin Dam was breached, causing total evacuation of the forebay reservoir and rendering the 225-MW power plant inoperable. The Federal Power Commission instituted an investigation of the dam failure, and a report on the investigation was published in February 1976. Subsequently, an evidentiary hearing was held before an administrative law judge who issued his initial decision on August 19, 1976. The Commission, on April 21, 1977, issued its Opinion No. 795 in which it adopted the initial decision with modifications and terminated the investigation of failure of Walter Bouldin Dam. Opinion No. 795 directs the staff of the Bureau of Power to prepare, for the future guidance of the Commission, a report on the deficiencies which were found in its investigation, together with advice as to how such deficiencies have been and should be remedied. Also, it directs the staff of the Bureau of Power to address certain general recommendations included in the initial decision. This report was prepared in response to that directive and summaries information on the dam failure and its investigation; the evidentiary hearing; the judge's recommendations, the reconstruction of the Bouldin Dam; and the evalution and status of the Federal Energy Regulatory Commission Dam safety program. (LCL)

  20. Design of anti-slide piles for slope stabilization in Wanzhou city, Three Gorges Area, China

    Science.gov (United States)

    Zhou, Chunmei; van Westen, Cees

    2013-04-01

    This study is related to the design of anti-slide piles for several landslides in Wanzhou city located in the Three Gorges area. Due to the construction of the Three Gorges Reservoir the hydro-geological conditions in this area have deteriorated significantly, leading to larger instability problems. China has invested a lot of money in slope stabilization measures for the treatment of landslides in the Three Gorges area. One of the methods for the stabilization of large landslides is the design of anti-sliding piles. This paper focuses on extensive slope stability analysis and modeling of the mechanical behavior of the landslide masses, and the parameters required for designing the number, size and dimensions of reinforced concrete stabilization piles. The study focuses on determining the rock parameters, anchor depth, and the pile and soil interaction coefficient. The study aims to provide guidelines for anti-slide pile stabilization works for landslides in the Wanzhou area. The research work contains a number of aspects. First a study is carried out on the distribution of pressures expected on the piles, using two different methods that take into account the expected pore water pressure and seismic acceleration. For the Ercengyan landslide , the Limit Equilibrium Method and Strength Reduction Method of FEM are compared through the results of the landslide pressure distributions on the piles and stress fields in the piles. The second component is the study of the required anchor depth of antislide piles, which is carried out using a statistical analysis with data from 20 landslides that have been controlled with anti-sliding piles. The rock characteristics of the anchor locations were obtained using laboratory tests, and a classification of rock mass quality is made for the anchors of antislide piles. The relationship between the critical anchor height and the angle of the landslide slip surface is determined. Two different methods are presented for the length

  1. Sediment and Cavitation Erosion Studies through Dam Tunnels

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2016-01-01

    Full Text Available This paper presents results of sediment and cavitation erosion through Tunnel 2 and Tunnel 3 of Tarbela Dam in Pakistan. Main bend and main branch of Tunnel 2 and outlet 1 and outlet 3 of Tunnel 3 are concluded to be critical for cavitation and sediment erosion. Studies are also performed for increased sediments flow rate, concluding 5 kg/sec as the critical value for sudden increase in erosion rate density. Erosion rate is concluded to be the function of sediment flow rate and head condition. Particulate mass presently observed is reasonably low, hence presently not affecting the velocity and the flow field.

  2. Massive accumulation of highly polluted sedimentary deposits by river damming

    Energy Technology Data Exchange (ETDEWEB)

    Palanques, Albert, E-mail: albertp@icm.csic.es [Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003 (Spain); Grimalt, Joan [Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona, 18, Barcelona 08034 (Spain); Belzunces, Marc; Estrada, Ferran; Puig, Pere; Guillén, Jorge [Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003 (Spain)

    2014-11-01

    Uncontrolled dumping of anthropogenic waste in rivers regulated by dams has created contaminated deposits in reservoirs that have remained unidentified for decades. The Flix Reservoir is located in the Ebro River, the second largest river flowing into the NW Mediterranean, has been affected by residue dumping from a chlor-alkali electrochemical plant for decades. High-resolution seismic profiles, bathymetric data, surficial sediment samples and sediment cores were obtained in the Flix Reservoir to study the characteristics of the deposit accumulated by this dumping. These data were used to reconstruct the waste deposit history. Since the construction of the Flix Dam in 1948, more than 3.6 × 10{sup 5} t of industrial waste has accumulated in the reservoir generating a delta-like deposit formed by three sediment lobes of fine-grained material highly contaminated by Hg, Cd, Zn and Cr (max: 640, 26, 420 and 750 mg kg{sup −1}, respectively). This contamination was associated with the Hg that was used for the cathode in the electrochemical plant from 1949 and with the production of phosphorite derivatives from 1973. After the construction of two large dams only a few kilometres upstream during the 1960s, the solids discharged from the industrial complex became the main sediment source to the Flix Reservoir. The deposit has remained in the reservoir forming a delta that obstructs about 50% of the river water section. Its stability only depended on the flow retention by the Flix Dam. At present, this contaminated waste deposit is being removed from the water reservoir as it is a cause of concern for the environment and for human health downriver. - Highlights: • A delta-like anthropogenic deposit prograded into the reservoir behind the Flix dam. • More than 3.6 × 10{sup 5} t of anthropogenic waste was accumulated in less than 4 decades. • A waste deposit with extreme levels of Hg and Cd was trapped in the Flix Reservoir. • The main pollution was related to

  3. Simulating dam - breach flood scenarios of the Tangjiashan landslide dam induced by the Wenchuan earthquake

    NARCIS (Netherlands)

    Fan, Xuanmei; Tang, C.; van Westen, C.J.; Alkema, D.

    2012-01-01

    Floods from failures of landslide dams can pose a hazard to people and property downstream, which have to be rapidly assessed and mitigated in order to reduce the potential risk. The Tangjiashan landslide dam induced by the Mw=7.9 2008 Wenchuan earthquake had impounded the largest lake in the

  4. the effect of age of dam on weaning mass for ftve dam breed types

    African Journals Online (AJOL)

    SUMMARY: The effect of age of dam on adjusted 210 day calf weaning mass was estimated by the Least Squares method for 5 dam types on 2 farms. ... the later maturing breeds would have a low level of productivity because these cows would be eliminated in their potentially prime .... time at 28 (2A) or 3l (28) months old.

  5. The remains of the dam: what have we learned from 15 years of US dam removals?

    Science.gov (United States)

    Gordon E. Grant; Sarah L. Lewis

    2015-01-01

    Important goals for studying dam removal are to learn how rivers respond to large and rapid introductions of sediment, and to develop predictive models to guide future dam removals. Achieving these goals requires organizing case histories systematically so that underlying physical mechanisms determining rates and styles of sediment erosion, transport, and deposition...

  6. The interplay of activists and dam developers : the case of Myanmar’s mega-dams

    NARCIS (Netherlands)

    Kirchherr, Julian; J. Charles, Katrina; Walton, Matthew J.

    2017-01-01

    Scholars investigating activism against large dam developments in Asia usually focus on those campaigning, but not on those the campaigns are aimed at–the dam developers. Yet the developers’ perspective is crucial to comprehensively understand the dynamics of social and environmental activism in

  7. Dam that social networking: connecting South Africa's major dams to social media

    CSIR Research Space (South Africa)

    Butgereit, L

    2011-10-01

    Full Text Available where four major South African dams are connected to Twitter and Facebook (and other social media such as MXit and Google Chat) in a mechanism which would be easy to replicate for additional dams or rivers. Data is supplied by the South African...

  8. Modeling the capacity of riverscapes to support beaver dams

    Science.gov (United States)

    Macfarlane, William W.; Wheaton, Joseph M.; Bouwes, Nicolaas; Jensen, Martha L.; Gilbert, Jordan T.; Hough-Snee, Nate; Shivik, John A.

    2017-01-01

    The construction of beaver dams facilitates a suite of hydrologic, hydraulic, geomorphic, and ecological feedbacks that increase stream complexity and channel-floodplain connectivity that benefit aquatic and terrestrial biota. Depending on where beaver build dams within a drainage network, they impact lateral and longitudinal connectivity by introducing roughness elements that fundamentally change the timing, delivery, and storage of water, sediment, nutrients, and organic matter. While the local effects of beaver dams on streams are well understood, broader coverage network models that predict where beaver dams can be built and highlight their impacts on connectivity across diverse drainage networks are lacking. Here we present a capacity model to assess the limits of riverscapes to support dam-building activities by beaver across physiographically diverse landscapes. We estimated dam capacity with freely and nationally-available inputs to evaluate seven lines of evidence: (1) reliable water source, (2) riparian vegetation conducive to foraging and dam building, (3) vegetation within 100 m of edge of stream to support expansion of dam complexes and maintain large colonies, (4) likelihood that channel-spanning dams could be built during low flows, (5) the likelihood that a beaver dam is likely to withstand typical floods, (6) a suitable stream gradient that is neither too low to limit dam density nor too high to preclude the building or persistence of dams, and (7) a suitable river that is not too large to restrict dam building or persistence. Fuzzy inference systems were used to combine these controlling factors in a framework that explicitly also accounts for model uncertainty. The model was run for 40,561 km of streams in Utah, USA, and portions of surrounding states, predicting an overall network capacity of 356,294 dams at an average capacity of 8.8 dams/km. We validated model performance using 2852 observed dams across 1947 km of streams. The model showed

  9. Macrofossil evidence for pre-settlement vegetation of Central Otago's basin floors and gorges

    International Nuclear Information System (INIS)

    Wood, J.R.; Walker, S.

    2008-01-01

    Composition of pre-settlement vegetation communities in the semi-arid Central Otago lowlands has been one of New Zealand's long-standing ecological puzzles. Uncertainty is due largely to a paucity of fossil data. Here, we provide new evidence for pre-settlement vegetation in the region based on analyses of plant macrofossils from 15 late Pleistocene and Holocene lowland sites. The assemblages represent two habitat types: wooded or partially wooded intermontane basin-floor wetlands, and low forest and/or shrubland habitats in the Kawarau and Clutha River gorges. In both habitat types, plant communities appear to have been predominantly woody, with significant components of herbaceous dicotyledons but few grasses. Both habitats seem to have undergone major post-settlement vegetation transformation. Several presently common taxa were rare or absent before human settlement, but others (including threatened spring annuals), now rare or extinct in the region, were formerly more common. (author). 57 refs., 5 figs., 3 tabs

  10. STUDIES ON LIGULARIA SIBIRICA (L. CASS. IN ITS SOUTHERN POINT IN ROMANIA, BRUSTURETULUI GORGES, ARGEŞ COUNTY

    Directory of Open Access Journals (Sweden)

    Andreea Natalia Matei

    2015-12-01

    Full Text Available The community importance species, Ligularia sibirica (L. Cass. it is located in its southern point in Romania, in Brusturetului Gorges in Arges County. In NATURA 2000 habitat, 3220 Alpine rivers and herbaceous vegetation along their banks, it is present the species of community importance Ligularia sibirica (L. Cass. in the plant association: Carici remotae-Calthetum laethae Coldea (1972 1978 ligularietosum sibiricae Alexiu et Stancu 2003. Habitat description and qualitative and quantitative analysis of association flora, it has an important role in establishing the conservation status of relict species Ligularia sibirica (L. Cass. Through obtained results, the present paper is contributing to the existent information related to the studied species and to the presentation of its preservation nowadays. Ligularia sibirica (L. Cass. species require real protective measures at the site.

  11. Hydrogeophysical investigations at Hidden Dam, Raymond, California

    Science.gov (United States)

    Minsley, Burke J.; Burton, Bethany L.; Ikard, Scott; Powers, Michael H.

    2011-01-01

    Self-potential and direct current resistivity surveys are carried out at the Hidden Dam site in Raymond, California to assess present-day seepage patterns and better understand the hydrogeologic mechanisms that likely influence seepage. Numerical modeling is utilized in conjunction with the geophysical measurements to predict variably-saturated flow through typical two-dimensional dam cross-sections as a function of reservoir elevation. Several different flow scenarios are investigated based on the known hydrogeology, as well as information about typical subsurface structures gained from the resistivity survey. The flow models are also used to simulate the bulk electrical resistivity in the subsurface under varying saturation conditions, as well as the self-potential response using petrophysical relationships and electrokinetic coupling equations.The self-potential survey consists of 512 measurements on the downstream area of the dam, and corroborates known seepage areas on the northwest side of the dam. Two direct-current resistivity profiles, each approximately 2,500 ft (762 m) long, indicate a broad sediment channel under the northwest side of the dam, which may be a significant seepage pathway through the foundation. A focusing of seepage in low-topography areas downstream of the dam is confirmed from the numerical flow simulations, which is also consistent with past observations. Little evidence of seepage is identified from the self-potential data on the southeast side of the dam, also consistent with historical records, though one possible area of focused seepage is identified near the outlet works. Integration of the geophysical surveys, numerical modeling, and observation well data provides a framework for better understanding seepage at the site through a combined hydrogeophysical approach.

  12. Seismic Hazard and Ground Motion Characterization at the Itoiz Dam (Northern Spain)

    Science.gov (United States)

    Rivas-Medina, A.; Santoyo, M. A.; Luzón, F.; Benito, B.; Gaspar-Escribano, J. M.; García-Jerez, A.

    2012-08-01

    This paper presents a new hazard-consistent ground motion characterization of the Itoiz dam site, located in Northern Spain. Firstly, we propose a methodology with different approximation levels to the expected ground motion at the dam site. Secondly, we apply this methodology taking into account the particular characteristics of the site and of the dam. Hazard calculations were performed following the Probabilistic Seismic Hazard Assessment method using a logic tree, which accounts for different seismic source zonings and different ground-motion attenuation relationships. The study was done in terms of peak ground acceleration and several spectral accelerations of periods coinciding with the fundamental vibration periods of the dam. In order to estimate these ground motions we consider two different dam conditions: when the dam is empty ( T = 0.1 s) and when it is filled with water to its maximum capacity ( T = 0.22 s). Additionally, seismic hazard analysis is done for two return periods: 975 years, related to the project earthquake, and 4,975 years, identified with an extreme event. Soil conditions were also taken into account at the site of the dam. Through the proposed methodology we deal with different forms of characterizing ground motion at the study site. In a first step, we obtain the uniform hazard response spectra for the two return periods. In a second step, a disaggregation analysis is done in order to obtain the controlling earthquakes that can affect the dam. Subsequently, we characterize the ground motion at the dam site in terms of specific response spectra for target motions defined by the expected values SA ( T) of T = 0.1 and 0.22 s for the return periods of 975 and 4,975 years, respectively. Finally, synthetic acceleration time histories for earthquake events matching the controlling parameters are generated using the discrete wave-number method and subsequently analyzed. Because of the short relative distances between the controlling

  13. Analysis on biomass and productivity of epilithic algae and their relations to environmental factors in the Gufu River basin, Three Gorges Reservoir area, China.

    Science.gov (United States)

    Ge, Jiwen; Wu, Shuyuan; Touré, Dado; Cheng, Lamei; Miao, Wenjie; Cao, Huafen; Pan, Xiaoying; Li, Jianfeng; Yao, Minmin; Feng, Liang

    2017-12-01

    The main purpose of this study conducted from August 2010 was to find biomass and productivity of epilithic algae and their relations to environmental factors and try to explore the restrictive factors affecting the growth of algae in the Gufu River, the one of the branches of Xiangxi River located in the Three Gorges Reservoir of the Yangtze River, Hubei Province, Central China. An improved method of in situ primary productivity measurement was utilized to estimate the primary production of the epilithic algae. It was shown that in rivers, lakes, and reservoirs, algae are the main primary producers and have a central role in the ecosystem. Chlorophyll a concentration and ash-free dry mass (AFDM) were estimated for epilithic algae of the Gufu River basin in Three Gorges Reservoir area. Environmental factors in the Gufu River ecosystem highlighted differences in periphyton chlorophyll a ranging from 1.49 mg m -2 (origin) to 69.58 mg m -2 (terminal point). The minimum and maximum gross primary productivity of epilithic algae were 96.12 and 1439.89 mg C m -2  day -1 , respectively. The mean net primary productivity was 290.24 mg C m -2  day -1 . The mean autotrophic index (AFDM:chlorophyll a) was 407.40. The net primary productivity, community respiration ratio (P/R ratio) ranged from 0.98 to 9.25 with a mean of 2.76, showed that autotrophic productivity was dominant in the river. Relationship between physicochemical characteristics and biomass was discussed through cluster and stepwise regression analysis which indicated that altitude, total nitrogen (TN), NO 3 - -N, and NH 4 + -N were significant environmental factors affecting the biomass of epilithic algae. However, a negative logarithmic relationship between altitude and the chlorophyll a of epilithic algae was high. The results also highlighted the importance of epilithic algae in maintaining the Gufu River basin ecosystems health.

  14. Examining time trends in the Oldowan technology at Beds I and II, Olduvai Gorge.

    Science.gov (United States)

    Kimura, Yuki

    2002-09-01

    The lithic analysis of the Bed I and II assemblages from Olduvai Gorge reveals both static and dynamic time trends in early hominids' technology from 1.8 to 1.2 m.y.a. The Bed I Oldowan (1.87-1.75 m.y.a.) is characterized by the least effort strategy in terms of raw material exploitation and tool production. The inclusion of new raw material, chert, for toolmaking in the following Developed Oldowan A (DOA, 1.65-1.53 m.y.a.) facilitated more distinctive and variable flaking strategies depending on the kind of raw materials. The unique characters of DOA are explainable by this raw material factor, rather than technological development of hominids. The disappearance of chert in the subsequent Developed Oldowan B and Acheulian (1.53-1.2 m.y.a.) necessitated a shift in tool production strategy more similar to that of Bed I Oldowan than DOA. However, the evidence suggests that Bed II hominids might have been more skillful toolmakers, intensive tool-users, and engaged in more active transport of stone tools than the Bed I predecessors. Koobi Fora hominids maintained a more static tool-using behavior than their Olduvai counterparts due mainly to a stable supply of raw materials. They differed from Olduvai hominids in terms of less battering of cores, consistent transport behavior, and few productions of side-struck flakes, indicating a regional variation of toolmaking and using practice. However, they shared with Olduvai hominids a temporal trend toward the production of larger flakes from larger cores after 1.6 m.y.a. Increased intake of animal resources and the expansion of ranging area of Homo ergaster would have led to the development of technological organization. Technological changes in the Oldowan industry are attested at Olduvai Gorge, Koobi Fora, and Sterkfontein, suggesting that it was a pan-African synchronous phenomenon, beginning at 1.5 m.y.a.

  15. Geological constraints on cave development in the plateau-gorge karst of South China (Wulong, Chongqing)

    Science.gov (United States)

    Szczygieł, Jacek; Golicz, Mateusz; Hercman, Helena; Lynch, Erin

    2018-03-01

    The Houping Tiankeng cluster is a part of the South China Karst UNESCO World Natural Heritage Site. Within the distinctive Wulong plateau-gorge karst, > 200 km of cave passages have been documented to date. This paper focuses on detailed tectonic and morphological research on the Luo Shui Kong cave, enriched with U-series dating of speleothems and complemented by morphometric analysis of the San Wang Dong and Er Wang Dong caves. All of these caves exhibit three regional levels of cave development: 1) 1040-1020 m a.s.l.; 2) 900-840 m a.s.l.; and 3) 740-660 m a.s.l. The Houping Tiankeng area is a carbonate rock sequence several hundred meters thick, overlain by the less soluble Lower Ordovician strata, limiting recharge points to faults exposing underlying easily soluble formations. This leads to the domination of concentrated, high-volume inflow and thus results in caves of large volume in the plateau-gorge karst. Shafts connecting the surface with cave passages located underneath formed along faults, changing the hydrogeological pattern through karst water capture and remodeling of existing conduits, albeit mainly by increasing their overall dimensions rather than by deepening them. The most favorable structures for cave-level development are two sets of joints conjugated with gently inclined bedding. Since these joints are characterized by a small vertical extent, downward development is limited. Hence, most of the passages are wide but not deep canyons and typical of a water-table cave pattern. Places where the fault plane is eroded from the surface and where, at the same time, an underneath cave chamber ceiling expands upwards are particularly predisposed to the formation of a tiankeng.

  16. Spatial Multicriteria Decision Analysis of Flood Risks in Aging-Dam Management in China: A Framework and Case Study

    Science.gov (United States)

    Yang, Meng; Qian, Xin; Zhang, Yuchao; Sheng, Jinbao; Shen, Dengle; Ge, Yi

    2011-01-01

    Approximately 30,000 dams in China are aging and are considered to be high-level risks. Developing a framework for analyzing spatial multicriteria flood risk is crucial to ranking management scenarios for these dams, especially in densely populated areas. Based on the theories of spatial multicriteria decision analysis, this report generalizes a framework consisting of scenario definition, problem structuring, criteria construction, spatial quantification of criteria, criteria weighting, decision rules, sensitivity analyses, and scenario appraisal. The framework is presented in detail by using a case study to rank dam rehabilitation, decommissioning and existing-condition scenarios. The results show that there was a serious inundation, and that a dam rehabilitation scenario could reduce the multicriteria flood risk by 0.25 in the most affected areas; this indicates a mean risk decrease of less than 23%. Although increased risk (<0.20) was found for some residential and commercial buildings, if the dam were to be decommissioned, the mean risk would not be greater than the current existing risk, indicating that the dam rehabilitation scenario had a higher rank for decreasing the flood risk than the decommissioning scenario, but that dam rehabilitation alone might be of little help in abating flood risk. With adjustments and improvement to the specific methods (according to the circumstances and available data) this framework may be applied to other sites. PMID:21655125

  17. Hydro-geomorphology of the middle Elwha River, Washington, following dam removal

    Science.gov (United States)

    Morgan, J. A.; Nelson, P. A.; Brogan, D. J.

    2017-12-01

    Dam removal is an increasingly common river restoration practice, which can produce dramatic increases in sediment supply to downstream reaches. There remains, however, considerable uncertainty in how mesoscale morphological units (e.g., riffles and pools) respond to the flow and sediment supply changes associated with dam removal. The recent removal of Glines Canyon Dam on the Elwha River in Washington State provides a natural setting to explore how increased sediment supply due to dam removal may affect downstream reaches. Here, we present observations and surveys documenting how a 1 km reach, located approximately 5 km downstream of the former dam site, has evolved following dam removal. Annual topographic/bathymetric surveys were conducted in 2014-2016 using RTK-GNSS methods, and these surveys were coupled with airborne lidar to create continuous surface maps of the valley bottom. Differencing the elevation models reveals channel widening and migration due to lateral bank retreat and bar aggradation. Analysis of aerial imagery dating back to 1939 suggests that rates of both widening and meander migration have increased following dam removal. We also used results from depth-averaged hydrodynamic modeling with a fuzzy c-means clustering approach to delineate riffle and pool units; this analysis suggests that both riffles and pools stayed relatively consistent from 2014-2015, while both areas decreased from 2015 to 2016. Without any considerable changes to the hydrologic regime these higher rates of change are implied to be the result of the increased sediment supply. Our results, which indicate an increased dynamism due directly to the amplified sediment supply, have the potential to further inform river managers and restoration specialists who oversee projects related to changing sediment regimes.

  18. Novel monitoring protocol for the Monte Cotugno Dam (Southern Italy) healthiness

    Science.gov (United States)

    Soldovieri, Francesco; Loperte, Antonio

    2015-04-01

    This work is concerned with the application of an integrated approach based on a non-invasive geophysical technique, as the Electrical Resistivity Tomography (ERT) and geotechnical and visual inspections for the monitoring of the Monte Cotugno dam, the largest rock fill dam in Europe. Monte Cotugno dam is located on the Sinni river (Basilicata District, South Italy) and represents the nodal point of the whole hydraulic system on the Ionic side of Italy. In fact, the dam allows harnessing of the Sinni river water for agricultural, industrial, drinking and domestic purposes. The dam consists of a central core in sandy silt and of gravelly-sandy shoulders; its water tightness is ensured by a bituminous conglomerate facing on the upstream side, welded at the bottom to the foundation sealing system. The latter is about 1,900m long and consist of a massive concrete cut-off wall based on the marly-clay formation, 300m long on the right and 600 m long on the left side. On the valley bottom, dam is made up of a reinforced concrete cut-off wall that is inserted in the marly-clay formation and is surmounted by an inspection and percolation water collection tunnel. The watertight face consists of different layers and the shallowest layers have been affected by incipient small detachments due to thermal solicitations; These detachments affect the structural behavior of the dam, since they are way for water infiltration in the dam. For this reason, on 2010 dam's owner decided to activate an integrated geophysical survey based on the integrated use of Infrared Termography, ERT and Ground Penetrating Radar, with the aim to identify and evaluate the potential loss of water through small cracks in the bituminous concrete dam [1]. Following the results achieved by this non-invasive integrated approach, it was decided to activate a long term monitoring based on periodic ERT surveys. In particular, ERT surveys were carried out for two years at two specific times of the year, in order

  19. Malaria and large dams in sub-Saharan Africa: future impacts in a changing climate.

    Science.gov (United States)

    Kibret, Solomon; Lautze, Jonathan; McCartney, Matthew; Nhamo, Luxon; Wilson, G Glenn

    2016-09-05

    Sub-Saharan Africa (SSA) has embarked on a new era of dam building to improve food security and promote economic development. Nonetheless, the future impacts of dams on malaria transmission are poorly understood and seldom investigated in the context of climate and demographic change. The distribution of malaria in the vicinity of 1268 existing dams in SSA was mapped under the Intergovernmental Panel on Climate Change (IPCC) representative concentration pathways (RCP) 2.6 and 8.5. Population projections and malaria incidence estimates were used to compute population at risk of malaria in both RCPs. Assuming no change in socio-economic interventions that may mitigate impacts, the change in malaria stability and malaria burden in the vicinity of the dams was calculated for the two RCPs through to the 2080s. Results were compared against the 2010 baseline. The annual number of malaria cases associated with dams and climate change was determined for each of the RCPs. The number of dams located in malarious areas is projected to increase in both RCPs. Population growth will add to the risk of transmission. The population at risk of malaria around existing dams and associated reservoirs, is estimated to increase from 15 million in 2010 to 21-23 million in the 2020s, 25-26 million in the 2050s and 28-29 million in the 2080s, depending on RCP. The number of malaria cases associated with dams in malarious areas is expected to increase from 1.1 million in 2010 to 1.2-1.6 million in the 2020s, 2.1-3.0 million in the 2050s and 2.4-3.0 million in the 2080s depending on RCP. The number of cases will always be higher in RCP 8.5 than RCP 2.6. In the absence of changes in other factors that affect transmission (e.g., socio-economic), the impact of dams on malaria in SSA will be significantly exacerbated by climate change and increases in population. Areas without malaria transmission at present, which will transition to regions of unstable transmission, may be worst affected

  20. Arc structure of the DAM Jupiter Emission

    International Nuclear Information System (INIS)

    Leblanc, Y.

    1981-01-01

    An analysis of the dynamic spectra of the Jovian DAM emission (1.3--40 MHz) has been made from Voyager data; it appears that the different Jovian 'sources' can be defined by spectral chaaracteristics, rather than by occurrence probability. The non-Io emission consists of two families: vertex early arcs (VEA) and vertex late arcs (VLA). These two families are superimposed at all longitudes, but one is always more intense than the other. The characterics of the two families are specified; in particular, it is shown that the VEA family is more stable in time than the VLA family. The Io-controlled emission consists of the four sources already known from the ground-based observations in addition to a new source (Io-A')sp, identified by its dynamic spectrum alone. All of the sources are partially superimposed on non-Io emission. The (Io-B)sp and (Io-A')sp sources are made up of low-curvature arcs having low-frequency limits above 5 MHz. The high-frequency limit of the (Io-B)sp source is strongly modulated by Io-phase. The (Io-A)sp source has a specturm similar to the non-Io VLA emission. The other two sources, (Io-C)sp and (Io-D)sp, are not structured into well-defined arcs. A comparsion is made between the occurrence of these sources in the Io-CML plane with the sources defined from ground observations by probability of occurrence. Local time effects are observed only in the non-Io emission when compared before and after encounter. Before encounter, the VEA family is very weak and the VLA family very intense. After encounter, the opposite effect is observed. The Io-controlled sources are not affected by these local time effects

  1. Fluvial River Regime in Disturbed River Systems: A Case Study of Evolution of the Middle Yangtze River in Post-TGD (Three Gorges Dam), China

    NARCIS (Netherlands)

    Zhao, G.; Lu, J; Visser, P.J.

    2015-01-01

    The fluvial river is a kind of open system that can interact with its outside environments and give response to disturbance from outside on the earth. It can adjust itself to the disturbances outside the system and reflects new characteristics in the process of reaching a new equilibrium. The TGD

  2. Dams, Hydrology and Risk in Future River Management

    Science.gov (United States)

    Wegner, D. L.

    2017-12-01

    Across America there are over 80,000 large to medium dams and globally the number is in excess of 800,000. Currently there are over 1,400 dams and diversion structures being planned or under construction globally. In addition to these documented dams there are thousands of small dams populating watersheds. Governments, agencies, native tribes, private owners and regulators all have a common interest in safe dams. Often dam safety is characterized as reducing structural risk while providing for maximum operational flexibility. In the 1970's there were a number of large and small dam failures in the United States. These failures prompted the federal government to issue voluntary dam safety guidelines. These guidelines were based on historic information incorporated into a risk assessment process to analyze, evaluate and manage risk with the goal to improve the quality of and support of dam management and safety decisions. We conclude that historic and new risks need to be integrated into dam management to insure adequate safety and operational flexibility. A recent assessment of the future role of dams in the United States premises that future costs such as maintenance or removal beyond the economic design life have not been factored into the long-term operations or relicensing of dams. The converging risks associated with aging water storage infrastructure, multiple dams within watersheds and uncertainty in demands policy revisions and an updated strategic approach to dam safety. Decisions regarding the future of dams in the United States may, in turn, influence regional water planning and management. Leaders in Congress and in the states need to implement a comprehensive national water assessment and a formal analysis of the role dams play in our water future. A research and national policy agenda is proposed to assess future impacts and the design, operation, and management of watersheds and dams.

  3. Experience with embankment dam safety evaluation in Alberta

    International Nuclear Information System (INIS)

    Houston, M.; Morgenstern, N.R.

    1989-01-01

    Following a rash of dam failures in the 1970s, many jurisdictions responded with the implementation of both legislation and regulations mandating dam safety evaluations. Almost all dams in Alberta are embankment dams, of which failures are mainly caused by: overtopping during flood discharge due to inadequate spillway capacity or non-functioning floodgates; internal erosion along the dam foundation interface; non-homogeneity in the foundation or dam, leading to foundation failure or erosion; large settlements in the foundation; cracks following settlement, with resultant piping; and liquefaction. Summaries are presented of a series of case histories of dam safety evaluations conducted in Alberta where the outcome was not routine. The case histories describe evaluations carried out at the following dams. The Bighorn hydroelectric development was completed in 1972, and measured seepage was found to be ten times greater than a recommended alert level. Dam safety evaluations concluded that the performance of the dam and concrete cutoff wall is satisfactory, but the owner reads all monitoring instrumentation on a regular basis and seeks on-going review from consultants. The Three Sisters Dam is a 21 m high homogeneous embankment hydroelectric dam. Very large seepage flows were found, and although remedial measures have been effective, extreme vigilence with an intensive inspection and monitoring program is required. Other case studies detail seepage monitoring at the St. Mary Dam, complex seepage patterns at Waterton Dam and Tavers Dam, and material durability studies at Hartung Dam and Murray Dam. The importance of good records and construction and performance histories is emphasized. 12 figs., 10 refs

  4. Numerical modelling dam break analysis for water supply project

    International Nuclear Information System (INIS)

    Lariyah, M S; Vikneswaran, M; Hidayah, B; Muda, Z C; Thiruchelvam, S; Isham, A K Abd; Rohani, H

    2013-01-01

    Dam provides many benefits to the society, but it can also cause extensive damage to downstream area when it fails. Dam failure can cause extensive damage to properties and loss of human life due to short warning time available. In general, dam spillway was designed to drain the maximum discharge from the dam during the Probable Maximum Flood (PMF). The spillway is functioned to prevent the dam from failure due to overtopping, which can lead to the dam failure. Dam failure will result in large volume of water travelling at very high velocity to the downstream area of the dam. It can cause extensive property damage, destruction of important facilities, and significant loss of human life along the way. Due to the potential of high hazard it poses to the downstream area, a dam break analysis is considered very essential. This paper focuses into the dam failure analysis for Kahang Dam by prediction of breach flow hydrographs and generation of inundation map at downstream area. From the PMF scenario simulation, the maximum inflow is 525.12 m 3 /s and peak discharge from the dam during dam failure is 6188m 3 /s. The results are able to provide information for preparation of Emergency Response Plan (PMF), in which appropriate steps can be taken by relevant authorities to avoid significant loss of human lives.

  5. Meta-analysis of environmental effects of beaver in relation to artificial dams

    Science.gov (United States)

    Ecke, Frauke; Levanoni, Oded; Audet, Joachim; Carlson, Peter; Eklöf, Karin; Hartman, Göran; McKie, Brendan; Ledesma, José; Segersten, Joel; Truchy, Amélie; Futter, Martyn

    2017-11-01

    Globally, artificial river impoundment, nutrient enrichment and biodiversity loss impair freshwater ecosystem integrity. Concurrently, beavers, ecosystem engineers recognized for their ability to construct dams and create ponds, are colonizing sites across the Holarctic after widespread extirpation in the 19th century, including areas outside their historical range. This has the potential to profoundly alter hydrology, hydrochemistry and aquatic ecology in both newly colonized and recolonized areas. To further our knowledge of the effects of beaver dams on aquatic environments, we extracted 1366 effect sizes from 89 studies on the impoundment of streams and lakes. Effects were assessed for 16 factors related to hydrogeomorphology, biogeochemistry, ecosystem functioning and biodiversity. Beaver dams affected concentrations of organic carbon in water, mercury in water and biota, sediment conditions and hydrological properties. There were no overall adverse effects caused by beaver dams or ponds on salmonid fish. Age was an important determinant of effect magnitude. While young ponds were a source of phosphorus, there was a tendency for phosphorus retention in older systems. Young ponds were a source methylmercury in water, but old ponds were not. To provide additional context, we also evaluated similarities and differences between environmental effects of beaver-constructed and artificial dams (767 effect sizes from 75 studies). Both are comparable in terms of effects on, for example, biodiversity, but have contrasting effects on nutrient retention and mercury. These results are important for assessing the role of beavers in enhancing and/or degrading ecological integrity in changing Holarctic freshwater systems.

  6. The effect of rubber dam on atmospheric bacterial aerosols during restorative dentistry.

    Science.gov (United States)

    Al-Amad, Suhail H; Awad, Manal A; Edher, Faraj M; Shahramian, Khalil; Omran, Tarek A

    Rotatory dental instruments generate atmospheric aerosols that settle on various surfaces, including the dentist's head. The aim of this study was to quantitatively assess bacterial contamination of the dentist's head and to evaluate whether it is affected by using a rubber dam. Senior dental students (n=52) were asked to wear autoclaved headscarves as collection media while performing restorative dental treatment with and without a rubber dam. Four points from each headscarf were swabbed for bacterial culture after 30min of operative work. Bacterial contamination was quantified by counting the colony-forming units. Regardless of the collection point, using a rubber dam was associated with more bacterial colony-forming units than not using a rubber dam (P=0.009). Despite its clinical value, the rubber dam seems to result in significantly higher aerosol levels on various areas of the dentist's head, requiring that dentists cover their heads with suitable protective wear. Copyright © 2016 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

  7. Chixoy Dam Legacies: The Struggle to Secure Reparation and the Right to Remedy in Guatemala

    Directory of Open Access Journals (Sweden)

    Barbara Rose Johnston

    2010-06-01

    Full Text Available The World Commission on Dams brought global attention to the adverse costs of large dam development, including the disproportionate displacement of indigenous peoples and ethnic minorities and the extreme impoverishment of development refugees. The WCD recommended that governments, industry and financial institutions accept responsibility for flawed development and make proper reparation, including remedial activities such as the restoration of livelihood and land compensation for relocated communities. One exemplary case cited is Guatemala’s Chixoy dam. Completed in 1982, this internationally financed dam was built during a time when military dictatorships deployed policies of state-sponsored violence against a Mayan citizenry. Construction occurred without a resettlement plan, and forced displacement occurred through violence and massacre. This paper describes an attempt to implement WCD reparation recommendations in a context where no political will existed. To clarify events, abuses and meaningful remedy, an independent assessment process was established in 2003, auditing the development record, assessing consequential damages and facilitating the community articulation of histories and needs. The resulting 2005 study played a key role in reparation negotiations. The Chixoy case illustrates some of the more profound impacts of the WCD review. The WCD served as a catalyst in social movement formation and a force that expanded rights-protective space for dam-affected communities to negotiate an equitable involvement in development.

  8. Past, Present, and Future Nutrient Quality of a Small Southeastern River: A Pre-Dam Assessment

    Directory of Open Access Journals (Sweden)

    Paul M. Stewart

    2013-07-01

    Full Text Available Riverine dams alter both the physical environment and water chemistry, thus affecting species assemblages within these environments. In the United States, dam construction is on the decline and there is a growing trend for dam removal. The Choctawhatchee, Pea, and Yellow Rivers Watershed Management Authority had initiated the permitting process for placing a reservoir dam on the Little Choctawhatchee River (LCR, a tributary to the Choctawhatchee River. The purpose of the proposed reservoir was water supply, and while the permit application has been suspended, history shows that this or related projects are likely to arise in the future. This study collected data on nutrient quality seasonally (four times from 12 sites in the LCR watershed from October 2007 to June 2008 in order to determine pre-dam conditions and to compare these data to historical and regional information. Historical and current nutrient concentrations were elevated throughout the watershed, in most cases above suggested criteria, and indicated that water quality of the river was and continues to be nutrient rich. A future reservoir at recent levels of water quality will likely be highly eutrophic, and anthropogenic influences will further stress this ecosystem and its water quality as the urban region expands.

  9. Flood effects provide evidence of an alternate stable state from dam management on the Upper Missouri River

    Science.gov (United States)

    Skalak, Katherine; Benthem, Adam J.; Hupp, Cliff R.; Schenk, Edward R.; Galloway, Joel M.; Nustad, Rochelle A.

    2017-01-01

    We examine how historic flooding in 2011 affected the geomorphic adjustments created by dam regulation along the approximately 120 km free flowing reach of the Upper Missouri River bounded upstream by the Garrison Dam (1953) and downstream by Lake Oahe Reservoir (1959) near the City of Bismarck, ND, USA. The largest flood since dam regulation occurred in 2011. Flood releases from the Garrison Dam began in May 2011 and lasted until October, peaking with a flow of more than 4200 m3 s−1. Channel cross-section data and aerial imagery before and after the flood were compared with historic rates of channel change to assess the relative impact of the flood on the river morphology. Results indicate that the 2011 flood maintained trends in island area with the loss of islands in the reach just below the dam and an increase in island area downstream. Channel capacity changes varied along the Garrison Segment as a result of the flood. The thalweg, which has been stable since the mid-1970s, did not migrate. And channel morphology, as defined by a newly developed shoaling metric, which quantifies the degree of channel braiding, indicates significant longitudinal variability in response to the flood. These results show that the 2011 flood exacerbates some geomorphic trends caused by the dam while reversing others. We conclude that the presence of dams has created an alternate geomorphic and related ecological stable state, which does not revert towards pre-dam conditions in response to the flood of record. This suggests that management of sediment transport dynamics as well as flow modification is necessary to restore the Garrison Segment of the Upper Missouri River towards pre-dam conditions and help create or maintain habitat for endangered species. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

  10. Using Choice Experiments to Assess Environmental Impacts of Dams in Portugal

    Directory of Open Access Journals (Sweden)

    Anabela Botelho

    2015-08-01

    Full Text Available Despite their well-known benefits in electricity production, dams are also responsible for some adverse environmental impacts affecting particularly the wellbeing of residents of the local communities. These environmental damages have not been included in the cost-benefit analysis of hydropower developments mainly because of the difficulty to determine their value. The prime objective of this paper is to measure the economic values of several environmental impacts due to the dams' activity in Portugal, using a discrete choice experiments approach. With the results of this research paper, we expect to contribute to a more efficient and thorough cost-benefit analysis within the complex process of deciding the optimal location of future dams to be built not only in Portugal, but elsewhere. The addition of this stage to the decision-making process allows the integration of economic, social and environmental dimensions, promoting a richer and more informed decision process.

  11. Game-Theory Based Research on Oil-Spill Prevention and Control Modes in Three Gorges Reservoir Area

    Science.gov (United States)

    Yin, Jie; Xiong, Ting

    2018-01-01

    Aiming at solving the existing oil pollution in the Three Gorges reservoir, this paper makes research on oil-spill prevention and control mode based on game theory. Regarding the built modes and comparative indicator system, overall efficiency indicator functions are used to compare general effect, overall cost, and overall efficiency, which concludes that the mode combining government and enterprise has the highest overall efficiency in preventing and controlling ship oil spills. The suggested mode together its correspondingly designed management system, has been applied to practice for a year in Three Gorges Reservoir Area and has made evident improvements to the existing oil pollution, meanwhile proved to be quite helpful to the pollution prevention and control in the lower reaches of Yangtze River.

  12. Seismic response of concrete gravity dam reinforced with FRP sheets on dam surface

    Directory of Open Access Journals (Sweden)

    Hong Zhong

    2013-10-01

    Full Text Available This paper aims at exploring the effects of anti-seismic reinforcement with the fiber-reinforced polymer (FRP material bonded to the dam surface in dam engineering. Time-history analysis was performed to simulate the seismic failure process of a gravity dam that was assumed to be reinforced at the locations of slope discontinuity at the downstream surface, part of the upstream face, and the dam heel. A damage model considering the influence of concrete heterogeneity was used to model the nonlinearity of concrete. A bond-slip model was applied to the interface between FRP and concrete, and the reinforcement mechanism was analyzed through the bond stress and the stress in FRP. The results of the crack pattern, displacement, and acceleration of the reinforced dam were compared with those of the original one. It is shown that FRP, as a reinforcement material, postpones the occurrence of cracks and slows the crack propagation, and that cracks emanating from the upstream surface and downstream surface are not connected, meaning that the reinforced dam can retain water-impounding function when subjected to the earthquake. Anti-seismic reinforcement with FRP is therefore beneficial to improving the seismic resistant capability of concrete dams.

  13. Whole-rock U-Pb dating of the Shuijingtuo formation sedimentary rocks in the Yangtze Gorge

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Y.F. (Goettingen Univ. (Germany, F.R.). Geochemisches Inst.); Zhou, H.F. (Tianjing Inst. of Geology and Mineral Resources, TJ (China)); Huang, B. (Guilin Inst. of Mineral Resources and Geology, GX (China))

    1990-01-01

    Black shale and enclosed limestone lenticule from Lower Cambrian Shuijingtuo Formation in the Yangtze Gorge is successfully dated by whole-rock U-Pb method. The results yield a concordant age of about 573+-14 Ma, in excellent agreement with both stratigraphic and palaeontologic evidence. The whole-rock U-Pb method can provide a reliable approach for age determination of sedimentary stratum. (orig.).

  14. The Morphological Evolution of the Breach Channel by Prototype Field Experimental of Landslide Dam

    Science.gov (United States)

    Xuan, S. K.; Chen, S. C.

    2016-12-01

    Landslide dam breach release the large amounts of water and sediment, which cause dramatic change in downstream channels. In previous studies, data collection from the landslide dam breach could be obtained from two sources. One is monitoring field cases and another one is the small scale laboratory tests. However, the prototype field experiment combined the advantages of both. The dam breach was more similar to real event in this experiment, which improved the shortcomings of the lab test including too small scale, over-simplified and the boundary effect. On the other hand, it also solves the problems of the incomplete and unrepeatable data collection in the field cases investigation. Therefore, the evolution of channel morphology caused by hydrological processes of landslide dam breach was analyzed by using the pressure gauges, Acoustic Doppler Velocity Profiler (ADCP), photographic monitoring, topographic measurement of 3D Lidar in the Landao Creek, the Huisun Experimental Forest, Central Taiwan in this study. The peak outflow was affected mainly by the breach cross section. Therefore, the velocity of the breach cross section was measured by ADCP and its development was analyzed by the bathymetry function of ADCP combined with images analysis. The downstream sediment concentration affected by the sediment loss of the breach cross section was estimated by taking the water sample during the dam breaching. In addition, this study observed the deposition after breaching experiment, which was compared with the channel morphology after natural extreme hydrological events, by topographic measurement. The result of water sampling showed that the sediment concentration raised from 1.57% upstream to 6.13% downstream of the dam. A fourfold increase of sediment carrying capacity by flood caused serious deposition in downstream and the deposition height was about 10 cm.

  15. Lac Courte Oreilles Hydro Dam Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Jason [Lac Courte Oreilles, Hayward, WI (United States); Meyers, Amy [Kiser Hydro, LLC, Norway, MI (United States)

    2014-12-31

    The main objective of this project was to investigate upgrading the existing hydro power generating system at the Winter Dam. The tribe would like to produce more energy and receive a fair market power purchase agreement so the dam is no longer a drain on our budget but a contributor to our economy. We contracted Kiser Hydro, LLC Engineering for this project and received an engineering report that includes options for producing more energy with cost effective upgrades to the existing turbines. Included in this project was a negotiation of energy price sales negotiations.

  16. Hydroelectric dams need billions for rehab

    International Nuclear Information System (INIS)

    Carr, F.H.; Soast, A.

    1993-01-01

    Many of the Corps of Engineers older hydroelectric dams will require major rehabilitation over the next ten years. Preventive maintenance, repair work, and major rehabilitation of the Corp's hydro dams in inadequate because the revenue generated by sales of electricity, by law, is returned to the Treasury. Most multimillion dollar rehabilitation projects require specific approval for funding by Congress and securing it is a long and difficult process. It is hoped the funding problem will soon be addressed by the Clinton administration. Already, nearly one-sixth of the 2,154 Mw of hydro is unavailable because with hydro units are either out of service or operating at less than full capacity

  17. Official opening of the Olympic Dam project

    International Nuclear Information System (INIS)

    Parbo, A.

    1989-01-01

    This is the text of an address given on November 5, 1988 to mark the commencement of production of copper, uranium, gold and silver from the first stage of the Olympic Dam project at Roxby Downs, South Australia. The huge deposit was discovered in 1975 and years of exploration, underground development, metallurgical testing, planning and establishing the infrastructure followed, at a cost of $750 million. 740 people are now employed at Olympic Dam. The first shipment of copper and uranium oxide left for Sweden at the end of November 1988. The deposit is able to support a much higher production rate as the market for the products, particularly uranium, improves

  18. National Inventory of Dams Coastal California Extract 2010

    Data.gov (United States)

    California Department of Resources — The National Inventory of Dams (NID) is a congressionally authorized database, which documents dams in the U.S. and its territories. The NID was most recently...

  19. National Inventory of Dams Coastal California Extract 2010

    Data.gov (United States)

    California Natural Resource Agency — The National Inventory of Dams (NID) is a congressionally authorized database, which documents dams in the U.S. and its territories. The NID was most recently...

  20. Inventory of Dams in the State of Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Permitted dams in Iowa and associated attributes, as recorded by the Floodplain Section of the DNR. The dams regulated are those with the parameters listed below: a....

  1. Macrobenthic Communities of the Dam Neck Disposal Site.

    Science.gov (United States)

    1985-02-01

    catharinensis Muller Byblis aerrata Smith 0 Caprellidae app. Corophium app. Gammarus sp. Listriella barnardi Wigley Protohaustorius spp...TABLE 2 : Hydrographic Measurements at Dam Neck Stations (A) - Dam Neck Extension Stations Station Date Bottom Salinity Bottom Temperature Depth (ppt

  2. Timber box dams - an alternative for small power plants

    International Nuclear Information System (INIS)

    Lia, Leif

    2005-01-01

    The article discusses timber dams as an alternative concrete or stone filling dams for small power plants. Old knowledge, advantages and disadvantages are mentioned as well as some examples and environmental aspects

  3. Dam-Break Flood Analysis Upper Hurricane Reservoir, Hartford, Vermont

    National Research Council Canada - National Science Library

    Acone, Scott

    1995-01-01

    .... Various dam break flood conditions were modeled and inundation maps developed. Based on this analysis the dam is rated a Class 2 or significant hazard category in terms of its potential to cause downstream damage...

  4. Investigation on the Causes of Cracking in Earth Dams (Case study: Mahmood-Abad Earth Dam

    Directory of Open Access Journals (Sweden)

    H. Rahimi

    2016-09-01

    Full Text Available Introduction: Cracking of earth dams is a one of the main threat causes of stability of embankment dams. In this research by modeling of the behavior of an embankment dam and employing conditions of the earthquake, the reasons of cracking were inspected using by modeling of earth dam behavior. Based on the literature, one of the main causes of dam failures is sliding and cracking of the dam structure during earthquake. Localized liquefaction of foundation soils was one of the causes of the observed post-earthquake distress within these dams. Material and Methods: In order to study the causes and the results of crack on earth dams, Mahmoodabad earthen dam with a height of 19 m, is located in Zanjan province, northwest of Iran, which suffered a longitudinal crack on the crest and slight sliding of the upstream slope due to 2001 Avaj earthquake was studied. This dam has faced earthquake two times with an interval of two years. During the first earthquake with the magnitude about 6.6 in Richter scale small longitudinal cracks had created on the crest. The developed cracks had been repaired by injecting the cement and then has been hidden by passing the time. After the second earthquake with the magnitude about 6.5 in Richter scale the hidden cracks had been appeared again and the slight movement of the upper slopes of dam reported. Based on the site investigation and documented information about dam, including maps and parameter data, the behavior of the dam has modeled by using Plaxis as a finite element model. In order to check the accuracy of the design of dam, the stability analysis has been conducted using by Xslope as a limit equilibrium model. The foundation conditions and the Geotechnical properties of the layer beneath the dam has been inspected by open excavation. Results and Discussion: Underground investigation about Geotechnical properties of dam foundation has showed that there is a thin sandy layer confined in alluvium material of the

  5. Atmospheric deposition inputs and effects on lichen chemistry and indicator species in the Columbia River Gorge, USA

    International Nuclear Information System (INIS)

    Fenn, M.E.; Geiser, L.; Bachman, R.; Blubaugh, T.J.; Bytnerowicz, A.

    2007-01-01

    Topographic and meteorological conditions make the Columbia River Gorge (CRG) an 'exhaust pipe' for air pollutants generated by the Portland-Vancouver metropolis and Columbia Basin. We sampled fog, bulk precipitation, throughfall, airborne particulates, lichen thalli, and nitrophytic lichen distribution. Throughfall N and S deposition were high, 11.5-25.4 and 3.4-6.7 kg ha -1 over 4.5 months at all 9 and 4/9 sites, respectively. Deposition and lichen thallus N were highest at eastern- and western-most sites, implicating both agricultural and urban sources. Fog and precipitation pH were frequently as low as 3.7-5.0. Peak NO x , NH 3 , and SO 2 concentrations in the eastern CRG were low, suggesting enhanced N and S inputs were largely from particulate deposition. Lichens indicating nitrogen-enriched environments were abundant and lichen N and S concentrations were 2x higher in the CRG than surrounding national forests. The atmospheric deposition levels detected likely threaten Gorge ecosystems and cultural resources. - Nitrogen, sulfur and acidic deposition threaten natural and cultural resources in the Columbia River Gorge National Scenic Area

  6. Atmospheric deposition inputs and effects on lichen chemistry and indicator species in the Columbia River Gorge, USA

    Energy Technology Data Exchange (ETDEWEB)

    Fenn, M.E. [USDA Forest Service, Pacific Southwest Research Station, 4955 Canyon Crest Drive, Riverside, CA 92507 (United States)]. E-mail: mfenn@fs.fed.us; Geiser, L. [USDA Forest Service, Siuslaw National Forest, PO Box 1148, Corvallis, OR 97339 (United States); Bachman, R. [USDA Forest Service, Pacific Northwest Regional Office, PO Box 3623, Portland, OR 97208 (United States); Blubaugh, T.J. [USDA Forest Service, Pacific Southwest Research Station, 4955 Canyon Crest Drive, Riverside, CA 92507 (United States); Bytnerowicz, A. [USDA Forest Service, Pacific Southwest Research Station, 4955 Canyon Crest Drive, Riverside, CA 92507 (United States)

    2007-03-15

    Topographic and meteorological conditions make the Columbia River Gorge (CRG) an 'exhaust pipe' for air pollutants generated by the Portland-Vancouver metropolis and Columbia Basin. We sampled fog, bulk precipitation, throughfall, airborne particulates, lichen thalli, and nitrophytic lichen distribution. Throughfall N and S deposition were high, 11.5-25.4 and 3.4-6.7 kg ha{sup -1} over 4.5 months at all 9 and 4/9 sites, respectively. Deposition and lichen thallus N were highest at eastern- and western-most sites, implicating both agricultural and urban sources. Fog and precipitation pH were frequently as low as 3.7-5.0. Peak NO{sub x}, NH{sub 3}, and SO{sub 2} concentrations in the eastern CRG were low, suggesting enhanced N and S inputs were largely from particulate deposition. Lichens indicating nitrogen-enriched environments were abundant and lichen N and S concentrations were 2x higher in the CRG than surrounding national forests. The atmospheric deposition levels detected likely threaten Gorge ecosystems and cultural resources. - Nitrogen, sulfur and acidic deposition threaten natural and cultural resources in the Columbia River Gorge National Scenic Area.

  7. Canyons and gorges as potential geotourism destinations in Serbia: comparative analysis from two perspectives - general geotourists' and pure geotourists'

    Science.gov (United States)

    Božić, Sanja; Tomić, Nemanja

    2015-10-01

    Serbia represents one of those countries which have not yet differentiated themselves on the world tourism map. However, it has an immense but still unrevealed potential for geotourism development. In this paper we analyzed several remarkable canyons and gorges of great scientific importance and geotourism potential. These sites include the Djerdap Gorge and Lazar River Canyon, located in Eastern Serbia and the Ovcar-Kablar Gorge and Uvac Canyon located in Western Serbia. One of the main goals of this paper was to analyze and compare the current state and tourism potential of these geosites by using the M-GAM model for geosite assessment. However, the principal aim of the paper is to analyze how important is each subindicator in the assessment process for different market segments. In this paper, we also analyzed how giving different importance to subindicators can influence the position of the geosites in the matrix indicating different assessment done by two chosen market segments. The research showed that general geotourists appreciate considerably different values when assessing a geosite in comparison to pure geotourists. The paper can be used as framework for developing the tourism management strategy of geosites taking into consideration the needs and preferences of the target market segments.

  8. [Comparison of trophic status analysis of the Daning River within the Three Gorges Reservoir before and after experimental impoundment].

    Science.gov (United States)

    Zhang, Jia-Lei; Zheng, Bing-Hui; Liu, Lu-San; Wang, Li-Jing; Wu, Guang-Ying

    2012-10-01

    We evaluated 4-year data set to assess the trophic state and limiting factors of the Three Gorges Reservoir (TGR) during the experimental impounding period (September 2005 to September 2007) and the normal operating period (September 2008 to September 2010). The results indicated that there had been appeared new characteristics in spatial and temporal distribution of trophic state indices after impoundment. The trophic state indices (TSI(TP)) showed increased trend after the TGR impoundment during the study area, but TSI(TN) and TSI(SD) had no significant changes after the TGR impoundment. The values of TSI(CHL) showed increased trend after the TGR impoundment in S1, and the values of TSI(CHL) did not show obvious changes in S2, S3 and S4 after the TGR impoundment. The values of TSI(TN), TSI(TP) and TSI(SD) show similar spatial variances with the highest value in S4, followed in a descending order by S3, S2 and S1. TSI(CHL) in the S2 and S3 were higher than that in S1 and S4. According to the characteristics of water level, the operational period of the TGR classified into following four stages: stage I (pre-November-April), stage II (May-July), stage III (July-September) and stage IV (September-November). The values of TSI(TN) and TSI(TP) in the Daning River and the TGR mainstream showed similar seasonal variances with the highest value in the stage II and III, followed in a descending order by stage I and IV. The values of TSI(CHL) varied substantially among the four stages, with the highest value in stage III, followed by stage II, IV and I. The trophic state indices differences were getting smaller between the four stages after the TGR impoundment. Using Carlson's two-dimensional approach, deviations of the TSI(S) indicated that factors other than phosphorous and nitrogen limited algal growth and that nonalgal particles affected light attenuation. These findings were further supported by the significant correlation among the values of TSI and hydrological

  9. Dynamic analysis of Moste concrete gravity dam with CADAM software

    OpenAIRE

    Novak, Matic

    2013-01-01

    In this thesis a short literature overview is given for simplified dynamic analysis of concrete gravity dams. A parametric study using CADAM software was conducted. By this study the Moste concrete gravity dam response was analyzed for different loads and earthquake accelerations. The results showed that safety of Moste dam is comparable to its design safety. Also is shown that the Moste dam would sustain more intense horizontal ground movement than the designed values for sliding and overtur...

  10. Design and Construction of Dams, Reservoirs, and Balancing Lakes

    International Nuclear Information System (INIS)

    Lemperiere, F.

    2003-01-01

    The general data presented in sections two and three gives an idea of the extreme diversity of the millions of very large or very small dams worldwide. Dam design and construction methods for the most usual types of large dams are presented and justified in section four. The possibility and usefulness of building as many dams in the 21. century as have been built in the 20. is analyzed in section six. (author)

  11. Long-term changes in fish assemblage following the impoundments of the Three Gorges Reservoir in Hejiang, a protected reach of the upper Yangtze River

    Directory of Open Access Journals (Sweden)

    Liu F.

    2013-03-01

    Full Text Available The construction of the Three Gorges Reservoir (TGR has seriously affected the fish assemblage in the impounded reaches. However, fish assemblage changes in the riverine zone remain poorly documented. In order to explore how upstream fish assemblage has responded to the successive impoundments of the TGR, fish investigations were conducted biannually in Hejiang, a protected reach of the upper Yangtze River, during the period from 1997 to 2011. Multivariate analysis revealed significant temporal differences in fish assemblage following the impoundments of the TGR. Prior to the impoundments, the fish assemblage appeared to be very diversified and very even. Immediately after the first and the second impoundment, the lotic species, such as Coreius guichenoti, Rhinogobio ventralis, Rhinogobio cylindricus and Coreius heterodon, became evidently dominant, due to their upstream migrations from the reservoir. However, two years after the third impoundment, the lotic species decreased dramatically, while lentic Hypophthalmichthys molitrix and Pelteobagrus vachelli became the new dominant species. Based on this and other studies, we can see the habitats of the riverine fish in the upper Yangtze River have been shrunk seriously because of the impoundments of the TGR. The cascade hydropower development in the lower Jinsha River will pose an accumulative effect on the aquatic environment in the mainstream of the upper Yangtze River. Free-flowing tributaries, such as the Chishui River, will play more important roles in fish conservation.

  12. Seismic performance assessment of latyan concrete buttress dam ...

    African Journals Online (AJOL)

    In order to design earthquake resistant dams and evaluate the safety of existing dams that will be exposed to future earthquakes, it is essential to have accurate and reliable analysis procedures to predict the stresses and deformations in dams subjected to earthquake ground motion. For a damwater- foundation system, the ...

  13. Characterisation of gold tailings dams of the Witwatersrand Basin ...

    African Journals Online (AJOL)

    The oxygen diffusion data reveal that the flow of oxygen in the Witwatersrand tailings dams is controlled by secondary porosity (i.e. cracks caused by roots on the dam surface). The age of the dam does not have a significant bearing on the extent to which the oxidised zone development and subsequently AMD can progress.

  14. Factors influencing hysteresis characteristics of concrete dam deformation

    Directory of Open Access Journals (Sweden)

    Jia-he Zhang

    2017-04-01

    Full Text Available Thermal deformation of a concrete dam changes periodically, and its variation lags behind the air temperature variation. The lag, known as the hysteresis time, is generally attributed to the low velocity of heat conduction in concrete, but this explanation is not entirely sufficient. In this paper, analytical solutions of displacement hysteresis time for a cantilever beam and an arch ring are derived. The influence of different factors on the displacement hysteresis time was examined. A finite element model was used to verify the reliability of the theoretical analytical solutions. The following conclusions are reached: (1 the hysteresis time of the mean temperature is longer than that of the linearly distributed temperature difference; (2 the dam type has a large impact on the displacement hysteresis time, and the hysteresis time of the horizontal displacement of an arch dam is longer than that of a gravity dam; (3 the reservoir water temperature variation lags behind of the air temperature variation, which intensifies the differences in the horizontal displacement hysteresis time between the gravity dam and the arch dam; (4 with a decrease in elevation, the horizontal displacement hysteresis time of a gravity dam tends to increase, whereas the horizontal displacement hysteresis time of an arch dam is likely to increase initially, and then decrease; and (5 along the width of the dam, the horizontal displacement hysteresis time of a gravity dam decreases as a whole, while the horizontal displacement hysteresis time of an arch dam is shorter near the center and longer near dam surfaces.

  15. SEISMIC RESPONSE OF DAM WITH SOIL-STRUCTURE INTERACTION.

    Science.gov (United States)

    Bycroft, G.N.; Mork, P.N.

    1987-01-01

    An analytical solution to the response of a long trapezoidal-section dam on a foundation consisting of an elastic half-space and subjected to simulated earthquake motion is developed. An optimum seismic design is achieved when the cross section of the dam is triangular. The effect of soil structure interaction is to lower the strain occurring in the dam.

  16. Liberated rivers: lessons from 40 years of dam removal

    Science.gov (United States)

    Marie Oliver; Gordon Grant

    2017-01-01

    In recent decades, dam removal has emerged as a viable national and international strategy for river restoration. According to American Rivers, a river conservation organization, more than 1,100 dams have been removed in the United States in the past 40 years, and more than half of these were demolished in the past decade. This trend is likely to continue as dams age,...

  17. Tenaga Nasional Berhad dam safety and surveillance program

    International Nuclear Information System (INIS)

    Jansen Luis; Zulkhairi Abd Talib

    2006-01-01

    This paper discusses the current practice of dam surveillance, which includes dam monitoring which is a process of visual inspections, measuring, processing, compiling and analyzing dam instrumentation data to determine the performance of a dam. The prime objective of the dam surveillance system is to ensure that any occurrence and development of safety deficiencies and problems are quickly detected, identified, analyzed and the required remedial actions are determined and consequently carried out in due time. In brief, the section is responsible to ensure that the dam monitoring and surveillance works are implemented as per scheduled and in accordance with the requirement and guidelines prepared by the dam designers and in accordance with international commission on large dams, ICOLD. The paper also illustrates and recommends an alternative approach for dam surveillance program using risk management approach, which is currently being actively adopted by some countries like USA, Canada, Australia and etc, towards improving the dam safety management and the decision making process. The approach provides a wider area of opportunity, improvements and benefits particular in the evaluation and modifications to the dam performance and safety. The process provides an effective and efficient tool for the decision makers and engineers through a comprehensive evaluation and a good understanding of the hazards, risks and consequences in relation to dam safety investigations. (Author)

  18. How to manage the cumulative flood safety of catchment dams ...

    African Journals Online (AJOL)

    Dam safety is a significant issue being taken seriously worldwide. However, in Australia, although much attention is being devoted to the medium- to large-scale dams, minimal attention is being paid to the serious potential problems associated with smaller dams, particularly the potential cumulative safety threats they pose ...

  19. 25 CFR 173.16 - Reserved area, Coolidge Dam.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Reserved area, Coolidge Dam. 173.16 Section 173.16... area, Coolidge Dam. No permit for any commercial business or other activity (except boating concessions...-fourths of a mile from the center of the Coolidge Dam, Arizona. ...

  20. 43 CFR 418.18 - Diversions at Derby Dam.

    Science.gov (United States)

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Diversions at Derby Dam. 418.18 Section... Operations and Management § 418.18 Diversions at Derby Dam. (a) Diversions of Truckee River water at Derby Dam must be managed to maintain minimum terminal flow to Lahontan Reservoir or the Carson River except...

  1. Waterbirds at the Theewaterskloof Dam, Western Cape, South Africa ...

    African Journals Online (AJOL)

    With a perimeter of 82km, the Theewaterskloof Dam is the largest dam in the Western Cape. This paper, based on midsummer and mid-winter surveys between 1993 and 2005, assesses the importance of the dam for waterbirds. The median numbers of waterbirds in summer and winter were 3 086 and 1 321, respectively.

  2. Earthquake induced liquefaction analysis of Tendaho earth-fill dam ...

    African Journals Online (AJOL)

    fill dam, which is part of Tendaho Dam and Irrigation Project; the largest irrigation project in Ethiopia to date. The dam is located in the most seismic part of Ethiopia and was originally designed to be founded on potentially liquefiable alluvium ...

  3. Major dams of the United States, Geographic NAD83, USGS (2006) [dams00x020_USGS_2006

    Data.gov (United States)

    Louisiana Geographic Information Center — This map layer portrays major dams of the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or...

  4. Effect of dam weight and pregnancy nutrition on average lactation performance of ewe offspring over 5 years.

    Science.gov (United States)

    Paten, A M; Pain, S J; Peterson, S W; Lopez-Villalobos, N; Kenyon, P R; Blair, H T

    2017-06-01

    The foetal mammary gland is sensitive to maternal weight and nutrition during gestation, which could affect offspring milk production. It has previously been shown that ewes born to dams offered maintenance nutrition during pregnancy (day 21 to 140 of gestation) produced greater milk, lactose and CP yields in their first lactation when compared with ewes born to dams offered ad libitum nutrition. In addition, ewes born to heavier dams produced greater milk and lactose yields when compared with ewes born to lighter dams. The objective of this study was to analyse and compare the 5-year lactation performance of the previously mentioned ewes, born to heavy or light dams that were offered maintenance or ad libitum pregnancy nutrition. Ewes were milked once per week, for the first 6 weeks of their lactation, for 5 years. Using milk yield and composition data, accumulated yields were calculated over a 42-day period for each year for milk, milk fat, CP, true protein, casein and lactose using a Legendre orthogonal polynomial model. Over the 5-year period, ewes born to heavy dams produced greater average milk (P=0.04), lactose (P=0.01) and CP (P=0.04) yields than offspring born to light dams. In contrast, over the 5-year period dam nutrition during pregnancy did not affect average (P>0.05) offspring milk yields or composition, but did increase milk and lactose accumulated yield (P=0.03 and 0.01, respectively) in the first lactation. These results indicate that maternal gestational nutrition appears to only affect the first lactational performance of ewe offspring. Neither dam nutrition nor size affected grand-offspring live weight gain to, or live weight at weaning (P>0.05). Combined these data indicate that under the conditions of the present study, manipulating dam weight or nutrition in pregnancy can have some effects of offspring lactational performance, however, these effects are not large enough to alter grand-offspring growth to weaning. Therefore, such manipulations

  5. DAM-LAKEFRONT PLAZA: Revitalization of an Agriculture Reservoir Dam in Kashar-Tirana/Albania

    Directory of Open Access Journals (Sweden)

    Valbona Koçi

    2014-12-01

    Full Text Available The Dam-Lakefront Plaza in Kashar-Tirana/Albania is a research project that proposes not only the re-consideration and reinforcement of the artificial Reservoirs Dams built during Socialism in Albania, but envisions the maintenance of dams and revitalization of the lakeside area promoting the public-private collaboration. In addition, it envisions the generation of qualitative and lively public spaces in sub-urban areas as well. Admitting the artificial lakes as specific nodes of man-made infrastructure in the landscape, and consequently the dams (together with the drainage channels as important hydrotechnic elements of the flood protection infrastructure, this research intends to elaborate on one type of landscape infrastructure - the vertical screens, offering a mediation between the natural and built landscape.

  6. Dam water quality study. Report to Congress

    International Nuclear Information System (INIS)

    1989-05-01

    The objective of the report is to identify water quality effects attributable to the impoundment of water by dams as required by Section 524 of the Water Quality Act of 1987. The document presents a study of water quality effects associated with impoundments in the U.S.A

  7. Geologic Conceptual Model of Mosul Dam

    Science.gov (United States)

    2007-09-01

    geomechanical characteristics or geotechnical properties. As an example, if the locations and depths of zones of high grout-take are known, these zones can...Dam safety Foundation grout Geologic model GIS Gypsum Hydrogeology Iraq geology Karst 3-D modeling 16. SECURITY CLASSIFICATION

  8. living in Kapulukaya Dam Lake (Kirikkale, Turkey)

    African Journals Online (AJOL)

    GREGORY

    2010-08-23

    Aug 23, 2010 ... Key words: Esox lucius, Northern pike, breeding, Kapulukaya Dam Lake, Turkey. INTRODUCTION. Northern pike (Esox lucius) from Esocidae family is a commonly hunted fish due to its tasty meat. It generally lives in lakes but it is frequently seen in rivers and stream. Although it is known as a freshwater ...

  9. Will We. . .? Thai Dam Resource Book.

    Science.gov (United States)

    Murphy, Richard, Ed.; And Others

    This resource book is intended as an aid to persons working with Thai Dam refugees. To help the language teacher, some differences between Lao and English are discussed, specifically tonal inflections, positioning, declension of pronouns, conjugation of verbs, interrogatives, classifiers and predicate adjectives. An outline of cultural differences…

  10. Dam tot damloop : economische en maatschappelijke waarde

    NARCIS (Netherlands)

    de Nooij, Michiel; Horsselenberg, Peter

    2014-01-01

    Ruim 36.757 lopers (op de hoofdafstand!) en 115.000 bezoekers langs het parcours van het centrum van Amsterdam naar het centrum van Zaanstad, maakt de Dam tot damloop een groot evenement (het grootste hardloop evenement van Nederland) met een flinke impact op de (lokale) samenleving en economie. Dit

  11. Rehabilitation of the John Hart dam

    International Nuclear Information System (INIS)

    Cathcart, D.S.

    1989-01-01

    The largest and most recent rehabilitation project undertaken by British Columbia Hydro involves the John Hart Dam on the Campbell River on Vancouver Island. This area has the potential for large earthquake events, with an earthquake with a 7.3 rating on the Richter scale occurring as construction was underway in 1946. Investigation showed that the dam and foundations were liable to liquify under low seismic loading, and the area downstream is now well developed and inhabited. Taking the 120 MW power plant out of operation would jeopardize the power supply to northern Vancouver Island, so it was decided to take immediate steps to stabilize the most sensitive areas and then to rehabilitate the dam to an acceptable level of earthquake resistance while maintaining the reservoir at normal level with the power plant in operation. Using innovative engineering techniques and careful monitoring, the project, which included foundation improvement under existing structures and virtual rebuilding of the earthdam, was completed without lowering the reservoir. In spite of the very restrictive environmental constraints, the work was done without unacceptable environmental impact or adverse public reaction. Costs were $24 million, slightly under budget. All instrumentation has been monitored on a regular basis and the performance of the dam is satisfactory. 7 figs

  12. Physicochemical characteristics of undrainable water dams utilized ...

    African Journals Online (AJOL)

    pH, electro-conductivity and total dissoved solutes (TDS) were measured in-situ from three reservoirs (Gathathini, Lusoi and Kianda dams) differing in their habitat characteristics. Water samples were collected for determination of the ionic concentartions of the reservoirs. Water quality status differed markedly between sites, ...

  13. Can Dams and Reservoirs Cause Earthquakes?

    Indian Academy of Sciences (India)

    FAULT. Triggering of Earthquakes. Ramesh Chander. No! Not on their own. But, stresses and pore pressure due to natural causes may already have accumulated in crustal rocks at some dam sites to near critical levels for fresh faulting or renewed slip on nearby pre-existing faults. The stresses and pore pressure induced ...

  14. Reservoir-induced landslides and risk control in Three Gorges Project on Yangtze River, China

    Directory of Open Access Journals (Sweden)

    Yueping Yin

    2016-10-01

    Full Text Available The Three Gorges region in China was basically a geohazard-prone area prior to construction of the Three Gorges Reservoir (TGR. After construction of the TGR, the water level was raised from 70 m to 175 m above sea level (ASL, and annual reservoir regulation has caused a 30-m water level difference after impoundment of the TGR since September 2008. This paper first presents the spatiotemporal distribution of landslides in six periods of 175 m ASL trial impoundments from 2008 to 2014. The results show that the number of landslides sharply decreased from 273 at the initial stage to less than ten at the second stage of impoundment. Based on this, the reservoir-induced landslides in the TGR region can be roughly classified into five failure patterns, i.e. accumulation landslide, dip-slope landslide, reversed bedding landslide, rockfall, and karst breccia landslide. The accumulation landslides and dip-slope landslides account for more than 90%. Taking the Shuping accumulation landslide (a sliding mass volume of 20.7 × 106 m3 in Zigui County and the Outang dip-slope landslide (a sliding mass volume of about 90 × 106 m3 in Fengjie County as two typical cases, the mechanisms of reactivation of the two landslides are analyzed. The monitoring data and factor of safety (FOS calculation show that the accumulation landslide is dominated by water level variation in the reservoir as most part of the mass body is under 175 m ASL, and the dip-slope landslide is controlled by the coupling effect of reservoir water level variation and precipitation as an extensive recharge area of rainfall from the rear and the front mass is below 175 m ASL. The characteristics of landslide-induced impulsive wave hazards after and before reservoir impoundment are studied, and the probability of occurrence of a landslide-induced impulsive wave hazard has increased in the reservoir region. Simulation results of the Ganjingzi landslide in Wushan County indicate the

  15. Monitoring the structural integrity of large concrete dams: the case of Cabril dam, Portugal

    OpenAIRE

    Oliveira, S.; Ferreira, I.; Berberan, A. L.; Mendes, P.; Boavida, J.; Baptista, B.

    2010-01-01

    The safety control of large dams under static and dynamic loads, involving observation data and numerical modeling, is now one of the challenges of structural engineering. The complexity of the dam-reservoir-foundation geometry, the presence of different types of discontinuities, the water-structure interaction, the influence of thermal and water level variations, the development of deterioration processes over time and the occurrence of exceptional events such as major floods or earthquakes,...

  16. National Dam Safety Program. Raintree Lake Dam (MO 20388), Missouri - Kansas City Basin, Cass County, Missouri. Phase I Inspection Report.

    Science.gov (United States)

    1979-05-01

    report was pepared under the National Program of Inspection of Non-Federal Dams. This report assesses the general condition of the dam withprespect...raise any serious questions relating to the safety of the dam or iden- tify any serious dangers that would require a Phase II investigation. e. Seismic

  17. Experimental research on the dam-break mechanisms of the Jiadanwan landslide dam triggered by the Wenchuan earthquake in China.

    Science.gov (United States)

    Xu, Fu-gang; Yang, Xing-guo; Zhou, Jia-wen; Hao, Ming-hui

    2013-01-01

    Dam breaks of landslide dams are always accompanied by large numbers of casualties, a large loss of property, and negative influences on the downstream ecology and environment. This study uses the Jiadanwan landslide dam, created by the Wenchuan earthquake, as a case study example. Several laboratory experiments are carried out to analyse the dam-break mechanism of the landslide dam. The different factors that impact the dam-break process include upstream flow, the boulder effect, dam size, and channel discharge. The development of the discharge channel and the failure of the landslide dam are monitored by digital video and still cameras. Experimental results show that the upstream inflow and the dam size are the main factors that impact the dam-break process. An excavated discharge channel, especially a trapezoidal discharge channel, has a positive effect on reducing peak flow. The depth of the discharge channel also has a significant impact on the dam-break process. The experimental results are significant for landslide dam management and flood disaster prevention and mitigation.

  18. 78 FR 60271 - Hollow Dam Power Company; Ampersand Hollow Dam Hydro, LLC; Notice of Application for Transfer of...

    Science.gov (United States)

    2013-10-01

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 6972-032] Hollow Dam Power Company; Ampersand Hollow Dam Hydro, LLC; Notice of Application for Transfer of License, and Soliciting Comments and Motions To Intervene On September 10, 2013, Hollow Dam Power Company (transferor) and...

  19. National Dam Safety Program. Lake Frederick Dam (Inventory Number NY 769), Orange County, New York. Phase 1 Inspection Report

    Science.gov (United States)

    1980-03-11

    COMPUTATIONSF F . OTHER DATA LAL M- PHASE I REPORT - NATIONAL DAM SAFETY PROGRAMA _ Name of Dam: LAKE FREDERICK DAM (I.D. NO. 769) V - State Located: NEW YORK... abc -ut 230 feet to the right of the spiliway. The conduit runs = underground and outfalls about 75 feet downstream frm the toe of the dar; the

  20. Experimental Research on the Dam-Break Mechanisms of the Jiadanwan Landslide Dam Triggered by the Wenchuan Earthquake in China

    Science.gov (United States)

    Xu, Fu-gang; Yang, Xing-guo; Hao, Ming-hui

    2013-01-01

    Dam breaks of landslide dams are always accompanied by large numbers of casualties, a large loss of property, and negative influences on the downstream ecology and environment. This study uses the Jiadanwan landslide dam, created by the Wenchuan earthquake, as a case study example. Several laboratory experiments are carried out to analyse the dam-break mechanism of the landslide dam. The different factors that impact the dam-break process include upstream flow, the boulder effect, dam size, and channel discharge. The development of the discharge channel and the failure of the landslide dam are monitored by digital video and still cameras. Experimental results show that the upstream inflow and the dam size are the main factors that impact the dam-break process. An excavated discharge channel, especially a trapezoidal discharge channel, has a positive effect on reducing peak flow. The depth of the discharge channel also has a significant impact on the dam-break process. The experimental results are significant for landslide dam management and flood disaster prevention and mitigation. PMID:23844387

  1. PREDICTION OF TOTAL DISSOLVED GAS EXCHANGE AT HYDROPOWER DAMS

    Energy Technology Data Exchange (ETDEWEB)

    Hadjerioua, Boualem [ORNL; Pasha, MD Fayzul K [ORNL; Stewart, Kevin M [ORNL; Bender, Merlynn [Bureau of Reclamation; Schneider, Michael L. [U.S. Army Corps of Engineers

    2012-07-01

    Total dissolved gas (TDG) supersaturation in waters released at hydropower dams can cause gas bubble trauma in fisheries resulting in physical injuries and eyeball protrusion that can lead to mortality. Elevated TDG pressures in hydropower releases are generally caused by the entrainment of air in spillway releases and the subsequent exchange of atmospheric gasses into solution during passage through the stilling basin. The network of dams throughout the Columbia River Basin (CRB) are managed for irrigation, hydropower production, flood control, navigation, and fish passage that frequently result in both voluntary and involuntary spillway releases. These dam operations are constrained by state and federal water quality standards for TDG saturation which balance the benefits of spillway operations designed for Endangered Species Act (ESA)-listed fisheries versus the degradation to water quality as defined by TDG saturation. In the 1970s, the United States Environmental Protection Agency (USEPA), under the federal Clean Water Act (Section 303(d)), established a criterion not to exceed the TDG saturation level of 110% in order to protect freshwater and marine aquatic life. The states of Washington and Oregon have adopted special water quality standards for TDG saturation in the tailrace and forebays of hydropower facilities on the Columbia and Snake Rivers where spillway operations support fish passage objectives. The physical processes that affect TDG exchange at hydropower facilities have been studied throughout the CRB in site-specific studies and routine water quality monitoring programs. These data have been used to quantify the relationship between project operations, structural properties, and TDG exchange. These data have also been used to develop predictive models of TDG exchange to support real-time TDG management decisions. These empirically based predictive models have been developed for specific projects and account for both the fate of spillway and

  2. Synthesis of common management concerns associated with dam removal

    Science.gov (United States)

    Tullos, Desiree D.; Collins, Mathias J.; Bellmore, J. Ryan; Bountry, Jennifer A.; Connolly, Patrick J.; Shafroth, Patrick B.; Wilcox, Andrew C.

    2016-01-01

    Managers make decisions regarding if and how to remove dams in spite of uncertainty surrounding physical and ecological responses, and stakeholders often raise concerns about certain negative effects, regardless of whether or not these concerns are warranted at a particular site. We used a dam-removal science database supplemented with other information sources to explore seven frequently-raised concerns, herein Common Management Concerns (CMCs). We investigate the occurrence of these concerns and the contributing biophysical controls. The CMCs addressed are: degree and rate of reservoir sediment erosion, excessive channel incision upstream of reservoirs, downstream sediment aggradation, elevated downstream turbidity, drawdown impacts on local water infrastructure, colonization of reservoir sediments by non-native plants, and expansion of invasive fish. Biophysical controls emerged for some of the concerns, providing managers with information to assess whether a given concern is likely to occur at a site. To fully assess CMC risk, managers should concurrently evaluate site conditions and identify the ecosystem or human uses that will be negatively affected if the biophysical phenomenon producing the CMC occurs. We show how many CMCs have one or more controls in common, facilitating the identification of multiple risks at a site, and demonstrate why CMC risks should be considered in the context of other factors like natural watershed variability and disturbance history.

  3. Phosphate accumulation in farm dam sediments

    International Nuclear Information System (INIS)

    Ruan, H.D.; Gilkes, R.J.

    1998-01-01

    Full text: Large amounts of phosphate are applied to agricultural regions in Australia each year. Phosphate is incorporated into organic materials, sorbed onto the surface of clay minerals, carbonates, iron oxides/hydroxides and other colloids or dissolved in soil solution. Phosphate in soil solution may leach into dam, or absorbed and particulate phosphate may be washed into dams during soil erosion and eventually accumulate in sediments. Variable and sometimes high concentrations of phosphate in water and sediments occur in farm dams in the York area of Western Australia. Phosphate accumulation in farm dam sediments (O to about 2 cm) was investigated using chemical analysis and X-ray diffraction. Concentrations of phosphorus up to 5 ppm in water and 1100 ppm in sediment were observed. The results of this study indicate that the amounts of total, organic and inorganic phosphate in sediment are approximately equal and are linearly related the dissolved phosphate concentration in dam water. High concentrations of nitrogen also exit in sediments and are closely related to the phosphate content of sediment presumably reflecting the high content of organic matter in sediments, ranging from 3 to 7% C. The concentration of phosphate in sediments is closely related to the organic matter concentration measured by LECO CHN analyser. X-ray diffraction patterns show that clay minerals in sediments consist of minor to large amounts of smectite and kaolinite, minor to moderate amounts of illite, mica and feldspars. Minor amounts of calcite and iron oxides were present only in a few samples. Clay minerals and iron oxides have moderate to high phosphate sorption capacities because the reactive sites on crystal surfaces and their high surface area. Thus colloidal minerals, organic materials and organo-mineral complexes may provide reactive sites for phosphate sorption

  4. Measuring Inclinations in Cabril Dam with an Optoelectronic Sensor

    OpenAIRE

    Henriques, M. J.; Lima, J. N.; Oliveira, S.

    2012-01-01

    A high precision inclinometer was placed at the top gallery of Cabril dam, the highest dam in Portugal (132 m). Cabril dam has been presenting, since the first filling of the reservoir (1953), some horizontal cracks in the central upper zone. The dual axis inclinometer, with a recording measuring rate of 1 Hz, was installed for two days; during the same period a digital thermometer, for recording air temperatures, was placed next to the downstream face of the dam. The dam remained under norma...

  5. Dam safety status in New South Wales (NSW), Australia

    International Nuclear Information System (INIS)

    Himsley, N.

    1996-01-01

    The design, operation and safety of some 250 large water supply/irrigation/hydroelectric/mine tailings dams in New South Wales (NSW) rest upon legislation enacted by the NSW Government in 1978. This paper provides a description of the details surrounding the evolution of the Act, problems that the Act was enacted to resolve, and practices and requirements for prescribed dam owners relating to dam design, construction, operation and maintenance, upgrading, decommissioning, and activities around dams. Future concerns, relating to pressures for economic rationalization, environmental concerns, public participation in decision making, dam ageing, and advancement of technology also have been addressed. 3 refs., 1 tab

  6. Proceeding of the public safety around dams conference

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    The Canadian Dam Association hosted the Public Safety Around Dams workshop in which presentations were given in the morning to describe the different measures and methods implemented by the Ontario Ministry of Natural Resources, Ontario Power Generation and others to improve safety around dams. In the afternoon, the participants toured the Auburn and Lakefield dams and facilities to view the infrastructures and equipment. A roundtable discussion concluded the day. Following this workshop, a Public Safety Around Dams group was created on the social network site, LinkedIn. This conference featured 6 presentations, 3 of which have been catalogued separately for inclusion in this database.

  7. The influence of controlled floods on fine sediment storage in debris fan-affected canyons of the Colorado River basin

    Science.gov (United States)

    Mueller, Erich R.; Grams, Paul E.; Schmidt, John C.; Hazel, Joseph E.; Alexander, Jason S.; Kaplinski, Matt

    2014-01-01

    Prior to the construction of large dams on the Green and Colorado Rivers, annual floods aggraded sandbars in lateral flow-recirculation eddies with fine sediment scoured from the bed and delivered from upstream. Flows greater than normal dam operations may be used to mimic this process in an attempt to increase time-averaged sandbar size. These controlled floods may rebuild sandbars, but sediment deficit conditions downstream from the dams restrict the frequency that controlled floods produce beneficial results. Here, we integrate complimentary, long-term monitoring data sets from the Colorado River in Marble and Grand Canyons downstream from Glen Canyon dam and the Green River in the Canyon of Lodore downstream from Flaming Gorge dam. Since the mid-1990s, several controlled floods have occurred in these canyon rivers. These controlled floods scour fine sediment from the bed and build sandbars in eddies, thus increasing channel relief. These changes are short-lived, however, as interflood dam operations erode sandbars within several months to years. Controlled flood response and interflood changes in bed elevation are more variable in Marble Canyon and Grand Canyon, likely reflecting more variable fine sediment supply and stronger transience in channel bed sediment storage. Despite these differences, neither system shows a trend in fine-sediment storage during the period in which controlled floods were monitored. These results demonstrate that controlled floods build eddy sandbars and increase channel relief for short interflood periods, and this response may be typical in other dam-influenced canyon rivers. The degree to which these features persist depends on the frequency of controlled floods, but careful consideration of sediment supply is necessary to avoid increasing the long-term sediment deficit.

  8. Coastal habitat and biological community response to dam removal on the Elwha River

    Science.gov (United States)

    Foley, Melissa M.; Warrick, Jonathan A.; Ritchie, Andrew C.; Stevens, Andrew; Shafroth, Patrick B.; Duda, Jeff; Beirne, Matthew M.; Paradis, Rebecca; Gelfenbaum, Guy R.; McCoy, Randall; Cubley, Erin S.

    2017-01-01

    Habitat diversity and heterogeneity play a fundamental role in structuring ecological communities. Dam emplacement and removal can fundamentally alter habitat characteristics, which in turn can affect associated biological communities. Beginning in the early 1900s, the Elwha and Glines Canyon dams in Washington, USA, withheld an estimated 30 million tonnes of sediment from river, coastal, and nearshore habitats. During the staged removal of these dams—the largest dam removal project in history—over 14 million tonnes of sediment were released from the former reservoirs. Our interdisciplinary study in coastal habitats—the first of its kind—shows how the physical changes to the river delta and estuary habitats during dam removal were linked to responses in biological communities. Sediment released during dam removal resulted in over a meter of sedimentation in the estuary and over 400 m of expansion of the river mouth delta landform. These changes increased the amount of supratidal and intertidal habitat, but also reduced the influx of seawater into the pre-removal estuary complex. The effects of these geomorphic and hydrologic changes cascaded to biological systems, reducing the abundance of macroinvertebrates and fish in the estuary and shifting community composition from brackish to freshwater-dominated species. Vegetation did not significantly change on the delta, but pioneer vegetation increased during dam removal, coinciding with the addition of newly available habitat. Understanding how coastal habitats respond to large-scale human stressors—and in some cases the removal of those stressors—is increasingly important as human uses and restoration activities increase in these habitats.

  9. The fluvial sediment budget of a dammed river (upper Muga, southern Pyrenees)

    Science.gov (United States)

    Piqué, G.; Batalla, R. J.; López, R.; Sabater, S.

    2017-09-01

    Many rivers in the Mediterranean region are regulated for urban and agricultural purposes. Reservoir presence and operation results in flow alteration and sediment discontinuity, altering the longitudinal structure of the fluvial system. This study presents a 3-year sediment budget of a highly dammed Mediterranean river (the Muga, southern Pyrenees), which has experienced flow regulation since the 1969 owing to a 61-hm3 reservoir. Flow discharge and suspended sediment concentration were monitored immediately upstream and downstream from the reservoir, whereas bedload transport was estimated by means of bedload formulae and estimated from regional data. Results show how the dam modifies river flow, reducing the magnitude of floods and shortening its duration. At the same time, duration of low flows increases. The downstream flow regime follows reservoir releases that are mostly driven by the irrigation needs in the lowlands. Likewise, suspended sediment and bedload transport are shown to be notably affected by the dam. Sediment transport upstream was mainly associated with floods and was therefore concentrated in short periods of time (i.e., > 90% of the sediment load occurred in transported more constantly (i.e., 90% of the load was carried during 50% of the time). Total sediment load upstream from the dam equalled 23,074 t, while downstream it was transport downstream. More than 95% of the sediments transported from the upstream basins were trapped in the reservoir, a fact that explains the sediment deficit and the river bed armouring observed downstream. Overall, the dam disrupted the natural water and sediment fluxes, generating a highly modified environment downstream. Below the dam, the whole ecosystem shifted to stable conditions owing to the reduction of water and sediment loads.

  10. Migration delays caused by anthropogenic barriers: modeling dams, temperature, and success on migrating salmon smolts

    Science.gov (United States)

    Marschall, Elizabeth A.; Mather, Martha E.; Parrish, Donna; Allison, Gary W.; McMenemy, James R.

    2011-01-01

    Disruption to migration is a growing problem for conservation and restoration of animal populations. Anthropogenic barriers along migration paths can delay or prolong migrations, which may result in a mismatch with migration-timing adaptations. To understand the interaction of dams (as barriers along a migration path), seasonally changing environmental conditions, timing of Atlantic salmon (Salmo salar) downstream migration, and ultimate migration success, we used 10 years of river temperature and discharge data as a template upon which we simulated downstream movement of salmon. Atlantic salmon is a cool-water species whose downstream migrating smolts must complete migration before river temperatures become too warm. We found that dams had a local effect on survival as well as a survival effect that was spatially and temporally removed from the encounter with the dam. While smolts are delayed by dams, temperatures downstream can reach lethal or near-lethal temperatures; as a result, the match between completion of migration and the window of appropriate migration conditions can be disrupted. The strength of this spatially and temporally removed effect is at least comparable to the local effects of dams in determining smolt migration success in the presence of dams. We also considered smolts from different tributaries, varying in distance from the river mouth, to assess the potential importance of locally adapted migration timing on the effect of barriers. Migration-initiation temperature affected modeled smolt survival differentially across tributaries, with the success of smolts from upstream tributaries being much more variable across years than that of smolts with a shorter distance to travel. As a whole, these results point to the importance of broadening our spatial and temporal view when managing migrating populations. We must consider not only how many individuals never make it across migration barriers, but also the spatially and temporally removed

  11. Migration delays caused by anthropogenic barriers: Modeling dams, temperature, and success of migrating salmon smolts

    Science.gov (United States)

    Marschall, E.A.; Mather, M. E.; Parrish, D.L.; Allison, G.W.; McMenemy, J.R.

    2011-01-01

    Disruption to migration is a growing problem for conservation and restoration of animal populations. Anthropogenic barriers along migration paths can delay or prolong migrations, which may result in a mismatch with migration-timing adaptations. To understand the interaction of dams (as barriers along a migration path), seasonally changing environmental conditions, timing of Atlantic salmon (Salmo salar) downstream migration, and ultimate migration success, we used 10 years of river temperature and discharge data as a template upon which we simulated downstream movement of salmon. Atlantic salmon is a cool-water species whose downstream migrating smolts must complete migration before river temperatures become too warm. We found that dams had a local effect on survival as well as a survival effect that was spatially and temporally removed from the encounter with the dam. While smolts are delayed by dams, temperatures downstream can reach lethal or near-lethal temperatures;as a result, the match between completion of migration and the window of appropriate migration conditions can be disrupted. The strength of this spatially and temporally removed effect is at least comparable to the local effects of dams in determining smolt migration success in the presence of dams. We also considered smolts from different tributaries, varying in distance from the river mouth, to assess the potential importance of locally adapted migration timing on the effect of barriers. Migration-initiation temperature affected modeled smolt survival differentially across tributaries, with the success of smolts from upstream tributaries being much more variable across years than that of smolts with a shorter distance to travel. As a whole, these results point to the importance of broadening our spatial and temporal view when managing migrating populations. We must consider not only how many individuals never make it across migration barriers, but also the spatially and temporally removed

  12. Use of Sentinel-1 SAR data to monitor Mosul dam vulnerability

    Science.gov (United States)

    Riccardi, Paolo; Tessari, Giulia; Lecci, Daniele; Floris, Mario; Pasquali, Paolo

    2017-04-01

    . It was completed in 1984 and started generating power on 1986. Since then, frequent consolidation works have been carried out pumping cement mixtures into the soil foundation to keep it stable and prevent it from sinking and then breaking apart. To overcome the impossibility of directly monitoring the structure, analysis of recent deformation affecting the Mosul dam is achieved considering C-band Sentinel-1 SAR data, acquired from the end of 2014 to the present. These 20-m ground resolution data can provide a millimetric precision on displacements. Furthermore, ESA archive available SAR data (ERS and Envisat) are considered to reconstruct the temporal evolution of the deformations. In this work, different stacks of data are processed applying SBAS and PS A-DInSAR techniques; deformation fields obtained from SAR data are evaluated to assess the temporal evolution of the strains affecting the structure. Obtained results represent the preliminary stage of a multidisciplinary project, finalised to assess possible damages affecting a dam through remote sensing and civil engineering surveys.

  13. Postpartum behavioral profiles in Wistar rats following maternal separation - altered exploration and risk-assessment behavior in MS15 dams

    Directory of Open Access Journals (Sweden)

    Loudin Daoura

    2010-06-01

    Full Text Available The rodent maternal separation (MS model is frequently used to investigate the impact of early environmental factors on adult neurobiology and behavior. The majority of MS studies assess effects in the offspring and few address the consequences of repeated pup removal in the dam. Such studies are of interest since alterations detected in offspring subjected to MS may, at least in part, be mediated by variations in maternal behavior and the amount of maternal care provided by the dam. The aim of this study was to investigate how daily short (15 min; MS15 and prolonged (360 min; MS360 periods of MS affects the dam by examining postpartum behavioral profiles using the multivariate concentric square field™ (MCSF test. The dams were tested on postpartum days 24-25, i.e. just after the end of the separation period and weaning. The results reveal a lower exploratory drive and lower risk-assessment behavior in MS15 dams relative to MS360 or animal facility reared dams. The present results contrast some of the previously reported findings and provide new information about early post-weaning behavioral characteristics in a multivariate setting. Plausible explanations for the results are provided including a discussion how the present results fit into the maternal mediation hypothesis.

  14. Assessment of Productivity Status Using Carlson’s TSI and Fish Diversity of Goronyo Dam, Sokoto State, Nigeria

    Directory of Open Access Journals (Sweden)

    Hassan Muhammad Maishanu

    2018-01-01

    Full Text Available Goronyo Dam is the largest lentic waterbody in Sokoto, it was constructed to serve as flood control and used for irrigation activities. The study was conducted to evaluate productivity status and fish diversity of Goronyo Dam in 2016. Water samples were collected monthly from the Dam at two sampling sites (Upstream and Downstream. Water samples were collected using sterilized sampling bottles and analyzed in the Laboratory for physicochemical variables and the diversity of fish was evaluated through the use of a structured questionnaire. Depth and transparency were the only variables that did not show any statistically significant difference between the months. Productivity status of the dam was evaluated using Carlson’s Trophic State Index. The downstream has high TSI value of 16.54 compared to upstream with 13.00. A diversity of fishes from the shows that 3 species were more abundant in the dam, these were; Mormyrops species, Alestes species and Clupeid species. Factors contributed to the survival of fish species were an abundance of water and plankton in the dam. While factors affecting the distribution of fish species were pollution and predation.

  15. Audit Technical of Kori Rubber Dam in the River of Keyang District of Ponorogo East Java Province

    Science.gov (United States)

    Murnianto, E.; Suprapto, M.; Ikhsan, C.

    2018-03-01

    The development of science and technology for the utilization and protection of rivers has embodied various types of river infrastructure. Without proper maintenance, rapid river sediments undergo physical degradation and function. Problems that occur in Kori Rubber Dam, among others, the damage to the body of the rubber dam that is made of rubber, so that the function of flower deflection is not optimal. This happens because of limited operational and maintenance activities (OM). A technical audit is a process of identifying problems, analyzing, and evaluating ones conducted independently, objectively and professionally on the basis of examination, to assess the truth, accuracy, credibility, and reliability of information about a job. In this case an assessment of the Kori Rubber Dam, which is basically a benchmarking activity. Assessment of rubber dam components includes the physical conditions and functions that affect the weir. This research is expected to know the performance of Kori rubber Dam as a recommendation material in the implementation of OM Rubber Dam activities.

  16. Rehabilitation of an 80 year old Ambursen dam

    International Nuclear Information System (INIS)

    Matich, M.A.J.; Eddy, W.; Tyler, R.J.; Budgell, W.S.

    1999-01-01

    The Abitibi-Price Inc. hydroelectric facility at Bishop's Falls, NF, as built comprised an earth dam, a hollow concrete Ambursen type dam, and intake works at the powerhouse, as the main retaining structures. On January 13, 1983, an unprecedented flood occurred in the region which completely destroyed the earth dam connecting the powerhouse building to the riverbank of the town of Bishop's Falls. Major items of remedial work included a new earth dam and a new gated spillway. The flood did not result in any serious damage to the Ambursen dam, but exposure of the dam to the elements did result in stress which required rehabilitation. The favourable performance of the dam through a long service life in a northern Canadian climatic setting was a significant factor in the decision that the structure could be used without serious modification for at least 50 years. The evaluation of the dam, together with the distress experienced as a result of the flood and the remedial action applied are described as a case history. On the basis of condition and stability analysis, it was considered that repairs consisting of a new lining on the upstream side, grouting of deformation related cracking in the interior of the dam, and shotcrete treatment to the exterior of the downstream side, would give the dam a long service life. These remedial actions were applied, and the performance of the dam to date has met design expectations. 26 refs., 10 figs

  17. Dynamic response of Masjed-Soleyman rockfill dam

    Energy Technology Data Exchange (ETDEWEB)

    Jafarzadeh, F. [Sharif Univ. of Technology, Tehran (Iran, Islamic Republic of)]|[Moshanir Power Eng. Co., Tehran (Iran, Islamic Republic of)

    2004-07-01

    Earth dams are large three-dimensional non-homogeneous structures constructed from inelastic materials. One of the main mechanical characteristics of earth dams is the nonlinear behaviour of soil materials under large strains such as those induced by earthquakes. In order to determine the seismic safety of earth dams, it is necessary to predict the dynamic response of embankment dams to earthquake motions. This study examined the response of the newly constructed, 177 metre high Masjed-Soleyman rock filled dam located in a seismic region of southwest Iran. This paper described the dam site geology and seismicity, dam instrumentation, response to ground motions, and numerical simulations. Some earthquakes which registered more than 5 on the Richter scale occurred near the dam site just after impounding. Accelerometers at the crest and downstream shell recorded the response of the dam body. This paper presented the time and frequency history of the dam response. Dynamic properties such as fundamental frequencies of the dam were estimated using 2 constitutive models called equivalent linear and elastoplastic nested surface models. Good agreement was noted between recorded characteristics and numerical analysis. 5 refs., 1 tab., 10 figs.

  18. Seismic failure modes and seismic safety of Hardfill dam

    Directory of Open Access Journals (Sweden)

    Kun Xiong

    2013-04-01

    Full Text Available Based on microscopic damage theory and the finite element method, and using the Weibull distribution to characterize the random distribution of the mechanical properties of materials, the seismic response of a typical Hardfill dam was analyzed through numerical simulation during the earthquakes with intensities of 8 degrees and even greater. The seismic failure modes and failure mechanism of the dam were explored as well. Numerical results show that the Hardfill dam remains at a low stress level and undamaged or slightly damaged during an earthquake with an intensity of 8 degrees. During overload earthquakes, tensile cracks occur at the dam surfaces and extend to inside the dam body, and the upstream dam body experiences more serious damage than the downstream dam body. Therefore, under the seismic conditions, the failure pattern of the Hardfill dam is the tensile fracture of the upstream regions and the dam toe. Compared with traditional gravity dams, Hardfill dams have better seismic performance and greater seismic safety.

  19. Simulation of Reservoir Sediment Flushing of the Three Gorges Reservoir Using an Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Xueying Li

    2016-05-01

    Full Text Available Reservoir sedimentation and its effect on the environment are the most serious world-wide problems in water resources development and utilization today. As one of the largest water conservancy projects, the Three Gorges Reservoir (TGR has been controversial since its demonstration period, and sedimentation is the major concern. Due to the complex physical mechanisms of water and sediment transport, this study adopts the Error Back Propagation Training Artificial Neural Network (BP-ANN to analyze the relationship between the sediment flushing efficiency of the TGR and its influencing factors. The factors are determined by the analysis on 1D unsteady flow and sediment mathematical model, mainly including reservoir inflow, incoming sediment concentration, reservoir water level, and reservoir release. Considering the distinguishing features of reservoir sediment delivery in different seasons, the monthly average data from 2003, when the TGR was put into operation, to 2011 are used to train, validate, and test the BP-ANN model. The results indicate that, although the sample space is quite limited, the whole sediment delivery process can be schematized by the established BP-ANN model, which can be used to help sediment flushing and thus decrease the reservoir sedimentation.

  20. Landslide displacement analysis based on fractal theory, in Wanzhou District, Three Gorges Reservoir, China

    Directory of Open Access Journals (Sweden)

    Lei Gui

    2016-09-01

    Full Text Available Slow moving landslide is a major disaster in the Three Gorges Reservoir area. It is difficult to compare the deformation among different parts of this kind of landslide through GPS measurements when the displacement of different monitoring points is similar in values. So far, studies have been seldom carried out to find out the information hidden behind those GPS monitoring data to solve this problem. Therefore, in this study, three landslides were chosen to perform landslide displacement analysis based on fractal theory. The major advantage of this study is that it has not only considered the values of the displacement of those GPS monitoring points, but also considered the moving traces of them. This allows to reveal more information from GPS measurements and to obtain a broader understanding of the deformation history on different parts of a unique landslide, especially for slow moving landslides. The results proved that using the fractal dimension as an indicator is reliable to estimate the deformation of each landslide and to represent landslide deformation on both spatial and temporal scales. The results of this study could make sense to those working on landslide hazard and risk assessment and land use planning.

  1. Soil erosion and deposition in the new shorelines of the Three Gorges Reservoir.

    Science.gov (United States)

    Su, Xiaolei; Nilsson, Christer; Pilotto, Francesca; Liu, Songping; Shi, Shaohua; Zeng, Bo

    2017-12-01

    During the last few decades, the construction of storage reservoirs worldwide has led to the formation of many new shorelines in former upland areas. After the formation of such shorelines, a dynamic phase of soil erosion and deposition follows. We explored the factors regulating soil dynamics in the shorelines of the Three Gorges Reservoir (TGR) on the Yangtze River in China. We selected four study sites on the main stem and three on the tributaries in the upstream parts of the reservoir, and evaluated whether the sites close to the backwater tail (the point at which the river meets the reservoir) had more soil deposition than the sites far from the backwater tail. We also tested whether soil erosion differed between the main stem and the tributaries and across shorelines. We found that soil deposition in the new shorelines was higher close to the backwater tail and decreased downstream. Soil erosion was higher in the main stem than in the tributaries and higher at lower compared to higher shoreline altitudes. In the tributaries, erosion did not differ between higher and lower shoreline levels. Erosion increased with increasing fetch length, inundation duration and distance from the backwater tail, and decreased with increasing soil particle fineness. Our results provide a basis for identifying shorelines in need of restorative or protective measures. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Monitoring Tracer Stones in Fall Creek Gorge of Warren County, Indiana

    Science.gov (United States)

    Slaven, S.; Anders, A. M.

    2012-12-01

    Fall Creek, in western Indiana, is an incised ravine, draining a ~25 km2 rolling upland. The pothole section of Fall Creek Gorge is a bedrock-incised step-pool system consisting of a 70 meter long reach which drops approximately 3 meters over a series of 12 hydraulic jumps. Repeated surveys of bed topography are used to estimate sediment transport through this reach. In addition, we track the motion of locally-collected cobble to boulder sized particles using passive integrated transponder (PIT) tags. We observed a large change in bed morphology associated with a heavy rainfall event. Specifically, there was a net transport of sediment into the potholes reach. During the same event, tagged particles moved into and through the study area. The mobility of large particles supports the possibility that they act as tools shaping the potholes. Through ongoing monitoring we will assess the relationship between precipitation events and sediment transport and estimate the residence time of large particles within potholes. The ultimate goal is to understand the relationship between large sediment transport and pothole formation.;

  3. Lions as Bone Accumulators? Paleontological and Ecological Implications of a Modern Bone Assemblage from Olduvai Gorge.

    Science.gov (United States)

    Arriaza, Mari Carmen; Domínguez-Rodrigo, Manuel; Yravedra, José; Baquedano, Enrique

    2016-01-01

    Analytic models have been developed to reconstruct early hominin behaviour, especially their subsistence patterns, revealed mainly through taphonomic analyses of archaeofaunal assemblages. Taphonomic research is used to discern which agents (carnivores, humans or both) generate the bone assemblages recovered at archaeological sites. Taphonomic frameworks developed during the last decades show that the only large-sized carnivores in African biomes able to create bone assemblages are leopards and hyenas. A carnivore-made bone assemblage located in the short-grassland ecological unit of the Serengeti (within Olduvai Gorge) was studied. Taphonomic analyses of this assemblage including skeletal part representation, bone density, breakage patterns and anatomical distribution of tooth marks, along with an ecological approach to the prey selection made by large carnivores of the Serengeti, were carried out. The results show that this bone assemblage may be the first lion-accumulated assemblage documented, although other carnivores (namely spotted hyenas) may have also intervened through postdepositional ravaging. This first faunal assemblage potentially created by lions constitutes a new framework for neotaphonomic studies. Since lions may accumulate carcasses under exceptional circumstances, such as those documented at the site reported here, this finding may have important consequences for interpretations of early archaeological and paleontological sites, which provide key information about human evolution.

  4. Paleoenvironmental reconstruction of a paleosol catena, the Zinj archeological level, Olduvai Gorge, Tanzania

    Science.gov (United States)

    Driese, Steven G.; Ashley, Gail M.

    2016-01-01

    Paleosols record paleoclimatic processes in the Earth's Critical Zone and are archives of ancient landscapes associated with archeological sites. Detailed field, micromorphologic, and bulk geochemical analysis of paleosols were conducted near four sites at Olduvai Gorge, Tanzania within the same stratigraphic horizon as the Zinjanthropus (Paranthropus) boisei archeological site. Paleosols are thin (< 35 cm), smectitic, and exhibit Vertisol shrink-swell features. Traced across the paleolandscape over 1 km and just beneath Tuff IC (1.845 Ma), the paleosols record a paleocatena in which soil moisture at the four sites was supplemented by seepage additions from adjacent springs, and soil development was enhanced by this additional moisture. Field evidence revealed an abrupt lateral transition in paleosol composition at the PTK site (< 1.5 m apart) in which paleosol B, formed nearest the spring system, is highly siliceous, vs. paleosol A, formed in smectitic clay. Thin-section investigations combined with mass-balance geochemistry, using Chapati Tuff as parent material and assuming immobile Ti, show moderately intense weathering. Pedotransfer functions indicate a fertile soil system, but sodicity may have limited some plant growth. Paleosol bulk geochemical proxies used to estimate paleoprecipitation (733-944 mm/yr), are higher than published estimates of 250-700 mm/yr using δD values of lipid biomarkers.

  5. Landslide Monitoring Network Establishment within Unified Datum and Stability Analysis in the Three Gorges Reservoir Area

    Directory of Open Access Journals (Sweden)

    Shengxiang Huang

    2017-01-01

    Full Text Available A landslide monitoring network construction within unified datum which combined fiducial points, working reference points, and monitoring points was intensively studied in the Three Gorges Reservoir area. With special long and narrow geographical location in the area, designing and building monitoring network was vital to the realization of landslide monitoring. To build such a network with high precision, this paper mainly focused on the following four aspects: (1 method of using multiple GPS reference stations to build a unified datum network and subnet adjustment, (2 GPS data processing algorithm with millimeter level, (3 analysis of influence on the adjustment resulting from systematic error of time evolution datum from different GPS observations, and (4 establishment and stability analysis of unified datum. Then, using global test and trial-and-error method to analyze the datum based on the GPS observations (2008~2011 of landslide monitoring network in the area, we concluded that there were moved reference points during the three years of high water impoundment, and the horizontal displacement of moved reference points was more than 4 cm, even up to 79.4 cm. The displacement direction of unstable reference points was inspected with geographical environment at sites, which revealed congruency between them.

  6. Hominin raw material procurement in the Oldowan-Acheulean transition at Olduvai Gorge.

    Science.gov (United States)

    McHenry, Lindsay J; de la Torre, Ignacio

    2018-01-10

    The lithic assemblages at the Oldowan-Acheulean transition in Bed II of Olduvai Gorge, Tanzania, represent a wide variety of raw materials reflecting both the diversity of volcanic, metamorphic, and sedimentary source materials available in the Olduvai basin and surroundings and the preferences of the tool-makers. A geochemical and petrographic systematic analysis of lava-derived archaeological stone tools, combined with textural and mineralogical characterization of quartzite, chert, and other metamorphic and sedimentary raw materials from two Middle and Upper Bed II sites, has enabled us to produce a comprehensive dataset and characterization of the rocks employed by Olduvai hominins, which is used here to establish a referential framework for future studies on Early Stone Age raw material provenancing. The use of rounded blanks for most lava-derived artifacts demonstrates that hominins were accessing lava in local stream channels. Most quartzite artifacts appear to derive from angular blocks, likely acquired at the source (predominantly Naibor Soit hill), though some do appear to be manufactured from stream-transported quartzite blanks. Raw material composition of the EF-HR assemblage indicates that Acheulean hominins selected high-quality lavas for the production of Large Cutting Tools. On the other hand, the HWK EE lithic assemblage suggests that raw material selectivity was not entirely based on rock texture, and other factors, such as blank shape and availability of natural angles suitable for flaking, played a major role in Oldowan reduction sequences. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Evaluation of gridded precipitation data for driving SWAT model in area upstream of Three Gorges Reservoir.

    Science.gov (United States)

    Yang, Yan; Wang, Guoqiang; Wang, Lijing; Yu, Jingshan; Xu, Zongxue

    2014-01-01

    Gridded precipitation data are becoming an important source for driving hydrologic models to achieve stable and valid simulation results in different regions. Thus, evaluating different sources of precipitation data is important for improving the applicability of gridded data. In this study, we used three gridded rainfall datasets: 1) National Centers for Environmental Prediction-Climate Forecast System Reanalysis (NCEP-CFSR); 2) Asian Precipitation-Highly-Resolved Observational Data Integration Towards Evaluation (APHRODITE); and 3) China trend-surface reanalysis (trend surface) data. These are compared with monitoring precipitation data for driving the Soil and Water Assessment Tool in two basins upstream of Three Gorges Reservoir (TGR) in China. The results of one test basin with significant topographic influence indicates that all the gridded data have poor abilities in reproducing hydrologic processes with the topographic influence on precipitation quantity and distribution. However, in a relatively flat test basin, the APHRODITE and trend surface data can give stable and desirable results. The results of this study suggest that precipitation data for future applications should be considered comprehensively in the TGR area, including the influence of data density and topography.

  8. Assessment of hydrological changes in the Nile River due to the construction of Renaissance Dam in Ethiopia

    Directory of Open Access Journals (Sweden)

    Mohammed El Bastawesy

    2015-06-01

    Full Text Available This paper assesses impact of the Renaissance Dam on Ethiopia; on the Nile discharge ultimately reaches Egypt downstream. The Landsat-8 satellite images of 2013 were obtained and interpreted to identify locations for the construction sites for the Renaissance Dam. Then the Shuttle Radar Topography Mission (SRTM data were obtained and processed to create a digital elevation model (DEM for the Blue Nile upstream areas that will be submerged. Different scenarios for the dams’ heights and resulting storages were simulated to estimate the resulting abstraction of the Blue Nile flows until completion of the project and the annual losses due to evaporation thereafter. The current site (506 m asl for the Renaissance Dam allows the creation of a 100 m deep reservoir with a total storage of 17.5 km3; overflows will occur at that lake’s level (606 m asl from the north western part of the developed lake into Rosaires downstream. Construction of the spillway dam to control the overflow area can allow the creation of a 180 m deep lake that store up to 173 km3 in a lake that will cover 3130 km2. The analysis of Tropical Rainfall Monitoring Mission (TRMM suggests that the variation of total annual rainfall could reach 20%, thus the resulting hydrological fluctuations could affect the estimated filling time, the operational functions and discharge downstream. The negative hydrological impacts of the Renaissance Dam will increase by increasing the height of its spillway dam, as increasing the storage capacity could affect the strategic storage for the reservoirs in Egypt and Sudan. It is strongly recommended that an agreement should be reached to compromise the storage capacities and water supplies for all dams on the Nile to thoroughly satisfy the necessary needs.

  9. Understanding the role of farm dams in the Murray-Darling Basin in Australia through hydrological analysis coupled with stakeholder interviews

    Science.gov (United States)

    Kuil, Linda; Winnubst, Madelinde; van Dijk, Albert

    2013-04-01

    Climate predictions suggest that surface water availability in the Murray-Darling Basin (MDB) in Australia is more likely to decline than to increase in the next decades. In 2000, farm dams were first recognized as a significant risk to future flows in the MDB and have since been the subject of hydrological research. This study was conducted to provide insight into the role of farm dams in the Yass catchment, which is a subcatchment of the MDB close to Canberra, in order to indentify obstacles for integrated water management. The role of farm dams was investigated from both a hydrological and social perspective. Model prediction and data inference were used to estimate the impact of farm dams on streamflow. The density of farm dams in the catchment was estimated at 5.7 dams km-2. The impact on the Yass River was simulated to be in the order of 20 percent of mean annual streamflow. To understand why farm dams are used, semi-structured interviews were conducted to capture views and opinions of land holders. Research found that farm dams play a very important role in terms of individuals' water supply, although other systems are also used. Furthermore, land holders are responsible for their own water supply for drinking and agricultural water needs. Water rights are based on a right to rainfall or groundwater that is present on an individual's property. This means that landholders have both a need and a right to collect and store runoff. Current legislation put in place by the New South Wales government to restrict the amount of rain water to be captured does not seem to affect most people. If additional policy to minimize the impact of farm dams on streamflow were to be introduced, this has to be based on well-thought-out arguments based on a long term vision as the interview results indicate that farm dams are deeply embedded in Australian rural culture.

  10. Dam Seepage Investigation of an Earthfill Dam in Warren County, Missouri Using Geophysical Methods

    Directory of Open Access Journals (Sweden)

    Stanley C. Nwokebuihe

    2017-01-01

    Full Text Available Electrical resistivity tomography (ERT, induced polarization (IP and spontaneous potential (SP data were acquired across and in proximity to a leaking earth-fill dam (Wolf Creek dam in Warren County, Missouri. The objectives were to identify and map probable seepage pathways through the dam and to determine if the outlet works drainage pipe used in the construction of the dam was leaking. On the basis of the integrated interpretation of the acquired geophysical data two probable seepage pathways through the leaking earth-fill dam were identified and mapped. These two pathways are referred to as the Groin Leak and Water Fall Leak, respectively. The Groin Leak and Water Fall Leak seepage pathways are both characterized by relatively low resistivity and low chargeability. It is also concluded that there is high probability that water is leaking from the downstream end of the outlet works drainage pipe. The interpreted drainage pipe leak (Outlet works Leak is characterized by relatively low resistivity, high chargeability and negative self-potential values.

  11. Excavation of the Surikamigawa dam diversion tunnel. Surikamigawa dam karihaisui tunnel kantsu

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, T.; Konno, T. (Ministry of Construction, Tokyo (Japan))

    1994-04-01

    A bypass tunnel construction has been completed at the Surikamigawa dam (Japan). This paper describes the summary of the construction. The full-swing dam construction work is scheduled to begin in 1995. The soils distributed near the dam site consist of lapillus tuff containing andesite-based light stones and tuff-based conglomerates containing large gravels. Excavation of the dam diversion tunnel has used a blasting method, and the tunnel construction has adopted an automatic tunnel cross section marking system and a non-electric explosion method. This marking system is a system to irradiate a laser beam onto the facing to depict excavation lines that realizes labor saving and high-accuracy excavation. The error at the tunnel completion was found 20 mm. The non-electric explosion method ignites a coated explosive layer with an impact wave, which is electrostatically safe, and reduces blasting vibration. Electric detonators have also been used because of using ANFO explosives. The result obtained from measurements of inner space displacement necessary for the blasting process has indicated that the area near the dam site consists of stable mountains. 6 figs., 4 tabs.

  12. Effects of Long-Term Periodic Submergence on Photosynthesis and Growth of Taxodium distichum and Taxodium ascendens Saplings in the Hydro-Fluctuation Zone of the Three Gorges Reservoir of China.

    Directory of Open Access Journals (Sweden)

    Chaoying Wang

    Full Text Available Responses of bald cypress (Taxodium distichum and pond cypress (Taxodium ascendens saplings in photosynthesis and growth to long-term periodic submergence in situ in the hydro-fluctuation zone of the Three Gorges Dam Reservoir (TGDR were studied. Water treatments of periodic deep submergence (DS and moderate submergence (MS in situ were imposed on 2-year-old bald cypress and pond cypress saplings. The effects of periodic submergence on photosynthesis and growth were investigated after 3 years (i.e. 3 cycles compared to a control (i.e. shallow submergence, abbreviated as SS. Results showed that pond cypress had no significant change in net photosynthetic rate (Pn in response to periodic moderate and deep submergence in contrast to a significant decrease in Pn of bald cypress under both submergence treatments, when compared to that of SS. Ratios of Chlorophyll a/b and Chlorophylls/Carotenoid of pond cypress were significantly increased in periodic moderate submergence and deep submergence, while bald cypress showed no significant change. Diameter at breast height (DBH and tree height of both species were significantly reduced along with submergence depth. Relative diameter and height growth rates of the two species were also reduced under deeper submergence. Moreover, bald cypress displayed higher relative diameter growth rate than pond cypress under deep submergence mainly attributed to higher productivity of the larger crown area of bald cypress. When subjected to deep subergence, both species showed significant reduction in primary branch number, while in moderate submergence, bald cypress but not pond cypress showed significant reduction in primary branch number. These results indicate that both bald cypress and pond cypress are suitbale candidates for reforestation in the TGDR region thanks to their submergence tolerance characteristics, but bald cypress can grow better than pond cypress under deep submergence overall.

  13. Effects of Long-Term Periodic Submergence on Photosynthesis and Growth of Taxodium distichum and Taxodium ascendens Saplings in the Hydro-Fluctuation Zone of the Three Gorges Reservoir of China.

    Science.gov (United States)

    Wang, Chaoying; Li, Changxiao; Wei, Hong; Xie, Yingzan; Han, Wenjiao

    2016-01-01

    Responses of bald cypress (Taxodium distichum) and pond cypress (Taxodium ascendens) saplings in photosynthesis and growth to long-term periodic submergence in situ in the hydro-fluctuation zone of the Three Gorges Dam Reservoir (TGDR) were studied. Water treatments of periodic deep submergence (DS) and moderate submergence (MS) in situ were imposed on 2-year-old bald cypress and pond cypress saplings. The effects of periodic submergence on photosynthesis and growth were investigated after 3 years (i.e. 3 cycles) compared to a control (i.e. shallow submergence, abbreviated as SS). Results showed that pond cypress had no significant change in net photosynthetic rate (Pn) in response to periodic moderate and deep submergence in contrast to a significant decrease in Pn of bald cypress under both submergence treatments, when compared to that of SS. Ratios of Chlorophyll a/b and Chlorophylls/Carotenoid of pond cypress were significantly increased in periodic moderate submergence and deep submergence, while bald cypress showed no significant change. Diameter at breast height (DBH) and tree height of both species were significantly reduced along with submergence depth. Relative diameter and height growth rates of the two species were also reduced under deeper submergence. Moreover, bald cypress displayed higher relative diameter growth rate than pond cypress under deep submergence mainly attributed to higher productivity of the larger crown area of bald cypress. When subjected to deep subergence, both species showed significant reduction in primary branch number, while in moderate submergence, bald cypress but not pond cypress showed significant reduction in primary branch number. These results indicate that both bald cypress and pond cypress are suitbale candidates for reforestation in the TGDR region thanks to their submergence tolerance characteristics, but bald cypress can grow better than pond cypress under deep submergence overall.

  14. Sediment Transport Over Run-of-River Dams

    Science.gov (United States)

    O'Brien, M.; Magilligan, F. J.; Renshaw, C. E.

    2016-12-01

    Dams have numerous documented effects that can degrade river habitat downstream. One significant effect of large dams is their ability to trap sediment delivered from upstream. This trapping can alter sediment transport and grain size downstream - effects that often motivate dam removal decisions. However, recent indirect observations and modeling studies indicate that small, run-of-river (ROR) dams, which do not impede discharge, may actually leak sediment downstream. However, there are no direct measurements of sediment flux over ROR dams. This study investigates flow and sediment transport over four to six different New England ROR dams over a summer-fall field season. Sediment flux was measured using turbidity meters and tracer (RFID) cobbles. Sediment transport was also monitored through an undammed control site and through a river where two ROR dams were recently removed. These data were used to predict the conditions that contribute to sediment transport and trapping. Year 1 data show that tracer rocks of up to 61 mm were transported over a 3 m ROR dam in peak flows of 84% of bankfull stage. These tracer rocks were transported over and 10 m beyond the dam and continue to move downstream. During the same event, comparable suspended sediment fluxes of up to 81 g/s were recorded both upstream and downstream of the dam at near-synchronous timestamps. These results demonstrate the potential for sediment transport through dammed rivers, even in discharge events that do not exceed bankfull. This research elucidates the effects of ROR dams and the controls on sediment transport and trapping, contributions that may aid in dam management decisions.

  15. Dam spills and fishes; Eclusees et poissons

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    This short paper reports the main topics discussed during the two days of the annual colloquium of the Hydro-ecology Committee of EdF. The first day was devoted to the presentation of the joint works carried out by EdF, the Paul-Sabatier University (Toulouse), the Provence St-Charles University (Marseille), the ENSAT (Toulouse) and the CEMAGREF (Lyon and Aix-en-Provence) about the environmental impact of dam spills on the aquatic flora and fauna downstream. A synthesis and recommendations were presented for the selection and characterization of future sites. The second day was devoted to the hydro-ecology study of the dam reservoir of Petit-Saut (French Guyana): water reoxygenation, quality evolution, organic matter, plankton, invertebrates and fishes. The 134 French dams concerned by water spills have been classified according to the frequency of spills, the variations of flow rates created, and their impacts on fishing, walking, irrigation, industry, drinking water, navigation, bathing. Particular studies on different sites have demonstrated the complexity of the phenomena involved concerning the impact on the ecosystems and the water quality. (J.S.).

  16. Three Sisters Dam: Investigations and monitoring

    International Nuclear Information System (INIS)

    Slopek, R.J.; Courage, L.J.R.; Keys, R.A.

    1990-01-01

    The geotechnical investigations, monitoring and interpretation of data associated with the evaluation of the Three Sisters Dam, which has been suffering from excessive seepage and is in need of enhancement, are outlined. The Three Sisters Dam is located in the continental ranges of the Rocky Mountains in Alberta, impounding the Spray Reservoir, and is founded on 60 m of interbedded sand, gravel, silt and clay layers. The computer code PC-SEEP was used to evaluate seepage. Details are provided of drilling, ground-penetrating radar surveys, seismic surveys, penstock inspection, sinkhole activity, piezometer monitoring, silt wells, settlement monuments, and tailrace monitoring. The intensive investigations of the foundations showed that they consist of a complex formation of interfingered stratified layers and leases of talus and glaciofluvial deposits. Due to the depth and nature of these materials drill hole penetration was limited to the use of the Becker hammer. This equipment successfully delineated the major soil horizons of the foundation. The continued information attained from inspection, drilling, testing, radar surveys, seismic work, monitoring of piezometers, leakage, silt wells and settlement monuments indicated that there are no large voids within the foundation of the dam. 2 refs., 12 figs

  17. Numerical Analyses of Earthquake Induced Liquefaction and Deformation Behaviour of an Upstream Tailings Dam

    Directory of Open Access Journals (Sweden)

    Muhammad Auchar Zardari

    2017-01-01

    Full Text Available Much of the seismic activity of northern Sweden consists of micro-earthquakes occurring near postglacial faults. However, larger magnitude earthquakes do occur in Sweden, and earthquake statistics indicate that a magnitude 5 event is likely to occur once every century. This paper presents dynamic analyses of the effects of larger earthquakes on an upstream tailings dam at the Aitik copper mine in northern Sweden. The analyses were performed to evaluate the potential for liquefaction and to assess stability of the dam under two specific earthquakes: a commonly occurring magnitude 3.6 event and a more extreme earthquake of magnitude 5.8. The dynamic analyses were carried out with the finite element program PLAXIS using a recently implemented constitutive model called UBCSAND. The results indicate that the magnitude 5.8 earthquake would likely induce liquefaction in a limited zone located below the ground surface near the embankment dikes. It is interpreted that stability of the dam may not be affected due to the limited extent of the liquefied zone. Both types of earthquakes are predicted to induce tolerable magnitudes of displacements. The results of the postseismic slope stability analysis, performed for a state after a seismic event, suggest that the dam is stable during both the earthquakes.

  18. Reflections on hydroelectric dams in the Amazon: water, energy and development

    Directory of Open Access Journals (Sweden)

    Bertha Koiffmann Becker

    2012-12-01

    Full Text Available The essay discusses the deployment of hydroelectric dams in the Amazon having as a starting point the relations between water and hydropower consumption at different scales of analyses. So, if all parts of the world are affected by global processes, they are not in the same way. The global scale is dominated by the apocalyptic discourse of increasing water scarcity and global warming, requiring the reduction of emissions of greenhouse gases through the use of renewable energy and new technologies. On a Brazilian national scale, the problems are, rather, how to manage the abundance of water with social and territorial justice, and how to stop the loss of 20% of the electricity produced. Finally, it is at the regional scale - in the Amazon - that major problems arise: i the biggest paradox between the abundance of water and social inaccessibility to this resource; ii most of the dams planned for the country will be built there, with the risk of negative impacts already known; iii the obligation of building sluices at all the proposed dams, suggested by the industrial sector in name of the rivers navigation, will serve, in fact, to export commodities produced in the Brazilian central region. An ethical question is, therefore, posed to society and to Brazilian government: are really needed so many hydroelectric dams in the Amazon?

  19. [Temporal-spatial analysis of bacillary dysentery in the Three Gorges Area of China, 2005-2016].

    Science.gov (United States)

    Zhang, P; Zhang, J; Chang, Z R; Li, Z J

    2018-01-10

    Objective: To analyze the spatial and temporal distributions of bacillary dysentery in Chongqing, Yichang and Enshi (the Three Gorges Area) from 2005 to 2016, and provide evidence for the disease prevention and control. Methods: The incidence data of bacillary dysentery in the Three Gorges Area during this period were collected from National Notifiable Infectious Disease Reporting System. The spatial-temporal scan statistic was conducted with software SaTScan 9.4 and bacillary dysentery clusters were visualized with software ArcGIS 10.3. Results: A total of 126 196 cases were reported in the Three Gorges Area during 2005-2016, with an average incidence rate of 29.67/100 000. The overall incidence was in a downward trend, with an average annual decline rate of 4.74%. Cases occurred all the year round but with an obvious seasonal increase between May and October. Among the reported cases, 44.71% (56 421/126 196) were children under 5-year-old, the cases in children outside child care settings accounted for 41.93% (52 918/126 196) of the total. The incidence rates in districts of Yuzhong, Dadukou, Jiangbei, Shapingba, Jiulongpo, Nanan, Yubei, Chengkou of Chongqing and districts of Xiling and Wujiagang of Yichang city of Hubei province were high, ranging from 60.20/100 000 to 114.81/100 000. Spatial-temporal scan statistic for the spatial and temporal distributions of bacillary dysentery during this period revealed that the temporal distribution was during May-October, and there were 12 class Ⅰ clusters, 35 class Ⅱ clusters, and 9 clusters without statistical significance in counties with high incidence. All the class Ⅰ clusters were in urban area of Chongqing (Yuzhong, Dadukou, Jiangbei, Shapingba, Jiulongpo, Nanan, Beibei, Yubei, Banan) and surrounding counties, and the class Ⅱ clusters transformed from concentrated distribution to scattered distribution. Conclusions: Temporal and spatial cluster of bacillary dysentery incidence existed in the three gorges

  20. Petrography and geochemistry of the Dales Gorge banded iron formation: Paragenetic sequence, source and implications for palaeo-ocean chemistry

    DEFF Research Database (Denmark)

    Pecoits, E.; Gingras, M. K.; Barley, M. E.

    2009-01-01

    Banded iron formations (BIFs) have long been considered marine chemical precipitates or, as more recently proposed, the result of episodic density flows. In this study, we examined the mineralogy, petrography and chemistry of the Dales Gorge BIF to evaluate the validity of these models. Microbands...... provenance. Nonetheless, when all the lithologies (i.e., source rocks, S and BIF macrobands) are evaluated together, continuous geochemical trends can be observed. This suggests that at least part of the precursor material of BIF macrobands was sourced from the same material that gave origin to the S...

  1. Eruption History and Geochemical Evolution of Servilleta Basalt Along the Rio Grande Gorge, Colorado and New Mexico

    Science.gov (United States)

    Cosca, M. A.; Thompson, R. A.; Turner, K. J.; Morgan, L. E.

    2016-12-01

    Subalkaline basalt to basaltic andesite lava flows formally known as Servilleta Basalt (SB) are the most voluminous rock type forming the Pliocene Taos Plateau volcanic field. Pleistocene incision by the Rio Grande into the bedrock-floored plateau has resulted in spectacular exposures of occasionally thick ( 240 m) accumulations of SB within the Rio Grande gorge. Incremental CO2 laser heating of individual rock fragments, the SB within and along the length of the Rio Grande gorge has been precisely dated by 40Ar/39Ar geochronology to between 5.3 Ma and 3.3 Ma. SB older than 4 Ma is restricted to some lava flows exposed between La Junta point, at the confluence of the Red River and Rio Grande, and the Gorge Bridge crossing northwest of Taos, NM. Vertical sampling through thick SB flow sequences within the gorge yields precise emplacement histories and also reveals small but systematic major and minor element concentration variations (including Si, Rb, Sr, Cu and Zn). 40Ar/39Ar data show that these trends developed over short (0-250 ka) timescales, and probably relate to partial assimilation of crust, possibly at multiple depths. Combined field, geochemical, and 40Ar/39Ar data consequently record short-lived changes in tholeiitic melt compositions in response to regional extension and development of the Rio Grande rift. The age, lateral extent, and thickness of exposed SB partially reflect the paleotopographic surface of the southern San Luis Basin prior to onset of Pliocene Taos Plateau volcanic field magmatism; paleotopographic highs diverted some flows while topographic lows were areas of infilling and accumulation. Heterogeneous basin paleotopography developed during contemporaneous or precursory andesitic to dacitic volcanism, extensional faulting and subsidence of sub-basins within the San Luis Basin, and deposition of prograding alluvial fans that originated in the Sangre de Cristo and Picuris Mountains. SB flowed into the southern San Luis Valley beginning 5

  2. The Gorge of the Missouri: An Archeological Survey of Lewis and Clark Lake, Nebraska and South Dakota. Volume 1.

    Science.gov (United States)

    1983-05-01

    8217s and 1950’s as a virutal abandonment of the reservation. The 1970 decennial census estimates 84 AD-A139 118 THE GORGE OF THE MISSOURI: AN...in emphasis of BIA policy. The discontinuance of the agency, considered before 1900, became a reality in 1917, and the crumbling buildings were...hilly land suitable only for grazing, so that in reality they have been unable to replace the tillable land lost to the formation of the lake. One of

  3. Do Hydroelectric Dams Mitigate Global Warming? The Case of Brazil's Curuna Dam

    Energy Technology Data Exchange (ETDEWEB)

    Fearnside, P.M. [National Institute for Research in the Amazon (INPA), C.P. 478, 69011-970 Manaus, Amazonas (Brazil)

    2005-10-15

    Hydroelectric dams in tropical forest areas emit greenhouse gases, as illustrated by the Curuna dam in the Amazonian portion of Brazil. Emissions include carbon dioxide from decay of the above-water portions of trees that are left standing in the reservoir and methane from soft vegetation that decays under anaerobic conditions on the bottom of the reservoir, especially macrophytes (water weeds) and vegetation that grows in the drawdown zone and is flooded when the reservoir water level rises. Some methane is released from the reservoir surface through bubbling and diffusion, but larger amounts are released from water passing through the turbines and spillway. Methane concentration in the water increases with depth, and the turbines and spillway draw water from sufficient depth to have substantial methane content. In 1990 (13 years after filling), the Curuna Dam emitted 3.6 times more greenhouse gases than would have been emitted by generating the same amount of electricity from oil.

  4. Geochemistry of tephra from Bed I, Olduvai Gorge, Tanzania: Stratigraphic correlations and implications for magmatic evolution

    Science.gov (United States)

    McHenry, L.

    2003-04-01

    At least 10 predominantly trachytic and rhyolitic tuffs are preserved interbedded in volcaniclastic sediments of Plio-Pleistocene Bed I, Olduvai Gorge, Tanzania. Physical correlation of the tuffs is complicated by faulting and variation in preservation and lithofacies. Differences in the degree and type of tephra alteration (clay, zeolitic, none) and preservation of glass shards within the various depositional environments (saline-alkaline lake, lake margin, wetlands, alluvial fan) make correlation by conventional glass chemistry methods impossible. However, variations in overall mineralogy and chemical compositions of co-magmatic phenocrysts (feldspar, augite, titanomagnetite, amphibole) have proven useful to uniquely characterize the tuffs for correlation purposes. Samples of 10 major tuffs in the Olduvai Bed I sequence were collected from various depostional and preservational environments situated up to 15 km apart. Thin sections and mineral separates (10-60 grains of each type of phenocryst/ sample, 2-3 samples/ tuff) were analyzed by electron microprobe for major and minor elements. The lower Bed I tuffs are rhyolitic and easily distinguished from the upper tuffs by the presence of quartz and high-Fe augite. Feldspar composition has been previously found to separate all of the upper tuffs (1B-1F) except the two trachyandesitic tuffs (1D and the "unnamed" tuff between 1E and 1F). Mn and Ti concentrations in the titanomagnetites separate the upper tuffs (MnO%: 1B=1.5-2, 1C=1.3-1.6, 1D=1.1-1.4, 1E=1.5-1.7, unnamed= 0.9-1.2, 1F=1.6-2; TiO2%: 1B, 1E=23-26, 1C=18-22, 1D=25-27, unnamed=20-21, 1F= 12-20). Tuffs 1B, unnamed, and 1F contain abundant amphibole, 1D contains none. Mn and Fe concentrations in the augites also separate the tuffs (MnO%: 1B=1.2-1.5, 1C=0.9-1.2, 1D=0.6-0.9, 1E=0.9-1.1, unnamed=0.5-0.7, 1F=variable; FeO%: 1B=19-21, 1C=15-19, 1D=12-16, 1E=13-16, unnamed=11-14, 1F=variable). Results of these findings provide new widespread markers in the Olduvai

  5. Hydrothermal alteration of the Ediacaran Doushantuo Formation in the Yangtze Gorges area (South China)

    Science.gov (United States)

    Derkowski, Arkadiusz; Bristow, Thomas F.; Wampler, J. M.; Środoń, Jan; Marynowski, Leszek; Elliott, W. Crawford; Chamberlain, C. Page

    2013-04-01

    The geochemical and fossil record preserved in the Ediacaran age (635-551 Ma) Doushantuo Formation of South China has been extensively examined to explore the impact of changing climate and the oxidation state of the oceans on the development and distribution of early multicellular life. In the Yangtze Gorges area, this formation shows many of the geochemical trends and features thought to typify global ocean chemistry in the Ediacaran Period, but there are indications that post-sedimentary processes modified these signals. This study of clay minerals and organic matter builds a more detailed picture of the type and degree of post-sedimentary alteration at different stratigraphic levels of the formation and focuses on how this alteration influenced stable carbon and oxygen isotope records. In the cratonward Jiulongwan and Huajipo sections of the Doushantuo Formation, its lower part (Members 1 and 2) consists largely of dolomitic shale, rich in authigenic saponite that crystallized in an alkaline sedimentary basin. Saponite has been altered to chlorite via corrensite across tens of meters of strata in lower Member 2, with increased alteration downward toward the cap dolostone. The greater chloritization is accompanied by lower δ18O and higher δD values of trioctahedral clays. This pattern of alteration of trioctahedral clays is likely due to hydrothermal fluid activity in the underlying, relatively permeable Nantuo Formation and cap dolostone. A concomitant increase of solid bitumen reflectance toward the base of the formation supports this idea. In the uppermost part of the formation in the Yangtze Gorges area (Member 4), a typical open water marine dolomitic shale rich in illite and organic matter, increases in the methylphenanthrenes ratio index and solid bitumen reflectance correlate with decrease of the bulk rock K/Al ratio upward, providing evidence for hot fluid migration above the nearly impermeable shale. Clay from the upper part of the formation is

  6. Characterization of heavy metal contamination in the soil and sediment of the Three Gorges Reservoir, China.

    Science.gov (United States)

    Wang, Tujin; Pan, Jin; Liu, Xuelian

    2017-02-23

    This paper analyzes the concentration, distribution, bioavailability, and potential heavy metal contamination risk of Cu, Pb, Cd, Zn, and Cr in the soil and sediment of the Three Gorges Reservoir (TGR). In this paper, 14 stations that cover the upper reaches to the lower reaches of the TGR were selected. The spatial distribution of heavy metals in the TGR showed that the average concentrations of Cu, Pb, Cd, Zn, and Cr were higher in the upper and lower reaches than those in the middle reaches because of industrial and agricultural activities as well as natural processes (e.g., soil erosion, rock weathering). The results also indicated that multiple pollution sources and complex geomorphological, geochemical and biological processes resulted in remarkably higher heavy metal concentrations in the soils of the water-level-fluctuation zone (WLFZ) than in the soils of the banks. The Cu, Pb, Cd, Zn, and Cr concentrations in the soils of the TGR did not exceed their respective maximum allowable concentration (MAC) values for agricultural soils in China, indicating that the soil in the TGR was not seriously contaminated with Cu, Pb, Cd, Zn, or Cr. However, the mean concentrations of all the studied metals in the sediments were higher than the geochemical background values and much higher than those in the soils, thus indicating the effect of the pollution sources and the altered hydrologic conditions that occurred after the impoundment of the TGR. A geoaccumulation index analysis indicated that the TGR sediments were moderately polluted with Cu and Cd, unpolluted to moderately polluted with Pb and Cr, and unpolluted with Zn. Fractionation studies indicated that Cd was mainly present in the non-residual fractions and exhibited great instability and bioavailability; furthermore, the alternating wetting and drying of the WFLZ soils enhance the mobility and bioavailability of Cd. Thus, greater attention should be paid to Cd pollution in the TGR because of its higher risk

  7. Tephrochronology of Bed II, Olduvai Gorge, Tanzania, and placement of the Oldowan-Acheulean transition.

    Science.gov (United States)

    McHenry, Lindsay J; Stanistreet, Ian G

    2018-04-12

    Tuffaceous marker beds, derived from volcanic products from the Ngorongoro Volcanic Highlands, help define a stratigraphic framework for the world-renowned fossil and stone tool record exposed at Olduvai Gorge, Tanzania. However, previous efforts to constrain this tuff record, especially for Olduvai Bed II, have been limited because of erosion, contamination, reworking, and the alteration of volcanic glass under saline-alkaline conditions. This paper applies previously defined geochemical and mineralogical "fingerprints" for several major Bed II marker tuffs, based on glass (where available) and phenocrysts more resistant to alteration (feldspar, hornblende, augite, and titanomagnetite), to tuffs from stratigraphic sections in the Olduvai Junction Area, including previously and recently excavated Acheulean and Oldowan sites (HWK EE (Locality (Loc) 42), EF-HR (Loc 12a), FLK (Loc 45), and MNK (Loc 88)). The Middle Bed II Bird Print Tuff (BPT) is found to be more compositionally variable than previously reported but is still valuable as a stratigraphic marker over short distances. The confirmation of blocks of Tuff IID in conglomerate helps constrain Upper Bed II stratigraphy at sites where in-situ tuffs are absent. This paper also compiles the results of published geochronological research, providing stratigraphic context and updating previously reported dates using a consistent 40 Ar/ 39 Ar reference standard age. The results of this work support the following paleoanthropologically relevant conclusions: 1) the early Acheulean site EF-HR (Loc 12a) is situated above the level of Hay's Tuff IIC, and thus sits in Upper rather than Middle Bed II, (2) the HWK EE (Loc 42) Oldowan site is constrained between Tuff II