共查询到20条相似文献，搜索用时 31 毫秒
1.
针对澜沧江高坝大库对物质迁移转化的影响问题, 自主研发了深库智慧采样设备和潜流带动态监测系统, 于2016年、2017年、2018年开展了澜沧江上游1 290 km的9个梯级水库的监测分析, 实现了280 m最大工作水深的垂向分层水样与沉积物样无扰动采集和潜流带水土环境界面的多指标监测。研究发现: 梯级水库促进了水体中生物有效磷、氨氮占比和沉积物中生物有效磷释放的沿程增加;沉积物中甲基汞的分布与泥沙颗粒沉降有关, 受到水力停留时间和库龄的共同调控;温室气体的排放通量因建坝有所提升, 但远低于世界平均水平;潜流带因干湿交替频率和面积的增加, 加强了水库关键带脱氮和温室气体削减效应;水库中微生物群落并未因建坝隔离, 在沿程和垂向上, 水温都是其关键影响因子。 相似文献
2.
Prashanth Reddy Hanmaiahgari Nooka Raju Gompa Debasish Pal Jaan Hui Pu 《Natural Hazards》2018,91(3):1075-1096
The present study attempts to predict the reservoir sedimentation in 32 km region of the Tenryu River between the Hiraoka and Sakuma Dams in Japan. For numerical simulations of the reservoir sedimentation, the one-dimensional model of the Hydrologic Engineering Centre-River Analysis System (HEC-RAS) is used together with the inclusion of channel geometry, bed gradation curve, Exner-5 bed sorting mechanisms, fall velocity of the particle, and flow and sediment boundary conditions pertaining to modeling region. The modeling region of the Tenryu River is divided into 48 river stations with 47 reaches in the numerical simulations. The numerical model is calibrated using the available data for 48 years from 1957 to 2004. The formulae of sediment transport function, Manning’s roughness coefficient, computational increment and fall velocity have been identified for getting the best estimation of the Sakuma Dam reservoir sedimentation. Combination of obtained sensitive parameters and erodible limits of 2 m gave the best comparison with the measured bed profile. The computed results follow the trend of measured data with a small underestimation. Although Manning’s roughness coefficient has an effect on the sedimentation, no direct relation is found between the Manning’s roughness coefficient and reservoir sedimentation. It is found that the temperature of water has no effect on the reservoir sedimentation. 相似文献
3.
Anzhou Zhao 《Arabian Journal of Geosciences》2016,9(15):664
Hydrological process modeling depends on the soil data spatial resolution of the watershed. Especially, in a large-scale watershed, could a higher resolution of soil data contribute to a more accurate result? In this study, two soil datasets with different classification systems FAO (World Reference Base) and GSCC (the Genetic Soil Classification of China) were used as inputs for the SWAT model to study the effects of soil datasets on hydrological process modeling in Weihe River basin, China. Results show that the discharge simulated using FAO soil data was better than one simulated using GSCC soil data before model calibration, which indicates that FAO soil data needed less effort to calibrate. After model calibration, discharges were simulated better by both of FAO and GSCC soil data but statistical parameters demonstrate that we can make a relatively more accurate estimation of discharge using the GSCC rather than FAO soil data. Soil water content (SW) simulated using GSCC soil data was statistically significantly higher than those simulated using FAO soil data. However, variations in other hydrological components (surface runoff (SURQ), actual evapotranspiration (ET), and water yield (WYLD) were not statistically significant. This might be because SW is more sensitive to soil properties. For studies aiming to simulate or compare SW, merely calibrating and validating models using river discharge observations is not enough. The hydrological modelers need to identify the key hydrological components intrinsic to their study and weigh the advantages and disadvantages before selecting suitable soil data. 相似文献
4.
High turbid water in the river has been one of the major concerns to the downstream residence. During heavy local rainfall, high turbid water occurs in many countries located in the Asian monsoon climate region. The Andong and the Imha reservoir, two adjacent multipurpose dams, located in the upstream of the Nakdong River in Korea have suffered from severe turbid water problem. This study applied hydrodynamic water quality model CE-Qual-Riv1 to simulate turbidity propagation in downstream coupled with long-term watershed hydrologic model SWAT to consider contributions of tributaries. The outputs of runoff and suspended sediment in tributaries are incorporated into the input data necessary for the hydrodynamic water quality model. The simulation focused on the joint dam operation to minimize the negative impact of high turbid water in downstream river. Simulated turbidity in downstream shows a good agreement with the observed data, and the approach proposed in this study is applicable for establishing a sound turbid water management in downstream of the reservoir. 相似文献
5.
Spatial and isotopic analysis of watershed soil loss and reservoir sediment accumulation rates in Lake Anna, Virginia, USA 总被引：1，自引：1，他引：0
Soil erosion and associated sedimentation are a threat to the sustainable use of surface water resources through the loss
of volume storage capacity and conveyance of pollutants to receiving water bodies. The RUSLE2 empirical model and isotopic
sediment core analyses were used to evaluate watershed erosion and reservoir sediment accumulation rates for Lake Anna, in
Central Virginia. A sediment flux rate of 66,000 Mg/year was estimated from the upper basin and land use was determined to
be the primary factor contributing to soil erosion. Barren lands and agricultural activities were estimated to contribute
the most sediment (>20 Mg/ha/year), whereas forested and herbaceous landscapes were less likely to erode (<0.3 Mg/ha/year).
Eleven separate 210Pb-based estimates of sediment accumulation were used to construct reservoir-scale sedimentation rates. Sedimentation rates
in the upper reaches of the reservoir were variable, ranging from 2.3 to 100 Mg/ha/year, with a median rate of 8.4 Mg/ha/year.
Historical sedimentation showed an increase in annual accumulation from 1972 to present. Based on these data the reservoir
has experienced a 2% loss of volume storage capacity since impoundment in 1972. Results from this study indicate that Lake
Anna is not currently experiencing excessive sedimentation and erosion problems. However, the predominance of highly erosive
soils (soil erodibility factor >0.30) within the watershed makes this system highly vulnerable to future anthropogenic stressors. 相似文献
6.
Soil erosion is a serious environmental problem in Indravati catchment. It carries the highest amount of sediments compared
with other catchments in India. This catchment spreading an area of 41,285 km2 is drained by river Indravati, which is one of the northern tributaries of the river Godavari in its lower reach. In the
present study, USLE is used to estimate potential soil erosion from river Indravati catchment. Both magnitude and spatial
distribution of potential soil erosion in the catchment is determined. The derived soil loss map from USLE model is classified
into six categories ranging from slight to very severe risk depending on the calculated soil erosion amount. The soil erosion
map is linked to elevation and slope maps to identify the area for conservation practice in order to reduce the soil loss.
From the model output predictions, it is found that average erosion rate predicted is 18.00 tons/ha/year and sediment yield
at the out let of the catchment is 22.30 Million tons per annum. The predicted sediment yield verified with the observed data. 相似文献
7.
M. A. Levitan A. N. Balukhovskii T. A. Antonova T. N. Gelvi 《Geochemistry International》2013,51(5):345-352
Using the methodology of A.B. Ronov, we compiled lithofacies maps for the Early and Middle-Late Pleistocene pelagic sedimentation of the Pacific Ocean, accounting for sediment thicknesses. We calculated areas, volumes, masses, and accumulation rates of main sediment types for both Pleistocene subdivisions. A comparison of the results confirmed a strong increase in the rates of terrigenous and biogenic sedimentation. Special emphasis was laid on intensification of sea-ice and eolian sedimentation for the terrigenous types of sediments and on the evolution of siliceous and carbonate sedimentation for the biogenic types of sediments. 相似文献
8.
9.
Several small reservoirs and a large number of check dams had been constructed in the Wangkuai reservoir watershed after 1970s, and flood time series lacked stationarity, which affected the original design flood hydrographs for the Wangkuai reservoir. Since the location, storage capacity and drainage area of the large number of check dams were unknown, we present a method to estimate their total storage capacities (TSC) and total drainage areas (TDA) by using the recorded rainstorm and flood data. On the basis of TSC and TDA, the flood events which occurred in an undisturbed period were reconstructed under current conditions to obtain a stationary flood series. A frequency analysis was subsequently performed to assess the design flood peak and volume for both small and medium design floods with a 10–200 year return period. For large and catastrophic floods, it was assumed that the upstream check dams and small reservoirs would be destroyed, and water stored in these hydraulic structures were re-routed to the Wangkuai reservoir by unit hydrograph. The modified flood peak and volume decreased for floods with a 10–200 year return period when compared to the current design flood. But for large design floods with a return period exceeding 500 years, peak discharge increased. This study provides a new method for design flood calculation or modification of the original design flood in watersheds with a large number of check dams. 相似文献
10.
Turbid-water problem of reservoirs due to soil erosion causes a major issue in dam operation. This study presents a methodology
to quantitatively analyze the occurrence possibility of turbid-water in four hydrologic basins (Sayeon, Degok, Gwangdong,
and Imha Dam basins in S. Korea), quantifying the weighting value of turbid-water occurrence in reservoirs. To do this, the
study conducted indoor tests, including laser-assisted particle size analysis, X-ray powder diffraction method analysis, and
scanning electron microscope, to give the geologic characteristics such as the distribution of soil particle size, settlement
time, landslide, and existing sediment yield. The study used RUSLE models to calculate sediment yield on the basis of soil
maps, DEMs, and landcover maps as auxiliary data. This study classified factors for evaluating the possibility of turbid-water
occurrence into geology, sediment yield, landslide and soil components, and these evaluation items’ weighting and score are
presented using the analytic hierarchy process technique. The suggested method is promising in that it can analyze the risk
factor of turbid-water occurrence in basins and that can provide a guideline to estimate the turbid-water occurrence of reservoir
in dam construction. 相似文献
11.
Tayebeh Zinati Shoa Saeedeh Nateghi Ahmad Nohegar Fazel Amiri Biswajeet Pradhan 《Arabian Journal of Geosciences》2014,7(7):2841-2850
Soil erosion and sediment yield from catchments are key limitations to achieving sustainable land use and maintaining water quality in nature. One of the important aspects in protecting the watershed is evaluation of sediment produced by statistical methods. Controlling sediment loading in protecting the watershed requires knowledge of soil erosion and sedimentation. Sediment yield is usually not available as a direct measurement but is estimated using geospatial models. One of the geospatial models for estimating sediment yield at the basin scale is sediment delivery ratio (SDR). The present study investigates the spatial SDR model in determining the sediment yield rate considering climate and physical factors of basin in geographic information system environment. This new approach was developed and tested on the Amammeh catchments in Iran. The validation of the model was evaluated using the Nash Sutcliffe efficiency coefficient. The developed model is not only conceptually easy and well suited to the local data needs but also requires less parameter, which offers less uncertainty in its application while meeting the intended purpose. The model is developed based on local data. The results predict strong variations in SDR from 0 in to 70 % in the uplands of the Basin. 相似文献
12.
Changbin Li Jiaguo Qi Zhaodong Feng Runsheng Yin Songbing Zou Feng Zhang 《Frontiers of Earth Science》2010,4(3):296-310
This study simulated the watershed flow and sediment responses based on calibration of the SWAT model in the semi-arid Chinese
Loess Plateau (LP) where soil erosion intensively occurs. After the model’s initiation and manual modification, a 7-year inconsecutively
observed flow and sediment data from 1984 to 1990 was used to analyze the model’s application in the selected watershed called
AJW in the Chinese LP region. The model procedure included sensitivity analysis, parameter calibration and model validation.
The best parameter set was finally determined based on the combination of parameter localization and auto-calibration. Then
the model was assessed for its accuracy based on the NSE estimation, resulting in 0.77 and 0.67 for calibration and 0.46 and
0.32 for validation on simulations for flow and sediment, respectively, which is a moderately satisfactory accuracy among
the applications of the SWAT model. Annual watershed assessment on flow and sediment with the calibrated SWAT model resulted
in a multiyear averaged annual runoff coefficient of about 2.7% and an erosion modulus of 797 t/(km2·a−1) in the AJW, indicating a beneficial consequence from the implementation of the historical soil and water conservations. 相似文献
13.
小型水坝随着服役时间的增长,其面临的安全、经济和生态方面问题日益突出,针对一些修复价值较低的病险水坝,实施降等或报废拆除已成为一种综合最佳的管理措施。拆坝后,原库区大量淤沙无控释放将改变原有河道形态,对水生生物栖息地造成影响。为预测拆坝后河道在不同时间尺度上的变化特征,以长江流域乌江水系内的西河水坝为研究对象,建立二维水沙数学模型,分别研究了拆坝后水沙输运造成的短期和长期河床形态变化。结果表明:拆坝后短期内,坝址上游主河道发生了强烈的冲刷下切,且水库淤沙前缘部分出现了显著的淤积抬高,相比而言,坝址下游河床变化并不明显,只有坝下河段及河口附近出现较显著的泥沙淤积;在拆坝后长期的河床演变过程中,坝址上下游河道均发生了不同程度的冲刷下切,拆坝2年后下游河床逐渐趋于稳定,而上游主河道由冲刷下切转化为冲淤交替的演变趋势,河床形态不断调整变化。本研究可为病险坝和小水电报废拆坝后的河道治理、水生生物栖息地修复提供参考依据。 相似文献
14.
The application of range of variability approach to the assessment of a check dam on riverine habitat alteration 总被引：2，自引：0，他引：2
This report uses the intermediate disturbance hypothesis to assess the influence of constructing a check dam on river environment.
HEC-HMS and HEC-RAS programs were used to generate hydraulic parameters such as flow discharge, water depth, velocity, water
surface width and sediment discharge. Indicators of hydrologic alteration (IHA) and indicator of habitat alteration (IHabA)
were used to evaluate the flow and habitat conditions before and after check dam construction. The range of variability approach
was used to calculate the degree of hydrologic alteration for each IHA, degree of habitat alteration and overall alteration
for IHabA. Variability of river habitats before and after check dam construction was contrasted. Alteration became larger
the closer to the dam body. An assessment method for check dam construction is offered which does not require ecological investigation
data and combines ecology concepts and hydraulics. 相似文献
15.
In this study, the effects of changes in historical and projected land use land cover (LULC) on monthly streamflow and sediment yield for the Netravati river basin in the Western Ghats of India are explored using land use maps from six time periods (1972, 1979, 1991, 2000, 2012, and 2030) and the soil and water assessment tool (SWAT). The LULC for 2030 is projected using the land change modeller with the assumption of normal growth. The sensitivity analysis, model calibration, and validation indicated that the SWAT model could reasonably simulate streamflow and sediment yield in the river basin. The results showed that the spatial extent of the LULC classes of urban (1.80–9.96%), agriculture (31.38–55.75%), and water bodies (1.48–2.66%) increased, whereas that of forest (53.04–27.03%), grassland (11.17–4.41%), and bare land (1.09–0.16%) decreased from 1972 to 2030. The streamflow increased steadily (7.88%) with changes in LULC, whereas the average annual sediment yield decreased (0.028%) between 1972 and 1991 and increased later (0.029%) until 2012. However, it may increase by 0.43% from 2012 to 2030. The results indicate that LULC changes in urbanization and agricultural intensification have contributed to the increase in runoff, amounting to 428.65 and 58.67 mm, respectively, and sediment yield, amounting to 348 and 43 ton/km2, respectively, in the catchment area from 1972 to 2030. The proposed methodology can be applied to other river basins for which temporal digital LULC maps are available for better water resource management plans. 相似文献
16.
Data from the literature were used to revise a set of lithofacies maps for the Triassic-Jurassic epochs published by V.E. Khain, A.B. Ronov, and A.N. Balukhovskii in 1983. The study area is the Circum-Arctic belt, whose present-day northern boundary lies along the shelf break, and the southern boundary, at a latitude of 60° N. For the purpose of our study we used a simplified legend, which does not show climatic and tectonic features and emphasizes lithofacies zones. For each map, we calculated areas and volumes of sediments of the identified lithofacies zones and particular types of sediments. Using these data, we estimated the masses of dry sediment and rates of sediment accumulation. Trends in the distribution of the quantitative parameters of the Circum-Arctic belt were compared with global trends driven by tectonic and climatic changes. The contributions of regional-scale characteristics of sediment accumulation were identified. The results of this study indicate that global trends played a dominant role in regional sedimentation history. Two stages, Triassic and Jurassic, were distinguished in the history of sedimentation. 相似文献
17.
Paweena Panichayapichet Suwanchai Nitisoravut Arpa Wangkiat 《中国地球化学学报》2006,25(B08):119-120
Discharge of wastewater from the retaining pond of a Pb ore-flotation plant since 1967 and breaching of the retaining pond in April 1998 contaminated 17540 cbm of river bank sediment with 833 ton Pb, nearly 19 km along the Khli Ti Creek. High blood Pb concentration was detected in many inhabitants. Prohibition of water and aquatic biota consumption has caused difficulties for rural people to make their ends meet. The governmental agency closed the ore-floatation plant and built 2 rock check dams downstream. The dam was designed to slow down water velocity and precipitate particulate matter. Contaminated sediments that have been trapped in front of the dam were planned to be dredged and disposed in landfill. Until now, no dredging is performed because some experts claim that dredging will resuspend the contaminated sediment into the water column, and fresh sediment deposited during periods of high flow will cover the contaminated sediment. The aim of this study was to evaluate the ability of the rock check dam to prevent the transportation of Pb-contaminated sediment in the Khli Ti Creek. Sediment located before and after the rock check dam and 2 km downstream were collected in September 2003 and May 2005. During September 2003, Pb concentrations in sediment deposited before and after the rock check dam and 2 km downstream were 48840, 53741 and 36020 mg/kg, respectively. These results showed that Pb-contaminated sediment was transported over the first rock check dam but still remained after the rock check dam. Result of May 2005 sampling also showed the same trend, although with different ranges due to seasonal variation, types of collected sediment, sample preparation and analytical techniques. Pb concentrations in sediment were 209684, 306775 and 33760 mg/kg, respectively. 相似文献
18.
When a dam is constructed on a river to store water, sediments transported by the water flow are also stored and reservoir
capacity is gradually reduced by sediment accumulation. Prediction of sediment distribution in reservoirs is an important
issue for dam designers to determine the reservoir active storage capacity, outlet sill elevation, dam stability, recreational
facilities, and backwater conditions. The main objective of this study is to develop the most reliable parameters of sedimentation
that are directly or indirectly influencing in the equations and measured dataset. For validation of the proposed parameters,
data of 40 reservoir sets gathered from different reliable sources, rather than focusing entirely on bed-load equations. Artificial
neural network (ANNs) method was used to validate this study. Several graphs and statistical analysis were presented to emphasize
the influencing effect of those parameters that were detected by ANNs and are directly controlling the error in the bed-load
sediment flux using measured particles datasets. 相似文献
19.
Agricultural nonpoint source (NPS) pollution at the Three Gorges reservoir area in China has been increasingly recognized as a threat to aquatic environment in recent years due to the serious eutrophication problem. Adsorbed NPS pollution is one of the major forms of NPS pollution in mountainous regions, the essential of the adsorbed NPS pollution is soil loss. Thus, simple, highly sensitive and continuous methods are required to simulate and quantify sediments yield at watershed scales. It is imperative to construct an integrated model to estimate the sediment yield and adsorbed NPS pollution load. According to the characteristics of climate, hydrology, topography, geology, geomorphology and land use types in Three Gorges reservoir area, a GIS-based dynamic-integrated-distributed model of annual adsorbed NPS load was presented in view of impacts of the rainfall intensity, sediment delivery ratio (SDR) and land management, where the temporally dynamic-continuous model of annual sediment yield was established by modifying the revised Universal Soil Loss Equation (RUSLE), and the spatially integrated-distributed model of annual adsorbed NPS load was then developed via the correlation between sediment yield and adsorbed NPS load. Furthermore, a case study of the Jialing River basin in China was applied to validate the integrated model, the dynamic-distributed coupling among GIS technology, sediment yield model, and adsorbed NPS load model was achieved successfully. The simulation results demonstrate the following: (1) runoff and sediment are influenced greatly by rainfall intensity, SDR and vegetation cover; rainfall and land management show high sensitivities to the integrated model; the average annual adsorbed TN and TP pollution loads from 2006 to 2010 decreased by 76 and 74 % compared with the previous treatment (1990), respectively. (2) Spatio-temporal variations of adsorbed NPS nitrogen and phosphorus load are mainly related to different land use types and the background level of nutriments in topsoil; different land use types have different contribution rates; the largest contribution rates of adsorbed total nitrogen (TN, 58.9 %) and total phosphorus (TP, 53 %) loads are both from the dryland cropland. (3) The identification of critical source areas can help to implement the prevention and control measures aiming at the reduction of water environmental pollution. These results will provide useful and valuable information for decision makers and planners to take sustainable land use management and soil conservation measures for the control of sediment pollution in the Three Gorges reservoir area. The application of this model in the catchment shows that the integrated model may be used as a major tool to assess sediment yield risks and adsorbed NPS pollution load at mountainous watersheds. 相似文献
20.
Dams and their reservoirs, constructed to manage the water scarcity problems of a region, sometimes lose whole or part of their functionality due to sedimentation. This issue, seen as a negative impact as far as reservoir life and its purpose is concerned, can be a boon to the construction industry, by providing a highly demanding construction material in the form of sand dredged from the reservoirs. Malampuzha reservoir, a multipurpose reservoir in the South Indian state of Kerala, is also losing considerable part of its storage due to siltation. This paper assesses the rate of sedimentation in Malampuzha reservoir, through bathymetric survey and suggests measures for utilization of the removable sediment. Our analysis has shown that the reservoir capacity is reduced from 226 to 205.19 Mm3; a reduction in capacity of 20.81 Mm3 in 55 years. The rate of sedimentation of the reservoir is estimated as 16.95 mm/year. The dead storage capacity of the reservoir has reduced to 47.5 % from the original at present. The composition of deposited sediments is also identified, based on which its productive use is recommended. 相似文献