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1.
 King Talal Dam (KTD) watershed is the most important one in Jordan. At its outlet lies the KTD (80 MCM capacity) which serves irrigation purposes in the Jordan Valley. However, the dam suffers from accelerated annual sedimentation. Therefore, this study is directed to assess the erosion risk over the watershed, and to simulate actual annual sediment yield at the dam in order to devise the appropriate conservation practices. Generalized assessment was first conducted over the watershed on the basis of drainage texture, rainfall erosion index (R), and the ratio p2/P. As a result, the watershed is divided into zones of severe, high (gullying), high (overland flow) and low erosion risk. Sediment yield at the dam was evaluated by a simulation model. For model validation the simulation results were compared to the measured values over 12 years period, and a good agreement was obtained in some of the years. The simulation results allow us to assess the application of two practical conservation practices: terracing and plantation of trees. Received: 18 November 1997 · Accepted: 18 May 1998  相似文献   

2.
Jordan is part of the arid and semi-arid region of the Middle East, where water resources are known to be scarce. Thorough planning is inevitable and must be applied wisely, especially as it is known that drought conditions were evidenced for many years in Jordan.Surface water average accounts for 693 MCM/year out of which 359 MCM/year is base flow and 334 MCM/year flood flow. Therefore, management of surface water has been given great attention in Jordan because of the overexploitation of groundwater resources. Hydrological simulation models interfaced with Geographical Information Systems (GIS) were examined in this study. GIS interfaced hydrological models were considered as a major tool for surface water management at a watershed scale because they are capable of presenting the relationship between the spatial and hydrological features of the watershed in an efficient way. This study aimed at exploring the advantages of using GIS-based hydrological models as a water management tool to study the largest river basin in Jordan namely, the Zarqa River basin.In this study, the Spatial Water Budget Model (SWBM) and HEC-HMS / HEC-GeoHMS extension model were used. The models were calibrated and validated based on King Talal Reservoir inflow for a period of eight years. The calibration was performed for the most sensitive parameters. The calibration for the two models was performed for the years 1979, 1980, 1981 and 1982. Satisfactory results were obtained for both models with an R2 of 0.90 and 0.85 for the HEC-HMS and SWBM model, respectively. Validation for the models was performed using the years 1993, 1994, 1995 and 1996, and the results were satisfactory with an R2 of 0.75 and 0.80 for the SWBM and HEC-HMS model, respectively. Models after their calibration and verification can then be used to test scenarios related to climate change and/or land-use change at the watershed scale.  相似文献   

3.
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   

4.
金沙江流域水库拦沙效应   总被引：2，自引：0，他引：2       下载免费PDF全文
袁晶  许全喜 《水科学进展》2018,29(4):482-491
水库拦沙是金沙江下游沙量减小的主要原因,对三峡水库的入库水沙条件产生了重要影响。为了系统掌握金沙江流域水库拦沙情况,基于1956年以来流域内水库及实测水沙资料,采用经验公式、典型调查以及输沙平衡原理相结合的方法,对近60年不同阶段金沙江中下游的水库拦沙情况以及水库建设对金沙江流域减沙贡献权重进行了定量研究。结果表明:1956-1990年、1991-2005年和2006-2015年水库拦沙对屏山站的减沙权重分别为0.3%、48%和83%,可见水库拦沙作用逐步增强;1956-2015年,金沙江流域水库年均拦沙0.310亿t,其中大型水库拦沙量占总拦沙量的89%,尤其是2011年以来,随着金沙江中下游以及雅砻江梯级水库群的陆续建成,流域内水库群年均拦沙量达1.92亿t,对屏山站同期年均输沙量的减少权重在90%以上。  相似文献   

5.
Typhoons Aere (2004) and Matsa (2005) caused high nephelometric turbidity in the Shihmen reservoir in northern Taiwan, jeopardizing the operation of the reservoir for several days, and ultimately impacting the living conditions and economy of the downstream residents. The torrential rains caused landslides and debris flows in upland areas, and flowed into riverbeds, likely contributing significantly to the suspended sediment yields in the reservoir. This investigation elucidates how upland landslides affect sediment attributes in the reservoir basin. Study methods including field observations, spatial analysis in GIS and aerial photo interpretation are adopted to trace the sediment sources and contributing factors to the landslide. Torrential rains induced landslides and debris-flows upland, causing river incisions and soil erosion in landslide areas lacking vegetation. These factors, together with the conditions of the engineered structures and geologic vulnerabilities of the area, caused suspended sediment yield in the reservoir. The high nephelometric turbidity could potentially reoccur, with masses of landslide-derived sediment remaining upland and in the riverbed.  相似文献   

6.
The rainfall events that occurred in the Cubat?o do Norte River watershed, Santa Catarina State, Brazil, in 2008, were characterized by both high intensities and amounts and triggered landslides in this watershed. The objective of the present study was to analyze the influence of landslides on the turbidity and the total solid concentration (TS) in this river using turbidity, TS, and river discharge data obtained from March 23, 2008, to June 11, 2010. The comparison between turbidity and discharge patterns implies that the landslide process was not continuous and increased the turbidity intermittently and irregularly. The sediment yield during the landslide occurrence was approximately five times higher than without the landslide, even though the discharges were similar. The turbidity/discharge relationship during the landslide occurrence was markedly different from that before and after the occurrence. The correlation coefficients between turbidity and TS showed that the landslide significantly changed the sediment yield in this watershed. The result indicates that sediment yield estimations at the watershed level should be treated more carefully when landslides occur.  相似文献   

7.
流域产沙模型的研究   总被引：17，自引：1，他引：17       下载免费PDF全文
由坡面泥沙颗粒的动力平衡条件,推导出坡面上细颗粒泥沙的起动切应力,由坡面径流的剩余输沙能力,导得坡面径流的侵蚀量计算公式,与文献[4]的雨滴溅蚀量计算公式一起,构成了概念清楚、过程明确、结构完整的流域产沙模型。产沙量取决于水流挟沙能力与可供沙量的对比关系,若水流挟沙能力小于供沙量,则产沙量等于水流挟沙能力;反之,水流将进一步冲刷表土,形成径流侵蚀,产沙量就等于供沙量与径流侵蚀量之和。据此,可计算出坡面和流域产沙量。模型在岔巴沟流域上应用,结果令人满意。  相似文献   

8.
In this study, we developed a physiographic soil erosion–deposition model to simulate sediment yield from a watershed into Agongdian reservoir and sediment flushing to estimate the efficiency of empty flushing. The model was verified using data related to Typhoons Morakot and Fanapi. Thereafter, we calculated the sediment flushing efficiency of empty storage under the conditions of 1- and 2-day storms with seven return periods. The simulated results revealed that the amount of sediment yield from Joushui River watershed was approximately 70% on average, whereas that from Wanglai River watershed was approximately 30%. These results are consistent with those of a government research report, which suggested that the sediment yield figures from Joushui and Wanglai River watersheds were 72 and 28%, respectively. Furthermore, the efficiency of empty flushing was more than 55% when using the shaft spillway pipe, suggesting that the model can be applied to estimate sediment yield and flushing efficiency.  相似文献   

9.
Data on temperature, major constituents and some trace elements, measured in the dissolved and particulate phases, were used to identify the hydrodynamics of a reservoir (the Bicaz reservoir, Romania). Results revealed that the reservoir experiences two thermal stratifications per year (summer and winter). However, the summer stratification is delayed by the high river inflow of June–July. Two layers were identified, a surface and a deep layer, whose location and impact vary with time. The surface layer originates from the river inflow (intrusion layer) and the deep current is produced by the outflow (velocity current). According to season, the river inflow either supplies the deep current or remains recordable up to the dam. Consequently, the structure of the water column, and thus the biogeochemical processes within it, are governed both by thermal stratification and by these layers.  相似文献   

10.
The objective of this study was to assess the lake sediment budget of land use changes using the Universal Soil Loss Equation (USLE), sediment delivery ratio (SDR), and trap efficiency (TE). The geographic information system was combined with the USLE to estimate the soil erosion of the Lake Asan watershed. Spatial data for each of the USLE factors were obtained from the land use, soil, and 1/25,000 scale digital contour maps. Landsat-5 TM images were selected for analyzing soil erosion changes due to land use changes. The sediment yield to Lake Asan was estimated using the SDR and TE. The estimated sediment budget was compared with observed data from the Lake Asan watershed between 1974 and 2003. The total estimated annual mean sediment budgets from Lake Asan in 1986, 1992, and 2000 were 0.267, 0.301, and 0.339 × 106 ton, respectively, with an average of 0.302 × 106 ton. The average measured sediment budget was 3.15 × 106 ton year?1. The average estimated value shows reasonable agreement with the observed sediment balance. The average estimated and measured sediment budgets contain uncertainties due to both the methods and the approach used by the observers. The simulated results indicated that soil erosion in the Lake Asan watershed increased at a rate of approximately 2 % per year from 1986 to 2000 due to land use change. This study may be useful for managers to identify reservoir rehabilitation management methods for stable irrigation water supply.  相似文献   

11.
Understanding the sediment source is very significant for erosion control in small watersheds. On the Loess Plateau of China, over 110 thousands of check dams were constructed in the past 60 years, which played an important role in controlling soil loss and also kept much information of erosion and sediment yield in the past. The objective of this investigation is to identify the sediment source by the 137Cs tracing method in a small watershed in the Loess Hilly Region of China. Fifty-five sampling sites were selected from the watershed (44 from the inter-gully area, 7 from the gully sides and 4 from the reference sites), and a total of 114 soil samples were collected from three sediment profile cores at the Sidizui watershed check dam constructed in 1959. Based on the erosion rate from the inter-gully area by the 137Cs models, and the total erosion amount deposited in the check dam since 1963, the relative contributions of sediment from the inter-gully area and gully area were estimated during 1963–2013. By comparing the difference of 137Cs activities of surface soils from the check dam (deposited in the 2011–2013 flood events), the inter-gully and gully areas, the relative contributions of sediment derived from the two source areas to the flood sediment during recent years (2011–2013) were estimated by a simple mixing model. Results showed that the erosion rate from the inter-gully area was about 3054 t/km2 a during 1963–2013, and the relative contributions of sediment from the inter-gully area and gully area were estimated to be 27 and 73%, respectively. The sediment from the inter-gully area was about 20% of the total sediment yield amount to the 2011–2013 floods, and from the gully area it was about 80%. The relative contribution of sediment from the inter-gully or gully area was not a fixed value in the watershed. Both of the inter-gully erosion and gully erosion should be simultaneously controlled, and more erosion control measures on the gully area should be taken in the subsequent watershed management in order to reduce the erosion amount in this region.  相似文献   

12.
水库溯源冲刷试验是评估在水库速降水位过程中,结合工程控制条件、水沙条件、冲刷时机和初始水库蓄水条件等因素,研究支流拦门沙坎破坏程度对干流溯源冲刷的影响。采用按照水库高含沙模型相似律建立的小浪底水库实体模型开展了4个组次的水库降水库区发生溯源冲刷的试验,第1~4组次库容恢复率依次为11.6%、6.8%、12.2%和6.6%。拦门沙坎破坏越严重,水量越大,库区溯源冲刷量越大,库容恢复率大;侵蚀基准面越低,库区溯源冲刷量大,库容恢复率大;库区淤积量42.00亿m3时采用降低水位引起库区发生溯源冲刷优于库区淤积量32.00亿m3。对原有的陕西水利科学研究所与清华大学的逐日溯源冲刷公式在考虑支流促因的基础上进行了改进,说明支流蓄水量进入干流越多,引起支流口以下的干流河段冲刷量越大,其计算结果与实测值满足生产实践精度,可作为多沙河流水库调水调沙方案制定参考。  相似文献   

13.
In Jakarta, climate change has been detected through rising air temperatures, increased intensity of rainfall in the wet season, and sea level rise. The coupling of such changes with local anthropogenic driven modifications in the environmental setting could contribute to an increased probability of flooding, due to increase in both extreme river discharge and sedimentation (as a result of erosion in the watersheds above Jakarta and as indicated by sediment yield in the downstream area). In order to respond to the observed and projected changes in river discharge and sediment yield, and their secondary impacts, adaptation strategies are required. A possible adaptation strategy is through policy making in the field of spatial planning. For example, in Indonesia, presidential regulation number 54 year 2008 (Peraturan Presiden Nomor 54 Tahun 2008—Perpres 54/2008) was issued as a reference for the implementation of water and soil conservation. This paper assesses the impact of climate and land cover change on river discharge and sediment yield, as well as the effects of Perpres 54/2008 on that river discharge and sediment yield. The spatial water balance model Spatial Tools for River Basins and Environmental and Analysis of Management Option was used for the runoff computations, whilst the Spatial Decision Assistance of Watershed Sedimentation model was used to simulate erosion, Sediment Delivery Ratio, and sediment yield. The computation period is from January 1901 to December 2005, at the scale of the following watersheds: Ciujung, Cisadane, Ciliwung, and Citarum. During the twentieth century, computed average discharge in the downstream area (near Jakarta) increased between 2.5 and 35 m3/s/month, and sediment yield increased between 1 × 103 and 42 × 103 tons/year. These changes were caused by changes in both land cover and climate, with the former playing a stronger role. Based on a computation under a theoretical full implementation of the spatial plan proposed by Perpres 54/2008, river discharge would decrease by up to 5 % in the Ciliwung watershed and 26 % in the Cisadane watershed. The implementation of Perpres 54/2008 could also decrease the sediment yield, by up to 61 and 22 % in the Ciliwung and Cisadane watersheds, respectively. These findings show that the implementation of the spatial plan of Perpres 54/2008 could significantly improve watershed response to runoff and erosion. This study may serve as a tool for assessing the reduction in climate change impacts and evaluating the role of spatial planning for adaptation strategies.  相似文献   

14.
胡兴林 《冰川冻土》2001,23(1):57-62
Tank模型（又称为水箱模型），是一种用于流域径流预报的确定性水文模型，根据龙羊峡水库入库主要产流区－－黄河上游唐乃亥水文站以上流域下垫面条件下产汇流特性，将其概化为以降雨量为输入，径流量为输出的单孔出流的线性水箱，工用于该水库汛期旬平均入库流量的预报，经对历史资料进行拟合和试验预报的 结果表明，该模型具有较高的预报精度，现已应用于黄河上游龙羊峡水库汛期旬平均入库来水量的中期预报中，取得了十分显著的经济效益。  相似文献   

15.
基于1956-2015年洞庭湖主要控制站实测水文数据,运用Mann-Kendall检验法、主成分分析法对比分析了近60 a来洞庭湖东、南、西三个湖区水位演变特征及其影响因素。结果表明：从调弦口堵口至葛洲坝截流后,南咀和城陵矶站同流量下水位均升高,但南咀站平均水位受三口分流能力减弱而下降（0.03 m）,城陵矶站平均水位受湖盆泥沙淤积和长江干流顶托作用而上升（1.33 m）;三峡水库运行后,湖盆冲淤基本持平,湖泊同流量下水位基本不变,由于该时段长江流域整体为相对枯水期,因而与葛洲坝截流后相比湖泊年平均水位下降约0.31~0.58 m。近60 a来南咀站平均水位呈显著下降趋势（p<0.05）,而城陵矶站水位呈显著上升趋势（p<0.01）,说明湖泊水位影响因素作用存在空间异质性。洞庭湖年内水位存在涨（4-5月）~丰（6-9月）~退（10-11月）~枯（12月-次年3月）的变化特征,葛洲坝运行期丰水期水位上涨明显,三峡运行期各月水位均有下降,受水库调度方式影响7-10月水位降幅最大。洞庭湖流域降水量、四水入湖和出湖径流大小以及长江干流水情是洞庭湖水位变化的主要影响因素,三口来沙变异条件下的洞庭湖冲淤量变化是湖泊水位变化的次要因素。  相似文献   

16.
堆积层滑坡是库区常见的滑坡类型之一,而地形坡度是滑坡发育的重要内因,研究地形坡度与堆积层滑坡发生概率之间的关系对水库型堆积层滑坡的危险性评价具有重要意义。以三峡库区及丹江口库区的139处堆积层滑坡为例,首先,将滑坡地形坡度以每隔5划分为一个区间,总共分为7个区间; 在此基础上,采用贡献率方法,定量研究了地形坡度分别对滑坡数量、面积、体积的贡献率; 最后,通过迭加统计,得到了不同坡度区间对滑坡发生的综合贡献率。结果表明, 15～25的地形坡度对水库型堆积层滑坡的贡献率最高, 10～15及25～30的地形坡度对水库型堆积层滑坡的贡献率中等,小于10及大于30的地形坡度对水库型堆积层滑坡的贡献率最小。研究结果可为具有类似地质背景的水库型堆积层滑坡危险性评估及防治规划提供参考依据。  相似文献   

17.
Nitrogen and phosphorus are the major nutrients to cause eutrophication to degrade water quality of the Miyun Reservoir,a very important drinking water source of Bijing,China,and they are mainly from non-point sources.The watershed in Miyun County was selected as the study region with a totoal area of 1400km^2.Four typical monitoring catchments and two experimental units were used to monitor the precipitation,runoff,sediment yield and pollutant loading related to various land uses in the meantime.The results show that the total nutrient loss amounts of TN and TP are 898.07t/a,and 40.70t/a,respectively,in which nutrients N and P carried by runoff are 91.3% and 77.3%,respectively.There is relatively heavier soil eroson in the northern mountain area whereas the main nutrient loss occurs near the northeast edge of the reservoir.Different land uses would influence the loss amounts of non-point source pollutants.The amount of nutrient loss from the agricultural land per unit is highest,that from forestry comes next that from grassland is lowest.However,due to the variability of land use areas,agricultural land contributes a lot to TP and forestry lands to TN.  相似文献   

18.
This study presents an application of the model Soil and Water Assessment Tool (SWAT) to simulate daily and monthly water flow and sediment fluxes in the Wadi Hatab watershed (2200 km2) located in central Tunisia. The study basin is characterized by a significant climatic contrast, abrupt topography, and soil fragility, resulting thereby in flash floods and important water erosion rates. This alarming situation requires urgent interventions in order to preserve water and soil resources, implying the need for a decision tool for proper integrated management of the watershed. The model was calibrated and validated based on a comparison of simulated and observed flow rates at the basin outlet (hydrometric station Khanguet Zazia), during the periods 1987–1988 and 1989–1990, respectively. The comparison was based not only on visual inspection of the agreement between observed and simulated time series, but also on statistical parameters. Indeed, for the daily time step application, the Nash—Sutcliffe efficiency (NSE) values were 0.52 and 0.61, and the coefficient of determination (R2) was 0.54 and 0.61 for calibration and validation, respectively. As for the monthly time-step application, the obtained NSE values were 0.67 and 0.89 while R2 values were 0.83 and 0.87 for calibration and validation, respectively. This clearly shows the reasonably good agreement between simulated and observed flow rates. In terms of erosion, the model gave sediment yield values ??of 1.15 and 5.37 t/ha/year during the periods of calibration and validation, respectively.  相似文献   

19.
Landslides in Jordan have caused numerous problems during the past 40 years. The most critical slides occurred during the period of 1991/1992 after exceptional heavy rain and snowfall. Many disastrous landslides occurred along the newly reconstructed international highway that links Amman, Jerash and Irbid. Causes for these slides are attributed mainly to the lack of a comprehensive overview and geotechnical understanding of the problem.Many investigators have been interested in this problem of finding an adequate solution to such landslides in Jordan either by using theoretical analysis or by using computer software to solve the slope instability problems. A detailed study was conducted at the Jordan University of Science and Technology to investigate the potential causes and measures for this problem. Seven landslides along the mountainous section of this international highway were reviewed. One of these landslides was thoroughly investigated using a three-dimensional computer program called JUST-SLOPE introduced at the Jordan University of Science and Technology campus. Results of this study indicate that landslides at this site could have been predicted had this technique been applied prior to the occurrence of this slide.  相似文献   

20.
改进密云水库汛期调度方案的途径   总被引：2，自引：0，他引：2  
廖松 《水文》1996,(1):10-15
密云水库是华北最大的水库，确定密云水库汛期调度方案的原则是２０年前制定的，按现代观点看来，其设计防洪库容过大，因而降低了密云水库的蓄水能力。在深入分析潮白河水文特征的基础上，并考虑新建３个水库对下游汉域洪峰流量的影响，提出了几个新的方案，每一个新的方案，每一个建议的方案都能显著提高密云水库的效益。  相似文献   

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