中国的水库泥沙淤积问题

由于我国有许多河流是含沙最高、输沙量大的多泥沙河流,水库泥沙淤积问题异常严重．主要表现在：淤积数量大,淤积速率快．据统计,截止到1981年底全国水库总淤积量达115×10~8m~3．占统计水库总库容的14．2％．年平均库容损失率达2．3％,高于世界各国．水库的严重淤积,不仅影响水库兴利效益的发挥,严重威胁水库的使用寿命,而且还造成一系列在进行水库规划时未曾充分估计到的环境问题．本文重点从河流水文泥沙特性、我国水库淤积问题的严重性、水库淤积引起的问题及水库防淤减淤措施等4个方面作一较全面的分析和探讨．     

Sediment settling in the Latian Dam in Iran

Among the difficulties that influence future dam operations,reservoir sedimentation is the most problematic for engineers.This study predicted the amount and pattern of sedimentation for use in estimation of the useful lifespan of reservoirs and identification of optimal locations for outlets and intakes at the initial stages of dam design.Hydrographic surveys of different dams can provide better insight into this phenomenon.Latian Dam in Iran has conducted hydrographic surveys during 7 time periods.The amount and process of sedimentation in this reservoir were determined,and predictions of distribution of sediments were validated by well-known,common methods.The formation of a delta in the reservoir was investigated for different time periods after operation.Future problems due to the impacts of sedimentation on dam operation and the useful lifespan of the reservoir were predicted.In addition,the study results may be used for developing empirical methods to predict sedimentation patterns in other reservoirs.     

Numerical simulation of sedimentation process in reservoirs and development of a non-coupled algorithm to improve long-term modeling

This paper investigates the validity of a quasi-steady approximation for sediment transport and presents a new algorithm based on this concept. The developed non-coupled algorithm interacts among hydrodynamic, sediment, and morphology modules which are based on depth-averaged Navier-Stokes equations for the flow, the three-dimensional equation of conservation of sediment, and the mass balance between the bed and sediment (Exner equation) to simulate the reservoir sedimentation process. The non-coupled algorithm solves both the short-term scale and the relatively long-term scale problems of reservoir sedimentation. The proposed algorithm is verified using field data and by comparison with other accurate algorithms. Based upon the results of this investigation, the developed algorithm can be used to simulate long-term reservoir sedimentation while considerably decreasing the computational costs and preserving computational accuracy. The computational cost of the non-coupled algorithm is about 97% less than the conventional semi-coupled approach whereas the errors (Root Mean Square Error, Average Relative Error, and Maximum Relative Error of bed level) of the developed algorithm are approximately 15% greater than those for the semi-coupled algorithm for the average value.     

Re-Look to Conventional Techniques for Trapping Efficiency Estimation of a Reservoir

All reservoirs are subjected to sediment inflow and deposition up to a certain extent leading to reduction in their capacity. Thus, the important practical problem related to the life of reservoir is the estimation of sedimentation quantity in the reservoirs. Large number of methods and models are available for estimation of reservoir sedimentation process. However, each model differs greatly in terms of their complexity, inputs and other requirements. In the simplest way, the fraction of sediment deposit in the reservoir can be determined through the knowledge of its trap efficiency. Trap efficiency （Te） is the proportion of the incoming sediment that is deposited or trapped in a reservoir. Most of the Te estimation methods define a relationship of the T, of the reservoir to their capacity and annual inflow, generally through curves. In this study, the empirical relationships given by Brune and Brown were used and compared for estimating the trap efficiency of Gobindsagar Reservoir （Bhakra Dam） on Satluj River in Bilaspur district of Himachal Pradesh, in the Himalayan region of India. A new set of regression equations has been developed for Brune＇s method and compared with Brown and other available Brune＇s equations. It has been found that Brune＇s equations developed in the present study estimated better than the other Brune＇s equations reported in literature. Later, in the present study it was found that Brown＇s approach was over estimating the T,. Hence it was again modified for Gobindsagar reservoir. It was also identified that sediments coming to this particular reservoir were mainly of coarse nature.     

莫西庄地区三工河组二段储层特征评价

三工河组二段砂体为莫西庄地区的主要含油储层,分布相对较稳定.三工河组二段含油砂体分为三工河组二段一砂体和三工河组二段一砂体两套砂体,分布稳定.文章通过分析沉积特征、物性特征、孔隙类型和孔喉特征,对这两套含油储层进行了系统的评价,认为J1s12含油储层属中—差型储层,J1s12含油储层为中等储层.在综合评价的基础上,通过地震反演,预测了莫西庄地区主力含油砂体厚度的分布.     

Optimization of operation rule curves and flushing schedule in a reservoir

Flushing sediment through a reservoir has been practiced successfully and found to be inexpensive in many cases. However, the great amount of water consumed in the flushing operation might affect the water supply. To satisfy the water demand and water consumed in the flushing operation, two models combining the reservoir simulation model and the sediment flushing model are established. In the reservoir simulation model, the genetic algorithm (GA) is used to optimize and determine the flushing operation rule curves. The sediment‐flushing model is developed to estimate the amount of the flushed sediment volume, and the simulated results update the elevation‐storage curve, which can be taken into account in the reservoir simulation model. The models are successfully applied to the Tapu reservoir, which has faced serious sedimentation problems. Based on 36 years historical sequential data, the results show that (i) the simulated flushing operation rule curves model has superior performance, in terms of lower shortage index (SI) and higher flushing efficiency (FE), than that by the original reservoir operation; (ii) the rational and riskless flushing schedule for the Tapu reservoir is suggested to be set within an interval of every 2 or 4 years in the months of May or June. Copyright © 2003 John Wiley & Sons, Ltd.     

水库区地壳稳定性与地震预测研究的途径和方法

随着经验的积累和科学技术的不断进步,水库地震预测的研究从以往的“现象描述－定性评价”逐渐进入“模式机制研究－定量评价”阶段。其重点是深入研究库区各种新构造运动的现象;地壳运动方式所决定的形变场与应力场和水载荷的作用等。具体作法较多,本文仅就水库区地质环境、水库规模、蓄水位、孔隙压和地形变与地震关系进行讨论。后两种方法是作者近期承担湖北省科委下达的有关课题研究时完成的。这些方法虽出于对水库区不同因素     

A REVIEW OF RESERVOIR DESILTATION

I INTRODUCTIONThe number of dam constructions has increased during the last decades, pafticularly in the tropics andsemi-arid areas where high sediment yields are prominent, and therefore also the problems of reservoirsedimentation. In 1900 there were 42 large dams, i.e. higher than 15 m, while in 1950 and 1986 therewere 5,268 and about 39,000 respectively (ICOLD, 1988). In the period 1975 to 1990, the regions withthe largest increase of large dams were Central and South America, Asia …     

Influences of retrogressive erosion of reservoir on sedimentation of its downstream river channel——A case study on Sanmenxia Reservoir and the Lower Yellow River

Retrogressive erosion, a widespread phenomenon of sediment transport in reservoirs, often impacts on both the reservoir capacity and the sedimentation in the downstream river channel. Based on field data from the Sanmenxia Reservoir and the Lower Yellow River over the past decades, three courses of ret-rogressive erosion with distinctive features were analyzed. The results indicate that retrogressive erosion, especially caused by rapid reduction in the water level till the reservoir is empty, often results in the serious siltation of the lower Yellow River and threatens the safety of the flood control in the Lower Yellow River. Unreasonable operation of the reservoir and incoming hyperconcentrated floods accom-panied by retrogressive erosion also aggravate the siltation of the main channel of the river. However, a reasonable operation mode of the reservoir so named"storing the clear (low sediment concentration) water in the non–flood season, and sluicing the muddy(high sediment concentration) water in the flood season" was found, which might mitigate the deposition in both the reservoir and the Lower Yellow River. This operation mode provides important experience for the design and operation of large reser-voirs in other large rivers carrying huge amounts of sediment.     

Optimization and simulation of reservoir operation with sediment evacuation: a case study of the Tarbela Dam,Pakistan

Many reservoirs around the world are being operated based on rule curves developed without considering the evacuation of deposited sediment. Current reservoir simulation and optimization models fall short of incorporating the concept of sustainability because the reservoir storage losses due to sedimentation are not considered. This study develops a new model called Reservoir Optimization‐Simulation with Sediment Evacuation (ROSSE) model. The model utilizes genetic algorithm based optimization capabilities and embeds the sediment evacuation module into the simulation module. The sediment evacuation module is implemented using the Tsinghua university flushing equation. The ROSSE model is applied to optimize the rule curves of Tarbela Reservoir, the largest reservoir in Pakistan with chronic sedimentation problems. In the present study, rule curves are optimized for maximization of net economic benefits from water released. The water released can be used for irrigation, power production, sediment evacuation, and for flood control purposes. Relative weights are used to combine the benefits from these conflicting water uses. Nine sets of rule curves are compared, namely existing rule curves and proposed rule curves for eight scenarios developed for various policy options. These optimized rule curves show an increase of net individual economic benefits ranging from 9 to 248% over the existing rule curves. The shortage of irrigation supply during the simulation period is reduced by 38% and reservoir sustainability is enhanced by 28% through increased sediment evacuation. The study concludes that by modifying the operating policy and rule curves, it is possible to enhance the reservoir's sustainability and maximize the net economic benefits. The developed methodology and the model can be used for optimization of rule curves of other reservoirs with sedimentation problems. Copyright © 2008 John Wiley & Sons, Ltd.     

A STUDY ON SEDIMENT PROBLEMS IN THE GONGZUI RESERVOIR

IINTRODUCTIONTheannualaverageruff-offinthewatershedoftheGongzuiReservoiris50billioncubicmeterswithanaveragesedimentloadof34.7milliontonsperyear.Finesedimentwithd,,=0'055mmcompose97%oftheiota]sedimentload.Theannualcoarsegravelpericleswithd,,=58.5mmisaboutonemilliontons.TheendofbackWateris38kmawayfromthedam.Thereservoirwasoriginallydesignedtoatotalstoragecapacityof374millioncubicmeters,inwhich102millioncubicmetersisregulationstoragecapacityand243millioncubicmetersis'dead'storagecapacityfo…     

MULTIOBJECTIVE PROGRAMMING MODEL FOR SEDIMENT SLUICING AND POWER GENERATION IN RESERVOIR OPERATION

I. INTRODUCTIONReservoir operation study in planning stage is an important task for the water resourcesdevelopment design. In the past. much attention has been paid to making the most ot' floodcontol. power generation, navigation. and water supply, but less to the unfavorable effectsdue to reservoir sedimentation. According to the survey of 425 reservoirs in Japan with a total storage capacity of 13.2 billion mJ a volume of 825 million m3 of sediment was depositedby the end of 1979. This…     

EXTREME RESERVOIR SEDIMENTATION IN AUSTRALIA:A REVIEW

ＥＸＴＲＥＭＥＲＥＳＥＲＶＯＩＲＳＥＤＩＭＥＮＴＡＴＩＯＮＩＮＡＵＳＴＲＡＬＩＡ：ＡＲＥＶＩＥＷＨｕｂｅｒｔＣＨＡＮＳＯＮ１ＡＢＳＴＲＡＣＴＩｎｔｈｅｐａｐｅｒ,ｔｈｅａｕｔｈｏｒｒｅｖｉｅｗｓｔｈｅｐｒｏｂｌｅｍｏｆｒｅｓｅｒｖｏｉｒｓｉｌｔａｔｉ...     

Assessment of reservoir sedimentation using remote sensing and recommendations for desilting Patratu Reservoir,India

ABSTRACT

This study describes the assessment of reservoir sedimentation of the Patratu Reservoir using Satellite Remote Sensing (SRS). The sedimentation assessment was carried out using satellite data and reservoir water level data from 2006 to 2012. Water spread area was analysed from satellite data. The Normalized Difference Water Index (NDWI) has been used to delineate open water features and to enhance the presence of water surface in satellite imagery of the Patratu Reservoir. Water spread area of the reservoir at a particular elevation on the date of the passing of the satellite was used to develop an elevation-area curve. For the present case, fluctuation of water level was found to vary from 387.096 to 406.152 m. The linear interpolation/extrapolation technique has been employed to assess the water spread area of Patratu Reservoir at different elevations. Further, these areas were used to compute the live storage capacity of the reservoir between two elevations by the Prismoidal formula. From the study, it was found that due to sedimentation, the live storage capacity of Patratu Reservoir has reduced from 101.95 to 89.96 hm³, thus showing capacity loss of 11.76% in a span of 44 years. To increase the live storage capacity of the reservoir it is proposed to adopt manual and mechanical digging combined with flushing for desilting of the deposited sediment.

EDITOR D. Koutsoyiannis ASSOCIATE EDITOR S. Kanae     

SEDIMENTATION STUDY ON PUMPED-STORAGE POWER STATION OF PUSHI RIVER

I.INTRODUCTIONThePtlmped-storagepoll,erprojectofPushiriverisconsistedofupperreservoir,lobal-erreset'oir.watertransmissionSystemandpotvergeneratingsystem.ThelowerreservoirIviththecatchmentbasinareaof1141kmZisthewatersupplierl-c'hichislocatedonthedownstreamofthePushiriverinthesouthernpactofNortheastChina.Theupperreservoirisabout300-400metershigherthanthelowerresen!oirattheleftsideoftheriverwithcatchmentbasinareaof1.12km2.Thecharacteristicsoftheprojectandreservoirareshottviintablel-l.Ino…     

Optimization of the Sefid-Roud Dam desiltation process using a sophisticated one-dimensional numerical model

Although water and soil conservation activities reduce reservoir sedimentation, it is inevitable that reservoirs fed by rivers transporting high amounts of sediment will experience sedimentation. The Ghezel-Ozan and Shah-Roud rivers, which flow to the Sefld-Roud reservoir dam, are both highly sediment-laden and transport significant amounts of sediment in both bed load and suspended load forms to the reservoir. Hence, it seems that the only practical way to remove the sediment from the reservoir is to flush it out using the Chasse method. In the present paper, field measurements of Chasse operation characteristics taken in previous years are presented, and a numerical model that simulates this process is introduced. After calibrating the model using field measured data, the calculated results （for reservoir pressure flushing and released sediment volume） of the numerical model were compared with other measured data for the same Chasse operation and the results agree well. Finally, using the numerical simulation results, the best approaches to ensure highly effective flushing while conserving reservoir water are presented （at least for the Sefid-Roud dam）. The operation of the bottom outlet gates, the shape of the output hydrograph, and the reservoir water level variation during flushing were optimized. In addition, the numerical model and related parameters, which need to be calibrated, are discussed.     

Time-dependent reliability analysis using Bayesian MCMC on the reduction of reservoir storage by sedimentation

Currently, an operational strategy for the maintenance of reservoirs is an important issue because of the reduction of reservoir storage from sedimentation. However, relatively few studies have addressed the reliability analysis including uncertainty on the decrease of the reservoir storage by the sedimentation. Therefore, it is necessary that the reduction of the reservoir storage by the sedimentation should be assessed by a probabilistic viewpoint because the natural uncertainty is embedded in the process of the sedimentation. The objective of this study is to advance the maintenance procedures, especially the assessment of future reservoir storage, using the time-dependent reliability analysis with the Bayesian approach. The stochastic gamma process is applied to estimate the reduction of the Soyang dam reservoir storage in South Korea. In estimating the parameters of the stochastic gamma process, the Bayesian Markov chain Monte Carlo (MCMC) scheme using the informative prior distribution through the empirical Bayes method is applied. The Metropolis–Hastings algorithm is constructed and its convergence is checked by the various diagnostics. The range of the expected life time of the Soyang dam reservoir by the Bayesian MCMC is estimated from 111 to 172 years at a 5 % significance level. Finally, it is suggested that improving the assessment strategy in this study can provide valuable information to the decision makers who are in charge of the maintenance of a reservoir or a dam.     

1999-2015年汛后小浪底水库典型支流口门淤积发展影响分析

支流作为水库综合效益发挥的重要组成部分,其河口泥沙大幅淤积会影响水库综合效益的发挥.选取多沙河流水库黄河小浪底库区畛水、石井两支流作为典型实例,在对1999-2015年汛后水库的来水来沙、水库调度、库区干支流淤积量与形态分析基础上,研究干支流淤积形态的变化,重点研究支流口门拦门沙坎抬升变化特征,结果表明：支流的分流及淤积与入库流量、含沙量及库区的淤积形态有关.入库流量越大,支流分流比小,支流淤积规模小;入库含沙量越大,支流分沙比越大,支流淤积规模越大.     

A one‐dimensional process‐based approach to study reservoir sediment dynamics during management operations

A comprehensive understanding of the dynamics of erosion and sedimentation in reservoirs under different management conditions is required to anticipate sedimentation issues and implement effective sediment management strategies. This paper describes a unique approach combining fluvial geomorphology tools and morphodynamic modeling for analyzing the sediment dynamics of an elongated hydropower reservoir subjected to management operations: the Génissiat Reservoir on the Rhône River. Functional sub‐reaches representative of the reservoir morphodynamics were delineated by adapting natural river segmentation methods to elongated reservoirs. The segmentation revealed the link between the spatial and temporal reservoir changes and the variability of longitudinal flow conditions during reservoir management operations. An innovative modeling strategy, incorporating the reservoir segmentation into two sediment transport codes, was implemented to simulate the dynamics of erosion and sedimentation at the reach scale during historic events. One code used a bedload approach, based on the Exner equation with a transport capacity formula, and the other used a suspended load approach based on the advection–dispersion equation. This strategy provided a fair quantification of the dynamics of erosion and sedimentation at the reach scale during different management operations. This study showed that the reservoir morphodynamics is controlled by bedload transport in upper reaches, graded suspended load transport of sand in middle reaches and suspended load transport of fine sediments in lower reaches. Eventually, it allowed a better understanding of the impact of dam management on sediment dynamics. Copyright © 2017 John Wiley & Sons, Ltd.     

Including daily constraints in a monthly reservoir operation model for low-flow

In many real-world situations, operation of water resources systems are subject to constraints which are formulated on a daily basis. Since mathematical models (simulation or optimization models) are often developed on a monthly basis to avoid dimensionality problems and to reduce necessary computer time, some degree of approximation is necessary. Two examples are presented in order to show how this approximation can be done:

• •- a reservoir is operated for hydroelectric power production and low-flow augmentation is provided on a daily basis as a function of inflows (Lech River System in Germany)
• •- a reservoir is operated optimally for daily low-flow augmentation at a control gage downstream. The model includes also mandatory releases as constraints (Wupper River System in Germany).

In the first example the daily requirements are part of the constraints in the system, while in the second example the daily constraint concerns directly the objective function. Further, in the first case water can be saved and in the second case more water is needed as compared to calculations on a monthly basis.These examples are presented to show two solutions using envelope curves but other possibilities (i.e., regression analysis, constraints, coefficients) could be considered.