Impacts of water surface area of watershed on design flood简

In order to analyze the impact of the water surface area of a watershed on the design flood, the watershed was classified into a land watershed and a water surface watershed for flood flow calculation at the same time interval. Then, the design flood of the whole watershed was obtained by adding the two flood flows together. Using this method, we calculated design floods with different water surface areas of three reservoirs and analyzed the impact of water surface area on the flood volume and peak flow. The results indicate that larger water surface areas lead to greater impacts on the flood volume and peak flow. For the same watershed area, the impact of water surface area on the flood volume and peak flow is positively proportional to the flood frequency, i.e., the higher the frequency, the greater the impact becomes.     

Risk analysis for earth dam overtopping

In this paper, a model of overtopping risk under the joint effects of floods and wind waves, which is based on risk analysis theory and takes into account the uncertainties of floods, wind waves, reservoir capacity and discharge capacity of the spillway, is proposed and applied to the Chengbihe Reservoir in Baise City in Guangxi Zhuang Autonomous Region. The simulated results indicate that the flood control limiting level can be raised by 0.40 m under the condition that the reservoir overtopping risk is controlled within a mean variance of 5×10-6. As a result, the reservoir storage will increase to 16 million m3 and electrical energy generation and other functions of the reservoir will also increase greatly.     

KALMAN FILTERING CORRECTION IN REAL-TIME FORECASTING WITH HYDRODYNAMIC MODEL

Accurate and reliable flood forecast is crucial for efficient real-time river management, including flood control, flood warning, reservoir operation and river regulation. In order to improve the estimate of the initial state of the forecasting system and to reduce the errors in the forecast period a data assimilation procedure was often need. The Kalman filter was proven to be an efficient method to adjust real-time flood series and improve the initial conditions before the forecast. A new model integrating the hydraulic model with the Kalman filter for real-time correction of flood forecast was developed and applied in the Three Gorges interzone of the Yangtze River. The method was calibrated and verified against the observed flood stage and discharge during Three Gorges Dam construction periods （2004）. The results demonstrate that the new model incorporates an accurate and fast updating technique can improve the reliability of the flood forecast.     

Real-time flood forecasting of Huai River with flood diversion and retarding areas

A combination of the rainfall-runoff module of the Xin’anjiang model, the Muskingum routing method, the water stage simulating hydrologic method, the diffusion wave nonlinear water stage method, and the real-time error correction method is applied to the real-time flood forecasting and regulation of the Huai River with flood diversion and retarding areas. The Xin’anjiang model is used to forecast the flood discharge hydrograph of the upstream and tributary. The flood routing of the main channel and flood diversion areas is based on the Muskingum method. The water stage of the downstream boundary condition is calculated with the water stage simulating hydrologic method and the water stages of each cross section are calculated from downstream to upstream with the diffusion wave nonlinear water stage method. The input flood discharge hydrograph from the main channel to the flood diversion area is estimated with the fixed split ratio of the main channel discharge. The flood flow inside the flood retarding area is calculated as a reservoir with the water balance method. The faded-memory forgetting factor least square of error series is used as the real-time error correction method for forecasting discharge and water stage. As an example, the combined models were applied to flood forecasting and regulation of the upper reaches of the Huai River above Lutaizi during the 2007 flood season. The forecast achieves a high accuracy and the results show that the combined models provide a scientific way of flood forecasting and regulation for a complex watershed with flood diversion and retarding areas.     

Rainfall-runoff simulation and flood forecasting for Huaihe Basin

The main purpose of this study was to forecast the inflow to Hongze Lake using the Xin＇anjiang rainfall-runoff model. The upper area of Hongze Lake in the Huaihe Basin was divided into 23 sub-basins, including the surface of Hongze Lake. The influence of reservoirs and gates on flood forecasting was considered in a practical and simple way. With a one-day time step, the linear and non-linear Muskingum method was used for channel flood routing, and the least-square regression model was used for real-time correction in flood forecasting. Representative historical data were collected for the model calibration. The hydrological model parameters for each sub-basin were calibrated individually, so the parameters of the Xin＇anjiang model were different for different sub-basins. This flood forecasting system was used in the real-time simulation of the large flood in 2005 and the results are satisfactory when compared with measured data from the flood.     

REAL-TIME FLOOD FORECASTING METHOD WITH 1-D UNSTEADY FLOW MODEL

A real-time forecasting method coupled with the 1-D unsteady flow model with the recursive least-square method was developed. The 1-D unsteady flow model was modified by using the time-variant parameter and revising it dynamically through introducing a variable weighted forgetting factor,such that the output of the model could be adjusted for the real time forecasting of floods. The application of the new real time forecasting model in the reach from Yichang to Luoshan of the Yangtze River was demonstrated. Computational result shows that the forecasting accuracy of the new model is much higher than that of the original 1-D unsteady flow model. The method developed is effective for flood forecasting,and can be used for practical operation in the flood forecasting.     

Reservoir operation schemes for water pollution accidents in Yangtze River

After the Three Gorges Reservoir starts running, it can not only take into consideration the interest of departments such as flood control, power generation, water supply, and shipping, but also reduce or eliminate the adverse effects of pollutants by discharge regulation. The evolution of pollutant plumes under different operation schemes of the Three Gorges Reservoir and three kinds of pollutant discharge types were calculated with the MIKE 21 AD software. The feasibility and effectiveness of the reservoir emergency operation when pollution accidents occur were investigated. The results indicate that the emergency operation produces significant effects on the instantaneous discharge type with lesser effects on the constant discharge type, the impact time is shortened, and the concentration of pollutant is reduced. Meanwhile, the results show that the larger the discharge is and the shorter the operation duration is, the more favorable the result is.     

EXPERIMENTAL INVESTIGATION OF THE FAILURE OF CASCADE LANDSLIDE DAMS

This paper presents results of model tests for the landslide dam failure of a single dam and cascade dams in a sloping channel. The dams were designed to be regular trapezoid with fine sand. A new measuring method named the labeled line locating method was used to digitalize the captured instantaneous pictures. Under two different inflow discharges, the morphological evolution and the flow patterns during one dam failure and the failure of cascade dams were investigated. The results indicate that when the inflow discharge is large, the deformation pattern of the downstream dam is similar to that of the upstream dam, and both dams are characterized with the overtopping scour throughout the dam failure process. When the inflow discharge is small, the upstream dam is scoured mainly through a sluice slot formed by the longitudinal incision, and the downstream dam is characterized with the overtopping scour. The data set presented in this paper can be used for the validation of numerical models and provide a reference for the flood risk management of cascade landslide dams.     

Risk calculation method for complex engineering system

This paper presents a rapid and simple risk calculation method for large and complex engineering systems, the simulated maximum entropy method (SMEM), which is based on integration of the advantages of the Monte Carlo and maximum entropy methods, thus avoiding the shortcoming of the slow convergence rate of the Monte Carlo method in risk calculation. Application of SMEM in the calculation of reservoir flood discharge risk shows that this method can make full use of the known information under the same conditions and obtain the corresponding probability distribution and the risk value. It not only greatly improves the speed, compared with the Monte Carlo method, but also provides a new approach for the risk calculation in large and complex engineering systems.     

2-D NUMERICAL SIMULATION OF FLOODING EFFECTS CAUSED BY SOUTH-TO-NORTH WATER TRANSFER PROJECT

Since the General Channel designed for the South-to-North Water Transfer Project in China has to cross many rivers and streams flowing from west to east, there are potentially serious effects additional flooding on the western side of the project alignment. Therefore, a 2-D numerical model for forecasting basin flood disasters was established and verified using historical flood data. The model was applied to researching the interaction between the proposed Project and flooding events for 5 streams in the Anyang River reach as a representative case study. Simulated results indicate that the model could correctly forecast the flood, submerged area and depths, and water surface elevations along the left side of the channel. The discharge capacity and location of hydraulic structures in the transfer canal alignment were analyzed. Then adjustments to the dimensions and positioning of proposed hydraulic structures were recommended at intersections, especially the addition of a channel to transfer flood water from one stream to another, which can effectively limit the sluice and protect the Anyang City from flooding.     

大型水库群对流域洪水过程影响分析

以淮河流域鲁台子上游大型水库群为例,比较水库修建前后下游断面洪水过程变化情况,分析水库群对洪水过程的总影响,提出逐库添加法划分各水库在洪水过程变化中的贡献,明确各水库的影响程度,采用分级聚类法对水库影响程度进行划分,甑别重要水库。结果显示淮河流域大型水库群显著削减了鲁台子断面洪水总量与洪峰流量,峰现时间也有所变化,各库贡献差异较大,其中梅山、响洪甸、宿鸭湖、南湾、鲇鱼山和佛子岭等6座水库对鲁台子断面洪水过程影响显著,是流域防洪调度的重点水库。     

淮河上游水库群防洪联合调度效果及潜力分析

水库群防洪联合调度效果与潜力分析,对进一步提高水库群防洪效益具有参考价值。以淮河王家坝以上防洪系统为研究对象,以9场历史实测大洪水为样本,采用控制断面的洪防洪效果指数、综合防洪效果指数、极限潜力、优化潜力和综合潜力指数等作为水库群防洪联合调度的效果和潜力评价指标,王家坝以上水库群在现行的防洪调度水平下,对下游班台、息县和王家坝防洪控制断面防洪效果显著,各水库仍具有不同程度的防洪潜力,进一步研究水库群防洪联合调度具有实际意义。     

南水北调中线工程交叉河流白河设计洪水计算

南水北调中线工程白河交叉断面以上控制流域面积３５９４．６ｋｍ＾２。控制干流河长１１５ｋｍ面上游有相关联的大中型水库３座，设计条件复杂，水文资源匮乏，交叉断面设计洪水计算在南水北调总干渠沿线交叉流中极具典型性。     

临淮岗洪水控制工程淮河截流的建设管理

临淮岗洪水控制工程是国家"十五"重点项目,淮河截流是工程建设的里程碑.为贯彻国务院加快治淮工程建设的重大决定,临淮岗工程需全面加快建设,提前1 a实施截流.淮委临淮岗工程建设管理局认真分析研究淮河截流的特点和面临的诸多不利因素,合理确定截流工程的项目管理模式,科学制订导流、截流方案,精心组织、科学调度、果断决策,与各参建单位齐心协力、克服困难,成功截流.     

基于HEC-RAS的淮河淮南段洪水漫顶风险分析

淮河淮南段聚集了大量的人口、工厂、农田、建筑物等,一旦发生较大规模的洪水,将对人民生命财产安全造成严重威胁。运用HEC-RAS软件和HEC-GeoRAS模块,在GIS环境中,模拟现有防洪工程条件下淮河淮南段在40年、60年及100年一遇洪水周期下的洪水漫顶淹没情况,得到不同横断面的设计水位线、漫顶淹没的范围、淹没水深等...     

浚深新沂河使其成为淮沂沭泗下游合流排洪入海主河道的规划设想

针对淮河和沂沭泗下游排洪工程系统由于历史原因使治水缺少长远规划,防洪形势严峻,出现"中洪水大灾害"的反常现象这一状况,提出浚深新沂河,使其成为淮沂沭泗下游合流排洪入海主河道的规划设想,以替代淮河入海水道二期和新沂河续建工程.初步估计该规划设想工程可节省投资40余亿元,并可望从根本上治理淮河下游的洪涝灾害.     

黄浦江上海市区段防汛墙漫溢风险分析

为明确黄浦江上海市区段防汛墙防御能力,采用2012年防汛墙高程监测数据以及黄浦江防汛墙设计参数,利用蒙特卡罗法计算不同潮位下防汛墙漫溢概率以及远期海平面上升情况下的漫溢概率,提出防汛墙漫溢风险评价准则,并统计相应的漫溢风险。结果表明:现状防汛墙防御能力明显不足,如果再考虑到近年来黄浦江水位趋势性抬高及未来海平面上升,黄浦江防汛形势不容乐观;漫溢高风险区主要集中在市区段上游;黄浦江防汛墙漫溢风险不仅与防汛墙高程欠缺有关,也与不同岸段采用的设计潮位有关。     

三里坪水利枢纽工程设计洪水复核分析

南河流域洪水特性受台风雨影响,表现为洪高量大,汇流快。为了对三里坪枢纽工程验收提供设计洪水复核成果,通过对坝址附近控制站—台口（二）水文站多年实测资料分析,并进行历史洪水调查,结合历史洪水与实测洪水组成不连续系列进行频率分析,得出坝址设计洪水成果,对原有初步设计成果加以复核。复核结论认为,依据台口（二） 站计算的设计洪水成果可作为三里坪水库的设计依据。其分析计算方法可供类似工程区域设计洪水计算参考。     

漫坝风险分析在水库防洪中的应用

综合应用随机水文学、随机水力等等学科知识，全面考虑洪水、风浪、库容和泄水能力的不确定性、建立了土坝对抗洪水和风浪联合作用下的漫坝风险理论，并提出了风险取值标准。此法是防洪减灾的一种辅助策略。可在坝体坚固、管理人员素质较高的大型水库推广应用。综合     

王临段治理对淮干王家坝站行洪能力影响分析

淮河中游王家坝至临淮岗河段行洪不畅,无法满足设计泄洪能力要求,2020年淮河干流王临段治理工程全面开工建设。为评价现阶段淮河干流王临段治理工程对王家坝站行洪能力的影响,结合治理工程前后洪水实测资料,运用水文学方法,从河道过水断面、水位-流量关系以及洪量和洪峰比值三个方面进行了分析。结果表明：治理后濛河分洪道分洪过水能力增大,在一定程度上消减了淮河干流王家坝断面的洪量和洪峰流量,提高了淮干王家坝断面的行洪能力。