JOURNAL OF HYDRAULIC ENGINEERING

Vol . 50 No . 2，2019（Monthly）

CONTENTS

Deformation characteristics and shear strength failure criteria of CC-RCC materials in combined damstructures ………………………………………… LI Mingchao ZHANG Mengxi ZHANG Jinrui（157）Intelligent grouting control method and system for hydropower engineering………………………………

FAN Qixiang HUANG Canxin JIANG Xiaochun WANG Kexiang HUANG Wei YANG Ning（165）Influence of roughness and backwater of bridge piers on flood carrying capacity in a wide-shallow riv⁃er …… WANG Tao GUO Xinlei LI Jiazhen GUO Yongxin ZHOU Zhigang GUO Xiaoming（175）Experimental study on the influence of density and stress level on particle breakage of coral sand …

CAI Zhengyin HOU Heying ZHANG Jinxun ZHANG Fenglin GUAN Yunfei CAO Yongyong（184）Optimality conditions for operating rule of parallel reservoir system Ⅱ. Algorithm design and casestudy ……………………… HU Tiesong ZENG Xiang WANG Jing WANG Xin WANG Qin（193）Water resources comprehensive allocation and simulation model（WAS），part Ⅱ. Application ………

………………………………… SANG Xuefeng ZHAO Yong ZHAI Zhengli CHANG Huanyu（201）Real-time flood control risk estimation of reservoir and analysis on the interoperability of storage ca⁃pacity of multi-reservoir regulation …………………………………………………………………………

DUN Xiaohan ZHOU Jianzhong ZHANG Yongchuan CHEN Lu WANG Quansen DAI Ling（209）Unsteady change of water and sediment processes downstream of cascade reservoirs in the Lower Jin⁃sha River and its influence on navigation conditions ……………………………… CHEN Xujian（218）Influence of water content on dynamic compressive properties of concrete subjected to seismic strainrate…………… WANG Hailong YIN Wenwen CHENG Xudong SHENG Yufei SUN Xiaoyan（225）Entropy production analysis for vortex rope of a turbine model …………………………………………

…………………………… LU Jinling WANG Like LIAO Weili ZHAO Yaping JI Qingfeng（233）Calculation of crop coefficient and evapotranspiration based on temperature effect ……………………

……… WANG Zhenlong GU Nan LÜ Haishen HU Yongsheng ZHU Yonghua YANG Miao（242）Ecological thresholds for the dominated wetland plants of Poyang Lake along the gradient of floodingduration…………………………………………………………………………………………………………

………… HAN Zhen WANG Shiyan LIU Xiaobo PENG Wenqi GE Gang HUANG Aiping（252）Application of overall matrix method in operation stability analysis for frequency regulation mode ofhydropower stations ……………………………………………………………………………………………

… MA Anting YANG Jiandong YANG Weijia TANG Renbo FENG Wentao HOU Liangyu（263）Characteristic analysis and uncertainty assessment of joint distribution of flow and sand in Jinghe Riv⁃er basin ……………………………………………… MA Chuanhui HUANG Qiang GUO Aijun（273）

水 利 学 报SHUILI XUEBAO

第 50卷 2019年 第 2期（月刊）

目 次

［期刊基本参数］CN11 - 1882/TV * 1956 * m * A4 * 128 * zh * P *￥30.00 * 1000 * 14* 2019-02

常态-碾压混凝土联合筑坝材料变形特性与抗剪强度准则研究……… 李明超 张梦溪 张津瑞（157）

水电工程水泥灌浆智能控制方法与系统……………………………………………………………………

…………………………………………… 樊启祥 黄灿新 蒋小春 王克祥 黄 伟 杨 宁（165）

河道糙率和桥墩壅水对宽浅河道行洪能力影响的研究……………………………………………………

…………………………………………… 王 涛 郭新蕾 李甲振 郭永鑫 周志刚 郭晓明（175）

密度与应力水平对珊瑚砂颗粒破碎影响试验研究…………………………………………………………

…………………………………………… 蔡正银 侯贺营 张晋勋 张凤林 关云飞 曹永勇（184）

并联供水水库联合调度规则最优性条件研究Ⅱ：算法开发与实例研究…………………………………

……………………………………………………… 胡铁松 曾 祥 王 敬 王 欣 汪 琴（193）

水资源综合模拟与调配模型WAS（Ⅱ）：应用 ……………… 桑学锋 赵 勇 翟正丽 常奂宇（201）

水库实时防洪风险计算及库群防洪库容分配互用性分析…………………………………………………

…………………………………………… 顿晓晗 周建中 张勇传 陈 璐 王权森 戴 领（209）

金沙江梯级水库下游水沙过程非恒定变化及其对通航条件的影响 ……………………… 陈绪坚（218）

地震应变率下水饱和度对混凝土动力压缩效应的影响……………………………………………………

……………………………………………………… 王海龙 银文文 程旭东 盛余飞 孙晓燕（225）

基于熵产理论的水轮机尾水管涡带研究 ………… 卢金玲 王李科 廖伟丽 赵亚萍 吉庆峰（233）

基于温度效应的作物系数及蒸散量计算方法………………………………………………………………

…………………………………………… 王振龙 顾 南 吕海深 胡永胜 朱永华 杨 秒（242）

基于淹水时长梯度的鄱阳湖优势湿地植被生态阈值………………………………………………………

…………………………………………… 韩 祯 王世岩 刘晓波 彭文启 葛 刚 黄爱平（252）

总体矩阵法在水电站频率调节稳定性分析中的应用………………………………………………………

…………………………………………… 马安婷 杨建东 杨威嘉 唐韧博 冯文涛 侯亮宇（263）

泾河流域水沙联合分布特征分析及其不确定性评估 ………………… 马川惠 黄 强 郭爱军（273）

EDITORIAL BOARD

HONORARY PRESIDENTSSUO Lisheng HU Siyi LIU Ning

CONSULTANTSLU Youmei ZHU Erming GAO Anze ZHANG Zezhen CHEN Bingxin GAO Jizhang

PRESIDENTKUANG Shangfu

VICE PRESIDENTSWU Hongwei TANG Xinhua JIA Jinsheng YANG Xiaodong

MEMBERSCAI Ximing CAI Yuebo Chandra Madramootoo（Canada） CHEN Jin CHEN Houqun CHEN QiuwenCHEN Minjian CHEN Shengshui CHEN Zuyu CHENG Guoyin CHENG Xiaotao DENG JiaquanDesmond Walling（UK） DU Leigong FANG Hongwei FENG Ping FENG Shaoyuan FNEG Shurong GAN HongGAO Zhanyi GU Hong GUO Jun GUO Qizhong（U.S.A） GUO Shenglian HAN Qiwei HE Jianbing HU ChunhongHUAI Wenxin HUANG Jiesheng HUANG Qiang HU Zuoliang Hyo-Seop Woo（Korea） JIA Jinsheng JamesYang（Sweden） JIANG Naiqian JIE Yuxin JIN Juliang KANG Shaozhong KONG Xianjing KUANG ShangfuLI Jiren LI Jia LI Jiusheng LI Wanhong LI Yun LI Yuanyuan LI Zantang LIAN Jijian Xu Liang（U.S.A）LIU Handong LIU Xiaoyan LIU Yulong LIU Zhiping LU Jinyou LU Wenxi MA Hongqi MA JianhuaNI Jinren NIU Xinqiang Norihisa Matsumoto（Japan） PENG Caide QIN Boqiang Roger Falconer（UK） SHEN ZhenzhongSHU Longcang TIAN Bin WANG Fujun WANG Guangqian WANG Hao WANG Lizhong WANG RenkunWANG Wensheng WANG Xiaohong WANG Yicheng WANG Xiaogang WEI Qiwei WU Hongwei WU PuteWU Zhongru XIA Jun XU Zeping XU Zongxue XU Weilin YANG Dawen YANG Kailin YANG XiaodongYAO Shuanxi YAO Wenyi YU Qiyang ZHANG Chaoran ZHANG Chunsheng ZHANG Guoxin ZHANG LiminZHANG Jian ZHANG Jianmin ZHANG Jianyun ZHANG Yongbo ZHANG Zongliang ZHENG PeimingZHONG Denghua ZHONG Pingan ZHONG Zhiyu ZHOU Xiaoguang ZHU Bofang ZHU Xingming ZUO Qiting

CHIEF EDITORCHENG Xiaotao

DEPUTY CHIEF EDITORSGAN Hong XU Zeping

《水利学报》第九届编辑委员会组成名单

名誉主任： 索丽生 胡四一 刘 宁

顾 问： 陆佑楣 朱尔明 高安泽 张泽祯 陈炳新 高季章

主 任： 匡尚富

副 主 任： 吴宏伟 汤鑫华 贾金生 杨晓东

主 编： 程晓陶

副 主 编： 甘 泓 徐泽平

编 委：（以汉语拼音为序）

蔡喜明（美国） 蔡跃波 Chandra Madramootoo（加拿大） 陈 进

陈厚群 陈求稳 陈敏建 陈生水 陈祖煜 程国银 程晓陶 邓家泉

Desmond Walling（英国） 杜雷功 方红卫 冯 平 冯绍元 冯树荣

甘 泓 高占义 顾 洪 郭 军 郭祺忠（美国） 郭生练 韩其为

何建兵 胡春宏 槐文信 黄介生 黄 强 户作亮 禹孝燮（韩国）

贾金生 姜乃迁 介玉新 金菊良 康绍忠 孔宪京 匡尚富 李纪人

李 嘉 李久生 李万红 李 云 李原园 李赞堂 练继建

梁 旭（美国） 刘汉东 刘晓燕 刘玉龙 刘之平 卢金友 卢文喜

马洪琪 马建华 倪晋仁 钮新强 松本德久（日本） 彭才德 秦伯强

Roger Falconer（英国） 沈振中 束龙仓 田 斌 王福军 王光谦

王 浩 王立忠 王仁坤 王文圣 王小红 王义成 汪小刚 危起伟

吴宏伟 吴普特 吴中如 夏 军 徐泽平 徐宗学 许唯临 杨大文

杨开林 杨晓东 杨效亮（瑞典） 姚栓喜 姚文艺 于琪洋 张超然

张春生 张国新 张利民 张 健 张建民 张建云 张永波 张宗亮

郑沛溟 钟登华 钟平安 仲志余 周晓光 朱伯芳 朱星明 左其亭

Deformation characteristics and shear strength failure criteriaof CC-RCC materials in combined dam structures

LI Mingchao，ZHANG Mengxi，ZHANG Jinrui（State Key Laboratory of Hydraulic Engineering Simulation and Safety，Tianjin University，Tianjin 300354，China）

Abstract： In the form of combined damming，many parts of the dam body are jointly poured by large vol⁃ume conventional and roller compacted concrete. The diversity of the distribution positions of the two materi⁃als and the difference of the mechanical properties are the main causes of deformation coordination problemof the dam body. In order to analyze the deformation coordination characteristics of dam materials，meso⁃scopic mechanical numerical models of CC （Conventional Concrete）-RCC （Roller Compacted Concrete） com⁃posite specimens were established. Based on the actual performance of concretes in the dam body， the me⁃soscopic strength of composite specimen was calculated and analyzed by non-homogeneous finite elementmethod. The effects of fly ash content and material interface slant angle on the mechanical properties ofcomposite materials were evaluated. The results show that the strength of concrete composite specimens isdetermined by the strength of weaker concrete materials and it decreases with the increase of fly ash con⁃tent. The lateral compressive stress increases the strength of composite specimens greatly. According to thenumerical test data， the failure criterion of composite specimens in the form of combined damming is pro⁃posed. Then， the mechanism of slant shear failure of composite specimens is analyzed and the validity andreliability of shear failure criterion are verified. The research results can provide a reference for the designof the material in combined dam structures.Keywords：combined dam structure；CC-RCC；composite specimens；shear failure criterion；numerical sim⁃ulation

—— 164

Intelligent grouting control method and system for hydropower engineering

FAN Qixiang1，HUANG Canxin1，JIANG Xiaochun2，

WANG Kexiang1，HUANG Wei1，YANG Ning1

（1. China Three Gorges Projects Development Co.，Ltd，Beijing 100038，China；

2. Spring Energy Science and Technology Co. Ltd.，Chengdu 610093，China）

Abstract：Cement grouting is an important measure for foundation reinforcement and anti-seepage in hydro⁃power projects. Based on the intelligent closed-loop control theory of "full perception， real analysis and re⁃al-time control"， this study proposed a 3-zone， 5-stage and P-Q-C-t coordinated real-time control meth⁃od. Through real-time coordinated intelligent control of the grouting pressure P， the absorption rate Q， theslurry density C， the rock mass uplifting value ΔH，slurry temperature T and grouting duration t， the inte⁃gration intelligent identification and control of grouting under normal and special circumstances are realized.This study also developed an intelligent grouting system composed of intelligent grouting cell （iGC） and in⁃telligent grouting management cloud platform iGM，which realized one-key closed-loop intelligent control oncement grouting process. The system has been fully applied in the consolidation and high-pressure curtaingrouting at the Wudongde and Baihetan hydropower stations. The application ensured the construction quali⁃ty of cement grouting at dam site，and have high popularization and application value in similar projects.Keywords：cement grouting；intelligent grouting method；intelligent control system；intelligent grouting units

—— 174

Influence of roughness and backwater of bridge piers on flood carrying capacityin a wide-shallow river

WANG Tao1，GUO Xinlei1，LI Jiazhen1，GUO Yongxin1，ZHOU Zhigang2，GUO Xiaoming3

（1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin，

China Institute of Water Resources and Hydropower Research，Beijing 100038，China；

2. Hunchun Water Conservancy Survey and Design Team，Hunchun 133300，China；

3. Yellow River Institute of Hydraulic Research，Zhengzhou 450003，China）

Abstract：The roughness and backwater of bridge piers are the key parameters，which effect on the floodcarrying capacity in a wide-shallow river. In this study， these two parameters are analyzed by physical mod⁃el test，numerical simulation and empirical formula. The slope protection is simulated by four kinds of mate⁃rials，namely，no vegetation，sparse vegetation，sparse vegetation and shrub，and dense vegetation. The av⁃erage water level difference is 0.03m under the condition of no vegetation and dense vegetation. The resultsshow that the impact on the flood carrying capacity is not significant with the obvious roughness changes inthe wide-shallow river. The simulation on the backwater of bridge piers shows the results of the two-dimen⁃sional mathematical models， which can reflect the boundary conditions of the river and characteristics ofthe bridge more really than the empirical formula and one-dimensional mathematical model， are close tothe physical model experiments. This study provides a reliable basis for the evaluation of the roughness andthe calculation of the pier backwater in the wide-shallow river.Keywords：wide-shallow river；roughness；backwater；bridge pier；physical model；numerical simulation

—— 183

Experimental study on the influence of densityand stress level on particle breakage of coral sand

CAI Zhengyin1，HOU Heying1，ZHANG Jinxun2，

ZHANG Fenglin2，GUAN Yunfei1，CAO Yongyong1

（1. Department of Geotechnical Engineering，Nanjing Hydraulic Research Institute，Nanjing 210024，China；

2. Beijing Urban Construction Group Company Limited，Beijing 100088，China）

Abstract：During the shearing process，coral sand is prone to particle breakage，which is related to stresslevel， initial density and stress path. In order to study the effect of density and stress level on the parti⁃cles breakage of coral sand， triaxial compression tests and one-dimensional compression tests were carriedout. In this paper， the quantitative relationship between the relative breakage of particles and the confiningpressure and the initial void ratio of the specimen under triaxial compression is established，as well as therelationship between the relative breakage and the average particle size of the sample. The results showthat， under triaxial compression and one-dimensional compression， the relative breakage increases with theincrease of stress level （confining pressure or vertical stress） and sample density， but the degree of parti⁃cle breakage under the two stress paths is significantly different.Keywords：coral sand；particle breakage；triaxial test；one-dimensional compression

—— 192

Optimality conditions for operating rule of parallel reservoir systemⅡ.Algorithm design and case study

HU Tiesong，ZENG Xiang，WANG Jing，WANG Xin，WANG Qin（State Key Laboratory of Water Resources and Hydropower Engineering Science，Wuhan University，Wuhan 430072，China）

Abstract：Following the assumption that multi-period reservoir optimal operation problem can be formulatedby multiple two-period optimal operation problems， this paper designs a new algorithm to solve themulti-period operation model on the basis of K-T conditions presented in companion paper. Further，to veri⁃fy the effectiveness of the new algorithm， a real-world parallel reservoir supply system in Liaoning Prov⁃ince， i.e.，Biliu River reservoir and Yingna River reservoir， is used as a case study. The numerical resultsshow that less water shortage and higher supply reliability are obtained from the new algorithm with compar⁃ison of the performances of the commonly used operation rule.Keywords： parallel reservoir system； two-period model； optimality conditions； K-T conditions； algorithmdesign

—— 200

Water resources comprehensive allocationand simulation model（WAS），part Ⅱ. Application

SANG Xuefeng，ZHAO Yong，ZHAI Zhengli，CHANG Huanyu（State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin，

China Institute of Water Resources and Hydropower Research，Beijing 100038，China）

Abstract：Aiming at the characteristics of the natural-social water cycle system， a multi-dimension indexmodel verification method for cross-section flow process， cross-section feature runoff volume， regional waterallocation was established， and Qingyang City in Gansu Province is taken as an example to use the WASmodel（Water Allocation and Simulation Model）. The correlation coefficient R2 of runoff simulation in calibra⁃tion period 1967-1985 of the Yuluoping cross-section was 0.89， and the Nash coefficient was 0.79. Thecorrelation coefficient R2 of runoff simulation in validation period 1986-2000 was 0.88，and the Nash coeffi⁃cient was 0.76. The average annual error of the simulation and measurement of regional water resourceswas 4.1%，and the errors at frequency of 25%，50%，75% and 90% were 5.0%，1.1%，5.9% and 4.2%，

respectively. The average error of the water allocation and measurement of Qingyang City was 0.35%. Basedon the result， the water resources allocation plan for water supply of 284 million m3 and water consump⁃tion of 211 million m3 in the current year was put forward， and the decomposition map of regional waterbalance was given. The results show that WAS model can describe the dynamic feedback relationship be⁃tween natural and social water circulation systems，and the model can also meet the accuracy requirementsof water resources assessment and management.Keywords：water resources； simulation； allocation； verification；water resources assessment；water resourc⁃es management

—— 208

Real-time flood control risk estimation of reservoir and analysis on the interoperability ofstorage capacity of multi-reservoir regulation

DUN Xiaohan1，2，ZHOU Jianzhong1，2，ZHANG Yongchuan1，2，

CHEN Lu1，2，WANG Quansen1，2，DAI Ling1，2

（1. School of Hydropower and Information Engineering，Huazhong University of Science and Technology，Wuhan 430074，China；

2. Hubei Key Laboratory of Digital Valley Science and Technology，Wuhan 430074，China）

Abstract： The risk analysis of reservoir flood operation is an important link and basis for real-time floodcontrol decision-making. In order to evaluate the real-time flood control risk of the reservoir，a method forcalculating the frequency curve of reservoir capacity based on a long series of measured historical runoff da⁃ta was presented in this paper. Based on this proposed method， the risk analysis model of real-time floodcontrol operation was established. Furthermore， according to the actual flood control operation demand ofthe Three Gorges Reservoir， the flood control risk of reservoir in different periods of flood season was fur⁃ther analyzed. Meanwhile， the variation of the frequency curve of flood control capacity and the interopera⁃bility of storage capacity of multi-reservoirs were studied when the upstream cascade reservoirs cooperatewith the Three Gorges Reservoir for joint operation. The study shows that the calculated frequency curve ofreservoir flood control can be used to judge the current flood situation and effectively reduce the flood con⁃trol risk of the Three Gorges Reservoir by using the interoperable performance of reservoir flood control rea⁃sonably.Keywords： flood control storage capacity； risk analysis； frequency curve； joint flood control operation；flood storage capacity distribution and interoperability

Unsteady change of water and sediment processes downstream of cascade reservoirs in theLower Jinsha River and its influence on navigation conditions

CHEN Xujian（State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin，Laboratory of Hydraulics and Sediment Science and

River Training of Ministry of Water Resources，China Institute of Water Resources and Hydropower Research，Beijing 100048，China）

Abstract：With the construction and application of cascade reservoirs in the Lower Jinsha River， the waterand sediment processes downstream of the reservoirs are obviously changing and affecting navigation condi⁃tions. The analysis method of water and sediment unsteady process is proposed，and the unsteady character⁃istics of water level，discharge and sediment concentration downstream of Xiangjiaba reservoir and its influ⁃ence on navigation conditions are analyzed. The results show that the variation coefficient of water level canreach 0.10~0.12，and the variation coefficient of discharge can be 0.20~0.40. Although the sediment concen⁃tration decreased significantly， the variation coefficient of sediment concentration could reach about 1.0. Theannual average normalized water level and discharge in Xiangjiaba hydrologic station is about 1.0， and thenavigation conditions of the montanic river channel downstream of Xiangjiaba reservoir are generally stable.It is beneficial to reduce the flood peak and increase low discharge to the navigation conditions of the riv⁃er channel downstream the dam，but the daily regulation of the hydropower station， the reservoir water stor⁃age and the flood discharge increase the inconstancy of the flow and water level，which have some adverseeffects on the navigable conditions.Keywords： Lower Jinsha River；cascade reservoirs；water and sediment process；unsteady change；navigationconditions

—— 224

Influence of water content on dynamic compressive propertiesof concrete subjected to seismic strain rate

WANG Hailong1，YIN Wenwen1，CHENG Xudong2，SHENG Yufei2，SUN Xiaoyan1

（1. College of Civil Engineering and Architecture，Zhejiang University，Hangzhou 310058，China；

2. College of Pipeline and Civil Engineering，China University of Petroleum，Qingdao 266580，China）

Abstract： To clarify the influence of water contents on the mechanical properties of concrete subjected toseismic strain rate，a vacuum water-saturated equipment was used to prepare concrete specimens with differ⁃ent water contents rapidly. The effect of cement secondary hydration on the rest results can be minimizedby this method. Uniaxial compression tests were carried out at strain rates of 10-5，10-4 and 10-3 s-1. The ef⁃fects of strain rate and water content on the stress-strain curves， compressive strength， elastic modulusand critical strain of concrete are analyzed. The obtained results show that the compressive strength andelastic modulus increase with the increase of strain rate，while the critical strain of concrete decreases. Ata same strain rate， increasing water content lowers the compressive strength， but increase the dynamic in⁃crease factor under dynamic loading. Critical strain decreases more significantly with the increase of watercontent especially at higher strain rates. Empirical formula for the mechanical properties of concrete are pro⁃posed in this study considering the effect of strain rate as well as the water content， which has a goodagreement with the test results.Keywords：concrete；water content；strain rate；multi-parameter analysis；mechanical properties

—— 232

Entropy production analysis for vortex rope of a turbine model

LU Jinling，WANG Like，LIAO Weili，ZHAO Yaping，JI Qingfeng（Xi’an University of Technology，Xi’an 710048，China）

Abstract： In order to study the causes and pressure pulsation characteristics of the vortex rope under thepartial load condition of the pump turbine， the model pump turbine was set as the research object in thispaper. Both the steady and unsteady three-dimensional numerical simulation was carried out to simulate theinternal flow，which was analyzed by the entropy production theory further. The results show that the numer⁃ical simulation is in good agreement with the experimental data. The entropy production in the scroll andstay vane is very small，while it is greater in the runner and draft. The flow separation produced on thepressure surface in the small discharge condition and it leads to the appearance of the high entropy produc⁃tion rate distribution area. And the area will expand as the discharge is further reduced. There are twokinds of vortex ropes with strong and fine shape at partial load，which are all spiral. The formation of thevortex rope has a great relationship with the circulation of the blade outlet n deviating from the zero. Theappearance of the vortex rope will form a vortex in the draft tube，blocking the draft tube passage. The vor⁃tex rope will rotate in the same direction with the runner，but the rotation speed is lower， resulting in lowfrequency pressure pulsation with large amplitude in the draft tube.Keywords：pump turbine；entropy production；vortex rope；pressure fluctuation；flow field

—— 241

Calculation of crop coefficient and evapotranspiration based on temperature effect

WANG Zhenlong1，GU Nan2，LÜ Haishen2，HU Yongsheng1，ZHU Yonghua2，YANG Miao2

（1. Water Resources Research Institute of Anhui Province，Bengbu 233000，China；

2. Hohai University，Nanjing 210098，China）

Abstract： It is of great significance to accurately estimate the crop evapotranspiration， for developingsound irrigation plans and improving water use efficiency. To explore the dynamic change of daily water de⁃mand，and temperature effect on crop growth， the three-point temperature （optimal temperature，upper lim⁃it temperature， lower limit temperature） were applied to calculate crop coefficient and evapotranspiration.The calculation models of evapotranspiration for winter wheat and summer maize were established based onthe data of large-scale weighing lysimeters and weather monitoring station in Wudaogou Hydrological Experi⁃mental Station. The results show that crop coefficients of wheat and maize simulated through temperaturehad a high degree of fitness with the measured data. Both correlation coefficients are greater than 0.80 andboth average absolute errors are about 0.10. The evapotranspiration model has reliable forecasting ability ondifferent time scales， of 1 d，3 d and 5 d. The correlation coefficients of wheat are 0.95，0.98， and 0.98，respectively. With the time scale increasing from 1 d to 5 d， the absolute error decreased from 0.67 mm·d-1

to 0.41 mm·d-1， the forecast accuracy rate（<1 mm·d-1） increased from 73% to 90%，and the forecast accu⁃racy improved. Simultaneously，maize showed the same law.Keywords： temperature effect；crop coefficient；actual evapotranspiration； reference crop evapotranspiration；time scale；forecast model

—— 251

Ecological thresholds for the dominated wetland plantsof Poyang Lake along the gradient of flooding duration

HAN Zhen1，WANG Shiyan1，LIU Xiaobo1，PENG Wenqi1，GE Gang2，HUANG Aiping1

（1. Department of Water Environment，China Institute of Water Resources and Hydropower Research，Beijing 100038，China；

2. Nan Chang University，Nanchang 330000，China）

Abstract：After 2003， the "river-lake" relation between Poyang Lake and Yangtze River has been changedsignificantly. The flooding duration for the wetlands is obviously shorter than that before 2003， and it ishard to guarantee the ecological demands of wetland plants. The trend of wetland degradation has emergedgradually. In order to illustrate the ecological demands of wetland plants for flooding duration， the responsecurve has been established by the coupling between hydrodynamic model and statistical model，and the eco⁃logical thresholds of the six dominant wetland plants of Poyang Lake are quantified， respectively. The re⁃sults demonstrate that the relation between area of wetland plants and flooding duration can be depictedthrough Gaussian curve，and the optimal， suitable and inhibited thresholds can be estimated along the gra⁃dient of flooding duration. Besides， there are obvious differences for the ecological thresholds among the sixspecies of wetland plants. For instance， Carex has the strongest adaptability to flooding， and the suitableand the optimal thresholds for the Carex are 60~240 days and 120~180 days， respectively， while itsgrowth would be inhibited if the duration of flooding is longer than 300 days. Among the six species of wet⁃land plants， Cynodon dactylon shows weakest adaptability to flooding， its suitable and optimal thresholdsare 30~60 days and 30~90 days， respectively， and it is not found in area where the flooding duration islonger than 120 days. Different survival strategies， such as dormancy and morphological plasticity， are themain reason for the different ecological threshold. The findings of this study can be used for guiding theeco-hydrological process regulation and wetland restoration.Keywords：Poyang Lake；wetland plants；flooding duration；gradient；ecological threshold

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Application of overall matrix method in operation stability analysisfor frequency regulation mode of hydropower stations

MA Anting1，YANG Jiandong1 YANG Weijia1，

TANG Renbo1，FENG Wentao2，HOU Liangyu1

（1. State Key Laboratory of Water Resources and Hydropower Engineering Science，Wuhan University，Wuhan 430072，China；

2. Guangdong Hydropower Planning and Design Institute，Guangzhou 510635，China）

Abstract： The operation stability is a key problem in design and operation of hydropower stations. In thepast， theoretical analysis based on transfer function method and numerical simulation were mostly used toanalyze the operation stability of hydropower stations. However，when the pipeline system is more complex，such as a system with multiple generating units sharing a same pipeline， it is difficult to deduce the sys⁃tem transfer function，and it is not easy to establish the simulation model and get a more accurate stabilityregion. The aim of this paper is to study the above problems. First， the expression of the impedance of hy⁃dropower generating units is derived. Then，based on the analysis method of oscillation characteristics of hy⁃draulic system，an overall matrix of the hydropower generation system is established，and the stability crite⁃rion is applied based on whether the maximum damping ratio is smaller than zero. In order to verify themethod， two engineering examples are given in this paper. For a hydropower station with one generatingunit， the proposed overall matrix method is compared with transfer function method and numerical simula⁃tion based on MATLAB/Simulink； for a hydropower station with four generating units sharing the same con⁃duit， the proposed overall matrix method is compared with the numerical simulation based on MATLAB/Simulink. The results show that the overall matrix method can accurately solve the stability region of thecomplex system and can be adapted to various layout forms of hydropower stations by modifying the orderof the corresponding matrix arrangement of the system，which greatly facilitates the calculation and analysisof the stability of hydropower stations.Keywords：hydropower station；overall matrix；complex pipeline system；stability

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Characteristic analysis and uncertainty assessment of joint distributionof flow and sand in Jinghe River basin

MA Chuanhui，HUANG Qiang，GUO Aijun（State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China，

Xi’an University of Technology，Xi’an 710048，China）

Abstract：The flow and sediment are non-independent two-dimensional random variables，so it is very nec⁃essary to carry out joint probability analysis of flow and sediment in order to realize the scientific manage⁃ment scheme of flow and sediment. In the joint probability analysis， the limited flow and sediment samplesize would induce quantile estimation uncertainty in bivariate probability analysis. Based on Monte Carlomethod， this paper presents the quantitative uncertainty evaluation method of bivariate quantile estimationin the Jinghe River basin. The flow and sediment joint distribution model is established based on Copulasfunction and the most likely realizations of bivariate quantile estimation are derived. The Monte Carlo sam⁃pling method is used to analyze the influence of sample uncertainty of bivariate quantile estimation，and theconfidence region of bivariate quantile estimation is calculated. The results demonstrate that when the OR re⁃turn period is 20 years， the 95% confidence region of bivariate quantile estimation shows greater uncertain⁃ty. It is a great challenge to determine the quantile estimation of river basin engineering design. The uncer⁃tainty of bivariate quantile estimation increases with the increase of the joint return period level.Keywords：Copula function；Joint return period；Monte Carlo；Most likely combination；Jinghe River basin

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