CONTENTS

Key words sediment transport rate，graded sediment，effect coefficient of non－uniformity，saltation.

Abstract  A new method for inverse calculation of the blade S2 stream surface in centrifugal pump is established with the flow slip has been considered.The meridian flow is considered as a vortex flow and a slip rate correction is recommended to consider the effect of slip caused by finite amount of blade.An example is given for demonstration.

Key words  centrifugal pump, blade of impeller, slip,S2 stream surface, inverse calculation.

Back analysis of elastic moduli according to the
displacementmeasurements in cut slopes
Deng Jianhui Feng Dingxiang Ge Xiuren
(Wuhan Institute of Rock and Soil Mechanics,Chinese Academy of Science)

Abstract  A model and a practical optimization method are suggested in this paper for the back analysis of elastic moduli
according to the displacement in cut slopes.The model and the method have been proved to be feasible through the back analysis of elastic moduli of the Three Gorges' shiplock slope.

Key words  cut slope,elastic modulus,back analysis,displacement measurement.

The assessment and check of dam safety for flood prevention
Jiang Shuha
(Nanjing Hydraulic Research Institute)

Abstract　Top redict nume rically theris kasse ssme nt of the dam failu redue toove rtopping,am athe matic alproce dure isproposed inthis paper.The metho dprovide sanap proach tovis ualize the random and fuzzy  phenomena in dam flood prevention system and helps to establish the stochastic risk model for overtopping.

Key words  dam safety， overtopping， stochastic differential equation，random and fuzzy risk analyses.

Characteristics of environmental hydromechanics and total pollutants dischargeload control for down stream of Yangtze River

Zhu Weibin Zhu Huaining Zheng Xiaoyu
(Hohai University)

Abstract This paper takes the Zhengjiang river section as an example to analyze the water pollution in different river sections of Yangtze river from environmental hydromechanics point of view.It also investigates how to carry out regional total pollutants discharge load control to preserve the water resources in course of economic development.

Key words  environmental hydromechanics， water pollution，  total load control，  environmental benefits.

The study on multiobjective optimization method
for cascade water-power development

(Luo Zhihui)
((Hunan Normal University))
(Chen Huiyuan Feng Shangyou)
((Wuhan University of Hydraulic and Electric Engineering))

Abstract  Multiojective complex sequencing model for minimizing discounting cost and accumulating overcapacity expansion process is developed.It is theoretically demonstrated that the two dimensional problem related to optimizing sequencing and operating time for power can be converted into the one-dimensional problem to minimize the sequencing.
The direct method for optimizing vector technique to make noninferior policy for multiojective DP is developed.
Key words  Cascade water－power stations， sequencing， multiobjective.

Weighted optimum curve－fitting method for estimating the
parametersof Pearson type－Ⅲ distribution
Qiu Lin
(North China Institute of Water Conservancy and Hydropower)
Chen Shouyu
(Dalian University of Technology)
Pan Tong
(China Internationl Water & electric Coip)

Abstract The weighted optimum curve－fitting method for estimating the parameters of Pearson type－Ⅲ distribution is presented in this paper. This method can increase the stability of calculation and reduce the influnce of errors in hydrologic data on estimation of the parameters as well as utilizing information in real hydrologic data.The method is tested by safety standard of hydraulic engineering with a great deal of ideal and real hydrologic data. The results show that the method of least squares criterion is stable and its precision satisfies the safety standard for hydraulic engineering.

Key words  parameter estimation， curve\|fitting， fuzzy weighted optimum，relative membership.

An expermental method of mutidimensional dynamic programming
and its application in cannal engineering system

Cheng Jilin Jin Zhaosen Sen Jie Liu Zhengxiang Chen Ping
(Yangzhou University)

Abstract  This paper presents an optimal experimental method for mutidimensional dynamic programming.Applicaiton of this method makes the solution of high multidimeusional problem become possible.An optimal design model of cannal engineering is introduced as an example.
Key words  dynamic programming, mutidimension,optimal design method,cannal engineering.

Simulation of water balance in crop growth field

Lu Jun
(Zhejiang Agricultural University)

Abstract Based on the crop growth model MACROS(L1D), a dynamic coupling model for crop growth and water balance in field is established with the help of the relationship between soil water conditions and crop growth. The model includes three submodels; crop growth, water transmission in SPAC system, and coupling relationship between crop growth and soil water conditions. In this paper a ttention is focussed on the discussions of the simulation approaches for water balance in the crop growth field. Comparing with the field experiment, the simulation results of soil water movement in crop growth and the sensitivities of some parameters about water balance have been analyzed. The model system has been used in simulating the water balance for winter wheat in rainy region of southern China, and in studying the processes of occurrouce and fading of soil waterlloging in this region.

Key words SPAC water transfer, coupling model for soil water movement and crop growth, water balance, waterlogging, soil surface drainage.

Structural and seepage characteristics of rockfill damby directional blasting

Chen Binlin Wang Baoyi Chen Yaozhong
(China Institute of Water Resource and Hydropower Research)

Liu Hongliang
(Yunnan Provincial Water Conservancy & Hydroelectric Survey Design & Research Institute)　

Chen Tianbao
(Bureau of Water Resource & Electric Power Wuding County Yunnan Province)

Abstract The results of prototype observation of Jiyi rockfill dam by directional blasting are presented in this paper. 1.structural characteristics and the mechanism of stability against seepage flow of the damare discussed .2.the highest water head loaded by the dam respectioely are 66.55m and 68.54m.2)2 years water retaining test had been engaged without impervious element.8.fallowing the conception of proposed.3.The water surface distribution,flow pattern and head loss of seepage in the dam are investisuted.4.An empirical formula and a method for calculating unit tam width seepage discharge of rockfill dam are given.
Key words  rockfill dam by directional blasting,prototype observation,degree to dam up,seepage discharge for unit dam width,stability against seepage flow

Experimental study on shear cracking strength of prestressed
steel fiber reinforced concrete beams

Zhao Shunbo
(North China Institute of Water Conservancy & Hydropower)
Zhao Guofan Huang Chengkui
(Dalian University of Technology)

Abstract   Based on the experimental study on the shear behaviors of forth－five prestressed steel fiber reinforced concrete beams, the effects of the stirrups, the shear span to depth ratio, the effective precompressed force, the volume fraction and aspect ratio of steel fiber on the shear cracking strength of prestressed steel fiber reinforced concrete beams are analyzed. The theoretical model and the practical formulas for calculating the shear cracking strength of prestresseed steel fiber reinforced concrete beams are proposed.
Key words  steel fiber  prestressed concrete  beam  shear cracking strength.

A study on field soil water balance for summer corn in north China plain

Liu Qunchang
(China Institute of Water Resources and Hydropower Research)
Xie Shenchuan
(Tsinghua University)

Abstract  In this paper,field soil water balances in root zone is simulated by using one－dimensional variable saturated water flow model under the condition of different hydrographic year and irrigation requirement for summer corn during different growing stage.The relation among the evaporation from cropped soil surface,the leak at bottom and the irrigation requirement have been studied quantitatively.The optimal irrigation requirement recommended by the authors is 600m
ha for summer corn in north China plain.

Key words  summer corn,field soil water balances,irrigation requirement.

Study on upstream bottom－joint for improving the stress conditions of high arch dam
Wang Guanglun Zhang Chuhan Guo Zhisong Jin Feng
(Tsinghua University)

Abstract  The BEM is adopted to study the effect of upstream bottom-joint on the stress distribution of arch dam. The variations of stress and displacement of arch dam with bottom joint at different elevation, of different crack depth, with or without water pressure on the crack face are to be studied. The result of analysis demonstrates that the setting of upstream bottom-|joint is a suitable measure for improving the stress condition of arch dam.
Key words  arch damd, upstream bottom-joint, boundary element method, wet joint

Field experiments and numerical simulation of soil water and heat
regimesunder the condition of summer corn partially covered by mulch strips

Ren Li
(China Agricultural University)
Zhang Yufang Shen Rongkai
(Wuhan University of Hydraulic and Electric Engineering)

Abstract  The field experiments of soil moisture and temperature regimes under strip wheat straw mulch are introduced in this paper. A numerical model using the alternating direction implicit(ADI) finite difference method to study two－dimensional soil heat and water flow with a partial surface mulch cover is established. In the model, a soil  surface energy balance equation is used to determine soil surface boundary condition of mulch data. The inputs required for the numerical simulations are common weather data, soil thermal and hydraulic parameters as well as mulch data. The heat flow model is verified with analytical solutions. The proposed model successfully simulates the field moisture content and temperature regimes under the condition of strip wheat straw mulch at summer seeding stage.
Key words strip mulch, soil moisture and temperature regimes, model, simulation