Abstract Flow characteristics of multi-jet impinged into a plunge pool are investigated experimentally. By using the sheet laser light and tracing technology, flow visualization is carried out. The experimental result Is in accordance with the theoretical analysis. It shows that the effect of flowing water cushion is significant in reducing the impact on the plunge pool bottom. Some hydraulic formulas deduced are verified by experimental Data.

Key words jets, plunge pools,flowing water cushion, impact.

On the differences of flow patterns and hydraulic characteristics

(China Institute of Water Resources and Hydropower Research)

Abstract This paper deals with the flow characteristics in model tests of plunge pool for high arch damunder different ambient pressure, including the flow patterns, time average pressure and fluctuating pressure acting on the bottom floor and downstream face of the dam. The results show that the flow patterns and flow characteristics in plunge pool are changed with the reduction of ambient pressure in vacuum tank.

Key words ambient presure, flow pattern, hydraulic characteristics, vacuum tank.

Application of artifical neural network approach to implement recognition and predict flow induced vibration system

Abstract Basd on the recognition theory of artifical neural network, using the strong function of learning and thinking of artifical neural network, the model of dynamic system are set up, including the simulation model of nonlinear dynamic system and vibration system of hydraulic engineering struture , The computational results of neural network are in accordance with the theoretical analysis. Neural network approach is adopted to establish an intelligent model to simulate the flow induced vibration of high archdam. The results are consistent with the calculation by reverse analysis theory.

Key words neural network, dynamic system. flow induced vibration, equivalent load, intelligent prediction.

(Taiyuan University of Technology)

Abstract Based on the infiltration experiments of natural freeze-thaw soils in field lysimeters whth different groundwater levers within freezing and thawing period, the influence of the buried depth of groundwater level on the capacity and the relative steady infiltration rates of freeze-thaw soils as well as the characteristics of soil infitration capacity are analyzed and discussed. The results indicate that the buried depth influences clearly on the infiltration capacity of freeze-thaw soils. The results is of practical meaning in determining the reasonable irrigation technical parameters within the winter and spring irrigation in searsonal frozen districts.

Key words freeze-thaw soil, water infiltration, buried depth, ground water level, steady infiltration rate.

(China Irrigation and Drainage Engineering Development and Training Center)

Abstract Optimal design model pipeline network is being improved by introducing superposition discharge, coefficient of reduced discharge and virtual regulator of pressure in accordance with the special characteristics of the well-irrigation area in North China. The optimal design of single well pipeline network is obtained.

(Xian Engineering University)

Abstract By using an ideal model pumping groundwater near an incomplete river, the authors developed a 3-D steady state mathematical model for the problem. On the basis of solving the model using finite difference method, the authors concluded that pumping near an incomplete river may cause groundwater flow from the other side of the river into the pumping side. The width, completeness of the river and the permeability of the river bed layer will strongly affect this kind of groundwater flow. Groundwater flow problem under such circumstance should be simulated by 3-D mathematical model.

Key words riverside pumping, incomplete river, groundwater, beneath river.

(Hohai University)

Abstract The evolutions of the river sections downstream of Shuikou and Danjiangkou Hydro Project are investigated on the basis of the analysis on observation data.

Key words reservoirs, river evolution, regulation line, groin, flood control, embankment.

(Institute of Geography, Chinese Academy of Sciences)

Abstract Based on data from alluvial rivers in China, some complicated mechanical behaviors of silt water flow in river are investigated. It shows that the channel geometry also exhibits some complicated behaviors in response to variation of suspension concentration. With the increase of concentration, the channel width-depth ratio increases. But it will decrease, after reaching a maximum. When suspension concentration is low, the river tends to meandering pattern. The increase in concentration leads to transformation from meandering to braided patterns. However, when the concentration further increases and enter the range of hyper-concentrated flows, meandering pattern appears again.

Key words silt water flow, stream power, complicated behaviors, channel pattern.

(North China Institute of Water Conservancy Hydroelectric Power)

Abstract In this paper the concept of river entropy is introduced. Based on the law of the trend of river system, the self-adjust mechanism and energy dissipation properties of alluvial river are analyzed in the view of system. According to the variation principle, the regular pattern of energy dissipation in river system as well as the relationship between freedom degree of riverbed adjustment and river energy dissipation for counting the river disturbance by human activities are further studied.

Key words river system, river entropy, energy dissipation in crosswise, feedback adjustment.

Abstract Experimental results of long term autogenous volume deformation of concrete containing MgO mixed in different types are presented in this paper. It is illustrated that the long term mechanical behavior of MgO concrete is stable and the expanding agent has little effect on the long term mechanical properties of the concrete.

Key words MgO expanding agent, concrete, long term, autogenuous volume deformation.

Abstract The modified version and the extended version of the parabolic wave equation for mild slope are derived based on the variation principle. The equations are compared with conventional parabolic wave equation. The numerical examples for demonstrations of the applicability of the modified equation are given. The proposed new equation are shown to be capable of describing the propagation of the wave over a bed consisting of substantial variations in water depth and predicting the wave refraction-diffraction with 3-D topography.

Key words variation principle, modified parabolic wave equation, mild slope,refraction-diffration,  numerical simulation.

(Hehai University)

Abstract By using coordinate transformation of revolve, compression and again revolve, this paper concludes a formula for calculation of three-dimension well flow in random anisotropic rock masses. Based on the information of pumping test a semi-analytic method for determination of hydraulic conductivity tensor in random anisotropic rock mass is proposed. The example given in this paper shows that this method is easy to use and quite accurate.

Key words conductivity tensor, semi-analytic solution, 3-D well flow, pumping test.

Abstract Based on the analysis of the characteristics of rainfall and relevant surface and subsurface waterlogging, this paper presents the idea that a drainage project must accomplish combined control both of surface and subsurface waterlogging. From this idea, in planning a drainage project or in water management of a drainage system, the crop yield losses caused by both surface and subsurface waterlogging resulted from heavy rainfall should be taken into consideration. Two drainage indexes for the combined control of surface and subsurface waterlogging are proposed. Based on the experimental results, the relationship between relative yield of cotton and comprehensive index of waterlogging control are established.

Key words surface and subsurface waterlogging, drainage index, farmland drainage.

(Pearl River Water Resources Commission)

Abstract Based on the research of the laws of water-sediment transport and evolution of shoals and gullies the optimal harness alternatives of Lingdingyang Bay in Pearl River estuary is selected by means of data analysis, physical model, numerical model and remote sensing.

Key words Pearl River estuary, Lingdingyang Bay, harness, control line, improvement.