Abstract: This paper presents a frame of constructing a family of finite volume high performance schemes on unstrctured grids for solving the shallow-water equations. By introducing upwind decompositions of numerical fluxes in the direction normal to and across each side of cells,four one dimensional algorithms including Osher,TVD, and two Flux-Vector Splittings,can naturally be extended to the two dimensional case. Moreover,boundary procedures applied to opern and land boundcries for both supercritical and subcritical flows are given. Finally,the schemes have been used to model flows over a bump,with a moving land boundary,and of an estuay tide,respectively. The results show that they are not only sufficiently accurate and nonoscillatory,but also capable of treating automatically fow transients, hydraulic jumps,and moving land boundaries.
Abstract: Accordint to the field data of velocity distribution in several years and the hydrology-water quality in 1987 and 1988,thd longitudinal dispersion in Guangzshou reach of the Pear River was analyzed,and the instantaneous value,the tidal averaged value and the equifinal value of dispersion coefficients were obtained by using the dispersion theory of unsteady flow.
Abstract: A field water balance model has been developed in this paper. With the assumed boundary conditions,the long-term annual percolation of soil water (PSW) is simulated for one-meter depth soil horizon for cropping systmes of winter wheat/summer maize and winter wheat/bare soil. The results show that PSW is expressed as a linear function of seasonal precipitation,which is different in various cropping systems. PSW changes significanly in different hydrologic year types, which is 70~140mm more in humid years than in dry years. While in the winter wheat/bare soil it is 30~50mm more than in the winter wheat/summer maize.
Abstract: The paper analyses the trend of annual runoff series for Guanting Reservoir of Yongding River and Fenhe Reservoir of Fenhe River. The meteorological factors and human activities resulting in the trend are studied. The research results show that the main factors affecting the trend of annual runoff are the trend of precipitation corresponding fluctuation of precipitation during the some periods and the increasing of agricultural.industrial,forestrial and domestic water use in the basin. According to historical data and possible human activities of the basin under study in the future,the predicted results of long trem annual runoff are presented.
Abstract: Based on conventional model of flood control benefit,several kinds of uncertainties,including hydrological,hydraulic,structural,managemental and operational uncertainty,are synthetically analyzed. A risk model of flood control benefit of Three-Gorge Project has been established. It is indicated that the probability distribution of the benefit represents more reasonably,considering the impact of various uncertainties.
Abstract: The thixotropy of a Bingham plastic fluid and the law of drag force flowing around a sphere in the fluid are studied in this paper. Through theoretical derivation and experiments,the formulas calculating the yield stress of Bingham fluids with thixotropy and the non-settling maximum sphere diameter of increasing with the duration of the fluid at rest were obtained. The Navier-Stokes equations of Bingham fluids with thixotropy were developed. By solving these equations,the formulas of the drag force and drag coefficient flowing aroung a sphere in Bingham fluids with thixotropy were derived also. Using data of rheological experiments with various slurries and of a sphere motion observed on X-ray screen,the above equations were verified with the results that the calculated values are in good agreement with the experimental values.
Abstract: The roles and selection of several models in water quality planning and prediction were discussed. The theoretical shortcomings associated with COD first decay models and some difficulties encountered in loading evaluations from CODMn and CODCr are indicated.and some resasonable and feasible methods dealing with those problems are given also.
Abstract: An Artificial Neural Network (ANN) methodology for optimal opertions and operation rules of multi-reservoir system is developed in this paper,it has also been investigated the effect of the change of training parameters,methods and patterns on the training and performance of BP network. The case studies have shown the feasibility and the effectivenes of the proposed model and algorithm.
Abstract: The Artificial Neural Network (ANN)method for long-range runoff forecast was dresented in this paper. With the application of one of the typical artificial neural network models "back-propagation" model,we selected the runoff status of Da Huofang Reservoir as an object of study to test the performance of the ANN mehtod approach. As a result,the successful rate is higher and the fault-tolerant ability is stronger. Therefore the ANN method might be referred as an effective assistant technique for long-range runoff forecast.
Abstract: The network method,minimum-cost and maxinum-flow method,has obvious advantages for simulating systems in water resources planning. By taking a tributary of the Yellow River as an example,this paper presents some technical problems and their solutions in the applications of the method to the simulation of river-basin water-resources planning and utiliza-lion.
Abstract: Experimental studies for division of flow in a short branch channel set at right angles to a main channel were carried out for various flow division rations of the branch channel flow to the main channel flow. Based on the measured data of flow velocities eight flow regions near the open channel junction are divided to explain the different flow configuration. The width of dividing flow of the main channel into the branch channel along the vertical direction is measured in order to determine the sediment load flowing into the branch channel.
Abstract: Many application researches of artificial neural networks (ANN)have been made in hydrology and water resources. The state-of-the-art of ANN as applied to hydrology and water resources has been examined and evaluated through four classified problems,those are(1)pattern recognition,(2) prediction,(3) optimization,and (4)ANN-based expert system. The major problems and directions for the future studies are presented in this paper.