Abstract: For higher accuracy in simulating the transformation of three-dimensional wave,applying the advantages of the constant panels and linear elements,a combined boundary element is applied in this research.The method can be used to get rid of the transverse vibration due to the accumulation of computing errors.A combined boundary condition between the Sponge layer and the Sommerfeld radiation condition is used to remove the reflected waves from the computing domain.By following the water particle on the water surface,the third order Stokes wave transform is simulated by the numerical wave flume technique.The computed results have good agreement with theoretical one.
Abstract: Based on the high accurate Gauss integral formula,a high resolution and totally two orders accurate scheme is designed by using a staggered grid for shallow water equation.The difference scheme does not face to solve Riemann problem due to use the staggered grid,so the difference scheme has the specialty of simple computing and convenient programming.By the way,in one-dimensional scalar equation,the difference scheme is TVD (Total Variation Diminishing scheme) with CFL (Courant Friedrich Lewy) condition.In two- and three-dimensional cases,the scheme has MmB (Maximum and Minimum Bounds Preserving) property.With the Shuguang-1000 distribution storage vast scale parallel computer at the computing center of China,the high resolution difference scheme for solving shallow water equation with the staggered grid is used to numerical simulate several typical program,the computed results are satisfy.
Abstract: Based on the algorithm frame of finite volume on unstructured grids,by introducing upwind decomposition of flow and sediment numerical fluxes in the normal direction to and across each side of cells,a 2-D finite volume method for flow and sediment movements is established,including exchange modes between suspend sand and bed sand,and sediment-carrying capacity formula of different grain.The algorithm is used to simulate the numerical value on flow and sediment transport and riverbed deformation.It is proved that this algorithm can reflect the dynamic process of flow and sediment transport and river bed deformation,and that the precisions satisfy the analytic need of the river engineering.
Abstract: Based on recent development of gas-solid two phase flows,a necessary condition for suspended particle enhancing turbulence in open channel flows was derived,which incorporates with the standard for distinguishing suspended load and bed load.The analysis result is in good agreement with exist ing experimental evidences.
Abstract: The κ-ε turbulence model is used to establish a mathematical model of a plane negatively buoy ant inclined jet in static environment.Through the comparison of the calculated result and tested data of D.M.Shahrabani,predictions of these kinds of jets are made.The region of this flow can be divided into three parts,namely,jets region,recirculation region and horizontal spreading region.The demarcations between jets,horizontal spreading region,and the inner demarcation of jets region are given also.The position of the contracted section and the variations of velocity,density and turbulent kinetic energy along the contracted section are given in the end,which can be used as the boundary condition for calculation of far-field-behavior.
Abstract: Because of construction of the world famous.Three-Gorge Project,the local turbulent flow,compared to the original,has been changed greatly.The variation of hydrodynamics results in change of water environment.Based on the features of hydrodynamics and contaminant transportation of the water body affected by constructing the Three-Gorge Project's first- and second stage-cofferdam,this paper establishes a 3-D hydraulic and water quality model.The results of simulation indicate that there is a pollution zone in the area close to the discharge outlet,but the polluted range and the contaminant concentration is not big.Most of the water body is not affected and the water quality is close to that of inflow.
Abstract: The flow velocity distribution in circular ecology channel is investigated.The flow field is simulated by employing the κ-ε turbulence model in cylindrical coordinates.The comparison of the computational results and the experimental data shows that the computation is reliable.The results can be employed to analyze the movement of the snails in the flow.The experiment on the sensitivity of Oncomelania to flow velocity is important to research into the diffusion of Oncomelania with water flow.
Abstract: The geomorphologic dispersion is described by the width function,the hydrodynamic dispersion is described by the channel response function,and a formula of the watershed geomorphology instantaneous unit hydrograph (WGIUH) can be obtained.The geomorphologic parameters in the formula of WGIUH is determined by the digital elevation model (DEM) of watershed.The example is given in order to test and verify the new method.
Abstract: The present models of flood control benefit need a lot of data,and are complex in calculation.In accordance with the problems above,this paper presents the concepts of flood frequency-area coefficient and flood frequency-damage degree coefficient,and infers a macro-model for calculating benefit of flood control systems in a basin on the base of macro-hypothesis in connected with the characteristics of flood control benefit.The results of a case study prove that the model is rational and easily operated.
Abstract: Benefits of flood control engineerings system is very difficult to calculate,and in many cases,they are only obtained by rough estimating.Hydrology,hydraulics,engineering and economic problems of the Yellow River flood control engineerings system are discussed.A systematic calculating model is developed to solve these problems.A 2-dimensional flood routing model is also developed to study flood status in flooding area of the lower Yellow River flood protected zone (120 000 km2).According to real conditions of the protected zone,the estate data,flood loss rate,terrain and obstruction parameters and so on are discussed.The cases studies show that the results are reasonable and the model is effective.
Abstract: A method confirming the flood submerged area is provided.The method adopts the digital elevation model (DEM),GIS,hydrodynamic model and object-oriented data base (OODB) to determine the submerged area.The steps are as followings: first,the whole research region is divided into some small subcatchments and the DEM of the region is established; then the submerged area is distinguished from the whole region under the condition of the given water level calculated by the hydrodynamic model,and is calculated and visualized based on the flood water level,GIS and the DEM data set; last,the submerged area map is overlaid with raster data converted from other thematic vector maps as a result map.Further more,the quantitative evaluation of flood damage can be easily achieved with object-oriented database of social and economic data.The precision of this method mainly depends on the spatial resolution of the DEM.The method was applied to Fenghua River watershed of Zhejiang province,and got a satisfactory result.
Abstract: River is an important water source for human living and production.Management of its water quality and pollution sources is one of the major tasks of river basin management of water environment.All rivers in a river basin form a river network.Some kinds of GIS software provide a module specially for solving network-related issues.Based on an analysis of the features of river water environmental system,this paper studies the method of application of GIS network analysis technology to river water pollution tracing,which include establishment of digital river network model and river water environmental database,integration of associated with river water environmental data,and implementation of river water pollution tracing.In addition,a prototype study has been carried out in the Hanjiang River basin.
Abstract: As an important analysis method in systems engineering,the analytic hierarchy process has been applied in many practical engineering problems of multi-object decision-making.According to the definition of judgement matrix,an analytic hierarchy process based on the accelerating genetic algorithm (AGA-AHP) is presented for comprehensive evaluation of complex system.The priority weights of hierarchy elements can be determined and the consistency check of judgement matrix can be done at the same time by using the AGA-AHP.The results of theoretical analysis and case study show that the AGA-AHP is visual,feasible,effective and convenient,that the computational precision of the AGA-AHP is high,and that the AGA-AHP possesses important theoretical meaning and broad application value in systems engineering.
Abstract: Based on the neural network model of time series and the periodical changing characteristic of the groundwater level in dry region,a seasonal artificial neural network forecast model is set up.At the same time the data smoothing process is carried out aimed at the different fluctuation during different period before these data are used for training.The prediction results indicate that the model is reasonable,its accu racy is better,and has some practical value when being used in the dynamic groundwater level analysis.
Abstract: The purpose of this study is to investigate the influence of irrigation methods on soil fertility during the sabbath period.This study chose two blocks of paddy field,whose soil were turned over after the harvest.One of the blocks was irrigated continually to maintain ponding water and was called continual irrigation field.The other was without irrigation except natural precipitation and was called natural irrigation field.The sampling locations were at four corners and the center of the block.Each location was withdrawn six samples at six layers.Each layer was 10 cm in depth to a totality of 60 cm below ground surface.The soil samples in each layer were air dried and mixed homogeneously by passing 0.42 mm sieve.The mixed soils were analyzed for their pH,EC,organic matter,total nitrogen,effective phosphorous,Ca,Mg,K,and Na.The results showed that organic matter and effective phosphorous increased significantly after sab bath period due to the decay of rice roots.In natural irrigation field,the organic matter and effective phos phorous increased 51% and 88%,respectively.In cont inual irrigation field,the organic matter and effective phosphorous increased 13% and 69%,respectively However,in the natural irrigation field,Mg,K,and Na decreased 35%,24%,and 47%,respectively.In continual irrigation field,Mg,K,and Na decreased 29%,14%,and 41%,respectively.
Abstract: Based on the analysis of experimental data at Guilin Station for late rice,the models of water pro duction function (WPF) for rice and its regularity of temporal and spatial variation are studied in a systematical way.The key problem of use WPF is how to expand the water sensitivity index (WSI).Based on the regularity of the variation of WSI in the Jensen model for rice,the cumulative function of WSI with a growing curve is given out and the characteristics of this function are analyzed,so the problem of conversion WSI be tween different time step are solved.The regularity of the variation of water sensitivity indices with the climate and soil conditions are investigated,especially,the relationships between WSI,the reference evapo transpiration (ET0),and the available soil moisture are presented.Thus,the principle and methods for widening the ranges of time and space for applying the water production function of rice and the principle and methods for drawing the isogram of WSI based on the isogram of ET0 and the soil map are developed.
Abstract: Water plays a key role,and there are many water resources issues for the development in the Northwest China.In this article,based on the analysis on the regional characteristics of water resources in the Northwest China,some aspects which are very important for the west-development,regarding of the ecological environment and its management,tree planting and desert fathering and others were discussed.Finally,the writer pointed out that the west-development depends fully on the available capacity of water resources in the regions,we have to return the water,which should be used for natural ecological environmental system but has been robbed by human,back to its original purpose,and water projects which transfer water from one basin to another one are the ultimate way to solve the water-shortage problem in the west China.
Abstract: Water resources is considered as a key of the development in Northwest China,so its characteristic must be thought enough and accurately.The water resource data in Northwest China is analyzed,which indicate that: (1) the runoff of endorheic drainage is mainly formed in mountain regions,dissipated at basin or plain front of mountain,and supplied by the rainfall,snowfall,glacier and groundwater; (2) Glacier and snowfall play an important part in adjustment of surface water; (3) transformation relationship between rainfall,surface water and groundwater is notable,and (4) The water resources balance of endorheic drainage is easily influenced by the human actions.
Abstract: Water conservancy modernization is a developmental and dynamic process from traditional water conservancy to modern water conservancy.There is different connotation of water conservancy within different areas and different stage.Water conservancy modernization in the information era should include modernized foundation facilities,modernized science and technology,modernized management system and optimized resources and environment.According to the basic national conditions of our country,the aim is to establish water conservancy modernization with Chinese characteristic.Considering the unbalance condition of social and economic development between areas and the lower scientific and technical capabilities situation,the evaluation index system for water conservancy modernization and the level evaluation model are established by referring to the international modernization standard and other department modernization standard for reference some suggestions about the dividing of development stage of water conservancy modernization are put up also.
Abstract: This paper discusses the current research advance in ecological water demand and environmental water demand,including study content,quantitative analysis methods and research achievements etc.On the basis of above analysis,the main existent problems in this field are pointed out1.At the same time,the questions to be studied in the field of ecological and environmental water demand are put forward.
Abstract: A new mathematical method,wavelet analysis which is called mathematical microscope,is introduced.Then the state of application and research of wavelet transform is introduced in the hydrology system,including four aspects: (1) time-frequency multiple time scales analysis of hydrological time series,(2) change properties of hydrological time series,(3) forecasting in hydrology,and (4) simulating of hydrological process.Finally,some trend and directions for future studies in hydrology and water resources are presented.
Abstract: The concept and defining of the water saving irrigation are discussed in the paper.In view of the above,effects of the water saving irrigation were analyzed in detail.The current situation of water saving irrigation evaluation is remarked,and the development of this research field is discussed and reviewed.
Abstract: This paper summarized the characteristics of water usage and situation of water saving in the world,including new technologies,new methods,new products and advanced policies.Both advantage and disadvantage were outlined.In order to improve the efficiency of water usage in china,several suggestions were pointed out.