Abstract: A dynamic model on interaction between water particles and trace organis chemicals was presented on the basis of the research of adsorption,hydrolysis,biodegradation and algae accumulation in water.The concentration distribution of dimethlyl phthalate and dioctyl phthalate in aquatic environment was calculated by using the model.The results show that the concentration of phthalate esters in algae and particles in higher than those in water.
Abstract: In this paper tee diffuser discharge wastewater is presented.The mathematical model and calculational method are used to predict the flow phenomenon of tee diffuser discharge.The developments of the centerline velocity,concentration and dilution are calculated.The length of the main current core,the transverse velocity and concentration are given.The kinetic energy of discharge and the length of tee diffuser are found to have strong influence on the characteristics of tee multiport diffusers.
Abstract: An optimal irrigation and drainage non-linear programming model is proposed with the concepts of soil salinity threshold and critical underground water table,aimed at preventing soil salinization in irrigation district,furthermore,combined with the real conditions of Xinjiang Kongliu Unity irrigation district to approach the model.The solution of the model gives the optimal irrigation and drainage policies,regulation process of under-ground water table,variation process of soil salinity in the different crops planted area over a year,optimal leaching water over a growing season and preplanting leaching water for different crops aimed at preventing soil salinization for four typical years(P=20%、50%、75%、95%).
Abstract: Using the theory and methods on large scale systems and fuzzy mathematical programming theory and method,this paper studies fuzzy optimal operation of the multireservoir power system,while develops the fuzzy optimizing dispatching model.And an interaction balance-fuzzy programming(IB-FP) method is devised.Theoretical analysis and a case study shows that the fuzzy optimizing dispatching model and IB-FP msthod are very rational and effective.
Abstract: In this study,one mathematic model witch combines the simulation model with the optimum technique is established.it can be used in the operation and management of large scale water transfer project.In the model,the different objective functions,water user,irrigation region and season are considered in the obective function.The Operation Guide Curves for the project,one multiple cascaded reservoirs system,and their optimization are discussed based on the analysis of the project features on the opreation.
Abstract: The water reticulation is regarded as a continuous medium and water movement in the system is analogized with that in porous medium in macro-scopic scale.The expression of water movement in the system has been derived under above conditions.The model in Tai Lake Area has been developed with the method and the results are reasonable.
Abstract: A one-dimensional unsteady and non-equilibrium transport mathematical model is presented.It may not only be used to simulate the water level,discharge,sediment concentration and sediment deposition when the Yellow River intruding into the Weihe River,but also be used to calculate the water and sediment of a reach which has two-direction velocity or tributary inflow.The verified results show that the model can simulate the whole process of the changes of hydrologic and sedimentary elements in the downstream of the Weihe River.
Abstract: Based on the field survey in the Hukou Waterfall reach of the Yellow River,the headward erosion rates of the waterfall during the different time periods tracing back to about 4000 years were obtained.The historical runoff time series within the last 4200 years were reconstructed by referring to the ratio of water volume of the waterfall measured presently to the width of the stone trough formed due to the waterfall.The temporal variation of paleo-water volumes on the basin up the Yellow River-Hukou has been worked out,also the thousand-year-scale comparison of its wet、dry,peak and trough periods with the warm cold,wet and dry periods of the ancient climate、the movement and fall of the fourth era in western china、and the formation and break of the ancient soil along the sides of the yellow River,has been presented.
Abstract: Based on the relationship between monthly mean discharges and maximum flood peaks,a flood frequency assessment model is established,and nonparametric method is used to estimate the conditional probabilities of each discharge class.Using the monthly water balance model,the sensitivity of flood frequencies and discharge peaks for changing climate conditions have been analyzed and tested.The results indicate that flood frequencies and peak discharge are more sensitive to precipitation variation than to the temperature increase.In Dongjiang and Hanjiang river basins,temperature incerase 2℃ and rainfall changes between plus 10%-20%,the occurrence of a two-year flood frequency will increase from 19.1% to 47.4%,annual maximum peak discharge which return period is 20 years will increase from 10.2%to 24.1%.
Abstract: In this paper,based on the exprimental results of a testing flume model,a systematical study on sediment deposition caused by circulating flow in the cecum branch is made.Details on the model of deposition,the size of infiunce zone,the variation in size distribution of sediment depositions and the properties of riverbed deformed are discussed.The main factors which influence the sediment deposits are analysed,and a formula to estimate the sediment deposition rate in the closed thannel is also established.Finally,a project measure for control sediment deposits is presented.
Abstract: An experimental research on river bed deformation near piers is reported in this paper.The flow structure and river bed deformation near piers when an angle exists between the trend of piers and the direction of main-flow will be different from those when the angle equal to zero,such as the flow-obstructing width will increase,the diversion function will occur,the partial scouring pits get larger and deeper,and the main-flow and thalweg within a certain distance downstream the piers will deviate to one side.
Abstract: This paper designs an experiment of catching and controlling the precipitation by means of covered ridge planted flute in semi-arid field as one way of controlling soil-plant-atmospheric continued system,for receiving and storing precipitation fully and decreasing evaportranspiration and flow-out of water-soil-fertilizer causing by flow and proposed hydrologic balance equation of semi-arid field flut.This experiment indicats that the water input is increased,the water output is decreased,the soil moisture is increased and conserved well in the plant flute by using this means.It's not only advantage of anti-drought and rich crop and build up the stable hydro-control semi-arid agriculture,but also advantage of decreasing the flow-out of water-soil-fertilizer.It has obvious economic effect and ecologic effect.
Abstract: In this paper,the status of studies of crop-water production functions both abroad and within our country is introduced.The prevailing yield response models are classified into two categories:final crop yield model and dynamic crop yield model,the specific features and conditions of application of both kinds of models are analyzed.Besides,the methods for testing crop-water production function and design of experimental treatments are also discussed.
Abstract: A gap exists between theory study and practice of water resource system analysis approach at home and abroad.Some foreign experts consider that a hopeful approach closing the gap is the decision support system for water resources planning and management(WRPM-DSS).In this paper,a comprehensive review of study and practice for WRPM-DSS in the West in the 1980's is summarized.A brief introduction of study and practice on this field as well as their prospects in China is presented.