Abstract: Sediment problems in the environment,and enviro mental problems caused by sediment motion are discussed in this paper.Sediment problems in the environment are very common in nature and there exist effects of sediment motion on the environment all the time and every where.It is important and necessary to combine with sediment motion to study environmental problems and to use know ledges of environmental sciences to research on sediment motion.these can be integrated into a subject titled "Mechanics of Environmental Sediment".It studies the law,control and application of pollutant(sediment particles included)transport—transformation in environment.Combining hydrotechnics,that is,mainly hydraulics and mechanics of sediment motion,and environmental sciences,such as, environmental chemistry,environmental geochemistry and hydrochemistry to study environmental problemsr elated to sedimentmotion and to research on sediment motion is its key point.Its reseach contents and methods were discussed by the paper.Thorough research on these aspects will further advance environmental sciences definitely,and to some extent promote and enrich sediment research.
Abstract: This paper simulates the mixing mechanics of submerged,multi-port diffusers used to discharge heated water from stream-electric power plants,and households into shallow receiving waters.The 3-dimensional turbulence modelling and the hybrid finite analytic method are used to predict the dilution behavior of near field for multiple jets in river.The predicted dilutions are good by comparision with available laboratory measureents.A empirical formula for temperaturs dilution in near fields for this kinds is given.It is very interesting that there are bifurcation and Coanda effect in this kind flow.
Abstract: The chemical data from different kinds of waters in the central Guizhou showed that the spring water from the carbonate rock cracks(crack-water)presented neutrality or meta-al kalinity and[C]Ca-Ⅱ.The amount of all ions and the concentrations of HCO3- and Ca2+ were higher in the autumn than that in the spring.The crack-water was influenced by the infiltration of surface water in the process of erosion and/or transportation with decrease in HCO3- and increase in pH, SO42-,Cl-,K+ and Na+,when running in a certain distance on the land surface. The concentrations of SO42-,Na+,Fe3+ and NO3- of the Water fall Huang guoshu river at the Tianxing qiao(upper-stream),Shuiliandong(mid-water fall)and Luoshuitan(down-pool)varied closely with seasons.The CaCO3 deposits violently with CO2 release in the spring.In Lake Hong feng,areser voir in the karst region,the equivalentratio between HCO3- and SO42- was only 2.1～2.4,but for Ca2+ and Mg2+ was up to 2.4～4.2.The concentrations increased in one time for Cl- and in one quantitative level for the Na+ compared to the spring water,which suggested that these increase with solution in surface soils and pollution by mankind.The soil pore-water belonged to strong mineralized water and the lake water presented transitional water.The obvious differences in the water quality resulted from the carbonate deposition,sulphate mineralization and nitrogen fixation as well as ammonification.
Abstract: In 1987～1995,precipitation,water from Black River,groundwater from Gurinai grassland and its vicinity were sampled positionally and periodically, groundwater and lake water from gobi and desert were sampled stochastically during the expedition into Badain Jaran Desert.Isotope composition of precipitation with its δD～δ18O fits the Craig Line while that of groundwater with anunusual deuterium excess of about -22‰ was found in this area.The formation of this isotopically anomal ous groundwater,however,is still not clear.The engineering impact of the planned Black River Project on groundwater is evaluated from comparing isotopic composition of waters.It seems unlikely that it would intensify the ongoing desertification of the Gurinai grassland area in the near future.But it seems to be important for the area by the Black River and,the Ejin Oases.
Abstract: The serial daily potential evapotranspiration was calculated from meteorological data collected from the Yucheng Comphrensive Experimental Station,Chinese Academy of Sciences.Based on the serial data,normalized ETP series (NETP)were generated with the mean of ETP removed and the residue dimen-sionalized by standard deviation.Furtherly,a discrete AR(1)model was constructed for NETP.On the basis of the discrete AR(1)model,the corresponding continuous parameter model,namely A(1),wasest up and the coefficients invol vedestimated. A(1)is a first order stochastic differential equation.The probability density function,autocorrelation function and spectral density function associated with the A(1) were obtained analytically.
Abstract: The runoff modeling in the watersheds where there is lack of hydrologicoal data is amportant and difficult prolbem in Hydrology. In this article, one hydrological model which can be used to model runoff in a watershed only using its geo-eferenced data based on a Geographical Information System was presented. In this model, the Runoff Curve Number method of SCS(Soil Conservation Service of American) was a used to calculate the generated runoff volume in a storm, and one revised unit hydrograph was proposed based on the triangular shape unit hydrograph of SCS and used to route the runoff into discharge at the outlet of thewatershed. In this paper, how to determine parameter values using geo-eferenced data of the watershed was discussed, and finally,the application of the model in the Dodder watershed of Ireland was intoduced as a case study.
Abstract: The normal equation of linear regression is used to calculate the effects of high frequency components on the determination of secular trend of relative sea level(RSL).It shows that the periodic variation components(with period from several months to 18.61 years)have significant effects on the determination of secular trend of the short-time gaugerecords.The maximum flat filter which cut-off period is 4-year has been designed to filter out the high frequency components(with period less than 4 years)of monthly mean sea level.Secular trends of RSL are determ ined by the linear regression of low-passed gauge records.
Abstract: The turbulence Fractal feature is confirmed by analyzing two turbulent fluctuation pressure tem poral signals.Firstly,the correlation dimension of the turbulent fluctuation pressure temporal signal had been calculated and connected with the dimension of the figure structure drawn in the phase space of the dynamic system.The calculated results show that the correlation dimension DC is tended to a
Abstract: Based on the Kilman filter theory and Muskingum method,the half-self adaptive updating Kilman filter model of channel flow routing has been developed for real time application of flood forecasts.In the model,the measurement error covariance matrix can be estimated in real time throught on the innovation sequence. A reasonable and simple model is used in the inflowerrors.The examples show the model are reasonable.
Abstract: In this paper,the pheno menon of "over fitting" of ANN is studied.A new method called control led-weight is proposed to improve the generalization ability of layered forward neural networks.Its efficiency is given by using daturm from the field of hydrological forecasting.
Abstract: According to the mechanical condition of incipient motion of the non-cohesive uniform sediments and using some results of other researches,the relationship between incipient probability and flow condition is established.The for mulae of incipient shear stress and incipient flow velocity in which the incipient probability has been taken into account is obtained,the incipient criterion has been connected with the incipient motion condition.The analysing of some typical formulae for incipient motion condition of non-cohesive uniform sediment shows that the formulae of this paper is rational.
Abstract: This paper introduces the application of neural network expert system to bed rook fissure water prospecting,including the composition and structure of neural network expert system,and training of the neural network.The trained networks are applied to the prospecting of a bed rock fissure water source field in Jilin Province,the results are good.
Abstract: Since the latest 20 years,a greal progress has been made in the theories and computational methods in flood routing.This paper places stress on intro ducfion to developments in small disturbance analysis of flood wave,hy draulics flood routing methods,and application of new technique to flood routing in China and other countries,and gives brief reviewson them.
Abstract: The basic principles of genetic algorithm are summarized in this paper. Agreat deal of researeh works and more details about applications of genetical gorithm to the problems of optimization in water resources systems and power systems are discribed.Then future works are also proposed.
Abstract: The paper analyses the definition,the quantity and the evaluating methods of the water resources,and points out that the view of water resources decline is untenable.The water resources keep constantly the dynamic equilibrium.When the series length in the sample is not same,the average value should be differeent too.Actually,the problem for runoff decline should be analyzed from the aspects of rainfall and humanactions,and not simply decided.