Abstract: First the general hydrologic cycle models of land-atmosphere system of mainland China scale and regional scale and a set of parameters for describing the features of hydrologic cycle have been developed and calculated.Then,the characteristics of hydrologic cycle of the mainl and of China and its different regions have been discussed and compared.Some conclusions are interested.
Abstract: Regional distributions of the seasonal variations of precipitation and rainstorm which are closely related to the designs and operations of water resources and hydroelectric projects are studied,including seasonal variations of the rainstorm elements:means of ten day precipitation and maximum 1d rainfall,inter-annual variation of rainstorm,depth-area-durat ion relationship,etc..The map of the seasonal concentration coefficient of precipitation is shown,and the similarities and differences for the seasonal variations among precipitation,ordinary rainstorm,and rare rainstorm are also discussed.
Abstract: The problem of two-dimensional unsaturated flow in a hypothetical heter ogeneous soil is analyzed by Monte Carlo simulation.It is assumed that the flow domain is scale-hetergeneous along the horizontal direction but homogeneous in vertical direction,and the locally soil water flow can be described by the Richards equation.The heterogeneity in the soil hydraulic properties is represented by a scaling factor which is visualized as being arealization of a one-dimensional spatial stochastic function,and the NNM model is used to generate realizations for the scaling factor.The spatial distribution of soil water pressure head is quantified in terms of its first-and second-order moment.The results indicate that the variance of pressure head is a function of its mean,the spatial covariances of pressure head assume their steady state form after a short period of infiltration.
Abstract: This paper classifies the flood into several types based on the history flood data by the hierarchical clustering method and builds a fuzzy probability prediction method that is used for real-time flood type forecasting.The result shows that the flood data is predict able to the types in some degree.Then a Bayes real-time dispatching rule is introduced into optimal flood dispatching.
Abstract: In this paper,based on the analytical solution of linear diffusion waveequation with water level,a flood routing model of channel is developed,which has clear physical significance and takes all kinds of effects (backwater and lateral inflow) in the flood wave movement into account,so that it has wide useable range.It doesn't require detailed data of cross sections or river bed geometry but requires only their average values.In this model an excellent means to analyze individual or overall effects of boundary conditions is provided.When it is applied to Jingjiang channel of the Yangte River which is a complex network with join of tributaries and distributaries as well as Dongting lake water system,it shows good results.
Abstract: Based on flux-vector splitting,a conservative and implicit defference scheme is presented for one-dimensional shallow discontinuous water equations with arbitrary cross-section.Numerical simulation has been done for the dam-break problems in the cascade reservoirs with bed stope and friction when the dams are broken at the same time and in succession.Numerical results are discussed.There-sults are reasonable and show that the method is efficient and feasible.
Abstract: To solve the problems of irregular boundaries and free surfaces in CFD (Computational Fluid Dynamics),a modified κ-ε turbulence model is derived,and the governing equations of turbulent flow over irregular boundary are developed by analyzing the solid-liquid two-phase theoretical flow model.And furthermore a partial-cell parameter is introduced to treat irregular boundary.To track free surfaces,a simple but powerfule method is described that is based on the concept of fractional volume of fluid (VOF).By using the established computer code,several typical examples in hydraulic engineering are studied numerically,the results of which are in agreement with experimental data.
Abstract: Based on a new incomplete simiarity assumption of the simiarity theory and the classic Nikuradere experimental data,a power-type velocity distribution formula is proposed for turbulent flow in hydraulic rough region.Corresponding to the new formula,skin-friction laws for turbulent flow in hydraulic rough region in open channels and pipes are presented.
Abstract: A robust estimate method for Hydrological frequency analysis is developed by Combining Huber's M-estimate and Minimum Distance (MD) estimate in this paper.To P-Ⅲ distribution,Monte-carlo results show that the methed presented is robust when the sample is contaminated by some interference data,and simultaneously is better statistical characteristics when the sample is not contaminated by some interference data.
Abstract: Based on the geomorphologic unit hydrograph,the Philip infiltration equation and the rainfall property frequency distribution,this paper presents the model for the estimation of the theoretical frequency distribution and return period of the peak discharge less than or equal to the given Qp through the derivation of the probabilities of rainf all events without yielding runoff using the concept of initial time of runoff and excess rainfall.This paper also gives the examples of the model test and analyzes the prospect of application of the model.
Abstract: This paper discusses main mechanisms contrilling or affacting chemical compositions of lake water mass such as atomsphere precipitation,sediment and water interaction,biological process,soil chemical weathering,crystal zation and evaporation within the lake,describes some methods of source analysis of some chemical components in lake water,and presents some typical problems in environ-mental geochemistry in lakes to be needed to study in the further.
Abstract: The soil column test in laboratory were used to investigate nitrogen transpor and transformation.A new type of tension sensors was used to collect soil-tension data automatically.Through tests of the soil column,enough data were obtained.This paper estimated the soil hydraulic,transport and transformation parameter by using tracer and a combined simulation-optimization approach under variably flow condition.A nonlinear weighted least square algorithm was used to estimate the model parameters by minimizing deviations and those predicted by the numerical model transpor and transformation process.
Abstract: The saturated irrigation tests were carried out in a couple of lysimeters (the levels of groundwater are all 1m) built in the field of Huaibei Plain.The irrigating water was taken from Kuiriver of Xuzhou.The results obtained are summarized as follows:Although ammonium-N is as high as 5.35mg/L in the wastewater,it con't pollute the groundwater directly when wastewater irrigates it in the soil in a normal condition,because ammonium-N is sorbed mainly by soil colloids and is difficult to move.When wastewater moves down,it leaches washing nitrite and nitrate that have accumulated in the soil,and makes their concentrations increase rapidly.After irrigating,with the variation of moisture,oxygen and pH value,the ammonification,nitrification and denitrification are successively the majorcauses of nitrogen trasformation in the soil.During ten days of irrigation,NO2- and NO3- arisen from leaching and nitrification bring about serious pollution in the shallow groundwater.
Abstract: Serious atomization occurs as hydraulic structures discharging high water head and large discharge,producing environmental pollution to hydraulic engineering and pepple's daily life and working conditions.It is an important problem which should be considered.Theories of measuremental methods used in prototype observation are presented in this paper.Radioisotope is applied to measure the atomization concentration in typical area.Stereophotogrammetry is applied to measure the shape and area of atomization flow.And atomization rainfall strength is measured by raing ages.The results provide scientific basis for the safe management of practical hydrauli cengineering and first hand data for the study of discharge atomization mechanism.
Abstract: The aim of the study of losses of fertilizer in drained lands is to investigate the influence of drainage on leaching of fertilizer and explore rational measures of fertilizer application and effective drainage design and management practices for reducing ferlilizer losses from the drainage effluent.In this paper the advances of research both in field experimental study and numerical simulation of fertilizer losses in drained lands are reviewed,and the major to pics to be further investigated are discussed.