Abstract: Fundamental issues such as basic laws,supporting conditions,development modes,and evolution control modes,which arises from sustaining water resources utilization,are focused upon in the light of sustainable development theory. Futhermore,a theoretical and practical framework is briefly out lined.
Abstract: Based on the serial meteorological data from Changpin Meteo rological Stations located in the suburb of Beijing the every ten-day period average potential evapot ranspiration(ETp)were calculated and analyzed.The analysis shows that the ETp changes in a strong seasonal trend of which the mean and STD fit to the two-harmonics of Fourier series approximately.Moreover,ETp is a random variable which follows the normal distribution with mean and deviation changing with season.Finally,the probability density function of ETp is given.
Abstract: Based on the theory of energy balance of soil surface,micro-meteorology,moisture and heat transfer in unsaturated soil,an evaporation model is established.Then a fully implicit finite difference method with automatically adjusted time step is developed for simulation.In this model,Neumann condition and Cauchy condition are introduced for the upper boundary of moisture and heat transfer,respectively.These made the model both stable and efficient.The model has been tested using the data of Yerqiang River Basin in North-West China for 31 days.Then numerical simulations are performed to examine the effects of soil type, depth to ground water table and weather conditions etc.It shows that the model can be applied to simulate the soil moisture and heat transfer in long period,and can also be used to find out the relationship between evapor ation and external environments.
Abstract: In this study,the moving mean slope(MM S)model and the moving concentration slope(M CS)model presented by Moldr up et al.for vertical,unsaturated water flow and solute transport are applied to simulate the variation of moisture and solute under infiltration and evapo ration in high clayey soil.Compared with the finite difference method combined with charateristic(CFD),the computational results shaw that the new model has the adv ant age of more efficiency.It is of great importance to predict the long dynamics of salt content in a saline region.
Abstract: A techique to measure the field soil water by using Time Domain Reflectometry(TDR)and its applications are introduced in this paper,including determing soil water content in the root zone and soil water storage for the soil profile;automatic and continuous monitoring soil moisture.The measured soil water can be used to estimate evapot ranspiration in the crop growth season and to evaluate the spatial variability of soil moisture in the field.The three methods of TDR, neutron probe and soil sampling are compared in measuring soil water content.The results showed that the TDR is superior to the other two methods for measuring the field soil water.
Abstract: A correspondence analysis method is applied to dealing with groundwater quality data.It is shown that the groundwater in the research area can be classified as follows:(1)weak alkalinity with low TDS value;(2)strong alkainity with relatively high TDS value,and(3)interg rade between(1)and(2)above mentioned. According to the feed-back information,the existing ground-water quality monitoring points seem to be more than necessary.The optimal analysis is made on the basis of the detailed water quality types,TDS values and the related water-environment characteristics.Although the water quality monitoring points are less than before,they can still reveal the main information from the existing ones,by regular monitoring.
Abstract: This paper proposes a mathematical model and its solution of optimal operation planning for urban storm-flood system in Beijing according to the properties of the system.The simulation technique,multi-objective decision and regression analysis can be applied comprehensively to derive the optimal operation rules of the system.A case study shows that the model and its solution are available and the effect of optimal operation is remarkable.
Abstract: Based on the mathematic model of synthetic judgement with multistage quantization and word picture in the Fuzzy theory,the state of incipient cavitation are estimated,which considers varieties of effective factors that the solid wall surface irregularities and materials of spillway as well as the operation of water conservancy project.As such,not noly thinking over the quantization factors but also making full use of word or language variables,the evaluation method of incipient cavitation has been given in this paper.
Abstract: Heavy rainfall is mainly generated by the mesoscale and microscale synoptic systems that are short life cycle.Presently,the forecast with this kind of synoptic systems can only rely on the combining real-time monitoring by satellite and radar and extrapolating by the conceptual model of the mesoscale systems.Because the terrain is very complex in the Nort hwest China,the terrain creats radar shadow that have influence on estimating rainf all rate.Therefore,the information of GMS-4 satellite infrared and visual stretched image have been used.These data are converted and reduced.The digitial terrain data of corresponding grid mesh of the satellite data are a available factor for use.The multilevel stepwise discriminatory model is used to estimate rainfall rate grade.At last,a set of software system which can be performed false color image display and process of rainfall rate field at micro computer has been created.This system has been satisfied a great need for now casting.The result has been proved that the estimation of area and shape,of hourly rainf all rate grade that is more than light rain,is generally consistent with the real-time rainfall.
Abstract: This review describes the occurrence of mercury pollution in aquatic environment.Much of the review discusses studies of mercury methylation and the opposite process-demethylation.By means of selection of mercury-resistant bacteria or fungi,it shows that equilibrium can be attained between the degradation and synthesis of methyl mercury in mineral mercuny polluted media,such as sediments.Effective water quality management of mercury contaminated natural waters necessitates quantitative models that can predict mercury transformations under various environmental factors.It emphasises that the accumulation of mercury and metyl mercury along food chain is most important polluted way for fish,poultry and human.The toxico logical effects of methyl mercury to fish and humen are also discussed.
Abstract: Based on the activities of International Association of Hydrological Science on the XXI General Assembly of International Union of Geodesy and Geophysics,advances and tendencies of hydrological study since 1990 are delineated from such four aspects as hydrological observation,hydrological processes,hydrological modelling and hydrolo gical characteristics.Scientists have paid more and more attentions to the measurement of soil moisture and ground water quality.With the studyonl and surface parameterization,the research of the middle stages of rain-fall-runoff processes will be strenthened.Scale,sustainability,uncertainty and predictability are still hot topics of hydrology.
Abstract: This paper addresses advances in management of water resource systems and sustainability over the last quadrennium in the light of recent international conference's information,such as the XXI General Assembly of International Union of Geodey and Geopysics that was hold in Boulder,Colorade,USA,July 2-14.Main review involves three parts:(1)Social sustainable development;(2)Recent international advances in management of sustainable water resource systems such as the hydrological basis for water resources management,water resources planning in a changing world,management of water quantity and water quality,man's influence on freshwater ecosystem,water environmental protect and so on.The topic namely biosphere aspect of hydrological cycle was also addressed;(3)The problems and challenges in modeling and management of water resource systems associated with catchment scale in China.The purpose is to provide an out look of recent advances in water resources system and suatainability,which relate to some of the scientific, technologic,and policy aspects of the field of water science and management.