Abstract: The paper extends a significant progress both in theory and in application of the prediction of longitudinal dispersion coefficient for natural rivers.The method is based on the hydraulic geometry relationship of stable rivers and on the assumption that the equations used in uniform-flow are still valid for local depth-averaged variables.The lateral distributions of the local flow depth and the deviation of local velocity from the cross-sectional average value are determined for straight alluvial rivers.By using the suggested transverse mixing coefficient equation and the direct integration of Fischer's triple integral,the paper presents a new theoretical equation of the longitudinal dispersion coefficient for natural rivers.The distinct feature of the new equation lies in its involvement of the transverse mixing coefficient.By the comparison with 59 sets of field data and the equations by other investigators,it is found that the equation presented in this paper predicts the longitudinal dispersion coefficient of natural rivers more accurately.Moreover,the new equation is reasonable in theory and clearer in dispersion mechanism as compared to other equations.
Abstract: This paper presents a three-dimensional hydrodynamic model.The bottom friction has used quadratic expression of velocity.In the treatment of vertical turbulent coefficients,the parameterization scheme has been employed with Richardson numbers.A vertical compressed coordinates(σ) was used.With splitting mode technique and alternating direction implicit(ADI)algorithm,the external model is derived by vertically-integrating the momentum equations to solve the change in water surface which feedback the internal model and solve the vertical velocities.Hence this algorithm scheme can save computing time significantly,therefore,this model can be used in deep and small water body,as well as thermocline lakes/reservoirs.Finally,as a example of its application,this model was applied in East Canyon reservoir,Utah,USA.The efficiency of the prediction of thermocline corresponding to the wind forcings and inflow and outflow has been discussed.
Abstract: Recently,the duckbill-shaped elastomer check valves have installed on many oceanic outfalls and diffusers to prevent sea water and sediment intrusion.In this paper,the mixing characteristics of a duckbill valve jet has been studied by using acoustic Doppler velocimeter(ADV) and laser-induced fluorescence(LIF) techniques.The measurement results reveal a complicated near-field flow extending up to about 12.5 jet diameters,within which the turbulence intensity is much higher than that of a round jet,the jet spreading in the major and minor axes are distinctly different,and an axis-switching is observed in this region.Beyond.the near-field,however,the jet mixing characteristics are similar to an equivalent round jet.
Abstract: Supposing the "basic concentration" of each pollutant and substituting the relative value for the monitoring value of pollutant concentration,the parameters in the formula of pollution harm rate of water quality are independent of the characters of pollutants.The formula of pollution harm rate of water quality assessment suited to multipollutant and the formula of comprehensive index of pollution harm are derived by using the genetic algorithm to optimize the parameters.The comprehensive pollution harm index of water quality is calculated by weightting to partial index of pollution harm using the general fuzzy contrast method. The comprehensive assessment method of water quality shows the clearness of physical meaning,easy to calculate,simple to use and the generality and comparison.
Abstract: This paper introduces the WQRRSR and the simulation model for reservoir aquatic ecological system,and analysed the principle of aquatic ecological process in reservoirs and its numerical simulation method,In addition,by adopting the WQRRS model,the ecological diversifying process in Danjiangkou reservoir in 1995 is simulated day by day.The hydrological data,meteorologic data,initial water quality data,dispatch data of Danjiangkou reservoir and water quality data of tributary inflow during 1995 are used for the simulation.
Abstract: To overcome the shortage of current methods which may not be applied in the case of taking adsorption into consideration,a suitable transformation is conducted on the approximate analytical solution which describes one-dimension indoor sandy column dispersion test in the condition of constant injecting concentration and steady seepage,and on the base of this,an analyzing data method is established according to the extreme principle of correlation coefficient.Thia method may be applied to estimate the values of longitudinal dispersivity,retarding coefficient and equilibrium adsorption coefficient if the effective porosity of porous medium is known.
Abstract: A study of uranium disequilibrium in groundwater from the Cambrian-Ordovician(∈-O)carbonate aquifer system,the Mouthspring,southwest of Datong has been undertaken to answer questions pertaining to the development of this aquifer system.An adjacent ∈-O aquifer system,the Deityhead Spring,is differentiated from the Mouthspring using activity ratio of 234U/238U,third kinds of ∈-O groundwater related to strong to weak circulation patterns and aquifer environments are interpreted,too.234U excess is used for identification of many ∈-O subsystems,their mutual relations and the lateral recharge and discharge as well. The source waters of these subsystems are deduced,contributions of these waters are evaluated quantitatively by mixing ratios.The concentration and activity ratio of uranium in ∈-O groundwater are varied greatly,it is seldom seen that activity ratios less than that of the secular equilibrium are found from ∈-O groundwater of the Deityhead-spring.
Abstract: Two-dimensional seepage flow of free-surface over cutoff wall has been solved by conformal transformation method in this paper.By introducing the hodograph plane and utilizing Schwarz-Christoffel transform,the mapping relational formula between the physical plane Z(x,y) and complex potential plane ξ(Φ,Ψ)has been deduced.The main four parameters and integrated constants also have been obtained by joint-solution method.The solution example indicates that the solution method is feasible.
Abstract: The groundwater resources have been seriously deficient since the 1980s in the plain area of Beijing.So it is very necessary to reduce the loss of runoff and evaporation and to use flood water and runoff for recharging the local groundwater.In this paper,about data of twenty years on rainfall and groundwater level observed from the water resources experimental area in south-eastern suburb of Beijing was comprehensively processed.The storage capacity and regulating capacity of 0-3 m layer of soil reservoir in the different hydrologic years were analyzed and calculated.The hydraulic force connections among the different levels of groundwater were revealed.The variation relations between phreatic water,confined water and precipitation were studied,and at the same time it proved that rainfall affected the shallow groundwater beyond one year.
Abstract: In this paper,the scouring and silting can be computed by wmbining the 2-D plane bed load numerical model with the experimental scouring formula around bridge-pier in the whole computational reach and the location around bridge-pier,which takes into account of the interaction between whole flow and local flow condition in river.A reach of Changjiang river near Huangshi bridge is taken as a computational example,which computed local scouring around the brige-pier,and the computational results basically coinside with the measured data.
Abstract: Based on the flow characters of skew bridge crossing and the theory of wake spread as well as decay,the iterative calculating formulas of backwater and relation of bridge aperture design are deduced.In order to verify them,the value of backwater of a skew bridge crossing is calculated.The results agree with the experimental ones.
Abstract: Based on the concept of the numerical dispersion of Kinematic-wave to model the physical dispersion of diffusion wave at a certain condition,the Muskingum-Gunge flood routing method is developed by means of the finite difference method.As for the weighting factor X in the method,hydrologists have not obtained a uniform conclusion for along time,so this paper researches the problem using the Von Neumann and the stability condition of the routing method is systematically analyzed.
Abstract: The bi-directional flow often happens in the downdraft reach due to the influence of main thannel,so that its velocity calculation is obviously different from normal river in practical engineering.In many condition,the necessary hydrologic data and topography is lacked in these downdraft reaches,then the mathematical and physical model are difficult to apply directly.So based on the combination of physical, mathematical model and multivariate regression analysis for typical downdraft reach,a empirical formula is putted forward in this paper,and can be directly used to determine maximum velocity at a engineering point in downdraft reach.
Abstract: The operating and scheduling system of Wanjiazhai Yellow River Diversion Project(YRDP) is a big complex diversion system.Based on this system,the simulation models with three administrative levels, including the system dynamics simulation of water resources supply and demand analyses,the water transfer simulation of hydraulic transition process and the collection and management simulation of hydrographic and engineering data,are established in this paper.The managing and scheduling plan and system characteristic parameter are analyzed by using these models.A new concept,water resources sustainable use amount,is proposed to study the future water demand and the management policy of step by step resuming environment and ecology,and to pmmote water resources sustainable use of water supply area.
Abstract: Based on the analysis of the basic,characteristics of the medium and small river basins,this paper firstly presents the objective and significance of the flood control planning in these river basins.Then the main contents and steps of flood control planning are introduced,and the development and application of flood control planning decision support system in medium and small river basins are described in detail.The application of the decision support system in medium and small river basins will inevitablely promote the research,simplify the process for the flood control planning in medium and small river basins,and also make the flood control planning in these river basins more accurate and scientific.
Abstract: Based on the research on the pilot of Hongru River Basin,this paper introduces the development and application of flood control planning decision support system in medium and small river basins.Meanwhile an anatomization on the relative analysed results is also provided.The case indicates the significance of the utilization of decision support system in flood control planning issues because of the ability not only to speed the period,but also to advance the accuracy of the flood control planning.Therefore it is feasible to pay more attention on the research in this field.
Abstract: A system multiobjective decomposition-coordination macro-decision is ented and applied to the Yellow River downstream water quantity allocation.The results show that the method is practicable.
Abstract: This paper introduces the characteristics and functions of the MATLAB toolbox and explores its application in the areas of hydrology and water resources.Meanwhile some key technical problems are also analyzed and discussed.The author thinks that the toolbox has good prospects in the areas of hydrology and water resources and is worth to popularize.
Abstract: This paper presents a design model of hydroproject management based on Geographic Infonmation System(GIS),and the model is used to develop GIS of the seawall management of Zhejiang.The practice indicates that the model is valid and practical.
Abstract: This paper reviewed the principles of electrokinetics and its application in remediation of contammated soils and groundwater.The electrokinetics is able to drive water and ions to move through soil pores including electromigration,electroosmosis and electrophoresis under electric field.Many researches have demonstrated that high efficient removal of heavy metal ions can be achieved.New developments demonstrated that electrokinetics can also remove organic pollutants alone or by combining with bioremediation synergistically.This technology is convenient in installation,simple in operation,cheap and does not disrupt ecoenvironment,thus is a potential remediation technology.
Abstract: In modern hydraulic engineering,the river training schemes are mainly decided by movable-bed model studies.This paper first reviews the important advances and Latest achievements in the research in similarity laws of movable-bed model of river,and then prospects the developments of similarity laws of movable-bed model.
Abstract: This paper introduces the situation and some recent advances in application of GIS to the field of water resources and water environment in both China and some other countries.Some issues facing the applicanon of GIS to the field are also discussed.
Abstract: In the paper,the new water-saving irrigation method which was named the control root-splited alternative irrigation is introduced.Its conception and saving-water mechanism is discussed.Its research history and status at home and abroad are summarized.The problem existed in application of the method to the field and its developing direction is presented.
Abstract: The reproducible ability of water resources and its influencing factors are expatiated by analyzing the water resources and its basic characters,and the class system of reproducible ability of water resources and a concept model are put forward in the paper.All of above lay a foundation of the reproducible ability theory of water resources.