Abstract: The flood disasters took place very often in the history of the lower Yellow River.The main flow shifts frequently on the bed within the both dikes,which is silted seriously year after year.After the Xiaolangdi project is completed,The deposition and fluvial process of the lower Yellow River may be greatly changed.The paper discusses the fluvial tendency and makes a conclusion that the lower Yellow River will become trained gradually.
Abstract: In this paper,taking the nonuniform flows in lateral trenches as research object,a series of schematic model tests in flume are used to study the variance laws of surface velocity and near-bottom velocity under the condition of different incident flow conditions and slope angles of trenches.Moreover,the relevant empiric formulas for calculating the negative mean velocity and the positive mean velocity are derived.
Abstract: A new method called Neutron Activate Analysis Tracer Method(NAATM)for studying soil erosion was formed through combination tracer method with neutron activate analysis technique,and the method was used to study the erosion process on slope.The research results showed that the changes of relative erosion amount with the distance from slope bottom to top accord with the Weibull distribution.The shape parameters of the Weibull distribution are mainly affected by precipitation,duration of rainfall and depth of runoff,and the scale parameters are related with aver age rainfall intensity and I30.Soil erosion and deposition happened at the same time on slope.Generally,deposition is less under the short duration rainfall with high rainfall intensity than that of long duration rainfall with low intensity.The relationship between deposition amount at acertain slope position and its distance was derived.The runoff directly affects delivery ratio(DR).When the depth and coefficient of runoff is large,the DR approaches 1,otherwise the DR will decreases.
Abstract: The basic concept and several characteristics of entropy are introduced,and the different computing metheds on entropy are compared. Based on the spatial distribution of entropy,the paper studies the directional information transfer index between gauged stations,with which the spatial construction of precipitation distribution is revealed,and some natural conclusions are obtained.According to the studies,it is one of effective roads to use the entropy to research uncertainty in hydrology and water resource.
Abstract: The Information transfer function model is set up on the base of numerical simulation,so that the information transfer study is transisted from dispersed states to continuous.The information distance and the information field are defined,and the information transfer is extended from only one direction to an area.Finally the nonuniformity on precipitation distribution is studied further using the clustering method.
Abstract: In this paper,a mathe matical model for calculating the air demand of the aerator is established,and the target mathematical function for optimizing the shape of the aerator is proposed.The aeration character and the optimum shape of a prototype aerator are investigated.The optimum area of the air slot and the optimum height of the ramp or step are calculated.The results are in good agreement with the measured data.The method proposed herein may be used for preliminary design purposes.
Abstract: The phenomenon of the free overfall is studied here assuming the steady flow to be two-dimensional,irrotational and frictionless and accounting for the presence of gravity and two free curvilinear boundaries.The boundary integral equations for calculating 2-D potential free overfall flow with both free surfaces are derived by using the Riemann-Hilbert mixed boundary problem technique of analytical function.The numerical calculation on the physical plane shows that this method has the advantage of fast convergence with small calculating quantity and high accuracy,and applicable to the complex shaped boundary without special requirement to the initial inputted value.Comparison with the experimental data indicates the present computations allow fair determination of all flow quantities with high accuracy.
Abstract: With the rapid development of new theory and new problem,the current trends in the areas of water resources research are reviewed in this paper.On the other hand,the concept of water resources,in the eye of time,is defined again.Furthermore,the hydrologic replacement time and its relative theories are introduced to determine the water availability from ground and surface water sources.
Abstract: This paper describes the stochastic basin model in the study of impacts global climate change on the water resources.With recent GCM experiments results for 2010-2039 and 2040-2069 presented by IPCC,the possible change of runoff volume for different freguency in Dongjiang River basin has been calculated and discussed.
Abstract: Based on the principle of system,a basin,taking water as a intermediary,is regarded as a open and complicated system through the interaction between mankind and nature,and asustainable development model of the basin system proposed.The mechanism running of sustainable development of a basin system is analyzed,the index system of sustai nable deelopment and its fundamental structure are established.A synthetical measurement method combining analytic hierarchy process and neural network is proposed.Form static state and dynamic state,this method is used to measure the sustainable development of upper reach of the Minjiang.
Abstract: The DRASTIC,one of the wildly applied systems for aquifer vulnerability evaluation in the world,is introduced and the main problems in it are analyzed.The fuzziness exists in aquifer vulnerability and its assessment are discussed.Then a fuzzy pattern recognition model is presented and the conventional describe language for accessing aquifer vulnerability is suggested.A case study,in which the DRASTIC system and the fuzzy pattern recognition model are applied respectively,is conducted.The results of comparison between the two models show that the fuzzy pattern recognition model is more effective than DRASTIC system.
Abstract: The "strong" and "weak" of ground water flow are the typical fuzzy concepts.For the sake of the accurate classfication of hydrogeological parameters and establishment of hydrogeological concept model,this paper proposes a fuzzy partition model and verifies and tests the model with a practical situation.
Abstract: It is a key problem to study the fuzzy optimizing multi-dimensional dynamic programming model for water resources systems.The paper establishes a fuzzy optimizing multi-dimensional dynamic programming model based on Chen Shouyu's theory and the optimization model for multi-stage and multi-objective systems.The model is used for water resources planning and yields satisfactory results.
Abstract: The optimal hydroelectric operation model of cascade reservoirs during flooding periods is presented in this paper.The formulated model including river flood routing equations is the kind of dynamic programming model without Mar kovin property.Then,two new corresponding algorithms,simplified multi-dimen sional dynamic programming algorithm (MDDPA) and progressive optimal algorithm (POA) for dynamic programming models without Markovin property,are proposed.A case study is given.The result shows that these two methods are feasible,especially the latter has higher computing speed.
Abstract: This paper analyzes the hydrologic informations of some river basins in forest cover in loess hill region of Gansu Province,showing the forest cover in the region contributes to increase precipitation,regulates obviously storm-flood and annual runoff,and improves efficiently microclimate,soil and water conservation.
Abstract: This paper gives the review on macropore flow research in soils,including the researching history and the study methods of macropore flow.It also discusses the details of two-domain model and points out the existing problems of recently research.
Abstract: This paper reviews recent advances in numerical simulation of two-phase flow and contaminan t transport.Many methods on deriving the primary parameters and the generalization of some physical processes are summarized in two-phase flow simulation.Mea nwhile various solving algorithms to the two-phase flow equations and contaminan t transport equations are reviewed,and t heir merits and shortcomings are summarized.Hence further issues to be solved are put forward.
Abstract: It is one of major content of "resources-water conservancy" to strengthen the water deman management.With protruding incerasngly the contradiction between water demand and water supply,this paper analyzes the major reasons from water supple management to water demand management,persents a series of countermeasures,points out some problems as before,and looks forward to the development trend of water resources management.
Abstract: On January 22,1998 the 12th Conference of Rhine Ministers adopted the "Action Plan on Flood Defence" in Rotterdam,Netherlands,implying expenses of up to 12 billion ECU.This Action Plan aimed at the improvement of precautionary flood protection will be implemented within the next twenty years.Its content and countermeasures,as well as the thinking and models for sustainable management at watershed level in Europe can be taken example by the flood protection and floodplain management in our great river catchments in China.