Abstract: Previous investigations of non-equilibrium and equilibrium sediment transport are analyzed and a two-dimensional mathematical model of non-equilibrium sediment transport in river channels with non-uniform bed material is presented.The concept of exchange rate of bed material is introduced,and a very short time step is used in the calculation.The main reason why the sediment recovering equilibrium distance for the non-uniform bed material is far longer than that for uniform bed material is discussed.Because the size composition of surface bed material is coarsened,the scouring of finer sand is farless than that for the initial state an d the distance of non-equilibrium sediment transport becomes much longer.A slower exchange rate of bed material then leads to a longer distance of non-equili brium sediment transport.
Abstract: Sedimentati on is one important cause of river flooding.Many mathematical simulation model systems for this process have been successfully established.These model system sare very powerful in simulating calculation,but much more weaker in visualization of process data and further spatial analysis.Current GISs are very strong in visualization and spatial analysis.So by integrating with GIS,it is hopeful to resolve this problem.In this paper,a visualized analysing system of sedimentation process is studied and implemented.
Abstract: The navigation channel of Lujiahe Shallow Reach of the Yangtze River is divided into two:sand channel and gravel channel by the channel bar named "qiba".The incoming condition of this reach including flow and sediment has a significant effect on thefluvial process of the navigation channel.Based on the field data and model experiments of moveable bed,the effect of process of the discharge on scouring of the sand channel after the flood peak has been analyzed.It has been found that the sediment deposited in thesand channel during the flood season will be scoured when the flow discharge keeps in the range of 10000～25 000 m3/s.After the construction of the Three Gorges Project,the incoming condition of flow and sediment in this reach will change greatly,in which the duration of the flow discharge keeping in the range of 10 000～25 000 m3/s will increased to some extent,therefore the phenomenon of temporary cutt-off of the navigation channel will be improved.
Abstract: In this paper a new type interceptor sewer system is introduced and a model is establishedto solve the problem of optimal controlby analysing the facts on the interceptor sewer system and a Fortran program is produced for this model.This paper shows that the optimal control states can be determined by working out the optimalflow rates by means of the linear programming.A simple sewer system is conside red in order to examine the model as well as the program and the result is verysensible with interception points and the concentration weight coefficients overtime.The results farther highlight some practical applications for the existing interceptor sewer systems or the systems under design.
Abstract: A BOD5-DOparameter inverse coincidence model is set up in this paper according to the verse theory and the dispersed inverse arithmetic method.The Parameter formulas of the coincidence model are educed.The deoxygenation rate,reaeration rate,deposition and suspend once more coefficient,photosynthesis reaeration and abc warfare breath deoxygenation coefficient,andself-clearing coefficient by space arequantitaively calculated also,giving a new approach for water self-clearing rulereserch.
Abstract: The paper describes the formulation ofwater quality index to evaluate the level of pollution.The developed index system includes the water quality assessment standard,the calculation method and the water quality meaning of index.The water qualityindex system combines the advantages ofwater quality indexes from several countries such as China,U.S.A and former Soviet Union,and isreasonable and simple to practise.
Abstract: This paper analyzes the drought and flood events during Meiyu and summer over the middle and lower Yangtze River.Based on theseanalyses,we study the atmospheric circulation in earlier stage of the drought and flood,and identify predictable the factors lastly.A conception modelis developed,which is of great importanceto predict the extraordinary drought andflood events.
Abstract: According to analyzing the data on the mean monthlysea surface temperatures(SST for short) at grid points in the Northern Pacific,the relationships between SST field and yearly high-flow or low-flow in the upper Yellow River were revealed.The in fluence of abnormal changes of SST on the runoff was discussed.Meanwhile,theregression equation was established andthe data of SST was used to make longterm forecasting test on the yearly runoff in the upper Yellow River.The good effect was achieved.
Abstract: The climatic variations since 1961 over the upper Yellow River were analyzed in this paper.It indicated that the tendency of annual air temperature rising was very obvious from the med and late 1980s,especially the annual air temperature in 1998.From 1990s,the spring and summer temperature were rapidly increased.The precipitation dit not have significant variation tendency in the annual and autumn,tended to increas in the winter and spring,and to decrease in the summer.The effects of the annual flow,rainfall,air temperature,and droughty climate on the water resources were andyzed.The results showed that the water resoures were decreased,and the reductive tendency was very obvious since the late 1990s.This tendency consisted with that of the summer precipitation.It indicated that the reductive precipitation during flood season was the dominant factor of climate for reducing flow of the upper Yellow River.
Abstract: This paperstudied the influence of the sea ice in the north pole area on the runoff in theupper Yellow River during flood season with hemisphere scale from the point of view on the cold source in north hemisphere.The correlation ship between the runoff in the upper Yellow River during flood season and the sea ice in the northpole area was obtained through the statistical analysis.Then the physical mechanism of influence of the sea ice in north polerea on atmospheric circulation and further on the runoff volume in the upper Yellow River were discussed.
Abstract: Based on a new difference scheme,aflood routing method with the forecast period was derived,in which the weighted coefficient of the difference scheme is determined interms of the simulated physical dispersion principle of flood wave by numerical dispersion of the difference scheme,and the stability conditions of this method are obtained.This method was applied to flood forecasting of of the lower Yellow River,and satisfactory results were acquired.
Abstract: Forecasting the water level with tidal effect is difficulty,because it is influenced by flood and tidal.This paper treats the water level as time series and compares thewater level forecasted by some model with observed,the result shows that the neural network model is suitable for tidal river and the ARMA(2,1) is suitable for high level forecasting,but for floodriver,the forecasting ability of all models should be improved.
Abstract: This papertries to analyze and define the basic concept,connotation,researching contentsand analyzing method of water resource srational allocation and carrying capacity on the basis of theory of sustainable developmet and to discuss the relationship between water resources rational allocation,carrying capacity and thinking of sustainable development.This isuseful for the research work in the field of water resources planning and management.
Abstract: This paper int roduces the evolution of transforming engineering water into "resou rces water" in Jiangsu province,explainsthe practice of "resources water "inprimary stage,summaries seven features of "resources water" stage in many examples,presents some key problems which mustbe solved in practice,and researches the development trend of "resources water "in Jiangsu province.
Abstract: This article analyzes the reason and themechanism blocking stream of the Extraordinary mountain slide which was occurred in Yigong river of xizang in April 9,2 000.The possible disaster of what the a ccumulated body of the slide intereptedthe stream water is analyzed also.Implementing structural measures and nonstructural measures of the wrecking and disaster mitigation are introduced.
Abstract: According to the theoretical and practical simulation of isothermal and non-isot hermal movement of water and salt,and boundary with mulch,this paper introduces the status of studying advances in simulation and coupled modeling on moisture movement,heat transfer,and salt transportin soils,especially the soils with straw mulch.Based on summarizing above,the features of concerned models and desirable development are discussed briefly.
Abstract: In traditional study of water flow in vadose zone,little attention is paid to the effect of air entrapment,while this effect is rather important.There take place not only water flow,but also air flow in vadose zone.A better understand of two-phase flow is important to grasp the process of contaminant transport in vadose zone.This paper describes the water flow,air flow and its effect on water flow and the variation of air pressure during the infiltration based on the research in recent decades.The distinction among these results is also analyzed.
Abstract: The article presents the lastest development of Geographic Information System(GIS) and pointsout that the technology of GIS has nowattained a rather high level,and is no longer the most important restrict factorin most fields.Based on the review andanalysis of several typical case,the main problem and trend in application of GIS in regional water environmental fieldis pointed out by the author.
Abstract: Following points have been pointed out:(1) South-to-North Water Transfer Project in China(SNWTP) is not only a water resources project,but also a eco-environment project.(2) The feature of water transfer in North China is discontinuous supplement of water according to situation of water sh ortage,and is continuous supplement of water for the annual in North-West China.(3) A minimum risk ideal is suggested for decision of SNWTP.
Abstract: This paper describes the theretical background of the TOPMODEL and the variable-source-area concept of stre am flow generation as well as the characteristics of TOPMODEL simulating hydrological response using different spatial distributions of the topographic index.All of the TOPMODEL's applications be fore are only limited on hillslope scale,the paper tries to widen the range of its applications and tests its applied result in ordinary catchment.Huaihe basin is chosed as the study area,and the TOPMODEL is made preliminary comparison with the Xinanjiang model.