Abstract: According to the quantity conservation principle of any grain sediment during the sediment transportation course,this paper,based on the former research,builds a one-dimensional unsteady sediment-laden flow equation.By introducing the concepts of particle diameter and a balance state of scouring and depositing,this paper sets up a formula about particle diameter of scouring and depositing material and brings forward an integrate method for calculating the suspended load and the bed load exchanging.This method is introduced to one-dimensional expanded sediment numerical model.It is verified by the typical flood in 1977 and the scouring series from the end of flood period in 1999 to its the beginning in 2002.The result shows that this method may preferably simulate the exchanging course between suspended load and bed load.This method gets over the limitation of the former one based on the transferring capacity of grouping sediment,and improves the calculation of the non-uniform sediment in theory and may be more perfectian application.
Abstract: The behaviour of absorbing nitrochlorobenzene (NCB) by the Yellow River sediment is investigated.With the stat experimental,the result of the experimental study about the sediment shows that about two hours is required for the sorption equilibrium.Furthermore,the mechanism of the absorption and the factors controlling the organic substance absorption from the sediment are studied,including the sediment concentration,pH,and the ionic strength.It is concluded that the adsorbent amount increases with the absorbent equilibrium concentration,and decreases with the sediment concentration.Under the experimental condition,the adsorbent amount of NCB decreases with the increase of pH and increases with the ionic strength.
Abstract: The cations in natural river would influence the velocity of sediments especially the fine sediment.The main reason of settling velocity affected by cations is the flocculation of fine grain sediments.On the basis of the experimentation of sedi ments settling in water with differentions concentration,the relationship between settling velocity and the positiveions concen tration is given.The positiveions include Na+,Ca2+,Mg2+ and Al3+ etc.The way used in the experimentation is called the pipette way.The results of the experimentation show that the press can be divided into two phases: ①The settling velocity will increase when the concentration of positively chargedion increase; ②If the concentration of positively chargedions are excess of some critical,the settling velocity would not be change,or changed a little as the concentration increase.When different positively charged ions have the same concentration,the ion with higher valency has more influence on sediments settlement Analyzing the characteristic of hydrochemistry in accordance with the data from the Yangtze River and the Yellow River,we can know that it is necessary to consider the effect on sediment settling velocity by the concentration of cat ions on condition of the ion concentration in the nature river.
Abstract: By placing different rare earth elements (REE) in different soil depth and different section across one slope in an indoor plot,one simulated rainfall was applied to study the spatial-temporal process both of depth and section erosion across one slope plot simultaneously.The results indicated that the REE tracer technology has high precision to quantify the spatial-temporal process of soil erosion; In earlier rainfall course,the development degree of sheet and rill erosion was general equation; Otherwise in the following course,the rill erosion was dominant in the total erosion,its average erosion acceleration and the average erosion rate was 15 and 9 times of sheet erosion,respectively; In the end of experiment,the rill erosion took up 90% of total erosion amount; The section of slope bottom occupying about 1/3 slope area was active erosion segment in this experiment.
Abstract: In order to further show the underwater terrain terrain evolution mechanism of the Pearl River networks,we employ the techniques of 3-D visualization and spatial analysis.The comparision with 3-D data of different period will help to expose the underwatr terrain evolution and forecast the trend of the evolution of the Pearl River estuary.In addition,in view of the problem of the elevation value rectified,we present the methods of zero value line and the field identification.The method of zero value line is based on that of point radial.But this method exists the disadvantages,such as the extra computation.The method of field identification is proved to be an efficient method.
Abstract: The dispersion of the contracted jet from a spillway with flaring gate piers for high arch dams depends on the distribution of the velocity at the exit section of the jet.In this research,a 3-D numerical simulation of spillway with flaring gate piers is presented with the volume of fluid (VOF) method for the free surface flow in order to find out the hydraulic features.The results show that four kinds of flow patterns emerge,depending on the water heads over the weir and the geometrical meters of the flaring gate piers.The discharges and water surface profiles from the numerical modeling agree with the experimental results from different flow patterns,including free over-fall,shockwave,hydraulic jump and subcritical flow,which verifies that the model is suitable in this situation.
Abstract: The normal depth plays an important role in hydraulic calculation.To a compound channel,when water in a main channel flows in an out of bank condition and onto the adjoining flood plain,it results in great error if the normal depthiscal culated by the Manning equation.All kinds of methods predicting the normal depth in compound channels are systemically summarized in this paper.In all the methods,the normal depth is solved by the dichotomy method and compared with different series of experimental data from Engineering Research Council Flood Channel Facility.By comparison,it is found that the calculation precision is high with the methods considering momentum exchange between the main channel and the floodplain.According to the order from high precision to low,they are,in turn,the channel coherence method,the Liu Peiqing‘s method,the cross sectional inclined division method,the momentum transfer method,the Xie Han-xiang's method,and the superposing cross section method.By analyzing the advanteges and disadvantages of the methods mentioned above,it is pointed out that the channel coherence method is a good method in calculating the normal depth in natural rivers with compound cross section.
Abstract: A flood control operation model for Linhuaigang flood control project on Huai River is developed in this paper.The model is based on the middle breach of Huai River from Runheji to Lutaizi sections,which combines with 1-D for the branch and 2-D model for the main river and flood retention basin.The verification of the model is carried out by using flood of 1982 and 1991 data.They show that the results using this model are good agreeable with the field data However,the model can be applied to forecast the flood process and determined optimal operation modes for Linhuaigang project and flood retentions.
Abstract: The dynamic mechanism of stratified shear flows in strongly curved flumes was experimentally studied.Three physical models,with straight flume and strongly curved flumes with 90°and 180°bend,were set up respectively.Two-layer flows with different velocity and temperature were produced by using the two independent inflow systems sets.In this experiment investigation,the different flow statuses from the obvious stratified flow to strongly entrainment were studied under the different velocity ratio between upper layer and lower layer.The distribution of velocities,temperatures,turbulent kinetic energy and the Reynolds stress and transect secondary flow were systemically measured and presented with some equipments such as ADV,infrared thermograph and digital thermometer,etc.The dynamic characteristic of stratified flows in curved flumes was revealed and compared with that in straight flume simultaneously.
Abstract: The spatial variability of hydraulic properties is the basis of stochastic research on groundwater.The hydraulic conductivity is the most important parameter.There is still no exact answer to the question about the distribution of hydraulic conductivity though studies dealing with this topic are numerous.In this paper,a discussion of Sudicky's (1986) field experiment for the geostatistical characterization of the hydraulic conductivity at the Borden aquifer in Ontario,Canada is performed by using the different schemes of the data disposal.The results of the analysis suggest that the distribution of hydraulic conductivity is lognormal by using the appropriate method.In addition,some useful advices are provided for carrying out the field study on the spatial variability of hydraulic conductivity in the future.
Abstract: The shallow groundwater seepage,which appears as infiltration from soil profile and from fissure of weathered rocks at the bottom of slope or on the way out of valley,is a ubiquitous phenomenon in the gneiss area in the Taihang Mountains.Collection of shallow groundwater is an important part of rain-water use in hilly areas in North China.The interactions between atmosphere,surface,soil,and fissure water systems are the focus of the study.By measuring water content and water potential in rock and soil,the hydraulic characteristic curve of soil profile and rock in slope was developed.Based on curve,the complexity and spatial variability of hydraulic characteristics on slopes were explained.Two new techniques related to the collection of shallow groundwater were suggested to help the traditional rain water collection and utilization in the Taihang Mountains.
Abstract: The heterogeneity of agricultural soils leads to the complexity of flow and solute transport.To improve the efficiency of numerical simulation,some parameters must be upscaled.In this study,we take the numerical simulation of atrazine leaching through unsaturated soils at field scale as an example,by taking 100 soil samples from a field plot with an area of 27 m×27 m,located in the eastern suburb of Beijing,and analyze their main physicochemical properties.The hydraulic parameters of the van Genuchten‘s type for all soil samples are generated by using pedotransfer function,and the dispersivities of atrazine transport are indirectly estimated by using the hydraulic information.The adsorption coefficients of atrazine on the soil texture are indirectly calculated,too.On the assumption of column model,the atrazine leachs in the soil on the condition that the rainfall infiltrat ionredistribution is simulated.Firstly,the dynamics of the soil water matric potential and the atrazine concentration in individual soil column are simulated by using 100 simulat ions of HYDRUS-1D software,and then their mean spatial distribution is obtained from the results.Secondly,the dynamics of soil water matric potential and atrazine concentration in an equivalent porous media is simulated by using the effective parameters and one simulation of HYDRUS-1D.In this paper,the emphasis is put on discussing the effect of the equivalent effective parameters,being calculated by the power law averaging technique,on the numerical simulation of the mean distribution of soil water matric potentia and atrazine concentration at field scale.It is shown that the upscaled numerical simulation of high accuracy can be obtained,when the geometry mean or harmonic mean values of hydraulic parameters,transport parameters and adsorption parameters are taken as their effective parameters,while the arithmetic mean of soil water matric potential of normal distribution under initial condition is taken as its equivalent quantity.
Abstract: The effects of runoff from upslope on rainfall infiltration,wetting front movement and soil water redistribution are studied based on the simulated rainfall at a planar slope,while soil erosion is prevented during rainfall infiltration and evaporation is stopped during soil water redistribution.The results show that when initial soil water content is very low,the infiltration rate at hillslope with runoff from upslope has an increasing process but the average one decreases,compared with the rainfall infiltration without runoff from upslope.Runoff from upslope has a marked effect on wetting front movement at the beginning of rainfall infiltration due to upslope runoff infiltration,and then has a little effect,which implies that the wetting front movement mostly depends on the matric suction.The wave distribution of soil water along hillslope results from the fluctuation of overland flow,upslope runoff infiltration,and lateral downslope flow.
Abstract: For the over exploitation of groundwater worsens the environment,the early-warning model about the ground water resource management is established.The model takes the urban area of Changchun as an example,and the geological and hy drological condition are considered in this paper.Based on the geological and hydrological conditions of the urban area of Changchun,the criteria of the water level and water quality are ascertained.According to the model,the early-warning system of the ground water resource management is programmed.And with the programme the early-warning performs for the water level and the water quality under the exploitation condition in the future or nowadays.Accordingly the reliable warrant and guar antee for the scientific management and the continuable utilization for the water resources can be offered.
Abstract: THe indicator system and assessment methods for sustainable utilization in relation to water resources are one of core subjects of the sustainable water resources management.Based on the complex system theory,we define water resources,society-economy and environment as a complex system.With the Bossel's orientor indicators framework of sustainable development,the indicator system for regional water resources is established.In the assessment process,the maximum deviation sum of squares from the reference state,which is based on the Bossel's evaluation criteria,is used to calculate the weight value by means of systematic comprehensive assessment method.And the comprehensive assessment value model and the development potential model of RSWRS are presented.The models are applied to the assessment of the sustainable water resources in Shaanxi Province.
Abstract: Water resource carrying capacity relates to economy,environment and other resources.It has dynamic,synthesis,spatial variance and other characters.Combined with the characters of water resources carrying capacity,an evaluation method for water resource carrying capacity under the basis thoughts of asset liability analysis is established in this paper.Finally,demonstrated with Zengdu District of Suizhou City,Hubei Province,the satisfactory scheme on the water resource sustainable development is obtained.
Abstract: In the paper,the integrated research of characters,objectives,models,principles,index system and affecting factors of trans-boundary water resource allocatio is done: (1) the research progress in the trans-boundary water allocation in the past 10 years is summed up,and then the new development tendencies related are concluded; (2) the key issues and difficulties on transboundary water allocation are judged through the analysis on the characters of trans-boundary water resource in both aspects of the natures and the international laws; (3) the water allocation models as the whole allocation,the project allocation and the integrated watershed planning allocation are systematically analyzed; (4) the technical index system is brought forward,their affecting items are discussed,and the major index are defined based on the analysis of allocation principles of the trans-boundary water; and (5) the relative suggestions for the allocation of trans-boundary water resources in China are put forward.
Abstract: When the input includes several regimentations and the number of some variables in some regimentations is much more than that of the other regimentations,the former will weak the latter's effect on the output,which leads to the augment about the forecasting error of the model.The entropy based the self-accommodation back propagation neural model is introduced to solve this problem,in which the several variables of each regimentation are weighted according to their importance,so each regimentation is turned into one input respectively in the back-propagation (BP) net work model.The improved model can take the all kinds of inputs into account entirely and reasonably,and boost the forecast accuracy,which develops the applied theory of the neural network.
Abstract: The principles and the application of microwave radiometer are briefly introduced before the DMSP F-series satellite SSM/I data over the antarctic ice sheet are analyzed.The microwave brightness temperature (Tb) isoline,combined with the topographic contour line of ice sheet,interprets the characteristic of brightness temperature distribution in Antarctica.Time series (1992-2000),daily SSM/I Tb data from eight specific study regions are analyzed to understand the characteristic of Tb,seasonal and interannual changes and the sudden fluctuation over the different Antarctic ice caps and ice shelves.The research implies that the Tb value of the coastal ice shelves and the Antarctic Peninsula are increasing rapidly,while the inland ice sheet keeps stable.It is concluded that the surrounding ice shelves and Antarctic Peninsula are in increasing melting due to global warming.
Abstract: A model for the regional surface energy-balance and daily evapotranspiration is applied to the farmlands in the North China Plain,and the experiments at Luancheng Agro-ecosystem station,Chinese Academy of Sciences are made to test the accuracy of the model.The results show that the model can successfully estimate the surface daily evapotranspiration and the components of the surface energy-balance with the inputs of LANDSAT-7 Enhanced Thematic Mapper-Plus (ETM+) data and synchronous surface observation data at the experimental station.The frequency distribution of the daily evapotranspiration and the NDVI is different in different crop growing seasons,which is mainly caused by the different vegetation indexes.
Abstract: The mathematical analysis method can't be applied to deal with the complexity of the geography and the mathematical statistics method and to analyze the cause of the formation in establishing a water enviroment capacity model in a complex river.The geographic information model (GIM) is a better method to complex geography and a model that combines the inevitability with the chanciness of the geographic phenomena.In this paper,the water enviroment capacity (WEC) of Guilin section of Lijiang River,a complex karst,is studied by using GIM,the application of the GIM to water environment capacity calculation is discussed,and a GIM model is established and is validated.The result shows that the GIM method is a simple calculating method and can reach a perfect result when it is applied to calculate the WEC in a complex section of a river.
Abstract: This article brings forward 8 indexes for evaluating the irrigation management level of the irrigation area,aiming at the country-wide large irrigation area's continued allocation facilities construction and the water saving reform project.We adopt the principle of the factor analysis system to build up the comprehensive index for evaluating irrigation management level of irrigation area-comprehensive factor,with which the result shows it obeys the normal distribution,and brings forward the relevant standards on this basis.The result shows that it can reflect thoroughly the performance of the irrigation management and picture the level of irrigation management.It has the practical,maneuverable and popularization value.
Abstract: This paper analyzes the development of water quality models,especially surface water,groundwater and non-point sources models,and points out the development features of the water quality model.That is,from the experimental study to the mechanism study,from a single factor (or inorganic,large amount,non-toxic) to multi factors (or organic,trace amount,toxic),from a single media to multi-media,from a point source to the non-point source and to joint study of point and non-point sources,from steady to dynamic,from saturated zone study to aerated zone study and to the joint study of them,from small scale and scattered study (river,lake,groundwater,etc.) to large scale integrated study (whole basin),from theoretical study to practical application.The key period of transferring from water quality study to river basin management study is pointed in the paper.A river basin management model,water analysis risk management framework (WARMF),is introduced and its the characteristics are analyzed.
Abstract: Some beneficial inspiration to china,which are contributes to reinforcing the cooperation,the integrative development,the opening in the whole river basins and corresponding the ecological environment for the rational and effective development of water resources in the global rivers,are obtained by analyzing the cases of the development of the global rivers,such as the Euphrates River and the Tigris River in the Asia,the St Lawrence River in the North America,the Danube River in the Europe,the Nile River in the Africa,the Amazon River in the South America,which are used for the reference of their succeed experiences and lost lessons Moreover,several advices friendly to neighbor countries and partners are put forward to develop and manage the global rivers in China.
Abstract: With the social and economical development,the worldwide problem of water shortage becomes more and more seri ous.To introduce the experience of the water resources management in other countries,the paper presents the water resources and the water supply management policy in Tampa Bay area.The water resources in Tampa Bay area mainly rely on groundwater at present.It has a positive effect on the planning,the economic analysis and the management method of changing the resource of water supply from mainly groundwater (75% of total water supply) to a uniform distribution of surface water,ground water and desalinated water (1/3 of each).Referring to the success of Tampa,some of new possible water supply measures are discussed based on the practical background in China.The direct use of rainwater and the reuse of treated wastewater are two effective water saving methods in urban area Desalinated water will play a great rule in the coastal cities.For the wide rural area,rainwater collection ponds and small plain reservoirs may be good measures to improve their water supply condition and water environment.
Abstract: In the paper,the problems of regional water security and the concerned challenges are analyzed,the research and practice of regional water security strategies at home and abroad are summarized,and the tendency of the future study as well as the questions in need of further research are expounded.The paper suggests that the interaction between the social and economic development and the water security in a region will be still closer in the 21 century,and that,with the help of the modern strategic theory of thinking and the simulation methodology of systematic dynamics,both applied to the systematic and dynamic simulation and appraisal in a region,the scientific option of the reasonable water security strategy will be a valuable project with practical significance and theoretical value research.