Abstract: In accordance with the characteristics of water resources utilization in arid zone where a fragile ecological system exitsts and on the basis of theory and method of dual water resources evolution,a mode and calcuation method of rational water resources allocation for the inland arid zone in the Northwest China is formulated,which can maintain the water-land eguilibrium,the water quantiy bulance and the water-salt equilibrium,consider the allocation in space,time,uses,water sources and management,determines the development index by available water resources on the basis of actual situation,and rationally allocate water resources to ecological use and economical use in the unit of a rever basin.The quantitative calculation indicates that among the runoff water resources of 809×108 m3,the water quantity directly allocated to the natural ecological system is 302×108 m3.Plus the returning water of 126×108 m3,the quantity of water which can supply the ecological system amounts to 428×108 m3,and the actual ecological water demand is 385×108 m3,so the water demand of the ecological system can be satisfied on the whole except the Heihe river basin and the Shiyanghe river basin.
Abstract: The vadose water within the surface layer with depth of about 2 m of 7 megadunes and 1 movable dune was observed during camel expeditions of 1997-2003.The relative height of these megadunes ranges from 300 to 400 m with the altitude of 1 300 m-1 488 m a.s.l.Traditional methods are used to probe the vadose water content and the physical features of its eolian deposit.Observations were made during 25-27 September every year at different spots in the hinterland of that sand sea.The results show that for all of the observed megadunes,the vadose water content appears to increase volumetrically with the depth with an amount of about 3% at the depth round 2 m below the megadune surface.It reaches to about 65% of the maximum wetness held by matrix potential of the deposit (HB) which was measured after rainfall events during the expeditions of 2000 and 2003.The positive δ18O values of the vadose water at the depths from 25 cm to 1 m beneath the megadune surface reveal a repeated recharge-evaporation process.The infiltration depth of a few centimeters after rainfall event was also observed along a slope of 120 m on a sand dune,it could be quickly exausted through the evaporation measured by energy budget.It is concluded that the local precipitation with annual mean of about 50 mm from its northwest to 80 mm southeastwards seems not sufficient for the output amount of annual evaporation from megadune surface even if a portion of it being condensed.If take into account the high percentage of HB of the vadose water within the surface layer of megadunes and the enrichment process of 18O,the current concept that the main recharge source of the megadune area is the local precipitation will be challenged.The existence of an important groundwater recharge source far away from this dune desert,perhaps,from the mountainuous area to its south,is not directly identified,but it seems to be implied.
Abstract: The procedure of cadmium ion transport through unsaturated soils can be described by the convection-diffusion equation,coupled with non-equilibrium sorption effect.The undetermined model parameters in the dimensionless governing equation include the longitudinal dispersivity,the sorption distribution coefficient,the precipitating rate,the dissolving rate and the maximum precipitation.This paper aims at inversing parameter values of the parameter mentioned above for cadmium ion transport in 8 Portugal soils samples and.Belgium soils sample under different experimental conditions.Experimental results of 15 groups are obtained in virtue of the laboratory soil column tests for 9 soils samples mentioned above by using self-designed experimental apparatus under different experimental condition.The gradient regularization method is adopted as the inversion method.Based on the experimental results (BTCs),the corresponding model parameters for each experiment are identified by the numerical inversion.The validity and reliability of the gradient regularization method is verified by the numerical simulated experimental results.The computational results confirm the veracity of results presented in this paper.
Abstract: An unsteady one-dimensional numerical model was developed for the simulation of flood routine and alluvial process of rivers with heavy sediment load.In this model,the basic equations and relations for sediment transport were modified to cope with hyper-concentrated flow.To avoid non-physical oscillation caused by sharply changed channel geometry and intensive erosion/deposition,the governing equations were discreted in staggered grid and a TVD scheme was adopt to obtain numerical solution.Applications of the model were also presented in this paper.
Abstract: In former researches about wakes flow,the length scale in the spanwise direction of the wake generator is usually very large.While the wake flows in natural environments and hydraulic projects are often very shallow,compared with the horizontal dimension.Because of the limits of the bottom and side walls,the shallow wakes have some special characteristics.The digital particle image velocimetry (DPIV) is employed to study the flow field around a solid plate in shallow water.The experiments are carried out in a flume with 30 m long,3.5m wide and 1m deep.The movement of large-scale vortex is analyzed.The changes of flow pattern with wake stability parameter are investigated.Such large-scale quantitative experimental study on shallow wakes can rarely be found in literature.
Abstract: The mathematical analysis shows that,with disregarding local head losses and by means of different simplified rigid models,the calculated results of the maximum pressure in a pressurized pipe system containing trapped air mass are equal to and independent of the initial length of the water-column.However,the calculation examples in this paper indicate that,if the initial water-column length is relatively short or the volume of the trapped gas is very small,the calculation error may be significant and even leads to a false conclusion.Therefore a complete rigid model is then presented in this paper,along with its theoretical limitation and suitable application terms.
Abstract: The overbank flow in a compound channel is studied.And the relationship between the friction factor and one dimensional in-bank flow friction factor is established.The dimensionless eddy viscosity is found increasing with the growing friction factor on flood plains.The effect of secondary flow is expressed in the same form as the Reynolds shear stress so that they can be combined into the apparent shear stress and determined through the dimensionless apparent eddy viscosity,which can be calculated by the relationship of the dimensionless apparent eddy viscosity and the friction factor similar to that of the di mensionless eddy viscosity and the friction factor.The symmetric overbank flows with smooth boundary are computed and the results agree with the experimental data.
Abstract: This paper is concerned with a mathematical model for two-dimensional strong turbulence flow with free surface including the effects of streamline curvature in orthogonal curvilinear coordinate system,with which the characteristics of the turbulence flow field on the ogee spillway is numerical simulated.In the numerical simulation,the flow control equation in orthogonal curvilinear coordinate system is discretized by the finite volume method; the physical parameters,pressure P,U,V,κ,ε,γ,etc.,are arranged on a staggered grid; the discretized equations are solved by SIMPLEC method; and the complex free surface is dealt with VOF method.The computed results show that the velocity fields,pressure field,shear stress distribution and kinetic energy of turbulent flow on the ogee spillway are in agreement with the experimental data.
Abstract: The numerical simulation of three-dimensional flow for spillway containing frusta is presented in this paper by means of the finite volume method.Turbulence is simulated with the κ-ε turbulence models and the waterline is determined by the VOF method.In order to investigate the feasibility of the proposed method,the numerical models are applied to type-2 and -3 frusta.The results show the flow spillway,the waterline and the surface pressure of the three water surface heights.And the experimental results validate the simulate results,which shows that the proposed method can simulate exactly three-dimensional flow for spillway containing frusta give advice on the design for spillways.
Abstract: A non-grid hydrodynamic numerical model is established by using the moving particle semi-implicit (MPS) method to investigating the possibility of the model in the research of the hydrodynamics of the coastal structures under the action of water movement.Without grids,the interaction effect among neighboring particles can be simulated by means of the kernel function,based on which the governing equation is discretized by establishing the smoothing model,the gradient model and the second-derivative model (i.e.the Laplacian model).The incompressibility of the fluid is determined by introduction of a socalled particle density number.The model is free from limitation through complex shape of rigid boundary and arbitrary defomation of the free surface,and thus has the adaptability to special practical situation.In the end,collapsing process of a water column impinging an upright wall after by-passing a set of perforated blocks is simulated by using the MPS model.The numerical results show that the peak value of the pressure in the case of the perforated blocks decrease by 42% compared with the case without perforated blocks.
Abstract: Through the analyses of the formation factors causing disaster of the Yangtze River flood,the boundary conditions and its disaste-breeding environment and the carrying body easy to be damaged,this paper devotes to the inevitability of the middle Yangtze River becoming the extreme seriousness of flood disaster in China,analyzes the harnessing of human creature along the river to increase the stability of the river course,thus reducing the risk of flood disaster.But,the tendency of raising the flood stage still exists in the local reaches of the middle Yangtze River,which also increase the dangers of flood disaster and is still the high dangerous basic characteristics in this region.After studying the operation of the Three Gorges Project,new situation of flood protection occurs in the middle Yangtze River.On the one hand,a huge flood control capacity of the Three Gorges Reservoir can retain a large amount of floodwaters,thus greatly reducing the flood disaster in the middle and lower of the Yangtze River.On the other hand,the strong erosion of the river course will make the river regime to change violently,increasing river channel shifting.It is difficult to stabilize bank wall of the local reaches,which also increases the pressure of flood protection.Meanwhile,because of flattening surface slope,there is a tendency to transfer downstream at the risk of flood disaster.In the future,the middle Yangtze River is still the high dangerous region,and it should still be attached great importance to.
Abstract: Systematic investigations in various forms of N in the Yangtze River mainstream and major tributaries and lakes from the Yangtae River in the Yangtze upper reaches to the mouth were carried out from November to December 1997 (dry season),and in August and October 1998 (flood season).There were basic similar models in transport of various forms of N,their transport fluxes gradually increased from the river's upper reaches to the mouth and the most obvious were NO3N 、 DIN 、 TDN and TN which were consistent with their stability extent.The export fluxes of various forms of N in the Yangtze River mouth came mainly from the middle and lower reaches,particularly in the dry season,and over half of N were contributed by the tributaries and the lakes and the maximum came from the Dongtinghu Lake,then the Poyanghu Lake water systems.In the transport and export fluxes in the dry and flood seasons,NO3-N was major in three forms of inorganic N,DIN was major in various forms of dissolved N,and dissolved N was major in all forms of N.In the dry and flood seasons,various forms of N fluxes in the Yangtze River mainstream and tributaries and the export fluxes of various forms of N in the Yangtze River mouth were mainly controlled by runoff.The transport equations of various forms of N were suggested by this paper.
Abstract: The renormalization grop (RNG) based on the κ-ε turbulence model and the hybrid finite analytic method with staggered grids is used to calculate negatively buoyant jets in static ambient.The maximum penetration depth,velocity vector in the whole field,the temperature contours,the turbulent kinetic energy contours,the velocity and temperature distributions in cross sections and the axial temperature distribution are got by simulation.The calculated results are compared well with the available experimental date,which shows that the RNG based on the κ-ε turbulence model amd the hybrid finite analytic method can be used to simulate the variation density flow.
Abstract: With the application of the hybrid algorithm of simplex method (SM) and the simulated annealing (SA) (SMSA),the function optimization problem is effectively solved in analyzing the data of water mass tracer test of river stream on the condition of instant injection of tracer to estimate such parameters as the longitudinal dispersion coefficient,the average stream velocity and the other parameter.With such different key parameters of algorithm as the number of inner loop,the cooling rate and the range of random disturbance in the new state generator,the simulation experiments are conducted to explore the effect of these key parameters on the convergence of the hybrid algorithm.The results show that the SMSA hybrid algorithm may be effectively applied to solve the function optimization problem of estimating water quality parameters of river stream,the conver-gence of hybrid algorithm is much better than that of improved simulated annealing with memory function in inner loop,the number of inner loop and the cooling rate have little effect on the convergence of hybrid algorithm,but much on that of improved SA,and the range of random disturbance in the new state generator may have clear evident effect on the convergence as on that of improved SA as well.
Abstract: The starting principles of sediment in Taihu lake are simulated in an annular tank,the different stages of sediment movement are analyzed,and the changes of total phosphorus (TP) concentration in upper water with velocity are studied in this paper.The experimental results show that the incipient velocities of sediment in Taihu lake at three different incipient standards (individual movement,ounce movement,universal movement) gained from the lab experiments are 35,45 and 60cm/s respectively,and the observed TP concentration in the upper water varies significantly at the three starting velocities.In this paper,the theoretical sediment starting model is also used to calculate the incipient velocity and the incipient shear stress of Taihu lake at three different starting standards.The calculated values are 37.9,46.7,59.8 cm/s and 0.428,0.636 and 1.042 N/m2,respectively.It can be concluded that the starting velocities gained from the lab experiments and the model simulation are fairly applicable,which can basically reflect the actual starting state of sediment in Taihu lake.
Abstract: The vertical distribution of total phosphorus (TP),the dissolved total phosphorus (DTP),the soluble reactive phosphorus (SRP),the suspended solid (SS) and its loss on ignition (LOI) in Taihu lake,a large,shallow,eutrophic lake,was observed in a strong wind course (with the wind speed of 12 m/s) and a light breeze course (with the wind speed of 3 m/s).The water depth of the observed site was 1.9 m.The concentrations of TP,DTP,SRP and SS at 10,90,140,and 190 cm below the water surface were monitored.The water-column mean concentration of SS in strong wind period was 468.8 mg/L±302.1 mg/L,which is 10 times higher than that in light breeze period,and the concentration of TP was 0.296 mg/L±0.081 mg/L,which is 3.6 times higher than that in light breeze period.However,the difference of the concentrations of DTP and SRP between strong wind period and light breeze period was insignificant 1 Additionally,both in the strong wind period and in the light breeze period,concentrations of SS and TP were insignificantly different among those in the upper three layers,and lower than those in the bottom layer.However,the concentrations of SRP were insignificantly different in the whole water column.The results indicate that,wind-induced wave not only cause the drastic sediment resuspension and the nutrient releasing,but also result in the absorption of dissolved reactive phosphorus.The sediment resuspension may not increase,but decrease the amount of the bio-available phosphorus in the water column.
Abstract: The eco-environmental water demand of urban lake include the water for evaporation,itself,habitat,pollutant cleaning,leakage and landscape.Apart from the calculation principles of the priority to protect environment,compat ibility,max and grade,and that timelines should be emphasized.A case study of six lakes of Beijing six lakes is mentioned,and its water demand but winter is calculated.The result is that the minimum water demand in spring is 296.82×104 m3,in summer is 643.94×104 m3,and in fall is 474.59×104 m3,and the all year water demand is 1415.35×104 m3.The percentages of the water demand for pollutant cleaning are 35.87%,71.23%,70.08% and 63.42% separately According to the result,some suggestions about the development of the eco-environment of six lakes are presented.
Abstract: Flood system is usually very complex,and always changes with different inflow from upstream,local rainfall,riverbed deformation and other factors.When the back propagation (BP) neural network is applied in such system for flood forecasting,the algorithm must have ability for real-time tracing of the changes of parameters in the system.In this paper,a variable weighted forgetting factor based on recursive least-squares parameter estimation is introduced into the BP model to simulate such time-variant system.Each weight of the neural network can be real-time modified and the transitional invariable mapping relationship between input and output in the non-liner system of neural network is improved.And two examples are given to demonstrate the effectiveness of the improvement.The calculated result shows that the time-variable weights can be traced with a fast speed and agrees well with the measured data.
Abstract: A new method based on geographic information system (GIS) is presented to generate body-fitted meshes automatically.First,a principle is put forward to express the variable flow direction numerically in close approximation,which is based upon the spatial relationship between nodes of the river centerline; then,sections vertical to the flow direction are partitioned throughout the river,and a smoothening method is worked out to prevent overlapping sections from coming into being.A uniform relationship between the sampling direction and the flow direction at anywhere should be guaranteed in order to eliminate "wresting" phenomena in output results and the "right-hand" rule is applied here.And then,an elevation-based interpolation algorithm is designed to reconstruct the landscape model of the river,which is in the form of the output body-fitted meshes.At last,results and tests of the algorithm in pictures and tables are also provided,which proves the algorithm to be well body-fitted and efficient.
Abstract: On the base of redefining usable water resources and ecological water demand the water resources carrying capacity of Northwest China is estimated on the scale of basins.The ecological water demand and water rights was neglected in the former definition of usable water resources.This paper defines usable water resources for human being as:One part of total available water resources that can be consumed by human living and economic production under conditions of certain techno-economic level,certain standards of ecological protection and water right limitation.Taking the viewpoint of runoff resources,ecological water demand means one part of total available water resources that is needed to maintain the integrity of ecosystem.The total available water resources is balanced by human usable water resources,ecological water requirement and water resources not usable by human being and ecosystem we want to protect.The total renewable water resources of Northwset China (including internal closed basins and Yellow River basin within Shaanxi,Ningxia,Gansu,Qinghai,Xinjiang and the westem part of Inner Mongoulia) is 1 638 1 5×108 m3,while the net amount that flow into other countries is 411.9×108 m3,the quantity if ecological water requirement is 454.4×108 m3,and the quantity of usable water resources is 742×108 m3.By using an optimizing model the water carrying capacity of Northwest China is appraised:under the conditions that per capita GDP double every 10 years and water use efficiency rise at the rats of 7% annually,water resources of Northwest China can support population of 12.7 million persons in year 2030.
Abstract: This paper introduces the relationship between the water pricing and the sound operation of the water transfer project.Through the economics analysis of the different water pricing methods,it states the effectiveness of the long term marginal cost water pricing method on the optimized allocation of the transferred water resources.The paper proposes further the water pricing principles for the South to North Water.Transfer Project:to be guided by the long term marginal cost water pricing thinking,to realize the combination of volume water pricing and the volumetric water pricing,to establish a water pricing mechanism with the dynamic readjustment as the supplementary measures,to raise properly the price of the water transferred from South to North,and to ensure the stable transition of the water price in the water receiving areas and the water source structure.
Abstract: The paper is based on an experimental study on in-situ rainwater harvesting by irrigating several selected crops,spring wheat,watermelon,broccoli and cucumber.The experiments were conducted at the Gaolan Station of Agricultural and Ecological Experiment (Gaolan County,Gansu Province),Chinese Academy of Science,in 2000-2001,in order to explore the rate of rainfall-runoff,compare the micro-catchment's cost of various types of water collection,analyze the storage cost of various water cellars,and investigate the unit yields and water use efficiency (WUE),production values of the selected crops and the production value per cubic water.The results indicated that,the costs of both micro-catchments and storage of harvested rainwater are averagely expensive,which accounted for.1.07-RMB.m-3 and 5.08-RMB.m-3,respectively,with a higher water storage cost.The cucumber in solar greenhouse has the highest values in both net production and production per cubic water,followed by broccoli in open field,watermelon in gravel-mulched field,and wheat in open field for the comparable values.All the net production values of wheat are negative if the investment of manual work is considered; supplementary irrigation causes the decrease of the net production values to a great degree.In contrast,harvested rainwater for micro-irrigation of watermelon in gravel-mulched field,of broccoli and cucumber in solar greenhouse brought large benefit.We may get a conclusion that the model of “one cellar and one pond” for solar greenhouse is the effective catchments-storage-high utilization of rainwater model for solar greenhouse in the region with an annual precipitation of 300 mm.
Abstract: The main problems and the central issues of the study in hydrology and water resources development stage in China are described in the paper.And the study direction of hydrology and water resources in arid inland river basin in China are preliminarily discussed through an example of Xinjiang.
Abstract: The Three Gorges reservoir area have been synthetically harnessed for nearly ten years,its water environment problem is decelerated from getting worse,but the pollution is still serious.The content of sand in the water in this area is still the biggest along the Yangtze River area.It is main because of the inefficient environment supervising,legal system being devoid of restriction on water environment harnessing,the environment management mechanism short of vigor,the environment protecting establishment short of market function,the industry structure inconsequential and the people indifferent to zoology protection.To solve the water environment problem bassically in the Three Gorges reservoir area,we must induct the circulating economic theory and the economic theory of ecosystem,rebuild ecotypic industrial structure,establish and perfect the handling system and its market mechanism,set up the relatively independence legal system in environment protecting,extend the right for the public to know what happened about environmental protection,encourage the public to be concerned with environment supervision,establish the green GDP statistic system and the local government official environmental protection achievement evaluation system,completely push forward the city's ecotypic development,and set up the modern synthetic early-warning system.
Abstract: With the increases of world trade a new concept,virtual water,recently arising and being frequently used in the field of water resource has became an important factor affecting region water system.The Economic background of the appearance of its appearance is analyzed,and methods to calculate the content of virtual water in crops and livestocks and the virtual water flow are introduced and reviewed.The virtual water flow concerning China's crop trade is also analyzed preliminary.And the importance of virtual water in raising the water use efficiency,making the comprehensive water resource planning,and possible effect on social and economic aspects are concluded preliminarily.