Abstract: By using bathymetric chart and discharged flow data,the relation between the rive-bed evolution and change of discharged flow in the braided reach of the south and north passage is studied in this paper.After implementing Yangtze Estuary Deepwater Navigational Improvements,there are an decreasing trend and an increasing trend in the ratio of ebb flow diversion through the north passage and the south passage,respectively.The length of sediment deposited on the entrance region in the north passage is about 12 km long,and that of the eroded on the upper region in the south passage about 18 km.But the total cross-section area of the entrance reach in the north passage and south passage decreased from 1998 to 2006.There are good correlations between the total channe storage and the yearly averaged ebb flow ratio in the north passage,and the cross-section averaged depth of the entrance reach in the north passage and south passage and their yearly averaged ebb flow ratio,respectively.According to the relationship formula,the change of the ebb flow ratio and the cross-section averaged depth of the entrance reach in the north passage and south passage are evaluated.
Abstract: The velocity distribution in the circulation zone around the spur dike is studied by 3D-PDA in the water tank in this paper.According to the distribution characteristic of the velocity and the flux,the general flow field can be divided into three regions in the transverse direction: the reverse-velocity backflow region,the positive-velocity backflow region and the main flow region; and two regions in longitudinal direction: the reverse flow velocity-increasing region and the reverse flow velocity-decreasing region.The longitudinal variation of the each region is also studied,which shows that the width of the negative velocity area and the circulation flow area changes linearly in the longitudinal direction.
Abstract: To well understand the mechanism of energy dissipation in a turbine flow passage and explore the change of turbu lence structures,a spatio temporal sinusoidal oscillatory mode is numerically tested in a turbulent curved-channel flow using large eddy simulation (LES).Six computing cases incorporated with different vibrating parameters of the wall are dealt with,and the distributions of the pressure,vortices,and other turbulent statistical quantities in the near wall regions are studied.The results show that the turbulence intensities increase largely in near wall regions,suggesting that the viscous sublayer is thinner as a result of the velocity graduate's rise due to the spanwise wall oscillation.Furthermore,the energy dissipation is increasing.The present study also shows that the mechanism of energy dissipation by spanwise-wall oscillation is strongly related to the spanwise-vortex generated at the edge of the viscous sublayer by the periodic Couette flow layer.
Abstract: The advection upstream splitting method (AUSM) is used to discretize the 2D shallow water equations based on the finite volume method and unstructured triangular grids.The source terms and drying wetting moving boundary in the shallow water equations are specifically handled.Compared with the theoretical and classical cases for 2D dam break and Zhalong wet land,it shows that the results are in good agreement with the field data and the advantage of original scheme is also remained.The application of AUSM scheme is shown its stability and credibility.
Abstract: With the laboratory experiments of the saltwater and the freshwater replacing each other in the level sand-column,and taking the kaolin,illite,smectite,bivalent mercury ion (Hg2+) and the phenol (C6H5OH) as the examples,this article studies the water sensitivity characters of the powder-silver sand.The results show that the influence of the content of the kaolin and illite on the water sensitivity of the powder-silver sand is very slight,which results in the descense of only one grade even the content reaching 10%(weight ratio); but for the smectite,it causes the hydraulic conductivity descending sharply by above-grades when its content reaches 3% (weight ratio),and without water flowing through the sand columns at 4% (weight ratio).With the effect of the shearing force from high speed fluid,the removing rate of Hg2+ ion and phenol (C6H5OH) is 31.68% and 55.71% respectively.And the remnants can be hold out of the powder-silver sand columnswith the particle's release and migration in water sensitivity process.The reason for the obvious difference between removing rates of two kinds of pollutants is that there are many negative charges on the particles surface which absorb the bivalent mercury ion (Hg2+) which makes its resorting rate is higher than the phenol (C6H5OH).So,we can make good use of the water sensitivity character of the powder-silver sand to build the impenetrable purdah and remove pollutions of the heavy metals and organic pollutants in the sand aquifer.
Abstract: In this paper,the domestic wastewater,a multi-component mixture,is used as the simulat ed pollutants,and two groups of fine sediment with different size as the experiment materials Some experiments are conducted to study the biodegra dation reaction kinetics of pollutants in water with sediment and the expression between the biodegradation rate constants and sediment concentration is established.The analysis of experiment results show that: ①the biodegradation process of low concentration pollutants in water with sediment can be expressed by one order reaction kinetics,②in the water with the same group sediment,the greater sediment concentration is,the faster the pollutants are biodegraded,which means that sediment accelerates the biodegradation of the pollutants,and ③the biodegradation rate constant increases and reaches the maximum with increasing sediment concentration,and there is a nonlinear function between them.
Abstract: The hydrodynamic and sediment environments near island coasts and its changes caused by coastal structures both have their own characteristics and complexity.According to the historic data,the changes of the process of hydrodynamics and sediment in the Shengsi fishery port area,caused by the builting coastal structures,are analyzed systematically.On the basis above a 2D mathematical model for sediment transport by waves and tidal currents is developed,and the changes of the tidal current field,sediment concentration field and the deposition-erosion caused by the proposed coastal structures are predicted and analyzed by the model.After the implement of the built and the proposed breakwaters in the fishery port area,the hydro-dynamic conditions are worse obviously and the seabed is deposited with a rate of 0.1-0.3 m per year.After the implement of the built and the proposed reclamation in the fishery port area,the hydrodynamic conditions are better and the seabed is eroded slightly.The effects on the hydrodynamic and sediment environments caused by both the built and the proposed coastal structures have a good consistency.
Abstract: Based on the daily observational precipitation data of 147 stations in the Yangtze River basin during 1960-2005,the projected daily data at 79 grids from ECHAM5/MPI-OM in the 20th and the former half of the 21st century,time series of precipitation extremes which contain AM(Annual Maximum) and MI (Munger Index) are constructed.To quantify the characteristics of flood-drought events over the Yangtze River Basin,four distribution functions are used,namely,General Extreme value (GEV),General Pareto (GPA),General Logistic (GLO) and Wakeby (WAK).It is proved that WAK can describe the probability distribution of precipitation extremes quite well calculated from observed and projected data..The return period of precipitation extremes show spatially different changes under thee greenhouse gases emission scenarios.The 50-year heavy precipitation and drought events from simulated data during 1951-2000 will be more frequent and become the 25-year events for the most midlower Yangtze region in 2001-2050.The changing character of return levels of precipitation extremes should be taken into account for the future water resource management.
Abstract: Based on the observed monthly streamflow of 19 key hydrological control stations in the six larger basins in China since 1950,the uneven coefficient of seasonal distribution,concentration rate,concentration period and variation range are analyzed,and the Mann-Kendall test method is employed to detect trends of inner-annual runoff.Results indicate that since 1980s,the observed monthly streamflow in the six larger basins has generally changed,except of Shixiali station,Xiangshuipu station in Hai river basin and Huayuankou station in Yellow River basin.For other stations,the uneven coefficient of inner-annual distribution and relative concentration rate are larger,particularly in Songliao river basin.Moreover,the monthly runoff in winter and spring (from December to March) in southern basin increases and decreases in May and increases in July while in winter and spring (from January to May) in northern basin it decreases evidently in Hai river basin,Tieling station in Liao river basin,Lijin station in Yellow River basin and Wujiadu station in Huai river basin.
Abstract: A grid-based distributed hydrological model is proposed,which can simulate the physical processes of hydrological cycle,including precipitation,interception,infiltration,evaptranspiration,runoff generation and flow concentration in each grid and flow routing in river networks.To obtain rainfall values for each grid,the co-Kriging method integrating the altitude influences is applied.To compute evaptranspiration and interception,the land use-cover change information in study site is derived from remote sensing data.To compute the runoff generation in each grid,a relationship between topography index,which can be generated from the digitat elevation model (DEM),and the maximal soil moisture deficit is established.The flow routing paths of effective rainfall in each grid are derived from DEM.The model structure is simple and most parameters can be determined directly from DEM.The model is calibrated and applied to the Yanduhe Basin of Three Gorges flow reach of the Yangtse River.The simulation results are satisfactory.
Abstract: The remote sensing can provide surface parameters for Evapotranspiration (ET) estimation at regional scale,where-as the traditional approaches just provide points measurement.This paper introduces an ET monitoring system using remote sensing ETWatch,which is an operational processing chain starting from data pre-processing to application products,utilizing spatial information on climate,soil type,land use,vegetation cover,digital elevation,and remote sensed land surface parameters.The surface energy balance algorithm for land (SEBAL) and the surface energy system (SEBS) are integrated into ET-Watch to estimate surface fluxes on clear-sky condition,while the Penmon-Monteith is applied to retrieved daily ET based on the surface resistence model,the meteorological data and the surface parameters from remote sensing.The application of ET-Watch in Haihe basin is demonstrated for year 2002 to 2005,and a validation is carried by comparing the field fluxes measurement and the hydrological records with the model estimation.The results show that when the energy closure ratio (ECR) of eddy covariance (EC) technique is above 0.9,average deviation of daily ET at the 1 km scale is below 10%; at the 30 m field scale,compared with water consumption from soil-moisture-depletion-method,average deviation of remote sensed daily crop ET is about 12.7%.
Abstract: A strength Pareto evolutionary algorithm (SPEA) to solve the multi-objective programming (MOP) of the feeding reservoir group optimal operation is presented in this paper.The SPEA seeks the Pareto optimal set through the program of the population evolution.The individual in SPEA is abstracted as a solution of the problem.In the process of the individual evolution,the population converge to the Pareto optimal set.The result of case study shows SPEA can solve the MOP of the feeding reservoir optimal operation.The SPEA shows its advantage in multimodal search,the distribution of the final Pareto optimal set and the convergence.Therefore a new efficient method is provided for MOP of the feeding reservoir optimal operation.
Abstract: The Qiantang estuary is a strong alluvial estuary.The sedimentation/erosion extends usually reaches 5-10 under the action of the flood or tidal flow.So the riverbed erosion extend is the key technical problem for the tunnel project across the Qiantang estuary.In the paper,three prediction methods on the maximum erosion depth of the river bed nearby this tunnel are set up based on the analysis of the hydraulic geometry of river channel,the sediment mathematical model and the movable bed physical model.These models are calibrated using hydrographic field data as well as those on the historical morphological changes in the Qiantang estuary.After the calibration these models are used to investigate the maximum scour depth caused by an exceptional flood in the cross-section of a tunnel across the Qiantang estuary.Finally,the maximum erosion depth and erosion curve of the riverbed cross-section nearby the tunnel under the 100-year flood is predicted by the three predicting methods,and the predicted result agrees very well with the geologic drilling data.It is shown that the predicted result is basically reasonable and the scientific basis is offered for the study of this tunnel.
Abstract: A field study was conducted to investigate rainfall interception and rainfall redistribution by salix psammophila,which is a typical sand-fixat ion plant in Maowusu sandland,Northwest China During the experimental period,from May 23 to Oct 23,2006,there were 21 rainfall events,and the cumulative gross rainfall was 136.5mm The amount of throughfall (TF),stemflow (SF),and canopy interception (IC) was 98.5 mm (72.2%),4.0 mm (2.9%),and 34.0 mm (24.9%),respectively.The statistical analysis shows that there is a significant positive linear correlation between rainfall and TF,SF and IC,respectively (significant level p < 0.0001).The relat ionship between rainfall and the proportion of TF,as well as the pro portion of IC could be matched well by a hyperbola function (signif icant level p < 0 05).Moreover,IC and TF increase with rise of the maximum rain intensity in 10 minutes (I10).
Abstract: The digital elevation model (DEM) grid size has significant influence on topographic index,and the effects of topography on watershed hydrology are represented in the TOPMODEL as the distribution of topographical index ln (α/tan β).In this study,the 10 m grid size is selected as the base resolution,and 17 DEMs are generated ranging from 10 m to 1000 m resolutions.The discharge of TOPMODEL in 10m grid is taken as the observed value compared with the discharges among different DEM resolutions.A significant change of the model in response to scale is identified with the grid size of 300 m,the efficiency remains approximately constant between 10m and 150 m,and above this scale the efficiency declines rapidly.In the last section of the study,the Monte-Carlo method is used to analyze the effects of DEM grid size on the five TOPMODEL parameters.More significant are the results of T0 which shows a strong positive relationship with the grid size increase and the other parameters perform have no clear influence.
Abstract: By setting up benchmarks for underground water indices,a universal exponential formula with power function suitable to the multiindexes is put forward to evaluate underground water.The immune evolutionary algorithm (IEA) is used for optimizing the parameters in the formula.The optimized formula is free from the restrictions of kinds and numbers of pollutant,including assessment formula of single index as a special example.It can be used for evaluating several cases,compared with the results of other methods,the modified universal formula is simple,easy to calculate,comparable and practical.
Abstract: The objectives of this study are to develop a quantitative method to describe heterogeneous flow patterns and identify the heterogeneous information characteristics based on flow patterns.Dye tracer experiments were performed on plots with different conditions.The flow patterns were separated into similarly stained horizontal layers based on the width distributions of the stained areas Then the layers ident ified in the flow patterns were partitioned into groups with similar patterns by hierarchical clustering.The results show that the dye coverage and width of stained structures are the most indicative factors for the dif ferent clusters.The number of clusters affects the degree of layer discrimination.Three and eight clusters seem to be sufficient to capture the main characteristics of the heterogeneous flow patterns.For the experimental plots where the vertical flow is dominated,the clusters contain the layers with the homogeneous flow,preferential flow,and those with flow changes from ho mogeneous infiltration to preferential flow.For the experimental plots where the horizontal heterogeneous is significant,the soil horizons has a strong influence on the water flow patterns.
Abstract: In this non-point pollution control experiment,three local swards: Cynodon dactylon,Festuca Arundinace,and Trifolium repens,and four gradients: 2,3,4,and 5% are selected to construct the buffer strips test base.The final results show that: the riparian buffer strips can effectively remove SS in runoff water and the nutrients in seepage water; the differences of sward and gradient have notable influence on the pollutants purification of buffer strips.The SS retention rate of the 2% gradient buffer strip,19 m long is 14% higher than 5% gradient strip; that of the Cynodon dactylon buffer,19 m long is 11% higher than Trifolium repens strip.When the TN concentration of influent is lower than 10 mg/L,that of seepage effluent of 2% gradient Cynodon dactylon strip is lower than Grade V of Surface Water Environmental Quality Standards (SWQS) (Chinese EPA,2002).When the TP concentration of influent is about 0.6 mg/L,that of seepage effluent of Cynodon dactylon,Festuca Arundinace,Trifolium repens and 2,3,and 4% gradient strips is lower than Grade Ⅲ of SWQS 1 According to the approach used in this paper,the optimal width of 5% gradient buffer strip is 8.6 m longer than 2% strip; and the optimal width of Trifolium repens buffer strip is 4.3 m longer than Cynodon dactylon strip.
Abstract: Hypoxia is one of the environmental problems existing in the Pearl River estuary (PRE).In this paper a coupled 3-D hydrodynamic-ecological numerical model is used to investigate the distribution and causes of the hypoxia phenomena in the PRE in summer.Hypoxia at the bottom layer of the major regions is well reproduced by this model,and in complete agreement with the observed pattern.The main results of the simulation show that the hypoxia phenomena in the PRE are caused mainly by the coupled dynamics of the water stratification and biochemical processes.The simulated hypoxia phenomena develop during the neap tide and disappear during the spring tide.The front and salinity stratification impact greatly on the range and intensity of the low oxygen water in the PRE.
Abstract: When using the existing typical algorithm to solve the model of optimizing irrigation schedule,with each algorithm itself having the insufficiency,the acceptable optimal solution of the model is usually not able to search successfully.The free search (FS) is a novel optimization algorithm.As an illustrative case,the article modifies it properly and applies it to solve the model of optimizing irrigation schedule at the different water supplies.The results obtained suggest that FS has favorable stability and convergence and can give a more accurate solution to the dynamic programming successive approximation (DPSA),genetic algorithm (GA) and chaos algorithm (CA) FS has clear regulation and convenient operation,and is a better method for optimizing irrigation schedule.
Abstract: Even though the water quality in natural river is polluted,the water power still exists and can be used.So we propose a method for air aeration using water power and appliedit to the aspect of sewage ecological treatment.The water quality standard will reach Ⅲ classification for surface water and the direct operation cost of sewage treatment will be greatly reduced in the polluted river water.The method abolishes the blast aeration (kinetic energy utilization),breaks down "The Sound Barrier" of sewage ecological treatment and brings the advantage of the water power utilization with cost low into full play.
Abstract: The automatic canal control system based on the water level and discharge of a canal can greatly improve the operation and the water use efficiency,and reduce the operation costs.This paper introduces systematically the canal control theory and the concept of automation.A brief review on the studies of the complex long-distance water transfer projects in recent years is provided,and the problems in the literature and possible ways of improvement in the operation are discussed.The control scheme is investigated from the viewpoint of the multi-input multi-output of the system,the nonlinear model,and the stochastic disturbance.The future study in the fields of canal operation mode,control algorithm,and gate control scheme is suggested.
Abstract: We briefly introduce the computable general equilibrium (CGE) model,and review the water resource CGE models on several study fields: water pricing,the optimal allocation of water resources,water rights & water market transactions,as well as other issues such as sustainability and flood.The time span of the reviewed CGE models is more than 20 years,and its spatial scale spreads from a small watershed at the county level to global water resource issue.On the other hand,the water is sue is an important component of the socio economic system,the impacts of water resource issues would spread to other sectors of the socio economic system,so we think that CGE model is suitable to the study of water resource issue,summarize the fun damental characteristics of water resource CGE models,and work out three methods about water resource issues are linked to the CGE model.However,because of the linkage problems between water resource and the CGE model,as well as the data collection and other reasons,water resource CGE models are still at its immature and active development stage.