Abstract: A 3D mathematical modeling considering bank erosion is developed by using both a cohesive bank erosion model and a 3D flow-sediment transport model.The locally-adaptive grid system based on the non-orthogonal grid is proposed to simulate the lateral migration in the channel due to the bank erosion.The governing equations for flow-sediment transport are solved with the finite volume method and the SIMPLEC algorithm with the momentum interpolation.The computed case of the self-forming meander evolution demonstrates that this model is able to predict the complex fluvial processes in alluvial rivers with bank erosion.
Abstract: In the up stream of the Yangtze River,the construction of the hydroelectric power projects,such as Xiluedu reservoir and Xiangjiaba reserwir,changes the hydrodynamic and sediment environment of the backwater area of the Three Gorges Proj ect ( TGP).After the adjusting of the runoff-sediment by the reserwirs in the upstream,the sediment deposition and erosion in the backwater area has the corresponding changes. In this paper,based on the watersediment characteristics and fluvial process of the backwater area of the TGP,a 2D sediment mathematical model in the boundary fitting orthogonal curvilinear coordinate system is developed by the authors,then the rules of the space-time changes of the sediment deposition and erosion in the Chongqing reach is predicted in 100 years by using the model,and its effects on the harbors and navigation channels are detailedly analyaed. The Analysis of the results proves that,under the water-sediment conditions during 1960s,serious sediment deposition occurred mainly in the river sinuses,the recirculating zones and broad-shallow reach. After the construction of reservoirs,the sediment deposition wlume decreases by 82.6% in the Yangtze River and 89.7% in the Yangtze River, compared with that of 1960s,which is advantageous for the maintenance of TGP and the development of Chongqing reach.
Abstract: In this study,based on the consecutive hydrological and climate records in the past 50 years and the landsat scanning images in the Yellow River Delta from 1986 to 2001,the quantitative relationship between the area of the main wetland type and the runoff and sediment changes are well established through the regression analysis.The results indicate that the runoff at 200×108～300×108 m3 and the sediment discharge at 5×108～8×108 t into the Yellow River Delta are probably the most appropriate range for maintaining the stability of the wetland landscape pattern.There exists the close positive relation among area,runoff and sediment discharge.The regression models are established between the area and the hydrological and climate parameters in order to provide scientific basis for the establishment of the early warning mechanism and the protective strategy for the degenerated wetland.
Abstract: A GIS-aided MIKE SHE model,distributed hydroloyic model,is used to simulate the stream flow in an ungauged Kaidu River Basin(19012 km2)with arid climate,which is one of the most important sources of Tarim River. Based on the GIS technique,the DEM of the study basin is successfuly used to delineate the stream network and to extract the information of catchments characteristics. Landsat TM data from 1995 to 2001 are utilized for various scale depended maps of the land use and vegetation,and leaf area index(LAI)from MODIS data is used as input data for the distributed hydrological modeling. Further,the root depths of the annual vegetation are related to the temporal and spatial variation of LAI. The observed discharge at Dashankou station is used for the calibration and validation. It is shown that a well-calibrated MIKE SHE model with five "free" parameters can produce the consistent results with the model efficiency coefficients greater than 0.7,the water balance error lower than 3%,and the simulated discharge is highly correlated to the observed discharge.
Abstract: An improved entropy spectral estimation method,Genetic Entropy Spectral estimation(GES),is proposed to identify the implicit periods in annual runof time series.The method is based on the accelerating genetic algorithm(AGA),which is mainly used to optimize the parameters of maximum entropy spectral analysis method(MESA),and minimize the four equivalent conditions of MESA.Compared to the traditional variation spectral method and Burg spectral method,the entropy estimation results based on the improved method is not depend on the selection of initial value,further more,the method has high adaptability for data length,signal noise ratio and initial phases.Taking Houdacheng station in the Sanchuanhe River basin as a case,an annual runof series from 1956 to 2000 is studied with the method.And results show that there are two prominent periods of 12.29 years and 2.67 years in the time series with 95% confidence level.GES method can provide a new approach for variation law and phases analysis study of runof series.
Abstract: The social-economic dynamic model(SEDM)reflecting land use and land cover(LULC)variation is coupled with the regional climate model(RegCM3)and used to simulate the regional climate change in north China as if a large scale of agriculture and pastureland is irrigated after the completion of the South-to-North Water Transfer Project(SNWTP).The preliminary simulation results show that the large-scale agriculture irrigation might cause significant regional climate change in China1 During the most possible irrigation time of summer months from June to August,the ground temperature,sensible heat flux as well as the potential height at 500 hPa are all decreased within the irrigated region and the adjacent areas,while the low-level air humidity,cloud cover,latent heat flux and precipitation are all increased.The large-scale agricultural irrigation not only changes the water vapor factors of soil moisture and air humidity,but also the thermal factors,such as temperature,the sensible heat flux,the dynamic factors of potential height and wind field in the atmosphere,which cause the regional climate change in the whole numerical domain.
Abstract: It is indicated that the successive grain total yield increase leads to the accordingly increasing groundwater exploitation in the plain of Hutuo River basin since 1953,and that the saving level of irrigating in the farmland is rised while the rate of groundwater exploitation is reduced.The groundwater exploitation will actually increase the grain total yield up to 142.3×108m3/yr according to the average intensity of exploiting groundwater(3.11 m3/kg)for the irrigating farmland from 1953 to 1970,which is 117.9×108m3/yr more than the practical exploitation(24.4×108m3/yr).The exploitation increases averagely 2.45×108m3/yr in each five years by the grain increasing according to the averagly intensity of exploiting groundwater(0.53m3/kg)for the irrigating farmland from 2001 to 2005,and increases averagly 11.74×108m3/yr in each five years according to the average intensity of exploiting groundwater(3.11 m3/kg)from 1953 to 1970.Therefore,the importance means of relaxing the status of the exceed exploiting groundwater in Hebei Plain is to fight drought,water save crop energetically and to regulate reasonably the agriculture planting structure.
Abstract: This paper analyzes the influence of reduced irrigation on water balance of farmland by the soil-water-atmosphere-plant(SWAP)Model.The experiment site is an area controlled by lateral canal in Hetao irrigation district of China.The results show that the ratio of evapotranspiration to total consumed water is over 90%,which further proves evapotranspiration is the leading water-consumed factor in Hetao irrigation district.The result also shows that relative production will fall evidently due to reduced irrigation water.Therefore,when the quantity of water alloted in Hetao irrigation district is cut down from 5.2 billion m3 to 4.0 billion m3,the pattern of crops and irrigation scheduling etc must be regulated newly.
Abstract: Debnath derived the nonlinear schr dinger(NLS)equation form from the general form of the nonlinear wave dispersion relation.In this paper,the analysis of the NLS equation bagins from the 2-order Stokes' nonlinear deep-water wave dispersion relation.The exact solutions of the nonlinear wave are obtained by using the modified mapping method.As this specialization of this equation,the solutions are different from those that obtain and contain the solutions as Debnath did.At the same time,the solitary solution is obtained in the their limit.
Abstract: The flow field around groyne is of the 3D characteristic. In order to analyze the influence of the flow field and river bed scouring and silting on the polutant diffusion,the dynamical compressive models of water and suspended sediment are derived with the volume of fluid method. Considering the pollutant's adsorption and desorption actions,the 3D water quality models are established for soluble and absorbable pollutant in sediment flow. With calculation of the 3D flow affecting the non-submerged groyne,the comparison between calculative and experimental data means that the dynamical compressive models can accurately simulate the free surface and the flow field around groyne. The simulation of pollutant difusion around groyne shows that the backflow behind groyne slows the decay of pollutant concentration. The turbulence of water flow around groyne increases soluble concentration and absorptive capacity of the suspended sediment markedly under river bed scouring and silting conditions.
Abstract: The experiments are conducted about the influence of the aeration on dynamic pressure on riverbed before the scour hole formed is formed.Results show that the aeration enlarges the dynamic pressure on the riverbed bottom in the jet impact field before the formation of the scour hole. However the dimensionless mean pressure distribution at jet stagnant,the dimensionless mean pressure distribution on riverbed and the dimensionless ultimate dynamic pressure distrbution of the non-aerated flow and the aerated flow obey same rules. The dynamic pressure on the scour hole bottom is studied by means of the experiments,and the dynamic pressure characteristic during the scour process in the jet impact field is obtained,which indicates that the influence of the aeration on the dynamic pressure on bottom of scour hole is not obvious,and the root mean square of dynamic pressure distribution of the aerated jet on the botom has no certain disciplinarian compared with the distribution of the non aerated pure water jet.
Abstract: Coastal salt marshes are the important intertidal ecosystems at the land-ocean interface.The investigation of the complex flows and the associated solute transport in marsh soils is made in order to improve our understanding of these wetland systems,particularly the relation to the important hypotheses in the marsh ecology:the nutrient outwelling and the plant zonation.In this paper,we modify the SUTRA code to simulate the complex pore water flows and the associated solute transport in marsh soils.We simulate the pore water flow and the associated solute transport in a salt marsh based on an imaginary creek section.The results show that the pore water flow and the associated solute exchange near the tidal creek are more intensive than in the inner marsh,which prevents pore water solute near the creek from concentrating or accumulating.During the ebb tide,the pore water flow near the tidal creek is both vertical and horizontal,while it is primarily horizontal far from the creek. The optimal aeration condition is also found occurring near the tidal creek.These results are consistent with the observation that the salt marsh plants often grow better near tidal creeks than in the inner areas.
Abstract: In this paper,taking Dali River Chabagou watershed and Dabucha watershed on Loess Plateau as examples,a new multifractal mathematic model for the large region based on the height distribution probability(HDP)is provided and established for describing the topographic characteristics of watershed by using multifractal theory.The meaning of multifractal spectrum of the topographic characteristics is discussed.The results show that:(1)the multifractal spectrum can express the topographic characteristics of a watershed more sensitive and comprehensive than the simple fractal one.The width of the multifractal spectrum can characterize the degree of the undulation of a surface quantitatively.The difference of the fractal dimensions between the maximum and minimum probability subset can give a statistical result of the ratio between the numbers of lowest and highest sites,which reflects the ratio between the peaks and valleys indirectly.(2)The multifractal spectrum can scientifically represent inner fine structure of a watershed and emphasize the abnormity partial variations of a watershed.And(3)the rational range of the non-scale domain should be identified from the cell size to the 1.5 times the height extremum of the watershed.
Abstract: Heterogeneous soil water flow was investigated by using the iodine-starch staining patterns.The field experiments were conducted at four plots with ponding water depths of 20,40,60,and 80 mm,respectively.The stained patterns of soil profiles show that soil water flow changes from the preferential flow with a few flows path and low stained coverage to the homo-geneous infiltration of the decreased unstained areas with the increase of ponding water depths.The redistribution of infiltration water is mainly influenced by the stained patterns.Flow patters are characterized by using the distributions of the maximum and actual depths.The heterogeneous soil water flow patterns from the four experiments show the multifractal nature.The flow heterogeneity is closely correlated to the multifractal spectrum.The constitutive properties of the fractal spectrum function are determined by the soil texture,whereas the range and shape of the function are affected by the nonlinearity of the heterogeneous flow.
Abstract: Taking the plain area in Liaoning province as example,This paper establishes a mathematical model for groundwater system in typical area,presents a variable hydro-geological parameters simulation method about the equivalent permeability coefficient of aquifer and average specific yield,and shows an improvement about the routine zoning method,which is used in the constructed model to increase the precision of the model.We use the modified finite element method to numerically discrete to the model,and establish the calculation program by using Visual Basic.The simulation result is better for the groundwater1 The constructed model provides condition for the research of the sustainable utilization of groundwater in the plains in Liaoning province.This method provides significant reference for the model research on similar area.
Abstract: This paper presents the results of bias corrections for Geonor T-200B Pluviometer and Chinese standard precipitation gauge(CSPG)measurements in the middle of Tanggula Mountain,Tibetan Plateau.The precipitation observation in frigid mountainous areas is always the bottleneck for studies of regional hydrology and climate.During May-December 2005,a continuous meteorological measurement was conducted in the Dongkemadi glacial drainage.In the meantime,we take up a comparative analysis of the precipitation observation between ability of Geonor T-200B Pluviometer and CSPG.Based on the correlative relationship between precipitation type and temperature,the precipitation type can be divided by using the observed contemporary temperature 2.7℃ in the mountainous areas,therefore,the observed precipitation values are corrected.The bias corrections results show that the corrected precipitation value(662.1mm)of T-200B Pluviometer is closer to the corrected value(657.2 mm)of CSPG.The precipitation in 2005 compared with that of 1993 increases by 200 mm because of the bias corrections.Therefore,this study has great importance for reducing precipitation observation error in the frigid mountainous areas.
Abstract: Based on the daily climatic data from the nation weather station in 1956-2000,the paper employs the P-M equation and the sensitivity coefficient method to analyze the evolution rule of the potential evapotranspiration(ET0)and the sensitivity relation of ET0 to climatic variables in Haihe River basin.The results indicate that the annual ET0 series appears decreasing trend with four different sub-stages in the recent 45 years.The multi-annual ten-day average ET0 shows inverse "V" shape, and 61.6% of the whole ET0 amount occurs in the middle-April to the up-August.In space,the multi-annual ten-day average and the annual ET0 have an increasing trend from the upstream to the downstream.Compared with the evolution rule of the climatic variables and the sensitivity of ET0 to them,the evolution rule of the annual ET0 in the whole basin is similar to that of the multi-annual average wind speed,sunshine time and short wave radiation,and inverses to that of the multi-annual average temperature.The evolution rule of the multi-annual ten-day average ET0 has same trend to that of the temperature,actual vapor,and sunshine time,as wel as the short wave radiation.However,in all the sensitivity coefficient of ET0 to these climatic variables,that of ET0 to short wave radiation is maximum in the whole year and the second water resources districts.The sensitivity of the ET0 to any other climatic variables is different in time and space,and the values of sensitivity coefficients vary greatly.According to the analysis above,the ET0cs decreasing trend in the whole basin may be caused by the change of short wave radiation and sunshine time.
Abstract: Based on the runoff data of Nenjiang River in 1956-2006,the Mann-Kendall,the wavelet wave analysis and the cumulative filter methods are used to find out the variation law and its impacting factor of runoff amount in Nenjiang River.The result shows that the runoff annual distribution in Nenjiang River is not uniform and occurs mainly in July,August and September.The result also shows that the runoff amount decreases in the recent 50 years,and more significant in the early of 1960s, while in the 1980s there is a trend of increase,but it isn't significant.In the middle and late of 1990s the runoff amount decreases again.The runoff changes from year to year with a change periodicity of 8 years.And other change periodicities are of 20 years and 40 years or longer.The most important climate factor is precipitation and evaporation.The human activity is also an important factor.
Abstract: In order to study the propagation effect of the precipitation uncertainties on the flood forecasting,the paper presents a methodology combining the fuzzy set theory with the genetic algorithm to quantify the effect of the uncertainty on the discharge simulation due to the precipitation magnitude and temporal-spatial distribution.The uncertainty of precipitation magnitude is represented by the fuzzy set concepts.The random disaggregation of precipitation into the shorter time step takes into account the uncertainty associated with temporal distribution of precipitation.The spatial variations of rainfall fields are represented by the different temporal disaggregation patterns within the sub-catchments.All the kinds of uncertainties are propagated through the fuzzy extension principle.Based on the methodology above,the TOPMODEL is used to simulate the flood events in the upstream area of the Xinning hydrological station.The results show that the uncertainty in the magnitude is more significant than the uncertainty resulting from the spatial-temporal distribution of precipitation.Moreover,there is no more difference between the precipitation uncertainty with time step of 1 hour and that with time step of 0.5 hour.It means the simulated time step of.hour is able to represent the temporal variation of precipitation in the study area.
Abstract: In order to calculate the river ice thickness distribution from Harbin to Tongjiang about 660 km along Songhua River,and based on the fact of the short-term hydrological and meteorological data along Songhua River,the kinetic energy effect of fluid velocity under ice cover on ice growth is added into Stefan equation which is commonly needed meteorological data for the single point ice thickness calculation under the state water conditions.In the case with scarce measured fluid velocity data under ice cover,it is assumed that water flux and roughness is same in the supposed river,then the relationship between the fluid velocity and the river width is set up,and some mean fluid velocities under ice covers at different sites are evaluated. And in the case without measured meteorological data along the river,the average daily surface temperature is interpolated by using the method of inverse distance squared if the ice forms under the same weather system during the ice period.The statistical relation is obtained following the theoretical analysis and limited hydrological and meteorological data.Based on the calculated results from Harbin to Tongjiang along Songhua River,660 km long,it shows that the human interference in the fluid velocity affects the ice growth rate and the calculation of longer river has higher accuracy.
Abstract: The mechanical breakup of ice covers during spring often lead to the serious ice-dam formation.However,the method for predicting the ice-cover breakup based upon the mechanical principle is in short supply.In this paper with the mechanical-analysis methodology the mechanism of the longitudinal-crack formation during the river-ice initial breakup is fully investigated by using the theory of beams on elastic foundation.A theoretical expression for predicting ice-cover breakup is presented.The comparison with the field observations indicates that the presented formula can to predict the location accurately.
Abstract: The black water cluster(BWC)has occurred in the north part of Taihu Lake,especially bloomed in near-bank of Gong Lake and Yixing in 2007 and 2008.This paper analyzes this phenomenon using the observed data and historical data. The results indicate that the main cause of forming BWC is the combination of the high pollution load,the dead algae in water, the sludge distribution,the wind of fields,the temperature fields,and the water level in the lake area.It provides a way and basis for the study of formation mechanism and control counter measures of BWC.
Abstract: According to the investigated water demand of various sub-regions in the lower reaches of Tarim river,the paper establishes and solves the optimal alocation model for the water deliveries by using the nonlinear optimization theory with the constrained conditions. By employing the famous Kuhn-Tucker condition method,this paper solves the optimal allocation model for the water deliveries to the lower reaches of Tarim River and obtains the reasonable allocation of water quantity for various sub-regions of the lower reaches of Tarim River. The result indicates that the improved eco-area of 1490 km2 is achived through the water deliveries(3.4×108m3)to the lower of Tarim river.This reasonable al ocation model of water quantity will provide technical support for the water deliveries in times of emergency in the future.
Abstract: The accelerated change of the glacial environment due to the global warming and human activity is significant Glacier lakes outburst has become a serious disaster in mountainous areas. In order to understand the glacier lake outburst and find a reasonable assessment way for the glacier lake outburst assessment,this article summarizes these main methods for glacier lake outburst assessment developed by the researchers fromal over the world,explants some problems existing in current studies and analyzes the advantages and disadvantages of each methods. Finally,some new ways in the future research are discussed,which gives some information and suggestions for the future study.
Abstract: The risk analysis in hydraulic engineering system is classified into the single risk assessment and the comprehensive risk assessment in this paper. Various risk analysis methods,developed and applied in hydraulic engineering system,are summarized including the applicable conditions,advantages and disadvantages of each method and their interrelationship. The main methods for the single risk assessment are the mathematical statistics methods,concerning the stochastic uncertainties of the hydraulic system. The comprehensive ones,on the one hand,can take into account the stochastic,fuzzy and grey uncertainties;on the other hand,there still exist some problems,such as the correlation,consistence and impact analysis of behavior factors. Based on the review,some suggestions are putforward,such as choosing appropriate assessment method and integrating the probability with the consequences in risk analysis.