• 全国中文核心期刊
  • 中国科技核心期刊
  • 美国工程索引(EI)收录期刊

2009 Vol. 20, No. 5

Display Method:
Retrieval of the daytime pixel-level hourly rain rate using FY-2C’s dual-spectral imagery
ZHUGE Xiao-yong, YU Fan
2009, 20(5): 607-613.
Abstract:
Based on the geostationary meteorological satellite FY 2C's multi-spectral data of China,this paper studies the method using thermal infrared bright temperature and visible light albedo to imitate and demonstrate the pixel level hourly rainfall rate and rainfall intensity class.We firstly employ the rainfall probability analysis matrix to differentiate precipitation cloud and non precipitation cloud with the skill score reaching 0.5073 This notably improves the accuracy of the rain area estimation compared with the threshold value distinguishing method.The accuracy of analyzing hourly rain rate with the method is about 52.19% if the deflection of ±20% is permitted.And after the test of more than 1200 samples,the accuracy of this investigation of small,middle and heavy rain and rainstorm reaches 62.79% Furthermore,if we consider the tiny rain with its rain rate less than 0.5 mm/h as the non rain case,the accuracy of the rainfall rate est imation can reach 88.17%.
Method for calculating Lhasa reference crop evapotranspiration by modifying Hargreaves
YANG Yong-hong, ZHANG Zhan-yu
2009, 20(5): 614-618.
Abstract:
In this article,we analyze comparatively the two results from Penman-Monteith and Hargreaves of Lhasa reference crop evapotranspiration(ET0) based on the data from Lhasa weather stations during 1955-2006.The calculated results show the Hargreaves method still has a large deviation in Lhasa in spring and rainy seasons.To further enhance the appropriateness of the Hargreaves methods in Lhasa,we establish and evaluate the method of modifying Hargreaves by introducing the humidity factor,it thus provide a simple method and scientific proof for the accurately determining the water demand of cropand the irrigation schedule in Lhasa region.
Risk study of the bivariate encounter of interzone rainstorm and flood level of the outer river
LIU Zeng-mei, CHEN Zhi-sheng
2009, 20(5): 619-625.
Abstract:
The waterlogging control methodology and the drainage capacity are deeply influenced by the flood level of outer river which encounters interzone rainstorm,so it's necessary to study the risk rule of the interzone rainstorm encountering with the outside river flood.The Copula theory is applied to construct the joint distribution of inter}ne rainstorm and the flood level of the outer river.The density of the bivariate joint probability is used to describe the chance of the bivariate encounter.The methods used to analyae the risk probability and the risk return period is presented.The case study is conducted and the resups indicate that the Cbpula function is able to simulate well the joint distribution of the interzone rainstorm and the flood level of outer Lianjiang river in Yangshan of Guangdong Province.The bivariate joint probability density clearly shows the characteristic of the positive skew distribution.The interzone rainstorm with a return period of no more than ten-year is most likely to encounter the flood level of outer river with the same frequencies,while for the interzone rainstorm with a return period of more than ten-year,the return period of the flood level of outer river corresponding to the maximal chance of encountering is smaller than that of the interzone rainstorm.For any return period of drainage,there are many kinds of combined schemes between the return period of the interzone rainstorm and the flood level of the outer river which are of the inverse correlation,and the return period of the interzone rainstorm is bigger that of drainage in any combined scheme.
Influence of sampling frequency and sample size on turbulence statistics in open-channel flow measurements
WANG Long, LI Dan-xun, YANG Sheng-fa, ZHONG Qiang, WANG Xing-kui
2009, 20(5): 626-631.
Abstract:
The influences of sampling frequency and sample size on the accuracy of turbulence measurements are experimen tally investigated.A set of 340535 velocity data are first sampled at a frequency of 600Hz with the particle image velocimetry to measure the turbulent parameters of the flow.A series of statistical samples corresponding to various sampling frequencies and sample sizes are then achieved by extracting data from the original data set.Comparison of the mean velocity,turbulent in tensity,and Reynolds stress obtained from these samples reveals that sampling frequency and sample size both show a threshold value above which the measured turbulence characteristics become relatively stable,and that,to achieve the same level of the experimental accuracy,the required sampling frequencies and sample sizes increase progressively in evaluating mean velocity,turbulence intensity and Reynolds stress.
Numerical simulation of influence factors of slot-generated thermal buoyant jets
WANG Ling-ling, YUE Qing-hua
2009, 20(5): 632-638.
Abstract:
A three-dimensional numerical model of the coordinate is developed The σ-coordinate transformation transfers the irregular physical domain with the wavy free surface and uneven bottom to the regular computational domain with the shape of rectangular prism The Smagorinsky model is used in the modeling The operator splitt ing method,breaking the solution procedure into the advection,diffusion,and propagat ion steps,is used to solve the modified Navier-Stokes equations and energy equation The model is used to simulate thermal buoyant jets in both stagnant water and wave environment,to compare the distribution of velocity and temperature,the decay law of the mean velocity along axis and the self-similar characteristic,and to numerically analyze the influence factors such as the width of slot and the difference of temperature The numerical result is of great practical importance for the design of the thermal and wastewater diffusers.
New method for reducing the numerical error in solving the problem of contaminant transport in ground water
MEI Yi, WU Ji-chun
2009, 20(5): 639-645.
Abstract:
The numerical simulation of the contaminant transport in subsurface porous media have been a hotspot for years.It is always considered to be tough to deal with the problems regarding the numerical dispersion and the oscillation around sharp front area of contaminants.This paper presents a new method which can reduce the numerical dispersion in the numerical modeling of the contaminant transport in groundwater.The core of the new method is adding a new numerical dispersion estimation term to the hydrodynamic dispersion coefficient and obtaining a modified hydrodynamic dispersion coefficient(MHDC).We use MHDC instead of the traditional hydrodynamic dispersion coefficient and put forward a new parameter of numerical dispersion factor(μNDF).The research area can be divided into different μNDF areas,and their values can be adjusted according to our needs.In this way,we can control the numerical oscillation and diminishing the numerical dispersion.The Simulated results of several examples from one-dimension problems to two-dimension problem indicate that the new method can considerably reduce the numerical dispersion on the basis of diminishing the numerical oscillation and obtain more precise simulation results.Hence,the new method is simple in theory,convenient in application and worth popularizing.
Experimental study on the behavior of horizontal turbulent side jets in compound open channel with vegetated plain
HUAI Wen-xin, QIN Ming-chu, YANG Zhong-hua, ZHAO Lei
2009, 20(5): 646-651.
Abstract:
The Micro ADV is used to test the round jets in the cross flow in the unsymmetrical compound channel with vege tated plain for the 3 typical cross sections.The measured velocity fields show that the interact ion between the jets and the cross flow results in bifurcation,which is enlarged by the secondary flow and allayed by vegetation.The half angle of the bifurcation is 5.71°.The velocity and the turbulent kinetic energy of the jet exit plane with different jet-to-cross velocity ratios are obtained.It is found that the jets are anisotropic in the whole flow field.The curvature of the jet curve and the jet center lines's location mainly depend on the jet to cross velocity ratios.The data can be used to validate the turbulent model and the numerical methods.
LES of viscous liquid sloshing problem based on the LBGK method
DING Quan-lin, WANG De-guan, WANG Ling-ling
2009, 20(5): 652-657.
Abstract:
The Lattice Bhatnager Gross Krook(LBGK) method combined with the large eddy turbulent model is applied to the numerical simulation of the viscous flow,and the Volume of fluid(VOF) concept is introduced into the LBGK method,which is used to simulate the action of the free surface The free sloshing of the viscous liquid in a tank as well as the first mode sloshing excited by the nonlinear acceleration are simulated.The pressure distribution at the wall of tank is obtained.The equations of pressure force and bending moment are fitted.Both the theoretical analysis and the simulation result show that themethod in the paper has high precision in the simulation of the incompressible flows with a free surface.
Relationship between ion transport and sediment discharge in river
WANG Jia-sheng, CHEN Li, FAN Bei-ling, CHAI Xiao-ling
2009, 20(5): 658-662.
Abstract:
There exists the mutual influence of ions and sediment in river water.And the sediment discharge and the ion chemical character are linked together.In this paper,the progress of the physical and chemical denudation in a river basin is analyzed,and the relat ionship between ions and sediment is researched according to the data obtained at the hydrological station on Jialing River and Weihe River.The result indicates that the positive relationship between the sediment discharge and ions discharge is evident,the related coefficient changes if the ions.category changes,and the relationship is different in the different river.
Physically based retrieval of soil moisture using passive microwave remote sensing
CHEN Liang, SHI Jian-cheng, JIANG Ling-mei, DU Jin-yang
2009, 20(5): 663-667.
Abstract:
The soil moisture inversion algorithm,which is adopted in the soil moisture and ocean salinity(SMOS) mission,uses the semi-empirical Q/H model to figure out the surface emissivity.The Q/H model shows the effects of the surface roughness on the emissivity at V polarization are same as that of Hpolarization.In this study,we use the advanced integrale-quation model to generate a simulated database with a wide range of the surface roughness and soil moisture conditions under SMOS sensor configurations and develop a simplified multi-angular surface emission model based on the simulated database.Based on the parameterized model,an inversion procedure is set up in terms of dual-polarization microwave brightness temperatures to retrieve soil moisture with the minimum auxiliary information about the ground.The inversion technique is validated with multi-angular ground microwave radiometer experiment data at L-band from several test sites at Beltsville,MD.The accuracy in random-mean-square error is about 4% at inciden angles of 20°~50°.The results reveal that the proposed inversion procedure decreases the perturbing effects of the surface roughness on the soil moisture estimation.
Infiltration model and numerical simulation of the soil water movement in furrow irrigation
NIE Wei-bo, MA Xiao-yi, WANG Shu-li
2009, 20(5): 668-676.
Abstract:
Based on unsaturated soil water movement theory,the mathematical model of furrow irrigation is developed to un-derstand the characteristic of Two-dimensional soil water movement in furrow irrigation.The simulation results are verified by the laboratory experiments and agreed well with the experiments measurement values,which shown that the mathematical model can be used to study the two-dimensional soil water infiltration in furrow irrigation.The soil wetted volume characteristic of furrow irrigation are simulated and analyzed under different factor combination by this model,the results indicate that soil initial water content and furrow spacing have slight effect on the accumulation infiltration quantity of furrow irrigation,meanwhile the soil character,bulk density,water depth and bottom width have obvious effect on the accumulation infiltration quantity.The bottom width and soil initial water content have a littler influence on the wetting pattern and the wetting soil movement migration,but the soil character and bulk density have a great influence on it.The water depth and furrow spacing have an effect on the water contribution near the zero flux plane,the vertical moist front migration has accelerated after interference infiltration near the zero flux plane.Taking these results as the foundation,the two-dimensional infiltration model for furrow irrigation was established which contained the wetted perimeter.
Parametric estimation of the van Genuchten’s equation based on hybrid genetic algorithm
GUO Xiang-hong, SUN Xi-huan, MA Juan-juan
2009, 20(5): 677-682.
Abstract:
The van Genuchten equation is the most commonly used soil characteristic curve equation,and its parameter value precision directly affects the soil water movement equation computation precision.In this paper,the parameter optimized model for van Genuchten equation was established,and the hybrid genetic algorithm which combines genetic algorithm with Levenberg-Marquardt optimization algorithm was used to solve it.A series of numerical experiments were conducted to verify the model.The results show that the hybrid genetic algorithm has the higher convergence efficiency than the ordinary genetic algorithm,moreover the number of convergence iteration also reduces greatly.The hybrid genetic algorithm has the higher estimate parameter precision than the nonlinear simplex method and the damped least squares method,moreover,do not need the initial parameter value.Therefore,the hybrid genetic algorithm can be can be used to estimate van Genuchten equation parameters as a new method.
Safety threshold of soil water content for reed wetland in Yellow River Delta
XIE Tao, YANG Zhi-feng
2009, 20(5): 683-688.
Abstract:
According to the different soil water contents,the light response of photosynthesis of potted three ecotypes of reeds(fresh water swamp reeds,FWSR,salt meadow reeds,SMR,and salty water swamp reeds,SWAR) collected from the reed wetland in Yellow River Delta are measured,and their moderate soil water content ranges during the fast growing period are compared,so as to provide the evidence for the establishment of the ecological water requirement standards in reed wetland.The results show that the maximum net photosynthesis rate of FWSR,when the soil relative water content is 95.6%,is signifi-cantly higher than that in the waterlogged condition(p< 0.05).However,for SMR and SWAR this difference is not signifi-cant(p> 0.05).The net photosynthetic rates of the three ecotypes of reeds have different response thresholds to the alteration of soil water content.And the tolerance of FWSR to soil water stress is stronger than the other two ecotypes,which may be mainly due to the different soil salinities in their habitats.
Revised random walk model for degradable water pollutant
HAN Long-xi, CHEN Li-na
2009, 20(5): 689-694.
Abstract:
The random walk model for the existing water quality is improved and a quality 2D random walk model considering the role of self-purification is established based on the assumption of a reaction kinetics of biodegradable pollutants and considering the defects that the water quality model for random walk only takes the convection-diffusion of pollutants into account,and neglects the effect of their own degradation of pollutants.Through the typical case of a model test,the results of the improved random walk model and the 2D convection-diffusion equation analytical solutions are analyzed.It shows that the water quality of the random walk model is consistent with that of the analytical solution.The improved model considers the characteristics of the degradation of water pollutants and visually describes the pollutant migration characteristics.
Evaluation method for lake eutrophication influence and public satisfaction
ZHANG Bao, LIU Jing-ling
2009, 20(5): 695-700.
Abstract:
A new evaluation method based on Weber-Fechner Law is used to assess the lake eutrophication and its integrate influence on people.The transparency(SD),CODMn,total nitrogen(TN),total phosphorus(TP),chlorophyll a(chl-a) are selected as the evaluation factors,whose weights determined by the entropy coefficient method are 0.1242,0.1768,0.2140,0.203 4,and 0.28161 The relationship between the entropy impact indexes(Ki) and the eutrophication indexes is also established.Ki standing for the connection of people's feeling with the changes of lake nutritional status,together with the nutritional status of lakes people.s satisfaction is classified into four levels:Better,normal,worse and worst according to the corresponding relationship between Ki values and its change rate with trophic indexes.The case study is conducted on Baiyangdian Lake in Haihe Basin of China.The results show that the average Ki value is 0.0523 and its change rate is 304.67,which suggests that Baiyangdian Lake is in the serious eutrophication status averagely.The people.s satisfactory level with the nutritional status of Baiyangdian Lake is lower.In different spaces of 8 locations of eutrophication from serious to better are as follows:Nanliu village > Quantou > Wangjia village > Zhang village > Shaohce lake > Zaolin village > Caiputai > Duan village.Ki values change from 0.029 3 to 0.10061 People's satisfactory levels are all worse,but exists the space diversity.
Experimental and numerical study on the transfer process of suspended matter in the interaction of wave and current in Taihu Lake
LI Yi-ping, PANG Yong, LUO Lian-cong
2009, 20(5): 701-706.
Abstract:
Based on the experiment and numerical model,the transfer process of suspended solids(SS) in the interaction of wave and current is studied.The results are as follows:Firstly,when the mean wind speed ranges 2 to 8 meter per second,the relationship between resuspend flux and wind speed shows the positive correlation relation.The formula method of Gansith is suitable for computing the resuspend flux of Taihu Lake.Secondly,when the suspended solids concentration(SSC) is low,no clear relationship is found between the settling velocity and SSC.But settling velocity obviously rises with the increase of SSC while the latter is high.Based on the data from the four hydrostatic experiments,it is found that the settling velocity of suspended matter and the suspended matter concentration fitted in logistic curve.Thirdly,the hydrodynamic process of Taihu Lake is described properly based on coupling the wave and current.Finally,the combined effects of the wave and current are included in the SS model.The amounts of suspended and precipitated sediments near lake bed surface layer are treated separately,the stochastic characteristics of turbulent flow pulsation near lake bed are also considered,and the startup conditions of sediment suspension are introduced to the model.The model elucidates the mutual exchange processes between sediment particles in SS and the active sediments within and on bed surface layer.The simulated results show that the lake current has relatively significant effects on the SSC at littoral areas of Taihu Lake,while SSC at the central area of the lake is mainly influenced by waves.
Simulation of backscattering properties of Taihu Lake
LE Cheng-feng, LI Yun-mei, ZHA Yong, SUN De-yong, LÜ Heng
2009, 20(5): 707-713.
Abstract:
In order to study the properties of the backscattering coefficient in Taihu Lake,quasianalytical algorithm and optical closure are used in this paper to stimulate the backscattering coefficient of Taihu Lake according to the field measurement data,and its properties and influence factors are also analyzed synchronously.The results indicate that,because of the variation of the suspended sediment concentration,the backscattering coefficient varies over all sampling stations,and the backscattering is mainly caused by the inorganic suspended sediment in Taihu Lake,while the contribution of phytoplankton is slight.The specific backscattering coefficient also varies among the stations,and the variation mainly results from the difference of suspended particle size,shape and composition.Taking 550 nm as reference to parameterize the backscattering coefficient of Taihu Lake,we can find that there is a greater linear relationship between the backscattering coefficient and the suspended sediment concentration,and the exponent index n ranges from 1.32 to 2.8 with a average value of 2.09.
Dissolved-particulate partitioning of heavy metals in urban road runoff of Shanghai
CHANG Jing, LIU Min, LI Xian-hua, YU Jie, LIN Xiao, WANG Li-li, GAO Lei
2009, 20(5): 714-720.
Abstract:
The partitioning characteristics between the dissolved and particulate-bound fractions of heavy metals in runoff waters in roads are preliminarily invest igated in this paper.56 runoff samples were collected in two rainfall-runoff events in five different areas located in the central area of Shanghai.The results indicate that during the wash-off processes,the 25th percentile concentrations of Cr and the 90th percent ile concentrat ions of Zn,Pb and Cd are over the fifth classified values of the National Surface Water Standards,while the pollution levels of Cu and Ni are relatively lower.The results also show the high positive correlations between the total heavy metal concentrations and the total suspended sediment(TSS) concentrations are in the order of Pb > Cu > Zn > Cd,and the correlation of Ni and TSS is not obvious.The fractions of dissolved-to-total metals are ranked by Cu and Ni of 35%,Zn and Cr of 19%~22%,and Cd and Pb of 4%~8%. With the modified dissolved-particulate partit ioning(Kd) calculated method,the order of Kd is Pb > Cd > Zn > Ni > Cu > Cr.The Kd values of metals show the similar spatial distribution pattern among the different areas.The results also show that TSS concentration has the great negative influence and shows the so-called "particle concentration effect" on Kd values When pH values of runoff belong to the interval of 6.4~ 7.2,it has a relatively weaker effect on Kd values.
Optimal ecological sound operation of the cascade reservoirs in the lower Yalongjiang River
MEI Ya-dong, YANG Na, ZHAI Li-ni
2009, 20(5): 721-725.
Abstract:
The paper investigates the ecological sound operation of the cascade reservoirs in the Lower reach of Yalongjiang River.Based on the type and arrangement of the cascade hydropower stations,two flow control cross-sections are proposed:one is at the downstream location of the division sluice for the Jinping-Ⅱ station,the another is at the backward position of the Ertan dam.25 flow variation control schemes are presented with respective to the ecological requirement of these two flow control points.Then,a longterm optimal operation model,which is to maximize the total output of power generation of the cascade reservoirs,is established and solved by using the dynamic programming method.The total power generation amount and reservoir release discharge process corresponding to each flow variation control scheme are obtained.These influences on total power generation amount of different ecological flow values at the downstream division sluice and flow variation limits on the release discharge of the Ertan reservoir are analyzed,the indicators of power losses to ecological flow needs are defined and their values are calculated.Lastly the fitness of the Ertan reservoir release discharge processes to the natural flow regime is evaluated.The result shows that the total power generation amount of the cascade reservoirs will decrease while the release discharge process of the Ertan reservoir approaches the natural flow regime.
Integrative risk evaluation of regional floodwater utilization
FANG Hong-yuan, WANG Yin-tang, HU Qing-fang
2009, 20(5): 726-731.
Abstract:
According to the characteristics of the regional floodwater utilization measures such as reservoirs,flood detention areas and canal storages and the risk generating mechanism of these floodwater utilization measures,the analysis method synthesizing risk rate and risk degree is used for computing the flood risk from the floodwater utilization of subregions and the various utilizing measures.Based on the relationship between the risk of the regional floodwater utilization and the risk from the floodwater utilizing measures of subregions,this paper proposes the mathematical model considering the fuzzy property of the flood risk assessment for evaluating the integrative risk of the floodwater utilization by using the fuzzy theory and the analytic hierarchy process,details with the hierarchical structure and the solution procedures of the model,the synthetic analysis technique of the risk rate and risk degree and the method for identifying the weights of fuzzy evaluation factors.Finally,taking the Beisanhe watershed in Haihe River Basin as example,the integrative risk rate is computed using the proposed model for evaluating risk in the regional floodwater utilization.
Advances in evaluation study on utility of agriculture water utilization
LEI Bo, LIU Yu, XU Di, JIANG Wen-lai
2009, 20(5): 732-738.
Abstract:
The key issue of agricultural water resources utilization(AWRU) is utility.It is significant to establish target system to evaluate the utility of AWRU for realizing the efficient and sustainable utilization of agricultural water resources.The methods and theories for evaluating the utility of AWRU are in process from water use efficiency to the combination of water use efficiency and benefit.Therefore the scale of evaluating the utility of AWRU is being transformed from micro-level of crop and field to the medium and macro-level of irrigation district,watershed,nation and globalization.The research of the evaluation of AWRU in the future will be focused on the establishment of the target system of AWRU which is based on the different water balance and the transformation and the scale effect at different scale.
Review of the vertical structure of wave-induced currents
ZHANG Chi, WANG Yi-gang, ZHENG Jin-hai
2009, 20(5): 739-746.
Abstract:
The wave-driven current is one of the most significant factor affecting nearshore engineering and coastal evolution.The depth-integrated 2D wave-driven currents are studied with great efforts and applied widely in the coastal engineerings.However,the vertical variation of wave driven currents may result in the structure instability and morphology evolution in the coastal region.There still need More work on this topic in China.Based on the published literatures about the laboratory and field measurements,the theoretical analysis and the numerical simulations,the research progresses in this subject at home and abroad are reviewed,and several opinions on the existing problems and the future developments are proposed.
Definition and connotation of water demand management
Editorial board of Advances in Water Science
2009, 20(5): 747-754.
Abstract:
Water resources are fundamental natural resources and strategic economic resources,as well as controlling element for ecological environment improvement.Water amount per capita in China is about 2 200 m3 on average,which is less than 1/3 of world average,meanwhile,the spatial and temporal distribution of water resources is quite uneven.Water resources regime in China is undergoing a new changing due to double stresses from global climate change and large-scale economic development.Therefore,the concept of water resources management needs to be changed from water supply to water demand.The definition and connotation of water demand management are discussed from different aspects for the purpose of whole profound understanding of water demand management.Water demand management is a sequential system engineering to balance water supply and demand between all water consumers including human being through adopting administrative economic measures and law,to improve water utilization efficiency through limiting irrational water requirement.Briefly,the idea of water demand management is to allocate water based on water supply rather than water requirement,the final target is to realize the harmony of human and water resources,and achieve sustainable utilization of water resources.