Abstract: The relationship between the capillary pressure and the saturation in two phase system is the basis of gaining the relationship between the capillary pressure and the saturation in the multi-phase system. A simple and reliable setup is employed to obtain the relationship between the capillary pressure and the saturation of the water air and oil water system in the sand and soil samples. The experimental results show that,for a two-phase system with different porosity of porous media,the saturation is bigger with the reduction of porosity under the same capillary pressure;for different two phase system with same dry bulk density,the curve of capillary pressure and saturation in sand appears flater at less than a special capillary pressure value and steeper at the bigger capil ary pressure.However,the curve of the capillary pressure and the saturation in soil seems steeper than in sand. The data analysis shows that the measured values of the water-air and oil water system accord with the scaling method based on van Genutchen(1980)relation mainly proposed by Parker;and when the relationship between the capillary pressure and the saturation in one two-phase is known for a system with a specific porosity and a specific porous medium,those of other two phase can be gained by using scaling method,and the estimated value is in better agreement with the measured one.
Abstract: To address the flow heterogeneity issue,the objective of this study are to investigate heterogeneity of soil water flow at different measurement scales using dying infiltration experiments and characterize the heterogeneity information included in different scales with the random cascade model. The random cascade model with a lognormal distribution is used to simulate the infiltration process in soils,and the different methods are applied to estimate the model parameters. Results based on the experimental data and the model simulations show that the measurement scale is important factors affecting the flow patterns in soils. To accurately describe flow transport processes at different scales,it is necessary to consider heterogeneities in the vertical and horizontal directions. As the measurement scale increases,the effect of multi-dimensional heterogeneities on the flow processes in soils becomes more significant.
Abstract: To make known the process and the mechanism of the chemical transport in the soil-stone mixture,we measured the process of the water and solute transport,based on the displacement experiments using Cl- during the saturated and steady flow in the soil containing rock fragments,and stuied the effect of different content and constitutes of rock fragments on the breakthrough curves of the solute. The parameters(D,R)of classic CDE were fitted to the measured BTCs using CXTFIT211 at the given pore velocities. The results show that:D values varied from 0.258 cm2·h-1 to 22.31 cm2·h-1,and R values from 0.6 to 1.54.The relations between the soil-stone ratios and the averaged pore velocities,the dispersion coefficients and the dispersivitis all fit the power functions repeatedly. After correlate analyses,the effect of size and constitutes of rock frag-ments on the parameters is expressed in the content of rock fragment. When the content of rock fragments smaller than 5mm increases,the pore velocity and the D have decreasing trend;while the rock fragments bigger than 10mm in diameter are favorable to the solute transport. The result of transport of the non-reactive anion in this paper may provide important data and be useful for better understanding of the solute transport in the heterogeneous porous media.
Abstract: The pipelines with circular cross section are widely used in the pract ical engineering. It is necessary to determine the flow discharge and the velocity under the partially filled condition. Most of the existing formulations use hydraulic radius as a characteristic-length parameter to reflect the influence of cross-section shape. The studies indicate that the results calculated from these types of formulations represent poorly the actual flow characteristics,especialy when the flow depth reaches the top of pipe. Based upon the principle of hydrodynamics and the experimental study,the dyadic characteristics between the flow discharge and the degree of fullness for the partially fil ed uniform flow in circular-section pipelines are fully analyzed,and a more accurate expression using discharge as the shape parameter is developed.
Abstract: The catastrophic forest fire on the northern slope of Great Hing'an Mountains in 1987 greatly affects the ecological environment. Wetland,as one of the important attributes,is very sensitive to the environment change. The Yuying and Fendou farms administered by Tuqiang forestry bureau,one of the mainly burned area in 1987 fire,are selected as the study area to reveal the wetland pattern change and the restoration of the regulating capacity of forest hydrology post-fire with GIS software. The results show that the total area of wetland increases by 77.56% with convergence tendency compared with that of pre-fire, and the average regulating capacity of forest hydrology restores a lot,but the area of high regulating capacity of forest hydrology decreases. The regulating capacity of forest hydrology,terrain factors and fire severity is related to the wetland pattern change. The increase of wet land is remarkable in valley,gentle slope and severe burned area,and also in area with decreasing regulating capacity of forest hydrology.
Abstract: The dynamics of nitrogen(N)in the atmospheric wet deposition in typical wetland ecosystem of Sanjiang plain was studied from July 2004 to June 2005,and its ecological ef ects were also analyzed. The results show that there are significant differences among monthly average N concentrations,and the seasonality is evident. The reasons are mainly correlated with human activities,precipitation intensity and frequency,wind direction,geographical location and NOx natural emission. The total inor ganic nitrogen(TIN)is the main body of the total nitrogen(TN)in wet deposition(51.38%~98.96%),and the ammonium nitrogen(NH4+-N),nitrate nitrogen(NO3--N),especially NH4+ N,are the main body of TIN. The path of precipitation synoptic system,to a greatextent,affects the composition of N in wet deposition. The precipitation only has faintish negative correla tions with N concentrations(p>0.05),but the NH4+-N has significant positive correlations with NO3--N and TON(p<0.05), and they might have homologue. The better correlation between NH4+-N and NO3--N is mainly related with their reactions in liquidoid. The growing season is the important phase of N deposition in a year,its deposition amount is 1.84 folds of that in non growing season,and their proportions are 64.78% and 35.22%,respectively. The deposition amounts of N in growing season are much higher than those in non growing season except nitrite nitrogen(NO2--N)The total N deposition amount in a year is 7.57 kg/hm2,and TIN/TON ratio is 5.47. These show that TIN is the main deposit ion body and its proportion is 84.56% Moreover, NH4+-N and NO3--N are the main body of TIN,and their proportions are 52.55% and 30.03%,respectively Further analysis indicates that N is the limited factor that affects the growth of plant. The N deposition in growing season has direct ecological signification which might stimulate the growth of plant,but in non growing season,the N deposition has indirect ecological signification which can greatly supplement the nutrient in initial growth stage of plant in the second year.Anyhow the ecological func tions can not be neglected. In recent years,the decrease of N deposit ion amount in wetland ecosystem might be the important cause which induces the wetland degradation,nor can its ecological effects be neglected.
Abstract: Based on the investigated data of sea ice physical processes during the Second Chinese National Arctic Research Expedition(CHINARE 2003)in the summer of 2003,the sea ice dynamical characteristics are analyzed and the parameters expressing these characteristics are given. From these parameters,the new findings are:(1)The ice density from investigation is lower than 2-3 tenths compared with that from NOAA Ice Chart,and the ice thickness in the summer is less than 2 m compared with the results invest igated during the First Chinese National Arctic Research Expedition in 1999(CHINARE 1999); (2)The standing deviation of ice bot om fluctuation is 3.8 times of that of the snow surface on the ice sheet and(3)the maxi mum speed of ice floe CHIS7 is 1300 m/h in rotation and oscil ation While the floe moves toward North-east,the rotation angle increases step by step with the maximum of 37.8,and while the floe moves toward South-east,its rotation angle decreases step by step. The oscil ation period of the floe is 12.45 h consistent with that of the inertia current at the same latitude,which shows the contribution of the inertia current to the ice floe movement.
Abstract: The broad-shallow and shifting channels in Xinjiang have characteristics of shallow water depth,steep gradients, high flow velocity and easily scoured river bed. Its backwater,due to bridge constrictions,is different from that of alluvial channels. In this paper,a simple formula is developed for estimating backwater by generalized mobile-bed river engineering model experiment. As it reflects characteristics of the broad-shallow and shifting channels in Xinjiang,author's formula fits in with this kind of rivers preferably.
Abstract: In order to establish a special well-balanced scheme technique for dealing with source term due to bottom topography constructed,this paper develops a well-balanced Godunov-type scheme of the second-order accuracy for 2D shallow water flow with triangle mesh. The numerical flux of the interface between cells are computed by the exact Riemann solver,and the improved dry Riemann solver is used to deal with wet/dry problem. The model is verified to compute some typical examples and the tidal bore on the Qiantang river.The results show that the scheme is robust and accurate,and worthy to be brought into wide use.
Abstract: The length of hydraulic jump in the gradually broadened channels is studied in this paper. Firstly,the hydraulic pressure acting on the hydraulic jump in the gradually broadened channel is analyzed,and why the length of hydraulic jump is always shorter in the gradually broadened channel than in the non-broadened channel expounded Considering the influence of the divergence angles on the jump,an approximate expression for the water surface profile of the jump in the gradually broad ened channel is written based on this analysis From the expression,the momentum equation and the cont inuous equation of the flow,the semi empirical formula for calculating the length of the jump in the gradually broadened channel is derived At the same time,the simplified solution to the semi empirical formula is proposed by employing an empirical formula for calculating the length of hydraulic jump in the non broadened channel Secondly,the limitations of the semi empirical formula are pointed out Based on the limitations,the applicable ranges of the semi empirical formula are obtained In the ranges the validity of the semi empirical formula is verified with the experimental data Lastly,the most empirical formulae for calculating the length of hydraulic jump in the gradually broadened channel are classified and some are recommended for the designers of the stilling basin We hope that the recommendation is useful to the designers.
Abstract: At present,some problems are found in the current water environmental function zoning. Based on the theory of the landscape ecology,the watershed protection approaches and the ecosystem services,the methods of ecoregions,the the ecosystem integrity assessment,and the comparative analysis,this paper proposes the concept of water environmental function zoning at watershed scale(WEFZWS)and analyzes its meaning,technical approaches and key problems. This WEFZWS is consistent with the international trend and the national requirement,especially at watershed scale,harmony and the site-specific and dynamic. And this WEFZWS efficiently balances the relationship between the human demand function and the water ecosystem demand function,and harmonizes the conflicts in trans-boundary regions,and synthetically considers the use of water resource,the environment restoration and the water ecosystem protection. In a word,this WEFZWS will promote China's water environment management and watershed management in the future.
Abstract: In this paper an approach to simulate bed load graing due to degradation in alluvial rivers with sand bed is presented. The approach is characterized by introducing a new equation for the evolution of the bed graing in an active layer. The equation permits to describe both the temporal and spatial variances of the bed graing in the active layer.Therefore,in the case of the degradation,the method has ability to simulate the process that the coarsing of the bed material initially occurred at the bed surface which progressively develops into the inner part of the river bed. Being a nonlinear partial differential equation which must be solved with the flow and sediment transport equations,a numerical methodology for the approach is also described in this paper. The simulations of the bed graing during degradation of the channel bed by the approach agree satisfactorily with the available experiments conducted in laboratory flumes. The approach can be useful in the numerical modeling of the fluvial processes.
Abstract: Based on the observed streamflow of 19 key hydrological control stations in the six larger basins in China for the past 50 years,this study employed the Mann-Kendall test to detect trends of annual runoff. It was found that annual runoff in the six larger basins has generally decreased during the periods,with signicant decreases detected in the northern China. Especially in Haihe river,Yellow river,Liaohe river and Songhuajiang river,there are remarkable decreasing trends.
Abstract: Input data aggregation is a common method for representing watersheds in the distributed-parameter models. To integrate a number of simpler process-based sub-models derived at different scale is one way to build distributed hydrological models. Both the spatial aggregation of watershed information and the model structure have significant impacts on the model output. This study investigated how different watershed partitioning affect flow,sediment and nutrient quantitatively using SWAT2000. The conclusions are:(1)Annual sediment yield and nutrients predictions are highly sensitive to the number of sub-basins used to represent a watershed,but runoff is not.(2)There're two thresholds for model output response. Below the lower threshold,although we can also get reasonable results by calibration,it might not fulfill the spatial demand for environmental management and programming. Above the higher threshold,distortional output may occur. The determination of the thresholds depends on the actual watershed characteristic. And(3)the sensitivity of sediment is bigger than TN and TP to the number of sub-watersheds when few subwatershed is partitioned,and smaller than TN and TP when more subwateshed is partitioned.
Abstract: With the development of economy and society,the conflict between water supply and demand aggravates. The water right system needs to be set up in order to control the overuse and unlimited demand of water resources. The allocation of water right is an essential part of the establishment of the water right system that should be established early. After classifying the all ocation principles of water right of use suggested by some experts in China,the leading principles are set out as follows:the ecological water guarantee,the prior appropriation,the basic water guarantee,the equity principle and the high efficiency principles. Based on these all ocation principles,the model on water right of use allocation is set up,using Genetic Algorithm (GA)to work out the multi-objectively non linear model. The convergence and stability of GA is analyzed by taking the Yellow River basin as an example. The allocation results of the surface water right of use are compared with "87-water-allocation-scheme" for the Yellow River basin.
Abstract: The reference evapotranspiration(ET0)is a crucial factor which affects water balance analysis of wetlands. By fitting the FAO56 Penman-Monteith equation,a new empirical model is established,which can evaluate the monthly ET0 in the region of Zhalong wetland. The meteorological data used in the model come from eight weather stations around Zhalong wetland from 1961 to 2000. Several combinations of meteorological parameters,which affect the reference evapotranspiration obviously, are introduced in lots of fitting models in order to choose the fitted expressions. According to the maximum fitting correlation coefficient(R2)and the minimum root mean square error(RMSE),the nonlinear exponential model with monthly maximal temperature,minimal temperature,total precipitation and wind speed is selected. In order to understand the effectiveness of the model,three commonly used empirical models,Blaney-Criddle,Priestley-Taylor and Hargreaves,are used to compare with the new one,and the answer is positive. The applied results show that the new model improves the R2 and reduces the RMSE markedly. Consequently,it can serve as a useful tool for monthly ET0 calculations in the study site.
Abstract: Maintaining river's healthy life and realizing human-water harmony are our goal of the river management in the new era. Based on approaching the meaning of river's healthy life,this paper constructs evaluation index system for river's healthy life,which takes into consideration the satisfiactory degree of human society as well as the requirements of river's own life. From the multi-disciplinary synthesis,such as ecology,river morphology,economics,river mechanics,etc.,it constructs sixteen specific indices which reflect river structure and function at different layers and classes,indicates the meaning and the determination approach to the indices,and finally determines the index weight through the layered binary compared the expert analysis method.
Abstract: The urban heat island(UHI)can greatly reduce the comfort of the people who live in cities. Due to the regional weather and complicated surface conditions,the UHI can appear in cities,which can be affected by the human act ivities.The UHI in Beijing is remarkable,and its averaged intensity is about. eduring the period 1960-2000. The present research is done about the numerical simulation of the heat island in Beijing,and focuses on investigating wind and temperature fields near surface which are influenced by various land surface conditions.And the various urban canopies can affect the UHI to certain extent. A regional numerical model,MM5,is employed in this research. The simulation results show that the MM5 model success-fully simulates the heat island effect on Beijing. Comparing the MM5 with the coupled model of MM5 and Noah LSM,the results show the MM5-Noah LSM coupled model does a better job.
Abstract: During the Jinta experiment in 2004,sounding balloons were set free to collect the meteorological data in the upper air,such as temperature,pressure,and humidity to calculate the total water content in the air. Then,the remote sensing data of EOS-MODIS are used to revert the total water vapor content The retrievals are compared with the observed ones,as a result,the maximal relative error is 8.02%,the minimal is 0.70% and the average relative error is 4.5%,which shows that the reversions are believable According to the regional distribution of the water vapor content and the section plane along the sounding site from East-West and South-North,there is biggish difference in the spatial distribution of the water vapor content. The water vapor content,in all,is relatively less over the gobi and hungriness and more over the oasis;there is "the clothesline effect" which influences the stabilization and development of the oasis at the margin of the oasis or the long and narrow protection forest through the deserts or in the neighborhood of the river and the aqueduct.
Abstract: The development of hyperspectral technology enables the quantitative monitoring of water quality based on the hyperspectral data. By now,the ordinary monitoring method always depends on the developing relat ionships between radiance/reflectance in single band or band ratios and the chlorophylla concentration. In this paper,a spectral mixing model is established based on the field hyperspectral data. And three types of data,the original,normalized and differential data,are selected as the input. The optimal band range(670-710 nm)which indicates the chlorophylla concentration is selected,and the chlorophylla concentration is reverted by the linear spectral mixing model in which the water and chlorophylla end-member spectral come from in situ water samples. The compared results show that the spectral mixing model based on differential data gives the best result in the model precision and stabilization. Finally,three-phase field hyperspectral data are processed and the chlorophylla concentration is extracted by using this spectral mixing model. The result shows that the spectral mixing model is a feasible,stable and of high resolution model in the pract ical application of remote sensing water quality monitoring.
Abstract: Immunity,a basic physiology,is derived from the research of anti-infection,whose organism recognizes antigenicity eyewinkers and rejects them. Modern bionic technologies use immunity to solve nonlinear programming problems and form particular artificial immune system(AIS)which represents feasible solutions through antibodies and embodies constrains and objective function through antigen. AIS also adopts anticipant productive rate to define selection probabilities which can be used for random search of the whole optimal solution. According to the application of AIS to the short-term optimal scheduling of hydro plants in cascade,the AIS is confirmed.
Abstract: In cone of depression areas caused by the over-exploitation of groundwater resource,the construction and planning of groundwater reservoir with the depleted aquifer space is of great significance for sustainable development and utilization of regional water resource. In this paper,the author defines the operation of water levels and reservoir capacities. Meanwhile,the spatial distribution of the reservoir capacity is analyzed by the ArcGIS. It can be concluded that the total capacity of groundwater reservoir is about 7×108m3,and the utilizable capacity is more than 4.4×108m3.Furthermore,the spatial distribution of reservoir capacity is different,which is caused by the specific yield and the groundwater depth.
Abstract: The evolution processes of the distributed hydrologic models are reviewed,and their building ways are analyzed. The physical basis is a key kernel of the distributed hydrologic models. A new and comprehensive explanation is given for the connotation of "physically-based". Two kinds of popular models,the distributed physically-based models and the distributed conceptual models,are discussed,especially about their existing problems and future. Finally,two new promising developmental directions are discussed:one is a physically-based incompact structure distributed hydrologic model that integrates the advantages of the above two kinds of popular models;the other is a deterministic-stochastic coupled distributed hydrologic model.
Abstract: This paper summarizes the concept and development of aquatic ecological region,introduces the indicators,depicts method and system of aquatic ecological regionalization by taking U.S.A. and Australia as an example,and analyze the application of ecological region in the field of water quality,stream biological monitoring,lake and reservoir management,wetland management and aquatic biology conservation in detail. According to analysis of the present status of the aquatic regionalization in China,the paper proposes the frame of the aquatic ecological regionaliation in China and discusses the indicators for the ecological regionalization,and finally predicts application prospects of the aquatic ecological region in China.
Abstract: The latest developments of the remote sensing of lake water quality,such as the mathematic methods for the remote sensing of water quality model,the water quality indicators with the most sensible wave band and applications of TM,SPOT, MODIS,MERIS,AVHRR,CASI etc.,the satellite sensors and the airborn remote sensing,as well as reasons and solution which probably result in the errors of remote sensing of the lake water quality model,are explicated and analyzed. It can be regarded as the most complex and non-linear black-box model for the effect of several components in lake water on each other. Thus it is the most useful for the remote sensing of water quality simulated by Bp ANN. And the sensible band,the ultra-spectrum as well as wave bands clearly associated with water quality indicators should be selected and studied. A good way of making the remote sensing of lake water quality become a practical monitoring method is that water quality remote sensing must be combined with the aquatic eological problems.As a monitoring tool,it would be combined with the algae distribution in water, the nutrient transportation model and the lake water quality model. The ultra-spectrum data is seldom used in China,because the band width for the water quality monitor of sensor is not very suitable in China. We should develop the water quality sen-sors by ourselve.