Abstract: The data for soil hydraulic properties collected on a 30m×30m field with sandy loam soil has been investigated by the statistical method,the results show that the saturated hydraulic conductivity KS and soil water capacity are the normally distributed,and the pore size distribution parameter α is the log-normally distributed respectively.According to geostatistical method,the spatial stuctures of KS and lnα are characterized by the spherical semivariogram model.The Kriging technique is used for the spatial estimation of KS and lnα,the results indicate that the estimating variances are approximately the same as those when the sample points are reduced by 26 percent,and the average estimating variance of Cokriging method is about 6.87 percent lower than that of the Kriging method for parameter lnα.
Abstract: In this paper, the soil columns(repacked sieved sandy loam, different dry density, 15.3 cm diam.×50 cm long)were irrigated at constant ponded infiltration intensities with a step-change in NaCl solution. The transfer function model(TFM)developed by Jury et al(1982)was used for simulating chloride travel through the soil columns during steady, saturated water. The transport parameter values for the soils were determined by TFM(with an assumed lognormal distribution of travel times). The simulations were tested against experimental values of drainage effluent concentration. In addition, the characteristic values of convective transport of chloride in soils were analyzed.
Abstract: The soil-water pressure is measured by 100 individual tensionmeters for a long time in a 30m×30m field with sandy loam soil in Yongledian Irrigation experimental station.Through analysis, it can be found that the relationship between the variance and the mean of the pressure can be described by a quadric function,and the variance increases with the mena of the pressure. Finally, the semivariogram of the soil-water pressure is simulated.
Abstract: In this paper,a linear programming model of water-rock interaction is established and is applied to the analysis and appraisal of complex hydrogeology condition of Xiluodu power station as an example from geochemistry.The results of research not only show the results of physicochemical reaction of water-rock interaction,but also provide scientific basis for the correct appraisal of hydrogeology condition of Xiluodu power station.
Abstract: To discuss the feasibility of utilizing the radial basis function-artificial neural network (RBF-ANN) model and to predict daily reference evaportranspiration,five different kinds of model inputting factors'composition are made and their correlative influences on the model's forecasting precision are studied.A case of applying the model shows that the precision of forecasting by using the RBF-ANN model is high.
Abstract: A brief review was made on automated extraction of drainage network from grid digital elevation model.The digital elevation drainage network model(DEDNM) was mainly introduced,including principal framework,model structure,and computing procedure. And the DEDNM was applied to the Shiguanhe catchment with the 5 930km2 of area, the intensified observation field for thd HUBEX/GAME.The result shown that the drainage system generated by the DEDNM is acceptable as compared with that on 1:100000 topography map, providing a solid foundation for further development of distributed hydrological model.
Abstract: Based on the characteristics of Yanghe resrtvoir,this paper presents a real-time optimal flood dispatching model with a fuzzy constraint condition,a new algorithm of discrete differential dynamic programming with changable penalty term and a new mothed calculating the flood storage capacity.some rules are given for the real-time flood controlling of reservoir.The results of case study show that the mathematical models and solution techniques are feasible and available.
Abstract: In this paper,The characteristics of flood events series have been analyzed by using fractal theory,it is shown that the flood events have the character of self-similarity,and is a fractal.Further,a case study on the seasonal flood periods classification at the station of Xiao Deshi in Ya Long river is given,the results show that the periods determined by using fractal theory are consistent with that from traditional method.In comparison with traditional method,the new method is much more objective.
Abstract: A new technique, wavelet transform, is introduced to analyze hydrological time series. By using discrete wavelet transform, we evaluated the information cost function (ICF), and compared the three indexes: uniformity coeffecient, information cost function, and fractal dimension. The results show that the three indexes demonstrate the fluctuation in hydrological process from different points of view, and when measuring the fluctuation we should select an index in according with demand.
Abstract: The genetic algorithms are known to be efficient for global optimizing. They are, however, prone to premature convergence and not well suited to perform finely tuned local searches. This paper suggests combining a genetic based algorithm with a simple heuristic local tuning method to improve the efficiency of optimization. The case study shows that the procedure is efficient, robust and practical.
Abstract: The effects of the chamber volume,the air statement index in chamber,the resistance in pipe network,and the field comprehensive resistance on the characteristic values in pressure regulation process are analyzed systematically in this pater.The results show that the chamber volume,the air statement index in chamber effect obviously the pressuer change period and have little effects on the pressure change range, the resistance in pipe network effects markedly both the pressure change period and pressure change range;the field comprehensive resistance effects the pressure change process,with a minimum change period existed.
Abstract: In view of heavy losses and harms in economy, environment and ecology etc. caused by the no-flow in the lower reaches of Yellow River, this paper thinks that the no-flow is not only a simple phenomenon of water resources shortage or distributive nonuniformity in water basin system, but also a serious disaster. It is an important content of harnessing Yellow River to control the disaster of no-flow. In this paper the disaster characteristics and basic law of no-flow in the lower reaches of Yellow River are analysed emphatically, the present situation of research is discussed, and the problems to be researched are pointed out in the future.
Abstract: Based on the statistical analysis of 448 times rainstorm in 13 medium and small watersheds on the Loess plateau, the nonuniformity of spatial distributions of different patterns of rainstorm in this area were systematically studied, inculding deviation coefficient of areal rainfall of watershed, non-unifom coefficient of rainfall, raito of maximum point and minimum piont rainfall, relationship betwwen point rainfall and areal rainfall, and spatial correlation characteristics of rainfall amount,ect.
Abstract: In this paper, the data of flood alarm of Yellow River in Qing dynasty, the drought and flood distribution of China in recent 500 years, etc. are used to estimate the series of natural annual runoffs from 1470 to 1918 for Sanmenxia gauge station of Yellow Rivers, which consists of a series of 520 years natural annual runoffs with the 71 years observed data from 1919 to 1989 of Shanxian (Sanmenxia) gauge station.
Abstract: Based on reviewing the history and development of Gausu's hydrologic network, the hydrologic network in Taohe River and main river of Longnan Jialingjing River are studied by using the line principle and region principle, obtaining beneficial results to practice. Some suggestions about hydrologic network development, how to plan and regulate the hydrologic network and benefit reasonable development and ultilization of water resources, are proposed.
Abstract: It is of great significance to quantify water exchange through interface between groundwater, soil moisture or atmospheric water. An overview of advances in water exchange research through interfaces is presented in this paper from three aspects, according to starting point and emphasis of these researches. The summary shows that much development in small scale measurement has been acquired, but most methods have not been solved heterogeneous problem and regional problem successfully. Of all research methods, remote sensing, numerical method and combination method appear to be most promising.
Abstract: With the increase of population and fast development of economy, the shortage of water resources has become increasingly serious. In this paper, the water demand of China by the mid 21th century has been forecasted based on the macroeconomic model of sectoral water demand projection.The shortage of water resources will still baffle the social economical development of China and the contradiction between water supply and water demand may deteriorate in a considerable long time period in the 21th century.The water shortage peak is predicted to emerge around 2030.The gap between water supply and water demand is hopeful to be slowed down after 2030 and the relative balance between total water supply and total water resources demand will be reached in the mid 21th century.
Abstract: Basing on the implication study of water resources, water resources value and shadow price, this paper thinks the realization of water resources value depends on its sustainable usage. According to its utilization forms,water resources can be classified into natural water resources, engineering water resources and regeneration water resources.Different kinds of water resources have different implications and their price components.The evaluation of water resources value should be based on its shadow price.