Abstract: This article expounds the connotation of the base system of water and discusses the existence and evolvement of the system. It also models the base system of water by the mathematical method. On the basis of these,the atributes of stability, concordance and the rate of evolvement are applied to analyze and estimate the system. The strategy of the application of the system is discussed and the prospect of its application is also described.
Abstract: Numerical simulation is a primary method for studying the flow and transport in porous media.It is rather important to specify the exact value of parameters,which can represent the real hydraulic feature during the numerical simulation of groundwater.As the porous media is a complex system,particularly when the studyied area is large-scale,the spatial variability of hydraulic parameters is especially significant.The traditional deterministic model has certain limitation in considering the spatial variability.This study performs the numerical simulation via the Monte Carlo method,which can take such spatial variability into account to study how the spatial variability effects the numerical simulation.The monte Carlo simulation of flow and transport is used to compare with the deterministic model in three-dimensional heterogeneous media.And a series of comparisons,such as the difference in hydraulic head,velocity and tracer concentration,show that the Monte Carlo simulation is more effective because it has a higher resolution and a good explanation to the simulation error and the source of such error.
Abstract: The governing equation of water-air phase flow is the best one,and established by the two fluid volume-averaged momentum and continuity equations based on seepage mechanics and the optimization theory of parameter inversion.The constitutive relationships of permeability-saturation-pressure controlling multiphase flow is given.The optimal estimation values are obtained by adopting the constrained variable metric method to inverse the parameters.The results show that the optimized values by the numerical method in this paper is in good agreement with the experimental data,and the comparison analysis validates the reliability and practicability of the numerical model,which deals with the sensitivity of the values to the initial conditions.The uniqueness and stability analysis indicates that the inverse model is well posed,and that the numerical model provides sufficient information for the successful application of the parameter-estimating approach.The numerical experimental is completed by this method,using the numerous initial values to meet the practical project.It not only supplies the foundations to the numerical calculation of the contaminant transport in unsaturated zone,analyzes well the test data in the process of oil gas reservoir exploitation,the landfill gas release and the contamination remediation of the volatile organic compounds,but also provides the theoretical basis for determining the parameter of the permeability-saturation pressure.
Abstract: The rough set(RS)theory is a new mathematical tool for analyzing the uncertainty and imprecise problems. By using the RS theory in the attribute reduction of the groundwater quality indexes,the significance of the attribute between the groundwater quality indexes and the groundwater quality class,and 2 reducts of the original data are obtained. The discernibility matrix is used to find the reductions. Among the 4 groundwater quality indexes,only 3 indexes are necessary. It is shown that the RS theory is simple,precise and practical for the at ribute reduction of the groundwater quality index through the theo-retical analysis and practical application.
Abstract: In this paper,the theoretical foundation of mode clarification is introduced at first,based on which the analysis is done according to the results got by the Back-Propagation neural(BPN)new training. It is found that the features of the sedi ment capacity ability are similar to the hyper-concentration and lower-concentration flow. So the sediment capacity ability is not a desirable criterion for the classification of hyper concentration and lower-concentration flow. This agrees well with the results got by other researchers. During the BPN training,if,in most cases,the Bingham shear stress of the flow is greater or less than certain critical value,the training results always agree well with the measured data,while others not Several training tests get nearly the same conclusions. It can be deduced that there indeed exists a critical value of the Bingham shear stress, and when the shear stress exceeds this critical value,the flow can be classified as the hyper concentration flow. For the flow with a hyper-concentration powered phenolic,this critical value is about 3.2×10-1Pa.
Abstract: The turbulent structure and the vertical distribution of the velocity of sediment-laden flow would be effected by the sediment condition including sediment particles' diameters and concentration. In this paper,the MicroADV is used to measure the mean velocity distribution of sediment-laden flow. It analyzes the influence of interaction between the sediment particles and flow on the distribution of the velocity of the flow with the different sediment condition and flow intensity. By verifying the application of the existing distribution formula with the experimental data,a new formula of exponential of the velocity distribution is proposed,at the same time,the variational law of coefficient(k)and index(m)in the new formula with the sediment concentration(s),the diameter of particles(d)and the hydraulic condition is analyzed.It is concluded that the k increases with the increasing sediment concentration,the hydraulic condition and the diameter of particles.However,the m decreases with the increasing diameter of particles,and increases with the increasing sediment concentration.
Abstract: Based on the maximum entropy principle,a velocity formula is derived to describe the variation of longitudinal velocity in both the vertical and transverse directions in a open channel with trapezoidal cross-section. The effect on the longitudinal dispersion coefficient of the inhomogeneity in the vertical and transverse directions of the flow is studied.And the conclusions fairly agree with the work of other researchers. A formula for predicting the longitudinal dispersion coefficient in a open channels with trapezoidal cross-section is proposed. According to the formula,the longitudinal dispersion coefficient is determined by two parameters which reflect the inhomogeneity of the velocity distribution and the influence of channel walls. The method on the longitudinal dispersion in this paper is not based on some special experimental results or the field data. Because of the solid theoretical basis,this method can be used as an efficient tool to determine the longitudinal dispersion coefficient in any open channels with trapezoidal cross-section.
Abstract: The first test of water-sediment regulation of the Yellow River was performed from the 9:00 A.M. on July 4 to the 9:00 A.M. on July 15,2002.The second test was conducted from the 9:00 A.M. on Sept.6 to the 6:30 P1M.on Sept118,2003.According to the test results from the Yellow River water-sediment regulation,especially the first test,the paper analyzes the results of the scouring or deposition in the lower river and the area of the river-mouth bar,the adjustment of the channel morphology,the effect of channel regulation and the changes of flowing capacity of the lower reaches.The test results show that the water-sediment regulation can reduce aggradations of the channel,increase its flowing capacity and improve the sediment delivery conditions of the channel in the lower river.Therefore,the water-sediment regulation is one of the effective measures to solve the sedimental problems of the Yellow River.
Abstract: According to the design of digital water resources regulation project,a new auto-adapted method is established to contrive a scheme for the water resource regulation.This method introduces the auto-adapted control theory to the water regulation system and it can update data automatically and reach the object exactly.The targets of the scheme is to protect the system of basin river against dry-ups and ice-run hazard and allocate water very rationally.The method can automatically adjust reser-voir's discharge or water supply plan to reach these targets.By using this method to make the schemes of 2001-2002,the results show that the auto-adapted method can make the schemes exactly and efficiently.
Abstract: The river fractal features can reflect the features of river systems,and the fractal dimension is an important variable that can reflect the fractal features. So there is certain relation between the river fractal dimensions and the river floods. By taking the middle and lower courses of the Yangtze River as an example,this paper calculates its fractal dimensions and analyzes its fractal features by grid-covered analysis,and tries to indicate the relationship between the river fractal dimensions and the river floods through the analysis. The results show that,the higher the river course fractal dimension,the lower the river network fractal dimension,the higher the possibility that flood-happens.
Abstract: How to process depression and flat areas and their drainage direction is a key issue and must be solved prior to the extraction of drainage network based on the digital elevation model(DEM).This paper investigates the shortcomings of the existing methods for the complex terrain DEM with depressions and flat areas,and proposes several new methods,namely,the classification and the merger of depressions,the valid filing depression,the classification of flat areas,and the construction of the drainage direction based on the flow cost for the river valley plains.These methods can be performed in the software system developed by authors. The test shows that the methods mentioned above can be used to process complex depressions validly and construct flat areas water flow direction in the consideration of the ambient terrain and astringency to the potential waterway. And they are proved to be rationa. In addition,by using the methods,odd waterways such as parallel and pseudo ones can't be generated in the extraction of the drainage network. Hence the results obtained are consistent with the real situation.
Abstract: In this articles,the principles of the surface energy balance system(SEBS)and an arithmetic for quantitative survey of surface drought characters based on SEBS using NOAA satellite images and observed weather data were introduced. The application of the arithmetic on drought monitoring at large scale in China was dicussed,including of data processing,model parameters initialization,results evaluation and error analysis.
Abstract: The background of climatic anomalies relating to heavy rainfalls over the middle reaches of the Yangtze River in China are studies in this paper. A t-test for composite signal field is performed. The case studies of heavy rainfall show that the distribution of significant anomaly in the 500 hPa signal field is an important precursory signal of heavy rainfall. The pattern of the signal anomaly with ‘+-+' in the composite signal field in the cases is found. It occurs in the area over eastern part of China.
Abstract: Through the analysis on the relationship and variable tendency between the present population situation,main index of economic development and the amount of water consumption,the quota of water consumption,meanwhile,synthetically con sidering about the variation of influential factor such as water resources condition in future,economic and social development, science and technical progress,the efficiency of water consumption and the level of water conservation,etc,the relationship between the above mentioned synthetical influential factors and the index of water demand amountis established and the variation of growth rate of water demand in future and the variation breadth of other indices such as water consumption per capita and water consumption unit value of output are confirmed Furthermore,the amount of water resources demand in 2030 and 2050 are calculated according to the predicted indices such as population and economic development of the target year.
Abstract: The problem and challenge of the GIS applied in the hydrology are analyzed and discussed. On the basis of the data structure of the Arc hydro,the data organization and implementation of the spatial hydro-data model are discussed and studied with respect to the object-oriented technology. The hydrologic object's spatial locations,feature attribute,temporal attribute and their topological relationships could be well represented in the object-oriented GIS hydro-data model. Finally,the object-oriented GIS hydro-data model is applied to the Qingfengshan Basin. The application result shows that the object-oriented GIS hydro-data model provides a common structure frame for the hydrological spatial data and is helpful to promote the wide application of GIS to the hydrology.
Abstract: The virtual water is the water used in the production process of goods and services.So far as the water resource utilization is concerned,the physical trading actually implies the virtual water trading,hence,the virtual water trading approach can be used to alleviate the water scarcity in arid regions.Based on the input/output method,the consumption of virtual water in Ningxia in 2002 is calculated and analyzed in a systematic way as a prime-case study,which reflects some difficulties and problems that Ningxia will face once the virtual water strategy,the larger dimension allocation to water resource,is implemented.This method breaks away from traditional solutions,which merely focus on the using of the local water resource. Meanwhile,several new suggestions are put forward for saving water resource in arid regions.
Abstract: A new approach to coastal water quality analysis is expected in this paper through the study on the SOM(Self Or ganizing Map).Firstly,the water quality data of Bohai Bay is ready. Then,a set of software for coastal water quality analysis is developed based on the batch version algorism of the SOM and the SOM toolbox in the MATLAB environment. This software can analyze and display the data charact ers through the training of the SOM. Furthermore,the training results can be analyzed so that the data is divided to five different kinds of pollution. Lastly,it is also realized that the monitored data serial can be tracked,and the new data can be classified automatically. Through application it can be found that this study helps to analyze the coastal water quality in depth with several kinds of graphics,which supply the decision support to recognize the pollution status and takeing the corresponding measures.
Abstract: Taking the Wenruitang river system as a case study,a dynamic water quality model for looping river networks is developed based on the framework of uncertainty analysis.The distribution of water quality parameters can be got by the HSY (Hornberger,Spear and Young)algorithm based on the uncertainty analysis,which can improve the credibility of the model simulation and reduce the risk of the decision making.The model consists of two sub-models,i.e,the hydrodynamic and the water-quality models.The hydrodynamic sub-model is based on the Saint Venant equations and the four-step numerical method is applied to their solutions.The water quality sub-model is estabilished from the CSTR concept,yet with essential amend ments in accordance with the requirements of looping river networks. Only ordinary differential equations need to be solved, and the matrix solving can be avoided so that the calculation efficiency is greatly improved,which makes HSY algorithm possible to be used.The model is firstly applied to Lucheng river network,which is the key part of Wenruitang river system in Wenzhou City HSY algorithm is used to calibrate the model parameters,and the parameter's uncertainty is analyzed.The model is verified and the results are relatively ideal Finally,the uncertainty transfered to the simulation results due to the parameter's uncertainty is briefly discussed.
Abstract: Close to the South channel of the Yangtze River estuary,the main channel to transport sediment,the east shore of Nanhui becomes an important position for sediment silting. It has an favorable condition of the shore and sediment supply for reclaiming,and now is a key area in Shanghai reclamation plan. Shanghai has already started a reclamation project on the east shore of Nanhui. The reclamation will move the sea line,which can bring about the change of the hydrodynamic condition. A 2-D tidal flow mathematics model is set up to predict the change and discuss the influence of the project on the water area surrounded.
Abstract: In the past 30 years,water has ceased to flow in the 357 km lower reaches of Tarim River,and water must be de livered there emergently for resuing the environmental condition,which is a rare worldwide case of ecosystem recovery and re-habilitation in the deteriorated river basin.In this context,this article uses a great deal of monitored data from the eco-environmental baseline investigations and the methodologies of the river hydraulics,the groundwater dynamics and the vegetation ecology to analyze the law of water transportation,transformation and consumption along cross the river course and in the vertical profile of the river course,by following the mail line from water consumption along the river course the dynamic changes of groundwater table and the vegetation recovery. It contains scientific analyses of the three dimensional eco environmental responsive effect and vegetation recovery impacts on the emergent water deliveries,thus lays theoretical and practical foundation for creating and perfecting the evaluation system for the supplementary water delivery,the ecological recovery and rehabilitation of the damaged eco-environmental systems in the arid areas,mean while,provides the important technical support for the comprehensive improvement of the Tarim Basin.
Abstract: Based on the monitoring data from Jilin section in Songhua River,the contribution rate of water pollution factors to Jilin section in Songhua River is calculated quantitatively,and all kinds of water environmentally managed areas are divided rationally with the complex model of the principal component-cluster analysis. According to the assessment results,the corresponding measures of water environment management are put forward. The results show that the main pollutions in Jilin section in Songhua River are volatile phenol,Chemical Oxygen Demand(COD)and Ammonia-nitrogen(NH3-N),which have their pollution characteristics of organic Pollution and non-point Source Pollution. The results also show that in the seven selected monitoring sections(i.e.,Fengman,Longtanqiao,Hadawan,Shaokou,Jiuzhan,Anda and Baiqi),the water quality in the sections between Fengman and Longtanqiao,Longtanqiao and Shaokou,Shaokou and Baiqi is lighty,heavily and moderately polluted respectively,which means that the water resources in these sections should be preserved,controlled and exerted respectively. The development of the study has certain reference value to gross control of the regional water environment,and can implement the scientificall classified management of the water areas of Songhua River in Jilin Province.
Abstract: In this paper,a simple discrete vegetation model is used to estimate the change of soil moisture. First,we use an assumption to replace the total volume of the backscattering from vegetation cover.Second,we ignore the double bounce com ponent of the model of its little contribution to the whole backscattering of VV polarization;thirdly,the last term of the model, the backscattering from bare soil,is described as a function of the Fresnel reflectivity and surface roughness functions. After comparing the two repeatedly passed measurements,we get a new algorithm to estimate the relative change of soil moisture. The results show that the algorithm proposed in this paper can be used directly to estimate soil moisture change and magnitudes of the vegetated surface using multi-temporal L-band VV polarization AirSAR data.
Abstract: The assessment of rivers health is the foundation of environmental management and ecosystem monitoring. The river's health status can be determined through a holistic appraisal of rivers and their surrounds. Five components of the rivers health include:water quality,aquatic life,physical form,hydrology and streamside zone. Many methods and criteria are available to assess the status of river ecosystem,and this review focuses on RIVPACS,AUSRIVAS,IBI,RCE,ISC,RHS and RHP,which are classified into the predictive model and the multimetrics. Based on the review of the river assessment in various countries,the future development trends are discussed in this paper. There is great need for our country to design an indicator system for rivers health assessment,which can be used to report on environmental condition of rivers,judge the long-term effectiveness of rivers rehabilitation programme and assist the managers in making decisions about rivers management activities.
Abstract: Whether hydrologic processes are low dimensional chaotic processes is still controversial.After analyzing the litera ture about the research of chaos,we find that there are many problems.For instance,the estimation of the time delay is very subjective and application dependent;in estimation of correlation dimension,many researchers ignore intentionally or carelessly a principle,i. e,there must be a clearly scaling region used for confirming the existence of finite correlation dimension; many researchers still use the original formula of G-P algorithm to calculate the correlation of hydrological time series instead of using the modified formula proposed by Theiler.Therefore,the temporally correlated points in the state space are probably mistaken for a spatial geometry in the state space,and the problem still commonly exits that the size of the studied series by researchers in China is too small.
Abstract: Great attentions have been paid on eco-environmental water requirement in recent years. The paper analyzes and summarizes the current research advance in eco-environment water requirement,including the connotation and extent of the eco-environment water requirement,the evaluation methods of eco-environment water requirement,pointing out some problems,and looking forward to the development trend of the eco-environment water requirement.