Abstract: As a matter of fact,a river is an open system,not an isolated system or a closed one.In this paper,the changes of the entropy,the entropy production and the rate of energy dissipation in river adjustment are analyzed by using the principle of classical thermodynamics and non-equilibrium thermodynamics.It is shown that the entropy is different from the entropy production,the minimum entropy production is equivalent to the minimum rate of energy dissipation,and an alluvial river can adjust itself in accordance with the theory of minimum entropy production or the theory of minimum rate of energy dissipation rather than the principle of maximum entropy.
Abstract: The key to study turbulence problems in reality by using numerical simulation is to take into account discrepancy of the Reynolds Stress.A 3-D anisotropic algebraic stress model (ASM) is established successfully to simulate turbulence driven secondary flow in natural channel.Comparison between the calculated results and experienced results in rectangular ducts has certified the high accuracy of the numerical model.Combining the ASM with unstructured meshes results in more reasonable out come than ever before for open channels with complicate sandpit The ASM is a powerful tool to study stability and deformation of riverbeds.The analyzes show that not only the streamwise flow scours the upstream edge of the sandpit but also the sec ondary current erodes transversal part of the cross section.However,studies in its turbulence characteristic indicate that a sandpit has severe effect on riverbed stability.
Abstract: The erosion processes of 10 kinds of soil were studied with the experimental erosion slots and 2 artificial rainfalls with an interval of 11 hours.As a result,rill erosion has been observed in most soils during the second event of rainfall.The observations about runoff and sediment suggest that sediment concentration and runoff rate of all the soils with rill erosion decrease in the first rainfall,and increase then decrease in the second rainfall.The results of physical and chemical analysis and the multi-factor regression show that soil texture,content of soil organic matter,ferrous and aluminous compounds have an unnoticeable effect on rill erosion,while indexes of soil structure concerning soil aggregates have a close correlation with the rill erosion,the velocity and grosses of runoff and sediment.The degree of aggregate despersibility and the ratio of collapsing rate to infiltration rate work well in predicting possibility of rill erosion and the sediment discharge as well.
Abstract: Combined with the runoff scouring method and the rare earth element (REE) technology,the temporal and spatial variation laws of the sediment yield on slope are studied in this paper.The results show that the process of sediment yield on slope can be divided into the following three stages,interrill erosion stage,intensive rill erosion stage and rill erosion declining stage.The results indicated that the ratio of the amount of sediment yield in the various period to the amount of total sediment yield augments at the beginning and decreases at last during the runoff scouring experiment under the different flow discharge and the different slope gradients Under the same flow discharge,the maximum value of the ratio shows a tendency of appearing in advance with the slope gradient increasing.The intensive rill erosion stage accounts for the main sediment yield,which contribute 52%~75% to the total sediment yield in the whole experiment.The relative erosion mass of the different section a long the slope decreases at first and increases at last during the runoff scouring experiment Experiment on the steeper slope with smaller flow discharge indicates that the relative erosion mass of the different section along the slope is similar to that on the gentle slope.When the flow discharges is larger,the relative erosion mass decreases with the length of slope increasing.The temporal variation of sediment yield on slope is that the relative erosion mass at the bottom section of the slope decreases with experimental time length of the experiment,while the relative erosion mass on other section increases fluctuantly.
Abstract: Spatial distribution of runoff and sediment in the vertical belt sections of soil erosion chain is studied by the simulated rainfall examination on block diagram combined with multi-slope sections.The results show that the runoff increase from the upper slope to lower one.The runoff per unit area and the unit time increases in order of the upper hillslope,the middle hillslope,the lower hillslope and the gully slope.Also,different the erosion patterns develop well on the hillslope with rainfall intensity of 90.2 mm/h and rill erosion extends from bottom of the slope to the middle and the upper hillslopes.Rill erosion,in contrast,only occurs in the lower hillslope and gully slope with rainfall intensity of 60.5mm/h,and gully erosion do not develop with rainfall intensity of 29.7mm/h.Due to the effect of runoff from the upper slope,sediment yields of hillslope and gully slope have increased by 20.2%～63.5% and 42.9%～74.5% respectively.
Abstract: Effect of the erosion control measures on the sediment delivery ratio is studied,based on the data from the Wuding River,a major sediment-supplying tributary of the middle Yellow River.The erosion control measures have greatly changed sediment erosion,transportation and deposition processes in the drainage basin,and thereby the previously established sediment budget has also been modified.In natural conditions without human disturbance,the sediment delivery ratio over the Wuding River basin approaches 1.0.However,when the sediment delivery ratio has rapidly declined to 0.4～0.3 due to the large-scale erosion control measures having been taken since the 1960s.The dramatic change of sediment delivery ratio is caused by the formation of artificial sediment sinks,i.e.,sediment-trapping check-dams and reservoirs.Large quantities of sediment has been trapped by them,only to decrease the sediment ratio.At present,the effect of the sediment interception of these artificial sinks is 2.4～6.3 times as high as that of the sediment reduction with the slope measures such as land terracing and tree-and grass-planting.This indicates that these direct erosion-reduction measures should be strengthened in the middle Yellow River basin.
Abstract: Based on uncertainty of the parameteric information about current velocity,the pollutant comprehensive attenuation coefficient,and so on,an unascertained mathematics model for river water quality simulation and prediction is put forward according to the unascertained mathematics theory.The established model can provide not only the pollutant concentration but also the corresponding reliability,it present more useful and scientific pollutant concentration information for water contamination controll plan and water environmental management.The result shows that it is feasible and reliable to simulate and predict river water quality.
Abstract: In the paper,the water conflict in transboundary regions of Guanting reservoir watershed is studied.The conflict model is obtained by using the conflict analysis techniques of Fraser and Hipel,in which thore are three sides concerned,the central,the upstream and the downsteam government Out of 18 possible out comes,the partly cooperative outcome and the fully cooperative one are optimized by analyzing the preferences of each side and the stability of their outcome.And the fully coop erative out come will be most likdy to occur,which shows that with coordination of the central government using the stimulus and strategy,the cooperation between the upstream and downstream government can improve the status of water resource,i.e,the upstream to reduce pollutant completely and the downstream to give financial support.
Abstract: During the propagating processes of the level and uniform velocity landslide bore,a shock wave is formed when the landslide object is advancing at the uniform velocity.When it stops advancing,a rarefaction is formed between the landslide object and the shock wave Then the interaction will occur when the raretact ion cat ches up with the shock wave.The article provides a quantitative research on the reflection shock wave and the incidence shock wave generatd by the interaction.Based on the track equations of the incidence shock wave,some quantitative relations between wave heights,wave speeds and others concerned are obtained,and some simple computing methods are presented to solve them.
Abstract: Based on the Cauchy-Helmholtz theorem and the Smagorinsky model,a second-order dynamic sub-grid-scale (SGS) model with two dynamic coefficents is proposed,in which the sub-grid scale stress is the function of both strain-rate tensor and rotation-rate tensor.The velocity and pressure fields are calculated by using the simplec algorithm and the finite difference approximation to discretice the governing equations.Compatison between computational and experimental results of velovity and pressure fields in a curving conduit is conducted.The computarional results are in good agreement with the experimental ones.
Abstract: The relationship between the indexes of ENSO during 1951-2001 in the tropical Pacific and the Antarctic sea ice extents during 1973-1998 are analysed,and the relationship between the sea surface temperature in the Southern Ocean and in the Pacific during 1950-2001 and the Antarctic sea ice extents are studied.The result shows that the variations of the Antarctic sea ice extents especially in the Southeast Antarctica is closely related to the ENSO erents.This telecorrelation shows that the circulation process of ENSO is closely associated not only with ai-r sea interact ion in the tropical. Ocean but also with the variation of the Antarctic sea ice extent.If the extent of sea ice in Southeast Antarctic anomalous increases or decreases,after lagging a year's,the indexes of El Nino and La Nina will become weaker and stronger accordingly,however the indexes of Southern Oscillation will become stranger or weaker accordingly.Such correlation machanism is achieved by the ocean circulation that transports the anomalous sea temperature from south to north.The anomalous variation of the Antarctic sea ice extent has an influence on the warmer and cooler structure of Antarctic Circumpolar Current and on the longitudinal transportation of anomalous warmer and cooler water,which leads to the anomalous variation of upper ocean in the tropical and subtropical Pacific,playing an important promotive role in the happening of El Nino or La Nina.
Abstract: Based on the in situ investigation data obtained during the period from June in 2001 to May in 2002 in Tianmuhu Lake,the paper analyzes the vertical and spatial distribution and yearly and daily variations of water temperature,and reveals the distribution and variation of thermocline and the relationship between water temperature and dissolved oxygen and nutrient.The results suggest that the hourly maximum temperature of surface water of Tianmuhu Lake occurs between 14:00 and 19:00 and the hourly minimum temperature of surface water occurs between 0:00 and 8:00.The yearly variation of water temperature is summer > spring,autumn > winter and with a maximum value in July or August and a minimum value in January or February.There exits obvious temperature difference between surface and deep layer water in spring,summer and autumn.Thermocline turns up from March to October,and strongthens from March to May,then weakens from September to October.The variation of water temperature has an obvious effect on the values of dissolved oxygen and the concentration of nutrient.When the thermocline is found in the lake,the value of dissolved oxygen on surface is less than that of the deep layer.However,when the thermocline disappears,the difference between surface and deep layer is minor.Moreover,the thermocline prevents the nutrient exchange between the surface and the deep layer water.
Abstract: Only statistical flood information is employed in the traditional control of the limited elevation of a reservoir in the flood season.In this case,the reservoir is controlled at a relatively low elevation in order to prevent from its design flood every moment during the whole flood season.In this way,many reservoirs,especially in northern part of China,have to spill lot of surplus water when floods occur,while there is little inflow to those reservoirs after the flood season when they are allowed to store water to a relatively high elevation.In order to use more flood resources,a new idea and its syntheric inference models are proposed in this paper to control the limited elevation of a reservoir dynamically during the flood season according to rainfall-runoff and shortterm (24-h) rainfall forecast in the reservoir basin.At the present developmental level of rainfall-runoff and short-term rainfall forecast,it is possible to predict what floods will occur in the next few days.Furthermore,the limited elevation of the reservoir is dynamically controlled by means of a set of synthetic inference model.At the same time,when the design flood happens,we must have compensation measures to ensure the reservoir's safety in case of forecast errors.
Abstract: The assessment index system and standards of water resources renewability are established from a quantitative viewpoint.By using the projection pursuit,the genetic algorithm,the reverse S-shape curve and the assessment stardards of water resource reproducible ability,a new method for comprehensive evaluating water resource reproducibe ability,the genetic projection pursuit method (GPPM) is established,for which detailed steps are given,it is used to assess the water resources reproducible ability of the 9 administrative divisions along the Yellow River.The result shows that the water resources reproducible ability of the Yellow River is rather low.But the GPPM has visual,effective and well adaptative features,where the evaluation results are given with real number.It is a superior evaluation method to various water resource comprehensive evaluation problems.
Abstract: In this paper,based on the risk analysis theory,a risk assessment model for agricultural drought is developed,which includes the occurrence probability of drought,capacity of drought prevention,percentage of planting area,etc.The relative yield is introduced as the agricultural drought index reflecting the impaction of water transport in the SPAC system on the yield.By means of the index and the model,the agricultural drought risk of irrigation area is evaluated,which analyses the living phase of crops with the highest influence on risk degree of crops and the crop of the most risk degree.The results would greatly benefit to establish reasonable scheme of drought prevention and alleviate the disaster loss.
Abstract: The symmetry of the 1-D Boussinseq equation for transient phreatic flows is discussed in this paper.And its analytical solution under such conditions as initial and boundary conditions is obtained by the method of the Lie group transformation.The errors between the non-linear Boussinesq equation and that of its linearization are compared.Based on the analytical solution,a new method for null error linearization of the Boussinesq equation is proposed,and some principles in the linearization are analyzed.
Abstract: Based on the field data from the three plots of one hectare in Quzhou County on North China Plain,water drainage and nitrate leaching are calculated with a soil water balance model (SWB) and the dynamic process model (DPM).Quantities of water drainage and nitrate leaching calculated by the SWB method range from 191～202 mm and 38～63 kg·N/hm2 in 1998/1999 respectively.When the DPM method is used,they range from 168～234 mm and 27～53 kg·N/hm2 respectively.The cause for the difference is that the upword and unsaturated water flow is taken into account by the DPM method,but not by the SWB method.The DPM method needs lot of field data,mainly to study nitrogen cycle in field,assess water and nitrogen usage efficiency and optimize management soil water and nitrogen fertilizer.But the SWB needs few field data to calculate the quantities of water drainage and nitrate leaching.The SWB is a good method for management soil water and nitrogen fertilizer in fields without high precision.
Abstract: Numerical simulation of groundwater flow in the semiarid and semi humid climate of the Nebraska Sand Hills was made using the MODFLOW and the water balance model in the unsaturated zone.Analysis of groundwater recharge and dis charge and water balance in the aquifer reveal influences of unique topography of the sand dunes and soil property on ground water recharge and discharge.The simulation results demonstrate that the large infiltration rate of the sand soil results in much precipitation recharging into the aquifer,and thick unsaturated zone reduces groundwater evaporation losses.Therefore,sufficient groundwater could be stored in the thick aquifer,which maintains a steady streamflow and supplies numerous lakes and wet lands.This study is beneficial for groundwater resources evaluation and water resources protection in the environmentally vulnerable area of our country.
Abstract: Estimating solute transport parameters with boundary layer method is a reliable and simple method,but how to determine the position of the boundary layer is the key factor to limit its the application.Because the boundary layer of the brilliant blue dye in soil is very clear and easy to be determined,the feasibility of indicating the boundary layer of Cl- using the brilliant blue dye is studied in this paper.The results show that the transport law of the brilliant blue dye is similar to that of the Cl-.The relationship between the boundary layers of the Cl- and the brilliant blue dye can be described by the linear-equation under the condition of the relatively small value of dispersivity.Furthermore,the relationship between the boundary layers of the Cl- and the brilliant blue in sand soil and light loam soil could be derived,which will provide an idea to use the brilliant blue dye to indicate the boundary layers of the non-reactive solutes.
Abstract: The particle image velocimetry (PIV) is an effective and non-intrusive technique to measure the planar distribution of velocity in the fluid based on the cross-correlation of flow images.In general,cross-correlation analysis in the PIV can be implemented quickly by the fast Fourier transform,and the efficiency can be improved by considering the property of real Fourier transform.Furthermore,the higher efficiency can be obtained by using the Hartley transform of separable kernels.Three algorithms are specified in detail in the paper,and the comparison of the three algorithms is conducted in the theory and computation time in practice,which can show the advantages of the Hartley transform.
Abstract: The RNG κ-ε turbulent model with wall-function law is firstly applied to simulate the flow of the reversible two-way passages pumping station.The incompressible N-S equations are solved by the finite volume method with a staggered grid in a non-orthogonal curvilinear system.The optimum function of outlet passage is proposed,and the numerical loss of head is given.A good agreement is achieved between prediction data with experience data.The RNG κ-ε turbulent model with wall-function law can be used to simulate flow field and loss of head in the passages of the pumping station.
Abstract: Since the moral hazard,the adverse selection and the credit hazard problems and so on,exist in traditional (re) insurance,it is difficult to disperse the flood hazard effectively Therefore,it is necessary to find an effectual financial tool to transfer the flood hazard to the capital market.On the basis of building the concept system of flood insurance bond,this article expatiates the differences between the general bond and traditional reinsurance bond.From the view of economics and actuarial science the price mechanism is delineated by analyzing flood insurance bond.By studying the operating mode of flood insurance bond,this article expounds the developmental perspective of flood insurance bond in China and points out that flood insurance bond provide us a new financial tool to control and reduce flood disasters.
Abstract: This paper introduces the present state of flood insurance in some countries,and applies the economics,the insur ance theory,the system engineering to the analysis and study of flood insurance,which reveals the inherent property and law of flood insurance,and establishes the utility model of flood insurance.Some advices are proposed to implement flood insurance thoroughly according to our situation.
Abstract: Reasonable water resources allocation is one of the effective control measures in the sustainable water resources utilization.This article divides the current research on reasonable water resource allocation into two types:a broad and a narrow sense.Research advances in narrow sense reasonable water resource allocation are systematically summarized in three aspects of internal mechanism,practice process and evaluation.This article points out main problems in current water resource allocation processes in China,including the shortage of the effective initial water rights allocation systems,the reasonable and effective compensation mechanism,the broad social involvement and the post-effect evaluation systems.Therefore it is hard to achieve full reasonable allocation of current water resources.In order to solve those related problems in water resources allocation practice,four important aspects must be focused on water resource allocation in China in future research,i.e.,setting up "natural-artificial" dual knowledge and perception mode from modern river basin water cycling process,setting up water resources reasonable allocation mode based on water cycling,setting up uniformly based rules for water resource allocation,and setting up evaluation standard and systems for the rationality of water resources allocation.
Abstract: This paper reviews the history of flow simulation,points out the key problems about restricting flow simulation development,and proposes that the approach to solve those matters is to intelligentize flow simulation by intercrossing hydraulic science with intelligence science.And this paper presents the theory of flow intelligent model,discusses its construction approaches by means of genetic algorithm,fuzzy logic,cellular automata,chaos theory,artificial neural networks,expert system and data collection,etc,which is important for constructing an excellent flow simulation intelligent system.The Conclusions indicate that intelligentizing of flow simulation becomes a new subject,and the flow intelligent model is a new means to study hydraulic science and has broad prospects.