Abstract: Based on XBT temperature data during 1955-1999 in the tropical Pacific,the regularity of the warm anomalous signals of the sub-surface ocean temperature in the warm pool region that play important role to the El Nino event occurred in the western Pacific has been analyzed and discussed.The formating mechanism of sub-surface ocean temperature anomaly in the warm pool region in the western Pacific has been announced. The analysis indicates that the relationship between the sub-surface anomalous warming in the western Pacific warm pool and the temperature anomalies in the northern equatorial current(10°N)is close.In the earlier stage of the El Nino event,the anomalous warm water located in the equator central and eastern Pacific subducts toward the warm pool region of the western Pacific along thermocline of the northern equatorial current.Then piles up in the warm pool region and expands toward the equator western Pacific thoroughly.The eastward transport of warm water to the equator central and eastern Pacific will float to the sea surface along the sloping thermocline under the forcing of atmosphere.When anomalous warm wat er achieves a certain strength,it finally leads to the eruption of El Nino event.The westward transport of anoma lous temperature in the northern equatorial current is right the important factor to trigger the sub surface tem perature anomalies in the warm pool region in the western Pacific.So it leads to the key interpreting that El Nino event occurs.
Abstract: Based on the date from some weather and hydrometric stations,the corresponding relationship between El Nino,the air temperature,the precipitation and the runoff in the Qilian mountain is analyzed. The result shows that the effects of El Nino are different in the different time and zones.That is,when El Nino occurs,the air temperature rises,but the precipitation and the runoff decrease in the whole mountain area,especially in the east and middle parts.In the next year when El Nino occurs,however,though the air temperature rises,the precipitation and the runoff in the east and middle part of the Qilian mountain region don't decrease as much as in the year when El Nino occurs,and there is no obvious correlativity between El Nino,the temperature,the precipitation and the runoff in the west part of Qilian mountain region.
Abstract: The image processing technique was applied to measure velocity fluctuations of suspended parti cles in open channel flows. Two kinds of spherical particles were studied:plastic particles(d=0.1~1.5 mm)and glass particles(d=0.1~0.3 mm)Experimental results reveal that:(1)coarse particles pos sess greater velocity fluctuations than fine particles in the near bed region,while the scenario is completely opposite in the upper flow;(2)the velocity fluctuation of fine particles is a function of y/h,and for coarse particles,the velocity fluctuat ions relate not only to y/h but also to the shear stress;and(3)the plastic particles have greater velocity fluctuations than glass particles of the same size.
Abstract: The laboratory calibration were used to determine the relationship between backscattered signal strength and sediment concentration.A non-intrusively way of concentration measurement was introduced, and the inner fluctuation of concentration was analyzed rudimentarily.Finally,according to the fluctuation concentration acquired by MicroADV,the equilibrium of upward flux and downward flux were compared quantificationaly.
Abstract: The relationships between hydraulic property parameters(flow regime,flow velocity,mean depth and friction factor)and discharge,slope gradient were simulated in a hydraulic flume(5 m×0.4 m×0.4 m). The unit discharge varied from 0.625×10-3/(s·m) to 12.5×10-3m3/(s·m),and the slope gradients varied from 5° to 25°. The results indicated that there is deeply relationship between the flow regime and the flow depth. The flow mean velocity,depth and the Darcy-Weisbach friction factor(f)are mainly controlled by the discharge,and can be well simulated by a simple power function of unit discharge and slope gradient. The determination coefficient are 0.98,0.97 and 0.95 respectively1 When the slope gradient is cancelled,the determination coefficients only decrease 7%,16% and 3%. When the Reynolds number increases,the Darcy 2Weisbach friction factor decreases as fine power function1 The influence of slope gradient on f depends on the discharge.
Abstract: The stageⅠregulation work of deep water channel of the Yangtze River estuary and the topographic change of the lower-section of the Jiuduan Sandbank(JS)after regulation are simply described. The non-linear three2dimensional numerical model under the σcoordinate system is applied,which is verified by the field observations. According to the measured topographic change of the lower-section of the JS after and before the stageⅠregulation work(from May 1997 to March 2000),the tidal flow discharge,the Euler's residual flow and the current velocity characteristics in the middle and lower sections of the North Channel are simulated by using the model in order to interpret the hydrodynamic mechanics of sediment movement and topographic change.
Abstract: A test method of unsaturated seepage flow of single fracture is presented and an experimental equipment for testing the relationship of capilary pressure,saturat ion and unsaturated permeability of fracture is developed. In order to examine the reliability of experimental provision and the validity of experimental principle,and to expound the mechanisms of unsaturated seepage flow in fracture,a simplified fracture model with flight aperture is developed and an experiment of unsaturated seepage flow in this fracture model is done Mechanisms of unsaturated seepage flow in fracture are expounded initially.At the same time,the experimental results show that the experimental provision and the experimental principle in this paper are reasonable and reliable.
Abstract: The macro-hydraulic conductivity,macro-soil water characteristics,and macro-dispersivity are determined from the statistic parameters of the unsaturated soil water hydraulic conductivity obtained from the field experiment,which are the key parameters for analyzing soil water flow and solute transport in the large scale.
Abstract: Parameter estimation is the key job of mathematics simulation and calculation,and its most complex problem is the simulation of water movement and contamination transferring in unsaturated soil. On the basis of analyzing movement and transference,the hydrodynamic functions of piecewise-continuous which is suitable for coordinate grid is adopted,and a contamination distributing equation about soluting concentrations in the liquid,solid,and gaseous phases in variably saturated soil is established. The inverse problem mode is adopted to discuss the optimization estimation technique of the model parameters. The Levenberg-Marguardt modification of the Gauss-Newton minimization algorithm is used to calculate iterative problem of the model parameters. The experiment model parameters of one-dimensional soil column and two-dimensional large tilting soil tank are estimated by the method,and the effect of the given parameter and estimation amount on parameter's confidence intervals and forecast result are discussed. The identified and analyzed results shows that the parameter estimation technique is feasible and the forecast result is dependable. The parameter estimation technique is used to simulate the transferring and transforming of pollutants in unsaturated soil.
Abstract: This paper studies the distributing characteristics and the controlling factors of ground temperature,geothermal gradient and surface geothermal current value by using the data of 28 geothermal wells in the Kaifeng geothermal field.Dividing the reservoir(depth 300~1 600 m)into 6 sub-reservoirs,the hydraulic-connection among sub-reservoir is researched also.The hydro-geological characteristics and hydrochemical characteristics of 6 sub reservoirs are assessed.The age,the circulating rate and the recharge area of geothermal groundwater are determined based on the radioactive isotope 14C content.
Abstract: Taking the Streeter-Phelps model for example,this paper primarily studies the water environmental risk considering the factor of stochastic vibration,and reveals that the stochastic force maybe have great effect on water environmental risk,which provides theoret ical basis for risk assessment and management.
Abstract: The effect of NH4+-N removal in a polluted raw water of water sources by the bioremediation process with the elastic fillings and micropore aerators was studied in this paper.The effect of waterbody temperature on the NH4+-N removal in the polluted water sources was also discussed. The results show that the waterbody temperature is an important factor effecting the bioremediation process. The temperature has the biggest effect on the removal of NH4+-N for the bioremediation process under low waterbody temperature. The temperature has a smaller effect on the removal of NH4+-N for the bioremediation process under higher waterbody temperature.
Abstract: The stable isotope hydrological processes in Naqu River basin,middle of the Tibetan Plateau, was studied based on the observations of δ18O in both river water and precipitation during the summer in 1998. The fluctuation amplitude of δ18O is much smaller in river water than in precipitation. The variation of δ18O in river water is a combined effect of δ18O in river water,precipitation amount and surface evaporation. The study also found the obvious impact of lake water on stable isotope homogeneity in river water. The difference between the weighted δ18O in river water and lake water reflects the strong soil surface and lake surface evaporation in the research basin.
Abstract: By studying on determining the quality factors of the sulfide standard curve and on the pretreament methods for different water samples,the conclusions are obtained that the standard liquid of sulfide has to be prepared for using immediately,and the direct determination method,the extract filter determination method and the acidization-air injection determination method should be used separately for samples with different pollution degree.
Abstract: The lower Yellow River reach from Huayuankou to Jiahetan is a typical wandering river. The generation of computational mesh,which is used to simulate the flood,is affected by the distribution of water works in the river channel. The spatial information about the two Yellow River banks,the protecting dykes,and these roads that is obviously higher than the ground are need to be used to generate the computational mesh. As a result these dykes and roads must be located in the element interface of the computational mesh. In the model the finite-volume method is used to solve the shallow wave equations and the Osher scheme is used to calculate the flux through the interface between the neighbor element. The flood event with peak discharge of 15 300 m3/s,occurred in the period from July 30 to August 10,1982,is simulated1 The estimated result indicates that the simulation method is good.
Abstract: The paper briefly presents the natural general situation of Ejina oasis,analyzes the variation ten dency of surface water and groundwater lasted 20 years in the lower Heihe River basin,dissects the growth of vegetation,succession of plant species,vegetation degree of coverage,the relationship between Ejina oasis and the depth of local groundwater,forecasts the change of Ejina oasis area in the designed years,and points out that the sustainable development of economy and society and environment construction in Ejina oasis rely on water resources.The core issue of Ejina ecology protection is how to steady the oasis and make it moderate expanding,which has important stratagem significance.
Abstract: The evaluation of water supply is an important component of water resources programming. According to the connotation of water supply evaluation,this paper re-argues the index of water supply in agriculture irrigation,and presents a new evaluation method for water supply by using the crop water production function and the fuzzy method.
Abstract: An experimental work on water depth surveying in the Nantong section of the Yangtze River was carried out by using satellite remote sensing multi-spectral technique. On the basis of the analysis on the mechanism of remote sensing in water depth surveying,a digital model of the water depth surveying in the riverbed of the section was set up by calculating quasi 2synchronous remote sensing spectral data and channel sounding data,and inverted the water depth maps from landsat TM data in 1984,1994 and 1998. The result inverted shows that the landsat TM data have some efficiencies in measuring shallow water depth in such a high sediment discharge riverbed.
Abstract: The safety stockpile of nuclear waste,the forecast and control of groundwater contamination and many other key problems demand to research the groundwater solute transport in the large-scale fractured rock.The scale effect of groundwater solute transfer in fractured rock is a great challenge for the research. The multi-scale conceptual model and its physical and mathematical simulating method of groundwater solute transport in fractured rock are introduced,and the relation of simulating scale and surveying scale,forecasting scale,fractured medium scale and the fractal characteristic of scale dependent are also discussed.
Abstract: The conditional simulation is one part of the interdisciplinary subject-geostatics.The theory can keep spatial correlation of variables as a strict mathematical simulation to reproduce dispersion variance and fluctuation process. It has been drawn great attention in geology,water resources,soil science and environment science etc. After a brief introduction to the theory and methods of conditional simulation,the article reviews the main achievements of its application to water resources system and the development of new methods and techniques at home and abroad in the nineties of the 20th century,and looks into the future of the subject and its technique development.
Abstract: Through comparing the history,present condition of Chinese cities and that of European cities, this paper illustrates that the urban flood mitigation will be a hard long term task in China and Chinese urban flood mitigation strategy will only be the coordinat ion between human activities and flood in the 21th century.
Abstract: Based on the field survey of tubewells in Hebei Province,a stochastic water frontier production model of tubewells is established. The research results show that the ownership,the management mechanisms and the scale are all statistically significant influence factors on tubewell technical efficiency,and the technical efficiency of non-collective ownership is higher than that of collective ownership1 Based on this study,several policy suggestions on efficient and sustainable development of irrigation systems are provided.