Abstract: Histories of Gores in the Qiantang Estuary,are modelled by using a two-dimensional finite-volume,Osher scheme,and a discontinuity-fitting method. The algorithm ensures mass and momentum conservation,and can be applied to cases with irregular morphography,and moving boundaries. Based on a simplification a line-bore,the modelling can be done on a coarse mesh by a microcomputer,After having calibrated against a typical semi-diurnal tide,the model is used to predict the succeeding semi-diurnal tide for validating its reasonability and applicability.
Abstract: A method based on the Schwarz-Christoffcl trans-formation is developed for the solution of velocity at moving interfaces between fresh-and salt-water in aquifers. It involves the following primary steps:(1)Map the given fresh-and salt-water regions of the flow plane Z onto the upper halves of auxiliary planes tf and ts, respectively. (2) Use a mapping between the planestfandl,and the complex potential planes wf and ws to set up equations for the side-length rations of complex potential polygons,containing some geometric parameters,so that the problem becomes one of solution for the parameters. (3) Set up equations for boundary conditions, including those of fresh-water influx and material interface. (4) Solve the coupled equations for the velocity at interfaces. A main distinction between the method and common numerical methods is direct solution of the velocity without discretizing flow regions, leading to smaller error. An example shows that the method is both feasible and effective.
Abstract: In this paper,a new combinative prediction model for thd time-series which has a periodic feature is proposed. In the model,the real measured series is decomposed into an annual average,an annual amplitude and a remains series. The multi-layer hierarchical models are used to model and predict for the average and the amplitude series because of their time-varying feature, the remains series is modelled with ARMA model. The case study shows that the model has good resuits for the prediciton of groundwater level dynamics.
Abstract: The atmospheric moisture content and water vapour transport flux over the Sanxi Province has been computed,the results show that the seasonal variation of moisture content is more obvious than those of other regions in China and some cyclical processes seem to exist in the secular variation;the annual net-inflow amount of atmospheric moisture in 1990 is about 5350×108 m3 with coming mainly from the west-south boundary and escaping mainly from the east boundary. Based on the computation of atmospheric moisture content,water vapour transport and other hydrologic balance components,a hydrological cycle model of the Sanxi Province has been developed. The model shows some characteristics of hydrological cycle in the Sanxi Province:(1)The use rate of atmospheric moisture is about 30%which is lower than the average use rate of the whole country;(2) The contribution of precipitation formed by local evaporation to the total precipitation is about 15%,showing the hydrologic re-cycle is active,especially more active than those of the area south to Yangtze River Basin;(3) The influence of groundwater minig on hydrologic cycle components has became visible,which may feat to some harmfuleffects for the environment.
Abstract: On the basis of numerous experimental data and practical experiences obtained from extensive evaporation investigation of different types of water regions in China,a formula of evaporation coefficient which could be universally used in China is developed and recommended. The formula,simple in form,not only refleets closely the real picture of the mass transfer at air-water interface,but takes care of the mechanism of free and forced convection in a single expression both in form and function. The new formula has been satisfactorily compared with some well-known relevant formulas and evaporation data measured directly from various water bodies.
Abstract: Regional distributions of the rainstorms and floods caused and effected by tropical cyclones are described and.the geographical divitions of China are also given in this paper. The hydrological characteristics of tropical cyclone rainstorms and floods are discussed and are compared with that of non-tropical cyclones.
Abstract: Rainfall spatial variability is one of the major factors affacting the spatial variation of runoff production in loess regions. Some characteristics of rainfall spatial variability including point-area reduction relationship,frequency and structure are analyzed by using rainfall intensity data of 5,15,30 and 60 minutes durations observed on small catchments with highy dense rain gauge stations and good observation conditions. The internal relationshop between interval intensity and event rainfall are also studied. The results will provide a basis for the modelling of runoff production on small loess catchments.
Abstract: This paper discusses the philosophy basis of fuzzy sets analysis to hydrologic system. The comprehensive methods for determining the membership function of flood period is put forwards by combining hydrologic cause of formation and probability statistics with fuzzy set analysis. In addition, the paper expounds elemental methodology of fuzzy sets analysis to hydrologic system from research on flood period description.
Abstract: In this paper,regional water resources planning is treated as macroeconomic activities. First of all,we introduce a concept of system-macroeconomy-based regional water resources system,on the basis of which a planning system-Multiple-Objective Integrated System(MOIS) is identified. A Macroeconomic Model (MEM)and its submodels act as the core of this system,while a Multiple Objective Analysis (MOA) model takes the position of top model,in which primary relationships in the macroeconomic water resources system are integrated. In addition, forecasting simulation and optimization are also integrated,to make the system a comprehensive tool for regional water resources planning and management.
Abstract: The complexity of the menagement of flood storage and detention basins first is examined in this paper. Next the effects of flood diversion on the land use of flood storage and detention basins are analyzed. Also the factors related to flood damage and the evaluation methods of losses are discussed. Then,a research framework for hazard mitigation is developed with its basic subjects proposed. At last,a case study on land use and hazard mitigation is introduced by applying a probability model,an unsteady flow model and optimization models.
Abstract: The intensifying interactions between water and rock in the environmental water around some dam sites in China are studied in the paper. Case studies show that the behaviour of the environmental water have been altered significantly since the dams were built and the reservoirs were impounded. The changes consist in(1)Weak acidification of the water on the bottom of reservoirs;(2) Alkalizationor acidification of the ground water under dam foundations;(3)Discharge of eluates occurring at or near the top of some drainage holes drilled into dam foundation; (4)Dissolutio n of curtains;C5)Growth of local uplift pressure values beyond design ones;etc. All these would have important influcence on dam safety,and therefore should attract enough attention.
Abstract: In this paper,the approaches and methods for determining directly or indirectly parameters of hydrologic models are investigated by using remote sensing images. Based on the parameters extracted from Landsat TM images,the daily monthly and annual runoffs in the Caoe River Basin were simulated through the Sacramento hydrological model with considerable accuracy. Thus,this technique provides a potential way for dynamic simulation and monitoring of hydrological processes in the area without observed hydrologic data.
Abstract: In view of the features of torrential rains,an extended forecast of them is of urgent necessity for the flood-protection and construction of the Main Dam on the Three Gorges of the Yangtze River. Hence,studies are concentrated first on the heavy rains that may cause flash-floods,in which a new concept and its mathe-matical expression of "Flood-Causing Torrential Rain" (FCTR)is proposed. Through a series of combination of meteorological and hydrological studies including:climatological and atmospheric synoptic patterns of FCTR,satellite cloud systerns and OLR features,extra-long and long wave fluctuations,low frequencies of atmospheric oscillations,medium-range atmo-physical parameter diagnoses,and relationships between intense rainfall process and flash-flooding,etc,some extended FCTR forecast methods have been established and used experimentally.