Study On Theory And Method Of DHM

Distributed Hydrological Model (DHM) is widely studied at present especially in the domain of Climate Change, Land Use/Cover Change, Predictions in Ungauged Basins, et al. Almost all kinds of DHMs have been analyzed from the view of foundation, structure, preferences, cell set, program and datum command. A project about netlike conflux model with rainfall-runoff model in its meshes was emerged from the analyses. Main work and methods were programmed.A new rainfall-runoff model with mixed mechanism of saturated-excess and infiltration-excess was founded. A conceptual saturated-excess model is run in skin-deep soil with alterable thickness at the beginning of each time slice, go with an increasing-step difference mathematic model of the vertical soil water movement to bring influence from the lower zone moisture and ground water. The model simulates the moving of soil water even in non-rain time and can responses to the change of ground water. Time of each calculate step is limited to several hours.A physically mode simulating the heat transmission in soil was found witch has same spatio-temporal structure as that of soil water model. By it the precision of evaporation calculation can be improved a bit. An equation is recommended to describe whole day's temperature to surface temperature. Simulation shows temperature of soil under -5cm of surface is steadier than surface and the former is more useful in the description of frozen earth.The amount of evaporation adjusted by the influence of land cover and soil water can be reaved from the kin-deep soil, of cause a relevant change should be simulated in the mathematic model of the vertical soil water movement. Study shows, evaporation of each cell where slope steeper than 5‰ or latitude over 45° in the distributed model should be modified by grid's grade and slope direction according to solar radiation. Modified equation of each cell is served. Fact data of evaporation-infiltration from Wudaogou plot are employed to verify the unit model's mechanism, and a well score was gotten.The moving of surface water is traced and simplified followed special measure to deal with the error from simplification. A conceptual grid-to-grid conflux model of surface water was found, it can bring a distributed outputs used in future's multi-ply validation. The new rainfall-runoff model and conflux model can be used in the simulation of flux and an example in Dongwan region is served.Method of downscaling daily precipitation to each hour was simply studied and one suit of parameters is enough in both flood simulation and daily flux calculation. In order to deal with bigger spatial scale, 2 parameter are set to adjust the soil and plat type, and water capacity curve from Xin'anjiang model are employed. Method of changing average soil water content into distributed points' value was founded, it can improve the score of flux simulation according to Dongwan region's examples.A summarize of the main methods and fruits of this paper is given, shortcoming of these work and task in future's study are listed.