Abstract:

A realistic distributed biosphere hydrological model (DBHM) has been developed for representing the role of both topography and land cover characteristics in hydrological cycle. The model is designed for use in large river basin and coupling with atmospheric models. The vegetation phenology is described by satellite data and the transfer of energy, mass and momentum between the atmosphere and the vegetated surface is calculated by a realistic land surface model SiB2. The hydrological part estimates the surface runoff and calculates the interlayer exchanges within the soil profile and interaction between soil water and groundwater. The geomorphologic properties are abstracted from Digital Elevation Model using a distributed hydrological sub-model. Realistic watershed map and river way map are used to delineate sub-river basins and river network. The sub-river basins are coded following a natural numbering scheme which is self-replicating and is possible to provide identification numbers to the level of the smallest sub-basins. The river network routing order of the sub-basins is implicated in the numbering scheme. The runoff is then accumulated and routed to outlet using kinematic wave approach. The model was applied to the Yellow River Basin to investigate its applicability to a region with large variations in climate and land cover. The hydrological simulations has implemented by hourly time step from 1981 to 2000 with a drainage area of 794,712 km². Basic data representing topography, land cover, soil type were prepared in 10 km mesh grids. The simulated hydrographs at 9 gauges were compared with the river discharge observations for evaluation of the model performance.

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