Hydrological Simulation by the use of an Atmosphere-Vegetation Interaction Model (AVIM)
Hao Zhenchun (1), Su Fenge (1)
(1) Hohai University
The land surface scheme AVIM (Atmosphere-Vegetation Interaction Model) is developed by
Ji (1989,1995). The characteristic of AVIM is to couple the physical transfer and the physiological growth processes at land surface. The scheme is usually optimized and verified with regard to energy budgets, thermal and moisture states of canopy and soil, leaf area index and CO2 flux. But the treatment of hydrological processes in AVIM is too rough, and runoff is simply an excess of precipitation over evapotranspiration.
In this paper, the parameterization of runoff generation in AVIM is improved. Three kinds of runoff production mechanism are involved in the water balance model of AVIM, including saturation excess, infiltration excess, and snow melt. Green-Ampt method is adopted to partition precipitation into components of infiltration and surface runoff. Xin'anjiang model is used to describe the runoff generation from saturation excess. Snow accumulation and ablation model is based on the degree-day method. Snowmelt is assumed to be linearly related to the difference between the air temperature and a base temperature , normally 0. Based on the concept of Hillslope hydrology, total runoff is divided into three components, namely, surface runoff, subsurface runoff, and groundwater runoff. They are routed to the outlet of river basin separately by the use of Linear Reservoir and Muskingum method.
The soil column is divided into three soil layers. Each model grid cell is assigned a surface cover type and soil properties. Evapotranspiration from wet canopy, vegetation, and bare soil is modeled by using aerodynamic formulations. The variation of unsaturated soil wetness obeys one dimension Darcy's law.
In order to evaluate the surface water budgets of AVIM and to evaluate the ability to simulate runoff, the implementation of AVIM to Xilinhaote drainage basin (in Mongolia) and daily discharge simulations from the year 1991 to 1993 are presented.
Submittal Information
Name :
Date :
Ms Su Fenge
31-May-01-14:48:13
Organization :
Theme :
Water Resources Development & Utilization Lab., Hohai University
