黄土高原典型植被覆盖下SPAC系统水量平衡模拟

Water Balance Simulation in SPAC Systems of Slope Lands Covered with Typical Vegetations on Loess Plateau

应用土壤-水-大气-植物整合模型(SWAP),在野外观测试验基础上对坡耕地(豆地)、长芒草地和苜蓿草地土壤-植被-大气系统中的水循环进行了数值模拟。结果表明,土壤水分和储水量模拟结果与实测值具有很好的一致性;长芒草地水分收支基本平衡,苜蓿草地的水分支出是坡耕地(豆地)的1.38倍,其中苜蓿的蒸腾耗水量是坡耕地(豆地)的3.88倍,这是引起苜蓿草地群落过度消耗土壤储水而呈现负补偿的主要原因。农地退耕还林还草后会增加SPAC系统水分支出,如果植被群落耗水过大很可能使土壤干化。

A numerical model,soil-water-atmosphere-plant model（SWAP）,was applied to simulate dynamics of soil moisture and soil-water balance in three kinds of land use patterns,including cropland with mung bean,Stipa bungeana grassland and alfalfa grassland,based on field observations.The predicted values of soil moisture and soil water storage had obviously consistent with the measured values.The water input on Stipa bungeana grassland was roughly equal to the output.The water output on alfalfa grassland was 1.38 times of that on cropland,and the evapotranspiration of alfalfa was 3.88 times of that on cropland with mung bean,which was the main reason causing soil water deficit on alfalfa grassland.So conversion of farmland to forest and grassland regeneration will increase the output of water in the SPAC system,if there is a great deal of water consumption by vegetation community,it will lead to soil desiccation.