黄土高原坡耕地苜蓿产量及水土流失地形分异模拟——以延安燕沟流域为例

Topographic Differentiation Simulation of Alfalfa Yield and Soil and Water Loss in the Loess Plateau

退耕还林还草是目前黄土高原整治生态环境和控制水土流失的主体政策。为使生态退耕政策得到有效落实,本文基于WIN-YIELD软件,以延安燕沟流域为例,利用2006年延安站的逐日气象数据和燕沟流域地貌、土壤及土地利用等资料,模拟分析了不同地形高程、坡度和坡向条件下坡耕地种植苜蓿的秸秆干物质产量、水土流失量及其地形分异特征。结果表明:在黄土高原,地形坡度是影响苜蓿秸秆干物质产量和泥沙流失的重要因素,苜蓿秸秆产量模拟值随地形坡度的增大而减小,泥沙流失的模拟值随地形坡度的增大而增大;地形高程1000 m以下的地域种植苜蓿其产量明显高于1000 m以上的地域,坡耕地苜蓿产生径流和泥沙随地形高程的变化不显著;地形坡向对苜蓿秸秆产量和水土流失量的影响不大。

De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss in the Loess Plateau.This paper,taking the Yangou Basin as a case study and using the day-by-day meteorological data from Yan’an station in 2006,simulated and analyzed the quantitative relation between alfalfa straw yield,soil and water loss and topographic condition with the aid of WIN-YIELD software.The results show that： a） Topographic gradient has important influences on straw yield and sediment loss in the Loess Plateau.The bigger the gradient is,the lower the straw yield and the more sediment loss will be.b） The straw yield,when the alfalfa is planted below an elevation of 1000 m,is sig-nificantly higher than that over 1000 m.Changes of soil and water losses with topographic height on slope farm-land are not significant.c） Topographic slope aspect has little effect on the straw yield and soil and water loss.