分析了黄土高原沟壑区森林小流域和自然草地小流域的水文效应,并利用实测资料和模型计算结果比较了两流域的水循环特点,结果发现在郁闭度相同的情况下,森林小流域较自然草地小流域有较小的径流量、较大的蒸散量和较低的３ｍ土层平均含水量,也就是说森林的覆盖增强了水分小循环,削弱了水文大循环,并导致土壤含水量降低。同时也发现森林的上述水文效应仅当其郁闭度达到一定程度时才能表现出来。通过比较两类生态系统植物生长的土壤水分环境条件和水分利用率,认为黄土高原沟壑区在大力发展林业时应以沟谷为主

In order to investigate the hydrological behaviors of forest and grassland watersheds,a comparative analysis of water balance elements on two experimental watersheds in the gully region of the Loess Plateau was made.The quantitative results of the model applied and observed data confirm that the depth of annual runoff in the forest watershed is less than that of the adjacent grassland on condition that cover degree of both is the same,the amount of evaportanspiration in forest watershed is higher than that of the grassland,and soil water storage in the three meter horizon is less than that of grassland.So we consider that forest cover strengthens the processes of water vertical circulation,and weakens that of the hydrological cycle,and reduces soil water content.A practical suggestion about forest development in this region is also given in this paper.