森林影响河川径流的流域因素

BAISN FACYORS OF THE IMPACT OF FOREST ON RIVER RUNOFF

国内外所进行的小区或小流域试验表明,砍伐森林径流量增加,增加森林植被覆盖则径流量减少。但是,在大流域,砍伐森林并不一定能增加河川径流量。小面积试验得出的结论不适于推而广之到大的流域。其主要原因是流域因素——所处的自然气候地带、地质地貌特别是水文地质条件的不同。大面积种树种草或砍伐森林,对一个较大流域总水量的影响是比较复杂的。在什么样的条件下水量减少、增加或者变化不大,要对整个流域进行详细地调查和观测,只进行简单的小流域试验是不可能得出正确结论的。

About the impact of forest on the river runoff, many experiments in small areas and small river basins have been made at home and abroad. The experimental results show that deforesta-tion makes runoff increase and that, on the contrary, raising forest vegetation ratemakes runoff decrease. However, in large river basins it is not surely the case mentoned above. Therefore, it is not suitable to apply the consequence of the experimnt in small areas to large river basins, In short, the impact of tree planting and grass plating or deforestation on the total amount of water in large basins is rather complicated. In order to know what makes water quantity in a large basin decrease, increase or remain almost unchanged, detailed investigation and observation should be made on the related natural conditions (basin factors) of the basins. Simple expreiments carried out in small areas cannot provide a correct answer.