BAISN FACYORS OF THE IMPACT OF FOREST ON RIVER RUNOFF
森林影响河川径流的流域因素

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.