中国水土流失及其对旱涝灾害的影响

人口膨胀对土地的压力增长，导致水土流失面积扩大，土壤侵蚀量增多，目前我国水蚀面积已达１７９万平方公里，每年流失土壤５０亿吨。水土流失减薄土层，阻碍植被恢复，大大降低土地的蓄水库容，造成水文干旱和农业干旱；同时，河床淤积使河流泄洪能力降低，洪水水位抬高，加剧洪涝灾害的发展，在同样降雨情况下，洪涝灾情比以往增加１倍。对水土流失采取综合治理可有效地减轻水旱灾害。江西兴国通过十年的综合治理，使兴国县水旱灾害频率下降４８．８％，成灾面积减少５０．７％。

SOIL AND WATER LOSSES AND ITS EFFECTS ON DROUGHTS AND FLOODS IN CHINA

In this paper the implication of soil and water loss disasters was described. The soil and water loss disasters are divided into two types:chronic disaster and acute disaster.There is interrelations between the chronic and acute disasters.If chronic disaster is not to be controlled in time,it will be lead to the occurrence of acute disaster.This artical alos expounds the current situation and characteristics of soil and water loss disasters in China. Because of destruction of forest,thinning the soil layer,resulting river sedimentation and deterioration of ecological enevironment,the water storage capacity on earth surface is decreasing and the amount of runoffis increasing.Consequently,in several eroded areas,not only the intensity of runoff is increased but also runoff begins sooner ,which aggravate the potential of flooding,waterlogging and drought.