水土流失是我国重大生态环境问题。全国现有土壤侵蚀面积357万km2,占国土面积的37.2%;全国分布有八大水土流失类型区,年均土壤侵蚀总量45.2亿t,约占全球土壤侵蚀总量的1/5。由此导致的土地退化、河流浑淤和生态恶化,严重威胁国家粮食安全、防洪安全和生态安全,限制了山丘区人民群众脱贫致 Soil and water loss is a major ecological and environmental issue in our country. There are currently 3.57 million km2 of soil erosion in the country, accounting for 37.2% of the total land area. There are eight major types of soil erosion in the country, with an average annual soil erosion of 4.52 billion tons, accounting for about 1/5 of the total soil erosion in the world. The consequent land degradation, river silting and ecological deterioration have posed a serious threat to the national food security, flood control and ecological security, and have limited the people in the hills and areas from getting rid of poverty.