陕南山区侵蚀环境与水土流失特征

<正> 陕西省的南部山区,北靠秦岭,南临巴山,汉江、丹江、嘉陵江从境内流过,区内辖汉中、安康、商洛三个地区及宝鸡市的太白、凤县,共30个县(市)。秦岭山脉是黄河、长江流域和我国地理分带的天然分界,所以陕南山区的水土流失也表现出独有的特征。

Erosion Environment in the Mountainous Area in Southern Shaanxi and the Characteristics of Soil Loss

Bashan and Qinling mountainous area in southern Shaanxi, has a land area of 70000 km2. and is featured with high mountains and steep slopes, large gully density, large river (or gully) bed slope, high rainfall and thin topsoil layer. Annual, sediment load transporting into the Yangtze River amounts to 82 million tons, among which the ratio of sediment in suspension to the bed load is 1:1. 3 to 1:1. 7. Enormous amount of the bed load leads to aggradation of rivers that are suspended over the adjacent land, causing serious flood hazards. Gravitation erosion such as landsliding, slumping and collapsing has a broad distribution, resulting in more frequent clami-ties. The topsoil layer in southern Shaanxi is generally 30-40 cm in thickness, so soil is valuable and should be strictly protected.