陕北黄土高原的土壤侵蚀与综合治理

The Soil Erosion in the North of Shaanxi Province of the LoessPlateau and Its Synthetizing Harness

陕北的榆林和延安两地区２５个县（市），面积８００９１．８８ｋｍ２。水土流失强烈为最突出的特征。土壤侵蚀的特点是：（１）现代侵蚀是古代多期侵蚀轮回基础上的继承和叠加。（２）水土流失面积大，侵蚀产沙强度高。水土流失面积占７６％，年输沙量６．９６亿ｔ，平均侵蚀产沙模数为９３７０ｔ／（ｋｍ２·ａ），沟谷密度大，平均密度３．０６ｋｍ／ｋｍ２。沟谷面积占４５％～５５％。（３）侵蚀类型、方式和强度垂直分布和水平地带分异规律明显。（４）侵蚀强度与生态环境因素密切相关。（５）工矿城镇建设直接增加水土流失的现象加剧，必须采取综合措施治理水土流失。

There is about 80 091.88 km2 including 25 counties (cities) in the Yulin and Yanan regions of the north of Shaanxi province of the loess plateau. Exceptionally severe soil erosion is the most outstanding character in the area. And its features are as follows: (1)Based on several circles of ancientry erosion in geology history, the erosion of modern times is succeeded and more quickly developed. (2) The area of soil loss is very big accounting for 76% of total land, intensity of river sediment from erosion is very high with annual transport sediment 6.96108 t in average. Erosion modulus by the data of hydrology station of river is about 9 370 t/km2a. The channels or vales average density is 3.06 km/km2 with 45%55% of total area. (3) It is the very distinct for distributing law of type, manner and intensity of soil erosion in vertically along the altitude and horizontally on the latitude. (4)The close correlation between the erosion and the factors of the ecological environment. (5) The soil loss becomes more severe because of building roads and factories, exploit coal mine and so on. In order to developing the economic and rising the living standards of the people , we have to take the synthetizing measures for controlling soil loss.