北方农牧交错带风水蚀复合区水土流失现状与综合治理对策

Current status and comprehensive control strategies of soil erosion for wind-water complex erosion region in the Northern agro-pasture zigzag zone of China

风水蚀复合区是中国北方农牧交错带的一部分。区域的东面与南面毗邻水蚀地貌形态,东南界为沙漠化土地发生、发展的东南界;区域的西面与北面与风蚀地貌形态接壤,西北界为旱作农业的西北界。复合区包括74个县(旗),面积42.77万km2,总人口2400万(2004年)。主要生态问题为:沙漠化持续发展,沙尘暴频发;土地退化严重,承载力急剧下降;生态环境恶化,自然灾害频繁。复合区水土流失的主要特点表现为风水蚀在时间上交错,空间上叠加。受侵蚀营力系统与环境系统的制约,水土流失类型表现出明显的地域分异规律。2000年水土流失面积26万1517.35 km2,占全区土地面积的61.14%;复合区每年流失土壤11.97亿t,其中水力侵蚀量5.55亿t,风力侵蚀量6.42亿t。近20多年来,复合区大部分地区的水土流失面积有所减少,侵蚀强度有所降低。随着国家加大生态建设的力度,预计在未来的十到几十年,复合区的水土流失态势将呈现逐步逆转的趋势,但局部的水土流失状况依然很严峻。风水蚀复合区水土流失治理要以预防为主、保护领先为原则,生物措施、农业技术与工程措施相结合综合治理,把国家的生态需求与农户的经济需求相结合,依法协调经济开发与环境保护的关系,注重科学研究,提高科技含量。根据风水蚀复合区现状,提出了一些治理工程项目,主要包括复合区黄河粗泥沙综合治理工程和生态修复工程。这些工程的实施,将大大减少进入黄河的粗泥沙量,风水蚀复合区水土流失状况可以得到改善。

As a part of Northern agro-pasture zigzag zone, wind-water complex erosion region located mainly in south edge on Inner Mongolia plateau and the area along the line of Great Wall, the boundaries of east and south part is the south-east end of land desertification, and that of west and north is north-west end of dry farmland. It involves 6 provinces and 74 counties that total area is 42.77 × 10^4 km^2 and total population is 2.4 × 10^7（in 2004） and average density of population per krn2 is 57. There are some ecological problems in this region including desertification developing continuously and dust frequently, bearing capacity of land resources decreasing sharply, and eco-environment worsening obviously and natural calamity appearing frequently. The characteristic of soil erosion is that the action of wind erosion and water erosion alternates in temporal and overlaps in spatial. The wind-water complex erosion region can be divided into three sub region according the characteristics of soil erosion and ratio between two erosional agents： 1 ） wind-water well-matched region; 2） wind erosion predominating region; 3） water erosion predominating region. Being controlled by erosional agent systems and environmental systems, the erosion types in wind-water complex erosion region have clear spatial-temporal variation features. The wind erosion part is mainly in three sandy lands-Mowusu, Hunshandake, and Kerqin, The water erosion part is mainly in neighboring area of Shanxi-Shaanxi-Inner Mongolia and north the foot of Yanshan Mountain. The area of soil erosion in 2000 is 261 517.35 km^2 which accounts for 61.14% of total land area. The amount of soil loss is 11.97× l0s t, among which 5.55 × 10^8 t is eroded by water and 6.42 ~ l0s t is eroded by wind. In the past 20 years, the area of soil erosion in most parts of the region is decreased for great scale projects of soil and water conservation, but the area of soil erosion in some parts is still increasing. With enhancing eco-environment construction extent, by estimating, in future decades, the soil erosion situation will tend to reversion gradually; but the condition of soil erosion in part area will be still very serious. The comprehensive combating countermeasures in wind-water complex erosion region include carrying out the policy of putting prevention first and giving priority to protection ing biological-agriculture technology with engineering; combining state ; comprehensive combating by combinecological demand with farmer＇s economic needs; harmonizing economic development with environment protection in accordance with law; empha- sizing technology research and improvement of technology content. On the basis of present situation of soil erosion in wind-water complex erosion region, two key projects bring forward in this paper which includes： 1 ） comprehensive control of coarse sediment area of Yellow River Basin; 2） ecological restoration and regenera-tion. With putting in practice, the coarse sediment transported into Yellow River will be greatly reduced and soil erosion condition will be improved in the wind-water complex erosion region.