基于GIS的三江源区冻融侵蚀评价与分析

Research of freeze-thaw erosion in the Three-River-Source area based on GIS

三江源区由于其高海拔、高纬度和低气温的气候特点而成为冻融侵蚀较严重的区域,因此开展其冻融侵蚀强度的研究对区域合理的生态环境规划和生态环境保护方案制定具有积极作用。该文采用归一化方法和冻融评价模型,利用影响冻融侵蚀的主要因子气温年较差、降水量、坡度、植被盖度和太阳辐射进行定量研究与分析,结果表明:三江源区冻融侵蚀区分布面积较广,占源区总面积的75.7%,其中长江源区的冻融区面积比最大,其次是澜沧江源区和黄河源区。3个流域的冻融侵蚀均以中度侵蚀为主,但它们在侵蚀强度等级构成和不同强度等级所占比例均存在显著差异,总体而言长江流域的冻融侵蚀相对最严重。相同强度冻融侵蚀区在空间上积聚,不同强度冻融侵蚀空间分异明显,呈现出由东向西的低-高-低-高侵蚀的带状分布特征。尽管该区域内存在多个高值和低值区交叉分布的现象,但它们的主要影响因素存在一定的差异,其中西部地区以植被覆盖和太阳辐射为主,而东部地区以降水、坡度和太阳辐射为主。

The Three-River-Source area is an area of serious freeze-thaw erosion with high altitude, latitude and low temperature, so it plays a positive role on putting forward some suitable ecological environment plans and protection measures to carry out research of freeze-thaw erosion. Using normalization method and evaluation model, this paper takes annual temperature range, precipitation, slope, vegetation coverage and solar radiation as indexes to evaluate freeze-thaw erosion intensity. The results show that： （1） Freeze-thaw erosion is widely distributed in this area, accounting for 75.7% of total area and the largest one is Yangtze River; （2） Though the three areas are most covered by moderate erosion, they are different in proportion of five classes in each basin and in proportion of five classes in three basins, and in general Yangtze River is the most serious area; （3） The spatial distribution seems to change from low to high alternatively as zonal distribution, but the determinant factor is different in the east and west. The west zone is influenced by vegetation coverage and solar radiation, the east zone is influenced by precipitation, slope and solar radiation, and the middle of this area is influenced by all those factors.