陕北神木地区沙漠化动态演化分析

Dynamic evolution analysis of the sandy desertification in the Shenmu area, North Shaanxi, China

通过神木地区的1∶5万生态地质填图,以实际调查为基础,结合20世纪80年代、2000年等不同时期的航空、航天信息资料和历史文字、图形、图表等对神木地区沙质荒漠化(简称沙漠化)的特点、影响因素、动态演化趋势进行了分析,认为地质因素是沙漠化的内因,是沙漠化的物质基础,气候和人类经济活动是沙漠化的外因,影响着神木地区沙漠化的进程与速度。以地质因子调查为基础,以卫星遥感技术为手段,初步查明了沙漠化的物质来源、分布特点,并建立了神木地区沙漠化动态分析模型;分别编制了20世纪80年代及2000年两个时段的沙漠分布图,总结了20年间神木地区沙漠化发展趋势,将该地区沙漠化演化类型划分为逆转型、扩大型、活化型和无明显变化型。神木地区以逆转型为主导,表现在流动沙丘及半固定沙丘的面积逐步减少,而固定沙丘的范围在快速扩大,其变化速率分别为-5.725、-9.603和16.218km2/a。对神木地区今后沙漠化演化趋势进行了预测分析,并根据研究区的实际情况提出了沙漠化的防治措施。

On the basis of 1∶50000 geological surveying and mapping, combined with the information from aero photos and space images in the 1980s and in 2000 and some historic records including some diagrams and graphs, this paper analyses the features, influential factors and dynamic tendency of sandy desertification in the Shenmu area and indicates that the geological factors are the immanent causes and material base of the sandy desertification; The climate and anthropic activities are the extrinsic factors affecting the course and speed of sandy desertification in the Shenmu area. By means of satellite remote sensing and geological surveying, this paper discusses on the material source and distribution features of the sandy desertification, establishes a dynamic analysis model for the sandy desertification in the Shenmu area, compiles the distribution maps of desertification in the 1980s and in 2000, and summarizes the development tendency of sandy desertification of the Shenmu area in 20 years, and divides the sandy desertification in this area into reversion-type, expansion-type, activation-type and unobvious change-type. In this area, the reversion-type is the dominant one. It shows that the areas of active sand dunes and semi-fixed dunes are lessening step by step with the speed of-5.725 km2/a,-9.603 km2/a, respectivel, while the areas of fixed dunes are extending rapidly with the speed of 16.218 km2/a. Finally, this paper analyses and forecasts the development tendency of the sandy desertification in the Shenmu area in the future, and puts forward some preventive and controlling measures against sandy desertification.