内蒙西部古居延—黑城地区历史时期环境的变化与沙漠化过程

沙漠系指第四纪时期由于自然因素所形成, 而沙漠化乃是在具有沙漠化发生潜在自然因素的基础上, 于历史时期内由于人为活动破坏脆弱生态平衡, 使原非沙漠的地区出现了类似沙漠景观的环境变化。换言之, 也就是人为活动对干旱及半干旱生态系统的过度干予所造成不平衡的环境退化, 生产力下降的一种方式。因此研究干旱及半干旱地区历史时期沙漠化过程、发展和演变趋势, 对于合理开发利用自然资源有着重要的意义。

The Environmental Chges and Desertification processes in Historical Period in the Areas of Ancient Juyan-Heicheng Region in Western Inner Mongolia

The ancient Juyan-Heicheng region is located at the lower reach of Ruo Shui River in western Inner Mongolia, and was a reclaimed area in Han, Western Xia(1032-1227A.D.) and Yuan Dynasties and now has alredy been desertified. According to the aerophoto analysis, the region at that time was a lower reach delta of Ruo Shui River with a fan shaped water system,which flowed eastward to the ancient Juyan Lake, The preserved farmlands, irrigational channels, residential centres, beacon towers etr. reflect that the farming areas had a considerable scale in the region during that period. With reference to the ages of unearthed artifacts and old buildings, the reclaimed areas in the region in Han Dynasty occupied the lower and middle parts of the delta; the reclaimed areas in the region in Western Xia and Yuan Dynasties occupied the upper and middle delta besides the old part of the reclaimed areas in Han Dynasty in the middle part of the delta. Heicheng, a main town in Western Xia and Yuan Dynasties was situated on north bank of east tributary of Donghe River in the middle and upper delta. The abandonment of Heicheng and the nearby reclaimed areas was related to wars at the end of Yuan Dynasty and the early of Ming Dynasty, to the destruction of water conservancy projects and to the cut-off of water sources. In Ming Dynasty, the areas in Hexi Corridor within the Great Wall was once again reclaimed on a large scale, the misuse of water resources in the upper and middle reaches also affected the water sources in the lower reach. Therefore, Heicheng has not been rejected since its abandonment.