RS-GIS-Based Investigation And Research Into The Desertification

The Southwest of China is one of the three major centers of karst distribution in the world. The problems of rocky desertification and poverty in karst environment are not only the worldwide basic issues, but also a very important factor in close association with the sustainable development of southwest area. The rocky desert is one of the four primary frail belts of ecological environment ~ Karst, Loess, Desert, Tundra— in the west of China. The vulnerability of karst ecosystem is the foundation of forming rocky desert. While the intensive human activities have largely affected all processes of this event.The present study, supported by the project of China Geological Survey— Remote Sensing Investigation and Monitoring on the Key Karst Mountain Areas in Southwest China, focuses mainly on the Mabiehe catchment. Based on a large numbers of high-resolution remote sensing image and aided by the GIS technique, our effort as the first time, is addressed to characterize the forming mechanism of the rocky desert in Mabiehe drainage basin. It is out hope that our study can provide some scientific basis for a sound management of the weak ecosystem and implementing of desertification mitigation in close relation to the sustainable development of the study area.By combining the environmental condition of rocky mountain area and previous researches within the study area, our investigations focus on: 1) establishment of the database of the distribution of carbonate rocks in study area;2) recognizing of the threshold value of classification accurately according to the analysis of rocky desertification index image in typical areas;3) design of the appropriate method to extract information. 4) transforming the remote sensing image data into geographic map in Geographic Information System (GIS) platform automatically to get the map of rocky desert.According to the map of spatial distribution of rocky desertification, the slope chartderived from DEM data and previous achievements in Mabiehe catchment, this study mainly tried to find out the distribution characteristics of rocky desert with the overlaying analysis and research into the original mechanism of rocky desertification.On the basis of the investigation by remote senseing, the present situation of rocky desert of 2005 in Mabiehe catchment was basically revealed. The total area of rocky desert in the whole investigated region is approximately 1203.35 km2, accounting for 41% of the total investigation area and 54% of the karst mountain area.The lithology was a controlling factor of the rocky desertification. The distribution of lithology affected the distributed rules of rocky desert directly.The slope was another dominant factor which determined the distribution of rocky desert. Based on the spatially analyze and the synthetically study on the distributive map of rocky desert and the map of slope in monitoring area, we found that the change of slope affected the degree of rocky desert's forming. The higher the slope is, the more percentage of the rocky desert occupies within the study region. Slope is of the upmost important driving factor in rocky desertification.