Analysis of Karst Rocky Desertification Actuality and Sensitivity in Nanchuan of Chongqing Based on RS and GIS
LI Ying-gang et al (School of Geography Sciences,Southwest University,Chongqing 400715)
Nanchuan of Chongqing is one of rocky desertification areas in southwest China.Under the support of RS and GIS,the present situations and control factors of rocky desertification in Nanchuan were analyzed by using TM remote sensing image data in 2004.The results showed that the karst area in Nanchuan was 973 km2,total land area of rocky desertification reached 224.39 km2.The land area of slight rocky desertification,medium rocky desertification and strong rocky desertification was 100.29,119.47 and 4.62 km2 respectively.The land area of potential rocky desertification was 293.97 km2,which occupied 30.21% of total karst area.By using the spatial analysis functions of GIS,the rocky desertification actuality map in Nanchuan was overlapped with DEM map,slope gradient map,lithology map and land use map.It was found that the rocky desertification was mainly distributed at the elevation of 600-800 m and 800-1 200 m.The main slope gradient was in the range of 15°-25°.The stratum mainly consisted of pure limestone,limestone and dolomite.The rocky desertification of dry land was serious.In the premise of not considering the human factors,elevation,slope gradient,vegetation coverage,stratum lithology and so on were taken as the evaluation factors.The geometric mean method was used in the uniform spatial framework.Through spatial operation and attribute item consolidation,the sensitivity of rocky desertification was classified into five grades,including non-sensitivity,low sensitivity,moderate sensitivity,high sensitivity and extremely high sensitivity.The sensitivity evaluation model of rocky desertification disasters based on GIS was set up.The rocky desertification risk classification and rocky desertification spatial overlapping analysis showed that the selected evaluation indices and classification were reasonable.The rocky desertification risk zoning was realized through the model.It was found that the total area of sensitivity area was 507.20 km2,which occupied 52.13% of total area of karst region.The research provided the important decision-making basis for the prevention and ecological environmental protection of rocky desertification disasters in this area.
【Fund】： 973计划前期研究专项(2008CB417208);; 国家自然科学基金(40672165)资助
【CateGory Index】： X171
【CateGory Index】： X171