STUDY ON PERMAFROST OF QILIAN MOUNTAINS BASED ON GIS SPATIAL ANALYSIS MODEL

Based on those empirical formulas of temperature, permafrost thickness, latitude,longitude and altitude in Qilian Mountains and Tibet Plateau,the distribution characteristics of mean annual temperature,mean annual ground temperature and the thickness of permafrost in Qilian Mountains are obtained by Arc GIS spatial analysis model. The results show the average annual temperature and annual mean ground temperature of the permafrost regions in Qilian Mountains are in the range of- 12 ~- 6 ℃ and- 4 ~- 2 ℃ correspondingly,and the thickness of permafrost varies from 90 to 140 meters. The area with elevation above 4300 m around Hala Lake has the lowest temperature and the thickest permafrost. Its average annual temperature and ground temperature are lower than- 10 ℃ and- 4 ℃ respectively,and permafrost is thicker than 140 m.Combined with the distribution of hydrocarbon source rock and the permafrost thickness of gas hydrate drilling in Qilian Mountains,the middle of Qilian basin-mountain tectonic zone is believed to be the most favorable area for the gas hydrate reservoir.