Artificial and Natural Oasis Mutual Converting Process and the Proper Ration in the Typical Basin of Arid Land——Taking the Kaidu-Kongque River Basin as an Example
Based on the Landsat TM/ETM remote sensing image of Kaidu-kongque-river basin,by using RS/GIS technology,this paper extracts the land use/cover type information of 1990,2000 and 2010,analyzes the changing rule and the area ratio of the artificial and the natural oasis in Kaidu-kongque-river Basin,and discusses the suitable area ratio of the artificial and natural oasis.The results show that:①The artificial oasis was expanding,natural oasis area was shrinking in Kaidu-kongque-river basin from 1990 to 2010.The artificial oasis area increased by 2 895.1 km2 in 1990-2010,the expansion speed was 144.8 km2/a,the natural oasis area decreased by 1 946.4 km2,and the decreasing rate was 97.32 km2/a.② In the process of artificial oasis expansion,land using types in artificial oasis also changed greatly from 1990 to 2010;artificial reservoir area was growing fastest,with an average annual growing rate of 15.86% from 1990 to 2010.Orchard area was growing fastest and with the annual growth of 37.1% from 2000 to 2010.③The artificial oasis area in Kaidu-kongque-river Basin took on an increasing trend and the natural oasis area took on a declining trend in recent 20 years,the ratio of artificial oasis area and natural oasis area were 2 ∶ 8,3 ∶ 7 and 4 ∶ 6 respectively.