【作者】 但尚铭； 何飞； 但玻； 任国业； 石承苍；

【Author】 DAN Shang-ming1,HE Fei2,DAN Bo3,REN Guo-ye4,SHI Cheng-cang4 1.Sichuan Province Agrimeteorological Center, Chengdu 610072, P.R.China; 2.Chengdu University of Information Technology, Chengdu 610225, P.R.China; 3.Sichuan Provincial Meteorological Observatory, Chengdu 610072, P.R.China 4.Institute of Remote Sensing Application,Sichuan Academy Agricultural Sciences, Chengdu 610066,China;

【机构】 四川省农业气象中心； 成都信息工程学院； 四川省气象台； 四川省农业科学院遥感应用研究所；

【摘要】 文章利用1989、1994、2000和2005年的4期Landsat/TM,ETM+遥感影像,在几何校正、辐射定标、大气校正的基础上计算了归一化植被指数(NDVI),建立最小二乘法线性回归方程对多时相NDVI进行同化处理,基于二分模型提取植被覆盖度并转换成荒漠化指数(DI),对理塘县城附近约103.1km2范围的分类研究结果表明:(1)分为无沙化、轻度、中度、重度和严重沙化5级,其中2005年中度、重度和严重沙化面积分别为2.562km2、2.925km2和1.576km2;中度沙化比1989年减少9.69%,重度和严重沙化分别增多35.79%和161.8%;(2)2005年中度以上沙化面积比1989年增加1.470km2,增加了26.3%,年增加率为1.47%;(3)沙化面积均呈前期小、中期大幅增加、后期增加减缓的总体趋势;(4)降水量和风速因子的变化趋势有利于缓解沙化,气温变化趋势没有反映出对沙化的促进作用。人类活动是造成沙化趋于恶化的主要因素;(5)沙化增加趋势与同类研究结果一致。更多还原

【Abstract】 Using the four remote sensing images of Landsat/TM and ETM+ in 1989,1994,2000 and 2005, the normalized difference vegetation index (NDVI) is calculated on the basis of the geometry correction, radiometric calibration and atmosphere correction, and the assimilation of the NDVI images made establishing the least squares equation of linear regression, and to extract the vegetation coverage from the NDVI and converted into the desertification index (DI) Based on the binary model, the classifiable research is made about 103.1km 2 near the Litang county town. The result demonstrates that, (1) the extent of desertification is divided into five levels,such as, non-desertification, mild-desertification, moderate-desertification, severe-desertification and serious desertification. The area of moderate-desertification, severe-desertification and serious-desertification were respectively 2.562 km 2 , 2.925 km 2 and 1.576 km 2 in 2005; moderate-desertification decreased by 9.69% than that in 1989, severe-desertification increased by 35.79%, and serious-desertification increased by 161.8%. (2) the area of moderate-desertification and above levels increased 1.470 km 2 than in 1989, it increased by 26.3%, the annual increased rate was 1.47%. (3) the main tendency of desertification area shows that it gets small increase in the early stage, substantial increase in the medium term and it increases slowly in the latter stage. (4) precipitation and the variation of wind speed are beneficial to desertification easing, but the trend of temperature changing does not reflect the promotion to the desertification. Moreover, human activity is the main factor which makes the trend of desertification turn worse. (5) the increasing trend of desertification is consistent with the results of similar studies.更多还原