川西北土地沙化区生态环境质量遥感动态监测

为了分析防沙治沙工程的实施对区域生态环境质量的影响,以川西北沙化土地为研究对象,选取沙化土地治理前(2004年)和治理后(2014年)的Landsat影像,基于ENVI平台,从绿度、湿度、干度、热度4方面分别提取归一化植被指数(NDVI)、湿度指数(WET)、建筑物—裸土指数(NDBSI)和地表温度(LST),并对这4个指数进行主成分分析,选择信息量较多的主成分贡献率为权重,建立遥感生态指数(RSEI)评价模型,对研究区的生态环境质量进行了评价。结果表明:2004—2014年,研究区的RSEI均值由-0.059 8下降为-0.068 6,降幅为14.72%,生态环境质量总体下降; 较2004年,2014年优和良等级比例分别增加0.70%和1.77%,增加区域位于川西北防沙治沙工程的实施区; 10年间共有1.25%的区域生态得到改善,1.96%的区域生态发生了退化,生态环境改善区域主要分布于石渠县的防沙治沙工程实施区。因此,川西北防沙治沙工程的实施对改善区域生态环境质量起到了重要的作用。

Remote Sensing Dynamic Monitoring of Ecological Environment Quality in the Sandy Land of Northwest Sichuan

This study aimed to monitor and evaluate the changes of eco-environment quality before and after the control of sandy land in northwest Sichuan, and analysis the impact of the sand prevention and control project on the the regional eco-environment quality. The study took the sandy land in northwest Sichuan as the study area and selected Landsat images before 2004 and after 2014 of the control of sandy land. Based on the ENVI platform, from the aspects of greenness, humidity,dryness and heat, the normalized vegetation index(NDVI), wet index(WET),land surface temperature(LST),and normalized difference building-soil index(NDBSI)were extracted. Principal component analysis on these four indexes, selected the principal component contribution rate with more information as the weighted factor and established RSEI evaluation model was performed to evaluate the eco-environment quality of the studied area. The results showed that, from 2004 to 2014, the mean value of RSEI of the study area decreased from -0.059 8 to -0.068 6, a decrease of 14.72%, and the overall eco-environment quality decreased; compared with 2004, the proportion of high and good grades increased by 0.70% and 1.77%, respectively in 2014, the increasing area was located in the place where desertification prevention and control project in northwest Sichuan was implemented; within 10 years, 1.25% of the region had its eco-environmental quality improved, and 1.96% of the region experienced ecological degradation; the area that achieved improvement was mainly located in Shiqu County's sand prevention and control project site. The implementation of the sand prevention and control project in northwest Sichuan had played an important role in improving the regional eco-environment quality.