四川省九寨沟县地震前后区域生态环境质量评价

基于地理信息系统和遥感数据处理软件平台,对四川省阿坝藏族羌族自治州九寨沟县在2017年8·8地震前后的生态环境质量进行了监测和分析。利用Landsat 8 OLI卫星传感器所获得的2016年(震前)和2017年(震后)的遥感影像数据,提取归一化植被指数、湿度分量、地表温度、归一化土壤指数分别作为绿度、湿度、热度、干度等4个指标,进行主成分分析得到遥感生态指数。根据该指数,可将九寨沟县生态环境质量状况分为优、良、中等、较差和差级。2016年九寨沟县有24.8%处于生态环境质量状况优,2017年震后则下降到19.84%,2017年生态环境质量状况较差和中等的面积占比呈增加趋势,分别占17.99%和33.93%;震中15.5 km缓冲区内生态环境质量状况优的面积占比下降最多,为5.01%;2017年8·8九寨沟地震对震中15.5 km缓冲区的生态环境质量状况有较明显的影响,县界内的三个自然保护区中九寨沟国家级自然保护区受到冲击最大。本研究可为九寨沟地区生态环境监测、灾害评价和恢复重建提供科学依据。

Evaluation of regional eco-environmental quality before and after earthquake in Jiuzhaigou County,Sichuan Province.

Based on remote sensing data and the geographic information system processing software platform,we analyzed the eco-environmental quality of Aba Tibetan and Qiang Autonomous Prefecture in Sichuan Province before and after the 20178·8 earthquake.We used the Landsat8 OLI satellite sensor to obtain remote sensing image data of December 31,2016(before the earthquake)and December 18,2017(after the earthquake),and extracted the normalized vegetation index,humidity component,surface temperature,and normalized soil index as four indices of green degree,humidity,heat degree and dryness,respectively.We used principal component analysis to obtain the Remote Sensing Ecological Index(RSEI)from these four indices.According to the RSEI,the eco-environmental quality of Jiuzhaigou County was categorized as excellent,good,medium,poor and worse.In 2016,24.8%of Jiuzhaigou County areas were in an excellent eco-environment level,which fell to 19.84%after the earthquake in 2017.In 2017,area proportions of the eco-environment quality at poor and medium levels showed an upward trend,accounting for 17.99%and 33.93%,respectively.The proportion of the area with excellent eco-environment quality in the buffer zone of 15.5 km from the epicenter of the earthquake decreased most,accounting for 5.01%.In summary,the Jiuzhaigou earthquake in 2017 had significant impacts on the eco-environment quality,particularly in the buffer zone of 15.5 km.The Jiuzhaigou National Nature Reserve was most impacted among the three nature reserves of Jiuzhaigou County.Ourresults provide scientific basis for ecological monitoring,disaster assessment,and restoration in Jiuzhaigou area.