自然灾害胁迫下区域生态脆弱性动态——以四川省清平乡为例

利用四川省绵竹市清平乡2008年“5·12”汶川地震后航空遥感图像和2010年“8·13”特大山洪泥石流灾后无人机低空遥感图像,结合清平乡2006年土地利用现状图、1∶5万地形图与野外调查资料,对清平乡生态脆弱性进行评估和分析.结果表明:清平乡2010年“8· 13”特大山洪泥石流灾后生态不脆弱、一般脆弱、中度脆弱、脆弱和极脆弱区的面积比例分别为1.9％、7.9％、18.7％、23.0％和48.5％,生态极脆弱和生态脆弱区总面积达238.45 km2,占全乡总面积的71.5％,清平乡生态环境整体上已经非常脆弱;受这两次特大自然灾害的胁迫作用,清平乡生态脆弱性明显增强,生态脆弱和极脆弱区面积比“5·12”汶川地震前增加12.4％,生态极脆弱区面积是“5·12”汶川地震前面积的1.67倍;清平乡生态脆弱性动态演化主要表现为生态脆弱性等级由脆弱演化为极脆弱.复杂的地形条件是导致清平乡生态脆弱的关键因素.

Dynamics of regional ecological frangibility under natural hazard stress: a case study in Qingping Town of Sichuan Province, Southwest China

By using the aerial remote sensing images after May 12, 2008 (the date of catastrophic Wenchuan Earthquake) and the unmanned aircraft vehicle remote sensing images after August 13, 2010 (the date of extraordinary debris flow), and in combining with the land use map (1:10000), topographic map (1:50000), and collected field investigation data of Qingping Town, Mianzhu City of Sichuan Province in 2006, this paper analyzed and evaluated the ecological frangibility of the Town. In the Town, the slightly, lightly, moderately, heavily, and extremely fragile ecological zones after the extraordinary debris flow occupied 1.9%, 7.9%, 18.7%, 23.0%, and 48.5%, respectively, with the area of heavily and extremely fragile ecological zones accounting for 71.5% of the total, being 238.45 km2, i. e., the ecological environment was overall very fragile. Under the impact of the two natural hazards, the ecological frangibility degree of the Town increased obviously. As compared with that before the Earthquake, the area of heavily and extremely fragile ecological zones after the Earthquake increased by 12.4%, and the area of extremely fragile ecological zone was 1.67 times larger. The dynamic evolution of the ecological frangibility of the Town was mainly manifested in the conversion of heavily fragile ecological zone into extremely fragile ecological zone. Complex terrain was the key factor of the ecological frangibility of the Town.