Monitoring of Ecological Restoration at the Central Quake-Hit Areas of Wenchuan Earthquake Using RS & GIS Remote Sensing

Abstract:

The 2008 Sichuan earthquake, occurred on 12 May 2008 with a magnitude of 8.0 and the center at Wenchuan (31.021°N, 103.367°E), has not only caused a large number of human casualties and property loss, but also severely damaged the ecological system in its surrounding 10 counties, threatening the local ecological safety. As part of the post-disaster reconstruction services, a systematic monitoring of the ecological restoration at the central quake-hit areas has been made based on RS & GIS remote sensing. In this paper we selected the Dujiangyan area for analysis. The reason to select this region is because that Dujiangyan area is about 40 km from the epicenter, and as a region in the subtropical monsoon climate zone, it has a well developed forest ecosystem in the northern part before the earth quake. The coverage of grassland in this region is relatively less. Since the ecological restoration after the earthquake is a long term process, the restoration for different vegetation types has different characteristics. From the analysis of the spatiotemporal change of land-use and vegetation cover in Dujiangyan area from the post-earthquake in 2008 to 2013, we found: (1) During the earthquake, the major vegetation type destroyed is the woodland, which accounts for 99.34% of the destroyed area, and the next are arable land and grassland. (2) The ecological restoration started from the grassland and gradually transited to shrub. In two years after the earthquake, the most significant increase in both area of coverage and magnitude is the grassland, and by 2013, the area of grassland decreased slightly, and instead the area of shrub increased, demonstrating a transition trend from the grassland to the shrub. (3) From the map of vegetation cover, we can see these change occurs mainly in the northern mountain area, while the change of land use mainly occurred in the southern part of the city. These changes can be linked clearly with the earthquake disaster and the post- reconstruction human activities.