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Distribution of Elevation and Relief Amplitude in the Eco-environment Seriously Damaged Areas of Wenchuan Earthquake |
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Abstract: Based on the DEM data, the relief amplitudes of the severest disaster areas of Wenchuan earthquake (including 11 counties) are analyzed. The results show that the southwest is higher than northeast in the area. The regions where the elevation is more than 1 500 m account for 55.34% of the total area, and those with the elevation of more than 3 000 m account for 19.67%. The regions where the elevation is less than 800 m are mainly in the south, and account for 18.59%. The acreage of the region where the relief amplitude within 5 km×5 km grid size is greater than 1 000 m accounts for 23.92%. The acreage of the region where the relief amplitude within 1 km×1 km grid size is greater than 200 m accounts for 44.78%. The elevation of the core disaster area (between the epicentrums of Mw8.0 earthquake and Mw6.4 aftershock) ranges between 650 m and 3500 m. And among this area, the regions where elevation is more than 800 m and less than 2 000 m account for 73.34% of the area. The regions with high elevation and relief amplitude are mainly in the west of the area. The results of analyzing the relief amplitude within 1 km grid size show that the relief amplitude in the south is higher than in the north, and the regions where the elevation is more than 300 m account for 39.07% in the south area and 17.97% in the north area, respectively. The regions where the eco-environment is seriously damaged by the earthquake are mainly in the southwest. The southwest is the center of the earthquake and is also the region with high elevation and relief amplitude, which indicates that there may be some relationship between the damage degree of eco-environment caused by earthquake and the relief amplitude in the area. The acreage of damaged eco-system in the southwest where the relief amplitude is higher accounts for 87.25% of the area, and the acreage of new soil erosion accounts for 68.06%. The chain of causation of the seriously damaged eco-environment in the disaster areas could be described as: strong earthquake+ fault slipping+topography→Geological disasters→damaged vegetation and eco-system→damaged ecological functions.
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Received: 27 July 2009
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