5·12汶川地震重灾区水土流失初步估算

Estimation of Soil Erosion Caused by the 5·12 Wenchuan Earthquake

5·12汶川地震诱发大量的崩塌、滑坡、堰塞湖,导致了大量的水土流失。基于北京一号小卫星影像数据,在重灾区共解译出崩塌、滑坡点总面积2264.53km2。通过对重灾区内距离地震破裂带分别做5km、10km、30km、50km、100km的缓冲区,分别统计不同区段的崩塌、滑坡体的面积,结合野外实地考察和简易测量数据来确定不同区段的松散土体厚度,初步计算出重灾区的崩塌、滑坡水土流失量为相当于全国一年的水土流失量。通过对重灾区34处重点堰塞湖的堰塞坝堆积方量进行计算,估算所有堰塞湖的堰塞坝水土流失量为1.87×108t。重灾区山地灾害的水土流失总量为55.86×108t。讨论估算中存在的问题,提出了进一步提高精度的措施。

The Wenchuan earthquake on May 12, 2008 has induced many secondary disasters, such as collapse, landslide, dammed lake, as well as a wide range of soil erosion. Based on the image data form Beijing No. 1 small satellite, it is estimated that collapses and landslides cover a total area of 2 264.53 km^2 in the heavy disaster areas. Furthermore, distribution of the total erosive area is analyzed with respect to the subregions in radius of 5 km, 10 km, 30 km, 50 km, 100 km respectively from the major fault. Besides, the erosive depth has been estimated by field investigation. Consequently, the amount quantity of soil erosion of collapse and landslide is about 55.86 × 10s ton. In addition, the erosion quantity from the 34 major dammed lakes is estimated as 1.87 × l0^8ton. Thus the soil erosion in the quake-hit area amounts to the quantity in a whole year before. Finally, some problems involved in the estimation are discussed.