基于GIS/RS的地震灾区流域水土保持功能恢复效应评价

Assessment of Restoration of Soil and Water Conservation Function in Watershed in Earthquake Disaster Area Based on GIS/RS

水土保持在维护区域生态安全中具有重要作用。"5.12"汶川地震中,茶坪山区域水土保持功能严重受损,经过4年时间,其恢复效果及变化趋势如何,是决策者迫切需要的重要信息。利用TM影像,解译了研究小流域2007、2008、2011年地震前后3个时段的土地利用图。基于GIS和RS,利用RUSLE模型分别计算了3个时段土壤侵蚀量和侵蚀强度。通过对比,分析了水土保持功能恢复效应。结果表明:总面积474.41km2的研究区内,2007年土壤侵蚀总量4.061×105t,2008年土壤侵蚀总量6.997×105t,增加了72.30%。2011年土壤侵蚀总量6.163×105t,相比2008年,土壤侵蚀总量减少了11.92%,水土保持功能有所恢复。分析发现,地震前后3个年份各侵蚀强度级别的面积都是随侵蚀强度的增加而减少,说明地震破坏及恢复期,土壤侵蚀强度的面积分布格局并未改变。

Soil and water conservation plays an important role in the maintenance of regional ecological security. Soil conservation function of Mountain Chaping region was badly damaged during ＂5.12＂ Wenchuan earthquake. After four years, how the effect it recovery and change trend, are information that policymakers need urgently. The land-use maps of the small watershed in 2007, 2008 and 2011 including three periods before and after the earthquake were interpreted using TM image. Based on GIS and RS, using RUSLE model the quantity and intensity of soil erosion of the three periods were calculated respectively. Through the contrast, the restoration effect of soil＇and water conservation function was analyzed. The results showed that in the research area with 474.41 km2, the total soil erosion in 2007 was 4. 061 x 105 t, and that in 2008 was 6. 997 x 105 t, increasing than 2007 by 72. 30%. In 2011, the total amount of soil erosion was 6. 163 x 105 t, compared with that in 2008, the total amount of soil erosion decreased by 11.92% , soil and water conservation function restored. By analysis it found that in three years before and after the earthquake, the area of every level of erosion intensity decreased with the increase of erosion intensity, which meant that there was no change of the soil erosion pattern during the periods of earthquake damage and restoration.