基于GIS/RS的灾区土壤保持功能恢复效应评价

Evaluation of Restoration Effect of Soil Conservation Function in Disaster Area Based on GIS/RS

土壤侵蚀是土地退化的根本原因,也是导致生态环境恶化的重要影响因素,随着地震等重大地质灾害的发生,灾区土壤保持功能遭到严重破坏,因而进行地震灾区土壤保持功能恢复效应评价具有重大意义。选择"5·12"汶川大地震极重灾区为研究区,以2007年、2009年、2011年研究区Landsat5 TM数据及DEM数据为主要数据源,结合降雨信息数据等其他数据,运用修订的通用土壤流失方程(RUSLE),以ArcGIS软件作为平台,建立了灾区土壤保持功能恢复效应评估模型。研究结果表明:灾区2007年平均土壤侵蚀模数为3 389.57 t/(hm^2·a),年侵蚀总量为8.75×10~7 t,2009年土壤侵蚀模数增加了64.64%,平均为5 580.60 t/(hm^2·a),年侵蚀总量为1.44亿t,相比2009年、2011年土壤侵蚀模数减少了24.08%,年侵蚀总量为1.09亿t,土壤保持功能有所恢复;从土壤侵蚀面积和土壤侵蚀模数两个角度来看,灾区土壤保持功能也达到了一定的恢复;此外,离地震中心越近的地方,土壤保持功能受到的削弱程度越大,其恢复能力也越差,因而,建议有关部门在进行灾后重建的工作中,应当重点加强对震中及其周边地区的改善。

Soil erosion is the fundamental cause of land degradation, and is also an important factor that causes the deterioration of the ecological environment. With the occurrence of earthquake and other major geological disasters, the soil conservation function of the disaster areas has been seriously damaged. Therefore, it is of great significance to evaluate the restoration effect of soil conservation function in earthquake stricken areas. We selected ‘5·12’ Wenchuan earthquake extremely heavy disaster area as the research area, and took the Landsat5 TM data and DEM data in the 2007, 2009, 2011 research area as the main data source, combined the other data of rainfall information and other data, used the revised universal soil loss equation, and used ArcGIS software as the platform to establish the evaluation model of the restoration effect of the soil conservation function in the disaster area. The results showed that the average soil erosion modulus was 3 389.57 t/(hm2·a) in 2007, the annual total erosion amount was 8.75×107 t, the soil erosion modulus increased by 64.64% in 2009, the average was 5 580.60 t/(hm2·a), the annual total erosion amount was 1.44×108 t;compared with the parameters in 2009, the soil erosion modulus decreased by 24.08%, the annual erosion amount was 1.09×108 t, and the soil retention function was restored in 2010. From the aspects of the soil erosion area and the soil erosion modulus, the soil conservation function of the disaster area had also reached a certain recovery. In addition, the closer to the earthquake center, the more weakened the soil conservation function is, the worse the recovery capacity of the soil is. Therefore, it is suggested that the relevant departments should focus on strengthening the change of the epicenter and its surrounding areas in the work of post disaster reconstruction.