基于实地和遥感调查的离子型轻稀土尾砂土壤侵蚀对植被修复措施响应

稀土开采产生大量尾砂,导致严重土壤侵蚀,伴生水质和地质灾害,评价植被修复措施对稀土尾砂土壤侵蚀治理效果可为措施优选提供理论依据。以寻乌县离子型轻稀土尾砂区为研究区,基于1982—2015年GIMMS NDVI 3 g、DEM等遥感和尾砂理化性状现场调查数据,采用空间代时间方法,结合RUSLE模型及其全微分公式探究不同修复年限土壤侵蚀量对植被修复措施的响应机理。结果表明:1982—2015年研究区土壤侵蚀模数显著下降,倾向率为-60 t/(km~2·10a),突变年份为2008年;在植被修复措施实施年(2008年)前后,多年平均土壤侵蚀量减幅超过60%;土壤侵蚀模数呈现上升、平稳、上升、平稳、上升和下降的阶段性变化,与NDVI时程变化呈负相关;水土保持措施、植被覆盖、土壤可蚀性和降雨变化对土壤侵蚀量减小的贡献率分别为33.18%,32.19%,19.95%,13.19%。植被修复过程中,矿区土壤侵蚀量减少的主要影响因子为水土保持措施因子和植被覆盖因子。

Response of Soil Erosion to Vegetation Restoration Measures in Ion-type Light Rare Earth Tailings Based on Field and Remote Sensing Investigation

The mining of rare earth produces a large amount of tailing, resulting in serious soil erosion, associated with water quality and geological disasters. Evaluating the effect of vegetation restoration measures on soil erosion control of rare earth tailings can provide theoretical basis for the optimization of measures. With the method of spatial sere substituting for time sere, this study took ion-type light rare earth tailings area of Xunwu County as an example to analyse the response mechanism of soil erosion to vegetation restoration measures under different repair years, using the RUSLE and its total differential formula based on GIMMS NDVI 3 g data from 1982 to 2015, DEM and field survey data. The results showed that soil erosion modulus decreased obviously at a rate of -60 t/(km²·10a), and the change point was 2008. The annual average soil erosion decreased by more than 60% before and after the implementation of vegetation restoration measures (2008). The soil erosion modulus showed the stage changes of rising, stable, rising, stable, rising and falling, and the NDVI showed the opposite changes in the corresponding period. The contribution rates of the soil and water conservation practices factor, the vegetation cover factor, the soil erodibility factor and the rainfall erodibility factor to soil erosion reduction were 33.18%, 32.19%, 19.95% and 13.19% respectively. The main influencing factors of soil erosion reduction in the rare earth mining area of Xunwu County were the soil and water conservation practices factor and the vegetation cover factor.