岩溶地区坡地土壤地表、地下流失定量评价

The soil-forming process was very slow and surface and subsurface soil loss were concomitant in karst area. It was pivotal to the prevention and cure of stony desertification and ecological restoration that the characteristics of surface and subsurface soil loss and it's quantitative evaluation were thorough researched. The rare earth element tracers technology is better than other element tracers technology for describing the erosion process of slope field, but the reports could hardly be seen that the erosion process of slope field was discussed with the rare earth element tracers technology in karst area. The characteristics of surface soil loss and estimation of subsurface soil loss were discussed with the single rainfall observation and rare earth element tracers technology in runoff-plot and the quantitative evaluation method of surface and subsurface soil loss for sloping field was structured. The results were helpful to the prevention and cure of water and soil loss in karst area.

岩溶地区成土速度十分缓慢，土壤地表、地下流失共存，岩溶地区的"土壤丢失"现象已被国内外众多研究者揭示，深入研究土壤地表、地下流失特征及其定量评价，对该区域石漠化防治与生态恢复具有重要的科学意义和实用价值。利用稀土元素（rare earth elements，REE）示踪来定量监测坡面侵蚀的演变过程，比其它示踪剂具有较大的优越性，而利用稀土元素（REE）示踪技术研究岩溶地区坡地土壤侵蚀过程少见报道，因此，本项目拟将径流小区天然次降雨观测、稀土元素示踪技术与土壤养分垂直分布分析相结合，开展岩溶地区坡地土壤地表、地下流失特征及其定量评价研究，构建岩溶地区坡地土壤地表、地下流失定量评价方法，结果可为探讨岩溶地区水土流失治理问题提供科学依据。

岩溶地区成土速度十分缓慢，土壤地表、地下流失共存，本研究将径流小区天然次降雨观测、稀土元素示踪技术与土壤养分垂直分布分析相结合，开展岩溶地区坡地土壤地表、地下流失特征及其定量评价研究。12个径流小区2014年-2017年31场侵蚀性次降雨观测结果分析表明，径流小区地表年平均土壤侵蚀模数为152t/hm2，地表土壤发生侵蚀的降雨雨量为19mm，平均雨强为0.06mm/min；径流小区地下年平均土壤漏失模数为224t/hm2，土壤发生地下漏失的降雨雨量为16mm，平均雨强为0.04mm/min；对侵蚀性降雨而言，雨强是影响岩溶地区坡地土壤地表流失和地下漏失量的关键因子，平均雨强0.068 mm/min是影响岩溶地区坡地土壤地表流失和地下漏失量的阈值；平均雨强小于0.068 mm/min时，以地下漏失为主，平均雨强大于0.068 mm/min时，地表流失量急剧增加。总体而言，岩溶地区坡地年平均土壤地表流失和地下漏失总量为376t/hm2，地表流失和地下漏失的比例约为1:1.5。结果可为岩溶地区水土流失治理问题提供科学依据。