三峡库区紫色土坡耕地土壤侵蚀研究：进展与方向

紫色土坡耕地是三峡库区粮食经济作物的主产载体，也是库区水土流失的主要源地和入库泥沙的主要来源。结合野外调查和相关报道，对三峡库区紫色土坡耕地土壤侵蚀研究方法、侵蚀强度、泥沙颗粒形态以及侵蚀引起的养分流失等方面进行综述。结果表明，坡耕地土壤侵蚀研究方法主要包括径流小区法、人工模拟降雨法和侵蚀针法等直接观测方法和核素示踪、模型模拟和遥感监测等间接观测方法；库区紫色土坡耕地土壤侵蚀速率达3464～9452t／km2，其中15°～25°坡度范围的土壤侵蚀最为严重，是今后坡耕地土壤流失防治的重点坡段；流失泥沙主要以〈0．02mm的团聚体和〈0．002mm的粘粒为主，其中粉粒（0．002~0．02mm）和粘粒（〈0．002mm）携带的养分流失较多；植物篱、垄作和坡改梯等措施理水效果明显，均对坡耕地侵蚀产沙具有较好的控制作用。今后应在模型方法、埂坎结构和功能、水土保持措施适宜性评价等方面拓展研究。

Review of Soil Erosion on Purple-soil Sloping Croplands in Three Gorges Reservoir Area

The purple sloping farmland is an important cropland resource in the Three Gorges Reservoir area, and the main source of soil erosion and sediment into the Reservoir. Soil erosion monitoring methods, soil erosion intensity, sediment particle features, nutrient loss on purple soil sloping croplands in the Three Gorges Reservoir Area are summarized. The erosion monitoring methods mainly include runoff plot observation, artificial simulated rainfall, erosion pin observation, nuclide tracing, model simulation, RS monitoring. The publications show that soil erosion rates of the purple sloping croplands range from 3 464 to 9 452 t/km2 · a, and the most serious erosion usually occurs on the slope from 15° to 25°, wich is also the focus slope gradient for preventing soil erosion on sloping cropland in the future. The loss of sediment is dominated by aggregates （%0. 02mm） and clay （%0. 002mm）. The silty （0. 002~0. 02mm） and clay soils （%0. 002mm） are the main carrier of soil nutrient loss on the purple sloping croplands. Hedgerows, contour tillage and terracing are given a significant effect in preventing soil erosion. The erosion simulation using physi- cal model, the structure and function of ridge and suitability evaluations of soil conservation measures are recommended for further study in this particular geographical unit.