黄土高原植被作用下黄河数字流域模型坡面侵蚀模块改进

Improved hillslope erosion module of the digital Yellow River integrated model considering the vegetation effects on the Loess Plateau

植被是影响坡面侵蚀的重要因素,如何在基于物理机制的侵蚀产沙过程中考虑植被作用仍是目前亟需解决的关键问题。该文基于土壤分离能力与泥沙输移能力双重限制的坡面侵蚀产沙机制,建立了考虑植被作用的坡面侵蚀模型。采用黄土高原典型流域径流小区数据对所建模型进行验证,结果表明:不同土地利用下该模型的决定系数为0.84~0.94, Nash-Sutcliffe有效系数为0.83~0.93,相对误差为-16.1%~14.2%。与黄河数字流域模型现有坡面侵蚀模块(决定系数0.01~0.51, Nash-Sutcliffe有效系数-74.45~0.48)相比,该文所建立的模型明显改善了不同土地利用和植被作用下的侵蚀产沙过程模拟,模拟产沙量的相对误差绝对值降低13%~96%,还具有与分布式流域水沙模型集成和应用的潜力。

Vegetation plays an important role in controlling hillslope erosion but how the vegetation controls the soil erosion is still not well understood. The interactions between the soil detachment capacity and the sediment transport capacity were modeled in a hillslope erosion model that integrates vegetation effects. Runoff plot data in typical watersheds on the Loess Plateau were used to validate the model with coefficients of determination values ranging from 0.84 to 0.94, Nash-Sutcliffe simulation efficiencies(NSE) ranging from 0.83 to 0.93 and relative errors ranging from-16.1% to 14.2% for various land uses. The original module in the digital Yellow River integrated model(DYRIM) had coefficients of determination ranging from 0.01 to 0.51 and NSE ranging from-74.45 to 0.48. Thus, the new model is more accurate for various land uses and vegetation types with the absolute values of the simulated sediment discharge rates reduced by 13%-96%. This model can be applied to the Loess Plateau and can be integrated into DYRIM and other distributed hydrological and sediment coupled models.