应用KINEROS2模型对土质道路侵蚀过程的模拟

Modeling erosion processes on unpaved roads using KINEROS2

土质道路在三峡库区分布广泛,是库区泥沙重要来源地之一。在考虑道路的水沙效应基础上,结合野外调查和相关研究将三峡库区土质道路分为3级,Ⅰ级车流量大,主要为集镇之间的道路;Ⅱ级是Ⅰ级与大型村落间的道路;Ⅲ级多见于Ⅰ或Ⅱ级至农户的道路。为了有效评估其侵蚀风险、预测径流和侵蚀速率,以3级土质道路的人工降雨资料为基础,应用KINEROS2模型对土质道路的侵蚀过程进行了模拟。结果表明,径流量误差在3.6%～14.7%,侵蚀量的误差在4.5%～31.8%,对人为干扰相对较小的Ⅲ级道路模拟效果要好于Ⅰ级或Ⅱ级道路。土壤流失过程的模拟效果相对较差,初期明显低于实测值,而后期则高于实测值。

Unpaved road is a ubiquitous feature in mountainous areas.Although such roads facilitate the use and management of natural resources,they may result in adverse changes in watershed processes.In particular,they can alter hydrologic processes that influence sediment transport and delivery.In this paper,the Wangjiaqiao Watershed,located in the Three Gorges Area（TGA）,is taken as a case study area to understand the impacts of unpaved roads on hydrologic processes,sediment transport,and sediment delivery at small watershed scale from a multidisciplinary perspective. The results showed that roads on the TGA could be classified into 3 classes based on their functions and scales.The event-and physics-based KINEROS2 runoff/erosion model for predicting overland flow generation and sediment production was applied to unpaved roads.Field rainfall simulations conducted in the TGA provided independent data for model calibration and validation.Validation showed that KINEROS2 can be parameterized to simulate total discharge,sediment transport and sediment concentration on small-scale road plots during simulated rainfall events.Differences between measured and simulated values in total runoff and total soil loss were about 3.6%-14.7% and 4.5%-31.8%,respectively.The KINEROS2 model,however,did not accurately predict time-dependent changes in sediment output and concentration.In particular,early flush peaks and the temporal decay in sediment output were not predicted.