紫色土小流域土壤流失对不同土地利用类型的响应

Response of soil loss to different land use types in small watersheds of purple soil

小流域土壤流失特征不仅反映了流域的土地利用和管理状况,而且对其下游水体环境和水利设施安全具有深刻的影响。1999—2000年间以紫色土区3个具有不同集水面积、物理特征和土地利用类型的典型小流域为研究对象,探讨不同雨型下土壤流失对不同土地利用类型的响应特征。中大型降雨和间歇型降雨侵蚀下,以林地为主要土地利用类型的流域输沙模数最小,平均为866 kg·hm-2,谷地农田利用类型最高,平均为5 550 kg·hm-2。次降雨侵蚀力和次降雨峰值径流流量,分别是紫色土区非林地和林地利用为主小流域输沙模数变异的主要影响因子。

Soil erosion characteristics of small watersheds not only reflect land use and management condition of watersheds, but also determine the safety of water body environment and water conservancy establishment in the lower reaches of river. Three small watersheds with different catchments area, physical characteristics and land use type were employed to investigate the responding characteristics of soil erosion under different storm types and land use types from 1999 to 2000 in the purple soil area, Results showed that the sediment transport modulus over the woodland-dominated watershed is the least under the erosion of ML-type precipitation and IM- type precipitation. The average modulus is 866 kg· hm^- 2. In contrast, the modulus over the farmland - domi- nated watershed is the highest with a mean modulus of 5 550 kg·hm^- 2. In addition, the total rainfall erosive factor and the total peak flow amount were proved to be the main influential factors of the variation of the sediment transport modulus for watersheds with various landscape structures and farmland-dominated landscapes, and woodland - dominated watersheds, respectively.