陇中黄土高原丘陵沟壑区不同植被恢复模式下次降雨产流产沙特征

基于甘肃省清水县汤峪河径流小区2015—2017年的观测数据,研究不同植被恢复模式条件下坡面次降雨入渗、产流产沙特征。结果表明：不同植被恢复模式条件下的土壤入渗量与降雨强度呈二次函数关系,存在入渗量达到最大值的临界降雨强度。入渗速率与降雨历时可以用幂函数关系表达,符合考斯恰可夫入渗模型。不同植被恢复模式条件下的产流率在0.003 3~0.003 6 mm·min^-1之间,相对裸地的减流率为54%~58%。产流率与降雨强度之间呈二次函数关系（R²>0.88）,产流率的主要影响因素是降雨强度。径流含沙量平均值乔灌混合区（3.13 g·L^-1）>灌木林（2.95 g·L^-1）>乔木林（2.79 g·L^-1）>草地（2.58 g·L^-1）,径流含沙量与降雨强度呈线性递增函数关系。裸地的产沙量显著高于各植被小区（P<0.05）,是各植被小区的43~57倍,各植被小区的减沙率在93%~94%之间,减沙效益高于其减流效益。各植被坡面土壤流失量与降雨侵蚀力呈线性递增函数关系;产流率与侵蚀产沙率之间呈极显著正相关关系（P<0.01）,二者间可采用二次函数关系表达。本研究成果可为黄土高原丘陵沟壑区水土保持优化配置提供理论依据。

Characteristics of slope runoff and sediment of different vegetation restoration patterns under individual rainfall events in hilly and gully loess region in middle Gansu Province

Observations of rainfall infiltration,runoff,and sediment of different vegetation restoration patterns were made at the Tangyuhe runoff plot in Qingshui County,Gansu Province,China from 2015 to 2017. This runoff plot contains complex arbor and bush land,bush forest,arbor forest,and grassland. Our results show that the relationship between the amount of soil infiltration for different vegetation restoration patterns and rainfall intensity followed a quadratic function,as critical rainfall intensity produced the largest infiltration amount. Meanwhile,the relation between the infiltration rate and rainfall duration can be described using the power function,which coincided with the Kostiakov infiltration model. The runoff rate of different vegetation restoration patterns ranged from 0.033 cm·min^-1 to 0.036 cm·min^-1. In contrast,bare land had a runoff rate of 0.079 cm·min^-1. The runoff reduction rate of different vegetation restoration patterns was approximately 54% to 58% compared with bare land. The relation between the runoff rate and rainfall intensity can be expressed as a quadratic function（R²>0.88）,which was induced primarily by rainfall intensity. The order,from highest to lowest,of average sediment concentration was as follows：complex arbor and bush land （3.13 g·L^-1）>bush forest （2.95 g·L^-1）>arbor forest （2.79 g·L^-1）>grassland （2.58 g·L^-1）. The relation between sediment concentration and rainfall intensity can be expressed as a linear increasing function. The sediment yield of bare land reached 2.558 t·hm^-2,which is 43 to 57 times higher than that of vegetation plots （P<0.05）. The sediment reduction rate of each vegetation plot was between 93% and 94%,and the benefit of sediment reduction was greater than that of runoff reduction. The relationship between soil loss and rainfall erosivity can be expressed as a linear increasing function,while the relationship between runoff rate and rate of sediment yield displayed a very significant positive correlation （P<0.01）,which can be stated as a quadratic function. These results are relevant for optimizing the configuration of water and soil conservation in the loess hilly regions and gully regions.