红壤区裸露坡地不同类型次降雨的产流产沙规律

为探究红壤区裸露坡地在不同类型次降雨下的产流产沙规律,研究收集长汀县水土保持科教园红壤裸露坡地径流小区2013年1月至2020年12月共388场降雨—径流—土壤侵蚀观测资料,采用K-means将降雨划分为4类进行分析。结果表明:(1)主要降雨类型有A(短历时、大雨强、小雨量、低频次)、B(长历时、小雨强、大雨量、中频次)、C(中等历时、小雨强、小雨量、高频次)3类,B、C为研究区主要产流产沙来源,贡献85%以上的径流和土壤侵蚀量。(2)次降雨径流深及土壤侵蚀量与降雨量(P)、最大30 min雨强(I₃₀)和降雨动能(E)呈线性正相关,与降雨侵蚀力(EI₃₀)呈幂函数关系。但降雨特征对产流产沙的总解释度小于65%,且随着降雨历时的增加而减小。(3)降雨特征与产流产沙存在3种约束关系,其约束线表明降雨特征对次降雨潜在最大产流产沙的影响。其中,潜在最大径流深主要由P和E决定,潜在最大土壤侵蚀量的上限为800~900 t/hm²。从降雨特征单因子影响、综合影响和约束效应3个方面分析了红壤裸露坡地的产流产沙特征,为红壤区水土流失防治提供了数据基础。

Runoff and Sediment of Different Rainfall Types on Bare Slope in the Red Soil Region

In order to explore the characteristics of runoff and sediment of different rainfall types on bare slope in the red soil region, the data of 388 rainfall-runoff-soil erosion observations were collected from January 2013 to December 2020 in the red soil bare slope runoff community of Soil and Water Conservation Center of Changting Country, and rainfall events were divided by K-means clustering method into 4 types for analyzing. The results indicated that: (1) There were 3 main rainfall types in the study area, including A (short duration, large rainfall intensity, small rainfall amount, and low frequency), B (long duration, light rainfall intensity, large rainfall amount, and medium frequency) and C (medium duration, light rainfall intensity, small rainfall amount, and high frequency). Types B and C were the main sources of runoff and sediment yield on bare slope, which contributed more than 85% of runoff and soil erosion; (2) Runoff depth and soil erosion of single-rainfall were linearly positively correlated with the rainfall amount (P), maximal rainfall intensity of 30 min (I₃₀) and rainfall kinetic energy (E), and presented a power function relationship with rainfall erosivity (EI₃₀). However, the total interpretation of rainfall characteristics on runoff and sediment was less than 65%, and decreased with the increase of rainfall duration; (3) There were 3 kinds of constraints between rainfall characteristics and runoff and sediment of bare slope, and the constraint line showed the influence of rainfall characteristics on the potential maximum runoff depth and soil erosion. The potential maximum runoff depth of single-rainfall was mainly determined by P and E, and the potential maximum soil erosion of single-rainfall had a ceiling of 800~900 t/hm². The runoff and soil erosion characteristics of bare slope in the red soil region were analyzed from three aspects: single factor influences, comprehensive influences and constraint effects of rainfall characteristics, which provided a data basis for the soil erosion control in the red soil region.