Journal of Geographical Sciences ›› 2020, Vol. 30 ›› Issue (3): 455-467.doi: 10.1007/s11442-020-1737-4

• Research Articles • Previous Articles     Next Articles

Effects of rainfall intensity on the sediment concentration in the Loess Plateau, China

LIU Xiaoyan1, DANG Suzhen2,*(), LIU Changming3, DONG Guotao2   

  1. 1. Yellow River Conservancy Commission, Zhengzhou 450003, China
    2. Yellow River Institute of Hydraulic Research, Yellow River Conservancy Commission, Zhengzhou 450003, China
    3. Beijing Normal University, Beijing 100875, China
  • Received:2019-03-22 Accepted:2019-06-08 Online:2020-03-25 Published:2020-05-25
  • Contact: DANG Suzhen E-mail:dangsz_hky@163.com
  • About author:Liu Xiaoyan (1964–), PhD and Professor of Engineering, specialized in the study of runoff and sediment changes in the Yellow River. E-mail: liuxiaoyan@yrcc.gov.cn
  • Supported by:
    National Key R&D Program of China(No.2016YFC0402400);National Natural Science Foundation of China(No.51779099)

Abstract:

To study the effects of changes in the rainfall intensity on sediment concentrations in the Loess Plateau, the observed rainfall intensities and sediment concentrations from three typical small watersheds were used to analyze the relationship between these parameters. The results showed that the sediment concentration generally increased with the increasing rainfall intensity on slope scale. However, at watershed scale, a significant threshold phenomenon was observed for the effects of the rainfall intensity on the sediment concentration. When the rainfall intensity exceeds the threshold, the flood sediment concentration will no longer increase with the increase in the rainfall intensity. The rainfall intensity threshold increased with increasing vegetation coverage. The rainfall intensity threshold was 10-15 mm/h during 1956-1969, reached 20 mm/h from 1990 to 1997 and is approximately 40 mm/h at present. Due to a rainfall intensity of 10-15 mm/h almost happened every year, the vegetation did not change much from the 1950s to 1980s. Sediment yield mainly depends on soil erosion caused by surface flow, but the surface flow speed does not increase indefinitely with the increase in the flow discharge. Thus, the annual maximum sediment concentration of the tributaries in the loess area has been basically stable before the 1990s.

Key words: Loess Plateau, loess hilly region, rainfall intensity, sediment concentration, influence