Effect of Rainfall Regime and Slope on Runoff in a Gullied Loess Region on the Loess Plateau in China

Abstract

Runoff was measured from seven plots with different slopes nested in Tuanshangou catchment on the Loess Plateau to study effect of slopes on runoff in relation to rainfall regimes. Based on nine years of field observation and K-mean clusters, 84 rainfall events were grouped into three rainfall regimes. Rainfall regime A is the group of events with strong rainfall intensity, high frequency, and short duration. Rainfall regime C consists of events with low intensity, long duration, and infrequent occurrence. Rainfall regime B is the aggregation of events of medium intensity and medium duration, and less frequent occurrence. The following results were found: (1) Different from traditional studies, runoff coefficient neither decreased nor increased, but presented peak value on the slope surfaces; (2) For individual plot, runoff coefficients induced by rainfall regime A were the highest, and those induced by rainfall regime C were the lowest; Downslope, the runoff coefficients induced by three rainfall regimes presented the same changing trend, although the peak value induced by regime A occurred on a shorter slope length compared to those by regime B and C; (3) Scale effect on runoff induced by rainfall regime A was the least, and that induced by rainfall regime C was the largest. These results can be explained by the interactions of crusting, soil moisture content, slope length and gradient, and erosion units, etc., in the context of different rainfall regimes.

The temporal changes in road stormwater runoff quality and the implications to first flush control in Chongqing, China

“…The reason for this difference is probably because of the quick convergence of runoff from the slope (10°) in our study. Chaplot and Le Bissonnais (2000) and Fang et al (2008) found also that the larger slope gradient could lead to higher flow velocity and increased runoff generation capacity. Similar temporal patterns were shown between TSS and TP.…”

Spatial scale dependence of sediment dynamics in a gullied rolling loess region on the Loess Plateau in China

“…Crusting is easily formed for the loess-textured soils on the Loess Plateau, and the hard layer on the soil surface increases its antierodibility (Luk et al 1989, Fang et al 2008b. Runoff scour and crusting formation during rainfall bred a temporal lack of sediment that produced a certain percentage of type I floods and clockwise hysteresis loops in slope zones (Table 3; Fig.…”

The characteristics of rill development and their effects on runoff and sediment yield under different slope gradients

“…For the total erosion, Jin (1995) presented that there was a critical slope which made erosion from strong to weak, but it is not a constant value, which changed with other factors such as soil property, rainfall intensity, etc. (Fang et al 2008;He et al 2012). Rill node, rill number and distance of the longest rill to the top of the slope were also used to analyze the characteristics of rill formation (Table 3).…”