Rainfall runoff in soil erosion with simulated rainfall, overland flow and cover

Abstract

The 20-100 mm portion of a yellow podzolic soil (Albaqualf) from the Ginninderra Experiment Station (A.C.T.) was used in a rainfall simulator and flume facility to elucidate the interactions between raindrop impact, overland water flow and straw cover as they affect soil erosion. A replicated factorial design compared soil loss in splash and runoff from 50 and 100 mm h-1 rainfall, the equivalent of 100 mm h-1 overland flow, and 50 and 100 mm h-1 rainfall plus the equivalent of 100 mm h-' overland flow, all at 0, 40 and 80% straw cover on a 9% slope. As rainfall intensity increased, soil loss in splash and runoff increased. Within cover levels, the effect of added overland flow was to decrease splash but to increase total soil loss. This is due to an interaction between raindrops and runoff which produces a powerful detaching and transporting mechanism within the flow known as rain-flow transportation. Airsplash is reduced, in part, because of the changes in splash characteristics which accompany changes in depths of runoff water. Rain-flow transportation accounted for at least 64% of soil transport in the experiment and airsplash accounted for no more than 25% of soil transport The effects of rainfall, overland flow and cover treatments, rather than being additive, were found to correlate with a natural log transform of the soil loss data.

PSEM_2D: A physically based model of erosion processes at the plot scale

“…The other parameters that can be entered as spatial distribution are the flow erodibility parameter K r , the rainfall erodibility coefficient for original soil a, the rainfall Figure 2. Comparison of (a) numerical outflow discharge hydrographs and (b) numerical sedimentographs obtained using PSEM_2D with the results of Govindaraju and Kavvas [1991] and the experimentally observed results of Singer and Walker [1983]. erodibility coefficient for the deposited layer a d , and the elevation of the soil surface z.…”

“…For this reason we propose to test the model over planar surfaces using data from the literature. We use the experimental data of Singer and Walker [1983] and Kilinc and Richardson [1973] and the analytical solution of Govindaraju and Kavvas [1991]. As an illustration we show the ability of PSEM_2D to run over non planar surfaces.…”

“…4.1.1. Experimental Data of Singer and Walker [1983] [29] The experiment set up used by Singer and Walker [1983] was a laboratory flume (3.0 by 0.55 m) of 9% slope and a rainfall simulator. The soil was a fine sandy loam with a clay content of 13.9% and a high amount of silt plus very fine sand (59.2% in the range 2 Â 10 À6 -1 Â 10 À4 m).…”

“…Collected by Singer and Walker [1983] [38] We first compare the performance of the model with results obtained from experiments conducted by Singer and Walker [1983]. The soil surface is represented as a plane element of 3.0 m long by 0.55 m wide using uniform grid cells of 0.05 m by 0.05 m.…”

“…We found a value of 5.2 mm h À1 . Figure 2 shows the comparison of numerical outflow discharge hydrographs (Figure 2a) and numerical sedimentographs (Figure 2b) obtained using PSEM_2D with the analytical results of Govindaraju and Kavvas [1991] and the experimentally observed results of Singer and Walker [1983].…”