Comparison of erodibility of some hararghe soils using rainfall simulation

Abstract

This paper reports an investigation on the comparative erodibility of three soil types occurring in the Hararghe Highlands, Eastern Ethiopia. Rainfall simulation at an intensity of 75 mm h 21 was used to investigate runoff generation and sediment yield characteristics of the three soil types. Results were compared with soil erodibility calculated from measured soil characteristics such as silt content, organic matter content, bulk density, pH (H 2 O) and air-dry aggregates (0.6 -0.2 mm). Aggregate stability index and shear strength measurements were used as surrogates for estimating erodibility. The three soil were not significantly 333 ORDER REPRINTS different in their sediment yield and runoff generation characteristics. However, sediment yield was highest for the Fluvisol both under dry and wet soil conditions which is in agreement with its lowest shear strength. The high rock-fragment (stone content) of the Regosol had a confounding influence on the actual erodibility of the Regosol, while the relatively low air-dry aggregate (0.6 -0.2 mm) content and high very fine sand and silt content of the Fluvisol rendered it to high sediment yield. Aggregate stability index was more in agreement with predicted erodibility than shear strength while shear strength was better related to sediment loss.

Surface runoff and soil erosion from Nitisols and Ferralsols as influenced by different soil organic carbon levels under simulated rainfall conditions

“…This indicated that although the organic matter level in the soil plays a major role in preventing soil erosion, the type of soil also has an important influence on erosion. This observation is in line with that of Fufa et al [ 103 ] and Ma et al [ 104 ] who concluded that the prediction of erodibility based on measured soil properties could be significantly influenced by its rock fragment content. This finding may be explained by Ferralsols ' high rock-fragment content and low organic matter content, both of which had confounding effects on the generation of runoff and the subsequent sediment yield.…”

Effects of Simulated Gravel on Hydraulic Characteristics of Overland Flow Under Varying Flow Discharges, Slope Gradients and Gravel Coverage Degrees

“…A reduction of the gravel coverage degree does not prevent the soil surface from sealing and leads to a decreased infiltration rate 19 . Gravel laying on the soil surface decreases runoff generation and increases the infiltration rate 20,21 , whereas gravel embedded in soil increases the runoff rate 22 . Moreover, the gravel particle size may contribute to plugging soil macropores 23 .…”

Relationships between rock fragment cover and soil hydrological response in a Mediterranean environment

“…Laboratory experiments have demonstrated that a decrease in rock fragment cover leads to a decrease in infiltration because part of the porosity has disappeared and the soil surface is not prevented from sealing (Brakensiek and Rawls 1994; Grant and Struchtemeyer 1959). However, the effect of rock fragments on the soil surface also depends on their relative position at the surface: rock fragments laying on the soil surface affect erosion by softening the splash effect of raindrops, delaying the time of initiation of run‐off and preventing sealing processes (Daba Fufa et al. 2002; Martínez‐Zavala and Jordán 2008).…”