ARS | Publication request: SURFACE ROUGHNESS EFFECTS ON RUNOFF AND EROSION

Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: November 5, 2000
Publication Date: N/A

Technical Abstract: Previous studies showed that soil surface roughness can either increase or decrease soil erosion and overland flow. Nevertheless, factors leading to these opposite results remain largely unknown. During rainfall, random roughness effects come from two geometric components: 1) clods that protrude above and channel the flow; and 2) depressions that hold water and sediments. These two roughness components may have opposing effects on runoff and erosion. A laboratory rainfall simulation study was designed for a multiple-box system to quantify the effects of these two roughness components on erosion processes. The multiple box system has a set of sediment source boxes to generate run-on sediment sources that feeds into a study box. The run-on sediment concentration was varied to create erosion-dominant and deposition-dominant sediment regimes in the study box. Other experimental variables on the study box included: soil erodibility and flow depth. Results showed a strong interaction among soil roughness, soil erodibility and the dominant erosion process. Additionally, the data support the concept of decoupled erosion and sedimentation processes. In consequence, usual considerations of roughness effects have to be reconsidered. Surface roughness cannot be defined by only one index but must be split into several processed-based components to ensure an adequate evaluation of its effects on runoff generation and sediment transport.