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ARS Home » Southeast Area » Tifton, Georgia » Southeast Watershed Research » Research » Publications at this Location » Publication #126940
Title: RAINFALL AND SURFACE ROUGHNESS EFFECTS ON SOIL LOSS AND SURFACE RUNOFF

Author
item JESTER, W - UNIV. AG. SCI.V.AUSTRALIA
item KLIK, A - UNIV.AG.SCI. V. AUSTRALIA
item HAUER, G - UNIV.AG.SCI.V.AUSTRALIA
item HEBEL, B - UNIV.OF BASEL,SWITZERLAND
item Truman, Clinton

Submitted to: Soil Erosion for 21st Century Symposium
Publication Type: Proceedings
Publication Acceptance Date: 1/20/2001
Publication Date: 1/20/2001
Citation: JESTER, W., KLIK, A., HAUER, G., HEBEL, B., TRUMAN, C.C. RAINFALL AND SURFACE ROUGHNESS EFFECTS ON SOIL LOSS AND SURFACE RUNOFF. SOIL EROSION FOR 21ST CENTURY SYMPOSIUM. PP. 463-466. 2001.

Interpretive Summary: Soil surface roughness affects infiltration, runoff generation, and amount of soil detachment and sediment transport occurring from interrill areas. We evaluated the effect of rainfall intensity (I=20-60 mm/h) on surface roughness decay, changes in soil microtopography, runoff, splash sediment, and soil loss. Soil loss, splash sediment, and runoff were measured from a 1.47 m*2 lab erosion pan in 5-min intervals throughout each event. Slope index was the best indicator of roughness decay due to rainfall. Quadratic polynomial curves described roughness decay for each rainfall and roughness condition. Cumulative runoff and soil loss increased as initial roughness decreased and was dependent on rainfall intensity sequence. Cumulative splash sediment was independent of microtopography, but was dependent on rainfall intensity sequence. Rainfall intensity sequence and initial roughness condition also influenced the time until runoff and the steady- state runoff rate. Soil loss rates varied with rainfall intensity even though runoff rates remained relatively constant. Splash sediment rates were rainfall intensity-dependent and decreased during each rainfall event. Understanding how erosion processes are influenced by surface roughness- rainfall intensity interactions will increase our ability to model the erosion process.

Technical Abstract: Soil surface roughness affects infiltration, runoff generation, and amount of soil detachment and sediment transport occurring from interrill areas. We evaluated the effect of rainfall intensity (I= 20¿60 mm/h) on surface roughness decay, changes in soil microtopography, runoff, splash sediment, and soil loss. Air-dried soil was placed in small erosion pans (1.47 m*2) with three surface roughness conditions and exposed to three simulated rainfall events (constant, increasing, and decreasing intensity). Soil loss, splash, and runoff were measured in 5-min intervals throughout each event. Among the compared roughness indices, slope index was the best indicator of roughness decay due to rainfall. Quadratic polynomial curves described roughness decay for each rainfall and roughness condition. Cumulative runoff and soil loss increased as initial roughness decreased and was dependent on rainfall intensity sequence. Cumulative splash sediment was independent of microtopography, but was dependent on rainfall intensity sequence. Rainfall intensity sequence and initial roughness condition also influenced the time until runoff and the steady-state runoff rate. Soil loss rates varied with rainfall intensity even though runoff rates remained relatively constant. Splash sediment rates were rainfall intensity-dependent and decreased during each rainfall event.