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Erosion‐sedimentation in a Closed Drainage Basin in Northwest Indiana
Author(s) -
Norton L. Darrell
Publication year - 1986
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1986.03615995005000010040x
Subject(s) - erosion , watershed , surface runoff , hydrology (agriculture) , loess , sedimentation , geology , universal soil loss equation , sediment , drainage basin , structural basin , drainage , environmental science , soil science , soil loss , geomorphology , geotechnical engineering , geography , ecology , cartography , machine learning , computer science , biology
A closed drainage basin representing a catchment for eroded sediment was studied to determine the amount of erosion since cultivation began, and to determine the spatial relationships of the erosion‐sedimentation process that had occurred during 145 yr of agriculture. Post‐settlement alluvium (PSA) thickness was easily determined in the field as light‐colored mineral soil overlying highly decomposed (sapric) organics in the depression. A detailed field study of the PSA, other geologic sediments, loess, and the original till surface in the watershed demonstrated a reduction in the original relief. The mass of PSA served as a measure of the amount of soil eroded from peripheral slopes. The long term average soil loss was > 26 Mg ha −1 yr −1 , which represented an average removal of over 24 cm of soil from the entire watershed in 145 yr. The maximum slope in the watershed was 5%. The loess thickness on the surrounding slopes was used as an indication of the spatial variation of erosion processes. Summit positions and convex slope shapes having divergent runoff had the most erosion while concave shapes with convergent runoff exhibited more sedimentation. These results are essentially opposite to those predicted by the Universal Soil Loss Equation (USLE). Accurate prediction models in the future should consider the dynamic aspects of erosion‐sedimentation on landscapes.