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Title: VALIDATION OF WEPP 95.X DAILY EROSION SIMULATION

Author
item Kramer, Larry
item ALBERTS E EUGENE

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Abstract Only
Publication Acceptance Date: 6/23/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The USDA WEPP erosion simulation model, version 95.X, was used to simulate runoff and soil loss for a 24-yr period of moldboard plowing for primary tillage of corn. The only model parameter adjusted was one which allowed matching of simulated and observed crop grain yields. WEPP results were compared to observed event runoff and soil loss amounts obtained from paired experimental 88 mm**2 erosion plots on Mexico silt loam soil near Kingdom City, MO. Event results were analyzed by rough fallow, seed bed, rapid growth, reproduction and maturation, and residue crop stage periods. Results from the application of WEPP version 94.7 showed that during multiple soil loss event sequences resulting from periods of excessive runoff, simulated soil loss values were biased low for final events of the sequences compared to the corresponding observed event values. Also frequency analysis showed annual peak values for WEPP 94.7 simulated soil loss were generally greater than observed soil loss for return periods greater that 2-yr, thus indicating a bias for WEPP to predict excess soil loss for extreme events. Nearly 200 soil loss events were simulated and observed. However for WEPP 94.7, the number of events simulated in the residue crop stage was nearly 80% less than the number observed, whereas the number of simulated events in the crop growing periods was greater than observed. Refinements in WEPP version 95.X are expected to reduce these biases.