Accuracy assessment of WEPP-based erosion models on three small, harvested and burned forest watersheds
Covert, S.A. 2003.
Accuracy assessment of WEPP-based erosion models on three small, harvested and burned forest watersheds.
Master of Science Thesis.
Moscow, ID: University of Idaho College of Graduate Studies.
Forest Resources.
54 p.
Keywords: GeoWEPP, erosion models, forested watersheds, WEPP
Links:
PDF [498 KB]
Abstract:
This study assesses the accuracy of GeoWEPP model (Geospatial Water Erosion
Prediction Project) and a modified version of WEPP for forest soils. Three small
watersheds (2-9 ha) in the Interior Northwest were monitored for several years following
timber harvest and prescribed fires. Observed site factors of climate variables, percent
ground cover and soil erodibility values, along with digital slope data were used to drive
the models. The GeoWEPP and WEPP model predictions of runoff and sediment yield
were compared to observed yearly totals from each watershed. Monthly totals were also
compared the results of the modified version of WEPP. The yearly results showed that
GeoWEPP under-predicts runoff and sediment and the results were not acceptable at a 90
percent confidence interval. The same data was tested with the modified version of
WEPP containing modified algorithms for deep percolation and subsurface lateral flow
intended to better represent forest hydrology. This modified version of the WEPP model
showed improvements to yearly predictions of runoff and sediment over the GeoWEPP
model and generated acceptable results of runoff and sediment. Monthly values of runoff
and sediment yield generated by the modified WEPP generated acceptable results
compared to the observed monthly values. The GeoWEPP model has the potential to
model erosion with the incorporation of digital elevation data, but lacks the ability to
accurately represent forest hydrology. The incorporation of a WEPP algorithm that
represent forest soils more realistically would improve the results of GeoWEPP
predictions.
Moscow FSL publication no. 2003n
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