Validation and sensitivity analysis of catchment runoff and erosion simulation technology (CREST): A GIS-assisted soil erosion model at watershed level

Abstract

Most erosion models have been developed based on a plot scale and have limited application to a watershed due to the differences in scale. In order to address this limitation, a GIS-assisted methodology for modeling soil erosion was developed using PCRaster to predict the rate of soil erosion at watershed level and identify the location of erosion prone areas. The GIS-assisted hydrology and erosion models were validated at Tanghaga Watershed using the observed values from previous experiment. The predicted peak rates, Q p, showed a highly significant relationship with the observed Q p, with an r 2 value of 0.75. For soil loss prediction, a significant relationship was also noted with an r 2 value of 0.74. Sensitivity analysis using four parameters was done. The model response was most sensitive to Manning's roughness coefficient (n) for Q p. An increase in n value from 0.02 to 0.13 resulted in a decrease of 546% in the predicted Q p. On the other hand, the predicted soil loss was most sensitive to the vegetative cover. Increasing the value of vegetative cover form 0.20 to 0.95 resulted in decrease of about 1,567%. The location of erosion hotspots was predicted within and along the tributary channels as well as in areas with low vegetative cover and steeper slope gradient. The capability of GIS-assisted model in predicting the location of erosion hotspots is a significant finding and this approach is a valuable tool in the formulation of a good watershed rehabilitation program.

Source or Periodical Title

Modelling for Environment's Sake: Proceedings of the 5th Biennial Conference of the International Environmental Modelling and Software Society, iEMSs 2010

Page

117-125

Document Type

Article

Subject

Catchment runoff and erosion simulation technology (CREST), Geographic information system, GIS-assisted modeling, PCRaster, Soil erosion

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