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Validating erosion models using Cesium-137-derived spatial data


Soil erosion is a worldwide problem causing severe land degradation and surface water quality deterioration.  To effectively control soil erosion, distributed soil erosion models such as Water Erosion Prediction Project (WEPP) have been developed to predict spatial and temporal patterns of soil erosion.  However, all the spatially distributed erosion models have not yet been rigorously tested in the absence of spatial erosion data.  The lack of spatial soil erosion data has restricted the validation and application of spatially distributed erosion models.

In a recently published article in the Soil Science Society of American Journal, spatial distribution patterns of soil erosion by water on a 200 m long slope were estimated using the cesium-137 tracking technique. The author also thoroughly validated the WEPP model with the derived spatial data to diagnose the potential weakness in the configuration and functionality of the WEPP model with respect to the prediction of downslope erosion patterns.

The author reports that the spatial erosion patterns predicted by WEPP using 1-m default rill spacing (rill density) were vastly different from those estimated by the 137Cs technique. Soil erosion rates predicted by WEPP were overly sensitive to slope length increases. However, the two patterns were well matched if different rill spacings along the slope were used to run the WEPP model. 

The study demonstrates that rill spacing is a key input parameter for correctly simulating soil redistribution patterns with WEPP. Knowledge of rill density distribution along a hillslope is critical to satisfactorily predicting rates of soil erosion and sediment deposition on a hillslope.  The accurate prediction of spatial soil erosion patterns would afford a great opportunity for efficiently implementing precision soil conservation measures and effectively controlling soil erosion.

Read the full paper in SSSAJ. Free preview March 8 - March 15