Comparison of soil erodibility factors in USLE, RUSLE2, EPIC and Dg models based on a Chinese soil erodibility database.

摘要

Soil erodibility (K-value) is a key parameter in erosion prediction and is important for conservation planning in the face of a rising need for protecting the limited land resources. This study investigated the predictive capability of the K-value estimated by Universal Soil Loss Equation (USLE), Revised Universal Soil Loss Equation (RUSLE), Erosion Productivity Impact Calculator (EPIC) and Dg models for different soil regions using a Chinese soil erodibility database covering 51 natural runoff plots. Model performance was evaluated using R2 (coefficient of determination), relative error (RE), Nash-Sutcliff efficiency (NSE) and P value (Mann-Whitney U test) statistics. The results showed that the existing four models overestimated almost all the K-values for the Chinese erodibility database, with most observed values concentrated in the range of 0.015-0.035. Without calibration, only the USLE and Dg models could be reliable and directly applied for the black soil region and the loess soil region, respectively. The Dg-OM model (R2=0.67, n=32) was established by the non-linear best fitting techniques of multiple regression. In the Dg-OM model, K-values accounted for the vibration in a combination of the D_g (geometric mean diameter) and OM (soil organic matter). NSE, R2 and the average RE was 0.94, 0.67 and 9.5% for the Dg-OM model's calibration based on the Chinese erodibility database; similar results were found for the validation process, with NSE of 0.93, R2 of 0.66 and average RE of 6.5%. The model performances showed that the Dg-OM model reached 'good' satisfactory level. Compared with the four existing erodibility models, the Dg-OM model permitted the best parameterization and accuracy, and was proved to be suitable for estimating soil erodibility values in China.Digital Object Identifier http://dx.doi.org/10.1080/09064710.2012.718358