TITLE:
Assessment of Various Empirical Soil Loss Estimation Equations in Arid Regions
AUTHORS:
Mahmoud M. Ahmed, Ayman G. Awadallah, Nabil A. Awadallah, Wael T. Ahmed
KEYWORDS:
Soil Erosion, RUSLE, R-Factor, Arid Region, Arabian Peninsula
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.10 No.1,
January
18,
2022
ABSTRACT: One of the most commonly used equations to estimate soil erosion is the
revised universal soil loss equation (RUSLE). Based on the early approach developed
by the Soil Conservation Service of USA, the rainfall erosivity factor
(R-factor) in the RUSLE equation requires sub-daily rainfall data, which is
usually not available. Other empirical equations estimate R-factor based on
available rainfall data like annual and monthly rainfall data. In arid regions
such as the Arabian Peninsula, several studies estimated the R-factor based on
these empirical equations without calibration. We propose in this paper to
assess the applicability of some of these empirical equations against R-factor
values calculated using as a reference the RUSLE approach. For this data, data from
104 stations with sub-daily rainfall was collected. The reference R-factor was calculated for the 104 stations. The results of seven empirical equations were
tested against the reference R-factor. Most of the tested equations
significantly underestimated the R-factor. Furthermore, the obtained RMSE and
MAE values were almost as high as the average R-factor, with MAPE exceeding
100%. Therefore, it is recommended not to apply these equations in arid
regions. A recalibration of the form of equation that gave the best results,
gave an RMSE of 280 (Mj·mm/(ha·hr)) and the MAPE dropped to 47.6%.