Evaluation of Suitable Rainfall Erosivity Factors for the Semi-Arid Region of Kenya

Abstract

Regression analysis of 28 erosivity factors with soil loss from bare fallow plots was done to ascertain the best erosivity factor for the semi-arid region of Kenya. The El30, defined as the product of the rainstorm's kinetic energy and its maximum 30-minute intensity, emerged as the best erosivity factor having a correlation coefficient of 0.80 and a mean annual cumulative value of 154.9 MJ cm ha-¹ h-1. Al30, 130, and A erosivity factors, defined as the product of the rainstorm's rainfall amount and its maximum 30-minute intensity, the storm's maximum 30-minute intensity, and the storm's total rainfall amount respectively, which are much simpler to compute than El30, were shown to be predictors of sou loss with a decreasing accuracy. They gave correlations with soil loss of 0.79, 0.72. and 0.57 respectively and had simple linear relationships with El30 having correlation coefficient values of 0.99, 0.83, and 0.80 respectively. It was therefore concluded that excellent estimates of El30 and good estimates of soil loss can be made using Ai30. The single parameters 130 and A, although perhaps better than others, must be considered appreciably less accurate in soil loss prediction than their products.