A portable rainfall simulator to evaluate the factors affecting soil erosion in the northwestern coastal zone of Egypt

Abstract

Soil erosion and the resulting sedimentation constitute major natural hazards that increase land degradation in the Mediterranean region. Understanding the behavior of soil erosion is of particular importance to control the degradation of productive soils. Therefore, a portable field rainfall simulator was designed to provide rainfall intensities in the range of 14 to 80 mm h−1. The simulator was tested in terms of Christiansen uniformity coefficients that ranged from 89 to 94% for the three full-jet nozzles used in this study, with median diameters ranged from 0.836 to 2.113 mm, showing an appropriate degree of accuracy. Furthermore, kinetic energy values ranged from 12.7 to 18.9 J m−2 mm−1, showing similarity to the natural rainfall occurs in the Mediterranean regions under conditions of low rainfall intensity. The applicability of the rainfall simulator in the dynamic processes of erosion characteristics was investigated in the northwestern coastal zone of Egypt. Five rainfall intensities (14, 21, 30, 36, and 45 mm h−1) were evaluated in three repetitions at three uncultivated sites having slope gradients of 5, 9, and 12%, forming 45 simulated rainfalls. The changes of sediment yield and runoff rate for the 45 simulated rainfalls were quantified. Altogether, the results indicated that runoff and sediment yield rates were substantially different between the rainfall intensities of 14 and 45 mm h−1 than those obtained between any other pairs of intensities under all soil gradients. Summing up the findings, the proposed rainfall simulator in this study can be used in future soil erosion studies.