Abstract

Developing a simple and proper model that can accurately predict runoff generation for various locations is in strong demand. This study developed a simple model based on the interactive effects of rainfall intensity and soil physicochemical properties on runoff using a locally produced rainfall simulator. The drop velocity (DV) was calculated to be 8.101m/s and 2.443 m/s when operated at maximum and minimum intensity, respectively, and the performance test revealed the experimental coefficient of uniformity (CU) and rainfall intensity from the simulator to be 79.86 % at 31.79 mmhr-1 and 78.03 % at 16.08 mmhr-1 at maximum and minimum intensity respectively. Results showed that the soils were loamy sand, with clay having the lowest percentage between 3.55% - 4% and sand having the highest percentage between 78.4% - 80.1% on both plots. Runoff significantly correlated with pH(H20), nitrogen and rainfall intensity for vegetative plot (p < 0.001, R2 = 86.29%) while for bare plot, runoff significantly correlated with pH (KCl), Electrical Conductivity, Exchangeable Calcium, and rainfall intensity (p < 0.001, R2 = 92.39%). This result revealed that rainfall intensity and alkalinity are key factors influencing runoff in the study location.

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