Comparative Evaluation of Conventional Infiltration Models under Tropical Rainforest (TRF) Conditions in South Western Nigeria

Abstract

Three commonly used expressions for modeling soil-water infiltration were evaluated for a tropical rainforest watershed in southwestern Nigeria under conditions of old, highly weathered soils and high rainfall intensities. The evaluation focused on the suitability of the expressions in assessing the decrease in infiltration opportunities that usually accompany deforestation. The equations were fitted into data spanning nine years obtained from infiltrometer experiments of the type where infiltration and runoff are generated onsite in response to single rainfall intensity without allowing for any modification due to inflow. The analysis revealed that soil-water infiltration into these tropical alfisols is better described by the Kostiakov’s model. Effects of duration of cultivation for different years following deforestation of the secondary vegetation were highlighted.