Effect of Rainfall Characteristics on Runoff and Water Erosion for Different Land Uses in a Tropical Semiarid Region

Abstract Rainfall intensity, duration, frequency and magnitude influence both runoff generation and sediment yield. In this study, 176 rainfall events over a five-year period were classified into four regimes based on rainfall depth, duration and 30-minute maximum intensity, using hierarchical cluster analysis in the semiarid region of Brazil. Rainfall Regimes were grouped from higher to lower rainfall depth, longer to shorter duration, and higher to lower I30. Rainfall regime impact on surface runoff and sediment yield was studied in three watersheds under different land use - native tropical dry forest, thinned tropical dry forest, and slash and burn followed by grass cultivation. Thinning of native dry tropical forest reduced surface runoff and sediment yield due to the protective effect of the well-developed herbaceous layer. Runoff generation in the three watersheds showed strong dependence on antecedent soil moisture and the type of rain. Rainfall depth was the major factor for highest sediment yields.