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Land degradation processes start with accelerated runoff and sediment delivery. In this study, rainfall-runoff induced sediment transport is investigated using data from an indoor laboratory experimental setup consisting of a rainfall simulator and an erosion flume. The data are analysed to develop empirical models using sediment discharge, slope, flow discharge, rainfall intensity and sediment size. Fine and medium sands are considered as bare soil in experiments. Four rainfall intensities (45, 65, 85 and 105mmh(-1)) are applied with combinations of lateral and longitudinal slopes of 5%, 10%, 15% and 20%. Eighty experiments are conducted. Flow is measured, and sediment within flow is separated and weighted. Experimental data are used for developing empirical models through multiple regression with parameters optimized by genetic algorithm. Results show that slope is the main contributing variable to the sediment transport over hillslopes. Accommodating variables among slope, rainfall intensity, flow discharge and median diameter of sediment as independent variables, one-variable, two-variable and four-variable models are developed considering also that higher number of parameters increases the performance of the model with higher cost of parameterization. Copyright (c) 2016 John Wiley & Sons, Ltd.