Rainfall energy losses in presence of shallow overland flow

Kinetic energy of a rainfall event is often determined by its intensity. The actual kinetic energy imparted on a soil surface is generally less than the total value of kinetic energy of a rainfall event. This is because of the cushioning effect of the overland flow created by the rainfall event above the soil surface. The cushioning effect decreases the amount of splash erosion. Therefore, there is a potential risk of over prediction of splash erosion by an erosion prediction model that does not account for this effect. A logarithmic energy loss model that accounts for the depth of shallow overland flow, rainfall intensity and bed slope to estimate potential loss of kinetic energy is proposed. An experimental setup was established consisting of a multipurpose hydraulic tilting flume, of 2m length and 1.4m width. Five highly sensitive piezoelectric force transducers were mounted on the surface of the flume to measure the impact of the raindrops. Different slopes were represented in the experiment by tilting the flume in four different angles from 0 to 15 degrees. Responses received into the transducers in the form of voltage and in the tipping bucket rain gauges in the form of pulses were stored into a data logger. Data gathered were analysed to develop the proposed model. An encouraging value of the Nash-Sutcliffe efficiency statistic (E=0.90) signifies the potential application of the model in soil erosion research.