Method for measuring velocity of shallow water flow for soil erosion with an electrolyte tracer

Measurement of the velocity of shallow water flow on a hill slope is of great importance in soil erosion studies. Electrolyte tracers have been tried to estimate mean velocity of water flow with the velocity of the leading edge of the solute propagation multiplied with a somewhat arbitrary correction factor. In this study, an analytical solution of solute (tracer) transport was formulated to serve as the mathematical foundation for measuring shallow water flow velocity. To estimate the flow velocity, a procedure was advanced. In the procedures, the analytical solution is fitted with the measured propagation curve and given the ‘the least square’ estimation of velocity. A detailed mathematical description is outlined for this purpose. Experimental results are given to show the feasibility of the method, including the analytical solution and the estimation procedures. This study provides the theoretical foundation for measuring the velocity of shallow water flow and for studies of overland solute transport.