RIVERBED HEAT-CONDUCTION PREDICTION

Heat flux between river water and riverbed contributes significantly t o river water heat content and river temperature, especially in shallo w rivers. A numerical model of heat conduction in a riverbed was verif ied with detailed temperatures measurements in a riverbed. Three diffe rent methods, the heat budget method, the gradient method, and an inve rse method, were used alternatively for the estimation of the riverbed heat flux. Propagation of uncertainty in the riverbed temperature mod el was studied using a vector state space perturbation method. Output uncertainty was estimated by random perturbations of the effective the rmal conductivity from the main value. The coefficient of variation of effective thermal conductivity was 0.1. Temperatures and heat fluxes in the riverbed were affected by the uncertain thermal conductivity.