Runoff simulation with eight different flow accumulation algorithms: Recommendations using a spatially distributed and open-source model

Flow accumulation algorithms (FAAs) predict the cumulative upstream drainage but each FAA generates a different map and this uncertainty still remains unsolved. This study makes advances in flow path research by testing 8 FAAs and analyzing the uncertainties of 15 simulations. The DR2-2013© SAGAv1.0 hydrological software is presented in a study carried out for two catchment lakes (NE Spain) over a 69-month test period. The best simulations were obtained with two single flow (Rho8 and Deterministic Infinity) and two multiple flow (Multiple Flow with threshold value and Triangular Multiple Flow) algorithms. Correlations between runoff depths and lake levels improved when the test period was split into wet and dry seasons. Correlations also improved with a one-month delay in response time and no delay in the large and small lakes. The DR2-2013© tool helped predict changes in lake volume and the highest model efficiencies were obtained with the multiple flow algorithms.