A simple conceptual model for coupled hydrological-hydraulic simulation in large basins with significant flood-propagation effects.

Abstract

This paper presents a model based on the combination of two simple conceptual sub-models, one for hydrology and one for hydraulics, which is capable of representing the discharges of large river basins with significant wave propagation effects in a lumped and efficient way, using a limited number of parameters (5-6 in the tested case). The model rests on the assumption that a large river basin can be represented as a rectangular region with a certain width-to-length ratio; the main river flows along the length of the rectangle and all the tributaries amount to a lateral uniform flow per unit width. The lateral inflows are represented by the lumped Logistic Equilibrium Model (LEM), while the flow evolution along the main river is given by the analytical solution to the Hayami equation with a uniform lateral inflow, as presented by Moussa (1996). The new model, has been successfully applied in the Tebicuary River at Villa Florida (Paraguay) with 20,400 km2 and compared with the Muskingum routing model, relying only on mean daily precipitations and potential evapotranspiration as input data. The proposed model is computationally efficient, easy to calibrate and open-source (Matlab version).