Large scale hydrologic and hydrodynamic modeling using limited data and a GIS based approach

In this paper, we present a large-scale hydrologic model with a full one-dimensional hydrodynamic module to calculate flow propagation on a complex river network. The model uses the full Saint–Venant equations and a simple floodplain storage model, and therefore is capable of simulating a wide range of fluvial processes such as flood wave delay and attenuation, backwater effects, flood inundation and its effects on flood waves. We present the model basic equations and GIS algorithms to extract model parameters from relatively limited data, which is globally available, such as the SRTM DEM. GIS based algorithms include the estimation of river width and depth using geomorphological relations, river cross section bottom level and floodplain geometry extracted from DEM, etc. We also show a case study on one of the major tributaries of the Amazon, the Purus River basin. A model validation using discharge and water level data shows that the model is capable of reproducing the main hydrological features of the Purus River basin. Also, realistic floodplain inundation maps were derived from the results of the model. Our main conclusion is that it is possible to employ full hydrodynamic models within large-scale hydrological models even using limited data for river geometry and floodplain characterization.