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Implementation of the CAESAR-Lisflood Cellular Automated Landscape Evolution Model to Determine Possible Flood Areas in the Portoviejo River Sub-basin, Coastal Ecuador

Abstract:

In the Portoviejo canton of the province of Manabí of coastal Ecuador, floods have historically occurred as a result of extreme rainfall events and the overflow of the Portoviejo River. Nowadays, hydrodynamic models constitute a tool that allows simulating the flow of water in hydrographic basins. The zones with the possibility of flooding at different return periods were determined in the Colón parish of the Portoviejo canton using the CAESAR-Lisflood two-dimensional model in its two modes, being the Catchment and Reach Mode. The inputs used for the simulation were rainfall and flow data at different return periods (historical and probable maximum) as well as the size of the sediments that were obtained from granulometric analysis by sieving and a Digital Elevation Model of ALOS PALSAR with a resolution of 24.5 m and were later compared to HEC-RAS. With the one-factor ANOVA statistical technique, it was determined that there are no significant differences between the means of the affected areas and flow depths. The flood hazard analysis was performed on the buildings of Colón, considering two main factors. The first has been the probability of occurrence depending on the return period (10, 25, 50, 100 and 500 years), where the greater the return period, the less probability of occurrence, while the second has been the intensity that is classified as low, medium and high depending on the depth of the water flow, when educational institutions, health centers and homes were the buildings of interest to analyze the medium and high hazard.