This investigation is a study of the spatial propagation of a flood through the execution of two processes integrated into Geographic Information Systems to produce maps of potential flood zones. Based on Multicriteria Assessment (MCDA) techniques, the Analytical Hierarchy Process (AHP) is used to identify areas with different potential degrees of flooding, and the hydrodynamic behavior of the extension is analyzed in terms of flooding in relation to different maximum flows, using the Nays2D solver of the iRIC software. For MCDA, four essential parameters were used for the evaluation of flood zones in the middle and lower course of the Acha–Arica: land use, elevation, slope of the land and distance to the river were used for the establishment of potential zoning. While photogrammetry procedures and a high-resolution Digital Elevation Model, together with base calculation conditions such as roughness, edge, discharge and time, were used for the hydrodynamic simulation of flooding for four different maximum flows of 42, 57, 84 and 114 m3/s. The results indicate that the AHP technique allows quite a coherent prediction of flood zones to be made with a limited amount of data. Hydrodynamic simulation with Nays2D allowed a simulated graphic representation of the extension to be obtained that reflects conditions very close to the actual conditions in which these events take place. Validation was performed by comparing the results with each other and with other sources of documentary records which showed high similarities between flood zones obtained. Graphical abstract: [Figure not available: see fulltext.].