The risk of flooding in cities near riverbeds is a latent concern, especially during the rainy season. A specific case is that of Misantla, located in the State of Veracruz-Mexico, where floods have already caused social and economic damages. For flood prevention, this study proposes a digital methodology based on specialized ArcGIS, HEC-RAS and HEC-GeoRAS software, taking as a case study the urban areas located in mountainous zones of Misantla, Veracruz; likewise, hydrodynamic models supported by field studies and the use of geographic information systems (GIS) were used to know the vulnerable areas. The simulation shows the probable flood zones and the maximum depth levels that flows can reach in extraordinary rainfall events, which is an important element for risk assessment. By forecasting flooding areas, the spatial resolutions used also have a direct impact on mitigating damages caused by flooding. The study results in a risk map showing the sectors of the population most vulnerable to the problem of flooding and information for the design of protection works. In the city of Misantla, the case of this study, the simulated risk map shows that 57.3% of the surface area of the city, particularly the downtown area, is at risk of flooding.