Arequipa, the second most important city in Peru, suffers every year from floods on the banks of the streams of the streams that enter the city and flow into the Chili River, triggered by short- lived but intense rainfall. High intensity. As the sediment load increases and becomes thicker, the flow becomes non-Newtonian, a catastrophic geological hazard in regions with arid or semi-arid climates, such as the city of Arequipa. A situation that is aggravated by little or no urban planning, since in the last 20 years extreme storms have become more and more frequent due to climate change. This study presents the results of the occurrence of mud and debris flows due to extreme rainfall. For this, extreme precipitation thresholds were generated for their characterization and to determine the danger of an adverse meteorological phenomenon, predicted or in development. The precipitation time series from the La Pampilla station of the SENAMHI (National Service of Meteorology and Hydrology of Peru) with a record of 42 years (1981–2022) was used to obtain flood hydrographs with the HEC—HMS model considering a profile SCS-II type storm. The O'Brien Equation (Quadratic) rheological model was used for the event that occurred in 2020, then the hydraulic model was calibrated with the new non- Newtonian characteristics of HEC–RAS 6.4. Finally, cartographic maps were prepared in QGIS that allow the evaluation of flood danger zones in the Los Incas torrent of the city of Arequipa, to contribute to the evaluation of disaster risks in an adequate and timely manner.