Flood analysis at different return times in the Mala River from the La Capilla hydrometric station using IBER and HEC-RAS (#163)

Authors

Auris Mariscal, Flor Jackelin Sorely

Diaz Mejia, Jose Miller

Carmona Arteaga, Abel

Ramos Orlandino, Carmela Cristhy

Abstract

The increase in global temperature is altering climate patterns, generating changes in watersheds that intensify phenomena such as floods. A notable case is the Mala River basin in Peru, which during the rainy season (December to April) faces extreme rainfall, especially due to the coastal Niño phenomenon. This has devastating consequences, such as crop damage and human loss. To evaluate the impact of these floods, an investigation was carried out with the objective of identifying flood-prone areas in the Mala River channel, downstream of the La Capilla hydrometric station, using two-dimensional models such as IBER and HEC-RAS. A Java-Script code was developed to obtain daily precipitation and temperature data from the ERA5 Land climate product. These data were integrated into the GR4J precipitation-runoff model, generating historical series of daily average flows from 1950 to 2024. Flood simulations were performed using the aforementioned models and compared with multispectral images. The results showed that the maximum instantaneous flow reached 235 m³/s for a return period of 10000 years. Furthermore, IBER showed larger flood areas than HEC-RAS in all evaluated return times, mainly affecting agricultural areas, which has a negative impact on the local economy and the quality of life of the population of the Mala district, especially in the lower part of the river.