Space-Time Variability of Maximum Daily Rainfall in Piura River Basin in Peru Related to El Niño Occurrence

Abstract

This study analyzes hydrometeorological data (1950–2023) to examine the signatures of El Niño and La Niña events and assess their impact on rainfall distribution in the Piura Region, Peru. Using data from 23 stations, high-resolution gridded rainfall datasets (PISCO), and oceanic–atmospheric indices we investigated the frequency, intensity, and spatial variability of these events in the Piura River Basin (PRB). Return periods for very strong El Niño and La Niña events are 25 and 19 years, respectively, compared to 2 years for neutral conditions. Over the past 30 years, the recurrence of Coastal El Niño has significantly increased. This increased frequency contributes to the global rise in El Niño events, reducing the return period for very strong events from 5.2 to 3.4 years. This rise correlates with an increase in maximum daily precipitation across the basin centered in the middle PRB during El Niño years. Future rainfall projections, based on 20 CMIP6 GCMs under SSP2-4.5 and SSP5-8.5 scenarios, suggest continued intensification of rainfall events. These findings highlight the necessity of incorporating El Niño variability into infrastructure design, water resource management, and climate adaptation strategies to mitigate the impacts of these increasingly frequent and severe events in the PRB.