Intra-event extreme rainfall characterization in the tropical Andes: a high-resolution weather radar approach

Introduction – Hydrological hazards, such as floods and landslides are frequently driven by extreme rainfall events (ERE). Thus, understanding the spatio-temporal patterns and intra-event behavior of these events is important for identifying vulnerable regions, improving early warning systems, and enhancing water management. Methods – This study aimed to analyze the spatio-temporal intra-event characteristics of ERE, using high-resolution (5min) weather radar data focusing on their internal structure and spatial distribution. The study was conducted in the headwaters of the Paute basin (2, 200–4, 400 m a.s.l.) in southern Ecuador. Based on three ERE classes, four intra-event rainfall features were analyzed: area, maximum rainfall, cohesion, and the locations of rainfall hotspots. Results – These features revealed different rainfall patterns for the three distinct rainfall classes. Class 1 is characterized by the highest rainfall peaks, concentrated between 12:00 and 19:00 (afternoon). Class 3 shows the lowest rainfall peaks. Class 2 shows the least cohesive rainfall core and a mixed behavior in features. Regarding the locations of rainfall hotspots, classes 1 and 2 show hotspots located at the catchment outlets and at the urban (City of Cuenca) areas of the sub-catchments (around 2, 500 m a.s.l), while those in class 3 are found at headwaters (above 3, 500 m a.s.l). Discussion – Identifying these rainfall characteristics and hotspot location provides a better understanding of extreme rainfall behavior in the tropical Andes, which enhances knowledge of hydrological processes, and improves flood forecasting.