Using continuous simulation for the meteorological characterization of floods in a high-relief peri-urban catchment in central Chile

Abstract

Flood forecasting using meteorological information is essential in small high-relief catchments 34 with short response times, in which early warning cannot rely solely on real time in-situ 35 monitoring. Moreover, the response of these catchments can be driven by both precipitation 36 and temperature, which controls the freezing level elevation and size of the contributing area. 37 This paper proposes and applies a meteorological characterization of floods using daily 38 precipitation and temperature data in a small high-relief catchment in central Chile. For this 39 purpose, hourly disaggregated daily temperature and rainfall records are used to run a 40 continuous hydrologic model calibrated using extreme discharges. Mapping plots relating daily 41 precipitation and minimum temperatures (Tmin) with peak flows are produced and used in their 42 characterization, the identification of threshold values explaining significant floods, and the 43 assessment of driving factors’ exceptionality. Significant floods are explained by extreme 44 precipitation and rather high Tmin values. They are typically produced by daily rainfall larger 45 than 70 mm if 5°C < Tmin ≤ 10°C, and 60 mm if Tmin > 10 °C, with 80% of these floods occurring 46 under wet antecedent. Our approach facilitates an early estimation of expected peak flows 47 given a meteorological forecast of daily precipitation and temperatures. 48 49 Keywords: Flood, Andean catchment, continuous simulation, freezing level, precipitation, 50 Chile