Flood discharge estimation in a small mountain stream: methodological review and application in the Montardit basin (Spanish Central Pyrenees)

Abstract

This paper is focused on the combination of historical, palaeoflood and instrumental records applied to estimate magnitude and frequency of floods in a high-gradient, small catchment in the Spanish Central Pyrenees: the Montardit basin, 15,2 km2. Historical data corresponding to past floods occurring in the Montardit drainage basin during the 20th Century were compiled through interviews with inhabitants of villages located in the basin. The largest floods of the stream were recorded in November 1907, in August 1924 and in 1944. The results of the methods applied in this study suggest that for high-frequency, low-magnitude events there is a good correlation between peak discharges yielded by palaeoflood reconstruction (7 to 46 m3 s-1) and those estimated through rainfall-runoff modelling (8 to 46 m3 s-1). In contrast, high magnitude events show a higher historical frequency than that provided by rainfallrunoff methods.