Flood Characterisation in Lithuanian Lowland Rivers Using a Peaks-over-Threshold Approach

This study advances research on river extreme events by applying the peaks-over-threshold (POT) approach to Lithuanian rivers. Extreme flow regimes were analysed for three rivers representing distinct hydrological regions and one large river. Results from the annual maximum series and three POT samples (POT1, POT2, and POT3) demonstrated the added value of the POT approach, as it enabled substantially more information on flood magnitude, frequency, and seasonality to be extracted from a single daily discharge time series. Trend analysis and seasonal flood frequency assessment revealed pronounced differences among rivers in regions with contrasting runoff-generation processes. Overall, the POT approach provided a more comprehensive characterisation of extreme flow behaviour, particularly for rivers susceptible to frequent flash flooding.