Summer monsoon precipitation patterns and their relationship to flood probabilities across Pakistan

Study region In Pakistan, the climate crisis manifests most dangerously through extreme monsoon precipitation and subsequent flooding. Study focus To quantify the relationship between summer monsoon precipitation and flood probability, the study establishes and applies Intensity-Duration-Frequency (IDF) and Quantile-Duration-Frequency (QDF) frameworks. These frameworks utilize ERA5 precipitation data and multi-source streamflow records from 1950 to 2024 to assess extreme events across Pakistan. New hydrological insights for the region Results reveal noticeable spatial variation in flood sensitivity across Pakistan. The northern mountainous regions exhibit the highest vulnerability to flooding, characterized by extreme precipitation magnitudes exceeding 25 mm/hr for 1-hr events and the highest streamflow elasticity (epsilon(1) up to 0.33 for 2-yrs and 0.35 for 100-yrs return periods), indicating that flood peaks increase proportionally with precipitation intensity. The Central and Eastern regions show moderate elasticity epsilon(1) up to 0.27 and 0.22, respectively. In contrast, the Southern region exhibits minimal flood probability/sensitivity (elasticity similar to 0.17), instead highlighting critical water scarcity. Flooding is primarily driven by short-duration (1-3 hrs) extreme summer monsoon precipitation exceeding 30 mm/hr in the Northern region and is characterized by a coherence between precipitation and streamflow peaks of more than 70%. The elasticity ratio epsilon(2), representing the alignment between storm duration and catchment response, is highest in the North (similar to 0.60) and lowest in the South (similar to 0.17), confirming the influence of terrain morphology on flood-generation efficiency. These findings highlight the critical need for region-specific flood risk strategies, including early warning systems in high-sensitivity Northern areas and water retention measures in arid Western regions of Pakistan.