Rainfall redistribution and warming drive future urban hydroclimatic intensification in Trnava, Slovakia

Urban areas are increasingly exposed to compound hydroclimatic pressures arising from intensified rainfall extremes, progressive warming and the growing sensitivity of urban drainage systems to short-duration rainfall events. However, future urban climate risk cannot be fully understood from changes in annual precipitation or temperature alone. This study investigates future urban hydroclimatic intensification in Trnava, Slovakia, using long-term meteorological observations, statistically downscaled CMIP6 climate projections, climate-extreme indices and a proposed Runoff-Generating Rainfall Index (RGRI). Future projections indicate that annual precipitation changes remain modest, whereas annual maximum 1-day and 5-day precipitation increase by approximately 37–41% and 17–19%, respectively. The RGRI further indicates greater concentration of annual precipitation in runoff-generating events, with significant increases in the contribution of very wet rainfall across all future scenarios. Concurrently, annual maximum air temperature increases from 35.9 °C to 38.6–38.7 °C, while warm-day and warm-night frequencies increase substantially relative to their historical thresholds, indicating both a warmer climate and more frequent warm extremes. Together, these findings highlight rainfall redistribution and progressive warming as key drivers of future urban hydroclimatic risk. The proposed framework provides a practical approach for hydroclimatic assessment and climate adaptation in medium-sized Central European cities with similar climatic and urban characteristics.