Unraveling hydroclimatic forces controlling the runoff coefficient trends in central Italy’s Upper Tiber Basin

Study region: This study refers to the Upper Tiber basin at the Ponte Nuovo outlet in central Italy. Study focus: This study aims at analyzing runoff coefficient (Rc) trends and connections with hydroclimatic parameters, namely (temperature (T), precipitation (P), soil water storage (SWS), and LULC (Land Use Land Cover) changes) using Mann-Kendall (MK) test and wavelet coherence analysis (WCA). New hydrological insights for the region: The results show a decreasing Rc over 1927–2020, coupled with increasing T and decreasing SWS based on seasonal MK test, and implications for water resource management in Central Italy. Results underscore the need for sustainable hydrological management paradigms to address challenges posed by scarcity of water resources under unpredictable changing climate. Rc-hydroclimatic parameters correlations through WCA revealed complex hydrological interactions. Precipitation exhibited insignificant and erratic patterns from 1950 to 1978, and while it established more significant correlations with Rc from 1990 to 2020, it remained moderately erratic. Conversely, weak correlation found against LULC changes, concurrently with strong positive but lagged correlation with SWS (1 month), and strong lagged (3–6 months) but negative correlation with T indicate the prevailing significance of hydroclimatic factors over LULC changes. These insights underscore the pivotal role of hydroclimatic factors in shaping regional water resources. Policymakers can harness these insights as a bedrock to develop effective strategies for water resources planning and climate change adaptation.