Modelling river ecosystem services in relation to discharge: The lower Jingjiang reach of the middle Yangtze River

Study region Lower Jingjiang, Middle Yangtze River, China. Study focus This study addresses the lack of dynamic process-based quantification of river ecosystem services (ES) assessment responses to flow variability. A dischargedriven framework links three-dimensional flow processes to ES delivery via proxybased models, simulating 19 ES potentials using 60-year flow data. We analyze ES dynamics, synergies, trade-offs, and bundles. New hydrological insights for the region Three ES response types emerge: decreasing (water conveyance), single-peaked (aesthetics, recreation), and increasing, with the latter further divided into threshold-triggered or saturating (e.g., flood mitigation, navigation) and continuous growth (e.g., water supply, nutrient cycling) subtypes. Heterogeneous responses form four synergistic bundles and two key trade-offs (sociohydrological vs. eco-hydrological bundles; downstream vs. local services). The models capture four distinct seasonal patterns of ES, reflecting differential flow dependency. Long-term simulations (1950–2013) show that while regulated flows stabilize overall service potentials, they also increase vulnerabilities in flow pulse-dependent supporting services, such as floodplain habitats and carbon storage, which rely on natural flow variability. Annual average ES potential correlates strongly with runoff via power-law, quadratic, or logarithmic functions, enabling predictions of service shifts under hydroclimatic change. This transferable framework supports adaptive water resource management by enabling scenario-based assessment of trade-offs between ecological integrity and human well-being.