Ecological Risk Assessment of Storm-Flood Processes in Shallow Urban Lakes Based on Resilience Theory

Urban shallow lakes are sentinel ecosystems whose stability is increasingly threatened by acute, sediment-laden storm floods. While chronic nutrient loading has been extensively studied, rapid risk assessment tools for short-pulse disturbances are still missing. Our aim was to develop a resilience-based, process-linked framework that couples depth-averaged hydrodynamics, advection-diffusion sediment transport and light-driven macrophyte habitat suitability to quantify hour-scale ecological risk and week-scale recovery. The ecological risk model integrates a depth-averaged hydrodynamic module, an advection–diffusion sediment transport routine, and species-specific light-suitability functions. We tested the model against field observations from Xinglong Lake (Chengdu, China) under 5-year and 50-year design storms. Ecological risk exhibited a clear west-to-east gradient. Under the 5-year storm, high-risk cells (complete inhibition) formed a narrow band at the eastern inlet and overlapped 82% with the SSC > 0.1 kg m−3 plume at 6 h; several western macrophyte beds returned to “suitable” status by 72 h. In contrast, the 50-year event pushed R > 0.9 over all macrophyte beds, with slow recovery after 192 h. Lake-scale risk peaked above 80% within 24 h for both return periods, but residual risk remained elevated in the 50-year scenario owing to the larger spatial footprint. The study provides a transferable early-warning tool for lake managers to decide when to trigger low-cost interventions and species-specific resilience rankings to guide targeted vegetation protection in shallow urban lakes worldwide.