Event-Scale Limits of Reservoir Flood Moderation: Peak Attenuation, Storage Saturation, and Capacity Size-Dependent Constraints Across India

Reservoir regulation reshapes high-flow dynamics, yet the event-scale limits of flood moderation remain poorly quantified at national scales. We develop a framework to compare naturalized (NAT) and regulated (DAM) high-flow responses for 223 Indian reservoirs by coupling Noah-MP runoff with vector-based mizuRoute routing (2000–2022). High-flow events are identified using scenario-specific P99 thresholds and evaluated at the inflow peak (T) and the subsequent recession day (T+1) to quantify peak attenuation and the storage states that determine remaining flood buffer. Reservoirs reduce peak magnitudes relative to NAT conditions across all storage classes, from large (>1,000 MCM) to small (