Relationships between <i>n</i>‐Day Flood Volumes for Infrequent Large Floods

Abstract

Design floods of specified frequency are used to consider relevant hydrologic and economic factors in the evaluation of operation, or changes in operation, of flood‐damage mitigation facilities. The design flood hydrograph is constructed using flood volumes, often extrapolated beyond observed records, from flood‐volume‐duration‐frequency curves. We examined the foundation of this approach using flood flow data from seven Pacific Northwest river catchments. Nested occurrence of large‐return‐period flood volumes (i.e., 1‐day and