Preliminary Examination of Relationships between Catchment Characteristics and Volumes of Infrequent Large Floods.

摘要

Design floods are used to consider relevant hydrologic and economic factors in the evaluation of operation, or changes in operation, of flood damage mitigation. The design hydrograph, which relates flood volume and frequency in a catchment of concern, is commonly used to estimate design floods of various duration. Constructing a design hydrograph is accomplished using flood volumes, often extrapolated beyond observed records, from flood volume-duration-frequency curves. An assessment of the existence of coincident and similar frequency flood volume relationships, required to construct design hydrographs, was conducted using flood flow data from seven Pacific Northwest river catchments. These catchments were influenced minimally by engineered facilities or farming or sivicultural practices. Coincident occurrence of large return period flood volumes, for flood durations important to decision making, held true for all seven basins. Flood volume-frequency-duration for the largest two or three flood volumes is strongly related in three catchments, moderately related in three others, and unrelated in the seventh.