Basin Response Time: Potential Hydrologic Basin Handprintby John Henz,
Abstract: Hydrologic lead time is an important factor in many water resources engineering applications. The determination of the response time of a watershed to runoff-producing rainfall is the focus of this paper. The paper tests the hypothesis that a watershed responds similarly to rainfall of various temporal distributions in a manner unique to that basin. Simply put, each basin has a unique handprint of physical characteristics resulting in a relatively uniform response time regardless of the rainfall distribution and resulting runoff volume. An HEC-1 basin model is executed using several different rainfall distributions. The lag time from the occurrence of the highest rainfall intensity to the time of the peak discharge is computed for each model. Those results indicate the handprint basin response drives the hydrologic lag time and is virtually uniform for all distributions. A historic flood-producing rainfall event is reconstructed from radar data to estimate the rainfall point values, spatial and temporal distribution and those data are input into an HEC-1 watershed model. The results indicate similar basin response times associated with the historic event as compared to the basin response time derived from the HEC-1 models using hypothetical rainfall distributions, thus supporting the original watershed handprint hypothesis.
Subject Headings: Basins | Rain water | Watersheds | Hydrology | Hydrologic models | Data processing | Floods | Water resources
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