Volume-Duration-Frequencies for Ungaged Catchments in Texas

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Texas Water Resources Institute

This report summarizes results from studies to determine relationships among the volume, duration and frequencies of floods in ungaged catchments in Texas. Methodologies were adopted for determining flood volumes at unregulated, non-urban catchments. Separate methodologies were developed for small and large watersheds. Regression equations were developed for twelve regions to estimate flood volumes for different durations and recurrence intervals. "Window Test" was conducted to establish a methodology to separate small and large watersheds based on their response characteristics. Regional flood volume-duration-frequency equations were developed for 8 of the 12 regions. This report, which includes information from reports released earlier at the completion of individual phases, consists of two volumes. Volume I (titled Volume-Duration-Frequencies for Ungaged Catchments in Texas: Calculation of Regional Regression Equations) presents the regional regression equations developed, while Volume II (titled Volume-Duration-Frequencies Ungaged Catchments in Texas: Computations of Flood Volumes of Varying Durations and Frequencies for Catchments with Areas Greater than 300 Square Miles) lists the actual flood volumes computed for different duration- frequencies at all rural, unregulated sites that have at least 300 square miles of contributing drainage area.