Hydrograph Time Parameters for Flatland Watersheds

Abstract

Available procedures for estimating storm hydrograph time parameters performed poorly in applications on low-gradient drainage systems of the Coastal Plain and Flatwoods regions of the southeastern United States. Existing empirical relationships generally underpredicted observed hydrograph time parameters on nine Coastal Plain and Flatwoods watersheds, with the standard error of estimate ranging from 63 to 132% of observed means. Hydrograph time parameters from flatland study areas were related to watershed physical characteristic and geomorphic data. The simple parameter, length of main channel, proved superior to all other simple or complex watershed characteristics for explaining observed variations in watershed time-of-concentration and hydrograph time-to-peak. Simple empirical relationships developed for estimating hydrograph time parameters for flatland areas provide needed information for watershed scale hydrologic design and environmental resource modeling applications on low-gradient drainage basins similar to those of the coastal regions of the southeastern United States.