The utility of HEC-1 flood hydrograph package in distributed flow guided area drainage master plan discharges verification in a desert environment

Abstract

Flood control management and policies that formed the foundation of the Upper New River Area Drainage Master Plan Development in Phoenix, Arizona, USA, took into account engineering, environmental, landscape, social, and economic considerations. In this engineering-in-practice focused paper, the authors verify the accuracy of the existing condition 100-year, 24-hour rainfall event design discharges by superimposing them on the existing probabilistic discharge envelope curves derived for the region by various US Government agencies over the last five decades. The US Army Corps of Engineers' HEC-1 flood hydrograph package has been the choice of the local flood control district since 1987 when the first flood insurance study (FIS) was conducted on the catchment. The HEC-1 model results accorded well with those on the various discharge envelope curves originally derived from gauged catchments. The computed peak discharges were adjusted using the results from a two-dimensional FLO-2D hydraulic model to account for the existing flow breakout locations and man-made storage areas in the post-FIS in-channel sand and gravel mine pits. The approach was a novel and timely undertaking by the modellers in support of robust flood control alternatives development.