The study watershed is unique in that it is completely urbanized and generally void of natural watercourses. Storm water runoff is typically conveyed in an extensive network of existing storm drains, tunnels, and overland within the city streets. The hydrologic modeling approach was unique in that it implemented a finite element approach using the U.S. Army Corps of Engineers HEC-1 Flood Hydrograph Package. Basic hydrologic model input parameters were developed using GIS databases. The hydrologic model accounts for aerial reduction, flood irrigated properties, storm drain and tunnel systems, retention/detention basins, irrigation canal diversions, and street/freeway/railroad diversions. The hydrologic models developed for the study quantify multiple frequency events, including the 100-, 50-, 25-, 10-, and 2-year storms. The 100-year model was also evaluated for 6-hour and 24-hour duration storms. These hydrologic models are the basis of the upcoming City of Phoenix Downtown storm drain projects.
- 2-, 10-, 25-, 50- and 100-year storm prevention
Flood Control District of Maricopa and City of Phoenix