Dams
  Goldsborough Creek | Upper and Lower Baker Dams | Hawaii Dam Break Analysis | Piedra Liza Dam

Dam Break Analysis
Statewide, Hawaii

Tetra Tech, Inc. is currently under contract with the Honolulu District Corps of Engineers performing site visits and all necessary work for a dam break analysis and downstream inundation mapping. The work effort includes hydrologic analysis and modeling of the 100-year and PMF hydrographs, analysis of various dam failure scenarios, and inundation area mapping of the downstream area. Dams evaluated include the Waita Reservoir (Island of Kauai), Reservoir 24 (Island of Maui) and Piwai Reservoir (Island of Kauai) as an option.

The objective of this work is to conduct sufficient hydrologic and hydraulic analysis primarily through computer modeling to determine dam break floodplains below a selected list of regulated dams in the State of Hawaii. This work includes the use of GIS tools to process topographic data for both the hydrology and the hydraulic analyses. A detailed terrain model will be developed for the identified hazard area using current and new topographic data. Calibrated models will be developed using HEC-HMS, HEC-RAS, HEC-GeoRAS. The BREACH program will be used to determine the dam breach parameters in conjunction with applicable regression equations. The actual dam failure and downstream hydraulic analysis will be conducted using HEC-GeoRAS. The dam break failure scenarios that will be analyzed will be the 100-year, PMF, and “full pool sunny day”.  

Major Tasks include site visits, data collection, hydrologic analysis, hydraulic analysis and floodplain mapping.