The Columbia River system, lifeblood of the Pacific Northwest, is large and complex. A 1964 treaty between the United States and Canada regulates hydropower and flood control within the basin. An HEC-ResSim reservoir model has been developed by the U.S. Army Corps of Engineers (USACE) to study how the system will be impacted by the continuation or termination of the treaty in coming years. Given the size and complexity of the basin, USACE identified several “mini-studies” to incorporate and test in their model. One of these studies included writing and implementing code that would simulate proposed winter flood operations.
Hansen, Allen & Luce teamed with WEST Consultants to assist USACE in completing the winter operations mini-study. The project required developing complex scripts that were added and tested in the existing ResSim model. The scope included the following tasks:
The challenges associated with this project included the complexity required in the scripts to achieve the desired reservoir operations. Site-specific operations required custom code for almost all projects. The scripts also had to be adjusted to produce consistent results even though the hydrology tended to vary widely.
Main length: 1,270 miles
Watershed area: 259,000 square miles
Flow during 1964 and 1996 flood events: Over 1,000,000 cubic feet per second
The scripts were tested on two historical winter flood events in 1964 and 1996, when modeling showed as much as a five-foot reduction in stage at Vancouver. In both cases the model performed as expected and showed a reduced stage relative to the projected stage. The modeling effort and development of the scripts demonstrated the value of incorporating the proposed winter flood operations. The proposed changes could reduce flood damages from winter storm events.