Columbia River Winter Operations Study

HEC-ResSim Modeling and Script Development
U.S. Army Corps of Engineers
Pacific Northwest

Introduction

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.

Scope

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:

1. Write a script that takes forecasted inflows and performs routing and simple reservoir operations to produce a projected stage at Vancouver, Washington.
2. Use the projected stage to determine the severity and timing of the flood.
3. Engage various reservoirs in the model to respond to a winter flood based on the severity and timing of the storm.
4. Verify that the scripts produce the behavior at each project that is expected given a forecasted winter flood event.

Challenge

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.

Solution/Result

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.

 

Photo: “Portland Summer Evening” by Stuart Seeger / CC BY 2.0