Why Do Flood Warning Systems Work When They Should? (or not)

Flood warning systems are expected to work when big floods hit. By definition, big floods are rare which means a flood warning system may lay mostly quiet in the years, if not decades, between big events. Yet, despite lying dormant for extended periods, flood warning systems are expected to “wakeup” and perform flawlessly when called upon. When they do work when they should, why?

Following epic flooding in the 7000 square kilometer Chehalis River Basin in western Washington in 2007 and 2009, the Chehalis River Basin Flood Authority (CRBFA) commissioned the development of a flood warning system. After a dozen years of relative quiet, record flooding returned in January 2022. The flood warning system, agencies, and the public were ready.

Since its inception in 2010, the CRBFA staff and consultant team worked hard to appropriately maintain the system, update technologies, and provide incremental improvements each year. Most importantly, the team encouraged public engagement through webinars, news articles, flood preparedness meetings, stake holder awareness, frequent updates to the CRBFA board, and integration with the Chehalis Basin Strategy managed by the Governor’s Office of the Chehalis Basin.

This presentation highlights critical elements of the Chehalis River Basin flood warning system that are key to the on-going system success.