In the wake of the Oso landslide, the King County Flood Control District wants to use advances in technology to dramatically improve the collection and use of landslide data. The district’s Executive Committee is now seeking a resolution calling for an update to King County’s river basin landslide hazard mapping. By mapping landslide hazards in light of flood and channel migration hazards, the district will be better prepared to act to reduce risks to people, property, and critical infrastructure.
Having accurate data is vital to land use decisions, says Flood District Supervisor Kathy Lambert, whose district includes the Snoqualmie River basin. Old maps used 1990s technology. Now, LiDAR (Light Detection and Ranging) will provide the maximum benefit and more safety to the taxpayers, she says. New landslide data collection technology will enable the county to be better prepared for any future flooding or landslides.
The district will provide approximately $200,000 in 2014 for these updates, with additional funds coming through 2016. The work in 2014 includes landslide hazard characterization along major rivers and significant tributaries, as well as listing high-risk sites where landslide and floodplain hazards intersect. Preliminary maps along major rivers and significant tributaries will be available by October, and potential high-risk sites will be identified by December of this year.
Further mapping improvements will follow through July 2016, including identification of different landslide hazard types, public safety consequences, historically active sites, landslide run-out zones, areas of moderate and severe channel migration, and areas at risk for debris dam formation that could lead to upstream flooding.
The King County Flood Control District will fund more than $1.4 million for the two-year project. The King County Water and Land Resources Division will conduct the mapping study, under agreement with the District.
The resolution was adopted by the Flood Control District Executive Committee at its May 19 meeting and is awaiting final action by the full Flood Control District Board of Supervisors.