Despite reticence in Washington, D.C. about the term “climate change” (see yesterday’s blog post on this topic), there is plenty of discussion in the media and in scientific circles about whether intense, off-the-charts storms like Hurricane Harvey are the result of, or are associated with, climate change. Unfortunately, we are unlikely to see a widely agreed-upon answer to that question (at least in political circles) in the near future. The good news is that the flood management community doesn’t need to have a precise answer to that question in order to consider how to deal with the uncertainty associated with changes in climate that scientists are predicting over the next few decades.

California has actually been thinking about this question for a while.  We hinted at this topic on our blog back in 2016 in the context of how California responded to catastrophic flooding in 1997.  It was after Hurricane Katrina and the failed levee system that devastated New Orleans that California got very serious, very quickly, about investing in its flood control system.

We left that blog post with the following teaser:

“How do you plan for a future system of facilities, the rehabilitation of which is very expensive and time-consuming, in the face of anticipated changes in precipitation patterns that we do not fully understand today?”

Here’s how California answered that question:

  • Flexibility – the Central Valley Flood Protection Plan, which was initially adopted in 2012 but a 2017 update was just adopted this summer, incorporates flexibility and resiliency into future changes and management of the flood protection system.  For example, projects that expand river channels through setback levees or (something else) will be prioritized in order to accommodate the increased flood flows anticipated in the future.  A more flexible and resilient system can work for a range of circumstances associated with changing weather patterns.
  • Land use incentives – as part of the legislative effort to address flood risk in 2007, the California Legislature passed a law tying land use decisions in the Central Valley (like approving new development) to flood protection, with the eventual result that no new development may be approved where sufficient flood protection (i.e., to a 200-year level in urban areas) standard is not in place.
  • Awareness – with the understanding that flood risks can never be reduced to zero, the Plan incorporates a robust flood risk awareness campaign to limit exposure of life and property to flooding over time.

The Central Valley Flood Protection Plan calls for an investment of $17 to $21 billion over thirty years, which is way more than California has ever spent on flood control.  But spending that amount of money only makes sense if the work is intended to make the system as resilient as possible given the uncertainty in climate that we are already experiencing.

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