Floodplains for the Future

Posted: 12.05.2017

This past years flooding in Houston and other parts of the world is a reminder of the great damages that floods cause when the defenses of an urban area are overwhelmed.   However, these floods are a stark reminder of the increasing vulnerability of urban areas across the world and the need for comprehensive strategies to reduce risk.  The evidence is clear that that floodplains managed for multiple services can reduce flood risk for many people while also promoting a range of other benefits, including increased biodiversity.

FP book Opperman Moyle et al floodplains (3).jpg

Unfortunately, climate change models tell us that floods will become bigger and more frequent in the future because warmer oceans will create bigger storms over wider areas.  For thousands of years, the general approach to handling floods has been to contain them with walls, levees, and dams, because people have wanted safe access to rich floodplain soils for farming and flat land for cities.  Responses to flooding have generally been couched in terms of fighting or controlling floods, at huge cost and occasional massive failures.  Today, the emphasis is slowly changing to flood management, where “green infrastructure”, such as flood bypass systems, not only reduces flood risks but creates habitat for fish and wildlife, supports farming, and provides open space for recreation. 

We think the world needs a lot more such green infrastructure to meet the forecasted challenges and to support floodplain ecosystems that can also function for conservation, farming and recreation. Engineered floodplains are a prime opportunity for multi-benefit outcomes. We have documented this trend, and reasons why green infrastructure works so well, in a new book. It is called “Floodplains: Processes and Management for Ecosystem Services”, published by University of California Press.

Our focus is reconciliation ecology, the science of integrating habitat for wild plants and animals into landscapes dominated by people. The book is based on our many years of studying floodplains in California, which is a leader in using floodplains for flood management.  But we also venture to other regions, especially Europe, Australia, and Asia, for new insights.   Towards the end, we provide 15 maxims to guide flood management such as “A bigger flood is always possible than the biggest experienced so far.”   We end with the following statement:

“We take heart from the huge flocks of migratory white geese and black ibis that congregate annually on California floodplains and from knowing that, beneath the floodwaters, juvenile salmon are swimming, feeding, and growing among cottonwoods and rice stalks, before heading out to sea. We can envision greatly expanded floodplains that are centerpieces of many regions, protecting people but also featuring wildlands, wildlife, and floodplain-friendly agriculture. Connectivity among floodplains, people and wild creatures is within reach, as is a future in which people work with natural processes rather than continually fighting them.” (p. 218).

Peter Moyle, Jeff Opperman, Amber Manfree, Eric Larson, Joan Florsheim