by Jay Lund
The tweet below, shows slight (but still frightening) levee overtopping this week on Cache Creek, just north of Woodland, California. It also illustrates the combined operations of flood preparation and response, with a simultaneous floodplain evacuation order. Integrating a range of preparations and responses have made the Sacramento Valley much safer from floods.
One often hears, “If only we did X, we would solve this problem.” Alas, effective solutions are rarely so simple or reliable. Most robust solutions for problems involve a diverse and complementary portfolio of actions, developed over time. When a set of diverse actions are carefully crafted to work together, they often provide more effective, adaptable, and reliable performance, at less expense that a single solution.
The Sacramento Valley’s flood management system is a good example where a portfolio of actions has greatly reduced flood damages and deaths, with relatively little management expense and attention in a highly flood-prone region. This case also illustrates how the many individual flood management options presented in the table can be assembled into a diversified cost-effective strategy involving the many local, state, and federal parties concerned with floods.
Portfolio strategies usually include actions which work in different ways over different times. Flood management portfolios usually include actions that prevent flooding (such as levees) complemented by actions that reduce the need for more expensive flood prevention (such as flood evacuations). Actions which protect areas from flood waters (often structural actions) are distinguished from actions that reduce vulnerability to damage and death if flooding occurs. Levees, bypasses, and reservoirs are all designed and operated to support each other in the Sacramento Valley to reduce the extent of flooding. Floodplain land management and flood warnings and evacuations have greatly reduced the property and people exposed to flooding.
Because most floods occur and pass quickly, most flood management is in preparing for floods and flood recovery, rather than in response during actual floods. As with fire-fighting, elections, and war, flood management time is more than 99% preparation and recovery and less than 1% actions during flood events. Pre-flood preparations to contain floods (with levees, reservoirs, and bypasses), reduce flood damage potential (with evacuations, building codes, insurance, and floodplain zoning), and prepare for rapid flood operations and evacuations (with education, warnings, and training) are crucial. Making and coordinating investments, training, and education are all prominent before floods, making urgent flood operations more effective (and less panicked). Post-flood response also can reduce flood damages and help prepare for the next flood. There is always a next flood.
Portfolio solutions require overcoming some challenges, however. Because portfolio solutions involve a range of actions usually controlled by different authorities and groups, they require more social and political organization than single-action silver-bullet solutions. This can take time, motivation, and leadership to bring together. But such diversification of responsibility for implementing portfolio can help spread expenses and provide useful perspectives of attention to details and effectiveness. In flood management, local residents and land owners, local governments, regional governments, and state and federal agencies all specialize in different elements of regional flood management. This specialization helps lower costs, increase attention to detail, and diversify political support. This can lead to a mutually-reinforcing ecosystem of institutions that are collectively more effective at attending the problem and innovating than would a single larger bureaucracy.
It took decades for California’s Sacramento Valley to build its current flood management portfolio. Even so, some flood problems remain. Small towns and some rural industries remain vulnerable – and there is always vulnerability to bigger floods and infrastructure failures. There will always be residual flood risks, as flood solutions are never perfect or complete.
Flood problems also change as the economy, population, social expectations, and now climate change. We now see floodplains and flood bypasses are closely linked to California’s environmental solutions, bringing new objectives in our flood discussions. Portfolio solutions can often better incrementally adapt to change because of their supporting diversified institutional network and operational flexibility.
Successes with water problems (and other areas) often comes from developing or evolving portfolio solutions. An integrated range of institutions supports this management, mixing the advantages of centralized and decentralized governance and finance to make more effective and adaptable solutions at less expense. No single person or institution can usually solve such problems.
A series of blog post essays will explore the use and development of portfolio solutions for major water problems. Successes and challenges will be discussed, as well as the problem of coordinating portfolios of actions across problems – such as managing a common water infrastructure for floods, water supply, and ecosystems – which traditionally have separate solution portfolios.
California Department of Water Resources, Central Valley Flood Protection Plan, https://water.ca.gov/Programs/Flood-Management/Flood-Planning-and-Studies/Central-Valley-Flood-Protection-Plan
Gilbert F. White (1937), Notes on Flood Protection and Land-Use Planning, Journal of the American Institute of Planners, 3:3, 57-61, DOI: 10.1080/01944363708978728
Independent Forensic Team (2018). “Independent Forensic Team Report: Oroville Dam Spillway Incident”. January 5, (2018).
Jeffres, C.A.; Opperman, J.J.; Moyle, P.B. (2008), Ephemeral floodplain habitats provide best growth conditions for juvenile Chinook salmon in a California river. Environ. Biol. Fishes, 83, 449–458.
Kelley, R. (1989), Battling the Inland Sea; University of California Press: Berkeley, CA, USA.
Lund, J.R. (2012), “Flood Management in California,” Water, Vol. 4, pp. 157-169; doi:10.3390/w4010157.
Jay Lund is a Professor of Civil and Environmental Engineering at the University of California, Davis.
Options missed: http://www.dewindonepasstrenching.com 1 pass in levee wall up to 60 feet deep and multi-feet wide. This would instantly give levee’s the strength to avoid a collapse and no rodent issues.
NEAR Breach – What to do? http://nilex.com/products/bituminous-geomembrane-bgm-liners 1,000 year liners can help the erosion of levee as the water goes over the top.
Inflatable dams – These can quickly and easily be installed where needed and inflated with the WATER near by. Aquadam or DamItDams have great products that can be used to raise level up to 20 feet if needed. http://aquadam.net/
These fit well as detailed options under existing options in the table.
OK, Thanks. But the problem is these solutions are not on your list or any list that the agencies in charge look at. So, these options are not considered, tested or tried. Maybe an University should try and fix the issue with one of these solutions or one’s of their own. The agencies working these issues NOW are not do a good, job as you point out in your article.
You have some very detailed and proprietary options here that fit pretty well under the broader heading sin the table.
Thanks for the thought provoking discussion!
For readers interesting in better understanding the rich history within U.S. flood risk management, I highly recommend also downloading from the US Army Corps of Engineers the 1994 Galloway report, officially known as “Sharing the Challenge: Floodplain Management into the 21st Century.” Chaired by Gen. Gerald Galloway, the report is the Federal response to the 1993 Mississippi River Flood. It laid out a comprehensive vision for portfolio-based solutions. Galloway’s team built on Gilbert White’s 1937 paper, his 1945 dissertation “Human Adjustments to Floods”, and his later work as the flood risk management advisor to both Democratic and Republic Presidents.
I agree with your point that the need to overcome challenges is fundamentally about working together at land owner, local, regional, state, and federal levels. Innovative solutions have been around before Gilbert’s and Gerry’s time, but the critical component has been the alignment of ability to move forward of all levels of responsibility (owner to government) at the same time. Financial and legal issues can and have been worked through in the past. But willingness to work together on a portfolio of actions floods and ebbs much like our tides.
Perhaps one of the most inspirational parts of the 1994 Galloway report was a letter Gerry included in the report’s forward. Within that letter, an 11-year old vision named Elizabeth described her efforts to illustrate how a portfolio approach to flood management might protect her family via her science fair. As a science fair judge, I’ve had the pleasure of judging Elizabeth’s California-based contemporaries work through similar projects (reaching similar conclusions) and find hope that the challenge in flood management is not due to a lack of imagination. Those of you interested in seeing first hand one-example of a portfolio of physical improvements should check out the West Sacramento setback levee and the nearby Yolo Bypass. Together they keep dozens of communities safe, while addressing multiple water management issues.
Excellent observations. Gilbert White was a major instigator of portfolio solutions in flood management.
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