High Water Marks, life jackets, and other “innovations” as California leads in flood preparedness

Last Friday was a day of great for progress in the communication of residual flood risk in California as the High Water Mark from the February 19, 1986 flood was unveiled in Garcia Bend Park  in “the Pocket” area of Sacramento. The Pocket is a neighborhood in a deep floodplain protected by levees. The signs are part of the “Know Your Line” national initiative—a multi-agency effort, led by FEMA to post high water marks from past floods around the country and increase community awareness of flood risk.  California is one of 6 or so pilot communities across the US and a total of 9 or 10 markers have been posted in both Sacramento and Roseville.

High Water Mark from 1986 Flood, posted in Garcia Bend, Sacramento, California (the Pocket)

High Water Mark from 1986 Flood, posted in Garcia Bend, Sacramento, California (the Pocket)

The high water marker above reads, “Levees Can Fail: Be Aware. Be Prepared. Buy Flood Insurance.

We will always face the threat of flooding in Sacramento,” said Tamboor Ellen with the Sacramento District Corps of Engineers. Standing in front of a levee, her words were bold, honest, and very fitting with both the legislatures’ passage of the Central Valley Flood Protection Act in 2008 which requires flood risk notification in levee-protected areas, and with California’s Flood Preparedness Week, November 4-8, 2013.

While risk communication in all flood prone areas is critical, the High Water Mark in the Pocket area, is especially important because it acknowledges the risk of flooding in an area protected by a levee— areas where often a false sense of security develops. As previous studies have mentioned, the NFIP also requires no building restrictions, no flood insurance, or flood hazard disclosure on lands protected by levees—so long as the levees are accredited by FEMA.

Congresswoman Matsui poses under the new HWM, with staff from DWR, FEMA, the Corps, and the Cities of Roseville and Sacramento

Congresswoman Matsui poses under the new HWM, with staff from DWR, FEMA, the Corps, and the Cities of Roseville and Sacramento

The agencies behind California’s effort included: FEMA, the USGS, the US Army Corps of Engineers, the California Department of Water Resources (DWR), the City of Sacramento, and the City of Roseville.

Notably not present is the  flood-prone neighbor, the City of West Sacramento. The lack of participation may be because they recently assessed themselves to upgrade the levees that protect West Sacramento (in order to further develop it), and the City may find it therefore politically unacceptable to participate in a risk communication effort.  If this is the case, it is an unfortunate situation, yet not a unique predicament in this country. Many communities in levee-protected areas have incentive to keep flood risk quiet to maintain business interest and not “alarm” the public. I was once told by a local  district engineer, “Yea, but if we tell [the public] that they can still flood, despite the levee, they then start yelling at us and saying we’re not doing our job [protecting the levee].”

Political pressure, and fear of depressed home prices or lack of economic investments cause local officials to keep flood risk quiet.

Political pressure, and fear of depressed home prices or lack of economic investments cause local officials to keep flood risk quiet.

John Barry captures how this has been a particular struggle for cities even as early as the 1920s in his excellent book,  Rising Tide: the Great Mississippi Flood of 1927 and How it Changed America 

‘If New Orleans is ever flooded, the world will not know it unless there is some outside newspaper man there.  The newspapers of New Orleans have not told their people the actual situation. It’s business depression that’s feared. Many leaders of the town had much rather take a chance at loss of life and destruction of property than face the possibility of the grain markets slumping a couple of notches…”

Given the difficulty in communicating flood risk to the public, and the challenges that cities must face in wanting to maintain an attractive place to build and live, while ensuring their residents are as prepared as possible–I think we should applaud those communities that do take it on, and find out how to help others do the same. To learn about how other examples or about how your community can participate, please go to this link or contact me and I’ll put you in touch.

The rollout received a good crowd with some participation of the general public—though it seemed a majority of participants were members of the agencies themselves. The agencies staffed the booths to answer questions from the general public and pour water over a clever model to show how rivers cause damages to property.  All partners gave a speech including Congresswoman Doris Matsui, a champion of structural flood protection for the Sacramento area. Many speakers acknowledged the ease with which we forget the flood when we haven’t seen one in years.

Bill Edgar, President of the Central Valley Flood Protection Board, joked about how many flood control officials working for DWR (and the Corps of Engineers) live in the Pocket area (designated a “rescue” zone on the flood maps because it could flood very deeply and very rapidly without sufficient time for evacuation), —he said they all understand the risk and it gives them a vested interest in keeping it dry. You might wonder the same about the number of DWR employees living in Natomas.

The area in red is designated a "rescue zone" and yellow is an evacuation zone. Sacramento River is in blue on the left. Source: CIty of Sacramento  http://www.cityofsacramento.org/utilities/flood/Map_17b.pdf

The area in red is designated a “rescue zone” and yellow is an evacuation zone. Sacramento River is in blue on the left. Source: CIty of Sacramento http://www.cityofsacramento.org/utilities/flood/Map_17b.pdf

Keith Swanson of DWR grew up in the area and he said that what he remembers of the river was that “children were on one side of the levee—water was on the other side.” He recalled that before the 1986 flood, his family kept life jackets by the door.

Further thoughts?  Great event and many Kudos to the efforts at the USACE Sacramento District (namely Judy Soutiere) and DWR Flood Risk Communications team who were the driving forces behind this and other flood risk preparedness events throughout the region. I am also regularly inspired by the increasing number of state and federal officials who express that risk communication is high on their priority list. I hope high water marks get posted more frequently—and better yet, in residential neighborhoods–not just parks and fire stations– so that would-be homebuyers can get a sense of where they are buying a home and so that people in the neighborhood get daily reminders. This may not guarantee a different home-buying decision, but at least it will get more people in the community thinking about it.

Let’s all appreciate for a moment how the podium and speakers were positioned in front of an inflatable boat.

City Councilman and the other speakers sitting in front of inflatable rescue boat.

City Councilman and the other speakers sitting in front of inflatable rescue boat.

Maybe the high water mark sign should read: Levees will fail. Be prepared, buy a boat.

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Multiple Layers of Safety in the Netherlands and United States

Back on U.S. soil for nearly a year, I’ve linked up with another Dutch research institute to launch an initiative aimed at  comparing our two countries on one particular matter: implementing multiple layers of safety for improved flood risk management.


A comprehensive flood risk reduction plan would in theory reduce the frequency of floods, and it would also minimize the consequences once a flood occurs.

To do so requires implementing “Multiple Layers of Safety”  (the Lake Ponchartrain Basin Foundation has championed the similar “Multiple Lines of Defense”):

Dutch Concept of Multi-Layered Safety: (I) Prevention, (II) Protection, (III)

Dutch Concept of Multi-Layered Safety: (I) Prevention, (II) Protection, (III)

Layer 1:       Prevention

(addresses probability of flood through structural measures like dikes, levees, dams, storm surge barriers, bypasses, levee setbacks, etc).

Layer 2:      Protection

(addresses consequences of flood by insurance, limiting exposure through buyouts, zoning regulations, building codes and flood proofing, in-place protections, subway tunnel closures, etc)


Layer 3:      Preparedness

(addresses consequences of flood through evacuation, emergency response, and recovery).


Any flood risk reduction plan would require some level of investment in all three safety layers.

A flood risk management plan would require investment in managing both probability (prevention), and consequences  of flooding (protection, and preparation)

A flood risk management plan would require investment in managing both probability (prevention), and consequences of flooding (protection, and preparation)

Our research question: in a given flood-prone region in the United States and the Netherlands, what determines the relative level of investment in prevention, protection, and preparedness, and why?

  • From a purely risk-based perspective how would the relative size of each piece change with increasing/decreasing probabilities and consequences?
  •  What other factors at play would increase or decrease the relative size of each?
Flooded subway from Hurricane Sandy. source: inhabitat.com

Flooded subway from Hurricane Sandy. source: inhabitat.com

For example, how, where, and why will we rebuild the greater New York region? Will we build a storm surge barrier and go back to business as usual? Will we protect barrier islands? Elevate? Buy out? All of the above?

Dune nourishment for coastal protection. Source: Dutchwatersector.com

Dune nourishment for coastal protection. Source: Dutchwatersector.com

Why will the Netherlands indefinitely dredge the North Sea to nourish the coastal dunes no matter how costly it becomes?  Why don’t they have evacuations plans yet, and why do many Dutch engineers tend to scoff at communicating risk?

Why did Valmeyer relocate after the 1993 Mississippi Floods instead of build a levee or elevate houses?

Why after the risk-informed “Green Dot Map” leaked to the New Orleans public did many neighborhoods rebuild in place?

None of my questions above express a preference or an opinion. They’re just questions. Likely the answers are obvious to some you. The decisions behind the aforementioned examples may have been risk-based, though likely there were  also social, cultural, economic, or political factors at play, and those are what we want to elicit from the research effort.

Are there notable trends and preferences in the United States that are different from those in the Netherlands?  In the US, the National Flood Insurance Program has been identified as responsible for increasing risk.  In the Netherlands, there is no insurance program because none can afford to take on the risk (so the government does).

Subtle (or not so) differences in history, culture, political, and insurance systems have set the context for the two countries’ current state of flood risk.  The Netherlands may be arguably safer than the United States from a probability standpoint with 10,000-year protection on the Coast.  The United States may be arguably safer than the Netherlands from a consequences standpoint with experienced flood fighters and elevated houses.

Going forward, the goal of this study is to understand the rationale behind investing in  certain flood risk reduction measures and safety layers over others in attempt to identify barriers and opportunities to implementing multi-layered safety approaches in both countries.

There will likely be a survey and interviews later on to professionals in the field—ideally gathering opinions from people in all three sectors. Further, we will use case studies to illustrate themes highlighted in surveys and interviews.

We have some case studies selected already, but if you were involved in a particularly interesting (or boring) case, or want to participate in the study somehow, please comment on it here or send me a message with some of your thoughts.  For questions/comments on our proposed method, please send email.

Yesterday I was asked what commercial company is sponsoring this study and that answer is: none. This effort is funded through Unesco-IHE, and was developed by myself and my research partner after my year as a Fulbright fellow. We are very interested in applications of this topic in both countries.

Jessica (dot) ludy (at) gmail (dot) com.

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From the Outside Looking In(to the Corps)…

In many fields, organizations evaluate or audit themselves to improve the way they operate. Because it is difficult to critically analyze from within, such an evaluation often requires going outside the institute (and sometimes the country)  to find one who can shed light on the embedded norms, assumptions, methods, protocols, values, and policies that have been in practice for years. A view from the outside can further offer new perspectives and fresh ideas going forward. This process arguably could not be more important than in the field of flood safety.

Old windmill in Noord Holland. Image: Jessica Ludy 2012

At the end of May, I had the opportunity to participate in such an examination of  two old and very important institutions in the Netherlands and the United States.

I want to share a post about this because prior to last year, I knew only that the Army Corps of Engineers and the Rijkswaterstaat had heard of each other. Until this year, I didn’t  understand the relationship the two agencies had cultivated with one another and the steps they are taking toward improving their own programs, and I think more people would be interested to know this was ongoing. In light of much Corps criticism in the aftermath of Hurricane Katrina, it bodes well for both the agency and the United States that the organization has been taking such a proactive step to improving practice and policy.  In reflecting on the experience, I think we have reason to be optimistic for the future direction of flood management and safety in the United States as lead by the Army Corps of Engineers (Corps).


The Rijkswaterstaat (RWS) and the United States Army Corps of Engineers were created only a few years apart back in 1798 [1] and 1802 respectively for roughly the same purpose:  maintaining waterways and navigation at the federal level.  Eventually both institutions have evolved and adopted additional responsibilities including flood safety, infrastructure, and environment.

Where the Dutch have an international reputation for flood defense, it seems only a fitting country to be part of such an exchange. While there are inherent differences between the two organizations, their similarities make the two institutions comparable and ripe for collaboration.

Rijkswaterstaat Headquarters, Westraven, the Netherlands. Image: Jessica Ludy

Roughly 10 years ago, the Rijkswaterstaat (pronounced “rikes water stot”) and the Corps  signed a Memorandum of Understanding (MOU) that catalyzed a partnership to share knowledge and expertise aimed at improving water management (and safety) in both countries.  The program stepped up the intensity a notch after Hurricane Katrina, which, with the utmost respect for those in New Orleans, also provided an opportunity for the United States to start fresh with the way at least at the Federal level, the country would choose to manage floods.

The Exchange.

There are two components so far to this exchange.

1The first is swapping people longer term.

Last year, someone from the RWS staff spent one year at the Risk Management Center (RMC) in Denver  (a specialized group within the Corps).  This year, someone from the RMC who sits at the Hydrologic Engineering Center in Davis spent a year at the Rijkswaterstaat  in Utrecht. Under the frame of Levee Safety, this exchange is to observe methods, approaches, policy implications, and to transfer the other country’s approach to their own cases.

2-The second is combining cohorts twice per year. The United States sends a delegation of Corps employees to the Netherlands and the Netherlands sends elected staff from the Rijkswaterstaat to the United States every six months.  Topics covered are mostly Levee Safety and Risk Assessment, but also on new research projects in both agencies.  As well, this year a group focused on so-called “Room for Rivers.”

Since the early 1900s with the MR &T and Yolo Bypass Projects, the Corps of Engineers has considered risk reduction measures which allow rivers more access to their floodplains. After 1995, the Dutch government implemented a Room for the River program on the National level.  That the two groups meet on this topic as part of the exchange is perhaps indicative of a commitment from both countries to consider even more of these measures in future flood risk management practices.  (See post on Room for Rivers for more information.)


The highlight of this meeting for me was participating in a really interesting SWOT (Strengths, Weaknesses, Opportunities, and Threats)  Analysis.

The Dutch had 15 minutes to present the VNK Project—which aims at quantifying flood risks for all dike rings in the Netherlands. The assessment is with respect to the probability of dike failure combined with economic damages and loss of life associated with that failure.

The Corps of Engineers in 15 minutes presented the results from the Base Condition Risk Assessment– the (relatively) new Corps method to assess likelihood of inundation (based on specific failure modes) and the consequences of inundation including economic damage and loss of life.

After each presentation, the Dutch and Americans both separated to discuss and critique each others’ method. They finished off the morning by openly discussing  Strengths, Weaknesses,  Opportunities, and Threats. I sat with the Dutch.

It was evident to me from the tone in the room that both institutions have developed an air of collegiality, friendship, and trust in one another which left them both open to really give and receive honest criticism.  This, I believe will lead to even more improved methods in risk assessment and safety in the future.


Not going into detail, there were similarities and differences between the methods, as well as limitations and strengths.While I have the utmost respect for Dutch engineers and risk assessment tools, this exercise highlighted that the United States is not “ages behind” the Dutch, though we often hear ourselves compared to them. I’m borrowing this quote from a presentation of one of the Corps group members. He used this reference to make the same point–that our engineers are constantly being compared to the Dutch.

While the 1965 team of engineers in New Orleans tried to build levees strong enough to withstand the strongest possible storm in 200 years, Dutch engineers designed a system strong enough to match the kind of catastrophic storm that only occurs once in 10,000 years. “

In fact, there were areas where the Corps approach could be seen as stronger and more comprehensive than the Dutch approach.  The engineers, geotechnical engineers, hydrologists and consequence specialists are very intelligent and competent in both institutes.

Similarities: Both methods aim to quantify risk by estimating the likelihoods and consequences of failure.

Differences: The Corps approach emphasizes more human expert judgement and the RWS approach relies more on a rule-based approach.

Base Condition Risk Assessment: The RWS staff identified that the strength in the Corps approach lies in the involvement and experienced engineering judgment used to assess safety and risk of the levees. Compared to the Dutch approach, which is more rule-based and generic, the Corps looks at an individual situation and asks:

  •  What could possibly go wrong here?
  • What different mechanisms could make this levee fail?)
  •  What would happen if it did fail in this way?

 They then develop specific risk reduction measures for specific failure modes.

One downside is the question about when those experts retire from the Corps of Engineers. I forget the number exactly, but the percentage of Corps (and other Federal) employees nearing retirement is shockingly high. Will their replacements be of equally excellent caliber?  Will the new ones have the same understanding of how the system works? On additional limitation it is rather time-consuming to make specialized assessments across a country as large as the United States.

VNK: The Dutch use a probabilistic approach that combines many failure modes to generate one generic levee-failure mode used for the entire system in the Netherlands. The limitation to this is that it is not specific to an area, so arguably the actual failure mode and consequences could be different from what is projected. Given risk reduction measures are often based on the risk assessment, this could lead to inappropriate risk reduction measure. But a strength of the method is that the VNK method can be applied consistently across the entire country to estimate risk more quickly than a specialized and personalized assessment for each dike ring would.

Both received criticism well and made notes for discussions upon returning to post.  There will be a follow up again in 6 months where they repeat the process and comment on changes made since the last meetings.

Gaps: The discussion in my meeting focused on likelihoods and consequences of levee failures–and the likely (traditional structural) actions to be taken to reduce those risks associated with levees.  One area that was not discussed in the levee safety group (where I participated)  was the integration of environmental aspects into overall risk assessment. This to me, would include the risks to ecosystems, as well as using ecological restoration to reduce flood risk such as in floodways or bypasses.

State wildlife officials and volunteers wrestle a 200-pound green sturgeon that was stranded Tuesday in the Yolo Bypass near the Fremont Weir after high water dropped. “It’s not every day you get to be hands-on with a threatened species,” said Erin Aquino-Carhart, an environmental scientist at the Department of Fish and Game, of the green sturgeon.
Read more here: http://blogs.sacbee.com/the_state_worker/2011/04/state-wildlife-officials-and-v.html#storylink=cpy Photo: Randy Pench

Both countries rely heavily on structural measures to reduce risk, and have a component of “room for the river” in their management practices. But it would have been interesting at the end to combine both the Room for River group with the geotechnical and Levee Safety group for a comprehensive discussion on risk and risk reduction. Maybe there are ways to share the costs for risk reduction and ecosystem restoration projects considering the requirement for environmental mitigation anyway. I haven’t personally done such a back-of-the-envelope calculation, but it might be interesting fodder for discussion.

Moving forward.

Having done my own exchange for the past 9 months , I can appreciate the insight gained on one’s norms from living overseas. Learning Dutch approaches to and concerns associated with land reclamation, safety standards, consequences assessment, spatial planning, and ecological values has forced me to question my own assumptions, views, and values, and to identify my own knowledge gaps as well.Though not specific to flood safety, I’d like to share one concrete (and slightly comical) example of this:

The IJsselmeer (in blue), closed off by the Afsluitdijk. Image: wikipedia

After giving a lecture to a research institute on an overview of California water (supply, environmental, flood risk, and political issues), a Dutch engineer asked me why not solve our water supply problem by just closing off the Golden Gate and turn San Francisco Bay into a freshwater reservoir? (as they had done in the IJsselmeer on the left).

My internal initial reaction was something to the effect of, “well, because that’s just plain ridiculous,” but I realized that would not be a satisfactory answer. Instead I took a moment to think about it a bit more and rather chose to explain a number of environmental laws passed through history, in the region, and including stakeholder values (not to mention litigation, litigation, and litigation) that would likely prevent something like this from ever going forward. In retrospect, however, I don’t know if his idea was so far gone, considering a similar plan was once proposed (and the Corps even completed a feasibility study in early 1950s) called the Reber Plan and the San Francisco Bay Project.

I imagine that in the coming years as we are faced with even more water-related concerns including safety, supply, quality, ecosystem, and decreasing budgets, we will be forced to collaborate with others (perhaps overseas) to innovate and think outside the box to avert catastrophe. Not doing so would be a disservice to ourselves.  Therefore, I believe the ongoing  partnership with the Rijkswaterstaat is a proactive and critical component to forward-moving flood management policy in the United States. Perhaps there are other arenas that could benefit from such an exchange. Rest assured your tax-dollars (and euros) are being well spent.

For more information on the partnership, see:


[1]. Hoeksema, Robert J. (2006). Designed for Dry Feet: Flood Protection and Land Reclamation in the Netherlands. ASCE Press

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Can the Dutch teach us something on the power of communication?

My time here has been focused on learning what we can take away from the Dutch in terms of water management expertise. What is it, you ask?   I know the suspense must be killing you, so I’ll give away part of my discovery:

The Dutch find incredibly creative and simple ways to communicate important messages to the masses. They put a lot of time and effort into public outreach and communication, which  from my observation over the past 8 months, has had a very powerful effect on increasing understanding and building support for government (and other) actions.

What could it mean for the United States?

In general the Netherlands is not quite such a litigious society as the United States, so they spend less time in the court room.  But they do, as a culture, strive for something called “overeenstemming”, or as we call it, consensus.  This takes its time as well.   I often wonder in the United States,  whether our advocates, project developers, governments, scientists, and engineers could put more time and efforts into public outreach, (see great examples below), especially with controversial topics, perhaps we would find ourselves in more agreement and less at a standoff–  At least we might have less anxiety over the unknowns, (be more open-minded as a result), and we could have a more-focused awareness and discussion on what it would really mean to:

  • expand a bypass
  • designate an emergency overflow area
  • restore a floodplain
  •  reinforce levees in place
  • update building codes behind dikes
  •  re-operate dams, or
  • (gasp) even demonstrate conveyance options in/around/under/through/upside-down/inside-out of the California Bay-Delta.

In the Netherlands, it is not uncommon to find large nice posters plastered all over public works projects to explain to the public why it is their train station is under construction yet again.  I rarely hear people cursing the delays (or at least significantly less than in the United States) as a result of it because they understand what the long-term goal is. You also commonly see billboards depicting the future of Amsterdam’s harbor (and how the people will be a part of it!).

One of many posters outside Amsterdam Central Station

These signs at Delft Station takes you to the website where you can learn about the new train station modifications in Delft.

Educational Videos:

I just came across the following and feel compelled to share:  At one minute-long each,  hydrologists, engineers,  and animators provide even children a “Primary school” understanding on the “Room for the River” program.   These animations explain the (rather) complicated hydraulic processes of giving room to river with the story of the Sheep Sieb (Schaap Sieb). Other links on the site also show how the Dutch are trying to involve young adults in water management early on.  I think these approaches are useful beyond targeting young people, however. Such concepts for a video, unmuddeled by opinion or technical jargon, can really help explain to stakeholders (including educated decision-makers) what we all mean when we’re talking about such things.

I’ve embedded a few of these (what I believe to be) fantastic videos here. You do not need to know Dutch to appreciate them. But feel free to check out the site for the complete set.

Key words : “dijk”= dike/levee  “overstroming”= flood.  “Hoogwater”= high water.


Dike Strengthening:

Levee/Dike Setbacks

Flood Bypass

Lowering the groins

For more, check out the Room for the River website

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