2017 has been a brutal year for floods across the Canada-US border, and more broadly North America. Major flooding hit areas like British Columbia, Washington, Texas, Florida, New York, Ontario and Quebec due to heavy rains, snowmelt conditions, saturated soils and severe storms. 2016 also saw major flooding, including multiple billion-dollar floods in Texas and Louisiana, as did 2015. Strategies to reduce flood risks have been advocated for decades, yet by many accounts, flood damages are increasing. Why?
The IJC addressed some of those mitigation strategies in multiple reports, including 2000’s Living with the Red (about flooding on the Red River), 1993’s Methods of Alleviating the Adverse Consequences of Fluctuating Water Levels in the Great Lakes-St. Lawrence River Basin, and 1981’s Regulation of the Richelieu River and Lake Champlain. Different measures may be needed to cope with flooding on lakes and rivers, but common themes have emerged.
The reports echo advice provided in almost every post flood assessment, including a floodplain study preliminary report the US Scientific Assessment and Strategy Team issued in 1994 following devastating floods along the Mississippi River in the summer of 1993. A common suggestion is that thoughtful land-use planning and an array of flood protection methods are the best way to minimize damages to low-lying communities that could be threatened by nearby water systems. While there is no singular element that can safeguard all communities from floods, a combination of relevant actions from the municipal to the federal level can help limit costs and impacts.
The IJC will confront this flood management conundrum in new flooding studies underway in the Lake Champlain-Richelieu River basin and the Souris River basin. Those studies should produce reports on mitigation strategies for those regions in 2021 and 2020, respectively, though some of the lessons will likely be transferrable to other regions, just as lessons in older reports on the Red River and Great Lakes.
Thoughtful Land Use and Flood Control Methods
Just as in real estate, when it comes to floods it’s all about location. Buildings in a flood plain are inherently at greater risk of being damaged than those built on higher ground. The IJC and others have repeatedly recommended that governments aggressively promote shoreline land use and management measures that keep the consequences of fluctuating water levels and floods in mind.
The use of land in Canada and the United States is determined by the land owner, within government-determined restrictions. The decisions of owners and governments affect flood risk. If flood damages are getting worse, is it because decision makers have not heard the advice on flooding or because they reject it?
Some flooding occurs far from rivers and lakes because of inadequate storm water management. That was part of the problem in Houston, Texas, and Windsor, Ontario, this year. The common advice is to require new developments to build retention ponds to offset the increase in runoff caused when roofs and asphalt replace trees and wetlands and to plan systems that can channel the runoff safely into large water bodies. Houston residents voted three times not to enact zoning codes that would reduce flooding but increase development costs, a decision that may have helped lead to disaster. Windsor has been working on improving its sewer system, which has been overwhelmed by exceptionally heavy storms like one that caused flooding in August.
Communities need to consider their zoning and land usage policies in riskier areas, either by leaving those at-risk areas undeveloped or requiring that structures built there follow flood-proofing construction measures. These can include being raised off the ground above the flood level, having erosion or recession setback requirements, or requiring hazard insurance for property owners who operate there. Undeveloped areas are capable of absorbing precipitation that would otherwise end up as runoff on impermeable streets, sidewalks and buildings, in turn helping reduce flooding.
Governments also can offer to buy out high-risk lands, giving property owners of developed lands a chance to relocate, and keeping at-risk undeveloped land from being built up. This approach was used along the Lake Ontario shoreline in Ontario in the 1970s, in New York and New Jersey after Hurricane Sandy, and in several states following the Mississippi River floods. In the IJC’s 1993 Great Lakes report, the commission noted that is “unfair to expect the general public to pay a disproportionately high price” to protect shoreline property owners unless some degree of mitigation is being used for developments.
Which measures should be taken depends on a location’s specific conditions. In particularly flat basins such as those around the Red River or in places already heavily developed, it might not be economically or socially viable to simply pack up and rebuild further away from the water. Raising buildings and constructing dikes or shoreline protection measures may be more feasible in those areas. But the IJC in its 1993 Great Lakes report cautions that privately built structures along the Great Lakes shore were often found to fail within 10 years, could shift damages from one riparian property to another, and damage the environment and natural habitats. Specific circumstances around their construction should be studied ahead of time, and inspections for protective structures carried out. The Commission noted that if an area is threatened by flooding or erosion, those problems will likely continue to exist regardless of shore protections.
The more obvious issue is flooding on land that abuts water. Zillow reports that waterfront homes are worth more than double of the value of homes overall, so there is strong impetus to develop the shoreline.
Analysts view the long-term history and warn that past floods may be repeated, even exceeded at any time. For the individual land owner, however, there may be a natural tendency to focus on the times when the land isn’t flooded, when the enjoyment of its location makes it so valuable. What new homeowner doesn’t imagine what can be done to improve the property? Many flood reports include statements from astonished land owners who testify that they have owned the land for many years and have never been flooded. The widespread resistance of owners to flood insurance, even though it’s often priced to subsidize expected damage, is evidence that owners act as if they will not be flooded. Ultimately, the IJC has recommended that there is a need to establish a culture of flood preparedness in areas where it’s a risk, and that requires property owners to understand and prepare for the worst.
Reservoirs and Flow Changes
In some areas, flooding can be reduced though the usage of water storage, according to the Living with the Red River report. These methods can include building flow-restricting dams and other structures to form artificial lakes and reservoirs; a “waffle approach” of using depressions, roads and gates to form smaller “micro-storage” fields that water runs off into; or with the help of wetlands. Unfortunately, these approaches alone are unable to solve all flooding problems.
Additionally, control structures have limits to how much they can influence waterways. While dams and gates can moderate flows, if water supplies are too great then there’s little, if anything, they can do. The Great Lakes report notes this, adding that the Great Lakes are so massive that flood control measures on the outlets of Lake Huron and Lake Erie would cost tens of billions of dollars to build. Further, such measures would require drastic adjustments to water flows and the rivers, a re-engineering of the St. Lawrence River, and wouldn’t be environmentally or economically feasible considering interests across the basin that would be impacted. The remaining natural cycles in the Great Lakes would be dramatically altered.
That same Great Lakes report also notes that flood control measures using levees, dikes, channels and control structures along the Mississippi River failed during the 1993 floods, becoming overwhelmed by the amount of water. While these structural attempts at changing how water moves can certainly play a role to limit or prevent small floods, they can’t serve as a catch-all solution either.
A stretch of heavy rains starting in April and stretching into July of 2017 around Lake Ontario and the Ottawa River, coupled with a record snowmelt on the Ottawa and problems developing an ice cover in the winter, overwhelmed control structures and water regulatory plans in Ontario, Quebec and New York this year. Communities around Montreal flooded as the massive amounts of snowmelt water made its way down the Ottawa River, which joins with the St. Lawrence River in Montreal’s Lake St. Louis. Extensive damage to shoreline property also occurred on Lake Ontario and elsewhere on the St. Lawrence River. When coupled with wet conditions on Lake Ontario, water managers who regulate Lake Ontario’s flows – and thus influence its water levels – couldn’t physically get water out of the system fast enough without worsening the situation downstream. Regulators studying the flood have found there simply wasn’t much of anything structurally that could have handled the warm and wet conditions in the winter and spring that led to the flooding.
The US Army Corps of Engineers alone has invested more than $100 billion dollars in hundreds of flood control reservoirs and built more than 8,000 miles of levees since the 1936 Flood Control Act, and yet by most accounts, US flood damages are increasing.
Modeling, Mapping and Studies
To assist in effectively preparing for floods, figuring out the best places to build and how best to make sure damages are limited, governments can start with maps. New technology can provide a strong foundation in mapping out the geography of the land and creating updated flood plain maps.
Additionally, new measurements can help refine hydrological models so officials have a better idea on how water enters the system, moves around, and ultimately how much flooding may result. These models bring in water sources like precipitation, snowmelt, groundwater and runoff to try and mimic natural processes. The models can be further improved by harmonizing Canadian and US data, which has been underway in basins across the transboundary region.
In the Mississippi River flood report, the authors suggested studies in a variety of regions to determine how different land use and land management techniques impact flood dynamics, sedimentation, agriculture and habitat restoration efforts. This would help improve those models for specific at-risk regions.
Additionally, the IJC in its 1993 Great Lakes report recommended long-term monitoring of shoreline erosion and bluff recessions to help refine erosion-related damage assessments.
That data and research should be used by managers and policymakers so they can effectively plan for future floods, whether they be from heavy rains, dramatic snowmelts or both. Models and maps can’t reduce flood damages unless they are accurate and used by local officials.
2018 and Beyond
If these widely supported solutions have not worked, however, what should we do? The IJC will have to confront the flood management conundrum in its Souris and Champlain studies. Other researchers, notably the nonprofit environmental and energy research institute Resources for the Future, have begun to analyze the difference between theory and practice and developed one new, bold suggestion: that communities rather than individual property owners should purchase flood insurance. The common wisdom has failed us; unless we can change, we can expect many brutal years of flooding in the future.
Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.