Facing Floods with Infrastructure

Marina Dauer

Author: Marina Dauer is a sophomore in the School of Arts & Sciences double majoring in Environmental Studies and Political Science, a University Scholar, and an Undergraduate Fellow at the Wharton Risk Center.

Funding large-scale infrastructure projects is important for reducing flood damage to homes and businesses, and is a vital part of the solution in an increasingly flooded world. Both the geographical extent and economic cost of flood events are projected to increase significantly by 2100. As Professor Benjamin Keys notes in his climate risk solution, the National Flood Insurance Program (NFIP) carries responsibility for much of the federal government’s climate risk resulting from flooding and hurricanes, but is also heavily in debt.

Increased subsidies or other policies designed to support low-income property owners, comprehensive education programs about the importance of purchasing flood insurance, and the development of innovative insurance models are all paths to building a stronger offering of flood insurance policies. However, the growing impacts of flooding due to climate change paired with the weaknesses of the National Flood Insurance Program necessitate increased investment in flood risk reduction. Funding a combination of gray, green, and hybrid infrastructure projects is one approach for reducing climate risks currently carried by the NFIP.

The most frequently-used flood mitigation tools have been “gray infrastructure” projects – built structures or human-engineered solutions, including flood control dams and reservoirs, channel modifications, floodwalls, and levees. Gray infrastructure projects are an effective disaster risk reduction as they prevent flooding before it occurs, and offer a complementary strategy to the risk transfer provided by insurance policies. These solutions have been put into place by many states and communities. After historic flooding in 2008, legislators in Iowa created the Iowa Watershed Project, a pilot infrastructure program which carried out over 150 grey infrastructure projects. In 2016, this effort was expanded into the Iowa Watershed Approach, a $97 million long-term program. Still, gray infrastructure solutions have limitations as they can cause a false sense of safety and resulting community under preparation, push flooding into new areas, and lead to worse outcomes in the event of infrastructure failure.

Large-scale infrastructure projects are most successful when they include a carefully planned combination of gray and green infrastructure, a category which includes tree plantings, green roofs, permeable pavement, and restoring wetlands (often after a land buyout). The use of green infrastructure has historically been low, due to the difficulty of quantifying the benefits of ecosystem services, the longer time horizons needed to restore natural ecosystems, and a preference for high profile post-disaster responses rather than less conspicuous green infrastructure. Recently, the adoption of green infrastructure has accelerated due to its large economic potential, with estimates that it could save hundreds of millions of dollars in flood losses. It also provides significant ecological co-benefits by preserving river-floodplain ecosystems, some of the most productive and diverse ecosystems. There are a number of green infrastructure success stories, including an initiative to transform vacant lots in Detroit into green spaces that has the capacity to reduce stormwater discharge by approximately 100,000 gallons during large storms. Another example is the creation of a linear park in Milwaukee’s 30th Street Industrial Corridor, which will connect two waterways and include strategically placed infiltration areas and bioswales.

Hybrid solutions which utilize both green and gray approaches can lead to the most cost-effective and resilient infrastructure systems. This also increases the number of possible infrastructure solutions, allowing for a wide array of outcomes that match the environmental and social needs of the community where they are implemented. Flood risk reduction experts are increasingly advocating for hybrid measures, such as utilizing both a mangrove conservation and a levee. Hybrid infrastructure solutions are a key component of a flood mitigation program that will remain effective as incidences of flooding increase.

Clark County, Nevada presents a compelling case study of integrated flood risk management at a local level, as the county has been able to successfully fund and implement large infrastructure projects on a continuous basis for the past four decades. The county’s flood infrastructure program, which has been described as “one of the most progressive self-funded flood control programs in the country”, has successfully removed 54 square miles of land including hundreds of homes from the high-risk floodplain. This program now protects the entire Las Vegas strip, as well as land upstream, which was achieved through the building of 650 miles of flood channels and over 100 flood basins. The program is funded primarily by the federal government, as well as through pro-rating .25 cents of the locally generated sales tax for flood protection projects. Clark County’s integrated flood risk management approach successfully combines hybrid infrastructure solutions with comprehensive risk communication and insurance promotion, providing a model for other communities looking to reduce flood risk for their residents; it also exemplifies the importance of making flood mitigation a sustained priority. The success of this program is evident as it creates or sustains over 1,500 jobs and has a 2.2:1 benefit to cost ratio for completed projects, which amounts to savings of millions of dollars every year.

Increased investment in flood risk reduction through infrastructure investment and integrated flood risk management solutions is necessary given the growth in flood events caused by climate change. Research into the effectiveness of hybrid infrastructure solutions provides excellent examples to illustrate best practices for addressing this worsening threat and evidence for why infrastructure is an essential component to integrated risk management approaches. Additionally, the Clark County case study illustrates the opportunity for savings by proactively investing in integrated flood risk management instead of using funds to fix flood damage after it occurs, as well as the benefits which can be achieved by using an integrated risk management approach that combines infrastructure with risk communication and insurance promotion. By investing in integrated risk management solutions now, we can avoid the higher costs – and human hardship – that will come with addressing floods after the fact.

Originally published on May 12, 2020.

See all student solutions here.