Both the Washington, D.C. area and greater New Orleans have been proactive when it comes to preparing for heavy rainfall and storm risk. But when an unprecedented amount of rain fell on Washington on July 8, hundreds of motorists were stranded in high water, their cars ruined by a flash flood. Residents and small businesses faced hundreds of thousands of dollars in flood-related damages. Likewise, when Tropical Storm Barry made landfall near New Orleans the following weekend, the Gulf and Mississippi Valley regions had to contend with flash flood warnings for more than 11 million people, power outages for more than 140,000 homes and “dangerous, life-threatening flooding.” The projected increase in frequency and intensity of events like these serve as stark warnings that more must be done to ensure our country’s infrastructure is prepared for climate change.
The July 8 thunderstorms dumped approximately 3 billion gallons of water onto the D.C. area. At one point, 3.3 inches fell in one hour, surpassing the previous record, set in 1958, by more than one inch. Even the White House flooded. Such a rain event in the D.C. area had only a 0.5 percent chance of occurring in a given year, based on historical data. However, climate change is making extreme precipitation events more common and more intense. When the climate warms, evaporation rates increase and more water vapor is stored in the atmosphere, resulting in more extreme precipitation events. By 2050, a storm of this magnitude will be eight times more likely to occur in a given year. And while it may be too soon to conclusively attribute D.C.’s extreme rainfall to climate change, it is right in line with National Climate Assessment projections.
These events highlight the integral role of resilient infrastructure. Washington, D.C and other communities in the metro region have been proactive in making infrastructure investments, but they have a long way to go to contain drainage overflows caused by heavy rainfall. The District of Columbia has invested $2.7 billion in storm and wastewater infrastructure through the Clean Rivers Project, which did help tremendously during the latest flooding. The Anacostia River Tunnel, built for $580 million as part of the project, stopped 170 million gallons of combined sewage from drainage overflows, but was still unable to capture 50 million gallons that flowed into rivers.
Like D.C., the Gulf and Mississippi Valley regions also experienced high levels of flooding when Tropical Storm Barry produced more than 3 inches of rain in one hour in some areas. Luckily, the rainfall total was less than some of the dire forecasts of up to 20 inches of rain and the Mississippi River cresting at 20 feet due to storm surge from the Gulf of Mexico. No levees were damaged or failed, sparing communities from untold damages. This near miss highlighted the precarity of the infrastructure protecting Louisiana. After Hurricane Katrina, the federal government spent $14 billion on a series of levees, floodwalls, gates and pumps to protect the greater New Orleans area from hurricane and storm risk. An analysis found that by 2023, this system would no longer offer adequate protection against a 1-in-100 year storm event, in part due to rising sea levels. Louisianans are also working at the state and local level to develop and implement innovative resilience strategies, many of which are outlined in the state’s Coastal Master Plan.
In preparing for a future shaped by climate change, the federal government must work with state and local governments to invest in infrastructure to protect at-risk communities and ensure that it is built to withstand climate impacts. Funding high-resolution climate data and technical support for states and communities to develop local projections is essential. This would empower communities to accurately assess their risk and create long-lasting plans to be resilient. Codifying resilience into federal infrastructure projects is another way to ensure investments are climate-smart. In 2015, the Federal Flood Risk Management Standard (FFRMS) was enacted by executive order. Revoked in 2017, the order would have made federal infrastructure investment contingent on a project’s ability to withstand a greater level of flooding than the typical 100-year floodplain maps anticipate. Codifying the FFRMS would ensure federal dollars are spent only on projects that could withstand future climate risk – protecting lives and investments. The federal government should also study and explore the use of nature-based infrastructure that can provide better protection and more co-benefits than traditional infrastructure projects.
Ensuring that localities have enough funding to implement resilient infrastructure projects must also be a key component in building a resilient future. While FEMA’s Pre-Disaster Mitigation fund gave out $235 million in FY 2018 for hazard mitigation projects, this amount is woefully inadequate in light of the multi-billion dollar cost of projects in Louisiana and D.C. alone. It’s a worthwhile investment: for every $1 spent through mitigation grant funding, $6 are saved.
Lastly, we can anticipate some flood risk is unavoidable and will need to be covered by flood insurance. Two National Flood Insurance Program (NFIP) reform acts, one in the House and another developed by a bipartisan team of Senate and House Members, include language to address affordability of flood insurance, improve flood mapping, and fund risk mitigation. Congressional action on NFIP reform can provide more stability to real estate markets and improve flood coverage for those at risk.
The two extreme rain events experienced in one week serve as a reminder that the frequency and intensity of similar events will only increase over time. Even though D.C. and the New Orleans area have been proactive in making infrastructure investments, both still experienced severe flooding and remain vulnerable. These communities cannot do this alone: the federal government must lead the way with resilient infrastructure policy and provide financial, technical and coordinating support to enhance community resilience. Following the steps outlined here could help protect them, and communities across America, from the high cost of climate change.