Urban flooding is a serious and growing problem. “Around 20-25 percent of all economic losses resulting from flooding occur in areas not designated as being in a “floodplain,” but as a consequence of urban drainage,” according to the Federal Emergency Management Agency (FEMA).
The impacts of urban flooding are also on the rise, which is why Rep. Mike Quigley (D – IL) and Rep. Peter King (R – NY) introduced the bipartisan Urban Flooding Awareness Act of 2014 (H.R. 5521) in Congress earlier last month. H.R. 5521 is essentially modeled after similar legislation passed in May of this year by the State of Illinois. Like the state bill, this federal legislation is intended to develop a clear-cut definition of “urban flooding" - this is important because it will allow experts and stakeholders to better understand the scope of the problem. Additionally, H.R. 5521 directs the Administrator of FEMA to enter into an agreement with the National Research Council to conduct a nationwide study on urban flooding.
As a result of our warming climate, heavier rainfalls are increasing nationally. According to the Third National Climate Assessment report released in May 2014, very heavy precipitation events, defined as the heaviest 1% of all daily events, have been on the rise in every U.S. region since 1960, with the Northeast, Great Plains, Midwest, and Southeast recording the largest increases – more than 30% above the 1901-1960 average.
More frequent and heavier precipitation patterns could lead to an increase in flood risk, particularly in urban areas with their paved surfaces and limited open land where rainwater can be absorbed. Urban flooding refers to the flooding of basements, backyards, and streets of homes and businesses caused by too much rain overwhelming drainage systems and waterways. With the continuing growth of cities, more and larger areas of impervious surfaces are created, such as roads, highways, parking lots, and rooftops – this expansion of impervious surfaces, coupled with expected upward trends in heavy downpours as a result of climate change, will lead to increased stormwater runoff, putting additional strain on our nation’s storm sewers.
Ariel view of New Orleans after Hurricane Katrina (Credit: NOAA)
The social and economic impacts of urban flooding are huge. Urban flooding damages homes and businesses, which can lead to loss of lives and livelihoods. According to FEMA, almost 40% of small businesses never reopen their doors following a flooding disaster. In addition, the costs of repeated flooding and wet basement damage are significant - something that, unfortunately, is mainly borne by U.S. taxpayers as 63% of all urban flooding damage payouts are paid for through FEMA disaster relief funds. Lastly, chronically wet houses are linked to an increase in respiratory problems and other illnesses.
Given the projected increases in urban flooding associated with a warming climate, the introduction of H.R. 5521 marks an important first step in helping at-risk communities across the country understand urban flooding and identifying innovative solutions to make cities more resilient even in the face of a growing threat of more severe floods in the future.
By setting a clear definition of urban flooding and thoroughly studying the issue, we can begin to better understand the risks and impacts, and consequently develop creative, thoughtful solutions to prevent future losses. Among other things, the urban flooding study will include an evaluation of the prevalence and costs associated with urban flooding events across the U.S., the adequacy of existing federally provided flood risk information, the causes of urban flooding, and the most cost-effective strategies, practices, and technologies to reduce the impacts of urban flooding.
The study will be the basis for recommendations that will be provided to Congress, no later than three years after the Act’s date of enactment, on policies and strategies that can reduce the risk of urban flooding and protect residents and business owners from the impacts of climate change.
The ultimate goal of H.R. 5521 is to develop policy options that the federal, state and/or local government can implement that may help communities mitigate and potentially avoid the impacts of urban flooding in the future. One such solution may be the use of green infrastructure. As my colleagues Ben and Larry have discussed many times before, green infrastructure is one of the best ways to reduce urban flood risks. Green infrastructure practices – such as green roofs, rain gardens, permeable pavements, rainwater harvesting systems, and pocket wetlands – help address stormwater runoff problems by restoring parts of the natural water cycle that were paved over by development. Not only can green infrastructure reduce risks of urban flooding by minimizing stormwater runoff but it can also improve water quality by preventing polluted runoff from ending up in our precious rivers, lakes, and ocean waters.
As climate change brings about heavier and more prolonged rainfall events, and exacerbates flooding risks in urban areas, it is time for our federal and state governments to act now to help American cities confront the realities of a warming climate. As such, we commend Reps. Quigley and King for introducing such an important bill like H.R. 5521 in Congress and for guiding the country towards a more resilient future.