Growing Threat of Urban Flooding Labeled National Challenge by New Study

Researchers at Texas A&M Galveston and the University of Maryland have just published a massive new study on The Growing Threat of Urban Flooding: A National Challenge. The study – a treasure trove of insights – actually started in 2016, before Harvey.

It focuses primarily on urban flooding as opposed to riverine flooding, which caused many of the Lake Houston Area’s problems. However, area residents should not dismiss it. The two types overlap and the report largely addresses issues that exacerbate both, such as inadequate governmental systems, engineered structures and growth that overwhelms both.

The report contains eight major sections that quantify the scope of the challenge. Below, a few highlights from each.

I. Urban Floods: The Nation’s Hidden Challenge

Documents the stunning extent of urban flooding and factors that continue to make it worse. Did you know for instance, that two thirds of the nation’s population living in floodplains live in just two states: Texas and New York? Or that Texas led the nation in billion-dollar water and wind disasters between 1980 and 2018?

II. Analyzing Urban Flooding

Reveals statistics on the scope of the problem. Two gems:

Nationally, 83% of respondents indicated they had experienced urban flooding in their communities. And 85% experienced urban flooding outside special flood hazard areas!

III. Where Urban Flooding Occurs

Shows that Texas ranks in the middle of the pack in terms of frequency of events, as opposed to major events. The researchers found that nationwide, approximately 25% of all flood insurance claims are submitted by policy holders whose property lies outside the 100-year flood plain. New York found that “The problem in most communities is lack of enforcement. Communities need a comprehensive plan to address development, infrastructure needs, stormwater runoff, and building codes. When a community doesn’t address these issues it only exacerbates other problems and continued urban sprawl eats up rural areas causing flooding, erosion, and infrastructure malfunction.”

IV. Why Does Urban Flooding Happen?

Examines aging and inadequate drainage systems, increases in local and regional runoff, sewage and stormwater backups, changes in local physical conditions, and failure to maintain drainage systems. Sound familiar? If you’re worried about where your drainage fee goes, be thankful that you don’t live in Detroit. That city reports that 75% of the drains citywide are covered by debris or have a blockage.

V: Consequences of Urban Flooding

Talks about the economic and social costs of urban flooding. Did you know, for instance, that almost 40% of small business never reopen their doors following a flooding disaster? And that 90% of businesses fail within two years of being struck by a disaster? However, because no single federal agency collects and evaluates flood loss information, all national flood loss estimates are considered “approximations.” Therefore, the report says, they are of marginal use in conducting accurate economic analyses to support urban flood risk reduction mitigation.

Social costs hit moderate income, the old, and those facing social challenges the hardest. “For those lacking critical resources (savings, insurance, etc.), the flood losses gnaw away at their well-being.”

In regard to Houston, the study found that, “The urban flooding that occurs in the heart of the central city is mainly attributed to existing drainage infrastructure that predates today’s design standards or insufficient pipe sizes for the now fully developed urban areas.”

VI: What Can Be Done About Urban Flooding?

Examines different strategies to mitigate flooding:

  • Planning
  • Capturing rain where it falls
  • Eliminating or reducing risk
  • Adequate maintenance
  • Upgrading capacity standards
  • Risk communication (gaining better public understanding)
  • Better mapping
  • Disclosing risks in user-friendly ways
  • Insuring at-risk properties.

Some key insights:

  • Lack of funding and lack of political will are the most significant issues.
  • Much of the available funding requires a cost share and significant participation in the NFIP program. Most properties outside the mapped floodplain do not carry flood insurance. This then requires localities to fund these initiatives by themselves.
  • New development outside the floodplain generally has limited stormwater control requirements. Local CEOs are often reluctant to require stormwater controls as they fear this would dissuade development.

VII. Major Challenges

Includes discussions of lack of resources, population/urban growth, climate change, priority setting and fragmented governance.

If you want to understand why flood mitigation  and what needs to be done to fix it, read this report.

VIII. Moving Ahead: Challenges and Recommendations

The study outlines ten challenges and makes 9 recommendations. Most target government leaders and policy makers. They are much too detailed to summarize here without tripling the length of the post. But if you want to know what you should push your representatives to consider, you must read section.

Number 8 read: “Governments, at all levels, have not provided effective means to communicate risks to those in urban flood- prone areas. A significant number of these areas are not identified by maps produced under the Federal Emergency Management Agency National Flood Insurance Programs, and actions by those responsible for urban flood mitigation are needed to delineate these areas. Communication of flood risk is often seen by public officials and developers as a negative.”

In my opinion, it’s a positive. A better understanding of risk could help everyone make better decisions that prevent heartbreaking losses, such as those we saw with Harvey.

All in all, this is a must read for anyone who wants to understand urban flooding and why it is so difficult to address.


For University of Maryland

  • Dr. Gerald E Galloway
  • Dr. Allison Reilly
  • Sung Ryoo
  • Anjanette Riley
  • Maggie Haslam

For Texas A&M University

  • Dr. Sam Brody
  • Dr. Wesley Highfield
  • Dr. Joshua Gunn
  • Jayton Rainey
  • Sherry Parker
Posted by Bob Rehak on 12/2/2018 with thanks to Jacque Havelka 
460 Days since Hurricane Harvey