Hot off the press from the Center for Disaster Resilience at the University of Maryland and Center for Texas Beaches and Shores at Texas A&M University, Galveston Campus: The Growing Threat of Urban Flooding: A National Challenge.
If Dr. Gerry Galloway is involved in this effort, you know it's got to be real good. Add Sam Brody and Jayton Rainey from TAMU and you have quite a team!
Download UMD_TAMU_Urban_flooding_report_online_revised
Webinar recording: click here or view below.
The blurb from the website:
In 2016, the Center for Disaster Resilience at the University of Maryland and Center for Texas Beaches and Shores at Texas A&M University, Galveston Campus initiated a joint study to identify the principal causes of flooding, determine the extent and consequences of urban flooding
in the United States, and explore what actions might be taken to mitigate this flooding in the future. Center researchers analyzed available data concerning urban flooding, surveyed municipal flood and stormwater managers, and met with professionals whose disciplines intersect with urban flooding at the local, state, and national level.The research team's findings affirm that urban flooding is a national and significant source of economic loss, social disruption, and housing inequality. This report presents the full results of the study, addresses governance issues that affect urban flood risk reduction, examines critical challenges, and offers recommendations for actions.
Enjoy!
"No single raindrop believes it is to blame for the flood." - E. L. Kersten
The report cites
"Aging and inadequate infrastructure, coupled with rapid land development, increased the amount of storm runoff to already stressed drainage systems, creating pockets of flooding" as the causes of urban flooding. It should be noted that these are all human-created conditions aside from the inference of increased intensity of storms.
Further, the report says:
"Through the 1968 NFIP, the federal government-initiated efforts to mitigate flood losses using a federally-backed framework that permits home and
business owners to purchase insurance for properties susceptible to flooding when their communities agree to participate in the NFIP and limit future development in flood-prone areas. The magnitude of NFIP claims has served as a measure of the nation’s flood vulnerability."
However, urban growth & sprawl has not been significantly limited...and in most cases it is the likely cause of both increased occurrence and increased intensity of urban flooding.
Recent headlines emphasize this point:
Urban sprawl in Houston, Texas, increased precipitation & flooding during Hurricanes
-- https://phys.org/news/2018-11-houston-urban-sprawl-rainfall-hurricane.html
-- http://www.startribune.com/houston-skyscrapers-may-have-worsened-hurricane-harvey-rain/500504781/
Continuing to allow development within the 100- and 200-year designated floodplains negates the natural availability of the 500-year floodplain to respond to storm events. Primarily using the 100-year flood event as a guideline can be extremely mis-leading in terms of flood events that should be expected. For example, from 1864 through 2002, there were at least 18 major istoric flood events on the Guadalupe River in Texas where peak discharges exceeded the 100-year flood, including the 1998 & 2002 floods which have been described as 500-year events. The interval between these events ranged from 4 to as many as 14 years.
Focussing on the "return period" or frequency provides a more reliable (and often times for humans a more alarming) estimate of future events which may serve as motivtion to take appropriate actions, limit growth in flood-prone area, and/or to develop effictive mitigation policies.
Posted by: EJ Hanford | Sunday, 02 December 2018 at 07:39 AM