What is Causing Houston’s City Flooding?

Aerial view of Buffalo Bayou flooding Houston’s Travis St. Bridge after the Memorial Day floods on 2015

If you’ve lived in Houston for any period of time, you’re familiar with city flooding. Do we particularly like it, no. Is it inconvenient at times, yes. Is it expensive to  property owners, as well as the the city and state, most definitely. Unfortunately, flooding is just one of the negatives you learn to deal with if you decide to make Houston your home. Some years are worse than others, but you can almost bet money on at least one of Houston’s gully washers to cause flooding somewhere in or around the city during the year. Weather officials have begun to question if Houston has become America’s “flood capital.” According to the National Centers for Environmental Information, Houston has had major flooding on an average of four to five days each year between 1996 and 2015. What Houstonians are not so familiar with, are the areas and neighborhoods never known to flood in the past suddenly flooding in recent years. This is exactly what happened during the Memorial Day flooding of May 2015. Freeways, buildings, and homes were submerged, trapping vehicles and triggering gridlock in some areas.

Houston Rainfall: May 25-26, 2015 as reported by by The Weather Channel Photo Courtesy of The Weather Channel

Information from the Harris County Flood Control District’s network, states rain totals of up to 11 inches were measured in southwest Harris County over Brays Bayou and Beltway 8. Citywide it was estimated a total over 162 billion gallons of rain was dumped over Houston and its surrounding suburbs in less than 10 hours. With rainfall like that, there is no where our city’s infrastructure can keep up. Houston hadn’t seen rainfall like that in nearly 14 years and many had forgotten the devastating affects Tropical Storm Allison had on our city back in 2001, and to think this rainfall was only a fraction of what Allison had graced us with. Seven people died in the Memorial Day Flood of 2015. Houston quickly reached the threshold to receive federal disaster assistance and authorities made a formal disaster declaration May 29. More than 13,000 residents were approved for disaster assistance from the Federal Emergency Management Agency and sought at least $57 million in aid. Not even a year later, Houston was hit again in April 2016.

Locals work to rescue up to 70 horses along Cypresswood Drive near Humble along Cypress Creek

Dubbed the Tax Day flood, parts of Houston never affected by flooding familiar to many were now victims. Hardest hit was Cypress Creek through the north Houston metro area, cresting just one inch shy of its all time record crest from October 1994 near Cypress, Texas on April 19. Incredibly, this was just under 10 inches higher than the crest there during the Allison flood of June 2001, though it should be noted metro area rainfall totals during Allison were up to double what they were in this event. An estimated 240 billion gallons of rain fell on the Houston area during the Tax Day floods of 2016, Harris County Judge Ed Emmett said. He called it the most significant flood event since Tropical Storm Allison in 2001, which left 41 people dead. The floods caused more than $5 billion in property damage in Harris County alone, the county’s Flood Control District said. What makes the Tax Day floods so different from previous floods is that more than a quarter of all 311 flood calls were outside of flood areas, which has many beginning to wonder why now?

Harris County’s watersheds according to the Harris County Flood Control District

Coined the “Bayou City” for good reason, Houston has ten winding waterways that flow through the area, but there is so much more to the extensive waterway system found within Harris County. Houston and its surrounding area has substantial watersheds from the San Jacinto River and 22 natural streams that included 44 miles of bayous, in addition to uncountable gullies.  After the Tax Day floods of April 2016, the Federal Emergency Management Agency or FEMA implemented the most significant revision of the region’s flood-risk map in nearly a decade. It was estimated that approximately 400 lucky ducks may find themselves no longer classified in flood zones, but effective January 2017 more than 8,000 structures and homes never considered to be in designated flood zones will now be elevated to Special Flood Hazard Areas. The new map places special emphasis on areas on the far western edge of the county, near the Addicks Reservoir, and vulnerable areas west of the Grand Parkway near Katy Hockley Road that saw substantial flooding in the spring of 2016. Other new flood hazard areas are in the regions east of the Beltway extending to San Jacinto College Central and along Armand Bayou in Pasadena, as well as areas on the east end of the 610 Loop along Buffalo and Brays Bayous and parts of northeastern Harris County.

Houston’s revised flood map that went in to effect January 2017

So why now? Why are established areas and neighborhoods now being elevated to Special Flood Hazard Areas? According to Dr. Sam Brody, PhD, professor and director of the Center for Texas Beaches and Shores in the Marine Sciences department at Texas A&M University in Galveston, the biggest driver of this urban flood problem is human development. Dr. Brody was recently a guest speaker at a presentation sponsored by citizen’s group, Residents Against Flooding, a group dedicated to reducing preventable flooding caused by development in the Houston region. He has also had an article featured in the British publication, The Guardian, where he stated “Houston has more causalities and property loss from floods than any other locality in the US, according to data stretching back to 1960.” He went on to say “[w]here the built environment is a main force exacerbating the impacts of urban flooding, Houston is number one and it’s not even close.” In March of this year, Dr. Brody was appointed to be a member of the National Academies of Sciences, Engineering and Medicine committee to study urban flooding, which has plagued Houston in recent years, and issue a report. During the 18-month project, “Urban Flooding in the United States,” Brody along with 11 fellow scientists selected by FEMA to chair the committee will gather flood-related data from agencies responsible for flood control, response, recovery and mitigation in 3 to 8 metropolitan areas, one of which is Houston. The committee, composed of social, natural and physical scientists, will ultimately produce a report for FEMA and federal legislators that identifies the scope of flooding, effective flooding mitigation strategies, unexpected recovery issues, and similarities and differences in flooding events in the project’s selected areas. The report will also identify the damage that flooding does to infrastructure, human life and property.

A Houston city map circa 1891 compared to an aerial view of Houston from 2011

It’s no surprise that Houston has changed since a cartographer created the map above in 1891, but it is these changes in the landscape and other developments of Houston that Dr. Brody is attributing the increase of flooding in recent years. Brody has repeatedly stated to audiences during his lectures, as well an interview with CNBC in April 2016, “every square meter of pavement in Houston, on average, translates into about $4,000 of extra flood damage.” Brody also commented in the same CNBC interview that “…between 1996 and 2011, the Houston region increased its pavement, its impervious surface coverage, by about 25 percent, which is hundreds of square miles of pavement.” That growth is likely to continue. In 2015 alone, an additional 90,000 people settled in Houston and the region is expected to grow by 3.7 million people over the next 30 years, according to Brody’s recent research.

Buffalo Bayou with downtown Houston’s skyline in the background

Another improvement imperative to help reduce flooding in Houston is better planning. According to Brody, “Flood planning requires efforts from multiple levels of government and community, from the individual homeowner to the local neighborhood and beyond.” The city of Houston follows the policy of widening and deepening (and destroying) our urban streams to handle increased storm water flow. Unfortunately, this policy is not only outdated it is also proven to be ineffective. Widening and deepening bayous simply creates a short-term solution, but doesn’t solve the city’s flooding issue. The Harris County Flood Control District is currently is working on a development project that would include razing the trees, digging up, channelize, and shorten on the last natural stretches of Buffalo Bayou in order to send more storm water faster. Not only would this project cost the city upwards of $12 million dollars, it’s a practice that even the US Army Corps of Engineers acknowledges causes more flooding and erosion downstream. So the question now is, what’s our solution to assist in decreasing the flooding in Houston? According to Dr. Sam Brody, the answer is green infrastructures.

Philadelphia, PA is being hailed “the most comprehensive network of green infrastructure in found in any US city”

Leading experts nationally agree that the emphasis should not be creating more space within our bayous, streams, and rivers for storm water to flow into, but on slowing down, spreading out, and soaking in storm water before it hits the city’s natural bodies of water. Cities all across America from San Francisco to Chicago to Philadelphia have began implementing the concept of green infrastructures in their cities as an approach to water management that protects, restores, or mimics the natural water cycle. Even the New York City the “concrete jungle” plans to rebuild using blue-green infrastructure after Hurricane Sandy, but a city such as flood-prone Houston does not. While hundreds of millions of dollars have been spent in beautifying Houston’s city parks and green spaces, very little has been done in the creation of green infrastructures that would not only be an effective and economical way of reducing our city flooding, but would also enhance community safety and overall quality of life. Groups such as local activists Save Buffalo Bayou and nationally known The Conservation Fund are both working hard to getting those in charge of our city’s big decisions to see our current policy is not working and the project they have on board involving Buffalo Bayou will be very expensive but ineffective as a flood plan.

Cincinnati, OH Sewer District’s Lick Run green infrastructure project

After the wallop Houston received two years in a row, it’s safe to say a change in in order. Is the city’s current plan of widening and deepening the bayous going to be successful, only time will tell. Will experts such Dr. Sam Brody come up with a solution to if not eliminate, at least decrease the flooding in Houston, hopefully.   Until then, any Houstonian will agree they would much rather see something similar to what Cincinnati or Philadelphia have implemented than horrific flooding experienced during May 2015 or April 2016.

Wimbledon Champions Park subdivision flooded after one of Houston’s gully washers
















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