Did Straightening Upper Buffalo Bayou Make Future Residents More Vulnerable to Flooding?

Federal Project in Late Forties Reduced Bayou Capacity Upstream

 

October 29, 2018

By the early morning of Aug. 28, 2017, after about thirty hours of record heavy rains from Hurricane Harvey, storm runoff was rising so fast in the two federal reservoirs in west Houston that the Corps of Engineers feared the water would overflow the aging earthen dams. They made the unprecedented decision to open the dam floodgates, slowly at first and then, in the following days, much wider, as stormwater did indeed begin to spill around the northern end of Addicks Dam north of Interstate 10.

For most people living and working on Buffalo Bayou, the peak of the flooding had already passed on Sunday, Aug. 27, when the floodgates were still closed. That Sunday storm runoff draining from the paved and built city into the bayou below the dams sent anywhere from two feet to eight feet or more into homes and other structures built on or near the banks.

But when the dam floodgates were opened in the first hours of Monday, roaring floodwaters pouring out of the dams spread out and inundated neighborhoods built on the bayou’s floodplain below the dams for more than six miles to just below Beltway 8 (West Belt). Many of these homes had not flooded earlier.

The horrific flow through the open floodgates eventually reached more than 16,000 cubic feet per second (cfs). For much of Buffalo Bayou in west Houston flood stage is around 6,000-7,500 cfs.

As a result, many more homes and other structures flooded on the upstream stretch of Buffalo Bayou between the federal dams and Beltway 8 than downstream of the beltway. (Homes built in the reservoir flood pools behind the dams also flooded, but that’s another story.)

Map of Harvey flood damage claims on Buffalo Bayou made to the Federal Emergency Management Agency. Barker Reservoir, south of Interstate 10, and Addicks Reservoir, north of the highway, are the green spaces on the left. Courtesy of Matthew Berg, Simfero Consultants

 

Blaming the Bayou. “Kinks” and “Bottlenecks” Downstream

This six-mile stretch of the bayou upstream of the beltway was straightened and shortened by the Corps of Engineers more than seventy years ago. The bayou downstream of the beltway remains a meandering stream, largely unchannelized, twisting and turning its way nearly to Shepherd Drive. Below Shepherd the bayou was stripped and channelized in Buffalo Bayou Park by the Corps in the Fifties. From there it flows along a heavily altered route through downtown, eventually becoming the Houston Ship Channel.

In the wake of this disastrous flooding upstream of the beltway, distraught and shell-shocked property owners, many of them without flood insurance and dealing with severe losses, have been blaming the “kinks” and “bottlenecks” in the meandering bayou below Beltway 8 for flooding their homes. The belief is that the meandering bayou constricted the flow and caused water to backup and flood property upstream. The common complaint is that the bayou downstream is too narrow and is “like a hose” that gets a “kink” in it, causing the water to stop and back up.

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6 thoughts on “Did Straightening Upper Buffalo Bayou Make Future Residents More Vulnerable to Flooding?”

  1. Grant says:

    Whatever the validity of the conjectures made in this article, the facts presented about the extent of Harvey flooding are factually wrong and grossly exaggerated. The maps suggest, for example, that all of Barkers Landing and Nottingham Forest were underwater, which isn’t even close to being true. The actual numbers were closer to 15% and 50%, respectively.

    This article also suggests that, following straightening of Buffalo Bayou in the 40s, homes and neighborhoods were built right up against the straightened bayou. This is true in some areas, but certainly is not the case for the majority of the neighborhoods along the bayou. Most of this stretch of the Bayou is abutted by the large open fields and green space of Terry Hershey Park. Even if the capacity of the stream itself is reduced compared to its natural state, to say that the total capacity of the system is reduced without accounting for the capacity of the abutting green space is disingenuous.

    1. Thanks for your comment, Grant.

      Not sure which maps you are referring to. There is a map of flood damage claims made to FEMA with the red areas. That was created by hydrologist Matthew Berg. There is also a map of projected inundation created by the Harris County Flood Control District.

      Nowhere does the article say that “homes and neighborhoods were built right up against the straightened bayou.” It says that “residences have been built on top of or very close to the historic path of the straightened bayou …” That’s a reference to the former meandering channel and remnant oxbows.

    2. Tom Helm says:

      Hi Grant, thanks for reading Save Buffalo Bayou’s posts. I’m a geologist, and in late 2016 did a study of the locations of the old meanders of Buffalo Bayou. This may be of interest to you. http://texasriparian.org/wp-content/uploads/2017/01/short-version-Searching-for-the-original-meanders-of-Buffalo-Bayou-final-reduced.pdf

      1. Thanks for pointing that out, Tom. Very informative research, as always. The link to that important study was sort of buried under “meanders” in the section “Making Room for the River.” Easy to miss.

        Rivers have a memory. Tom has shown how Buffalo Bayou seeks to restore its natural path. And how constantly spending public funds to fight that is futile, wasteful, and counterproductive.

  2. Kay Yates says:

    Please, Save Buffalo Bayou, would you send a copy of this excellent article to developer Brad Freels, Board Member of TIRZ 17, and to TxDot Houston Chief Engineer Quincy Allen. These two entities, TxDot and TIRZ 17, are planning to divert the Sam Houston Tollway trunkline that drains the Beltway 8 system into Tributary W-153, and that’s not all.

    In addition to the trunkline, they plan to dump the storm water run off from CityCentre and Town & Country Village into Tributary W 153. Also the Attingham Basin which drains the commercial street of Town & Country Way and the Mac Haik dealership. Also a 3-foot diameter culvert to divert storm water run off into W 163 from the Memorial Herman hospital complex which now floods Frostwood.

    It would be thoughtful if TxDot would mail legal notices to their intended targets: the residences that adjoin W 163, but TxDot has not yet done so. It would be nice if TxDot had announced their intention to divert this massive volume of storm water run off before the 800 residents that adjoin W 153 rebuilt their flooded homes after Harvey, but the bureaucrats have failed to do so.

    1. Will do! Thank you for the information.

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