Federal Project in Late Forties Reduced Bayou Capacity Upstream
October 29, 2018
(Update Nov.13, 2018: Harris County Commissioners’ Court approved a $350,000 contract to study “high-flow bypasses” through meanders on Buffalo Bayou as well as the impact of existing bridges.)
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.)
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.