Dickinson Bayou

The sun reflects off Dickinson Bayou near state Highway 3 on Oct. 18. Some argue dredging and detention ponds around the bayou could have helped mitigate flooding during Hurricane Harvey.

The idea may seem attractive on paper and this soon after a horrible flood, but dredging Dickinson Bayou probably would be the worst way to keep future torrential rains from doing as much damage as happened during Hurricane Harvey.

Some people, when they imagine a dredged bayou, probably see the same scenic, meandering waterway offering the same recreational opportunities as exists today, only somehow much better able to move vast amounts of water very quickly.

It seems unlikely, however, that a minimal dredging project, one that left the bayou more or less in its natural form, would do much to reduce flooding.

Deepening the channel might help some, as would widening it and clearing the mouth, where the bayou enters Dickinson Bay, Jack Murphy, chairman of the Dickinson Bayou Watershed Steering Committee, told The Daily News.

That wouldn’t solve the biggest problem, however, which, as Murphy pointed out, is that the bayou twists and turns along its way to the bay. Water heading for the lowest point during heavy rain is going to follow the straightest line, and that means flowing over land in the curves, Murphy said.

It’s just a fact that bayous are sluggish by nature. To make the channel faster, you have to make it straighter, as straight as possible, and remove things such as vegetation that tend to slow the flow.

Achieving a substantial increase in the flow rate probably would require something like the city of Houston has done to many of its bayous — deepening, widening, straightening, beveling the sides and lining them and the bottom with concrete.

If you want to see an example of that, visit White Oak Bayou in Houston. It’s still called a bayou, but it’s a huge concrete drainage ditch. It moves water relatively well, probably, but it’s no more a part of the natural environment than a 30-inch pipe in a storm sewer system.

The paradox is that attempting to engineer the bayou to be safe for people to live along, would turn it into something that very few people would want to live along.

“People want the natural components to survive — that’s why people live here,” Murphy said. “But it’s a dangerous thing to live next to.”

Meanwhile, it’s an open question whether destroying the bayou as a natural habitat with all the consequences for wildlife and people would achieve anything worth the cost and the loss. Houston has done a good deal of that, and still floods severely.

Such a project also would face opposition from several directions. Groups such as the Galveston Bay Foundation probably would oppose it, for example, as Scott Jones of the foundation told The Daily News.

“We’re open to different ideas,” Jones said. “We just always say there’s a burden of proof that you’re not going to ruin these tidal tributaries.”

And also, probably, would many people owning property along the banks of the bayou because a project that achieved a measurable reduction in flood risk would require them to give up some land.

The steering committee’s plan to buy land and build more detention ponds to capture and hold water after significant storm bursts is a better idea than dredging.

And as Jones pointed out to The Daily News, other less-engineered solutions should be considered, such as buyouts for repeatedly flooded properties and rules restricting building in floodplains.

• Michael A. Smith

Michael A. Smith: 409-683-5206; michael.smith@galvnews.com


(2) comments

Gary Miller

Some dredging of the area above Hwy 146 where a winding channel restricts flow could improve flow. Bypasses on the worst bends and turns as was done on Chocolate Bayou would speed up storm flow without disturbing the character of the bayou. The bypasses would only need to be deep enough to carry storm flooding not normal rain runoff.

Randy Chapman

Without changes of elevation, you can dig a waterway as deep as you want, and no improvement to drainage will occur. This area is too flat to improve drainage by simply digging deeper, straighter, or wider. Further north and west, where you have an actual useful elevation change between the bay and the drainage basin makes sense, but not at the coast.

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