Magic Fish and Failed Erosion Control

On Buffalo Bayou

 

Jan. 28, 2018

We paddled down Buffalo Bayou recently to see what we could see. It’s been a hard winter, and the worst flood in history, so it wasn’t glamorous. We did encounter a couple of fish, a lot of trash and mussel shells still, some fallen trees and wayward telephone poles, and numerous examples of expensive landscaping and erosion control projects gone wrong.

Note to property owners, public and private: we have slumping on Buffalo Bayou. Banks will slide down and away, especially if you remove trees and vegetation, landscape, irrigate, and build too close to the bank. Not much to be done about slumping, which is vertical erosion. Try to convince your neighbor not to armor their banks with concrete, rubble, or sheet metal, which will only make things worse for you and everyone else.

We put in at muddy Woodway in Memorial Park for a trip all the way past the park, the Hogg Bird Sanctuary, and Buffalo Bayou Park, taking out below the Sabine Bridge. It wasn’t easy getting our canoes there. Some cursed coincidence (cold weather?) had caused all kinds of vehicles to break down at the last minute.

Where Does All That Sediment Come From?

There was still a large amount of sediment piled up high on the banks. Rivers naturally deposit sediment on the banks and floodplain. It’s why floodplains are so fertile. (And why in ancient times people wisely moved out of the way of floods.) But people have been asking where all this sandy sediment comes from. Some of it washes out from landscaping and construction sites and other areas that have been disturbed. But erosion is a natural evolutionary process. Here is geologist Tom Helm, who was leading our expedition, explaining the origin of sand and the different kinds of sandstone in Buffalo Bayou.

Geologist Tom Helm explains sandstone and sediment in Buffalo Bayou. 1.21.18

 

The Fish That Didn’t Speak

On one of the new gravel bars, there was a fish, newly dead, it would seem, as its eyes were still clear. Looked sort of like a bass, but this was a Rio Grande Cichlid, according to Tom. Unfortunately being dead for some reason, it was unable to speak or grant us any wishes.

 

Rio Grande Cichlid on a gravel bar of Buffalo Bayou in Memorial Park, 1.21.18

 

Further downstream, on the growing bank of the meander at the eastern edge of Memorial Park, we encountered tracks of busy beavers dragging their tails and building materials on the steep sandy bank. We also discovered another fish, this one alive but sluggish, oddly resting, slightly gasping, on the bank. This gaudy black-and-white striped fish with sharp, lacy fins clearly did not belong here. And indeed it was an exotic invader, said Tom, an armored catfish, probably descended from an aquarium. We didn’t ask it for anything.

 

Suckermouth catfish, a member of the armored catfish family, on a sandy bank of Buffalo Bayou in Memorial Park, 1.21.18

 

Failed Erosion Control

Sadly, we also documented a great many failed erosion control projects, as well as sheet metal and concrete projects that, if they didn’t fail in place, likely caused damage to their neighbors upstream, downstream, and across the way. Such is the dynamic of hardened banks on a flowing stream.

What does Save Buffalo Bayou recommend? We recommend leaving vegetation in place in order to anchor the bank. We recommend not digging up or running heavy equipment over the banks. And if your bank has slumped away, we recommend leaving fallen debris in place to collect sediment and naturally rebuild. Be patient. Stand back. You can try installing brush mattresses constructed of live branches to reinforce the bank and mimic this natural process. (See links to slumping above.)

Here are some expensive methods that didn’t hold up to Harvey and may also have made things worse for everyone else.

 

  • Slumping next to and behind a recently installed sheet metal retaining wall in Uptown Park on the south bank of Buffalo Bayou. Photo 1.21.18
  • A closer view of slumping adjacent to a new retaining wall in Uptown Park. Photo 1.21.18
  • Slumping concrete riprap on a denuded bank of the River Oaks Country Club Golf Course downstream from Memorial Park. Photo 1.21.18
  • This method didn't work either.
  • The south-facing high bluff in the Hogg Bird Sanctuary, a city park on Westcott Street. Photo 1.21.18
  • Riprap, concrete bags, and concrete puzzle block all slid away.
  • A wealthy developer dumped all this concrete construction trash on the bank of his property on Buffalo Bayou in 2016. Photo 1.21.18
  • This concrete puzzle block is still there. This extensive armoring of the bank also provoked complaints from neighbors when it was installed in 2016. Photo 1.21.18
  • Downstream parts of the puzzle block haven't held up so well.
  • Slumped backyard garden wall in River Oaks. 1.21.18