![\"\"](\"https:\/\/www.savebuffalobayou.org\/wp-content\/uploads\/2017\/08\/Looking-US-Bend-2.jpg\")
<\/a>This steep, high bank in Memorial Park slumped after the Memorial Day 2015 storm, taking plants and bushes with it. Photo by Susan Chadwick looking upstream on April 10, 2017.<\/p><\/div>\n
Engineers Mistake Slumping for Erosion<\/strong><\/h4>\nBut the engineering consultant working for the flood control district describes what is happening to the high banks of the bayou in the project area as \u201cshear stress,\u201d which is the lateral or parallel drag of the water flowing past the banks and down the channel.<\/p>\n
The district\u2019s permit application<\/a> to the Corps of Engineers repeatedly refers to shear stress and shear stress only, specifically ruling out vertical instability. (\u201cVertical stability not an issue.\u201d P. 39.)<\/a> The Corps\u2019 Environmental Assessment<\/a>, released in May in conjunction with the granting of a permit for the project, also refers exclusively to shear stress.<\/p>\n\u201cThe assessments conducted by HCFCD’s design team indicated that due to the erosive nature of high flows in the bayou \u2026 hydraulic energy dissipation measures (bankfull benches, pool and riffle reestablishment<\/a>, channel pattern adjustments, and in-stream structures) were necessary in the design to relieve shear stress on the streambanks of the bayou, and ultimately stabilize the channel system,\u201d stated the Corps on page 21 of the Environmental Assessment<\/a>.<\/p>\nThe Corps\u2019 Environmental Assessment found that the proposed project, which would use heavy equipment to raze most of the trees and vegetation and dredge, fill, reroute, and reconfigure the channel, historic high banks and meanders of more than a mile of forested Buffalo Bayou flowing past Memorial Park, would have no significant impact on the environment.<\/p>\n
Remedy Decided Before Problem Was Analyzed<\/strong><\/h4>\nBut Flood Control\u2019s project, known as the Memorial Park Demonstration Project, is based on an error. Shear stress\u2014lateral erosion\u2014isn\u2019t the primary problem in this stretch of Buffalo Bayou. Slumping\u2014vertical instability\u2014is what naturally happens on our 18,000-year-old bayou. (And it’s only a “problem” if you, say, unwisely took down the trees and built your house or your mowed golf course on or near the edge of a bank.)\u00a0 The project will do nothing for slumping, for which there is little remedy anyway.<\/p>\n
Even worse, the proposed \u201cin-stream structures\u201d\u2014wads of tree roots to be installed to \u201cstabilize\u201d the toe or bottom of the banks to protect them from shear stress\u2014will likely also slide away<\/a>.<\/p>\nThe controversial project, not yet under construction, is based on a mistake. And it probably will fail, leaving behind a wasteland of denuded and weakened banks. That has happened elsewhere<\/a> with these controversial Natural Channel Design methods<\/a>. (See also here<\/a>.)<\/p>\nThe promoters of the project, who include the Bayou Preservation Association<\/a> and the Memorial Park Conservancy<\/a>, decided years ago to use Natural Channel Design to \u201cfix\u201d the bayou and demonstrate what they believed to be a superior method of erosion control.<\/p>\nThe remedy was decided before the engineering consultant, Kellogg Brown and Root (KBR), or apparently anyone else, had done an analysis of the problem. \u00a0Except that the same engineering firm, or its predecessor, Brown and Root (BR), had done a study in 1995, almost twenty years earlier. That study came to somewhat different conclusions: vertical stability was an issue.<\/p>\n
\u201cThe assessments conducted by HCFCD’s design team indicated that due to the erosive nature of high flows in the bayou \u2026 hydraulic energy dissipation measures (bankfull benches, pool and riffle reestablishment<\/a>, channel pattern adjustments, and in-stream structures) were necessary in the design to relieve shear stress on the streambanks of the bayou, and ultimately stabilize the channel system,\u201d stated the Corps on page 21 of the Environmental Assessment<\/a>.<\/p>\n The Corps\u2019 Environmental Assessment found that the proposed project, which would use heavy equipment to raze most of the trees and vegetation and dredge, fill, reroute, and reconfigure the channel, historic high banks and meanders of more than a mile of forested Buffalo Bayou flowing past Memorial Park, would have no significant impact on the environment.<\/p>\n But Flood Control\u2019s project, known as the Memorial Park Demonstration Project, is based on an error. Shear stress\u2014lateral erosion\u2014isn\u2019t the primary problem in this stretch of Buffalo Bayou. Slumping\u2014vertical instability\u2014is what naturally happens on our 18,000-year-old bayou. (And it’s only a “problem” if you, say, unwisely took down the trees and built your house or your mowed golf course on or near the edge of a bank.)\u00a0 The project will do nothing for slumping, for which there is little remedy anyway.<\/p>\n Even worse, the proposed \u201cin-stream structures\u201d\u2014wads of tree roots to be installed to \u201cstabilize\u201d the toe or bottom of the banks to protect them from shear stress\u2014will likely also slide away<\/a>.<\/p>\n The controversial project, not yet under construction, is based on a mistake. And it probably will fail, leaving behind a wasteland of denuded and weakened banks. That has happened elsewhere<\/a> with these controversial Natural Channel Design methods<\/a>. (See also here<\/a>.)<\/p>\n The promoters of the project, who include the Bayou Preservation Association<\/a> and the Memorial Park Conservancy<\/a>, decided years ago to use Natural Channel Design to \u201cfix\u201d the bayou and demonstrate what they believed to be a superior method of erosion control.<\/p>\n The remedy was decided before the engineering consultant, Kellogg Brown and Root (KBR), or apparently anyone else, had done an analysis of the problem. \u00a0Except that the same engineering firm, or its predecessor, Brown and Root (BR), had done a study in 1995, almost twenty years earlier. That study came to somewhat different conclusions: vertical stability was an issue.<\/p>\nRemedy Decided Before Problem Was Analyzed<\/strong><\/h4>\n