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April 2012  | February 2012  | February CHARTING BUFFALO  | January 2012  | March 2012  | May 2012



If you have walked along Buffalo Bayou on the northern bank next to the Dairy Ashford bridge since early April, you have probably noticed the segment of bank sliding down, or "slumping" into the channel. 

The second edition of Slope Stability and Stabilization Methods states: "Sudden drawdown is a rapid lowering in the level of water standing against a slope. This particular situation is commonly encountered in a design of bridge approach embankments at river crossings. In such a case, rapid drawdown occurs when the river falls following a flood. Other examples of sudden drawdown include the lowering of a reservoir adjacent to the upstream slope of an earth dam, lowering of the water level next to a natural slope, and a drop in the sea level next to a slope. Most of the highway slope failures due to sudden drawdown occur at stream crossings. 

Failures due to sudden drawdown often occur in embankment slopes composed of clayey materials in which the excess pore water pressures do not have enough time to dissipate, thereby reducing the overall shear strength of the clay materials. Undrained shear strength is lower than drained shear strength. Also, the water acts as a stabilizing pressure against the slope face when in place. If the water level against the slope face is suddenly drawn down, this stabilizing pressure is removed suddenly, but the driving forces within the slope are relieved much more slowly, creating an unbalanced condition."*

In other words, if the dam gates are shut off too rapidly, the banks of the bayou may loose strength and stability, and segments of the bank may slide down into the channel.  By scrolling down, you will see images of slope failure near the Dairy Ashford bridge and charts indicating the sustained high flow rates and water levels at the bridge preceding the sudden drawdown and then collapse in the early part of April.  If you scroll further down, you will be able to compare videos of the high flow rate and low flow rate and be directed to links for information regarding why the high flow rates are taking place.

Building in-line detention in Terry Hershey Park will do nothing to halt the destructive effects of sudden drawdown.  In-line detention is designed to accept water at an elevation well above the level being inundated by the Corps controlled releases.  Tackling sudden drawdown requires a comprehensive plan incorporating the flow mechanics of the Barker and Addicks Dams.


VIDEO - On the banks below the Dairy Ashford Bridge
in Terry Hershey Park - High Release - March

Video - On the banks below Dairy Ashford Bridge
in Terry Hershey Park - Low Release - May

See the March portion of "On the Bayou" for links to the Interim Action Plan and an explanation for why the bayou is experiencing periods of high release.

Abramson, Lee W., Thomas S. Lee, Sunil Sharma, Glenn M. Boyce.  Slope Stability and Stabilization Methods: 2nd Edition.  New York: John Wiley & Sons, Inc., 2002


Briar Forest Super Neighborhood Council President Greg Daniell, Secretary and Stormwater Committee Chairman Allen Kelley and Greater Houston Off Road Biking Association President Bill Rustam met with Congressman Culberson to discuss at length the Clodine Waterhole Regional Detention Basin proposal and to request the Congressman's participation and leadership in bringing about a round table meeting.  Copies of some of the documents given to Congressman Culberson during the discussion are linked below as are images of the discussed topics.

All three local leaders stressed the importance of bringing together the listed subject matter experts to discuss a comprehensive plan for moving forward on issues related to future water needs, for reducing flood damage and to make a determination of responsibility for implementing planned objectives.  Congressman Culberson very clearly and repeatedly stated he would do all he could within his power to "fill the glass", meaning provide federal funding for the proposed Clodine Waterhole Regional Detention Basin up to an "80/20" deal (with 80% being federal funding). 

The Congressman raised the 10th Amendment and stated his continued participation would be contingent upon the requests of the relevant local government entities.  As shared earlier in "On the Bayou", District G Council Member Oliver Pennington has met with the Congressman and has enlisted the aid of Akin Gump in drafting legislation for the Congressman to use in obtaining funding for the Clodine Waterhole Regional Detention Basin.  In addition, at the Congressman's request, the BFSNC President provided Precinct 3 Commissioner Steve Radack with a copy of information discussed during the meeting and requested the Commissioner to give the "green light" to the Congressman to work on the objectives discussed during the meeting.

Meetings are also planned with Congressman Green, Congressman McCaul, Congressman Olson and Congressman Paul.





Longpoint Slough (the basin location would be to the right)



The Greater Houston Off Road Biking Association (GHORBA) has been busy working on the Anthills Trail to upgrade and build new bridges and improve the quality of the trails.  GHORBA was awarded a $10,000 REI grant to help accomplish their goal of building and maintaining sustainable multi-use trails.  GHORBA was formed in September 1999 when the Houston Area Mountain Bike Riders Association and the Memorial Park Mountain Bike Association joined forces to save the trails in Memorial Park from closure to all cyclists.  Over the years, GHORBA has expanded trail interests to dozens of Houston area mountain bike trails.  GHORBA is helping to renovate and improve the decades old Anthills trail network with the goal of making it a more enjoyable asset for all trail users.  Many of GHORBA's dedicated volunteers have come out over the past few weeks to haul wood, tools and other materials great distances into the forest and build some impressive and highly appreciated bridges.  In the near future, several kiosks with maps of the trail system will be added.

Please always remember to keep your eyes and ears open on the trail and let people know you are present when approaching blind corners, going down or up hills, or passing.  By communicating with your fellow trail users and exercising common courtesy, you are helping to keep the trail safe and enjoyable for everyone.  Please keep in mind that the trails in the Houston area are susceptible to increased erosion and damage after it rains.  All trail users can help to keep the trail in top condition by allowing the trails to dry out before biking, running or hiking after a rainstorm.  Please also always pack out what you bring in.  Keep the trails a friendly and beautiful place to share.  If you are interested in helping to maintain the Anthills, please consider joining thp-trailwork@googlegroups.com.  To learn more about GHORBA and to become a member, visit their website.



Video - GHORBA bridge building











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