Hydraulic engineers Alam and Willson use physical modeling to test river management measures

Sidney A. Murray Low Head Hydroelectric Plant, foreground, part of the Old River Control Complex, Simmesport, Louisiana

The February 2009 edition of the quarterly publication Louisiana Civil Engineer features two related articles that should be of great interest to readers of this blog.  They both pertain to the challenge of designing a new way to manage the lower Mississippi River to retain the 140 million tons of sediment that is currently disappearing into deep water every year.  

The cover article is by Sultan Alam, Hydraulic Engineering Consultant, and the related article is by Clint Willson, PhD, PE, LSU associate professor of civil engineering.  Both articles describe the design and operation of what is called a small scale physical model of the lower Mississippi River. This unique tool, which was designed by Alam, is housed at LSU and managed by Willson.  In his article Alam describes creating a similar physical model of part of the Old River Control Complex to overrule critics of the design of the hydroelectric power plant, which is shown in the above photograph.  

I recently reminisced about my youthful love of model ships, trains and planes and I noted that in today’s world models that simulate the behavior of real world objects or systems are primarily constructed of mathematical algorhythms interpreted by digital computers producing endless series of zeros and ones. Such numerical models can perform extraordinary feats, including calculating the trajectory of a meteorite that could collide with earth centuries from today.

Nevertheless the science of simulating the behavior of chaotic fluid systems, such as turbulent river water carrying sediments, is not a precise science – it requires lots of approximations.   For that reason, with respect to predicting the detailed behavior of flowing water and sediments there are still a few old school proponents of the use of physical simulation models, in addition to numerical simulation models.  Sultan Alam is one of those proponents.  

Physical models that use geometrically accurate scaled down reaches of river beds with real flowing water have several obvious advantages over numerical modeling.  To observe water flow and sediment erode and accumulate under the influence of actual gravity confers a visual credibility that the most sophisticated mathematical models lack.  In addition, physical models are easy to manipulate like sand boxes, using trial and error experiments that can quickly and cheaply test alternative management strategies.

Experiments using physical models also have great public relations value and persuasive power with respect to critical stakeholders and policy makers who may be uncertain about signing on to expensive and politically sensitive public works projects that change familiar conditions.

The lynchpin of comprehensive coastal restoration for the deltaic plain is the diversion of most of the river flow upstream of Head of Passes.  Achieving approval among stakeholders for such a radical change in management of the lower part of the largest river in North America will require an extraordinary “marketing” campaign.  I believe that a working physical model of the lower river (a larger and more sophisticated version of the existing model) will be a necessary part of that campaign. 

I predict that the final management design for the lower river will be based on a combination of physical and numerical modeling and I hope that Sultan Alam oversees the physical modeling component of that effort.  I also hope that Clint Willson’s considerable skills and experience are utilized for the same effort.    

The person who deserves credit for recruiting both Alam and Willson to consult on delta management is Chris Knotts, PE, the president-elect of the Louisiana Section, American Society of Civil Engineers. Chris serves as the director of the engineering division of the newly-formed Louisiana Office of Coastal Protection and Restoration.  

Len Bahr

1. Leland says:

   January 16, 2012 at 8:08 am

   Exactly what did all these politicians wonder might probably come about to our credit scores when these individuals carry on along the lines of poker players with our financial state? they have behaved the same as spoiled young kids and must be relieved they are not swinging from lampposts for their diabolical thought patterns.

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2. HeidiHoe says:

   March 14, 2009 at 10:10 am

   what “models” have others such as the Waterways Experiment Station (now ERDC) developed of this area?

   I would assume that Vicksburg staff has done both “physical modeling” and “numerical modeling” of these significant features.

   I believe in the past that the concurrent utilization of the physical/numerical model combination was possibly called “hybrid modeling.” Both systems have their strong and weak points but together provide valuable insights.

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3. sultan alam says:

   March 13, 2009 at 9:21 am

   From experience it may be confirmed that state-of-the-art physical hydraulic modelling not only allow us to design hydraulic structures correctly, it also often enables lot of savings and not build structures which does not work!

   Sultan Alam.

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4. HeidiHoe says:

   March 13, 2009 at 7:33 am

   At M.I.T. also cutting edge research is presently being done with some interesting results and questions being asked:

   http://www.dailygalaxy.com/my_weblog/2009/03/scientists-at-m.html

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