Tag Archive for: Gibbs

99% Solutions to a 1% Problem Are No Solutions at All

Today, I read a scientific article that talked about 99% solutions to 1% problems. It hit me between the eyes with the force of a freight train. It was written 30 years before Hurricane Harvey for a 1987 symposium sponsored by the U.S. Navy called Sedimentation Control to Reduce Maintenance Dredging of Navigational Facilities in Estuaries.

“SESSION A: SEDIMENT SOURCES AND TRANSPORT PROCESSES”  made months worth of arguments, complaints and frustrating meetings suddenly fall into sharp focus. I quickly realized our problem.

I can’t post the paper here for copyright reasons. So I will link to it and quote brief passages in a review. The author was Ronald J.Gibbs, Center for Colloidal Science, College of Marine Studies, University of Delaware.

His paper begins by looking at the largest rivers in the world and rank ordering them by their discharge (flow) rates. He then talks about factors that influence sedimentation, such as soil types, river gradient, and weather events. 

Rare Weather Plays Mammoth Role in Sedimentation

In case after case, extreme weather played a hugely dominant role in sediment transport. For instance…

…in one storm on the Delaware River, a two day discharge represented three full years of average discharge.

An even more spectacular example: a storm struck the Eel River in California. “In a three day period, the Eel River carried more sediment past Scotia, California than it had during the previous seven years.”

In ten days, the transport was equivalent to the previous ten average years.”

“To put this into perspective, the total suspended discharge for the Eel River was 168 million tons that year, which compares with the 184 million tons carried by the Mississippi River past St. Louis during the same year.” I had never even heard of the Eel River, so this caught my attention. 

Difficulty of Measuring

The authors’ point: This tremendous variability, occurring over a period of many years, is exceedingly difficult to sample and to understand because it is normally very expensive to prepare for sampling these types of rare events. However, sudden events are extremely significant in terms of quantity of sediments discharged…”

A Storm Like Harvey 

Another example: the Susquehanna, which flows south through eastern Pennsylvania before entering Maryland and Chesapeake Bay. Gibbs referenced another study that estimated sediment discharged in one week (June 22–28, 1972) during a major storm. “The Susquehanna River probably discharged greater than 50 x 10(6) metric tons of suspended sediment than had been discharged during the past three decades, and probably even during the past half century.” 

50 million more tons of sediment in one week than during the previous fifty years!

Annual Patterns Follow Extremes, Too

Gibbs looked at both extremely rare events like this and typical annual patterns. He found that,

“During 1 percent of a year (3.6 days), most rivers discharge better than one-half to two-thirds of their sediments for that year.”

These observations illustrate how important rare events are in transporting sediment. Gibbs says, “They dominate deposition over many years and greatly affect dredging and shoaling activities.”

I knew that most sediment transport happened during floods. But I until I read this study, I did not understand how extreme the disparities between normal and flood transport were.

Implications for Regulators and Legislators

Suddenly, the tumblers clicked into place. I understood why the Brown & Root study quoted sediment transport figures for the West Fork, Spring Creek and Cypress Creek, and then told people to ignore them; they measured suspended solids when the streams were moving only at about 60 cfs, not 131,000 cfs as during Harvey. 

Suddenly, I also understood how TACA, the TCEQ and state legislators could conclude that mining in floodways was OK. They look at the 99%, not the 1%. But the 1% is when all the damage occurs.

As a business person, I might have made the same mistake. Conventional wisdom dictates that you design systems for the 99%, and that you’ll go broke chasing that last 1%. Or more to the point, the last .2%.

Design for Disaster: The 1% Solution

Very few industries design for extreme events. In the airline business, the cost of a crash is unthinkable. Nuclear power plants simply cannot go out of control.  Every pacemaker has to work. For almost everything else, 99% success gets you a nice Christmas bonus and a promotion. But when the cost of failure is a major portion of the nation’s fourth largest city…

As a legislator, you listen to the carefully crafted arguments of TACA and say to yourself, “This was a force majeure event, an act of God. We can’t ask them to design their mines for that. They’ll go broke!” And you never stop to think, “Yes, I can. No, they won’t. It’s simple. I ask them to move out of the floodway. It doesn’t cost them a dime out of pocket. They just don’t mine so close to the river.”

At least you don’t realize it’s that easy until the sediment sent downstream by Hurricane Harvey dams the river and contributes to wiping out 16,000 homes, 3,300 businesses, a college, a high school, a hospital, a fire station, entire subdivisions, and entire shopping centers. Repairs for all of the above also wiped out billions in equity, college funds and retirement savings.

We Need to Fix A Business Model that Destroys Growth

If that doesn’t move you, consider that it also slowed the growth of an area from 6% to 1%. That’s what happened in the Humble ISD right after voters approved a  $575 million bond referendum.

Attention: governor, developers, aggregate producers, concrete manufacturers, legislators, mayors, city council members, county commissioners, chambers of commerce, do you really want to bet on a business model that destroys growth?

Sometimes, it makes more sense to think of the 1% solution than the 99%. This is one of those times. In fact, the 1% is the ONLY thing we should be focusing on as we consider legislation to fix the broken sand mining model. What good is building cheap roads if you drive residents to move out of state?

These are my opinions on matters of public policy and protected under First Amendment of the U.S. Constitution and the Anti-SLAPP statute of the Great State of Texas.

Posted by Bob Rehak on 12/16/2018

474 Days since Hurricane Harvey