University of Houston study shows no linkage between deep groundwater production and subsidence in Montgomery County

Hydrogeologic section of Montgomery County and Gulf Coast aquifer system. It’s important to note that the Jasper aquifer is much closer to the surface in Montgomery County than it is closer to the Gulf Coast. It’s also important that the Burkeville Confining Unit, composed of dense clays, lies above the Jasper and prevents water movement as well as prevents horizontal movement of the layers below it.

Montgomery County, July 25 – While neither property rights advocates, Board members of the Lone Star Groundwater Conservation District, nor San Jacinto River Authority General Manager Jace Houston and his pro-surface water allies have mentioned it, there’s actually an extremely important scientific article which appeared in the International Journal of Geophysics, a highly-respected academic journal, concerning the relationship between extraction of groundwater from deep layers in the Gulf Coast aquifers and subsidence. They concluded that there is no subsidence from groundwater production from the Jasper aquifer within the Fleming Formation.

That’s an extraordinarily important scientific conclusion in the peer-reviewed, data-intensive article, because it basically suggests that Montgomery County utilities, municipalities, homeowners associations, and other large-scale groundwater users could draw water production from the Jasper acquifer without causing any subsidence at the surface of Montgomery County. It also suggests that, as long as groundwater production comes from the Jasper or lower formations (such as the Upper Catahoula Formation), there is little need, if any, for any groundwater regulation whatsoever.

The article is “Is There Deep-Seated Subsidence in the Houston-Galveston Area?” by Jiangbo You, Guoquan Wang, Timothy J. Kearns, and Linqiang Yang of the Department of Earth and Atmospheric Sciences of the University of Houston. The International Journal of Geophysics published the article on July 2, 2014.

Dr. Jiangbou and his research team concluded that “We conclude that recent subsidence (1993–2012) in the Houston-Galveston area was dominated by the compaction of sediments within 600 m below the land surface. Depending on the location of specific sites, the compaction occurred within the Chicot aquifer and part or all of the Evangeline aquifer. No measurable compaction was observed within the Jasper aquifer or within deeper strata. Deep-seated subsidence is not likely occurring in the Houston-Galveston area.”

“We conclude that recent subsidence (1993–2012) in the Houston-Galveston area was dominated by the compaction of sediments within 600 m below the land surface. Depending on the location of specific sites, the compaction occurred within the Chicot aquifer and part or all of the Evangeline aquifer. No measurable compaction was observed within the Jasper aquifer or within deeper strata. Deep-seated subsidence is not likely occurring in the Houston-Galveston area.” – – Jiangbou You, Guoquan Wang, Timothy J. Kearns, and Linqiang Yang of the Department of Earth and Atmospheric Sciences of the University of Houston, 2014.

The University of Houston researchers took long-term groundwater and land subsidence monitoring data in the Montgomery County, Houston, and Galveston areas from the period of 1993 to 2012 and concluded:

  • The groundwater head has actually been increasing during that time period in the Chicot and Evangeline aquifers closer to the Earth’s surface. The earth scientists believe that groundwater regulation of those more shallow aquifers might make sense and had something to do with the increase in the groundwater head.
  • Overall land subsidence rates in the Gulf Coast area has been decreasing during that time period.
  • A review of 13 borehole extensometers and 76 GPS antennae properly mounted to take such measurements in the Greater Houston Area revealed that subsidence has declined and is completely unrelated to groundwater production below the Burkeville Confining Unit, a thick clay formation.
  • The Jasper aquifer is not hydrologically connected to the Evangeline aquifer, because the Burkeville confining layer greatly restricts the vertical flow of groundwater from one aquifer to the other.
  • The confining features of the Burkeville, therefore, reveal that groundwater production below the Burkeville Confining Unit will not result in horizontal shifting of subsurface strata, so that subsidence of the Earth’s surface would not occur.
The University of Houston researchers developed this map showing the reduction in subsidence rates from 2006 to 2012.

This study contains profound analysis and conclusions. Since the quantity of groundwater in Montgomery County is essentially unlimited, and since Montgomery County aquifers enjoy almost 100% recharge annually after production drawdowns have occurred, there would seem to be no reason whatsoever to regulate groundwater production from the Jasper aquifer and the Catahoula aquifer.

Why should Montgomery County citizens care?

Because Montgomery County water prices have skyrocketed since 2009, when the Lone Star Groundwater Conservation District, working closely with the San Jacinto River Authority (SJRA) began heavily restricting and regulating groundwater production and drove water users, especially utilities, municipalities, property owners associations, and others to have to purchase water supplies from the extraordinarily-expensive SJRA. SJRA has created a regulatory-induced monopoly which has forced water purchasers to buy surface water from that state agency rather than from much less expensive groundwater sources.

The University of Houston study suggests that it’s time for the Lone Star Groundwater Conservation District to bring the entire over-regulation of groundwater to a crashing halt.

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