Tag Archive for: Dupre

UH Geology Professor Weighs in with TCEQ on BMPs Related to Sand Mining

Professor Emeritus William Dupré, Ph.D., of the University of Houston’s Department of Earth and Atmospheric Sciences filed a 36-page report with the TCEQ on sand mining in the San Jacinto River Basin. Dupré has broard experience with geologic hazards and risk assessment. He submitted his report in support of the petition filed with the TCEQ by the Lake Houston Area Grassroots Flood Prevention Initiative to establish best management practices (BMPs) for sand mining.

The first issue that Dupré identified is flooding. “With one exception, all sand mines in the San Jacinto River Watershed are located partially or completely within the regulatory floodway, an area delineated by FEMA as having the highest potential for flooding (and erosion) along major waterways. “[T]he floodway is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles and erosion potential…”. (Montgomery County Flood Plain Management Regulations, 2014, p.25)

Floodway Constriction

Dupré notes that partitioning large areas of the floodway from rising floodwaters by levees and dikes can result in increased flooding of adjacent areas.

A good example: sand mines on the north side the San Jacinto West Fork and I-45 have walled off half the floodplain, forcing floodwaters onto neighboring property on the south side.

Sand mines have walled off more than 200 acres west of I-45 and north of the San Jacinto West Fork. See below.
The high dikes force floodwater to the other side of the river rather than allowing it to spread out on both sides. The concentration of water in a smaller area also increases the velocity and erosion. For close-up of area inside red circle, see image below.
This shows how high the dike around the sand mine is.

Levee Failure Can Flush Pollutants into Waterways

“Flood-induced breaches in levees can also add to the problems of flooding, erosion, and sedimentation downstream,” Dupré says, flushing sediment and other pollutants into adjacent land, wetlands, and waterways. See two examples below.

In the top row, river migration eroded the pit wall which allowed the contents to drain into the West Fork near North Park Drive. In the bottom row, the entire contents of a mine pit drained into the West Fork near Bennett Estates.

In-Stream Mining Disrupts River Habitat

A. Google Earth image of point bar on the west Fork of the San Jacinto River; B. Same bar 5 months later showing un-permitted (i.e. illegal) In-stream “bar-scalping.”

“Since the passage of Section 404 of the Clean Water Act Amendments of 1977, some states have heavily restricted or banned in-stream mining, as have many countries,” writes Dupré. “These restrictions are mainly based on the significant environmental problems associated with this type of mining.”

Such mining can create major disruptions of riparian habitats by increasing the amount of sediment put into suspension. “Major channel modifications can also occur, including upstream incision (headcutting) and downstream erosion and deposition.”

BMPs Can Make Compliance with Regulations More Efficient

In his paper, Dupré next examines applicable regulations and suggests several BMPs to supplement them. He recommends that:

  • All APO’s should develop and make available to regulators and the public a Comprehensive Mine Plan and an Environmental Assessment Report on potential impacts before permits are issued.
  • Likewise, all APO’s should develop and make available to regulators and the public a Reclamation Plan before permits are issued and file a performance bond ensuring reclamation before a production permit is granted. Such permits should have significant civil and criminal penalties for non-compliance.
  • New mining should be minimized or restricted in delineated floodplains and floodways and channel migration zones (areas most like to be eroded by lateral migration and river avulsion).
  • Mines should be “prohibited within the adopted regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses that the proposed encroachment would not result in any increase in flood levels…. A development permit must be secured from the Flood Plain Administrator prior to the placement of fill or other encroachment in the floodway….” (Montgomery County Flood Plain Management Regulations, 2014).
  • Stockpiles should be located outside the floodway, because of the high potential for erosion (and resultant sediment pollution) during frequent flooding.


Dupré acknowledges that aggregate mining clearly provides valuable material and employment to the state and nation.

Nonetheless, Texas is one of the few states where sand and gravel mines remain largely unregulated. Issues related to flooding, erosion, and sedimentation create many unintended (and undesirable) environmental and economic impacts associated with sand and gravel mines – especially in the San Jacinto River watershed. “I believe there is a clear need for the requirement for BMP’s to better protect the public and the environment,” says Dupré.

TCEQ Public Comment Period Rapidly Coming to a Close For Sand Mining BMPs

On November 11, the TCEQ held a public hearing on a joint proposal between TACA and the Lake Houston Area Grassroots Flood Prevention Initiative to establish best management practices for sand mining in the San Jacinto watershed. The public comment period closes on December 11, 2020 – in just 12 days.

If you want to weigh in on the subject, you can review presentations from the hearing here. TACA and the Lake Houston Area people are in substantial agreement on most points. However, they still differ on four key issues.

  • Where should the BMPs be enforced? On the main stems of the East and West Forks or on the smaller tributaries, too?
  • Should there be performance bonds for reclamation?
  • How far from rivers should the sand mines be set back for safety reasons?
  • Should compliance with best practices should be voluntary or mandatory?

If you have comments or questions for the TCEQ, please e-mail Outreach@tceq.texas.gov. Make sure to include “Sand Mining Rulemaking” in the subject line of your e-mail.

Posted by Bob Rehak on 11/29/2020

1188 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Flooding and Floodplains in the Houston Area: Past, Present, and Future

On August 24th, Dr. William R. Dupré , Professor Emeritus of Earth & Atmospheric Sciences from the University of Houston, gave a presentation at the Kingwood Community Center sponsored by the Houston Geological Society. The presentation is titled Flooding and Floodplains in the Houston Area: Past, Present, and Future. Professor Dupre’ has given ReduceFlooding.com permission to post his presentation. It consists of two parts. Together, they will help you understand how and why floodplains change over time.

Urbanization is just one of many factors cited by Dr. Dupré that increase flooding.

The Basics of Flooding, Floodplains and Measurement

In Part 1, Dupré focuses on the basics of flooding, flood plains and measurement.  He begins by explaining:

  • The difference between drainage basins, networks and watersheds
  • How stream gages work
  • How and where to find flood data (USGS, SJRA, Harris County Flood Warning System)
  • How to compare hydrographs from different locations and assess your risk of flooding
  • The difference between annual recurrence intervals and annual exceedance probabilities
  • How to understand flood maps
  • Assumptions behind flood plain calculations
  • Different types of flooding (overbook, ponding, sheet flow, etc.)

At the end of Part 1, Dupré shows how some of these concepts apply to different watersheds within Harris County and discusses how flooding dangers differ in various parts of the County.

How and Why Floodplains Change Over Time

In Part 2, Dupré goes into greater detail about how floodplains change over time.  The four main reasons include:

  • More data and a longer record
  • Changing land use, (i.e., urbanization, prairie restoration, etc.)
  • Structural changes (dams, levees, channelization and detention/retention basins)
  • Changing climate

Part 2 concludes with a discussion of changing approaches to flood control and a brief discussion of the recently approved Harris County flood bond.

Do Sand Mines Play a Role?

Part 2 includes a discussion of sand mining under “Causes of Changes in Sediment and Sedimentation. Dupré talks about different types of sand mines and their impacts. While the professor and I disagree about the interpretation of several satellite images, we agree wholeheartedly about the need to locate pits outside of a ‘channel migration’ zone, as regulations  in Washington state and Arizona require.

The danger, he says, is that rivers can migrate to and through sand mine dikes. If this happens after abandonment of the mine, no one will me there to repair the dikes and the river will reroute itself through the pit, carrying stored sediment downstream.

Who Will Benefit from This Presentation

If you enjoy earth sciences, as I do, these presentations will feel like going back to college. If you’re simply a homeowner trying to figure out why you flooded, you’ll find lots of food for thought in these two presentations. If you’re debating whether to buy flood insurance, these presentations will make you a believer.

Key Messages

One of the key takeaways from Part 1 is that you should not think of the 100-year (1%) floodplain as a bright line where you’re safe on one of it and not safe on the other. Dupré calls that choice a “false binary.” He urges people to think of flood plains as ever shifting and flood plain boundaries as very fuzzy lines, much like the cone of uncertainty used for hurricane path prediction. The width of the line represents the margin of error behind the calculation of probabilities.

After reviewing Part 2, you should come away with a better appreciation for how gradual, almost unnoticeable changes in your environment can increase your flood risk.

Related Reading

The points Dr. Dupré  makes support the conclusions drawn in a report by the Bayou City Initiative titled “Houston A Year after Harvey: Where We Are and Where We Need to Be,” especially the section on the need to revise outdated flood maps.

Remember Flood Control Presentation At Community Center on 9/17

Matt Zeve, Director of Operations for Harris County Flood Control, will also discuss flood map revisions in his upcoming talk at the Kingwood Community Center on September 17 at 6:30. Don’t forget to mark your calendar.

Posted by Bob Rehak on September 11, 2018

378 Days since Hurricane Harvey and 17 years since 9/11

Flooding and Floodplains in the Houston Area: Past, Present and Future

FEMA Flood Hazard Layer Viewer. Shows Humble-Kingwood-Atascocita-Corridor on West Fork of San Jacinto. Floodway (hatched), 100-year flood plain (aqua) and brown (500-year) flood plains are superimposed.

This Friday, from 7-9pm, Dr. William Dupre from the University of Houston Department of Earth and Atmospheric Sciences will conduct a  free Informational Workshop on flooding and flood plains sponsored by the Houston Geological Society. The event is free and open for the public.

Flooding in the Houston area over the last three years has caused residents and professionals alike to reconsider how we evaluate and respond to flood hazards in the region.
Dr. Dupre will discuss:
  • How watersheds and floodplains are defined and mapped
  • How individuals can obtain (and understand) information on local watersheds and floodplain maps
  • Recent floods, including how floods are measured and how flood frequency is calculated
  • How and why floods and floodplains in Houston have changed in the past, and are likely to change in the future
  • Possible approaches to reducing flood risk in the future.


Where:    Kingwood Community Center, 4102 Rustic Woods Dr, Kingwood, TX 77345

When:     Friday, August 24th, 7-9 PM

Speaker: Dr. William R. Dupre’, University of Houston, Dept. of Earth and Atmospheric Sciences

To reserve a seat: Please call the Houston Geological Society office (713) 463-9476 before 4 pm Thursday, August 23, or send your request to jajordan@hgs.org, and put “Kingwood Reservation” in the subject line.


Additional Information on Bond Proposal

The Harris County Flood Control District (HCFCD) Preliminary Draft of 2018 BOND PROPOSED PROJECTS is available at:the Harris County Flood Control District website.

The actual text of the Bond Proposal and Election can found at https://www.hcfcd.org/media/2855/bpl.pdf

This program is a community outreach effort by the Continuing Education Committee of the Houston Geological Society, the largest local geological society in the world.  The event is posted on their website.  Go to www.hgs.org; on the blue banner click on CALENDAR; on the Calendar page click on August 24.

Remember, the final day to vote for the flood bond is August 25, this Saturday, at your regular polling place. Please VOTE FOR it.

Posted by Bob Rehak on August 23, 2018

359 Days since Hurricane Harvey