Seitzinger Contributes Second Study on Harvey, Addressing Timing and Backwater Issues

David Seitzinger, P.E., a Kingwood-based engineer, has contributed another study to the discussion of Hurricane Harvey. He titled the first one, SJR Flooding: Causes, Impacts, Potential Solutions. The second, SJR Flooding: Water Levels, Flows and Timing, does an even deeper, 92-page dive into the data.

One of the backwaters identified by Seitzinger.

Scope and Purpose

Seitzinger states in the opening that flooding cannot be eliminated when you get as much rainfall as we did with Harvey. But then goes on to say that, “There may be ways to limit the flooded areas in future.” His paper is intended to provide a better understanding of what happened. He hopes this will help design remedies that make the area more resilient to flooding.

River Obstructions Creating Backwater Effects

Seitzinger identifies six river obstructions creating backwaters:

  1. The narrow Riverway near Lonestar College/Kingwood
  2. The I-69 Bridge
  3. A sand bar by the Kingwood Country Club
  4. The Stream Mouth Bar
  5. The 1960 Bridge
  6. The Lake Houston Dam

He then spends the next 70 pages analyzing what happened at each of these during the flood and developing various strategies to deal with them. He breaks his recommendations up into short- and long-term.

Short-Term Recommendations

Short term recommendations include:

  • Establishing a regional authority to provide multi-county coordination on legislative, operation, mitigation and funding efforts for flood control
  • Reviewing and updating SJRA and CWA water release protocols.
  • Installing additional water-flow and level gages on the tributaries and Lake Houston with predictive flow algorithm.
  • Providing a better flood warning system for the general public.
  • Reviewing and legislating new sand-mining procedures and enforcement fines to prevent sand loss into the rivers during high water
  • Reviewing communications. Include clear regional decision maker assignments and house-to-house warnings for all homes in the floodway and below the 100 yr. levels at a minimum
  • Removing West Fork sand bars to re-establish main channel flow
  • Annual West Fork maintenance dredging.

Long-Term Recommendations

Longer-range recommendations for investigation and implementation include:

  • Dredging to return channel depths in West Fork and East Fork to original depths
  • Adding additional, controlled, water-release capability to Lake Houston
  • Widening the 59 bridge and FM 1960 bridge channels
  • Widening the 59 bridge and West Lake Houston Parkway bridge entrance and exit channels
  • Stopping flood plain re-development west of Hwy 59
  • Setting new regulations for storm zoning and land reservation
  • Adding controlled storm reservoirs to Cypress, Spring, and Lake Creeks and East Fork
  • Develop public-private partnership for river-sand removal and reclamation.

Limitations of Study

Seitzinger’s presentation is very technical; it is not easy reading. He targets other engineers with this and requests peer review.

One thing that will require validation: his velocity calculations. They seem at odds with velocities reported by rescue workers. I talked to an HPD officer, for instance, who estimated velocity in the vicinity of the West Lake Houston Parkway Bridge at 10 to 20 miles per hour. By calculating peaks as they moved downriver, Seitzinger estimates 1.03 mph. The difference could have to do with water jetting through the bottlenecks that Seitzinger describes. Unequal distribution of rainfall across upstream tributaries could also affect offsets among downstream peaks. Regardless…

Value of Study

Seitzinger provides all the data for others to check his calculations. The main value of an effort like this is that it collects all the crucial data in one place for posterity, cross-examination and comparison.

Kingwood is lucky to have many talented engineers, such as Seitzinger. This should stimulate much discussion.

Posted by Bob Rehak on 3/8/2019

556 Days since Hurricane Harvey