Tag Archive for: Final Report

San Jacinto Regional Flood Planning Group Submits Final Recommendations

The San Jacinto Regional Flood Planning Group (SJRFPG) submitted its final recommendations to the Texas Water Development Board on January 10. The 316-page report includes recommendations on floodplain management evaluation, strategies and projects; the plan’s impacts; administration, regulatory and legislative recommendations; and financing.

I discussed the floodplain projects and impacts when I reviewed the draft plan in August of 2022. Not much as changed with the projects and impacts except for some minor details.

Now, with the state legislature in session, I would like to review the administrative, regulatory and legislative final recommendations in Chapter 8.

Legislative Recommendations

The SJRPG made four legislative recommendations to facilitate floodplain management plus flood mitigation planning and implementation.

Provide recurring biennial appropriations to the Flood Infrastructure Fund (FIF):

In 2019, the legislature appropriated money to establish the FIF. However, it did not appropriate additional funds in 2021. We need more money to fully implement the plans in the coming years.

Provide state incentives to establish dedicated drainage funding:

State law provides municipalities with the authority to establish local drainage utilities. Those that don’t use that authority generally rely on federal partners to fund floodplain management and regulatory programs. Or else they use some combination of general tax revenues and municipal bonds. The state should incentivize local communities to fund drainage projects rather than rely solely on federal funding.

Provide counties with legislative authority to establish drainage utilities/fees:

Municipalities have that power. But the unincorporated areas of counties do not. Give counties a reliable source of revenue to implement, maintain and repair drainage projects. Let them establish drainage utilities and drainage fees in unincorporated areas.

Update the state building code on a regular basis:

Texas is missing out on a billion dollars in FEMA’s Building Resilient Infrastructure and Communities (BRIC) Grants because of antiquated building costs. To take advantage of those grants, we need to update building codes. Adopt recent versions of the International Building Code (IBC) and the International Residential Code (IRC) at a minimum. Also we should adopt updated codes regularly in future legislative sessions.

Regulatory and Administrative Recommendations

The plan also made the following recommendations for regulatory and administrative changes.

Upgrade TxDOT design criteria:

Require all new and reconstructed state roadways to be elevated at or above the Atlas-14 1.0% annual chance flood level. Use the 0.2% level if Atlas 14 has not yet been adopted. TxDOT should also consider future conditions, such as urbanization and climate variability, in its roadway design criteria. TxDOT does not in all cases design roadways consistent with minimum NFIP requirements. TxDOT should strive to meet NFIP standards, especially for critical infrastructure such as evacuation and emergency routes.

Recommend Minimum Statewide Building Elevation Standards:

Recommend statewide minimum finished floor elevations at (or waterproofed to) the FEMA effective 2% annual chance flood except in areas designated as coastal flood zones. Use the 1.0% annual chance flood elevation where Atlas 14 has been adopted. Incentivize higher building standards. Recent historic floods and NOAA’s updated Atlas-14 rainfall probabilities reveal how much base flood elevations (BFE) can change over time. Jurisdictions that have required a freeboard over the current BFE have mitigated the risk of these increasing BFEs.

Clarify the process and cost to turn Base Level Engineering (BLE) data into Flood Insurance Rate Map (FIRM) panels:

BLE efficiently models and maps flood hazard data at community, county, watershed, and/or state levels. Currently, the state and FEMA are heavily investing in BLE. Clearly communicate to local jurisdictions how to implement this data in regulations and flood insurance rate maps. The steps remain unclear to many local jurisdictions.

Establish and fund a levee safety program similar to the TCEQ dam-safety program:

The TCEQ has a program to inspect dams that fall under its jurisdiction. Levees, on the other hand, are not subject to a similar safety program despite posing similar risks during flooding events.

Promote flood awareness, education, safety and outreach:

Partner with the Texas Floodplain Managers Association (TFMA) to promote public flood awareness, education, and safety in communities. Also, partner with Texas Association of Counties to do the same for Floodplain Administrators lacking technical flooding background (e.g., some County Judges). A well-informed public can make better informed personal choices regarding issues that involve flood risk and also will be more likely to support public policies and mitigation measures to reduce that risk.

Support ongoing education/training for floodplain management:

Provide no- or low-cost online resources including training modules, webinars, and print. Target training for non-technical Floodplain Administrators (e.g., County Judges who may serve as Floodplain Administrators but not have the necessary technical background). This would help to make effective floodplain management more prevalent across the state, especially in smaller counties.

Develop state incentives to participate in the National Flood Insurance Program (NFIP) and Community Rating System (CRS) program:

NFIP works with communities to adopt and enforce floodplain management regulations that help mitigate flooding. CRS encourages practices that exceed minimum requirements of the NFIP. Both programs are essential to achieving State Flood-Plan goals.  Implement State-led incentives to encourage communities to participate.

Develop a public database that tracks flood fatalities:

Fatalities have occurred during extreme flood events throughout the state’s history. A statewide database and tracking system with appropriate privacy restrictions could aid in future project planning and regulatory decision making. It could also help with future education efforts regarding actions that frequently lead to fatalities. An example is the importance of not attempting to drive through flood waters. 

Help smaller jurisdictions prepare grant and loan applications or make the process easier:

Provide training for Councils of Governments (COGs) to assist with the funding process. Developing applications for project funding can be difficult, especially for smaller jurisdictions with limited experience and access to funding to obtain expert assistance. Simplifying applications and making funding available specifically for application development would serve to make the process more accessible across the state and help close knowledge gaps.

Develop interactive models that use Base Level Engineering (BLE) data: 

Provide them to Regional Flood Planning Groups and their technical consulting teams. Standardize future conditions and land use data. The State’s and FEMA’s BLE data should be available in most parts of the state.

Allow partnerships to provide regional flood-mitigation solutions:

Flood risk does not recognize jurisdictional boundaries, yet many flood-mitigation programs prevent multiple jurisdictions from working together if they want to remain eligible state funding. Flood-mitigation studies and solutions require inter-jurisdictional collaboration. Update policies to encourage and permit it.

Next Step on Final Recommendations

These final recommendations sound like good ideas to me. Please communicate your feelings to your state senator and representative.

I have summarized the final recommendations above. To see their exact text, review chapter 8. Or see the entire report to put them all in context.

Posted by Bob Rehak on 1/22/2023

1972 Days After Hurricane Harvey

Final San Jacinto River Basin Master Drainage Study Released Today, Recommendations Revealed

This afternoon, Harris County Flood Control District (HCFCD), San Jacinto River Authority (SJRA), Montgomery County, and City of Houston released final results of the massive San Jacinto River Master Drainage Plan (SJMDP) study which began in April 2019.

It will take weeks to digest all this information. It consists of:

That’s more than 3,600 pages, EXCLUDING the zipped materials.

Executive Summary Summarized

The executive summary includes a heat map of historically flooded areas, estimated structural damage costs in the next 50 years, and projected population growth during the same period. Not surprisingly, the three fasted growing areas (West Fork, Spring Creek and Cypress Creek) also show the most projected damage.

The summary then proceeds to flood-damage-reduction strategies. They include:

  • Detention Basins
  • Channel Improvements
  • Floodplain Preservation
  • Buyouts
  • Flood Warning Improvements
  • Floodplain Re-mapping
  • Policy updates
  • Formation of a vision group
  • Flood Response Improvements (Evacuation planning, protection of critical facilities such as hospitals, etc.)

The exec summary also lists the top sixteen project priorities, estimates their costs, outlines possible sources of funding, and lays out next steps.

Project Location Map
Project rankings. Note: Rankings do not necessarily coincide with numbers on map above.

“Benching” in reference to the Kingwood Area involves lowering the floodplain near the West Fork to increase flood capacity. This link shows how a similar project in California worked.

The proposed projects will provide tangible benefits, including reduction in the number of at-risk structures for a range of storms as shown in Figure 1.10 below.

With these projects in place, the level of a 100-year flood at I-69 and the West Fork could be reduced by 5.94 feet, Likewise, where Caney Creek meets the East Fork, the 100-year flood would be reduced by 2.82 feet.

Next Steps

That’s good news indeed for everyone who lives in the San Jacinto Watershed. With this information now in hand, we now can quantify the benefits of projects, priorities them, and get on with the hard work of actual mitigation.

More news to follow.

Posted by Bob Rehak on 12/30/2020

1219 Days since Hurricane Harvey

Final HCFCD Report on Tropical Storm Beta Finds Only 25-30 Homes Flooded

The Harris County Flood Control District (HCFCD) issued its first and final report on Tropical Storm Beta today. The 24-page report found that only 25-30 homes in Harris County flooded from the storm, none in the Lake Houston Area. In most places, streams and bayous remained well within their banks. The report also says that HCFCD flood-reduction projects along Braes and Sims Bayous prevented the flooding of 930 structures. The combination of low rainfall intensities, frequent breaks in heavy rainfall, and dry grounds going into the event likely helped reduce the number of homes flooded, according to the report.

Understanding the Uniqueness of Storms

As with all such HCFCD reports, this one presents a treasure trove of statistics, graphs, charts and illustrations. Taken together, they help you understand the uniqueness of individual storms and how to compare them to each other.

Frequent Breaks in Storm Prevented More Severe Flooding

Tropical Storm Beta could have been much worse. The report says, “While Beta did produce heavy rainfall over the county, there were frequent breaks in the training rain bands.”

Overall rainfall intensities were generally in the 1.0-2.0 inch per hour range.

HCFCD final report on tropical storm beta

Most storm drains in the City of Houston are designed to handle 2″ per hour. The report continued, “The lower rainfall rates along with breaks in heavy rainfall allowed most creeks and bayous and internal drainage systems to effectively carry storm water capacities with limited flooding.”

2- to 10-Year Rains in Most Harder-Hit Areas

In most of the harder-hit areas, the storm dropped between 2- and 10-year rains. Those included Clear Creek, Brays Bayou, Keegans Bayou, Willow Waterhole, Buffalo Bayou, White Oak Bayou and Cypress Creek. One place along Sims Bayou recorded a 50-year rain. All other Harris County watersheds had generally less than a 50% (2-yr) rainfall exceedance probability, says the report. Those rainfall exceedance probabilities correspond to new Atlas-14 rates adopted after Harvey.

Intense Short-Duration Rains Cause Most Street Flooding

House flooding in Harris County correlates strongly to the intensity of short duration rainfall rates. In Tropical Storm Beta, short duration rainfall rates generally fell below intensities that lead to widespread and significant house flooding from:

  • Overwhelming capacity of primary drainage systems or…
  • Exceeding capacities of bayous and creeks.

The following chart compares the maximum rainfall amounts recorded in Harris County from Tropical Storm Imelda, Hurricane Harvey, Tropical Storm Allison, and Tropical Storm Beta for various time periods.

From page 3 of HCFCD’s Final Report on Tropical Storm Beta.

The chart above compares the maximum rainfall amounts recorded in Harris County from Tropical Storm Imelda, Hurricane Harvey, Tropical Storm Allison, and Tropical Storm Beta for various time periods.

For the 1-hr rainfall rate, Beta was nearly 50% lower than Imelda, Allison, and Harvey and nearly 8-10 inches lower for the 3-hr rainfall rates.

HCFCD Final Report on Beta

Beta Rates Lower than Other Recent Major Storms

As the chart above shows, rainfall rates associated with Tropical Storm Beta fell significantly below other recent tropical storms that impacted Harris County. The lower rainfall rates were likely a function of a dry air mass wrapping into the circulation, and a general lack of organized and persistent thunderstorm activity.

Beta’s short duration rainfall rates remained slow enough that drainage systems could remain effective. Additionally, dry grounds leading into the event allowed the first few inches of rainfall to be absorbed, helping to reduce run-off.

Jeff Lindner, Harris County Meteorologist

Dramatic NW to SE Rainfall Gradient

The maximum rainfall over 48 hours shows a dramatic gradient aligning from northwest to southeast. As you can see from the iso-map below, people in the Lake Houston Area received less than a third of the rainfall that people received on the southwest side of Houston.

To see the entire 24-page report, click here. For easy future reference, this report can also be found under the Major Storms Tab on the Reports page.

Posted by Bob Rehak on 10/5/2020 based on information from Harris County Flood Control

1133 Days after Hurricane Harvey and 382 after Imelda