At Mayor Pro Tem Dave Martin’s final town hall meeting last night, he and Chief Recovery Officer Stephen Costello gave an update on the status of new, higher capacity floodgates for the Lake Houston Dam. Their talks also addressed dredging and sand traps.
City of Houston Chief Recovery Office Stephen Costello (l) and Mayor Pro Tem Dave Martin at Martin’s final town hall meeting on 10/17/2023. Term limits bar Martin from running again for Council, though he is running for City Controller.
According to the latest estimate, construction of the gates now looks like it could begin in mid-2026, barring unforeseen setbacks.
The City has scheduled more dredging for the San Jacinto West Fork south of where the mouth bar used to be. Also, Costello says the City has completed opening up ditches and tributaries north of the railroad bridge and is now starting on those south of it.
Finally, Costello revealed that Lake Houston has lost almost 20% of its capacity due to sedimentation. To receive future dredging grants, the City must take steps to reduce the rate of sediment inflow. Costello revealed plans for a pilot sand-trap project in a point bar outside the Hallett mine far upstream. He said that the mine had agreed to remove trapped sediment there for free. Otherwise, he did not explain why a possibly more effective location closer to the problem area was not chosen for the pilot project.
For more details on each, see below.
Gates Details/Timeline
The purpose of adding more floodgates to the Lake Houston Dam: to lower the lake faster in advance of a flood.
The City must now start to lower the lake so far in advance of a storm that storms can veer away before they arrive. This wastes water.
The existing gates have 1/15th of the release capacity of the gates on Lake Conroe. This makes a joint pre-release strategy virtually impossible in extreme storms.
After examining and discarding the notion of adding crest gates to the spillway portion of the dam, the City is now focusing on adding 11 tainter gates to the earthen portion of the dam (east of the existing gates).
Proposed location for 11 new tainter gates.
With Mayor Sylvester Turner’s help, the City secured enough funding for construction during the regular session of this year’s legislature.
Next steps include:
3/24 – New environmental and historic preservation assessments, Army Corps permitting
12/24 – Construction plans completed
1/25 – Bidding
6/25 – Award Contract
5/26 – Begin Construction
The success of this plan will require the election of a new Mayor and City Council Representative who are committed to the project. Early voting begins next week.
Dredging Volumes, Costs
Dredging at various locations around Lake Houston will likely be a continuous effort for years to come. Sedimentation has already reduced the capacity of Lake Houston an estimated 18%. The City estimates future yearly losses in the range of 360-460 acre feet per year.
Historic and projected capacity loss in Lake Houston due to sedimentation.
One acre roughly equals the size of a football field. So imagine 400 football fields covered with sludge a foot deep. Each year!
To keep this problem in check, the City is already looking at doing additional dredging on the East and West Forks. It and the Army Corps finished major projects in both areas less than four years ago.
East of Atascocita and south of the convergence of the East and West Forks, the City plans to spend another $34 million to remove almost 900,000 cubic yards of sediment.
To date, Costello estimates that dredging nearly 4 million cubic yards of material has cost $186 million.
Summary of dredging costs and volumes in Lake Houston since Harvey
The City hopes to recoup some of these costs by reselling sand that it recovers from “hilltops” in the lake. Costello showed the heat map below. Notice the heavy sediment concentrations in the lake’s headwaters. This is because sediment drops out of suspension where rivers slow down as they meet standing bodies of water.
In addition to reducing the volume of Lake Houston, the sediment also poses a flood threat. It reduces conveyance of the rivers and lake forcing water up and out. Sediment blockages, such as the mouth bar, can also form dams that back water up.
Costello also addressed the ongoing dredging of 17 canals around Lake Houston. He said the focus is now shifting to the southern part of the lake.
Sand Traps to Reduce Inflow
In addition to dredging sediment from the lake, Costello also emphasized the need to reduce sediment coming downstream via sand traps. This last effort may be a condition of future grants for dredging.
Costello described two pilot types of pilot projects that the City is working on with the SJRA and sand-mining industry. The first is “sand traps” dug in point bars outside sand mines. The second: in-channel traps.
The idea behind the traps: dig holes in the river or its sand bars where migrating sand can settle out of the flow before it reaches the lake.
The first project may be near the Hallett Mine on the West Fork. According to Costello, the mine has agreed to remove the sand for free, thus reducing long term maintenance costs.
During Q&A after Costello’s presentation, however, he admitted that the City has no plans to try to get sand mines to reduce illegal emissions. In one notable instance, the TCEQ documented 56 million gallons of sludge discharged into the West Fork by the LMI mine.
Controlling sediment is crucial in reducing flooding. Accumulated sediment reduces storage capacity and conveyance for stormwater. The smaller capacity means lakes and rivers will flood faster and higher.
For high res versions of all the slides shown in the Town Hall, see this PDF.
Posted by Bob Rehak on 10/17/23
2241 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/10/20230812-RJR_2234-copy.jpg?fit=1100%2C733&ssl=17331100adminadmin2023-10-18 06:47:582023-10-18 15:28:45Update on Floodgates, Dredging, Sand Traps from Martin, Costello
Below I’m reprinting verbatim a press release from FEMA dated 98/6/23. It’s about a new formula for disaster funding. And it creates “Disaster Resilience Zones” that will receive increased federal support. Caution: government euphemisms ahead, including:
“Underserved communities most at risk”
“Socioeconomic status”
“Social vulnerability”
“Social justice”
“Economic justice”
“Disadvantaged communities”
The press release does not mention “damage” or “threats to life” at all. See my editorial comment at the end of this post.
FEMA Press Release
WASHINGTON – Today, FEMA is announcing the initial designation of 483 census tracts that will be eligible for increased federal support to become more resilient to natural hazards and extreme weather worsened by the climate crisis. Congress directed FEMA to make these designations in the Community Disaster Resilience Zones Act of 2022 and implement this bipartisan legislation to help build resilience to natural hazards in communities most at-risk due to climate change.
Designated Disaster Resilience Zones in Houston Area
FEMA will use Community Disaster Resilience Zones designations to direct and manage financial and technical assistance for resilience projects. For example, for federal agencies, the legislation provides additional federal cost-share for projects in designated zones. The zone designations can also help the private sector, nonprofits, philanthropies, and other non-federal partners target investments in community resilience.
The act aims to increase resilience efforts and preventative measures designed to address underserved communities most at risk to natural hazards. Consistent with legislative direction, FEMA considered natural hazard risk from a national and state level while accounting for factors that reflect disaster impacts felt by coastal, inland, urban, suburban and rural communities. FEMA also ensured that each state has at least one Community Disaster Resilience Zone in these initial designations.
“These designations will help ensure that the most at-risk communities are able to build resilience against natural hazards and extreme weather events, which are becoming increasingly intense and frequent due to climate change,” said FEMA Administrator Deanne Criswell. “This aligns with Congress’ direction and other FEMA initiatives to get federal support and resources to the communities that need them most.”
This initial set of designations covers all 50 states and the District of Columbia. These designations can be explored on an interactive map on FEMA’s website. Additional information on the designation methodology and criteria is available. More Community Disaster Resilience Zone designations, including tribal lands and territories, are expected to be announced in the fall of 2023.
An additional designation of zones will occur in 12-18 months based on updates to the National Risk Index, lessons learned from these initial designations, and stakeholder input. Examples of planned updates to the National Risk Index include additional data on tsunami and riverine flood risk.
Designated zones will have prioritized access to federal funding for resilience and mitigation projects. For example, this fall, the National Oceanic and Atmospheric Administration (NOAA) will make awards for the Climate-Smart Communities Initiative program funded by the Inflation Reduction Act to accelerate the pace and reduce the cost of climate resilience-building for communities across the United States. NOAA will work with communities to co-develop equitable climate resilience plans that can be readied for funding and implementation. The priority is to assist communities that are at the highest risk to climate impacts and have the most need for assistance, such as the FEMA-identified Community Disaster Resilience Zones.
The vision for the Community Disaster Resilience Zone Act, passed with bipartisan support in December 2022, is to leverage collaboration and cross-sector coordination across all levels of government, philanthropic foundations, private non-profits, universities, the insurance industry and private businesses.
FEMA will continue to engage the public as it refines the natural hazard risk assessment methodology to designate the zones, consults with local jurisdictions and implements post-designation support from a range of public and private resources.
Editorial Comment
Notice that the press release doesn’t mention damage at all. This appears to be much like Harris County’s Equity Prioritization Framework. We saw last weekend how that distorted the distribution of flood-mitigation funds. Let’s hope that by creating “resilience zones,” we don’t also deprive other areas of the help they desperately need.
At US59, Harvey reached more than 20 feet above flood stage, the deepest in Harris County.Almost a quarter of all the flood fatalities in the county happened near here.
Posted by Bob Rehak on 10/17/23
2240 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/10/Screenshot-2023-10-17-at-10.15.55%E2%80%AFAM-e1697560136356.png?fit=1200%2C639&ssl=16391200adminadmin2023-10-17 12:30:382023-10-17 13:03:05FEMA Adopts New Formula for Disaster Funding
The National Weather Service (NWS) has launched a nationwide rollout of “experimental” flood forecasting maps. The maps show when, where and how much floodwaters will impact specific areas up to five days in advance.
NWS’s new experimental flood inundation maps help communicate the timing and magnitude of high water events by showing modeled inundated areas in blue overlay. Emergency managers may use these services to preposition resources, secure critical infrastructure and recommend evacuations and evacuation routes.
System Already Rolled Out to Houston Area
NWS has already rolled out the system for Houston and East Texas with other parts of the county to follow.
The new system should enable emergency managers to see how predicted rainfall could impact structures, communities and people.
Until now, the best NWS could do was issue a flood watch or warning for communities. But the new maps will show how far floodwaters could spread in a community. That will help people better prepare for floods and evacuate from them. For instance, it will reportedly show when roads will be cut off by rising waters.
However, the new maps can’t yet forecast urban flash flooding related to lack of storm sewer capacity.
Near Real-Time View for Emergency Managers
NWS announced the new experimental flood maps on September 26, 2023. “These new services complement and support the issuance of flood watches and warnings by providing near-real-time, high-resolution, street-level visualizations showing where, when, and how much flood waters are forecast.”
The descriptions conjure up images of floodplain maps. But they show expected flooding from approaching storms – not just the extent of flooding in a hypothetical 100-year event.
David Vallee, director, Service Innovation and Partnership Division, NOAA’s National Water Center said, “These services will dramatically improve our ability to provide impact-based decision support services to our partners so they can preposition people and resources ahead of flood events.”
Three New Tools
Three new near-real-time services will help improve flood impact information. They include:
Hourly Analysis will model flood inundation extent based on streamflow analysis.
Posted by Bob Rehak on 10/16/23 based on information from NWS
2239 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/10/Screenshot-2023-10-16-at-1.34.08%E2%80%AFPM-e1697481825151.png?fit=1100%2C614&ssl=16141100adminadmin2023-10-16 13:46:262023-10-16 17:26:46National Weather Service Rolling Out New Flood Warning Maps
Update on Floodgates, Dredging, Sand Traps from Martin, Costello
At Mayor Pro Tem Dave Martin’s final town hall meeting last night, he and Chief Recovery Officer Stephen Costello gave an update on the status of new, higher capacity floodgates for the Lake Houston Dam. Their talks also addressed dredging and sand traps.
According to the latest estimate, construction of the gates now looks like it could begin in mid-2026, barring unforeseen setbacks.
The City has scheduled more dredging for the San Jacinto West Fork south of where the mouth bar used to be. Also, Costello says the City has completed opening up ditches and tributaries north of the railroad bridge and is now starting on those south of it.
Finally, Costello revealed that Lake Houston has lost almost 20% of its capacity due to sedimentation. To receive future dredging grants, the City must take steps to reduce the rate of sediment inflow. Costello revealed plans for a pilot sand-trap project in a point bar outside the Hallett mine far upstream. He said that the mine had agreed to remove trapped sediment there for free. Otherwise, he did not explain why a possibly more effective location closer to the problem area was not chosen for the pilot project.
For more details on each, see below.
Gates Details/Timeline
The purpose of adding more floodgates to the Lake Houston Dam: to lower the lake faster in advance of a flood.
After examining and discarding the notion of adding crest gates to the spillway portion of the dam, the City is now focusing on adding 11 tainter gates to the earthen portion of the dam (east of the existing gates).
With Mayor Sylvester Turner’s help, the City secured enough funding for construction during the regular session of this year’s legislature.
Next steps include:
The success of this plan will require the election of a new Mayor and City Council Representative who are committed to the project. Early voting begins next week.
Dredging Volumes, Costs
Dredging at various locations around Lake Houston will likely be a continuous effort for years to come. Sedimentation has already reduced the capacity of Lake Houston an estimated 18%. The City estimates future yearly losses in the range of 360-460 acre feet per year.
One acre roughly equals the size of a football field. So imagine 400 football fields covered with sludge a foot deep. Each year!
To keep this problem in check, the City is already looking at doing additional dredging on the East and West Forks. It and the Army Corps finished major projects in both areas less than four years ago.
East of Atascocita and south of the convergence of the East and West Forks, the City plans to spend another $34 million to remove almost 900,000 cubic yards of sediment.
To date, Costello estimates that dredging nearly 4 million cubic yards of material has cost $186 million.
The City hopes to recoup some of these costs by reselling sand that it recovers from “hilltops” in the lake. Costello showed the heat map below. Notice the heavy sediment concentrations in the lake’s headwaters. This is because sediment drops out of suspension where rivers slow down as they meet standing bodies of water.
In addition to reducing the volume of Lake Houston, the sediment also poses a flood threat. It reduces conveyance of the rivers and lake forcing water up and out. Sediment blockages, such as the mouth bar, can also form dams that back water up.
Sand Traps to Reduce Inflow
In addition to dredging sediment from the lake, Costello also emphasized the need to reduce sediment coming downstream via sand traps. This last effort may be a condition of future grants for dredging.
Costello described two pilot types of pilot projects that the City is working on with the SJRA and sand-mining industry. The first is “sand traps” dug in point bars outside sand mines. The second: in-channel traps.
The idea behind the traps: dig holes in the river or its sand bars where migrating sand can settle out of the flow before it reaches the lake.
The first project may be near the Hallett Mine on the West Fork. According to Costello, the mine has agreed to remove the sand for free, thus reducing long term maintenance costs.
During Q&A after Costello’s presentation, however, he admitted that the City has no plans to try to get sand mines to reduce illegal emissions. In one notable instance, the TCEQ documented 56 million gallons of sludge discharged into the West Fork by the LMI mine.
Controlling sediment is crucial in reducing flooding. Accumulated sediment reduces storage capacity and conveyance for stormwater. The smaller capacity means lakes and rivers will flood faster and higher.
For high res versions of all the slides shown in the Town Hall, see this PDF.
Posted by Bob Rehak on 10/17/23
2241 Days since Hurricane Harvey
FEMA Adopts New Formula for Disaster Funding
Below I’m reprinting verbatim a press release from FEMA dated 98/6/23. It’s about a new formula for disaster funding. And it creates “Disaster Resilience Zones” that will receive increased federal support. Caution: government euphemisms ahead, including:
The press release does not mention “damage” or “threats to life” at all. See my editorial comment at the end of this post.
FEMA Press Release
WASHINGTON – Today, FEMA is announcing the initial designation of 483 census tracts that will be eligible for increased federal support to become more resilient to natural hazards and extreme weather worsened by the climate crisis. Congress directed FEMA to make these designations in the Community Disaster Resilience Zones Act of 2022 and implement this bipartisan legislation to help build resilience to natural hazards in communities most at-risk due to climate change.
FEMA will use Community Disaster Resilience Zones designations to direct and manage financial and technical assistance for resilience projects. For example, for federal agencies, the legislation provides additional federal cost-share for projects in designated zones. The zone designations can also help the private sector, nonprofits, philanthropies, and other non-federal partners target investments in community resilience.
The act aims to increase resilience efforts and preventative measures designed to address underserved communities most at risk to natural hazards. Consistent with legislative direction, FEMA considered natural hazard risk from a national and state level while accounting for factors that reflect disaster impacts felt by coastal, inland, urban, suburban and rural communities. FEMA also ensured that each state has at least one Community Disaster Resilience Zone in these initial designations.
“These designations will help ensure that the most at-risk communities are able to build resilience against natural hazards and extreme weather events, which are becoming increasingly intense and frequent due to climate change,” said FEMA Administrator Deanne Criswell. “This aligns with Congress’ direction and other FEMA initiatives to get federal support and resources to the communities that need them most.”
This initial set of designations covers all 50 states and the District of Columbia. These designations can be explored on an interactive map on FEMA’s website. Additional information on the designation methodology and criteria is available. More Community Disaster Resilience Zone designations, including tribal lands and territories, are expected to be announced in the fall of 2023.
An additional designation of zones will occur in 12-18 months based on updates to the National Risk Index, lessons learned from these initial designations, and stakeholder input. Examples of planned updates to the National Risk Index include additional data on tsunami and riverine flood risk.
This new law amends the Robert T. Stafford Disaster Recovery and Emergency Act to direct use of a natural hazard risk assessment index, like FEMA’s National Risk Index, to identify communities which are most at risk of the effects of natural hazards and climate change. For these designations, this methodology uses a tailored version of the National Risk Index that includes socioeconomic status, household characteristics, house type and transportation themes from the Centers for Disease Control and Prevention’s Social Vulnerability Index.
The designation methodology also advances the Biden-Harris Administration’s whole-of-government commitment to environmental justice by incorporating the White House Council on Environmental Quality’s Climate and Economic Justice Screening Tool, which identifies disadvantaged communities that are underserved and overburdened by pollution and climate risk.
Designated zones will have prioritized access to federal funding for resilience and mitigation projects. For example, this fall, the National Oceanic and Atmospheric Administration (NOAA) will make awards for the Climate-Smart Communities Initiative program funded by the Inflation Reduction Act to accelerate the pace and reduce the cost of climate resilience-building for communities across the United States. NOAA will work with communities to co-develop equitable climate resilience plans that can be readied for funding and implementation. The priority is to assist communities that are at the highest risk to climate impacts and have the most need for assistance, such as the FEMA-identified Community Disaster Resilience Zones.
The vision for the Community Disaster Resilience Zone Act, passed with bipartisan support in December 2022, is to leverage collaboration and cross-sector coordination across all levels of government, philanthropic foundations, private non-profits, universities, the insurance industry and private businesses.
FEMA will continue to engage the public as it refines the natural hazard risk assessment methodology to designate the zones, consults with local jurisdictions and implements post-designation support from a range of public and private resources.
Editorial Comment
Notice that the press release doesn’t mention damage at all. This appears to be much like Harris County’s Equity Prioritization Framework. We saw last weekend how that distorted the distribution of flood-mitigation funds. Let’s hope that by creating “resilience zones,” we don’t also deprive other areas of the help they desperately need.
Posted by Bob Rehak on 10/17/23
2240 Days since Hurricane Harvey
National Weather Service Rolling Out New Flood Warning Maps
The National Weather Service (NWS) has launched a nationwide rollout of “experimental” flood forecasting maps. The maps show when, where and how much floodwaters will impact specific areas up to five days in advance.
System Already Rolled Out to Houston Area
NWS has already rolled out the system for Houston and East Texas with other parts of the county to follow.
The new system should enable emergency managers to see how predicted rainfall could impact structures, communities and people.
Until now, the best NWS could do was issue a flood watch or warning for communities. But the new maps will show how far floodwaters could spread in a community. That will help people better prepare for floods and evacuate from them. For instance, it will reportedly show when roads will be cut off by rising waters.
However, the new maps can’t yet forecast urban flash flooding related to lack of storm sewer capacity.
Near Real-Time View for Emergency Managers
NWS announced the new experimental flood maps on September 26, 2023. “These new services complement and support the issuance of flood watches and warnings by providing near-real-time, high-resolution, street-level visualizations showing where, when, and how much flood waters are forecast.”
David Vallee, director, Service Innovation and Partnership Division, NOAA’s National Water Center said, “These services will dramatically improve our ability to provide impact-based decision support services to our partners so they can preposition people and resources ahead of flood events.”
Three New Tools
Three new near-real-time services will help improve flood impact information. They include:
For more on how the system will work, see this story map based on Houston and Hurricane Harvey. Imagine how many lives could have been saved if we had this system then!
Posted by Bob Rehak on 10/16/23 based on information from NWS
2239 Days since Hurricane Harvey