FEMA has agreed to dredge another million cubic yards from the the area near the San Jacinto West Fork Mouth Bar. A report produced for the City of Houston by Tetra Tech helped convince FEMA. The report relied on sonar, LIDAR, and core sample data to estimate the total volume of sand deposited by Hurricane Harvey in that area: approximately 1.4 million cubic yards.
Those close to the project have discussed several strategies to date.
The Corps’ initial strategy: Dredge upstream from the mouth bar. They said 1D modeling showed that would accelerate water flowing into mouth bar and give it the velocity needed to push sand from the mouth bar farther out into the lake.
Another strategy: dredge downstream from the mouth bar and let the river push the mouth bar into the dredged area.
A third strategy: reconnect the river and the lake with a narrow channel that accelerated the flow of water and carried suspended sediment out into the broader lake south of the 1960 bridge.
2019 Tetra Tech Report
Stephen Costello, the City’s flood czar, says that new survey and modeling work has yet to be completed. That will ultimately determine where new dredging happens. However, he also added that consulting Tetra Tech’s exhibits would help provide clues as to where dredging might be most effective, based on knowledge accumulated to date.
The first chart in Appendix A showed the coring locations and transects (survey lines) of the lake’s bottom profile.The second chart shows what they foundin various coring locations.The feet indicate the thickness of the top layer.
Composition of the core samples provides clues as to what was laid down when. Sand (the yellow dots) is generally laid down during floods which have the energy to transport the heavy particles. However, clay and silt (the green and blue dots) are smaller. So they tend to drop out of suspension when water is calmer.
Finding sand above silt in a core sample indicates that a storm like Harvey likely laid down the sand.
The third chart is the most crucial. It’s a difference map that shows areas of deposition and scour pre- and post-Harvey. This shows two things: where most sediment fell out of suspension and where the main flow of the river tried to churn a path through the mounting muck.
From the difference map above, you can see that the river tried to scour its way through the sediment along a path from LH-16 to LH-21 to LH-23. You can see another area of scour to the far right from LH-15 to LH-25 to LH-26.
Where River Flowed Before Lake Was Impounded
Interestingly, the area of scour to the left follows the river’s relic channel.
San Jacinto River map before Lake Houston was impounded
Note how the West Fork hugged what is now Atascocita Point – the thumb of high land that sticks up in the Tetra Tech illustrations.
Harnessing Natural Energy of the River
From the third and fourth illustrations above, one might conclude that excavating a channel near Atascocita Point represents the best way to harness the natural energy of the river. That’s the shortest channel where scour is deepest.
Given the million cubic yard limit, that path also represents a chance to dig the deepest, widest channel possible within the budget. When technicians compiled the difference map above, most of that path was already at or below its 2011 level.
500,000 square-yard path outlined in yellow would let dredgers excavate six feet. Average bottom depth is already 5.5 feet in that area.
Following that path also lets you funnel future sediment through the FM1960 causeway and disperse it out into the wider, deeper lake.
Before the additional dredging can begin, several things must happen.
Completion of a new survey
Model different scenarios
Identify best strategy
Locate suitable placement area
Compile scope of work
Bid job
Mobilize
Based on past experience, that could take months to a year or more. It took 13 months after Harvey for the Corps to put equipment in the water for its Emergency West Fork Dredging Project. However, we don’t have as many unknowns this time.
Posted by Bob Rehak on 9/5/2020
1103 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/09/Tetra-Tech-Study_Page_26.jpg?fit=2550%2C1650&ssl=116502550adminadmin2020-09-05 15:39:592020-09-05 15:53:16Tetra Tech Study Provides Clues To Possible Mouth Bar Dredging Strategies
Earlier this month, the City of Houston announced that FEMA would pay to dredge another million cubic yards of sediment from the West Fork Mouth Bar. What does that mean in practical terms? What are the objectives of the program? How wide and deep will they go? Neither the objectives, nor a dredging plan, have yet been released.
The official plan will hopefully rely on new survey work and hydraulic modeling. A survey boat has been seen on the lake for several weeks now.
Since January of this year, the City of Houston has been trying to reduce the above water portion of the mouth bar with mechanical dredging, a much slower process than hydraulicdredging. Note how shallow the water is in the foreground.
How to Play Armchair Engineer
In the meantime, since fall football is in doubt due to COVID, here’s a simple way to keep your armchair quarterbacking skills finely honed. What would you do if you were the project engineer or manager? Play what if and experiment with different scenarios.
Download and open Google Earth Pro. It’s free.
Zoom in on the West Fork Mouth Bar.
Select the measuring tool.
Click on the polygon tab.
Select square yards for the unit measurement for the areas you will define.
Now start second guessing the project engineers. Play “what if” by defining an area that you would like to see dredged.
Readjust the points that define the area by dragging them in, out, up or down.
Watch the total square yards recalculate as you move the points.
Examples of Different Scenarios
Here are some examples to show you what I’m talking about.
4.3 Million Square Yard Area, Roughly 8 inches Deep
Largest area. This scenario takes in everything between where the Corps stopped dredging in its Emergency West Fork Program and the FM1960 Bridge.
The scenario above takes in the mouth of Ben’s Branch, plus all the other drainage ditches that empty Fosters Mill, Kings Point, and Atascocita north of the FM1960 Bridge.
The scenario above covers 4.3 million square yards. But with a budget to dredge only 1 million cubic yards, you would divide 1/4.3 = 0.23 yards of depth. That’s less than a third of a yard. It works out to about 8 inches.
3 Million Square Yard Area, 1 Foot Deep
In the next scenario, I pulled the boundaries in so that the area equaled 3 million square yards.
This scenario is a little more intuitive. You’re dredging 1 million cubic yards across an area of 3 million square yards. Within this bounding box, you could reduce the level of sediment roughly a foot.
2 Million Square Yard Area, 18 inches Deep
If you reduced the area to be dredged to 2 million square yards, you could reduce the level of sediment by half a yard or 18 inches.
1 Million Square Yards, 3 Feet Deep
Path followed by the relict channel before Lake Houston was built.
If you reduced the area further, to 1 million square yards, you could dredge to 3 feet. With the five feet of depth already there, you could have an eight foot channel connecting the river and the lake. Make it narrower and you could even go deeper. And perhaps, just perhaps, keep sediment from accumulating so rapidly upstream of the FM1960 bridge.
Difficult Choices Ahead
As you can see, engineers have some difficult choices ahead. They must chose between unblocking channels and streams, or dredging a channel roughly the size of the upstream west fork all the way to the 1960 bridge.
Last year, the Corps reduced the 600-acre area between the mouth bar and Atascocita Point to an average depth of 5.5 feet. So we have a good head start. But there are other considerations:
The West Fork was roughly 22 feet deep where the Corps stopped dredging just west of the mouth bar. Because of scouring, it’s at least that deep where the west fork passes under FM1960.
As a result, water coming down the west fork hits an underwater mesa that still blocks off three quarters of the conveyance.
Prominent area geologists, such as Tim Garfield and RD Kissling, theorize that that wall traps sediment and is rapidly diminishing the value of previous dredging programs. They believe that the most important objective for this phase of dredging should be to “reconnect the West Fork with the Lake.”
But Advancing Delta Now Blocks Major Streams, Channels
Meanwhile, consider this, too. In 2014, Bens Branch and the drainage ditch that empties large parts of Fosters Mill and Kings Point had a clear path to the river. Today, both are blocked by the mouth bar and an advancing delta within the lake. Compare the two images below.
Google Earth view from 2014 shows steams could still easily connect with relict channel.
Today, however, an advancing delta within the lake blocks them.
These are some of the real world trade offs that engineers and project managers must deal with every day.
So to return to the football analogy, do you send your receivers wide or deep? Do you have them hug the sidelines or cut for the goal post?
Understand that this isn’t a game, however. It’s a struggle to return a community to prosperity.
What would you do? And why?
Posted by Bob Rehak on 8/31/2020
1098 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/08/20200831-DJI_0613.jpg?fit=1200%2C900&ssl=19001200adminadmin2020-08-31 20:38:392020-08-31 20:52:02How Much Will Dredging Another Million Cubic Yards Reduce the West Fork Mouth Bar Area?
Because of low interest rates, new developments seem to pop up weekly around the Lake Houston Area. The question often arises, “How will the development of new flood maps affect the development of new subdivisions?” Most people by now have heard that City building code revisions now require elevation at least two feet above the .02-percent-annual-chance flood (formerly known as 500-year flood). But does that mean two feet above the old floodplain or the new? Due to a little-known provision in the City’s floodplain regulations, it means the new floodplain even though the new floodplain maps are not official yet.
Here’s what you need to know if you’re concerned that someone may be building future buyouts next to your neighborhood. First the timetable for new flood maps.
Remaining timetable for new Harris County Flood Maps
Even though FEMA won’t release the new flood maps officially for approximately another five years, developers should still be building to the higher standards associated with newly acquired data (in other words, the data on which the new maps are being built). See below.
Floodplain Regs Authorize City Engineer to Use Data Behind New Flood Maps
Section 19-4 of the City’s Floodplain regulations address Use of other flood hazard data to supplement the effective Flood Insurance Rate Map (FIRM). It states, “New elevation and flooding studies are undertaken by or under the auspices of FEMA and local political subdivisions, such as the Harris County Flood Control District. Upon determination that the data generated by such a study appears to be reliable and based upon sound engineering and surveying practices and further that the study’s data indicate that the effective FIRMs are FIRM is materially inaccurate, the city engineer may cause the study data to be administered for purposes of this chapter as though it were a part of the effective FIRM. Any such determination shall be issued in writing and a copy shall be placed on file in the office of the city secretary. The city engineer is authorized to utilize updated information from FIS and floodplain models in administering this chapter.”
Basically, that means even though the new maps have not yet been adopted, the City Engineer can require developers’ plans to reflect the new underlying data as though it were part of the current map. In this case, the new underlying data is already in hand.
MaapNext Website Describes New Data Improvements
Current floodplain maps will change greatly according to Harris County Flood Control. The district has already started releasing information on a new website called MaapNext (Modeling, Assessment and Awareness Project).
Components of the MaapNext program. A $3.5 million FEMA grant made MaapNext possible.
According to the MaapNext site, we now have updated data based on:
County-wide impervious data developed from 2018 aerial imagery
Completed flood risk reduction projects
NOAA’s recently-released Atlas 14
Updated terrain data
We also have new and better ways to model that data since the last survey after TS Allison:
2-Dimensional Hydraulic Modeling
New hydrology method that better accounts for a watershed’s conveyance capacity
Rain-on-Grid analysis that identifies previously unmapped urban flood risk.
And, we are beginning to develop better maps:
Modeling results in GIS (Geographic Information Systems)
New flood-risk data sets describe results in a variety of useful ways
Reportedly, the City is already requiring developers to act on the new “best available data” instead of waiting five years for the next maps.
Chapter 19 of the City Ordinances deals with dozens of other requirements for building in floodplains. But more on those in future posts.
Posted by Bob Rehak on 8/29/2020
1096 Days (Three Years) 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/08/image001-1.png?fit=1182%2C847&ssl=18471182adminadmin2020-08-29 17:17:162020-08-29 17:21:55New Flood-Map Timetable and How It Affects New Development
Houston Mayor Pro Tem Dave Martin announced today that FEMA will fund the dredging of an additional million cubic yards of sediment from the area around the San Jacinto West Fork Mouth Bar. The giant sand bar partially blocked the mouth of the West Fork during Harvey and backed water up. It contributed to the flooding of thousands of homes and businesses in Kingwood, Humble and Atascocita.
Only a skeleton of the above-water portion of the mouth bar remains. But water remains shallow on both sides of it. Note all the trees and little islands poking up between the bar and camera position. Photo taken 8/20/2020.
Ending a Three-Year Debate
The City and FEMA debated for almost three years about how much sediment Harvey deposited in the area between Kings Point and Atascocita Point. The disaster declaration following Harvey only allowed FEMA to fund dredging of sediment deposited by that storm, not to pay for any deposits there previously.
Back before Great Lakes removed its hydraulic dredge, the City commissioned TetraTech to determine the quantity. In April 2019, the City submitted TetraTech’s ninety-four-page report. Based on core sampling, TetraTech estimated that Harvey deposited approximately 1,012,000 cubic yards of sand/sediment.
Subsequently, Martin, Senator Brandon Creighton and Representative Dan Huberty gained support from Governor Greg Abbott to provide a $50 Million grant for additional debris removal. Approximately $7 Million went to dredging the mouth bar land mass, a project which is still underway.
Huberty’s amendment to Senate Bill (SB) 500 set aside another $30 Million for Harris County for dredging at the confluence of the San Jacinto River and Lake Houston. The City is currently a sub-recipient of approximately $10 Million of those funds. Dredging will continue until the City exhausts the funds. According to Martin, the money should cover approximately 242,000 more cubic yards.
Then the FEMA money for the additional million cubic yards will kick in.
Said State Representative Dan Huberty, “After two years of showing FEMA the data, I am thrilled that we are allowed to continue this project due to the hard work of Mayor Pro Tem Martin and Mayor Turner. The funds we secured from the State during the last budget cycle to continue where FEMA left off are nearly depleted. This new funding source will let us complete this necessary and critical project. It is great news for our community. It also recognizes how important the Lake Houston Watershed is to our region.”
Other Lake Houston Dredging Projects
Approximately $10 Million of local funds are earmarked for the dredging activity within Lake Houston south of FM 1960. The City plans to coordinate with Harris County Flood Control District to utilize a portion of the $10 Million to remove the mouth bar obstruction at Roger’s Gully.
Rogers Gully Mouth Bar
However, it won’t happen anytime soon. Based on the bond priorities pushed through Harris County by Precinct One Commissioner Rodney Ellis, County funds will not be available until July 2021 at the earliest. And maybe not until March 2022.
Credits
Mayor Pro Tem Martin, Congressman Dan Crenshaw, State Representative Dan Huberty, State Senator Brandon Creighton, Texas Division Emergency Management Chief Nim Kidd, Mayor Sylvester Turner, and Chief Recovery Officer Stephen Costello have all worked together to make these projects happen.
Another view of the slowly disappearing San Jacinto West Fork mouth bar.
Posted by Bob Rehak on 8/21/2020
1088 Days after Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/08/20200820-DJI_0501.jpg?fit=1200%2C900&ssl=19001200adminadmin2020-08-20 17:31:122020-08-20 17:51:55FEMA to Fund Additional Million Cubic Yards of Dredging from West Fork Mouth Bar Area
FEMA defines base flood elevation as “The elevation of surface water resulting from a flood that has a 1% chance of equaling or exceeding that level in any given year.” In other words, it’s how deep the water would be in a 100-year flood at any given spot.
Let’s take a look at each.
Texas Watershed Viewer
The Texas Watershed Viewer lets users identify local watersheds, sub-watersheds, river basins, and river sub-basins throughout the State of Texas.
To find your watershed and river basin, simply type your address into the search bar and press enter. The map will zoom into the address. From here, click anywhere on the map and the name of the sub watershed will appear. If you click the next arrow on the feature label, the name of the watershed will appear. If you click the next arrow again, the name of the river sub basin will appear followed by the larger river basin.
Clicking on Caney Creek showed the extent of the watershed. Clicking on the arrow within the green bar at the top of the info box changes the outline to match the river sub-basin or basin.
This lets you quickly visualize the extent of a watershed so you can see where water is coming from and going to.
After you click on map to see the feature’s name, you can view the geographic extent of the sub watershed, watershed, river sub basin, and river basin, by clicking the minus sign on the top left corner to zoom out from the address level to the boundaries of the other features. The boundaries of these features will be light blue.
Other Texas Watershed Viewer tools
Zoom: You can zoom in on your neighborhood or zoom out to the entire state of Texas.
Layers: adds the layers window in the top right corner. You can turn the layers on and off by click on the check box.
Basemap gallery: lets you change the basemap of the viewer. The topographic map, for instance, is a useful layer because river, lakes, and streams are labeled.
Measure: lets you measure the distance from your home to a water feature.
Share: lets you show your friends what you see on social media.
Print: lets you print out a copy for your records.
Uses
This site helps viewers understand where water comes from and how it converges. As land is cleared and leveled, it also helps you understand where streams used to flow. (Note: This feature only works until background maps are updated, however.)
One reader used this feature to show how a developer had filled in natural drainage on the developer’s property and blocked off drainage from the reader’s subdivision. With three potential tropical systems moving in our direction at this moment, that information could be very useful if his home floods and he needs to call a lawyer.
Using the topographic base layer, you can also predict where and how runoff will flow during a flood. Many homes near the East Fork flooded during Imelda when Caney Creek captured the Triple PG mine and started flowing south through an area where several other creeks converge. Homeowners report being flooded from overland flow before the creek rose. The topographic feature shows the path that the water likely took.
Those who have a passion for understanding the physical world around them could spend days exploring this website.
Legend shows estimated water depths in image above.
Like most flood maps of this sort, you can turn layers on and off and change base maps.
For instance, by clicking buttons, you can have it show the estimated flood extent and depths for a 1%-chance flood and a .02%-chance flood. You can also view stream center lines, cross sections, and view detailed information on flood insurance rate maps.
You can even activate a split screen mode and compare different features side by side, i.e., ten and hundred year flood extents.
The point of this whole site is to understand not just the extent of floods, but their DEPTH as well.
Uses
FEMA says information from this site helps:
Inform personal risk decisions related to the purchase of flood insurance and coverage levels.
Inform local and individual building and construction approaches.
Prepare local risk assessments, Hazard Mitigation Plans, Land Use Plans, etc.
Prepare information for Letter of Map Amendment (LOMA) submittals.
Helpful Where Flood Maps Not Yet Available
The BLE (Base Level Engineering) Data in this website provides flood hazard information where flood insurance rate maps may not yet be available. We saw this, for instance, in Woodridge Village (north of Elm Grove) where flood maps stopped at the Harris/Montgomery county line. LJA Engineering claimed there were no floodplain issues on the Montgomery County side of the line. In fact, most of the Woodridge Village was in a flood plain as you can clearly see below; it just had not been mapped yet.
Compare that to FEMA’s Flood Hazard Layer Viewer below and you will immediately see the difference.
FEMA’s National Flood Hazard Layer Viewer shows danger stopping abruptly at the county line.
FEMA’s estimated base-flood elevation viewer helps reputable land developers identify flood risk, expected flood elevation, and estimated flood depth where Base Level Engineering has been prepared (i.e., as in the Lake Houston Area).
Reportedly, the information in this tool is not yet Atlas-14 compliant. But it’s still better than nothing.
“Buyer Aware”
The more tools you have to evaluate the purchase of insurance and property, the safer you will be.
No one tool can do everything. But together, the can make you “buyer aware.”
Posted by Bob Rehak on 8/20/2020
1087 Days since Hurricane Harvey and 335 since Imelda
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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/08/Screen-Shot-2020-08-19-at-10.30.14-PM.png?fit=1422%2C1080&ssl=110801422adminadmin2020-08-19 23:17:552020-08-19 23:39:41Two More Websites That Help You Understand Drainage and Flood Risk
On 7/23/2020, consultants for the San Jacinto River Basin Master Drainage Plan gave the SJRA Board and the public a first look at a draft of the plan. The final report is due out at the end of August. The draft shows the broad outline of the team’s efforts.
Draft Shows Broad Outline of Recommendations
It shows the types of recommendations they will make. However, this draft does not yet include specific recommendations as to prioritization of projects. Those will change before the final report. For instance, much of the draft focuses on upstream detention. But specific detention site recommendations have not yet been finalized.
Funding and Partners
Below are the key slides and a brief explanation of the main point behind each. This drainage study is 75% funded by a FEMA Hazard Mitigation Grant and 25% by four local partners: the SJRA, City of Houston, Harris County Flood Control, and Montgomery County.
Scope of Study
The study area covers almost 3,000 square miles and the tributaries listed on the left.The SJRA primarily has responsibility for the portion of the watershed in Montgomery County. However, the scope of the drainage study extends to other counties including Waller, Grimes, Walker, Liberty, and San Jacinto.
Heat Map Shows Where Most Damage Occurs
The team started by looking at where flooding has occurred historically. The tan areas aboveshow where the most damage has occurred.
Goals and Methodology
The partners started by looking at vulnerabilities and identifying mitigation possibilities. Their main goals are in red. The final report will make specific recommendations for detention, buy-outs and improving conveyance. Recommendations will also improve flood warning and communication.The team started by integrating and updating all existing hydraulic and hydrologic models in the watershed as reflected on the latest 2018 lidar terrain data. They now take into account new construction, growth, additions to impervious cover, and Atlas-14 rainfall probabilities (which vary by sub-watershed within the larger watershed).To calibrate and verify its H&H models, the drainage study team examined four historical storms that, together, impacted the entire study area. They then adjusted the models using radar rainfall data, and USGS high water marks and peak flow data. The objective: to make the models reflect “ground truth.”The team is also looking at strategies to reduce sedimentation. However, this is not a major focus of this study. Their purpose is not to evaluate the relationship between sediment and flooding. Other studies will do that.
Three Main Areas of Focus
This slide shows the three major thrusts of drainage study effort over the last 1.5 years. The primary focus has been on: a) identifying the best locations for upstream detention that can reduce the volume of water coming downstream to populated areas during floods, b) where to install additional gages to improve flood predictions and warning times, and c) improving communication during emergencies.This shows the steps the drainage team went through to evaluate and rank-order potential sites for detention.
Areas of Highest Potential for Mitigation
Here’s where they found the highest and lowest potential for mitigation. The box explains the watersheds that see the most effective solutions within the SJMDP study area, as explained in the list to the left of the slide.Some drainage projects recommended in previous plans are no longer possible today because of upstream development. However, areas that once held potential for a single large project still hold potential for several smaller projects that add up to significant flood reduction.
Mitigation Project Funding
The cost all the drainage projects identified adds up to about $3 billion. They only reduce flooding of structures worth about $756 million dollars. Because costs exceed benefits, FEMA will not likely fund all of these.However, many of the projects are in areas with low to moderate income (brown and tan areas). See the large concentration in the eastern watershed. That opens up other sources of funding, such as the Department of Housing and Urban Development where the benefit/cost ratio may not be as important.
Harmonizing Regulations Throughout Region
The team will also make recommendations to harmonize floodplain development regs throughout the region. Continuing to allow unmitigated upstream development in floodplains could destroy any new investment made to protect highly populated downstream areas.
Some Problems May Only Be Solved Through Buyouts
Buyouts usually have a high benefit-to-cost ratio relative to construction projects such as detention ponds. Buyout strategies can target the most vulnerable properties, such as those in the 2- and 5-year floodplains. None of the detention projects recommended by the team will likely remove those from danger.
Steps Still Not Completed
The team has finished the steps in red. They in the process of prioritizing projects and developing a phasing plan. The last bullet point is not part of this study.
More Upstream Gages Needed to Eliminate Blind Spots
The team has also identified locations for additional upstream gages and local partners who can help maintain those gages. Think of these like a “distant early warning” system. They give river forecasters visibility into “blind spots.” Forecasters will be able to add up the rainfall on various tributaries and predict the impact and timing of flooding downstream.That could give people more time to evacuate.
Ways to Improve Communication
The team is also looking at ways to communicate better during flood emergencies. They are looking at inundation mapping, evacuation routes, and improved communication protocols.
Timetable for Remainder of Project
This chart outlines the project workflow. It shows completed steps in red, and incomplete steps in yellow.The final report with specific recommendations should be released at the end of August or in early September.
Every Little Bit Helps
I can’t wait to see this report in its final form. During the presentation, the presenter talked about reducing flooding downstream at the West Fork and I-45 by up to six feet if all upstream projects are implemented.
One thing to keep in mind: there is no single silver bullet that can solve the regions flood problems. All of these steps are additive. In my personal opinion, a foot here and a foot there can help offset future releases from Lake Conroe. People in the Lake Houston Area benefit from any and all upstream improvements.
Posted by Bob Rehak with thanks to SJRA and HCFCD
1064 Days since Hurricane Harvey and 313 since Imelda
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/07/Screen-Shot-2020-07-23-at-10.27.52-AM.jpg?fit=1500%2C1141&ssl=111411500adminadmin2020-07-28 16:33:252020-08-03 15:02:43San Jacinto River Master Drainage Plan Draft Provides First Look at Final Report Due Out in August
Imagine you pull up to a stoplight and two needy people approach you for a handout. You want to help, but have only $1 in your pocket.
Do you give the dollar to the person who has not eaten for the longest time? Or to the person from the zip code with the highest percentage of minorities and lowest average household income?
As you may have guessed, the people at the stoplight are a metaphor for flood victims.
More Needs than Dollars
Harris County doesn’t have enough dollars to build every flood mitigation project that everyone needs. Flood mitigation requires tough choices.
So the County is setting up a supposedly unbiased task force to decide whom to help. But its composition will be biased toward people who believe flood bond money should favor low income, minority neighborhoods, i.e., the constituents of the three politicians pushing the task force (Judge Lina Hidalgo, Precinct 1 Commissioner Rodney Ellis, and Precinct 2 Commissioner Adrian Garcia).
Stacking the Jury
Look at the proposed overview and bylaws for the Community Resilience Task Force. You will see that they embed the concepts of equity, social justice, and social vulnerability into every recommendation the task force will make. For flood mitigation. Housing. Health. Construction. Urban planning. And more. For the next 30 years!
Proposed bylaws for the task force explicitly state that the members MUST demonstrate:
An interest in “equitable” flood mitigation.
Interest in socioeconomic and demographic factors that affect resilience.
So they are baking “equitable” into the job descriptions.
Difference Between Equitable and Equal
“Equitable” treatment sounds like “equal” treatment. But it’s not.
Treating people equally means treating them identically. Treating people equitably means treating them differently, but fairly.
For instance, handicapped people get to park closer to the door. That’s fair…based on need.
But what happens when you start making flood mitigation decisions on the basis of race, income, and social vulnerability? Is that fair to more affluent communities destroyed by flooding?
Because poor people have a harder time recovering from floods, they should get more protection from flooding. They can’t afford to flood (…as if anyone can).
Hidalgo, Ellis and Garcia all advocate the use of a CDC social-vulnerability index and LMI (low-to-moderate-income) data to prioritize flood projects.
They argue in meeting after meeting that FEMA bases grant decisions on a benefit/cost ratio (BCR) that favors neighborhoods with more expensive homes. That’s true, but…
They never mention that Department of Housing and Urban Development (HUD) Community Development Block Grants for mitigation (CDBG-MIT) and disaster recovery (CDBG-DR) already favor poorer (LMI) neighborhoods.
Nor do they mention that the County has already received a BILLION dollars in CDBG-DR funds. Or that the Texas General Land Office is sitting on top of approximately $4.2 billion in CDBG-MIT funds that it’s trying to distribute. The vast majority of those funds must go toward LMI/socially vulnerable neighborhoods. (The exact percentages vary by storm and type of grant. But they often range up to 70%.)
Problems With Basing Flood-Mitigation Decisions on LMI Data
There are two more problems with basing flood-mitigation decisions on racial and LMI data.
First, it ignores need. Shouldn’t projects that help the largest numbers of people or the worst flooding be mitigated first?
Second, LMI data only comes by zip code. Zip codes can mask huge disparities in wealth. So even if you feel poor people deserve more flood protection than the middle class, it’s hard to ensure that result with zip code data. Elm Grove, for instance, is an LMI neighborhood embedded within an affluent zip code.
He did not mention Army Corps of Engineers grants to HCFCD for work on four bayous in his precinct. Nor did he mention that in the entire history of Harris County Flood Control (which dates back to 1937), not one federal dollar has ever been funneled through HCFCD by the Corps for work in the Lake Houston Area.
4 Out of 5 Flood Bond Projects in SVI Neighborhoods
How much have Ellis, Hidalgo and Garcia skewed flood bond spending to date?
During the Commissioners Court meeting on June 30, 2020, Harris County Flood Control was asked to prepare a report to document the status of flood bond risk reduction projects in socially vulnerable neighborhoods. See Item 2E on Tuesday’s Commissioners Court Agenda. It shows a startling fact.
Out of the 145 active bond projects, 79% are located in high or moderately high SVI areas.
Letter from HCFCD to Commissioners Court
The distribution looks like this.
79% of Flood Bond Projects are located in the most socially vulnerable neighborhoods; only 21% in the least socially vulnerable neighborhoods. Source: Memo to Commissioners Court from HCFCD.
If you live in a “socially vulnerable” neighborhood, you’re 4X more likely to have a flood bond project near you.
And those are just the projects based on Flood Bond money. The Flood Control District is also pursuing additional CDBG grants and Army Corps funding to help fund even more projects in socially vulnerable areas. Those projects are not reflected in these percentages.
Rushing Through Public Comment Period
One measure of how much Ellis, Hidalgo and Garcia want to institutionalize their own definitions of equity is that they’re giving only six more days for public comment with little public warning.
You can bet that the commissioners court meeting on the 28th will be packed with surrogate speakers for Ellis, Hidalgo and Garcia who favor the “equity bias.” They’ve shown up in Commissioners Court for months.
Why wouldn’t they? It’s worked. They now have 4 out of every 5 flood bond projects going into their neighborhoods and they could get even more if this task force goes through in its current form.
Meanwhile, the San Jacinto watershed, says the Greater Houston Flood Mitigation Consortium, received 0% of the mitigation budget prior to Harvey, yet had 14% of the region’s damages during Harvey.
How Do We Decide What’s Fair?
So, should projects go to neighborhoods that:
Had the fewest flood mitigation projects?
Flooded the worst?
Help the greatest number of people for the dollars invested?
Are the poorest?
Or should the money be split equally or on some other basis?
Personally, I think decisions like these should be left in the hands of engineers, not partisan politicians.
Register Your Opinion
The County Judge’s office is inviting the public to share their thoughts and ideas on the proposed draft bylaws of the Task Force. You can register your opinion from now until July 30th, 2020, via one of the following methods:
Email CRTF@cjo.hctx.net and submit comments digitally, beginning July 21
Join a virtual focus group via Zoom. After registering, participants will receive a confirmation email containing information about joining the meeting.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/07/Bond-Spending-by-SVI-Index.jpg?fit=1200%2C691&ssl=16911200adminadmin2020-07-24 17:07:032021-07-29 16:06:18Harris County Changing How It Will Choose Which Flood Projects to Support; Welcome to the “Equity Bias”
The once-beautiful townhomes, in the floodway of the West Fork, were designed to have first floors that flooded. But Harvey’s raging floodwaters reached well into the second floors. 240,000 cubic feet per second raging down the West Fork didn’t leave much. After Harvey, structural instability made these townhomes unsafe and uninhabitable.
Townhomes on Aqua Vista in Forest Cove that were demolished by Harvey and then HCFCD.
Almost three years after Harvey, little has changed except for the accumulation of discarded mattresses and couches that grows larger every week.
Buyout of Townhomes Slow and Cumbersome
Today, Harris County Flood Control (HCFCD) has bought out and torn down several of the buildings within this complex. But the process is slow and cumbersome. HCFCD can tear nothing down until all units in a building have been bought.
Without pointing a finger at anyone, the entire process, which stretches from Marina Drive to Pennsylvania Avenue is a logistical nightmare. Such eyesores lower property values and drag down communities.
After viewing the image above, HCFCD said it would accelerate these buyouts. Resolution can’t come too soon for my taste. They serve only one purpose at this point – as a stark reminder not to build near a river.
Posted by Bob Rehak on July 4, 2020
1040 Days after Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/07/20200627-DJI_0035.jpg?fit=1200%2C900&ssl=19001200adminadmin2020-07-04 19:40:212020-07-04 20:03:21One Year Ago Tonight, Flooded Townhomes Burned for Third Time Since Harvey
An article in the New York Times yesterday discussed a new flood-risk website called FloodFactor.com. The article’s headline trumpeted “New Data Reveals Hidden Flood Risk Across America.” The new website was developed by First Street Foundation, which defines itself and its mission as, “a non-profit research and technology group defining America’s Flood Risk.” Past. Present. AND FUTURE. That’s your first clue as to what this new site offers that FEMA doesn’t.
According to the Times, FloodFactor estimates that 14.6 million properties are at risk from what experts call a 100-year flood, far more than the 8.7 million properties shown on federal government flood maps.
FloodFactor takes into account things like sea-level rise, increased rainfall, and flooding along smaller creeks not mapped federally.
New York Times
Purpose of This Post
This article will examine the advantages and limitations of both of the FEMA and FloodFactor sites. Together they can give property owners a fuller understanding of their flood risk. Individually, each can mislead.
That’s both good and bad. Good that information is debated. Bad that sometimes pushback from landowners and local governments distorts true flood risk. No one wants to be reclassified INTO a flood zone that would require paying more for flood insurance. And no one wants his or her property to become undevelopable or unsaleable after a map revision.
Another flaw in the FEMA system: many areas remain unmapped. That allows developers to say they are not in a flood zone when, in fact, they are. We saw that loophole exploited by LJA Engineering with Perry Home’s Woodridge Village. They showed the Taylor Gully floodplain magically stopping at Harris county line. The area on the other side of that county line had not been mapped, therefore they claimed, it wasn’t in a floodplain. That enabled the developer to follow more lenient development guidelines.
FEMA maps also do not estimate future flood risk due to factors such as climate change.
Sometimes it even feels as though FEMA’s trying to catch up with the past.
FEMA maps in Montgomery County are currently based on flood data developed during the 1980s. However, the county has been one of the fastest growing in the country. New unmapped upstream development has significantly altered downstream flood risk, as we saw in Elm Grove twice last year.
Finally, FEMA maps, at present, don’t define risk for individual properties (although FEMA hopes to introduce that capability next year). “This leaves millions of households and property owners unaware of their true risk. There has long been an urgent need for accurate, property-level, publicly available flood risk information in the United States,” says FloodFactor.com.
Pros and Cons of FloodFactor.com
FloodFactor.com addresses many of FEMA’s shortcomings. That’s a huge benefit.
During Harvey, HCFCD says that of the 154,170 homes flooded, 70,370 were outside of the 1% (100-yr) and .2% (500-yr) floodplains. 105,340 or 68% were outside the 1% (100-yr) floodplain. 64% of the homes flooded did not have a flood insurance policy in effect.
Perhaps with a better understanding of true flood risk, many more home and business owners would have purchased flood insurance and avoided financial pain.
Claims include insurance and disaster relief claims on National Flood Insurance Program policies
FEMA Individual Assistance flood claims for those who do not have NFIP policies
Disaster assistance provided by the Small Business Administration.
However, during Harvey, of the 154,170 homes across Harris County that flooded, 68% did not have flood insurance. Many of those sought government assistance. But many also did not. Most government assistance is biased against upper income households.
Regardless, FloodFactor.com claims that it:
Shows flood risk to individual properties
Calculates street flooding risk due to heavy rainfall
Incorporates areas unmapped by FEMA
Compensates for adaptations such as levees and berms that protect people from flooding
Projects future changes such as precipitation increases, stronger storms, and sea level rise
Predicts risk 30 years into the future, theoretically at least, enabling users to gage the probability of flooding during a 30-year mortgage
Intends to update its models annually
Shows risk to individual properties on a sliding scale of 1-10, instead of a yes/no, “I’m in/out of the 100-year floodplain” as FEMA does.
Shows users an estimate of risk in increments (500-year, 100-year, 20-year and 5-year floods or 0.2%, 1%, 5% and 20% annual risk).
Explains what parts of a building are affected by floods of varying depths
Presents flood mitigation solutions individuals can implement
Provides area-wide “risk overviews” and predicts how they will change in the future
FloodFactor.com Looks at Texas and Houston
FloodFactor posted a national outlook with state-by-state discussions. The discussion on Texas says, “The First Street Foundation Flood Model calculates the number of properties facing any risk of flooding in Texas as 2,116,800 over the next 30 years. Of these properties, 218,700 were categorized as facing almost certain risk, with a 99% chance of flooding at least once over the next 30 years.”
They continued, “The city of Houston has the greatest number of properties at risk of flooding in the state with 186,500 currently at risk, or 32% of its total number of properties.”
First Street Foundation
Interestingly, when FloodFactor.com modeled Texas flood risk, they used four historical storms that did NOT include Harvey. They did not explain why.
Shortcomings of Both FEMA and FloodFactor
As far as I can tell, neither FEMA, nor FloodFactor, account for upstream development in their flood mapping. However, FloodFactor does allude at one point to factoring in impervious cover. FloodFactor’s annual updates could help address that issue (if everything is really updated annually).
My background does not qualify me to critique FloodFactor’s methodology or documentation. But I have lived in the north Houston area for 35 years. So I do feel qualified to talk about their predictions for the Lake Houston area.
“Ground-Truthing” Accuracy Claims
I evaluated some areas that I know flooded during recent large storms to get a feeling for how well FloodFactor performed.
After all, if FloodFactor can’t predict the past, why should I believe it can predict the future any better?
I looked at four areas in Kingwood and SE Montgomery County. I was extremely familiar with homes and businesses that flooded or didn’t flood in each during major storms.
Elm Grove:
FloodFactor seemed to nail it. FEMA did not. FEMA shows no flooding north of the county line. FloodFactor even showed areas flooding on Perry Homes’ undeveloped property, plus around it.
North of the blue/green line, no flood map exists for FEMA to reference.FloodFactor.com more accurately shows flooding potential north of the county line. This helps explain the origin of flooding potential south of the county line.
However, the background map appears to be about 10 years old, judging by the extent of development in Woodridge Forest (lower left). Much of that area has since been built up by developers.
So has Woodridge Village (center forested area). It has been cleared for about two years now. Five large detention ponds have been constructed. And the dirt excavated from those has built up the remainder of the property. So in that sense, FloodFactor is outdated from the git-go.
It’s unclear whether Floodfactor’s predictions, say for the Taylor Gully area through Elm Grove (bottom center), take those new upstream detention ponds into account.
River Club/River Ridge:
Between FM 1314 and the West Fork just south of Northpark Drive, lie two small subdivisions called River Club and River Ridge. FEMA nailed it. FloodFactor missed. Badly.
FEMA correctly showed that almost every home in the center flooded during Harvey.
FloodFactor shows most of the homes have no flood risk.
North and South Woodland Hills in Kingwood:
Mixed results. FEMA nailed areas that flooded during Harvey, but missed some street flooding during Imelda. FloodFactor makes me scratch my head. For instance, FloodFactor showed most of North and South Woodland Hills flooding, presumably from street flooding, after climate change will make rainfalls even more intense. However, they don’t specify exactly where most of the risk comes from. These are among the two highest subdivisions in Kingwood.
FloodFactor shows North and South Woodland Hills, plus the Northpark Place Commercial area flooding worse than other areas which have experienced more flooding.
Two Better than One
Given the fact that neither FEMA, nor FloodFactor, is perfect, it’s best to use them in conjunction with each other. With a knowledge of the limitations of each, one can gain a better understanding of flood risk. There’s just no substitute for talking to people in the neighborhood.
One more example in that regard.
Northpark Commercial Area Near Woodland Hills Drive
FEMA correctly shows historical flood risk. Note the location of red dot for reference below.
FEMA flood map showing risk from Ben’s Branch. Red = floodway. Aqua = 1% annual chance. Brown = 0.2% annual chance of flooding.
The red dot above shows the location of a building that was raised 3 feet before construction, but not listed with FEMA because it was far outside the 500-year floodplain.
FloodFactor predicts this whole commercial area will flood due to environmental changes and that the building by the red dot will take on 2.2 to 2.6 feet of flooding. It doesn’t recognize the building had been raised.
One big benefit of the FEMA maps is that property owners who elevate their homes can have them reclassified out of the floodplain. It’s not clear how that might work with FloodFactor.
However, with input from both websites, if I were buying a property, I would know enough to start asking questions:
What’s happening around this area to increase flood risk? (Upstream development in the Ben’s Branch Watershed? Environmental change?)
Should I check the elevation of my property against FloodFactor’s estimate? (Yes!)
Could floodproofing or elevation strategies help my property? (Yes!)
Should I look again at getting flood insurance? (Yes!)
This is like getting a second repair estimate for your car. You are always safer with at least two estimates.
Make Your Own Comparisons
Find a neighborhood or property of interest on FEMA’s National Flood Hazard Layer Viewer.
Since the National Flood Insurance Plan’s (NFIP) inception in 1968, additional legislation has been enacted to strengthen the program, ensure its fiscal soundness, create better maps, and tie rates closer to risk. Next year, FEMA will transform the NFIP with something called Risk Rating 2.0, a major change.
FEMA says that with Risk Rating 2.0, NFIP is leveraging industry best practices and current technology to deliver rates that are fairer, easier to understand, and better reflect a property’s unique flood risk.
That last part is code for “we lost a lot of money.”
Unsustainable NFIP Losses
NFIP continues to pay claims in excess of revenues, and borrows increasingly from the U.S. Treasury.
Last October, Michael D. Berman wrote an article titled “Flood Risk and Structural Adaptation of markets: An Outline for Action” in the Federal Reserve Board’s Community Development Innovation Review. In it, he says, “On September 22, 2017, after borrowing $5.825 billion to fund claims from Hurricanes Harvey, Irma and Maria, the NFIP had reached its maximum U.S. Treasury borrowing authority of $30.425 billion in program debt. On October 26, 2017, Congress cancelled $16 billion of NFIP debt—the first time in the history of the NFIP that has occurred. Then on November 9, 2017, the NFIP borrowed another $6.1 billion to fund additional 2017 losses, including additional losses from Hurricanes Harvey, Irma and Maria.”
Rating Flood Risk at Property Level
Berman claims, “The NFIP is clearly not properly pricing flood risk, nor is it adequately influencing prudent behavior by property owners and municipalities to sufficiently reduce or otherwise mitigate this risk…This new rating system, known as Risk Rating 2.0, is expected to include repricing of premiums based on flood risk at the property level.”
What Risk Rating 2.0 Involves
FEMA says its current risk-rating methodology has not fundamentally changed since the 1970s. It is now heavily dependent on the 1-percent-annual-chance-event (100-year floodplain).
Risk Rating 2.0 will incorporate a broader range of flood frequencies, new mapping data, and new technologies, more individual rating characteristics, such as:
• Distance to the coast or another flooding source; • Different types of flood risk; and • The cost to rebuild a home.
By reflecting the cost to rebuild, the new rating plan will also aim to deliver fairer rates for owners of lower-value homes.
Rates that Promote Mitigation Efforts
FEMA also plans to offer mitigation credits to help incentivize risk-reduction efforts and reduce the cost of future flood events. Risk Rating 2.0 will initially provide credits for three mitigation actions:
Installing flood openings;
Elevating onto posts, piles, and piers; and
Elevating machinery and equipment above the lowest floor.
FEMA is not yet saying how many premiums will increase or decrease, or by how much. Two things ARE clear though.
6:1 Payback on Flood Mitigation Investments
First, the old system is broken and unsustainable. Flood maps were outdated and based on data decades old in many cases. They contained many unmapped areas and the mapped areas were strongly influenced by local politicians and developers. Maps also did not reflect the effects of upstream development or more intense, frequent storms.
Second, the new system has a chance to incentivize risk-reduction. The old system encouraged people and communities to rebuild things the way they were after a disaster. We need a new system that encourages more prudent behavior.
FEMA cites a recent study by the National Institute of Building Sciences. Looking back over 23 years of data, the study found that for every dollar that the federal government invests in flood hazard mitigation, taxpayers save an average of six dollars of future disaster recovery spending.
Rebuild to Fail or Rebuild to Adapt?
The current federal flood insurance program promotes rebuilding in flood prone areas. Hopefully, the new system will promote adaptation to help mitigate increased risk.
Flood insurance rates that better reflect risk may promote more prudent behavior by developers, lending institutions, property owners, buyers, and real estate agents who will all “follow the money.”
