According to Harris County Flood Control District’s (HCFCD) latest flood-bond update, 19 of 19 active capital improvement construction projects are now in Democratic precincts (1, 2 and 4). None is in the County’s lone Republican-led Precinct 3, the county’s largest.
Moreover, the update also shows that the San Jacinto watershed now has NO active maintenance OR construction projects.
Latest Update Restates Numbers for 12 Months Ending 11/22
Every month, Harris County Flood Control District issues an update on 2018 Flood-Bond projects. The updates typically cover:
Newsworthy items from the previous month
Performance metrics
A master schedule of all projects
Funding and spending to date by watershed
Active Maintenance Projects
Active Construction Projects.
This month, the update also includes restated figures for 2022 reports. The last page corrects several figures in previous monthly reports. Some of the reports contained incorrect figures related to confusing labels.
The corrected figures show that from December 2021 through November 2022 (the last month covered in this report), HCFCD:
Awarded 7 constructsruction contracts valued at a total of $60 million.
Awarded 91 other agreements for things, such as engineering studies and design, valued at a total of $140 million
Spent a total of $1.151 billion on all bond projects since 2018. That includes:
$602 million of bond funds
$392 million in grants
$157 million of other local funds
Completed 24.1% of the bond projects in 44% of the time allotted.
Gives itself a schedule performance index of .95
Completed 913 buyouts for $174 million total (Average = $190,000 each)
No Active Construction Projects Shown in P3
Under Active Capital Improvement Construction Projects, HCFCD shows none (zero, nada, zilch, bupkis, diddly-squat, zip, i.e., nothing at all) in Precinct 3, the county’s largest precinct and one of the most heavily flood damaged.
Note absence of active construction projects in Precinct 3 (pink), the county’s largest. All active construction projects are now in the three Democratic precincts.
However, elsewhere on the Commissioner’s Court agenda for Tuesday, Rodney Ellis is asking for $2.66 million for hike-and-bike trails around Willow Water Hole on South Post Oak in his Precinct 2. See Item 303. Precinct 2 Commissioner Ellis is reportedly an avid bicyclist. He lives near there.
No Active Construction OR Maintenance Projects in San Jacinto Watershed
Also, the update shows NO active construction or maintenance projects anywhere in the San Jacinto Watershed, the county’s largest and one of the most heavily flood damaged.
Updated Spending Totals by Watershed
Here are the latest spending totals by watershed per the update.
Spending by watershed through November 22
In tabular format, they stack up like this:
Totals by watershed from inception of bond through end of November, 2022.
Posted by Bob Rehak on 1/27/23 based on the November 2022 HCFCD Bond Update
1978 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/Screenshot-2023-01-27-at-8.48.56-PM.png?fit=1910%2C1240&ssl=112401910adminadmin2023-01-27 21:34:392023-01-28 18:00:15All Active HCFCD Construction Projects Now in Democratic Precincts
The dangers of street flooding can be costly. We’ve all read about people who drown while driving through flooded underpasses. But other dangers exist, too. Costly ones.
On Tuesday 1/24/23, the Lake Houston Area received a 5-year rain. Streets flooded throughout the area because storm sewers are generally designed to carry 1- to 2-year rains.
So, water backed up into streets. When cars and trucks tried to plow through the ponding water, they set up waves that slapped against people’s homes. This video dramatically shows what those waves can do.
And when the ponding water rises over the level of your tailpipe, it will choke your engine and stall your car. It can also flood the interior and ruin your electronics.
It’s impossible to tell the depth of water accurately in these situations.
Progressive Insurance lists common problems with flood-damaged cars. Flooded vehicles can easily turn into total losses. “Flooded cars are often declared a total loss because repairing water damage is complicated and costly,” they say. “A total loss means the insurance company has determined that the damage cannot be repaired safely, or the cost to repair the vehicle is more than the value of the car.”
So, your best bet is to stay home and watch Wheel-of-Fortune reruns until the water recedes.
The roads cleared about an hour after the homeowner took these photos. The dangers of street flooding disappeared down the storm drains.
Diagnosing Street Flooding Problems
If your street flooded and the streets around you didn’t, you may want to call authorities and have them see if your storm sewers are blocked.
You might also be interested in seeing if the storm drain inlets are located at the lowest points on your block. Here’s how to check the elevations.
Finally, examine the storm drain inlets and make sure you have sufficient drainage. There are many different sizes and types.
Posted by Bob Rehak on 1/26/23
1976 Days after Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/20230126-Screenshot-2023-01-26-at-7.39.55-AM.jpg?fit=1200%2C614&ssl=16141200adminadmin2023-01-26 08:29:522023-01-27 12:26:43Dangers of Street Flooding
Between 1:00 and 3:00 PM on 1/24/23, approximately 3.6 inches of rain fell over Royal Pines in southeast Montgomery County. According to Atlas-14 rainfall tables, that qualifies as a 5-year rainfall event. But floodwaters from White Oak creek approached the edge of the 100-year floodplain. And missing silt fences let sediment escape into the wetlands that border the property.
5-Year Rain
A friend who lives a mile from Royal Pines recorded about 4″ on his rain gage for the full day. A check of nearby rain gages on the Harris County Flood Warning System, showed that the official gage at FM1485 and the San Jacinto East Fork recorded approximately 3.6 inches between 1 and 3 PM today.
Harris County Flood Warning System hyetograph shows approximately 3.6 inches fell in two hours on 1/24/23.
Cross-referencing that rate with NOAA’s Atlas-14 rainfall probability estimates for this area, we can see that 3.6 inches in 2 hours equals a 5-year rain.
NOAA Atlas 14 rainfall probabilities for Lake Houston Area.
100-Year Flood Line
Now let’s look at how close that 5-year rain came to the 100-year flood line. In the construction diagram below, the developer shows the edge of the 100-year flood plain. It’s the dotted line between Zone AE and Zone X. I’ve circled the relevant portion in red.
If you were to project that line toward the lower right, it would roughly parallel the heavy black line that forms the eastern boundary of Country Colony, which you can see in the middle right of the photo below.
Floodwaters from Creek Overflow Royal Pines
The water comes almost to the edge of the floodplain shown in the construction diagram above.
Looking SE across Royal Pines. County Colony in upper right.
That big area filled with water, is a part of White Oak Creek cutting across Royal Pines. Think it’s just standing water? Think again.
The closer shot below shows water streaming through the soon-to-be subdivision and filling the Country Colony drainage ditch to overflowing.
Notice the water streaming through the cleared area and carrying away sediment downstream.
Notice also how the floodwaters approach what appears to be some sort of water treatment facility in the upper right.
These shots also document the absence of silt fence on the eastern side of Royal Pines.
All that silt will migrate down White Oak Creek and Caney Creek into the East Fork San Jacinto which the City of Houston just dredged at great public expense. The public also must foot the bill for increased water-purification costs.
More Missing Silt Fence in NW Corner of Royal Pines
The SE corner of Royal Pines wasn’t the only part of the development missing silt fence. The developer removed it from the NW corner – where a neighbor has now flooded three times in two months.
Looking N toward White Oak Creek. Contractors removed the silt fence last week. Rain then swept sediment into the woods.
Those woods contain sensitive wetlands.
Notice how water coming from the north (left) is clear. But water coming from Royal Pines (right) is filled with sediment.The muck filled the wetlands for more than a mile downstream.
How Can a 5-Year Rain Reach Almost as Far as a 100-Year Floodplain?
We need an answer to that question before this development starts pouring concrete. There are several possible explanations.
Clearcutting accelerated runoff.
Bulldozers compacted soil, limiting the rate of infiltration.
The developer hasn’t built any stormwater-detention-basin capacity to offset the increased runoff.
Planners used old (lower) Montgomery County rainfall data to determine the extent of the floodplain in their plats and plans.
Engineers didn’t count on the cumulative impact of insufficiently mitigated upstream development, some of which used beat-the-peak, hydrologic-timing surveys to avoid building detention basins.
More rain fell upstream than at the gage shown above.
Some or all of the above.
I took these photos within an hour of the end of the rain. So there wasn’t much time for water to work its way downstream very far.
Two floodplain experts I consulted pointed to the cumulative impact of upstream development as a possible culprit. Engineers are likely working with flood data acquired in the 1980s before Montgomery County became one of the fastest growing counties in the region. The data is simply too complex to adjust after each new development. So, it never gets revised and errors compound over time.
I’m sure the Montgomery County Engineers Office and TCEQ will want to get to the bottom of this before the developer starts building homes. If homebuyers flood on rains that are far less than 100-year rains, tremendous liabilities could result.
If Royal Pines or Montgomery County would like to rebut the issues I’ve raised, I will be happy to publish their point of view. The public deserves to know what’s going on.
Posted by Bob Rehak on 1/25/23
1975 Days since Hurricane Harvey
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/20230124-DJI_0738.jpg?fit=1200%2C799&ssl=17991200adminadmin2023-01-25 11:21:142023-01-25 15:48:255-Year Rain Brings White Oak Creek Close to 100-Year Mark in Royal Pines
The National Weather Service and Harris County warn of a severe weather threat for Tuesday.
Harris County Meteorologist Jeff Lindner warns that severe thunderstorms, some of which could turn into tornados are likely with heavy rainfall, and gusty winds across SE Texas Tuesday.
The National Weather Service Storm Prediction Center also warns of the potential for supercell development and hail.
Up to 3 inches of rain are likely with isolated higher amounts (up to 6″ according to Lindner) where thunderstorm training exists.
Rainfall for Tuesday from the NWS Weather Prediction Center.Posted at 2:38PM Central Time, Monday 1/23/23.Hail probabilities for Tuesday range from 5-15% across region.
Overview
A deepening upper level trough over the SW US will move eastward and into SW/W TX tonight/Tuesday and then exit the state early Wednesday morning to the east. This system will bring dynamic weather to much of Texas starting late Monday tonight.
The dry air now over SE TX will undergo significant changes in the next 24 hours. A low level jet will quickly transport extreme moisture northward from the SW/W Gulf of Mexico. Moisture levels in the atmosphere will quintuple overnight, driven by the 50-60 mph winds just above the surface. NWS indicates strong winds are the primary threat.
A wind advisory will likely be required for much of the area with isolated to scattered power outages possible.
Jeff Lindner, Harris County Meteorologist
Lift should rapidly increase Tuesday morning with scattered to numerous showers and thunderstorms developing from SW to NE across the region.
Look for scattered showers to begin developing around sunrise, then increase in coverage through the day. The highest potential for thunderstorms in the Houston metro area should be mid-afternoon. But they should move out of the state by early evening.
Heavy Rainfall Expected
Models hint at some sort of low-level convergence boundary becoming established along the US 59 corridor around mid-morning Tuesday. That should trigger heavy rainfall well ahead of the approaching front and boost rainfall in the Fort Bend, Harris, and Liberty County areas. Lindner worries that this could lead to a period of training storms and quick rainfall accumulations.
He predicts widespread rainfall of 1-3 inches with isolated totals of 4-6 inches possible.
Street flooding will be a concern in areas that catch heavier rainfall. Hourly rates may approach 1-3 inches.
Given the time of year, wet grounds, and dead vegetation from recent freezes, maximum run-off is likely. Lindner expects rises on area streams, but also says that the current forecasted rainfall amounts should not lead to creek, bayou, or river flooding.
Severe
The National Weather Service Storm Prediction Center suggests that an impressive 80-100kt mid-level jet carving across SE TX Tuesday afternoon could bring enough instability south of I-10 for severe thunderstorms to develop. SPC has upgraded the risk in that area into a (2 out of 5) slight risk.
Wind gusts of 60-70mph will be possible. Near the coast, a tornado or two will be possible. The highest threat of severe weather is currently offshore, but the severe threat could be upgraded south of I-10.
Winds
Starting late tonight, the strong low level jet overhead will bring sustained winds of 25-35mph and gusts of 40-45mph at the surface much of Tuesday. Gusts may be higher near the coast and inland bays. A wind advisory will likely be required for much of the area and these winds may down trees and tree limbs, result in isolated to scattered power outages, and move unsecured outdoor objects.
Marine
Dangerous marine conditions will quickly develop late tonight into Tuesday as southerly winds rapidly increase into the 35-45kt range for all waters.
A gale watch is in effect for all waters and will be upgraded to a warning this afternoon. Seas will quickly build 6-8 ft in bays and 10-12ft offshore on Tuesday.
The strong winds may result in elevated tides in the northern portion of Galveston Bay Tuesday along with wave run-up on the Gulf facing beaches.
The line of strong to severe thunderstorms arriving Tuesday afternoon/evening will bring W/NW winds at 30-40 kts. Wind gusts of 50-55kts will be possible. Small craft should be in port by this evening and remain in port until winds and seas subside on Wednesday.
One Year Anniversary of Kingwood Tornado
Although January tornados are rare, we should not forget what happened last January when several twisters slashed through Kingwood downing trees and power lines. Exercise caution.
Posted by Bob Rehak on 1/23/2023 at 2PM based on information from the NWS and Jeff Lindner
1973 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/d12_fill.gif?fit=800%2C561&ssl=1561800adminadmin2023-01-23 15:08:342023-01-23 15:27:21Severe Weather Threat Tuesday with High Winds, Rain Up to 3″ and Possible Tornados
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.
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
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/20230121-Screenshot-2023-01-21-at-9.54.40-PM.jpg?fit=1200%2C788&ssl=17881200adminadmin2023-01-21 21:57:432023-01-21 23:33:14San Jacinto Regional Flood Planning Group Submits Final Recommendations
On January 10, 2023, McGehee ☆ Chang, Landgraf, Feiler responded to the government’s most recent motion in the Addicks Barker Downstream “Takings” Case on behalf of the plaintiffs. Their response included a counter-motion against the government. Here is a copy of their motion. Each side will have a chance to file one more round of written arguments before trial.
Background: Government Denies Claims
To recap, in November 2022, the government again moved for a summary judgment in the case. The government contended that the Addicks and Barker dams:
Historically prevented far more damage ($16.5 billion through 2016) than the release of water during Harvey caused
Reduced plaintiff’s level of flooding by up to 7-8 feet
Did not “cause” – in a legal sense – the plaintiffs’ flooding
Further, the government contended that plaintiffs’ claims are based on a single, extraordinary, catastrophic event and any action undertaken by the Corps during the event does not constitute a “taking” under the Fifth Amendment.
The government compared peak flows at several points along Buffalo Bayou during Harvey and contended that the plaintiffs properties would have flooded regardless of the release. It claims that the releases constituted less than 10% of total flow. The government also claimed that had it never built the dams, downstream flooding would have been far worse.
Plaintiffs Allege They Were Not Informed of Risk
The plaintiff’s response (which included 3800+ pages of arguments, depositions and appendices) focuses on how the government modified the dams and its procedures over time.
It adjusted discharge rates to maintain a “non-damaging channel capacity over time.” The rates went from the original design concept of 15,700 cubic feet per second down to about 2,000 cubic feet per second in a series of incremental steps over decades. The changes were designed to accommodate residential construction along Buffalo Bayou.
The plaintiffs allege that the Corps publicly reassured property owners that it would not open the dams to a point where it would cause downstream flooding. Plaintiffs further allege that over the years, people grew to rely on these assurances and none of the test properties experienced any flooding.
Nor did any of them know that the Government might deliberately release water from the Reservoirs in sufficient quantities to flood their properties.
One commercial property reported just a few inches of flooding prior to the releases, escalating to six feet afterward. Plaintiffs argue that they would have suffered no or substantially less flooding if the government had not released water, a decision motivated in part to protect upstream properties.
Crux of Plaintiff’s Arguments
Plaintiffs claim the government:
Repeatedly promised downstream property owners that it would keep the floodgates closed
Could have kept the floodgates closed; the Reservoirs were never in danger of failing
Elected to open the floodgates even though it did not have to do so to avoid any imminent failure
Knew that opening the floodgates would flood the downstream property owners
Cannot meet the high bar required to assert releases were necessary.
Could have bought-out the properties it flooded but chose not to because of the expense.
Plaintiffs conclude by saying that:
The Government’s summary judgment motion should be denied
The Court should enter a partial summary judgment for the Plaintiffs on the liability and causation elements of their claims
All other issues, including damages, should be set for a prompt trial.
To review all the appendices submitted by plaintiffs, click here. Size caution: 330 megabytes.
A Shakespearean Tragedy
Although it might be buried somewhere in thousands of pages of filings, neither side in this case appears to directly address which properties would have flooded regardless of the release and which flooded because of the release.
The government seems to contend it is responsible for none of the flooding because it was unavoidable. And the plaintiffs contend the government is responsible for all of it.
This is like watching a Shakespearean tragedy unfold. Not even at issue here are the policies that allowed lucrative development in dangerous places, the lack of risk disclosure, and the erosion of safety margins.
Next up: The government can reply to plaintiff’s motion by February 9, 2023. Plaintiffs will then have a chance to reply to the reply by March 11. Then both sides will gear up for a hearing before the Judge.
Posted by Bob Rehak on 1/19/2023
1969 Days since Hurricane Harvey
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/20230119-Screenshot-2023-01-19-at-12.18.25-PM.jpg?fit=1200%2C625&ssl=16251200adminadmin2023-01-19 12:24:482023-01-19 12:27:59Downstream Addicks Barker Case Moves Another Step Closer to Trial
The sky darkens. Thunder grows louder. Suddenly, the rain comes down so hard you can barely see. Soon, water starts coming over the curb toward your house. Your weather radio crackles with warnings. And when it’s over, the stormwater has stopped just feet from your door. Close call! But then you wonder. How intense was that storm? And does it really matter?
The answers affect disaster planning, flood insurance, mitigation, and more.
Consider the intensity question first.
How Intense Was That Storm?
Was it a 1-, 2-, 5-, 10-, 25-, 50- or 100-year storm?
Determining the intensity requires more than just reading your rain gage. That’s because intensity depends on volume within a certain time period. Five inches of rain in an hour should concern you far more than in a day.
Start by going to the Harris County Flood Warning System. It shows all official gages in the region. Hover over any one. A box with a hyperlink will pop up. For this example, let’s assume you live near the East Fork San Jacinto and FM1485.
Hovering over the gage by New Caney pulled up box with the blue link.
Click on the More Information link. It will lead you to a search screen that lets you specify date(s). You can also specify time ranges from one hour to one year.
In this case, I selected 2 days and adjusted the date until I captured all the significant rainfall.
By experimenting with different time ranges, you can narrow down the start and stop times. This is crucial, because intensity depends on both quantity and duration.
At our sample gage, I learned that rainfall from Tropical Storm Imelda in 2019 happened over a two-day time period.
Now, look up the total (28.68 inches) in the Atlas-14 table below. This table shows the rainfall precipitation frequency estimates for the Lake Houston Area.
So, how intense was that storm? The total rain for two days – 28.68 inches – qualifies Imelda as a 500-year storm at that gage. Look down to the 2-Day line and then across to the 500-year column.
If you captured more or less rain in your rain gage at home, use that total instead. At least now you know that you’re working with a 2-day event. (Note: some rain fell outside this range, but not much.)
Check other Gages to See Geographic Rainfall Distribution
While you’re exploring the Flood Warning System, check several different gages, especially those upstream. Rainfall can vary considerably within short distances.
For instance, during Imelda, a gage at the West Fork and SH242 showed only 13 inches of rain during an identical period – less than half the rain just a few miles west. That ranks as a 25-year storm, not a 500!
When people say that “We got X number of 500-year storms in Y years,” it’s important to remember that the 500-year designation applies only to a particular gage, not an entire region.
Do 500-Year Storms Mean 500-Year Floods?
Also remember this. As the example above shows, having a 500-year storm somewhere near you does not automatically mean you will experience a 500-year flood. It depends on where the rain falls in your watershed. If it falls upstream, it could result in a 500-year flood. But if it falls downstream, it will not.
During Imelda, the gage(s) at:
Greens Bayou and US59 got 15 inches – between a 25- and 50-year rain.
Spring Creek and I-45 got 8 inches – a 5-year rain.
Cypress Creek and US290 got 2.52 inches, not even a 1-year rain.
Lake Creek at Dobbin got 1.52 inches.
Lake Conroe at 1375 got .84 inches.
Use the drop-down list of gages to explore rainfall rates elsewhere.
A few miles in each case separated Armageddon from something far more manageable.
What Can You Do with This Information?
This exercise can help protect you in several ways. For instance:
If you didn’t flood during Imelda and you heard it was a 500-year rain, you might assume you didn’t need flood insurance. That could be a financially devastating miscalculation.
If you get little rain upstream and still flood, you should investigate why.
If you flood frequently on small rains, you need to investigate the causes and mitigation. Engage with HCFCD, your county engineer or floodplain manager. Perhaps the floodplain has been altered by upstream development. Perhaps the stream near you has become clogged. Perhaps you need to elevate your home or seek a buyout.
The more you know, the safer you’ll be.
Posted by Bob Rehak on 1/18/23
1968 Days since Hurricane Harvey
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/CallbackPanelPartial-2.png?fit=820%2C400&ssl=1400820adminadmin2023-01-18 17:14:232023-01-18 17:24:09How Intense Was That Storm? And Why Does It Matter?
One third of Harris County is now impervious cover. According to the Harris County Infrastructure Resilience Team, green roofs are one of several tools that can help mitigate flooding by converting impervious cover back into green space.
Also known as ‘vegetated roofs’ or ‘living roofs,’ they can reduce runoff by soaking up part of the rainfall during a storm and holding it back.
Part of 19,200 square foot green roof installed on EPA headquarters in Denver
Green roofs consist of a waterproofing membrane, growing medium (soil) and vegetation (plants) overlying a traditional roof.
The U.S. General Services Administration (GSA) manages more than 2 million square feet of green roofs. Some date back to the 1930s. So, they have extensive experience.
GSA points out that “Most urban and suburban areas contain large amounts of paved or constructed surfaces which prevent stormwater from being absorbed into the ground. The resulting excess runoff damages water quality by sweeping pollutants into water bodies. Green roofs can reduce the flow of stormwater from a roof by up to 65% and delay the flow rate by up to three hours.
Green roofs mimic natural hydrological processes as part of a watershed management approach to drainage. They are just one of many tools to reduce impervious cover.
Cost/Benefit Analysis Shows Payback
Cost/benefit analysis shows that green roofs can provide payback in 6.2 years. Their longevity has the greatest effect on savings.
They last twice as long as conventional roofs.
U.s. General services administration
Of course, they cost more to install and maintain. But GSA says that the other benefits they provide (stormwater and energy reduction) more than compensate for the premium owners pay.
But any cost/benefit analysis for owners/investors depends on many factors, such as the square footage and height of buildings. Energy and stormwater management benefits increase with size of a roof. Energy savings primarily benefit the higher floors in a multi-story building, i.e., those closest to the roof.
GSA notes that any increased market value of buildings with green roofs was not included in its cost/benefit analysis. GSA believes that if it were, it would show even greater benefit.
Benefits to Owners AND Community
Regardless, even though they provide a positive payback to owners, benefits to the community have the greatest positive impact. They provide net present value savings of almost $38 per square foot of roof, according to the GSA.
It is important that green roofs have a suitable drainage path for excess water that is not absorbed during larger storms. All green roofs should be designed to move excess water away from the building. This water can then be directed to rain gardens or cisterns.
However, green roofs won’t work for everyone. The increased weight requires additional structural support. And the slope must be gentle. They’re primarily for flat or slightly sloping roofs. All those factors make retrofitting them to pre-existing buildings difficult. Generally, engineers must plan for them before construction of a building.
Posted by Bob Rehak on 1/14/23, first in a series on green infrastructure
1964 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/20230114-Screenshot-2023-01-14-at-6.25.25-PM.jpg?fit=1200%2C680&ssl=16801200adminadmin2023-01-14 18:29:142023-01-14 18:52:11Green Roofs Help Reduce Runoff and Energy Use
On October 28, Royal Pines flooded a neighbor on less than an inch of rain. Two months later, on December 29th, the same thing happened again. The video below provided by the homeowner shows the volume of water funneled across her property by the developer.
Video from NW corner of Royal Pines
This video and the previous one from October demonstrate the dangers of clearcutting and redirecting drainage without first constructing sufficient stormwater detention capacity.
The homeowner who shot the video lives adjacent to the left border in the photo below. Royal Pines has apparently sloped its property toward that corner where contractors will eventually build a stormwater detention basin.
Looking N across Royal Pines. This and other photos below taken on 1/3/23.
Land now slopes toward where video was filmed at left corner. But that area used to slope in the opposite direction. See details below from the USGS NATIONAL MAP and the developer’s plans.
Green arrow on left shows location of homeowner’s property. Red X within V-shaped contour shows exact location of low point (graph on right) before clearing and grading the land.
There used to be an 8-foot drop east of the homeowner’s property. But now, instead of water flowing directly north to White Oak Creek, it flows northwest.
The general plan for Royal Pines (below) shows the same V-shape in the proposed detention basin (upper left). The line represents the edge of the floodplain and confirms that the developer A) knew about the slope and B) changed it.
Royal Pines General Plan.
Silt Fence, Trench Ineffective Against That Much Water
The video above and the photos below show that silt fence makes a terrible dam against even small rains funneling toward a point from such a large area.
Exercise in futility. A series of silt fences have done little to catch and slow the water...or the silt. Note erosion deposited in woods.Looking south. The developer apparently tried to divert runoff racing toward the homeowner with a trench. But erosion from the barren land rapidly filled it in. Runoff also collects at the entrance to Royal Pines. Looking ENE from the entrance at the northern end of West Lake Houston Parkway.
Unfortunately, the developer plans to build homes there, not another detention basin.
0.88 Inches of Rain Fell in Two Hours
The graph below from the Harris County Flood Warning System shows that .88 inches of rain fell in the two afternoon hours before the homeowner shot the video.
Homeowner shot video after first two bars on left.
The table below shows that that much rain in two hours constitutes less than a 1-year rainfall event.
Atlas 14 rainfall probabilities for this area.
That’s consistent with actual observed events and climate records. According to the National Weather Service, on average, we can expect rainfalls greater than 1 inch 14 times per year in Houston. That’s about once per month.
Woodridge Village Revisited
The Montgomery County Engineer’s Office has reportedly asked the developer’s engineering company to revise its plans. The homeowner says that according to the engineer’s office, not even a 6-7 foot tall berm around that portion of the property would be enough to stop all the water flowing in that direction.
So, what lessons can we learn from this example? As with Woodridge Village, don’t clear and grade this much land before constructing detention basins!
The first sentence of Section 11.086 of the Texas Water Code states that “No person may divert … the natural flow of surface waters in the state, or permit a diversion … to continue, in a manner that damages the property of another…”
Posted by Bob Rehak on 1/13/2023
1963 Days since Hurricane Harvey
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/01/Keyframe-Royal-Pines-Flood-2.jpg?fit=1200%2C675&ssl=16751200adminadmin2023-01-13 10:01:062023-01-13 10:38:08Royal Pines Floods Neighbor on Less Than 1″ of Rain … AGAIN
On January 9, 2023, FEMA released a Simplified Procedures policy for Public Assistance grants to speed up recovery for applicants. Small projects are now defined as those up to $1 million.
The new policy should reduce administrative burdens and enable communities to recover more quickly after presidentially declared events by streamlining documentation requirements.
FEMA will accept estimates with summary information and the applicant’s certifications for damage and work, instead of requiring applicants to provide full or detailed documentation.
FEMA Press Release
FEMA conducted a review in 2020. It showed that if a $1 million threshold were applied, 94 percent of projects would be considered small and help put additional recovery dollars in the hands of applicants faster and accelerate closure of projects.
FEMA intends to continue adjusting the threshold annually to reflect changes in the Consumer Price Index. It also intends to review the base threshold every three years.
The new policy is not directly aimed at individuals, but at state and local governments and certain types of private nonprofit organizations. Public Assistance grants cover such things as:
Disaster-related debris removal
Emergency protective measures
Repairs to damaged or destroyed infrastructure (i.e., roads).
FM1010 Washout during Harvey at Rocky Branch in Plum Grove near the East Fork. Still not repaired after 5.5 years.
Depending on repair cost and other factors, the road washout above is an example of the type of project that might benefit from the new policy. However, it’s not clear whether the simplified procedures apply retroactively to damage from past disasters or only future disasters. More details will follow.
Applicant has legal responsibility to perform the work
Cost is reasonable.
Once FEMA and the state review and approve the government agencies’ or nonprofits’ RPAs, applicants work with their FEMA representative to develop a damage inventory.
FEMA obligates funds to the state once a project meets Stafford Act eligibility requirements. The state is the official recipient of FEMA federal assistance. The state is then responsible for disbursing the money to applicants.
FEMA will hold a series of webinars in coming weeks to explain more about the simplified policy. Additional details are not yet available.
Getting aid to people faster after a disaster is necessary. This is a very complex subject. I wish all forms of disaster relief, including hazard mitigation, could be simplified. We’re still waiting on the Harris County, the GLO and HUD to agree on a plan for spending $750 million in mitigation funds related to Hurricane Harvey – 5.5 years after the event!
Posted by Bob Rehak on 1/12/23 based on a FEMA Press Release
1962 Days after Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/10/20201025-DJI_0919.jpg?fit=1200%2C900&ssl=19001200adminadmin2023-01-12 13:04:432023-01-12 13:20:54FEMA Simplifying Procedures for Small Public Assistance Grants
