Update: 10/28/22 11am: Today’s reports indicate the highest severe storm risk is shifting SW of Houston and offshore. Experts now predict 1-2 inches of rain for the Houston area today.Areas offshore are already getting 2-4 inches per hour.
Tomorrow will likely bring strong thunderstorms. Rainfall rates could exceed the capacity of street drains leading to localized street flooding. And the severe weather may also spin up some tornados, according to Harris County’s meteorologist and the National Weather Service (NWS).
NWS predicts two to three inches of rain could fall on Friday, as warm, moist air pushing in from the Gulf collides with a cold front pushing in from the northwest. Jeff Lindner, Harris County meteorologist, predicts the worst period for us will be Friday afternoon.
The NWS Storm Prediction Center in Norman, Oklahoma, issued this warning for Friday . It shows a marginal risk of severe weather for the entire Houston area and a slightly higher risk for areas south and west of us.
Reasons for Concern
For the weather wonks reading this, Lindner cites an unusual convergence of storm systems at different levels of the atmosphere.
A trough will begin to move eastward toward Texas later today. Surface pressures will begin to fall this afternoon as low pressure develops ahead of the approaching mid-level low. Southeast winds will increase today, letting Gulf moisture quickly return to coastal Texas.
As the mid-level low approaches us, it will meet the northward-moving, moisture-laden warm front moving in from the Gulf.
Severe threats will be highest along the boundary. Tropical moisture will march quickly northward tonight on a 30-knot low level jet. Precipitable waters – the amount of moisture in a column of air – will equal 1.8 inches by Friday morning over much of the region.
As large-scale lift increases over the developing warm sector, showers and thunderstorms will develop from southwest to northeast across the region.
The cold front associated with the mid-level low will sweep west to east across southeast Texas on Friday afternoon, touching off more thunderstorms. The front will slow Friday night, so showers will linger over the area.
The surface low approaching from the northwest will meet the warm front coming from the opposite direction along a NW to SE axis on Friday. This warm front will extend from near San Antonio to near Freeport during the day and produce strong to severe thunderstorms. Low-level winds near the warm front will circle back toward the ESE and enhance low-level storm rotation.
Such collisions are notorious for tornado production, according to Lindner. Discrete cells may develop ahead of the line of storms approaching from the west. The location of the greatest severe risk will depend on where the warm front sets up Friday morning. Areas along and south of the front will have the highest risk.
If the warm front moves just a few miles farther north, it will increase risk to the Houston metro area. Kingwood was struck by tornados in a similar setup earlier this year.
Damaging winds will be the main threat. The worst of the storms should be over by 3-5 pm Friday, but lighter rains may linger well into the evening hours.
Moisture will deepen Thursday into Friday. By Friday morning, a saturated air mass will be in place over the region. “Strong divergent lift coupled with low-level inflow will increase the potential for heavy rainfall along with cell training from southwest to northeast.”
Lindner describes himself as “aways wary of such setups.” They can help anchor and train convection.
These storms could become significant rainfall producers – if they become sustained along the warm frontal boundary. The good news is that the ground is dry and can handle several inches of rainfall. “However, rainfall rates may exceed localized drainage capacities and result in some street flooding regardless of the dry ground conditions,” says Lindner.
Cloudiness should linger much of Saturday keeping temperatures in the 50’s under northerly winds. South of the cloud line temperatures will warm into the 70’s. Where that line will be Saturday is hard to determine. Clouds should erode Saturday night with mostly clear skies. Sunday will be mild.
The hurricane season has another month to go. It isn’t over yet! The National Hurricane Center now gives an area of low pressure moving WNW across the Caribbean a 50% chance of turning into a tropical depression in the next five days. No one is yet predicting what will happen if it does.
Posted by Bob Rehak on 10/27/22based on information from Jeff Lindner, NWS, and NHC
1885 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2022/10/Rainfall-10.28.22.png?fit=793%2C561&ssl=1561793adminadmin2022-10-27 14:16:182022-10-28 10:52:03Strong Thunderstorms, Street Flooding, Tornados Possible Tomorrow
Harris County Commissioners Court considered a motion today by the County Administrator to change the prioritization of flood-bond projects for the fourth time. By a 3-2 party-line vote, they approved a proposal that could soon lead to depriving outlying neighborhoods of flood bond funding. The vote today was preliminary. Before they take a final vote, they will submit the proposal to the Community Flood Resilience Task Force (CFRTF) for input, then take a final vote in 60 days. Based on past experience, the CFRTF will likely rubber stamp the three recommendations in the proposal:
Exclusion of partner funding
Inclusion of street flooding in 500 year floodplain
Counting people not structures when measuring benefits
Exclusion of Partner Funding
The exclusion of partner funding will mean that 90% match grants from the US Department of Housing and Urban Development (HUD) will no longer be available to anyone. Inner city neighborhoods will use flood-bond money to complete their projects instead of HUD money. And more affluent, outlying neighborhoods do not qualify for HUD grants.
County Judge Lina Hidalgo, Precinct 1 Commissioner Rodney Ellis, and Precinct 2 Commissioner Adrian Garcia all admitted during debate that there wasn’t enough money to complete all the bond projects. But they voted to consider the allocation changes regardless.
Precinct 4 Commissioner Jack Cagle and Precinct 3 Commissioner Tom Ramsey also agreed there wasn’t enough money to complete all bond projects. However, they voted against the proposal.
The 3-2 vote will send the proposal to the CFRTF for input. To date, the CFRTF has rubber stamped everything proposed by Democrats that benefits low-to-moderate income (LMI), inner-city neighborhoods at the expensive of outlying neighborhoods.
That means construction funds may not be available for outlying projects by the time inner city neighborhoods complete theirs.
Those who compiled the list of bond projects were counting on approximately $2.5 billion in partner funding. The Flood Control District has already secured more than a billion just three years into a ten year bond. But this move could now jeopardize a large portion of the remaining partner funding.
Inclusion of Street Flooding
Not one project in the flood bond addressed street flooding. That is not within HCFCD’s scope of responsibility.
Regardless, Commissioner Garcia said, “People don’t care where they flood from. They just want it fixed.” He never addressed the budget issue or who was responsible for cleaning out those roadside ditches – Garcia, Ellis, Turner and other City mayors!
Expanding the scope of the bond and eliminating partner funding will mean even fewer dollars left over to address flooding in outlying neighborhoods.
Counting People Not Structures
Typically, the objective of flood-mitigation projects is to remove structures, not people, from a flood plain. By counting people, not structures, in an evaluation matrix, you push funding toward more densely populated neighborhoods. Normally, helping more people is good. But what if the density is vertical, not horizontal?
Let me give you an example. Consider an apartment building with a hundred residents. But none lives on the ground floor.
Now consider 25 single family homes each with three people. All live on the ground floor.
Project A could take a 100 people out of the flood plain whose apartments would not flood. Project B would take 75 people out of the floodplain and prevent damage to 25 structures that would flood. Should A or B get the flood-mitigation project?
This provision would also drive funding away from outlying neighborhoods which generally have fewer apartments.
The People Spoke and Are Being Ignored
The People – with a Capital P – voted on the flood-bond and approved it overwhelmingly. Now its being repeatedly changed by a few individuals to push ever more funding to inner-city neighborhoods which already get the lion’s share. These latest moves could deprive outlying neighborhoods of construction dollars needed to complete projects.
Seems to me that the three Dems and their proxies are depriving half the county of their votes and taxes.
The two Republicans on Commissioners Court, Precinct 4 Commissioner Jack Cagle and Precinct 3 Commission Tom Ramsey, argued against the changes.
Commissioner Cagle argued that “We must do what we say. We must work on projects in the bond.” He went on, “Changing the projects included in the 2018 flood bond is a bad idea. The promises we made to voters in 2018 are sacred. While I support the concept of asking to finance more flood mitigation projects in the future, the public has to know that we can be trusted to keep our word.”
Top 4 LMI Watersheds Receive 53% of All Funding since 2000
However, when you look at spending to date and the ever-changing “equity” guidelines, we’re far from approaching anything that resembles equity. And we’re getting farther from it with each round of changes to the so-called “equity” guidelines.
For the record, that’s $1.6 billion out of $3.1 billion during the period of comparison.
Top LMI Watersheds Get More than Twice as Much as Top NON-LMI Watersheds
Comparing those 4 LMI watersheds with the most dollars to the four NON-LMI watersheds with the most, we can see that LMI watersheds have received more than two dollars for every dollar received by a non-LMI watershed.
The four LMI watersheds receiving the most money included Brays, Greens, Sims, and White Oak Bayous.
The four NON-LMI watersheds receiving the most included Cypress Creek, Addicks, San Jacinto and Buffalo.
All dollars include HCFCD and partner spending from 1/1/2000 through Sept. 30, 2021.
Bottom 4 LMI Watersheds Get 3X More than Bottom 4 NON-LMI
At the opposite end of the spectrum, the four LMI watersheds receiving the least money have received 3X more dollars than the four lowest NON-LMI watersheds since 2000.
There are only 8 LMI watersheds hence the comparison of groups of four.
The four LMI receiving the least dollars since 2000 include Halls, Hunting, Goose Creek/Spring Gully, and Vince.
The four NON-LMI watersheds receiving the least include Luce, Galveston, Jackson and Carpenters.
But what about those other NON-LMI watersheds in the middle of the spending pack? Simple. Altogether, the scale is already so tilted, they can’t tilt the balance back much. See comparison below of ALL LMI and NON-LMI watersheds.
Partner Funding Also Favors LMI Watersheds, Not Affluent Ones
Anyone who doubts the percentages above can check my calculations. Here’s the raw spending data for each watershed with percentages of low-to-moderate income residents – including pre- and post-Harvey spending.
I’ve also included partnership funding since 2000 for each watershed. Because the dollars involved vary widely and because Non-LMI watersheds outnumber LMI watersheds 2:1, the fairest way to compare partner funding is by looking at it as a percentage of total funding for each watershed since 2000.
During that period, 26% of all flood mitigation funding in Harris County has come from partners, such as FEMA, HUD, the Army Corps, TWDB or cities. However, LMI watersheds have attracted a higher percentage of partner spending: 30%.
While that’s not a huge advantage, it shows conclusively that LMI watersheds, as a rule, are not disadvantaged when it comes to partnership funding.
The correlation between total dollars and partnership dollars spent in all watersheds is not a perfect (1.0), but very high at .79.
In fact, the two highest partner percentages both belong to LMI watersheds (Sims at 55% of the watershed total and White Oak at 33%). The two lowest partner percentages belong to two of the most affluent watersheds (Willow Creek at 6% and and Barker at 3%).
Conclusion: Organize, Protest
Outlying communities must organize and protest en masse before commissioners take a final vote on shifting even more dollars to LMI communities based on bad information. If they change the deal on this flood bond, they’ll do it again on the next.
Fool me once, shame on you. Fool me twice, shame on me.
Posted by Bob Rehak on 12/14/2020
1568 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/2021/12/Screen-Shot-2021-12-14-at-8.56.24-PM.png?fit=1616%2C854&ssl=18541616adminadmin2021-12-14 22:23:322021-12-15 09:44:23Move by Dems Could Mean Flood-Bond Projects in Outlying Neighborhoods Never Get Built
A front moving into the region could bring high hourly rainfall rates and rapid street flooding, according to Jeff Lindner, Harris County’s meteorologist. He says, “A weak front will move into the area today and tonight, and stall near the coast or just offshore on Tuesday and Wednesday.”
Slow-Moving Front, Training Cells, Possible Street Flooding
“The slow-moving front is moving southward across north and central TX. Numerous showers and thunderstorms have already formed along it. The air mass in the Houston region will become increasingly unstable this afternoon. Expect numerous, slow-moving showers and thunderstorms to develop across the region,” says Lindner.
“The combination of slow movement, deep tropical moisture, and the potential for training all points toward a heavy rainfall threat this afternoon,” he said.
Mainly South of I-10 and Offshore by Tomorrow
Lindner continued, “The front will push toward the coast tonight and may even move offshore on Tuesday. A slightly drier air mass will build into the region behind the front with rain chances focusing near the coast and across Gulf waters later today and tomorrow.”
He sees the main rain chances on Tuesday for areas south of I-10. However, he also predicts much of the activity will be offshore.
Enjoy the slightly drier air mass and “cooler” temperatures behind the front as it washes out by late week. After that, onshore flow will return along with humidity. “By next weekend, heat index values could near advisory levels,” Lindner warns.
Tropics to Pick Up by Mid-August
On an unrelated topic, Lindner sees no concerns for the next 5 days for tropical development in the Atlantic basin. However, Lindner sees signals that the Atlantic basin will become increasingly favorable for development toward mid August.
Posted by Bob Rehak on 8.2.21based on information provided by HCFCD
1434 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/08/Radar-8.2.21-noon.jpg?fit=1200%2C1677&ssl=116771200adminadmin2021-08-02 12:26:042021-08-02 12:27:55Possible Street Flooding Later Today
Seventh in a series of eight articles on flood-mitigation funding in Harris County.
For the last two years, I’ve heard the same tirades in Commissioners’ Court – that rich neighborhood’s get all the flood-mitigation money while the poor neighborhoods get none. According to Commissioners Ellis and Garcia, that’s because higher home values in rich neighborhoods generate higher Benefit/Cost Ratios and therefore get more FEMA grants. Problem is, FEMA looks at many other factors. And HUD grants favor low-income neighborhoods. But you never hear Ellis or Garcia talk about those.
In reality, most flood mitigation-money in Harris County goes to watersheds with high percentages of low-income residents. (See links to previous posts below.)
In the most flooded parts of Halls and Greens watersheds, street after street has clogged ditch drains. Responsibility for cleaning those drains falls onto, you guessed it, Ellis and Garcia, along with their counterpart at the City of Houston, Mayor Sylvester Turner.
Simple FOIA Request Disproves Narrative
The Ellis/Garcia narrative just didn’t sound right to me. So I submitted a Freedom-of-Information-Act (FOIA) request to the Harris County Flood Control District in March for historical funding data. I wanted to see if the allegations were true. They’re not.
Analysis shows that the Ellis/Garcia narrative is 180-degrees from the truth. By almost any statistical measure, flood-mitigation spending favors the poorer watersheds in Harris County. That’s where most of the damage is.
Verbal Sleight of Hand Deflects Attention from Who’s Responsible
So, what’s going on here? Why the constant barrage of racial accusations and divisive rhetoric?
They seem designed to deflect attention from those responsible for a crucial part of the problem: street drainage.
And if you don’t fix that, you will never solve flooding no matter how much money you throw at channel widening, detention ponds and green solutions.
A process engineer in the oil and gas industry once told me, “There’s always a bottleneck in every system somewhere.” And one of the biggest issues in neighborhoods that flood repetitively is street drainage. Water can’t get out of the neighborhoods to the bayous.
Poor Ditch Maintenance Contributes to Street Flooding
By alleging racism in the HCFCD funding, Commissioners Ellis and Garcia are deflecting attention from a serious issue; many of the neighborhoods in their jurisdictions have awful internal drainage (streets and storm sewers) that contribute to frequent street flooding. Street flooding happens when high rainfall rates exceed the capacity of storm drains and ditches to carry the water away. The reduced capacity of the ditches below makes the streets flood on smaller rains.
Vasquez says that after a heavy rain, this drain backs water up throughout his neighborhood and contributes to flooding. He says it can take up to 3-4 days for water to drain away. Completely unprompted, he then said that Kingwood was getting all the help from the City. I told him that I lived in Kingwood and that our drains were just as bad as his. See below.
But I digress. Here are some more street drainage photos taken on 6/26/21 in Halls and Greens Bayou Watersheds as well as Kashmere Gardens on the southeast corner of US59 and Loop 610.
Wherever I drove for five hours, residents repeatedly told me that because of poor maintenance, water has a hard time getting out of neighborhoods. It must either sink in or evaporate. See below.
To be fair, not all the ditches were this bad. But I saw thousands like these on hundreds of streets while driving around for five hours. Sometimes sediment almost completely covered drains. I often had hard times spotting the pipes.
The saddest sight I saw all day was this home on Etheline Street between Homestead and US59.
With drainage this bad, water may evaporate or infiltrate faster than it flows out of neighborhoods!
Who is Responsible for Streets and Storm Sewers?
Who is responsible for clearing blockages like these? Not the Harris County Flood Control District.
Who is responsible for the unincorporated areas of Harris County? The Precincts. And the worst drainage happens in Precincts One and Two with Commissioners Ellis and Garcia.
Why does Kashmere Gardens (in the City) have open ditch drainage that hasn’t been maintained in years?
How do areas in East Aldine still have barely functional roadside ditches and residents who do not have municipal water and sewer service?
Commissioners Ellis and Garcia have the power and the money to address these issues. Yet they have chosen not to. Why have they not helped the very people they claim are left behind?
Show Us the Data
It is important to note the questions NOT being asked in this so-called “equity” debate.
How much has the City of Houston invested in these flood-damaged areas to remediate drainage?
How much have Precincts 1 and 2 invested?
What drainage projects have they completed since 2000?
What is the capital improvement plan for each precinct, and how much of that includes drainage improvements?
What is the equity prioritization framework for precinct spending?
How much unspent money does each precinct have for infrastructure?
The answers may point right back at the people making racial accusations.
The City and Commissioners Ellis and Garcia need to provide answers. Let’s see the data. How much have the City and the Precincts spent in these areas? If these areas are underserved, Commissioners Ellis and Garcia, and Mayor Turner are responsible.
They have claimed transparency is important to them. The time to prove that is now.
Blaming the problems on racial discrimination is an easy sell in minority neighborhoods. But it’s misdirection and it keeps the spotlight off Commissioners.
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/2021/06/20210626-RJR_8673.jpg?fit=1200%2C800&ssl=18001200adminadmin2021-06-27 12:35:382022-01-03 15:25:38Looking Through the Wrong End of the Drainpipe: The Politics of Misdirection
Fourth in a series of eight on flood-mitigation funding in Harris County
Since 2019, Commissioners Ellis and Garcia have harped on the need for more “equity” in flood-mitigation funding. They and some residents in their precincts allege that all the money is going to high-income watersheds while minority, low-income watersheds get “none.” Ellis repeatedly complains that Harris County Flood Control District gives those minority neighborhoods “back-of-the-bus” treatment. Garcia says he feels like he was “hit with a baseball bat.”
Unfounded Allegations of Racism in Construction Funding
In March, I became so alarmed at the allegations of racism, that I submitted a Freedom of Information Act Request to see if they were true. They aren’t. Funding data for new construction projects dating back to 2000 shows that:
Those first three articles in this series should suffice to disprove discrimination against minority, low-income watersheds. But more statistics just keep jumping out of the data.
So, today let’s compare watersheds with percentages of low-to-moderate-income (LMI) residents above and below 50%:
The low-income group has 7 watersheds, comprising 584 square miles.
The high-income group has 14 watersheds, comprising 1123 square miles.
The two groups vary radically in number and geographic size. So, to provide a valid comparison, we must evaluate them first on a per-square-mile basis. This pie chart shows how the smaller, low-income group gets triple the dollars per square mile.
Watersheds Above/Below 50% LMI
Here are the percentages of LMI residents in each group.
Lower Income Watersheds Get 3X More Construction Funding Per Square Mile
On a per-square mile basis, the low-income group averaged $2.5 million. The high-income group averaged only $0.8 million. See Table 2 below.
Smaller, Low-Income Group Also Receives About a Third More in Total Dollars
Comparing the total dollars (not $/square mile) received between the two groups is also illuminating.
In total dollars, the low-income group of 7 received $400 million dollars more than the high-income group of 14 since 2000. That skewed the averages back toward 3X again. See Table 3.
But More Damage in Low-Income Group
As we have seen elsewhere in this series, dollars flow to damage. Low-income watersheds had twice the total damage despite being half the size and number.
In four major storms since 2000 (Allison, Tax Day, Memorial Day and Harvey), the seven low-income neighborhoods had 146,832 structures damaged, compared to 70,719 for the higher income group of 14. However, on a per square mile basis, low-income group had four times as much (251 vs. 63).
*Vince Bayou omitted from the first group because it lies almost wholly within the City of Pasadena and is the City’s responsibility. Little Cypress Creek also omitted from second group because it is a newly developing area. Very few people live there and that skews statistical comparisons. HCFCD spending in Little Cypress relates to an experimental “frontier program.”
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/06/Screen-Shot-2021-06-24-at-7.44.08-AM.png?fit=1112%2C340&ssl=13401112adminadmin2021-06-24 09:56:492021-06-24 10:05:34Low-Income Watersheds Get Three Times More Flood-Mitigation Funding Per Square Mile
Had Harris County Flood Control not recently excavated parts of Bens Branch and Taylor Gully, both streams would have likely come out of their banks today. The skies opened up and dumped 4.98 inches on my rain gage in a little more than two hours. That’s about a 10-year rain according to the new Atlas 14 statistics below.
Photos from Around Kingwood
At 5 pm both streams were near the tops of their banks but well within them. That might not have been the case just a couple months ago before the flood control district widened and deepened them to restore their original conveyance. Parts of Ben’s Branch were down to a two year level of service. That’s means they would flood in a two-year rain…obviously less than today’s.
Forecast for Remainder of Evening
As of 5:30 pm, Jeff Lindner, Harris County Meteorologist said, “Heavy rainfall continues to progress WSW across the area while a second area of heavy rainfall is moving SE across western Montgomery, N Waller, and NW Harris County. This area to the northwest is the remains of a line of thunderstorms from central Texas.”
“Rainfall amounts have averaged 2-3 inches over the northern half of Harris County with 4-6 inches over the Humble, Kingwood, Crosby, and Huffman areas,” said Lindner. “Significant street flooding has occurred over the northeast and northern portions of the county into Liberty and Montgomery Counties. While the activity is continuing to progress through the area, recent radar and HCFCD gage rainfall sensors indicate the hourly rainfall rates have weakened into the .50-1.5 inch range which is significantly lower than the 3-4 inches per hour recorded earlier this afternoon.”
“Street flooding will continue into the early evening hours and slowly subside over the area, while creeks and bayous continue to respond to the heavy rainfall. At this time all creeks and bayous are well within banks.”
More Yet to Come
Heavy rainfalls like this afternoon’s should continue through Thursday when the chances start to diminish through the weekend. Runoff should increase as grounds are now thoroughly saturated. Stay cautious. I almost drove into the water that rose to the bumper of that semi above. It didn’t look that deep but obviously could have stalled my Tahoe. Remember, if water gets over your tailpipe, it will cause your engine to stall. Game over.
Posted by Bob Rehak on May 17, 2021 based on personal observation and information supplied by HCFCD, Jeff Miller, Paul Campbell, and Nicole Black-Rudolph
1357 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/05/20210517-RJR_6615.jpg?fit=1200%2C800&ssl=18001200adminadmin2021-05-17 18:05:152021-05-17 18:10:21Street Flooding Rampant Throughout Kingwood, Streams Near Capacity
What causes street flooding? At the risk of clarifying the obvious, rain accumulates faster than storm sewers and drainage ditches can carry it away.
A Lack-Of-Capacity Issue
Most streets are actually designed to be part of the flood retention system in any community. That’s because most storm sewers can only handle a two-year rain (about 2 inches per hour). When we get more than that – say a 10-, 25-, 50- or 100-year rain – water is stored in the street until capacity opens up in the storm sewers, ditches and creeks.
As you can see from the new Atlas-14 rainfall chart below, a 2-year rain in this area is 2.23 inches/hour; a 25-year rain 3.88 inches/hour; and a 100-year rain 4.88.
When evaluating rainfalls, look at the storm totals AND shorter intervals, such as 15, 30 and 60 minutes.
Street flooding usually results from short, high-intensity downpours caused by slow-moving or training thunderstorms.
From a street-flooding perspective, getting 4 inches of rain in one day is not the same as getting 4 inches in one hour.
If you get 2 inches of rain in 30 minutes, you’re already at a 5-year rain. That’s well beyond the design capacity of storm sewers. You can expect water to back up into the street at that point, even if there are no blockages in the storm sewers.
That’s why builders elevate most homes several feet above street level and above the 100-year flood plain. It gives you an additional margin of safety.
How To Determine Intensity of Rainfalls
If you flooded from your street, first determine whether the cause was simply overwhelming rainfall or whether complicating factors existed.
How can you determine how much rain you got in any given time interval during a storm? Follow these simple steps:
Click on the gage nearest you. (For me, that’s Gage #755 at the San Jacinto West Fork and West Lake Houston Parkway. I will use that in the example below.)
In the pop-up window, click on the “For More Information” button.
At the top of the next window, select date and time intervals. The Time Interval varies from One Hour to One Year. I selected September 19, 2019 (the day of Imelda) and 24 hours. That shows me 24 1-hour intervals. From this and the table above, you can see that we had three very intense hours in a row during Imelda.
From the two charts above, correlate the actual precipitation with the recurrence intervals. You can see that…
We had a 10-year rain, followed by a 5-year rain, followed by a 2-year rain – all in three hours!
Every single one of those hours met or exceeded the maximum capacity of the storm sewers. So it’s easy to see WHY we had street flooding.
When Street Flooding Turns into Home Flooding
In a small percentage of cases, street flooding turns into HOME flooding – when there simply isn’t enough backup capacity in the streets. (In the following discussion, I’m EXCLUDING homes that flooded from rivers, streams, or overland sheet flow during Imelda, i.e., Ben’s Branch, Elm Grove, etc.).
Extreme events reveal the weaknesses in any system. If your home was:
At a low point on the street…
Near a clogged storm drain…
A foot or two lower than surrounding homes…
At the bottom of a hill…
In an area where water collected or converged…
Near an outfall pipe that collapsed or was blocked…
Upstream from a ditch that was blocked…
…you may have flooded.
And then there are the bizarre cases.
I visited one man in Trailwood at the bottom of a hill that had NO storm drains. Inexplicably, someone placed the nearest drain in the middle of the hill – about half a block ABOVE his home.
Another man called me who lived near Village Park Drive next to a tributary of Ben’s Branch. The Community Association had erected a fence between the end of the street and the tributary. They built the fence so low to the ground that it became clogged with weeds and grass clippings during Imelda and formed a dam. In the heavy rain, water could not get under it and backed up into his home.
What Can You Do?
Short of praying or digging up every street in Houston to enlarge the storm sewers, homeowners DO have some remedies.
Keep storm drains clear. Keep yard waste out of them.
Call 311 for a storm-drain inspection if you suspect yours have become clogged. The City is currently inspecting ALL drains in Kingwood subdivisions that had street flooding last year.
Inspect outfall pipes where your storm drains enter the nearest ditch to ensure they have not collapsed or become blocked.
Look out for new construction, such as the fence above, that may back water up. Remove or elevate the horizontal rot board if it blocks the overflow of water from your street.
If the problem recurs in less extreme events, consider flood proofing or elevating your home.
Make sure you have flood insurance; that it’s up to date; and that it reflects the true replacement value of your home.
Great Options Where Possible
If your area floods repeatedly, you may also be interested in lobbying the City or County to build an overflow spillway or detention pond between your street and the nearest drainage channel. Obviously, geographic circumstances may rule this possibility out for many. But if you have a vacant lot in your neighborhood and a nearby ditch…
Posted by Bob Rehak on 2/22/2020
907 Days after Hurricane Harvey and 156 after Imelda
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/02/20200203-RJR_7540.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-02-22 19:33:112020-02-23 04:47:14Street Flooding: Causes and Cures
The National Weather Service has issued an urban and small stream advisory for the northern Lake Houston Area. It extends across north Houston up to Conroe. Expect street flooding.
According to Harris County meteorologist Jeff Lindner, the center of Imelda is drifting over southwest Montgomery County as of late Wednesday morning. Lindner adds that “lull” in heavy rainfall over Harris County should last until early afternoon. Expect rain to pick up significantly between mid afternoon and evening.
Flash Flooding Possible
The National Weather Service cautions that heavy downpours with rainfall rates between 2-4 inches per hour are possible. That’s enough to cause street flooding.
The National Weather Service in League City has issued a
* Urban and Small Stream Flood Advisory for...
Southwestern San Jacinto County in southeastern Texas...
Southeastern Montgomery County in southeastern Texas...
West central Liberty County in southeastern Texas...
Northeastern Harris County in southeastern Texas...
* Until 1245 PM CDT.
* At 949 AM CDT, Doppler radar indicated heavy rain that will cause
urban and small stream flooding in the advisory area. 3 to 6
inches of rain have already fallen across portions of these areas
and additional rain is expected during the next several hours.
* Some locations that will experience flooding include...
Conroe, Humble, Jersey Village, Willis, Aldine, Northside /
Northline, Kingwood, The Woodlands, Greater Greenspoint, Spring,
Spring Branch North, northeastern Addicks Park Ten, Oak Ridge
North, Panorama Village, Shenandoah, Splendora, Patton Village,
Roman Forest, Woodbranch and Cut And Shoot.
Incredible Rainfall Rates South of Houston
Incredible rainfall rates of 3-4 inches per hour have resulted in a 24 hour storm total of 21.34 inches at Sargent with 7.56 inches falling in 1.5 hours and 10.72 inches in 3 hours this morning. This shows the potential of this air mass to produce excessive rainfall in a short period of time.
Heaviest Rainfall Expected Along US59
As the air mass heats late this morning, expect renewed development along/near the US 59 corridor.
Where exactly this band develops and how defined it becomes remains in question. But higher intensity rainfall rates will be possible in the afternoon and evening hours.
Rainfall Total Forecast
Expect an additional 2-4 inches with isolated amounts of 6 inches this afternoon through Thursday morning. Remember, 2 inches per hour can cause street flooding. Don’t drive through high water. Park your car on high ground.
To check the rainfall rate per hour, go to http://harriscountyfws.org, click on the a gage near you, then click the “for more information” link that pops up.
Posted by Bob Rehak on 9/18/19 at 10:45 am
750 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/09/image8-1.png?fit=725%2C408&ssl=1408725adminadmin2019-09-18 11:02:262019-09-18 11:08:16Center of Imelda Drifting Over SW Montgomery County as of Late Morning Wednesday
Edy and Ricky Cogdill live across the street from Abel Vera on Village Springs Drive. Both the Veras and the Cogdills live at the end of the street. Their properties butts up against the new development on the other side of the Montgomery County line seen in the background of this video. Edy Cogdill shot the video on May 7, 2019. It shows what hydrologists call “overland sheet flow.”
Edy Cogdill shot this video will standing on her front porch with an umbrella. As the floodwaters came out of the clear-cut area to their north, the water hit the Cogdill house and started moving sideways. Toward the end of this short video, Edy pans right. You can see the the flow coming out of the new development and rushing down Village Springs Drive past the dead-end barrier.
The water from the development added to street flooding in progress. As a result, homes flooded.
Harris County Flood Control Issues Report on Storm
The report says: “130 structures were flooded in the Elm Groove Village subdivision in the northern portions of Kingwood on Tuesday evening. HCFCD staff investigated this area on Wednesday, May 8th and determined that the flooding was potentially caused by development upstream in Montgomery County that sent large volumes of sheetflow into the subdivision and Taylor Gully (G103-80-03.1). The isolated nature of the heavy rainfall on Tuesday afternoon prevented more widespread flooding impacts.”
Lindner also cautioned that the number of affected structures may change; the City of Houston is still verifying the number. Earlier media reports of 400 homes flooding may have overstated the problem.
2- to 50-Year Official Rainfall Rates
The Harris County Flood Control Report on the storm also states that on May 7: “Heavy rainfall rates developed due to slow storm motions over northeast Harris County including the Humble and Kingwood areas. A 30-min rate of 2.9 inches was recorded at US 59 and the West Fork of the San Jacinto River and a 1 hour rate of 4.0 inches. A 6-hr rainfall rate of 7.9 inches was recorded at the East Fork of the San Jacinto River and FM 1485. Rainfall rates between the 15-min and 6- hr time periods on Tuesday afternoon and evening averaged between a 2-yr and 50-yr frequency over the extreme northeast portions of Harris into southeast Montgomery Counties. This rainfall was relatively isolated in the far northeast portions of Harris County and the Kingwood area.”
Posted by Bob Rehak on 5/13/2019
622 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/05/VillageSpingsKeyframe.jpg?fit=900%2C1365&ssl=11365900adminadmin2019-05-13 12:21:322019-05-13 12:50:35Cogdill Video Shows Overland Sheet Flow From Clear-Cut Area Pouring into Elm Grove; HCFCD Issues Report on Flood
During Harvey, most of the damage in Kingwood happened from river flooding. Yesterday, it happened from street flooding. What are the respective causes? Differences? Fixes?
River Flooding Overview
River flooding happens when heavy rainfall exceeds the conveyance capacity of a river. In other words, the river comes up and out of its banks. This happened to the San Jacinto during Harvey. The river, normally a couple hundred feet wide, became three to four miles wide, inundating miles from the main current.
River flooding can be caused by heavy rain, upstream snow melt, dam/levee breaks, dam releases, and more. Most commonly, it takes hours to days for water to work its way through a river system and affect people downstream.
River Flooding Remedies
Fixes for river flooding include things like:
Building dams upstream to reduce the flow downstream.
Increasing the conveyance of the river through widening, deepening or dredging
Removing blockages such as the mouth bar on the West Fork of the San Jacinto
Increasing the outflow capacity, for instance by adding gates to dam
Diverting water to tunnels.
Street Flooding Overview
Street flooding, on the other hand, is often much more local and happens over shorter periods of time. It is often referred to as flash flooding because it comes up quickly and goes down quickly. That’s what the Lake Houston Area experienced yesterday. The San Jacinto, its tributaries and drainage ditches were and still are well within their banks.
Flash flooding occurs when the rainfall RATE temporarily exceeds the drainage capacity of storm drains, sewers, swales, and ditches that lead to rivers.
Yesterday, we received 1/20th the amount of rainfall that we did during Harvey, but many people reported the water coming up higher. That’s because storm sewers could not handle the intense rainfall that happened during approximately a one hour period.
Streets Designed as Part of Flood Retention System
The streets in Kingwood (and most cities) are actually designed to be part of the flood retention system. When developers excavate streets, they often use the fill to build up homesites. By increasing the elevation difference between street level and your foundation, they reduce the chances that you will flood.
They size the sewers so as not to make drainage ditches overflow. Rainfall rates like we experienced yesterday don’t happen for very long. The storm passes. The water in the street goes down and life returns to normal. You just don’t want to be caught out on the road in your car when it happens. Nor do you want to have your car parked on the street!
Street Flooding Remedies
The Greater Houston Flood Mitigation Consortiums’ report on Harvey contains an extensive discussion of the different types of flooding. Their discussion of street flooding starts on page 14. Page 15 identifies solutions, including:
Communicate the role of streets in the drainage system. Many residents may not be aware that roads are intended to act as a secondary short-term storage system and/or conveyance pathway for water. This can lead to severe property damage and loss of life when residents do not move property out of harm’s way. For example, recent street flooding has caused severe flooding of cars, which are frequently parked in the street. It is also important to note that 12 inches of water can float a sedan and 18-24 inches can float a larger vehicle, creating hazardous road conditions during extreme events. It is critical to develop a strategy to communicate to the public that streets are designed to be a secondary short-term storage system so that people can take action to prevent loss of property and life.
Address debris in streets and waterways. Maintaining clear openings to storm sewer inlets is a great way to help reduce street flooding. Flooding in many neighborhoods can be made worse by debris and floating trashcans that clog inlets. Additional city, county and MUD maintenance, or organized community efforts may be required.
Ensure that developers have sufficient “upstream” information. Land development engineers typically focus on mitigating the runoff generated by their development project, and as such, flows entering onto their site from other sources may not be considered in their design analysis. Examining strategies to share information about upstream conditions with developers during the design analysis phase could help maximize site-based mitigation.
Maximize on-site retention. Green infrastructure may provide a viable alternative for managing stormwater and reducing nuisance flooding through implementing on-site retention or by providing additional in-line storage capacity within the street (examples include Cottage Grove and Bagby Street).
Identify & target high-risk areas. Determining the neighborhoods most vulnerable to flooding from local drainage challenges would be a pivotal step to targeting public education and mitigation strategies.
For More Information
The flooding yesterday happened so quickly that it scared people. For many, it brought back vividly the trauma of Harvey and the pain that followed. One person even died when her car ran into a downed tree that fell across Kingwood Drive.
The most damage happened, not to homes, but to vehicles caught in high water on flooded streets – streets DESIGNED to hold water. There’s a simple answer to that. Unfortunately many people did not get the warnings that could have kept them off the streets.
For more information on different types of flooding, see the first part of this FloodWarn Training Seminar that Katie Landry-Guyton of the National Weather Service presented last year at Kingwood College.
Posted by Bob Rehak on 5/4/19
613 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/05/5.3.19-rain.jpg?fit=1500%2C2000&ssl=120001500adminadmin2019-05-04 12:23:012019-05-04 12:23:24Street Flooding vs. River Flooding