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Study Suggests Large Cities Like Houston Can Intensify Rainfall and Runoff From Hurricanes

A November 2018 article appearing in the peer-reviewed scientific journal Nature found that urban growth can intensify both rainfall and runoff from hurricanes. Further, urban growth can increase the risk of flooding and shift the location of flooding. The article specifically studied the effects of Hurricane Harvey on Houston and found that urban growth increased the probability of such an extreme flood across the basin by 21X.

A sister publication, Scientific American, reviewed the article the same month and helped explain the findings in Nature.

The Nature study looks at two distinct effects of urbanization. The first is the impact of impervious surface on RUNOFF. The second is the impact of the urban landscape’s surface roughness on RAINFALL.

The Runoff Component

Numerous studies have looked at the relationship between percentage of impervious cover, runoff, and flooding – a well documented phenomenon. Impervious cover accelerates transport of rainfall from neighborhoods to rivers. That raises peak flows rather than spreading them out over time. Dr. William Dupre, professor emeritus from the University of Houston visualized the relationship this way.

*Effect of Urbanization on Peak Stream Flows” by Dr. William Dupre, professor emeritus from the University of Houston.*

Rainfall Component Much Less Studied

However, the effect of urban growth and a city’s surface topography on RAINFALL from hurricanes is much less studied. The authors say in Nature that, “Urbanization led to an amplification of the total rainfall along with a shift in the location of the maximum rainfall.” (Page 386).

“Much less is known regarding the urban effects on the organized tropical rainfall of a hurricane, in particular during one like hurricane Harvey, which stalled for several days.” They continue, “…experiments (with computer models) clearly show a large increase in rainfall arising from urbanization over the eastern part of the Houston area.”

The authors compared present and past urban landscapes and also modeled a scenario in which the entire region was cropland.

Mechanisms Responsible for Increase Rainfall

To understand the physical mechanisms responsible for the heavier rainfall, they analyzed the vertical convergence of winds and wind fields.

Kingwood Greens Evacuation During Harvey by Jay Muscat — *Evacuation During Harvey. Photo courtesy of Jay Muscat*.

“The enhanced rainfall … and the shift of rainfall … are tied to the storm system’s drag induced by large surface roughness,” say the authors.

Scientific American explains in more detail. Kerry Emanuel, an atmospheric scientist at Massachusetts Institute of Technology, who did not work on the study said, “We know cyclones are sensitive to characteristics of the surface—mountains, streams, marshland. This new twist is that cities have become big enough to tangibly alter the storm.” Said Gabriele Villarini, an environmental engineer at The University of Iowa and an author on the study, “We removed the urban areas from Houston and replaced them with cropland.”

“The presence of urban areas enhanced all the things you need to get heavy precipitation,” Villarini, one of the study’s authors says. “A stronger drag on the storm winds, associated with a larger surface roughness length” contributed to the increased rainfall.

Emanuel explained, “First, the artificial ruggedness of an urban area slows air down. Whenever air slows in a hurricane, he says, it gets shunted toward the center of the storm and up into the sky. That increases rainfall everywhere [in a metropolitan area].” He added, “A storm moves particularly slowly over downtown areas where buildings are tallest, but the winds bearing down from outside the city are still moving quickly. So, [the storm] is piling up on the city.”

Impact on and Implications for Houston

This increase in urban growth in flat terrain creates problems from a flood perspective, despite mitigation measures already in place.

Urbanization has increased the probability of an event like the flooding associated with Hurricane Harvey by about 21 times, say the authors in Nature on page 388.

The authors make several high-level recommendations.

Urban planning must take into account the compounded nature of the risk now recognized.
Flood mitigation strategies must recognize the effect of urbanization on hurricanes.
Weather and climate models must incorporate the effects of urbanization to increase forecast accuracy on local and regional levels.

“It is critical for the next generations of global climate models to be able to resolve the urban areas and their associated processes,” conclude the authors.

About the Authors and Models

The authors are:

Wei Zhang and Gabriele Villarini from the Department of Hydroscience & Engineering, The University of Iowa, Iowa City, IA
Gabriel A. Vecchi from the Department of Geosciences, Princeton University and the Princeton Environmental Institute, of Princeton, NJ
James A. Smith from the Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ.

This presentation explains the Noah Model that the authors used to calculate air/ground interactions.

Local Questions Raised by Study

To date, the role of a city in altering rainfall during tropical cyclones has received very little attention. Houston has had the largest urban growth and the fifth-largest population growth in the United States in the period from 2001–2011. Much of that growth is now on the periphery of the city. The two fastest growing parts of the region are Fort Bend and Montgomery Counties.

As the city grows, we need mitigation measures that can offset the impact of that growth. That’s why the meeting of the Montgomery County Commissions on August 27th is so important. They will vote on whether to close a loophole that allows developers to avoid building onsite detention ponds. Closing that loophole is important. It will help protect hundreds of thousands of downstream residents as well as those in Montgomery County.

Also, the new NOAA Atlas-14 (rainfall measurements updated after Harvey) does not consider forward-looking urban growth effects. The precipitation frequency data in NOAA Atlas 14 was determined by a statistical analysis of historical rainfall, a key input for FEMA Flood Insurance Rate Map (FIRM) modeling. With all that uncertainty, we need to err on the side of caution in flood planning.

For more about Atlas 14, see this link.

Posted by Bob Rehak on 8/18/2019

618 Days after Hurricane Harvey

Cross Your Fingers: Porter Dam Replaced by Two Large Culverts Under Road to Nowhere

Last year, shortly before Christmas, I reported on flooding between Loop 494 and US59 related to an undersized culvert, nicknamed the Porter Dam.

A developer mysteriously installed two small culverts with grates in the ditch that runs on the west side of Loop 494. I say “mysteriously” because there was no apparent reason to install them. The developer also built a road over the culverts. But the road led nowhere. So there was basically no need for the project.

*Picture taken last December. The Porter Dam, an undersized culvert and an unnecessary road, backed water up for blocks.*

*The offending culvert and grate restricted flow in the ditch. Also from last December.*

*The Road to Nowhere crosses a ditch only to end at a detention pond. Photo taken December, 2018.*

Residents and businesses speculated that the real purpose of this project was to slow the flow of water from the north to speed up the flow of water from the south where a large shopping center and an apartment complex exist. While the small culvert worked wonders for those developments, it backed water up into businesses and homes for several blocks to the north.

As a result, Mike Eberle, owner of Mike’s Hobby Shop, Lakeside Plumbing and the Gulf Coast Raceway got an unwelcome early Christmas present last year. Here’s what the situation looked like before Christmas, 2018. Not good for a hobby shop!

*After the flood, Eberle complained to TxDot. Within days, a backhoe began lowering the road over the culvert*. *By lowering the road, the developer hoped to increase the conveyance of the ditch without removing the culvert.*

First Attempt at Porter Dam Mitigation Failed

However, that attempt at mitigating the Porter Dam failed. Within five months, the same area flooded again.

Last week, a reader, Dan Monks, sent me this photo. It looks like the developer is trying a third time with bigger culverts AND a lower road.

*Bigger culverts now installed under the Road to Nowhere.* *Photo 8/14/2019, courtesy of Dan Monks.*

Let’s hope this attempt works better than the last and gets things back to normal. These culverts appear to match the size of those farther up the ditch.

Please Help Shine a Public Light on Similar Problems

Hundreds of people, businesses and even a church were damaged by this thoughtless, careless project.

If you see situations that contribute to flooding, please send photos via the submissions page of this web site. By shining a public light on problems, we can encourage people to fix them.

Posted by Bob Rehak on 8/17/2019 with photos courtesy of Dan Monks and Mike Eberle

718 Days since Hurricane Harvey

TWDB to Host Two State Flood Plan Webinars on August 19

If you missed the Texas Water Development Board (TWDB) state flood planning seminar in Tomball, you still have three more options to participate.

TWDB Planning Process

The Texas Water Development Board (TWDB) will offer two webinars to discuss and solicit input on state flood planning and financing programs established during the last legislative session.

Discussion during each webinar will be guided by the issues presented in this document: Implementation of Flood Legislation from the 86th Texas Legislative Session.

Webinar #1: Monday, August 19, 9:30–11:30 a.m. CT

Webinar #2: Monday, August 19, 5:30–7:00 p.m. CT

How to Register for Webinar

To participate: Visit http://texasadmin.com/tx/twdb/ to register for the webinar.

The TWDB will launch the presentation screen approximately five minutes before the start of each webinar. Questions and comments will be addressed live during each webinar; you may email your questions and comments to FloodWebinar@twdb.texas.gov throughout the presentations.

Each webinar will be recorded and may be viewed at a later date at http://texasadmin.com/tx/twdb/.

Last In-Person Meeting at Houston City Hall

The last in-person meeting will be held on Friday, August 23rd at Houston City Hall.

Houston City Hall
Council Chamber,
2nd floor
901 Bagby St.
Houston, TX 77002
9:30-11:30 a.m.

The complete meeting schedule may be viewed on the TWDB website.

If you ever wanted to influence the way $800 million is spent, here’s your chance.

Posted by Bob Rehak on 8/16/2019

717 Days since Hurricane Harvey

Woodridge Village Plans Being Set in Concrete…Before Case Goes to Trial

Just three months ago, on May 7th, water poured out of Woodridge Village and into the streets and homes of Elm Grove. More than 200 flooded homeowners are suing the developer and contractor for negligence. Meanwhile, before the case has even gone to trial, contractors are pouring concrete. Let’s hope the drainage plans do the job. Because they are literally setting those plans in “stone,” so to speak. Here’s what’s happening north of the MoCo border.

Woodridge plans 5 detention ponds, 3 in the northern and 2 in the southern section. The two in the southern section are now at total depth. However, excavation still has not started on the three northern ponds, despite ideal construction weather.

Elevation Raised Compared to Elm Grove

Looking east along the southern border with the detention pond S1 out of frame on the left and the culvert that leads to Taylor Gully in the upper left. Village Springs in Elm Grove can be seen through the trees on the right.

The new development has been built up about four feet above Elm Grove and Woodland Hills Villages. It gives the hood a split level look.

At the top of that hill, along the perimeter, the contractor bulldozed a v-shaped notch. That’s called a backslope interceptor swale. The swale or depression collects rainwater that would otherwise drain straight into detention ponds. In theory it provides additional storage for rainwater. It also reduces the potential for erosion along the banks of the pond. That’s because water collects in the swale and drains through a pipe into the detention pond.

S2 detention pond above Village Springs in Elm Grove. Photo courtesy of Jeff Miller. Miller says that the pond looks 3 feet below the mouth to the culvert on Taylor Gully. So it will hold water constantly.

Detention Pond S1 Now Lined with Concrete

Contractors have also begun lining detention pond S1 with concrete. That should reduce erosion. It will also accelerate runoff.

*Woodridge Village Detention Pond S1 which is north of Woodland Hills Village. The ditch has reached its total depth and is now being lined with concrete.* *Photo courtesy of Jeff Miller.*

Roads Going In

Contractors have also poured the main road through the southern part of the subdivision. It is within feet of connecting to Woodland Hills Drive on one end. It will soon cross Taylor Gulley about in the middle of the subdivision and eventually connect to the northern half of the development.

*Looking east from Woodland Hills in front of Kingwood Park High School.*

It looks like this from the opposite direction.

*Looking southwest toward Woodland Hills from the northern side of the southern section of Woodridge. Main road in distance will soon cross Taylor Gully.* *Photo courtesy of Jeff Miller.*

In Other News

Jeff Miller says it appears that the contractor has nuked all of the trees separating the northern and souther section. Says Jeff Miller who supplied many of these pictures, “As Peter Townseand of the Who sang, ‘I can see for miles and miles.’” The song now applies to the view from Elm Grove looking north. There’s little to see but brush piles.

*Nothing but brush piles for miles and miles. Photo courtesy of Jeff Miller*

Risky Business: No More Detention Ponds Heading into Peak Hurricane Season

Contractors have not yet started excavation on any of the detention ponds for the northern section: N1, N2, or N3. That’s a risky strategy given months of ideal construction weather behind us and the peak of hurricane season fast approaching. Those Perry Homes subsidiaries are definitely connoisseurs of edge work.

*Peak of hurricane season is less than a month away. This is when things usually start to heat up.*

Posted by Bob Rehak on 8/16/2019 with thanks to Jeff Miller

717 Days since Hurricane Harvey

“Hold Your Fire! It’s Flood Control!”

Harris County Flood Control District (HCFCD) needs your help. Hold your fire. Someone is shooting up their equipment on Taylor Gully. The District is performing a clean-out of the ditch to restore its conveyance so people won’t flood again, as they did on May 7th.

Harris County Flood Control is now trying to restore the conveyance of Taylor Gully, but vandals are shooting up their equipment.

Slowing Down the Job, Raising Expenses

Sandra Musgrove, Director of HCFCD’s Infrastructure Division, reports that at night, Flood Control places metal sheets over the windows of their equipment to prevent vandalism. But now, instead of throwing rocks, vandals have taken their game to the next level. They’re SHOOTING out the windows.

Harris County Flood Control asked me to communicate that this adds to the cost of jobs and slows them down. That increases people’s flood risk. Plus it’s just not neighborly. So please help.

Lock Up Your Guns, Report Suspicious Activity

Keep your eyes and ears open for suspicious activity. Chances are, anyone you see packing on Taylor Gully late at night is hunting for heavy equipment. However, I have noticed some Texas-sized bullfrogs now and then in Taylor Gully.

Seriously. It’s a crime to discharge a firearm within the City. And if caught, something like this could ruin a young person’s life.

So lock up your guns. Hold your fire. And please report suspicious activity to 911.

Posted by Bob Rehak on 8/15/2019

716 Days since Hurricane Harvey

Harris County Commissioners Approve $700,000 Kingwood Area Drainage Study

Great news! Tuesday, Harris County Commissioners Court approved a $700,000 contract with Neel-Schaffer, Inc. for a Kingwood Area drainage study. The engineering firm will identify flooding sources in the Kingwood area and develop potential solutions.

Data shows that portions of Kingwood have potential for significant offsite flows from Montgomery County as well as ponding locations due to inadequate overland flow conveyance. Said another way, new upstream development is taxing Kingwood’s drainage infrastructure. This project will help ensure that a 100-year flood plain remains a 100-year flood plain, and doesn’t turn into a 10-, 20- or 50-year flood plain.

*Area of investigation outlined in red.*

Drainage Study Details Outlined in Contract

The contract for the work indicates its scope and details. Discussion of those begins in Appendix A on page 14. The goal of the study is to identify mitigation strategies that will return 12.4 miles of existing drainage ditches and streams within Kingwood to their originally designed 100-year service levels.

Agreement with TIRZ 10

TIRZ 10 is a Tax Increment Reinvestment Zone established in Kingwood at the time of annexation. The TIRZ provided a replacement financing mechanism for water, sewer, drainage costs for the development of residential subdivisions once the MUDs were dissolved.

Harris County Flood Control District (HCFCD) entered into an interlocal agreement with TIRZ 10 (Kingwood) to perform a drainage study of five main Kingwood streams to their confluence with the West and East Forks of the San Jacinto River. The five include:

G103-33-00 Bens Branch – From Rocky Woods Drive to WFSR (Length= 3.1 miles)
G103-33-01 – From North park Drive to the confluence with Bens Branch (Length= 1.3 miles)
G103-38-00 (Kingwood Diversion Ditch)- From Harris County Boundary to WFSR (Length = 4.0 miles)
G103-80-01 (Green Tree Ditch) – From Woodland View Dr to the EFSR (Length= 1.5 miles)
G103-80-03.1B (Taylor Gully)- From Harris County Boundary to Whiteoak Creek (Length= 2.5 miles)

Flood Control Will Fund Remainder of Streams/Ditches

In addition to the interlocal agreement, Harris County Flood Control District will also study all remaining streams and ditches within the Kingwood Area. Those include another 19.9 miles:

G103-33-00 Bens Branch – From Harris County Boundary to Rocky Woods Drive (Length = 2.2 miles)
G103-33-02 – From North park Drive to the confluence with Bens Branch (Length= 0.2 miles)
G103-33-03 – From Hidden Pines Dr. to the confluence with Bens Branch (Length= 0.1 miles)
G103-33-04 – From W Lake Houston Pkway to the confluence with Bens Branch (Length= 1.2 miles)
G103-36-00 (Bear Branch)- From Woodland Hills Dr. to WFSR (Length= 2.7 miles)
G103-36-01 – From Woods Estates Dr. to the confluence with Bear Branch (Length= 0.8 miles)
G103-36-02 – From Woodland Hills Dr. to the confluence with Bear Branch (Length = 0.9 miles)
G103-36-02.1- From Kingwood Dr. to the confluence with Bear Branch (Length= 0.4 miles)\
G103-36-03- From Royal Circle Dr. to the confluence with Bear Branch (Length= 0.4 miles)
G103-38-01- From Laurel Springs Ln. to the confluence with Kingwood Diversion Ditch (Length= 1.3 miles)
G103-38-01.1- From Red Oak Terrace Ct. to the confluence with Kingwood Diversion Ditch (Length = 0.4 miles)
G103-38-02- From Harris County Line to the confluence with Kingwood Diversion Ditch (Length= 0.7 miles)
G103-39-00- From Palmetto Ln. to the WFSR (Length= 1.3 miles)
G103-41-00 (Sand Branch) – From Sycamore Creek Dr. to the WFSR (Length= 2.0 miles)
G103-41-01- From Elk Creek Dr. to the confluence with Sand Branch (Length= 0.8 miles)
G103-45-00- From Trail Tree Ln. to the WFSR (Length= 0.4 miles)
G103-46-00- From Forest Cove Dr. to the WFSR (Length = 1.0 miles)
G103-46-01- From Sweet Gum Ln. to the confluence with G103-46-00 (Length= 0.7 miles)
G103-80-01.1- From Autumn Sage Ln. to the confluence with Green Tree Ditch (Length= 0.3 miles)
G103-80-03.1A (Mills Branch) – From Same Way to Whiteoak Creek (Length = 1.5 miles)
G103-80-04 (Blackland Gully) – From Maple Knob Ct. to the EFSR (Length = 0.6 miles)

For a map showing the location of these numbered ditches/streams, click here.

Stakeholder Meetings Part of Plan

The scope of work includes several stakeholder meetings with TIRZ 10, homeowner associations, and the community at large. Their purpose: to increase public awareness and understanding of the magnitude of the watershed problems, their complexities and the cost of solutions.

Drainage Study Data Acquisition Phase

The contractor will start by collecting all available information and data including:

Construction plans
Previous drainage studies
HCFCD historical flooding data
High Water Marks
Watershed Masterplan data
FEMA Repetitive Loss properties
Flooding reports
LiDAR DEM data
Aerial maps
HCFCD watershed maps
Hydrologic and hydraulic models
City of Houston GIMS data
Any other pertinent technical data in the development of this scope of services.

Field Reconnaissance Phase

Neel-Schaffer engineers will then conduct field reconnaissance of the existing drainage systems, outfalls, and drainage patterns within the project area. That will include field measurements of 27 bridge crossings, 32 culvert crossings, 16 pedestrian bridge crossings and 6 drop structures to be incorporated in the development of hydraulic models.

During this stage, Neel-Schaffer will also measure high water marks; update floodplains; and analyze stream performance and capacity to illustrate flooding issues to the County, TIRZ and community.

Identification of Structural and Non-Structural Mitigation Alternatives

The Engineer will determine structural and non-structural improvement alternatives to bring all streams back up to the 100-year level-of-service.

Neel-Schaffer will perform this analysis using full conveyance at peak flows. Engineers will identify the major constraints that affect the available solutions for each stream.

They will then consider both structural and non-structural alternatives for mitigation.

Structural Alternatives

Structural alternatives include:

Improved drainage channels including widening, deepening, and/or lining for increased conveyance capacity.
Watershed diversions using enclosed conduits (following existing roadway alignments or other public ROW).
New regional or sub-regional detention basins and modification of existing detention basins including inlet and/or outlet structures.
Enhanced conveyance using selectective clearing and re-shaping of natural channels.
Enhanced flood storage in natural and park areas using small-scale berms and grading.

Non-Structural Alternatives

Non-Structural Alternatives include:

Property buy-outs.
Coordinated ROW dedications for future improved channels and regional detention basins.
Regional detention fees for new development.

Drainage Study Will Consider Detention Ponds

This contract includes identifying detention needs, identifying potential locations, and developing schematic layouts of the detention ponds. It also includes:

Proposed Right of Way acquisition
Preliminary Cost Estimates
A project priority and implementation plan

It is not clear at this point how long this project will take.

This post is dedicated to Barbara Hillburn, the president of the Kingwood Lakes HOA, who fought long and hard to get a project like this started. Thank you, Barbara!

Posted by Bob Rehak on 8/14/2019 with thanks to Barbara Hillburn and Precinct 4 Commissioner Jack Cagle

715 Days since Hurricane Harvey

Army Corps Now 70% Complete with Its Portion of Mouth Bar Dredging

The Army Corps has released a new summary of its progress on dredging the mouth bar. The report indicates that Great Lakes, the contractor is now 70% complete. They have dredged 350,000 out of 500,000 cubic yards.

Great Lakes started dredging the mouth bar on June 25th, 2019, as part of a $17,085,861 extension of the original contract (FEMA mission assignment SWD-30).

Current area of operation is the blue area on the far right. Sediment removed from that area is being pumped 10 miles back upstream to Placement Area #2, a sand mine near Kingwood College, on the far left.

Between the start of mouth bar dredging and August 12, Great Lakes dredged an average of 6,363 cubic yards per day. If they can keep that pace up, they should be done by approximately Labor Day – three months ahead of schedule. That’s HALF the predicted time.

Remainder of Project Still Not Decided

What comes next? That still has not been finalized. City, County and State officials have been meeting in the background to determine that. The Army Corps still has not accepted or rejected Berry Madden’s property as a third placement area. And the $30 million appropriated by the State for mouth bar dredging won’t even become available until September 1st.

Meanwhile, Callan Marine, the subcontractor from the original West Fork Emergency Dredging job has pulled its equipment back to the dock opposite Forest Cove. However, Callan has not yet started disassembling its equipment and removing it from the river. According to Houston City Councilman Dave Martin, Callan has agreed to stay temporarily while officials attempt to work out details for the next phase of dredging.

RD Kissling and Tim Garfield, two local geologists who first brought the mouth bar issue to the public’s attention, estimate that 500,000 cubic yards is about one-fourth of the total sediment that must be removed to fully restore conveyance of the West Fork.

How Shallow is It?

The Corps has not yet released (or even developed) plans for mouth bar dredging. We do know the volume they intend to remove, and the general area they intend to remove it from. However, they have refused to divulge how much of a dent their efforts will make in solving the problem.

*This photo of a Kings River resident wading across the river shows how shallow it is near the orange channel marker.* *This resident says boats “beach” behind his property almost every day.* *Note: Deeper pockets may exist, especially near dredging equipment. The risk of drowning is real. Do not let children attempt this.* *Photo taken Sunday, August 10, 2019.*

*The resident made it almost to the channel marker without getting his shorts wet.* *Shot taken with 6X telephoto lens.*

*The lake/river within this area averages two to three feet deep. 500,000 cubic yards would lower the average level by another three feet as this calculation shows.*

Problem With Stopping after 500,000 CY

The problem with stopping after the Corps finishes its 500,000 cubic yards is that the river behind this area is much deeper. Where the Corps stopped dredging just past Kings Harbor, the river is now 25-30 feet deep. And places are even deeper according to fishermen. That means water coming downriver will be forced to flow uphill in this area. That will force it to slow down and more sediment will rapidly drop out of suspension. Some experts have suggested dredging a deep channel through this area to help restore full conveyance of the river. However, the Army Corps intends to stop after 500,000 cubic yards.

How Army Corps Sees its Role

The Army Corps has prepared a series of FAQs that represent its position on the remainder of mouth bar dredging. Among them:

“Q: What is USACE Galveston District’s plan for the rest of the mouth bar?“

“A. There is no additional work planned for the mouth bar. The current plan for the modification addressing material near the mouth bar can be found on the placemat. USACE Galveston District has no authority to conduct any additional work in the West Fork of the San Jacinto River or Lake Houston. The San Jacinto River is not an authorized federal waterway, the Corps of Engineers dredging operations are currently limited to dredging Harvey-related material. The ongoing work under the contract modification will remove the remainder of material attributable directly to Hurricane Harvey. The sedimentation from recurring annual flows are not within USACE Galveston District’s mission assignment from FEMA. Water flows on the West Fork of San Jacinto River were restored to pre-Harvey levels in December 2018.”

“Q: Who can the public contact for additional concerns with the maintenance of the San Jacinto River?“

“A. For concerns with the maintenance of the San Jacinto River, please contact Harris County Flood Control District, the San Jacinto River Authority and the City of Houston.”

Punt!

Meanwhile the City is still arguing with the Corps about how they arrived at 500,000 cubic yards. More on that later. I have obtained the Corps’ estimate through a FOIA request to the City of Houston. It raises many questions that I am still trying to sort through. More on that later.

Posted by Bob Rehak on August 14, 2019

715 Days since Hurricane Harvey

How This Hurricane Season Compares to Others So Far

With two weeks left in August and no active tropical systems in the Atlantic, Caribbean or Gulf, I started wondering how this hurricane season stacked up against the average. Through the end of July, we had two named storms in the Atlantic. We also had six in the eastern Pacific, none of which threatened land. That makes a total of eight. How does that compare to a normal year? Below is a chart from NOAA. It shows the averages for tropical storms and hurricanes by month.

167 Years of Hurricane History

The first thing I noticed when looking at this table is the clear jump between July and August. Through the end of July, the averages for both tropical storms and hurricanes are below 1. That means the chances of NOT seeing one are greater than seeing one. However, August is where things heat up (pardon the pun). Your chances of seeing one are far greater than NOT seeing one.

Distribution of Atlantic Storms by Month

Through the end of July, we exceeded the averages for The Atlantic and Pacific combined. But if you look at just the Atlantic, we are about on average, as the chart below shows.

*Cumulative Number of Storms Per 100 Years in The Atlantic Basin.* *Source: NOAA*

The official hurricane season for the Atlantic Basin (the Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico) is from 1 June to 30 November. As seen in the graph above, the peak of the season is from mid-August (now) to late October.

Current Outlook Clear

However, THIS August has been quiet so far. Season-to-date, we are still slightly above average, but the month of August is unusually quiet. We’re halfway through the month without any named storms in the Atlantic and NOAA expects no activity for the next five days.

*Source: NOAA*. *As of 8/14/19 at 8am EDT.*

Regardless, if you are the type to play the odds, so far this year Texans have to consider themselves lucky.

Lake Levels As of Mid-August

With that in mind, let’s look at what the San Jacinto River Authority (SJRA) and Coastal Water Authority are doing with Lake Conroe and Lake Houston to reduce the chance of flooding in the event of a major storm.

Both lakes are down about a foot. This creates an extra buffer against flooding by creating extra capacity within the lake.

The SJRA began lowering Lake Conroe on August 1. Normal level is 201 feet above sea level. As of this morning, Lake Conroe was at 200.03 feet and the SJRA continued to release water at a minuscule rate of 150 cubic feet per second. Evaporation is doing most of the work. The SJRA says the lake can lose up to an inch per day through evaporation in hot, dry weather, which we have had plenty of lately. You can always check the current lake level at SJRA.net.

The Coastal Water Authority is maintaining Lake Houston at 41.57 feet above sea level. Normal level is 42.38 feet. A recent lowering for dam maintenance combined with lack of recent rain and evaporation have all contributed to the current level.

The SJRA will continue releasing water at a rate that brings Lake Conroe down to 199 feet by September 1. The SJRA will maintain that level through the end of September, then allow the lake to gradually refill with rainwater until it reaches the normal level of 201 feet.

Pre-emptive seasonal lowering helped avoid flooding last spring. Keep your fingers crossed!

Posted by Bob Rehak on 8/14/2019

715 Days since Hurricane Harvey

Respect the Rivers

Jill Boullion, Executive Director of the Bayou Land Conservancy, sent me a link to a fascinating article called Fossil Rivers. It’s about the evolution of the Mississippi River. Even if you’re not a student of geology, the maps are worth looking at as pieces of abstract art. As the author of the article, Geoff Manaugh says, “Colors coil round other colors; abstract shapes knot, circle, and extend like Christmas gift ribbons. This is geology as a subset of Abstract Expressionism: rocky loops of the Earth’s surface in the hands of Jackson Pollock.”

*Army Corps map showing the geomorphology of the Lower Mississippi over time.*

Says Manaugh, “Indeed, what the Army Corps of Engineers discovered while producing these maps is that the Mississippi River has changed channel completely – and it has done this hundreds, even thousands, of times. In fact, the river’s endless self-alteration still occurs, even as you read these words: the Mississippi, like all rivers, is migratory, destined to wander across the landscape for as long as it continues to flow. It drifts back and forth – sometimes a few feet, sometimes a mile – walled in by its own silt and debris; until there is change: a natural levee fails, or a storm surge bursts into another watercourse nearby, and then the river finds itself on a quick new route to the sea.”

Powerful reminders to respect the rivers! Give them room. Those who build too close will lose in the long run. People can moan about property rights all they want. But in the end, Mother Nature always wins.

Posted by Bob Rehak on 8/13/2019

714 Days since Hurricane Harvey

Meet Bill King, Candidate for Mayor of Houston, At Los Cucos Tuesday at 6PM

Bill King, Candidate for Mayor of Houston, will visit Kingwood tomorrow to answer residents’ questions about how he would address flooding and other issues. King will offer a sneak peak of his flood plan that will be released next Monday or Tuesday.

Los Cucos
23730 Highway 59 North
Kingwood, TX 77339
Tuesday, August 13, 6PM

RSVP HERE FOR BILL KING EVENT

*King (left) with Elm Grove resident Abel Vera after the May 7th flood.*

Flood mitigation solutions by their very nature are political. I will be posting similar announcements for other candidates as events arise. My hope is that everyone in Houston can meet the candidates personally, get to know them, and learn about their ideas to reduce flooding. A massive turnout in November will help secure our future.

Posted by Bob Rehak on 8/13/2019

713 Days since Hurricane Harvey