Why “Improving Conveyance” Doesn’t Work
It Causes More Flooding
Taming the Mighty Mississippi May Have Caused Bigger Floods
Human meddling with the river is blamed for most of the rise in flood levels, but the role of climate remains unclear
Now a new study raises the possibility much of the effort humans have put into trying to control the mighty river has paradoxically made its large floods more destructive. The magnitude of so-called 100-year floods—massive inundations defined as having a 1 percent chance of occurring in any given year—has increased 20 percent in the past five centuries on the lower Mississippi, researchers reported this month in Nature. The bulk of the increase has been in the last 150 years, when human engineering of the river has been most intense. “We’ve channelized the river, we’ve straightened it,” says Samuel Muñoz, lead author of the new study and an assistant professor of marine and environmental sciences at Northeastern University. “We’ve made the gradient steeper, and we’ve encased the river in concrete mats and lined it with levees.”
The resulting physics is straightforward, Muñoz explains. With little leeway to meander and limited floodplain to spread over, the waters of the Mississippi in places are corralled into a relatively narrow chute, making peak flows higher than they would be otherwise. Muñoz and his colleagues estimate about 75 percent of the increase in 100-year-flood magnitude is due to river engineering, with the rest attributable to natural climate cycles. The study was not able to factor in the influence of anthropogenic climate change effects, though, leaving open the question of how much rising flood levels are driven by engineering and how much by a warming climate.
Read the rest of this article in Scientific American.
Lessons From Hurricane Harvey
Academic Experts Speak on What Can and Should Be Done About Flooding In Houston
March 30, 2018
Daniel Grossman reports for Re.Think on the annual American Geophysical Union meeting in New Orleans in December 2017. He also visits Houston and gathers opinions from local academics. Buyouts, making room for the river, stopping storm runoff before it floods our streams are some of the necessary strategies recommended here and elsewhere by those who study these things.
Heavier, More Frequent Rains
At the New Orleans conference, Emanuel laid out findings he’d published a few weeks earlier in the scientific journal Proceedings of the National Academy of Sciences. Simulating mayhem in a computer program, he’d released thousands of virtual past and future “seed” storms into the Atlantic Ocean and computed their tracks. The likelihood of a storm about as rainy as Harvey has increased by a factor of six in the last 40 years, he’d found. By 2100 the chance of such a deluge will increase another threefold. Then, a Hurricane Harvey will strike Texas once every 5 years.
Buyouts and Room for the River on Buffalo and Other Bayous
Yoonjeong Lee, a researcher at the Center for Texas Beaches and Shores at Texas A&M University at Galveston, says Houston should build Dutch-style flood protection, and she knows where. “Buffalo Bayou would be a perfect place to build a ‘Room for the River’ program.” She says the city could buy up a relatively small number of plots near its banks and – after demolishing any structures on them – construct a riverfront park. The land would be engineered to capture water when the bayou rose, safeguarding remaining districts. Houston has previously installed patches of parkland along its bayous before, but she says the city has to think bigger.
Timon McPhearson, a professor in Urban Ecology at the New School in New York City, says that another way Houston should become more resilient to wetter storms is by controlling how much water rushes into bayous in the first place. He says too much of the rain that lands on the city drains quickly into waterways. “Houston is an extremely paved city,” he says. Replacing street and driveway surfaces with permeable materials will lower peak floods. He also suggests green roofs, covered with vegetation that could provide important ecosystem services that retain – and stall – some of the rainwater.
Albert Pope, an architect at Rice University, doubts that adaptation through infrastructure fixes are sufficient to keep Houston safe from serious flood damage. He says that there’s too little undeveloped land left to accommodate new reservoirs of sufficient capacity, and that further straightening, widening, and bank-hardening can’t force bayous to carry more water. “We’re at the limits to what we can do, engineering-wise,” he says. His solution is more disruptive of the status quo, and Houston’s fix-it-with-concrete ethos. He insists that Houston should do something more transformative and remove all the buildings in its flood plains – 150,000 structures, including those on three-quarters of the acreage in Meyerland – and turn the acquired land into parks.
Read the article, “Lessons From Hurricane Harvey,” published by Re.Think on March 15, 2018.
High Flows in Harris County Streams Increasing Most in Texas
Study Questions Use of Dams and Urges Focus on Causes, Not Symptoms, of Flooding
County Commissioners to Discuss Flood Strategy, Funding, Tuesday, March 27, 10 a.m.
March 26, 2018
An “incredible” 70 percent of stream gauges in Harris County show significant increases in peak flow – as much as 6,400 percent in one case — since the beginning of record keeping by the US Geological Survey.
More streams in Harris County are increasingly flowing higher than in any other part of the state, according to a study recently published in the March 2018 issue of the Texas Water Journal, a publication of the Texas Water Resources Institute.
Three stream gauges on Buffalo Bayou have shown the greatest increase in peak flows since the federal dams were built in the 1940s to reduce flooding on the bayou, according to the report.
Significantly, two major streams, Langham and Bear creeks, feeding into one of these dams — the overburdened Addicks Reservoir — showed some of the largest upward trends in peak flow. The record amount of runoff flowing into Addicks during Hurricane Harvey was a major factor in the unprecedented decision to open the floodgates on both dams during the storm in order to prevent the dams from overtopping. Thousands of homes both below and behind the dams were flooded, and three people died.
The area in western Harris County above and behind Addicks Reservoir is experiencing some of the greatest development pressure in the region, particularly since the construction of the Grand Parkway (Highway 99). Buildings, paved surface, and other hard structures, including pipes, associated with development cause more and faster and more polluted rain runoff into streams, leading to flooding.
“An Overreliance on Flood Storage Reservoirs”
The report noted “the difficulty of maintaining lower peak flows below a reservoir when the inflows to the reservoir exhibit extraordinary increases year over year.”
“It is much easier for impoundments to store flood flows when these flows are not rapidly increasing on an annual basis. Thus, relying on large impoundment projects alone likely will not achieve success and again points back to our central emphasis of identifying causes, not just symptoms [of flooding].”
The study, titled “Peak Flow Trends Highlight Emerging Urban Flooding Hotspots in Texas,” was authored by Matthew D. Berg, CEO and Principal Scientist, Simfero Consultants, in Houston.
The USGS gauge on Greens Bayou at Cutten Road in northwest Harris County experienced the greatest increase in peak flow – 6,400 percent over a period of several decades.
Other rapidly increasing stream flows are occurring in Keegans Bayou at Roark Road in southwest Houston (nearly 5,000 percent), Greens Bayou near Highway 45 in north Houston (1,200 percent), Langham Creek near Addicks Reservoir in west Houston (750 percent), and White Oak Bayou near Heights Boulevard (600 percent).
Harris County Commissioners Court will meet Tuesday, March 27, to discuss flood management strategies and a possible bond referendum to pay for them. Also on the agenda is a proposal to study the feasibility of digging massive tunnels to drain stormwater from western Harris County into Galveston Bay. The contract to be negotiated is with Fugro USA Land, Inc.
The commissioners’ meeting begins at 10 a.m. on the ninth floor of 1001 Preston in downtown Houston. Those who wish to speak can sign up before the meeting here.
Rain Watchers Needed
Be A Backyard Rain Counter. Help Science
March 19, 2018
Message from the Community Collaborative Rain, Hail, and Snow Network:
The Community Collaborative Rain, Hail & Snow Network (CoCoRaHS) is a grassroots, non-profit, community-based, high-density precipitation database network made up of volunteers who take measurements of precipitation right in their own backyards. CoCoRaHS has observers in all 50 states nationwide, the Commonwealth of Puerto Rico, the U. S. Virgin Islands, the family islands of the Bahamas, and in Canada.
Texas CoCoRaHS needs volunteers who have an interest in weather observing and who would enjoy observing and reporting daily precipitation amounts on our website. Volunteers are asked to obtain an official CoCoRaHS scientific rain gauge and place it in a strategic location. They take daily precipitation measurements at approximately the same time – usually 7 a.m. – and record those measurements. Daily reporting of data is preferred, as days without precipitation are just as important to know as days with rainfall.
Many agencies rely on precipitation data collected by CoCoRaHS during and after rainfall and flood events to determine where the most rain has fallen and where the potential for flooding is greatest. CoCoRaHS’s volunteer precipitation reports help to fill in the gaps between official rainfall data collection sites in our region, such as the Harris County Flood Control District’s Flood Warning System, the National Weather Service’s climate sites, and the Lower Colorado River Authority’s Hydromet system.
The data reported by volunteers is organized and displayed on the CoCoRaHS website for use by scientists, researchers, and emergency managers – as well as the general public. The Harris County Flood Control District, National Weather Service, U.S. Department of Agriculture, and West Gulf River Forecast Center utilize CoCoRaHS data in their work, along with engineers, meteorologists, hydrologists, climatologists, insurance adjusters, ranchers and farmers, and many more.
The Houston/Galveston region of the CoCoRaHS Network consists of volunteers in 15 counties: Austin, Brazoria, Chambers, Colorado, Fort Bend, Galveston, Harris, Jackson, Liberty, Matagorda, Montgomery, Polk, San Jacinto, Waller, and Wharton counties. The network needs many more volunteers to better measure precipitation across the region. Weather hobbyists and those citizens who measure daily rainfall totals such as Master Gardeners and Master Naturalists are strongly encouraged to join CoCoRaHS.
To join, go to the CoCoRaHS website and click on the “Join CoCoRaHS” emblem in the upper right corner of the homepage. The website also has information on the organization’s background, observer training and educational tools, where to purchase the required CoCoRaHS rain gauge, how and where to set up the gauge on your property, and much more.
Please take a moment to tell a friend or neighbor about this exciting grassroots effort of citizens measuring precipitation right in their own backyards. It’s easy to join, takes only five minutes a day, and is a fun way to learn about this wonderful natural resource that falls from the sky. Your observations continue to give scientists an ever clearer picture of where and how much precipitation falls throughout our communities.
Make sure to read our newsletter.
High Bank on Bayou Damaged by Bike Riders
Fools Dug Up Vegetation and Drove Boards Into Top of Bluff
But Boy Scouts Do More Good Deeds, Plant Vegetation
March 7, 2018
Riding a bike along the edge of a cliff above a river is bad enough. Even walking on top of a high bank can be damaging. But the high banks of Buffalo Bayou in Houston’s Memorial Park are already stressed and attempting to recover from the overbank flooding that came with Harvey last summer. Large sections of the bank slid away, taking down trees and vegetation. With time, however, the vegetation will grow back, the downed trees will collect sediment, and the banks will rebuild.
Now that recovery will be much more difficult. In the past weeks, off-road cyclists built a bike jump and wooden ramp right at the very edge of the bank near the main tributary draining the center of the park. This is very near the Bend in the River that Save Buffalo Bayou and photographer Jim Olive have been documenting through the seasons for the past four years.
The culprits apparently removed vegetation, dug holes, and drove large boards into ground. And then, of course, they’ve been pounding the edge of the bank with their bikes. They also dug up dirt to mound it into a jump further down the bank.
Representatives of the Greater Houston Off-Road Biking Association (GHORBA) condemned the construction.
“We would never approve this type of activity,” said C.J. Bernard, trails director for the biking association, in an email. “For anything we do at GHORBA related to trail development and maintenance, we follow the IMBA Sustainable Trails guidelines which highly emphasizes ways to identify potential erosion concerns and provides ways to eliminate and/or minimize.” (IMBA is the International Mountain Bicycling Association.)
“Most likely it is from a mountain biker that isn’t associated with GHORBA, as our trail stewards must approve features before they are built and this one, to my knowledge, was not,” wrote Christy Jones, president of GHORBA, in an email.
The dirt paths through the woods along Buffalo Bayou south of the Picnic Loop in Memorial Park are unofficial trails. However, they are much used by walkers and runners. Other trails in the park are officially open to bike riders as well as others. The neighboring Arboretum, however, does not allow bikers on its paths.
A representative of the Memorial Park Conservancy said the structure would be removed. “We are very grateful that you alerted us to this and will assess and remove the structure ASAP,” wrote Cara Rudelson, chief operating officer of the Memorial Park Conservancy, the private nonprofit organization running the public park. “We always have our eyes out for unauthorized use of the unofficial trails!”
Boy Scouts Plant Riparian Rebar on Bank of Buffalo Bayou
In the meantime, some more positive news: members of Boy Scout Troop 55 are doing good deeds again. This time, under the leadership of Boy Scout Austen Furse, who developed the plan for his Eagle Scout project, they planted 200 buckets of native eastern gamagrass on the upper banks of the ugly stormwater outfall, formerly a nature trail, also known as the Woodway Boat Launch, in the Old Archery Range of Memorial Park west of Loop 610. This happened Saturday morning, March 3.
Eastern gamagrass is an herbaceous stabilizer plant, described as “riparian rebar” and a “big, green leafy cousin of corn.” Though slow to establish, once established, eastern gamagrass can grow to six feet or more and has “extremely good root stability,” according to Your Remarkable Riparian, a field guide to riparian plants found in Texas.
Take note, property owners contemplating ugly and damaging concrete riprap for bayou banks.
Let’s hope the young gamagrass doesn’t get mowed down.
Austen is planning to photograph the site every week or two to document the results, says his mother, Anne Furse.
Wild violets and chives and weird mushrooms
Must Be Spring on Buffalo Bayou
Feb. 28, 2018
Went for a walk with a visiting friend on the bayou in Buffalo Bayou Park recently. Aside from the barren ruin of the landscaping from the Harvey flooding, it’s jarring to have summertime weather with empty, leafless trees and vegetation. But there in the bank along the walkway some tiny violets had sprung out of the sand. And if there were violets, there were going to be wild chives. And there were! Growing everywhere. Couldn’t help grazing and munching on the tender little onions.
Later on a stroll through the Old Archery Range — that part of Memorial Park just west of Loop 610 at Woodway — we saw what at first looked like fields of orange flowers poking up through the leaves. Upon closer inspection the flowers turned out to be mushrooms, odd column-like things poking out of an egg-like sac.
There are some delicious mushrooms growing in Memorial Park and along Buffalo Bayou, including the armillaria tabescens (or ringless honey mushroom) and the beautiful white oyster mushroom. But this wasn’t one of them. The strange fungus was definitely not edible. Our nature advisors Tom Helm and Bruce Bodson identified it as an octopus stinkhorn or “devil’s fingers.” Definitely not edible. And definitely did not smell edible. Especially after sitting forgotten in a plastic bag in a purse for a few days.
Shocker: Save Buffalo Bayou and Corps of Engineers Agree About Something
Big Goal: Managing Raindrops Where They Fall
Feb. 20, 2018
In order to fix our very bad flooding problems, we need to understand what they are.
A wide-ranging study, proposed by the US Army Corps of Engineers, would look at where raindrops fall and how they flow across our roofs, yards, parking lots and streets, through our drainage systems and waterways and into Galveston Bay. It would analyze where the problems are and help us agree on the best solutions.
The cooperative project, first proposed to the city and county in 2015, now appears to be moving forward.
Edmond Russo, deputy district engineer for the Galveston District of the Corps of Engineers, reports that federal funding for the Metropolitan Houston Regional Watershed Assessment is in place. The district expects to receive word from headquarters in Washington, D.C. within several weeks.
The Feb. 9 passage of the federal budget also provided funds for the long-awaited study of improvements to the troubled Addicks and Barker dam and reservoir system on Buffalo Bayou in west Houston. Engineers were forced to open the floodgates of the aging, earthen dams in August when an unprecedented amount of rain runoff from Harvey threatened to overwhelm the dams. Three people died and thousands of homes and businesses were flooded.
Russo says the two studies would complement each other.
What’s To Like
The study has the potential to move the Houston region’s outdated flood management practices into the modern era. Flooding begins on the land. The focus of flood risk reduction elsewhere – including even Fort Worth – is on managing flooding in place, stopping stormwaters before they flood rivers and streams. That means slowing the flow. It means educating people about rain runoff and helping them be stewards of their own watershed. It means swales and rain gardens instead of lawns, more trees, vegetation, and green spaces instead of impervious surface, opening up ravines and streams filled for development, buying out properties and widening the floodplains of our streams, and more.
Houston and Harris County leaders continue to emphasize bigger drainage pipes and channelizing, widening, and deepening our bayous and streams to “improve” conveyance and flush more water downstream as fast as possible. Scientific experts widely agree that this approach, costly to the taxpayers as well as the environment, causes more flooding and erosion.
Russo, in a recent telephone interview, spoke passionately about a “comprehensive approach,” a “range of ideas,” “a suite of solutions” and “actions at various levels,” including cisterns, porous concrete, green buildings, the possibility of redesigning golf courses on Buffalo Bayou for detention, water features for detaining floodwaters, “managing all this water as far upstream as we can … before it gets to the bayous.” He pointed out that “a tiny bit of improvement across the whole drainage network could equal another reservoir.” He spoke of bringing together different planning bodies, community groups, the city and county flood control, bayou coalitions, landscape architects, hydrologists, and engineers, of using Housing and Urban Development grants and other federal funds as well as tax breaks for green infrastructure and assistance to homeowners and others to make changes to their homes and property.
Buffalo Bayou is the main river flowing through the city of Houston, the center of some 22 interconnected watershed systems, most of which drain into it. The bayou itself is part of the larger San Jacinto River watershed.
The Harris County Flood Control District has signed a Letter of Intent to be the non-federal partner in the project, sharing twenty-five percent of the cost.
The goal is to have “everybody singing off the same sheet of music,” said Russo.
“If we don’t do this, all the problems we have are only going to get worse.”
Personnel and Policies Change
The Corps of Engineers is not widely admired, particularly here after the disaster caused by the unprecedented opening of the floodgates of the federal dams on Buffalo Bayou during Harvey. The Corps has a reputation for ruining rivers, arrogantly ignoring natural systems, destroying the environment, and building projects that fail. “The Corps is going to come up with engineering solutions,” commented a skeptical acquaintance working on flooding issues. Harris County Commissioner Steve Radack, whose Precinct 3 includes the dams, complained in a recent interview of the impact of a decade of foreign wars on the ability of the Corps to address domestic issues.
Living in a Special Flood Hazard Area
Public Comment through March 5 on proposed changes to City floodplain regulations
And the Flood Czar’s Committee makes a Final Report
Feb. 19, 2018
The public has until March 5 to comment on proposed changes to Chapter 19, the section of the city code that regulates building in floodplains defined by the Federal Emergency Management Agency. These are the so-called 100-year and 500-year flood hazard areas that few people seem to understand, including members of the Houston City Council who met last Monday to hear about the proposed changes.
Actually there was a lot city council members didn’t seem to understand, including who was on the Flood Czar’s Drainage and Redevelopment Committee, how long they had been meeting, and what they were talking about. The Flood Czar himself, Steve Costello, officially known as the Chief Resilience Officer, addressed members of the Transportation, Technology, and Infrastructure committee and the Regulation and Neighborhood Affairs committee. Remarkably, Costello appears untarnished by the Houston Chronicle report that he and his engineering company helped develop plans for subdivisions behind the reservoir of Barker dam that they had to know would flood.
The city’s director of Public Works and Engineering also addressed the council members and made a presentation about the proposed changes. Carol Ellinger Haddock was appointed as director last month after serving as acting director since July 2017. The previous director had served about two months. Other administrative positions remain unfilled.
City council members angrily objected to the brief period for public comment on the changes proposed by Haddock. The draft changes already had been reviewed for comment by developers and builders. The public comment period, initially set to end on Feb. 19, has been extended to March 5.
SBB On the Radio
Understanding Flooding and Our Bayous
Hot News: Save Buffalo Bayou and Corps of Engineers Agree About Something
Feb. 6, 2018
Save Buffalo Bayou was on KPFT’s Open Journal on Monday evening. We had a lively discussion with hosts Duane Bradley and Sherri McGinty, who asked a lot of good questions about what Save Buffalo Bayou is doing now and how we are working to focus flood mitigation efforts on stopping stormwater before it enters our streams. Flooding begins on the land. Digging up and widening our bayous is outdated, costly, and only causes more flooding. Amazing development: Save Buffalo Bayou supports a Corps of Engineers project to study our regional Houston watershed, beginning with where raindrops fall and how we can slow them down to reduce our flooding. The faster the runoff from our homes, businesses, streets, parking lots and sidewalks, the higher peak flow in our natural drainage systems. Slow the flow. Citizens need to support this and contact their representatives. The project needs funding and the Corps by law cannot lobby. So who’s going to lobby?
Buyouts: Best Practices for the Best Flood Response
Experts Gather in Houston for Public Discussion, Tuesday, Feb. 6
Feb. 5, 2018
Interested in how buying out hopelessly flood-prone buildings can help with our flooding problem?
Experts on this issue from across the country will be gathering in Houston tomorrow, Tuesday, Feb. 6, for a public discussion titled “Buyout Best Practices in the Wake of Harvey.”
The free public program is sponsored by the Greater Houston Flood Mitigation Consortium. The conference is scheduled for 7 to 9 p.m. at the BioScience Research Collaborative, 6500 Main Street in Houston. Though free, registration is required. Register here.
According to a statement from the nonprofit Consortium, “there is a broader opportunity for buyouts to be a part of a comprehensive multi-purpose strategy for assuring more resilient and livable neighborhoods, through coordination with flood control infrastructure, parks, and housing.”
The discussion topics will include:
- How to work with (and around) federal requirements
- How to coordinate with different agencies
- How to utilize buyouts as part of an overall neighborhood strategy
- How to address housing issues
- How to build community support
Experts on the panel are:
- Dave Canaan, Mecklenburg County
- Tom Chapman, Milwaukee Metropolitan Sewerage District
- Molly O’Toole, PE, Molly O’Toole & Associates, LTD.
- Gavin Smith, UNC-Chapel Hill
- Rachel Wider, New York State Homes and Community Renewal