Chadwick: Practices to reduce flooding risk are out of line with our region's needs

Houstonians last week once again found themselves facing flooded homes and cars, closed schools, roads and transport. No doubt they were asking, "Why does this keep happening?"

Maybe it's because our political leaders are prioritizing the wrong solutions and are treating the symptoms instead of the problem. Widening and deepening bayous, a top priority for city and county officials, is an ineffective, environmentally damaging and unnecessarily costly approach to reducing flooding.

Yet widening and deepening bayous is the stated policy and practice of the Harris County Flood Control District and a recommendation of Mayor Sylvester Turner's 2016 Transition Report on ReBuild Houston, a report largely written by engineers. The practice also is embraced by conventional wisdom. Widening bayou channels was one of a number of responses to the region's flooding problems listed in a recent Chronicle article, "How to Fix the Houston Floods," by Dylan Baddour (HoustonChronicle.com, Dec. 31), as well as in a commentary by former mayoral candidate Bill King ("Homeowners puzzled by increase in floods" Page A13, Jan. 13).

Here's why widening and deepening our bayous and streams are the wrong approach:

Widening channels is like building bigger highways. "It's a never ending process," points out Sam Brody, director of the Center for Texas Beaches and Shores in the Department of Marine Sciences at Texas A&M University, Galveston. "We can solve the problem or treat the symptoms," says Brody. Widening bayous is just treating the symptoms, which will only get worse. "They've been widening the Gulf Freeway since I've been alive. The same is true for bayous."

Widening destroys the riparian wetlands. The trees, vegetation and soil structure along the banks of bayous are so vital for slowing storm waters and runoff, cleansing our urban water and stopping erosion of the banks. Water flowing through our bayous during and after storms is primarily polluted rainwater running off our paved and built city and ending up in Galveston Bay. Studies have shown that the specially adapted vegetation on riverbanks cleanses the water more effectively than expensive sewer treatment plants. And trees are powerful stormwater detention devices. Sadly, the flood control district's counterproductive practice is to cut down trees, violating its legal mandate to conserve forests.

The days of widening and deepening are over. So says Phil Bedient, Herman Brown Professor of Engineering at Rice University and director of the Center for Severe Storm Prediction, Education and Evacuation from Disasters (SSPEED). Federal priorities have changed, emphasizing sustainability, the wise use of floodplains, and protecting and restoring natural systems, among other things. Bedient supports the ongoing $480 million federal-county project to widen Brays Bayou in order to reduce flooding in Meyerland, a "sitting duck," he says. But there aren't going to be any more of these big, expensive federal projects, he says.

Widening leads to channel instability, requiring continuing costly maintenance. "Wider channels do not maintain themselves, as the river cannot maintain such an artificially expanded width, and sediment deposits within the channel," says Mathias Kondolf, professor of environmental planning at the University of California at Berkeley, one of the world's leading river experts. "This then requires expensive dredging and an endless cycle of 'serial engineering' - in which each engineering intervention produces a reaction, which prompts another engineering intervention, and so on." Not to mention banks collapsing. Great for engineers. Not so great for taxpayers.

So what are the correct responses? How do we treat the problem instead of the symptoms?

The Chronicle's excellent December article listed some of the answers, among them building more detention facilities, as well as developing a program of government-sponsored buyouts of properties in 100-year-flood zones.

King's commentary also urged the need for a regional, long-range plan to address flooding. Indeed, it's far past time to set up a regional commission to investigate and recommend intelligent solutions to flooding.

But it may be surprising to learn that one answer is not putting in bigger and bigger drainage pipes, culverts and storm sewers, or other costly engineering solutions similar to widening bayous that have been proposed by city and county engineers. Those traditional but outmoded solutions only make flooding worse by collecting and concentrating more stormwater faster, as pointed out by many experts, including the authors of the important book, "Floodplain Management, A New Approach for a New Era."

The rest of the world, and much of the rest of the country, has moved on to better practices in reducing flood risk, recognizing that slowing down, spreading out and soaking up storm waters before they enter our streams is the solution, along with getting out of the way - in other words, stop building in areas that flood or where impervious cover will worsen downstream flooding. Bedient and Brody's suggestions, in line with current thinking around the world, include:

Better land use and development policies; more green space; protection and restoration of wetlands; buyouts of flood-prone property; better drainage policies; better education about flooding; regional and local stormwater detention, including, says Bedient, expanding the capacity of the dams on Buffalo Bayou.

"We can't just keep developing the way we've been developing," says Bedient. Most would agree.

Chadwick is executive director of Save Buffalo Bayou.