Best response to flooding? Initiative looks for solutions based in evidence

Flooding is the most disruptive natural hazard in the United States. It’s also an issue of great significance in Texas, whose Gulf Coast region is home to 7 million people — a population greater than 35 of the U.S. states.

The potential for another Hurricane Harvey-like disaster is ever-present. The hurricane’s catastrophic damage, spread through a 49-county area, ranged in the hundreds of billions of dollars; the damage was exacerbated by decades of development in low- lying coastal areas.

The best response to flooding is a coordinated group of local, regional and national-scale, evidence-based solutions, said Galen Newman, an associate professor in the Department of Landscape Architecture and Urban Planning and director of the Center for Housing and Urban Development.

Newman is part of a sizable band of researchers seeking flooding solutions as part of Partnerships for International Research (PIRE), a massive, $3.5 million, five-year initiative funded by the National Science Foundation that includes faculty and student researchers from Texas A&M, Rice University, Jackson State University, and TU Delft in the Netherlands, a nation that has fine- tuned flood mitigation techniques for centuries and is considered the world’s flood prevention leader.

In addition to collaborating year-round with Netherlands flood reduction experts, Newman, with other PIRE-associated faculty, accompanies 15 Texas A&M students to the Netherlands each summer as a part of the PIRE program to conduct flood reduction research with his guidance. (The trip was suspended in 2020 due to the coronavirus pandemic.)

Part of the complexity of implementing flood reduction measures is that there’s no “one-size- fits-all” solution, said Newman, who heads the Texas A&M Department of Landscape Architecture and Urban Planning’s PIRE engagement. There’s a variety of measures, such as engineered structures — levees, dikes and seawalls — as well as “green” infrastructure, including wetlands and detention ponds.

There’s also a difference in project size: large scale, such as the previously mentioned dikes; medium scale, such as a park or riparian zone instead of a housing or commercial development in a flood zone, and small scale, such as rain gardens or a bioswale — a landscape element with gently sloped, vegetation-filled sides that removes silt and pollution from storm water runoff and routes it to larger waterways.

Ideally, these measures all work together, conveying ordinary amounts of storm water to a designated area for holding or funneling to other channels. In the case of storm water overflow, instead of inundating homes or businesses, it should get funneled to other channels until it is eventually washed into a lake, reservoirs or other bodies of water.

“The intent is to also slow the volume of storm water runoff and capture as much as you can to increase its ground absorption,” said Newman. “You’re looking to reduce the amount of impervious surfaces such as parking lots, which are a significant contributor to urban flooding.”

Newman has applied his PIRE-related research findings to Texas projects.

In one study, Newman explored and devised enhancements for integrating the previously proposed Ike Dike – a proposed clay-core dune running along Galveston Island and the Bolivar Peninsula with two large-scale floodgates at opposite ends of the island – into the landscape, with less visual and spatial disturbance. The dike’s proponents see it as a protection mechanism from Galveston Island floods, but the dune, if not integrated correctly, could also become a visual and social barrier that decreases beachfront connectivity and walkability and fragment animal habitat areas.

Newman recommended incorporating elements that would improve the dune by providing economic and social benefits to the area while enhancing the dunes’ flood reduction effectiveness, that include the placement of:

• flood ‘overtopping’ detention areas behind the dunes that would attract wildlife and absorb unblocked storm surge;
• retail spaces, such as cafes and beach equipment rental businesses, between the beach and the dunes;
• green spaces with bicycle and pedestrian lanes atop and across the dunes, and
• native plantings to protect the stability of the dunes

In another project, PIRE-affiliated graduate landscape architecture student Zixu Qiao created an award-winning design proposal in 2017 of a medium-density development at a 97-acre site in coastal League City, Texas, that is highly vulnerable to flooding and sea level rise.

Her concept’s main feature is a large, central preserved wetland that serves as both a recreational area in dry times and a flood zone during heavy rains or a storm surge. The space’s numerous amenities include a boat launch, a recreational pier and walking paths. A gate protects the development from adjacent Clear Creek floodwaters and a built slope covered with vegetation mimics a natural levee.

The green space is surrounded by residential and commercial areas with permeable paving and bioswales.

Her plan earned a highly coveted 2017 Student Honor Award from the American Society of Landscape Architecture. The award is one of the most competitive and prestigious awards a landscape architecture student can earn, said Newman, who chaired Qiao’s final study committee.

Newman’s research also informs his green landscape performance modeling — virtually increasing an existing design’s “green” infrastructure by a predetermined amount, and then seeing how much the flood and storm water associated with the design decreases.

“With this kind of modeling, we can advocate for the inclusion of ‘green’ infrastructure because we have data to show how, together with new land use procedures, it makes a real reduction in Gulf Coast flooding,” said Newman.