Q&A: Houston hydrologist explains climate change’s role in intensified flooding, importance of planning for future storms

Hurricane Harvey hit the Houston region in 2017. (Vanessa Holt/Community Impact Newspaper)
Hurricane Harvey hit the Houston region in 2017. (Vanessa Holt/Community Impact Newspaper)

Hurricane Harvey hit the Houston region in 2017. (Vanessa Holt/Community Impact Newspaper)

Climate change’s effects on water in the Houston area—from droughts to flooding—has been a key consideration in some of Stephanie Glenn’s most recent work.

Glenn has worked with the Houston Advanced Research Center since 2003, specializing in ecology and hydrology. She currently serves as the organization’s hydrology and watersheds program director, and she has worked with the Greater Houston Flood Mitigation Consortium to help identify steps to mitigate the effects of flooding locally.

“We are definitely staring down the barrel of hurricanes with stronger winds, more rainfall,” she said. “We’re looking at more intense and more frequent storms, and so, as a region, we’re going to need to think about that when we’re planning. We need to plan for that worst-case climate change [scenario].”

A best-case scenario to mitigate the impacts of climate change long-term would be lessening the amount of emissions in the air and having nation leaders worldwide agree on certain protocols, Glenn said.

However, she said she believes this is an unlikely outcome, and most scientists project climate change falling somewhere between this best-case and a worst-case scenario, in which sea levels along the Texas coast could rise by 6 feet and the annual average temperature could rise by 7 degrees Fahrenheit by the end of the 21st century, according to a report from the U.S. Global Change Research Program.

Community Impact Newspaper interviewed Glenn about flooding issues in the Houston region and how climate change plays a role. Responses may have been edited for length and clarity.

What are your thoughts on the $2.5 billion bond passed a couple years ago for new flood mitigation projects in Harris County?

I would say it’s definitely a good starting point. I know it sounds like a lot of money, and it is a lot of money, but when you’re talking about some of these flood mitigation projects—these are major, expensive projects. Every little bit helps.

Flooding is the whole region’s problem. It’s a problem for the people that it impacts at the time, but solutions to it are regional, and so every little thing that’s put in along the watershed is going to help protect flooding downstream. If you put a solution into one place, you’re just moving the flooding problem further downstream, so you want to make sure that you have a combination of solutions all throughout the watershed.

The bond includes some drainage projects, sedimentation projects, some floodgate type projects for some of the reservoirs—everything like that can help. But there is no one ring to rule them all. There’s no big solution that could come in and stop flooding, but you can mitigate its impacts, and these projects will definitely help mitigate the impacts.

Beyond the projects included in the bond, what are some other steps that could be taken at the county, state and federal levels to help make the region more flood-resilient?

It’s critical in the region that we have the counties working together, the cities working together, that we recognize that flooding doesn’t stop at these divisions of county lines. It really is watershed by watershed, and all these watersheds end up in one bigger watershed, and they all impact each other.

I think that we need to continue having the discussions where we take into account vulnerability and social equity. Hurricane Harvey really showed households that are struggling financially are going to be the hardest-hit. They don’t have the capability of recovering as some of the other households do.

With these big flooding events, there’s always a big response right afterwards, but it is crucial that we focus those conversations to before the big storm and not after.

Why is it important to take preventive measures rather than to try to figure it out in the aftermath of a major storm?

Harvey was such a turning event for Houston because it really gained a lot of traction to continue talking, to continue planning among agencies, to face the fact that we’re going to have to design differently. The rainfall that we’re looking at now is not the rainfall of the past. A 100-year flood plain is going to have to have different design standards because there is going to be more precipitation in those 100-year storm events.

Really focusing regionally and looking at the hardest-hit areas, what happened and what we can do differently next time—having those kinds of plans in place beforehand and talking about response and recovery is important. What systems are in place, and where can people go? What is it going to mean if this vulnerable population is without electricity for a certain amount of time? Where can they go to get the resources they need, and how can we get them there?

The conversation is about mitigating impacts in all different areas and mitigating the flood itself. What can we do to help those waters come down slower and dissipate to all areas and not just one? What can we do to help the people in the path of the floodwaters? What can we do to help the response teams? What can we do to help with planning?

How is climate change contributing to the increased frequency and devastation of these major flood events?

When you’re looking at things like storm events and hurricanes, this season alone is a good example of what happens when you have warmer temperatures in the Gulf. And it doesn’t have to be by a lot, but the current predictions are more frequent and more intense storms, which bring more and bigger flood events.

We hear a lot about the importance of having updated flood plain maps. How much does climate change play into that versus development?

It’s about both. The development is very important to keep up with because that changes a lot of what goes into some of those flood plain calculations. The simplest way to think about that is more development brings more concrete and quicker, flashier runoff. That impervious area change is a big deal for those.

Climate change is also a big deal. Atlas 14 [a study including historical and projected future rainfall data] was prompted by a big change in precipitation—especially with Harvey, where we got more than we’d ever gotten in that short amount of time. They use some of those models to figure out where the 100-year storm and the 500-year storm is going to be when calculating those flood plains, too.

Do you ever see Harris County getting to the point where it won’t have devastating floods like Harvey?

I’d like to think we can get to the point when we could say we put ourselves in a position to really help mitigate the devastating impacts from storms like Harvey. Will we continue to see storms that are more intense? Yes. But can we continue to plan so that the impacts we see aren’t as intense? I think as a region, we have the capability to do so.
By Danica Lloyd

Editor, Cy-Fair

Danica joined Community Impact Newspaper as a reporter in 2016. As editor, she continues to cover local government, education, health care, real estate, development, business and transportation in Cy-Fair. Her experience prior to CI includes studying at the Washington Journalism Center and interning at a startup incubator in D.C., serving as editor-in-chief of Union University's student magazine and online newspaper, reporting for The Jackson Sun and freelancing for other publications in Arkansas and Tennessee.