Breaking the “Hydro-illogical” Cycle
René Franks is a Senior Associate and Stormwater Team Leader in Parkhill’s Public Works Sector. She is an expert in floodplain management, floodplain hydrology and hydraulics, infrastructure design, and subdivision development. Prior to joining Parkhill in 2010, René spent almost 20 years working for the City of Midland, holding positions up to City Engineer and gaining a deep understanding of municipal government. Prior to relocating to Midland, René was employed as a storm drainage engineer for a Houston area consultant.
The catastrophic and unprecedented flooding in Houston will renew discussion about stormwater management in that and many other cities. There is no time like the past to provide flood protection. Cities that have some reduced levels of flooding can be deeply grateful for earlier decisions that made it possible. But since in many cases we didn’t plan ahead, the present is the best time to start.
As a professional engineer specializing in predicting and preventing floods for over three decades, I have seen what is called the “Hydro-illogical” cycle, a play on the term hydrologic cycle, which describes how rain falls, flows into the ocean, evaporates into clouds, falls, over and over.
With each flood, public attention is drawn to the dramatic results, the rescues, the rebuilding. Funds are allocated for projects to prevent a repeat. We require better drainage management in our development policies. But major floods are not usually frequent (Houston being the exception recently). We implement a few improvements; then move on to more attractive uses of public funds such as roadways, police and other services, and parks. In a few years, drainage is pushed aside; a list of unbuilt drainage projects sits on a desk at City Hall; our regulations aren’t updated or enforced as we intended. THEN, IT RAINS! And we start the next loop of the “Hydro-illogical” cycle.
Can we break this cycle? Design and floodplain management professionals have a suite of solutions, most of which can best be implemented during development of land. Maintain wetlands and natural buffers along streams and rivers. Excavate detention basins to store runoff until the downstream water can receive it. Use paving materials and green spaces that allow infiltration, if the underlying soil is permeable enough. Limit urban sprawl. The golden rule should be that the new development will not flood anyone else’s property or itself.
Our city clients hire us to think of imaginative solutions for decades-old development where no one adequately predicted what the future floodplain management needs would be. There are older areas in every city where there simply is not a place for all the water to go. The resulting projects are expensive, and all of them involve buying out buildings, installing huge basins, or providing large storm drains through developed areas. The City of Lubbock is a client which has made a remarkable financial commitment to interconnecting natural wet-weather lakes with pipes and eliminating months of standing water.
Unfortunately, there are several factors that work against even the most determined cities’ efforts to protect from new and eliminate historic causes of flooding.
Much flooding in Texas happens because development occurs, often a few acres at a time, outside of cities. Counties in Texas have fewer powers than cities to regulate development, and in many cases have neither the citizen support, budget, nor a sense of urgency to engage in such difficult regulation. Many developers are quite responsible and provide flood protection on their own. Counties near large cities tend to be more proactive in using the powers they have to maximum effect. Texas should consider whether counties have adequate authority to protect Texans.
A lack of training is a challenge for West Texas counties. Parkhill, Smith & Cooper and the City of Fort Stockton provided floodplain management training to counties in West Texas in 2016, through the Texas Floodplain Management Association.
Local officials use floodplain maps published by FEMA in regulating where new developments can be placed, and how high. Many of these maps are out of date, not showing the effects of upstream paved and roofed areas that reduce infiltration and increase flooding. Often, local officials have more stringent requirements that take future development scenarios into account. This may not be enough, however, because rainfall and sea level are changing.
Building critical buildings such as hospitals, schools, etc., at a higher safety factor above the estimated flood elevation provides a buffer for 1,000-year floods, which we now know can occur in our lifetimes. A higher building level offsets out of date maps, lack of upstream regulation and in coastal areas, sea level rise.
Sea levels are already rising and predicted to go higher — whether we agree on the cause or not. We don’t know how far they might rise, so it’s best to play it safe and put new and rebuilt buildings a few feet higher. The expense we incur now will be far less than the disaster we avoid later.
We know that intense storms are occurring more frequently in the past few decades. This varies by location in the U.S., with the worst effects seen in New England, where there is 67 percent more very heavy precipitation than in the early 1900s. Heavy precipitation is already 15 percent more common in West Texas. What we thought was a safe design in years’ past might not be anymore, and that is another reason to provide extra factors of safety as we build and rebuild.
But the most important factor in breaking the “Hydro-illogical” cycle is public involvement. If something good comes from the incredible devastation in the Houston metro area, it would be a sustained interest and support for public officials in their efforts to manage stormwater and floodplains to protect us all.