Landscape architects well aware of coastal Texas’ vulnerabilities and strengths weigh in on Hurricane Harvey’s landfall.
By Zach Mortice
This is Part 3 of our conversation about Hurricane Harvey with the design team at Studio Outside in Dallas, which has won a 2017 ASLA Professional Award for Analysis and Planning for its work on Galveston Island State Park. Part 1 and Part 2 can be found below. Correction appended below on August 28.
Studio Outside’s resiliency plan for Galveston Island State Park earned a 2017 ASLA Professional Award for Analysis and Planning, drawing praise from the jury for its comprehensive and forward-looking anticipation of the havoc a hurricane could release. But Studio Outside’s Andrew Duggan and the design team, led by principal in charge Mike Fraze, knew they were pondering ironclad eventualities, not hypothetical disasters.
Over the weekend, the city of Galveston and Galveston Island State Park to its southwest found themselves in the path of Hurricane Harvey, which made landfall on Friday night, a Category 4 storm that has prompted mass evacuations of the Houston region.
Studio Outside’s project, “Storm + Sand + Sea + Strand: Barrier Island Resiliency Planning for Galveston Island State Park,” tracks the loss of habitat and land as perpetuated by sea-level rise, encroaching development, and hurricane flooding. It prescribes soft and green natural barriers to storm surges, assisted by flexible infrastructure. As a barrier island bordered by Texas’s West Bay to the northwest and the Gulf of Mexico to the southeast, there are few places to hide from floodwaters or to absorb them, and even less given that this part of the island was partially paved over to accommodate RVs in the 1970s. On Friday and over the weekend, Duggan (based safely in Dallas) and members of the design team (Fraze and Duggan of Studio Outside, and Jennifer Dowdell and Ed Morgereth of Biohabitats) emailed LAM some thoughts on how the storm might play out for Galveston Island State Park.
****Post will be updated as the storm progresses****
Part 3: Thursday, September 7
Was most damage caused by rain as the storm hovered over the island, as you suggested last week?
Andrew Duggan: I did visit with one of our contacts for the project with [the] Texas Parks and Wildlife Department (TPWD) on Tuesday, August 29, and as of that time there were no real reports from the site yet. But the expectation was somewhat grim that each of the coastal state parks in the system would likely have some damage, potentially heavy. During the planning phase of the project, there was talk about TPWD policies for securing the site, transport of vehicles to higher ground, and evacuation of staff in advance of storms. Folks around here are primarily focused on rescue at the moment, and it seems that the assessment and recovery phases will be coming next week. Anecdotally, however, I [saw] on the news [on] Thursday that Texas A&M University’s Galveston Campus is back in for classes on Monday or Tuesday of [this] week with apparent minimal damage. Although that campus is on the east end of the island that has the sea wall, that is positive news.
How did this hurricane compare with recent past hurricanes that have struck the area?
Jennifer Dowdell: From all we have read, this hurricane was unique in recent historical records given the amount of time it spent in the region—[it was] almost stationary—and given the rainfall amounts that have been reported. The National Weather Service had to add colors to their mapping palette in order to report on this much rainfall in one storm event. Because there was not a direct hit on Galveston Island, it has probably avoided some of the most catastrophic damage to structures that we saw after Ike, but we will have to wait to see.
Ed Morgereth: Before Hurricane Harvey, there had been four hurricane landfalls in Texas in the 21st century: Claudette (July 2003), Humberto (September 2007), Dolly (July 2008), and Ike (September 2008). Hurricane Rita (September 2005) technically made landfall in Cameron Parish, Louisiana, but also affected Texas. Of these storms, Ike was the strongest as a Category 2 storm with winds of 110 miles per hour at landfall; it was surpassed by Harvey as a Category 4 storm with 130-mile-per-hour winds. The last Category 4 hurricane to make landfall in Texas before Harvey was Carla in 1961, with winds of 145 miles per hour. It should be noted that the total amount of rainfall with a storm, and the associated rainfall impacts, aren’t necessarily associated with storm category intensity. Many slow-moving tropical storms also have had significant heavy rainfall impacts in Texas, such as Amelia (1978), Claudette (1979), and Allison (2001).
Andrew Duggan: Each storm has its own personality, a signature issue that people remember. For Harvey, it will likely be the rain and inland flooding. It will also be remembered by the spirit of the Houston community, who have reached out to help their neighbors. Although the rain has stopped, there are also bound to be some more surprises that occur when the water recedes.
How long does it take these ecosystems to recover from a shock like this?
Ed Morgereth: That can be highly variable, taking a range of days to decades to recover. The timescale for recovery depends on the spatial extent of the area affected, and the intensity of specific impacts. Only time will tell.
Andrew Duggan: I was visiting with one of our clients at Audubon Nebraska who was telling me about habitat assessment teams that are already on the ground assessing things. The example from Audubon was the potentially affected whooping crane habitat in South Texas that serves as wintering grounds for the species. The question is, when a threatened or endangered species returns south as part of an annual migration, and their expected habitat has been significantly impacted since their last visit, what do they do? Where do they go to search out suitable wintering grounds? What is the long-term impact on the species? Natural habitats are generally more resilient than developed areas, but this has been an extreme event.
Do you plan to go to Galveston Island State Park and assess damage? Might this be an opportunity to revise your plans?
Andrew Duggan: We are most interested in visiting the site and seeing how it fared. The point of all the long-term planning for the site is to anticipate these events and how they quite literally change the site. Storms such as Harvey were part of the modeling that our team developed to predict the future of this diverse island environment. This storm likely hastened some of those predictions, but it may be years until we know by how much. Hopefully this unfortunate storm event will encourage decision makers to invest in plans that embrace resilient and restorative approaches to park development. This is the only way that we can work with the natural ecosystem to deliver unique experiences for all visitors—both now and for generations to come.
Part 2: Monday, August 28
Do you know how much damage was done to the park with the storm’s initial impact?
Andrew Duggan: The park is closed, and I haven’t seen any footage from the site. I am curious how the “temporary” facilities that the Texas Parks & Wildlife [Department] constructed after Hurricane Ike have fared—namely a visitor [center] building on the beach, and some restroom structures both on the beach and on the bay, none of which were significantly elevated. The only other new facilities that have been built since Ike were two park ranger/manager residences on the bay side that were elevated, and a new maintenance facility that is two levels. Finally, the restoration of two historic homes on the bay side of the property as group cabins was completed a few years ago, but as they were historic, they were not elevated. Those may be susceptible to some flooding. We’ll have to wait and see as the rain subsides.
How long might it take for torrential rains to begin significantly impacting Galveston Island State Park and causing excessive erosion?
Ed Morgereth: Episodic bands of heavy rains have been pushing through the region, and are projected to continue for the next several days. Inundation and flooding is expected to continue all around the Galveston area, including West Galveston Island. Localized erosion can be an issue where intensive runoff occurs, particularly in exposed soil areas. Erosion from this hurricane is more of an issue on the Gulf-side beach, and on dunes from onshore-driven wind and waves.
Andrew Duggan: The master plan purposefully moves the beach-side camping behind a generous setback from the beach, to allow for a dune field to be restored. Many factors contribute to beach erosion during storms, not the least of which is the storm surge, and then the receding waters that pull sand back into the gulf. Hurricane Ike took 90 feet of beach from Galveston Island State Park, with an almost direct hit. Should be less this time, but down where Harvey came onshore it could be worse.
How much water can these types of wetlands absorb and contain? Per day, per hour?
Ed Morgereth: That is difficult to answer quantitatively. Generally speaking, the brackish and salt marsh wetlands in the park can handle tremendous amounts of rain, as they are directly connected to the tidal waters of Galveston Bay. Freshwater wetlands in the swales behind the beach dunes and the ponds in the park will fill up with rainwater. They go through a pattern of drawing down in dry or droughty periods and recharging in wet weather. The amount of rain projected before Harvey’s effects are over with is extreme over the next several days, potentially measured in feet of rain.
Would the hurricane have been worse and stronger as it traveled deeper into Texas if it hadn’t had to pass over a series of barrier islands first?
Ed Morgereth: Barrier islands tend to be a first line of defense in absorbing storm impacts. Naturally functioning extensive wetland systems help absorb hurricane storm surge impacts. Without the functions provided by barrier islands and wetlands, direct hurricane impacts would be felt farther inland. Their protection, conservation, restoration, and management are important to long-term coastal resiliency protection including from tropical storm/hurricane impacts.
Andrew Duggan: The proposed “Barrier Island Discovery Center” is intended to engage visitors with the overlapping storylines of the barrier island environment: tropical storms, wildlife, habitat, beach, bay, cultural elements, and many others. It is intentionally located on the bay side of the park so that visitors are encouraged to explore all aspects of the island transect rather than primarily visiting the beach. Hopefully as we come to comprehend these systems, we can better learn to anticipate and plan resilient systems that can accommodate these periodic events. It is how we manage and care for these systems between episodic hurricane events that dictates how they perform during one. It should be noted that our team also included Joey Coco, a hurricane engineer, now with Forte & Tablada in Baton Rouge, Louisiana, who helped us navigate the possible storm scenarios that may face Galveston Island State Park in the future. His data, combined with the predictive sea-level-rise models prepared by Biohabitats Inc., became the basis for the planning vision. We had to comprehend what the site may be in 50 years before we could think about what to rebuild there today.
Part 1: Saturday, August 26
What happened to Galveston Island State Park in 2008 with Hurricane Ike? How was the island affected? How was it damaged?
Mike Fraze: The entire site was inundated with over eight feet of storm surge, and the result was complete devastation. It seemed that half of the beach side campsites were simply gone, and the other half were covered in sand or broken [into] pieces. Roads buckled and utilities were uprooted.
Ironically, this level of destruction created two phenomena: [It] recalibrated the lens of park planning in coastal environments by proving that buttressing and fighting Mother Nature does not work, and a reconsideration of best practices was required. And [it created] a relatively clean slate to [re-envision] this park. The planning process was a rare opportunity to literally rebuild from the ground up. [The] Texas Parks & Wildlife Department and the planning team seized the chance to rebuild with a natural system resiliency mind-set.
What are the biggest risks to the island and Galveston Island State Park with this hurricane?
Ed Morgereth: There’s the potential for high winds and coastal flooding, and with that, there may be saltwater inundation of some of the freshwater wetlands found within the park. But let’s be clear that there are a lot of unknowns with this storm including its exact landfall location.
Andrew Duggan: And the forecast is changing hourly. The situation with Hurricane Harvey is very different as it relates to Galveston than were the conditions with Hurricane Ike in 2008. Harvey is bearing down on Corpus Christi—about 200 miles southwest of Galveston—where Ike was almost a direct hit on the island. The biggest risk with Harvey might be an ongoing rain deluge and associated flooding if the storm stalls, and meanders up the coast over a period of days with a continuous assault of rain. That said, the churning of the gulf and expanded wave action will most certainly contribute to more rapid beach and dune erosion.
Is Galveston Island State Park particularly vulnerable to hurricane flooding?
Ed Morgereth: Yes. And it is worth noting that Galveston Island is very low-lying. Much of it is less than [10 feet] above sea level, so effects during a hurricane with a large storm surge on the system are inevitable. The question becomes, how resilient is the landscape to flooding and storm surge?
Because of all of the changes that have occurred over the last several decades, we see significant reductions in wetlands and [marshes] (key natural features in the absorption of some of the effects of storm surge) present when natural conditions prevail. But here, the natural conditions on the island as a whole have been replaced by roads, buildings, and infrastructure. And within the park there is a reduced amount of wetland habitat on the bay side available to help absorb the storm surge and the flooding that is likely to occur. Dunes on the beach side of Galveston Island have been compromised, reducing their storm attenuation function.
Jennifer Dowdell: As an undeveloped natural feature, the barrier island could respond to these weather systems with natural cycles of erosion, sedimentation, and dune migration. The winds and waters pick up the sand and move it in natural ebbs and flows, and the plants reseed themselves with time. But when it is populated, those natural features are gone, or are much smaller. At Galveston Island State Park, we have remnants of unique and important ecosystems, but they are represented within the 2,000 acres of the park. The island is about 134,000 acres in total.
Mike Fraze: The broader context of the story, however, is that development patterns on the island and degradation of natural habitat have increased the vulnerability, as natural systems are generally more resilient to storms than the historical construction patterns on the island. Although many lessons were learned from Ike, construction on the island continues.
How does hurricane flooding disrupt ecosystems in the region: the health of plants and animals, migration patterns for fauna, etc.?
Ed Morgereth: If we step back and consider this as a natural system, without the human impact, this barrier island system has always had hurricanes playing a role. The system has evolved to be resilient, with the migration of dunes, and natural erosion and sedimentation patterns. That resiliency is diminished by human development patterns.
Often, in the naturally functioning barrier island/dune system, the wildlife have evolved to survive these events. The birds will fly inland. The terrestrial creatures move to higher elevations. The aquatic species may take refuge in deeper areas of the water. Unfortunately, in an altered system like what we have left at Galveston Island State Park, there is less refugia available on the island overall, and the systems have been fragmented such that the wildlife may have a harder time migrating to these safer high elevation spaces. Storms such as Hurricane Ike [had] a storm surge that [covered] essentially all of the island’s habitats. The saltwater inundation of the freshwater ponds and of inland areas might also cause impacts to species sensitive to saltwater, such as the live oak mottes found within the park.
Sea-level rise brought on by climate change is predicted to swallow up almost a quarter of the park’s land by 2060. How does this anticipated land loss affect how the island handles hurricane storm surges?
Ed Morgereth: Unfortunately, we have seen significant wetland loss since the 1970s in the Galveston Island system, and this has been exacerbated by sea-level rise. If sea-level rise is accelerated as projected, then at some point we are going to see a system of migration and accretion of wetland habitats lose their ability to keep up with the rate of change. The barrier island’s natural responses may not be able to keep up with the sea-level rise, causing loss of habitats and functions including storm abatement. This is why it was so important during our planning process to consider the steps needed to take to restore and manage habitats and their ecological function within the park. The park needs assistance in recovering function and habitat value in the face of storms and climate change.
Correction: An earlier version of this post indicated that Andrew Duggan led Studio Outside’s design team. The principal in charge was Mike Fraze. We regret the error.