2020’s Hurricane Season is off to an Early Start with Tropical Storm Cristobal
Tropical Storm Cristobal is this hurricane season’s third named storm. Cristobal is unique in the sense that it has been classified as a rare “crossover” storm. Originating in the Pacific as Tropical Storm Amanda, the storm traveled through Central America crossing into the Gulf of Mexico where the residual force moved North and produced Tropical Storm Cristobal. The storm made landfall on June 7th in Southeast Louisiana and – considered its biggest oddity – managed to survive overland as a tropical depression moving further North until eventually dissipating over lower Wisconsin. This impressive land trajectory makes Tropical Storm Cristobal the 4th known tropical system to reach Wisconsin.
Hurricane Cristobal Nearly Eliminated the Gulf Coast’s Drought
Many communities located on the storm’s path suffered extensive damage and life loss due to flooding and tornadoes. The storm was so powerful that its outer bands reached the entire Gulf Coast and produced 10 inches of rainfall. According to Jonathan Erdman, a senior meteorologist for The Weather Channel, this rainfall alone almost entirely wiped out the ongoing regional drought that had lasted for a few months and spanned most of the Gulf Coast. After the storm passed, we set out to evaluate any damage that might have occurred to properties we currently maintain and have restored in the past. Unfortunately, a few properties endured significant erosion, but most emerged unscathed. When wave action erodes a section of beach, the surge deposits the sand elsewhere – enabling the sand movement cycles that foster our dynamic coastal ecosystem. Below, are 4 of the properties we documented in the weeks following the storm’s landing, three of which were on the receiving end of eroded sand and one that suffered extensive erosion.
Dune Villas, Seagrove Beach 30A, Florida: Extensive Erosion caused by Tropical Storm Cristobal
Of all the post-storm visits we conducted, a row of properties on Seagrove Beach experienced significant damage. Dune Villas Condominium was one of the properties that underwent heavy erosion, emerging from the storm with a steep drop-off. A large peatland formation east of the property is most likely a factor that contributed to Dune Villa’s extensive loss of sand. Peatland is a tough, fibrous material that can absorb surge shock without eroding as quickly as sand. By assessing the contour of Dune Villas’ erosion, our team concluded that Cristobal’s storm surge most likely struck the peatland to the east and curved landward, resulting in a churning effect that carved out a semi-circle depression in Dune Villas Condominium’s dune. In the aerial images, the black mass on the beach is the peatland and to its immediate left is Dune Villas. We are currently working with authorities to arrive at solutions that can offset their damage.
1900 Ninety Eight Condominium, Destin, Florida: More Sand Accumulation as a Result of Cristobal
At 1900 Ninety Eight, a gulf front condominium located in Destin, we estimate that Cristobal’s surge deposited a little over a foot of sand on their dune. In the images below, take note of their white umbrella box. In the picture to the right, taken before Storm Cristobal, the box is completely above ground; but in the picture to the left, taken after the storm, the container is half-buried. To read more about the evolution of 1900 on 98’s dune’s evolution read our case study here.
Bella Vita Condominiums, Santa Rosa Beach, Florida: Dune Stabilization under the Boardwalk
Another property that gained a fresh layer of sand was Bella Vita Condominiums, Santa Rosa Beach. To fully understand the significance of their outcome, let’s briefly discuss the project we implemented two months prior to Cristobal. As of early March, the portion of Bella Vita’s dune under the boardwalk was suffering from heightened erosion because of a phenomenon we call the Washing Machine Effect. This effect is caused by storm surge churning away at the sand around the base of a boardwalk’s beams, aggressively eroding that portion of the dune. In our experience, the Washing Machine Effect is quite common rendering the stretch of sand underneath a boardwalk often the most susceptible to erosion. To neutralize this effect, we installed native vegetation under their boardwalk to help stabilize the slope. The image to the left was taken shortly after the native vegetation was installed in mid-March, and the image to the right was taken after Cristobal. The most obvious difference between the two is how little bare sand can be seen in the image to the right as the vibrant vegetation has successfully colonized the slope and anchored it in place when Cristobal’s surge washed through.
An additional benefit the two images above reveal is how the sand accumulation resulted in a more gradual incline after the storm. Take a closer look at the single sand fence blocking passage under the boardwalk in the bottom right corner of both images. To help you visualize the accretion, we highlighted the top of the sand fence and the slant of the slope. When compared, the image to the right depicts a slope that is nearly parallel with the top of the fence and significantly less steep.
Bella Vita Condominiums Continued: Sand Fences Captured Fresh Sand
The following images showcase how much sand Bella Vita’s sand fences captured during Cristobal. In the left picture, 4 binding wires spaced vertically about a foot apart stretch horizontally across the planks to hold the fence together. In the image to the right, only 3 binding wires are above ground indicating about a foot of sand was deposited on their protective berm. Also, in the middle right of the left picture, you can see ornamental dune flowers at the base of a single signpost. In the picture to the left, the flower bed is almost entirely buried and, with it, the defined sharp angle the slope used to make when it met the toe of the dune.
Wind Drift Condominiums, Orange Beach, Alabama: Sand Fences Captured Fresh Sand
Another property that benefitted was Wind Drift Condominiums located in Orange Beach, Alabama. Below, the picture to the left was taken two weeks before Storm Cristobal. By counting the sand fence’s horizontal wires that are spaced at roughly one foot apart from each other, we know the visible portion of the sand fence was roughly almost four feet above the ground before the storm. Afterward, only three wires are visible indicating the fences and vegetation captured roughly one foot of sand.
Why did Some Properties Benefit while Others were Damaged?
Some of the factors that determine whether Mother Nature will either build or erode your dune during a storm include the beach’s contour, the height of the storm surge, and the angle at which the high tides wash up onshore. Because these factors change on a daily basis, the impact that a storm will have on your property ultimately boils down to luck. However, when a property owner has invested in optimizing their dune and in building a new protective berm prior to storm action, this combination between luck and preparation may yield an impressive outcome as the healthy vegetation and sand fencing can effectively trap the surge-borne sand. The National Oceanic and Atmospheric Administration (NOAA) predicts that 2020 will be a year with above-average Atlantic hurricane activity. As this hurricane season unfolds, we are committed to support you and help you prepare and recover from future storms that may threaten your property.
“Busy Atlantic Hurricane Season Predicted for 2020.” Busy Atlantic Hurricane Season Precited for 2020 | National Oceanic and Atmospheric Administration, www.noaa.gov/media-release/busy-atlanic-hurricane-season-predicted-for-2020.
Erdman, Jonathan. “Tropical Storm Cristobal Almost Wiped Out Gulf Coast Drought.” The Weather Channel, The Weather Channel, 11 June 2020, weather.com/storms/hurricane/news/2020-06-11-tropical-storm-cristobal-drought-relief-gulf-coast.