Hurricanes as a Major Driver of Coastal Erosion in the Mississippi River Delta: A Multi-Decadal Analysis of Shoreline Retreat Rates at Bay Champagne, Louisiana (USA)

Abstract

The Louisiana shoreline is rapidly retreating as a result of factors such as sea-level rise and land subsidence. The northern Gulf of Mexico coast is also a hotspot for hurricane landfalls, and several major storms have impacted this region in the past few decades. A section of the Louisiana (USA) coast that has one of the highest rates of shoreline retreat in North America is the Caminada-Moreau headland, located south of New Orleans. Bay Champagne is a coastal lake within the headland that provides a unique opportunity to investigate shoreline retreat and the coastal effects of hurricanes. In order to examine the influence of hurricanes on the rate of shoreline retreat, 35 years (1983–2018) of Landsat imagery was analyzed. During that period of time, the shoreline has retreated 292 m. The overall rate of shoreline retreat, prior to a beach re-nourishment project completed in 2014, was over 12 m per year. A period of high hurricane frequency (1998–2013) corresponds to an increased average shoreline retreat rate of >21 m per year. Coastal features created by multiple hurricanes that have impacted this site have persisted for several years. Bay Champagne has lost 48% of its surface area over the last 35 years as a result of long-term shoreline retreat. If shoreline retreat continues at the average rate, it is expected that Bay Champagne will disappear completely within the next 40 years.

Analyzing the Impact of Sea Level Rise on Coastal Flooding and Shoreline Changes Along the Coast of Louisiana Using Remote Sensory Imagery

“…This is because the beachless coast of Louisiana is eroding and by the end of the 20th century, the land will be vanishing at a rate of about 24 square miles (62 square km) per year, especially with the incidence of Hurricane Katrina in 2005 which eroded an additional 73 square miles (189 square km) of the Louisiana coastland (Norrell, 2022). The rate of coastal retreat and land loss in Louisiana is therefore among the highest recorded in the world (Dietz & Bianchette, 2018). Hence, these effects have necessitated the need to understand and mitigate these impacts which are crucial for the preservation and sustainability of this valuable coastal treasure for current and future generations.…”

Effects of Beach Nourishment Project on Coastal Geomorphology and Mangrove Dynamics in Southern Louisiana, USA

“…The cyclic switching of the Mississippi River Delta lobe, coupled with human activities, have caused marine transgressions at the Bay Champagne coast for over several hundred years [37]. The shoreline retreated ~1550 m between 1887 and 2012, but the rate of shoreline erosion has fluctuated from ~14.8 m/year (1887-1930) to ~9.8 m/year and ~12 m/year [10,38,39].…”

“…This port is the only home-base for offshore oil terminals in the U.S., and serves as the intermodal support hub for ~90% of the Gulf of Mexico drilling and ~16% of the U.S. domestic oil and gas production [7]. However, the rapid acceleration of global sea-level rise (~3.4 mm/year at the present with an expected rise of 65 cm by 2100) has jeopardized the stability of many coastal areas around the world [8], particularly along the Mississippi River Delta, where reduced sediment supply, hurricane activity, and relative sea-level (RSL) rise have been causing shoreline retreat at an alarming rate of ~12-14 m/year [9][10][11][12][13][14][15]. Moreover, three-dimensional geospatial data indicate that the sand dunes at Caminada-Moreau Headlands were migrating inland at a pace of up to 4.4 m/year between 1998 and 2013 [12]suggesting that both the shoreline and the beach barrier were migrating landward as a response to sea-level rise and reduced sediment supply.…”

“…As part of the Louisiana Coastal Protection and Restoration Authority's coastal restoration effort to strengthen the beach barrier and mitigate the threats of shoreline retreat to the infrastructures and coastal wetlands at the lower Mississippi [26], a beach nourishment project was undertaken in 2013 to replenish 2.8 × 106 m 3 of sediments (dredged from offshore) along 9.5 km of coastlines near Port Fourchon [10]. In addition, sand fencing was installed in 2013 along the dunes to control the location and rate of aeolian erosion or sand deposition [27,28].…”

Do hurricanes or freezing events regulate the sustainability of subtropical mangroves on the Gulf of Mexico coast?

“…In 2020 and 2021 respectively, Hurricane Zeta (cat 3) and Ida (cat 4) made landfalls near Port Fourchon, Louisiana, in two consecutive years for the rst time since 1850s (Yao et al 2022b). The combined effects of hurricanes and relative sealevel rise (~9.16 mm/year at the present) (Jankowski et al 2017; NOAA 2021) have caused shoreline retreat at a rate of up to 14 m/year (Cohen et al, 2021;Dietz et al, 2018;Penland et al, 2005;Yao et al, 2018). The rapid shoreline retreat has prompted the Louisiana Coastal Protection and Restoration Authority (CPRA) to intervene by launching beach renourishment projects in 2013 to halt the land loss and coastal erosion (CPRA 2017).…”