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

Author(s)

Lisboa Cohen, Marcelo Cancela ^[1] ; Vivan de Souza, Adriana ^[1] ; Liu, Kam-Biu ^[2] ; Rodrigues, Erika ^[1] ; Yao, Qiang ^[2] ; Ruiz Pessenda, Luiz Carlos ^[3] ; Rossetti, Dilce ^[4] ; Ryu, Junghyung ^[2] ; Dietz, Marianne ^[2]

Affiliation

^[1] Fed Univ Para, Lab Coastal Dynam, Grad Program Geol & Geochem, Rua Augusto Correa 01, BR-66075110 Belem, Para - Brazil

^[2] Louisiana State Univ, Dept Oceanog & Coastal Sci, Baton Rouge, LA 70803 - USA

^[3] Univ Sao Paulo, CENA, 14C Lab, Av Centenario 303, BR-13400000 Piracicaba - Brazil

^[4] Natl Space Res Inst INPE, Rua Astronautas 1758 CP 515, BR-12245970 Sao Jose Dos Campos - Brazil

• Document type: Journal article
• Source: REMOTE SENSING; v. 13, n. 14 JUL 2021.
• Web of Science Citations: 0

Abstract

Relative sea-level (RSL) rise associated with decreased fluvial sediment discharge and increased hurricane activity have contributed to the high rate of shoreline retreat and threatened coastal ecosystems in Port Fourchon, Louisiana, USA. This study, based on QuickBird/drone images (2004-2019) and LIDAR data (1998-2013), analyzed the impacts of shoreline dynamics on mangroves (Avicennia germinans) and marshes before and after the initiation of a beach nourishment project in 2013. The coastal barrier and dune crest migrated landward between 1998 and 2013. Meanwhile, the dune crest height increased between 1998 and 2001, then decreased in 2013, probably due to hurricane impacts. The total sediment volume along this sandy coastal barrier presented an overall trend of decline in the 1998-2013 period, resulting in a wetlands loss of similar to 15.6 ha along 4 km of coastline. This has led to a landward sand migration onto muddy tidal flats occupied by Avicennia germinans (1.08 ha) and Spartina (14.52 ha). However, the beach nourishment project resulted in the advancement of the beach barrier from Nov/2012 to Jan/2015, followed by a relatively stable period between Jan/2015 and Mar/2019. Additionally, both the dune crest height and sediment volume increased between 2013 and 2019. This set of factors favored the establishment and expansion of mangroves (3.2 ha) and saltmarshes (25.4 ha) along the backbarrier environments after 2013, allowing the tidal flats to keep pace with the RSL rise. However, waves and currents caused shoreline erosion following the beach nourishment project between Oct/2017 and Nov/2019, threatening wetlands by resuming the long-term process of shoreline retreat. (AU)

• FAPESP's process: 20/13715-1 - Dynamics of American mangroves at austral and boreal limits on secular and decadal scales
• Grantee: Luiz Carlos Ruiz Pessenda
• Support Opportunities: Regular Research Grants