T. Mann, A. Serwa, A. Rovere, E. Casella, K. Appeaning-Addo, P.-N. Jayson-Quashigah, T. Mensah-Senoo, K. Trstenjak, B. Lassalle, M. Flitner, H. Westphal
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引用次数: 0
Abstract
Abstract Human infrastructures, such as dams, seawalls, and ports, can affect both the sedimentary budget and nearshore hydrodynamics, enhancing and accelerating the loss or gain of coastal sediments. Understanding the processes and factors controlling beach morphodynamics is essential for implementing adequate adaptation strategies in coastal areas, particularly in those regions where coastal protection measures are scarce. This study analyzes shoreline changes in the Keta Municipal District, located in southeastern Ghana (West Africa). This area is characterized by the sedimentary input of the Volta River, forming a river delta situated to the west, i.e., updrift, of our study site. Following the construction of two dams (Akosombo and Kpong) on the Volta River in 1965 and 1982, groins and revetments have been built along the coast between 2005 and 2015 to reduce the high rates of coastal erosion in this area. Here, we explore the influence of these dams and the hard protection constructions on beach morphodynamics using historical maps and satellite images complemented by a shoreline survey undertaken with a differential GNSS in 2015. The multi-decadal evolution between 1913 and 2015 reconstructed for 90 km of shoreline suggests that local erosion rates in the region predate the construction of the two dams on the Volta River, indicating that these structures might not be the primary driver of coastal erosion in this area, as previously suggested. We emphasize that delta dynamics under conditions of high-energy longshore drift, modified by anthropogenic drivers such as sand mining, play a key role in the long-term evolution of this coast. Our results also show that the infrastructures built to halt coastal erosion result in localized erosion and accretion down-current along the coastline towards the border with Togo, highlighting the need for a transnational perspective in addressing the problems caused by coastal erosion.
期刊介绍:
Geo-Marine Letters is an international peer-reviewed journal focussing on the rapid publication of concise original studies and reviews dealing with processes, products and techniques in marine geology, geophysics, and geochemistry. Coverage spans
- structural geology, including plate tectonics of recent active and passive margins
- sea-bed morphology, physiography and morphodynamics
- sediment transport, depositional processes and sedimentary facies analysis
- stratigraphy, basin analysis and paleoenvironmental reconstruction
- sea-level history, paleoproductivity, gas hydrates, salt domes and brines
- sediment-water interaction and organism-sediment relationships
- geochemical tracers, stable isotopes and authigenic mineral formation
- geotechnical properties and application of new geo-marine techniques, and more.
In addition to regular articles, reviews, discussion/reply articles and technical papers, Geo-Marine Letters welcomes contributions by guest editors in the form of conference/workshop proceedings, or bundles of papers dealing with specific themes.