• Energy Research

Ndour, A.; Ba, K.; Almar, A.; Almeida, P.; Sall, M.; Diedhiou; P.M., Floc'h, F.; Daly, C.; Grandjean, P.; Boivin, J-P; Castelle, B.; Marieu, V.; Biausque, M.; Detandt, G.; Tomety Folly, S.; Bonou, F.; Capet, X.; Garlan, T., Marchesiello, P.; Benshila, R.; Diaz, H.; Bergsma, E.; Sadio, M.; Sakho, I., and Sy, B.A., 2020. On the natural and anthropogenic drivers of the Senegalese (West Africa) low coast evolution: Saint Louis Beach 2016 COASTVAR experiment and 3D modeling of short term coastal protection measures. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 583-587. Coconut Creek (Florida), ISSN 0749-0208.West Africa's low and densely populated coasts crystallize most of the environmental and societal problems and resulting vulnerability. It is becoming urgent to document this coast and the natural and anthropogenic forces to understand its evolution. Saint Louis is a historic (World Heritage) city located on the Langue de Barbarie, a 10 km sandspit at the mouth of the Senegal River. Because of its location, it is vulnerable (erosion, flooding) to river and ocean variability. This intermediate barred microtidal beach is located in a storm-free intertropical environment, but is exposed to distant oblique energetic waves from high latitudes, causing one of the highest coastal drifts in the world (∼800,000 m3/year). As part of the COASTVAR project, an intensive international field experiment was conducted in Saint Louis from 4 to 13 December 2016 to quantify the natural protective role played by the sandbar, coastal currents and transient exchanges with the inner shelf. Many instruments have been deployed to measure waves, currents, bathymetry and topography. This article provides an overview on the objectives of the experiment, the deployment and the first results of the modeling of coastal protection strategy.

Sandy shorelines are constantly evolving, threatening frequently human assets such as buildings or transport infrastructures. In these environments, sea level rise will exacerbate coastal erosion to an amount which remains uncertain. Sandy shoreline change projections inherits the uncertainties of future mean sea level changes, of vertical ground motions, and of other natural and anthropogenic processes affecting shoreline change variability and trends. Furthermore, the erosive impact of sea level rise itself can be quantified using two primary different coastal impact models. Here, we show that this latter source of uncertainty, which has been little quantified so far, can account for 20 to 40% of the variance of shoreline projections by 2100 and beyond. This is demonstrated at four contrasted sandy beaches relatively unaffected by human interventions in south-western France. Over these four sites, a variance-based global sensitivity analysis of shoreline projections uncertainties can only be achieved owing to previous observations of beach profile and shoreline changes. This means that sustained coastal observations and efforts to develop sea level rise impact models are needed to understand and eventually reduce uncertainties of shoreline change projections, in order to ultimately support coastal land use planning and adaptation.

The European project DuneFront (https://dunefront.eu, https://cordis.europa.eu/project/id/101135410) is working to improve coastal protection across Europe by using Nature-based Solutions (NbS), such as Dune-Dike hybrids (DD-hybrids), to defend coastlines from extreme weather and rising sea levels. Within this project, this “Physical Boundary Conditions” deliverable focuses on collecting and mapping key physical boundary conditions that affect the effectiveness of these solutions. The aim was to create a consistent, Europe-wide, high-quality dataset that helps understand how DD-hybrids are, and will be, affected by waves, tides, weather patterns, and climate change. The dataset is made of 5 geopackage files, each duplicated in csv format for accessibility. See the deliverable report (pdf) for detailed information on each file, use notes, and literature references. We explicitly recommend the use of the gpkg files over csv for any GIS application, for reasons that are detailed in the report.