Impact of mean sea-level rise on the long-term evolution of a mega-nourishment

Impact of mean sea-level rise on the long-term evolution of a mega-nourishment

Ribas, Francesca (Universitat Politecnica de Catalunya)
Portos-Amill, Laura (University of Twente)
Falqués, Albert (Universitat Politecnica de Catalunya)
Arriaga, Jaime (TU Delft Environmental Fluid Mechanics)
Marcos, Marta (University of the Balearic Islands)
Ruessink, Gerben (Universiteit Utrecht)

2023

Mean sea-level rise (MSLR) will induce shoreline recession, increasing the stress on coastal systems of high socio-economic and environmental values. Localized mega-nourishments are meant to alleviate erosion problems by diffusing alongshore over decades and thus feeding adjacent beaches. The 21-st century morphological evolution of the Delfland coast, where the Sand Engine mega-nourishment was built in 2011, was simulated with the Q2Dmorfo model to assess the Sand Engine capacity to protect the area against the effects of MSLR. The calibrated and validated model was forced with historical wave and sea-level data and MSLR projections until 2100 corresponding to different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5). Results show that the Sand Engine diffusive trend will continue in forthcoming decades, with the feeding effect to adjacent beaches being less noticeable from 2050 onward. Superimposed to this alongshore diffusion, MSLR causes the shoreline to recede because of both passive-flooding and a net offshore sediment transport produced by wave reshaping and gravity. The existing feeding asymmetry enforces more sediment transport to the NE than to the SW, causing the former to remain stable whilst the SW shoreline retreats significantly, especially from 2050 onward. Sediment from the Sand Engine does not reach the beaches located more than 6 km to the SW, with a strong shoreline and profile recession in that area, as well as dune erosion. The uncertainties in the results are dominated by those related to the free model parameters up to 2050 whilst uncertainties in MSLR projections prevail from 2050 to 2100.

Climate change
Global warming
Mega-nourishment
Morphodynamic modelling
MSLR
Sand Engine

http://resolver.tudelft.nl/uuid:36d2123c-cfa6-40c6-92dc-4dcfbd96c501

https://doi.org/10.1007/s10584-023-03503-6

0165-0009

Climatic Change: an interdisciplinary, international journal devoted to the description, causes and implications of climatic change, 176 (5)

Institutional Repository

journal article

© 2023 Francesca Ribas, Laura Portos-Amill, Albert Falqués, Jaime Arriaga, Marta Marcos, Gerben Ruessink