Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast
Current coastal protection strategy in Portugal defines beach and shoreface nourishment as a valid measure to mitigate coastal erosion in some erosional hot-spots, being considered as an adaptation measure under the present climate change scenario, including the impacts of sea level rise. However, s...
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| Format: | Article |
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MDPI AG
2022-01-01
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| Series: | Journal of Marine Science and Engineering |
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| Online Access: | https://www.mdpi.com/2077-1312/10/2/146 |
| _version_ | 1797478994379014144 |
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| author | Celso Aleixo Pinto Rui Taborda César Andrade Paulo Baptista Paulo Alves Silva Diogo Mendes Joaquim Pais-Barbosa |
| author_facet | Celso Aleixo Pinto Rui Taborda César Andrade Paulo Baptista Paulo Alves Silva Diogo Mendes Joaquim Pais-Barbosa |
| author_sort | Celso Aleixo Pinto |
| collection | DOAJ |
| description | Current coastal protection strategy in Portugal defines beach and shoreface nourishment as a valid measure to mitigate coastal erosion in some erosional hot-spots, being considered as an adaptation measure under the present climate change scenario, including the impacts of sea level rise. However, scant objective data on shoreface nourishments are available to evaluate performance of this type of intervention in mitigating beach erosion and managing coast risk. We present the first monitoring results of a ≈2.4 × 10<sup>6</sup> m<sup>3</sup> shoreface nourishment on the Aveiro coast (Costa Nova—Ílhavo), the largest until now in Portugal, focusing on its morphological development, impacts on adjacent beaches due to alongshore spreading and cross-shore redistribution, and contribution to the sediment budget of the nourished sediment cell. The analyses are based on high-resolution coastal monitoring data, provided by the Portuguese COaStal MOnitoring Program (COSMO). A Multiple Monitoring Cell (MMC) approach was used to evaluate local and feeder efficiency of the nourishment, sediment budget exchanges within both the placement and wider survey domains (≈1 km<sup>2</sup> and 12 km<sup>2</sup>, respectively). Results show rapid (ca. 6 months) morphological change over the placement area, with a decrease of about 40% of the initial volume. Fast onshore sediment redistribution explains part of this change, placed sand having merged with the pre-existing bar system increased the volume of the shallower nearshore. Longshore transport is reflected by increasing the robustness of the bar downdrift of the placement area and also explains the negative sediment budget (0.75 × 10<sup>6</sup> m<sup>3</sup>) of the survey domain, which corresponds to losses through its southern boundary. Sediment spreading also induced accretion of the subaerial section of Costa Nova beaches in front of the placement area, reversing their long-term erosive trend. In contrast, this trend persisted at downdrift beaches. This suggests that the time lag of the subaerial beach response to this intervention increases with the distance to the placement area, and reversal of the erosive trend will only be noticeable in the following years. This study provides new insights on the time scales of beach response to high-magnitude shoreface interventions in high-energy wave-dominated sandy coasts, which will support decision making regarding similar operations designed to manage erosional hot-spots elsewhere. |
| first_indexed | 2024-03-09T21:40:32Z |
| format | Article |
| id | doaj.art-c1a76c77b5534929ab6240f1ffa69ead |
| institution | Directory Open Access Journal |
| issn | 2077-1312 |
| language | English |
| last_indexed | 2024-03-09T21:40:32Z |
| publishDate | 2022-01-01 |
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| spelling | doaj.art-c1a76c77b5534929ab6240f1ffa69ead2023-11-23T20:34:18ZengMDPI AGJournal of Marine Science and Engineering2077-13122022-01-0110214610.3390/jmse10020146Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western CoastCelso Aleixo Pinto0Rui Taborda1César Andrade2Paulo Baptista3Paulo Alves Silva4Diogo Mendes5Joaquim Pais-Barbosa6Coastal Monitoring and Risk Division, Portuguese Environment Agency (Agência Portuguesa do Ambiente), 2610-124 Amadora, PortugalIDL—Instituto D. Luiz, Departamento de Geologia, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, PortugalIDL—Instituto D. Luiz, Departamento de Geologia, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, PortugalDepartamento de Geociências e Centro de Estudos do Ambiente e do Mar (CESAM), Campus de Santiago, Universidade de Aveiro, 3810-193 Aveiro, PortugalDepartamento de Física e Centro de Estudos do Ambiente e do Mar (CESAM), Campus de Santiago, Universidade de Aveiro, 3810-193 Aveiro, PortugalHAEDES, Casais do Arrocho, 2025-452 Azóia de Cima, PortugalDepartamento de Física e Centro de Estudos do Ambiente e do Mar (CESAM), Campus de Santiago, Universidade de Aveiro, 3810-193 Aveiro, PortugalCurrent coastal protection strategy in Portugal defines beach and shoreface nourishment as a valid measure to mitigate coastal erosion in some erosional hot-spots, being considered as an adaptation measure under the present climate change scenario, including the impacts of sea level rise. However, scant objective data on shoreface nourishments are available to evaluate performance of this type of intervention in mitigating beach erosion and managing coast risk. We present the first monitoring results of a ≈2.4 × 10<sup>6</sup> m<sup>3</sup> shoreface nourishment on the Aveiro coast (Costa Nova—Ílhavo), the largest until now in Portugal, focusing on its morphological development, impacts on adjacent beaches due to alongshore spreading and cross-shore redistribution, and contribution to the sediment budget of the nourished sediment cell. The analyses are based on high-resolution coastal monitoring data, provided by the Portuguese COaStal MOnitoring Program (COSMO). A Multiple Monitoring Cell (MMC) approach was used to evaluate local and feeder efficiency of the nourishment, sediment budget exchanges within both the placement and wider survey domains (≈1 km<sup>2</sup> and 12 km<sup>2</sup>, respectively). Results show rapid (ca. 6 months) morphological change over the placement area, with a decrease of about 40% of the initial volume. Fast onshore sediment redistribution explains part of this change, placed sand having merged with the pre-existing bar system increased the volume of the shallower nearshore. Longshore transport is reflected by increasing the robustness of the bar downdrift of the placement area and also explains the negative sediment budget (0.75 × 10<sup>6</sup> m<sup>3</sup>) of the survey domain, which corresponds to losses through its southern boundary. Sediment spreading also induced accretion of the subaerial section of Costa Nova beaches in front of the placement area, reversing their long-term erosive trend. In contrast, this trend persisted at downdrift beaches. This suggests that the time lag of the subaerial beach response to this intervention increases with the distance to the placement area, and reversal of the erosive trend will only be noticeable in the following years. This study provides new insights on the time scales of beach response to high-magnitude shoreface interventions in high-energy wave-dominated sandy coasts, which will support decision making regarding similar operations designed to manage erosional hot-spots elsewhere.https://www.mdpi.com/2077-1312/10/2/146wave dominated coastcoastal erosionshoreface nourishmentcross-shore and longshore processescoastal protection strategy |
| spellingShingle | Celso Aleixo Pinto Rui Taborda César Andrade Paulo Baptista Paulo Alves Silva Diogo Mendes Joaquim Pais-Barbosa Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast Journal of Marine Science and Engineering wave dominated coast coastal erosion shoreface nourishment cross-shore and longshore processes coastal protection strategy |
| title | Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast |
| title_full | Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast |
| title_fullStr | Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast |
| title_full_unstemmed | Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast |
| title_short | Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast |
| title_sort | morphological development and behaviour of a shoreface nourishment in the portuguese western coast |
| topic | wave dominated coast coastal erosion shoreface nourishment cross-shore and longshore processes coastal protection strategy |
| url | https://www.mdpi.com/2077-1312/10/2/146 |
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