Morphosedimentary and ecosystem evolution at Belharucas beach after a sand nourishment (Algarve, south Portugal)
- 1Instituto Português do Mar e da Atmosfera, Departmento de Geologia e Georecursos Marinhos, Tavira, Portugal (tdrago@ipma.pt)
- 2Instituto Dom Luiz (IDL), Faculdade de Ciências da Universidade de Lisboa , Lisboa, Portugal
- 3Agência Portuguesa do Ambiente, ARH-Algarve, Faro, Portugal
- 4Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Matosinhos, Portugal
- 5Centro de Ciências do Mar e do Ambiente (MARE), Universidade Nova de Lisboa, Caparica, Portugal
- 6Centro de Ciências do Mar (CCMAR), Universidade do Algarve, Faro, Portugal
- 7Departamento de Geologia, Faculdade de Ciências, Universidade Lisboa, Lisboa, Portugal
Beach nourishment is an increasingly recommended solution for reversing the erosion process that affects nowadays the coastal zone. Usually, it is used in emergency situations as a local and short-term solution or as a regional and long-term management strategy.
From April 2017 to November 2019, sediment samples and beach profile data were collected seasonally, before and after a sand nourishment (100.000m3) that increased 30m of width in Belharucas beach (south Portugal, Algarve).
The main objective of the work was to evaluate the nourishment impact in the beach ecosystem, aiming at contributing to seafloor integrity assessment, in the scope of Descriptor 6 of the Marine Strategy Framework Directive.
Methodology included grain size and macrobenthic fauna analyses in two profiles of the nourished area and another one further away, selected as a control area. Each profile was sampled at three intertidal zones: supralittoral (beach berm), mediolittoral (beach face) and infralittoral (low tide terrace). Beach profile data were collected with the main objective of measuring the beach width and evaluate nourishment longevity.
Results show that grain size variability, higher at beach face, is dominated by local energy beach conditions rather than to changes related to the nourishment.
Morphological data shows that beach nourishment had a relatively low longevity as two years after the nourished beach present roughly the same width as priori to nourishment.
While supralittoral samples were defaunated, medio and infralittoral ones exhibited extremely low diversity. Assemblages were dominated by small-size polychaetes, bivalves and isopods. No statistically significant differences were found in assemblage composition regarding pre- and post-sand nourishment, year seasons, tidal zones and control stations.
In conclusion, Belharucas beach exhibited high resilience to the sand nourishment, preserving its morphodynamics and ecosystem conditions.
The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL and through the strategic project UIDB/MAR/04292/2019 - MARE and ECOEXA project (MAR-01.04.02-FEAMP-0016)
How to cite: Drago, T., Teixeira, S., Rosa, M., Tuaty-Guerra, M., Gaudêncio, M. J., Lobo-Arteaga, J., Veronez, A., Taborda, R., and Cascalho, J.: Morphosedimentary and ecosystem evolution at Belharucas beach after a sand nourishment (Algarve, south Portugal), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15838, https://doi.org/10.5194/egusphere-egu21-15838, 2021.
