Sapientia
Repositório Científico da UAlg
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Sensing short-term adaptive cycles in mesotidal energetic beaches from satellite imagery
Publication . Costas, Susana; Santos, Jacqueline; Doherty, Yarran; Splinter, Kristen D.; Serrão Bon de Sousa, Maria Luísa; Kombiadou, Katerina; Plomaritis, Theocharis; Taborda, Rui
The rapid development of approaches to automatically detect and extract shorelines from satellite imagery is revolutionizing the way we study coastal systems, offering deeper insights into their dynamic responses and adaptive capacities. This study evaluates the performance of the CoastSat toolkit in detect-ing shoreline retreat and recovery at Praia de Faro beach, South Portugal, following storm Emma in March 2018. The mesotidal, low-tide-terrace beach experienced significant erosion, with an average retreat of 20 m. PlanetScope imagery is used to assess shoreline detection accuracy, due to its higher temporal coverage com-pared to other open-access satellite constellations. This includes understanding the correspondence between the detected waterline and two water levels: the tide level and the instantaneous water level (combined effect of wave runup and tide). Linear water level corrections are applied to horizontally translate the detected water levels to a reference elevation that enables temporal comparisons. Results suggest that beach morphology strongly influences optimal correction approaches due to the type of beach response to storms, such as profile rotation. Under non-storm conditions, detected waterlines generally represent astronomic tide levels. While tide-level-based corrections improve accuracy during storms, runup-based corrections consistently outperform under non-storm conditions. Consequently, applying corrections that account for slope changes, runup levels during non-storm conditions, and tide level under storms enables the detection of storm impacts and recovery with an accuracy of approximately 6 m in Praia de Faro. These findings highlight the importance of tailoring detection methodologies to the morphological state of the beach as it evolves over time.
Risk communication by coastal geoscientists
Publication . Matias, Ana; Pinto, Bruno; Carrasco, Rita; Areia, Neide
Storms often harm coastal communities, a situation expected to worsen due to climate change and urban development. Effectively communicating with diverse audiences is thus critical for adapting to and attenuating increased coastal risks. This research focuses on risk communication by Coastal Geoscientists and Engineers, aiming to assess their perspectives and practices. The method used was an online questionnaire, with data collected in 2022–2023. The sample (n = 133) average age was 45, with slightly more men and mostly from Europe. About 95% of participants reported engaging in public communication, and most do coastal risk communication. Direct interaction with audiences such as public talks (74%) is preferred over indirect communication, and 79% had at least one annual contact with a journalist. Participants believe decision-makers should be more informed about risk location, frequency of occurrence, and how to engage citizens with coastal risk. However, this does not align with their top communication subject (coastal physical processes). Some significant differences were found in how gender, professional roles, and scientific backgrounds influence perceptions and priorities in coastal risk communication.
Super typhoon vs. earthquake as driving force of forest succession in a subtropical tectonically active region
Publication . DOI, Ryoichi; Panagopoulos, Thomas
This study compared the effects of super typhoons and earthquakes on forest succession at the slopes of the Rokko Mountains in Japan. According to changes in the enhanced vegetation index (EVI), the super typhoon in 1991 caused severe, widespread damage to topographically distinct forest stands across the mountains. A major earthquake in 1995 with a magnitude of Mj = 7.2 caused moderate effects on the EVI. The 1994 super typhoon and the 1995 major earthquake exhibited similar spatial damage patterns, with impacts concentrated on the northern slopes. Although the 2018 super typhoon recorded higher wind speeds, there was no reduction in forest stands across the mountains, indicating an increase in forest resilience. Nevertheless, detailed observations revealed localized, patchy impacts in 2018, specifically the death of some evergreen trees on the northern slopes. The 1991 typhoon diminished up to 14% (conf. int. 95%: ±3%) of the pre-typhoon EVI values for the most negatively affected forest stands. Hence, the typhoons were thought to be the primary driving force that accelerated the forest succession by eliminating vulnerable trees. This elimination enhanced the increasing dominance of broadleaved evergreen laurel tree species, which are known to have stronger root systems than the vulnerable conifers. In addition, it was revealed for the first time that multiple vegetation types on slopes under the same topographical conditions were commonly damaged by multiple super typhoons within a 27-year period, during which typhoon-enhanced forest succession was strongly pronounced. The findings offer beneficial prospects for proactive climate-resilient forest management and disaster mitigation strategies tailored to slope-specific vulnerabilities. This study is the first to compare the effects of super typhoons and a major earthquake on forest stands.
Challenges in assessing longshore transport along the gulf of cadiz coast: insights from analysis of different wave data sources
Publication . Santos, Jacqueline; Costas, Susana; Taborda, Rui; Garzon, Juan L.; Drago, Teresa
Estimating coastal sediment budgets presents significant challenges due to the complex nature of coastline configurations and the often-bimodal wave regime. This study investigates longshore sediment transport (LST) along the Gulf of Cadiz by analyzing estimates obtained from various wave data sources and employing various approaches. The sensitivity of transport calculations to different wave data sources and approaches is evaluated, and the impact of easterly waves, or “Levante,” is examined for the different approaches. The nearshore wave regime was simulated using the SWAN model, with offshore conditions from ERA5 hindcast and the Faro buoy. Results were validated using observational data and LST was estimated using a deep water approximation of the CERC formula, extracting the net transport and the two components of the sediment transport: west-east and east-west. The results emphasize the critical importance of selecting appropriate forcing for applied models to simulate the nearshore wave regime and estimate sediment transport.
Technical and economic feasibility study of a grid-connected solar power plant in northwest algeria for charging electric vehicles
Publication . Cheikh, Ghizlene; Boutlilis, Fatima; Haba, Cristian-Győző; Bentounes, Hadj Adda; Monteiro, Jânio
The ongoing expansion of electric vehicles requires the development of charging infrastructures, preferentially powered by clean energy sources. This study investigates the optimal design of a hybrid photovoltaic/battery/grid system to supply an electric vehicle charging station in Mesra, Mostaganem province, Algeria. The approach integrates 22 years of high-resolution climate data analysis, the development of a representative charging load profile based on three EV models, and a techno-economic optimization performed with HOMER Pro software. The proposed station is dimensioned to satisfy the expected daily charging load, corresponding to about 97 vehicles per day. Results highlight an optimal configuration combining photovoltaic panels, a battery storage system, and grid backup, ensuring full supply reliability. The energy mix achieves a well-balanced contribution between solar generation, battery storage, and grid electricity. Economic analysis demonstrates strong feasibility, characterized by a highly competitive levelized cost of energy and a reasonable initial investment, confirming the economic attractiveness of the proposed system. From an environmental perspective, the system achieves complete elimination of critical air pollutants and a substantial reduction in CO2 emissions. This research provides both a scalable framework for integrating renewable energy into EV charging infrastructures and a strategic contribution to Algeria’s transition toward a cleaner and more resilient energy mix.