Sapientia
Repositório Científico da UAlg
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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.
A new management tool to monitor salinity intrusion in the guadiana estuary under average and extreme river discharge conditions
Publication . Martín-Llanes, Guillermo; Garel, Erwan; López-Ruiz, Alejandro
At the Guadiana Estuary (southern Iberia), strong river flow regula-tion and the intensification of droughts pose a significant threat to the freshwater resource due to enhanced saltwater intrusion. To accurately predict the salinity dynamics under various river discharge conditions (i.e., average and extreme), a 3-dimensional idealized model (Delft3D) has been developed, calibrated and val-idated. The overall performances of the model make it a powerful and versatile tool to design and evaluate mitigation management strategies to control salt intru-sion during prolonged periods of low river flow. This paper provides a detailed description of the numerical framework and the validation process, together with examples of the future model applications.
Size-dependent salinity tolerance in juvenile stellate sturgeon (Acipenser stellatus): physiological and histopathological responses
Publication . Pajand, Zabih Ollah; Hosseinnia, Esmaeil; Jafari Pastaki, Naghmeh; Hallajian, Ali; Yousefi, Ayoub; Lebria, Arash; Ashori, Alireza; Abdollahpour, Hamed
We investigated the physiological, endocrine, and histological responses of juvenile stellate sturgeon (Acipenser stellatus) to salinity challenge across four weight classes (0.89 ± 0.21, 2.01 ± 0.32, 4.84 ± 0.39, and 9.07 ± 1.47 g; mean ± S.E.) and four salinity levels (0, 4, 8, and 12 ppt) over acute to chronic exposure (3–624 h). A total of 4800 juveniles were used across four sequential experiments, with 100 ± 5 fish per tank (12 tanks per experiment). A replicated factorial design (three tanks per treatment) enabled robust assessment of ionoregulation, stress response, and tissue integrity. Plasma osmolality increased from approximately 230 to 266 mOsm kg− 1 during early exposure, followed by progressive convergence toward a narrower physiological range (≈251–284 mOsm kg− 1 ) at 624 h, indicating partial osmotic compensation. This adjustment was driven primarily by sodium, which exhibited the strongest salinity- and size-dependent response, confirming its central role in extracellular osmotic regulation. In contrast, potassium displayed pronounced size-dependent dysregulation, with markedly elevated concentrations in fish 3 g maintained values within or near the physiological range. Cortisol dynamics revealed a clear ontogenetic shift in stress responsiveness. Smaller juveniles (3 g) demonstrated more efficient recovery, with the 5–10 g group achieving ~92% recovery by 96 h, compared to only ~45% in the smallest size class. These endocrine patterns were consistent with ionoregulatory performance and further support a size-dependent transition in physiological resilience. Histopathological analysis corroborated systemic findings. Histopathological analysis using a semi-quantitative scoring system (0–4) revealed significant size- and salinity-dependent tissue alterations. Gill tissues showed lamellar fusion, epithelial lifting, hyperplasia, necrosis, and hemorrhage, with more severe lesions in smaller juveniles at intermediate to high salinities. Kidney tissues exhibited glomerular expansion, tubular degeneration and obstruction, congestion, hemorrhage, and hemosiderin deposition, with lesion severity generally decreasing with increasing body size. These histological patterns were consistent with physiological and endocrine responses and reflected greater structural resilience in larger juveniles under salinity stress. Collectively, these integrated responses identify an empirical transition zone at approximately 3 g under the tested conditions, below which juveniles exhibit limited capacity to maintain physiological homeostasis under salinity challenge. Above this threshold, fish display more effective physiological regulation, resulting in better ion balance, lower stress, and improved tissue integrity. Together, these findings provide mechanistic evidence for size-based acclimation protocols, gradual salinity transitions, and optimized release strategies to enhance survival and performance in aquaculture and stock enhancement programs.
A millennium of coastside occupation. Micromorphological insights from the indigenous site of Las Estacas Cave, Tenerife
Publication . García‐Villa, Pedro; Hernández, Cristo M.; Mallol, Carolina
The archaeological site of Las Estacas Cave (NW Tenerife, Canary Islands) preserves some of the earliest human occupations in Tenerife, dating to the 2nd century CE, spanning the entire pre‐European time range up to the 15th century. Using soil micromorphology, this study applies a geoarchaeological approach to reconstruct site formation processes and human activities through the analysis of 12 thin sections from 9 stratigraphic units, covering most of the sequence. The deposit is largely geogenic and consists of autochthonous basalt fragments, detrital volcanic gravel, and aeolian quartz grains from the Sahara Desert in a spongy clayey matrix characteristic of sodic coastal soils. Aridification evidence in the soil is observed from Unit IV onwards, spanning roughly from the 11th to 15th century. Certain stratigraphic Units (VIII, VII, IV, and II) exhibit increased concentrations of microscopic anthropogenic particles and clear evidence of sedimentary reworking due to trampling. The dominance of geogenic sedimentation and sporadic anthropogenic signals implies episodic use of the cave rather than continuous occupation. The results highlight the interplay between natural depositional processes and human activities in shaping the cave's archaeological record. This study demonstrates the value of microstratigraphic, microcontextual approaches for understanding coastal indigenous sites in Tenerife.