Groundwater chemistry in Madeira Island (Portugal): main processes and contribution to the hydrogeological conceptual mo
- PDF / 3,970,822 Bytes
- 19 Pages / 595.276 x 790.866 pts Page_size
- 10 Downloads / 199 Views
ORIGINAL ARTICLE
Groundwater chemistry in Madeira Island (Portugal): main processes and contribution to the hydrogeological conceptual model Ana Luísa Fernandes1 · J. Virgílio Cruz2 · Celso Figueira1 · Susana Prada1,2 Received: 27 September 2019 / Accepted: 25 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Groundwater resources are the main water supply source of Madeira Island, thus the characterization of the main hydrogeological mechanisms is vital for their sustainable management. Through the present study, a large hydrochemical dataset was analyzed by traditional and PCA analysis in light of the conceptual hydrogeological model of the island. Groundwater is mainly characterized by being low mineralized (mean EC = 128.6 µS/cm), cold (mean temperature = 13.4 °C) and slightly acidic (mean pH = 6.7). Springs draining local and small perched aquifer have low solute content and local flow path, while drilled wells, tapped in the basal aquifer near the coast, are more mineralized. Groundwaters are of the Na–HCO3, Mg– HCO3−, Ca–HCO3− and Na–Cl types. The latter is found in some springs and in a few drilled wells. The hydrogeochemical and principal component analysis identify silicate weathering process as the most important factor involved in groundwater mineralization, as also CO2 dissolution and seawater spraying. Based on the 3H levels, most groundwaters have a significant component of modern recharge. Springs correspond to young waters, whilst waters in tunnels/galleries and drilled wells are mixtures of modern and submodern waters. The lower 3H concentration in these waters indicates longer residence time in the aquifers than spring water with higher levels and recent recharge. In general, flow paths are local and shallow. The interpretation of the chemical data in conjunction with 3H and δ18O data is in line with the conceptual model of Madeira Island proposed by Prada et al. (Comun Inst Geol Min 90:125–142, 2003; J Hydrol 536:409–425, 2016). Keywords Volcanic aquifers · Hydrogeochemistry · Groundwater · Hydrogeological conceptual model · Madeira Island
Introduction Groundwater is a critical resource to maintain water supply in many volcanic islands, where besides the natural constrains due to their hydrology setting there is an increasing water demand (Falkland and Custodio 1991a, b). In these islands, groundwater is usually the main water source for human consumption, irrigation, industrial use, and energy production. The same also applies to Madeira, a volcanic island located southwest of the Iberian Peninsula, with about 260.000 inhabitants and visited annually by 1.2 million * Celso Figueira [email protected] 1
Faculdade de Ciências Exatas e da Engenharia da Universidade da Madeira, Campus Universitário da Penteada, Madeira, 9000‑390 Funchal, Portugal
IVAR, Instituto de Investigação em Vulcanologia e Avaliação de Riscos, Universidade dos Açores, Açores, 9501‑801 Ponta Delgada, Portugal
2
tourists, in which groundwater explains the greater part of
Data Loading...
