Sustainability of groundwater resources of weathered and fractured schists in the rural areas of Galicia (Spain)

• Published in: Environmental earth sciences Vol. 81; no. 5
• Main Authors: Samper, Javier, Naves, Acacia, Pisani, Bruno, Dafonte, Jorge, Montenegro, Luis, García-Tomillo, Aitor
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2022; Springer Nature B.V
• Subjects: Aquifer recharge; Aquifers; Biogeosciences; Climate change; Contamination; Discharge; Drought; Earth and Environmental Science; Earth Sciences; Electric contacts; Electrical resistivity; Environmental Science and Engineering; Farms; Geochemistry; Geology; Groundwater; Groundwater data; Groundwater discharge; Groundwater flow; Groundwater levels; Groundwater management; Groundwater pollution; Groundwater quality; Groundwater recharge; Groundwater resources; Groundwater supply; Groundwater table; Hydrogeology; Hydrologic models; Hydrology; Hydrology/Water Resources; Original Article; Oscillations; Rain; Rainfall; Rainfall infiltration; Regolith; Rocks; Rural areas; Schist; Schists; Seepage; Shallow water; Slurries; Sustainability; Terrestrial Pollution; Tomography; Transmissivity; Valleys; Water balance; Water pollution; Water quality; Water resources; Water springs; Water supply; Water table; Spain; Schists; Climate change; Groundwater pollution; Groundwater resources; Sustainability; Rural water supply; Galicia
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-022-10264-5

Water supply deficits in droughts, groundwater pollution and climate change are the main challenges for the sustainability of groundwater resources from hard-rock aquifers in rural areas of Galicia (Spain). Here, we address the sustainability of groundwater resources of weathered and fractured schists in the rural areas of the Abegondo municipality. The conceptualization of the hydrogeology of the study area includes: (1) The weathered schist (regolith), (2) The decompressed highly fractured schist layer; and (3) An underlying slightly fractured schist. Groundwater flows mostly through the regolith and the highly fractured rock. Rainfall infiltration is the source of aquifer recharge. Groundwater discharges in seepage areas, springs and along creeks and valleys. The water table is generally shallow and shows seasonal oscillations of up to 4 m. The equivalent transmissivity of the regolith and the highly fractured schist ranges from 15 to 35 m 2 /days. The electrical resistivity tomography identifies a shallow water table and attests that the contact of the highly fractured schist and the slightly fractured schist is highly heterogeneous. Groundwater resources were quantified with a hydrological water balance model. The mean annual recharge is about 185 mm. Groundwater recharge at the end of the twenty-first century could decrease from 6 to 10% due to climate change. The decline in groundwater table could aggravate the shortages during droughts. Groundwater quality data show bacteriological and nitrate contamination due to the poor management of the manure in the fields and occasional discharges of slurry from pig and mink farms. Groundwater management and protection actions are proposed to prevent groundwater pollution and achieve a sustainable groundwater supply in the study area.