Hydrochemical Evaluation of La Gomera Aquifers (Canary Islands) and its Relationship to Garajonay National Park

Abstract

The hydrogeological model proposed for La Gomera (Canary Islands) suggests the presence of an upper aquifer (perched groundwater bodies), a lower aquifer (General Saturated Zone) and flows through them. Many perched groundwater bodies are located under Garajonay National Park, where most of the springs are found. About 60% of the water supply in La Gomera is covered with spring water. Therefore, if new wells are constructed and the lower and upper aquifers are truly connected, the new extractions could affect the springs of Garajonay. Hydrochemical data and multivariate statistical analyses (PCA and CA) of 120 water analyses performed by Instituto Geologico y Minero de Espana in 1991 show a great chemical variability of groundwater, precluding the identification of springs-groups and hydrochemical patterns, and therefore, transfer areas. Thus, it is not possible to assess the potential impact on the springs of Garajonay National Park. The factors for this hydrochemical heterogeneity could be: (1) heterogeneity of the volcanic materials; (2) influence of marine aerosols; (3) irregular rainfall; and (4) complex hydrogeological system formed by partially disconnected water bodies.