Estimating Natural Recharge by Means of Chloride Mass Balance in a Volcanic Aquifer: Northeastern Gran Canaria (Canary Islands, Spain)

Abstract

Abstract:The chloride mass balance method was used to estimate the average diffuse groundwater recharge on northeastern Gran Canaria (Canary Islands), where the largest recharge to the volcanic island aquifer occurs. Rainwater was sampled monthly in ten rainwater collectors to determine the bulk deposition rate of chloride for the 2008-2014 period. Average chloride deposition decreases inwardly from more than 10 g·m . The application of the chloride mass balance method resulted in an estimated average recharge of about 28 hm 3 /year or 92 mm/year (24% of precipitation) in the study area after subtracting chloride loss with surface runoff. The average storm runoff was estimated to be 12 hm 3 /year (9% of precipitation) for the 1980-2014 period. Runoff was sampled during scarce rainy periods, which produce surface water flow. Average recharge varies from less than a few mm/year near the coast up to 270 mm/year in the highlands (about 33% of average rainfall), with a close-to-linear increase inwardly of about 18 mm·year. Recharge rate uncertainty corresponds to an estimated CV of 0.3-0.4 because of the short data series available.

Radon in Groundwater of the Northeastern Gran Canaria Aquifer

“…Finally, the Rd5, Rd12, Rd16, Rd21, Rd24 and Rd28 wells that exploit groundwater below 400 m have a lower concentration of radon. This could suggest that the surrounding area around these wells is dominated by basaltic basic rocks, but these low concentrations could also be attributed to the double pumping system of these wells, so loss of radon gas during the extraction process is possible, although the possible infiltration of surface water must be also considered because these wells are located at higher levels ( Figure 2) where most of the recharge occurs in the area [39].…”

Constraining probabilistic chloride mass-balance recharge estimates using baseflow and remotely sensed evapotranspiration: the Cambrian Limestone Aquifer in northern Australia

“…The chloride concentration of groundwater can generally be measured fairly easily with a high degree of precision but the chloride deposition due to rainfall is far more uncertain (Naranjo et al 2015). There is then more uncertainty introduced through upscaling from the point scale to the regional scale.…”

Simple solutions for steady–state diffuse recharge evaluation in sloping homogeneous unconfined aquifers by means of atmospheric tracers

“…It has been applied under many diverse circumstances. See for example Claasen et al (1986), Dettinger (1989), Edmunds and Gaye (1994), Guan et al (2010), Liu et al (2003); Prych (1998); Sukhija et al (1988); Cook and Herczeg (1999); Alcalá and Custodio (2013;2015), Custodio (2010), Marrero et al, 2015, Naranjo et al, 2015, and the many references in them.…”