Review on groundwater recharge in carbonate aquifers from SW Mediterranean (Betic Cordillera, S Spain)

This paper presents a review of groundwater recharge assessment in some 50 carbonate aquifers of the extreme SW Mediterranean domain (Betic Cordillera, southern Spain), an area highly vulnerable to climate change. The selected aquifers represent a broad range of meteorological and geological conditions, and consequently results can be expanded eastward to other Mediterranean aquifers. The methods most commonly applied for recharge assessment over the past 20 years are aquifer water budget and soil water balance. While these methods support the first steps in groundwater management in Spain, precision in quantification requires other methods to be incorporated. They include chloride mass balance, diverse lumped model codes and empirical methods such as APLIS. In eastern areas of the Betic Cordillera, where semiarid conditions prevail, lumped and distributed models for recharge assessment and calibration are based on the time series of water table data. The mean annual rainfall, recharge and coefficient infiltration (as percentage of rainfall) are, respectively, 648, 262 mm/year and 38 %. A high correlation was observed between annual rainfall and annual recharge in all the studied aquifers. However, the infiltration coefficient can vary substantially even with the same annual rainfall recharge. This reflects significant differences in the degree of surface karstification and the development of the vegetal cover-soil-epikarst system in the carbonate aquifers of the Betic Cordillera. The results of this work may serve to improve the assessment and management of renewable water resources in western Mediterranean carbonate aquifers. The findings are moreover useful for future comparisons involving recharge assessments under different scenarios of climate change and changes in land use.