Methodology for the Study of Unexploited Aquifers with Thermal Waters: Application to the Aquifer of the Alhama de Aragon Hot Springs

Abstract A methodology for the study of thermal waters in unexploited aquifers is proposed. This methodology has been applied to the Alhama Aquifer, which is the origin of the most important thermal springs of the Iberian Peninsula. A conceptual model was made of the aquifer by integrating data such as (1) the geometry at depth (on the basis of deep geophysics) and at the surface (from conventional geological maps); (2) hydrographic analysis of the aquifer discharge; (3) a study of the recharge by classic hydrometeo‐rological methods; and (4) conventional and isotopic hydrochemistry. In addition to the hydraulic regional parameters it provides, the model explains the origin of the Alhama springs in terms of simple circulation at a depth of some 900 m and a normal geothermal gradient (3°C/100 m), with no requirement of contact with a source of heat at the bottom of the aquifer.