Origin and residence time of water in the Lima Aquifer
  The 8 million inhabitants of the coast Lima City are supplied with water from Rimac and Chillons rivers and water wells in the Lima aquifer. Historics of Rimac River flow and static level of water level in wells are correlated in order to calculate residence time of water since the aquifer is recharged by Rimac River until water reaches a well located 12 km farther, in Miraflores district near sea. Relative abundances of 2H and 18O are used to identify origins of waters from those wells. 3H and 14C contents, respectively, are used to estimate ages of waters. 
Modesto Montoya and Enoc Mamani
physics.geo-ph