  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.
