Karst springs as “natural” pluviometers: Constraints on the isotopic composition of rainfall in the Apennines of central Italy

► Isotopic compositions of karstic springs in central Italy have been reviewed. ► Isotopic gradients of rainfalls for elevations have been evaluated in an Alpine valley. ► Karstic drops have been calculated by using isotopic compositions of springs. ► Isotopic compositions of rainfalls in central Italy have been re-calculated using the isotopic compositions of karstic springs.