Predicting oxygen-18 and deuterium over South America: local meteoric water lines for countries and biogeographical regions

Abstract

Stable isotope ratios of rainwater, 2H/1H and 18O/16O, play a crucial role as natural tracers through the various compartments of the hydrological cycle in hydrological studies. Knowing the isotopic signatures of precipitation helps us to interpret water entry into continental hydrological systems, such as basins and aquifers. Spatial predictions of δ18 O and δ2 H in precipitation across South America were performed using multivariate geostatistics supported by remote sensing covariates. This is the first map dedicated to describing countries’ and biogeographical regions’ spatiotemporal isotopic distributions with their local meteoric water lines (LMWLs). R2 from 0.90 to 0.99 were found considering all LMWLs. Modelling errors for historical, May–September, and October–April periods are 2.83, 2.41, and 2.67% for δ2H, and 0.33, 0.37, and 0.41% for δ18O, respectively.