Testing δ^18 O and δ^2 H isoscapes in the hyperarid Atacama Desert

Stable isotopes have a natural origin whose composition is tied to the hydrological phase shifts of the water cycle. These can provide essential information regarding water sources, ages, travel times and distances, flows, and any physical-chemical influences, such as precipitation, evaporation, and even pollutants when analyzed under a standard isotopic rate. This knowledge is crucial for northern Chile's desert basins, where water is scarce. The concurrently related information can contribute to planning strategies and formulating policies for social, tourism, economic, and sustainable consumer development, among other domains. Following this objective, we elaborated a new database that will be added to the existing scientific information using previously and newly sampled updated data. From this, we generated isoscapes of stable isotopes of oxygen δ18O and deuterium δ2H composition covering the latitudes 17.5°S to 24.5°S of northern Chile. This was achieved by selecting a geostatistical model for the study area, which was accomplished by comparing the interpolation approaches of the conventional ordinary kriging (OK) and the inverse distance weighted (IDW) models. This process revealed which strategy is the most robust method in the context of our study setting. Therefore, while spatially uneven grids in recent studies have shown IDW to be a superior interpolator, the prevailing belief that the OK approach is invariably the most effective maintains its status as the most widely chosen alternative. We performed comparison statistics based on correlation parameters (R), normalized root mean square error (nRMSE), standardized standard deviation (σ) , efficiency coefficient (NSE), Willmot's coefficient (d) and the probability density function plot (pdf). From the above, the IDW interpolator outperforms all the OK approaches investigated here. Interestingly and contrariwise, the IDW's three-dimensional isoscape well depicts the influences of geography, altitude, coastal fronts, Altiplano rainfall, and biases to positive values in some more saline water bodies for both δ18O and δ2H. The elaborated and refined isoscape layers, in addition to the metadata used in this research, are available to the scientific community.