water Article Where Does the Chilean Aconcagua River Come from? Use of Natural Tracers for Water Genesis Characterization in Glacial and Periglacial Environments Sebastián Andrés Crespo 1,* ,Céline Lavergne 2,3 , Francisco Fernandoy 4 , Ariel A. Muñoz 1, Leandro Cara 5 and Simón Olfos-Vargas 1 1 Instituto de Geografía, Facultad de Ciencias del Mar y Geografía, Pontificia Universidad Católica de Valparaíso, Valparaíso 2362807, Chile;
[email protected] (A.A.M.);
[email protected] (S.O.-V.) 2 Laboratory of Aquatic Environmental Research, Centro de Estudios Avanzados, Universidad de Playa Ancha, Viña del Mar 2581782, Chile;
[email protected] 3 HUB Ambiental UPLA, Universidad de Playa Ancha, Valparaíso 234000, Chile 4 Laboratorio de Análisis Isotópico (LAI), Facultad de Ingeniería, Universidad Andrés Bello, Viña del Mar 2531015, Chile;
[email protected] 5 Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA-CONICET), Mendoza 5500, Argentina;
[email protected] * Correspondence:
[email protected] Received: 1 August 2020; Accepted: 12 September 2020; Published: 21 September 2020 Abstract: The Aconcagua river basin (Chile, 32 ◦S) has suffered the effects of the megadrought over the last decade. The severe snowfall deficiency drastically modified the water supply to the catchment headwaters. Despite the recognized snowmelt contribution to the basin, an unknown streamflow buffering effect is produced by glacial, periglacial and groundwater inputs, especially in dry periods. Hence, each type of water source was characterized and quantified for each season, through the combination of stable isotope and ionic analyses as natural water tracers. The δ18O and electric conductivity were identified as the key parameters for the differentiation of each water source.