Role of Sparsely-Glacierized Basins and Groundwater in semiarid Andes Periglacial Headwaters

Role of Sparsely-Glacierized Basins and Groundwater in semiarid Andes Periglacial Headwaters | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL Hydrological Processes This is a preprint and has not been peer reviewed. Data may be preliminary. 30 January 2025 V1 Latest version Share on Role of Sparsely-Glacierized Basins and Groundwater in semiarid Andes Periglacial Headwaters Authors : Rémi Valois 0000-0002-6447-7057 [email protected] , Gonzalo Navarro , Shelley MacDonell 0000-0001-9641-4547 , Solène Buvat , Giulia de Pasquale , Vincent Marc 0000-0002-9474-4857 , Marina Gillon , … Show All … , Esteban Saez Robert , Ayon Garcia , Christopher Ulloa , Julien DUPONT , Milanka BABIC , Eric Sproles 0000-0003-1245-1653 , Jules Burgat , and Etienne Bresciani 0000-0002-6295-2176 Show Fewer Authors Info & Affiliations https://doi.org/10.22541/au.173827422.23852918/v1 Published Hydrological Processes Version of record Peer review timeline 509 views 201 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract A better understanding of headwater hydrogeology in the semi-arid Andes is critical because high-elevation basins are considered water towers for the main valleys, where there is over-allocated water demand. While international literature generally focuses on the glacier contribution to streamflow, there is little information on the contribution of sparsely glacierized basins and the origins and processes of groundwater generation at high elevations. The Corrales catchment in North-Central Chile contains both glacierized and s parsely sub-basins as well as the highest public borehole in the region, making it suitable to fill such scientific gaps. Geophysical surveys and a pumping test were carried out to obtain information on groundwater flows beneath the Tapado terminal rock glacier and a main tributary of the Elqui river. Radioactive and stable isotopes were used to characterize the hydrological connectivity and the water origins of the headwater basins. Low electromagnetic velocities and resistivities reveal the presence of liquid water beneath the rock glacier, which could be the upper limit of a proglacial aquifer. The downstream valley aquifer appears transmissive and dominated by old waters (several decades) that are a mix of high-glacierized and low-glacierized basins. Additionally, stable isotopes indicate different signatures for high- and low-glacierized basins, which could result from isotope fractionation. These results indicate that water isotopes could be used to discriminate waters originating from high-glacierized and low-glacierized basins. The study identifies also the presence of old waters in the low-glacierized basins, which indicates long term storage, slow release or low turnover times. This finding is important for understanding late season baseflow and streamflow evolution in the context of climate change. As the contribution of such basins to total streamflow is significant, a better understanding of hydrological processes in sparsely glacierized regions is required. Role of Sparsely-Glacierized Basins and Groundwater in semiarid Andes Periglacial Headwaters Rémi Valois 1 , Gonzalo Navarro 2,3 , Shelley MacDonell 3,4 , Solène Buvat 5 , Giulia de Pasquale 3 , Vincent Marc 1 , Marina Gillon 1 , Esteban Saez Robert 6 , Ayon Garcia 7 , Christopher Ulloa 7 , Julien Dupont 1 , Milanka Babic 1 , Eric Sproles 8 , Jules Burgat 9 , Etienne Bresciani 10 1 Avignon Université, INRAE, UMR 1114 EMMAH, F-84000, Avignon, France 2 Universidad de La Serena, La Serena, Chile 3 Centro de Estudios Avanzados en Zonas Áridas - CEAZA, La Serena, Chile 4 Waterways Centre, University of Canterbury, Christchurch, New Zealand 5 Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, F-63000 Clermont-Ferrand, France 6 Departamento de Ingeniería Estructural y Geotécnica Santiago, Pontificia Universidad Católica de Chile, Chile 7 Universidad de Atacama, Copiapó, Chile 8 Geospatial Snow, Water, and Ice Resources Lab, Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA 9 RECOVER, INRAE Aix-Marseille Université, 13182 Aix-en-Provence, France 10 Instituto de Ciencias de la Ingeniería, Universidad de O’Higgins, Rancagua, Chile Corresponding Author : Avignon Université, INRAE, UMR 1114 EMMAH, F-84000, Avignon, France, France. [email protected] Abstract (up to 300 words) A better understanding of headwater hydrogeology in the semi-arid Andes is critical because high-elevation basins are considered water towers for the main valleys, where there is over-allocated water demand. While international literature generally focuses on the glacier contribution to streamflow, there is little information on the contribution of sparsely glacierized basins and the origins and processes of groundwater generation at high elevations. The Corrales catchment in North-Central Chile contains both glacierized and sparsely sub-basins as well as the highest public borehole in the region, making it suitable to fill such scientific gaps. Geophysical surveys and a pumping test were carried out to obtain information on groundwater flows beneath the Tapado terminal rock glacier and a main tributary of the Elqui river. Radioactive and stable isotopes were used to characterize the hydrological connectivity and the water origins of the headwater basins. Low electromagnetic velocities and resistivities reveal the presence of liquid water beneath the rock glacier, which could be the upper limit of a proglacial aquifer. The downstream valley aquifer appears transmissive and dominated by old waters (several decades) that are a mix of high-glacierized and low-glacierized basins. Additionally, stable isotopes indicate different signatures for high- and low-glacierized basins, which could result from isotope fractionation. These results indicate that water isotopes could be used to discriminate waters originating from high-glacierized and low-glacierized basins. The study identifies also the presence of old waters in the low-glacierized basins, which indicates long term storage, slow release or low turnover times. This finding is important for understanding late season baseflow and streamflow evolution in the context of climate change. As the contribution of such basins to total streamflow is significant, a better understanding of hydrological processes in sparsely glacierized regions is required. Keywords: proglacial aquifer, Andes, mountain hydrogeology, cryo-hydrogeological systems, and environmental tracers. 1. INTRODUCTION Headwaters in the semiarid Chilean Andes are often considered to be water towers for the downstream socioeconomical needs because they provide an important water contribution from the cryosphere (Navarro et al., 2023a). While the annual streamflow volume is mainly driven by the seasonal snowmelt (i.e., snowfall that almost completely melts during the following summer (e.g., Favier et al., 2009; Ayala et al., 2023)), glaciers and rock glaciers are often considered significant sources of water for maintaining baseflow during low-flow periods (Gascoin et al., 2011; Ragettli et al., 2014; Schaffer et al., 2019). Their contribution is crucial considering the high interannual precipitation variability in the region (Valois et al., 2020a), and the decreasing annual precipitation, accumulated snowpack and the stored volume in reservoirs since 2010 as consequences of an ongoing Megadrought in Central Chile (Garreaud et al., 2017; 2020). This megadrought has been the longest dry period over the last centuries with large precipitation deficits. Projections of future climate scenarios show a reduced capacity to meet future water demand during the peak irrigation season (from December to March) (Hublart et al. 2013), earlier peak runoff (Yáñez San Francisco et al., 2023) and the loss of permafrost in high catchments, although the hydrological implications of such changes are poorly understood (Rogger et al., 2017). Consequently, mountain water resources are expected to be severely affected by these trends, threatening not only water storage but also water generation and water routing in its early stages in the headwater catchment areas. In this context, research in the semiarid Andes have mainly focused on the cryospheric contribution to runoff, focusing on glacier processes and how the accumulation of seasonal snow contributes to the wider catchment runoff (Ayala et al., 2016; Ragettli et al., 2014). Consequently, other hydrological processes and the importance of basins with a low percentage of its total area occupied by (rock) glaciers and perennial snow have been scarcely studied, leaving a gap of information regarding groundwater and low-glacierized basin (here defined as a basin where glacier area is <2% of total area). As such, a better understanding of the hydrogeological functioning of Andean headwaters is needed, especially with regard to hydrological connections between different headwaters units (e.g., Navarro et al., 2023a). Recent research has shown that periglacial groundwater discharge in the Andes can be a significant contributor for streams during the driest months (e.g., Crespo et al., 2020; Reato et al., 2023, Ruiz Pereira et al., 2023). Despite the fact that conceptual models of glacier systems often include a groundwater component with subglacial and proglacial aquifers (Vincent et al., 2017; 2019), direct characterizations of the structure and functioning of such aquifers are scarce worldwide. These proglacial aquifers have been observed to be recharged from glacial and snow meltwater, precipitation and frozen-ground sources, whose contributions vary annually and seasonally (Williams et al., 2006; Ruiz Pereira et al., 2023). However, their potential role in connecting waters from cryosphere reserves to lowlands is still poorly unknown. For instance, it has been recognized that meltwater contributes a considerable percentage to the recharge of some springs in the Cascade Mountains (U.S), Livingston and Lewis ranges (U.S.) (Miller et al., 2021), as well as in the Nevado Coporuna (Peruvian Andes) (Olson et al., 2024). However, there remains a poor understanding of the contribution from basins with scant to absence of debris-free glacial occupation. The present study focus on the Corrales catchment, on the headwaters of the Equi River basin, in the semiarid Chilean Andes (30°S), to characterize the hydrogeological structure (depth and extension) and function of its proglacial aquifer, as well as to better understand the importance of low-glacierized basins for supplying water to the main stream in semiarid regions. We will address the following research questions: do groundwater flows play a significant role in headwater periglacial basins? What is the structure and function of headwater aquifers? Are rock glaciers connected to groundwater systems? Do low-glacierized watersheds play a significant role in late-season baseflow? Can isotopes help to differentiate water origin between ice and seasonal snow? The diversity of landform abundance in the different sub-basins that compose the Corrales catchment makes it an ideal site for understanding meltwater sources and pathways, as well as to better assess the role of proglacial aquifers in transferring flows to lowlands in semiarid catchments. A combination of hydrogeological methods was carried out to answer the scientific objectives. Hydrogeophysical methods were used in combination with pumping tests and groundwater level monitoring to characterize the proglacial aquifer and groundwater flows, while hydrochemical analysis (radiogenic and stable water isotopes) was employed to gain information on the dynamics of the hydrogeological headwater system. We expect that our results will elucidate the dynamics of periglacial groundwater routing and sources in the semiarid Andes and other arid or semiarid regions around the world. 2. MATERIALS AND METHODS 2.1 Study site The study focuses on the Corrales catchment, a 79 km 2 catchment located in the headwaters of the Elqui River (~30°S; 4000-5500 m asl), in the Chilean Andes (Fig. 1b), with tundra climate at high elevation (Sarricolea et al., 2016). Five main sub-basins are identified in this catchment (named B1-5, Fig. 1c), from where streamflow emerges to feed the Colorado River. The latter river supplies the La Laguna reservoir (3130 m asl, 37.8 Mm 3 ), constructed to support water supply for human and industrial use in the region. The Corrales catchment has a 5.5% glacierized area, including only two glaciers (1.9 km 2 ), 15 rock glaciers (2.3 km 2 total area), small glacierets, and some perennial snow patches (DGA, 2022). The geomorphology of the area is dominated by periglacial and proglacial processes and landforms, along with subordinate fluvial processes in the valley bottom and gravitational processes in the hillslopes (Velásquez et al., 2021). The (peri)glacial landforms are unevenly distributed in the different sub-basins that compose the Corrales catchment. Sub-basin B1 is highly glacierized (28.7%), which includes Tapado glacier complex, that comprises the largest clean-ice glacier in the region. The Tapado glacier (0.93 km 2 in 2020, Robson et al., 2022) is connected to a debris-covered glacier and rock glaciers (Monnier et al., 2014; Vivero et al., 2021). Sub-basin B2 is the second most glacierized basin (7.1%), which includes a series of rock glaciers and the second largest clean-ice glacier of the catchment; whereas the three remaining basins (B3 to B5) have only a minimum area covered by small (rock) glaciers and perennial snow patches (<1.1%, Fig. 1). There is no evidence of past glaciers in B4 and B5, whereas sub-basin B3 has Pleistocene proglacial moraine deposits (Velásquez et al., 2021), which could indicate the previous presence of glaciers in the sector. According to Velásquez et al. (2021), the area is composed by pyroclastic rocks and breccias, tuffites and subordinate sedimentary rocks. There are also glacial formations with unconsolidated deposits on the proglacial area, that are poorly sorted with sub-angular debris. Hydrogeological information at the outlet of the Corrales catchment can be derived from the highest public borehole in the region (BH, at approximately 3973 m asl, yellow cross in Fig. 1c). The borehole is located 15 m away from the Colorado River, along which peat and grass can grow (Fig. 2); such peatlands are common in the high Andes and constitute biodiversity hotspots (Valois et al., 2021; Navarro et al., 2023a). The well was drilled in February 2016 up to a depth of 30 m without reaching the underlying bedrock. Lithological information is provided in Section 3.1. The annual streamflow volume is mainly derived from the snow cover that almost entirely melts each year (Favier et al, 2009). Precipitation falls predominantly as snow during the winter months and is primarily sourced from humid air masses from the Pacific Ocean (Scaff et al., 2017). Precipitation shows a very high interannual variability, with annual amounts ranging from less than 20 mm (13 mm in 2019 at the La Serena station at sea level, https://camels.cr2.cl/, last accessed 02/12/2024) to more than 150 mm (177 mm in 2017 at the La Serena station at sea level). Snow sublimation is the dominant snow ablation component in this area, representing between 30 and 90% of total ablation (Réveillet et al., 2020; Voordendag et al., 2021; Ayala et al., 2023). This process also controls the existence of snowmelt hotspots due to the reduction of snow available for melting (Ayala et al., 2023). Some summer precipitation occurs, mainly as snowfall, due to local convective thunderstorms as an effect of intense surface heating by solar radiation (Aceituno, 1997) or a south-easterly mode of the Bolivian High (Jara et al., 2020). There is however a significant runoff contribution from glaciers and rock glaciers during the end of summer and drought periods, supporting baseflow when the snowpack has completely melted (Gascoin et al., 2011; Schaffer et al., 2019). Figure 1: Study location. a) Annual total precipitation average (mm) between 1979 and 2019, based on the CR2MET high-resolution (0.05 ° × 0.05 °) gridded product v2.5 (Boisier, 2023) b) Location of the Elqui watershed. c) Location of each water sample on the Corrales basin, showing its topography, sub-basins division and cryosphere landforms, according to the national Public Glacier Inventory (Inventario Público de Glaciares; IPG2022v2: DGA, 2022). Discharge measurements were carried out in November 2023. Figure 2: Borehole (BH) location and inferred aquifer boundaries. 2.2 Geophysical methods Electrical Resistivity Tomography (ERT) is a method for estimating the distribution of electrical resistivity in a vertical 2D cross section (Dahlin and Zhou, 2004). The electrical resistivity provides information on the type of rock, water content, structure. A known electrical current is injected in electrode pairs in an array which diffuses the current underground. Other electrode pairs measure the potential difference, so that the apparent resistivity can be computed. Inversion of the raw data enables an assessment of the underground resistivity distribution (Loke and Barker, 1996). We performed ERT profiles on the rock glacier area of the Tapado glacier complex (360 m length) and across the narrow valley (48 m length) at the outlet of the Corrales catchment (Corrales sector) to gain information on aquifer structure. This method has shown good performance in periglacial environments (de Pasquale et al., 2022; Navarro et al., 2023b) and in valleys with peatlands (Valois et al, 2020a, 2021) due to the high contrast between saturated and unsaturated sediments and the marked increase in resistivity at the freezing point (Kirsch, 2006; Hauck and Kneisel, 2008). We employed the Wenner–Schlumberger configuration, using a Syscal Junior switch-48 (IRIS Instruments, France) consisting of two cables using 45 (rock glacier) and 48 (Corrales sector) stainless-electrodes. The detailed procedure for the rock glacier profile is described in Navarro et al. (2023b). The transect on the valley in the Corrales sector consisted of 48 electrodes spaced from 2 to 5 m apart. Wenner–Schlumberger array was chosen because it provides a good trade‐off between sensitivity and signal-to-noise ratio (Valois, 2011). Ground Penetrating Radar (GPR) has proven to be useful for characterizing subsurface characteristics and dynamics associated with freeze-thaw processes and ground ice phenomena in periglacial environments (Annan and Davis, 1976). GPR data were collected for the rock glacier area using a PulseEKKO® PRO DVL system equipped (Sensors & Software Inc., Canada) mounted with a bistatic unshielded antennae of 50 MHz. One common mid-point (CMP) survey was completed on a relatively flat and accessible surface on the rock glacier to assess the electromagnetic velocity distribution with depth. The CMP survey used an initial antenna separation of 2 m, a step size of 0.5 m and a final antenna separation of 41 m (79 traces). The data were processed using EKKO Project v5 (Sensors and Software Inc., Canada). The CMP velocities were interpreted to identify differences in hydrogeological properties with depth, which is dependent on relative water or ice content in the medium (Hauck and Kneisel, 2008). 2.3 Hydrogeological methods 2.3.1. Pumping test We performed a single-well pumping test in BH during April 2022 to determine the hydraulic properties of the aquifer. The well was pumped for six hours at a constant rate of 0.7 l s -1 . Water levels were measured manually with an electric dip meter in the pumping well. Measurements were taken at increasing time intervals during both pumping and recovery phases. The recovery phase was monitored during 14 h, time at which the water level returned to its initial level. The pumping test was interpreted using the AQTESOLV software, which incorporates a wide range of analytical solutions (Duffield, 2007). 2.3.2. Hydrogeological monitoring Groundwater level changes were monitored using a CT2X INW vented probe in BH (Fig. 2). The hourly record starts in October 2017 and ends in May 2020. 2.3.3. Discharge measurements Additionally, salt gauging was carried out to evaluate streamflow discharge in B1 to B5 basins. This method generally works well in highly turbulent flow conditions (e.g., Valois et al., 2017) such as in the high topographic gradient basins in this study. Discharges were measured in November 2023 and April 2024 at the streamflow sampling sites (Fig 1b). 2.4 Isotope sampling and analysis Stable isotopes of water ( 18 O, 2 H) have been extensively used in mountain hydrology because of the large differences in isotope ratios in rainwater according to altitude. For this reason, they generally provide relevant information on water origin (Poage and Chamberlain 2001; Vitvar et al. 2005; Valois et al., 2021). Tritium is a naturally occurring isotope of hydrogen, formed in the atmosphere primarily through cosmic ray interactions or from anthropogenic sources such as nuclear testing. Tritium in precipitation infiltrates into groundwater. As water moves downward through the soil and into deeper aquifers, tritium concentrations can decrease, primarily due to mixing with older water, dilution, and radioactive decay. Thus, tritium (3H) can generally discriminate young waters from older due to its relatively fast radioactive decay (Boronina et al., 2005; Eastoe et al., 2012; Stewart and van Der Raaij, 2022; Desens et el., 2023). However, precipitation tritium activities are approaching levels similar to pre-bomb activities making it difficult to differentiate modern water from bomb-pulse water (components of 60 to 70 year old recharge). In this study, water samples were taken along the different water courses and cryosphere components in the Corrales catchment. Collected waters include snow, snow/ice melt, supraglacial streams, supraglacial lake, groundwater from BH, spring from the Tapado glacier complex and surface water from each sub-basin and the streams resulting from their junction (eight sites in total). Sampling was performed during four different field campaigns (April 2022, December 2022, March-April 2023, November 2023). Water was collected in plastic bottles sealed with Parafilm® and analyzed at the Hydro Lab at Avignon University. Stable water isotope results were normalized to the VSMOW-SLAP scale (Vienna Standard Mean Ocean Water-Standard Light Antarctic Precipitation), using a Picarro L2140-6i spectrometer laser analyser and they are reported as δ 18 O and δ 2 H in per mil vs VSMOW (‰) for oxygen ( 18 O) and hydrogen ( 2 H) isotopes, respectively, with an analytical error of 0,1 ‰. Tritium ( 3 H) measurements were performed using a scintillation counter (Tri-Carb 3180 TR/SL) with a detection limit ranging from 0.5 to 0.8 Tritium Unit (TU) and an analytical error ranging from 0.2 to 0.5 TU. 3. RESULTS 3.1 Aquifer structures The inverted resistivity model (Fig. 3c) for the rock glacier on the Tapado glacier complex shows a shallow sub horizontal low resistivity zone (<10 000 Ωm) of ~7-10 m thick overlying a deep high resistive zone (100 000 Ωm to 527 000 Ωm). It is interpreted as the active layer with meltwater above the mixture of ice lenses and rocks. This resistive zone is traversed vertically by an intermediate resistivity zone (between the abscissas 580 and 610 m in Fig. 3c), which is evidence of vertical pathways of liquid water in the rock glacier. A conductive area is also found beneath the mixture of ice and rocks at the bottom end of the profile, which is interpreted as the presence of liquid water filling the pore space of the debris (Fig. 3c). Additionally, the CMP result from the GPR survey shows a sharp diminution in electromagnetic velocity with time (from about 0.11 to 0.05 m ns -1 , Fig. 3d). The time represents the two-way travel time from the antennas to the reflector at depth (Appendix A1 presents the original radargram on which hyperbolas were fitted). A longer time equates to a greater depth. Such low values (0.05 m ns -1 ) is evidence of a water-saturated zone, according to values found in published literature (Neal, 2004). Thus, both ERT and GPR highlight the presence of liquid water in the deeper part of the rock glacier, which can cause groundwater flows towards sub or proglacial aquifers. More information on the rock glacier internal structure and hydrological implications can be found in Navarro et al. (2023b). The lower-elevation ERT cross section in the narrow valley at the Corrales sector is correlated and calibrated with the information from the borehole stratigraphy recorded during the (air flushing) drilling process. The borehole was drilled up to 30 m depth in glacio-fluvial deposits, without reaching the underlying bedrock. The cuttings showed a heterogeneous granulometry with coarse materials, whereas some fine-grained materials can be found near the surface (Fig. 3b). During drilling, a first water level was found at a depth of 2.69 m, whereas after drilling, the static level stabilized at 5.23 m. This suggests the presence of a shallow aquifer and a deeper aquifer in the coarser material. The shallow aquifer must correspond to peatland level observed on the site. According to the available lithological information, the deeper aquifer is at least 20 m thick. It is worth noting that a constant downward flow of water occurs through the well, inferred from a significant dripping/flowing noise that can be heard when standing above the borehole, interpreted as a consequence of the well connecting the shallow aquifer to the deeper one. The inverted resistivity model for this section shows subhorizontal resistive zones (300 to 2000 Ωm) that are well correlated with dry materials near the surface, followed in depth by a conductive zone (100 to 200 Ωm) that is interpreted as the peatland aquifer presence. The deeper aquifer is associated with slightly higher resistivities (200 to 300 Ωm), likely related to a lower silt and clay content relative to the upper layers. Figure 3: a) Location of surveys in the western area of the Corrales catchment. b) Borehole (BH) stratigraphy and groundwater levels. c) Inverted resistivity tomogram of the rock glacier section (adapted from Navarro et al. (2023b). d) Electromagnetic wave velocity analysis from a common mid-point survey on the rock glacier (adapted from Navarro et al., 2023b). e) Inverted resistivity tomogram of the downstream valley aquifer (Corrales sector). Yellow lines: ERT transects. 3.2 Pumping test and borehole monitoring The drawdown data depict an “S” shape typical of unconfined aquifer responses on a logarithmic plot (Neuman, 1975; Fig. 4). While the early phase (where the slope is steeper) may be influenced by wellbore storage (Mucha et al., 1986), wellbore storage alone cannot explain the observed behavior since the data do not show a unit-slope straight line characteristic of this effect (Bourdet, 2002). Hence, it is concluded that the pumped aquifer (i.e., the deeper aquifer, since the water level in the well stands in the deeper aquifer) is unconfined. Equivalently, it is concluded that the shallow aquifer is perched. Accordingly, the Moench (1997) solution for pumping in unconfined aquifers was employed to model the pumping test. This solution accounts for water release from elastic and phreatic storages, wellbore storage and skin effects. Nonetheless, we fixed the skin factor (S w ) to zero; skin effects are likely small as: no additive was used during drilling; the well was simply developed by pumping until water came out free of sediments (i.e., it was not exuberantly stimulated); and the well is almost never pumped, which rules out the main causes of clogging (Jeong et al., 2018). Other fixed model parameters include: well outer radius (r s ); well casing radius (r c ); downhole equipment radius (r eq ); saturated aquifer thickness (b) (Table 1). Fitting this model to the data yielded a good match (Root Mean Square Error (RMSE)=0.85 cm) but an unrealistic anisotropy ratio (K z /K r =10.1, where K z is the vertical hydraulic conductivity and K r is the horizontal hydraulic conductivity) (Appendix A2). Furthermore, fixing the anisotropy ratio to a more realistic value (K z /K r =0.1) and adjusting the remaining parameters degraded the fit significantly (RMSE=1.25 cm) and yielded an unrealistic storativity ratio (S/S y = 0.76, where S is elastic storativity and S y is specific yield) (Appendix A3). As the pumping well is located in a narrow valley, we then included a no-flow boundary at a 10 m distance (d), which is the approximate distance to the closest valley side where the sediments probably lay against hard rock (Fig. 2). Fitting this model yielded as good a match as the first model (RMSE=0.86 cm) and more realistic parameter values (Fig. 4, Table 1). We also tried to include a second no-flow boundary, parallel to the first one and at a 25 m distance from the well on the opposite side (i.e., the approximate distance to the other valley side, Fig. 2); however, fitting this model yielded a slightly higher RMSE (0.98 cm) and the anisotropy ratio was again unrealistic (K z /K r =13.5) (Appendix A4). We suspect that the widening of the valley towards the northeast (Fig. 2) makes the parallel no-flow boundaries assumption too constraining. We did not include any constant-head boundary that would represent the stream, since the groundwater level is several meters below the stream, implying that the stream is disconnected from the aquifer. Based on the above, the Moench (1997) model with a single no-flow boundary at a 10 m distance was selected to estimate the aquifer parameters (Table 1). Transmissivity (T) was estimated at 2.52 10 -3 m² s -1 . Considering the 25 m aquifer thickness, this means K r =1.01 10 -4 m s -1 , which is a realistic value for poorly sorted sand (Freeze and Cherry, 1979), in agreement with the stratigraphy information (Fig. 3b). K z /K r was estimated at 0.038, a plausible value for sedimentary deposits containing clay (Todd and Mays, 2005). S and S y are estimated at 1.32 10 -4 and 0.2%, respectively, which are at the limit of typical ranges of values (Freeze and Cherry, 1979). Nonetheless, it is important to note that these estimations are not free of uncertainty. In particular, the 95% confidence interval (CI) calculated as part of the automatic curve fitting in AQTESOLV shows that only T is well constrained by the data, whereas the other parameters have more than 100% uncertainty (Table 1). Furthermore, this uncertainty does not account for conceptual uncertainties, and so the true uncertainty is likely larger. Table 1: Parameter values of the retained pumping test model (NA means not applicable). r s 0.0762 NA m No r c 0.0762 NA m No r eq 0.02 NA m No S w 0 NA - No b 25 NA m No T 2.52E-03 [2.13E-03; 2.91E-03] m 2 /s Yes K z /K r 0.038 [0; 0.085] - Yes S 1.32E-04 [0; 2.79E-04] - Yes S y 0.002 [0; 0.00498] - Yes d 10 NA m No Figure 4: Pumping test data (open circles) and adjusted model (continuous line). Groundwater levels were monitored between 2018 and 2022 (Appendix A5) without significant annual or seasonal variation (at about 5.3 m below ground level). Such stable groundwater levels suggest that the aquifer delivers more or less the same amount of water all year along downstream, in addition to having little variation in its stored volume. 3.3 Hydrogeological functioning using isotopes 3.3.1 Stable isotopes The δ 18 O values range from -15.62 to -20.96 ‰ (Table 2), whereas δ 2 H values range from -115.31 to -150.78 ‰. The lowest values are at the highest elevations, which is consistent with high elevation precipitation being depleted in heavy isotopes. There are eleven samples from the B1 basin and only one for the other basins as the B1 basin includes the glacier complex with several distinct water source possibilities, whereas there may be only one or two water emergences from the other basins. In addition to flows form the sub-basins, snow, borehole samples and the outlet of the five basins were sampled. They showed less variation in δ 18 O and δ 2 H than B1 samples. The Local Meteoric Water Line (LMWL) was calculated using 16 isotope samples in 2015 from seven locations from the sea until the upper part of the Elqui river basin (from 185 to 4300 masl; Fig. 5; Valois et al., 2021). It matches the Global Meteoric Water Line (GMWL; Craig; 1961), as well as two local lines in southern areas that include high elevation sampling locations: the Juncal basin from Rodriguez et al. (2016) and the Aconcagua basin from Taucare et al. (2020). The local line of Oyarzun et al. (2014) in the southern low Limari basin is similar to the four previous lines, but with a higher slope. The local line of Spangenberg (2007) from southern Chile (not shown here) is below all sampling points and lines. The two lines in the upper group were calculated at the Elqui coast by Squeo et al (2006) and in the Northern desert of Pampa del Tamarugal by Aravena et al. (1999). Stable water isotopes of the low-glacierized basins streamflow (B3 to B5, Fig. 5) and the snow samples are aligned with the GMWL or the similar LMWL, whereas samples from the high-glacierized basin (B1) are above the GMWL, except for the two supraglacial lakes samples. This offset from the MWLs can be explained by liquid-ice fractionation processes and excess in deuterium (Noor et al., 2023), where partial melting at low rate is related to the kinetic depletion of heavy isotopes of water from melting ice. It can be corroborated with the supraglacial lakes, where the in-situ snow and ice melted entirely so that there is no fractionation. The second-highest glacierized basin (containing clean-ice glacier and rock glacier) (B2) sample seems to be closer to the samples originated from partial ice and snow melt. Thus, it highlights as well a distinct signature of high glacierized basins as compared to low-glacierized basins. Because there are many sampling locations in the B1 basin, stable isotopes exhibit larger variation than the other where only the basin outlet streamflow was sampled. The borehole isotopes (BH) do not show a significant variation with the sampling date. Nonetheless, its location between the GMWL and the high-glacierized samples (B1 and B2) highlights probably a mixing between the low-glacierized and high-glacierized basins. Table 2: Water isotopes for each sample. Colors refer to basin, or type of water. B1 Debrid-free glacier runoff (moraine) -30.1502 -69.9233 4672 07/04/2022 -19.39 -141.05 0 B1 Moraine spring -30.1556 -69.9078 4068 07/04/2022 -16.81 -120.60 2.5 B1 Supraglacial lake -30.1569 -69.9080 4302 06/04/2022 -16.38 -122.15 0 B1 Tapado glacier complex outflow (moraine) -30.1556 -69.9078 4068 21/12/2022 -18.98 -136.09 4.9 B1 Snowmelt near the glacier -30.1502 -69.9233 4672 21/12/2022 -20.13 -144.31 4.2 B1 Supraglacial flow (ice and snowmelt?) -30.1523 -69.9236 4702 21/12/2022 -20.96 -150.78 5.9 B1 Supraglacial flow draining a lake -30.1574 -69.9214 4549 21/12/2022 -18.97 -138.10 6.0 B1 Supraglacial flow in DCG -30.1524 -69.9260 4662 22/03/2023 -17.74 -127.36 0.5 B1 Tapado glacier outflow -30.1508 -69.9236 4650 23/03/2023 -18.67 -134.62 0.9 B1 Supraglacial lake -30.1577 -69.9182 4537 23/03/2023 -15.62 -115.31 3.3 B1 Moraine spring -30.1557 -69.9078 4275 23/03/2023 -17.38 -124.26 3.0 B1 Surface runoff coming from Tapado area -30.1518 -69.8863 4084 21/03/2023 -17.41 -125.43 3.8 B2 Surface runoff from a (rock)glacierised basin -30.1516 -69.8861 4079 21/03/2023 -17.74 -129.56 3.4 B3 Surface runoff near Corrales -30.1551 -69.8713 4043 22/03/2023 -18.11 -137.37 1.4 B4 Surface runoff near Corrales -30.1576 -69.8639 4578 22/03/2023 -17.48 -130.64 3.0 B5 Surface runoff near Corrales -30.1614 -69.8741 3990 13/04/2023 -17.94 -133.85 1.5 BH Borehole in Corrales (Mixing) -30.1616 -69.8763 3967 07/04/2022 -17.78 -131.43 1.2 BH Borehole in Corrales (shallow aquifer) -30.1616 -69.8763 3967 18/01/2023 -17.66 -130.42 2.5 BH Borehole in Corrales (deep aquifer) -30.1616 -69.8763 3967 13/04/2023 -17.74 -131.03 2.0 B1-5 outlet River water in Corrales -30.1618 -69.8764 3965 07/04/2022 -17.28 -127.39 2.0 River water in Corrales -30.1618 -69.8764 3965 21/12/2022 -18.07 -130.70 4.4 River water in Corrales -30.1618 -69.8764 3965 13/04/2023 -17.65 -130.28 2.7 B1 Snow Snow near the Glacier -30.1502 -69.9233 4672 21/12/2022 -17.38 -132.11 8.6 B1 Snow Snow -30.1576 -69.9210 4547 21/12/2022 -17.03 -127.41 6.3 Figure 5: Stable isotopes together with tritium concentration. Circle size is proportional to tritium activity.B1 to B5 outlets correspond to streamflow and BH to groundwater. 3.3.2 Radioactive isotope Seasonal snow shows a significant amount of tritium content (between 6.3 and 8.6 TU, Fig. 5), which are the highest values obtained in this study. It corresponds well to values derived from a regional scale analysis of 3 H in precipitation by Basaldua et al. (2022). Liquid water sampled on the glacier shows significant tritium variations in both time and space. While some samples are below the detection limit (<0.5 or 0.7 TU), others do show some significant tritium amount (5 TU). It can be easily explained by the glacier contribution. A glacier can store water for decades or longer, so that the water sampled in the glacier, streams or boreholes is a mix of older water with more recent ones. There is a seasonal tritium content variation that seems to be linked to snowmelt and precipitation amount (Fig. 6). Tritium activities are the lowest in April 2022 for the glacier flow in B1, the streamflow that collects B1 to B5 and the borehole. It corresponds to the end of the melting season when the 2021 snowpack melted entirely. The percentage of melt water is thus low, and stream flow is dominated by water with larger residence time (groundwater or melting ice) and consequently lower 3 H than snow. At the beginning of the melting season in December 2022, tritium content is the highest in the three locations. This can be explained by a larger fraction of seasonal snowmelt with higher tritium content in the sampled water. The final sampling period is at the end of the melting season in April 2023, which shows lower tritium content than at the beginning of the melting season. Nonetheless, tritium content is still higher than in April 2022, which can be explained by a larger amount of snowmelt because of the higher 2022 precipitation amount (138 mm) than in 2021 (58 mm). Water sampled in B2 and the borehole have a relatively low tritium content (3.4 and 2 TU respectively in March-April 2022). It can be explained by a mix of older water stored in ice and aquifers with more recent water such as seasonal snow. During the same period, B3 and B5 basins have a quite low tritium content (1.5 TU), which was unexpected from basins that do not present evidence of long-term storage, such as ice or slow aquifers. By hypothesizing that the water sampled is not a mix of older water with more recent water, a simple decay model can be applied to assess a mean residence time. Waters with 3 H<1.5 TU should have been recharged before 1995 according to the isotopic composition of precipitation in Basaldua et al. (2022). Tritium-depleted samples (3H < 0.5 TU) are a good indicator of relatively old water and likely contain some component of pre-bomb recharge. Figure 6: Annual cumulative precipitation at La Laguna station (upper part) together with tritium seasonal variation (lower part). B1-5 outlets correspond to streamflow and BH to groundwater. 3.4 Discharge results Discharge during the snowmelt season (June to November) was generally lower than at the end of the summer season (Table 3). Such a result can be explained by a low amount of snowfall in 2023 (Fig. 6) as compared to the average. Snowmelt discharge in November 2023 is therefore lower than melt from glaciers in April 2024, as observed in B1 and B2. The low-glacierized basins (B3 to B5) show less absolute discharge variation between the two surveys, but they contribute for 20 to 30% of the total streamflow. Since we observed that B3 to B5 are dominated by old water, which possibly originated from active layer thaw or glaciarets, we normalized discharge by the sub-basins (Table 3). B3 shows a similar basin-normalized discharge than B1 and B2 in November 2023, whereas B4 and B5 have lower values that could be caused by underground pathways or less ice melt. In April 2024, there is a clear correlation between the normalized discharge and the relative glacier cover area (Fig 7a): i.e. a higher glacier surface area cover corresponds to higher late-summer season discharge. After April 2024, ice melt can explain the rise (2 to 5 times) of B1 and B2 basin-normalized discharge (Fig 7b), while it is more challenging to identify a comparable process for a similar increase in B4 basin-normalized discharges given its low-glacierized area (outlier in Fig 7b). Comparatively, B3 and B5 display a low decrease in basin-normalized discharges between the two gauging periods, which can be explained by a lower snow contribution. There is also a clear correlation between discharge ratio and glacier relative cover area (Fig 7b): i.e. higher glaciated area relates to a higher spring/autumn discharge ratio because of the increasing ice-melt contribution. Table 3: Discharge measurements at the outlets of the sub-basins and basin. The results are normalized by the surface areas of sub-basins. L/s L/s/km² L/s L/s/km² B1 14.1 1.64 68.6 7.97 4.87 28.7 B2 28.7 1.45 63.3 3.21 2.21 7.1 B3 14.4 1.47 11.7 1.19 0.81 1.1 B4 5.4 0.36 15.2 1.00 2.81 0.9 B5 10.7 0.47 8.2 0.36 0.77 0.8 B1-5 106.7 1.40 172 2.26 1.61 5.66 Figure 7: a) April 2024 discharge and b) 2024/2023 discharge ratio in function of the relative area covered by glaciers, glaciarets and perennial snow patches 4. DISCUSSION 4.1 On the Atlantic source precipitation Precipitation from humid air masses could have a distinct origin: from the Pacific or the Atlantic. According to Aravena et al. (1999), the δ18O-depleted values observed in the high-altitude area, the Altiplano, were related to processes that affect the air masses that (i) originated over the Atlantic Ocean, (ii) cross the Amazon Basin (continental effect), (iii) ascended the Andes (altitude effect) and (iv) precipitated (convective effect) in the Altiplano. Even if the humid air masses have a distinct stable isotope signature, Magaritz et al. (1989) showed that the isotopic pattern of the springs in the high Andes of northern Chile is mainly a reflection of the altitude of their recharge areas. In addition, Hoke (2013) indicated that precipitation on the eastern slopes of the Andes at ~33°S, at elevations above 2 km, is largely derived from a westerly, Pacific-source component. For Tapado Glacier, Sinclair and MacDonell (2016) also showed the dominance of Pacific source precipitation and its impact on isotope signatures in accumulated snow. Air masses from the Atlantic source is expected during the Austral summer. Only 10% of the precipitation amount fall in summer at the La Laguna station between 1964 and 2024. For these reasons, we choose to neglect its effects on isotopes composition, even though humid air masses from the Atlantic are not expected to be significantly different in Pacific source tritium activity or unaligned with the GWML. 4.2 On the role of low-glacierized basins The low-glacierized sub-basins (B3 to B5) have a significant discharge (Table 3) when compared to the catchment outlet, which highlights significant flows from low-glacierized areas at the basin scale. The normalized discharge of B3 and B4 (Fig. 8) is much higher than B1 or B2, which suggests hidden ice reserves or transfer flows from another basin. The normalized discharge of B5 is more or less the same as B1 or B2, which could indicate there are no hidden ice reserves contributing to runoff. Additionally, those basins (B3, B4, B5) are associated with relatively low tritium values (Fig. 8), which indicates that those waters were recharged decades ago (Basaldua et al., 2022; Ruiz Pereira et al., 2023). Snow samples (5.3 to 8.6 TU) are in agreement with the precipitation tritium measured in Basaldua et al. (2022) and Ruiz Pereira et al. (2023) (7.1 in the first study, 4.51 and 8.21 TU in the second one, respectively). Thus, it appears that these low-glacierized basins are not only impacted by the seasonal snowmelt but also by older waters. While inter-basin flow from the glacierized basins (B1 and B2) could seem possible, stable isotopes samples do not support this hypothesis. Stable isotopes from B3-B5 are indeed aligned with the GMWL (Fig. 5), whereas those from B1-B2 are higher. Thus, the older water presence may be explained by other processes such as storage in permafrost or aquifers. Talus slope permafrost or slow aquifers can indeed act as buffers that delay water flows downstream. Because of past glacial processes and a steep topography, Andean headwater basins are often characterized by large amounts of sediments, such as talus slopes and various types of tills. These landforms influence runoff generation because of their buffering capacity (Clow et al., 2003; Liu et al., 2004; McClymont et al., 2010). Snowmelt flows through the subsurface before entering a stream (Campbell et al., 1995; Sueker et al., 2000). In that case, permafrost processes (such as active layer development) may indeed influence storage and subsurface pathways and consequently the basin streamflow response (Koch et al., 2013), with rock glaciers playing a key role in enhancing vertical water pathways (Navarro et al., 2023b). The low-glacierized basins play a significant role in maintaining interannual baseflow levels with little seasonal snowmelt contribution. It means that there are unknown reserves that shall be assessed in order to predict streamflow evolution under climate change. Thus, studies that aim at better understanding headwaters hydrology or predicting streamflow should include not only highly-glacierized basins, but also basins that do not include large, debris-free glaciers. 4.3 On the role of aquifers in mountainous periglacial headwaters Geophysics revealed the presence of liquid water beneath the terminus of the Tapado rock glacier in sub-basin B1 (Fig. 3). Such water is likely connected to a subglacial or proglacial aquifer that drains the water that percolates to the deeper part of the rock glacier (Fig. 8). This aquifer may be connected to lower aquifers such as in the downstream valley, but efforts (ERT, Time-Domain Electromagnetics) to detect these connections were unsuccessful. Even though groundwater discharge is very difficult to assess in that kind of environment, efforts should be made because this hidden discharge may be on the same order as surface flow (Jones, 1953; Vincent et al., 2017) originating from the glacier. In the lower part of the headwater basins, the borehole intercepts a perched aquifer in the peatland and an unconfined aquifer beneath it made of fluvioglacial deposits. Assuming a hydraulic gradient equal to the topographic gradient (4%) to get a rough estimate of the flow rate from Darcy’s law (using the estimated transmissivity of 1 10 -3 m²/s, aquifer width of 35 m), groundwater flow in the Corrales sector would be equal to 1.3 l/s, i.e., about 1.5% of surface water flow at the same location in November 2023. Although this is nearly two orders of magnitude smaller, groundwater flow is likely to be constant throughout the year, as indicated by the consistent groundwater levels (Appendix A.2). In addition, groundwater flows may not be limited by the arbitrary aquifer width and thickness defined here. Deeper and lateral pathways could of course increase the groundwater contribution to downstream resources. Radioactive isotopes show that the deeper aquifer does present some seasonal variations, with more recent water at the beginning of the melting season, but with less absolute variation than the surface flows (Fig. 6). The groundwater sample with the lowest tritium level (1.2 TU) indicates that some of the water was recharged before 1990. This reveals long term storage which can be caused by a combination of permafrost change, glacier and slow groundwater velocity. The stable isotopes at three different periods do not present large variations. The borehole measurements in the Corrales sector could correspond to a mix of the five sub-basins outlets. Because of its position slightly away from the GMWL, it should correspond at least to a mix of a high-glacierized basin (B1 or B2) that is significantly different from the GMWL and a low-glacierized basin (B3, B4 or B5) that is aligned. Thus, the aquifer is likely recharged by both the high- and low-glacierized basins. The groundwater should be composed by a small portion of seasonal snowmelt that infiltrates rapidly through the ground with slower flows from glaciers and permafrost meltwater or deeper flow through the basement. The aquifer contributes to downstream flow, either with seepage towards the stream or towards downstream aquifers. There is little information on headwater aquifers and how they can buffer flows in a changing climate (Hughes et al, 2011; Foster et al., 2017; Wolf et al., 2023; Halloran et al., 2023). Further information is needed to evaluate the groundwater discharge, how it is impacted by a changing climate, and how it impacts downstream hydrology. Figure 8: Schematic diagram of the hydrogeological functioning. The snowflake represents snow isotopes signatures. The dark circles areas represent the area of the five basins. The blue circles represent glacierized areas. Black numbers are the basin normalized discharges per glacierized covered area in L/s/km² from the April 2024 survey. Brown numbers are the tritium content in TU. Green symbols represent the alignment of stable isotopes with respect to the GMWL. 5. CONCLUSIONS Aquifer structures and groundwater flow information were obtained using geophysics and isotopes at the front of the glacier and in the valley that collects all flows from the periglacial area. Evidence of water beneath the deep and terminal sector of a rock glacier that may flow towards a proglacial aquifer were derived from GPR and ERT. The lower valley that collects fluxes from the five studied sub-basins is composed of a perched aquifer overlying an unconfined aquifer that has fairly high transmissivity and storativity according to the stratigraphy and pumping test. The observed seasonal tritium variation of groundwater is correlated with precipitation amount and suggests that groundwater is a mixture of relatively old water with more recent inputs (Fig. 6). Stable isotopes suggest that groundwater is a mixture of water originating from both high-glacierized and low-glacierized basins, which highlights the important role of low-glacierized basins for recharging aquifers. From a methodological perspective, we show that GPR could identify subglacial aquifers using a common mid-point survey. Additionally, stable isotopes highlight a liquid ice fractionation as observed in other studies, which can help discriminate water that originates from glaciers from water that originates from seasonal snow. Tritium activities in all basins and in the borehole are very low, which indicates that some of the water was recharged decades ago. This is evidence of long-term storage or very slow flows in these headwater basins. While long-term storage makes sense in high-glacierized basins, it is more difficult to understand in the low-glacierized basins. It could be explained by very slow groundwater flows, but it is not expected in a region with such a high topographic gradient. Another explanation would be a contribution from permafrost thaw, but there is no stable isotope fractionation such as in the high-glacierized basins. Both explanations highlight the role of low-glacierized basins to provide a significant baseflow that was recharged decades ago. Although highly-glacierized basins have been proved to play a significant role in the delivery of water during the late season, further investigations are required to assess the potential contribution of low-glacierized basins in providing significant water fluxes during low-flow periods and how this contribution would change in a changing climate. The processes highlighted in this study: (i) the importance of the low-glacierized basins in providing significant water amount to streamflow, (ii) the relatively old water in both groundwater and low-glacierized basins, (iii) a distinct stable isotope signature for high-glacierized basins, (iv) the presence of liquid water beneath the rock glacier, can be useful to other studies in similar geographical configurations for better modelling or characterizing hydrogeological processes and cryosphere-groundwater interactions. Since headwaters are of primary importance for generating streamflow for downstream uses (Hayashi, 2020) and because recent advances suggest that high mountain groundwater may provide some resilience—at least temporarily—to climate-driven glacier and snowpack recession (Somers and McKenzie, 2020), a better understanding groundwater and streamflow dynamics and origin is crucial for ecological and socio-economical needs. ACKNOWLEDGEMENTS The authors would like to thank the CEAZA Glaciology and Hydrogeology group for logistical and fieldwork support. The study was supported by ECOS-ANID project 210044/C21U02 and ANID-CENTROS REGIONALES R20F0008. Gonzalo Navarro was additionally financially supported by Agencia Nacional de Investigación y Desarrollo (ANID)/scholarship program/Doctorado Nacional/2021-21210918 and Universidad de La Serena. The authors thanks also the two anonymous reviewers who help improving the paper and the graphical abstract. 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APPENDICES (if any) to be printed Figure A1: CMP radargram on the rock glacier in B1 basin (Fig. 2). Figure A2: Pumping test data and adjusted model when all four parameters shown were allowed to change, and without no-flow boundary. Figure A3: Pumping test data and adjusted model when K z /K r was fixed, and without no-flow boundary. Figure A4: Pumping test data and adjusted model when all four parameters shown were allowed to change, and with two parallel no-flow boundaries. Figure A5: Groundwater level at the Corrales borehole (BH). Information & Authors Information Version history V1 Version 1 30 January 2025 Peer review timeline Published Hydrological Processes Version of Record 25 Oct 2025 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Collection Hydrological Processes Keywords andes geophysics hydrology isotopes proglacial aquifer Authors Affiliations Rémi Valois 0000-0002-6447-7057 [email protected] Avignon Universite View all articles by this author Gonzalo Navarro Universidad de La Serena View all articles by this author Shelley MacDonell 0000-0001-9641-4547 Centro de Estudios Avanzados en Zonas Aridas View all articles by this author Solène Buvat Universite Clermont Auvergne Polytech Clermont View all articles by this author Giulia de Pasquale Centro de Estudios Avanzados en Zonas Aridas View all articles by this author Vincent Marc 0000-0002-9474-4857 Avignon Universite View all articles by this author Marina Gillon Avignon Universite View all articles by this author Esteban Saez Robert Pontificia Universidad Catolica de Chile Centro de Bioetica View all articles by this author Ayon Garcia Universidad de Atacama View all articles by this author Christopher Ulloa Universidad de Atacama View all articles by this author Julien DUPONT Avignon Universite View all articles by this author Milanka BABIC Avignon Universite View all articles by this author Eric Sproles 0000-0003-1245-1653 Montana State University Department of Earth Sciences View all articles by this author Jules Burgat Aix-Marseille Universite - Campus d'Aix-en-Provence View all articles by this author Etienne Bresciani 0000-0002-6295-2176 Universidad de O'Higgins Instituto de Ciencias de la Ingenieria View all articles by this author Metrics & Citations Metrics Article Usage 509 views 201 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Rémi Valois, Gonzalo Navarro, Shelley MacDonell, et al. 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