Preprints
https://doi.org/10.5194/hess-2021-287
https://doi.org/10.5194/hess-2021-287

  04 Jun 2021

04 Jun 2021

Review status: this preprint is currently under review for the journal HESS.

Evidence for high-elevation salar recharge and interbasin groundwater flow in the Western Cordillera of the Peruvian Andes

Odiney Alvarez-Campos1, Elizabeth J. Olson1, Marty D. Frisbee1, Sebastián A. Zuñiga Medina2, José Díaz Rodríguez2, Wendy R. Roque Quispe3, Carol I. Salazar Mamani3, Midhuar R. Arenas Carrión3, Juan Manuel Jara3, Alexander Ccanccapa-Cartagena4,5, Chad T. Jafvert4,6, and Lisa R. Welp1 Odiney Alvarez-Campos et al.
  • 1Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, 47906, USA
  • 2Departamento de Geología, Geofísica y Minas, Universidad Nacional de San Agustín de Arequipa, Arequipa, Perú
  • 3Departamento de Ingeniería Ambiental, Universidad Nacional de San Agustín de Arequipa, Arequipa, Perú
  • 4Lyles School of Civil Engineering, Purdue University, West Lafayette, IN, 47907, USA
  • 5Escuela Profesional de Antropología, Universidad Nacional de San Agustín de Arequipa, Av. Venezuela S/N, 04000, Arequipa, Perú
  • 6Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, Indiana, 47907, USA

Abstract. Improving our understanding of hydrogeological processes on the western flank of the central Andes is critical to communities living in this arid region. Groundwater emerging as springs at low elevations provides water for drinking, agriculture, and baseflow. Some springs also have recreation or religious significance. However, the high elevation sources of recharge and specific groundwater flowpaths that support these springs and convey groundwater to lower elevations in southern Peru remain poorly quantified in this geologically complex environment. The objectives of this study were to identify recharge zones and groundwater flowpaths supporting natural springs east of the city of Arequipa in the volcanic mountain terrain, particularly, the potential for recharge within the high-elevation closed-basin Lagunas Salinas salar. We used geochemical and isotopic tracers in springs, surface waters (rivers and lakes), and precipitation (rain and snow) sampled from March 2019 through February 2020. We obtained monthly samples from six springs, bimonthly samples from four rivers, and various samples from high-elevation springs during the dry season. We analyzed stable water isotopes (δ18O and δ2H) and general chemistry of springs, rivers, local rainfall, and snow from Pichu Pichu volcano. The monthly isotopic composition of spring water was invariable over time, suggesting that the springs receive a stable source of groundwater recharge and are not supported by relatively short groundwater flowpaths. The chemistry of springs in the low- and mid-elevations (2500 to 2900 masl) point towards a mix of recharge from the salar (4300 masl) and mountain-block recharge (MBR) in or above a queñuales forest ecosystem at ~4000 masl on the adjacent Pichu Pichu volcano. Springs at higher elevation closer to the salar and in a region with a high degree of faulting had higher chloride concentrations indicating higher proportions of interbasin groundwater flow from the salar. We conclude that while the salar is a closed basin, surface water from the salar recharges through the lacustrine sediments, mixes with mountain-block groundwater, and is incorporated into the regional groundwater flow system. Groundwater flow in the mountain block and the subsequent interbasin groundwater flow is accommodated through extensive faulting and fracturing. Our findings provide valuable information on the flowpaths and zones of recharge that support low-elevation springs in this arid region. In this study, high-elevation forests and a closed-basin salar are important sources of recharge. These features should be carefully managed to prevent impacts to the down-valley springs and streams.

Odiney Alvarez-Campos et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Referee Comment on hess-2021-287', Anonymous Referee #1, 24 Jun 2021
  • RC2: 'Comment on hess-2021-287', Anonymous Referee #2, 06 Aug 2021

Odiney Alvarez-Campos et al.

Odiney Alvarez-Campos et al.

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Short summary
In this paper we present results of a hydrologic study of groundwater recharge near the city of Arequipa, Peru. There are a number of springs below a high-elevation salar that show some chemical evidence of connectivity to the salar, possibly facilitated by faults in region. These results suggest that this salar is not a strictly terminal lake, but that some interbasin flow exists. In addition, a high-elevation forest ecosystem seems important for groundwater recharge as well.