31 Jan 2023
 | 31 Jan 2023
Status: this preprint is currently under review for the journal HESS.

Spatial distribution and controls of snowmelt runoff in a sublimation-dominated environment in the semiarid Andes of Chile

Álvaro Ayala, Simone Schauwecker, and Shelley MacDonell

Abstract. Sublimation is the main ablation component of snow and ice in the upper areas of the semiarid Andes (~26–32° S and ~69–71° W). This region reaches up to 6000 m, is characterized by scarce precipitation, high solar radiation receipt, and low air humidity, and has been affected since 2010 by a severe drought. In this study, we suggest that most of the snowmelt runoff originates from specific areas with topographic and meteorological features that permit large snow accumulation and sufficient energy for snowmelt. We quantify the spatial distribution of snowmelt runoff and sublimation in a catchment of the semiarid Andes using a process-based snow model that is forced and validated with field data, satellite-derived indices of snow presence and an independent SWE reconstruction product. Results from model simulations over a two-year period reproduce point-scale records of snow depth and SWE and are also in good agreement with distributed patterns obtained from satellite-derived products, such as snow cover area and indices of snow absence and persistence. We estimate that 50 % of snowmelt runoff is produced by 18–28 % of the catchment area, which we define as “snowmelt hotspots”. Snowmelt hotspots are located at elevations between 4200 and 4800 m, have easterly aspects, low slope angles, and high snow accumulation and persistence. We suggest that snowmelt hotspots play a key hydrological role when connecting with other features of dry mountain regions, such as areas of groundwater recharge, rock glaciers and mountain peatlands, and recommend more detailed snow and hydrological monitoring of these sites, especially in the current and projected scenarios of scarce precipitation.

Álvaro Ayala et al.

Status: open (until 28 Mar 2023)

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  • RC1: 'Comment on hess-2023-23', Anonymous Referee #1, 07 Mar 2023 reply
  • RC2: 'Comment on hess-2023-23', Anonymous Referee #2, 15 Mar 2023 reply

Álvaro Ayala et al.

Álvaro Ayala et al.


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Short summary
As the climate of the semiarid Andes is very dry, a large fraction of the seasonal snowpack is lost to the atmosphere as sublimation. We suggest that snowmelt runoff originates from specific areas that we define as snowmelt hotspots. We estimate that snowmelt hotspots produce half of the snowmelt runoff in a small study catchment, but they correspond to about a quarter of the total area. Snowmelt hotspots might be important for groundwater recharge, rock glaciers and mountain peatlands.