A review of the current state of knowledge of proglacial hydrogeology in the Cordillera Blanca, Peru

Abstract

The rapidly melting glaciers of Peru are posing new risks to regional dry season water supplies, and this is evident in the Cordillera Blanca, the mountain range with the world's largest concentration of tropical glaciers. Permanent ice loss is causing reductions to dry season streamflow, which is coupled with shifting demands and control over water access and entitlements in the region. A full evaluation of hydrologic inputs is required to inform future water management in the relative absence of glaciers. Over the last decade, new studies have shown groundwater to be a significant component of the regional water budget during the dry season, and it cannot be ignored when accounting for water quality and quantity downstream of the Cordillera Blanca's alpine catchments. Distinctive common features of the Cordillera Blanca's proglacial catchments are sediment‐filled valleys that were once under proglacial lake conditions. The combination of lake sediments with other alpine depositional features results in storage and interseasonal release of groundwater that comprises up to 80% of the valley's streamflow during the driest months of the year. We summarize the emerging understanding of hydrogeologic processes in proglacial headwater systems of the region's principal river, the Rio Santa, and make suggestions for future research that will more clearly characterize the spatial distribution of stored groundwater within the mountain range. As glaciers continue to recede, differences in aquifer thickness and groundwater residence time between alpine catchments in the region will increasingly control dry season water availability at the local and basin scale. This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water and Environmental Change Engineering Water > Planning Water

A review of groundwater in high mountain environments

“…Hydraulic conductivity of subsurface materials can also control groundwater response to precipitation (Smith et al, 2014) and geomorphic features of high mountain basins can redistribute groundwater recharge. For example, alluvial fan aquifers can channel flow into valley bottom aquifers (Glas et al, 2018; Smerdon et al, 2009; Winter et al, 1999).…”

Groundwater Buffers Decreasing Glacier Melt in an Andean Watershed—But Not Forever

“…Groundwater, previously often ignored in mountain hydrology (Bales et al, 2006;Huss et al, 2008;Juen et al, 2007;Ragettli et al, 2014;Voeckler et al, 2014), is now understood to be a significant contributor to streamflow generation in the Andes Glas et al, 2018;Gordon et al, 2015;Saberi et al, 2019;Somers et al, 2016) and in mountain systems globally (Andermann et al, 2012;Frisbee et al, 2011; ©2019. The Authors.…”

“…Groundwater, previously often ignored in mountain hydrology (Bales et al, ; Huss et al, ; Juen et al, ; Ragettli et al, ; Voeckler et al, ), is now understood to be a significant contributor to streamflow generation in the Andes (Baraer et al, ; Glas et al, ; Gordon et al, ; Saberi et al, ; Somers et al, ) and in mountain systems globally (Andermann et al, ; Frisbee et al, ; Hood & Hayashi, ; Liu et al, ; McClymont et al, ). While groundwater supplies may prove more resilient than snow and glaciers to climate change (Lemieux et al, ; Tague et al, ), our knowledge of future impacts is limited by oversimplification of groundwater processes in hydrological models due computational and/or observational limitations in mountain regions (Juen et al, ; Ragettli et al, ).…”

Half a century of glacier mass balance at Cordilleras Blanca and Huaytapallana, Peruvian Andes

“…Any decreases in the glacial component of discharge will also put increased pressure on other water sources. Decreasing glacial area is projected to result in groundwater forming a larger percentage of dry season discharge (Glas et al, 2018;Vuille et al, 2008aVuille et al, , 2008b which is likely to place greater strain on groundwater reserves. The increased reliance of discharge on precipitation and groundwater will increase the seasonality of discharge regimes and has the potential to increase the risk of drought impacts on a multi-year scale (Baraer et al, 2009;Mackay et al, 2020).…”