TY - JOUR
T1 - Sources and pathways of stream generation in tropical proglacial valleys of the Cordillera Blanca, Peru
AU - Gordon, Ryan P.
AU - Lautz, Laura K.
AU - McKenzie, Jeffrey M.
AU - Mark, Bryan G.
AU - Chavez, Daniel
AU - Baraer, Michel
N1 - Funding Information:
The authors would like to thank Jesús Gomez, the Peruvian National Water Authority, Glaciology and Water Resources Unit (ANA-UGRH), and Huascarán National Park (INRENA) for site access, logistical support, and scientific collaboration; AnneMarie Glose for assistance in the field; and Patrick Burns, Alex Eddy, and Oliver Wigmore for assistance with spatial and geochemical data. Two anonymous reviewers provided constructive comments on an earlier version of this paper. This work was supported by a National Science Foundation Graduate Research Fellowship under Grant No. DGE-0750965 , a CUAHSI Pathfinder Fellowship, a GSA Graduate Student Research Grant, the National Science and Engineering Research Council of Canada , and the National Science Foundation under Grant Nos. EAR-0901480 , EAR-1316429 , EAR-1316432 , and DEB-1010384 .
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/3/1
Y1 - 2015/3/1
N2 - Tropical glaciers supply approximately half of dry-season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows and other proglacial geomorphic features. A better understanding of the hydrogeology of alpine groundwater, including sources, storage zones, and the locations and magnitudes of contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrologic budget, and for our ability to make predictions about future water resources as glaciers retreat. This field study focuses on two high-elevation meadows in valleys of the Cordillera Blanca, in headwaters and mid-valley locations. Tracer measurements of stream and spring discharge and groundwater-surface water exchange were combined with synoptic sampling of water isotopic and geochemical composition in order to characterize and quantify contributions to streamflow from different groundwater reservoirs. At the headwaters site, groundwater supplied approximately half of stream discharge from a small meadow, with most originating in an alluvial fan adjacent to the meadow and little (6%) from the meadow itself; however, at the mid-valley site, where meadows are extensive, local groundwater has a large impact on streamflow and chemistry through large net contributions to discharge and turnover of surface water due to gross exchanges with groundwater. At the mid-valley site, stream discharge increased by 200Ls-1 (18% of average discharge) over 1.2km as it descended a moraine between two meadows. Such valley-crossing moraines, which create significant steps in the down-valley slope, are likely locations of substantial groundwater contribution to streams.
AB - Tropical glaciers supply approximately half of dry-season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows and other proglacial geomorphic features. A better understanding of the hydrogeology of alpine groundwater, including sources, storage zones, and the locations and magnitudes of contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrologic budget, and for our ability to make predictions about future water resources as glaciers retreat. This field study focuses on two high-elevation meadows in valleys of the Cordillera Blanca, in headwaters and mid-valley locations. Tracer measurements of stream and spring discharge and groundwater-surface water exchange were combined with synoptic sampling of water isotopic and geochemical composition in order to characterize and quantify contributions to streamflow from different groundwater reservoirs. At the headwaters site, groundwater supplied approximately half of stream discharge from a small meadow, with most originating in an alluvial fan adjacent to the meadow and little (6%) from the meadow itself; however, at the mid-valley site, where meadows are extensive, local groundwater has a large impact on streamflow and chemistry through large net contributions to discharge and turnover of surface water due to gross exchanges with groundwater. At the mid-valley site, stream discharge increased by 200Ls-1 (18% of average discharge) over 1.2km as it descended a moraine between two meadows. Such valley-crossing moraines, which create significant steps in the down-valley slope, are likely locations of substantial groundwater contribution to streams.
KW - Climate change
KW - Groundwater-surface water interactions
KW - High-elevation (alpine) meadows
KW - Mountain hydrology
KW - Tropical glaciers
KW - Water resources
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U2 - 10.1016/j.jhydrol.2015.01.013
DO - 10.1016/j.jhydrol.2015.01.013
M3 - Article
AN - SCOPUS:84921882822
SN - 0022-1694
VL - 522
SP - 628
EP - 644
JO - Journal of Hydrology
JF - Journal of Hydrology
ER -