HR: 0800h
AN: H21A-1322    [Abstracts]
TI: Water Resources in a Peruvian Mountain Watershed: Hydrochemical Tracing of Groundwater and Glacier Meltwater Impact on Streamflow
AU: * McKenzie, J M
EM: mckenzie.251@osu.edu
AF: Byrd Polar Reasearch Center, The Ohio State University, Columbus, OH 43210 United States
AU: Mark, B G
EM: mark.9@osu.edu
AF: Department of Geography, The Ohio State University, Columbus, OH 43210 United States
AB: The Callejon de Huaylas, Peru, is a large (~5000 km²; elevation range from ~1800 to 1650 masl) drainage basin for the Rio Santa, which is fed by the glacierized Cordillera Blanca and the non-glacierized Cordillera Negra. The region is well-populated, with extensive agricultural diversity and natural resources, but currently receding glaciers are threatening the future water supply. During the dry season (May to September) glacial melt water from the Cordillera Blanca partially buffers stream-flow, although the magnitude of this effect is not easily measured. We attempt to evaluate the relative contribution of glacier meltwater and groundwater to the regional stream discharge, from 1st order basins to the whole watershed. In July, 2004 and July, 2005 we collected 89 water samples from streams, springs, and groundwater within the Callejon de Huaylas and analyzed for major dissolved ions and the isotopes of oxygen and hydrogen. The water generally has a Ca-Mg-HCO₃ chemical signal, consistent with the regional geology. Preliminary δ¹⁸O and δD values range from -15.6‰ to -4.9‰ and -113‰ to -51.3‰ respectively. Transects of surface water samples from Cordillera Blanca glaciers to the Rio Santa show isotopic enrichment with lower elevation. We sampled 14 groundwater wells and springs, and found the isotopic composition of the water to be isotopically enriched and very similar to surface water within the Cordillera Negra. The Rio Santa is a mixture of Cordillera Blanca and Cordillera Negra surface waters, and the down gradient transect becomes relatively depleted with lower elevation, possibly due to the distribution of glacier mass in the Cordillera Blanca. This research is the beginning of a long term water sampling and monitoring program to identify unique geochemical end-members for quantification of glacier meltwater and groundwater contributions and to assess changes in the hydrologic balance within the Callejon de Huaylas as a result of glacier recession.
DE: 1836 Hydrological cycles and budgets (1218, 1655)
DE: 1860 Streamflow
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
DE: 1884 Water supply
SC: Hydrology [H]
MN: Fall Meeting 2005