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Hydrogeochemistry, Isotopic Composition and Water Age in the Hydrologic System of a Large Catchment within a Plain Humid Environment (Argentine Pampas): Quequén Grande River, Argentina
Author(s) -
Martínez D. E.,
Quiroz Londoño O. M.,
Solomon D. K.,
Dapeña C.,
Massone H. E.,
Benavente M. A.,
Panarello H. O.
Publication year - 2017
Publication title -
river research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.679
H-Index - 94
eISSN - 1535-1467
pISSN - 1535-1459
DOI - 10.1002/rra.3072
Subject(s) - baseflow , hydrology (agriculture) , streamflow , surface runoff , δ18o , drainage basin , groundwater , environmental science , aquifer , precipitation , stable isotope ratio , geology , geography , ecology , physics , cartography , geotechnical engineering , quantum mechanics , meteorology , biology
The Quequén Grande River (QGR) is a large catchment (10 000 km 2 ) in the Pampa Plain in Argentina. From November 2004 to April 2013, a hydrochemical and stable isotopes monitoring program was conducted, which included three sampling stations of monthly composite precipitation, weekly samples in two sites along the river and several groundwater samples. A standard data interpretation was initially performed applying standard statistics, Piper diagrams and δ 18 O versus δ 2 H diagrams. The time evolution of the values of δ 18 O in precipitation and streamwater were also determined. The integration of hydrogeochemistry and stable isotopes data indicates the existence of three main components of streamflow: (i) baseflow characterized by electrical conductivity (EC) from 1200 to 1800 µs/cm and an isotope composition quite constant around δ 18 O −5.3‰ and δ 2 H −33.8‰. Water age for groundwater contribution is typically around 30 to 40 years using chlorofluorocarbons; (ii) direct runoff composed of channel interception and overland flow, which is of low EC in the order of 50 to 100 µs/cm, and a highly variable isotopic composition; and (iii) translatory flow (pre‐event water that is stored within the subsoil) with an intermediate EC and isotopic composition close to that of the weighted average composition of precipitation. The hydrochemical and stable isotopic data allow the differentiation between baseflow and direct runoff. In addition to this, chlorofluorocarbon dating is a useful tool in assessing the dominance of baseflow in a stream. The data lead to a conceptual model in which an intermediate flow system, with mean residence time (MRT) of around 35 years, discharges into the drainage network. A regional flow system (MRT > 50 years) discharges to the ocean. It is concluded that in this large plain catchment streamflow separation, only two components can be applied in: (i) short storm precipitation events having a high sampling frequency and (ii) during long dry periods when pre‐event soil water is not released. Copyright © 2016 John Wiley & Sons, Ltd.