Articles | Volume 19, issue 7
Hydrol. Earth Syst. Sci., 19, 3015–3032, 2015
https://doi.org/10.5194/hess-19-3015-2015
Hydrol. Earth Syst. Sci., 19, 3015–3032, 2015
https://doi.org/10.5194/hess-19-3015-2015

Research article 02 Jul 2015

Research article | 02 Jul 2015

Vulnerability of groundwater resources to interaction with river water in a boreal catchment

A. Rautio1, A.-L. Kivimäki2, K. Korkka-Niemi1, M. Nygård3, V.-P. Salonen1, K. Lahti2, and H. Vahtera2 A. Rautio et al.
  • 1Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland
  • 2Water Protection Association of the River Vantaa and Helsinki Region, Helsinki, Finland
  • 3Pöyry Finland Oy, Vantaa Water {&} Environment, Vantaa, Finland

Abstract. A low-altitude aerial infrared (AIR) survey was conducted to identify hydraulic connections between aquifers and rivers and to map spatial surface temperature patterns along boreal rivers. In addition, the stable isotopic compositions (δ18O, δD), dissolved silica (DSi) concentrations and electrical conductivity of water in combination with AIR data were used as tracers to verify the observed groundwater discharge into the river system in a boreal catchment. Based on low temperature anomalies in the AIR survey, around 370 groundwater discharge sites were located along the main river channel and its tributaries (203 km altogether). On the basis of the AIR survey, the longitudinal temperature patterns of the studied rivers differed noticeably. The stable isotopes and DSi composition revealed major differences between the studied rivers. The groundwater discharge locations identified in the proximity of 12 municipal water intake plants during the low-flow seasons should be considered as potential risk areas for water intake plants during flood periods (groundwater quality deterioration due to bank infiltration), and should be taken under consideration in river basin management under changing climatic situations.

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Short summary
Based on low-altitude aerial infrared surveys, around 370 groundwater–surface water interaction sites were located. Longitudinal temperature patterns, stable isotopes and dissolved silica composition of the studied rivers differed. Interaction sites identified in the proximity of 12 municipal water plants during low-flow seasons should be considered as potential risk areas during flood periods and should be taken under consideration in river basin management under changing climatic situations.