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The Seasonal Origins of Streamwater in Switzerland
Author(s) -
Allen Scott T.,
Freyberg Jana,
Weiler Markus,
Goldsmith Gregory R.,
Kirchner James W.
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl084552
Subject(s) - evapotranspiration , precipitation , streamflow , environmental science , water balance , streams , surface runoff , transpiration , hydrology (agriculture) , climatology , drainage basin , geography , meteorology , geology , ecology , computer network , photosynthesis , botany , cartography , geotechnical engineering , computer science , biology
Quantifying the relative contributions of winter versus summer precipitation to streamflow may be important for understanding water‐resource sensitivity to precipitation variability. Here we compare volume‐weighted mean δ 18 O values in precipitation and streamflow for 12 catchments in Switzerland, to determine whether summer or winter precipitation is overrepresented in streamflow, relative to its proportion of total precipitation. Similarities between precipitation and streamflow weighted‐mean δ 18 O values indicate that roughly equal fractions of summer and winter precipitation supply streams in Switzerland. These results, together with mass conservation, suggest that similar fractions of summer and winter precipitation supply evapotranspiration. These findings contrast with the assumption that because summer precipitation falls when transpiration rates and evaporative demand are high, it should be underrepresented in streamflow and overrepresented in evapotranspiration. This contrast between seasonal water‐balance variations and the partitioning of seasonal precipitation into runoff and evapotranspiration demonstrates substantial interseasonal carryover of precipitation in storages that supply evapotranspiration.