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Depth of Solute Generation Is a Dominant Control on Concentration‐Discharge Relations
Author(s) -
Botter M.,
Li L.,
Hartmann J.,
Burlando P.,
Fatichi S.
Publication year - 2020
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2019wr026695
Subject(s) - dilution , precipitation , environmental science , tracer , nutrient , dissolved organic carbon , hydrology (agriculture) , carbon fibers , relation (database) , scale (ratio) , soil science , atmospheric sciences , chemistry , environmental chemistry , geology , meteorology , thermodynamics , mathematics , computer science , physics , geotechnical engineering , organic chemistry , algorithm , database , composite number , nuclear physics , quantum mechanics
Solutes in rivers often come from multiple sources, notably precipitation (above) and generation from the subsurface (below). The question of which source is more influential in shaping the dynamics of solute concentration cannot be easily addressed due to the general lack of input data. An analysis of solute concentrations and their dependence on discharge across 585 catchments in nine countries leads us to hypothesize that both the timing and the vertical distribution of the solute generation are important drivers of solute export dynamics at the catchment scale. We test this hypothesis running synthetic experiments with a tracer‐aided distributed hydrological model. The results reveal that the depth of solute generation is the most important control of the concentration‐discharge (C‐Q) relation for a number of solutes. Such relation shows that C‐Q patterns of solute export vary from dilution (Ca 2+ , Mg 2+ , K + , Na + , and Cl − ) to weakly enriching (dissolved organic carbon). The timing of the input imposes a signature on temporal dynamics, most evident for nutrients, and adds uncertainty in the exponent of the C‐Q relation.