Unraveling hydrologic and hydrochemical processes based on long-term concentration–discharge analysis in the Green Lake 4 catchment, Colorado Front Range, USA

Concentration–discharge (C-Q) relationships were analyzed over decadal, annual, and seasonal timescales from water years 1982 to 2020 to understand hydrologic and hydrochemical processes in the Green Lake 4 catchment, Green Lakes Valley, Colorado Front Range. Geogenic solutes, along with the magnitude of stable isotopes, were dominated by a strong (p C-Q power law (C = aQb, where a and b are constants from the curve fitting, with b usually termed the b-coefficient) and consistent patterns over various timescales. The b-coefficients of geogenic solutes were negative, suggesting that those solutes primarily originated from groundwater with higher concentrations and diluted by shallow source waters with lower concentrations (dilution effect). Nutrients other than nitrate were mainly chemostatic without a significant change in their concentrations with an increase in streamflow, indicating temporally variable concentrations in the source waters. The b-coefficients were usually positive for nitrate in the years with a significant C-Q power law (p