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Hydrochemical modeling of Emerald Lake watershed, Sierra Nevada, California: Sensitivity of stream chemistry to changes in fluxes and model parameters
Author(s) -
Wolford Ross A.,
Bales Roger C.
Publication year - 1996
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1996.41.5.0947
Subject(s) - snowmelt , environmental science , hydrology (agriculture) , snowpack , watershed , surface runoff , snow , precipitation , drainage basin , geology , ecology , geography , geomorphology , geotechnical engineering , cartography , machine learning , meteorology , computer science , biology
We applied a detailed hydrochemical model of watershed processes to assess the response of the Emerald Lake watershed in the southern Sierra Nevada to changes in inputs of water, chemicals, and energy and to changes in model parameters. Observations during the 1986 and 1987 water‐years were used as base conditions. In 1986 snowfall in the Sierra Nevada was well above average, although chemical fluxes were lower than in 1987, which was a low‐accumulation year. The chemical composition of stream water during the early part of snowmelt was sensitive to chemical loading in the snowpack and to snowmelt rate, both of which are subject to year‐to‐year natural variations and to anthropogenic perturbations. Stream‐water chemical composition was also sensitive to uncertainties in the model, including rate of chemical release from the snowpack, nitrogen reactions, and flow routing in the catchment. The largest effects were limited to a period lasting up to a few days, coinciding with the ionic pulse in spring snowmelt. Some significant effects were also apparent during summer rains. Stream waters in late summer and fall were also affected by a faster snowmelt rate, primarily associated with soil drying and lower late‐season streamflows. Overall, the analysis suggests that the Emerald Lake basin may be particularly sensitive to acidic loadings in precipitation and to faster snowmelt and thus earlier runoff associated with climate warming.