INTEGRATED HYDROCHEMICAL MODELING OF AN ALPINE WATERSHED: SIERRA NEVADA, CALIFORNIA
AuthorWolford, Ross A.
AffiliationDepartment of Hydrology & Water Resources, The University of Arizona
KeywordsWatershed management -- Sierra Nevada (Calif. and Nev.) -- Mathematical models.
Acid deposition -- Sierra Nevada (Calif. and Nev.) -- Mathematical models.
Hydrogeology -- Sierra Nevada (Calif. and Nev.) -- Mathematical models.
Water chemistry -- Mathematical models.
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RightsCopyright © Arizona Board of Regents
Collection InformationThis title from the Hydrology & Water Resources Technical Reports collection is made available by the Department of Hydrology & Atmospheric Sciences and the University Libraries, University of Arizona. If you have questions about titles in this collection, please contact email@example.com.
AbstractSeasonally snow covered alpine areas play a larger role in the hydrologic cycle than their area would indicate. Their ecosystems may be sensitive indicators of climatic and atmospheric change. Assessing the hydrologic and bio- geochemical responses of these areas to changes in inputs of water, chemicals and energy should be based on a detailed understanding of watershed processes. This dissertation discusses the development and testing of a model capable of predicting watershed hydrologic and hydrochemical responses to these changes. The model computes integrated water and chemical balances for watersheds with unlimited numbers of terrestrial, stream, and lake subunits, each of which may have a unique, variable snow -covered area. Model capabilities include 1) tracking of chemical inputs from precipitation, dry deposition, snowmelt, mineral weathering, basefiow or flows from areas external to the modeled watershed, and user -defined sources and sinks, 2) tracking water and chemical movements in the canopy, snowpack, soil litter, multiple soil layers, streamflow, between terrestrial subunits (surface and subsurface movement), and within lakes (2 layers), 3) chemical speciation, including free and total soluble species, precipitates, exchange complexes, and acid -neutralizing capacity, 4) nitrogen reactions, 5) a snowmelt optimization procedure capable of exactly matching observed watershed outflows, and 6) modeling riparian areas. Two years of data were available for fitting and comparing observed and modeled output. To the extent possible, model parameters are set based on physical or chemical measurements, leaving only a few fitted parameters. The effects of snowmelt rate, rate of chemical elution from the snowpack, nitrogen reactions, mineral weathering, and flow routing on modeled outputs are examined.
Series/Report no.Technical Reports on Hydrology and Water Resources, No. 92-040
SponsorsSeveral agencies and individuals have supported the modeling efforts presented in this report. Model development was initiated under a Sierra Watershed Modeling Project contract with between the California Air Resources Board (CARB) and the University of Arizona (award no. A732 -035). The author received a multi -year fellowship from the Salt River Project of Arizona, and additional support from the Achievement Rewards for College Scientists (ARCS) Foundation. Completion of the work was supported by a subsequent grant to the University of California, Santa Barbara, awarded under Section 105 of the Water Resources Research Act of 1984, administered by the U.S. Geological Survey (award no. 14 -08- 001- G1888). Partial support was also provided by the National Aeronautics and Space Administration (NASA) under award no. NAGW-2062..
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