Effects of evaporative enrichment on the stable isotope hydrology of a central Florida (USA) river

    Authors

    P. Gremillion;M. Wanielista

    Comments

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    Abbreviated Journal Title

    Hydrol. Process.

    Keywords

    oxygen stable isotopes; hydrograph separation evaporative enrichment; recession analysis; WATER; O-18; STREAMFLOW; RAINFALL; BASIN; Water Resources

    Abstract

    The delta(18)O characteristics of water masses contributing to flow in the Econlockhatchee River basin, a subtropical low-gradient watershed in central Florida, were monitored to assess the potential for applying hydrograph separation models in the watershed. Daily sampling for a 2-month period in autumn 1992 revealed ranges in precipitation of - 6.64 to - 0.17 parts per thousand, in surficial groundwater of - 3.29 to - 2.90 parts per thousand, and in river water of - 2.68 to - 1.41 parts per thousand. Results indicated that river delta(18)O was consistently more enriched than either groundwater or precipitation by about 1 parts per thousand, prompting the hypothesis that evaporative enrichment significantly altered the delta(18)O of river water. Additional monitoring and mass-balance modelling of the entire basin (620 km(2)) and a subcatchment (70 km(2)) showed that evaporative effects could account for the observed enrichment. Although some enrichment occurred in headwater swamps and wetlands, the field data and modelling results supported the hypothesis that evaporation from the river channel significantly altered the delta(18)O of river water. Enrichment elsewhere in the hydrological cycle, such as during throughfall or temporary storage in wetlands or stormwater management ponds, may have contributed to the observed signal of evaporation, but could not be distinguished from headwater or river evaporation. It appears that a sufficient isotopic signal exists in central Florida precipitation to apply hydrograph separation models, but that evaporative isotopic enrichment should be included as a modelling element. Copyright (C) 2000 John Wiley & Sons, Ltd.

    Journal Title

    Hydrological Processes

    Volume

    14

    Issue/Number

    8

    Publication Date

    1-1-2000

    Document Type

    Article; Proceedings Paper

    Language

    English

    First Page

    1465

    Last Page

    1484

    WOS Identifier

    WOS:000087550400010

    ISSN

    0885-6087

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