Title

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

Authors

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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