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| Titel |
Calculations of evaporative losses using stable water isotope composition in dry climates |
| VerfasserIn |
Grzegorz Skrzypek, Adam Mydlowski, Shawan Dogramaci, Paul Hedley, John Gibson, Pauline Grierson |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094404
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| Publikation (Nr.) |
 EGU/EGU2014-9812.pdf |
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| Zusammenfassung |
| Evaporative loss from surface waters is a major component of the hydrological cycle in arid
zones, restricting recharge to aquifers and limiting the persistence of surface water bodies.
Calculation of evaporative loss is founded on the so-called Craig-Gordon model (C-G), and
the stable hydrogen and oxygen isotope composition of water can be successfully used to
estimate progressive evaporation. The advantage of this approach is that it does not require
monitoring of water levels, inflow and outflow rates. However, the precision and
reliability of calculations in very hot and dry climates can be compromised by variable
isotope composition of air moisture, which thus needs to be calibrated for C-G model
calculations.
In this study, we tested the range of uncertainty in the estimation of evaporative losses by
cross-validating a simplified stable isotope model with field pan evaporation experiments.
The use of standardized pans (1.2 m diameter, max volume 300 dm3) allowed simulation of
fast evaporation from shallow water bodies in hot and dry climates (mean daily
temperature 29°C and relative humidity between 19 and 26% RH during an 11
day experiment). The stable isotope composition of water in pans changed from
-8.23o(δ18O) and -56o(δ2H) to approximately +6.0o(δ18O) and +2.4o(δ2H),
reflecting evaporative losses of 56% in sun and 53% in shade. The maximum difference
between observed (measured in the field) and calculated evaporative losses was |
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