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| Titel |
Measurement and modelling of evaporation from a coastal wetland in Maputaland, South Africa |
| VerfasserIn |
A. D. Clulow, C. S. Everson, M. G. Mengistu, C. Jarmain, G. P. W. Jewitt, J. S. Price, P.-L. Grundling |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 16, no. 9 ; Nr. 16, no. 9 (2012-09-10), S.3233-3247 |
| Datensatznummer |
250013465
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| Publikation (Nr.) |
 copernicus.org/hess-16-3233-2012.pdf |
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| Zusammenfassung |
The surface renewal (SR) method was used to determine the long-term (12 months)
total evaporation (ET) from the Mfabeni Mire with calibration using
eddy covariance during two window periods of approximately one week each.
The SR method was found to be inexpensive, reliable and with low power
requirements for unattended operation.
Despite maximum ET rates of up to 6.0 mm day−1, the average summer
(October to March) ET was lower (3.2 mm day−1) due to early morning
cloud cover that persisted until nearly midday at times. This reduced the
daily available energy, and the ET was lower than expected despite the
available water and high average wind speeds. In winter (May to September), there was
less cloud cover but the average ET was only 1.8 mm day−1 due to plant
senescence. In general ET was suppressed by the inflow of humid air (low
vapour pressure deficit) and the comparatively low leaf area index of the
wetland vegetation. The accumulated ET over 12 months was 900 mm. Daily ET
estimates were compared to the Priestley-Taylor model results and a
calibration α = 1.0 (R2 = 0.96) was obtained for the site. A
monthly crop factor (Kc) was determined for the standardised FAO-56
Penman-Monteith. However, Kc was variable in some months and should be
used with caution for daily ET modelling.
These results represent not only some of the first long-term measurements
of ET from a wetland in southern Africa, but also one of the few studies of
actual ET in a subtropical peatland in the Southern Hemisphere. The study
provides wetland ecologists and hydrologists with guidelines for the use of
two internationally applied models for the estimation of wetland ET within a
coastal, subtropical environment and shows that wetlands are not necessarily
high water users. |
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