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| Titel |
Evaporation suppression from reservoirs using floating covers: Lab scale
wind-tunnel observations and mechanistic model predictions |
| VerfasserIn |
Dani Or, Peter Lehmann, Milad Aminzadeh, Martina Sommer, Hannah Wey, Christiane Krentscher, Hans Wunderli, Daniel Breitenstein |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250147318
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| Publikation (Nr.) |
 EGU/EGU2017-11469.pdf |
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| Zusammenfassung |
| The competition over dwindling fresh water resources is expected to intensify with projected
increase in human population in arid regions, expansion of irrigated land and changes in
climate and drought patterns. The volume of water stored in reservoirs would also
increase to mitigate seasonal shortages due to rainfall variability and to meet irrigation
water needs. By some estimates up to half of the stored water is lost to evaporation,
thereby exacerbating the water scarcity problem. Recently, there is an upsurge in the
use of self-assembling floating covers to suppress evaporation, yet the design and
implementation remain largely empirical. We report a systematic experimental evaluation of
different cover types and external drivers (radiation, wind, wind plus radiation) on
evaporation suppression and energy balance of a 1.4 m2 basin placed in a wind-tunnel.
Surprisingly, evaporation suppression by black and white floating covers (balls and plates)
were similar despite significantly different energy balance regimes over the cover
surfaces. Moreover, the evaporation suppression efficiency was a simple function of the
uncovered area (square root of the uncovered fraction) with linear relations with the
covered area in some cases. The thermally decoupled floating covers offer an efficient
solution to the evaporation suppression with limited influence of the surface energy
balance (water temperature for black and white covers was similar and remained
nearly constant). The results will be linked with a predictive evaporation-energy
balance model and issues of spatial scales and long exposure times will be studied. |
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