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(Comparing Empirical Methods of Evaporation in Hypersaline Lakes Utilizing Energy Balance Method (The Case of Urmia Lake,Iran

Jahanbani, Sima | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45355 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tajrishy, Masoud
  7. Abstract:
  8. Evaporation is the initial process of losing water and heat from the surface of the lake. There are six well-known methods for estimating the evaporation of water from surface water including: the water balance method,the energy balance method, themass transfer methods, the combined mass transfer and energy balance method, the empirical equation and using pan evaporation. In this thesis, evaporation has been calculated with using different equations, in-site observation and remote sensing data. These results also have been compared with the results of the energy balance method. In addition, we have developed modified empirical equations of fresh water evaporation estimation with the determination of salinity effects. The study area of this research was the Urmia lake basin. This comparison is based on the value of the monthly evaporation between 2005 to 2009.
    The mean annual evaporation has been estimated 1085 millimeters by the energy balance method. By considering differences between the other methods and energy balance method, we conclude that Priestly-Taylor and deBruin-Keijman methods ,with the mean annual evaporations of 995 and 1013 millimeters respectively have a higher accuracy comparing with energy balance. Then the values of the monthly evaporation were calculated by modifying the methods with the salinity effects. The mean annual evaporation was achieved at 991 millimeters by the modified energy balance. By investigating the modified methods with the salinate effect, the Priestly-Taylor and deBruin-Keijman methods have the negligible difference with the modified energy balance method with the mean annual evaporation of 990 and 1008 millimeters, and the average of the difference 0.1 and 1 millimeters per month respectively. The Penman-Monteith and Penman-kimberly methods, with the mean annual evaporation of 1588 and 1592 millimeters, respectively, have a big difference with the standard method for calculating of Urimia lake evaporation, hence they cannot be used as reliable methods.
    Finally, recorded data of local weather stations and water surface temperature was used to acquire an equation for estimating the monthly Urmia lake values of evaporation. Sensitivity analysis shows that air temperature and water surface have equal influence on the energy balance equation. In addition, reflected long wave radiation has stronger effect on evaporation among other types of radiation
  9. Keywords:
  10. Urumieh Lake ; Evaporation ; Bowen Ratio Energy Budget Method ; Methods Comparison

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