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Estimating Evaporation from Non-Agricultural Areas (Bare Soil and Range Land) in the Lake Urmia Basin

Abdoli, Mohammad | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52386 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tajrishi, Masood; Jalilvand, Ehsan; Haghighi, Erfan
  7. Abstract:
  8. Evaporation is one of the main parameters of the mass transfer from earth to the atmosphere, which annually transfers more than 65 billion cubic meters of water. Worldwide, evaporation consumes 25% of the energy input and plays a key role in restoring 60% of the precipitation to the atmosphere. Small changes in the water budget and evapotranspiration (ET) in arid and semi-arid areas can cause a large change in ecosystem health. Lake Urmia Basin has been taken into huge consideration due to steepest decline in lake level in the last three decades. Estimating evapotranspiration of this basin is important for the study of agricultural water consumption, hydrological modeling, water resources management, and water budget studies and in general, it is important for the lake restoration purposes. There are different methods for Estimating soil evaporation and ET which the energy balance is one of the most common procedure. This method has good accuracy in estimating ET in agricultural and dense vegetated areas; nevertheless, recent studies have shown that estimated ET in sparse vegetated and bare soil areas is higher than effective precipitation and have overestimation. Haghighi et al., 2013 and Haghighi & Or 2015a and b have developed a physical model (HO model) to calculate evaporation from soil surface which, with high precision, eliminates the errors of various models and has been replaced with many of empirical equations. For this reason, in this study, the HO model was used to estimating evaporation in Lake Urmia basin's bare soil and rangeland. Combination of meteorological data and satellite imagery was used to run the model and the obtained soil evaporation was compared with precipitation of basin synoptic stations. The results showed that evaporation in the bare soil and rangeland of basin are between 60 to 80 percent of the annual precipitation and there is a high correlation between the soil evaporation and precipitation. With producing the soil evaporation map, the Lake Urmia basin ET map (obtained from METRIC model) corrected. The long-term soil evaporation was also estimated for 18 years (2000 to 2017) at four stations of Lake Urmia Basin and its trend was investigated. The results showed that despite decreasing precipitation in three stations from the four stations studied, Soil evaporation in all stations had a significant increasing trend indicating climatic variations in order to increase the evaporation potential in the Lake Urmia Basin
  9. Keywords:
  10. Evaporation from Bare Soil and Range Land ; Lake Urmia Watershed ; METRIC Model ; Overestimation

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