Evaporation from Lakes and Reservoirs: Developing a Remote Sensing Algorithm of Reference and Water Surface Energy Balance

Complexity of evaporation process from a water body such as a lake or reservoir and lack of reliable and available data has led to limited developments in this field compared to research on other hydrological components especially where management of these water systems does not rely on more accurate spatial and temporal data. However the operation of reservoirs, development of a new storage, and water accounting strategies require more accurate evaporation estimates especially for drinking water supply in arid area. In this research a new method was developed for evaporation estimation presenting a different solution to the energy balance equation. The proposed approach, called reference and water surface energy balance (RWEB), carried out by defining the reference surface and simultaneously solution to the energy balance equation for both water and reference surfaces. The temperature and net radiation data were used in the proposed method. According to the input data, the RWEB method has the ability for remote sensing application and accordingly the remote sensing algorithm of RWEB was also developed. The method was applied to Doosti Dam Reservoir resulted in the distributed evaporation parameters and estimations