Ministry of Energy Yazd Regional Water Corporation.
Calculation of the components of water balance is very important in water resources management. One of the key components of balance is estimation of the amount of water drained by wells, springs and Qanats. Calculation of this parameter is too costly and time-consuming because of the need for field visit and field measurement. In order to solve these problems and to calculate the discharge amount of water resources in short period of time, using remote sensing technology and satellite images can be useful. Accordingly, actual evapotranspiration, the most important component of water-balance equation has been calculated and evaluated using this technology. The scope of the study in this research is the Chahgir plain of Abarkouh where underground water drop has caused many problems in the area. For this purpose, six Landsat 8 satellite images (OLI and TIRS sensors) during the period of June to September (2016) in Julian days 174, 190, 206, 222, 238 and 254 as well as meteorological data of two synoptic stations were used and SEBAL method was applied to estimate actual evapotranspiration. The results of the study and its comparison with the data obtained from smart meters (installed on the wells) with a 7.2 percent error indicates high accuracy of remote sensing data and used methods. Also, the amount of net groundwater extraction is estimated 1.07 million cubic meter (MCM) that comparison by pumping volume data (3.98 MCM), shows low efficiency and high water loss in the case study.