Quantitative analysis of water balance components in Lake Urmia, Iran using remote sensing technology

Accurate quantification of water balance components in large lakes is of great importance in assessing the changes in hydrological components, and subsequent variations in lakes water balance. The water balance of Urmia Lake in northwestern Iran was quantitatively analyzed in the year 2005 using remotely-sensed data (e.g. evapotranspiration and precipitation) and meteorological data. The analysis was based on GIS operations. For this purpose, the estimation of pixel-scaled monthly evapotranspiration (ET) was conducted via the Surface Energy Balance Algorithm for Land (SEBAL) using time series of Moderate Resolution Imaging Spectroradiometer (MODIS) images and meteorological data; precipitation was derived from the monthly Tropical Rainfall Measuring Mission (TRMM) satellite observations; surface runoff was estimated by the empirical formula; and finally, the computations of recharge were carried out using the water balance approach for the winter months where estimation of ET and surface runoff were subtracted from precipitation. Water balance components were quantified for the lake and the lake basin separately. Results showed that the water balance components calculated by remote sensing were in conformity with the reported figures in the literature. According to the results of the water balance method, Urmia Lake was suffering from a negative water balance of 3443 MCM yr(-1). Findings of this study demonstrated the application of the derived satellite data in estimating lake's water balance components in order to improve the accuracy of the lake water budget calculation.