1. Introduction

Iran, being located in the Middle East, is among the countries with the highest loss of freshwater. During a 7-year period, the Middle East region lost freshwater equal to a volume of 1.44 × 10¹¹ m³ (Voss et al. 2013; NASA Report 2013). In Fig. 1.1 the thick black line with hashed fill shows the area in the Middle East region including Iran with a strong negative trend in total water storage from January 2003 to December 2009 (Voss et al. 2013). According to Voss et al. (2013) water storage in the Middle East region is showing a decline after the beginning of a regional drought in 2007 and following changes in water use. It is mentioned that in a drought situation, farmers and people turn to groundwater use and consequently the majority of the water losses is due to reduction in groundwater availability caused by human activities (NASA Report 2013; Voss et al. 2013). The constant drought in Iran is making the future water supply of the country uncertain. If the current water situation is continued, the country will lose more of its freshwater. As stated by Rahnemaei et al. (2013) there is a high possibility that Iran will run out of suitable sites for dam construction in the near future.