## 3 Results and Discussion
### Water Resource Instability  
To study the effects of drought on water resources instability, the relationship of the discharge data of four main fountains, including Hashilan, Diabr, Ravansar, and Niloofar, and TRMM precipitation data were investigated. To correspond precipitation with discharge, the information of the nearest point of the TRMM precipitation network to the selected fountains was employed. The results are shown in Figure 10.  
Figure 9: Zonation of drought severity in the study area at 2014.  
Figure 9: \(Cont.\)  
Figure 10 demonstrates the fact that in most years, there was a direct relation between precipitation and discharge of the fountains in the region under study. So that there was consistency between the negative SPI values and the negative normalized fountain discharges, and correspondingly, between the positive SPI values and the positive normalized fountain discharges. Figure 10a shows that in fountain of Hashilan, the drought incidence affected the fountain discharge annually and almost without delay. The SPI values turned negative from 2007 onward, while the negativity of normalized fountain discharges began two years ahead from 2005, contemporaneous with precipitation decrease. Hence, this fountain has a great deal of sensitivity to reduced precipitation. Incidentally, the fountain discharge plummeted as of 2005, which would follow the rate of drought in the next years. Figure 10b guarantees that the discharge sensitivity of Bialbr fountain to the low intensity wetness and droughs (close to normal) was high, which may be related to nonrecharging of the fountain from permanent aquifers. Figure 10c,d shows the direct relationship between Ravasar and Niloofar discharges and annual drought. From 2010 onwards, the changes of normalized fountain discharge were reduced in Ravasar fountain. As for Niloofar fountain, drought duration tremendously influenced  
Figure 10: 12–month SPI versus normalized fountain discharge: (**a**) Hashilan; (**b**) Bialbr; (**c**) Ravasar; (**d**) Niloofar.  
the discharge. Field observations confirm this upon drying of this permanent fountain in recent years. This result agrees with the findings of [PERSON] et al. [30] and those of [PERSON] et al. [31].  
In the selected fountains, the highest value of discharge growth was recorded in 1998, 2002, and 2003. In these years, the medium-to-severe wetness governed the fountains' area, and the annual SPI took on its greatest values. The continual discharge decline from 2008 to 2013 is well noticeable in all the four selected fountains, which is in agreement with the 12-month precipitation SPI. During the study period, the most prevailing drought happened in 2008 and 2009. In these two years, the discharge of the fountains went through a significant decrease. For some of the fountains, such as Niloofar in the center of the study area, the most extreme droughts took place in the years of 2012 and 2013. [PERSON] et al. [30] and [PERSON] et al. [31] alluded to the strike of drought during the years of 2007 to 2013, with reference to its negative effects on fountains as well as water resource instability, having much agreement with the results of the current research.