Effect of Drought on Aquifer Quality of Iranshahr Plain Using SPI Index and Schuler Method

Recent droughts have caused a decline in the level of groundwater aquifers, which has affected water quality and usability. The aim of this study was to investigate the effect of drought on groundwater quality in Iranshahr plain aquifer. In this study, drought rates were studied using the statistics of Iranshahr synoptic station during the 30-year statistical period (1987-2017) based on SPI index in DIP software, for 6 to 24 months’ time series. Water quality was studied for 16 piezometer wells and 6 aqueducts during 2005-2017. Also, the top four models of semi-spherical, exponential, linear and Gaussin were evaluated using GS + 5.1 software. Then zoning maps of groundwater quality parameters were prepared using the models detected in ArcGIS 10.4.1. The results showed that during the period 1987-2016, normal drought has been dominated in the plain. Drinking water quality is divided into 4 classes in wet hydrological years (2005-2006) and 5 classes in drought (2016-2017). Good quality in terms of drinking decreased from 7.53 percent to 3.92 percent. Water quality has decreased from east to west of the region and the percentage of suitable and usable classes has decreased.