بررسی تأثیر خشکسالی هواشناسی و هیدرولوژیکی بر ویژگی های کمی و کیفی آب‌های زیرزمینی (مطالعه موردی: دشت مرند)

The studied area in this study is Marand plain with an area equivalent to 517.42 square kilometers in the North West of East Azerbaijan province. In this research, consecutive periods of meteorological and hydrogeological droughts were detected by SWI and SPI drought index at 6 periods (6, 9, 12, 18, 24 and 48 months). For this purpose was used monthly precipitation mean of 7 rain-gauge stations in period (1980-2012), Water quality data of 70 wells and monthly water levels data of 23 piezometers wells in period 2001-2011.Results of SPI index indicated that in the studied area, severe drought has occurred in 2007 year and regional wate/r requirement has not been supplied until the end of the studied years. Also SWI index results is indicator of increased extraction of groundwater for compensate of plain water requirement that have been followed fell about three meters of groundwater. Pearson's correlation between the meteorological drought and groundwater levels is significant at the 1% level of confidence and show influence of groundwater resources with a 5-month delay. Quality of groundwater chemistry based on the electrical conductivity (EC), sodium adsorption ratio (SAR) and chlorine (Cl) showed that Changes in water quality in a wide range of Marand plain has been occurred cause of increasing the area under cultivation and increasing extraction. The results obtained from diagram Wilcox showed that about 44 percent of the area of groundwater Plains is in classes C1S4 to C4S1 and is a salty for agriculture.