Investigating groundwater level fluctuations via analyzing groundwater hydrograph: a case study of Naqadeh plain in north-west of Iran

摘要

Due to population growth, agriculture development, climate change and droughts, the accurate knowledge of water resources, especially groundwater, and their fluctuations are necessary and inevitable for proper and comprehensive management of water. In this study, using the data of 33 observation wells, we investigated groundwater fluctuations in Naqadeh plain in north-west of Iran during a 15-year statistical period (2001-2015) through analyzing the slope and area under the curve (AUC) of groundwater hydrograph. The results indicated according to the hydrograph of the 15-year time period, the groundwater level has decreased by 2.21 m, indicating an annual average of 15.8 cm. The correlation coefficient between the factors affecting the groundwater level confirmed the direct (R= +0.648) and the inverse (R= — 0.193) relations of precipitation and evaporation with the groundwater level, respectively, with a 2-month delay. The highest and lowest slopes regarding groundwater fluctuations occurred in 2011-2012 and 2013-2014 water years, respectively. Also, the maximum and minimum areas under the hydrograph curve, i.e., consequently, the highest and lowest water content, were related to 2006-2007 and 2011-2012 water years, respectively. The area under the hydrograph curve (the water content of the aquifer of the target area) had a descending trend during the statistical period. The slopes of the rising and recession limbs of the hydrograph curve indicated an ascending trend, and the discharge rate of the aquifer was 2.7 times higher than the recharge rate which calls for an urgent and proper management of aquifer operation in the future.