Trend Analysis of Groundwater Quantity and Quality Parameters (Case Study: Tuyserkan Plain)

The groundwater level of Tuyserkan plain has dropped by more than 11 meters in the last 22 years. This study surveyed the trend of groundwater quality parameters in the study area using data from 15 observation wells from 2005 to 2016, the trend of groundwater quantity parameters using data from 17 observation wells, and also the trend of rainfall changes using 11 rain gauge stations data from 1993 to 2014 by non-parametric Mannkandal test. For each time series, the trend line slope was calculated using the Sen's slope method. The quality parameters included 13 parameters that were measured twice a year (i.e., during the wet and dry periods). Based on the results, the quality parameters of the plain decreased, and the trend of significant decreasing changes in the water table dropped by an average of 53 cm per year. Moreover, the results of precipitation analysis showed that the average annual precipitation decreased by 3.75 mm.