Analyzing the Groundwater Quality Parameters Using Frequency Analysis

Water quality problems are world spread as a result of land use changes and industrial development. Water deficit problems become more severe in result of water quality ignorance. Determining the probability values of water quality parameters for specific return periods could be very helpful in water resources management and conservation in terms of quality. In this research some water quality parameters such as: SO₄^2-, Cl^-, HCO₃-, TDS, TH, SAR, EC, Mg²⁺, Ca²⁺, K⁺ and Na⁺ were selected from 7 wells to study through which the most convenient statistical distribution function was determined for each parameter using EASYFIT software. To reach this aim 9 functions were used and the most suitable function was identified through Kolmogorov-Smirnov test. At the second stage the value of each parameter was determined for 5, 10, 20, 50 and 100 year return periods. Results show that Wake by fits the best for most of parameters although GEV and Gen. Logistic are the second and third functions which best fit to data. Also return period graphs of each parameter in 7 sites show that SO₄^2- follows the steepest slope as well as SAR and Cl^-.