Optimal Location of Groundwater Quality Monitoring Stations Using the Shannon Disorder Index in Dez Basin (Lorestan Province)

Site location is one of the spatial analyzes that has a great impact on reducing the costs incurred and launching various activities. So, this is one of the most important and effective steps in executive projects. Due to economic considerations and reduction of monitoring costs, optimization approaches in this study are to reduce groundwater quality monitoring stations in Dez watershed in Lorestan province. In this regard, using an algorithm based on the principle of maximum Shannon disorder index and based on the pollution index of TH, SAR, EC, SO4, Cl, HCO3, K, Na, Ca, Mg TDS and PH parameters, optimization was done for the available 63 monitoring stations in the statistical period of 1387 to 1396 (2008-2017). First, the average rank of each station in the 10 years data was obtained. Then, appropriates models were proposed for the network Shannon disorder index regarding the number of stations and time. After fitting the best model, the results showed that based on SO4, Cl, HCO3, K, Na, Ca, Mg, PH, TH SAR, TDS and EC parameters, 33, 34, 41, 24, 40, 34 , 30, 43, 33, 33, 41 and 28 stations are sufficient for groundwater in the study area, respectively. Also, among the 12 quality indicators evaluated for groundwater, potassium (K) had the highest value of Shannon disorder index. Therefore, it had the maximum Shannon disorder index and was selected as the superior index. The mean squared error and the mean absolute error value were used to validate the results.