Optimal design of groundwater monitoring networks using gamma test theory

Gamma test theory (GTT) is introduced as a novel method to determine the optimal number and location of groundwater monitoring wells without requiring temporal monitoring data. This method is based on the calculation of a statistic, called gamma, for the data of one monitoring period. The optimal wells are selected such that while they have the lowest gamma value, a further increase in the number of wells does not cause much change in their gamma value. The method was applied to the design of an optimal monitoring network for groundwater electrical conductivity (EC) on Kish Island, Hormozgan Province, Iran. The water EC of 55 wells, selected from 244 existing wells, was measured during one monitoring period on Kish Island and their latitude and longitude were recorded. A groundwater EC monitoring network was optimized using a GTT-based optimization algorithm. Based on the results, to estimate the spatial distribution of groundwater EC on Kish Island with maximum achievable accuracy, it was necessary to monitor at least 110 wells, which were identified. Finally, the water EC of the proposed wells was monitored in three monitoring periods and the proposed network was evaluated in these periods. Results indicated that the proposed wells are also optimum in these periods and the spatial distribution of groundwater EC can be estimated with maximum achievable accuracy using the EC data of the proposed 110 wells. The current study provides a time- and cost-effective method to achieve an efficient groundwater monitoring network especially when there is data limitation.