Study of Temporal-Spatial Trend of Groundwater Salinity by Hotspot and Outlier Analysis in Miandoab plain

Groundwater as an important part of water resources in arid areas is under influence of human and climatic factors. By illustrating the trend and fluctuation of regional water quality temporarily and spatially, it can be managed more effectively. Traditional methods of point data analysis cannot be used alone with high reliability, therefore the use of GIS, Geostatistical methods, and clustering analysis are suitable ways to analyze regional hydro-climatological phenomena. Normal spatial variability and outlier points can be assessed using the analysis of spatial clusters that divide the data into homogeneous groups and hotspots. These analyses determine in what situations there are valuable high or low clustering effects. In this study, the hot spots of the groundwater salinity of Minadoab plain and the Zarrinehrood network have been investigated. For this purpose, the salinity(Ec) of 32 observation wells located in Zarrinehrood network in the period of 1381 to 1399 has been used. The G* and Moran tests were used to investigate the location of high-value points, hot spot clusters, and significant outlier values. Based on the results obtained from both analyzes, hotspots in the western and northwestern parts of the network have been located. The trend of salinity hot spot areas through time was surveyed by the Man-Kendal test and the results indicate that these areas are increasing in recent years which can be a warning about increasing pollutant levels, drought, and contractile policies for surface water management on the shores of Lake Urmia.