Assessment of Groundwater Quality of Anamur and Aydıncık Districts of Mersin, Türkiye in Terms of Irrigation Using Geographic Information System

Monitoring groundwater quality is very important in coastal areas with intensive irrigation. Excessive use of groundwater use coastal areas can lead to seawater intrusion. The quality of irrigation water significantly has a significant impact on a crop productivity and can cause soil salinization. This study was conducted to determine the quality of groundwater quality and assess its suitability for irrigation in the coastal regions of Anamur and Aydıncık districts in Mersin province. In August 2021, samples were taken from 51 groundwater wells used for greenhouse irrigations, and the values of pH, electrical conductivity (EC, Na, Mg, K, Cl, SO4, HCO3, and Ca were measured. To assess the suitability of the water for irrigation, values for %Na, PI, RSC, PS, MR, KI, and SAR were calculated. Additionally, spatial distribution maps were created for the water’s chemical properties and irrigation water quality indices. The groundwater’s EC values ranged from a minimum of 0.475 dS m⁻¹ to a maximum of 1.13 dS m⁻¹. According to the spatial distribution map, it was determined that 92.03% of the region’s groundwater quality is classified as Class 3 in terms of irrigation suitability. In 9.71% of the study area, magnesium (Mg) levels exceeded the acceptable threshold for irrigation water. Based on potential salinity (PS) values, 84.91% of the area falls within the medium class for irrigation suitability. The Permeability Index (PI) varies between 17.19 and 48.17, with an average value of 29.84. The potassium (K) values ranged from between 0.391 mg L⁻¹ to 10.557 mg L⁻¹, with 68.3% of the groundwater samples in the region exceeding the threshold value which could pose a risk for irrigation. It was determined that there were no problems in terms of SAR, KI and RSC in the groundwater samples in the area. Groundwater quality is above the limit values in some regions. Due to the intensive agricultural activities in the study area and its proximity to the coastline, it was established that groundwater extraction in the area should be controlled.