Analysis of treated wastewater reuse potential forcontrolling of seawater intrusion in the coastal aquifersof Turkey

In fertile coastal areas where the population are densely concentrated, excessive pumping of groundwater damaged the natural and sensitive balance between freshwater and saltwater and allowing saltwater to flow further inland and causes seawater intrusion. Seawater intrusion is one of the most wide-spread environmental problem threatening freshwater resources along the coastal areas where the fresh groundwater aquifers are surrounded by sea. The objective of this study is to investigate the potential of reclaimed water quantitatively and also evaluate in terms of cost that could be used by injection wells in order to build a hydraulic barrier to help preventing seawater intrusion in the coastal regions of turkey where the groundwater contaminated or is under the risk of seawater intrusion. Spatial analysis has been done in ArcGIS Desktop 10.5 to determine the most suitable area for stablishing of injection wells. For this purpose, 15 provinces with high risk of seawater intrusion in Marmara, Aegean and Mediterranean regions (Adana, Antalya, Aydın, Balıkesir, Bursa, Çanakkale, Edirne, Hatay, İzmir, İstanbul, Kocaeli, Mersin, Muğla, Tekirdağ ve Yalova) of Turkey have been selected. 140 wastewater treatment plants with large capacity (equal or more than 5000 m3/day) have been considered with an average distance of 40 km to coastline in order to investigate reclaimed water potential in the study area. Approximately a total potential of 6 Mm3/day reclaimed water have been estimated in the study area. The reclaimed water divided in 3 groups according quality which are subjected to physical and natural treatment (about %37.5, 2,253,674 m3/day), secondary/biological treatment (about %14.4, 865,127 m3/day) and advanced treatment (about %48.1, 2,892,532 m3/day). Seven parameters namely, slop, land cover, fault line, residential area layer, road layer and distance layers from Wastewater treatment plants and shoreline have been used in GIS application in order to find an appropriate site location for stablishing of injection wells in the study area. According to the criteria specified in the GIS, a total of 720 injection wells have been estimated to be installed in 84 different points parallel to shoreline.