Hydrogeology of Küçükköy plain and sea water intrusion

This study contains hydrogeological and hydrogeochemical investigations carried out in Küçükköy (Ayvalık) Region. The study area is located on the Aegean coast within the borders of the Balıkesir Province and covered with alluvium units consisting Pliocene aged clayey limestone, marl and Quaternary aged clay, silt, sand and gravel. While the Pliocene units form weak aquicludes, alluvium are aquifers. Groundwater samples have been taken from the study area to determine the hydrogeological characteristics of the study area. According to the geochemical analysis results of the groundwater samples, hydrogeological characteristics of the groundwater have been determined; evaluated within the context of Piper, Schoeller, Wilcox and USA Salinity Diagrams. Chemical analysis of the groundwater samples taken from the boreholes drilled in the study area has shown that the salinity has been increased in time away from the sea shore. Categorized according to facies types, as ion amount of groundwater samples in the study area does not exceed 50%, it has been determined that alkalinity with complex and lack of carbonate is in the water type more than 50%, furthermore the groundwater quality of the Ayvalık plain is found to be C2S1 and C3S1 , in most part and C4S1 in the sample taken from nearly salty section. The salinities of the groundwater has increased in time with higher saltiness in internal sections in comparison to the coastline section, as observed from the chemical analysis of groundwater samples taken from wells in the study area. The reason of this is the sea water intrusion occurred as a result of the over discharge. The sea water intrusion caused that the saltiness of groundwater has increased in some regions following the opening of drilling wells and sea water has proceeded towards coastline aquifer depending on the increased water demand. It has been observed that water contains Al, Zn, Fe, Cd, Pb with high amounts, according to the heavy metal analysis made in laboratories with the samples taken. Therefore, there is a contamination.