Seasonal assessment of the impact of fresh waters feeding the Bay of Gokova with water quality index (WQI) and comprehensive pollution index (CPI)

Abstract

The Gokova Bay declared as Private Environment Protection Area (PEPA) in Turkey in 1989, where freshwater and seawater ecosystems are intertwined, is an important area that possesses high biodiversity. In the study, the water quality index (WQI), comprehensive pollution index (CPI) were used to determine the water quality and pollution of freshwater sources affecting the Gokova Bay. The water quality parameters were measured for each freshwater at both the dry and rainy seasons and all statistical analyses were carried out for each season, separately. Firstly, factor analysis was performed to determine the correlated water quality parameters and to collect correlated parameters under the common factors. The different factors were obtained from the dry and rainy seasons. This shows that the study area is fed by different water sources in the wet season and that the main factor affecting the area in the dry season is anthropogenic sources. The stations were statistically compared according to the factors. The relationships between the factors and WQI and CPI were investigated and lastly regression models between the factors and WQI and CPI were predicted. The results showed that the water quality parameters deteriorated in all the freshwater sources especially in dry seasons. A thematic map of each water quality and pollution index was developed in Geographic Information Systems (GIS). This study indicates that CPI can be used especially together with GIS as a useful tool for the evaluation of water quality and pollution.