Determination and management suggestions of diffuse polluting sources in the South Marmara Basin

The Southern Marmara Basin is a strategic region located in the northwest of Turkey, encompassing a significant part of the Marmara Region. Turkey's sustainable development goals require the protection and management of this region, rich in agriculture, industry, tourism, and water resources. The basin's strategic importance exposes it to a wide range of diffuse pollution sources. Therefore, the protection of the basin and the implementation of sustainable management strategies are of great importance. This study aims to estimate the nutrient loads (Total Nitrogen - TN and Total Phosphorus - TP) from diffuse pollution sources to receiving environments in the Southern Marmara Basin and thereby develop management recommendations to identify and prevent diffuse pollution that may reach water resources. In this context, the provinces within the boundaries of the Southern Marmara Basin and the areas of these provinces within the basin boundaries were identified. While determining the TN and TP loads that may reach water bodies, data from agricultural areas, livestock activities, forest areas, pasture-meadow areas, urban surface runoff, leachate from solid waste disposal sites, and atmospheric deposition were utilized. As a result of the study, TN and TP distribution maps of the Southern Marmara Basin were created. Additionally, the surface water quality class in the basin was evaluated according to the Surface Water Quality Regulation through selected streams where diffuse pollution is intensely observed, and the sources of water pollution were identified by creating correlation matrices of water quality parameters.