The study looked at water quality in Seonakdong River to understand pollution sources and create maps showing the distribution of different chemicals in the water. The main sources of pollution were sewage from populated areas and wastewater treatment plant discharges. High levels of nitrogen and phosphorus were found in the water, making it unsuitable for agricultural use. Tributaries like Hogeo stream were heavily affected by pollution from cities, leading to increased nutrient levels in the main river. Areas near the sea had high salt content, making the water unsuitable for farming. The study used GIS and remote sensing to map out the water quality data, making it easier to understand and develop solutions for improving water quality in the watershed.