Impact of Land-use Change on Water Quality in Söğütlü Stream, Trabzon Province, Türkiye with a Geographic Information System– Based Assessment

Water pollution is becoming an increasingly significant issue in both developed and developing countries. Land use change within a watershed directly affects water quality and aquatic ecosystems, making it essential to evaluate its impacts. This study examines the effects of land-use change on water quality in the Söğütlü stream watershed in the Eastern Black Sea Region and creates thematic maps of water quality parameters. Water samples were collected monthly from nine sampling stations between August 2019 and July 2020. These parameters include temperature (°C), pH, electrical conductivity (μS/cm), dissolved oxygen (mg/L), total dissolved solids (mg/L), salinity (ppt), and total suspended solids (mg/L). The obtained data were evaluated using water quality standards and statistical analyses. Oneway analysis of variance revealed significant differences among sampling stations for pH (F = 18.608, p < .001), electrical conductivity (F = 10.479, p < .001), total dissolved solids (F = 14.688, p < .001), and salinity (F = 13.652, p < .001), whereas temperature, dissolved oxygen, and total suspended solids showed no significant differences (p > .05). Duncan’s multiple range test indicated that pH, electrical conductivity, total dissolved solids, and salinity generally increased from upstream forest- and pasture-dominated areas toward downstream agricultural and residential areas. As a result, landuse change, sand quarries, and tunnel construction have adversely affected the water quality (especially total suspended solids, temperature, total dissolved solids, salinity, electrical conductivity), and quantity. The research findings demonstrate the importance of considering the impact of landuse change on water quality parameters for watershed planning in the Söğütlü stream watershed. Cite this article as: Koralay, N., & Kara, Ö. (2026). Impact of landuse change on water quality in Söğütlü stream, Trabzon province, Türkiye with a geographic information systems– based assessment. Forestist, 76, 0065, doi: 10.5152/ forestist.2026.25065.