In this study; the effects of land use/land cover (LULC) changes, soil type and slope characteristics on surface water quality trends were evaluated for rainy and dry periods based on the riverside boundary zone concept. The Mann-Kendall test demonstrated the degree and importance of tendencies in all water quality parameters for each riparian area between 2008-2015 and 1999-2015. The LULC changes (between 1999 and 2015), soil types and slope characteristics were demonstrated by geographical information system and remote sensing methods. Pearson correlation analysis was applied to determine the relationships between the variables of water quality parameters with LULC, soil types, and slope. Results show that urban and agricultural areas have a negative impact on water quality and vegetation cover areas play an important role in improving water quality. Negative correlations were found between bare areas and all parameters. LULC changes negatively affected water quality, especially in terms of NH4, NO3, total dissolved solids and total phosphorus parameters. Alluvial soils and 0%-2% slope group also negatively affected the water quality. This study demonstrated the spatial-temporal distribution of surface water quality across the watershed and emphasized the importance of the riparian area in determining the variables affecting water quality.