Effects of landscape structure on river water characteristics: a multi-scale analysis

This study aimed to assess the relationship between landscape characteristics and water quality in two distinct basins. Through the utilization of multiple stepwise regression analyses and redundancy analysis, the quantitative association between landscape metrics at both the watershed and riparian buffer scales was examined. The findings revealed that metrics at the riparian buffer scale exhibited greater effectiveness in predicting water quality compared to those at the watershed scale. At the 100-m buffer scale, specific variables such as forest edge density, and effective mesh size of urban areas in the Khorramabad basin, as well as forest aggregation index, urban edge density, and agricultural patch splitting in the Chalus basin, were identified as significant factors influencing water quality. In contrast, at larger scales, only metrics related to agriculture and urban land uses demonstrated dominance, indicating that these land-use classes play a decisive role in driving changes in water quality within the study areas. Moreover, as the scale increased, the influence of dominant variables on water quality exhibited a decreasing trend. Despite the minimal human activities observed in the Chalus basin, their impact on the quality of the Chalus River was substantial. Urban and agricultural land uses were consistently identified as dominant factors across all scales, suggesting that even a substantial amount of forest cover cannot fully mitigate the effects of human activities in a basin. This research underscores the significance of considering both the composition and configuration of the landscape when assessing water quality.