Fig. 2 Distributions of different land-use types in the study area. (a) Principal coordinates analysis (PCoA) biplot and (b) area proportions of major land-use types in three study regions.
The environmental factors in the different rivers over two seasons (autumn and spring) are visualized in Fig. S3. In both seasons, Turb, Cond, TN, TP, NH4+-N, and NO3--N in water samples from Weihe River were significantly higher compared with those of the Hanjiang River and Qinling tributaries. Pearson’s correlation coefficients were used to analyze the impacts of different land-use types on the environmental factors. The proportions of agricultural land, grassland, urbanized land, and open water areas exhibited significant positive correlations with Turb, Cond, TN, TP, NH4+-N, and NO3--N. However, with an increase in the proportion of forest land area, all environmental factors exhibited decreasing trends, excluding DO (Fig. S3).