Modeling the effect of forest patch connectivity on river water quality in the Caspian Sea basin

In this research, the continuity of land landscape was analyzed from the perspective of land landscape metrics (10 indicators) and graph theory indicators (12 indicators). First the correlation between correlation indices and water quality parameters was performed using Spearman and Pearson correlation coefficient and then with the help of stepwise linear regression method and through power, exponential and logarithmic regression models and using Akaike coefficient, the best model was chosen. The results showed that there was a significant negative correlation with water quality parameters between the land quality measures of CONIG and FRAC and the length of the corridor and most of the continuity indices of graph theory. Also, the highest coefficient of explanation or R2 belonged to CO3 models with a coefficient of explanation of 0.818, water flow with a coefficient of explanation of 0.733, Ca with a coefficient of explanation of 0.772 and TDS with a coefficient of explanation of 0.704. Almost all selected models are nonlinear models. Significant correlation of land feature continuity indicators, especially graph theory continuity indicators and corridor length with water quality indicators, shows the effect of structural features of land landscape on water quality in watersheds.