Relating Watershed Characteristics to Non-point Source Pollution in Miyun Reservoir Watershed Using Principal Components Analysis (PCA)

The watershed Landscape characteristics are important variables that influence surface water quality. Freshwater research and management efforts could be greatly enhanced by a better understanding the relationship between these variables and surface water quality. The major focus of this paper involved modeling relationships between watershed characteristics variables and water quality indicators. The Miyun reservoir watershed was the selected study site. Statistical analyses were performed to quantify the relationship between landscape metrics, hydrologic and surface water quality. PCA eliminated cross-correlations between variates and reduced the 13 input variables to 5 components that accounted for >92% of variance. TN, NO₃-N, NO₂-N and NH₄⁺-N coefficient of variation were predicted with PCA regression. Results showed that landscape characteristics in the study watershed could account for as much as 60% of the variation of water quality indicators.