Assessing the Interactions between Chlorophyll <i>a</i> and Environmental Variables Using Copula Method

Abstract

Eutrophication is a major water quality problem throughout the world. An understanding of the pattern of phytoplankton variation and the relationships between chlorophyll a and environmental variables can contribute to eutrophic lake management. In this study, the copula method is applied to discern the inherent relationship between chlorophyll a and environmental variables of Wulihu Lake to the north of Taihu Lake, China. The results show that the method can not only determine the correlation between chlorophyll a and environmental variables through Kendall’s τ but also determine the joint distribution without assuming the variables to be independent. Moreover, the return period of chlorophyll a can be obtained for given different environmental variables. This study may provide insights for policy makers wishing to improve the water quality of lakes and reservoirs.