Application of Hilbert Huang transform method for analysis of contaminant concentrations in the Niagara River

Water quality analysis and modeling in natural rivers has often been accomplished by monitoring programs and examination of the resulting series for long- and short-term tendencies, seasonality and the relationship of the cause and effect of human activities. This paper introduces the HHT method to the environmental engineering field for the analysis and prediction of non-stationary and nonlinear time series. The HHT combines two distinct analytical methods to decompose observed data into independent Intrinsic Mode Functions (IMFs), the Empirical Mode Decomposition (EMD) method and to transform these time-dependant functions into time-frequency functions, the Hilbert Transform method. The HHT is introduced to the field of water quality analysis for evaluation of trends and assessment of impacts of external physical factors for more sustainable river water quality management. A case study using the HHT method for data analysis and for simulation of time series of Chrysene concentrations in the Niagara River is presented. © 2008 ASCE.