Extracting coherent component of groundwater system by independent component analysis: A case study of Lanyang Plain

Groundwater fluctuations occur in response to a number of different physical mechanisms. If groundwater fluctuations can be broken down into several independent components, groundwater management problems can be better analyzed and addressed. This study investigates the ability of independent component analysis (ICA) to divide the spatial and temporal fluctuations of groundwater levels into several independent components, which are caused by various physical mechanisms. We applied a numerical model with one recharge source and two groups of pumping wells with different frequencies of the assigned time series for each of them. The model was simulated by MODFLOW and the simulation results at the observation wells were the ICA input. The method divided the mixed signals into three independent components, thus demonstrating the applicability of ICA. After verifying the applicability of ICA, we applied this method to a set of 22 daily observed groundwater levels from 2005 to 2010 within the Lanyang Plain. This study obtained two independent components representing the effects of rainfall and rivers. The results indicate that the proposed method can be used to interpret the signals of groundwater levels and to identify the major physical mechanism. Therefore, this method can serve as a useful reference for the analysis and management of regional groundwater systems.