Study of the effect of local forcing on the fractal behaviour of shallow groundwater levels in a riparian aquifer

Abstract

With the help of a physically based recharge-groundwater flow model and robust detrended fluctuation analysis (r-DFAn), the effect of local (catchment-scale) forcing on groundwater levels' scaling behaviour in a riparian aquifer in Wallingford, UK, is investigated. The local forcings investigated in this study include the rainfall's temporal scaling behaviour (which is simulated by changing rainfall's intermittency parameter in a β-lognormal multiplicative random cascade model), the aquifer's physical parameters (saturated hydraulic conductivity, specific yield, the empirical coefficients of the water retention curve and the river stage's scaling behaviour). Groundwater level's scaling behaviour was found to be most sensitive to rainfall's fractal behaviour. Additionally, there is preliminary evidence suggesting that changes to the rainfall's local scaling behaviour (i.e., change to the series' scaling that induces crossovers) affects the groundwater's and the recharge's local scaling behaviour.