In this paper, we present a methodology developed for quantifying fractal properties of salt concentration profiles induced anthropogenically in coastal aquifers of Bundaberg, Queensland, Australia. Based on data observed in the field and multifractal models, it is found that salt profiles induced in the coastal aquifers are periodic fractals, and the fractal dimensions of the salt profiles and associated tidal waves are predominant in urban and industrial areas where frequent human activities impose severe impact on the waveforms. It is found that the fractal tidal waves are heterogeneous as indicated by variable dimensions of the waveforms at different orders. It is also shown that the results from multifractal analysis are more consistent and reliable than those from spectral analysis. The methods developed in this paper can also be applied to characterise time series data in other fields such as data on hydrographs, water levels, pollutant and air quality etc.