Soil site studies are crucial in the analysis of seismic hazard in populated areas. This study focusses on the use of the Ground Penetrating Radar as a non-destructive geophysical method to analysis the water content of a sedimentary basin of a local urban area in Cervantes Parks in Barcelona city. Main objective of this work is to understand further the local seismic soil site, and analysis the background clutter amplitude and frequency of the GPR signal applied on the seasonal changes of the underground water content. Changes produces in the GPR signal could be associated to the changes of the ground material due to the existence of water content and water flow, which influence the grain size distribution of the soil characterisation. Previously, several methodologies have been applied to determine the changes of the ground material due to the existence of water content and most importantly effect of the seasonal changes on the soil characterisation. GPR has been applied as a new technology and non-invasive to further analysis water content in shallow geology. Methodology applied on this study compromised in four different phases; Two seasonal data collection using 100 MHz centre frequency shielded antenna in both dry and wet season, radar images are proceeded with common post-processing approaches, following more innovative processing approach based on the Fast Fourier Transform (FFT) method in order to analysis background clutter amplitude and frequency spectrum to achieve an accurate interpretation of underground water content activities, in conclusion a comparative study of the results driven from radar images are elaborated considering historical knowledge. Results show that GPR is an efficient technique to analysis water content invasively considering low frequency antennas to achieve deeper penetration depth in sedimentary deposits, and predict shifting and increasing of the underground streams due to changes in weather conditions. Results could contribute to the enhancing local seismic site behaviour in populated areas considering continuous monitoring of underground water activities in sedimentary basin sites.