Groundwater resources in the Mediterranean region face increasing threats from intensive anthropogenic activities and climate variability, particularly in complex fractured granitic environments where traditional mapping often lacks the resolution to characterize contamination pathways. This thesis presents an integrated vulnerability assessment of the Caldas da Cavaca hydrogeological system in Central Portugal, combining standard GIS-based indices with novel LiDAR-derived vegetation metrics. The primary objective of the study was to perform a comparative analysis of groundwater vulnerability using the intrinsic DRASTIC model and the specific Susceptibility Index (SI), while simultaneously testing the hypothesis that arboreal biomass distribution serves as a bio-indicator for subsurface weathering and fracture density.