Lineament domain analysis to infer groundwater flow paths: Clues from the Pale di San Martino fractured aquifer, Eastern Italian Alps

An automatic lineament extraction was carried out on a processed digital elevation model of a high-altitude Alpine fractured reservoir, the Pale di San Martino area (Dolomites) located in the southern sector of the Eastern Italian Alps. The strike of the main lineament domain indicates the direction of the principal crustal stress. This direction was compared with earthquake focal mechanisms to confirm the orientation of the regional crustal stress. The two data sets provide similar results and show a NNW-SSE maximum horizontal crustal stress orientation, compatible with the direction of the last Alpine compression reported by previous studies in the investigated region. The orientation of the maximum horizontal compressive stress was then used to explore the ability of specific fracture and fault sets to enhance groundwater flow. Subvertical strike-slip faults and joints oriented NW-SE to northsouth provide the greater contribution to the groundwater flow. The location of the main springs and evidence from a dye tracer test conducted in the area confirm this main drainage direction. This study demonstrates that automatic lineament analysis is an efficient and inexpensive method to identify the trajectories of groundwater flow in fractured aquifers.