Understanding water circulation in rocks represents a very important element to solving many of the problems linked with civil, environmental and mining engineering. This book offers a synthesis of the actual knowledge about the fluid flow in rocks: - from the medium characterization and the structural geological survey to the generation of stereonets; - the evaluation of the hydrogeological parameters using either deterministic or probabilistic methodologies; - the evaluation of the preferential flow direction considering the change of the hydrogeological structures; - the methods and models used to simulate the flows. Five case-studies are provided; groundwater-related slope instability, hydrogeological risk linked with tunnelling and road construction, and springs safeguard. Laura Scesi is Professor of Applied Geology at the Polytechnic University of Milan. She published about 70 papers and 4 books on protection and optimization of natural resources, technical, geological and hydrogeological investigations for projects, hydraulic circulation in rocks, landslides and risk analysis, underground excavations. Paola Gattinoni is Researcher in Applied Geology at the Polytechnic University of Milan. She authored about 40 papers on landslides and groundwater modelling, geological, technical and statistical analysis for hydrogeological setting and rock mass characterization, geological and hydrogeological risk assessment, water circulation in fractured rocks.