PERMEABILITY AND STRESS IN CRYSTALLINE ROCKS

Groundwater from crystalline rocks is a significant resource in many a reas of the world. It is also an important medium for contaminant tran sport from, for example, deep nuclear waste repositories. Stress distr ibutions in fractured rocks are important in controlling groundwater f low in several ways: (i) palaeostress fields are responsible for the e volution of fracture systems which transmit groundwater; (ii) current in situ stress fields will influence the shape and aperture of fractur es; (iii) humans can influence the natural stress field in a rock mass to enhance fracture flows. The significance of stresses for groundwat er flow can be investigated by field techniques (hydraulic fracturing) , laboratory techniques (stress cells) or by numerical modelling.