A major unsolved problem in glaciology concerns the interaction between glacier basal sliding and the subglacial hydrologic system. Despite four decades of modern theorizing and field endeavors, the role of the subglacial drainage system in modulating the speed at which glaciers flow is still relatively poorly understood. In this proposal we seek to elucidate the impact of the subglacial drainage system on glacier basal sliding, with a particular focus on a glacier's response to high-pressure events. In si tu measurements of the interaction between tha basal ice and the hydraulic system wil be carried out in the Svartisen Glaciological Observatory, at Engabreen, Norway. Pressure transducers installed in sealed boreholes and load cells installed at the glaci er bed permit measurement of pressure changes through time. Natural pressure variations can thus be documented. In addition, we will carry out high-pressure pump experiments, which involve injecting water from boreholes at the glacier bed into the basal h ydraulic system. The pressure transducers and load cells record the spatial and temporal pressure evolution of t he high-pressure zone thus created. The data will be analyzed and used as calibrating source for a numerical solution of the response of the b asal ice by the finite element method.