To meet the increasing demand for electric power and also preserve the environment, more and indeed new concepts for hydroelectric dams are been proposed. For pump-storage rockfill dams, the saturated-unsaturated hydraulic properties of construction materials are important considerations. This paper reports the results of a series of laboratory tests that were carried out on the hydraulic properties of coarse materials. A new method for determining the saturated-unsaturated coefficients of permeability of coarse materials in the laboratory and an evaluating system for rockfill dams under non-Darcy flow conditions due to rapid drawdown are proposed.