Based on both geologic and hydrologic investigations, predictions are made on how much water may flow into future underground excavations within fissured limestone at the Blendevale Prospect, Western Australia._x000D_
A conceptual model of equivalent fracture flow is used rather than an equivalent porous medium model. One advantage of the present method is that transmissivity of individual fractures is estimated and hence possible sudden bursts of water can be predicted with more confidence._x000D_
A second advantage is that the effect on flow caused by widening and narrowing of fractures around the perimeter of projected mining operations can be assessed more realistically in the future. Predictions are made both of flow from individual fractures as a function of depth and of average flow as a function of rate of a face advance. Three types of flow are distinguished, namely pressure-induced flow, gravity flow and long-term flow in response to regional recharge.