Estimation of water i nflow to a surface mining operation is a necessary requirement for mine drainage design. The water in a shallow surface mine may originate solely from a surface source and from the atmosphere in the form of precipitation. Water in deep mining excavations below the groundwater table may originate from a surface source or as atmospheric precipitation as well as from the groundwater system. Inflow of surface water to a mining excavation can be predicted by hydrological balance investigations of a mining catchment. The paper briefly describes the hydrological cycle of a mining catchment together w ith the technique of estimating inflow from a surface source.