A water-balance approach to estimate ground-water recharge is developed for ungaged basins of Oman and Abu Dhabi, United Arab Emirates. The technique uses a distributed transmission-loss model for ephemeral stream-flow in arid/semi-arid areas that is calibrated using relations between channel morphology and discharge characteristics, and between drainage-basin areas and flood magnitudes. Inputs for the transmission-loss model, including precipitation, may be determined using geomorphically established outflows from selected basins. Recharge is estimated by routing discharge of an index storm downchannel, accounting for channel losses and adjusting for interchannel recharge during low-frequency precipitation events.