The temporal dynamics of transmission losses are illustrated during single events within a 150 km long arid channel reach of the Kuiseb River, Namib Desert, Namibia. This is facilitated not using a traditional water balance study but by applying a mathematical flow routing scheme with parameters not calibrated with runoff information. Transmission losses are deliberately excluded from the model so that actual transmission losses can be identified as the component of model simulations that plots significantly higher than the measured discharges at the downstream end of the reach. Results indicate that transmission losses concentrate during high discharge peaks and are minor during small to medium flows. Keywords: Large ephemeral streams, Transmission losses, Arid environments, Flow routing, Riparian vegetation, Kuiseb River, Namib Desert.