8.6.3. Evaporation and Seepage Losses in Canals When water flows in an alluvial channel, some water is lost due to evaporation from the water surface and seepage through the bed and banks of the channel. These losses are termed transit losses or canal losses. The transit losses are calculated at the rate of about 3 m3/s per million square metre of the exposed water surface area. These losses may be of the order 10 to 40 per cent of the discharge at the head of a channel in case of large channels.
