It has been observed that evaporation and seepage losses in the main Ganga canal from head to mile 208 have risen from 360 cusecs, during the period 1932—37 to 1030 cusecs during the period 1951—54. An attempt has been made in this paper to analyse the possible causes. Two important changes that occurred on this canal during this period, and appear to be primarily responsible for this increase are (1) the tube-well pumping in the doabs covered by the Ganga Canal system and (2) the raising of water surface upstream of certain falls for construction of power houses. It would, therefore, seem that these can be the causes for this increase.
