a 
400 Journal of the Asiatic Society of Bengal. [November, 1909. 
submerged and eroded, or are covered with sand, as the 
the old course the loss of water in the dry season is often 
seriously felt. Now, when a river has banks of moderate 
rmness, so that side erosion can be kept within reasonable 
bank. “A pavement with rubble stone or concrete blocks is 
sufficient to prevent a gap forming. It is not difficult to 
calculate with approximate accuracy the volume of flood 
ows. What, however, has not yet been fully determined 
is partly rolled along the bed, and it is with respect to the 
than probable that these floods are mainly, if not entirely, due 
_ There is, sometimes, a tendency to write of flood banks 
me if they actually caused the flood. This, of course, is not 
the case. The flood is due to excessive rainfall on the catchment 
