Abstract
The usual method of estimating the change of volume of deposits in a river bed has been to measure 2 or more sets of photographs which have been taken at different times.
It seems that in the past, an accuracy check of the measurements obtained has been neglected due to the fact that it involves many uncertain factors.
The systematic accumulation of data containing many different factors is needed to evaluate the estimated results objectively.
We will report on some of the results of tests conducted.
