Critical depth equations for irrigation canals

Critical depth is an important parameter assuming the analysis of varied flow in the canals and natural streams. Direct solution of critical depth problems is not possible, as the governing equations for practical canal sections are implicit. The solution requires tedious computations of trial and error. Tabular and graphical methods are also available for solution. These methods are subject to errors of double interpolation or error of judgment in reading the graphs. No method is available for rounded-bottom and rounded-corner canal sections. Reported herein are explicit equations for critical depths in various sections used as irrigation channels.