Government of Sind Public Works Department. Proportional Slit distribution at the heads of Canals and Distributaries in Sind

(2) The change in the position at which the Jamrao approach channel originally took off from the Eastern Nara This change took place on account of gradual erosion of the nose formed at the point of bifurcation leading to the shifting of the approach channel further downstream and thereby causing a draw of a very large part of bed water which was heavily charged with silt. [...] 1. It will be noticed that the change in the course of the Eastern Nara since 1932 above the offtake of the approach channel is significant in as much as the channel has kept on shifting from the right bank to the left. [...] Model experiments were accordingly proposed with a view to verify whether the change in the position of the offtake point of the approach channel had anthing to do with the silt trouble and if so to find out the best alignment of the same which would reduce the silt entry in the Jamrao canal.3 SELECTION OF SCALE RATIOS FOR A DISTORTED MODEL. [...] (6) The following notations were adopted : Notations— Om= Discharge in the model Q = Discharge in the prototype Vm = Velocity in the model V -Velocity in the prototype Pin= WtAted perimeter in the model P = Wetted perimeter in the prototype Rin= H. M. D. in the model R = H. M. D. in the prototype T = Time in the prototype Ta Time in the model S = Slope in the prototype in tile model In a geometr [...] The flatness of the gradient was attributed to smoothness of the model resulting in an extremely low value of Nrn which worked out to o.0068 in the model as against the value of 0.0204 for the prototype.