Government of Sind Public Works Department Technical Paper No. 5 Proportional Silt Distribution at the Heads of Canals and Distributaries in Sind

Results of simultaneous observations taken on all the channels taking off at the Jamrao weir Makhi weir Khirthar Branch Head and at other places have showed that the silt load passing per second at the cross section on the upstream of the parent channel agrees very closely with the total silt load as measured on the downstream of all the offtaking channels. [...] i. 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 : NotationQm= Discharge in the model Q = Discharge in the prototype V.= Velocity in the model V = Velocity in the prototype Pm= Wetted perimeter in the model P = Wetted perimeter in the prototype R.= H. M. D. in the model R = H. M. D. in the prototype T = Time in the-prototype T.= Time in the model S = Slope in the prototype S.= Slope in the model In a g [...] The flatness of the gradient was attributed to smoothness of the model resulting in an extremely low value of ' which worked out to o.0068 in the model as against the value of 0.0204 for the prototype.