Transitions for Canals and Culverts

Results of large-scale model studies of variations in open-type and closed-conduit-type inlet and outlet transitions for small canals and culverts are presented. Losses for open transitions are 0.6 to 0.7 Δh_v for outlet service, and 0.4 Δh_v for inlet service. Reasonable changes in slope of the inverts, slope of the pipelines, or changes in divergence of the sidewalls have little effect on losses or scour. Losses for outlet service decrease to 0.4 Δh_v when short closed-conduit transitions are added between the pipeline and the open transition. Outlet losses are reduced to 0.1 Δh_v by using Six D-long closed-conduit transitions that discharge directly into the canal through vertical headwalls placed normal to the canal axis. Inlet losses remain at 0.4 Δh_v. Scour in earth canals is less with the closed-conduit transitions than with conventional open ones.