122 



BENDS, TRANSITIONS, AND OBSTRUCTIONS 



To illustrate further the use of Fig. 1003, let us consider a numerical 

 example. Suppose that a rectangular channel 10 feet wide narrows 

 down smoothly, in a short distance, to a width of 9 feet. If the depth 



P>. 



-^Di 



Elevation 





W, 



Plan 



10 



0.1 

 0.08 



0.06 

 0.05 

 0.04 



0.03 

 0.02 



0.01 



0.01 



0.02 



0.04 0.06 0.1 



0.2 



Values of 



0.4 0.6 

 ■2.9 



3 4 5 6 8 10 



J5, 



Fig. 1003. Ratios of Velocity Head to Depth Above and Below a Change of Width 

 in a Rectangular Channel. 



in the 10-foot section is 6 feet, and the velocity 5 feet per second, what 

 is the depth in the section of 9-foot width ? To solve this problem with 

 the aid of the diagram, first compute the following: 



FiV2g _ 0.389 

 Dx ~ 6 



= 0.0649, 



Zl 



2g 



-f i)i = 0.389 -f 6.0 = 6.389, and 



W2 9 



-^ = — = 0.9 



Wx 10 



