BACKWATER CURVES IN UNIFORM CHANNELS 



79 



from Fig. 701(&). Curves for other values of the discharge can be plotted on 

 the same graph. In obtaining /(y) for other discharges, only columns 7 to 11 of 

 Table 701 need to be recomputed, for the values in columns 7 and 9 will be 

 proportional to the square of the value of the discharge. 



8000 



6000 



4000 



2000 



9 — — . 



10 



12 



14 16 18 20 



y = Depth of Flow, in Feet 



Fig. 701(a). Plot of /(y) Computed in Table 701. 



Areas under this curve represent distances along the channel. 



10 



12 



14 



16 18 20 



y= Depth of Flow, in Feet 



22 



24 



Fig. 701(6). Summation of Areas under the Curve of Fig. 701(o). 



PROBLEM 



701. Assume that the canal of the illustrative example has a sudden drop-ofT 

 at the lower end, all other data remaining the same. Determine the backwater 

 curve, and compare it with that of problem 603. 



Backwater curves in horizontal uniform channels : preliminary. For 



the H2 and H3 backwater curves, which are the important special cases 

 for which the channel bottom is horizontal, a different treatment is 



