CU06997 Exercise lecture 12 ; computation

Link to exercise
Ditch with a length of 700 m.
Bed-slope is 1:3000, Downstream bed level is +0, m N.A.P.
Downstream a weir; width 5 m, m= 1,7, level crest 0,7 m N.A.P, free flow.
Cross section; bed width 2 m, slopes 1:3, n=0,02.
Culvert; Length 20 m, width = 2m, height = 1 m, invert level + 0,5 m N.A.P., λ-value = 0,022, located 350 m upstream from weir.
Discharge (steady) = 1,77 m3/s
1) Calculate the equilibrium depth of the ditch, assume C=40 and average width = 3,5 m
2) Calculate the critical depth of the ditch. Assume a average width of 4,2 m
3) Calculate the water level just upstream of the weir
4) Calculate the water level at the culvert (downstream)
5) Calculate the drop of water level at the culvert
6) Calculate the water level at 700 m upstream of the weir
7) Will the water level in the ditch reach the equilibrium depth?

Remarks!!!!!As discussed in the video, we made some small “mistakes”. For example assuming that total head (H) and pressure head (y) [water level] are on the same level. So we disregard the velocity head. With a velocity of 0,3 m/s the velocity head is 0,009 m.  Don’t do this during the exam!!!.
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