A cross-section of a compound channel is expected to be designed as shown in the Fig. below. The channel slope is 1 in 5

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A Cross Section Of A Compound Channel Is Expected To Be Designed As Shown In The Fig Below The Channel Slope Is 1 In 5 1 (61.28 KiB) Viewed 69 times

A Cross Section Of A Compound Channel Is Expected To Be Designed As Shown In The Fig Below The Channel Slope Is 1 In 5 2 (104.28 KiB) Viewed 69 times

A cross-section of a compound channel is expected to be designed as shown in the Fig. below. The channel slope is 1 in 500. The specifications of materials in all surfaces are also shown in the Fig. (hint: use the average values for manning's n). (1)The purpose is to design the optimum hydraulic section for maximum discharge (i.e. minimum wetted perimeter). (mark: 65%) a. Use equations 8.19, 8.20 and 8.21 of the reference book to calculate average manning's n (na) to design the cross-section and critical analyse which of the results obtained from the above three equations of average manning's n should be used for your design and also b. Critically analyse and discuss the best methods to improve the capacity of the waterway (i.e. channel and flood plain) through changing the materials used for construction of the cross-section. The following assumptions are considered when designing the cross-section: a. Minimum Capacity of the main channel for base flow is 10 m/s b. Minimum Capacity of both main channel and flood plain is 50 m/s C. Minimum width of the access path is 3 m d. Maximum depth of the main channel (h) is 1.5m for safety e. Maximum width of flood plain is 50m
Max 50m Sort ரக Min 3m Acces path Concete Mn 3m Access path Sort gais Concrete Concrete h 1.5 Concrete Stores 75150nmdam Poor dimet (2)The capacity of both main channel and flood plain in part 1 is calculated based on the peak value of the hydrograph of the flood runoff with a return period of 100 years in the upstream river catchment. If the results of the climate change show that the aforementioned peak value is likely to increase by 20% in the future (i.e. by the next 20 years), critically analyse/discuss any innovative solution/technique based on hydraulic principles for dealing with this situation. You can support your statement with numerical calculations and cost-effective analysis. Your solution can be linked to a wide range of potential options e.g. the change of the suggested cross- section or change in the sub-catchment upstream. (mark: 35%)
sop dreloage given by manningsformula 1 سرلا Q AS13 SO where DO The max channel is shown below nmanning disebbicient A welted Area pa wekte el peimelet =-bed Blope of the channel Su 6S 71 soc 160 B ان سے we com see . OC = han The - figare They area of channel = alea torc. A=T8 x 21 CB= 96 08 30 qe te PT C863 alea of scelton OaBeaua of DOAB 3*2T) - (* *2 xq coges YIT (936) TA = 772 V similarly the punietur of channel is p = 2T 3 -X 2304 3x2 P=2-17 3 valer in m - using The given mannings Evater weget
from? V7_513942 2 25 0.04 217 1000 L. solving for the or we get for = 9.43 meleys] bence depth of channel bed frau top is Ce=9-97 Cosbe CE=9.43 - 94430086 i hence top width - ABxoncasz = lowenst sed. Reul = [TE=40115m 279.43683! = 16.34 melis zoound level 33.5m-yetlom 2807260 a CE- part 2 : wowo .we have to pass a dich@ge of C227-30) aslsce da The 2 Hood beloup The depth of flow in the food planne is (RL) of carest Re of bed Forer. Boaled - 3500 - 33-003.- 103m Now we here: 1634) 1630) E K 1121 L area of Show once max channel (2x LX112.4 16.34 km wetted pumitee - (Role-L +19.61 ) m EXEC+112)m j3 (27-05) - dorix Qu4 L +19.61) 12 0.5 х 1000 (2 x (Ltlejte *Lood solving for L'weget L=216m 2xt +1634 . distance blw & below = QX046+1Ge 1642. 34 mm