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Civil Engineering - Water Resources Q5 (a) A hydroelectric scheme comprises an upper storage lake and a lower impounding reservoir connected by a tunnel of 2.4 km total length internal finished diameter of 1.2 m and Hazen-Williams friction factor of 80. The tunnel delivers water to an on-line turbine hall at a normal operating rate of 2 m3/s. A surge tank constructed within a circular shaft is positioned 100 m upstream of the impounding reservoir and has an internal finished diameter of 2400 mm. If the turbines experiences shutdown, compute the maximum likely instantaneous water level within the surge tank by filling Table Q5. Use 10 sec time steps. Table Q5: Computation of Surge Pressures -dy Hf y Hi-y t V -dv t=time; v=velocity in pipe; Q= flow through pipe; dy=change in water level, Hr=headloss due to friction; y=water level below no-flow level; dv=change in velocity (b) Explain the effect of timestep on the calculation of surge height in Q5(a).