The stage of river carrying a discharge of Q m7sec at a point is 10 m and slope of water surface is (1/4000). The discharge of a flood at the same point and same stage of 10 m with a water surface slope of(l/1000)willbe A)V2 Q m³/sec B)0.5 Q mVsec C)2 Q m³/sec D)4 Q m³/sec

Question

Quizplus · Accepted Answer

The discharge in an open channel flow, like a river, can be estimated using the Manning's equation or similar, which relates discharge to the slope of the water surface (among other factors). When the slope increases, the discharge increases as well, assuming other factors remain constant. The slope in the flood scenario is 4 times steeper (1/1000 vs. 1/4000), which increases the driving force for the flow, leading to an increase in discharge. The relationship between slope and discharge, in this simplified scenario, suggests that the discharge would be directly proportional to the square root of the slope change. Since the slope is 4 times steeper, the discharge would be 2 times larger (sqrt(4) = 2), making the correct answer 2 Q m^3/sec.

The Stage of River Carrying a Discharge of Q M7sec