Question

The ordinate of the instantaneous Unit Hydrograph (IUH) of a catchment at time t, is

• A. the slope of the 1-hour unit hydrograph at that time
• B. the slope of the direct runoff unit hydrograph at that time
• C. difference in the slope of the S-curve and 1-hour unit hydrograph
• D. the slope of the S-curve with effective rainfall intensity of 1 cm/hr

Answer 1

The correct option is D the slope of the S-curve with effective rainfall intensity of 1 cm/hr

Ordinate of IU is given by

$U\left(t\right)=\frac{1Ds}{iDt}$

i = intensity of rainfall
s = ordinate of S-curve
Thus, the ordinate of IU is the slope of the S-curve of intensity 1 cm/hr.