Question

The ordinates of a 2 h unit hydrograph at 1 h intervals starting from time = 0 are 0, 3, 8, 6, 3, 2, and 0 $m^3/s$. Use trapezoidal rule for numerical integration, if required.
What is the catchment area represented by the unit hydrograph ?

• A. $1.00k{m}^2$
• B. $2.00k{m}^2$
• C. $7.92k{m}^2$
• D. $8.64k{m}^2$

Answer 1

The correct option is C $7.92k{m}^2$


Area of unit hydrograph
= 1 cm x catchment area
$\Rightarrow \frac{1}{2}(0+3)\times 1+\frac{1}{2}(3+8)\times 1+\frac{1}{2}(8+6)\times 1$
$+\frac{1}{2}(6+3)\times 1+\frac{1}{2}(3+2)\times 1+\frac{1}{2}(2+0)\times 1$
$=0.01\times A$
$\Rightarrow 22\times 3600m^3=0.01A$
$A=7.92\times {10}^6{m}^2=7.92k{m}^2$