An agricultural subsurface pipe drainage network serves a total catchment area of $A = 80.0\text{ ha}$. The design drainage coefficient for the basin is $DC = 15.0\text{ mm/day}$. The continuous design drainage discharge capacity required at the outlet collector pump in liters per second ($\text{L/s}$) is ________ (round off to one decimal place).
Answer Key:
138.9
Step-by-Step Solution & Explanation
1. Daily volume of drainage water to be evacuated ($V$):
$A = 80.0\text{ ha} = 80.0 \times 10^4\text{ m}^2 = 800,000\text{ m}^2$
$DC = 15.0\text{ mm/day} = 0.0150\text{ m/day}$
$V = A \times DC = 800,000\text{ m}^2 \times 0.0150\text{ m/day} = 12,000.0\text{ m}^3/\text{day}$
2. Continuous design flow rate $Q$ in cubic meters per second:
$Q = \frac{12,000.0\text{ m}^3}{86,400\text{ s}} = 0.138889\text{ m}^3/\text{s}$
3. Converting to liters per second:
$Q = 0.138889 \times 1000 = 138.89\text{ L/s} \approx 138.9\text{ L/s}$