## Metric Problems

Determining the net water to apply and store in the root zone is dependent on having the appropriate data for the tables in SI units. They are not provided in this text, but additional problems such as system capacity can be computed in SI units.

Problem: determine the pump capacity that will be required to apply 30.5 mm of water to 50.0 ha when the irrigation interval is 10 days and the pump can operate 20.0 hr per day.

Solution: Using units method /m3 \

10,000 m2

10 day 60 min

m min

By equation: RSC

Ax DWA

IRPxHPDx0.1 10x20x0.1

305 "20

15.25 or 76.25

m h7

Or 1.27

m3 min x x

Problem: A producer spends 120 hr irrigating 35.0 hectares. The pump discharges 5.2 cubic meters per minute. What average depth of water (mm) is applied?

Solution:

60 min

x 120 hr

Problem: What is the largest size of lawn (m2) that can be irrigated in 6.0 hr if a minimum of 1.3 centimeters of water is applied at each irrigation, the system is 90% efficient, and the water supply delivers 13.0 Liters per minute (L/min)?

Solution:

60 m2