Water measuring device used for determining discharge from a piped irrigation system is usually
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Weirs, V-notches, and Flumes are used exclusively for open-channel gravity flows.
For closed, pressurized piped systems (such as drip or sprinkler systems), inline flow meters are the only suitable option.
Step 1: Understanding the Concept:
Irrigation water measurement devices are designed for specific hydraulic conditions, depending on whether the water flows through an open channel or a closed pressurized pipe. Step 2: Detailed Explanation:
Let us analyze the application of each water measuring device listed in the options:
- Weirs (including rectangular, trapezoidal, and Cipolletti types) and V-notches (triangular weirs) are gravity-flow structures placed in open channels to measure discharge based on the head of water flowing over a crest. They cannot be used inside closed pipes.
- Flumes (such as the Parshall flume) are specialized open-channel structures that contract the flow to create critical depth conditions, allowing discharge to be calculated from water depth measurements. Like weirs, they are not designed for closed, pressurized pipe flows.
- Flow meters (including propeller meters, electromagnetic meters, and ultrasonic meters) are specifically designed to be installed directly in-line within closed, piped irrigation systems.
As water flows through the pressurized pipe, it rotates a propeller or changes an electromagnetic/ultrasonic field, which is calibrated to display the real-time discharge rate and total volume of water delivered.
Therefore, flow meters are the standard device used to measure discharge in piped irrigation systems. Step 2: Final Answer:
The water measuring device used for determining discharge from a piped irrigation system is the flow meter.
