Irrigation gate status recorder
By Ted Sammis
The flow of water down an irrigation ditch can be measured using a flume or by measuring the discharge from a well into the cannel using a flow meter. Water flow in a cannel is measured and the water is then diverted into a field by opening gates in the cannel to each field. In order to calculate the depth of water applied to a field, it is necessary to know the time duration that the flow in the cannel is diverted to each field and the area of the field. The area can be determined by aerial photographs or using GPS equipment. The time that a gate (fig. 1) is open to the field can be measured with irrigation gate status recorder . The gate data logger consists of a event recorder (fig. 2) connected to
Fig. 1 Irrigation gate with data logger Fig. 2 Irrigation event data logger.
magnetic switch. The switch (fig. 3) is connected to the side of the gate using silicon rubber and the magnet is connected to the gate also using silicon rubber. The silicon rubber seals the switch and magnet from moisture damage. The switch is a standard magnet switch used in home burglar alarm systems. The event record is a rain gage event recorder that records the date and time that the switch is closed. The magnet is raised when the gate is raised, closing the switch closes and recording an event. As long as the gate is open, no further events are recorded. When the gate is closed another event is recorded. This data along with the integrated flow over the measured time period is used to calculate the water amount diverted into the field. If sets of gates are open for an irrigation event then, one recorder is installed on each set of gates to determine when they are open and closed. The total flow in the ditch must be diverted to one field at a time for the measurements to be accurate.
Fig 3. Switch and Magnet attached to a slide gate.