Large irrigation district adds low-maintenance Doppler sensors to its monitoring mix

West Texas cotton field being irrigated under a blue sky.

Overview

Seeking a flow monitoring alternative for areas where mechanical meters were problematic, the Central California Irrigation District found an affordable and reliable solution with Mace AgriFlo XCi meters and Doppler insert velocity sensors.

Challenge

From its point of origin at Jones Pumping Plant, the 117-mile long Delta Mendota Canal in central California delivers water from the Sacramento-San Joaquin Delta to the Mendota Pool in the San Joaquin Valley, where it travels through a 500-mile network of gravity-fed canals maintained by the Central California Irrigation District (CCID) to its final destination: the fields of more than 1,600 central valley growers.

CCID is charged with monitoring hundreds of turnouts, making sure irrigation water arrives at its destination unimpeded and canal operators have the information they need to anticipate demand through the growing season.

For decades the district largely relied on mechanical propeller meters to monitor flow at diversion points along the canals. The meters were readily available and typically performed well. But at several locations, routine maintenance was required to ensure the propeller meters performed to district standards.

AgriFlo XCi installed at an irrigation canal turnout. Credit: In-Situ

Solution

CCID sought a suitable alternative to monitor flow in sub-surface, reinforced concrete pipes ranging in size from 24 to 72 inches. They found what they were looking for in the Mace AgriFlo XCi and Doppler Insert Velocity Sensor. The sensor uses continuous-wave, advanced-spectrum Doppler to “see” velocity through the entire cross section of the pipe and calculate a true average flow rate.

To date, CCID has installed about 20 AgriFlo Series 3 meters, and about half of them monitor three sensors from a single box. At two canal-control locations, CCID went a step further and added a telemetry interface card with a Modbus output that integrates with the district’s SCADA system. A PLC regularly interrogates the meter for data and sends it to the SCADA, where it can be viewed in real time.

Canal staff and growers interact with the other AgriFlo units at the local level, collecting accurate data right off the meter. Because the sensors are inserted into the pipes underground and the AgriFlo boxes are contained in mounted electrical enclosures, the equipment is virtually maintenance free and protected from weather and vandalism.

Dopper Insert Velocity Sensor. Credit: In-Situ

Results

Installation of the below-grade sensors can require more effort upfront than propeller meters. However, propeller meters often demand more frequent field visits, and electric meters typically have heavier maintenance schedules. In contrast, the Doppler systems provide the accuracy needed with minimal ongoing maintenance and have proven to be a reliable alternative.

Water supply ranks high among California’s environmental concerns, and CCID makes a concerted effort to demonstrate responsible management of the resource.

With the recent passage of state legislation requiring a higher degree of accuracy in water measurement, CCID is well-positioned to meet those more stringent requirements and serve as a model for the state.