South Dakota: Canal-Based Irrigation System
Campbell Scientific dataloggers regulate automated check gates improving water-delivery efficiency by 84%
The vast tablelands just north of the Black Hills in western South Dakota require carefully monitored irrigation to thrive as agricultural farmland because of its semiarid conditions. The soil north of the Belle Fourche River is sticky gumbo soil that retains water. Without proper drainage, excess water seeps into the subsoils, salts rise to the surface, and the area can no longer be irrigated. The soil south of the Belle Fourche River, on the other hand, is thirsty, sandy loam that requires frequent watering.
In recognition of this region’s complex irrigation needs, the US Bureau of Reclamation established the Belle Fourche Irrigation District (BFID). The BFID is responsible for the care, operation, and maintenance of an irrigation system that delivers water to more than 50,000 acres of cropland using 94 miles of main canal, 450 miles of open lateral ditches, and several dams.
Because this region faces recurring drought, water conservation is critical to ensuring a sufficient, available supply for irrigation needs throughout the District. The BFID sought to reduce its canal-water-level fluctuations, thereby reducing water loss and increasing delivery efficiency. To maintain consistent canal water levels, the BFID’s canal check structures needed to be automated.
The BFID contracted with RESPEC to assist with coordinating the project; advising the BFID; and installing, configuring, and troubleshooting the canal check structures system. In 2006, RESPEC began automating the BFID canal check structures by installing water-level sensors, gate-height sensors, and gate actuators combined with Campbell Scientific dataloggers (CR1000, CR850, and CR200X models). RESPEC has facilitated several automation campaigns for the BFID over the past 14 years. In partnership with Intermountain Environmental, Inc. (IEI) in 2008 RESPEC and IEI installed two thirds of the current 55 automated sites and repeater stations. RESPEC installed the remaining systems and continues to maintain and update the automation infrastructure.
The automated check gates maintain a constant upstream water level throughout the canal system. The preferred water level is sustained by the automated gates moving up and down in response to level fluctuations, and the resultant constant water level promotes more efficient water delivery to farmer turnouts and lateral-head gates. If the water level at a check structure reaches an elevation that is too far out of range for the gate to control, Campbell Scientific’s LoggerNet software is configured to send an alarm notification in a text message to the irrigation personnel.
Several automated head gates work in combination with a flow-measurement structure. When the preferred lateral flow is programmed into the datalogger using LoggerNet, the lateral-head gate adjusts automatically to deliver that flow. The flow is measured either upstream or downstream of the gate using Parshall flumes, long-throated flumes, or constant-head orifice structures. A water-level sensor at the flume relays information back to the Campbell Scientific datalogger and the datalogger adjusts the water level to obtain the desired flow.
RESPEC set up and coordinated an extensive radio communication network across the BFID using RF450 spread-spectrum radios. With this network, selected sites are monitored and controlled in real time from the BFID headquarters in Newell, South Dakota, or from anywhere throughout the BFID using a vehicle-mounted mobile base station.
To assess and quantify the benefit from the automated gates, RESPEC conducted an analysis of the Vale Lateral, which is a major lateral on the South Canal. In 2005, before the check gate automation was implemented, the upstream canal level showed fluctuations greater than 1.0 foot. After the Vale gate was automated in 2006, the canal level showed fluctuations within ±0.05 foot. Based on water-delivery records, the check gate automation improved water-delivery efficiency by 84 percent. In 2007, a real-time automated head gate and sensors were installed on the Vale Lateral flume. The installation provided the exact, programmed amount of water to be delivered down the lateral without any waste. The estimated loss reduction is 3,460 acre-feet per year, which provides more water for distribution throughout the irrigation system or recreational purposes at the reservoir.
Excess canal water that is not delivered to irrigators moves through the system and out the end of the canal in wasteways. During this process, the water picks up sediments from the canal and return flows from the irrigated land. By reducing the volume of excess water, the sediment amount is also reduced and, with less sediment discharged into the adjacent Belle Fourche River, the water quality and fisheries are improved. The recreation potential is also increased at the Belle Fourche Reservoir (home to the Belle Fourche National Wildlife Refuge and Rocky Point Recreation Area).
Since 2006, RESPEC has automated 55 canal check structures using various Campbell Scientific dataloggers and an extensive RF450 radio network. The upgrades to the canal check structures have helped the BFID improve its water-delivery efficiency, continue to meet its irrigation needs, and protect a recreational resource for thousands of annual visitors.