A growing population and competing demands for limited water resources prompted California-USA to pass the Water Conservation Act. In addition to a 20% reduction in per-capita urban consumption by 2020, the law required agricultural suppliers to “implement efficient water management practices” and volumetric pricing. With a state-wide assessment of water use underway, the South San Joaquin Irrigation District (SSJID) Board of Directors realized the issue posed a potential threat and approved the Division 9 pressure system upgrade to demonstrate that the district is proactively addressing California’s conservation goals.

The SSJID historically delivered water to farmers through 400 miles of gravity-based canals and pipelines. Farmers drew from the network of laterals at scheduled times via flood irrigation or private pumps used for sprinkler or drip systems. While the system worked well for flood irrigation, the combination of flood and sprinkler usage on a single system became problematic. As a result, some customers did not buy water from the SSJID, opting instead to draw from their private, salinity-stricken wells. With the new pressure system, the customers increased and efficiency was improved.

The newly approved Division 9 pressure system efficiently managed water delivered by reducing water needs by up to 30% and accounted for water use through magnetic flow meters at each customer connection.

A portion of one of the district’s nine divisions – 1537 ha in Division 9 – was chosen as the site for building, testing, and optimizing a pilot pressure irrigation project. The vision for the system included the following fundamental capabilities:

Pressurization – pumping water from a 56-acre-foot pond to individual farms through 19 miles of pressurized pipeline

Calculated use – letting farmers choose the time, volume, and flow rate of deliveries

Automated/mobile access – developing a web-based tool that allows farmers to schedule deliveries from a computer, smartphone, or iPad based on current and past weather forecasts, previous water usage and historical evapotranspiration rates, and orchard moisture sensors.

The project consisted of a 19-mile network of pipelines with flexible pressurization (currently set at 60 psi), a 56-acre-foot water storage basin, a 1,225- hp (913482 W) pumping station containing seven vertical turbine pumps capable of pumping a total of 23,500 gal/min (52.4 ft3/s), and a total of 55 solar-powered Field Telemetry Units or FTU’s controlling 77 customer connections. The FTU consisted of a PV panel, a flow control valve, and meter, and a radio-based supervisory control that communicates with a data acquisition (SCADA) system in the pump control room.

With the Division 9 pressure system, each customer had one connection point, with a magnetic flow meter to measure and transmit water deliveries; historic data are automatically stored on the district’s server for uploading into the district’s billing software.

With the new system, irrigation water was distributed to the customers across 3,800 acres of California’s Central Valley through an automated channel. Using an online system similar to an airline ticketing platform, growers were able to login and schedule water deliveries. Additional information on current and past weather forecasts, previous water usage, historical evapotranspiration rates, and real-time moisture sensor readings were also available on the website. Each farmer selected from available delivery dates and received alerts via email and text message before and after delivery to confirm volume and flow rate data. To promote efficient water usage, moisture sensors placed in the ground on each grower’s property indicated optimal ordering times when orchards were at their greatest need.

The survey revealed that the customers received irrigation water at the exact time, flow rate, pressure, and duration they needed. In addition, the reduced number of customers using the gravity system allowed the flood runs to be accomplished faster and more efficiently, with less stress on the previously overloaded gravity system and reduced long-term maintenance costs.

The survey data indicates as follows:

With the Division 9 pressure system, Farmers were able to irrigate based on surface water availability and crop water requirement, at the exact flow rate and duration they desired. With the pressure system upgrade, the district proactively addressed California’s conservation goals. The system efficiently managed water delivered by reducing water needs by up to 30%. The farmers in the SSJID service area have historically been charged a flat rate of 24 USD/acre for irrigation water. A typical 40-acre orchard has numerous valve structures to flood irrigate the land. This posed a difficult and expensive challenge for the district to comply with due to the thousands of exit points off of the gravity system. However, in the new system, each customer has one connection point, with a magnetic flow meter to measure and transmit water deliveries. The historic data are automatically stored on the district’s server for uploading into the district’s billing software, complying with the Water Conservation Act.

The district’s fixed, the 10-day delivery schedule does not provide an optimal water supply at the frequency needed to maximize crop yield. The system’s East Basin Pump Station doubled as a regulating reservoir, storing and pumping irrigation water to 77 customer connections on an on-demand basis, the pressure system induced a demand to convert from flood irrigation to sprinkler/drip application methods. Of the 77 customer connections in the system, 18 installed sprinkler or drip systems immediately after the pressure system was available to serve their land. The increased use of sprinkler/drip increased the irrigation efficiency of the farming operation and contributed to the goal of maximizing beneficial use of the district’s water rights.

The system tapped into abundantly available solar energy in the region to meet the power demands of all of the customer connections. The solar system powered the solenoids of the flow control valve, magnetic flow meter, moisture sensors, process logic controller, and radio communications to operate the turnouts and provided real-time information on flow rate, crop moisture conditions, turnout pressure, control, and battery component status, and delivery details (start time, end time, total hours irrigated, average flow rate, total water delivered).

The ten-year average water supply (2002-2011) to the Division 9 pressure system customer base has been 7,528 acre-feet. The summation of water deliveries (calculated via magnetic flow meters at each customer connection) through the pressure system for the first year amounted to 4,695 acre-ft. Thus, a 2,833 acre-ft conservation has been achieved.

On a water delivered per acre basis, the savings magnified because 50% of the customers of the pressure system were using their wells before the pressure irrigation system. Now, the District was able to re-enrol these farmers and reduced groundwater pumping while higher quality surface water use increased. Before the pressure system, 19,924 acre-ft of water was delivered to Division 9 to support 3,151 acres, or 6.32 ft of water per acre. Water deliveries for the pressure system customer connection for the 2012 irrigation year amounted to 4,695 acre-ft to support 2,389 acres, or 1.96 ft/acre of water. The system reduced the acreage pumping from the groundwater aquifer by 50%. Groundwater pumping in the area was primarily conducted using diesel-driven pumps. The reduction in diesel emissions improved the air quality, and the high-quality surface water improved crop (primarily almond and walnut orchards) health.

Farmers participating in the pressure system used the direct injection of fertilizer at their filter stations and delivered chemicals directly to the root zone area; thus reduced the deposition of fertilizer in the local surface and groundwater.

To provide a manageable pressure system for both the SSJID and the customers, a user-friendly software interface was developed. Tools at the farmers' fingertips to plan their irrigations included national weather service alerts for the area (including frost and wind alerts), weather forecasts, Doppler radar imaging, customizable and exportable/printable charts on past weather (rainfall, wind, temperature, humidity, evapotranspiration rates), water deliveries (time start, time end, total hours irrigated, average flow rate, and total water delivered), and moisture sensor information.

Although data evidence on the increase in yield due to the Division 9 pressure system will take some time, other case studies reveal that farmers will see a 30% increase in yield. With increased control of irrigation timing, duration, and application rate, there has been a marked decrease in pests and diseases associated with water delivery. A major benefit was the consolidation of pumping operations.

Due to the new surface water-based pressure system, there was a considerable reduction in the pumping of salinity-stricken groundwater. Farmers reduced flood irrigation and utilized drip, micro, and solid-state sprinklers to irrigate their land which improved crop yield, conserved water by up to 30%, and reduced erosion and deposition of fertilizer into local surface and groundwater.

The pilot project showed a marked benefit over the conventional system therefore the same can be extended and replicated to other areas as well.

Willow Creek basin is adjacent to Willow Creek and the Malheur River in Vale Oregon Irrigation District, USA. Earlier, the irrigation water was delivered to users from the main canal through a complex network of open earthen ditches, established in the 1930s. These open canals dealt with increasing concerns associated with breaches as well as human and animal safety. They also substantially increased operation and maintenance costs.

To manage the situation, the Willow Creek Piping Project addressed 35,000 acres (14,164 ha) in the agricultural area and simultaneously worked on water quality and water conservation concerns. Piping irrigation laterals facilitated on-farm conversion to sprinklers, reduced the need for hydro-power, tillage, and fuel usage, conserved water, improved fish habitat, and benefitted the local economy.

Some of the major transformations in the Willow Creek Piping Project are listed below:

• The piped irrigation virtually eliminated conveyance losses from seepage and evaporation from the open-ditch delivery system and improved the efficiency of water use on the farm.
• The pressurized system made switching from flood irrigation to sprinkler irrigation easier, more cost-effective and reduced the need for additional power.
• Sprinklers improved the irrigation application efficiency, reduced tillage needed for crop production, and decreased crop consumptive use.
• Other on-farm conservation methods included pump back systems which captured the irrigation runoff from crop fields and enabled multiple re-uses of irrigation water.
• Piped irrigation system provided gravity pressurized water to irrigators and decreased power costs by reducing or eliminating the need to operate irrigation pumps. It improved reliability, control, and consistency of water delivery and measurement.
• Reduced operations and maintenance requirements and created opportunities for small "low-head" hydro-power facilities.
• Ultimately, it utilized irrigation water more effectively without increasing consumption.

Before the implementation of the Willow Creek Piping Project, a significant amount of water was lost from seepage and evaporation, especially at the beginning of the five to seven-month irrigation season when the canals were dry.

Calculations from the Vale Oregon Irrigation District showed that before the piping project, the first irrigation month’s water loss averaged more than 90% and rarely dropped below 30%. These issues were exacerbated in years when runoff reached below normal levels. In the high-desert region, the average rainfall was 10 inches per year. In low water years, the irrigation district did not receive sufficient water to meet all crop demands.

However, under the Willow Creek Piping Project, simply placing piping and burying open laterals prevented virtually all water loss from seepage and evaporation and enabled efficient delivery quantities and measurement. The piping project added USD 6.5 million to the state and federal grants funds to assist local farmers and ranchers in implementing better management practices that protect natural resources, conserve water and improve the water quality in rivers and streams. This project directly provided employment and opportunities for local businesses. In addition, yield increased due to efficient sprinkler irrigation and increased revenues to producers, which in turn helped the local economies of Vale and Ontario. These benefits lasted more than the lifetime of the project.

Willow Creek Piping Project essentially replaced the open canal conveyance system with piped irrigation system. This technique can be adopted globally as a water-saving measure. It not only leads to water conservation but promotes environmental sustainability and reduces the dependency on electricity and fossil fuel requirements.

Keywords: irrigated agriculture; user charges; market trades; water user associations; socioeconomic transformation; South Africa

Presented at: 58th IEC Meeting 2007, Sacramento, USA