Water Balance, Flow Measurement and On-Farm Conservation


Owner: South San Joaquin Irrigation District
San Joaquin Valley, California
Funding Source: South San Joaquin Irrigation District
Completion Date: Ongoing

Improved flow measurement device in SSJID drain

The South San Joaquin Irrigation District (SSJID or District) is gradually improving its water management capabilities through a package of integrated on-farm and District level improvements. Davids Engineering has supported the District’s efforts on a number of fronts. In 2009, Davids Engineering completed a District water balance analysis with three objectives:

  1. Provide insights into management practices at the District and farm levels to serve as a basis for reviewing existing operations practices and policies.
  2. Assess the District’s overall water supply adequacy and identify water conservation opportunities.
  3. Assess water measurement practices and accuracy and recommend measurement and associated data management improvements.

The water balance revealed the need to (1) expand the District’s measurement network and improve flow measurement accuracy, and (2) improve centralized storage and management quality controlled flow measurement and related water management data. The District began addressing these needs in 2010 by engaging Davids Engineering to develop a Flow Measurement Plan (Plan).

Eighteen sites were inspected and 14 selected for measurement improvements phased over a three-year period.  Additionally, the Plan included a Pilot Delivery Measurement Program to assess the accuracy of deliveries made to District customers, identify potential new delivery measurement approaches, and determine the required investment to comply with new State regulations (SBx7-7).

Also in 2010, Davids Engineering assisted the District with formulating an on-farm water conservation program. Based on the plan, the District’s board of directors approved $1.25 million in funding for implementation in 2011. The program, currently in its second year, provides financial incentives to District growers to implement three types physical improvements: 1) improved delivery measurement, 2) conversion from traditional flood irrigation systems to sprinkler or drip systems, and 3) tailwater recovery systems. Two management improvements were also funded, including scientific irrigation scheduling and soil moisture monitoring.  The program won the California Public Utilities Conservation Award in March of 2011.

Pilot test of magnetic meter for improved measurement of pumped farm deliveries

During 2011, rating curves were developed for Woodward Reservoir Outlet and Valley Home flow measurement sites on the District’s Main Distributary Canal. Additionally, Davids Engineering supported installation of upgraded measurement equipment by District staff at Drain 11 and the FCOC Drain.

The 2011 Pilot Delivery Measurement involved a detailed inventory of the different conditions under which customer water deliveries are made by SSJID and piloting of alternative measurement approaches matched to those conditions. Based on the 2011 findings, the effort was scaled up in 2012 to a “proof of concept” test of a unique differential measurement approach that accomplishes customer delivery measurement without making expensive physical modifications to the distributions system. Davids Engineering is currently assisting the District with installation of sensors, analyzing test delivery data and developing a delivery measurement plan to be included in the District’s 2012 Agricultural Water Management Plan.