Customer Water Delivery Measurement Investigation


Owner: Reclamation District No. 108
Colusa and Yolo Counties
Funding Source: Operations Budget
Estimated Completion Date: Fall of 2012

Reclamation District No. 108 (RD 108, District) is located along the western edge of the Sacramento River and delivers water to nearly 48,000 acres of farmland within southern Colusa County and northern Yolo County. RD 108 receives water from the Sacramento River under riparian water rights, licenses for appropriation of surface water, and a Settlement Contract with the U.S. Bureau of Reclamation. The first irrigated crops were grains, primarily barley, but today include rice, wheat, corn, safflower, tomatoes, beans, specialty seed crops, cotton, walnuts and fruit.

Stemming from the Water Conservation Act passed by the California legislature in 2009, California Water Code Section 597 (CWC §597) requires that certain agricultural water suppliers, including RD 108, measure the volume of water delivered to customers with sufficient accuracy to: (1) report aggregated farm-gate delivery data to the state and (2) adopt a pricing structure based at least in part on the volume of water delivered to each field. The District is conducting technical investigations to provide a basis for developing a customer delivery measurement plan that will comply with accuracy regulations approved in July 2012. Toward that goal, RD 108 engaged the services of Davids Engineering to pilot test three alternative measurement methods during the 2012 irrigation season, each one potentially capable of achieving the new accuracy standards.

Figure 1. Cross Section of typical farm turnout showing locations of three alternative flow measurement methods

The measurement methods include: (1) existing orifice farm delivery gates, (2) weirs set in precast boxes downstream of farm delivery gates, and (3) a recently introduced device called the RemoteTracker installed in the farm delivery outlet pipe (Figure 1).

The third measurement method, the RemoteTracker, was developed specifically to address the particular flow measurement challenges in RD 108 but is applicable wherever similar measurement challenges are encountered.  These challenges includes very small head differentials between supply canals and irrigated fields and very wide ranges in water delivery rates, in some cases between 1 and 30 cfs. The RemoteTracker consists of a portable, self-locating, data logging and wireless enabled acoustic Doppler velocimeter (WADV). The WADV is deployed in irrigation turnouts while flows are being set, adjusted or checked.

RemoteTracker and Panasonic Toughbook deployed for initial testing in dry lateral.

Davids Engineering began the pilot project by making various modifications to the RemoteTracker system. First, the user interface was modified to facilitate the manual entry of weir and orifice gate flow measurement data. Second, the RemoteTracker WADV rod was customized to fit different weir box heights. Finally, a CSV file was developed containing all the pertinent measurement data for each customer delivery in the study area, including latitude/longitude, field name, turnout pipe size and length, and other parameters.

Once the necessary modifications were made, the RemoteTracker system was implemented in a selected canal reach that includes 20 gravity deliveries and three pump deliveries. Implementation included several staff training sessions and subsequent user interface customizations. Davids Engineering then developed an automated process to forward new flow measurement data from the Toughbooks in the field to a centralized data server located at the District office. The automated process utilizes the Verizon wireless wide area network (WAN), and pushes new data from the Toughbooks to the District server on a user definable interval (currently configured at 1 minute).

The pilot test revealed that existing weirs are not be able to achieve the new accuracy standards but that both existing delivery gates and the RemoteTracker are. The District has selected the RemoteTracker for District- application due to the advantages it offers with respect to data consistency and labor savings.

Panasonic Toughbook mounted in operator vehicle

A customized Microsoft Access database was created to automatically process and quality control the raw measurement data. The custom database calculates monthly flow volumes for each turnout gate included in the pilot study utilizing flow measurement data from each of the three measurement methods.

The final task of the pilot study will be to perform a water balance on the pilot canal reach to determine which of the three measurement methods provides the most accurate flow measurement data. Flow measurement records from two Rubicon FlumeGates, one at the heading and one at the spill, will be used to bound the inflows and outflows from the water balance area. A brief technical memorandum will be developed to document the results and provide guidance for Phase II of the District’s turnout measurement efforts.