Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 22, 2010
Publication Date: July 1, 2010
Citation: Clemmens, A.J., Strand, R.J. and Bautista, E. (2010). Routing Demand Changes to Users on the WM Lateral Canal With SACMAN. Journal of Irrigation and Drainage Engineering 136 (7) 470-478. Interpretive Summary: Canals operate very differently from pressure pipelines, commonly used for domestic water supplies. When a farm delivery gate is opened, the inflow to the canal does not automatically increase to match outflow through the delivery gate. If the flow change is too large, the canal will simply be dewatered. For most canals, canal operators need to know that the farmer wants a change in flow rate. Then they can change the flow through the canal head gate to match the farmers demand change. Flow changes at the canal head gate take time to travel through the canal to the farmer’s delivery gate. Thus, the change at the canal head gate has to occur well before the change in delivery is made. Estimation of this delay time is referred to as routing. This paper describes the procedure used to route flow changes through a canal based on canal storage water volume. This method is implemented in computer software: Software for Automated Canal Management (SacMan). Examples are shown where the procedure is used to automatically adjust canal gates on the WM Canal at the Maricopa Stanfield Irrigation and Drainage District. These results will be of use to irrigation and large water districts, the Bureau of Reclamation, and consultants.
Technical Abstract: Most canals have either long travel times or insufficient in-canal storage to operate on-demand. Thus, most flow changes must be routed through the canal. Volume compensation has been proposed as a method for easily applying feedforward control to irrigation canals. SacMan (Software for Automated Canal Management) includes both feedforward routing with volume compensation and distant downstream water level control. SacMan was implemented on the WM canal of the Maricopa Stanfield Irrigation and Drainage District, Stanfield, AZ. Field testing was conducted for a 30 day period during 2004 where more than 50 deliveries to users were made. With feedforward control, wave dispersion, flow rate errors, and timing errors can cause water levels to fluctuate. Downstream water level control can be an effective method to overcome the limitations of this simple flow routing. This paper presents results from these field tests and demonstrates the degree of water level control achievable with this combined feedforward (routing) - feedback scheme.