Diversion-Runoff Calculator User Manual

The Diversion-Runoff Calculator (DRC) generates time series data and associated plots. These both contain observed canal flow rates (Qobs) at the headgate and the expected water that would be required in the canal to supply irrigation water to the crops based on calculated water demand and assumed system efficiencies. The calculated diversion flows are provided based on consumptive use ET Tables (QET Table) from Hill (1994) and from remotely sensed OpenET (QOpenET) data.

The DRC generates a number of different files highlighted below.

The DRC creates two "temporary" files. 'TempOutFile_CanalNames.txt' lists the flowline IDs associated with each stream/canal. This is used for troubleshooting these associations. 

The 'TempOutFile_NodeIDs.csv' file stores the extents of each irrigation node. The DRC checks to see if the TempOutFile_NodeIDs.csv exists before parsing the NetFieldsRAST file. If the file already exists, the DRC reads it into memory to save time. If the NetFieldsRAST file is ever edited, the previous TempOutFile_NodeIDs.csv should be deleted so that the DRC rebuilds this file with the updates included. Barring any changes to NetFieldsRAST, the TempOutFile_NodeIDs.csv is recommended to reduce runtime. 

The MassBalance.csv file provides the total diversion volume, total crop water consumption, and total seepage and runoff volumes for each canal listed in the input file. This file provides an overview of the water partitioning through each canal. 

More importantly, the MassBalance.csv file supplies an a priori condition to initialize each subsequent simulation. The DRC looks for this file in the working directory and uses it to initialize the model if the file exists. The DRC will run even without this file, but the absence of prior information on the amount of water in each canal will result in slightly different answers for the seepage calculations. 

The DRC estimates seepage and runoff from fields to other fields, and also back into canals, ultimately ending up back in the natural river system. These return flows are a component of the water budget into the river system. The River_LocalInflows.csv file aggregates these return flows according to the return flow groups specified in a 'ReturnFlow' field appended to the NetFlowlinesSHP shapefile/feature layer. These can be grouped any way the user chooses. However, for integration into another water budgeting software like RiverWare, the groups typically consist of portions of the natural river system that drain to a specific point, usually a stream gage, in order to account for local inflow. Return flows in the River_LocalInflows.csv file represent the average monthly inflow in cubic feet per second (cfs).

The WaterRightsForEachMainCanal.csv file lists individual water rights and the respective acreages and priority dates for each main canal. This information is used in drought mitigation scenarios with various water budgeting tools, or for evaluating change cases within the DRC. 

The Diversion-Runoff Calculator (DRC) generates time series data representing expected canal losses, crop water consumption, and diversion flows for individua canals. This information is written to the 'Output_Exel' folder. 

Plots are generated comparing the observed canal flow rates (Qobs) at the headgate when available with the amount of diversion flow expected to be required to supply irrigation water to the crops based on calculated water demand and assumed system efficiencies. The calculated diversion flows are provided based on consumptive use ET Tables (QET Table) from Hill (1994) and from remotely sensed OpenET (QOpenET) data.

Graphs comparing Qobs against QET Table and QOpenET are saved in the 'Output_Figures' folder. The y-axes in the graphs are in acre-feet per month. Qobs is calculated by taking the monthly median flow value (cfs) of the observed data and converting it to acre-feet per month similar to what is shown below:

The “GraphFlow” function in the Python code is used to create both graphical and tabular outputs. Graphs are created for every canal included in the MainCanalList and the Secondary_CanalList. 

In addition to individual files for each canal, the simulated and observed time series are combined into a single file called 'CombinedDiversionDepletion.csv' also written to the Output_Excel folder. The headings 'Canal_Name.Observed (cfs)' corresponds to Qobs and 'Canal_Name .Simulated (cfs)' corresponds to QET Table or QOpenET depending on which CombinedOutput_UtahTable0_OpenET1 flag is set. This combined output file is intended to be machine readable in order to pass diversion flows into other water budgeting tools. Aggregation specifically for RiverWare© is described in the section on RiverWare Integration. This generates yet another file called 'ObservedAndDRCDiverisions.xlsx'.

Similarly, canal losses are also compiled into a single file called 'CombinedLosses.csv'. When RiverWare© aggregation is turned on these get aggregated into their own worksheet within 'ObservedAndDRCDiverisions.xlsx'.

The DRC can perform scenario-based simulations to evaluate proposed changes in landuse, crop type, irrigation practice, canal lining, and field fallowing. The user specifies whether to run the standard baseline scenario, or a change case that includes modifications. This is done by setting the 'BaseOrModifiedScenario' flag to 1. Change cases are described in more detail in the Change Case Section. 

Since the change case is essentially a separate run, the DRC writes new mass balance, return flow, and water rights output specific to the change case. The new output files have the suffix '_ChangeCase' appended to their filename. This avoids overwriting existing output associated with the baseline scenario. 

An additional change log file called 'ChangeLog.txt' is written to the working directory. The additional files assocaited with a change case are highlighted below.