The real power behind the InfoWater Pro Demand Allocator is the Water Duty Calculator which allows engineers to modify water duty factors on-the-fly and see the overall system demands fluctuate accordingly. After you have allocated a demand with the Demand Allocation Manager, the Water Duty Calculator will appear, allowing you to modify water duties to match a known Total Demand. Click on any section to learn more:

Last Allocation Method - Displays the allocation method for this report. 

Allocation Statistics 

  • Usage Type - Usage type refers to the different class/classification types in the InfoWater Pro project as used by the Allocation Manager.

  • Description - The description for each class/classification as entered into the Allocation Manager.

  • Water Duty - Change these factors as desired to generate a Total Demand that matches a known average day water production load. As these values are changed, the Total Demand will update automatically, similar to how a spreadsheet operates. This value is being multiplied by the adjacent acreage to generate to Alloc Demand field.

  • Area - After the demand allocation process, the total composite acreage for each class/classification field is determined and written to the Area field. For example, the value in this field represents the total acreage for a particular land use type in sq. ft.

  • Alloc Demand - The total demand generated for each class/classification. Making changes to the Water Duty field or to the Allocation Scaling Factor will automatically adjust the results in this field. Note: If acreages are in sq. ft. and water duty's are in gpm/acre, use a scaling factor of 1/43560.

Allocation Scaling Factor - Use this box to normalize demand data.  The default value is set to unity (1.0) and may be changed to reflect the actual demand multiplier. It will be necessary to apply scaling factors when water duty factors are expressed in gpm/acre and acreages calculated from a polygon intersection are expressed in sq. ft.  In this instance, use an allocation scaling factor of 1/43560.

Total Demand - This field represents the total demand expressed based on land area and water duty parameters. This field should typically be equal to the total water supplied.

OK - Save and exit the Current dialog box.

Cancel - Close the dialog box.

What is the Purpose of The Water Duty Calculator?

The ability to intersect GIS data sets and allocate demand is integral in today’s master planning environment.  However, the reason these spatial intersections and allocations are conducted in the first place is to load the hydraulic model with a known system demand.  In many instances, the known system demand is generated from water production records which are accumulated over an entire calendar year.

This annual production data is then divided by 365 days (or 366 in a leap year) to generate the Average Day Demand (ADD) which is then used by the engineer to load a hydraulic model.  Spatial intersections allow the model to be loaded according to geographical consumption; however, engineers have traditionally spent many hours attempting to correlate the appropriate water duty factors to match the exact ADD.

How Does the Calculator Work?

The Water Duty Calculator allows you to alter water duty factors as necessary to generate a Total Demand that matches the ADD value from your utility’s production/purchase records. The following represents a work order process of how to use the Demand Allocator and Water Duty Calculator dialog boxes.

  1. Once GIS data sets are ready to intersect, open the Demand Allocation Manager dialog box and assign any known water duty factors. Factors do not necessarily matter as this juncture as the Calculator will be used to modify and refine these values to match a known production value.

  2. Click Save to use the entered water duty factors and allocate demands. By clicking the Save button from the Demand Allocation Manager dialog box, spatial data sets are intersected and their resulting acreages are determined for use in the Water Duty Calculator.

  3. Open the Water Duty Calculator and begin altering water duty factors as desired.  Adjust factors as necessary in order to generate a Total Demand that matches a known ADD value. When all adjustments have been made, click OK to automatically update all water duty factors in the Demand Allocation Manager dialog box with the most recent values entered in the Water Duty Calculator.

  4. Click on the Save button on the Demand Allocation Manager dialog box once again to load the hydraulic model with the new demand values generated from Water Duty Calculator.

Upon completion of the Allocator process, you will have loaded the system model with an average day demand geographically dispersed according to the GIS intersection between two polygon convergence.