Overview of Demand Calculation Methods

Several options exist to input and calculate demand within WEAP. For a particular demand site branch within the Data Tree, you can click on the "Advanced" button at the top of the Data Entry window to select among the following options:

(1) Monthly Demand - this option allows you to input month by month demand values for the demand site, or you may use the ReadFromFile function to read in monthly demands from a file.

(2) Annual Demand with Monthly Variation - this option allows you to express demands on an annual level. It requires you to input an activity level (e.g., number of people) and a water use rate associated with that activity level (e.g., an annual volume used per person). Monthly variation can then be described either with some user-defined expression or variation weighted by days in each month. If you want the monthly variation to differ by branches within a demand site, WEAP can accommodate this--just go to the main menu at the top of the schematic, select General, Basic Parameters to indicate this option.

Losses, reuse, and efficiency are accounted for separately. Water demand is calculated by multiplying the overall level of activity by a water use rate. Activity Levels are used in WEAP's Demand analysis as a measure of social and economic activity.

Note: Agricultural irrigation demands can either be calculated using activity levels and water use rates as described above, or by simulating catchment processes such as evapotranspiration, runoff, infiltration and irrigation demands. See Overview of Catchment Calculation Methods for more information.

Entered on: Data View, Branch: Demand Sites, Category: Advanced, Tabs: Methods