River Headflow

Headflow represents the average inflow to the first node on a river. Headflow can be specified either (1) as originating from a Catchment, with values calculated by the Simplified Coefficient or Soil Moisture Methods (see Overview of Catchment Calculation Methods), or (2) with values directly input with the Water Year Method, the Read from File Method, or an Expression (See Specifying Hydrologic Inflows for details). Note that if you select a Catchment as a headflow source for a river, then under the Headflow variable tab for that river, it will be set/locked to "Inflow from Catchment". You will not be able to enter additional headflow values for that river with the other methods.

With the direct input methods (such as the Read from File Method), the monthly inflows you enter should not include return flows from demand sites and wastewater treatment plants -- WEAP will calculate the inflows from return flows separately.

Linking flows from one WEAP area to another

If you have another WEAP model that represents the area upstream of your dataset, you may want to set the headflow of your river to be the outflow from a river in the upstream model.  Whenever WEAP calculates an area, it automatically creates additional CSV files containing the outflow from all unconnected rivers and diversions, one for each river and scenario.  The files will be named  Result_S<ScenarioID>_<ScenarioName>_RiverOutflow_<RiverName>_<YearRange>_<Timestep>.csv,  e.g.,  Result_S02_Reference_RiverOutflow_Weaping-River_2010-2020_Monthly.csv.  In order to link the outflow from an upstream WEAP area "A" to an inflow point in downstream WEAP area "B," you would create a river object in area B to represent the lower most river from area A, and give it the same name.  Go to the headflow data variable in area B for the new river and open the ReadFromFile wizard.  Browse the folder for area A and choose the CSV file with the river outflow results.  Because the names are descriptive, it will be easy to choose which file is correct.  The ReadFromFile wizard will read and display the CSV data, so it will be easy to verify that it has the correct years and units.  Do this linkage for each scenario in B.  If the timestep in A is smaller than in B, e.g., A is daily and B is monthly, WEAP will automatically aggregate the A results for use by B.

Entered on: Data View, Branch: Supply and Resources \ River \ <River Name>, Category: Inflows and Outflows, Tab: Inflow