The Drain Elevation category is dependent on the Horizontal and Horizontal and Vertical Gradient Seepage methods. Each Reach may have horizontal seepage to multiple drains or shallow groundwater aquifers, each of which can have unique drainage characteristics. Drain related slots are designed so that users can add columns to provide information on each drain present. A drain may be a man-made drain or groundwater.

None is the default for the category, and will result in an error if it is selected and a run is started.

This method allows you to set a constant drain elevation.

This method allows you to specify the drain elevation at each timestep.

This method calculates the drain elevation based upon flow through the drain (this method should be used only when drains are man-made as flow is unavailable for groundwater). A table interpolation of the Drain Flow vs Drain Elev table gives the elevation.

This method should be used when the drain or groundwater elevation depends on the Reach Avg Stage (water surface elevation). It calculates the drain elevation based upon a specified table relationship of Reach Avg Stage and Drain Elev. You can also include a time lag using the Drain Time Lag slot representing a lagged relationship between the Reach and drain elevations.