How to use outlets to remove water on the edges of your project

Situations arise where water should flow out of the project area, when the simulation area is limited. Inlets can be configured as outlets and used to remove this water on the edge of the project. Outlets can be further configured remove water from an area of cells or a single center point cell. Generally, when a cell is flat, an area can be used and when it is not, the single cell should be used. In the later case multiple outlets should be placed, one at each local height map depression on the project's edges.

Two situations on the edge of a project are described;

Removing water on land; either with an outlet as a point or an area
Removing water in a river; using an inlet and an outlet

Removing water on land edge of project

Configuration

Rain: 60 minutes, 30 mm , 2 hours dry. Outlet:

Inlet Q: -10000 ${m^{3}}/{s}$ ; Draining the cell(s) every timestep.
INLET_AREA: Either 0 (as center point) or 1 (as area)
UPPER_THRESHOLD: Upper threshold is optional. When the cell(s) should be drained completely, this value can be omitted.

Placement

An Outlet is placed as a point by default, but can be placed as an area. On sloped terrain, this can be an issue.

Placed as an area
Placed as a point

The reason why water remains is because when an Outlet, is because hydraulic structures configured as an area require an area datum height. The height selected currently is the highest datum values of the cells. This is clarified in the image below:

Surface Water removal on a slope

As can be seen below, water is removed by an outlet in both situations. For the drainage speed of the sloped terrain, both situations are quite similar. However, in the case of an Outlet as an area, water remains at the lowest point.