Unless you only want to model dam overflow, you will need to add one or more outlets to the dam to enable water to pass through it into the downstream system.

Outlet types available in ResSim include:

  • Controlled Outlets can be used to represent any outlet that has some mechanism, like a gate or valve, which can be used to adjust the release capacity of the outlet.
  • Uncontrolled Outlets can be used to represent any outlet whose release capacity cannot be adjusted; i.e. it is always fully open (e.g., gates, valves)
  • Power Plants are a special type of controlled outlet that can be used to represent a hydropower generation facility fed by a reservoir (e.g., weirs, culverts).
  • Pumps are another special type of controlled outlet that can be used to represent a pump or the "reverse" half of a reversible turbine in a pumpback system.

The other release elements that are available in ResSim include:

  • Outlet Groups are used to combine one or more outlets so that they can be operated together as a single unit.
  • Diverted Outlets are a combination of an Outlet Group and a Diversion. Diverted outlets are schematic elements. You create them from the map display area in the same manner as you create a diversion. You cannot add a diverted outlet to the reservoir through the Reservoir Editor, but you can edit it, including adding and removing outlets and other elements and defining the routing properties of the diversion.
  • Leakage is a loss of water from the reservoir pool that passes "through" the dam into the downstream system.

In addition to release elements, the following dam elements allow you to define certain properties of the dam, outlet, or group:

  • Tailwater Elevation is a feature you may need add to the dam or an outlet so that it can compute head, the difference between pool elevation and tailwater, for the purpose of computing power generation or determining the ability to pump.
  • Forebay Head Loss is a feature you can add to the dam or an outlet so that it can adjust the current pool elevation to reflect the elevation of water at the face of the outlets for the purpose of computing release capacity.

Like the Pool, there are two ways to add outlets and other elements to the Dam:

  1. from the Dam menu or
  2. from the Dam's context menu in the Reservoir Tree.

Each menu shown in "Figure: The Reservoir Editor's Dam Menus" provides the same list of options for adding and renaming dam elements. For simplicity, we'll focus on use of the context (right-click) menu.

Figure: The Reservoir Editor's Dam Menus

To add an outlet or other element to the dam:

  • Right-click on the Dam to which you want to add the outlet or other feature.
  • Select the outlet type or property you want to add from the context menu. The menus illustrated in "Figure: The Reservoir Editor's Dam Menus" show the various outlet types and dam elements that you can add to a dam.

  • The new outlet or feature will appear in the Reservoir Tree as a branch beneath the dam or outlet group you selected.

    Pulse Flow Options is a Dam menu option that is not discussed in this chapter. It is an advanced option needed for effective downstream control operation and is described in "Pulse Flow Options".