While a reservoir element conceptually represents a natural lake or a lake behind a dam, the actual storage simulation calculations are performed by a Routing Method contained within the reservoir. Five different Routing Methods are available. The Outflow Curve Method is designed to simply represent the reservoir with a known storage-outflow relationship. The Specified Release Method uses a specified discharge from the reservoir and computes the storage that would result. The Outflow Structures Method is designed to represent individual components of the outlet works. The Rule-Based Operations Routing Method extends the outlet works components to also allow for rule-based operations of gates within those structures. There is also a choice for the None Routing Method. This option assumes no storage in the reservoir and all inflow is passed as outflow for each time interval of the simulation.

The Routing Method for a reservoir is selected on the Component Editor for the reservoir element. Access the Component Editor by clicking the Reservoir Element icon on the Components tab of the Watershed Explorer. You can also access the Component Editor by clicking on the element icon in the Basin Map, if the map is currently open. You can select a Routing Method from the list of five available choices (Reservoir Elements, see figure). Use the selection list to choose the method you wish to use.

The parameters for each Routing Method are presented below the method selection list. The exact parameter data displayed in the Component Editor depends on which method is selected. Some parameters are common to more than one Routing Method. However, all possible required and optional data for each Routing Method is described in the following sections.