A direct discharge structure is a structure which is not represented by its geometry, but instead directly by the discharge flowing through it. This type of structure may for example be used when a regulation is to be applied directly to the discharge, and not to e.g. a gate level.
The Direct discharge menu contains some attributes of the structures, while the control rules regulating it are defined under the Control menu.
Under the General tab the following types of information must be specified.
Location
ID. String identification of the gate. ID will be used in structure results and hence makes it easier to identify a specific structure if setup contains many structures, or if multiple structures are defined at the same location.
Branch name. The Branch name of where the direct discharge is located can be chosen from the drop down list.
Chainage. Chainage at which the direct discharge is located.
Type. The location type may be defined as Regular, Side structure or Side structure with storage. See section Structure types definition (p. 114) for details.
Geometry
No. of structures. Number of identical parallel discharge structures. When multiple structures are included, the control rules define the discharge through a single structure. This discharge is then multiplied by the number of structures.
Attribute
Max. discharge change. This variable defines the maximum allowable change in discharge per time. This variable may be used to avoid very rapid changes of discharge. Such rapid changes may happen with some control rules whereas they wouldn't be realistic and could create instabilities in the computation.
Initial discharge. The value specified will be used as initial discharge at the beginning of the simulation.
Min. discharge. This value is the minimum discharge through the structure.
Max. discharge. This value is the maximum discharge through the structure.