You can use the Catchment Properties tab to change the Reference Pipe Network Structure. The Catchment Properties tab also displays several read-only properties for the catchment.
General Properties
General Properties
- Area. Displays the calculated area of the catchment.
- Runoff Coefficient. Specifies the runoff coefficient for the catchment. Acceptable values are between 0.01 and 1.00. A runoff coefficient is used when calculating runoff with the Rational methods.
- Discharge Point. Displays the specified discharge point of the catchment. If you defined the flow path from a polyline, this is the downhill end point of the selected flow path polyline. If you defined the flow path from a surface, this is the discharge point you selected in the drawing.
- Hydraulically Most Distant Point.
- Exclusionary. Specifies whether a catchment will exclude other catchments.
Exclusionary catchments exclude any other catchments within the same Catchment Group whether the other catchments are exclusionary or not. If a catchment is exclusionary, its boundary (and flow path) can be modified either by existing catchments as it is being created or by new catchments as they are being created.
As a catchment is created, it will check all other catchments within the same Catchment Group for two situations:
- If another catchment is exclusionary, and if the new catchment has some (or all) of its boundary within it, the other exclusionary catchment will exclude the new catchment from itself.
- If the new catchment is exclusionary, and if the other catchment has some (or all) of its boundary within it, the new catchment will exclude the other catchment from itself.
- Reference Pipe Network. Displays the name of the pipe network that contains the pipe network structure you select in the Reference Pipe Network Structure list.
- Reference Pipe Network Structure. Optionally specifies the pipe network structure to use as a reference for the catchment.
Note: Catchments can be associated with a single pipe network structure. The reason for making this association is to enable catchment data to be exported to Storm and Sanitary Analysis. When catchments are associated with a structure, they can be exported and converted into a Storm and Sanitary Analysis subbasin. With no association, however, catchment data cannot be exported.
- Catchment Group Name. Displays the group in which the catchment was created. To change the catchment group, you can use the Move To Catchment Group command.
- Reference Surface. Displays the surface upon which the catchment area was calculated. If the catchment was creating using the Create Catchment From Object command, this value is <none>.
Important: The surface associated with a catchment cannot be changed after the catchment is created. The catchment does not update dynamically if the surface changes after the catchment is created. However, you may select another surface to use for calculating flow paths when using the Edit Flow Segments command.
Time of Concentration
Calculation Method. Specifies which method to use for calculating the Time Of Concentration: TR-55 or User-Defined.
Flow Segments (TR-55)
- Open Flow Segments Palette. By default, flow paths are created with the number of segments as specified in the catchment feature settings. You can use the Edit Flow Segments command to add additional segments of any of the three types to a flow path after creation.
- Time of Concentration. Displays the sum of the calculated travel time values.
- Total Sheet Flow Travel Time (0). Displays the travel time for all sheet flow segments.
- Total Shallow Concentrated Flow Travel Time (0). Displays the travel time for all shallow concentrated flow segments.
- Total Channel Flow Travel Time (0). Displays the travel time for all channel flow segments.
- Hydraulically Most Distant Length. Displays the distance between the specified discharge point and hydraulically most distant point.
This length may not be the longest measurable distance between any two points within a catchment; it can be shorter.
Water moves through a watershed as sheet flow, shallow concentrated flow, swales, open channels, street gutters, storm sewers, or some combination of these. The hydraulically most distant length represents these flows along a path where "distant" relates to time rather than length.
Time of Concentration Properties (User-defined)
- Time of Concentration. Displays the sum of the calculated travel time values.
- Hydraulically Most Distant Length. Displays the distance between the specified discharge point and hydraulically most distant point.
This length may not be the longest measurable distance between any two points within a catchment; it can be shorter.
Water moves through a watershed as sheet flow, shallow concentrated flow, swales, open channels, street gutters, storm sewers, or some combination of these. The hydraulically most distant length represents these flows along a path where "distant" relates to time rather than length.