Connections are links between two elements of the Site. They allow a Connection Type to be specified, which will impact the Time of Travel along the Connection and therefore impact the analysis.
The flow routing calculations done during the Analysis are described in Analysis of Connections.
The connections form allows all of the available connections in the phase to be viewed as a table.The top (Input) spreadsheet then allows the Connection Type and other Physical dimensions to be adjusted as required. The lower (Results) spreadsheet will show the results from an Auto Sizing calculation for the selected flow path if available.
The Columns displayed are effected by the Connection Types shown and can also be filtered using the Spreadsheet Preferences.
Change Templates - Provides users the option to change the currently assigned templates for Connections.
Delete Row - Clears data in the current row and deletes the selected Connection.
Clear all data - Clears all data and deletes all Connections.
The Filter By drop down list allows the connections shown to be filtered:
When a Flow Path has been selected on the Filter it is then possible to perform an Auto Sizing of the pipe/channels that form the network along the flow path. The calculations are completed based on the specified Pipe Sizing Criteria when the 'Auto Size' option is clicked. Full details can be found in the Pipe Sizing topic.
Fields can be turned on or off using the Spreadsheet Preferences form that is accessed from the toolbar at the top of the form. The full set of columns available on both the Input and the Results spreadsheet are shown and can be turned on or off using the check boxes. These settings will be remembered between sessions.
Label (Always Shown)
Label of the connection as shown on the plan view.
The label of the item at the upstream end of the connection.
The label of the item at the downstream end of the connection.
Length (Always Shown)
Length of the connection. If in red - the length was defined by the user, otherwise, it was calculated using the Connections coordinates from the plan view.
Connection Type (Always Shown)
Type of the connection:
Longitudinal slope of the connection. This is calculated based on the Fall, between the upstream & downstream invert levels, along the Length of the connection. Entering a value for the slope will therefore adjust the downstream invert level.
Manning's coefficient for the connection, which will be used in velocity and flow/capacity calculations.
No. of Barrels
Number of barrels/channels laid in parallel.
Diameter of the connection if a Pipe, or base width of a Rectangular or Trapezoidal channel.
Height of a Rectangular, Trapezoidal or Triangular channel.
Slope of the sides of a Trapezoidal or Triangular channel.
Upstream Cover Level
The cover/exceedence level at the upstream end of the connection. Levels may be set automatically if sufficient data exists, see individual connection type pages for more details.
Upstream Invert Level
The invert level at the upstream end of the connection. Levels may be set automatically if sufficient data exists, see individual connection type pages for more details.
Downstream Cover Level
The cover/exceedence, level at the downstream end of the connection. Levels may be set automatically if sufficient data exists, see individual connection type pages for more details.
Downstream Invert Level
The invert level at the downstream end of the connection. Levels may be set automatically if sufficient data exists, see individual connection type pages for more details.
Lock the padlock to exclude the given connection from Auto Sizing calculations.
Time Of Travel
Time of travel of the flow through the connection. This value will be automatically calculated based on the dimensions of the connection, however manually entering a value into the column will overrule this.
The coefficient within the Muskingum calculations when using the Attenuated Flow Connection type. This affects the spread of the connections outflow hydrograph with values closer to 0.5 having less effect. The default value is 0.1, if it has been user specified it will be shown in red.
The bottom table shows results after Auto Size of the connections. The results will only be shown when the Flow Path that they relate to is selected on the filter.
Label (Always Shown)
Label of the connection as on the plan view
Total Travel Time
The Travel Time is calculated as the Min. Time of Concentration from the Pipe Sizing Criteria + The Travel Time through the Upstream connections. The time of travel for a given connection is calculated using the Velocity of flow under full bore conditions and the length of the connection.
The Rainfall Intensity is determined from the IDF data, specified on the Pipe Sizing Criteria, based on the Travel Time for the given connection. The Rainfall Intensity is then used in the selected Calculation Method to determine the Flow used for Auto Sizing the pipes/channels.
Total Contributing Area
Total contributing area from connected Inflows. This is factored by the Runoff Coefficient specified per area before being summed. This includes all the upstream contributing areas.
Total Base Flow
Total base flow including all base flows from the upstream connections.
The Proportional Depth is the actual depth of water in the pipe for the calculated flow.
The Proportional Velocity is the velocity of water in the pipeline (i.e. at the Proportional Depth) corresponding to the calculated flow.
Pipe Full Velocity
The Pipe Full Velocity is calculated using the Manning equation and is based on pipe full conditions.
The Pipe Capacity is calculated using the Manning's n equation and is based on pipe full conditions.
The flow is determined based on the calculation method selected in the Pipe Sizing Criteria:
Rational Method: Flow = Rainfall Intensity x Total Area + Total Base Flow
(UK) Modified Rational Method: Flow = Rainfall Intensity x Total Area * Cr(1.3) + Total Base Flow