DRAINS Catchment

DRAINS Catchments

Icon:
Menu:    Pipes > Create Drainage... > DRAINS Catchments
Ribbon: Pipes Tab > Drainage Design Panel > Catchment Area Dropdown > DRAINS Catchments

Introduction

In order to aid in transfer of data between Civil Site Design and DRAINS, the DRAINS Catchment command provides direct input tools for defining a catchment in DRAINS (ILSAX method).  Inputs on this form match exactly with DRAINS catchment inputs.

Coefficient of runoff values are included to facilitate calculation of flows in Civil Site Design (utilising the Rational Method).

A symbol will display in the drawing to confirm that a catchment has been added to the selected structure.

For each catchment, DRAINS allows for input of three land area types: Paved, Supplementary and Grassed.  Users are required to type in a percentage value applying to each area type, with the total summing to 100%.

Please refer to the Watercome DRAINS help for details on each input in the following form (with exception of the CSD C Factor).

Details

Upon selecting the command and selecting a structure the following form is displayed:

Structure Number

Non editable field describing the selected structure

Sub Catchment Name
Type in a name for the catchment

Area (Ha)
Type in a total area for the catchment

   Select in drawing
Allows selection of a closed polyline in the drawing.  The catchment area will be calculated directly from the polyline

   Create in Drawing
Command prompt will display for the user to click on screen to create a closed area for the catchment.  Press Enter or Esc for the software to close the area and add the area value to the form.

Input Method
The user can select the level of detail to include for the catchment

  Abbreviated
Limits the inputs to Percentage of area and Time of Concentration

  Detailed
Expands on the inputs, removing Time of Concentration and including additional inputs for the time to be calculated

Abbreviated Input Method - Inputs
The following inputs apply to Abbreviated Inputs

Percentage of Area
Type in a value between zero and 100 for each of Paved, Supplementary and Grassed.  Total must equal 100(%)

CSD C Factor
Input C factor values (between zero and 1) for each of Paved, Supplementary and Grassed.  Will be used for Civil Site Design catchment flow calculations

Time of Concentration (mins) Type in a time of concentration for Paved, Supplementary and Grassed

Detailed Input Method - Inputs
The following inputs apply to Detailed Inputs

Percentage of Area
Type in a value between zero and 100 for each of Paved, Supplementary and Grassed.  Total must equal 100(%)

CSD C Factor
Input C factor values (between zero and 1) for each of Paved, Supplementary and Grassed.  Will be used for Civil Site Design catchment flow calculations

Additional Time Users can specify an additional time (in mins) to apply to Paved, Supplementary and Grassed areas.  This is added to the calculated catchment time for the specified flow path

Flow Path Length Input a distance of flow for the catchment area for each of Paved, Supplementary and Grassed.

    Select in drawing
Allows selection of a polyline in the drawing.  The length and Flow Path Slope will be calculated directly from the polyline

   Create in Drawing
Command prompt will display for the user to click on screen to create a polyline.  Press Enter or Esc for the software to close the area.  The length and Flow Path Slope will be calculated directly from the polyline

Flow Path Slope Type in a slope.  If a polyline is selected or drawn, the slope will be calculated using the length of the polyline and the elevations calculated start/end of the polyline

Retardence Coefficient n* Type in a retardence coefficient to describe the influence of the terrain (eg: short grass, long grass) on the flows along the catchment

OK

Apply and exit.

Cancel

Exit the form without applying any changes.