HydroCAD Stormwater Modeling - Since 1986

CAD Watershed Import

HydroCAD provides direct import of watershed data from AutoCAD and BricsCAD without any additional software.  This capability works with all AutoCAD and AutoCAD-based products such as Civil-3D. Please note that AutoCAD-LT and BricsCAD-Lite are not supported.

Supported versions

AutoCAD Year  Requires HydroCAD   BricsCAD Version Requires HydroCAD
2008-2020 10.0-25 or later    
2021 10.1-4a or later    
2022 10.1-6a or later    
2023 10.2-1c or later V23 10.2-3c or later
2024 10.2-3c or later V24 10.2-4a or later
2025 10.2-5a or later    

Try it Yourself

If you are already using HydroCAD (including the HydroCAD Sampler) you can use the sample project and drawing that are pre-installed with HydroCAD.  Please review the CAD setup notes and then refer to the "CAD Import Tutorial" in the Help menu.

How it Works

The following "CAD Import Overview" is copied from the HydroCAD help system.

CAD Import Overview

HydroCAD provides the ability to import subarea data directly from a CAD drawing file, as configured on the Settings|Watershed screen.  The data is automatically extracted from the following drawing layers:

bulletEach ground cover is drawn on a separate ground cover layer.  In order to avoid unneeded layers you should specify which ground covers will be active in the current project file.  Each layer must contain closed polylines representing the ground cover boundaries.  Islands and holes are allowed.  In the case of partial overlaps between layers, the layer with the higher z-order will have precedence.  You may also specify a default ground cover, which is automatically used for all areas that don't have an explicit ground cover mapping.
bulletAll subcatchment boundaries are drawn on a single subcatchment layer.  Boundaries must be non-overlapping closed polylines.  Each subcatchment is identified by a subcatchment number which must appear on the designated subcatchment number layer.  Each subcatchment number must be a text object (label) whose center falls within the associated subcatchment boundary.
bulletSoil group boundaries must be drawn as non-overlapping closed polylines on the soil group layer.  Each polyline must be labeled with the corresponding soil group letter (A, B, C or D) on the soil group text layer.  You may also define a default soil group, which is automatically used for any areas that don't have an explicit soil group mapping.
bulletIf land-use analysis is enabled, each land use must be mapped as a closed polyline on the land use layer, and labeled with the appropriate land use category on the land use text layer.  Land-use polylines must not overlap.  Any area that doesn't have an explicit land use mapping will default to the land use category associated with the applicable ground cover.
bulletHydroCAD also creates a number of result layers that are used to store the final subarea data.  These layers may be turned on or off as desired, but they must exist in the drawing.

Layers are named and created on the Settings|Watershed screen, which also provides additional options such as layer sets, commonly used for mapping of multiple scenarios such as pre/post conditions.

After the watershed settings have been configured and the watershed information has been drawn on the designated layers, the actual import process is controlled by the Watershed Import Control button on the right-hand toolbar:

bulletSelect Import Now! to import all data according to the current watershed settings.

HydroCAD analyzes the input layers and populates the subarea layer with regions for each of the intersections of all the input layers.  Each region is then imported into the HydroCAD project as a separate subarea line in the appropriate subcatchment.  Subcatchments are automatically created and positioned according to the selections on the Settings|Watershed screen.

bulletSelect View Result Layers to toggle the result layers on and off.

When the hot track option is selected, drawing areas are automatically highlighted as individual nodes are selected on the routing diagram.

For a step-by-step example please see the CAD Import Tutorial in the help system.

Error Messages

If a problem occurs during the import process, a detailed error message will appear as discussed here.

AutoCAD and Civil-3D are registered trademarks of Autodesk, Inc.
BricsCAD is a registered trademark of Bricsys.

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