Civil 3D Catchment Delineation Tool

Automated catchment delineation using WhiteboxTools integrated with AutoCAD Civil 3D 2026.

Overview

This tool automates the watershed delineation workflow for Civil 3D storm drainage design:

1. Exports a Civil 3D TIN surface to a high-resolution DEM raster
2. Extracts pipe network inlet structure locations as pour points
3. Runs hydrologically-correct catchment delineation via WhiteboxTools (breach depressions, D8 flow direction, flow accumulation, watershed delineation)
4. Creates Civil 3D Catchment objects linked to their corresponding inlet structures

Commands

Command	Description
AUTOCATCHMENTS	One-step automated delineation (export, process, import)
CATCHMENTAUTO	Open the automated catchment delineation dialog (WPF UI)
CATCHMENTEXPORT / CATCHMENTTOOL	Export dialog for surface and inlet data
CATCHMENTIMPORT	Import dialog for catchment polygons
EXPORTCATCHMENTDATA	CLI-style export of surface DEM and inlet structures
IMPORTCATCHMENTS	CLI-style import of catchment polygons
LINKCATCHMENTS	Link existing catchments to outlet structures by naming convention
LISTPIPESTRUCTURES	List all structures in a pipe network

Project Structure

CatchmentTool/
├── CSharp/                          # Civil 3D .NET Plugin
│   ├── CatchmentTool.csproj
│   ├── CatchmentTool.sln
│   ├── Commands/
│   │   └── CatchmentCommands.cs     # All command definitions
│   ├── Services/
│   │   ├── SurfaceExporter.cs       # TIN surface → DEM raster
│   │   ├── StructureExtractor.cs    # Pipe network → inlet points
│   │   └── CatchmentCreator.cs      # Polygons → Civil 3D Catchments
│   └── UI/
│       ├── AutoCatchmentDialog.xaml  # One-click delineation dialog
│       ├── CatchmentDialog.xaml
│       ├── ExportDialog.xaml
│       └── ImportDialog.xaml
├── Python/                          # WhiteboxTools processing
│   ├── catchment_delineation.py     # Main delineation pipeline
│   ├── dem_utils.py                 # DEM conversion utilities
│   ├── run_delineation.py           # CLI entry point
│   ├── config_template.json
│   └── requirements.txt
├── Distribution/                    # Packaging and installation
│   ├── CatchmentTool.bundle/        # AutoCAD ApplicationPlugins bundle
│   ├── Install-CatchmentTool.ps1
│   ├── Install.bat / Uninstall.bat
│   └── README.md
├── Data/                            # Working directory for intermediate files
├── Build-Distribution.ps1           # Build + package script
└── INSTALL.md                       # Detailed installation guide

Requirements

Civil 3D

• AutoCAD Civil 3D 2026
• .NET 8.0 (included with Civil 3D 2026)

Python

• Python 3.10+
• whitebox, rasterio, geopandas, shapely, numpy

Quick Start

# 1. Install Python dependencies
pip install -r Python/requirements.txt

# 2. Build the C# plugin
dotnet build CSharp/CatchmentTool.csproj -c Release

# 3. In Civil 3D: NETLOAD → browse to CSharp/bin/CatchmentTool.dll
# 4. In Civil 3D: type AUTOCATCHMENTS

For detailed installation (including auto-load setup), see INSTALL.md.

License

Internal tool — Autodesk Water Infrastructure.