Learn about the Drainage Analysis Extension for Civil 3D.
Drainage Analysis for Autodesk Civil 3D 2026.1 is no longer a Technical Preview, but a production-ready tool set designed to integrate the drainage design environment of Civil 3D with analysis capabilities powered by InfoDrainage analysis cloud-services—all without leaving Civil 3D! This enhances drainage design capabilities by providing new workflows for the design of ponds, underground storage devices, and open channels, as well as improved catchment delineation with expanded runoff method support.
When a drainage engineer prepares to analyze a system, the analysis can be initiated directly within Civil 3D. This allows for the utilization of various rainfall and runoff methods and facilitates the execution of multiple storm event simulations. Upon completion of the analysis, engineers can validate results, including any warnings or errors, before applying them to the drainage components within the drawing and exporting a comprehensive analysis report.
To support the analytical workflows, a rainfall manager for the creation and management of rainfall events is included. Learn more.
New in 2026.1
In this update, improvements have been implemented for stormwater controls, the Rainfall Manager, and various user interface enhancements.
General Stormwater Control Enhancements
- Ponds, underground storage objects, and channels can be viewed in Autodesk Construction Cloud.
- Ponds and underground storage can now be added to the Model Viewer.
- In the Prospector, Stormwater Controls have been moved from the Pipe Networks node to their own first level node.
- The LIST command now displays properties for pond and underground storage.
- Ponds and corridors have been added to the Data Shortcuts Editor.
- Drawings containing Pond, Underground Storage, and Channel objects from the tech-preview will open and display correctly in this 2026.1 release. Version compatibility and tracking is maintained.
While analysis functions normally, it is not possible to create or edit drainage design object geometry or properties.
- A warning dialog displays to indicate incompatibility with Civil 3D 2026.1.
- To update these objects to the current version for editing, run DRAINAGEDESIGNUPGRADE from the command line.
Pond Enhancements
- Ponds can now be shared between drawings using data shortcuts and data references.
- The Storage tab on the Pond Properties dialog box has been redesigned for clarity.
- Ponds can now be created from surfaces. They can also be updated using the Redefine from Surface command.
- Pond now have type classifications. Conceptual ponds are sketched in the drawing. Surface-Based ponds are created from surfaces.
- Four new commands are available for editing pond grading: Quick Edit Pond, Add Side Slope, Add Contour, and Delete Contour.
- You can now adjust slope and volume of a pond from modifying the object in canvas. This includes adding slopes, editing slopes, deleting slope contours, adding contours and editing contour elevations.
- The Add Curves command has been renamed to Fillet Pond.
- The stage storage curve for surface-based ponds can be configured using the "Depth increment" or "User-defined" modes.
- Pond volume calculation has been improved.
- Style selection drop-downs are now available in all pond dialog boxes.
Channel Enhancements
- Added the CreateChannel command.
- Additional cross section shapes are available for Triangular, Rectangular, and Custom channel sections.
- A custom channel section can be defined manually, by importing points from a CSV file, or by picking a subassembly in the drawing.
- A custom channel section can be defined by importing from an existing Sub-assembly in the drawing.
- The station range for a channel baseline can be customized (Raw Station).
- Alignment and Profile as Channel Baseline support has been implemented for channel creation.
- Channel command and feature settings are now available.
Underground Storage Enhancements
- You can now select an underground storage and create, copy, and edit its plan view style from the contextual menu.
- Added the ability to display the proportion of empty space (voids) in a stage depth for water storage.
Rainfall Manager Enhancements
- User interface improvements were implemented to easily create, organize, modify, and exchange various rainfall data.
- Added Distribution Based Rainfall in order to create rainfall data based on a rainfall depth applied to a rainfall distribution.
- Added the ability to create a Distribution Based rainfall event based on SCS rainfall distributions and a valid rainfall depth (0 to 10080 mm).
- Added the ability to import and export individual or sets of rainfall data with a Rainfall Library (*.RAIN) file in order to share with other drawings.
Learn more: About the Rainfall Manager
Analyze Drainage System Enhancements
- Added individual and total system outfall details to the Drainage System tab of analysis results.
- Export option enhancements include selection of current result columns, all results columns, or exclusion of results entirely.
- Exporting analysis data now includes rainfall and input data.
- Additional tabs of input data are now included in the analysis exported Excel file. These include SBUH Runoff, Structure, SCS Runoff, SWMM, Analysis Criteria, Stormwater Controls (Ponds and Underground Storage), Connections (pipes and channels), Stormwater Control Outlet, and Time Area Runoff.
- Added support to pass bypass flows from an inlet structure to the downstream target inlet structure.
Learn more: Analyzing Drainage Systems