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Hydrologic and hydraulic modeling software - made simple.

Powered by an advanced computational engine, chan offers the industry's premier stormwater modeling interface. It's a top choice for engineers, hydrologists, designers, planners, and educators. With a focus on ease of use, it streamlines tasks like sizing a pond, designing a small site, or evaluating a compact drainage network. As a comprehensive modeling system, chan is equipped to handle large and intricate stormwater analyses, even at a watershed scale.

DES has worked tirelessly to update chan with a new workflow and modern feature set, and we are offering this professional-grade storm event simulation system at an incredible, affordable price. With chan, you'll not only save time and money but also enjoy the creative and thoughtful process involved in stormwater modeling.

Join the growing community of professionals who are discovering the unparalleled efficiency and simplicity that chan brings to every stormwater project - making complex tasks seem effortless.

starting at just $29/mo.


"we are offering this professional-grade storm event simulation system at an incredible, affordable price."



chan is a program to generate runoff hydrographs and perform hydraulic and hydrodynamic flow routings through connected systems of lakes, ponds, wetlands, channels, and other features.


With a new, feature-filled graphical interface, novice and expert alike will enjoy and excel at constructing models to analyze a wide range of conditions. Natural and manmade systems, defined by a network of basin, node, and reach elements, are constructed quickly using the fully interactive schematic editor.  Simply point and click to add components of your drainage system to a schematic layout. You can also build the model network through the use of the editor’s import facilities and export your layout as a Drawing Exchange Format (DXF) file.

Model formulation is a breeze as you move freely between editing, simulation, and retrieval modes. For production you simply queue and launch your scenarios. chan does all the heavy lifting in the background while you move on to other demands. 

"...novice modelers and experts alike will enjoy and excel at constructing models to analyze a wide range of conditions."

Key Features

​Quickly construct your model using tabular and schematic views.

Import spatial data and parameters through simple data exchange.

​Apply design or historical rainfall system-wide or vary across basins.

​Choose familiar rainfall excess and hydrograph generation methods.

Define constant or variable stage and flow boundary conditions.​Combine multiple serial and parallel structures within a single reach.

Apply a powerful hydrodynamic solution to unsteady open channels.​

Model dynamic flow in open water and wetlands in a 2D framework.

Queue and run multiple condition sets (scenarios) in the background.​

Retrieve and print results in customizable graphic and tabular views.

Generate run summaries and detailed simulation output reports.



"chan provides all of the flexibility and power that you will ever need to model stormwater systems with speed and accuracy in a surprisingly affordable package."



chan allows you to assign historical and synthetic (design) rainfall volume, duration, and distribution at the watershed or basin level. A customizable library of rainfall distribution files holds historical events input as incremental rainfall data and design distributions input as cumulative non-dimensional mass curves.


Rainfall excess is typically calculated using the SCS Curve Number Method with accounting for pervious, directly-connect impervious, and non-directly connected impervious areas. Parameters may be input directly or derived as area-weighted values from land use and soil group assignments to basins. Rainfall may also be applied directly or used to compute excess using a user-defined method. Excess can even be computed externally and assigned at runtime.


chan features several familiar methods for generating runoff hydrographs to meet the requirements of your project, including:

  • SCS Unit Hydrograph,

  • Santa Barbara Urban Hydrograph, and

  • Kinematic methods.  


For even greater flexibility, you may elect to develop and apply a User-defined Unit Hydrograph, and seasoned users will appreciate the inclusion of Snyder’s Unit Hydrograph as an advanced option.  


Mix and Match - All of these methods have distinct advantages and applicability to conditions found across a watershed. You can choose the method that best fits each basin in your network.

"With chan, your model can account for almost any complexity in a drainage structure."


chan is a fast, flexible, and powerful tool for simulating simple and complex structure hydraulics in stormwater management systems. 

Your model can account for almost any complexity in a structure.

  • Any number of culverts, weirs, gates, orifices, pumps, bridges, and junction channels can be in parallel within a single reach.

  • Any number of weirs, gates, and orifices can be upstream or downstream of each culvert, bridge, or junction channel.

  • Weir heights, gate openings, and pump schedules can vary with time or with stage at any referenced node in the system.

At the heart of chan is our proprietary computational engine. It calculates the flow rate and velocity through individual parallel and serial elements that comprise the reach, based on upstream and downstream water levels at each time step, and then reports the combined flow rate and maximum exit velocity for the reach.

H&H modeling is inherently challenging, which is why we've paid attention to the smallest details. chan defines structure features using real-world terminology, opting for concise terms that both users and reviewers can easily understand, such as span, rise, sill, blade height, orifice, flap gate, and pump. This stands in contrast to confusing, made-up terms we all have become accustomed to but nevertheless obscure the structure's physical characteristics.


"When it comes to hydrodynamic simulation,

chan is very easy to work with."



When it comes to hydrodynamic simulation, chan is very easy to work with. Our advanced algorithms provide you with an accurate and remarkably stable modeling experience, with performance to speed you through your work.  

Developed, tested, and improved over half a century, the explicit finite difference solution that chan applies to the unsteady flow equations is combined with unique computation techniques that dramatically reduce or eliminate instabilities under all but the most extreme open channel and open water flow conditions.


Our hydrodynamic solution ensures that dry channel beds and bothersome flow oscillations will not haunt you with chan. It also enables you to model not only ditches, streams, and canals, but also some of the traditionally more difficult features to model such as sloping wetlands, sloughs, marsh systems, and wet prairies.

"At this price point you can afford to distribute copies

to staff (engineers, spatial analysts, and technicians) with

each cross-trained on features of the chan toolset."


chan provides a host of tools to make modeling fast and easy. 


  • A travel time computer is built right in, so you can define times of concentration for each basin on the fly or import segment data from your Geographic Information System (GIS) and compute Tc values for your entire watershed at once.

  • Compute weighted Curve Number and Imperviousness for each basin based on land use and soil type sub-areas. Create and maintain a library of CN and Impervious values that you can import and use consistently across all chan projects. 

  • Our built-in global search and replace tool is a real time saver. If you happen to change your mind about any hydrologic parameter, you can globally replace the assigned value for any selected set of basins with the push of a button.  

  • An integrated cross section editor is also provided for fast and easy data entry. You can import and export section data from external files. You can thin data points in irregular sections generated by overzealous terrain extraction tools. Point and click to graphically modify irregular sections by adding and removing points. You can add piers, abutments, and a low chord to define a bridge; and flip, slide or skew any section.

  • Context-sensitive menus present a whole range of helper functions such as to set pipe inverts at desired barrel slope, to extract pipe length from the schematic, to select parameter values from a customizable library, and much more.


There are simply too many tools to discuss here, and more are being added all the time. Let's just say, in short, that a great many of the most time-consuming tasks of model construction have been addressed and the level of effort reduced dramatically, leaving you free to think more about the design and performance of your stormwater system and less about building of the model.


"Lay out your model network using real-world coordinates with

aerial or map background images displayed for spatial reference."



chan provides visual feedback in all phases of your modeling.


The schematic provides a customizable model domain overview.


All element types can be assigned unique display formatting.

Error status is clearly reflected in label coloring and messaging.

Storage and area relation plots are displayed for all nodes.


Land use and soil area relations are displayed for all basins.

Cross sections are viewed graphically as they are constructed.


Overlays allow visual comparison of cross section geometry.

Linked photos are displayed as you work on model elements.


Comments are also maintained and displayed for all elements.

Time series plots of simulation results are customizable.

Profile plots display the water surface in relation to features.

Animation of time series and profiles adds context to the viewer.

"Model construction, parameterization, simulation, retrieval, and

report generation workflows are nearly seamless with chan."


Track your simulation progress live or in looped playback, using customizable, animated schematic, profile, and time series views.


You can display conditions system wide or zoom in real tight to observe changing water levels around individual structures, all while interacting with your model network, adjusting hydrologic parameters, storage, design sections, control structure geometry, and taking notes so your decisions are documented on the fly.


"All chan users have membership in the chan/stormwater community."



All chan users have membership in the chan/stormwater community.


The chan/stormwater community was created by DES for all who have a common interest in stormwater management. It is designed and managed to filter out the noise of the internet and allow its members to have dialog, exchange ideas, and share experience. 


In addition to having a general feed, the community is launching numerous hosted Focus Groups. Through the development and growth of these focus groups we hope to provide a forum and knowledge base that spans many important areas related to stormwater. Members of the chan/stormwater community can pick and choose which, if any, focus groups they would like to participate in, including the chan users group - a focus group hosted by DES for targeted discussion and collaboration on stormwater modeling.


Other important resources that are made available to chan users through the chan/stormwater community include:


  • chan user manual - the definitive guide to using the software

  • chan FAQ page and feed - for questions, answers, and dialog

  • chan tutorials - video demonstrations of tools and techniques

While the chan/stormwater community is obviously linked to chan, topics related to the software are primarily discussed within the dedicated focus group. And you don't have to be a chan user to join the focus group. We hope that all modelers (users of SWMM, ICPR, HEC-RAS, TUFLOW, ...) and many others will join the focus group and help us advance our combined modeling knowledge and skills.


Hydrologic and hydraulic modeling software - made simple.

starting at just $29/mo.

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