Carlson Hydrology Stormwater Drainage and Hydraulic Design Software

Carlson Hydrology for stormwater drainage and hydraulic design

Carlson Hydrology is professional CAD-based software for analysing surface runoff and designing drainage systems for land-development and civil engineering projects. It brings watershed calculations, storm-sewer design, ponds, channels, culverts and hydraulic structures into the same drawing environment used for site and terrain design.

The software is primarily intended for civil engineers, drainage designers, land-development professionals and survey engineering companies that need to understand where water will flow across a site and then design infrastructure to manage that flow. Because the hydrology tools work with CAD geometry and digital terrain information, changes to a site can be evaluated in relation to the actual project layout rather than through disconnected calculations alone.

Turn terrain models into watershed information

One of the main advantages of Carlson Hydrology is its connection with the site surface. A digital terrain model can be used to determine drainage areas, flow directions and runoff paths across the project.

Watershed analysis tools can identify drainage boundaries and determine the watershed contributing to a selected location such as an inlet or catch basin. This is especially useful during early drainage design because engineers can see how grading and terrain direct water before deciding where structures and pipe networks should be placed.

The software can also determine maximum runoff paths from the terrain model and use this information as part of time-of-concentration calculations. For a designer, this reduces the amount of manually measuring and recreating watershed geometry outside the CAD drawing.

Calculate runoff for existing and proposed conditions

Carlson Hydrology supports site-drainage calculations using established Rational and SCS based methods. Users can calculate watershed area, time of concentration and peak flow rates for the areas being analysed.

Hydrologic Soil Groups, ground-cover areas and watershed boundaries can be represented with normal CAD geometry and layers. Carlson can analyse how these areas overlap and use the resulting information in the runoff workflow.

This is particularly useful when comparing existing and proposed site conditions. Changes in grading, paving, buildings or other ground cover can change the amount and speed of runoff. The software provides a practical way to incorporate these design changes into the hydrology model and produce supporting reports.

Design complete storm drain networks

After runoff has been determined, Carlson Hydrology provides tools for designing the storm-drain system that carries the water through the site. Inlets, structures and pipe connections can be created and managed as a network within the CAD drawing.

The software includes libraries for rainfall information, inlets, manholes, outlets and pipe-related design data. This helps engineers apply repeatable design information across the project rather than entering every parameter from the beginning for each structure.

Pipe networks can be drafted in plan view, profiles and 3D. Keeping the network connected to the CAD drawing makes it easier to review how drainage pipes interact with roads, finished levels and other underground infrastructure.

Calculate pipe flow and hydraulic grade lines

Carlson Hydrology provides the hydraulic calculations required to check how the drainage network will perform. Users can calculate pipe flow depth and velocity together with hydraulic grade line and energy grade line information.

These calculations help an engineer determine whether the selected pipe sizes, slopes and elevations can carry the design flow through the network. HGL and EGL information can also be reviewed in relation to structures and surface elevations to identify areas where the proposed system needs to be adjusted.

Because the network geometry and calculations are connected, changes to pipe sizes, invert elevations or other design parameters can be incorporated into the drainage model without rebuilding the complete layout manually.

Analyse inlets gutter flow and bypass water

For road and urban drainage projects, getting water into the pipe network is just as important as sizing the pipe itself. Carlson Hydrology provides tools for analysing inlet interception, bypass flows, gutter spread and gutter flow depth.

This allows designers to check whether an inlet captures the required flow and how much water continues to the next structure. Gutter spread information can also help evaluate how stormwater interacts with the usable width of a roadway or paved area.

These functions are useful for residential developments, commercial sites, roads, car parks and other projects where surface flow needs to be transferred efficiently into an underground stormwater system.

Automatic drainage network checks

A drainage network contains many relationships that can be difficult to review manually. Carlson Hydrology provides warnings for conditions such as pipe collisions, excessive pipe lengths, insufficient cover, insufficient slope and excessive flow rates.

These checks give the engineer another way to identify potential problems while the system is being designed. For example, a pipe crossing may work hydraulically but conflict with another utility, while an acceptable plan alignment may create inadequate cover when compared with the finished surface.

The warnings do not replace engineering review, but they can make it easier to find areas requiring attention before drawings and calculations are finalised.

Design ponds and detention storage

Carlson Hydrology includes tools for pond design and sizing, allowing stormwater storage to be developed alongside the rest of the drainage system. Stage-storage and stage-discharge information can be created for detention and other storage structures.

This is particularly valuable when a development increases runoff and requires storage to manage the difference between pre-development and post-development conditions. Pond geometry can be related to the terrain model, making it easier to understand how the proposed basin fits within the available site.

Hydrograph and runoff information can then support evaluation of the storage and outlet arrangement under the required design conditions.

Design culverts channels and outlet structures

Not every drainage system consists entirely of underground pipes. Carlson Hydrology also includes tools for culverts, open channels and outlet-control structures, allowing these elements to be incorporated into the wider stormwater design.

Channel tools can be used where runoff follows an open drainage route, while culvert design supports crossings beneath roads, access routes and other infrastructure. Outlet structures can include hydraulic controls such as orifices, weirs and other discharge components used to manage water leaving a pond or storage area.

Having these different structure types available within the same hydrology environment is useful on land-development projects where surface drainage, storm sewers and detention systems must operate together.

HydroNET for connected stormwater modelling

HydroNET provides a network-based approach to organising hydrology information. Subcatchments, ponds, reaches and links can be assembled into a connected model so that the engineer can understand how runoff moves through the complete drainage system.

HydroNET can automatically extract information from the CAD drawing and surface model, reducing repetitive data entry between terrain analysis and stormwater calculations. This is particularly useful on larger developments where several watersheds, ponds and drainage routes interact with one another.

Reporting tools also help document the resulting network and calculations for design review and project records.

HydroCAD integration

Carlson Hydrology can also form part of a workflow with HydroCAD. Carlson can extract project information such as subcatchment areas, soil groups, ground-cover information and watershed geometry and transfer the relevant data into a HydroCAD project for additional stormwater modelling.

This connection is useful for engineers who prefer to prepare and maintain the physical site geometry inside CAD while using HydroCAD for parts of the hydrologic routing and analysis workflow. Changes to the site information can then be reflected in the data used for further modelling instead of manually recreating every subcatchment.

Keep drainage design connected with civil site design

Drainage design rarely happens independently from the rest of a civil project. Roads, lots, finished surfaces, walls and grading all influence how water travels through a site. Carlson Hydrology is designed around this relationship.

Full 3D road, lot and site information can feed into flow and drainage calculations. When a surface changes, the designer can re-evaluate the watershed and drainage system rather than treating the original calculation as fixed.

This is particularly helpful during design development, when grading and drainage often need to be adjusted together until both the site geometry and stormwater solution work properly.

Dynamic plan profile and 3D drafting

Drainage information needs to become part of the construction drawing, not remain only in calculation reports. Carlson Hydrology can draw sewer and drainage information dynamically in plan, profile and 3D views.

Plan views show the relationship between structures and the rest of the site, while profiles make it easier to review pipe slopes, inverts, cover and crossings. A 3D representation provides another useful check where several networks or site features occupy the same area.

For engineering offices, creating calculations and drawing information within the same CAD environment can reduce duplicate drafting and improve consistency between the model and the final plans.

Useful for land development and civil engineering

Carlson Hydrology is particularly well suited to residential and commercial land development, road drainage, industrial sites, car parks, subdivisions and other civil engineering projects where changing the ground surface also changes the way stormwater behaves.

A civil engineer can begin with an existing terrain model, define the proposed development, calculate runoff, locate drainage structures and then design the pipe and storage network. The resulting information can remain within the project drawing for profiles, plans and construction documentation.

Works alongside survey and terrain data

Accurate drainage design starts with reliable terrain information. Survey data collected using GNSS, total stations, LiDAR or other methods can be converted into a surface model and used as the basis for watershed and flow analysis.

This makes Carlson Hydrology relevant to survey and engineering companies that manage both the initial site survey and the subsequent design work. Existing-ground measurements can feed directly into the terrain model, while proposed surfaces from the civil design provide the basis for analysing future drainage conditions.

Part of Carlson Civil Suite

Carlson Hydrology is available as an individual module and is also included in Carlson Civil Suite together with Carlson Civil, Carlson Survey and Carlson GIS. The suite configuration is useful for organisations that handle the complete survey and civil-design workflow rather than drainage alone.

Carlson Survey can process the field survey, Carlson Civil can create roads, sites and grading, Carlson Hydrology can analyse and design the drainage system, and Carlson GIS can manage geospatial attribute information. Because the modules share a CAD-based environment, the same project geometry can continue through several stages of the job.

IntelliCAD and AutoCAD workflow

Carlson Hydrology can run with the IntelliCAD environment supplied with Carlson or on a supported full AutoCAD installation. This gives engineering companies flexibility in how the software is deployed.

Businesses that do not already use AutoCAD can work with the included CAD platform, while companies with an established supported AutoCAD workflow can add Carlson’s hydrology and drainage functions to their existing CAD environment.

Who is Carlson Hydrology for?

Carlson Hydrology is intended primarily for civil engineers, stormwater engineers, drainage designers, land-development consultants and survey engineering companies. It is especially relevant to professionals who already work with terrain models and CAD drawings and want the hydrologic and hydraulic calculations to remain closely connected to that design information.

For smaller engineering offices it can provide a combined CAD and drainage workflow without requiring a separate application for every stage.