Trevor English
February 25, 2025
4 min read
Handling drainage from stormwater events often means integrating multiple SWCs (StormWater Controls) to effectively prevent catastrophic flooding.
One of the ways drainage designers are adapting their work to be more sustainably minded is by implementing drainage system features known as SuDS (Sustainable Drainage Systems). These have different names across the world like LIDs/BMPs/WSUDs, but they all have the same focus: building more sustainably by taking advantage of natural solutions instead of pouring more concrete. There are many SWCs to choose from, but let’s focus on swales, which are frequently used by drainage designers.
Swales are essential components in modern drainage design and play a significant role in managing stormwater runoff and promoting sustainable drainage practices. These shallow, vegetated channels are designed to slow down, capture, and filter stormwater, reducing the risk of flooding and improving water quality. Their goal is to work with nature, rather than against it. In this article, we will delve into the concept of swales, their benefits, and how Autodesk InfoDrainage integrates SuDS to help designers optimize swale implementation
Swales are typically shallow, gently sloping channels lined with vegetation, such as grasses or shrubs. Swales are, in essence, engineered ditches. Ditches are v-shaped and may not be carefully designed, but swales are different in that they have specific slopes, bottom widths and soil requirements. They are often designed to manage water runoff from impervious surfaces like roads, parking lots, and rooftops, but they can be placed anywhere.
The primary functions of swales are:
Swales are often filled with vegetation, which helps slow down the velocity of the stormwater, and helps with infiltration of that water into the surrounding ground.
But why use a swale over a more traditional ditch or culvert? Well, by working with nature, there are many benefits.
Swales offer numerous advantages over traditional drainage systems. The four main benefits of swales are:
Historically, many drainage designers have handled stormwater by building large culverts and making the surfaces that funnel water towards them impermeable by lining them with concrete. The idea is to forcibly move stormwater to where engineers want it to go, usually past an obstacle or into a subterranean waterway. But moving water away as fast as possible using impenetrable surfaces is not always the best solution. By utilizing swales and other sustainable urban drainage solutions, sites can not only handle changing stormwater events more effectively and efficiently than with culverts, but they can provide natural areas for vegetation and are naturally a habitat for surrounding birds, insects, etc. It’s an approach that not only seeks to use less concrete but to embrace natural ecosystems.
How might an engineer or hydraulic modeler know that the swale they designed can handle a flooding event? Using apps like InfoDrainage, modelers can simulate stormwater events of any size and know the exact inflows and outflows of a swale.
InfoDrainage provides a suite of tools for modeling and simulating swales and other SuDS components, ensuring that they are optimally sized and positioned within the drainage network. It also allows for detailed hydrological analysis, helping engineers understand how swales will perform under various storm events and conditions.
One of the benefits of using InfoDrainage is that you’re able to quickly generate compliant drainage reports for SuDS and LIDs by utilizing the built-in flexible reporting tool. This means that designing with more sustainable drainage systems and getting them through often antiquated approvals processes at your local authority can be easier than ever.
Inside of InfoDrainage, you can model a range of stormwater controls including wet swales, vegetated swales, and dry swales. What makes the app powerful is that you can link all your SuDs together and see how the entire system works, giving you the opportunity to fine-tune the landscape of your project site.
For example, you may want to model swales in conjunction with French drains, filter trenches, infiltration trenches, trench dry wells, wadis – all with or without under drain pipes. With InfoDrainage, you can very accurately model all these details and determine infiltration rates for not just each SuDs feature, but for the entire site.
Whether you are an engineer, urban planner, or environmental advocate, understanding the role of swales in drainage design is essential:
Sign up for the One Water Blog newsletter, and we'll keep you updated about our top stories, along with the best content we find online. We only send out a newsletter when we have something interesting to share.
May we collect and use your data?
Learn more about the Third Party Services we use and our Privacy Statement. May we collect and use your data to tailor your experience?
Explore the benefits of a customized experience by managing your privacy settings for this site or visit our Privacy Statement to learn more about your options.
