Bioswale vs Rain Garden

Last Updated on October 3, 2022 by admin

If you’re concerned about flooding and care about the environment, you might be wondering what kind of green infrastructure can help mitigate flooding while providing environmental benefits. As any homeowner knows, flooding can be a severe problem. It can damage property and can also lead to the spread of disease. Fortunately, there are many measures that can be taken to help reduce the risk of flooding. Two popular options are bioswales and rain gardens.

So, which is better, what’s the difference between the two, and which is the right solution for you? Let’s take a closer look.

What are Bioswales?

A bioswale is a landscaping feature designed to remove pollutants and silt from surface runoff water. It uses soil and vegetation to filter out contaminants before the water is discharged into natural waterways such as rivers and streams. Bioswales are usually long and narrow, and they are often installed in urban areas where there is a lot of pavement (think along streets.)

As water flows through a bioswale, pollutants like oils and heavy metals are trapped by vegetation and organic materials, while sediments settle out in the bottom of the channel. Perhaps the most important feature of a bioswale is its ability to attenuate nutrient loads. Because bioswales use green infrastructure, such as native plant species, they are particularly good at removing nutrients from stormwater runoff. This is of vital importance to the environment because excess nutrients can cause harmful algal blooms that threaten the health of receiving waters.

Bioswales are engineered systems. They often include drainage overflows that connect to the public stormwater system (drainage system.) While they do not always have a drainage overflow, in many cases, they include engineered materials that promote infiltration and even perforated pipes to augment further the ability for runoff to infiltrate rather than enter the drainage system.

What is a Rain Garden?

Rain gardens should be located in areas where stormwater runoff collects, such as near downspouts or at the low point of a property where water flows. The collected water is then slowly discharged back into the atmosphere through evaporation or is allowed to infiltrate into the ground. Rain gardens are typically shallower than bioswales, and they are often installed in residential properties and commercial complexes. However, they can be installed as green infrastructure in public rights of way. This is often the case in walkable streets and boulevards.

A rain garden is similar to a bioswale in that it’s designed to treat stormwater runoff before it has a chance to enter natural waterways. They include many of the same benefits, albeit oftentimes with a lesser degree of efficacy. Rain gardens are usually shallower than bioswales and don’t necessarily have vegetation or organic materials lining the bottom. Instead, rain gardens typically consist of heavily-planted areas that allow water to percolate down through the soil into underground aquifers. They also don’t usually include a high level of engineering design.

How do Bioswales Work?

Bioswales are designed to manage stormwater runoff from urban areas to improve water quality and reduce flooding. Bioswales are usually located on the side of streets, in rights-of-way, or other open spaces. They are designed to intercept, store, and infiltrate stormwater runoff. Bioswales are vegetated with native plants that tolerate the harsh conditions created by stormwater runoff. The vegetation helps to remove contaminants from the stormwater, assists in evapotranspiration, and filters sediments from the water. Bioswales also help to reduce the volume of stormwater runoff, helping to reduce the risk of flooding. Moreover, bioswales can slow down water flow, helping reduce erosion in certain areas. Bioswales are an effective tool for managing stormwater runoff in urban areas.

Bioswales route stormwater through an engineered landscape that removes pollutants before its discharge to a receiving water body. They work by leveraging the gravity flow of stormwater runoff and the benefits of green infrastructure.

How do Rain Gardens Work?

Rain gardens work by collecting and absorbing rainfall that would otherwise run off of impervious surfaces and into storm drains. The plants and soil in the rain garden help to filter out pollutants and slow down the flow of water, which reduces erosion and flooding. The mechanics of a rain garden are very similar to a bioswale. They also intercept stormwater runoff. However, the way they work is considerably more straightforward. Instead of having complex engineered systems and engineered soil strata, they are usually simple gardens with an appropriate soil mix to allow water to percolate.

Water runs off our roofs, driveways, and streets and into the sewer system when it rains. Rain gardens are designed to collect and hold this water and let it soak into the ground slowly. They are planted with deep-rooted native plants that act like a sponge to absorb lots of water. Rain gardens are beautiful and add an engaging landscape while also helping to solve a problem.

Why are Bioswales Important?

Bioswales are one of many green infrastructure solutions that can be implemented in the public right of way. In fact, they can be implemented at scale because many streets in urban and suburban areas already have swales (that grassy area between the road and the sidewalk). Those swales can be converted to bioswales with some design and minor construction.

Bioswales have a ton of benefits; however, they are part of a comprehensive stormwater management strategy. Bioswales are not intended to be the single flooding solution a community needs. Instead, bioswales provide a way to attenuate minor rain events while enhancing the built environment with green infrastructure.

Why are Rain Gardens Important?

Similar to Bioswales, rain gardens are important because they help to reduce runoff from impervious surfaces, which can lead to pollution and flooding. By collecting and absorbing rainfall, rain gardens help to protect our waterways and reduce the amount of pollution that enters them.

Rain gardens can be customized for any application. They can be small or large, depending on the available area. Moreover, rain gardens are often placed in areas that would otherwise be impervious – think courtyards.

Difference between a Bioswale and a Rain Garden

When it comes to managing stormwater, there are a number of different approaches that can be taken. Perhaps the most popular is grey infrastructure, which includes pipes, pumps, and other built structures. While these are of vital importance to a community’s stormwater management, they do not embody a holistic stormwater management strategy. This is where bioswales and rain gardens come into play.

Both bioswales and rain gardens help attenuate and treat stormwater runoff. However, there are some key differences:

1. Complexity: Bioswales are typically engineered systems that intercept, treat, and attenuate stormwater runoff. Rain gardens, on the other hand, generally are simpler systems that collect and detain stormwater runoff.
2. Conveyance: Bioswales are typically designed to intercept stormwater runoff and ultimately convey excess runoff back into the stormwater system. This is achieved by constructing piping and a drainage overflow. Rain gardens do not usually connect to the stormwater system, nor are they designed to convey stormwater to the public drainage system. This is a crucial distinction and, perhaps, the primary differentiator between a bioswale and a rain garden.
3. Use: Bioswales are typically public infrastructure solutions. They are used to augment the public drainage system and attenuate minor rain events. They are also used to treat stormwater runoff to comply with regulatory requirements. Rain gardens can be implemented on private properties – commercial or residential.
4. Maintenance: Both Bioswales and rain gardens require upkeep to ensure that the plant species remain healthy. However, since bioswales are typically located along the side of roads, they often need a higher level of maintenance. Cars parking on the bioswale, debris from the road, and the sheer magnitude of stormwater runoff, can all create additional maintenance needs.

Bioswale vs. Rain Garden Facts

As our society increases its awareness of environmental issues, both Bioswales and rain gardens are increasingly becoming commonplace. Here are a few quick facts about both green infrastructure solutions that you may find helpful.

Common Key Facts

• Bioswales and rain gardens are vegetated areas that are designed to remove pollutants from surface runoff water.
• The vegetation in bioswales and rain gardens helps remove pollutants from the water through absorption and filtration.
• The soil in bioswales and rain gardens also helps to detain and improve the water quality of the runoff.
• Bioswales and rain gardens are often used in urban areas, where they can help mitigate the effects of stormwater runoff and maximize their environmental benefits.
• Bioswales and rain gardens can be used to treat a variety of pollutants, including nutrients, heavy metals, and pesticides.
• Bioswales and rain gardens are typically constructed using plants that effectively remove pollutants from water. Typically these plants are native species that are tolerant of the environment and are well suited to handle stormwater runoff volumes.
• Bioswales and rain gardens can also be used to improve habitats for wildlife.
• Bioswales and rain gardens can be aesthetically pleasing flood mitigation solutions.
• Bioswales and rain gardens can reduce the urban heat island effect – lowering the overall temperature of the area they are in.

Key Bioswale Facts

• Bioswales are green infrastructure solutions designed to treat, infiltrate, and convey stormwater runoff.
• Bioswales are typically installed in public rights of way.
• Bioswales are engineered solutions that often involve complex designs using engineered soils, piping systems, and drainage overflows.
• Bioswales are typically more costly than rain gardens; however, this depends on the bioswale’s complexity and the rain garden’s size.
• Bioswales can require more maintenance than a rain garden.

Key Rain Garden Facts

• Rain gardens are similar to bioswales but typically smaller and more aesthetically pleasing. They are often planted with flowers and other ornamental plants, making them an attractive addition to any yard.
• Rain gardens are a type of garden that is designed to collect and store rainwater.
• Rain gardens are easy to construct and can be implemented anywhere – even in your home!
• Rain gardens are cost-effective green infrastructure solutions that anyone can implement.

Both bioswales and rain gardens can effectively mitigate flooding and pollution problems. However, each has unique characteristics that should be considered before implementing the solution. However, if you’re a private citizen looking to construct a green infrastructure solution on your property, a rain garden is probably your best bet.