Rain gardens can help mitigate the effects of flooding.
Answers to Commonly Asked Questions About Flooding, Garden Care and More
Ask the Expert: James Cowan on Stormwater
Flooding can happen at any time of the year and remains a primary concern for residents. Conservation authorities predict and warn about flooding through our flood forecasting and warning program. Your local municipality manages the stormwater system and assists you when flooding happens at home. Read our article on stormwater management from last year to learn more about the different types of flooding.
Even though conservation authorities and municipalities have their own responsibilities; they work together to prepare and respond during flood events. To answer some questions you may have, we brought in one of our experts, James Cowan, Flood Forecasting and Water Management Engineer, for a more technical perspective on flooding and to provide input on some of the most common questions he has received from residents.
What makes a neighbourhood prone to flooding?
Many neighbourhoods are at risk of flooding because stormwater systems were designed based on conditions of the time, such as nearby forests, wetlands and natural spaces that helped absorb rain and snowmelt. As land use has changed and natural areas have been reduced, these systems may no longer be able to handle today’s runoff. Climate change is also contributing to stormwater systems becoming overwhelmed because of the more frequent and intense rainfall, which increases the amount of water flowing into stormwater systems.
Still, understanding how stormwater is managed in your neighbourhood is important. Ask yourself:
- Does my neighbourhood have storm sewers?
- What drainage features are located on or near my property?
The best way to learn about flooding history in your area is to call your municipality’s planning and development department. Consult CVC’s interactive floodplain map to see if your home is within the floodplain of a nearby watercourse.
What steps can I take to direct stormwater away from my home?
There are several actions you can take to help stormwater drain away from your home. These include:
- Knowing which drainage features are on your property and keeping them clear. This may include catch basins in your yard and drainage culverts along the road.
- Maintaining the slope of the land around your home. Each property has a specific grade, or slope, that helps stormwater flow away from the building.
- Disconnect downspouts from the stormwater system and direct downspouts away from the foundation of your home.
What steps can I take to keep stormwater out of my home?
You can also consider actions in your home. Check with your municipality for more resources about:
- Installing a sump pump, if appropriate.
- Adding backwater prevention valves to storm drains and wastewater pipes. This can help prevent stormwater or sewage from backing up into your home. Municipalities often subsidize backwater prevention valves.
- Adding moisture detectors to your basement. These detectors inform you if water has made its way into your home. Moisture detectors can lower home insurance premiums.
- Retrofitting your basement with flood-resilient materials.
Where can I learn more about flood preparedness?
Understanding how stormwater is managed on your property and equipping your home for prevention are valuable steps toward avoiding costly flood damage. Additionally, municipalities and humanitarian organizations often provide guidance on how to prepare ahead of potential flooding and what to do during and after flood events. Some examples include the City of Mississauga’s flood guidance and the Red Cross’s Step-by-Step Guide on flood preparedness. Also, review A Residential Guide to Flood Prevention and Recovery to learn more about managing stormwater at home.
Ask the Expert: Sara Maedel on Rain-ready Gardening
Using rain-loving native plants, you can create beautiful, resilient rain-ready yards and gardens that can help manage and absorb rainwater. We posed some questions to our in-house gardening expert, Sara Maedel.
What can I do to reduce damage from extreme rain in my garden?
Consider planting native grasses, wildflowers, shrubs and trees with long, fibrous roots. Long, fibrous roots create a strong root system throughout your garden that can grip the soil during a flood. This helps prevent plants and soil from being moved around by stormwater. Examples of native plants with long, fibrous roots include Pennsylvania sedge, purple coneflower, eastern ninebark and smooth serviceberry.
How can I help my yard recover after a storm event?
Avoid disturbing waterlogged soil after a flood. Each time we step on or dig in wet soil, the small gaps between soil particles get compressed. Compacted soils make it difficult for rainwater to move throughout the soil, trapping water above the ground. For areas where it’s necessary to step, lay down wide boards to distribute your weight and reduce compaction.
What are the top species to plant in low-lying wet areas?
Low-lying, wet areas have damp soil throughout most of the year and drain slowly after heavy rainfall or flooding. If your yard has areas that hold water, consider adding native plants that prefer moist to wet soil, such as sensitive fern, spotted Joe Pye weed, northern spicebush, red maple, tamarack, or our plant of the month, harlequin blue flag.
Harlequin Blue Flag
Iris versicolor
A wetland wildflower by many names, harlequin blue flag is a perfect addition to many types of gardens, especially rain gardens.
What does harlequin blue flag look like?
A herbaceous perennial, harlequin blue flag displays stunning purple flowers with yellow-and-white-veins in May and June. Its sword-like blue-green leaves shield stalks reaching 60 to 100 centimetres tall.
Why is harlequin blue flag ideal for a rain-ready garden?
Harlequin blue flag loves water and can tolerate dry periods between rain. Although it’s an easy-to-care for plant and will grow in most gardens, it thrives best in partial to full sun and in moist to wet soil of any type. During extreme drought, extra watering may be needed.
Harlequin blue flag grows in clumps, and its rhizomes, a type of specialized underground stem, help stabilize soil during heavy rainfall. In your yard it is best suited to areas where moisture levels are highest and water may pool during heavy rainfall.
How do I care for harlequin blue flag?
Through its rhizomes and ability to self-seed, harlequin blue flag will spread and create colonies. Propagate by dividing its rhizomes, but wear gloves and protective clothing to avoid mild skin irritation.
What can I grow with harlequin blue flag?
Our Native Plants for Rain-ready Landscapes guide features the striking harlequin blue flag plant on its cover. Plant with swamp milkweed, cardinal flower and purple-stemmed aster for a garden attractive to hummingbirds, pollinators and caterpillars from spring to fall.
Use the scientific name for harlequin blue flag when looking for it at your local native plant nursery.