Although the Bow and Elbow Rivers occasionally spill over their banks, in reality Calgary is a rather dry city. However, when rain comes down, it tends to come down hard. Mitigating the amount of melt and rain water runoff that hits our watershed at any one time can be a problem for even the most common property owners. Installing a properly-designed rain garden can turn naturally occurring low spots, or areas immediately below gutter downspouts, into a new and exciting part of your landscape.
What Is A Rain Garden?
A rain garden is an engineered dry creek bed designed to accept the run off from the impermeable areas of your property, the roof, the driveway, or the parking lot, and mitigate not only flow rate and release time into the sewer and storm water drains, but also to remove volatile organic compounds, nitrates, and other pollutants before that water ends up in our rivers and creeks.
They are a really neat idea!
A rain garden is created through a combination of correct seepage and proper selection of foliage.
The Basics of Rain Garden Construction
Essentially, a rain garden performs the same job as a more engineered French drain, which also manages excess water.
First, a trench is excavated, following the slope of the low spot already present. The idea is to allow melt or rain to flow into an area that is prepped for the occasion. Stone and rock act as a splash-guard and provide erosion control, especially on the lowest part of the course. Then water-loving plants that can also tolerate drying out a bit can be planted to eventually develop extensive root systems to fully bind the soil and form a strong overall “garden”.
You can also plant along the banks. Here, plantings such as trees should be more drought resistant for when the garden is drier, but thirsty enough to be able to handle the infiltration zone being at capacity.