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Simple Strategies for Landscape Stormwater Management

Dry Swale

A long, permeable drainage ditch that allows stormwater to be filtered by plants and soil bacteria. These installations recharge groundwater reservoirs, and provide slow-release irrigation for a yard on a higher grade. [Image]


Bioretention Swale

A meandering swale, characterised by filtration layers (sand and silt) and a design that encourages storm runoff to remain as long as possible to allow sediment to settle and pollutants to be broken-down by vegetation. [Image]


Berm

An earthworks barrier with a raised grade, used in directing the flow of surface water. Berms are more resistant to erosion if anchored with vegetation. Often, they soak up excess surface water like a sponge. [Image]


Rain Garden

A garden with a deep, rich soil, planted in a depression over a well-draining substrate. Both swales and berms can channel water into rain gardens from many points in the garden. The rain garden is planted with flood-tolerant plants, often native species that are attractive to pollinators. Water that gathers in the depression slowly permeates the soil, all while being filtered into the water table and being re-directed from the sewer system. [Image]

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It must be kismet: it rained last night, just in time for me to see that the water-purifying storm drain was functioning properly!

The sand and rough drainage layer is functioning to hold the soil down, so the water in the reservoir is quite clear and undistrurbed. The water will be even clearer once the seeds planted on the banks germinate to prevent erosion, and the aquatic irises start purifying the water.

I believe the whole structure has a capacity for about 400-500 litres of water in total. If we get a stretch of rain, I imagine it will fill about 2/3 of the way with the surface water from the landscape. This is good news for the local birds, who like having a clean place to bathe, drink, swim, and frolic!