Shops and malls buy ponds and rain gardens for flood control

The next time you go to a mall or to a big chain store like Walmart, look around. You can find a pond near the parking lot. Although the water looks beautiful, its purpose is not to make the shops beautiful. These ponds are there to help manage the water that comes out of parking lots when it rains.

Anne Jefferson works at Kent State University in Ohio. While there, she studied water. “Once you start looking for them, you will be able to see them all,” she says of rain-fed gardens.

Do not be deceived. This is not just a random swamp. It is a bioreactor cell – a rain garden. It is designed to hold and filter water to ensure it is clean before entering streams or lakes. Moreau1 / Wikimedia Commons

Rain is mostly clean, she points out. Not the land. When rain falls on the ground, it picks up pollution. “Every time we brake [a car], We are dumping small amounts of metal on the road. ” Pollution caused by nearby industrial activities, traffic, or more can also damage the pavement.

If rainwater seeps directly into the storm, it can cause those pollution. But if the water passes through a bioremediate cell, it can come out clean, Jefferson said. These storage cells also have a more interesting name – urban rain gardens. Some always carry water. Others look like big pits or low fields. After heavy rains, they begin to fill up the streets, parking lots, or industrial areas.

Water helps plants grow. But it can also lead to flooding, which is of no use to cities. Rainforests can “reduce” rainfall, Jefferson notes. They temporarily store waste water from parking lots, roofs and streets. Later, she says, these ponds can slowly release that water into a stream. In this way, she says, they will help reduce the floodwaters. In some cases, she says, cities or factories try to “prevent water from entering the river.”

That’s why many cities and businesses are accepting these rainforests Jefferson. She says, “Keep your eyes open.” Every time they visit Walmart, she says, “there is a pond next to it in the parking lot.”

These ‘gardens’ also clean up pollution

Jefferson took many samples from places such as those Walmart reservoirs and canals near rap centers. Well-designed people irrigate cities. But she also wants to use this natural technology to purify the water. That’s why engineers have come up with so many ideas for how to build these sites.

They are carefully designed to act as water filters, not just for holes in the ground or near roadside. For that, they need to be watered and then drained slowly. In many sites, that will not happen without help.

Enter the rainforest gardeners. They promote these sites with many similar plants that you see along the road or near a store. That is not what makes them special. Underground.

Underneath the plants she said, “A mixture of sand and organic matter and fine particles.” They allow water to drink, “But it is not very fast and they cannot grow plants in it. There is a layer of gravel under the soil. It is a more regular soil under it. There may be a drain that goes out when the water reaches the bottom.

When these rainforests slow down, their pebbles and sand help to prevent pollution. And they don’t go out after a lot of pollution. “They are tied to the ground without drinking water,” Jefferson reported. For example, “She found that these were very unlikely [traffic-related] Metals come out of the soil and later contaminate the stream. ”

Illustration of soil and gravel surfaces used to filter water in rainforests
Many sciences were buried under these rainforests. After dropping the water on the ground, you can see the special soil and gravel designed to help filter and drain.Massachusetts Pure Water Equipment

Hurricane water is a major source of microplastics, from tiny bits that can be torn to cracked plastic bags. Rainwater gardens help keep those plastic pieces out of the water lines. That is the finding of a team of researchers from Canada and the United States. On May 5, they announced their findings ACS ES&T Water.

Jefferson and colleagues have shown that urban rainforests, built seven years ago, can wash away pollution today, just as they were new. In the long run, however, those gardens must be cleaned or rebuilt to avoid construction. Jefferson and colleagues published their findings in April 2020 General Environmental Science.

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