Retention ponds why do we need them? My sub-division has two. Can’t the water just get drained to the river?
In: Engineering
Rivers work best when they’re surrounded by lots of plants. Rain falls and plants and soil soak up most of the rain and only after a large amount is absorbed does excess rain flow directly into the river.
People like to live in homes and drive and that means making lots of waterproof things (roads, roofs, etc). When rain falls on these very little is soaked up and most of the water flows into a gutter and then stream or/then a river.
That means if a river only started getting water from rainstorms that dropped more than 3 cm or an inch of water, now it might get half the rain that falls on a large city plus any rain that falls over that amount. That’s a lot more water for the river to carry which means it floods far more than it did previously. This tends to make the people downstream upset.
To cut down on how much water they discharge, more areas have begun to require retention ponds to act more like the undisturbed area did (absorbing some of the water that the buildings and paved surface are shedding).
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