Methods to Reduce Urban Runoff
Introduced| English | Meaning |
|---|---|
| Urban runoff/ˈɜːbən ˈrʌnɒf/ | Urban runoff |
| Permeable pavement/ˈpɜːməbl ˈpeɪvmənt/ | Permeable pavement |
| rain garden/reɪn ˈɡɑːdn/ | A planted dip that collects and absorbs runoff. |
| green roof/ɡriːn ruːf/ | A rooftop planted with vegetation. |
Taming city rain
- In a paved city, rain has nowhere to soak in.
- It rushes off roofs and roads, flooding streets and rivers.
- But clever design can slow the water down and let it soak in.
- These green solutions reduce urban runoff.
The runoff problem
- Urban runoff 城市径流 is rainwater that rushes off hard city surfaces.
- With nowhere to soak in, it overwhelms drains and floods streets.
- On the way, it picks up oil, litter, and chemicals.
- All that pollution pours untreated into rivers and lakes.
Impervious surfaces send rain into drains; permeable surfaces let it soak in
Why is urban runoff a problem?
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Fast runoff from paved cities floods streets and washes oil, litter, and chemicals into waterways.
Let the water soak in
- Permeable pavement 透水路面 has gaps that let rain soak through into the soil.
- A rain garden 雨水花园 is a planted dip that collects and absorbs runoff.
- Both slow the water and let the ground filter it.
- Instead of flooding, the rain recharges the groundwater.
Permeable pavement helps because it…
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Permeable pavement has gaps that let rainwater soak into the soil instead of running off.
A planted, low area designed to soak up stormwater is called a rain ____.
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A rain garden collects runoff and lets plants and soil absorb it, reducing flooding and pollution.
Greening the city
- A green roof 绿色屋顶 is a rooftop planted with vegetation.
- Its plants soak up rainwater and shade the building.
- This cuts runoff and also eases the urban heat island.
- Trees and green spaces do the same across a whole city.
Helps or worsens runoff?
Sort each urban feature by whether it reduces or increases stormwater runoff.
Green roofs increase rainwater runoff and make buildings hotter.
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False. A green roof's plants and soil soak up rainwater and shade the building, reducing both runoff and heat.
Select all methods that reduce urban runoff.
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Solid concrete increases runoff. The other three all reduce it.
These methods work by copying nature's way of handling rain: letting it soak into soil and plants instead of shedding it off hard surfaces. The more a city acts like a forest — with permeable ground and greenery — the less it floods. Fighting runoff means bringing nature back into the city.
A car park that drinks the rain:
- A normal concrete car park sends every drop of rain rushing into the drains.
- Rebuilt with permeable pavement, the same car park lets the rain soak straight through.
- The water refills the groundwater instead of flooding the street — the same land, a very different outcome.
Urban runoff floods streets and pollutes rivers because paved cities shed rain fast. Solutions let water soak in instead: permeable pavement, rain gardens, and green roofs all absorb rainwater, reduce flooding and pollution, and recharge groundwater — by making the city behave more like nature.