• There are lots of hard (impermeable) surfaces in Bournemouth.
• This means that the water cannot infiltrate into the ground when it rains but instead flows overground along roads and over fields.
• The water faces much less resistance traveling overground, meaning it travels much faster.
• This results in the water reaching the river faster increasing the risk of flooding as all the water gets to the river at once.
• It also means the water can’t soak into the soil to recharge the aquifers.
• As the rainwater travels along the ground, it picks up lots of pollutants such as oil, rubber, heavy metals, and other contaminants from cars, and transports them to the river.
• Lots of sediment from the roads can also end up in rivers, causing them to become murky.