A large tree canopy softens the blow from a downpour, allowing rain to soak gradually into the ground. Less runoff reduces flooding, pollution, sedimentation in rivers and lakes, and the need to build bigger storm sewer systems. These are just some of the benefits of the urban forest. Within this band of land, subsurface water is high because of its proximity to the stream, and conditions favor the growth of water-loving vegetation. When prized and given care, they are ribbons of nature, winding through the landscape providing trees, wildlife, clean water, and places of refuge for renewing the human spirit.
Trees are an essential and integral part of the riparian zone.
When trees, shrubs, and other plants cover a stream's floodplain, they slow the rush of high water . Since fast-moving water can carry a higher amount of soil particles than slower water, sediments are dropped by the flood waters in the riparian zone rather than ending up downstream in reservoirs, channels, and harbors. Slowing the water also helps reduce bank erosion. Trees shade creeks and rivers and help keep the water cool . Cool water carries more oxygen and provides a more livable environment for many species of fish.