Increased surface runoff
When materials impervious to water , such as pavement and concrete , cover the ground , runoff increases . Differences between areas with natural ground cover ( before urban development ) and those with impervious cover ( after urban development ) are shown below . As little as 10 % impervious cover in an urban area can Increase surface runoff and lead to water quality problems ( Source : USEPA ).
Increased surface runoff means that large volumes of water enter water sources more quickly ( at higher velocities ) which can cause river or stream bank erosion .
Increased soil erosion
Raindrops hitting the soil ’ s surface and the movement of water ( runoff ) across it cause soil erosion . Disturbed soil , lack of vegetation , or both amplify such impacts increasing erosion . Poorly controlled construction sites are also a cause of soil erosion . Not only can these sites harm aquatic environments , but adjacent properties , public roadways and drainage systems .
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