How does urbanization generally affect stormwater runoff?

Urbanization typically increases the volume and speed of surface runoff due to several factors associated with changes in land use and surface conditions. When natural landscapes, such as forests and fields, are converted into urban environments, permeable surfaces are replaced by impermeable materials like asphalt and concrete. These materials do not allow water to infiltrate into the ground, resulting in a higher volume of runoff during rainfall events.

Additionally, urban areas often have increased amounts of drainage infrastructure designed to quickly channel water away from streets and properties. This infrastructure can lead to faster movement of water across the landscape, contributing to both heightened runoff speeds and volumes.

The alteration of the natural hydrology, in combination with increased impervious surfaces, means that urbanization ultimately intensifies stormwater runoff, which can lead to increased flooding risks, sediment transport, and pollutant loadings in local water bodies. The choice indicating that urbanization increases both the volume and speed of surface runoff accurately reflects the impact of urban development on stormwater management.