Changes

===Water quantity changes===

===Water quantity changes===

[[File:Urban_Hydrology_1.png|thumb|This image depicts a typical urban hydrologic condition wherein an end-of-pipe control (stormwater management pond) is used to control the peak discharge of urban runoff to a receiving water body.]]

[[File:Urban_Hydrology_1.png|thumb|This image depicts a typical urban hydrologic condition wherein an end-of-pipe control (stormwater management pond) is used to control the peak discharge of urban runoff to a receiving water body.]]

While rainfall intensity, soil and vegetation characteristics, slope length and steepness all play a role in the timing and rate of runoff generation, the creation of impervious surfaces – including rooftops, driveways, roads and parking lots – disrupts rainfall’s ability to penetrate the soil surface and infiltrate.  In heavily urbanized, well-drained areas, the time of concentration is significantly reduced due to the relative smoothness of impervious surfaces, and the dense network of stormwater [[conveyance]] infrastructure including gutters, catch basins and subsurface pipes.  

While rainfall intensity, soil and vegetation characteristics, slope length and steepness all play a role in the timing and rate of runoff generation, the creation of impervious surfaces – including rooftops, driveways, roads and parking lots – disrupts rainfall’s ability to penetrate the soil surface and infiltrate.  In heavily urbanized, well-drained areas, the time of concentration is significantly reduced due to the relative smoothness of impervious surfaces, and the dense network of stormwater [[conveyance]] infrastructure including gutters, catch basins and subsurface pipes.