Pervious surface means an area that releases as runoff a small portion of the precipitation that falls on it. Lawns, gardens, parks, forests or other similar vegetated areas are examples of surfaces that typically are pervious.
Groundwater means all water, which is below the surface of the ground in the saturation zone and in direct contact with the ground or subsoil.
Impact surface means an interior or exterior surface that is subject to damage by repeated sudden force such as certain parts of door frames.
Water surface elevation means the height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929, the North American Vertical Datum (NAVD) of 1988, or other datum, where specified, of floods of various magnitudes and frequencies in the floodplains of riverine areas.
Surface water means all water which is open to the atmosphere and subject to surface runoff.