4.6: Watersheds

Watershed

An area or basin of land, separated by topography from other areas, that drains to a common waterway (stream, lake, estuary, wetland, aquifer, maybe ocean)

Run-off

Water that moves horizontally across the surface of land

Human activities that alter the water cycle within a watershed

• Deforestation, or harvesting trees 

• Paving 

• Diverting water from one area to another (U5 Land use)

• An undisturbed watershed can absorb heavy rains 

• A watershed with lots of human development has more run-off

Impermeable surface

pavement or buildings that do not allow water infiltration or percolation

• Impervious/impermeable surfaces send excess water into streams or storm drains

• Carries dirt, toxic chemicals, trash, and warmer water directly into rivers

Buffer zone

area near the edge of a river

• Buffer zones comprised of grass, bushes, trees, and loose soil allow water to percolate into soil and not run off

Continental Divides

• Naturally occurring boundary that separates river systems.
  (Typically mountains)

• Each river system feeds into a distinct ocean basin, bay, or sea.