The amount of urbanization of a watershed has
a dramatic effect on the amount of precipitation which is delivered
to streams or lakes (runoff) and that which enters the soil (infiltration)
or returns to the atmosphere (evapotranspiration). Urban watersheds
typically have fewer plants (less transpiration) and more impervious surfaces (less infiltration). This leads to increased runoff and
higher streamflow (and perhaps flooding) during rain events. The
accompanying interactive animation illustrates this.