Freshwater Aquatic Science 2012

FRESHWATER The two main sources for freshwater are groundwater and surface water. Groundwater seeps through soil and cracks in rocks. (ex: aquifer) Surface water flows over land, then collects in rivers, lakes, streams, and reseviors.

Groundwater Lies below the surface of the earth 35% of public water supply in the USA comes from groundwater. An area that holds water underground is called an aquifer.

Surface water River, stream, brook, bayou, creek, lake…. Smaller bodies of water are referred to as streams and creeks. Larger bodies of water are called rivers. When streams join together they form a river system. The river system is fed by rain and snow (runoff)

Rivers… Most rivers don’t start out big. Where a river begins is called the “headwaters”. (this is usually at a high elevation) The area of land that drains into the river system is called the watershed.

Headwaters Fast flow Can grind out and form canyons, create waterfalls and rapids Currents are swift Clear, cold, highly areated, yet low volume of water. Plants and animals are adapted to this type of environment.

Rivers… As more streams flow into a river, it gets wider and wider. When the water reaches flat land, the water will slow down. As sediment is carried downstream and accumulates on the bottom a channel is formed. As the river slows, flat stretches of land called flood plains form on either side.

Rivers… During storms, rivers may overflow into the floodplain. Once the water recedes, it leaves deposits of rich sediment, making the flood plain fertile and productive. These larger slower rivers support diverse communities of species.

Mouth of the river… The mouth of the river (where it empties) is most often a lake or ocean. As the river nears the mouth, the flow slows down even more and dumps tons of sediment forming a delta.