Water on the Surface

What is a river system? A river system includes a river in addition to any streams or tributaries that flow into that river.

Tributary The smaller streams and rivers that feed into a main river.

Tributaries Tributaries flow toward the main river. They follow a downhill path. What force causes this?

Watershed The land area that supplies water to river system.

Amazon River Basin Largest watershed in the world.

Divide A ridge that separates one watershed from another.

Lakes and Ponds Lakes and ponds form when water collects in hollows and low-lying areas of land.

Ponds Ponds are thriving habitats for various plants and animals. Algae serves as food for many animals. Ponds are typically very shallow and sunlight can reach plants on the bottom.

Lakes Lakes are bigger and deeper than ponds. Lake bottoms consist of sand, pebbles and rock.

Lakes Lakes can form from: cut-off meandering rivers (oxbow lakes) Erosion by ice. Extinct volcano craters Movements of Earth’s crust. Manmade lakes are formed by river dams.

Oxbow Lake

Lakes- Human Uses Drinking water Irrigation Boating Fishing Reservoir- a lake that holds water for human use.

Lake Turnover When the water in a lake mixes due to temperature change causing minerals, plant matter, and other nutrients to rise to the surface. This refreshes the nutrients of the lake.

Eutrophication When nutrients build up in a lake over many years. Algae forms a thick green scum on the surface of the water.

Icebergs Large chunks that break off of a glacier and float away into the ocean. Made of frozen FRESHWATER.