“Where’s Water?” Unit: Surface Water Rivers, Lakes, and Ponds

River Systems The streams and smaller rivers that feed into a main river are called tributaries Tributaries flow downward toward the main river, pulled by the force of gravity A river and all its tributaries together make up a river system

River Features Headwaters Tributaries Flood plain Oxbow lake Meander Mouth Delta Estuary

River Features The many small streams that come together at the source (beginning) of a river are called its headwaters The steep slope of the land causes the river to flow quickly

River Features Meanders Meanders-looping curves in a river Meanders can curve back on themselves. The river may then cut a new, straight course, eventually leaving an oxbow lake

Horseshoe Bend of the Colorado River near Page, AZ

Ox Bow lake on Mississippi

River Features The broad, flat valley through which a river flows is its flood plain

River Features The mouth of a river is where the river flows into another body of water A delta is created when the river slows down and deposits the sediment it was carrying

Delta Formation DEPOSITON OF MATERIAL BY THE RIVER WHEN IT ENTERS THE SEA DEPOSITON OF MATERIAL BY THE RIVER WHEN IT ENTERS THE SEA

Mississippi Delta from Space MISSISSIPPI

Watersheds The land area that supplies water to a river system is called a watershed Watersheds are sometimes known as drainage basins We live in the Delaware River Watershed

Divides A ridge of land that separates one watershed from another is called a divide Mountains are an example of a divide

Divides

Estuaries An estuary is a coastal inlet or bay where fresh water from rivers mix with salty ocean water

Surface Water Part II: Ponds and Lakes

Ponds Ponds are freshwater Ponds are shallow Ponds form when water collects in low-lying areas of land Plants grow at the bottom of ponds

Lakes Lakes are freshwater Lakes are deep Lakes form when water collects in low-lying areas of land Plants do not grow at the bottom of deep lakes Lake Baikal, Russia

Lake Formation Lakes can be formed by natural processes or human efforts: 1. Volcanic lakes 2. Glacier- made lakes 3. Human- made lakes A lake that stores water for human use is called a reservoir

Volcanic Lake

Glacier-Made Lakes

Human-Made Lakes

Lakes Can Change Seasonal changes- water temperature at different depths changes during the year Lake turnover-nutrients mix Nutrients-substances such as nitrogen and phosphorous that plants and algae grow

Lakes Can Change Long-term changes Eutrophication-Algae and scum forms on the surface of the water becomes so thick that it blocks out sunlight and plants cannot carry out photosynthesis Death of a body of fresh water

Eutrophication

Eutrophication

Ponds and Lakes SAME Freshwater Still, standing water Form when water collects in hollows and low-lying areas of land DIFFERENT Lakes are deeper Plants don’t grow at the bottom of deep lakes Sunlight cannot reach the bottom of a deep lake and photosynthesis cannot occur

Crater Lake and Lake Nyos Links ries/august/21/newsid_ / st m ries/august/21/newsid_ / st m