Unit Essential Question: What would the world be like without water? Fresh Water Chapter 11 Unit Essential Question: What would the world be like without water?

Water on Earth – Section 1 97% salt water 3% fresh water Of the 3% of fresh water Ice 76% Water vapor 0.037% Lakes and rivers 0.34% Deep groundwater 11% Shallow groundwater 12% Less than 1% of water on Earth is available for human use

The Water Cycle Water cycle – continuous process by which water moves through the living and non-living parts of the environment In the water cycle, water moves from bodies of water, land, and living things on Earth’s surface to the atmosphere and back to Earth’s surface.

The process of the water cycle Evaporation – the process by which molecules at the surface of a liquid absorb enough energy to change to the gaseous state. Name three places that water evaporates from. Transpiration – the process of water being given off through leaves as water vapor.

Water Cycle continued Clouds form – condensed droplets of water clump together around tiny dust particles in the air, forming clouds. Precipitation – The water vapor in the clouds becomes so heavy that they fall back to Earth. Name the 4 types of precipitation.

How do we use water? Agriculture – growing plants Irrigation – the process of supplying water to areas of land to make them suitable for growing crops. Industry – industries use water in many different ways Transportation – oceans and rivers are used fore transportation Recreation – swimming, boating, skiing, snowboarding, skating

How do we use water? List an agricultural use, and industrial use, and a household use of water that you relied on today.

Water and living things Water makes up nearly 2/3 of your body Water is necessary to keep your body functioning Water is essential for living things to grow, reproduce, and carry out other important processes. Photosynthesis – plants use water, plus carbon dioxide and energy from the sun, to make food

Questions What is the water cycle? Where is most of the fresh water on Earth found? How does the water cycle renew Earth’s supply of fresh water?

Water on the Surface – Section 2 River system – a river and all of its tributaries together make up a river system Tributary – smaller streams and rivers that feed into a main river Watershed – the land area that supplies water to a river system. Watersheds are also called drainage basins. A river can flow into another larger river. When rivers join another river system, the areas they drain become part of the largest river’s watershed.

River systems Divides – One watershed is separated from another by a ridge of land called a divide. Streams on each side of the divide flow in different directions. What is the longest divide in North America?

Rivers and Floods Floods occur when the volume of water in a river increases so much that the river overflows it’s channel.

Can floods be controlled? Building dams is one method of flood control. Dam – a barrier across a river that may redirect the flow of a river to other channels or store water in an artificial lake. Name a large artificial lake around here that was created when a dam was built.

Levees Sediment deposits can build a natural defense against floods. As a river overflows onto its flood plain, it slows down and deposits heavier sediment alongside the channel. Over time these deposits build up into long ridges called levees.

Bodies of Fresh Water Water in streams and rivers is always on the move Water in lakes and ponds is still, or standing water Ponds are smaller and shallower than lakes Sunlight usually reaches to the bottom of all parts of a pond. Most lakes have parts were the water is too deep for sunlight to reach the bottom

Ponds and Lakes Ponds and lakes form when water collects in hollows and low-lying areas of land. Both are supplied by melting snow and ice and runoff Some are fed by rivers or ground water Some ponds only appear in the spring and are created by runoff Why can plants grow throughout a pond?

Ponds and Lakes The bottom of a pond is usually covered with mud and algae The bottom of a lake consists of sand, pebbles or rock

Lakes Lakes are created by A cutoff river meander – oxbow lake Ice sheets that melted at the end of the Ice Age Movement of Earth’s crust Erupting volcano Building a dam Reservoir – a lake that stores water for human use

Changes in a Lake As the water heats and cools the layers of water mix, as the water mixes, minerals, plant matter, and other nutrients rise from the lake bottom to the surface. This lake turnover refreshes the supply of nutrients throughout the lake. Eutrophication occurs when the nutrients build up in the lake and cause more algae to grow. This causes thick green scum on the surface of the water. As the algae gets thicker and blocks out more sunlight, the animals in the lake can not survive. The Lake will eventually dry up and be only plants.

Glaciers and Icebergs Glacier – any large mass of ice that moves slowly over land, 76% of fresh water on Earth Iceberg – When a glacier reaches the seacoast, icebergs form Icebergs break into chunks as big as houses as they drift south They begin to melt in warmer water 90% of an iceberg lies below the surface of the water. Only 10% is visible

Questions What bodies of water make up a river system? Explain how ponds and lakes form. Where do icebergs form