Land and Water Nathan Wells Grade 4 Greenfield Elementary School

1. Land and Water Nathan Wells Grade 4Greenfield Elementary School • Overview video • Model – how scientists represent complex events to help understand them better • Fresh water – about 2.8% of the world’s water

2. The Water Cycle – it’s a continuous process (Lesson 1 & 2) • Precipitation • Evaporation • Condensation • Water cycle.html

5. The Water Cycle • Precipitation • Clouds gather excess water • Water falls back to earth • Hail • Rain • Snow • Sleet • Drought – long periods without precipitation

6. The Water Cycle • Condensation • Water vapor rises • Cold air forms in the atmosphere • Water vapor clings to particles of dust • Cold air turns droplets to particles • Droplets combine to form clouds

7. The Water Cycle • Evaporation • The sun heats the earth • Water changes to gas (water vapor) • Minerals are left behind

8. Other related concepts… • Transpiration – plants “sweat” or lose water into the atmosphere • Hydrologist – scientists who study water on the earth and in the atmosphere • Geologist – scientists who study landforms

9. Watershed

10. Modeling Rain • Precipitation – it goes several places • surface waters (streams, lakes, oceans, etc.) • the ground • evaporates into water vapor • Runoff of impervious surfaces and saturated land

11. Examining Earth Materials (Lesson 5) • Two types of matter • Inorganic – weathered rock fragments; never alive • Organic – living and decaying plant and animal materials

12. Four Soil Components • Gravel • Inorganic • Heaviest, biggest particles • Colored - tan, white, brown, gray • Sinks in water

13. Four soil components continued….. • Sand • Inorganic • Lighter than gravel • Grainy texture • Colored – white, gray, tan • Clumps in water • Floats

14. Four soil components continued… • Clay • Inorganic • Lightest soil • Powdery • Orange-brown • Suspends in water

15. Four soil components continued……. • Humus (top soil) • Organic • Loose texture • Large and small pieces • Holds a lot of water • Clumps • Floats, then sinks

16. Where Does Water Go? (Lesson 6) • Water seeps into ground between soil particles or porespace under the force of gravity • Pore space – space between soil particles • Gravity – force that pulls matter to earth

17. Where Does Water Go? • Impervious – layers of rock, water flows off or around it • Runoff – water that flows over land • Compaction – the degree to which soil packs together

18. Water Table • Underground boundary between zone of saturation (land filled with water) and the zone of aeration (land filled with air and soil.)

19. Investigating Streams • Origin of streams • Flowing water or precipitation • Melting snow and ice • Underground springs • Water that flows out of cavities or caves (aquifers) • Groundwater discharge

20. Investigating Streams continued…. • Different forms of streams….. • Rivulets – tiny channels that form gullies • Gullies – deeper channels • Tributaries – small stream branches • Rivers – joined streams and tributaries

21. Investigating Streams continued…. • Parts of a stream channel (trunk) • Head – top of stream • Delta – triangular –shaped landform created by deposited sediment • Mouth – where the bottom meets larger body of water • Floodplain – land left behind after flood waters drain (often covered after heavy rain flows) • Tributary – branches of stream

22. Erosion & Deposition (Lesson 7 & 8) • Aerial drawing – “bird’s eye view” ; view of stream model from above • Velocity – the speed of water flow

23. Erosion & Deposition continued…. • Weathering - the process by which rocks break down into various earth materials including soil • Erosion – the wearing away of land • Wind • Waves • Flowing water or precipitation • Glaciers

24. Erosion & Deposition continued…. • Deposition – the soil which is moved by water • Sediment – another way to describe deposition • Suspension – when fine particles float in water and do not dissolve • Load – large amount of sediment • Causes an overflow of water

25. Glaciers • Moving rivers of ice • Usually only moves a few inches a day

26. Modeling Tributaries (Lesson 9) • Stream trunk and its tributaries act as a system for draining land • Watershed – all of surrounding area drained by stream channel and tributaries

27. Hills and Rocks: How Nature Changes the Direction and Flow of Water? (Lesson 11) • What Is An Oxbow Lake?An oxbow is a crescent-shaped lake lying alongside a winding river. The oxbow lake is created over time as erosion and deposits of soil change the river's course. You can see how an oxbow lake takes shape below:

28. Oxbow Lake

29. Dams: How Humans Change the Direction and Flow of Water (Lesson 12) • Flood-control dams – a barrier that controls the direction and flow of water • Main purpose is to hold excess water from a storm • Reservoir is an artificial lake created for excessive runoff • Hydroelectric power – stored water generates electricity

30. “Dams” continued • Flood – caused by a severe storm which can cause a stream to overflow its banks • Flash flood - sudden increase in runoff due to heavy flood of water • Levee – high ridges along banks that prevents or minimize flooding

31. “Dams” continued • Ecosystem – environment in which plants and animals live and interact • Irrigation – brings water to farmland through drainage channels that provides water for growing crops