2. Rivers

3. Almost half of the water that falls to the Earth’s surface eventually ends up in a stream or river (runoff), where it travels overland to the oceans. Streams and Rivers are an essential part in the water cycle and account for most of the erosion of Earth’s surface.

4. Rivers A tributary is a stream that runs into a larger stream. The main river will eventually drain into the ocean. A river and all of its tributaries is called a river system.

5. The drainage basin, or watershed, of a river includes all the land that drains into the river directly or through its tributaries.

6. The largest in the U.S.

7. A watershed is a precipitation collector!

8. Rivers of VA

9. Every drop of water (or pollution!) that falls into the watershed goes into that river

10. The high land that separates one drainage basin from another is called a divide. Watershed

11. To the Atlantic To the Pacific The major divide in the U.S. is called the Continental Divide.

13. The beginning of a river is known as the SOURCE. Freshwater Spring or Precipitation

14. River Delta When the mouth of a river finally reaches its destination, be it ocean or lake, the water slows down & deposits its sediment, forming a delta.

15. Greek Alphabet

16. Safid River Delta, Rasht, Iran See the sediments going into the ocean! 

17. Mississippi River Delta Sediments from the Mississippi come from everywhere between the Appalachian & Rocky Mtn chains. Eventually they may fill the Gulf of Mexico!

18. An Alluvial Fan is similar to a delta, but forms on land where a river emerges from a mountainous area and flows out onto a more gently sloping plain.

19. Alluvial Fan

21. Source River Valley Tributary Floodplain Meander Oxbow Lake Delta Parts of a River System

22. River Development  Youthful  Mature  Old The three stages in the development of a river are described as youthful, mature, and old.

23. Most rivers begin in the highlands or mountains. There water sources such as melting snow and ice feed fast- moving young rivers.

24. As the young rivers feed into larger rivers over flatter land they may take on characteristics of mature rivers.

25. As the river approaches the ocean it slows down and becomes wider & flatter taking on the characteristics of an old river.

26. 1. A youthful river has a steep slope, fast-moving water, V- shaped valleys, and many rapids and waterfalls Rapids & Waterfalls - caused by steep slopes and differential erosion.Rapids & Waterfalls

27. Flooding speeds up erosion and deposition creating a broader floodplain on the valley floor.

28. 2. A mature river has a shallower slope, is slow moving, and winds back and forth in broad curves called meanders.

29. 3. An old river moves very slowly, has a nearly flat slope and oxbow lakes. Elevated ridges along stream banks are called natural levees.

31. River Meander

32. 3-D View of Meander

33. River Meander

34. Meander Formation

35. Difficult Run

36. Inside Curve: deposition

37. Outside Curve: erosion

39. North Slope, Yukon

40. Meander  Oxbow Lake A river wants to find the shortest, straightest way to the ocean, so it will change paths along the floodplain cutting off wide loops leaving behind a curved body of water called an oxbow lake.

41. Oxbow Lake-To-Be

43. FLOOD!

44. Rivers may overflow its banks as a flood. The floodwater may cover part or the entire valley floor where the river runs eroding and depositing sediments.

45. This part of the valley floor is called the floodplain.

48. Floods can erode or…

49. .… deposit.

50. Coarse-Grained Sediments- Deposited by fast-moving water

51. Fine-Grained Sediments- Deposited by slow-moving or standing water

52. Characteristics of Streams & Rivers Velocity – the distance water travels in a certain amount of time; related to the amount of energy the water has; fast moving rivers erode material more quickly and can carry larger particles Gradient – the slope or incline of a stream; sources of rivers tend to have large gradient whereas deltas of rivers have small gradients. Discharge – the volume of water a river or stream passes in a certain amount of time; becomes larger as tributaries add water; seasonal changes Channel – the path through which water flows; size and shape effect velocity

53. Erie Canal