River Systems

1. River Systems

2. watershed • land from which water runs off into streams (drainage basin)

3. Surf your watershed http://www.epa.gov/surf/ Know your watershed http://ctic.purdue.edu/kyw/kyw.html

4. tributaries • feeder streams that flow into a main river

5. divide • ridges or elevated regions of high ground that separate watersheds headwaters • beginning of a stream

7. Stream Erosion

8. channel • the path that a stream follows

9. bank bed

10. headward erosion • process of lengthening and branching of a stream

11. stream piracy • the capture of a stream in one watershed by a stream with a higher rate of erosion in another watershed

12. Stage 1 - Beaverdam Creek, Gap Run, and Goose Creek flow eastward through the Blue Ridge and enter the Potomac.

13. Stage 2 - As the land is eroded downward, the three east flowing creeks do not have the power to erode as far through the Blue Ridge as the Shenandoah, Potomac system. The Shenandoah extends itself southward by headward erosion through the relatively high land west of the Blue Ridge. It eventually captures Beaverdam Creek.

14. Stage 3 - The capture of Beaverdam Creek added more discharge to the Shenandoah which was able to therefore erode more. Headward erosion leads to the capture of Gap Run. The water gaps where Beaverdam Creek and Gap Run used to flow through the Blue Ridge are left as wind gaps.

15. Stage 4 - Eventually Goose Creek is captured as well. Snicker's Gap, Ashby Gap, and Manassas Gap are left as wind gaps. As the land on either side of the ridge is eroded down together with the ridge summit, the relative elevation of the wind gaps becomes higher and higher.

16. channel erosion5 things that affect the rate stream load: material carried by a stream

17. dissolved load: mineral matter transported in liquid solution

18. suspended load: particles of fine grains and silt

19. bed load: made of larger, coarser sand, gravel, and pebbles

20. Bed

21. Observe how sediment is transported by flowing water.

24. discharge • volume of water moved by a stream within a given time gradient • steepness of a stream slope

27. water gap • notch formed where the stream has eroded its channel

28. Stream Valleys

29. Youthful river • straight • erodes rapidly • V-shaped • few tributaries • has waterfalls and rapids

33. Mature river • meandering (winding) • slow erosion • U-shaped • lots of tributaries • holds lots of water

37. Old river • gradient and velocity decreases • no more erosion • more meandering

39. Observe changes in the channel of a meandering river.

40. rejuvenated river • a river whose gradient increases due to movement in the Earth’s crust (form a step-like terrace) or velocity increases due to more water movement

42. Stream Deposition as the velocity of a stream decreases, it drops the sediment it was carrying

43. Observe how sediments are deposited.

44. delta • underwater deposit of sediment at the mouth of a river or stream

47. alluvial fan • fan-shaped deposit at the base of a slope on land

50. floodplain • part of the valley floor that may be covered with water during a flood