RUNNING WATER (RIVERS) • Anatomy of a River System 1. head or headwaters 2. trunk or channel

1. RUNNING WATER (RIVERS) • Anatomy of a River System 1. head or headwaters 2. trunk or channel 3. mouth

3. • 5 features that characterize all rivers • 1. discharge - volume of water flowing by a point in a given period of time

4. • 5 features that characterize all rivers 2. velocity i. laminar vs. turbulent flow

5. (1) in addition to velocity, the depth and viscosity of the water determines whether water flow is laminar or turbulent • (a) laminar - shallow and smooth channel, viscous and slow moving fluid • (b) turbulent - deep and rough channel, less viscous and fast moving fluid

6. • 5 features that characterize all rivers 3. channel configuration

7. • 5 features that characterize all rivers 4. gradient - slope of stream i. shape is concave upwards (why?)

8. ii. longitudinal profile - due to... (1) topography (2) climate (3) stream flow (4) resistance of rock to erosion (5) base level (a) ultimate base level? (b) intermediate base levels?

9. • 5 features that characterize all rivers 5. load - what it carries

10. • Sediment Movement - dependent upon type of flow 1. Erosion and transport i. erosion occurs due to: (1) abrasion (2) chemical and physical weathering (3) undercutting

11. ii. transportation of sediment can be broken into: • (1) suspended load • (2) bed load • (a) competence - the size particles that a stream can move • (b) capacity - total volume of sediment that a stream can carry • (3) dissolved load

13. • Sediment Movement - dependent upon type of flow • 1. Erosion and transport • iii. saltation - a particle is picked up when turbulent forces are great enough, and dropped when they decrease slightly

14. • Sediment Movement - dependent upon type of flow • 1. Erosion and transport • settling velocity - speed at which particles settle to the bottom of a channel • v. Dunes and ripples - form at the bottom of a channel and represent sediments that are in transit (requirements ?) • (1) gentle slope faces upstream, and steep slope faces downstream

15. • Stream Valleys, Channels and Floodplains • 1. stream valleys are the entire area from the top of the slope on one side of the river to the top of the slope on the other • i. usually V-shaped

16. • Stream Valleys, Channels and Floodplains • 2. channels are the trough along the bottom of the valley that in which the stream flows • i. channels can have patterns that are nearly straight to extremely circuitous

17. • Stream Valleys, Channels and Floodplains • ii. most streams that flow across flat areas develop curves that are called meanders • (1) not well understood, but once they start they migrate across the floodplain due to differences in the streams flow and velocity in the channel

18. • Stream Valleys, Channels and Floodplains • (2) velocity is greatest on the outside of the bend, this cuts into the bank on the outside bend and the river migrates in that direction

19. • Stream Valleys, Channels and Floodplains • (3) at the same time, the slower flow around the inside of each bend allows the stream to deposit a part of its load on the point bar

20. • Stream Valleys, Channels and Floodplains • (4) oxbow lakes are created when a meander encounters its own course and cuts itself off from the rest of the river

22. • Stream Valleys, Channels and Floodplains • 3. floodplains are the flat area along either side of the channel onto which water overflows during a flood • i. produced by the migration of the river

23. 3. floodplains are the flat area along either side of the channel onto which water overflows during a flood • ii. during floods, the overflowing water rapidly loses energy as it escapes from the channel thereby depositing sediments on the nearby floodplain

25. 3. floodplains are the flat area along either side of the channel onto which water overflows during a flood • iii. the greatest amount of sediment is deposited adjacent to the channel thereby creating a natural levee

26. • Stream Valleys, Channels and Floodplains • 3. floodplains are the flat area along either side of the channel onto which water overflows during a flood • iv. if the natural levee get too big, it can constrict and confine the rivers course

27. NOTE: SINCE THE FACTORS THAT CREATE RIVER FEATURES ARE DYNAMIC, RIVERS CHANGE WITH TIME.....AND DISTANCE • v. examples: longitudinal profiles and recurrence intervals

32. • Drainage Networks 1. a ridge that separates two streams serves as a divide

33. • Drainage Networks 2. divides establish drainage basins 3. stream piracy

34. • Drainage Networks • 4. drainage patterns show the shape and interconnection of streams and tributaries that form a particular drainage network

35. 5. types of drainage patterns • i. dendritic - most popular and resembles the root system of a tree (uniform bedrock)

37. 5. types of drainage patterns ii. rectangular- faulting controls runoff

39. 5. types of drainage patterns iii. trellis - folding controls runoff

40. 5. types of drainage patterns iv. radial - mountains or hills control runoff

42. • Delta's • 1. all streams eventually empty into a large body of standing water and as the streams current dies, sediment is deposited

44. • Delta's • 2. as the stream becomes an obstacle to flow, the streams course changes and forms lobes of the delta

46. • Delta's • 3. the stream deposits its heaviest load near the mouth and carries the finer material out to sea