2. Chapter 9 Surface Water

3. 9 – 1 Surface Water Movement

5. Hydrologic (Water) Cycle Hydrologic cycle: recycles water on Earth…always the same amount, just NOT always available at any given place. Water at surface either soaks in / evaporates / or flows down slope.

6. Runoff Runoff: water at the surface that does not soak into ground, but moves down slope.

7. Runoff may reach stream, lake, ocean, or soak into ground, or evaporate…. Factors affecting runoff include Porosity of soil, rate of precipitation, saturation, soil composition, slope, vegetation…

8. Vegetation More plant life results in less runoff. Vegetation allows more water to soak into ground by keeping soil from compacting

9. Precipitation Rates Light, gentle rains soak into ground… downpours can exceed the infiltration rate of the soil causing great amounts of runoff.

10. Soil Composition More humus means greater infiltration rates. Sandy soil is more porous, clay has low porosity.

11. Slope Gentle slope increases infiltration rates… steep slopes greatly reduce ability of water to soak into ground and increases erosion.

12. River Systems tributary: A stream that feeds into a larger stream or river. runoff from land areas feed tributaries, which make river system larger.

13. Usually begins in mountains or hills, often due to snowmelt in the western U.S., Springs in eastern U.S. Rill  gully  brook  creek  stream  River  Lake or Ocean?

14. Watershed Watershed: all land whose water drains into a common river (drainage basin). Mississippi watershed is the largest in USA

15. Divide Divide: the high land area that separates watersheds from each other. Mississippi Delaware Erie

17. Stream Load Stream Load: the amount of material that is carried by stream. Living and nonliving materials: sediments, oxygen, organisms, … 3 ways a stream carries it load…

18. As a Solution Solution: anything dissolved in water. Soluable minerals and gases from the material the stream has passed through. Measured in ppm: 5ppm means 5 parts to every million parts water.

19. As a Suspension Suspension: particles are small enough to be held up by the force of the flowing stream. Clay, silt & sand Varies with velocity and volume of water flow. As stream loses energy, suspended particles become sediments.

21. As Bed Load Bed Load: that which is too heavy to be carried, but rolls and bounces along riverbed. Sand, pebbles, rocks. Faster water moves larger materials. Rounds edges as material is transported

22. Carrying Capacity of Stream Carrying Capacity: ability of a stream to transport materials. Depends upon Volume and Velocity. Water moves fastest over smooth surfaces. Smooth bottomed steep sided channels = most movement.

23. Discharge of Stream Discharge: measure of the Volume of water flowing over a particular location in a certain time period. Discharge = width X depth X Velocity. Units are m 3 /s Mississippi River discharge: 173600 m 3 /s (Amazon 10X that!)

24. The equation defining discharge is: Q = VWD where Q = discharge, V = velocity, W = width, D = depth

25. Floodplains Floodplain: broad flat area extending away from stream banks that is covered in excess water during flooding. Flood: when water volume exceeds capacity of stream, water spills over banks and flows onto floodplain.

27. Floods Floods are normal, natural occurring events. Flood stage: level where stream overflows its banks. Crest: maximum height of flooding.

28. Pittsburgh, following “Ivan” 2004

30. Upstream Flooding Upstream Flooding: Downpours cause localized flooding over small areas for short periods of time. Flash Flooding is a type of upstream flooding.

31. Downstream Flooding Downstream Flood: heavy accumulations of excess water from large regional drainage due to tremendous water runoff (spring thaw & rainfall). 1993 Mississippi River flooding.

33. Flood Prevention USGS has established 4400 stream gauging systems throughout US to warn of flood dangers and allow for safe and effective evacuations.

34. End of 9 – 1

35. 9 – 2 Stream Development

36. Stream Terminology Source: beginning or “headwaters” of river. Mouth: end of river. Channel: carved deeper as runoff cuts into the Earth’s surface. Banks: sides of eroded channel that contains the flow of the stream.

37. Stream Valleys V-shaped valleys: most common valley cut by stream erosion. Most obvious in mountainous regions, eventually the valley widens.

38. Base Level… A stream seeks base level: the elevation where it enters another body of water. Lake, river, Ocean, groundwater…

39. 3 Classes of Rivers Rivers can be classified into 3 categories… Youthful Mature Old Based mostly on erosion rates

40. Youthful river Fast moving, steep slope, deep V-shaped valley, Rapids and waterfalls, High velocity flow. Colorado River / Youghiogheny (at Ohiopyle)

41. Youghiogheny

42. Mature River Slower river, less slope. Wider valley, with few rapids and waterfalls, some curves in river, less velocity and carrying capacity. Allegheny River / Stoneycreek River

43. Allegheny River

44. Old River Slowest river, almost no slope, very wide valley / floodplain, meanders, oxbow lakes? Low velocity and carrying capacity. Mississippi River

46. Deposition of Sediments As rivers slow, material is deposited, either due to changes in gradient, depth, or direction.

47. Alluvial Fan As a steep slope levels out quickly, the stream deposits its sediment at the base of the hill, creating an Alluvial Fan. The fan-like deposit on land, not in water.

48. Delta The triangle like deposit of sediment at the mouth of a river, forming a Delta. Forms as water slows in a large body of water. New Orleans is on a delta… not there 5000 years ago!

49. Rejuvenation Rejuvenation: when an old river actually resumes down- cutting due to an uplifting of the land or base level change. Utah’s Escalade River

50. End of 9 - 2

51. 9 – 3 Lakes / Wetlands

52. Lake Lake: Depression at the surface that collects and holds water. Streams, Runoff, local precipitation, springs and snowmelt supply water to lakes.

53. Most lakes have outlets that often reach the ocean eventually. Reservoirs: lakes that are made to supply water to communities. North Fork Reservoir

54. Quemahoning Reservoir

55. Lake origins Oxbow lakes form as old rivers change course. Glacier lakes form as moraines block valleys and form lakes. Landslides can block valleys and create lakes. Drop in elevation may create lake (Great Salt Lake)

56. Lakes are temporary landforms… They will eventually fill with sediment.

57. Eutrophication Eutrophication: natural buildup of nutrients in a lake due to organisms death and decay. Process can be quickened by the addition of fertilizers, which causes algal bloom that reduces dissolved O 2 in Water.

58. Eutrophic: too many nutrients – cloudy / dark

59. Freshwater Wetlands Areas of land that are covered by water at least part of the year. Bog, Marsh or Swamp.

60. Bog Wetland created by precipitation, no stream feeding it. Soil rich in sphagnum (peat moss) Acidic soils.

61. Marshes Non Woody wetlands No trees. Rich Benthic Zone Plants anchor into mud.

63. Marsh - cont Freshwater is most common. Brackish marsh is slightly salty. Tidal marsh is saltier yet.

64. Swamps Flooded woodlands. Flat, poorly drained land. Near rivers and streams.

66. Value of Wetlands Flood control Pollution control Federal Gov’t prohibits destruction… must replace any that is destroyed.

67. Wetlands provide… *Habitat for native and migratory wildlife. *Recreational fishing *Vegetation traps carbon that otherwise would enter atmosphere as CO 2 *Controls flooding *Remove pollutants from waterways. *Provides products like cranberries, peat moss..

68. Threats to Wetlands Drained and Cleared for farmland, Residential, and Commercial use. Was considered wasteland…

69. End of Chapter 9 … prepare yourself for the test!!!