1. Running Water and Groundwater

2. Earth as a system: the hydrologic cycle  Illustrates the circulation of Earth's water supply  Processes involved in the cycle Precipitation Evaporation Infiltration Runoff Transpiration

3. The hydrologic cycle

4. Sources of Earth ’ s water

5. Running water  Streamflow Factors that determine velocity Gradient, or slope Channel characteristics Shape Size Roughness Discharge – volume of water flowing in the stream (generally expresses as cubic feet per second)

6. Running water  Upstream-downstream changes Profile Cross-sectional view of a stream From head (source) to mouth Profile is a smooth curve Gradient decreases from the head to the mouth Factors that increase downstream Velocity Discharge

7. Running water  Upstream-downstream changes Profile Factors that increase downstream Channel size Factors that decrease downstream Gradient, or slope Channel roughness

8. Longitudinal profile of a stream

9. Running water  Base level Lowest point a stream can erode to Two general types Ultimate – sea level Temporary, or local Changing causes readjustment of the stream – deposition or erosion

10. Adjustment of base level to changing conditions

11. A waterfall is an example of a local base level

12. Running water  The work of streams Erosion Transportation Transported material is called the stream's load Dissolved load Suspended load Bed load

13. Running water  The work of streams Transportation Load is related to a stream's Competence - maximum particle size Capacity - maximum load Capacity is related to discharge

14. Running water  The work of streams Transportation Deposition Caused by a decrease in velocity Competence is reduced Sediment begins to drop out Stream sediments Known as alluvium Well-sorted deposits

15. Running water  The work of streams Transportation Features produced by deposition Deltas – exist in ocean or lakes Natural levees - Form parallel to the stream channel Area behind the levees may contain back swamps or yazoo tributaries

16. Structure of a simple delta

17. Running water  Stream valleys Valley sides are shaped by Weathering Overland flow Mass Wasting Characteristics of narrow valleys V-shaped Downcutting toward base level

18. Running water  Stream valleys Characteristics of narrow valleys Features often include Rapids Waterfalls Characteristics of wide valleys Stream is near base level Downward erosion is less dominant Stream energy is directed from side to side

19. A narrow V-shaped valley

20. Continued erosion and deposition widens the valley

21. The resulting wide stream valley is characterized by meandering on a well-developed floodplain

22. Erosion and deposition along a meandering stream

23. A meander loop on the Colorado River

24. Formation of a cutoff and oxbow lake

25. Running water  Floods and flood control Floods are the most common geologic hazard Causes of floods Weather Human interference with the stream system

26. Running water  Floods and flood control Engineering efforts Artificial levees Flood-control dams Channelization Nonstructural approach through sound floodplain management

27. Satellite view of the Missouri River flowing into the Mississippi River near St. Louis

28. Same satellite view during flooding in 1993

29. Running water  Drainage basins and patterns A divide separates drainage basin Types of drainage patterns Dendritic Radial Rectangular Trellis

30. The drainage basin of the Mississippi River

31. Drainage patterns

32. Water beneath the surface (groundwater)  Largest freshwater reservoir for humans  Geological roles As an erosional agent, dissolving by groundwater produces Sinkholes Caverns An equalizer of stream flow

33. Water beneath the surface (groundwater)  Distribution and movement of groundwater Distribution of groundwater Belt of soil moisture Zone of aeration Unsaturated zone Pore spaces in the material are filled mainly with air

35. Water beneath the surface (groundwater)  Distribution and movement of groundwater Distribution of groundwater Zone of saturation All pore spaces in the material are filled with water Water within the pores is groundwater Water table – the upper limit of the zone of saturation

36. Features associated with subsurface water

37. Water beneath the surface (groundwater)  Distribution and movement of groundwater Distribution of groundwater Porosity Percentage of pore spaces Determines how much groundwater can be stored Permeability Ability to transmit water through connected pore spaces Aquitard – an impermeable layer of material Aquifer – a permeable layer of material

38. Water beneath the surface (groundwater)  Features associated with groundwater Springs Hot springs Water is 6-9ºC warmer than the mean air temperature of the locality Heated by cooling of igneous rock Geysers Intermittent hot springs Water turns to steam and erupts

39. Water beneath the surface (groundwater)  Geologic work of groundwater Groundwater is often mildly acidic Contains weak carbonic acid Dissolves calcite in limestone Caverns Formed by dissolving rock beneath Earth's surface Formed in the zone of saturation

40. Water beneath the surface (groundwater)  Geologic work of groundwater Caverns Features found within caverns Form in the zone of aeration Composed of dripstone Calcite deposited as dripping water evaporates Common features include stalactites (hanging from the ceiling) and stalagmites (growing upward from the floor )

41. Dripstone formations in Carlsbad Caverns National Park

42. Water beneath the surface (groundwater)  Geologic work of groundwater Karst topography Formed by dissolving rock at, or near, Earth's surface Common features Sinkholes – surface depressions Sinkholes form by dissolving bedrock and cavern collapse Caves and caverns Area lacks good surface drainage

43. Development of karst topography

44. Infrared image of karst topography in central Florida