1. Running Water & Groundwater
Earth Science Ch. 6

2. 6.1 Running Water Earth’s Water 97.2% Oceans
2.15% Ice Sheets & Glaciers
0.62% Groundwater
0.009% Lakes
0.005% Soil
0.001% Atmosphere
0.0001% Streams

3. Driven by energy from the sun and gravity Evaporation / Transpiration
Water Cycle
Driven by energy from the sun and gravity
Evaporation / Transpiration
Condensation
Precipitation
Infiltration/run off
Accumulation

5. Infiltration: movement of surface water into rocks or soil
Runoff occurs when the rate of rainfall exceeds the earth’s ability to absorb it

6. Stream flow Stream flow is effected by gravity.
Gravity effects the velocity of stream flow
Erosion and transportation of sediment in a stream depend on velocity

7. Factors that determine the velocity of a stream
Gradient
The gradient is the steepness of a slope. The larger the gradient the greater the effect of gravity
Steep slopes produce higher velocities
Channel
The larger, straighter, and smoother the river channel is, the higher the velocity
Discharge
The amount of water in a stream
The greater the discharge, the higher the velocity

8. Changes from upstream to downstream
Gradient decreases
Discharge increases
Width increases
Depth increases
Velocity increases

9. Meanders Bends in streams
Caused by any feature on the surface that causes the stream to stray from a straight course.

10. 6.2 Streams Streams Important agent of erosion
Erosion occurs by movement, abrasion, and dissolving
Most of the stream load is sediment from weathering
The stronger the current, the more erosion.

11. Stream Load Dissolved (solution) Suspended (suspension) Bed (bottom)
Enters through ground water
Suspended (suspension)
Majority of the stream load
Sand, silt, and clay
Bed (bottom)
Larger coarser particles that move on the bottom
Plays a role in erosion

12. Deposition Occurs when a stream slows down
Materials in the stream settle out
Sorting of particles occurs
Heavier, larger particles settle out first (bed load)
Lighter, smaller particles settle out last (suspended and dissolved load)

13. Depositional Features
Deltas
Deposits that form at the mouth of a stream
Forms when the velocity of a stream decreases as it reaches slower moving water.
Identified by triangular shape due to change in direction of a stream.
Alluvial Fans
Formed by deposition at the base of a mountain
Form when the velocity of a mountain stream decreases

16. Natural Levees Ridges that form on the edges of streams
Form when a stream overflows its banks and leaves deposits of sediments
Natural levees reduce the risks of flooding but prevent flood water from returning to the stream.

18. Stream Valleys Youthful Stage Narrow Valleys V-shaped Steep slopes
Rapids and waterfalls
Few meanders

19. Mature Stage Wide valleys Stream energy is from side to side
Flood plains are common
The stream has meanders
Erosion occurs on the outside of the meander
Deposition occurs on the inside of the meander

20. Old Stage Valleys widen Oxbow lakes form due to increased deposition
Flood plain becomes wider

23. Drainage Basins (Watersheds)
The land area that contributes water to a stream
A divide is an imaginary line that separates the watersheds of one stream from another.

25. Groundwater Movement of ground water
Porosity: open space in rock or sediment
Permeability: ability to transmit a fluid through rock.
Ground water moves best when there is high porosity and high permeability.
Sandstone: high porosity and permeability
Shale: low porosity and low permeability
A substance can have high porosity but low permeability
A lot of pore space but the pores are very small or are not connected.
An aquifer is an area that has high porosity and permeability. These areas are good sources for wells.

26. Zones of Groundwater
Zone of aeration
Sediment is mostly dry
Closest to the surface
Capillary fringe
Some pore space is filled with water due to capillary action
Water table
Boundary between saturated and aerated zones
Zone of saturation
Pore space is completely filled or saturated with water
Ideal location for a productive well

28. Wells must be drilled into the zone of saturation to be productive
The water table drops more rapidly in the area nearest to the well due to the water being in rock.
This causes a feature called a cone of depression.

30. Ordinary Wells Artesian Wells Water is pumped out
Groundwater rises under its own pressure or pressure from surrounding rock

32. Springs Hot springs Geysers water table intersects the surface
Natural flow
Hot springs
Higher temperature due to igneous processes
Geysers
Hot springs that shoot up with great force

33. Caverns Form in areas that have limestone bedrock.
Form by carbonation which is a form of chemical weathering
Carbonic acid formed by H2O and CO2 combines with the calcite in limestone.
Caverns contain stalactites, stalagmites, and columns.
Stalactites: form from the ceiling of the cavern from water drops that contain calcite
Stalagmites: form from the floor of the cavern from calcite that accumulates
Columns: a stalactite and stalagmite that combine

34. Karst Topography Areas with limestone bedrock
Sinkholes are common which can form by 2 processes:
sinking rock when water is removed
the collapse of a cavern
Karst areas associated with caverns, caves, and sinkholes
The valley and ridge province of VA is well known for its karst topography.