Hydrologic Cycle and Groundwater

1
Hydrologic Cycle and Groundwater
2
What is hydrology?

• Hydrology is the study of the occurrence,
  circulation, and distribution of water on Earth
  and its atmosphere.
• Uses of Water
• Living Engineering Recreation
• Drinking Cooling Swimming
• Photosynthesizing Heating Fishing
• Respiring Cleaning Sailing
• Metabolizing Flushing Skating
• Irrigating Skiing

3
Distribution of H2O on Earth
Fig. 13.1
4
Groundwater

• What is groundwater?
• The mass of water stored below the Earths
  surface. Water stored in rock and regolith.
• Less than 1 of all H2O on Earth
• 40 times more abundant than water found in lakes
  and streams

5
Groundwater

• Why is groundwater such a valuable resource?
• 1. Its abundant - 70 times more in the
  subsurface than in surface reservoirs.
• 2. Because groundwater moves so slowly it is
  stored in the earth and remains available even in
  dry periods.
• 3. In some regions, groundwater flows from humid
  environments to dry ones, making water available.

6
Hydrologic Processes

• Infiltration The process by which water enters
  rocks or soil through joints or small pore spaces
  between particles. Soaking in.
• Transpiration Release of water vapor from
  plants.
• Sublimation Transfer of water directly from
  solid state (ice) to gas state (vapor).
  Important in glacial regions.

7
Hydrologic Cycle
Runoff Sum of all rainwater on the surface.
Fig. 12.2
8
Fig. 13.4
9
Rain Shadow Deserts
A rain shadow is an area of low rainfall on the
leeward (downwind) slope of a mountain.
Fig. 13.3
10
Runoff
11
Runoff

• Arid regions Precipitation is lost by
  evaporation and infiltration (little runoff).
• Humid regions (like Fl) Runoff is collected in
  rivers.

The big winner.
12
Wetlands

• Also known as swamps or marshlands.
• Can act as storage areas for runoff.
• Smooth out yearly variations in precipitation.
• Are disappearing quickly and are politically
  contentious (development vs. preservation of
  wetlands).

13
Swamps as Reservoirs
Reservoir A place where water is
stored. Residence time How much time water
spends in a given reservoir.
Fig. 13.5
14
Groundwater
15
Soils and rocks are not completely solid.

• Porosity portion of volume of a material that
  consists of open spaces.
• Permeability measure of the speed at which
  fluid can travel through a porous medium. How
  connected pore spaces are.

16
Fig. 13.7
17
Groundwater terms

• Zone of aeration Portion of soil and rock near
  the surface in which open spaces are filled
  primarily with air (a.k.a vadose zone,
  unsaturated zone).
• Saturated zone Zone in which pore spaces are
  filled with water.
• Groundwater table Boundary between zone of
  aeration and saturated zone.

18
Groundwater table
Boundary between the saturated and unsaturated
zone.
19
How does water get to the saturated zone?

• Recharge Infiltration of water into the
  subsurface.
• Infiltration of rain or melted snow.
• Through the bottom of stream beds.
• Discharge Opposite of recharge. Release of
  groundwater to the surface.

20
Groundwater Movement in Temperate Regions
Fig. 13.9
21
Groundwater Movement in Temperate Regions
Fig. 13.9
22
Groundwater Movement in Temperate Regions
Fig. 13.9
23
More Groundwater Terms

• Aquifer Body of rock that is sufficiently water
  permeable to yield economically significant
  quantities to wells and springs.
• Aquiclude Body of relatively impermeable rock
  that is capable of absorbing water slowly but
  does not transmit it rapidly enough to supply a
  well or spring.

24
Confined Aquifer
Fig. 13.10
25
PerchedWaterTable
Fig. 13.11
26
Springs
Locations where the water table intersects the
ground
Fig. 13.6
27
Drawdown Due to Pumping
Fig. 13.12
28
Oops
Fig. 13.13
29
Groundwater usage
Fig. 13.16
30
Saltwater Intrusion
Fig. 13.14
31
Rates ofgroundwater movement

• Slow to very slow (depending on permeability)
• Generally within the range of 10 to 100 cm per day

32
Darcys Law
AK(h1 h2)
Q
l

• Q discharge (m3/sec)
• A cross-sectional area (m2)
• K hydraulic conductivity (m/sec)
• h1 beginning height (m)
• h2 ending height (m)
• l length of flow (m)

33
Darcys Law
Fig. 13.15
34
Ogallala AquiferMining Groundwater
35
Karst

• Formed in carbonate rocks (limestone).
• Groundwater dissolves carbonates, forming caves,
  caverns, and sinkholes (remember carbonate
  erosion chemical equations?)
• Irregular hilly terrain.
• Underground drainage channels instead of rivers.
• High rainfall climate, jointed limestone
  formations, and large hydraulic gradients.
• LEON COUNTY, FLORIDA!

36
Major Features of Karst Topography
Fig. 13.19
37
Sinkhole in Winter Park
Fig. 13.18
38
Caverns in New Mexico
Fig. 13.17
39
Groundwater pollution
Fig. 13.20