1. Water Resources

2. About the Hydrologic Cycle
Hydrology is the study of movements and characteristics of water.
The hydrologic cycle has a profound effect upon climate prediction.
Water is vital so we must understand where to find water and how water supplies cycle through the Earth.

3. Where’s the Water?
FIGURE 11.2 The distribution of water on Earth. [Data from J. P. Peixoto and M. Ali Kettani, “The Control of the Water Cycle.” Scientific American (April 1973): 46; E. K. Berner and R. A. Berner, Global Environment. Upper Saddle River, N.J.: Prentice Hall, 1996, pp. 2–4.]

4. Where’s the Water?
(C & R p. 228)
Renewal time: the time required for the complete replacement of the water in a specific part of the cycle.

5. Flows and Reservoirs
Precipitation: water vapor condenses into tiny drops that form clouds, eventually fall as rain or snow
Infiltration: when precipitation soaks into the ground through particles of soil or cracks
Runoff: precipitation that doesn’t infiltrate moves over the land surface, eventually collecting in streams and rivers
Evaporation: liquid water transforming into gaseous water (water vapor)
Sublimation: solid water (ice) transforming directly into gaseous water (without becoming liquid)

6. Key Parts of The Water Cycle
Oceans
Reservoirs of liquid water
Precipitation
Water falling on earth in liquid (rain) or solid (snow) form
Evaporation and Transpiration
The drawing of water into the atmosphere from water bodies (evaporation) or plants (transpiration)
Surface Water
Ponds, lakes, and streams
Groundwater
Subsurface water storage

7. The Water Cycle
Figure The water cycle. This illustration shows the flow of water through the water cycle.
(C & R p. 227)

8. The Hydrologic Cycle
Numbers indicate thousands of km3/year

9. Precipitation
Figure Average annual precipitation in the United States.
(C & R p. 229)

10. Groundwater Infiltration Zone of aeration Zone of Saturation
Precipitation (rainfall and snowfall) seep into the soil
Zone of aeration
Pore spaces between soil grains contain air and water
Soil moisture in this zone is known as Capillary water
Zone of Saturation
Pore spaces between soil grains are filled with water
Soil moisture here is Groundwater

11. Groundwater
Capillary water
Groundwater
Impervious Surface

12. Groundwater
Figure Fate of water that has fallen on the ground as precipitation. This drawing also shows how an aquifer is formed.
(C & R p. 231)

13. Groundwater Aquifer Water table Aquifer recharge zones
Underground body of water
Water table
the boundary between the unsaturated and saturated zones
Aquifer recharge zones
Areas where precipitation can infiltrate the soil and add water to the aquifers
Figure An aquifer serves as a source of well water. Continued withdrawal of water would eventually deplete the supply if the rate of withdrawal exceeded the rate of recharge.
(C & R p. 231)