1. Hydrosphere Only planet with correct atmospheric pressure and temperature to allow water to exist in all its phases 97% water held in ocean basins 2% water frozen Only 1 % water fresh* Figure 2-11 (Merritts et al., 1998)

2. Image ID: corp1893, NOAA Corps Collection Location: Alaska Southeast Photo Date: August 1991 Photographer: Commander John Bortniak, NOAA Corps

3. The Hydrologic Cycle Water continuously circulates from the ocean to the atmosphere to the land and back to the ocean. Regardless of its physical form-solid,liquid, or vapor-every molecule of water eventually moves through the hydrologic cycle. Water sources for Earth included 1) water from icy comets, 2) volcanoes, and 3) minerals.

5. (Press and Siever, 1986)

6. Hydrosphere residence times Oceans = 3,100 years Atmosphere = 9 days Continents = 403 years Rivers 12 - 20 days These residence times are significant for evaluating environmental issues.

7. Water budget for the U.S. ~15.9 trillion liters/day fall on the U.S. 66% returned to atmosphere by evaporation and transpiration 3% seeps into groundwater 31% as runoff to rivers and lakes

8. Water Reservoirs Rivers Lakes Wetlands Groundwater Oceans “cryosphere” (glaciers)

9. Rivers: sources of flow Rain falling on the surface of the Earth may infiltrate (to groundwater), runoff (to rivers), or evaporate/ transpirate (to atmosphere).

10. River discharge Amazon, South America212,400 m 3 /s La Plata, South America 79,300 m 3 /s Congo, Africa 39,600 m 3 /s Yangtze, Asia 21,800 m 3 /s Brahmapututra, Asia 19,800 m 3 /s Ganges, Asia 18,700 m 3 /s Mississippi, North America 17,300 m 3 /s Colorado River, North Am. 300 m 3 /s

11. Large rivers of the U.S.

12. Rivers: Human influences Commerce Transportation Irrigation Waste disposal Dams diversions

13. Lakes Basins that collect water Location of basins defined by geologic setting, presence of water based on climate (local or regional) Most of the world’s freshwater resides in lakes

14. Lakes: Human influences Pollution Water diversion Exotic species

15. Wetlands Wetlands are usually inundated by water during some part of the year, are poorly drained, have low relief, and have high soil moisture. Wetlands may appear along coasts as swamps or marshes (i.e. salt marshes) or in the continental interior as marshes, wet meadows, or prairie potholes, or peat moss bogs http://www.epa.gov/owow/wetlands/

17. Natural wetlands have distinct ecosystem functions to which society can assign a “value.” nutrient storage  removal of fertilizing nutrients helping farmers to attain compliance with water quality targets accumulation of organic material for fuel or agriculture  storage of carbon, source of peat filtering of solids from waters  wastewater and sewage treatment, trapping sediment

18. Natural wetlands have distinct ecosystem functions to which society can assign a “value.” animal habitats  fishing, wildfowl hunting and fish and shrimp hatcheries. In addition, Wetlands are a home to a third of the nation’s threatened and endangered species. plant habitats  forestry, agriculture regulating water outflow  flood and erosion protection all functions  recreation, research, and education

19. Wetland losses in the U.S. In the 1660’s, 220 million acres of wetlands were thought to exist in the U.S. By 1980, only 103 million acres remained. Drainage Dredging Stream channelization Diking, damming Tilling Logging Levees, Mining  nutrient levels Pollution Nonnative species http://www.epa.gov/owow/wetlands/

20. Groundwater Water enters the ground as excess surface water Water then seeps downward due to gravity and the porous nature of soil, rock, and sediment Water ultimately seeks it’s base level (usually sea level)

21. Groundwater Depletion Overdraft Subsidence Saltwater intrusion Groundwater Pollution Contaminant transport

22. Environmental problems related to water usually involve problems with water quantity or water quality.