Global Water Resources

Freshwater vs. Saltwater

Fresh Water, a renewable resource, is continually recycled and returned to the ecosystem through the hydrologic cycle. As weather systems move through they deposit moisture in the form of rain, snow, hail or sleet.

Watershed: an area of land that captures rainfall and other precipitation and funnels it to a lake or stream or wetland

Water enters a watershed as either precipitation directly into surface water runoff from the surrounding land Groundwater inflow from upstream lakes.

Precipitation falling on the land infiltrates into the ground through percolation to replenish the groundwater. When water accumulates below ground in the spaces between soil and rock, it is called groundwater. Groundwater is contained in aquifers- porous, sponge like formations of rock, sand, or gravel that hold water

The water table is the boundary between the upper layer, or zone of aeration, and the lower layer, or zone of saturation, which is completely filled with water.

Water leaves the system through evaporation from the land and water surface or through transpiration, a process where moisture is released from plants into the atmosphere.

Water also leaves the system through groundwater outflow consumptive uses drinking water, industrial/agricultural systems, etc. Diversions outflows to downstream lakes or rivers.

Salt water is more dense than freshwater Salt makes water heavier Heat makes water less dense

Ocean Circulation

Surface Current: an ocean current that generally flows in the upper 1000m of the ocean. Caused by: Wind Earth’s Rotation Presence of Continents

Ocean Current: any continuous flow of water along a broad path in the ocean Density Current: current in the deep ocean, driven by gravity and differences in density (NOT wind!) Move slowly compared to surface currents

Warm Currents: flow away from the equator on the western side of ocean basins Cold Currents: flow toward the equator on the eastern side of ocean basins The temperature from these ocean currents is transferred to the atmosphere, thus affecting the climate of the areas around them!

Upwelling: when cold, deep water comes to the surface to replace the surface water that is pushed away by the winds Contains large amounts of nutrients that phytoplankton need to grow Very important to life in the ocean!

Downwelling: transports warm water downward, providing oxygen for deep-water life www.enso.info.com

Water as a resource

How we use water Most uses of water are consumptive use, in which water is removed from a particular body of water and is not returned to it Non-consumptive use of water does not remove, or only temporarily removes, water from an aquifer or surface water body

Agriculture Most of this water is lost because of poor irrigation techniques

Industry Water.usgs.gov

Industries that use the most water: Cement, Textiles, Paper All forms of industry use water in the formation of their products or to clean, cool, or heat the machinery.

95% of water use is hidden in the products you buy, the food you eat and the energy you use wwf.org

Residential Use Savingwater.org

How can we save water? At Home: Low-flow faucets, showerheads Energy and water efficient washing machines and toilets

Xeriscaping: landscaping with less water use…less water loss Before After

Agriculture: Drip system- 95% efficiency Industry: Require industries to reclaim and recycle their water

Surface and Groundwater issues

Consequences of depleting ground water: Drought Instability, leading to sinkholes Low water table Diminished surface water swfwmd.state.fl.us

Water conflicts in the United States 10% of U.S. watersheds are stressed to the point that the demand for water exceeds the supply Major water sources in the United States:

Left Hand Side Water Source Affected States Ogallala Aquifer TX, NM, OK, CO, KS, NE, WY, SD Lake Mead NV, AZ Colorado River CO, UT, AZ, NV, CA, NM, WY Klamath River OR, Klamath tribal nation Chattahoochee River GA, AL, FL

Ogallala Aquifer Lake Mead & Colorado River

Chattahoochee River Klamath River

Global Water Conflicts Demand for water is increasing due to… population growth Increasing agricultural and industrial use less predictable rainfall due to climate change

The Solution… Future water supplies may be increased by desalinization: removal of salt from salt water Not economically feasible! Conservation of water is Critical

International Water Conflicts Nile River Egypt and Ethiopia Indus River India and Pakistan Tigris and Euphrates Rivers Turkey and Syria Jordan River Israel and Palestine Colorado River United states and Mexico Al-Disi aquifer Saudi Arabia and Jordan