HYDROLOGIC CYCLE

I. What is the Hydrologic Cycle? Powered by solar energy Transfers of water between the surface and the subsurface (land, oceans and the atmosphere) Physical and chemical interactions with Earth's material that accompany the movement of water and the biological processes that affect it

I. What is the Hydrologic Cycle? Human interactions shape and greatly influence the availability, quality and flow of water systems 1.agriculture 2.manufacturing 3.mining 4.recreation UNESCO: International Hydrological Programme, World Water Resources and their use.

Water sourceWater volume, in cubic miles Water volume, in cubic kilometers Perce nt of freshw ater Percent of total water Oceans, Seas, and Bays 321,000,0001,338,000, Ice Caps, Glaciers,5,773,00024,064, Groundwater5,614,00023,400, Fresh2,526,00010,530, Saline3,088,00012,870, Soil Moisture3,95916, Ground Ice71,970300, Lakes42,320176, Fresh21,83091, Saline20,49085, Atmosphere3,09512, Swamp Water2,75211, Rivers5092, Biological Water2691, Source: Igor Shiklomanov's chapter "World fresh water resources" in Peter H. Gleick (editor), 1993, Water in Crisis: A Guide to the World's Fresh Water Resources (Oxford University Press, New York).

How much of Earth’s water is ocean water? How much of the freshwater is in glaciers? How much is groundwater? How much is in lakes? What percentage is available for human consumption and where does it come from? IN-CLASS ASSESSMENT: WATER ON EARTH

II. Components of the Water Cycle A. Evaporation: Evaporation is the primary pathway by which water moves from the liquid state back into the water cycle as atmospheric water vapor.

II. Components of the Water Cycle B. Precipitation: Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. It is the primary connection in the water cycle that provides for the delivery of atmospheric water to Earth. Most precipitation falls as rain.

II. Components of the Water Cycle C. Condensation: Condensation is the process by which water vapor in the air is changed into liquid water. Condensation is crucial to the water cycle because it is responsible for the formation of clouds.

II. Components of the Water Cycle D. Runoff: The flow of water that occurs when there is an excess in rainwater, meltwater, or other sources due to the presence of impervious surfaces (pavement, buildings) and/or fully-saturated soil.

II. Components of the Water Cycle E. Groundwater: Large amounts of water are stored in the ground. The water is still moving, possibly very slowly, and it is still part of the water cycle. Most of the water in the ground comes from precipitation that infiltrates downward from the land surface.

III. Water and Society Over 50 % of the world's population does not have access to clean drinking water. Water shortages are due to the growing human population, groundwater pollution and reservoir depletion. Climate change is predicted to diminish the already shrinking water resources of the planet.

IN-CLASS ASSESSMENT: WATER BUDGET Which factors contribute water to storage? Which factors remove it? Would this differ in different locations? What factors could influence this balance? The source of this image is the Kansas Geological Survey website at All Rights Reserved.

Total Water Use Per Capita by Country

III. Water and Environmental Justice 1.2 billion people lack access to clean water; 2.4 billion live without decent sanitation; and 4 billion without wastewater disposal. 12 million people die each year from lack of water, including 3 million children from waterborne disease. More than 113 million children in the developing world are without access to basic education; 60 percent of them are girls. UN Food and Agriculture Association

III. Water and Environmental Justice More than 3.4 million people die each year from water, sanitation, and hygiene-related causes. Nearly all deaths, 99 percent, occur in the developing world. Lack of access to clean water and sanitation kills children at a rate equivalent of a jumbo jet crashing every four hours. Of the 60 million people added to the world's towns and cities every year, most move to informal settlements (i.e. slums) with no sanitation facilities. 780 million people lack access to an improved water source—approximately one in nine people.

III. Water and Environmental Justice "[The water and sanitation] crisis claims more lives through disease than any war claims through guns." An American taking a five-minute shower uses more water than the average person in a developing country slum uses for an entire day. Over 2.5X more people lack water than live in the United States. More people have a mobile phone than a toilet. facts/water/

IN CLASS ASSESSMENT: LOCAL SOURCES Where does your community get its water? Are there surface water sources? Groundwater sources? Do these sources vary throughout the year? Do you worry about water resources in the future? Do you think there is a discrepancy with how these resources are allocated and where there is the greatest need?