Water Cycle The Water Cycle Water storage in ice and snow Water storage in the atmosphere Condensation Sublimation Precipitation Evapotranspiration Evaporation Surface runoff Snowmelt runoff to streams Streamflow Evaporation Spring Ground-water discharg Freshwater storage Water storage in oceans U.S.Department of the Intorlo ≤USGS Ground-water storage U.S.Goological Survey http://ga.water.usgs.gov/edu/watercycle.html
Water Cycle
Water Resources Uses of water include agricultural,industrial,household. recreational and environmental activities. Virtually all of these human uses require fresh water. 97%of the water on the Earth is salt water. ● only 3%is fresh water. slightly over two thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air
Water Resources • Uses of water include agricultural, industrial, household, recreational and environmental activities. • Virtually all of these human uses require fresh water. • 97% of the water on the Earth is salt water. • only 3% is fresh water. • slightly over two thirds of this is frozen in glaciers and polar ice caps. • The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air
Freshwater Terminology Surface water -Precipitation that remains on the surface and does not seep into soil ·Runoff -Movement of surface water to lakes,rivers,etc. Watershed (drainage basin) Land area that delivers water into a stream or river system Groundwater Freshwater under the earth's surface stored in aquifers 。Aquifer Underground caverns and porous layers of sand,gravel and rock in which groundwater is stored
Freshwater Terminology • Surface water – Precipitation that remains on the surface and does not seep into soil • Runoff – Movement of surface water to lakes, rivers, etc. • Watershed (drainage basin) – Land area that delivers water into a stream or river system • Groundwater – Freshwater under the earth’s surface stored in aquifers • Aquifer – Underground caverns and porous layers of sand, gravel and rock in which groundwater is stored
Distribution of Earth's Water Saline Atmospheric water ground- 0.22% water Freshwater Surface water Biological water 2.5% and other 0.93% freshwater 0.22% Saline 1.3% Rivers 0.46% lakes Groundwater Lakes Swamps and 0.07% 30.1% 20.1% marshes 2.53% Soil moisture 3.52% Oceans 96.5% Ice and Glaciers snow and ice caps 73.1% 68.6% Total global Freshwater Surface water and water other freshwater 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. Source:USGS
Source: USGS
WORLD WATER RESOURCE DISTRIBUTION Eastern Europe 2% South America 30% North America 15% Eastern Asia 7% Western Europe 4% Japan 1% Central Africa 4% Middle East 11% Southeastern Africa 2% Northern Africa 3% Southern Asia 4% Asia Pacific 17% "The Amazonian basin,where ten of the twenty largest rivers in the world are to be found...represents one fifth of the entire fresh water reserves of the planet." Brazilian Government's Ministry of External Affairs,2002