The water planet atmospheric water continental and sea ice oceans lakes and rivers O Water H H + -

Water: we waste it, we pollute it, we take it for granted…. Virtually the most valuable commodity we have (except maybe O 2 ) Tree = 60% water jelly fish = 90% water Where has your water come from???

All of the Earth's waters are connected and cleaned by the HYDROLOGIC CYCLE Water moves through the hydrologic cycle at various speeds. For example: 40,000 years to recycle oceanic water 2 weeks to recycle river water 9 to 10 days to recycle atmospheric water

Energy for the hydrological cycle is from the sun (solar power) The atmosphere is a heat trap –H 2 O is a greenhouse gas Hydrologic cycle = main global energy redistribution system --thru both the oceans and the atmosphere

Ocean currents The Atlantic Gulf stream carries energy at a vast rate from the gulf of Mexico to the Arctic Ocean: all the coal mined in the world in one year could supply energy at this rate for only 12 hours!(Franks 1984)

The hydrological cycle

Evaporation Injects water vapour into atmosphere Uses 50% of energy at earths surface (cools the earth’s surface)

The Atmosphere only 0.001% of all water links major water stores –evaporation –condensation –precipitation cold air hold less water than hot air as hot air rises and cools, precipitation can form

Effect of vegetation on rainfall P — precipitation

Effect of vegetation on rainfall E I —evaporation of intercepted rain E T —transpiration Interception loss may be 20 – 40% of total rainfall for forests

Hillslope runoff processes infiltration overland flow water table shallow subsurface flow deep drainage baseflow

The majority of accessible fresh water is groundwater, water beneath the Earth's surface. About 10% of precipitation will infiltrate the soil and rock to become groundwater, forming a water table. Water saturated permeable rock is an aquifer.

Aquifers

Rivers

The Water Balance May be applied to whole river basins or catchments total evapotranspiration catchment rainfall river + groundwater discharge change in soil, groundwater storage

The water balance Quantifying the hydrological cycle saturated zone unsaturated soil Rainfall P Evaporation E Change in storage  S Discharge Q = +15 mm = -4 mm = -6 mm 15 – 4 – 6 = +5 mm = +5 mm

u 0.03% of world’s water is readily available u Not evenly distributed u human water use has increased 4 times in the last 50 yrs! increasing population and increasing use per person u ~70% used for Agriculture u waste water production=1870 km 3 in km 3 in 2000

- The BIG water use  world irrigation area tripled u 1990: 7% less irrigated area per person than 1980 u inc. competition between rural and urban water use u 21% of USA crop irrigated by draw-down of W.T 26% of world irrigated area suffers waterlogging and salinization NOT SUSTAINABLE

The Ogallala Aquifer

Water use

WATER SAVINGS GUIDE Activity: Conservative use - saves water Normal use -- wastes water Shower Wetdown/rinse off: 4 gallons Regular shower: 25 gallons Brushing teethWet brush, brief rinse: 1/2 gal. Tap running: 10 gallons ToiletsMinimize flushing, low-flush toilets Old toilet, frequent flushing?!?! LeaksReport ASAPA small drip: 25 gallons per day EnergyTurn off powerWasting energy wastes water