WATER RESOURCES

Water: we waste it, we pollute it, we take it for granted…. Virtually the most valuable commodity we have (along with O 2 ) Tree = 60% water Jelly fish = 90% water 2

The water planet atmospheric water continental and sea ice oceans lakes and rivers O Water H H + - 3

All of the Earth's waters are circulated 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 Where has your water been? 4

The hydrological cycle 5

Evaporation Injects water vapour into atmosphere Uses 50% of energy at earths surface (cools the earth’s surface) 6

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 returning water to the earth or oceans 7

Rain doesn’t always make it to the earth P — precipitation 8

E I —evaporation of intercepted rain E T —transpiration Interception loss may be 20 – 40% of total rainfall for forests Rain doesn’t always make it to the earth 9

Snow can turn into glaciers and remain on land a long time 10

Antarctic ice photo by Megan Balks, Waikato Univ. 11

Discovering Planet Earth Rain that does make it to the earth can do several things… infiltration overland flow 12

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. 13

Aquifers 14

Waimakirri River, New Zealand Rivers return water from the land to the ocean 15

The Water Balance May be applied to whole river basins or catchments (watersheds) total evapotranspiration catchment rainfall river + groundwater discharge change in soil or groundwater storage 16

Quantifying the hydrological cycle Rainfall to a watershed P = 15 mm Evapotranspiration E = -4 mm Discharge in stream Q = -6mm Change in storage Q = + 5mm 17

Rivers 18

Boreal stream with organic acids flowing north to the arctic 19

Most of earth’s water is in the oceans 20

Water in the atmosphere helps trap heat (H 2 O is a greenhouse gas) and distribute heat The hydrologic cycle is the main global energy redistribution system -thru both the oceans and the atmosphere Running the hydrological cycle takes energy! Most of the energy for the hydrologic cycle comes from the sun 21

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) 22

The hydrological cycle 23

24 Titan: methane cycle

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ONLY % of world’s water is readily available AND this is NOT evenly distributed (many water-poor countries in the middle east) Human water use has increased 4-fold in the last 50 yrs! increasing population and increasing use per person Approximately 70% of water used is for Agriculture 26

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- The BIGGEST water use  world irrigation area tripled u 1990: 7% less irrigated area per person than 1980 u increased competition between rural and urban water use u 21% of USA crop irrigated by draw-down of water table 26% of world irrigated area suffers waterlogging and salinization This is NOT SUSTAINABLE 28

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The Ogallala Aquifer 30

Two main problems associated with groundwater usage: Withdrawal can result in: depletion (removal of water from aquifers faster than it can be replaced) land subsidence salt water intrusion Discharge can pollute groundwater (groundwater is very vulnerable to pollution which can be very costly and difficult to clean) 31

Dams and Canals redistribute water from areas of water surplus to water deficit areas Dams are built to minimize flood damage, store water, or provide hydroelectric power Environmental impacts of dams include: sediment accumulation, downstream scouring, water loss from evaporation, salinization, biological disturbance 32

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sources sinks 34

Water Resources Environmental costs are typically excluded 35

There are many areas where water is scarce! Political and Economic solutions may be needed to effectively use our water Laws now protect some surface and groundwater, but this is not true everywhere Water for agricultural use is subsidized--no incentive to conserve McKinney and Schoch,

There are many ways to increase efficiency in our use of water Microirrigation for agriculture Individual lifestyle conservation shorter showers don’t let the water run low-flush toilets Xeriscaping Wastewater reclamation 37

Water use 38

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 39

Key Points: Water circulates among the atmosphere, rivers, oceans, groundwater, glaciers and other locations through the hydrological cycle The hydrologic cycle is powered by the sun; it is a major way that global energy is redistribution Liquid Fresh water is a very small amount of the world’s total water supply (0.6% with only <0.03% readily available) Demand for fresh water is increasing, particularly for agriculture which uses most of the consumed water Water is not equally distributed throughout the world and conservation measures will become increasingly important as water demand increases and conflicts for water use increase 40