Water Resources, Usage, and Problems from Use Environmental Science Chap 20 Sect 1 & 2

Essential Questions to Examine Why is Water So Important?

Water For Life!! Helps shape our continents & moderates climate Medium by which living processes occur –Required by chemical reactions –Dissolves important substances for life- minerals, oxygen, nutrients –Removes wastes Regulates body temp and global temperature Supports structures- cells 60-70% of your body is water You can only survive a few days without it

Hydrologic Cycle Process by which Earth’s water supply is continually collected, purified, and distributed –Describes the circulation of water as it evaporates, condenses, and falls to the Earth surface Processes involved are: –Evaporation –Transpiration –Condensation –Precipitation –Infiltration

Hydrologic Cycle a.k.a The Water Cycle

Water as a Resource Availability of fresh, usable water is limited. Freshwater Resources Include: –Surface Water –Groundwater

Water Resources- Surface Water Surface Water- above ground water Run-Off- water flowing across land from rain or melted snow and ice into bodies of water –Creates rills- shallow grooves Watershed (drainage basin)- land areas that drain run-off water into bodies of water –Rivers, streams, etc.

Water Resources- Groundwater Most groundwater considered a “nonrenewable” resource Groundwater will eventually discharge into surface water Groundwater- underground supply of freshwater from precipitation seeping into soil –Infiltration-process where water percolates into soil and pores of permeable rock

Groundwater: Water Table Water Table- upper surface of groundwater, ground below is completely saturated by water –Zone of saturation- saturated rock layer below water table –Zone of aeration- area where water enters an aquifer –Zone of discharge- where groundwater leaves an aquifer & becomes surface water

Water Resource- Groundwater Aquifer-underground porous rock or caverns that contain groundwater –Confined (artesian) – storage area trapped between 2 impermeable rock layers Water is trapped, often underpressure Recharge area is often miles away –Unconfined- groundwater storage located above a layer of permeable rock Allows surface water to percolate and recharge (replenish)

Aquifer- Groundwater Use Problems Depletion- water withdrawn faster than recharge –Most recharge rates are very slow –Some recharge zones “covered” by development

UH OH SINKHOLE!! Subsidence- Withdrawal of groundwater cause porous formations to collapse –Surface settling –Sinkholes- form when too much water withdrawn from caverns and aquifers –Roof of the underground cavern collapses, creates a large surface crater

Collapse of an Aquifer

Aquifer- Groundwater Use Problems Salt Water Intrusion- occurs along coast Withdrawal of freshwater allows salt water to enter aquifer

Water Usage and Resources Water consumption varies by country due to its availability. –Domestic & municipal uses 9% –Industry uses 20% –The largest use of water worldwide is agriculture using 71% of total water consumption. According to the USGS- in 2005, 410,000 million gallons per day (Mgal/d) of water was withdrawn for use –80 % (328,000 Mgal/d) was from surface water –20 % (82,600 Mgal/d) was withdrawn from groundwater

Domestic Use of Water Domestic water use is water used for indoor and outdoor household purposes –drinking, preparing food, bathing, washing clothes and dishes, brushing your teeth, watering the yard and garden, and even washing the dog U.S. Sources: city/county water department or from a well. Average person in U.S. uses 300 Liters/day –Personal hygiene –Home cleaning & maintenance

Industrial Water Use Access to water a factor in short term & long term plans of industry Water is used by Industries that produce: –metals, wood and paper products, chemicals, gasoline and oils, –fabricating, processing, washing, diluting, cooling, or transporting a product –incorporating water into a product; or for sanitation needs within the manufacturing facility.

Agricultural Water Use Single largest user of water in U.S. Approx 200 billion L/day Used for livestock and crop production Irrigation is largest form of use –Flood irrigation –Furrow irrigation –Overhead irrigation –Subirrigation

Types of Irrigation Flood irrigation- flooding of flat area of land, inexpensive method –Very wasteful evaporation takes 50 % of water Furrow irrigation- releases water into furrows/ditches dug between crop rows –Evaporation rate is up and mineral salts accumulate

Types of Irrigation Overhead irrigation- –Sprinkler- flat & uneven slopes Efficiency is decreased with strong winds –Drip or trickle- very efficient but expensive Uses tubing to deliver small quantities of water to plant roots Great for areas where water supply is low Subirrigation- water introduced naturally or artificially beneath the soil –Effective in places where water is close to surface

Global Water Use Global averages vary a great deal between regions. Look at the examples below, tell me what do you think is different about these continents and how do you think that determines how they use water? In Africa, In Europe –agriculture consumes 88 % of all water withdrawn for human use –domestic use accounts for 7 % –industry for 5 %. –industry 54 % –agriculture's 33 % –domestic 13 %

Georgia Water Use In 2000, 6,490 million gallons per day (Mgal/d) Thermoelectric power 3,310 Mgal/d from surface water. –17 plants operate using fossil fuels & 2 nuclear-powered plants. hydroelectric power plants estimated to be 31,900 Mgal/d. –Most water remains in system, not counted as “Used”

Georgia Water Use Agricultural totaled 1,130 Mgal/d (1,090 Mgal/d for irrigation and 35 Mgal/d for livestock) % of water use Public-supply was 1,250 million gallons per day (Mgal/d), –surface-water withdrawal = 78 % –ground-water = 22 %

Water Problems: Too Much Water Flooding- a natural event, human activities contribute to removal of natural vegetation and floodplains (wetlands, etc.) greater frequency of impermeable surfaces

Water Problems: Too little water 3 primary reasons for freshwater shortages 1)Increasing pollution of existing water supplies- To be discussed in the next chapter must know that it’s a problem found with usage. 2) Climate- precipitation varies due to topographical effects (mountains, location on Earth i.e. latitude, near the coastline, desert belts, etc.) Cycles of wet and dry years create temporary droughts

Water Problems: Too little water 3) Rising Demands  Populations increasing  More water used for drinking, sanitation, agriculture, recreation, and industrial uses  More demand placed on surface and groundwater resources  Examples: Colorado River and Ogallala Aquifer

Rising Demands and Water Shortages- Colorado River Begins in N. Central Colorado- Ends in Gulf of California (1450 miles long) 7 states are in its Watershed- Colorado, Wyoming, Nevada, Utah, Arizona, N.Mexico, California –California River Compact (1922) divided up water among these states –each would receive 7.5 million acres /yr –all water is “spoken for” w/ population increases/development not enough water to go round Colorado River sometimes dries out before it can make it to the Gulf of California

Ogallala Aquifer  Largest groundwater source in the world  Farmers drawing water 40 times faster than it can recharge  Water table has lowered more than 30meters in some areas  Feared that groundwater level in aquifer will drop to a level to expensive to pump

Environmental Impact

Water Management

Water Management- Globally