Water A Fragile Resource Chapter 14

SF Delta Heart of the California Water system Heart of the California Water system –Drains 45% of California –Largest, most productive estuary on Pacific Coast –Provides drinking water for 2/3 of states population

Water Facts Water covers ¾ of earth’s surface Water covers ¾ of earth’s surface ___ of earth’s water is salty ___ of earth’s water is salty ____ is in ice caps & glaciers ____ is in ice caps & glaciers ____ is in the groundwater ____ is in the groundwater _____ is in lakes, rivers, atmosphere, etc. _____ is in lakes, rivers, atmosphere, etc.

More Facts Humans are made up of ____ water by weight Humans are made up of ____ water by weight Humans use ___% of all fresh water flowing in rivers and Streams Humans use ___% of all fresh water flowing in rivers and Streams By 2025, more than 1/3 of world population could live in areas without sufficient water By 2025, more than 1/3 of world population could live in areas without sufficient water

Chemical Properties of Water Water exists in 3 forms Water exists in 3 forms –Solid (ice) –Liquid –Vapor (steam) Water is a polar molecule Water is a polar molecule Hydrogen bonds are between molecules Hydrogen bonds are between molecules

More chemical properties Melting and freezing point Melting and freezing point Boiling point Boiling point High heat capacity – High heat capacity – Water is has the highest density at ___degrees C Water is has the highest density at ___degrees C

Definitions Vaporize – Vaporize – Sublimate – Sublimate – Universal Solvent – many things dissolve in water Universal Solvent – many things dissolve in water

More Chemical Properties Water is found mainly in molecules but some are broken up into hydrogen ions (H+) and hydroxide ions (OH-) Water is found mainly in molecules but some are broken up into hydrogen ions (H+) and hydroxide ions (OH-) More (H+) than (OH-) ions => More (H+) than (OH-) ions => Less (H+) than (OH-) ions => Less (H+) than (OH-) ions =>

pH [H+][OH-] = K w = [H+][OH-] = K w = –K w is the dissociation constant of water If [H+] = [OH-] (as in pure water) If [H+] = [OH-] (as in pure water) [H+] = [OH-] = K w ½ =  Neutral (neither more H+ or OH-) pH = -log 10 [H+] pH = -log 10 [H+]  So, if [H+] = then pH=7

Hydrologic Cycle Surface water – Surface water – Surface water is replenished with runoff. Surface water is replenished with runoff. Reservoir – Reservoir – Drainage basin – Drainage basin – Watershed – Watershed –

Groundwater Water under the ground surface that flows through permeable sediments or rocks. These formations are called aquifers. The water moves very slowly. Water under the ground surface that flows through permeable sediments or rocks. These formations are called aquifers. The water moves very slowly. Unconfined aquifers – Unconfined aquifers – The uppermost unconfined aquifer is the water table aquifer The uppermost unconfined aquifer is the water table aquifer

Groundwater (continued) Confined aquifer – Confined aquifer – Confined aquifers are under lots of pressure such that the head is above the ground surface => artesian aquifer. Confined aquifers are under lots of pressure such that the head is above the ground surface => artesian aquifer. Groundwater may be recharged from areas very far away Groundwater may be recharged from areas very far away Aquifer storage recovery – Aquifer storage recovery – –Way to store groundwater below ground surface –Manage it as a renewable resource.

Groundwater

Types of Uses of Water Worldwide Agriculture for irrigation – __% Agriculture for irrigation – __% Industry – __% Industry – __% Municipal – _% Municipal – _%

Precipitation Arid Lands – low precipitation (desert) Arid Lands – low precipitation (desert) Semi-arid land – more precipitation than deserts, but subject to frequent and prolonged droughts. Semi-arid land – more precipitation than deserts, but subject to frequent and prolonged droughts.

What problems exist for water resources? There are three: There are three: –Too much water –Too little water –Poor quality/contamination

Too Much/Flooding Building/constructing in flood plains Building/constructing in flood plains Removal of water-absorbing plant cover Removal of water-absorbing plant cover Constricting rivers/streams by levees => loss of meanders. Constricting rivers/streams by levees => loss of meanders. Paving reduces infiltration and increases runoff Paving reduces infiltration and increases runoff Loss of wetlands/offstream storage Loss of wetlands/offstream storage

Too little water Drought Drought Overdraw surface water Overdraw surface water Overdraft groundwater => aquifer depletion Overdraft groundwater => aquifer depletion Salinization of irrigated soil Salinization of irrigated soil Increase in salinity in estuaries due to less addition of freshwater Increase in salinity in estuaries due to less addition of freshwater Humans can remove ~30% of river flow without affecting the natural ecosystem. Humans can remove ~30% of river flow without affecting the natural ecosystem.

Where does all that rain water go? __% of water that falls as precipitation per day returns to atmosphere as evaporation and transpiration __% of water that falls as precipitation per day returns to atmosphere as evaporation and transpiration __% runs off to rivers, streams and lakes __% runs off to rivers, streams and lakes __% seeps into groundwater __% seeps into groundwater

Reclaimed Water Treated wastewater that is reused in someway Treated wastewater that is reused in someway Recycled water/grey water – untreated water that is reused in some way. Recycled water/grey water – untreated water that is reused in some way.

Stable Runoff Portion of runoff from precipitation that is available throughout the year. Portion of runoff from precipitation that is available throughout the year.

Global Picture Globally, there is enough water to meet everyone’s needs but poor distribution. Globally, there is enough water to meet everyone’s needs but poor distribution. South America and Asia are the two continents with the greatest total water supply. South America and Asia are the two continents with the greatest total water supply. 80% of human illness stems from insufficient or poor water quality. 80% of human illness stems from insufficient or poor water quality.

Water management goals The goal is to have sustainable water use. The goal is to have sustainable water use. This can be achieved by: This can be achieved by: –Reusing water –Recycling water –Improving water efficiency –Dams/reservoirs to confine and regulate water supplies –Desalinization/reverse osmosis

Water Reduction In agriculture – In agriculture – In industry – In industry – –90% of water is used for chemical production, paper/pulp mills, petroleum/coal, primary metal manufacturing, food processing. In municipalities – In municipalities –