Chapter 13 Water: A Limited Resource

Overview of Chapter 13 Importance of Water Hydrologic Cycle Water Use and Resource Problems Too Much Water Too Little Water Water Problems in US and Canada Global Water Problems Sharing Water Resources Water Management Providing Sustainable Water Supply Water Conservation

Importance of Water Cooking Washing Use large amounts for: Agriculture Manufacturing Mining Energy production Waste disposal Use of freshwater is increasing

Properties of Water Composed of 2 Hydrogen and 1 oxygen Exists as solid, liquid or gas High heat capacity – absorbs a lot of solar energy without increasing in temperature much. Earth’s temperature matches temperature for water as a liquid. “universal solvent” allows dissolved gases and minerals in water, including pollutants Colder water is more dense until 4 Celsius, then becomes less dense (ice floats and allows living things beneath)

Hydrologic Cycle

Only 2.5% of water on earth is freshwater 2% is ice! Distribution of Water Only 2.5% of water on earth is freshwater 2% is ice! Only ~0.5% of water on earth is available freshwater

Check for understanding 4 - I can explain to my peers at least 5 properties of water and how water is distributed on earth. 3 - I understand 3-4 properties of water and how water is distributed on earth. 2 - I can explain at least 2 properties of water and how water is distributed on earth. 1 - huh? I know 1 property of water.

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 Unconfined and confined (artesian) Water table

Freshwater Aquifer

Check for understanding 4 - I can explain to my peers the difference between a confined and unconfined aquifer, what a water table is and the difference between groundwater, surface water, runoff, and a watershed is. 3 - I understand the difference between a confined and unconfined aquifer, but might not fully understand the difference in one of the following terms: a water table, groundwater, surface water, runoff, and watershed 2 - I am confused about at least 2 of the above terms 1 - I am confused about at least 3 of the above terms

Water Use and Resource Problems Fall into Three Categories Too much water Too little water Poor quality/contamination (discussed later)

Water Use Mostly for irrigation for agriculture: 68% Industry Even arid (deserts) & semiarid land grow crops with enough H2O Asia uses most Industry Domestic/municipal: 8.6% xeriscaping

Too Much Water Flooding Both natural and human-induced. Causes??? Modern floods are highly destructive because humans: Remove water-absorbing plant cover from soil Construct buildings on floodplains Floodplain Area bordering a river channel that has the potential to flood Naturally leave behind organic matter in soil – good. Flood consequences???

Urban vs. Pre-Urban Floodplains

Floodplain Government restrictions on building Levees can fail Rather than rebuild levees adjacent to rivers, experts suggest allowing some flooding of floodplains during floods Less damage if flooded Replenish soil Save money

Left: Traditional levees adjacent to river Right: Suggested levee style, set back from river

NEW ORLEANS: HURRICANE KATRINA: AUGUST 2005

Case-In-Point Floods of 1993: Mississippi River Worsened due to: Draining wetlands for farms and homes 2. Building levees (can force more surge upstream) 3. Building on floodplains Similar to New Orleans

Check for understanding 4 - I can explain to my peers the causes and consequences of flooding and the problems associated with flooding and why modern societies suffer more damage from them. 3 - I understand the causes and consequences of flooding and the problems associated with flooding and why modern societies suffer more damage from them 2 - I need to reread my notes, but I understand 1 - I don’t fully understand flooding.

Too Little Water Typically found in arid land (40% of population – Africa/Asia) Women may walk to get water instead of school Problems Drought Remove native water absorbing plants and replace with crops/livestock overgraze  more runoff, less water in soil Overdrawing water for irrigation purposes  saltier estuaries, dried wetlands (loss of bird breeding grounds)

Too Little Water Problems (continued) Aquifer depletion Subsidence – sinking of land on porous rock Sinkholes – eroded limestone Saltwater Intrusion (coasts)

Problems (continued) Aquifer depletion Saltwater Intrusion (coasts)

Water Problems In US US has a plentiful supply of freshwater Many areas have a severe shortages Geographical variations Seasonal variations

Water Problems in US Water shortages in West and Southwest Historically for irrigation, now more water for industrial and municipals due to increased population Water is diverted and transported via aqueducts

Water Problems in US Surface Water Mono Lake (Eastern CA) Rivers and streams that once fed this lake are diverted to Los Angeles (275mi away) Becoming highly saline due to water diversion  disrupt food chain Court ordered water diversion reduction LA efforts to use more reclaimed water Colorado River Basin Provides water for 27-million people – Colorado, California, Arizona, into Mexico Numerous dams for Hydropower; also create resevoirs Colorado River no longer reaches ocean

HOOVER DAM: BETWEEN ARIZONA AND NEVADA

SALMON FISH LADDER

Colorado River bed in Mexico

Check for understanding 4 - I can explain to my peers how water diversion and dams can disrupt the amount of water in effected areas. 3 - I understand how water diversion and dams can disrupt the amount of water in effected areas 2 - I need to reread my notes, but I understand 1 - I don’t fully understand the impact of water diversion projects and dams.

Water Problems in US and - Groundwater Aquifer Depletion – especially Arizona, California, High Plains

Case study: Ogallala Aquifer High Plains Largest groundwater in world Uses 30% of irrigation water in US – corn, wheat, soybean, livestock (6% of land) Water table down 100 ft in some areas (rate of recharge less than rate of extraction) cost money to deepen wells, lose $ on dead crops

Global Water Problems Amount of freshwater on planet CAN meet human needs BUT, it is unevenly distributed and some places lack stable runoff

Global Water Problems 1. Water and Climate Change Climate change affects the type and distribution of precipitation Potential issues: Reduced snowfall will impact water resources downstream Sea level rise will cause saltwater intrusion into drinking water supplies

Global Water Problems 2. Drinking Water Problems Many developing countries have insufficient water to meet drinking and household needs (1.1 billion lack safe water, 2.6 billion no good disposal of wastewater/fecal waste)  illness Ex: Cholera Ex: Sahel region of Africa Help: World Bank, US Agency for International Development (AID)

3. Population Growth Increase in population means an increase in freshwater requirements Limits drinking water available Limits water available for agriculture (food) Ex: Northern China – Yellow River, Indus River in Pakistan, Mexico (aquifer)

Global Water Problems 4. Sharing Water Resources Among Countries Rhine River Basin (right) Countries upstream discharged pollutants into river Countries downstream had to pay to clean the water before they could drink it Aral Sea Kazakhstan and surrounding countries Water diversion for irrigation has caused sea to become too saline  decreased biodiversity

Aral Sea 1967 1997

Check for understanding 4 - I can explain to my peers how climate change, pathogens, a growing population, and water diversion can reduce water availability. 3 - I understand how climate change, pathogens, a growing population, and water diversion can reduce water availability 2 - I need to reread my notes, but I understand 1 - I don’t fully understand the impact of climate change, pathogens, a growing population, and water diversion can have on water availability.

Global Water Problems 5. Potentially Volatile International Water Situations Jordan River – supplies many middle Eastern countries Nile River (NE Africa) – Sudan and Ethiopia using more (increased population) and affecting Egypt’s supply

Water Management FUN FACT: For every kilogram of animal protein produced, livestock are fed nearly 6 kg of plant protein. Every kilogram of beef produced takes 100,000 liters of water. A kilogram of wheat requires 900 liters of water.

Water Management Main Goal: Provide sustainable supply of high-quality water Requires humans to use resource carefully Dams and Reservoirs Water Diversion Projects Desalinization THREE GORGES DAM - CHINA

Dams and Reservoirs Benefits: Disadvantages Ensure year-round supply of water with regulated flow Generate electricity Provide recreational activities Disadvantages Alter the ecosystem Reduce sediment load downstream Displace humans Disrupt salmon migration for breeding

Dams and Reservoirs Glen Canyon Dam To rectify situation Regulated flow has changed ecosystem To rectify situation Canyon has been flooded several times Small floods compared to natural floods Still helps rebuild habitat

Water Diversion Projects Diverting water via aquaducts/canals Ex: Mono Lake, Aral Sea Controversial and expensive ARAL SEA: Kazakhstan-Uzbekistan border

Desalinization Removal of salt from ocean or brackish water Two methods: Distillation- salt water is evaporated, and water vapor is condensed into freshwater (salt left behind) Reverse Osmosis- involves forcing salt water through a membrane permeable to water, but not salt Very expensive due to large energy input What to do with left over salt?

Check for understanding 4 - I can explain to my peers how dams/reservoirs, desalinization, and water diversion makes water available for human use and the consequences of each. 3 - I understand how dams/reservoirs, desalinization, and water diversion makes water available for human use and the consequences of each 2 - I need to reread my notes, but I understand 1 - I don’t fully understand how dams/reservoirs, desalinization, and water diversion makes water available for human use and the consequences of each

Water Conservation Reducing Agricultural Water Waste Drip Irrigation- irrigation that conserves water by piping to crops through sealed systems Also called microirrigation or trickle irrigation

Water Conservation Reducing Industrial Water Waste EX: paper, petroleum, food processing Stricter laws (and enforcement of those laws) provide incentive to conserve water EX: Recycling water within the plant Water scarcity (in addition to stricter pollution control requirements) will encourage further industrial recycling Potential to conserve water is huge!

Water Conservation Reducing Municipal Water Waste : reduce, reuse, recycle Gray Water (reclaimed water) Can be used to flush toilets, wash car or water lawn Water saving household fixtures Raising costs to reflect real cost Government incentives

Conserving at Home Install water-saving shower heads and faucets Install low-flush toilets Fix leaky fixtures Purchase high efficiency appliances – dishwasher/washing machine Modify personal habits Shorter showers, showers not baths Use the dishwasher instead of washing by hand

Check for understanding 4 - I can explain to my peers ways for agriculture, industry, and homes can conserve water. 3 - I understand ways for agriculture, industry, and homes can conserve water 2 - I need to reread my notes, but I understand 1 - I don’t fully understand ways for agriculture, industry, and homes can conserve water.