Guided Notes about Water Resources Chapter 25, Section 4

1. Only 3 percentof the Earth’s water is freshwater. Of this, 2.997% is locked up in ice caps or glaciers or stored as groundwater that is too deep to extract. This leaves only 0.003% of the Earth’s total volume of water available to humans for domestic, agricultural, and industrial purposes. 1. Only 3 percent of the Earth’s water is freshwater. Of this, 2.997% is locked up in ice caps or glaciers or stored as groundwater that is too deep to extract. This leaves only 0.003% of the Earth’s total volume of water available to humans for domestic, agricultural, and industrial purposes.

2. The world’s oceans help regulate climate, provide habitats for marine organisms, dilute and degrade many pollutants, and help shape the Earth’s surface

3. Water can exist as a liquid over a wide range of temperatures because of the hydrogen bonds between water molecules.

4. Water has a high boiling point, 100˚C, and a low freezing point, O˚C. As a result, water remains liquid in most environments on Earth.

5. Liquid water can store a large amount of heat without a correspondingly high increase in temperature. This is responsible for water’s ability to regulate earth’s climate.

6. Liquid water can dissolve a wide variety of compounds, which enables water to carry nutrients into, and waste products out of, the tissues of living things.

7. Unlike most liquids, water expands when it freezes.

8. Freshwater resources are not distributed evenly across Earth’s landmasses. The eastern states receive ample precipitation while the western states often have too little.

9. About 25 countries, most in Africa, experience chronic water shortages. This number is expected to rise to 90 countries by the year 2025.

10. The current rate of withdrawal of freshwater worldwide is 5 times greater than it was 50 years ago. Withdrawal rates are expected to double again within the next 20 years.

11. Nearly 80% of water used for irrigation evaporates or seeps into the ground before it can be used by crops.

12. Most countries manage their freshwater supplies by building dams, transporting surface water, or tapping groundwater.

What are the advantages of building a dam across a river valley? they control flooding downstream they control flooding downstream Water can be released as necessary Water can be released as necessary Provides water for hydroelectric power Provides water for hydroelectric power

How do countries transport surface water today? Many countries use aqueducts, tunnels, and underground pipes to bring water from areas where it is plentiful to where it is needed. Many countries use aqueducts, tunnels, and underground pipes to bring water from areas where it is plentiful to where it is needed.

15. Because groundwater is the source of many streams in the U.S, groundwater depletion also affects stream flow.

16. Most experts agree that they best way to meet the need for freshwater is to use available supplies more efficiently.

List several ways to reduce domestic use of freshwater: Farmers can change their irrigation methods, such as trickle irrigation Farmers can change their irrigation methods, such as trickle irrigation Industries can use recycled water for manufacturing processes Industries can use recycled water for manufacturing processes Homeowners can install low-flow toilets, plant drought-resistant plants for landscaping, and fix leaking pipes or faucets Homeowners can install low-flow toilets, plant drought-resistant plants for landscaping, and fix leaking pipes or faucets