• Figure 7-1 Earth’s water supply

Problem: Fresh water availability

Key Facts

• The primary use for fresh water in U.S. is for agriculture.

• In our homes, we use the most fresh water to wash, clean, and flush.

• The typical person in an industrialized nation uses 700-1000 gallons per week!

• Figure 7-4 Condensation

(The a

moun

t of

wate

r in

th

e a

ir)

Human effects on the Hydrologic Cycle

Figure 7-3 The Hydrologic cycle

• Figure 7-6a Global air circulation

Figure 7-6b Global air flow patterns

Rain shadow

Figure 7-7 Rain shadow

The Ogallala Aquifer

Figure 7-16 Exploitation of an aquifer

Reasonable access to safe drinking water is defined as the availability of at least 20 liters per person per day from an improved source within 1 kilometer of the user's dwelling.

Percentage of Population Without Reasonable Access to Safe Drinking Water 2008

http://www.theglobaleducationproject.org/earth/human-conditions.php

Population with access to safe water, 1990 pg. 213

Saltwater Intrusion

•

Figure 7-18 Saltwater Intrusion

Mono Lake

• Excellent example of human interference with the water supply.

• The water in the lake was diverted from the lake to the city of Los Angeles. It became a salt bed.

• ↑ Salt concentration due to evaporation

Agriculture

• Green Revolution- the introduction of high-yield grains to agriculture.

• High yield varieties are not ideal for subsistence farming because they need pesticides and chemical fertilizers.

• Sustainable- Crop rotation, variety of crops, animal wastes for fertilizer.

• The best, most effective way to solve world hunger is to help people provide for themselves.

Water Quality tests

• Nitrates

• pH

• Phosphates

• What do they tell you about your water?

Figure 7-6c Global trade winds

Figure 7-5 Global Precipitation

Figure 7-5 Global precipitation