1. Sustainability
Chapter 12

2. Sustainability
A sustainable activity is one that can be continued or repeated for the foreseeable future
How much human activity is sustainable?

3. Sustainability
Can we allow the global human population to continue to grow?
What resources do we require, and how do we acquire them?
Famine, disease, war

4. Sustainability Peruvian anchoveta fishery
Can we continue to harvest fish faster than they can replace themselves?
Maximum sustainable yield
Fixed quota
Fixed effort

5. Sustainability
Can we continue to harvest agricultural crops if the quality and quantity of soil deteriorates?
New soil t/ha/yr
Erosion t/ha/yr
Dust Bowl in central U.S s

6. Poor Agricultural Practices
Farming steep slopes
Removing fence rows
Moldboard plowing (in fall)
Overgrazing
Farming natural waterways
Compacting soil with large machines
Lack of crop rotation

7. Sustainability
Can we continue to demand and use more water despite its chronic scarcity and increasing contamination?
Fresh water recycled by water cycle, but humans now use >1/2 of accessible supply
Few water resources remain pristine

8. Lowering the Water Table
Original
water table
Initial water table
Cone of
depression
Lowered
water table

9. Groundwater Overuse Groundwater Overdrafts: High Moderate
Minor or none

10. Saltwater Intrusion Major irrigation well Well contaminated
with saltwater
Water table
Sea Level
Salt
water
Fresh
groundwater
aquifer
Interface
Interface
Saltwater
Intrusion
Normal
Interface

11. Transferring Water from One Place to Another
Watershed transfer
North Bay
Aqueduct
South Bay
California Aqueduct
CALIFORNIA
NEVADA
UTAH
MEXICO
Central Arizona
Project
Colorado River
Los Angeles
Shasta Lake
Sacramento
Fresno
Phoenix
Tucson
ARIZONA
Colorado
River
San Francisco
San Diego
California Water Project
Central Arizona Project

12. Saving Water in the Bathroom

13. Gray Water Systems

14. Sustainability
Can we continue to use the same pesticides if increasing numbers of pests become resistant to them?
Genetic resistance - accelerated selection for resistant individuals

15. Bioaccumulation/biomagnification - DDT and the bald eagle
Pesticide Problems
Persistence
Bioaccumulation/biomagnification
- DDT and the bald eagle
Nonspecificity
Broad spectrum vs. selective pesticides

16. Biological Controls: Alternatives
Predators or parasites
Attractants (pheromones = sex hormones)
Sterilization
Resistant crops (genetic)