Sustainability Chapter 12 Sustainability n n A sustainable

Sustainability Chapter 12

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

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

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

Sustainability Can we continue to harvest agricultural crops if the quality and quantity of soil deteriorates? New soil - 0. 2 t/ha/yr Erosion - 2. 0 t/ha/yr Dust Bowl in central U. S. - 1930 s

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

Sustainability Can we continue to demand 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

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

Groundwater Overuse Groundwater Overdrafts: High Moderate Minor or none

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

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

Saving Water in the Bathroom

Gray Water Systems

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