1. AGRON / MTEOR 404 Global Change Changes to Water Resources Raymond Arritt Department of Agronomy

2. Effects of water resources erosion Timing in crop growth cycle Runoff – wastewater treatment, pollution Groundwater depletion, subsidence Distribution of rainfall, shifting patterns Hydropower (energy) Distribution of ecosystems; desertification

3. Effect on flood plains Water ownership – who gets to use it? Ecology and biodiversity – new species introduced, take over and lose diversity Shift in rainfall patterns (wet and dry regions) Sustainable development – building

4. Irrigation systems – change in demand Energy production – cooling water for powerplants and industry Water conservation awareness Snowmaking for ski areas Dams and storage Glaciers How do we get people to understand?

5. IPCC Fourth Assessment Report Summary for Policy Makers

6. A simple surface water budget Precipitation – Evaporation = Runoff +  Storage storage includes lots of things: soil moisture, aquifers, reservoirs, withdrawals for irrigation, glaciers, snowpack, etc.

7. IPCC Fourth Assessment Report Summary for Policy Makers

8. Change in annual runoff 2041-2060 compared to 1900-1970 Where do we see increases in runoff? Where do we see decreases?

9. Predicted changes in groundwater recharge

10. Some observed effects on water resources

11. Predicted effects of climate change on water resources

12. Fastest growing states

13. Water resource stress without climate change Current 2055 (IPCC A2 scenario)

14. Change in water resource stress with climate change reduced water stress in tropical regions increased water stress outside the tropics results from two different climate models

15. What is drought? One definition: Elements of the definition: –deficiency of precipitation –extended period (how long is "extended"?) –water shortage for some user ("group or activity") A deficiency of precipitation over an extended period that causes water shortage for some group or activity.

16. Drought depends on the user Crops rely on stored soil water. Soil water can be rapidly depleted, so that monthly droughts may affect crops.

17. Drought depends on the user Rivers and streams may dry out during seasonal droughts. Arnie! I found your keys!

18. Drought depends on the user Multi-year droughts may deplete ground water that supports communities.

19. Drought, more precisely Must define the time period over which precipitation is below normal. Must define what is a water shortage that affects a particular activity.

20. Iowa corn yields 1988 drought 1993 flood

21. Remember Changes to water resources depend on more than just the change in rainfall. Whether a change is good, bad, or neutral depends on who we are and what we’re interested in.