1 Next week – (4/27) Global change – 4/29 First Review for Part III unit exam (final exam) –-Begin comprehensive question– due May 4 Notes 4/22

Final Exam Comprehensive Question: Comprehensive integration (50 pts): Imagine yourself as a content advisor to Tucson's Rio Nuevo Project, which has the goal of educating citizens about environment-human issues of the Southwest. Choose a modern Southwest environment-human issue from Part 3 of our course that you think should be included in museum displays and exhibits. For this issue: Explain why it is important currently. Describe a historic or prehistoric example of the issue (from our Part 2). Describe the environmental background to the issue (from our Part 1). Answer this three times using different issues (lectures) each time. The Geos. 220 course lecture topics are below. Don't be redundant, i.e., don't use any lecture topic more than once Typed, single-spaced; ½-page for each answer Due May 4, 2010

3 Today’s topic: Water in the Southwest Water stats & cycling Groundwater –Subsidence Colorado River Required Reading: General reading: Cadillac Desert

4 Water Information at UA Water Resources Research Center (WRRC) –Campbell, just south of 6th –Free Newsletters Arroyo Arizona Water Resource –Xeriscaping

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6 96% of Earth’s water is ………. 74% of Earth’s fresh water is ……… 99% of Earth’s fresh liquid water is …………. Water water everywhere, not a drop to drink

7 Units: 1000 km 3 /yr (0.26 mill-bill gallons/yr) Oceans: 85% …………, 79% ……………. Fresh water: surface, subsurface, or evap Water Cycle

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Where do we get our Water? ……………… –Wells into aquifers ……………….. –Reservoirs & streamflow ………………… –Small scale homeowners (not for drinking) 10

11 What Is An Aquifer? Aquifer - sands with water filling the pore spaces between the grains bedrock water table aquifer

12 Depth can be …………………..feet –Washed down throughout eons of erosion Filled in with water –……………………. water –“Borrowing” water from time. Basin Fill

13 Tucson Wells

Annual Groundwater Budget Tucson Active Management Area Inflow+………… ac-ft Natural and Incidental Recharge, Groundwater Inflow Outflow - …………..ac-ft Municipal, Agricultural and Industrial Pumpage, Groundwater Outflow Balance (OVERDRAFT) -…………… ac-ft Acre-foot: water 1 foot deep covering 1 acre (43,560 ft 2 ) = 325,851 gal. SRC Pool: ~2 acre-feet

15 Consequences Of Overdraft

16 Consequences Of Overdraft 1. Loss in ……………… 2. Increased …………….. 3. Change in water quality 4. Land ……………….. 5. Loss of ………………

17 From over pumping of groundwater Over 15 feet in ~40 years Everything sinks (even trees) Can be general, or with ………………. Subsidence

18 Subsidence in Tucson

19 Subsidence …………… and Infrastructure Not the same as ……………….. Roads damaged Canals crack, sewage flows backwards

20 Extent of Subsidence Areas with 1600 ft. of sediments (gray) Areas with serious subsidence (red) –………….. areas –……………… Conclusion: Best not to deplete groundwater

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22 How Much Water Left Under Tucson? So, ~………… maf left,

23 Well Hydrograph Pima & Swan

24 Consequences Of Overdraft 1. Loss in well productivity 2. Increased pumping costs 3. Change in water quality 4. Land subsidence 5. Loss of surface flows

25 Colorado River Watershed Seems big, but actually not (m 3 /sec): –Colorado: ……. –Columbia: …….. ……. –Miss.: ……………. –Amazon: ……………… Surface Water Source:

26 Lee’s Ferry flow: 13.5 maf/yr How many people would that provide for?

27 Whither the Rainfall? Assume avg ppt of 12 in./yr Assume half of CRB above Lee’s ferry CRB receives over 5x more rainfall than it drains Where does 80% of rainfall go?

28 Colorado River Compact, 1922 AZ: W.S. Norviel (2 nd from left) 4 th from left? (hint: It’s not Haury)

29 WY, CO, UT, NM – Upper Basin AZ, NV, CA – Lower Basin –AZ: ………..of basin, ………… of water –Who was left out? 7.5 maf for each basin per year –75 maf to Lower Basin per decade Extra 1 maf for Lower Basin, just to be nice. Colorado River Compact

30 Flow was assumed to 16.4 maf per year Past 300 years: –Average: 13.5 maf –Range: 4.4 – 22 maf How do we know this? Reality Check

31 …………….. –All within basin –Might claim > 5 maf –Can’t use it, but might sell it ……………. –1944 treaty: 1.5 maf –No flow to delta: water, silt, nutrients Other Parties

32 Colorado River to Tucson? Carl Hayden legacy Begun in 1960s …….. miles of canals Uphill –Havasu: 482 ft. –Enormous pumps Magnificent project $

33 CAP Pump: –~25,000 gal./sec. –~………. ft up Hohokam would be so proud!!

34 Storage into ……………….. Replace groundwater pumping Still not using entire allotment –CAP water unpopular to drink “Tasty,” smelly, different Working better this time –CAP expensive to farm Only 1 profitable crop? –Maybe 2?? Arizona and CAP Water

35 Importing Salts to Southern Arizona CAP water has 580 mg/L salts Where goeth the salts?

36 Groundwater Pumping ………………… through time Used mostly for irrigation

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38 Fix your faucets all you want … People replace cotton and lettuce, water use  Statewide Use: It’s agriculture

39 Water Summary Relatively ……… drinking water worldwide Absolutely enough for humanity, so far SW groundwater (like a miracle) –Not ………..., unintended consequences SW big rivers –Not much ………, engineering ………… Are we immune from having to abandon infrastructure?