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

5

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 km3/yr (0.26 mill-bill gallons/yr)• Oceans: 85% …………, 79% …………….• Fresh water: surface, subsurface, or evap

Water Cycle

8

9

Where do we get our Water?

• ………………– Wells into aquifers

• ………………..– Reservoirs & streamflow

• …………………– Small scale homeowners

• (not for drinking)

10

11

What Is An Aquifer?What Is An Aquifer?

Aquifer - sands with water filling the pore spaces between the grains

bedrockwater 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

14

1995 Annual Groundwater Budget Tucson Active Management Area1995 Annual Groundwater Budget Tucson Active Management AreaInflow +………… ac-ftNatural and Incidental Recharge,Groundwater Inflow

Outflow - …………..ac-ftMunicipal, Agricultural and IndustrialPumpage, Groundwater Outflow

Balance (OVERDRAFT) -…………… ac-ft

• Acre-foot: water 1 foot deep covering 1 acre (43,560 ft2) = 325,851 gal.

• SRC Pool: ~2 acre-feet

15

Consequences Of OverdraftConsequences Of Overdraft

16

Consequences Of OverdraftConsequences 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

21

22

How Much Water Left Under Tucson?

• So, ~………… maf left,

maf80.ft.ac000,000,80

porosity%25deep.ft1000.mi.sq1

acres640.mi.sq500

maf20.ft.ac000,000,20

porosity%25deep.ft250.mi.sq1

acres640.mi.sq500

yearTucson268day365

year1

Tucsonans10

Tucson

.gal200

dayTucsonan

af1

.gal851,325

maf1

af10maf60

6

6

23

Well HydrographPima & Swan

Well HydrographPima & Swan

100

200

300

1950 1960 1970 1980 1990 2000

De

pth

To

Wa

ter

(ft.

)

24

Consequences Of OverdraftConsequences 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 (m3/sec):– Colorado: …….– Columbia: ……..

…….– Miss.: …………….– Amazon:

………………

Surface Water

Source: http://www.rev.net/~aloe/river/

26

Lee’s Ferry flow: 13.5 maf/yrHow many people would that

provide for?

peoplemillion75~

day365

yr1

gal.160

day•pers1

af

gal.325,851

maf1

af10

yr

maf13.5 6

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?

maf157.ppt.ft1.mi.sq1

acres640.mi.sq000,246

28

Colorado River Compact, 1922• AZ: W.S. Norviel (2nd from left)• 4th 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

yr/tonnes000,715~mg10

)tonne(Mg1

l1

saltsmg580

.gal1

l785.3

af1

.gal851,325

maf1

af10

yr

maf1

9

6

)stopnon(min/trucks3

tonne1

truckstonhalf2

min600,525

yr1

yr

tonnes000,715

Where goeth the salts?

36

GroundwaterPumping

• …………………through time

• Used mostly for irrigation

37

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?