GEOS 3310 Lecture Notes: WaterResources

Dr. T. Brikowski

Spring 2012

file:waterSupply.tex,v (v. 1.37), printed April 5, 2012

Hydrologic Cycle

1

IntroductionThe hydrologic cycle is defined by the movement of H2O

between its major reserviors (large accumulations, e.g. oceans;

Fig. 1.)

• two almost-separate cycles, one over ocean, other over land

• much natural recycling of water takes place (Fig. 2)

• some surprises, e.g. Antarctica receives the least precipitation

of any continent, yet has abundant H2O [as ice, Table 13.1,

Keller, 2011]

• water residence time can be important, e.g. water may be

stored in ice and snow for 10’s of thousands of years [as ice,

Table 13.1, Keller, 2011]2

Hydrologic Cycle

Figure 1: The hydrologic cycle, from [Fig. 13.3, Keller, 2011].

3

Fluxes in the Hydrologic Cycle

Figure 2: Fluxes in the hydrologic cycle, from [Fig. 13.4,

Keller, 2011].

4

Declining Resources

Water stress (limited or inadequate safe water supply) is

becoming more prevalent, as population grows and climate

warms:

• world wide water stress (pg. 61) increasing rapidly, causing

much suffering and potential war. See also decadal summary

• dire warnings of persistent drought and loss of water resources

in the future

– California Central Valley, aquifers losing water at ≈1.2 inyr

[Famiglietti et al., 2011, see graphics at NYTimes ,]

– Lake Mead, NV

∗ persistent drought since 2000 has reduced water levels5

∗ see animation of lake shrinkage

∗ projections indicate 50% chance Lake Mead will “dry

up” by 2021 unless usage changes drastically

∗ U.S. Bureau of Reclamation indicates potential for basin-

wide water emergency as early as Summer 2011

– Great Plains

∗ Texas Panhandle - aquifer depletion coming soon! (Fig.

3)

∗ failed reservoirs, including Optima Lake in Oklahoma,

Lake Meredith near Amarillo

– Australia : Extended drought reduces rice crop by 98%,

leading to worldwide food shortages

– India, agriculture in west depends on overpumping of

aquifers (Fig. 4), see also MSNBC “Thirsty Planet” videos

(slide )6

• Climate Change: more evaporation everywhere, but

continental precipitation moves toward coasts and poles

7

High Plains Aquifer Lifetime

MidlandOdessa

Lubbock

Amarillo40

27

20

New

Mex

ico

Texa

s

Ok l ahoma

Texas

P r a i r i e D o g T o w n F o r k R e d R i v e r

C a n a d i a n R i v e r

Co l o r a d o R i v e r

B r a z o s R i v e r

GLASSCOCKMIDLANDECTOR

HOWARDMARTINANDREWS

BORDENDAWSONGAINES

GARZALYNNTERRYYOAKUM

DICKENSCROSBYLUBBOCKHOCKLEYCOCHRAN

MOTLEYFLOYDHALELAMBBAILEY

BRISCOESWISHERCASTROPARMER

DONLEYARMSTRONGRANDALLDEAFSMITH

WHEELERGRAYCARSONPOTTEROLDHAM

HEMPHILLROBERTSHUTCHINSONMOOREHARTLEY

LIPSCOMBOCHILTREEHANSFORDSHERMANDALLAM

Estimated UsableAquifer Lifetime

Estimated UsableAquifer Lifetime

0 10 20 30 40 505

Miles

Perennial StreamInterstateMajor RoadCounty BoundaryOgallala Aquifer ExtentOutside of TexasLand Surface Over the Ogallala Aquifer in West Texas

Less than 15 years16 to 30 years31 to 50 years51 to 75 years76 to 100 yearsGreater than 100 years

Water Table Rising

No Saturated Thickness Changebetween 1990 and 2004

Already Below 30 feet

Figure 3: Projections for usable lifetime of Ogallalla Aquifer,

Texas Panhandle. From TTU .

8

India Groundwater Declines

Figure 4: India annual pumping as fraction of recharge. From

NASA .

9

California Snowpack Reduction

Figure 5: Projected climate-change-related changes to California

snowpack. From Climate Change and Water Resources Factsheet . Lake

Lavon can hold 275,000 acre-ft of water.

10

Rainfall-Runoff

11

Watersheds

A watershed (drainage basin) is “an area of ground in which

any drop of water falling within it will leave via the same stream

or river” [see Fig. 13.6 Keller, 2008]

• useful designation for managing water resources by allowing

water balance over small parts of the earth, e.g. the

Metroplex

• boundaries are typically topographic divides or ridgelines

• inherently defined by runoff, which is the portion of

precipitation that moves horizontally on the ground surface

• runoff can take a variety of paths to streams in humid [see12

Fig. 10.5a Keller, 2000] and arid climates [see Fig. 10.5b

Keller, 2000]

13

Controls on Runoff

A variety of factors control runoff:

• geologic factors: primarily surface permeability (e.g. bare

rock sheds 100% of precipitation as runoff, just as pavement

does)

• physiographic factors

– extremely elongate basins are often extremely “flashy”,

flooding quickly with high discharge (e.g. The Narrows

of Zion National Park). Conversely wide basins are often

slow to produce floods

– slope generally determines the amount of runoff and time

of development of flood peaks14

• climate: worst flooding and erosion/sediment transport is

usually associated with infrequent high-magnitude storms

(e.g. desert areas)

• biological factors: density and type of vegetation. Generally

the thicker and taller, the longer it takes a flood to develop

after precipitation event (see also Soils and Environ notes)

15

Sediment Yield

In addition to water, streams carry sediment:

• the volume or mass of sediment passing a point per unit time

is the sediment yield

• in general, larger basins have larger “water yield” (discharge),

but smaller sediment yield, because of increased deposition

in their lower reaches (see typical stream profile )

16

Groundwater

17

Definitions

• groundwater is that water found below ground

• it is the major source of water for most of the Western U.S.,

30% of total use in the U.S. [see Fig. 13.21, Keller, 2011].

• distributed in three major zones underground: saturatedzone, vadose or unsaturated zone (separated by the watertable) and capillary fringe [see Fig. 10.6, Keller, 2000]

• movement of water in the saturated zone is controlled by the

distribution of more permeable aquifers and less permeable

aquitards [see Fig. 13.10, Keller, 2011]18

• aquifers may have the water table within them, in which case

they are termed unconfined. If the water table lies above

the aquifer top it is termed confined. [see Fig. 13.10, Keller,

2011]

• confined aquifers are naturally protected from direct

contamination, and may exhibit other beneficial features

like artesian conditions [see Fig. 13.11a, and Fig. 13.11b

Keller, 2011]

• many areas in the Western U.S. began with artesian wells

(Fig. 6), e.g. Waco, the “Geyser City”

• sometimes a localized or temporary saturated zone develops

above the normal water table. This is referred to as perchedconditions [see Fig. 13.10, Keller, 2011]

19

• groundwater is replenished by recharge, which is the

percolation of precipitation downward into an unconfined

aquifer

• groundwater is reduced by groundwater discharge, which is

often into surface water bodies or springs

• groundwater can be removed by pumping, which generates a

cone of depression in the water table (or “artesian pressure

surface”) [see Fig. 13.13, Keller, 2011]

20

Artesian Well, Las Vegas 1912

Figure 6: Artesian well in Las Vegas, NV, 1912. Continued water

extraction lowered water table and well ceased flowing by 1930. After USGS

Circular 1182 .

21

Groundwater Movement

Groundwater movement is controlled by two main variables:

• hydraulic gradient, which is essentially the slope of the water

table (water flow is driven by gravity, so the greater the slope,

the greater the flow rate)

• hydraulic conductivity, the ability of rock to transmit water.

In general the same idea as permeability. Both depend on

the number and size of rock pores (porosity), and especially

how well-connected those pores are to each other

22

Groundwater-Surface Water Interaction

Groundwater extensively interacts with surface water

(streams, lakes, etc.):

• streams may be characterized as gaining (“effluent”), and

flow all year (like Cottonwood Creek on campus). Aquifers

supply water to these streams [see Fig. 13.10, Keller, 2011]

• other streams may be losing (“influent”) water to aquifers

23

Water Supply

24

Water Budget

In determining sustainable use of water resources, a waterbudget is a crucial tool:

• the water budget for the U.S. illustrates the general

distribution of water fluxes, and confirms the predominance

of surface water flow in the eastern U.S. [see Fig. 10.12,

Keller, 2000]

• Ogallala (High Plains) Aquifer

– this is the main water supply for much of the mid-west

[see Fig. 13.14a, Keller, 2011]

– production in excess of recharge results in groundwateroverdraft, resulting in severe drop in water table. These

25

have been as high as 30 m in the panhandle of Texas [see

Fig. 14.14b, Keller, 2011] and good summary in USGS

Factsheet

• often drought, when precipitation is greatly reduced, will lead

to temporary overdraft situations

26

Desalination

A feasible alternative when mildly saline waters are avaiable:

• becoming increasingly affordable (see cost evolution

summary )

– until recently a boiling (“flash”) process was used,

consuming much electricity

– since 1990 “membrane technologies” (i.e. reverse osmosis)

have become increasingly affordable

– still, “desal” is most viable in areas with abundant energy

and severe water shortages, e.g. the Middle East , where

75% of the world’s desalination is done

• relatively few such plants operate in the U.S.:27

– mostly in Florida, e.g. Tampa Bay, FL , where traditional

freshwater sources are at their limit

– El Paso, TX using brackish groundwaters. Currently the

world’s largest inland desal plant

• really a last resort in the U.S., see “ Desalination,

With a Grain of Salt A California Perspective ’

http://www.pacinst.org/reports/desalination/

• also recent NAS history & summary

28

Optima Lake, OK

Figure 7: Optima Reservoir, OK, never more than 5% full.

Groundwater mining dried up inflowing streams. See also

USACOE map .29

Groundwater Mining and Reservoirs

Figure 8: Optima Reservoir, OK inflow and groundwater levels.

After Wahl and Tortorelli [1996]. See also Kansas streamflow

changes .30

Edwards Aquifer, TX

Figure 9: The Edwards Aquifer of Texas and associated

hydrologic boundaries and management zones [Fig. 13.A,

Keller, 2011]. See Edwards Aquifer website for general info.31

Edwards Cross-Section

Figure 10: Cross-section across the Edwards Aquifer of Texas.

After San Antonio Water System .

32

Water Sources: U.S.

• average water usage in U.S. is about 30% groundwater (Fig.

11)

• U.S. water usage trends:

– Consumptive water use up steadily

– ratio of groundwater to surface water also generally up,

partly due to climate (recent droughts led to increased

groundwater extraction)

– since about 1980 water use down slightly, but

ground/surface water ratio increasing (Fig. 11)

• Current water supply status: good websites for drought

status include:33

– U.S.: merged drought indicators

– U.S. Real Time Streamflow website (USGS)

34

Total Water Usage in the U.S., 1950-2005

Figure 11: Total water usage by source in the U.S., 1950-2005.

Groundwater use is steadily increasing, total and surface water

use has leveled off [Hutson et al., 2004] (really Kenny 2009).

35

Colorado River Hydrologic Basin

Figure 12: Colorado River Basin and legal-hydrologic features, after

Barnett and Pierce [Fig. 1, 2008]. See also Owen-Joyce and Raymond

[1996] and Keller [Fig. 13.C, 2011].36

Colorado River Profile

Figure 13: Topographic profile of Colorado River, showing

river gradient and major impoundments. After Keller [p. 281,

1996].

37

Colorado River Water Allocation

Figure 14: Colorado River Basin Compact allocation and

average discharge. After Keller [p. 282, 1996].

38

City Water Usage, Texas, 2006

RIC

HA

RD

SO

N

La

s V

eg

as,

NV

PL

AN

O

MID

LA

ND

AM

AR

ILL

O

WA

CO

DA

LL

AS

FO

RT

WO

RT

H

AU

ST

IN

Tuc

son,

AZ

SA

N A

NT

ON

IO

EL

PA

SO

HO

US

TO

N

100

120

140

160

180

200

220

240

260

280

Per-Capita Water Use 2006

Ga

llons

/Ca

pit

a/D

ay

(GP

CD

)

Figure 15: 2006 Estimated water usage for Texas cities with population

greater than 95,000. Richardson has the greatest usage, nearly double that

of San Antonio, and higher than Las Vegas. Data from TWDB .

39

U.S. Drought Status

Figure 16: Blended drought monitor for U.S. “A” is agricultural

(plant-health) drought, “H” is hydrologic (water supply)

drought. After National Drought Mitigation Center .

40

Dallas Water Supply

41

Dallas Reservoir System

Figure 17: Dallas water reservoir system showing major existing

sources of Dallas drinking water. After Dallas City Engineer .

See TWDB for current levels.42

Projected Water Shortfall

Figure 18: Projected Dallas Metroplex water shortfall given current supply

sources. Note per-capita use projected to increase, and population projected

to be 9.5 million by 2050. After Region C Water Plan .43

Metroplex Planned Reservoirs

Figure 19: Metroplex planned (ovals) and existing reservoirs (gray).

Note pumping costs from eastern reservoirs high, water at Marvin Nichols

would cost about $50/ac-ft, and $250/ac-ft upon delivery at Dallas. Land

acquisition for Fastrell failed in 2009-10. After Dallas Water Plan .44

Conservation Alternative

Figure 20: Conservation requirements to meet projected shortfall. With

22% reduction in Metroplex per-capita water use, no new reservoirs would

be needed. San Antonio reduced its demand by 30% in the last decade.

After Sierra Club .45

Managing Water Supply

46

Management Options

• conservation: target the largest uses

– Encourge efficient irrigation

∗ agriculture utilzes 70% of water resources nationwide

∗ residential use: 60% for outdoor irrigation (Fig. 21)

– Richardson has a 5-tiered pricing scheme , where water

gets more expensive as more is used per site

– that encourages conservation, except in some extreme

cases (Fig. 22)

• protect recharge areas (Fig. 23)

• water importation from other basins (e.g. Oklahoma for

NTX)

47

Residential Water Use Categories

Figure 21: Residential water use categories, outdoor irrigation is largest,

followed by toilet. After NAS .

48

Wealthy Immune to Incentives?

Figure 22: Extreme water use at Crowe residence, Highland Park After

Dallas Morning News .

49

Recharge Zone Protection

Figure 23: Recharge zone protection in Austin, TX. After Duke

University .

50

Other Resources

51

Useful Links

This is intended to be an ever-evolving list of useful links on

the general topic of this note set.

• NBC “Thirsty Planet” series, e.g. American West

• USGS study of groundwater use in Las Vegas, NV . Good

example of the general issues of groundwater mining.

• California state summary of projected climate and water

supply changes

• historical summary of scientific articles about climate change

and water supplies in the U.S. (emphasizing Colorado River

Basin)52

• concerns in New York that natural gas drilling will pollute

surface watershed for NYC

• BBC graphics slideshow (Apr. 2010) on impending water

stress

• NOAA Winter 2011 outlook indicates strong La Nina effects

again

• looming water shortages may lower rating of municipal

bonds

• good but brief summary of the issues worldwide, by U.S.

National Academies

• NTMWD wetland does final polish of reused water, which53

is then pumped back to Lake Lavon for storage

54

Bibliography

55

Tim P. Barnett and David W. Pierce. When will Lake Mead go dry? Water Resour. Res., 44(W03201), 29 March 2008. doi: 10.1029/2007WR006704. URL http://www.agu.org/journals/pip/wr/2007WR006704-pip.pdf.

J. S. Famiglietti, M. Lo, S. L. Ho, J. Bethune, K. J. Anderson, T. H. Syed, S. C. Swenson,C. R. de Linage, and M. Rodell. Satellites measure recent rates of groundwater depletion inCalifornia’s Central Valley. Geophys. Res. Lett., 38(3):L03403, Feb 2011. ISSN 0094-8276.doi: 10.1029/2010GL046442. URL http://dx.doi.org/10.1029/2010GL046442.

S. S. Hutson, N. L. Barber, J. F. Kenny, K. S. Linsey, D. S. Lumia, and M. A. Maupin. Estimateduse of water in the united states in 2000. Circular 1268, U. S. Geol. Survey, Reston, VA,May 2004. URL http://water.usgs.gov/pubs/circ/2004/circ1268/.

E. A. Keller. Environmental Geology. Prentice Hall, Upper Saddle River, NJ, 1996. 7th Ed.,ISBN 0-02-363281-X.

E. A. Keller. Environmental Geology. Prentice Hall, Upper Saddle River, NJ, 8th edition, 2000.ISBN 0-13-022466-9.

E. A. Keller. Introduction to Environmental Geology. Prentice Hall, 4th edition, 2008.ISBN 9780132251501. URL http://www.pearsonhighered.com/educator/academic/product/0,3110,0132251507,00.html.

E. A. Keller. Introduction to Environmental Geology. Prentice Hall, 5th edition, 2011.ISBN 9780321727510. URL http://www.pearsonhighered.com/educator/product/Introduction-to-Environmental-Geology-5E/9780321727510.page.

S. J. Owen-Joyce and L. H. Raymond. An accounting system for water and consumptive usealong the colorado river, hoover dam to mexico. Water-supply paper, U.S. Geol. Survey,Washington, D.C., 1996.

K. L. Wahl and R. L. Tortorelli. Changes in flow in the Beaver-North Canadian River BasinUpstream from Canton Lake, Western Oklahoma. Water Resour. Investig. 96-4304, U. S.Geol. Survey, Reston, VA, 1996.

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