Climate Change and Sustainability of g yGroundwater Quantity and Quality

Graham E. FoggDept. of Land, Air and Water Resources

Hydrologic Sciences Graduate Group

Toward Sustainable Groundwater in AgricultureSan Francisco, June 16, 2010

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California

Water System

4http://www.water.ca.gov/maps/allprojects.html

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CA Climate Change Center (2006)

http://www.oehha.ca.gov/multimedia/epic/pdf/ClimateChangeIndicatorsApril2009 df

Graham E. Fogg, 2009

http://www.oehha.ca.gov/multimedia/epic/pdf/ClimateChangeIndicatorsApril2009 df

Graham E. Fogg, 2009http://www.oehha.ca.gov/multimedia/epic/pdf/ClimateChangeIndicatorsApril2009.pdf

Graham E. Fogg, 2009

http://www.oehha.ca.gov/multimedia/epic/pdf/ClimateChangeIndicatorsApril2009 df

Graham E. Fogg, 2009 http://www.oehha.ca.gov/multimedia/epic/pdf/ClimateChangeIndicatorsApril2009 df

Graham E. Fogg, 2009

The CA Water Quantity Problem

7th l t i th ld• 7th largest economy in the world.• Produces 50% of nation’s fruits &

vegetables w/ irrigation.• Depends on snow-storage and p g

historically well-timed snow-melt to satisfy demand.y

• This system cannot function properly as the snow pack diminishes due tothe snow pack diminishes due to warming.

Solutions?Solutions?• Conventional wisdom – conserve &Conventional wisdom conserve &

build more surface storage.• Unconventional wisdom conserve &• Unconventional wisdom – conserve &

subsurface storage of excess winter flowflow.

• Plenty of storage space, but infiltration t ltoo slow.

• Is there a way of accelerating recharge of the coming glut of winter runoff?

Available Central ValleyAvailable Central Valley Storage Volume

• 10 to 50×106 ac-ft (12.3 to 61 7×105 ha m)61.7×105 ha-m)

• CA’s 4 largest reservoirs = g13×106 ac-ft (16×105 ha-m)

(Sh t O ill T i it N(Shasta, Oroville, Trinity, New Melones))

Sutter Bypass, Sutter Co., 1997 flood Case study - Cosumnes River, California

September 2001

Juni 2002

10/35

2006

Graham E. Fogg, 2002

River model – simulated water table

45 R1 R2

R3 R5

25

35

amsl

R6 Homogeneous-B

4/13/2001 (observed) channel elevation [m]

15

25

atio

n [m

] a

-5

5elev

a

-150 5 10 15 20 25 30 35 40 45 50 55

vertical exaggeration ~ 500x

river-kmFleckenstein, J.H., Niswonger R.G., & Fogg, G.E., Ground Water,44(6), 2006

14/35

River model – simulated seepage

R = realization

0.550.60

R1

0.400.450.50

3 /s]

R2R3R5R6

0 200.250.300.35

page

[m3

Homogeneous

0.050.100.150.20

See

-0.050.000.05

0 5 10 15 20 25 30 35 40 45 50 55river-km

Fleckenstein, J.H., Niswonger R.G., & Fogg, G.E., Ground Water,44(6), 2006

13/35

Sutter Bypass, Sutter Co., 1997 flood

LeveeNo Floodplain

Levee

Floodplain w/ set-back levees

Summary• The new timing of runoff will require different

mechanisms for storing water.g• Regional hydrofacies approach leads to

insights regarding mechanisms of d d f i igroundwater and surface water interaction.

• Subsurface storage of a sufficient magnitude not feasible unlessnot feasible unless…– we know the “sweet spots” and can implement

local enhancements to infiltration & vadose zone ?management?

– and we allow floodplains to function like floodplains?p

• What about water quality?

Age Distribution &Age Distribution & Sustainability

Groundwater quality sustainability is one of the major scientific and societal issues of our j

time...• Most fresh groundwater resources are 102 - 103 yr old, yet

most anthropogenic contaminants (e.g., salinity) <50-60 yr old.

• Groundwater ages (even from short screens) are g ( )generally highly mixed.– Molecular ages typically range greatly (e.g., 101 - 103

yr) within a single sampleyr) within a single sample.– In other words, in many systems there is significant

potential for water quality to get much worse over the i d d t t i d dicoming decades to centuries, depending on

contaminant sources.• In addition to models, limited monitoring data are

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consistent with the “things could get a lot worse” argument. 28

M it iMonitoring DataData

Long-Term Measurements?

From Dubrovsky, et al. (1998) - USGS NAWQA

City of Davis, CA Well Data, <135 m Depth

Major confining layers present

Davis

Arava Valley, Southern Israely,

Water table aquiferq

Confined aquifer

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2004

....... paper on groundwater sustainability argues that d li i d t lit d t lt t i t i

2004

declining groundwater quality due to saltwater intrusion and irrigation with wastewater is seriously threatening the future of water resources in Israel as well as the economic and social fabric that depend on those resources.

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But!There Are Potential Water QualityThere Are Potential Water Quality Benefits to Winter Recharge in CVFundamental: if most of the recharge is• Fundamental: if most of the recharge is relatively clean, groundwater quality is much more sustainablemore sustainable.

• Currently, most of the recharge in the CV is from irrigation.from irrigation.

• Assuming the excess winter flows can be managed to maintain good quality….g g q y

• Managed, ‘clean’ recharge could actually help groundwater quality sustainability in the CV.g y y

Sutter Bypass, Sutter Co., 1997 flood

Closing ThoughtsTh ti h t t t thi ki f hi h i i• The time has come to start thinking of a higher vision of how the CV aquifer system could be managed and used.

• Currently we are most limited by lack of knowledge of the anatomy and by lack of will to think outside the ‘box’ concerning groundwaterbox concerning groundwater.

• There are technical and research problems to greatly augmenting SSR:g g– Exploiting the aquifer architecture– Dealing with the problem of clogging due to

suspended sediment in winter flows– Effects on water quality, including salinity

• None of these are insurmountable• None of these are insurmountable