Climate Changgye and Sustainability of Groundwater ...ag-groundwater.org/files/56579.pdf · Graham...
Transcript of Climate Changgye and Sustainability of Groundwater ...ag-groundwater.org/files/56579.pdf · Graham...
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
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amsl
R6 Homogeneous-B
4/13/2001 (observed) channel elevation [m]
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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
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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