Understanding Groundwater. December 9, 2015

Transcription

1 Understanding Groundwater December 9, 2015

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4 Speakers Gabriele Ludwig, Almond Board (Moderator) Graham Fogg, University of California, Davis

5 Gabriele Ludwig, Almond Board

6 Graham Fogg, University of California, Davis

7 Understanding Groundwater: The Hidden Resource

8 Outline Groundwater fundamentals California groundwater occurrence & general background Climate change and a new epoch of scarcity Overdraft & negative consequences Non-sustainable storage depletion Subsidence Surface water & ecosystem effects Increased energy costs Bad water intrusion from aquitards and from depth Basin salt imbalance Seawater intrusion Sustainable yield Groundwater myths Pumping of fossil water is non-sustainable Groundwater storage depletion always takes a long time to recover Groundwater levels tell us how much groundwater storage is changing Quality of most groundwater is degraded Good quality groundwater today is likely to stay that way Potential myth: climate change will decrease groundwater recharge

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11 California Water System 11

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13 Snow Water Storage Slides: Bryan Weare, Definition: Snow-Water Equivalent (SWE) is a common snowpack measurement. It measure the volume of water contained within the snowpack (as a measure of depth). Figure: Mote (2006) Fig 5a: Observed changes in 1 April Snow-Water Equivalent over the 1960 to 2002 period of record from snow course observations. Paul Ullrich CCWAS: Lecture 03 October 7, 2013

14 Graham E. Fogg,

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16 The CA Water Quantity Problem 8 th largest economy in the world. Produces 50% of nation s fruits & vegetables w/ irrigation. Depends on snow-storage and historically well-timed snow-melt to satisfy demand. This system cannot function properly as the snow pack diminishes due to warming.

17 The Major Stores of Water. Snow Mountain Groundwater Surface Reservoirs Alluvial Valley Groundwater (Especially Central Valley)

18 Available Central Valley Groundwater Storage Volume 10 to ac-ft CA s 4 largest reservoirs = ac-ft (Shasta, Oroville, Trinity, New Melones)

19 Two Bank Accounts When Account A is depleted, uncontrolled withdrawals from Account B occur Surface Water Bank Account A (known balance, inputs and outputs) Unknown Groundwater Bank Account B (unknown balance, inputs and outputs)

20 The Major Stores of Water. Snow Mountain Groundwater Surface Reservoirs Alluvial Valley Groundwater (Especially Central Valley)

21 Groundwater and Surface Water From CA Water Plan 2014

22 UC Water Security and Sustainability Research Initiative

23 We apply three perspectives to every project. INFORMATION INSTITUTIONS Connected water resources science & management INFRASTRUCTURE Current program foci: Headwater Management Groundwater Management Water-Energy Nexus Intelligent Water System 12/14/

24 Integrating water-resources data & information systems Existing data User interfaces Sensor networ ks Well monitorin g Point data, time series Core data Custom data Modeled data Aircraft Landscape data Groundwate r aquifer water balance Satellite Market, demand & energy data QA/QC Spati al data, time series t y x Valueadded Interpolate d & blended spatial data Modeling & prediction Basin-scale water balance Decision support Water decision making Policy & legal data & constraints: water rights, diversions, ecosystems UC Water Security and Sustainability Research Initiative Aug 31, 2015

25 Winter Fallow Irrigation (Dr. Helen Dahlke, UCD)

26 Sutter Bypass, Sutter Co., 1997 flood

27 Climate Change and Groundwater: Higher Flooding Risks BUT Greater Recharge?? Flooding and Groundwater Levels Laura Chun/The Sacramento Bee 1997, 1995 Flood Events Sacramento County, CA 27

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29 Groundwater Occurrence

30 Major Aquifers ( Volcanics Alluvial Valleys Alluvial Valleys, Basin & Range 30

31 San Joaquin Valley Groundwater (from Faunt, 2009) Pre- Development Post- Development 31

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34 Groundwater Unsaturated zone Saturated zone Water table Land surface Surface water Ground water Creviced rock Air Water (not ground water) held by molecular attraction Surrounds surfaces of rock particles Gravel Air Approximate level of the water table All openings below water table full of ground water 34

35 Confined Aquifer Schematic (from Driscoll, 1986) Well Potential energy in confined aquifer Myth: Old (1,000 s of yrs) groundwater is fossil water that is not replenished enough to support pumping. 35

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37 Groundwater Overdraft: Pumping more groundwater than the system can sustain Potential consequences: Non-sustainable storage depletion Subsidence Surface water & ecosystem effects Increased energy costs Bad water intrusion from aquitards and from depth Basin salt imbalance Seawater intrusion

38 Groundwater Overdraft Trends, Central Valley 38

39 Groundwater Overdraft: Pumping more groundwater than the system can sustain Potential consequences: Non-sustainable storage depletion Subsidence Surface water & ecosystem effects Increased energy costs Bad water intrusion from aquitards and from depth Basin salt imbalance Seawater intrusion

40 Mining Ground Water San Joaquin Valley, California Approximate location of maximum subsidence in the United States identified by Joe Poland (pictured) 40

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42 Subsidence Induced Canal Damage From

43 Groundwater Overdraft: Pumping more groundwater than the system can sustain Potential consequences: Non-sustainable storage depletion Subsidence Surface water & ecosystem effects Increased energy costs Bad water intrusion from aquitards and from depth Basin salt imbalance Seawater intrusion

44 From Alley et al. (1999) 44

45 From Faunt (2009) 45

46 Groundwater Overdraft: Pumping more groundwater than the system can sustain Potential consequences: Non-sustainable storage depletion Subsidence Surface water & ecosystem effects Increased energy costs Bad water intrusion from aquitards and from depth Basin salt imbalance Seawater intrusion

47 Potential for Water Quality Degradation from Below is Clear and Present, but Unaddressed

48 Woodland Area Aquifer System Network (Stephen Maples, HYD 273)

49 Groundwater Overdraft: Pumping more groundwater than the system can sustain Potential consequences: Non-sustainable storage depletion Subsidence Surface water & ecosystem effects Increased energy costs Bad water intrusion from aquitards and from depth Basin salt imbalance Seawater intrusion

50 The danger of a hydrologic basin losing its outlet.

51 San Joaquin Valley Groundwater (from Faunt, 2009) Pre- Development Post- Development 51

52 Mono Lake: Closed Basin

53 Groundwater Overdraft: Pumping more groundwater than the system can sustain Potential consequences: Non-sustainable storage depletion Subsidence Surface water & ecosystem effects Increased energy costs Bad water intrusion from aquitards and from depth Basin salt imbalance Seawater intrusion

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55 Groundwater Quality is Degrading in Many Systems, But Most of the Groundwater Quality is Still Good

56 Age Distribution & Sustainability: Groundwater Ages are Highly Mixed!

57 Year Historic Nitrate Trends, TLB: Exceedance Rate Percent of wells above natural background Number of wells tested Percent of wells above half nitrate MCL Percent of wells above nitrate MCL

58 Outline Groundwater fundamentals California groundwater occurrence & general background Climate change and a new epoch of scarcity Overdraft & negative consequences Non-sustainable storage depletion Subsidence Surface water & ecosystem effects Increased energy costs Bad water intrusion from aquitards and from depth Basin salt imbalance Seawater intrusion Sustainable yield Groundwater myths Pumping of fossil water is non-sustainable Groundwater storage depletion always takes a long time to recover Groundwater levels tell us how much groundwater storage is changing Quality of most groundwater is degraded Good quality groundwater today is likely to stay that way Potential myth: climate change will decrease groundwater recharge