Groundwater Overview

Groundwater Overview
Christina Buck, PhD
League of Women Voters- Water Forum
May 21, 2016
BASED ON…
California Groundwater
Overview
Outline
•
Groundwater fundamentals
– California groundwater occurrence & general background
– 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
Case studies
– Coachella Valley
– Yolo County
– Orange Co.
Slide Credit: G. Fogg
Groundwater Occurrence
Slide Credit: G. Fogg
4
Slide Credit: G. Fogg
Major Aquifers (http://nationalatlas.gov/natlas/natlasstart.asp)
Volcanics
Alluvial Valleys
Alluvial Valleys, Basin & Range
Slide Credit: G. Fogg
6
Slide Credit: G. Fogg
7
Butte County
Fractured Rock
Alluvial
8
Slide Credit: G. Fogg
Slide Credit: G. Fogg
Alluvial Fan (near Bozeman, Montana)
http://geology.about.com/library/bl/images/blalluvfan.htm
Slide Credit: G. Fogg
San Joaquin Valley Groundwater (from Faunt, 2009)
PreDevelopment
PostDevelopment
12
Slide Credit: G. Fogg
Groundwater and Surface Water
Slide Credit: G. Fogg
From CA Water Plan 2014
Slide Credit: G. Fogg
Cosumnes Alluvial Aquifer System
Slide Credit: G. Fogg
Woodland Area Aquifer System
Network (Stephen Maples, HYD 273)
Slide Credit: G. Fogg
Slide Credit: G. Fogg
Groundwater
Land
surface
Unsaturated zone
Saturated zone
Water table
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
Slide Credit: G. Fogg
18
Unconfined vs. Confined
Monitoring well
Harter and Rollins 2008: ANR Publication 3497
• Transmissivity (T)
• Storativity (S)- order of magnitude different for confined
vs. unconfined aquifer
19
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
Slide Credit: G. Fogg
Groundwater Overdraft Trends,
Central Valley
Slide Credit: G. Fogg
21
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
Slide Credit: G. Fogg
Mining Ground Water
San Joaquin Valley, California
Approximate location of
maximum subsidence in the
United States identified by
Joe Poland (pictured)
Slide Credit: G. Fogg
23
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
Slide Credit: G. Fogg
25
Slide Credit: G. Fogg
From Alley et al. (1999)
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
Slide Credit: G. Fogg
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
Slide Credit: G. Fogg
Figure TL-26 Spring 2010 Groundwater Elevation Contours for the Tulare Lake
Hydrologic Region
[This figure is for the Central Valley; it will be updated with figure for the Tulare Lake
Hydrologic Region]
The danger of a
hydrologic
basin losing its
outlet….
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
Slide Credit: G. Fogg
Slide Credit: G. Fogg
30
Summary
• Groundwater fundamentals
– California groundwater occurrence & general background
– 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
• Groundwater myths
– Pumping of “fossil water” is non-sustainable
– Groundwater levels tell us how much groundwater storage is changing
https://watershed.ucdavis.edu/education/classes/california-water-policyseminar-series-groundwater-problems-and-prospects
Slide Credit: adapted from G. Fogg