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
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