General Groundwater Concepts for GSP Development in Sonoma Valley - - PowerPoint PPT Presentation
General Groundwater Concepts for GSP Development in Sonoma Valley Sonoma Valley Groundwater Sustainability Agency Advisory Committee Meeting May 8, 2018 sonomacountygroundwater.org Presentation Overview 1. Aquifer Properties and Groundwater
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US Geological Survey Circular 1139
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drains from an unconfined aquifer
yields 0.2 cubic feet of water
groundwater levels nearly one foot
Material Porosity Specific Yield Clay 50% 2% Sand 25% 22% Gravel 20% 19%
Modified from Heath, 1983
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Hydraulic Conductivity: Ability of aquifer materials to transmit water Darcy’s Law of Groundwater Flow (Q)
Q = KiA Common methods for estimating Hydraulic Conductivity:
responses in nearby wells)
geologist’s descriptions from well logs)
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Complex Geology:
deposits
Sonoma Valley Groundwater Basin
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U.S. Geological Survey Circular 1139
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Direct recharge to confined aquifers often limited by laterally extensive clay layers
Harter, UC Division of Ag and Natural Resources, Publication 8083
Pumping equal amounts of groundwater from unconfined and confined aquifers will result in larger groundwater-level declines in confined aquifers.
Heath, USGS Water Supply Paper 2220
Groundwater-level = Water Table Groundwater-level = Pressure Head
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Well Hydrograph, Groundwater and the Rural Homeowner, U.S. Geological Survey
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Well Hydrograph, Water Well Database, California Department of Water Resources
10 20 1948 1958 1968 1978 1988 1998 Groundwater Elevation
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Courtesy The Nature Conservancy
“Gaining Stream”
High Groundwater Levels Groundwater Maintains Stream Flow
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“Losing Stream”
Pumping Lowers Groundwater Levels Stream Loses Flow to Groundwater
Courtesy The Nature Conservancy
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“Losing Stream”
Pumping Lowers Groundwater Levels Stream Loses Flow to Groundwater Groundwater Levels Below Stream Channel
Courtesy The Nature Conservancy
sonomacountygroundwater.org Seepage to Groundwater Exceeds Stream Flow
Dry Stream
Seepage to Groundwater Exceeds Stream Flow Dry Stream Channel (Intermittently or Year-round) Dry Stream Channel (Intermittently or Year-round) Pumping Lowers Groundwater Levels Stream Loses Flow to Groundwater
Courtesy The Nature Conservancy
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(Groundwater flows into Stream)
Nathanson
(Stream recharges Groundwater)
Nathanson
May 2010
Paired Gauge Location
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Contaminant Hydrogeology, C.W. Fetter, 1992
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Tidal Marshlands
Formations
Inflow From Adjacent Aquifers
Natural Land Surface Percolation Streambed Percolation
Well Pumping Streambed Discharge Groundwater Evapotranspiration Surface Discharge
Outflow To Other Aquifers
son
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Undeveloped Aquifer System: Natural Recharge = Natural Discharge to surface water, ET, and springs Developed Aquifer System: Sources of water to pumping wells = Some combination of:
gaining to losing streams)
discharge to surface water/ET, and
groundwater that can be pumped without causing an undesirable result.
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Integrated Hydrologic Model
demands
diversions
changes
understand and convey applicability and limitations of the model Example Model Uses
strategies
use
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(1) Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon. (2) Significant and unreasonable reduction of groundwater storage. (3) Significant and unreasonable seawater intrusion. (4) Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies. (5) Significant and unreasonable land subsidence that substantially interferes with surface land uses. (6) Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water.
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