General Groundwater Concepts for GSP Development in the Santa Rosa - - PowerPoint PPT Presentation
General Groundwater Concepts for GSP Development in the Santa Rosa Plain Santa Rosa Plain Groundwater Sustainability Agency Advisory Committee Meeting May 7, 2018 sonomacountygroundwater.org Presentation Overview 1. Aquifer Properties and
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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
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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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Santa Rosa Plain Geology and Primary Hydrogeologic Units
Santa Rosa Plain Groundwater Subbasin
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U.S. Geological Survey Circular 1139
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Harter, UC Division of Ag and Natural Resources, Publication 8083 Heath, USGS Water Supply Paper 2220
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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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1951
east to west and discharging to Laguna de Santa Rosa 1990
pumping through 1980s and 1990s
developed in southern and western areas 2007 – 2015
pumping within southern area due to increased Russian River water use, conservation and recycled water use
depression has predominantly recovered
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Courtesy The Nature Conservancy
” low
High Groundwater Levels Groundwater Maintains Stream Flow
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umping Lowers Groundwater Levels Stream Loses Flow to Groundwater
“Losing Stream”
Courtesy The Nature Conservancy
Pumping Lowers Groundwater Levels Stream Loses Flow to Groundwat
sonomacountygroundwater.org Pumping Lowers Groundwater Levels Stream Loses Flow to Groundwater Groundwater Levels Below Stream Channel
“Losing Stream”
Groundwater Levels Below Stream Channel
Courtesy The Nature Conservancy
Pumping Lowers Groundwater Levels Stream Loses Flow to Groundwater
sonomacountygroundwater.org Pumping Lowers Groundwater Levels Stream Loses Flow to Groundwater Seepage to Groundwater Exceeds Stream Flow Dry Stream Channel (Intermittently or Year-round)
Dry Stream
Seepage to Groundwater Exceeds Stream Flow Dry Stream Channel (Intermittently or Year-round)
Courtesy The Nature Conservancy
Pumping Lowers Groundwater Levels Stream Loses Flow to Groundwater
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Contaminant Hydrogeology, C.W. Fetter, 1992
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Santa Rosa Plain Groundwater Subbasin
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Precipitation and streambed infiltration primary source of recharge Primary discharge: Pumping Evapotranspiration Baseflow Dominantly flows east to west Imbalance in the amount of inflows and
future climate change. Historical areas of groundwater-level decline largely recovered due to replacing some groundwater use with surface water and recycled water supplies and conservation.
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Inflow From Adjacent Aquifers
Natural Land Surface Percolation Streambed Percolation
Outflow To Other Aquifers
Well Pumping Streambed Discharge Groundwater Evapotranspiration Surface Discharge
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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
Natural Recharge ≠ Basin Sustainable Yield
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EXAMPLE MODEL USES
son
Values in Acre Feet Per Year
Surface Percolation 41,000 Subsurface
Aquifer Inflows 7,200
Streambed Percolation 32,400
Well Pumping 35,600 Streambed Discharge 25,800 Groundwater Evapotranspiration 8,500 Surface Leakage 6,100 Subsurface
Aquifer Outflows 7,900
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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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