Application of Arc Hydro Groundwater and MODFLOW Analyst

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Automated well permitting

• Application of Arc Hydro Groundwater and MODFLOW
  Analyst

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Overview

• Calibrated regional model is imported to ArcGIS
  as a baseline model
• Candidate wells are added to baseline model using
  well package.
• Impact of new well is analyzed using MODFLOW

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Candidate Well Analysis

• Step 1 User applies for a new well (coordinates,
  pumping rate, screen elevations).
• Create a new feature in the Well feature class

New Well (HydroID 1001)
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Candidate Well Analysis

• Step 2 Create new instances in the WEL table.

Custom tool that creates MODFLOW instances based
on the location of the well and the screen
elevations and finds the appropriate MODFLOW cell.
CellID represents MODFLOW i, j, k values
SourceID is the HydroID of the well feature
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Candidate Well Analysis

• Step 3 Export the new well data to the MODFLOW
  text file

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Candidate Well Analysis

• Step 4 Run MODFLOW simulation with candidate
  well
• Use OBS process to compute new flows at rivers,
  drains, etc.
• Export drawdown file as part of solution.

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Candidate Well Analysis

• Step 5 Read solution and compare to base
  simulation

• Generate appropriate reports to guide well
  approval/rejection.
• There can be a number of different criteria for
  comparison
• Changes in flows (observed vs. simulated
  equivalents) at key features.
• Drawdown at key locations.
• Drawdown maps
• Capture zones (using MODPATH).

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Case Study 1 - SRWMD
Permitting criteria based on impact to streams,
springs, etc.
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Well Analysis Workflow
Create new well ? update well table ? export well
package file ? run MODFLOW ? import solution ?
build map layers
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Case Study 1 - SRWMD
Location of candidate well
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Drawdown resulting from well
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Changes in flows to sources/sinks
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Case Study 2 Virginia DEQ

• Virginia Coastal Plain Model (VCPM)
• 10-layer MODFLOW model used to analyze impacts of
  candidate wells
• Criteria based on state law
• Potentiometric surface cannot fall below a
  critical surface (80 drawdown)
• Area of Impact defined by drawdown 1 ft

Heads for layer 8
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Well Permitting Workflow
Create new well ? update well table ? export well
package file ? run MODFLOW ? import solution ?
build drawdown map layer
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Products
Area of Impact Cells
Area of Impact Contour
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GIS Products
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Well permitting workflow demo