AUTOMATED WELL PERMITTING Application for Arc Hydro Groundwater and MODFLOW Analyst

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 (changes in streamflows, drawdown, etc.) is analyzed using the MODFLOW OBS process, and standard model outputs  Wells can be accepted or rejected and database is updated automatically

 Prepare calibrated model  Establish Flow Observations  Import calibrated model into the ArcGIS  Read solution files and set a model “baseline” to which future runs will be compared Model Preparation The MODFLOW OBS process is used to compare baseline flow with simulated flows. Drain feature Observation name Observed value Simulated value Drain_Time Drain_Time Drain_Time Drain_Time4130 Drain_Time Output heads are copied to starting heads to facilitate drawdown calculations

 Step 1: User applies for a new well (coordinates, pumping rate, screen elevations).  Create a new feature in the Well feature class Candidate Well Analysis New Well (HydroID = 1001)

Candidate Well Analysis  Step 2: Create new instances in the WEL table. CellID represents MODFLOW i, j, k values SourceID is the HydroID of the well feature Custom tool that creates MODFLOW instances based on the location of the well and the screen elevations and finds the appropriate MODFLOW cell.

Candidate Well Analysis  Step 3: Export the new well data to the MODFLOW text file

Candidate Well Analysis  Step 4: Run MODFLOW simulation with candidate well  Use OBS process to compute new flows and rivers, drains, etc.  Export drawdown file as part of solution.

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: o Changes in flows (observed vs. simulated equivalents) at key features. o Drawdown at key locations. o Drawdown maps o Capture zones (using MODPATH).

Case Study #1 - SRWMD Permitting criteria based on impact to streams, springs, etc.

Well Analysis Workflow Create new well  update well table  export well package file  run MODFLOW  import solution  build map layers

Case Study #1 - SRWMD Location of candidate well

Drawdown resulting from well

Changes in flows to sources/sinks

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

Well Permitting Workflow Create new well  update well table  export well package file  run MODFLOW  import solution  build drawdown map layer

AUTOMATED WELL PERMITTING DEMO Arc Hydro Groundwater

Products Area of Impact CellsArea of Impact Contour

GIS Products

For more information Norm Jones (AHGW Wiki page) (Info on tools)