Jennifer Garcia Reyes: Comprehensive Guide to Groundwater Flow Net Construction

The primary objective of the material provided by Jennifer Garcia Reyes is to demonstrate the methodology for constructing a groundwater flow net using head elevation data from monitoring wells.
The process involves horizontal and vertical spatial analysis to determine the direction and intensity of groundwater movement based on hydraulic head measurements.
The documents provided are designated as Page 4 of 5 and Page 5 of 5, with a revision date of 12/2018.

Flow nets represent lines of equal hydraulic head (equipotential lines) and the pathways of water movement (flow lines).
Equipotential Lines: These are the primary focus of the graphical exercise. They represent contours where the total hydraulic head is constant.
Linear Interpolation: To draw these contours between discrete data points (wells), linear interpolation is used. This assumes a constant gradient between any two points of measurement.
Calculation Principle: The location of a specific head value $H_{target}$ between two points $H_{1}$ and $H_{2}$ is determined by the ratio of their differences in elevation relative to the physical distance between the points.

Figure 1 provides a practical demonstration of finding contour points between four established monitoring wells with the following head elevations:
- Well A: $64\,\text{ft}$
- Well B: $81\,\text{ft}$
- Well C: $73\,\text{ft}$
- Well D: $63\,\text{ft}$
Target Contour Intervals: The exercise aims to plot contours for every $5\,\text{ft}$ increment, specifically the $65\,\text{ft}$ , $70\,\text{ft}$ , $75\,\text{ft}$ , and $80\,\text{ft}$ levels.
Interpolation between Well B ( $81\,\text{ft}$ ) and Well A ( $64\,\text{ft}$ ):
- Total head difference: $81\,\text{ft} - 64\,\text{ft} = 17\,\text{ft}$ .
- The following contours pass between these points:
  - $80\,\text{ft}$
  - $75\,\text{ft}$
  - $70\,\text{ft}$
  - $65\,\text{ft}$
Interpolation between Well B ( $81\,\text{ft}$ ) and Well C ( $73\,\text{ft}$ ):
- Total head difference: $81\,\text{ft} - 73\,\text{ft} = 8\,\text{ft}$ .
- The following contours pass between these points:
  - $80\,\text{ft}$
  - $75\,\text{ft}$
Interpolation between Well D ( $63\,\text{ft}$ ) and Well C ( $73\,\text{ft}$ ):
- Total head difference: $73\,\text{ft} - 63\,\text{ft} = 10\,\text{ft}$ .
- The following contours pass between these points:
  - $65\,\text{ft}$
  - $70\,\text{ft}$
Interpolation between Well D ( $63\,\text{ft}$ ) and Well A ( $64\,\text{ft}$ ):
- Total head difference: $64\,\text{ft} - 63\,\text{ft} = 1\,\text{ft}$ .
- No whole $5\,\text{ft}$ interval contours cross this line.

Figure 2 applies the flow net principles to a larger field site containing 14 monitoring wells (labeled B-1 through B-14) and two distinct surface water features: Arsenic Springs and Clearwater Pond.
Monitoring Well Elevation Data (Head Measurements):
- B-1: $172$
- B-2: $178$
- B-3: $162$
- B-4: $168$
- B-5: $166$
- B-6: $181$
- B-7: No value explicitly labeled in the provided view.
- B-8: No value explicitly labeled in the provided view.
- B-9: $176$
- B-10: $177$
- B-11: $171$
- B-12: $160$
- B-14: $173$
- Another labeled point near the bottom of the map shows an elevation of $168$ (attributed to B-13).
Geographic Context:
- Arsenic Springs: Located in the northwestern portion of the map, adjacent to well B-6 ( $181$ ) and B-2 ( $178$ ).
- Clearwater Pond: Located centrally, surrounded by wells B-14 ( $173$ ), B-10 ( $177$ ), B-1 ( $172$ ), and B-4 ( $168$ ).
- Orientation: A North arrow (N) is provided to orient the site layout.

Step 1: Data Plotting: Plot all recorded hydraulic head values from the monitoring wells on the site map.
Step 2: Selecting Interpolation Pairs: Identify adjacent wells between which contours must be drawn. Choosing pairs based on proximity is essential for accuracy.
Step 3: Calculating Fractional Distances: Use the elevation difference to determine where the target contour (e.g., $170$ , $175$ , $180$ ) should lie along the line connecting two wells.
- If well $X$ is $172$ and well $Y$ is $168$ , the $170$ contour will be exactly at the midpoint of the line segment connecting them.
Step 4: Connecting the Points: Connect the interpolated points of equal value with smooth, curved lines (equipotential lines). These lines should never cross each other.
Step 5: Establishing Flow Direction: While not explicitly shown in Figure 2, the next logical step in a flow net is to draw flow lines perpendicular to these equipotential lines, moving from high head to low head (e.g., from Arsenic Springs toward the southern portion of the map).