How to Read a 6-Figure Grid Reference from a Topographic Map

Introduction

• Objective: Learn to read a 6-figure grid reference from a topographic map using the Waimakariri River map in Canterbury, New Zealand.
• Topographic Maps: Features a grid of horizontal and vertical lines with corresponding numbers.
• Grid References: Useful for locating positions at a local scale.

Grid Lines

• Eastings: Vertical lines running west to east.
• Northings: Horizontal lines running south to north.
• Numbering: Lines are numbered sequentially (e.g., 25, 26, 27).
• Grid Squares: Each square is divided into ten parts.

Reading Grid References

• Order: Always read the easting first, then the northing (opposite of latitude and longitude reading).

Example Readings

Example A

• Easting: 97 (on the line), third number 0 → 970.
• Northing: 280.
• 6-Figure Reference: 970280.

Example B

• Easting: 989 (nine tenths along the grid square).
• Northing: 319 (nine tenths up the grid square).
• 6-Figure Reference: 989319.

Example C

• Easting: 005 (middle of the grid square).
• Northing: 255 (middle of the grid square).
• 6-Figure Reference: 005255.

Worked Example on Waimakariri River Map

Surf Club Location

• Easting: 77, halfway across → 775.
• Northing: 969 (nine tenths up the grid squares).
• 6-Figure Reference: 775969.

Kaiapoi River Mouth

• Easting: 751 (one tenth along the grid square).
• Northing: 958 (eight tenths up the grid square).
• 6-Figure Reference: 751958.

Conclusion

• Outcome: Understanding how to effectively read a 6-figure grid reference from a topographic map.