Today I am going to show you how to take a 6-figure grid reference from a topographic map.
This is a topographic map of the Waimakariri River which is in the Canterbury region of New Zealand.
Topographic maps have a grid of lines drawn on them.
You can see the lines, some horizontal some vertical and each line
has a number corresponding to it.
Grid references are very useful for finding a location on a local scale.
For example we might want to find the coordinates of this building here
just south of the river mouth.
Now coming to a more simple map you can see that the vertical lines are called eastings and
that is because they travel from west to east.
The horizontal lines on the other hand are called northings
and we call them northings because they travel from south to north.
So it goes 25, 26, 27 and so on.
The next important thing to know is that every square gets divided into ten.
And the formula for taking a grid reference
is that you always read the easting first and the northing second.
One formula that I often use for teaching this
is "like walking along a path, climbing up the ladder."
So remember always read your eastings first and northing second.
This is opposite to the way you would read latitude and longitude
Now I have three examples that I'm going to do on the simple map.
I've put in a red dot for A, B and C.
So first let's do a reading for A.
The easting would be 97 and because it's right on the line the next number would be 0.
If the red dot was over here it would be 975.
But because it's right on line it's 970.
Right there be 971, 972
Over here would be 979
and the northing for this would be 280.
So we would therefore read this as 970280
and I will just enlarge that so you can see it.
So that is the grid reference for A.
Now for location B which is right here in the corner.
So I would read your eastings first and it's right there,
so I would say it's about 989. (Repeats saying 989)
and our nothing here, coming up here.
Again its right in the corner so it'll be 319.
And finally we get to location C.
Now I've got it right in the middle of this grid square.
The easting would be 005 because it's right in the middle. (repeats the words 005)
and coming here for the northings, it would be 255.
Now I've come back to the Waimakariri River topographic map and I'm going to show you a worked example on here.
This building here is the Surf Club
I'm going to find a reading for this. So the easting would be 77.
(It) is halfway across so it'd be 5. So I would write 775.
and the, if you look over here
the northing would follow these numbers. Would be 9.
So it would be 969. It's right at the end there so it'd be 969.
So there'd be a good reference of 775969.(sorry)
And finally I will do one more.
Let's say this river mouth here where
the Kaiapoi River is entering into the Waimakariri River.
So we'll go for right on this point here.
Our grid reference would be ... looking at this
Do our eastings first ... 751 I would say ... to get that point there
and our northing would be about nine five. I reckon 8 because I would say that's about eight tenths the way up.
So 751958.
So I hope this helps you to do some six figure grid references.