Create a 5km square fishnet in ArcMap

[Thibaut_78]

Hi,

I have to create a grid that cover my entire study area and where each cell will have a surface equal to 5km square. Not sure what are the values should I setup in the cell size width and height?

This is what I tried:

If 1 degre = 111km, so 1km is 0.009 degre and then a square with a surface of 5km square would be a square of 2.236 x 2.236 km, so converted in degre: 2.236 x 0.009= 0.0201?

When creating that fishnet with 0.0201 of cell height and width, the surface of each cell is a bit less than 5km square...Sure I missed something!

Thanks

[JayantaPoddar]

The value (length) of a degree will differ from one latitude to another.

You could change the coordinate system of the data frame to an appropriate Projected Coordinate System (e.g. UTM, Web Mercator, etc.), and maybe put the height and width (in meters) as 2236.0679775 each, while creating fishnet.

[Thibaut_78]

Thank you very much. It works very well.

But now that I created a grid, I uploaded my GPS tracklines and I want to calculate the number of km in each cell. How to do that?

[JayantaPoddar]

1. Ensure you define a field with unique values for each cell of the Fishnet grid.

2. You could use Intersect (Analysis) between the Fishnet grid and the Tracklines. JOIN_ATTRIBUTES = ALL. Output will be a Polyline feature class with attributes of both the layers.

3. To the above output polyline layer, use Dissolve (Data Management) , keeping the Unique ID field of the Grid as the Dissolve Field parameter.

4. Use Join Field (Data Management).

Input Data: Fishnet_Grid

Input Field: Unique_ID

Join_Table: Tracklines_Dissolved

Join_Field: Unique_ID

Field(s): SHAPE_LENGTH

5. Optionally, you could add a new FLOAT/DOUBLE field in the attribute table of the Grid, and convert the Shape_Length (derived from Tracklines_Dissolved) from Meters to Kilometers using Field Calculator.

[Thibaut_78]

Thanks so much! really appreciated