Marine Data Literacy 2.0

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Home > 2. Marine GIS > 2.8 Boundaries & Coast

2.8 Adding Administrative Boundaries and Coastline to a Project Map in Saga

  • Exercise Title:  Adding Administrative Boundaries and Coastline to a Project Map in Saga

  • Abstract:  An excellent source for high-resolution, up-to-date country (i.e. international) and and internal boundaries, is mined for useful shapefiles.  The coastline included with these data is now believed to be, arguably, the very highest resolution global resource yet published (nominal resolution 30 arc-seconds).

  • Preliminary Reading (in OceanTeacher, unless otherwise indicated):

  • Required Software:

  • Other Resources: 

  • Author:  Murray Brown

  • Version:  6-2-2014

1.  Run Saga and do not open any project, or save and close existing projects.  We will create a new project for political borders ("adminstrative areas").
2.  When you open the GADM website, this is the main data interface page.  It carefully lists all the output file formats available.  Select LIBERIA (scroll down for it) and SHAPEFILE and click OK.
3.  This example map of Liberia appears.  Click DOWNLOAD.

NOTE:  For some countries, no example map appears.  Just go ahead and download anyway.

4.  Navigate to DATA > BASEMAP > BORDERS and save the file as borders_liberia_gadm_levels_all.zip
5.  Unzip the file in place, and then you'll find:
  • LBR_adm0.shp (plus the auxiliary files with similar name)
  • LBR_adm1.shp (plus the auxiliary files with similar name)
  • LBR_adm2.shp (plus the auxiliary files with similar name)
  • LBR_adm3.shp (plus the auxiliary files with similar name)

This indicates that 4 administrative "levels" have been identified for Liberia, starting with 0, which is the national level.  If you think about it, you'll realize that lines in the polygons of any level can actually serve at multiple levels.  For example, there will be level 3 lines that are also used as pieces of level 2, level 1 and level 0 polygons

6.  Now, we're going to load and display the border polygons in such a way that you can see the hierarchical structure visually.
7.  Use FILE > SHAPES > LOAD SHAPES to open the shape LBR_adm3.

Right-click on this object, and select ADD TO MAP. 

Then in the properties window, make these choices:

  • FILL STYLE = TRANSPARENT
  • OUTLINE COLOR = YELLOW

Then click SETTINGS > APPLY.

8.  Use FILE > SHAPES > LOAD SHAPES to open the shape LBR_adm2.

Repeat the steps above with this level, but color it GREEN.

Then click SETTINGS > APPLY.

 

9.  Use FILE > SHAPES > LOAD SHAPES to open the shape LBR_adm1.

Repeat the steps above with this level, but color it BLUE.

 

10.  Use FILE > SHAPES > LOAD SHAPES to open the shape LBR_adm0.

Repeat the steps above with this layer, but color it BLACK.

Now you can see the hierarchical order of the levels, which clearly define the political areas of Liberia, from the entire nation down to the smallest level.

 

11.  Select FILE > PROJECTS > SAVE PROJECT AS and navigate to the PRODUCTS > SAGA > AUXILIARY folder to save it as map_admin_areas_liberia.
12.  If you select MAPS > TREE at the bottom left, you can see that the layers are listed physically as they are place on the map, i.e. last layer on top.

Remember, you can right-click on any map object in any map and use the MOVE commands to move them up or down.

13.  Select any arbitrary area of the coast with the ZOOM tool.
14.  If you select the ATTRIBUTES tab at the bottom of the properties window, and the ACTION tool in the command line of Saga, you can investigate the tabular properties of the various levels.

Here you see that at the lowest level, the unit has TYPE = CLAN.  Try to identify the higher level unit names.

15.  Download the GADM data for Sierra Leone, Cote d'Ivoire and Guinea, all other countries that appear in the Liberia project map, no matter how small.
16.  Unzip these border files, but only add the level 0 components from each of them to your map.  We don't need all the lesser levels for these neighbor countries.
17.  Here is the combination of all the data: 
  • All levels for Liberia
  • Only level 0 data for the other 3 countries (ignoring the tiny sliver of Ghana).
18.  Give all the map objects understandable names in the properties window, using SETTINGS > APPLY for each one.

Then use FILE > PROJECTS > SAVE PROJECT to save this collection of border data objects.