Tuesday, 23 September 2014

Municipality summaries practical 1


In this practical you will create summaries of various biodiversity related features for your chosen municipality similar and updated to those found on the BGIS website which were produced from data available in 2009. They are currently being updated you are going to "jump the gun" as it were.

First you will need the South Africa's municipal boundaries. For now we are going to stay with the 2009 boundaries so that you can compare your findings with those on the BGIS website.

Download the zipped 2009 boundaries

On the BGIS website find and download the following zipped shapes of biodiversity related feature

The most up to date protected areas layer - read carefully!
National vegetation types 2006
National vegetation types 2009 - you need to log in
National Fresh Water Priority Area - wetlands
NFEPA - river FEPAs
Forest patches - download the shapefile here

We will used Arcview 3.1 which is installed on the machines in the lab you will have to do the following. I am not going give all click by click steps here you will learn in class.

1. Unzip all the shape files in a working directory which should be near the root and have not spaces e.g. c:/bdc332/
2. Open and look at all the layers in Arcview 3.1
3. Select your municipality using the select tool, find, query builder tool or attribute table.
4. Clip all the biodiversity related features to your now selected municipality. To clip  you will have to see that the geoprocessing extension is enabled. The geoprocessing tool can be found under view. Save the new clipped biodiversity related feature layers into a directory where you can find them again.

4. You can now produce a lists of the following
a. Protected Areas
b. Vegetation types 2006
c. Vegetation types 2009
d. Biomes 2006 - this can be created from the vegetation types
e. Forest types - look at the metadata!

First view the attribute tables for your new shapes - sort these. Notice that there are duplicates which are caused where there is more than one polygon belonging to the same protected area or vegetation type i.e. the feature has more than one piece which are not linked e.g. Table Mountain National Park. This may in some cases not be a problem.

You can reduce the entries in the attribute table to a single entry by using the dissolve geoprocessing tool to produce yet another shape file.  Choose the fields you want to keep carefully and experiment.

Pleae be aware that "a shapefile" is a collection of several even up to 7 files all with the same name but different extentions. You can view the .dbf which is the attribute table file also in excel but you can't save it so you can't break it.

5. Make a new layer of the following from the two remaining clipped biodiversity related features
a. All wetlands with a FEPA status of FEPA from the NFEPA wetlands clipped layer
b. All subquaternary catchments with the FEPA status of  FEPA from the NFEPA river FEPA clipped layer. What other FEPA status can a subquaternary catchment have?

To create these new layers you can use the select tool and save the selected features to a new shape file.

Confused by all the FEPA!
If you are confused join the club it took me a while to get my head around this one! I will try my best to explain this in class but to start please notice the projects name is NFEPA National Freshwater Ecosystem Priorities Areas. A wetland or a section of a river and its adjacent  subquaternary catchment were assigned the status of a Fresh Water Priority Area FEPA if they met certain criteria. Some rivers were not quite good enough to achieve the status of FEPA but still important for certain indigenous fish species in which case their FEPA status is Fish Sanctuary. What others did you find.    

6. You should finish the practical with 7 layers saved as shapefiles
5 from point 4 above the dbf's of which can to created lists of the related biodiversity features
2 from point 5 above which now only contain the wetlands or subquaternary catchemnts with a FEPA status of  FEPA

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