Hi everyone! In this tutorial, we're gonna
identify the hospitals in Ohio that are within particular distance of active
solid waste sites in this state. This is an example of spatial analysis in
environmental health. From lab 5 folder, load the whole dataset in
lab 5 folder. Connect to lab 5--> GIS lab -->lab 5: here we have three
shapefiles we have administrative boundaries of Ohio at the county level
we obtained the data from the TIGER/ Line website. We also have the location
of hospitals in Ohio which has been obtained from homeland infrastructure
foundation level data (HIFLD). These are the location of hospitals in Ohio
and also we have solid waste sites in Ohio which obtained from the same
organization so Homeland infrastructure foundation level data. Let's add this
data into ArcMap. In the first step, I think is better to change the color of
the symbol maybe to "red" the solid waste sites to red. We have to
create multiple ring buffer around the solid waste sites and buffers are
regions or areas around particular features. In this case, a buffer is an
area around solid waste sites. Once you create buffer around these
points (these red points), it will generate some circles around this point.
We're gonna make buffers at multiple distances at three distances: 1 mile,
1.5 miles and 2 miles around the solid waste sites in Ohio. For this
purpose, let's open up your Arctoolbox and then expand "Analysis tools"-->
proximity and here you can create "buffer" or "multiple ring buffer". Buffer means
you can create only a single buffer a single circle around these red points
around the solid waste points or multiple ring buffer it creates several circles
at multiple distances with the center of the solid waste sites. so we're gonna
make buffer at 1 mile,1.5 and 2 miles around solid waste sites: we
select multiple ring buffer. In this window, we have to tell what is the input
feature: your feature class that is going to be buffered is solid waste site
so you can select it from here or you can drag and drop here: solid waste
sites.. This process (this multiple ring
buffer) will generate a new shapefile into the table of contents so we have
to tell ArcMap what is the output feature class: the name of it and where we want to save the data so this default is very difficult to find in
the future (default path). So let's go to the lab5 folder and type "buff_solidwaste" so it's a buffer around the solid waste right so click
Save.. Here we have to specify what is the distance around the solid
waste so we're gonna make a buffer with distance of the 1
miles and then you need to hit this black plus sign okay so it will be added
here one and 1.5 miles and 2 miles so then we have to tell
the unit of the buffer it can be centimeters, feet, inches, kilometers, miles.
We're gonna make 1, 1.5 and 2 miles right? lets select miles.
Again, this process generates a new shapefile in the table of contents and
also it generates a field with the name of "distance" so you can change
the name of it for example if you want you can change this to Distance.
The last option is "Dissolve option" "Dissolve option" means when the buffers overlap, whether they will be merged into a single buffer or
not. If you select ALL they will be merged if you do not select all so they
will it will generate some single buffer or single features. The features are not
just one feature so if you google dissolve GIS and then click image... this is the
dissolve buffer for GIS. Here you can see we can create buffer around
point feature, line feature or polygon feature if you select "Dissolve Type"
None: after it creates a buffer or region around the points, these
features are different features okay so the colors are different right and also
here you can see the colors are different but when you select Dissolve
type ALL so when they overlap they kind of aggregated and also all of them are
just one feature okay so you can see the color is just one color around it.
We're gonna make only one feature okay all of these buffers are only one
feature on the map so let's select "Dissolve Option" ALL and then hit okay.
You need to wait for a couple of minutes because this is a huge process okay so
now we can see the process has been successfully done and we don't need ArcToolbox anymore so let's close it and also close this one. In the table of
contents, you can see a feature class has been added with the name of buffer
solidwaste if you open up the attribute table you can see it only created three features (I
don't know why it's more than three) you can merge these two buffer 1.5 and 1.5 they are the same so maybe for you is different but
it should be only three buffers 1, 1.5 and 2. If this case
happened to you, you have to merge this 1.5 distances. You
have to select these two from here if you select editor
and start editing we're gonna merge these two features okay so from the
editor if you select merge and then click ok
so you can see that these two features have been merged into just one feature.
And also for these two features because this is 2 miles and also these features
also are 2 miles so they are the same so you have to select them and then editor
and then click on merge, ok and after that editor--> stop editing and
save the results so now you have three buffers ok one miles: 1 miles, 1.5 and 2 miles. You can also see that a new field has been added to your feature class with the name of distance, I don't know why it's not uppercase but a new field
has been added to your output feature class with the name of distance right? so
where are the buffers? so these are the buffers but they are very
small because it's only one mile for the whole of the state of
Ohio. To better see the buffers you have to zoom in, zoom in several time
you can see there are some buffers around the solid waste site ok these red
points. let's change the color for the counties to hollow so this is area
around the point around the solid waste: 1 miles around it between 1 and 1.5 and
between 1.5 and 2 miles around the solid waste okay? so that's
the generated buffer. We're gonna select all of the hospitals that are
within the buffers that are within each of these buffers ok? for example we can
see here we have several hospitals so these blue points are hospitals right? we have several
hospitals that are within 1 miles of the solid waste site so we're gonna select
the hospitals for each buffer so first of all you have to open up the attribute
table of the buffer and then select the first record which is one mile
buffer so this highlighted one mile buffer so what we're gonna do
is we're gonna select all of the hospitals that are within this one mile
buffer like these two hospital okay so how we can do that? we
need to use "select by location" function okay? we already have worked with the
"Select by attributes" it was when we wanted to select some attributes based
on some attribute information or description we could use "select by attribute" but here is the relationship between two features their spatial relationships.. so we have to use select by location. And in this
window, we're gonna select what? we're gonna select the hospitals so check the
hospitals and based on which features that are within the buffer right? so we have
to select buffer solid waste and only not for the entire buffer only the
selected buffers" use selected features and here the selection
method should be select all of the hospitals that are completely within
this buffer right? so we have to select are completely contain or completely
within the source layer okay? and then hit apply and okay. So you can see that
it has selected these two hospitals right?
and also if you open up the attribute table you can better see the result for
the hospitals which hospital has been added? eight hospitals are within one
miles of the solid waste site if you click "show only selected records" and then
click on that you can see this hospital this one, this one and so you can see the
results. okay? so what we're gonna do is that we have to say that these hospitals
are at higher risk or higher exposure to the pollution of the solid waste site
right? so first of all we need to export all of these hospitals and then call
them high-risk okay. Data-->Export data only from selected hospitals and then in
lab 5 folder with the name of high-risk and save as type shape file
save and ok. And then click clear selection and
now we can change the color of this for example and symbol of this to hospital so it's searching within the
database that already existed in the ArcMap. For example this one
Hospital but with the color of red to show that this one is a higher
risk of exposure ok ? so click ok so this one these *points are high-risk Hospital.
we can easily identify using the GIS we can easily identify
which hospitals are at higher risk of exposure to the solid waste sites so the
next one you have to repeat this process for the 1.5 miles buffer. First you have to select the one and a half mile so these
are one and a half mile between these two lines and then selections:
Select by location Select all of the hospitals that are
within the solidwaste buffer --> use selected features that are completely within.. so apply
and ok so you can see for example all of these hospitals that are
within you can see this one are not selected but only between
one and one and a half and miles... after that you have to write down the number of the
hospitals that are selected so how many hospitals are within one and one and a
half miles? it's 17 hospitals out of 290. Then you need to export this
hospitals as medium-risk okay and in shape file and save. Change the
color of this to blue and ...Hospital this one is okay... and the size is very big maybe 13 also
for this one also.. okay clear selection, full extent.
So some hospitals are at very high-risk some hospitals are within one and one
and a half and what's next? we have to repeat this process: select by location-->
hospitals but first of all we have to select the two miles - - so you can see
this is the buffer between one and half and two
okay and then selection--> select by location
and everything is good apply and okay. what happened? you have to always
check that you have done your work properly so you
can see all of the hospitals are within this and see how many hospitals? 25 hospitals are within this buffer and after that
exports and type low_risk OK. You can change the color of these two: first
of all select hospital, the color to green and also size of 13 Clear selection. Now we can
remove the buffer ... You can also remove the solid
waste site and only select the hospitals but here maybe we can use white circles so here we can use white circles and
then click OK so this means that these are are not at the risk of so these are
location of the hospitals that are not at risk of exposure, use 13 (font) so the same size of the other hospitals. Maybe less than that. These are the location of the hospitals in Ohio and if you for example change the color to beige or this one.,. Here you can see... this is a map
that we're looking for... locations of the hospitals and also we have hospitals
that are higher risk; medium risk ; and low risk of the exposure to the solid waste
sites. If you go to the layout view and then full extent Put a title for here and then
so when you export it, it will be better but it's not really clear on this one
maybe we can change the orientation to landscape zoom to layer.. so what I'm gonna do? I'm gonna also add
a location of the solid waste sites as an inset map here okay so insert a new data
frame and in this data frame I'm going to add the counties and also the
solid waste sites so to see that where are the solid waste sites in Ohio. These are so why I can't see solid waste sites
because it's under the counties.. Here are the location of the
solid waste sites so you need to add for example insert title: solid waste site so this will be added to... this is for
this map okay? Let me add a white background for it? Edit Symbol If you go to the mask tab and
then Halo you can add the white background for the solid waste site so
these are the location of solid waste sites and also location of the hospitals.
Again I think it's better to make this map larger okay and then remove the
frame around it maybe it's a better idea if I remove the border around
the frame and so you need to also add the legend for these hospitals okay so
maybe it's better to increase the size of the hospitals ... So these are the location of hospitals so
let's insert legend for this because this one is activated: low-risk, medium-
risk, high-risk hospitals so we don't need this one so low risk
let me change it you can remove the underscore low risk hospital or low
exposure; medium exposure and high risk and other hospitals okay or no risk
hospitals or other hospitals hospitals (no risk) okay now if your insert legend so we can
remove this one and then preview and finish so legend will be distance of the
hospitals to to the solid waste site then you can add all of the necessary
information such as North arrow; scale bar and title for your map
location of the hospitals that are at risk of exposure to the solid waste
sites at different distances maybe you can specify the distance so just some
explanation that low-risk means: the distance from the hospitals to the solid
waste site the nearest solid waste is less than one mile and so you can
just bring some information here or you can add it to the legend of your
map.
