Creating a Buffer Analysis in QGIS - Revision history

Smitch: /* Methodology */ Examples of typos which could be cleaned out of this tutorial in revisions.

2022-01-05T19:23:14Z

Methodology: Examples of typos which could be cleaned out of this tutorial in revisions.

Smitch: fixed definition of buffers

2022-01-05T19:02:23Z

fixed definition of buffers

Benjamincolbourne: /* References */

2021-12-23T22:08:01Z

References

Benjamincolbourne: /* Conclusion */

2021-12-23T22:06:16Z

Conclusion

Benjamincolbourne: /* Purpose */

2021-12-23T20:09:43Z

Purpose

Benjamincolbourne: /* Map */

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Map

Benjamincolbourne: /* Categorize the New Buffer Layer */

2021-12-23T20:02:49Z

Categorize the New Buffer Layer

Benjamincolbourne: /* Province Clip */

2021-12-23T19:57:19Z

Province Clip

Benjamincolbourne: /* Reproject */

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Reproject

Benjamincolbourne: /* Map */

2021-12-23T19:52:55Z

Map

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 == Methodology ==
-The goal for this demonstration is to find a set of lakes in Quebec cottage country where you would want to construct a cottage or house that would require a septic system. Septic systems in Quebec must have a minimum distance of 15m from the edge of a Lake, watercourse, swamp or pond. This is stated under section 7.2 of Regulation respecting wastewater disposal systems for isolated dwellings by [http://www.legisquebec.gouv.qc.ca/en/document/cr/Q-2,%20r.%2022 LegisQuebec]. With this information in mind, we will create two buffers. One that is 15m from the edge of the lake (assuming this is the high-water mark) and another that is 100m from the lake (which has randomly been chosen to demonstrate the capabilities of the multi-distance buffer). After both buffers have been completed, a map with proper labeling will be created as a final product.
+The goal for this demonstration is to find a set of lakes in Quebec cottage country where you would want to construct a cottage or house that would require a septic system. Septic systems in Quebec must have a minimum distance of 15m from the edge of a lake, watercourse, swamp or pond. This is stated under Section 7.2 of Regulation respecting wastewater disposal systems for isolated dwellings by [http://www.legisquebec.gouv.qc.ca/en/document/cr/Q-2,%20r.%2022 LegisQuebec]. With this information in mind, we will create two buffers. One that is 15m from the edge of the lake (assuming this is the high-water mark) and another that is 100m from the lake (which has randomly been chosen to demonstrate the capabilities of the multi-distance buffer). After both buffers have been completed, a map with proper labeling will be created as a final product.
 == Process ==

← Older revision		Revision as of 19:02, 5 January 2022
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	~~Buffer’s~~ are a tool used to ~~calculate~~ ~~the~~ ~~distance~~ from an object or set of objects in an environment. In GIS, buffers are ideal for ~~analysis’~~ that involve distance constraints. Some examples of these would be the proximity of an endangered species to urban development or tracking the extent of nuclear fallout. Buffers can be very versatile and are able to provide distances with both raster and vector data (points, lines, polygons) by creating polygons around your designated input features. Additionally, you can either use a fixed width buffer, such as the endangered species example provided above, or a variable width buffer, such as the nuclear fallout example where wind conditions may affect the extent of the area over time. There are countless buffer tools and methods spread across multiple GIS platforms such as ArcGIS Pro/Desktop, QGIS, Maptitude and many more that are all useful.		Buffers are a tool used to define areas at specified distances from an object or set of objects in an environment. In GIS, buffers are ideal for analyses that involve distance constraints. Some examples of these would be the proximity of an endangered species to urban development or tracking the extent of nuclear fallout. Buffers can be very versatile and are able to provide distances with both raster and vector data (points, lines, polygons) by creating polygons around your designated input features. Additionally, you can either use a fixed width buffer, such as the endangered species example provided above, or a variable width buffer, such as the nuclear fallout example where wind conditions may affect the extent of the area over time. There are countless buffer tools and methods spread across multiple GIS platforms such as ArcGIS Pro/Desktop, QGIS, Maptitude and many more that are all useful.

	== Purpose ==		== Purpose ==

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 == References ==
+*Inhabited places - Government and Municipalities of Québec 2017: (https://open.canada.ca/data/en/dataset/1f3b874d-f881-4a6c-86ac-cfba856dfafc)
+*Provinces/Territories, Digital Boundary File - 2016 Census: (https://open.canada.ca/data/en/dataset/47bd4f2e-1c77-49f8-8406-dc4dca64ee6b)
+*Road Network File - 2016 Census: (https://open.canada.ca/data/en/dataset/57d5ffae-3048-4a19-9b4c-eab12f6322c5)
+*Water File - Lakes and Rivers (polygons) - 2011 Census: (https://open.canada.ca/data/en/dataset/448ec403-6635-456b-8ced-d3ac24143add#rate)
+*QGIS Download: (https://qgis.org/en/site/forusers/download.html)

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 == Conclusion ==
+The multi-distance buffer tool turned out to be critical in this tutorial as it provided the necessary functions to create multiple buffers in one shapefile. Other methods such as the stock buffer tool in QGIS and the single sided buffer proved to be functional through testing but neither tool was able to put multiple buffer distances into one shapefile.
 == References ==

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 == Purpose ==
-The purpose of this demonstration is to show users a step-by-step process on how to use the QGIS plugin ‘multi-distance buffer’ in QGIS. This GIS procedure that will be demonstrated is a buffering/overlay tutorial which will show the minimum distance required for installing septic systems from various lakes in Quebec cottage country. The step-by-step process will cover how to download/install the software along with the data, the steps required to create the buffer(s) as well as composing the final map.
+The purpose of this demonstration is to show users a step-by-step process on how to use the QGIS plugin ‘multi-distance buffer’ in QGIS. This GIS procedure that will be demonstrated is a buffering/overlay tutorial which will show the minimum distance required for installing septic systems from various lakes in Quebec cottage country. The step-by-step process will cover how to download/install the software along with the data, the steps required to create the buffer(s) as well as an example of a final map.
 == Software/Data ==

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 == Map ==
+The figure below is an example of a final map you may produce from this tutorial. You will notice there are map elements added such as labels, titles, descriptions etc.., which can all be added to your liking in the symbology and labels section in your layers tab and the map layout pane.
 [[File:Final Project5.jpg|800px|Figure 16. Final Map]]

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 To categorize your new buffer layer, open up the '''Symbology''' tab under '''Layer Properties''' from your buffer layer. Select '''Categorized''' as your symbol, '''Distance''' as your value, then click the plus button twice to add two entries. Add values of 15 and 100 respectively and choose an appropriate colour for each entry. Once you are satisfied, click '''OK'''.
-[[File:Fig 15g.jpg|400px|Figure 14. Example of the symbology used or the multi-distance buffer in this demonstration]]
+[[File:Fig 15g.jpg|400px|Figure 15. Example of the symbology used or the multi-distance buffer in this demonstration]]
+[[File:Figure 16.jpg|600px|Figure 16. QGIS work environment with proper categorization]]
 == Map ==

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	Next, we will '''clip''' all four layers to the extent of the province of Quebec. To do this, under the '''Processing Toolbox''', search for the '''Clip''' tool, right-click and select '''‘Run as Batch Process’'''. Under input layer, click '''''Autofill''''' → '''Select From Open Layers''', a new window will pop up: click '''Select All''' then click '''OK'''. Next, make sure your '''overlay''' layer is set to your Provinces and Territories layer then click the three dots → name as 'clipped' and save the files in your working directory. Under '''Autofill Settings''' select '''Fill with parameter values''' under Autofill mode and '''Input''' under Parameter to use. Check off the ‘load layers on completion’ box at the bottom left then click '''Run'''		Next, we will '''clip''' all four layers to the extent of the province of Quebec. To do this, under the '''Processing Toolbox''', search for the '''Clip''' tool, right-click and select '''‘Run as Batch Process’'''. Under input layer, click '''''Autofill''''' → '''Select From Open Layers''', a new window will pop up: click '''Select All''' then click '''OK'''. Next, make sure your '''overlay''' layer is set to your Provinces and Territories layer then click the three dots → name as 'clipped' and save the files in your working directory as a shapefile. Under '''Autofill Settings''' select '''Fill with parameter values''' under Autofill mode and '''Input''' under Parameter to use. Check off the ‘load layers on completion’ box at the bottom left then click '''Run'''

← Older revision		Revision as of 19:56, 23 December 2021
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	Once the '''CRS''' is set, click the three dots → name as 'reprojected' and save the files in your working directory. Under '''Autofill Settings''' select '''Fill with parameter values''' under Autofill mode and Input under Parameter to use. Check off the ‘load layers on completion’ box at the bottom left then click '''Run'''.		Once the '''CRS''' is set, click the three dots → name as 'reprojected' and save the files in your working directory as a shapefile. Under '''Autofill Settings''' select '''Fill with parameter values''' under Autofill mode and Input under Parameter to use. Check off the ‘load layers on completion’ box at the bottom left then click '''Run'''.

	Note: It is important to make sure your new layers are created in compliance with how your operating system saves its files. i.e., no special characters or spaces etc. Additionally, you may encounter a ‘?’ beside each one of your layers indicating the layer has not been assigned a CRS. If this is the case, click on the ‘?’ and assign the CRS to the same projection as you have just performed (i.e., '''WGS 84 [4978]'''. Additionally click the CRS button at the bottom right corner of QGIS (little globe) and make sure it is set to '''WGS 84 [4978]'''.		Note: It is important to make sure your new layers are created in compliance with how your operating system saves its files. i.e., no special characters or spaces etc. Additionally, you may encounter a ‘?’ beside each one of your layers indicating the layer has not been assigned a CRS. If this is the case, click on the ‘?’ and assign the CRS to the same projection as you have just performed (i.e., '''WGS 84 [4978]'''. Additionally click the CRS button at the bottom right corner of QGIS (little globe) and make sure it is set to '''WGS 84 [4978]'''.