the South fraser perimeter road

In the process of working on our project, we encountered a number of possible sources of error.

data Uncertainties

Agricultural Land Reserve

This 2003 data was obtained from the BC Provincial government. The ALR polygons did not account for those lands that have been removed from the ALR for the construction of existing freeways. Therefore, our calculation of total agricultural land and agricultural land that falls within 1km of the SFPR is likely to be slightly larger than it is in reality.

 

Burns Bog

The Burns Bog shapefiles were digitized and provided to us by the Wilderness Committee. These files did not contain any attribute data and were not 100% accurate. For example, the portion of Burns Bog under the Conservation Covenant was overlapping with the SFPR in some areas. This is inaccurate as we know that none of the proposed SFPR goes through conservation lands. For this reason, we were unable to calculate the specific area of Burns Bog that falls within 1km of the SFPR.

 

Parks & Recreational Areas

The parks data was derived from a land use layer. The attribute table for the parks data only provided us with the area in meters squared that was designated with this land use, and did not provide us with the number of parks that fall within 1km. Also, areas considered parks and recreational areas in this particular land use layer include areas that are floodplains.

 

NO₂ and PM_2.5 Multivariate Analysis

Both the NO₂ and PM_2.5 raster layers were created using a multivariate analysis, where multiple parameters were used to create a continuous surface that models levels of NO₂ and PM_2.5. These models are only estimates and have a large margin of error. The parameters used to model PM_2.5 were roads (10km buffer), industries emitting PM_2.5 (5km buffer), satellite estimates which read the reflectance of certain particles, and precipitation (higher precipitation means lower levels of PM_2.5). The parameters used to model NO₂ were highways (100m buffer), major roads (100m buffer), population density (2500m buffer), open areas (150m buffer), and residential areas (750m buffer).

Methodology Uncertainties

Streams and Rivers

When we had nearly completed our project, we realised that our streams data was not very accurate. The area calculated that fell within 1km of the SFPR was almost 79km, which did not make sense because the SFPR is only a 40km long freeway. We then realized that the calculated length of the Fraser River, according to our shapefile, was approximately 231km, which is also incorrect. In order to correct for this, we divided the incorrect area that fell within 1km of the SFPR by the total (incorrect) length of the Fraser River and came up with a percentage. We then attributed that same percentage to the estimated actual length of the river (40km), and came up with a result of 11.124km.

1km Buffer

We chose our 1km buffer based on the BC Provincial government’s Local Air Quality Impact Assessment. However, this does not mean that all areas beyond the 1km buffer would not be impacted by air pollution from the SFPR, or that all areas within the 1km buffer would necessarily experience an equal increase in air pollution. Other factors such as temperature, precipitation, wind direction, and wind velocity would all contribute to a high level of variance both within and without the 1km buffer zone.

PM 2.5 Histogram

The x-axis’ of the PM_2.5 histograms are categorized based upon different bin values. Attention should be paid to this when comparing the two.