Manatee - Sarasota County Transmission Line
Cameron Jackson, 12/10/2020, UWF GIS4043/L or GIS5050/L
Project Background
- Analysis of communities, environmentally sensitive land, and land types proximate to corridor outlining transmission line traversing the Manatee - Sarasota County boundary line
Objectives: Analyze and interpret qualitative and quantitative data relative to environmentally sensitive land impacted by transmission line installation; evaluate quantity of homes within transmission line corridor; evaluate quantity of schools and daycares proximate to corridor; compute length of transmission line
- GIS is necessary in implementing an analysis which is so involved, and contains so much data pertinent to geography, land, and the surrounding community. It facilitates the necessary qualitative and quantitative data analysis needed for a thorough examination.
Data required: shapefiles for NWI study area, conservation areas, county boundaries and parcels, major roads, corridor outlining transmission line, major local roads, wetland and upland area (retrieved from NWI), homes, and schools/daycares (retrieved from FGDL)
The Problem?
It is important that the placement of this transmission line is such that the impact to environmentally sensitive land, and the surrounding communities, is minimized as much as possible.
- In order to achieve the goal of minimal impact, and the most efficient placement, GIS was utilized (and necessary)
Projection Screenshot
- Projection inclusive to every layer: preferred corridor (light coral polygon), study area (light yellow), conservation areas (red polygons), wetlands (green and blue color scheme), homes, schools, and daycares.
Analysis - Study Area
Represented by square yellow polygon.
- 118,666 acres
Analysis - Conservation areas proximate to the corridor
- Represented by red polygons
- Total Conservation area proximate to transmission line - 159,765 acres
Analysis - Conservation areas intersecting corridor
Intersecting conservation areas represented by purple polygons
- 7,312 acres
- To find acreage of conservation land intersecting corridor, I clipped the polygons within the “conservation_land” layer which were not intersecting the corridor, forming a new layer which consisted of intersecting conservation land. I then use the “calculate geometry” to find the area.
Analysis - Homes within buffered corridor
Homes within preferred corridor: 159
Homes within 400 foot corridor buffer: 175
- I manually digitized homes within the corridor and the 400ft corridor buffer via creating a new point shapefile.
o Created two fields for this point shapefile: within_pc and 400ft_pc fields
o To assign each data point to one of the two fields, I used “select by location” to select homes within the corridor, and then used field calculator within the attribute table to populate the selected records inside the “within_pc” field. I then used switch selection, which selected all records outside the corridor, but within the 400 foot buffer, and used field calculator to populate the selected records within “400ft_pc”. I also used field calculator to assign ID of 1 for polylgons within the preferred corridor, and 2 for the polygons within the 400 foot buffer.
Schools & daycares proximate to corridor
Public or post-secondary school - purple animation with white background
Private school - light coral in color, outline with no fill.
Daycare - green pushpin
I gathered data for schools and daycares proximate to the corridor via FGDL.com, in the form of several point shape files.
Analysis - Wetlands & Uplands within (buffered) preferred corridor
Wetlands within corridor: 1,113 acres - 16.4 percent
Uplands within corridor (mango color): 5,652 acres - 83.3%
Total corridor area (including buffer): 6,785
Land types within corridor: freshwater emergent wetland, freshwater forested/shrub wetland, freshwater pond, lake, riverine
- Finding the land types intersecting the corridor proved challenging. I added a connection to a geodatabase which I retrieved from NWI, called "NWI_Code_Definitions.gdb", and this contained data for the wetland/land type, as well as a symbology format called "Mapper_Legend_Display" (both of which I implemented). I then added a connection to another geodatabase retrieved from NWI, called “FL_geodatabase_wetlands”, which contained a set of file geodatabase feature classes - I decided to implement the feature class titled "FL_Wetlands". It took quite a bit of fiddling with tools to figure out how to do this, but I eventually did figure out how to implement the Mapper_Legend_Display symbology layer into the FL_Wetlands layer by utilizing the "Apply Symbology From Layer" tool. To find the acreage of uplands in the corridor, I used a definition query and created a new layer which clipped out everything aside from the “upland” areas of land, which was identified with the NWI code, "U". My next task was create a layer which consisted of strictly upland areas of land, clipped within the corridor boundary. To do this, I first clipped the "FL_Wetlands" layer to the "PreferredCorridor", and then clipped "NWI_studyarea" layer to the "PreferredCorridor" as well. This gave me the two layers comprising the inside of the corridor as shown in this slide - uplands being mango colored, and wetlands symbolized by the "Mapper_Legend_Display" symbology. Although both layers were clipped, in the attribute table, and statistics, it was still registering the area of the unclipped original layers. I used “calculate geometry” and revised the acreage of the upland area to include only upland area inside the corridor boundary; once this was completed, I went to statistics to note the acreage of uplands inside the corridor. To find the acreage of wetlands, I used the same process - utilized “calculate geometry” and revised the acreage to include only wetland area inside the corridor, and again went to statistics to note total acreage of wetlands within the corridor. The combined acreages gave me approximate total corridor acreage.
- To find the types of land intersecting the corridor, I went to the attribute table of the "FL_Wetlands_Clip" layer (FL_Wetlands clipped to corridor) and retrieved the data within the “Wetland_type” field.
Transmission Line Length
- 96,901 feet
I simply used the measure distance tool to calculate the length of the transmission line.
Conclusion
- This transmission line was effectively installed, from what I can tell. It is in between two neighboring communities, so as to avoid running through, or too close to, any one community.
- The land it runs through is primarily rural, which was clearly the intent.
- Looking at the wetlands in the area, it is apparent that it was installed so as to avoid sensitive wetland areas if at all possible, though it does intersect some wetland area, as well as several streams and rivers.
- The transmission line pathway is not a straight shot, and this is seemingly to avoid running it through conservation areas, along with other strategic factors.
- The path does not intersect the conservation areas if at all possible. There is a little bit of intersection with conservation areas, but kept to a minimum.
- There are no schools or daycare facilities within the corridor, however, there are homes. This would make sense, seeing as avoiding areas highly populated by children is likely prioritized over home proximity.
- The middle segments run along major roads which are rural, unpopulated, and already being utilized for public works, therefore making these roads efficient pathways.
- Overall, this appears to have been very thoughtfully planned out, taking into consideration the health of the environment and neighboring communities. This application of GIS showcases the value of utilizing GIS to facilitate effective analysis within city departments tasked with implementing involved structures such as this transmission line.
Works Cited
University of Florida Geoplan Center. Florida Geographic Data Library. FGDL Search/ Download Data. https://www.fgdl.org/metadataexplorer/explorer.jsp.
U.S. Fish and Wildlife Service. National Wetlands Inventory. https://www.fws.gov/wetlands/index.html.