Project 4 Prepare week

For prepare week of Project 4 I was required  to locate clear cut areas that were visiable from roads that run throughout the area.  The study area was a  1400 ha “woodlot” located in New Brunswick, Canada. The first step in the analysis was to identify recent clearcuts adjacent to the main roads.  After adding the “cover” feature class to my workspace, I selected the main roads by selecting by attribute the cover type “RD”.   Next I did a select by location query to find the cover types that were adjacent to, or intersect my main road selections. Once this was complete I isolated the clearcuts and treed bogs from the selection by doing a select from current selection “all treed bogs and stands with an age of greater than or equal to “0” years and less than or equal to 5 years”. This left me with 43 clearcuts visible from main roads.  I then opened the attribute table calculated the statistics for the “shape_area” field to determine that the total area of clearcuts adjacent to the main roads occupied approximately 121 ha. 

Next I needed to identify boundaries shared by main roads and clearcuts.  To start this process I opened the “feature class to feature class tool.  I named the output “cover_arcs” set the coordinate system to the appropriate projection, and made all other entries, and ran the tool. I then joined the coverage PAT to the cover_arcs AAT using “COVER# and LPOLY as identifiers. Once this was complete I did a select by attribute from cover_arcs to isolate arcs with recent clearcuts on the left using the expression provided in the lab sheet.  I added a new field in the attribute table “LeftPoly” and assigned it a value of “CC” with the field calculator.  I then repeated these steps for the clearcuts on the right. I then removed the join.  I then did a select by attribute to calculate the total length of boundaries shared by young clearcuts and main roads.  This turned out to be 44 arcs with a length of nearly 8 kilometers (7.74).  To see how many, if any of the clearcuts were adjacent to each other I used the Dissolve tool. Once this tool was ran, it indicated that one area was nearly a kilometer long.

To calculate the viewshed for all roads I opened the “clines” feature class in Arcmap.  I then removed the sewer line and power line easements using the “definition query” and renamed the layer “Main Roads”.  Using the Merge tool I combined Main Roads with proads named the new feature class “RoadViewers”.  I then added the elevation raster as a layer.  I used the “feature to raster” tool to add stand heights from the cover layer to the elevation layer. I named the output “HeightClasses”.  To fix a band of “no data” I merged the publicrow with the cover layer and then computed a new “HeightClasses” raster.  Using the Raster Calculator and the elevation raster, and HeightClass layer I created a viewing surface, named oddly enough “ViewingSurface”.  Using the viewshed tool and the RoadViewers feature as the observer and ViewingSurface as the viewing surface I created a new layer named “Viewshed”. 

To determine the amount of visible clearcut I used the definition query to isolate young clearcuts in the cover layer, and renamed the layer “RecentClearcuts”. This operation selected 121 stands.  I then used the “feature to Raster” tool to convert “recentClearcuts” to a 10 m cell-sized raster and named the output “Clearcuts”.  To calculate where both “Clearcuts” and “Viewshed” exist I used the Raster calculator with “Clearcut” & “Viewshed” as input and named the output “VisibleClearcuts”.  The map above is a base map that depicts the study area I will be using for the entire project.