WIND TURBINE VISIBILITY ON THE COLBY CAMPUS

Emma Balazs ’09 and Jenny Helm ‘11

ES212: Introduction to GIS and Remote Sensing

Environmental Studies Program, Colby College

Abstract

This project was designed to demonstrate the visibility of potential future wind turbines built on the Colby campus. We conducted viewshed analyses in ArcGIS on three different potential turbine sites to determine the visibility of the turbines within a 10km radius. We found that the Runnals hill turbine would be visible to the largest area and the largest number of residents.

Introduction

There has been some discussion in recent years by both students and administrators about the possibility of placing a wind turbine on the Colby campus. A wind turbine would provide green power to the campus and would serve as a symbol of environmental awareness. This project shows the visibility of a turbine if it were constructed at one of three locations deemed suitable. This information could be used in the future to aid a decision about where to place a wind turbine on campus.

Methods

Using ArcGIS, we determined three locations on or near Colby property that would be suitable for wind turbines based on an elevation map that we created (Figure 1) within a 10km radius (Figure 2). We created two points at each location, one of which was given a 20m height while the other was given a 70m height, to enable comparison between the visibilities of turbines of two different sizes. We then obtained digital models of buildings on the Colby campus from the Colby College Physical Plant Department. For each building, we determined an average height and applied it to the polygon representing the footprint of that building. Next, we digitized polygons representing forested areas on and around campus and used a clinometer to come up with average tree heights. We then burned the vegetation and building layers into our original elevation layer so the buildings and trees were represented along with the topographical features of the town and campus. Based on this new elevation layer, we created a viewshed for each of the six potential wind turbines. We then calculated the total area on campus from which each of the six towers would be visible and the total area in a 10km radius of the towers from which the turbines would be visible. We also counted the number of people in census blocks located in visible areas to determine the number of residents within a 10km radius who would be able to see the turbines.

Results

We found that the site on Runnals hill is most visible in terms of total area within a 10km radius and area on campus (Figures 3, 6, and 7). The Washington Street site is the second-most visible within a 10km radius, but is least visible on campus (Figures 4, 6, and 7), while the lacrosse field site is least visible within a 10km radius and is the second-most visible on campus (Figures 5, 6, and 7). Among the 20m turbines, the site on Runnals hill would be visible to the largest number of people, followed by the lacrosse field and then the Washington Street site. Among the 70m turbines, one sited on Runnals would be visible to the largest number of people, followed by the Washington Street site and then the lacrosse field. Please see Table 1 for full results.

Discussion

If Colby wants to construct a wind turbine in a place that allows for very high visibility to the surrounding area as a symbol of environmental awareness, Runnals Hill would be the best site. However, if the college wants to minimize visibility so as not to disrupt views, it would be wiser to choose the site by the lacrosse field. If the college wants to minimize visibility on campus but still maintain moderate visibility outside of campus, the Washington Street site would be the best choice. In addition, a 70m wind turbine would be visible to a much larger number of people within a 10 km radius than a 20m turbine.

Conclusion

· Most visible wind turbine site within 10km radius: Runnals Hill

· Least visible wind turbine site within 10km radius: Lacrosse Field

· Most visible wind turbine site on campus: Runnals Hill

· Least visible wind turbine site on campus: Washington Street

· Wind turbine site visible to most residents in a 10km radius: Runnals Hill

· Wind turbine site visible to fewest residents in a 10km radius: Lacrosse Field

Data Sources

The aerial photographs were obtained from the United States Department of Agriculture’s National Agriculture Imagery Program (http://165.221.201.14/NAIP.html). The elevation layer was obtained from the Maine Office of GIS. Colby buildings and vegetation layers and building height data were obtained from the Colby College Physical Plant Department.

Acknowledgements

We would like to thank our professor, Philip Nyhus, for his ideas and feedback about our project. We would also like to thank the Colby GIS specialist, Manny Gimond, for his advice and help with obtaining and converting data.  Finally, we would like to thank Patricia Murphy and Andy Gockel of the Physical Plant Department and Matt Kearns of First Wind for providing us with critical information for our analysis.

Appendix

Table 1. Results of area and population analyses

Figure 1. Elevation around turbine sites

Figure 2. Study area

Figure 3. Viewshed of Runnals Hill site

Figure 4. Viewshed of Washington Street site

Figure 5. Viewshed of lacrosse field site

Figure 6. Areas within a 10km radius where each turbine is visible

Figure 7. Areas on the Colby campus where each turbine is visible

Figure 8. Total number of residents within a 10km radius that can see each turbine