Road Graphs and the Environment
Paper Link: http://www.aporc.org/LNOR/8/ISORA2008F19.pdf
So far in the course, in terms of graph theory, we have focused on connections between people and towns. We have explored how the connections between nodes represent friendships and roads, and what these connections imply. But there are many more ways to analyze graphs that weren’t discussed in class. Two researchers, Shiliang Liu and Yuhong Dong at the Beijing Normal University used a unique analysis of graph theory to investigate a connection between the construction of road networks and environmental characteristics.
The study was conducted in the Lancang River Valley which is a junction of Southwest China and Southeast Asia. The area, as stated in the paper is well knoxwn for its biological diversity and complex ecosystems, as well of its high use of highway transportation. Over 90% of the road transportation is done on highways. The researchers obtained the road vector data from thousands of road databases belonging to the Fundamental Geographical Info Center. Where this study begins to overlap with concepts discussed in class is the manner in which the researchers analyzed the graph data. The graphs were characterized by three attributes: an α index, which represents the loop percentage of the network, a ß index, which represents average lineage of each node, and a Ƴ index, which represents network connectivity. These indices are quantitative measures of concepts presented in lecture. The α index and Ƴ index, measures how circular and connected the nodes in a graph are, so these attributes would imply triadic closure among the nodes in the graph since graphs that satisfy the strong triadic closure property must have loops connecting nodes that have some string connection. Also, the ß index, which is <1 when the network forms a tree pattern and >1 when the graph has more complicated structures, can have implications on where bridges are within the network.
I think that this was a cool research project since it linked graphs to something that I would have never thought of. Usually, graphs give information about friendship networks or road systems, but in this project, the researchers were able to retrieve information on the features and changes in the surrounding landscape by analyzing the graph of roads in the area. I think more of this type of research should be conducted since advances in projects such as this could greatly benefit the conservation of our natural environment.
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