This is Why GIS Spatial Analysis is Special

This year’s Climate and Society class is out in the field (or lab or office) completing a summer internship or thesis. They’ll be documenting their experiences one blog post at a time. Read on to see what they’re up to.

Xuefei Miao, C+S ’16

Have you ever used GIS to analyze data? GIS — short for Geographic Information System — is a mapping tool that be used to turn datasets into useful information. I’ve learned how special GIS spatial analysis can be in solving problems after my internship at Agriculture and Food Security Center at Columbia’s Earth Institute.

If geography is ultimately about the holistic and comprehensive understanding of place, we might expect GIS to help us understand where things are and help us get to a holistic and comprehensive understanding of that place. All of that is true, broadly speaking, but I have a developed a deeper understanding of GIS application during internship. I’m working on a tiny part of the Millennium Villages project, a new and indeed unprecedented attempt to use foreign aid to jump-start economic growth in a number of African villages. There are 13 basic clusters of Millennium Villages in Africa.

Before doing some specific analysis using GIS, I had to do data cleaning first as there might be some control points of Millennium Villages with wrong latitude and longitude which makes them located out of the local village. As a next step, I collected related information about these countries and villages like government boundaries and high-resolution remote sensing images in specific period that we needed to analyze.

And the most important part of my internship was to do various analysis in ArcGIS, my preferred GIS software. Take the analysis tool to extract multiple values to points as an example. I got the high-resolution base map for the world, but the image size was too big which would slow down the analysis process in ArcGIS so I did the image extraction by mask. And then I used the toolbox to do extraction, then the attributes of the global image were shown on the points layer attribute table.

Land use in Ghana (left), Uganda (center), and Tanzania (right)

The products I made from GIS can be used in other analysis software to do further analysis. Using GIS data in Excel, for example, I made distribution plots and graphs of land use and land cover change to show the land cover types in different period.

Issues such as climate change and biodiversity loss, natural hazard, water quality degradation and more are becoming increasingly complex. The act in a global scale but they also increasingly affect our everyday lives at the local scale. My internship opened my eyes to thinking about the world geographically and using GIS to understand and make more effective decisions about environmental issues from local to global scale.

Histogram 1: LULC distribution in Ghana

Histogram 2: LULC distribution in Tanzania

GIS technology is critically important to make sense to these issues. That’s because GIS allows people to use real data including databases, maps, satellite images and models in a systematic way for decision making.