Changes in Vegetative Land Cover in Dallas, Texas from 2004 to 2018, studied through NDVI.
Course: Foundations of Geographic Information Systems
Date: Spring 2021
Type: Data Mapping and Analysis
Background: This course introduced the basic concepts of geographic information systems and taught us how to use different tools in ArcGIS such as buffer, raster calculator, overlay, etc. Our final project for this class required us to create a project that reflects on the fundamentals of GIS technologies and tools, so I decided to use raster calculator to create NDVI images to see how the land cover has changed over 14 years. I chose Dallas, Texas because it is an area that has extremely hot summers and cold snowy winters. Therefore, the vegetative land cover is prone to changing. In this project, the goal was to find out how the weather and changing city scape has affected the vegetative land cover over the span of 14 years.
Research Question: How has the vegetative land cover changed in Dallas, Texas from 2004 to 2018?
Data and Materials: The data for this project comes from the Texas Natural Resources Information System (TNRIS). The specific images that I used for the NDVI comparisons came from the Texas NAIP category because this category used CIR imagery, which is necessary when creating an NDVI image.
Methods: First I found NAIP images from the same area of Dallas, Texas for the years 2004 and 2018 and then I exported them to ArcMap and changed the images into CIR photos by changing the bands to display RGB. At this point I opened the Raster Calculator and plugged in the NDVI formula to create the final NDVI image. Once I plugged in the NDVI formula for both images in Raster Calculator the two images could be compared to see if the vegetation cover has changed in the 14 years between the two photos.
Workflow:
​
​
​
​
Results: By using the Raster Calculator I succeeded in creating two NDVIs that show the change in land cover in between 2004 and 2018. In these maps, the red and dark blue colors equal healthy vegetation while the light blue, yellow and green represent areas of little to no vegetation. The results showed a noticeable difference in the vegetative land cover in Dallas in 2018 compared to 2004.
Discussion: Using Raster Calculator, I was able to create two NDVIs that showed me that there was a noticeable change in land cover in Dallas, Texas from 2004 to 2018. One major conclusion that was noted between the two images was that the grassland area that was around the river in the 2004 image has withered a bit in the 2018 image. However, it must be considered that the image that was used for the 2018 NDVI could have been taken in the winter or the middle of summer when it is extremely hot as both seasons would influence the vegetation.
​
Key Figures:
