Michael Parks explains how he used GIS data and imagery to develop geospatial analysis and maps to recommend potential base camp sites.
Proper land use and facilities planning requires a thorough understanding of the proposed site—its physiography, hydrology, climate, human geography, and infrastructure. If you are going to build any type of long-term facility in a region, you must understand where you are building, what environmental factors can impact you, as well as the impacts that you will have on your environment. Engineers and project planners conduct site surveys to develop this critical information.
Traditionally, such site surveys were done in person, but with the advent of powerful GIS imagery and tools, we can visualize terrain from half a world away. GIS allows for a rapid, low-impact, low-budget macro and micro analysis of an area of interest. Furthermore, GIS allows us to visualize the land from miles above, and see it with digital eyes that capture what the human eye cannot.
In this article we will look at one application of remote sensing study to military base camp planning. Using open-source data and QGIS we will survey the South American country of Uruguay to identify potential base camp sites.
This location was chosen because of its small size, varied topography, and the limited amount of open-source data available (which allows us to demonstrate just how much one can do with limited resources).
Our study is given from the perspective of military planning, but the tools and techniques demonstrated have broad applicability to a variety of area studies, types of facilities, locations, and uses.
The Scenario: Evaluating Candidates for a Base Camp in Uruguay
Let’s begin by creating a scenario for our GIS study. Imagine you are an Army Geospatial Engineer working on the staff of the Division Commander. He has recently been advised to prepare a Brigade of 3,000 Soldiers to deploy to Uruguay for 3-5 years.
The brigade mission is to assist and support the host nation’s armed forces.
The staff is very early in the planning process, and details are scant, but the Commander would like to identify and study some potential base camp sites. Your task as the Geospatial Engineer is to conduct a broad-scope survey of the physiography and infrastructure of the host nation–including geologic features, waterways, transportation routes, and population centers–for the purposes of evaluating and recommending potential base camp sites.
The Division Staff has worked up a list of potential candidates based on their initial study of the problem; you are to evaluate these for suitability and propose additional sites. Your analysis should consider area security, logistics, access to HN officials and agencies, interference with the host nation populace, and environmental impact.
The Commander would also like to see some maps to accompany your study and recommendations.
Step #1: Outline the Problem
You have some challenges and limitations. The area of study has not had extensive geospatial study like the US, so there is a limited amount of data products available to you. Because of information security requirements, and the planned distribution of your maps, you must only use Unclassified data with unlimited distribution.
There is redundancy in the available data, so you must sift through and filter what is unnecessary to your project. You are required to use free and open-source software—budget cuts.
Lastly, you will need to conduct a meaningful analysis of your data layers, then transform and combine them deliberately to render data into information that fosters understanding in your audience and empowers their decision-making.
Step #2: Research available Data and Develop Initial Imagery
A good starting point for our QGIS project is the development of some base maps. XYZ Tiles are great for this purpose—they are free layers that are connected to your QGIS application through the web and can be easily modified to create the desired map layer.
A simple web search yields abundance of resources on how to add XYZ layers in QGIS, along with URLs of several maps to sync with QGIS. My primary source for XYZ Tiles was an article on Spatial Bias.
For this study we will primarily use the Esri Topo and Esri Imagery Tiles, although Google Hybrid and Carto Positron are useful as well. Each of these maps offers a different look at the terrain and has its advantages when layering data (e.g. the Esri Imagery is particularly useful as a base layer for DEM raster layers, as we will discuss below).
In the image below, we have layered our proposed sites over an ESRI Topo Map to visualize our sites.
Following an initial orientation to the terrain, we need to add some administrative and geographical data—administrative boundaries, roads, rail, waterways, land use, and points of interest.
Below are the readily available sources used for our study:
- OSM Data (Roads, Rail, Waterways, Landuse, Buildings, POI), format: SHP.
- Open Street Map HOTOSM Waterways Data, formats: SHP, GEOPKG, KML.
- DIVA-GIS – Country Vector Data, formats: SHP, Raster.
These sites provide a wealth of information which needs to be sorted and organized to create the right visualization for the data. We selected road, rail, waterway, landuse, and population data to help us visualize resources of the land, available space, and logistic capabilities. They were then overlaid on an Esri Topo Map to create the image below.
Now we need to take a closer look at population density. A useful method to conduct this analysis is to develop a classification image to show population density across the country.
A grayscale raster image was obtained from DIVA-GIS, but displayed too little variance to be useful. To enhance the contrast, we processed the Singleband Gray image into a Singleband Pseudo-color image, with an inverted spectral color ramp (Red = High Value, Blue = Low Value) in the Quartile mode.
The result was an image that grouped population densities into regions. Layering with OSM data over an Esri Topo Map, it gives a much more informative image.
We have now viewed our proposed sites with reference to population, landuse, waterways, and transportation routes. Using measuring and buffering tools in QGIS we are able to determine distance to specific locations and estimate travel times.
But what about elevation? It would be important to know whether one of our sites was on top of a mountain, right?
To solve this problem, we turn to Digital Elevation Model data developed from ASTER and SRTM imagery, obtained from USGS GloVis and Earth Explorer. Each DEM raster file covers about 4000 square miles (approximately 60 x 70 miles), but these individual images can be combined into one Virtual Raster in QGIS to cover the entire study area.
This new raster layer can then be manipulated to visualize and study the elevation around our proposed sites. For our study, the original grayscale image was duplicated, and each image was transformed—one into a Hillshade image showing the contours of the surface, and the other into Singleband Pseudo-color image continuously classified using a topographical color spectrum available in QGIS.
These new color and hillshade DEM layers can then be rendered as overlays, using the Blending Mode function, on top of an ESRI Imagery Map, giving us the following image.
The Esri imagery layer gives us an accurate background for the image, the hillshade layer highlights the contours of the terrain, and the color layer visualizes the height and depth of the terrain.
Terrain analysis using the above image adds a great deal of value to the overall study, allowing us to recognize potential problems with Site #3 (situated on top of a 500m peak) and Site #2 (separated from the city and port of Montevideo by a mountain range).
Step #3: Analysis and Recommendations
We have developed three composite images for our study—a Topographic Map, a Population Map, and an Elevation Map.
We can now conduct our analysis, rank our sites based on the Commander’s guidance, and propose additional sites for consideration by the staff.
Surveying our imagery, we see that Site #1 is proximate to roads and rail lines, but has limited access to water sources, and is perhaps too close to the urban center of Montevideo. Site #2 has access to roads, rail, and water, but is separated from much of the country by a mountain range.
Site #3 is disadvantageous in a number of ways: distance from population centers, limited access to rail lines, and logistical difficulties associated with the high elevation. Site #4 has access to several resources but is prohibitively distant from the city and port of Montevideo.
Looking for other potential candidates, we discover a site in the province of Florida which meets all of the Commander’s requirements. We’ll call this Site #5 and add it to our layer of proposed sites.
Finally, we develop our final map products for the Base Camp Development Plan (BCDP) and present them to the Division Staff. Once a particular site or sites are selected for additional study, we can focus in at a micro level and develop detailed maps for each site.
These products can in turn be used to prepare reconnaissance teams to conduct in situ surveys of the proposed sites.
Conclusion: Applications of GIS
As we have seen in the study above, one can conduct an effective site study using open-source data and a basic working knowledge of QGIS. While it may not be as robust or widely-used as some popular pay-to-use programs, QGIS offers all the utilities needed to process a variety of data and produce quality maps for decision making.
There is a broad applicability to site surveying for a variety of uses: base camps, training and support facilities, recreation facilities, etc. These techniques are also scalable: from national surveys to regional surveys, to local area surveys, to individual building site surveys.
Whether it be in the forests of Uruguay, or in your own backyard, open-source GIS data and the tools of QGIS offer an efficient and effective solution for land use planning.
About the Author
Michael Parks is an Engineer Officer in the US Army Reserve, currently in training at the US Army Engineer School in Fort Leonard Wood, MO. He has recently completed the Captain’s Career Course, which is designed to train junior officers in all aspects of military Engineering and prepare them for challenging command and staff assignments. He is also a graduate student in Geological Engineering at the Missouri University of Science and Technology in Rolla, MO. He is blessed to be married to his best friend, DeAnna, who has given him three beautiful daughters.