How to find, evaluate, and use geospatial data in a GIS: A short course

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01-03-2024 02:44 PM
JosephKerski
Esri Notable Contributor
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One of the topics I frequently write and teach about is how to find, evaluate, and use geospatial data.  Given the advance of the open data movement, the plethora of geospatial data libraries, portals, and Hub sites, and the increasing ease of bringing that data into ArcGIS Pro, ArcGIS Online, and other tools, is such a course still needed? 

I submit that this type of workshop and course is needed more than ever, because  (1) It is easier than ever to find and add data to your GIS, but with the rise of open platforms including crowdsourced data, it is more important to cultivate the attitude of critically evaluate any data before use, asking who created it, why, and how?   (2) Each data set is still bound to the temporal and map scale at which it was created; each data set has benefits to its use and also limitations.  (3)  The rapidly evolving GIS platform means that the types of GIS files has expanded, but also the means of serving that data--some is downloadable, some is streamed, some updates in real-time, some is static.  Which is most suitable for your needs?  (4)   The use of, and the communication that you do with your mapped data after you are done analyzing and issue, and who you share your web mapping applications with, are laden with ethical choices and issues, including location privacy, copyright, symbology, projection, classification, filtering, and much more. 

I recently taught a new edition of this course that I wanted to share, in this essay.  Much of the content for this course comes from writings that Jill Clark and I have been creating for years on our geospatial data blog, Spatial Reserves.  This column stemmed from the book we wrote for Esri Press on the same topic.

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What are modern best strategies for finding geospatial data?  Despite the increase in volume and variety of spatial data even in the years since we have been writing about data, I still receive this question several times each week.  And for good reason–-(1) Data needs are often very specialized, in theme, scale, region, attributes, and other characteristics, and often it is difficult to find a thread of a similar search by someone else online; (2) The ephemeral nature of the web makes it challenging to learn from others’ strategies (hence the reason for this blog).  My advice is still specifically tailored to the data requester, but there are some elements that are common to many of my responses, which I share below in the hopes it will be helpful to others.

10 Strategies.  (1) First and foremost, have a clear vision of the data you need, the scale, the date, the extent, the resolution, and other characteristics before you spend time searching.  Also set yourself a limit on how much time you will devote to processing the data before you can use it for analysis.  This will reduce the behavior that I think is similar to “wandering through a grocery store without a clear idea of what you are looking for”.  Walking up and down aisles in a grocery store, you might take something that you really didn’t want or originally intend to pick up, and waste valuable time with it in your project.  But once you’ve thought carefully about your needs and what you will and will not accept, then you are ready to search. 

Something key to keep in mind here is that more data is not always better.  A corollary is that higher resolution data is not always better than low resolution, whether block group vs county, or 3cm UAV imagery vs 1m satellite imagery--indeed, you may not see the "forest for the trees"; your deluge of data may obscure what you really need to be focusing on--patterns, relationships, trends. 

(2)  While you are searching, here is a useful aid to help you decide whether the data will meet your needs.

(3) Start your search with the ArcGIS Living Atlas of the World. In my judgment, the 8,000 + layers, maps, apps, and services represent the single most useful set of curated geospatial resources in formats that are easily ingestible into GIS software, especially the ArcGIS platform.  The easily ingestible is key--one noble goal is to minimize the data search component of your project, so that you can focus on analysis, and then communicating your results.  There are many stories of GIS users throughout the decades spending 90% of the project time manipulating and processing the data, leaving only a small amount of time for analysis, assessment, and evaluation.  If the data you are seeking is not in Living Atlas or not in the format that you desire, then move on to the next steps.

(4) Investigate ArcGIS Online.  The geospatial community has been wonderfully sharing content in ArcGIS Online since the platform launched in 2010.  Thousands of content items are uploaded daily, so there is no shortage of volume, and you can filter on data type, owner name, and other items to narrow your search, as explained here.  For example, I make use of the owner: ___ < owner name> search strategy quite often to find my own content and content from authors and organizations that I respect most.

(5)  Investigate ArcGIS Hub sites.  These have rapidly expanded over the past two years in breadth and depth and are an incredibly useful way of accessing data, especially if you are an ArcGIS user, but even if not.  Hub sites usually offer an array of download and streaming data options.  Starting points include searching on “Your area of interest” and then “GIS data portal” or “ArcGIS Hub”.  As one of hundreds of examples, here is the Boulder County ArcGIS Hub.  There are also useful starting points such as ArcGIS Hub search tools and galleries.

(6)  Visit and investigate several of the selected “top 10” (such as satellite imagery, Landsat, and vector data portals) lists that we have reviewed and compiled for this blog.

(7) If these do not net fruitful results, then dig into portals organized by theme that would cover your topic (such as WRIs on land use and natural resources).

(8) Next, investigate portals organized by location, that would cover at least in part, your study area (such as Ordnance Survey for the UK, and state, province, region, or city (examples here for Oregon, here for a large city of Los Angeles, here for the small city of Oak Hill West Virginia.

(9) Scholarly research.  Because more research is tied to geospatial data than ever before (see our essays here on this topic:  Part 1 and Part 2), check Google scholar, library databases, and other sources of peer-reviewed research, as well as conference proceedings from Esri, AGU, AAG, and other major events, to investigate the sources identified in the research.  Be tenacious: Often the data sources are listed at the end; sometimes the research will be published in a poster or a story map or other form of media; sometimes it may require you to contact the author to dig out the sources.

(10)   Use ChatGPT!   My recent inquiry to ChatGPT about data for eastern Nebraska was fairly useful, even though there were no hyperlinks available, and I am confident it will improve over time:

Results:  Here are a few options for finding geospatial data for Eastern Nebraska:

  1. USGS EarthExplorer : The USGS EarthExplorer website offers a wide range of geospatial data, including aerial imagery, satellite imagery, and topographic maps. You can search for data by location and download it for further analysis.

  2. Nebraska Department of Natural Resources : The Nebraska Department of Natural Resources (NDNR) provides geospatial data related to natural resources in Nebraska. Their website offers datasets such as hydrology, land cover, and geology.

  3. OpenStreetMap : OpenStreetMap is a collaborative mapping project that allows users to contribute and access geospatial data. You can search for specific areas in Eastern Nebraska and download data in various formats.

  4. Nebraska GIS Data Portal : The Nebraska GIS Data Portal is a platform that provides access to geospatial data from different sources. You can search for datasets by location or topic and download them for your specific needs.

This additional note from ChatGPT was also a good reminder:  Remember to review the terms of use and licensing requirements for each data source before using the data for your project.

Words of advice.  Just like there is often no “single best source” for one specific topic on the web, no single “geospatial gold mine” exists that is the end-all site for spatial data.  However, this is actually a good thing, in my opinion.  Why?  It forces the user to think critically about the data sets that user may or may not choose.  As is clear on the Spatial Reserves data blog, choices abound.  Those choices require the user to investigate and evaluate each of them.

The course is available in video form, here:

Part 1:   https://youtu.be/eBEWQRFYQBE?si=YwkLGw7TWUyIgjfO

Part 2:  https://youtu.be/UyG7TEdSv8I?si=UCSflXx16Om-zRhM 

Part 3:  https://youtu.be/JDH8LP5Vy1Y?si=GcaK3cVGEe7I92my 

Part 4:  https://youtu.be/XSCCq-IrYyY?si=ZSRekabrhCbftkVZ 

Feel free to use these resources for your own courses and workshops.  I hope this content is useful and relevant, and I look forward to your questions and comments!

 

--Joseph Kerski

 

About the Author
I believe that spatial thinking can transform education and society through the application of Geographic Information Systems for instruction, research, administration, and policy. I hold 3 degrees in Geography, have served at NOAA, the US Census Bureau, and USGS as a cartographer and geographer, and teach a variety of F2F (Face to Face) (including T3G) and online courses. I have authored a variety of books and textbooks about the environment, STEM, GIS, and education. These include "Interpreting Our World", "Essentials of the Environment", "Tribal GIS", "The GIS Guide to Public Domain Data", "International Perspectives on Teaching and Learning with GIS In Secondary Education", "Spatial Mathematics" and others. I write for 2 blogs, 2 monthly podcasts, and a variety of journals, and have created over 6,500 videos on my Our Earth YouTube channel. Yet, as time passes, the more I realize my own limitations and that this is a lifelong learning endeavor: Thus I actively seek mentors and collaborators.