Space-time analyses for forecasting future incident occurrence: a case study from Yosemite National Park using the presence and background learning algorithm

This follow up paper to the Yosemite Search and Rescue Incident Georeferencing Study has been published in the International Journal of Geographical Information Science. Many thanks to my colleagues and all of the volunteers who have helped support this project! 

Abstract

To address a spatiotemporal challenge such as incident prevention, we need information about the time and place where incidents have occurred in the past. Using geographic coordinates of previous incidents in coincidence with spatial layers corresponding to environmental variables, we can produce probability maps in geographic and temporal space. Here, we evaluate spatial statistic and machine learning approaches to answer an important space-time question: where and when are wildland search and rescue (WiSAR) incidents most likely to occur within Yosemite National Park (YNP)? We produced a monthly probability map for the year 2011 based on the presence and background learning (PBL) algorithm that successfully forecasts the most likely areas of WiSAR incident occurrence based on environmental variables (distance to anthropogenic and natural features, vegetation, elevation, and slope) and the overlap with historic incidents from 2001 to 2010. This will allow decision-makers to spatially allocate resources where and when incidents are most likely to occur. In the process, we not only answered questions related to a real-world problem but also used novel space-time analyses that give us insight into machine learning principles. The GIScience findings from this applied research have major implications for best practices in future space-time research in the fields of epidemiology and ecological niche modeling.

Download the Paper

The IJGIS will provide free access for the first 50 downloads. Since the GIScience community already subscribes to this publication, I thought I would open this up to the Search and Rescue GIS Community: Download Here

Conclusion for Search and Rescue GIS

• Both where and when an incident occurs is important.
• SAR incidents occur where visitation is likely highest (obvious) - but visitor use activity is also not well mapped in recreational areas like Yosemite. Therefore it is difficult to map risk factors independently. 
• If you don't map where an incident has occurred how will anyone else ever learn from the experience? 
• Maps are an extremely compelling tool for telling a story about a place and capturing institutional knowledge.
• GIS is an under utilized tool in Search and Rescue and this research is just beginning to scratch the surface

Acknowledgments

This research initiative is supported by the National Science Foundation (grant nos. BDI-0742986 and SBE-1031914). I would like to thank Yosemite Search and Rescue, Yosemite Volunteers-In-Parks, and the Yosemite National Park Division of Resource Management and Science for research permissions (OMB#1024-0236) and constructive suggestions. Special thanks to my Dissertation Commitee: Dr. Samuel Traina, Dr. Ruth Mostern, Dr. Yihsu Chen, labmates Wenkai Li and Otto Alvarez, co-authors Yu Liu and John Wieczorek, and especially my PhD advisor Dr. Quinghua Guo. Thank you to volunteers Diane and Greg Ambrose and Sarah Nurit for all of the Georeferencing and clerical work!

If we want to collaborate in follow up research, contact the Spatial Analysis & Research Center at University of California Merced (SpARC). 

This map below is just a point layer of cumulative incidents. Stay tuned for time-enabled maps and maps that filter by incident type.

A Remedy for Your Basemap Blues

Problem: Slow Maps

So you are on a search and rescue mission using ArcGIS Desktop and while panning and zooming around the map, you are continuously waiting for basemaps to "re-draw". You can't guarantee an internet connection so you want to utilize your local data.

 Solution: Basemap Layers

Some nerdy GIS talk from the help documentation: "Basemap layers are a kind of map layer that provides a framework onto which you display your dynamic operational information. Basemap display performance is very fast. Since basemap layers are relatively static and do not change frequently, their display can be computed once and reused many times. The first time you visit an area at a particular map scale, basemap layer display is computed. The display is recalled on return visits to that area and map scale."

It is FAST! So let's get started.

Step one - Cartography

So this step will vary based on what you use as basemaps for your area. A long time ago Liz Sarow from Esri showed me how to make a nice hill-shaded topo from publicly available data. For California here are some resources:

1) Topos available as Digital Raster Graphics

2) 30m Digital Elevation Models available as Images (or these can be made with any DEM using the Hillshade tool)

The next trick is to add these to your map and style appropriately. I personally use a hillshade-on-topo "sandwich" - but I set hillshade properties as transparency of ~55% and Resample to bilinear interpolation.

Map sandwich!

Step two - Add a New Basemap Layer

Right-click the data frame name in the table of contents and click New Basemap Layer.

Step three - Select the Layers 

Select the layers that will comprise your basemap and drag them into the basemap layer.Now you have a topo map that also highlights the terrain in your area - more importantly we can now pan and zoom around the map without waiting for redraw.

Please see the help document for more information. You can download my example as a tile package here and the try the steps above.

Other recommendations

• Create these and store them for your areas of operational responsibility so they are ready to go ahead of time. These can be stored locally and remotely using Dropbox or ArcGIS Online.
• Do not add any vector layers to your map that you plan on tracing for editing or clicking for attributes - this removes data access. No big deal if you do, just remember to pull the layers back out of the Basemap layer when you need them.
• Whenever possible - use ArcGIS Online basemaps, they render quickly and feature more often updated content than your old topo and trail maps. See the World Topo Community Basemap and Open Streetmap 
• RTFM Read the Free Manual: there are lots of other tips & tricks you can use in the ArcGIS Help documentation. Also - join our discussion group and ask the SARGIS geeks yourself! 

#RimFire in Yosemite continues to burn - highlighted on our US Wildfire Map

The Rim Fire continues to impact nearby communities, Yosemite National Park, and the San Francisco Power Utilities Commission. You can use this map to track updates on the fire and also see some of our maps that are available through the Esri Disaster Response Program website. For continuous updates from firefighters themselves, go to the CA-STF-Rim Fire forum thread on Wildlanfire.com. 

View Larger Map

Yosemite Search in 2008

11-10 to 11-12-08 - Major Search for Missing Backpacker
A solo backpacker became stranded for twelve days in a remote area of the Yosemite high country, snowed in by a signifcant winter storm. With a search area of 400 square miles, YOSAR ground, air, and investigative personnel tried to locate the starving backpacker. For more on the full story go to http://yosemiteblog.com/2009/08/24/survive-lost-in-the-snow/

Video provided by Tom Patterson, Esri Public Safety Team. www.mapsar.net