Parks in this Network
Repeat Photography in National Parks of Southwest Alaska
About This Project
How has this glacier changed in the last 100 years? What did this mountain look like before its last eruption? How are these trees responding to warmer, longer summers? These are all questions that can be answered, at least in part, by comparing photographs taken over time.
This website houses the repeat photography database for Southwest Alaska Inventory and Monitoring Network. Our goal is to provide a searchable, interactive platform to explore, use, and contribute to this growing database.
Guidelines for taking repeat photographs - Download Guidelines
Prior to going into the field...
- PRINT : Print the photos you would like to repeat.
- MARK : Using a ruler, draw a vertical line along the photograph's exact centerline. Then draw at least one vertical orientation line on each side of the centerline that passes through background and foreground features that can be identified in the field (e.g., a distant summit and a nearby boulder).
- LOCATE : Mark the location of the photographs in your handheld GPS unit.
- DESCRIBE : Write down any information that accompanies the original photo. This may help you locate and retake a new one.
- GATHER : Necessary equipment, such as the printed photos with orientation, camera, extra batteries and storage, tripod, GPS unit, notepad, and compass.
- CENTER : Once in the vicinity of the photo-point in the field, identify foreground & background centerline features in the landscape and adjust your position left & right so that these features are exactly in line. Accomplish this before adjusting your position forward & backward.
- DISTANCE : First identify the features marked along orientation lines in the actual landscape. Then begin the process of moving forward or backward such that these features (AND the photo centerline) are oriented in the same way as in the original photograph. For close-up photography, adjustment of camera height on the tripod will be necessary; in such cases, horizontal orientation lines will facilitate precise duplication of original camera height.
- ADJUST : Use a tripod if you can, set ISO at 100, use an F-stop setting of f/8.0, and use a minimum shutter speed of 1/100. High resolution settings are best. If visibility is low and waiting is an option, try another day. If you only have one shot, a foggy photograph is better than none.
- DESCRIBE : Take notes of the landscape or feature as well as of your photo shoot. Information noted may include your photo file names, the site ID, the geographic location (nearest landmark), GPS location (latitude and longitude), the accuracy of your GPS unit, error of GPS unit, elevation, camera height, camera type, vegetation cover, and other general notes.
Back in the connected world...
- BROWSE the 'Contribute Photos' tab and click on the appropriate Flickr group link..
- UPLOAD and SHAREyour photo(s) to your own Flickr account and add them to the appropriate repeat photography Flickr group.
Photos & Monitoring
Holgate Glacier in Kenai Fjords National Park is among the 90% of glaciers in Alaska that are retreating. NPS photo
Monitoring in Southwest Alaska
Photograph monitoring of Landscape Change in Southwest Alaska
Photo galleries of SWAN Scientists in the field
Historical photographs combined with archived data supplement other sampling methods and help us understand change over time. Repeat photography also helps interpret the data collected by other means..
Climate refers to the long-term patterns in weather of a given area. Today, scientists record temperature, precipitation, snow depth, and other short-term parameters to track long-term patterns.Since installing the weather stations, we've learned that the temperature routinely reaches 70F on the Harding Icefield during summer months. Winds of over 100 miles per hour have been recorded by several stations during winter storms. Maintaining the stations is an ongoing effort and involves annual visits to each remote location.
In many cases, photos are the first records of a glacier's physical characteristics and provide valuable information about the terminus, or face, of the glacier as well as its height and area of coverage.
Since installing the weather stations, we've learned that the temperature routinely reaches 70F on the Harding Icefield during summer months. Winds of over 100 miles per hour have been recorded by several stations during winter storms. Maintaining the stations is an ongoing effort and involves annual visits to each remote location.
See the shrub expansion in Lake Clark at the Chilligan River
Seasonal events, such as the green up of forests in spring or the onset of lake ice in winter, are cues for many other natural processes like migration and mating. In addition, they can help scientists determine long-term trends in seasons and the effects of climate change.
Large, landscape-level changes in vegetation types serve as both a driver of and response to changes in the environment. Repeat aerial photography is the primary tool used by scientists to categorize landscapes (ie. figure out which areas are forests and which ones are meadows) and to track changes in the national parks of southwest Alaska. When combined with photography and species observation on the ground, the aerial images form a detailed record of the changing landscape. While some changes in landscapes are correlated with climate change, others are due to fire, volcanic eruptions or earthquakes.
See evidence of volcanic activity at Half Cone.
Coastlines in southwest Alaska are dynamic and constantly changing. Changes to coastlines are often caused by storm-driven waves, hide tides, currents, runoff, landslides, and earthquakes. These changes alter the vegetation, animal communities and shore-type and have implications for humans and land management. Scientists with the National Park Service are monitoring coastal change using repeat aerial photography and satellite imagery. The photographs are then compared to surveys conducted along the shore to determine change.