Alaska TRP Map Tips
https://sites.google.com/view/tab-inventories/2022/alaska-trp-map-tips
Quick ways to get useful information from maps
Let's take the easiest approaches to common questions - we can use different mapping platforms for the answers but let's start each one with the simplest way - and the platform that is most available to everyone.
Activity #1
How do you find the location of a site using a map?
This might come up because you have an incomplete address in your site inventory, or you have GPS coordinates but no street address, or vice versa. Also, any time someone gives you an address or GPS coordinates it is good to check it by searching for it on a map; a common problem is that a company's headquarters may be listed as an address for a facility, rather than the actual property you are interested in. You can also check to make sure that it is the right location by looking at the satellite and Street View imagery; if the imagery shows you something different than you are expecting (like a view of a parking lot when you expected a building) the address or lat/long might need to be corrected.
The easiest thing to do is to go to Google Maps and search for the location and see what it is. You can use Satellite View and Street View to do a quick check (but see Activity #2 about checking the imagery date). You can get an amazing amount of useful information off of a simple Google Map.
Go to https://maps.google.com/ and follow the instructions in the slides below to do the first activity.
Here is the link to a Google Map with directions from the airport to the ANTHC campus: https://goo.gl/maps/J3kUX2kzid6jcptg8
Activity #1
Search for "Alaska Native Tribal Health Consortium." This will give you a view of the entire ANTHC medical complex.
Find the corner of Ambassador Drive and Elmore Drive, and locate the building that is labeled "Alaska Native Tribal Health Consortium."
Switch to Satellite View and zoom in. When you zoom in far enough you will go to Street View. Swivel around and look at the building.
Now let's answer a few questions:
What is the street address of the building?
What is the lat/long?
What is the date of the satellite imagery?
What is the date of the Street View imagery?
How do you get from the airport to the ANTHC campus?
Activity #2
Let's take a deeper dive into the GPS coordinates
What format should lat/long be in, and what do you do if you have multiple different formats for lat/long in your inventory list? The format matters a lot if you are going to map your sites, since the mapping platforms (ArcGIS, Google Earth Pro, etc.) require a specific format. And having everything in the same format is important if you are going to sort a spreadsheet and look for sites that are geographically close to each other. But most importantly for our Brownfields Inventory, we need to have the latitude and longitude coordinates in the correct format for ACRES and BiT.
You might see any of these formats:
Decimal degrees (DD): 61.182371, -149.806820
Degrees, minutes, and seconds (DMS): 61°10'55.2"N, 149°48'24.3"W
Degrees and decimal minutes (DMM): 61 10.9199 N, 149 48.4054 W
BiT and ACRES use Decimal degrees format. This is also the best format for Google Earth and ArcGIS, so you should convert all your GPS data into this format. You can see a screenshot from BiT on the right.
Click Here for ACRES Quick Reference Guide information about GPS coordinates.
Make sure you list your latitude coordinates before your longitude coordinates because the order matters.
It is important when you when you are using the Decimal degree format that you make sure to include the minus signs in the appropriate places, since whether the latitude or longitude is + or - determines which hemisphere you are in; take a look at the map on the left for an example (it is interactive so you can zoom in and out).
If you are in Alaska 61.182371, -149.806820
If you are in Russia 61.182371, 149.806820
If you are in the ocean off Australia -61.182371, 149.806820
If you are in the ocean off South America -61.182371, -149.806820
A real quick way to check for problems in your GPS coordinates is to sort the column in your spreadsheet from A to Z and from Z to A and make sure you don't have positive and negative values in the wrong places and that you have six values for the decimal places (if you have fewer values it will be inaccurate). This will also help you check to see if some of the values are formatted differently.
You can also import your spreadsheet into a Google My Maps or Google Earth and see if any points are in the wrong hemisphere.
To convert between different formats, the Polar Geospatial Center at the University of Minnesota has an especially useful set of tools for work in Alaska
https://www.pgc.umn.edu/apps/convert/
EPA ACRES recommends using this tool for conversions
https://www.fcc.gov/media/radio/dms-decimal
Activity #2
Go to the Polar Geospatial Center's online converter and convert 61°10'55.2"N, 149°48'24.3"W to Decimal degree format
Activity #3
How do you figure out the approximate acreage of your site?
For this we can use several different mapping platforms, for example Google My Maps, Google Earth Pro, ArcGIS online, or the EPA tools that are based on ArcGIS online. If you do an estimate using one of these platforms you should specify which one you used and that the estimate is based on satellite imagery rather than on-the-ground measurements.
The easiest platform to use for this is Google My Maps, which can be accessed with a Google Account. If you cannot use a Google Account because of work restrictions, you can either use Google Earth Pro (which requires you to download it to your computer), ESRI ArcGIS (which requires you to pay for access), or the EPA EnviroAtlas, which is free to use and is based on ArcGIS Online.
We will use the EnviroAtlas for this activity since everyone should be able to access it on their work laptops. If you are interested in learning how to use Google My Maps click here, and for Google Earth Pro click here.
Go to the EPA EnviroAtlas Click Here
Using the measurement tool in EnviroAtlas to measure the area around the Alaska Native Medical Center gives an approximation of 1.3 sq kilometers, which is about 320 acres (this is a quick demo, you can be more careful defining the boundaries of the property of interest).
Be careful not to report values that are more precise than you can measure. The accuracy of satellite imagery varies depending upon the source of the imagery, and the source of the imagery varies not only in different places, but at different zoom levels. In locations with the best imagery, such as a city, the accuracy is often around 1 meter, which is similar to what you would get from using a GPS to determine the location. In remote areas, especially in remote polar regions, the imagery (and GPS coordinates) may be much less accurate. So it is better to report 320 acres instead of 321.237 acres.
Activity #3
Go to the EPA EnviroAtlas Click Here
Open the EnviroAtlas Interactive Map and use the slides below for this activity.
Search for a location you are interested in measuring
Zoom to the location so that you can easily see the area you wish to measure
Click Mapping Tool>Draw and Measure and select the polygon tool
Outline the area of interest
Print a copy of your image
Calculate the acreage (you can just do a Google search for Kilometers = Acres)
Activity #4
How do you access historic imagery of your site?
The easiest way to do this is to use Google Earth Pro's time slider, or Google Earth Engine's Timelapse.
Google Earth Engine access Landsat satellite imagery from 1984 to 2020 to create visualizations of change over time. Because this is all Landsat imagery, you can't zoom in very closely; however, if you are interested in seeing how an area has changed over time it is a good tool for communicating with the public. For example, here is a visualization of glacial retreat in Alaska CLICK HERE You can see how Anchorage has grown in this view CLICK HERE
To look at a particular site it is move useful to call up imagery in Google Earth Pro using the time slider, which includes aerial imagery where available. The quality of the imagery will differ, so try different dates and zoom levels to find the best views. One handy trick is to find imagery from different times of the year - for example, winter imagery may give you a better view of the ground in areas where the trees shed their leaves.
Activity #4
Download Google Earth Pro (it is free) Click Here
Open Google Earth Pro on your laptop
Search for Alaska Native Health Consortium
Open the time slider and examine imagery from different dates
Drop pins and draw polygons to mark areas for comparison
2003
Look at the area around the pond and compare to the newer imagery
2021
You can clearly see where new buildings and parking lots have been added
Activity #5
How do you find the slope and drainage for your site?
There are two easy ways to get elevation profiles, one uses Google Earth Pro and the other can be done on the ArcGIS platform accessed through EnviroAtlas. Instructions can be found in the slide presentation below. Be aware that elevations are measured at the surface, so you won't be able to see the depth of a waterbody, and if there are buildings, bridges or other solid objects you may see some odd bumps in the profile.
Google Earth Pro: Begin by drawing a line between the points of interest, then clicking Edit>Show Elevation Profile
EPA EnviroAtlas (ArcGIS platform): You can use the Elevation Tool. Unfortunately the Raindrop and Watershed tools are not available for Alaska.
Activity #5
Search for your site of interest.
Draw a line between two locations and get the elevation profile; for example, you might draw a line from a Brownfield site to a nearby lake to see what the drainage looks like.