Lab for Lens: Wildfire tracking

Katie Tyler

May 23, 2024

Table of contents

Welcome to our new Labs for Lens series!

The purpose of this series is to provide you with additional ways to become an expert user of Lens, in just about 30 minute increments. Each lab will walk you through an example use case in Lens with some specific learning goals. There will be a video for you to follow along as well as some simple written instructions. For this first lab, we’ll be using Lens to investigate a wildfire.

Learning Goals

At the end of this lab you will know how to:

Upload a property to Lens
Explore the Lens Layers Library and add new datasets to your portfolios
Use the Analysis tool in Lens
Create notes and ultimately a report to tell a story about a disturbance on the land

Scenario

For this lab, imagine you are a new Natural Resource Manager for Sierra National Forest. You know there was a wildfire - Ferguson Fire - back in 2018. And you want to get a better sense of exactly when this fire occurred, the amount of damage, and the extent to which there has been any recovery in the years since. We can use Lens to answer all of these questions!

Instructions

Follow along with this video to complete the lab. Simple written instructions are also provided below if that suits your learning style better. The video can still help if you find yourself stuck on how exactly to complete a specific step. Be sure to take the quiz at the end of the page to test your knowledge when you’re done!

1. Add your property

Add a new portfolio from the Lens homepage.
Select ‘Draw on the map.’
In the map’s search bar, search ‘Hite Cove, California’. Zoom out until you can see both Brown Peak and Trumbull Peak on the map. Then, draw a rectangle on the map that encompasses the road going through Incline and El Portal (see image below for guidance). There is no need to get this exact as the fire perimeter extends beyond this area.
Name the portfolio and property and click ‘Review Datasets.’
In the pop up window we can browse different datasets available in Lens. Which layers may be most useful to help us investigate the impacts of the wildfire?
Browse the possible layers and click on a layer’s card to see more details. Find and add the following layers: Landcover from Impact Observatory and Burn Index from ESA Sentinel-2A/B.‍
Exit the pop-up and click confirm to kick off processing.
The property will begin processing - it should typically only take about 7 minutes before you can proceed with the lab, although in some cases it may take longer. You should receive an email when your property is finished processing.

2. Explore the property

Lens defaults to showing you the most recent high resolution true-color image. Use your left and right arrow keys to cursor through the available truecolor images. Do you notice one image when the effects of the wildfire are most pronounced?
Use compare mode to view the 2016 and 2018 NAIP images and see the changes on the land resulting from the fire.
Leave a note capturing your observations on the 2016 and 2018 images.

3. Explore vegetation trends

Now that we’ve explored truecolor imagery to get a better understanding of how this property has changed over recent years, let’s look at vegetation trends. We can use the Analysis tool in Lens to do exactly this!
Open the Analysis pane in Lens. Select the entire property, make sure the dataset for analysis is Vegetation (S2), chart type is Average Value, and set the Time range to All Time. Click Analyze and wait for the chart to load.
What do you notice about the vegetation chart? Is there a sharp decline in vegetation possibly as a result of the fire? Click on a point from before the sharp drop and then shift-click on a point after the sharp drop to view the vegetation data in compare mode before and during/after the fire.
Click ‘Add Note’ and type your observations from the vegetation chart and layers. Then click ‘Create’ to save your observations as a note.

4. Investigate Burn Index

To further bolster our observations on the timing of the fire made with vegetation data, we can also look at burn index data. This can be useful data to confirm that a drop in vegetation was from a fire, rather than a logging event or other disturbance. We’ll use Analysis again to look at past trends.
Open the Analysis pane in Lens. Select the entire property, make sure the dataset for analysis is Burn Index (S2), chart type is Average Value, and set the Time range to All Time. Click Analyze and wait for the chart to load.
What do you notice about the chart? Is there a spike in the burn index around the same time as when the vegetation declined? Click on a point from before the spike and then shift-click on a point near the top of the spike to view the burn index data in compare mode before and during/after the fire.
Look at the graph to see when the burn index first started rising. Can you make any conclusions about the timing of the start of the fire in this area?
Click on the trapezoid 3-D mode button on the right-hand side of the screen to view the land in 3-D and get a better sense of how the fire interacted with the topography of the area.
Click ‘Add Note’ and type your observations from the burn index chart and layers. Then click ‘Create’ to save your observations as a note.

5. Investigate landcover changes

Now that we’ve investigated when the fire began, let’s assess some of the impacts of the fire. One way we can assess changes on the land as a result of the wildfire is using landcover data. We’ll use Impact Observatory landcover data as it provides us with annual data back to 2017.
Open the Analysis pane in Lens. Select the entire property, make sure the dataset for analysis is Landcover (Impact Observatory), chart type is Area by Category, and set the Time range to All. Click Analyze and wait for the chart to load.
Click on 2017 and shift-click on 2019 to compare landcover before and after the fire. About how much forest loss does this data set estimate? Can you see any evidence of revegetation since 2019 with this data?
Click ‘Add Note’ and type your observations, then click ‘Create’ to save your observations as a note.

6. Check built areas for damage

Looking at the Impact Observatory LAndcover data, we can see that there are some built areas here in red. Let’s zoom in on some of these and switch to viewing high resolution truecolor imagery to see if the fire caused any damage in these areas. You should see four red areas - let’s zoom in on the middle two.
Switch your layer and date dropdowns so you are viewing high resolution truecolor imagery from 2018.
What do you see? Can you see a clear divide between burned and non-burned areas? Was anything acting as a fire break?
Add a note outlining the area you’re viewing and your observations.

7. Look for evidence of revegetation

Now switch to compare mode so that you are viewing high-resolution NAIP true-color imagery from 2018 and 2022. Compare the images and investigate the property for areas that show strong evidence of revegetation since the fire.
Add a note outlining the area you’re viewing and your observations.

Final step. Create a report!

By now, we’ve created 6 notes that tell a story of the timing of the fire, some of the impacts, and some of the recovery since then. Let’s package this all up into a report.
At the top of the notes pane, click the page icon to create a report.
If you have Lens Plus, use our new Smart Summary feature to automatically generate a summary for the report based on all of your notes.
Scroll through your report and make any edits you see fit to page titles, map zoom, or scale bar visibility. Save your report and/or export to pdf and you have successfully finished your first Lab for Lens!

Great job on completing your wildfire lab in Lens! Take a moment to think through the quiz questions below to test your new-found Lens expertise! To see if you got your answers right, head to the bottom and click on the respective questions to reveal their answer.

Quiz

What month was there the first sign of wildfire activity?
- A. June
- B. July
- C. August
- D. September
Which data layers might NOT be the most useful in assessing the impact of a wildfire?
- A. Vegetation
- B. Burn Index
- C. Surface Water
- D. Landcover
What acted as a fire break in this instance?
- A. The road
- B. The stream
- C. A trail
- D. Nothing
True or false: You need a geospatial file (shapefile, kmz, geojson, etc.) to upload a property to Lens.
- True
- False

Answers

Scroll over and click each number to reveal the correct answer.

1. Question 1 answer.

2. Question 2 answer.

3. Question 3 answer.

4. Question 4 answer.

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Congratulations again on completing your first Lab. Please reach out to us to let us know what else you’d like to learn about Lens, and happy monitoring!