Lesson 1. Use Google Earth time series images to explore flood impacts


Understand Disturbance With Data - Flooding and Erosion - Earth analytics course module

Welcome to the first lesson in the Understand Disturbance With Data - Flooding and Erosion module. This module uses time series data to explore the impacts of a flood. Learn how to use Google Earth imagery, NOAA precipitation data and USGS stream flow data to explore the 2013 Colorado floods.

In this lesson, you will learn to use the time series function in Google Earth to explore changes in the landscape associated with the 2013 Colorado floods.

Learning objectives

At the end of this activity, you will be able to:

  • Use the timeline function in Google Earth to view time series imagery data
  • Identify and describe a driver and an impact of a flood event

What you need

You will need to download and install Google Earth on your computer and then download the .kml file below.

Get Google Earth

Download .kmz file - Locations of Change

About the 2013 CO floods

In early September 2013, a slow moving cold air front moved through Colorado intersecting with a warm, humid air front. The clash between the cold and warm airs fronts yielded heavy rain. This rain, combined with a drought conditions, Colorado soil conditions and other factors yielded devastating flooding across the Front Range in Colorado, USA.

North St Vrain before and after 2013 flood.
The St. Vrain River in Boulder County, CO after (left) and before (right) the 2013 flooding event. Source: Boulder County via KRCC.

Use imagery to detect change

Spatially located (georeferenced) imagery, collected using satellites and airplanes provides a powerful visual record of landscape changes. Google Earth, has a time series feature that allows you to look at imagery of the earth, across time in certain areas of the Earth.

We will use this feature to look at the landscape in Boulder, Colorado both before and after the floods.

How to view time series imagery in Google Earth

  • Open Google Earth
  • Double click on the .kmz file that you downloaded above. It should open in Google Earth.

Tip: If the .kmz file doesn’t automatically open when you double click on it, try to Open Google Earth, go to File –> Open in Google Earth. Finally, navigate to the location of your downloaded file (~Documents/data/co-flood/locations) and open it.

  • Once you have the .kmz file open, notice it is listed in the Temporary Places section of the places window. It should automatically zoom you into to an area in North Boulder, Colorado. If it doesn’t double click on the text Locations of Significant Damage.
  • Click on the show historical imagery button in Google Earth
google earth time series feature.
The `show historical imagery` button allows you to turn on and slide through imagery from various points in time within Google Earth. It is the button outlined in pink in the above imaged.
  • When you click on the show historical imagery, a slider will appear in the upper LEFT hand corner of your window. Scroll back and forth through time to get used to the slider
  • Finally, double click on one of the thumbtacks from Locations of Significant Damage. Scroll to 10/2012 and then to 10/2013. Do you see any differences?
  • Check out the other thumbtack. What differences do you see?

Activity: What changes do you see?

As a group, discuss the following questions. Record your answers in the Google Document provided.

  • What differences do you see between 2012 and 2013?
    • For each difference: What do you think caused that difference?
    • For each difference: How can you quantitatively record the difference?
  • For each CAUSE listed above, could you somehow quantitatively record the “size” or impact of the cause?
  • Was the cause - caused by something else (i.e. did something else DRIVE the cause)?

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