Flood Activity Page

The Red River Flood

In this activity, you will determine the size of the flooded portion of the Red River Valley in North Dakota and Minnesota. Follow the steps below to do this:

1) Click on the picture to the left - a satellite view of the flood on April 21st, 1997 - to view a larger version of it.

2) In order to analyze the picture, it must be converted to a TIFF or PICT. Software such as GIF converter, Graphic converter or Paint Shop Pro can be used to complete this task.

3) Once the picture has been converted to TIFF or PICT, load NIH Image (or Scion Image) and open the picture.

4) First, NIH image must be calibrated. To do this, choose the Line Tool (diagonal dashed line with an arrow under it).

5) Draw a line from Grand Forks to the US-Canadian border. Grand Forks is located at the intersection of the Red River and Red Lake River (the river in Minnesota).

6) Go to Analyze, then Set Scale. The length that corresponds with the line you drew (in number of pixels) is displayed in "Measured Distance". The "Known Distance" category is where you enter the actual distance from Grand Forks to the border - 73 miles. Make sure you choose the correct units for the distance.

7) Now you are ready to make some measurements. Before you begin, click on the maginfying glass, then click inside the image on the flooded part of the Red River. It should look similar to the image to the left. This will allow for more accurate measurements.

8) Using the Line Tool, draw the longest segment you can across the flooded Red River. Once the segment is drawn, choose Analyze, then Measure, and release the mouse button. Again, click on Analyze, drag down to Show Results, and release the mouse button. A Results window will appear with your answer in the column labeled Length.

9) Repeat this task until you are confident you have found the widest measurement of the Red River. Record that information on the chart.

10) NIH Image has 4 tools used for selecting regions (areas) for study. They are the first four tools in the right column of the Tools window: They measure (from top to bottom) rectangular areas, oval or circular areas, polygonal areas, and any freehand shape.

11) Approximate the flooded area using each of the four tools as accurately as possible. After using each tool, choose Measure then Show Results from the Analyze menu. Record your results on the chart under April 21st.

12) Which measurement do you think is the most accurate? The least accurate? Why?

If time allows, repeat the activity for the following images, recording the information on the chart.