suggested grade levels: 7-12
view Idaho achievement standards for this lesson
1. Students will be exposed to the Digital Atlas of Idaho.
2. Students will be able to calculate streamflow and precipitation when given the required information.
3. Students will understand the relationship between precipitation and streamflow.
Expose your students to the Digital Atlas of Idaho.
To get there: Click on Atlas Home, Climatology, then on General Climate.
Have your students read through the pages to get an understanding of the general climate section. Encourage them to click on the links so they can observe the pictures.
Do the following as a demonstration/discussion
1. Tell the class that the average flow of a stream in a particular drainage
is 410 cubic feet per second. How could we determine the annual flow of this
Multiply the CFS by the number of seconds in a year.
(410 ft3/s)*(60 sec/min)*(60 min/hr)*(24 hr/day) * (365 day/yr) = 12,929,760,000 ft3/yr
2. Tell the class that the average rainfall in this watershed was 29.315 inches.
The area of this watershed is 456 square miles. How can we convert this to cubic
feet of rainfall?
Area = 456 mi2 conversion: (456 mi2)*(27,878,400 ft2/mi2) = 12,712,550,400 ft2
Precip Volume = (29.32 in)*(1ft/12 in)*(12,712,550,400 ft2) = 31,060,998,144 ft3/yr
3. Ask the class what is the relationship between precipitation and streamflow.
12,929,760,000 / 31,060,998,144 = .42
This means that 42 percent of the rain that fell ended up in the stream.
What happened to the other 58 percent?
(The other 58 percent evaporated, got absorbed in plant matter, or ended up in groundwater before it got to the stream)
Ask the students if they think it is always 42 percent. What factors could change this percentage?
These are links to access the handouts and printable materials.
Hydrology: Hydrology Topics