# Stream Characteristics Lab

## Summary

In this lab students look at rivers using Google Earth, estimate the sinuosity of the river and predict the relationship between the sinuosity and the river's gradient. Students then use a spreadsheet to calculate siniuosity and gradient and graph the results. They use the graph to predict the sinuosity of another river, and make measurements that allow them to test their hypothesis.

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## Learning Goals

Students are expected to calculate and graph the relationship between stream gradient and sinuosity. This exercise helps to build the following skills:
• graph interpretation
• data analysis
• hypothesis testing

## Context for Use

This activity is appropriate for an introductory level geoscience class. It requires access to Google Earth and Excel spreadsheets. It may be placed anywhere in a unit on rivers.

## Description and Teaching Materials

Teaching Materials

The files you may need are:
Description
Part 1:
Students look at 4 rivers using Google Earth and describe each river as being fairly straight, having some meanders, or having many meanders. They then predict the relationship between the number of meanders and the gradient of the river.
Part 2:
For each of the rivers viewed in part 1, students use Google Earth to calculate the distance of the river between two given elevations. They use the spreadsheet to calculate the gradient and the sinuosity of each river. They make a graph of Gradient vs. Sinuosity, and they use the graph to describe the relationship.
Part 3:
Students use the graph to predict the sinuosity of another river. They are given a location on the Santa Ynez River and they use Google Earth to determine change in elevation and distance, from which they calculate the gradient. They use the graph to predict the sinuosity of the river.
Part 4:
Students then use Google Earth to look at the river and they measure straight distance and river distance. From these measurements they determine the sinuosity, finding out whether their prediction was correct. The last part of the exercise involves looking at the Mexican Hat. From Google Earth they can see that the San Juan River has many meanders (this is an area of the San Juan River known as the Goosenecks), but it is very steep (rapids can be seen). They must try to explain why it doesn't fit the relationship established by the graph. (The San Juan is a rejuvenated river)

## Teaching Notes and Tips

If students have never used Google Earth, you will need to demonstrate its use and give students plenty of time to play with it, for they will insist upon finding their houses.

This exercise assumes that students have had experience creating graphs with Excel, but have not had experience inserting formulas into Excel, and so the instructions may need modification depending upon the spreadsheet expertise of the students. See references below for some links to Excel tutorials.

A note on Part 5 in Description above:
The last question about the Grand Canyon is likely to stump students who have not been introduced to the idea of rejuvenated streams. That is not necessarily a bad thing, for it provides a nice opportunity to initiate a discussion about landscape uplift and stream rejuvenation.