Changes along Fountain Creek, Colorado (1989-2006)

William Ouimet
University of Connecticut
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This assignment examines a rapidly changing alluvial river in Colorado. Students produce a map depicting these changes through the use of repeat air photos and then quantify the rates of change through time. Along the way, students learn about the patterns of erosion and deposition associated with meander bends, the role that bank stability plays (both natural and man-made), and the influence of large floods.

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Intermediate to upper level course for Geology, Geography or Environmental Science majors. It could also be an assignment within an applied GIS course (e.g., GIS for the Geosciences).

Skills and concepts that students must have mastered

Ideally students will have experience with rivers and meander bends, but this assignments also serves as a comprehensive introduction.

A principal component of the assignment is an analysis of repeat air photos, so a general understanding of air photos and/or satellite imagery is needed, as well as recognizing features such as rivers, roads, lines of trees. Most students have this basic knowledge, but what needs to be emphasized are aspects such as scale and image resolution.

Students are asked to produce a map requiring the use of trace paper/Mylar, or software such as ArcGIS, Adobe Photoshop or Illustrator, or Paint. Since this assignment may follow previous assignments introducing ArcGIS software and techniques, detailed instructions for the new and additional skills needed for doing this assignment in ArcGIS are provided.

How the activity is situated in the course

Some of this is included above. It can stand-alone, but also works well after a Google Earth exercise providing the basic skills of air photo analysis and feature/landform recognition, and a GIS introduction if GIS will be used.

This is an assignment/project designed to be introduced during lab and continued for homework. The technical aspects of the assignment require class/lab time.

In an earth surface process course, this assignment is designed to take place during the river, or fluvial, part of the semester. It also usually comes after a discussion/lecture/exercise on flood frequency, as there is USGS gaging station just upstream of the study site that may be useful in the analysis.


Content/concepts goals for this activity

Air Photo Analysis
Making a Map
Alluvial River Behavior and Meander Bends
* Patterns of erosion and deposition
* Point bars
* Cut-banks
* Bank stability (natural and man-made)
* The influence of large floods
* River avulsion

Higher order thinking skills goals for this activity

Analysis of data
Identifying and quantifying rates of change
Formulation of hypotheses and methodology
Synthesis of ideas and concepts

Other skills goals for this activity

Appreciating rates of landscape change
Emphasizing the use of historical air photos
Applying GIS techniques in earth surface processes

Description of the activity/assignment

In this assignment students receive six air photos of a 4 km stretch of Fountain Creek in El Paso Country, Colorado (38.7 N, 104.715 W) taken between 1989 and 2006 and are asked to evaluate and discuss how Fountain Creek has changed through the years. The main nuts and bolts of the assignment are an analysis of these repeat air photos and production of a map that depicts how the course of the river (or its cut-banks, point bars and bank-to-bank width) changes through time. To make this map, students can use trace paper/Mylar, or software such as ArcGIS or Adobe Photoshop or Illustrator, but whatever their method they use they need to be able to establish a scale allowing them to measure and calculate rates of change. What change to quantify is purposely left open ended - students typically focus on measuring rates of cut-bank erosion, point bar migration, bank-to-bank width changes, channel length or sinuosity variation over the prescribed study area - and is usually linked directly to what they decide to map, such as the course of the river or the extent of the 'active' channel. After producing their map and making measurements, the final part of the assignment is synthesis. In the final questions, students are asked to summarize and describe in words what's happening to the channel through time, with reference to their map and calculations, and to consider the environmental conditions that are driving the changes observed.

Determining whether students have met the goals

The assignment consists of the map, calculations and summary discussion.
-The map is evaluated based on it quality, accuracy and completeness (including essential map elements such as legend and scale).
-The measurements and calculations are evaluated based on their accuracy and presentation (plots, tables, etc.).
-The summary discussion and final questions are evaluated based the whether they synthesize the ideas and concepts associated with alluvial river behavior and meander bends with what they see and present in their map and how they put words to what they measure in terms of change. 

More information about assessment tools and techniques.

Teaching materials and tips

Other Materials

Supporting references/URLs

Website for USGS Fountain Creek Gage 5 miles upstream of the study site (no significant tributaries in between)