Daily Objectives

Department of Earth Science |Northeastern Illinois University

INTRODUCTION TO EARTH SCIENCE
ESCI 121
Section 05
Fall 2008
Daily Objectives #26 (November 20, 2008)                                                                                                                        Dr. Sanders

By the end of today's class, you should be able to do the following:

w REVIEW: Explain the terms watershed, drainage basin, and divide.

w REVIEW: Demonstrate how to locate a point on a map using the Public Land Survey system (township, range, and section).

STREAMS AND FLOODING

w REVIEW: Explain the terms oxbow, meander, floodplain, and stream discharge.

w REVIEW: Sketch a profile illustrating a floodplain. Explain how a floodplain would appear on a topographic map.

The Hydrologic Cycle:
     Make a list of all the kinds of environments in the world that contain water.
     Combine your list with a partner's.
     Write each environment on a sticky note.
     Compare your sticky notes with those of another pair of students. Eliminate redundancies and combine those that are similar.
     Arrange the sticky notes on a poster sheet and use them to illustrate the hydrologic cycle. Label the processes that connect the sticky notes.

ACTIVITY ONE: The Stream Table

Preparation: Smooth the surface of the sand in the stream table. Make it reach the level of the metal plate on the upstream side, and gradually decrease until it ends at the tape mark on the side of the table. The surface should be perfectly smooth!

Experiment A: Turn the water on by flipping the switch. Adjust the discharge by turning the valve until there is a small but continuous flow. This flow will create a stream. Carefully observe the stream for the next 5-10 minutes. It will change continuously during that time, and your job is to observe what happens.

w How does the stream channel form? What shape does it take? Does the shape change over time?

w Where does erosion occur? Where does deposition occur? Does this change over time? If so, how?

w What feature forms where the stream meets the ocean? Sketch it. Place a toothpick near the main channel in this area. Watch it for a few minutes. What happens? If you build your house on a feature like this, what is likely to happen to it?

Experiment B: Shut the water off, and smooth the sand again. Carve a deep, meandering channel for the stream. Then, turn the water back on. Watch one meander for a few minutes. Where does erosion occur? Deposition? Which side has steeper banks?

ACTIVITY TWO: Graphing Your Discharge Data

w Graph the stream data you collected in preparation for an exercise next time: graph discharge vs. time, showing the 10 days before the peak flow, the day of the peak flow, and the 10 days following the peak flow. Follow the example shown in class.

w Write the name of the stream and gage on a sticky note and apply it to the map of Illinois to indicate the location.

ACTIVITY THREE: The Rainfall-Runoff Relationship

w From the hydrologic cycle diagram, identify the processes that directly affect stream flow, and draw a diagram illustrating only those processes.

w Some watersheds (drainage basins) will respond to rainfall differently than others. Make a list of all the characteristics of drainage basins that might affect the rainfall-runoff relationship.

Department of Earth Science | Northeastern Illinois University