Utilizing GIS to Determine Oxbow Lakes
and Meander Scars Along the Neosho River
in Coffey County, Kansas

by
Lacey Dreyer
George Ford
Patrick Laird

This web page was created to fulfill the requirements of ES351 Intro to Geospatial Analysis.


Table Of Contents
Introduction
Data Acquisition
Using Heads-Up Digitizing in ArcView
Oxbow Lakes & Meander Scars
Land Use Concerning Oxbow Lakes & Meander Scars
Biology Associated With Oxbow Lakes and Meander Scars
Overview
References

Introduction

GIS (Geographic Information Systems) is becoming a powerful tool used in many fields today.  GIS is a computer system designed for capturing, storing, analyzing, querying, and displaying geographic data (Chang, 2002).  There are many tools within GIS that can be used for different purposes.  For this application, we will be using ArcView 3.3 and heads-up digitizing.

Heads-up digitizing, or hand classification, is the most common approach to feature extraction using imagery.   It is often the most accurate and available approach for the user.   During heads-up digitizing, the user manually traces the outline of a feature by clicking points on the screen.  This works best when the extracted features are few because the process is slow and the quality of the extraction diminishes as the user becomes tired (Opitz).

Objective

For every GIS application, there needs to be an objective.  The objective of this application is to create two new data layers, one for oxbow lakes and one for meander scars.  Along with the creation of the new data layers, another part of the objective is determine the use of these new data layers.

Return to Table of Contents.


Data Acquisition

Two features will be extracted for this application, oxbow lakes and meander scars.  The imagery used to obtain this information are from DOQQ's (Digital Orthophoto Quarter Quadrangles) and DRG's (Digital Raster Graphics).  To save on time, a MrSID Compressed Digital Orthophoto was used.  This is a compressed file of all the DOQQ's that make up the entire county.  A DOQQ is an aerial photograph acquired from an altitude of 20,000 feet and and taken with black and white film.  Each photograph is one quarter section of a 7.5 minute USGS quadrangle, and covers approximately a five and a half mile by five and a half mile area (USGS).  A DRG is the raster version of a topographical map which has been scanned so that it can be used as a data layer.  The data from the DOQQ is from 1991 and the data from the DRG is from 1997.

One source to obtain Kansas data is from the State of Kansas GIS Initiative's DASC (Data Access and Support Center), which is a data clearinghouse for GIS databases related to the state of Kansas.  Another source of data is the GIS Data Depot, which carries different data for different areas both in the United States and throughout the world.

Return to Table of Contents.


Using Heads-Up Digitizing in ArcView

In order to use heads-up digitizing, one of the imaged data layers must first be opened in ArcView.  A new theme must be created and the settings should be set to polygons.  After this is complete, make sure the new theme is highlighted and then choose 'start edit theme' from the pull down menu.  Using the toolbar at the top, you can zoom in fairly close on either the DOQQ or the DRG.  After panning to the feature you want to trace, choose the freeform icon, located to the right on the bottom of the toolbar.  Begin tracing the feature, in this case a meander scar (Figure 1), by clicking on the left button of the mouse.  After tracing all the features from both data sources, choose 'stop edit' from the pull down menu.  Create another new theme for the oxbow lakes and repeat the process.

 


Figure 1. Two Meander scars are visible on a DOQQ.  The town of Hartford is on the left.


After both new themes are complete, their databases can be opened in ArcView.  New rows and columns can be entered to contain any data necessary, such as numbering each oxbow lake and meander scar, size of the feature, length of the feature, location and so on.  This process is known as data manipulation.  After using heads-up digitizing, there were a total of forty meander scars and six oxbow lakes along the Neosho River in Coffey County, Kansas.

Return to Table of Contents.


Oxbow Lakes and Meander Scars

It is necessary to determine what oxbow lakes and meander scars look like in order to create the new data layers.  Both features are found with a mature river.  A mature river is one that meanders and has a well established flood plain.  As a meander neck forms, it becomes narrow, until an event called a cutoff takes place (Figure 2).  A cutoff occurs when the river cuts through this narrow part of the surface.  The remaining loop that is left is called an oxbow lake.  The formation of oxbow lakes occur when the river is in the flood stage.  This allows for the erosion of the meander neck (Strahler & Strahler, 1996).
 

Figure 2.  The formation of oxbow lakes and meander scars.  Image taken from Central Michigan University College of Science & Technology.
The meander neck is visible (2.a), while the cutoff process shows the formation of the oxbow lake (2.b).  As the oxbow lake fills with sediment, it becomes swampy or marshy (2.c).  Finally, when the oxbow lake completely fills with sediment (2.d), it becomes a meander scar.

As flooding occurs, the flood water deposits sediment into the oxbow lakes.  Over time, these oxbow lakes become oxbow swamps or marshes.  Eventually, the oxbow swamp loses it's ability to hold water and completely fills with sediment.  When this happens, it is referred to as a meander scar.  Meander scars become distinct when viewed from the air.  Time, erosion and agriculture do not alter the appearance of a meander scar (Figure 1).  When viewed on the DRG, oxbow lakes and meander scars have the same shape as when viewed from the air.  Oxbow lakes usually show up as water or marshes on a DRG.  The use of a DRG can aid the user when looking for meander scars.  Since rivers cut through the Earth's surface, they have a lower elevation.  Meander scars also have a lower elevation than the surrounding area and contour lines can show where these features are (Figure 3).


Figure 3.  Meander scars as seen on a DRG.

Using GIS to determine the location of oxbow lakes and meander scars can help Earth Scientists in several areas.  Both features can be used to help determine past river channels.  They can also be a source of fossils as organic material can become trapped in the oxbow lakes during periods of deposition.  Meander scars are particularly helpful in determining the age of a river.  There are three general ages of rivers; a young river, a mature river, and an old age river.  A young river will have very few or no meander scars, a small flood plain, and usually does not meander.  A mature river will meander, have several meander scars, a well defined flood plain.  An old age river has even more meander scars, a very wide (up to many miles across) flood plain, and will meander continuously throughout the course of the river.  By extracting and viewing the number of oxbow lakes and meander scars in Coffey County, the conclusion is that the Neosho River would be considered a mature river.  Oxbow lakes and meander scars are also evidence that rivers and streams do migrate, or change course.

Return to Table of Contents.


Land Use Concerning Oxbow Lakes and Meander Scars

Using GIS to determine the location of oxbow lakes and meander scars can also be useful for determing land use.  Oxbow lakes are wetlands and any change (either creation or filling) can be identified after severe flooding by using DOQQ's.  However, this can be insufficient data, as DOQQ's are only taken every five to seven years.  If you have more than one flooding event during that time, the data may not be accurate.

Rivers are often used as natural political boundaries.  This can cause an interesting debate when oxbow lakes are created.  Does the political boundary move with the river or does it stay with the oxbow lake?  Using GIS will not answer that question, but it can be used to draw fixed political boundaries instead of having the boundaries move every time a river changes (Christopherson, 2001).

Knowing where oxbow lakes occur and the location of meander scars enables city planners to work around them or avoid them, if need be.  The city of Burlington, the county seat for Coffey County, is adding on a new water treatment plant totaling $5.6 million (Peterson, 2003).  This new addition is to be built on the western edges of the Neosho River on the eastern side of Burlington, just south of the present day water treatment plant ( Figure 4).  Ideally, this is not a good location to build a water plant.  There is a meander just to the north of the water plant's location.  It is just a matter of time before this becomes an oxbow lake, which would mean the river would change course.  There are also two meander scars to the east northeast and one to the south of the water plant.  Since this is an area of frequent flooding and rivers are known to change back to an older river channel, this could cause problems in the future.  However, five miles upstream is John Redmond Reservoir.  Since the reservoir is there to prevent flooding downstream, the city of Burlington's water treatment plant will probably not be affected since the river has less chance of changing course.


Figure 4.  Water Treatment Plant at Burlington, KS.

Return to Table of Contents.


Biology Associated With Oxbow Lakes and Meander Scars

Oxbow lakes and meander scars are also important for the field of biology.  Oxbow lakes are wetlands, which in their own right, are ecosystems.  The flat floater mussel (Anodonta suborbiculata) can be found in the oxbow lakes along the Neosho River in Coffey County.  This fresh water mussel is an endangered species (KDWP, 2001).  Using data manipulation, GIS can show the locations where the flat floater mussel is found.  The data can also be updated when new oxbow lakes are created and if the flat floater mussel is found there.  GIS can also be used to show the distribution of any species of fauna or flora.  This data can be combined with various climate features such as rainfall and temperature which can be very useful.

Soils are another important area studied through biology.  Hydric soils are formed in wetland areas and are one of the identifying features of a wetland.  Hydric soils are defined by the U.S.D.A. Natural Resources Conservation Service (NRCS) as, "soils that form under conditions of saturation, flooding or ponding long enough during the growing season to develop anaerobic conditions in the upper part" (USDA).  As oxbow lakes become meander scars, the soil types within the meander scar differ from the surrounding soil.  Knowing where oxbow lakes and meander scars are located can help update and produce soil survey maps.

Return to Table of Contents.


Overview

Something as simple as oxbow lakes and meander scars can have a great impact in different fields.  The uses for GIS in the fields outlined in this web page just break the surface of what can be accomplished by using GIS.  Arcview 3.3 has a great many other tools besides heads-up digitizing.  By using the correct data and knowing where to find the data, just about anything can be accomplished.

Return to Table of Contents.


References

Chang, Kang-tsung.  2002.  Geographic Information Systems.  New York:  McGraw-Hill.

Christopherson, Robert W.  2001.  Elemental Geosystems.  New Jersey:  Prentice Hall.

KDWP.  2001.  Threatened and Endandgered Species Known or Likely to Occur in Coffey County, KS.  World Wide Web URL: http://www.kdwp.state.ks.us/PDF/EnvSrvs/TECo/COFFEY00.pdf.  Retrieved on December 5, 2003.

Opitz, David W.  Hierarchical Feature Extraction: Removing the Clutter.  World Wide Web URL:  http://gis.esri.com/library/userconf/proc02/pap0924/p0924.htm.  Retrieved on November 24, 2003.

Peterson, Mark.  2003.  Water Plant Construction Costs Trimmed to $5.6 Million.  Coffey County Republican Online.  World Wide Web URl:  http://www.coffeycountyonline.com/0909bcit.htm.  Retrieved on November 26, 2003.

Strahler, Alan & Strahler, Arthur.  1996.  Physical Geography:  Science and Systems of the Human Environment.  New York:  John Wiley & Sons, Inc.

USDA Forest Service.  Soils.  World Wide Web URL: http://www.na.fs.fed.us/spfo/pubs/n_resource/wetlands/wetlands5_soils.htm.  Retrieved on December 5, 2003.

USGS.  2003.  EROS Data Center - Products.  World Wide Web URL:  http://edc.usgs.gov/products/aerial/napp.html.  Retrieved on November 25, 2003.
 

Return to Table of Contents.


ES351 Intro to Geospatial Analysis Homepage.
Created December 8, 2003.