Landsat TM Imagery
Cheyenne Bottoms, Kansas

James S. Aber and Firooza Pavri


Introduction

Five Landsat thematic mapper (TM) datasets were selected to span the time from the mid-1980s to the early 21st century. All datasets represent early summer conditions (late June to mid-July) for the years 1986, 1989, 1991, 1995 and 2001. During this period, significant variations in climatic conditions took place, including some drought intervals and wet phases. Beginning in the mid-1990s, the Nature Conservancy began to modify land use in its holdings. Meanwhile, new levees were installed and several artificial islands were constructed in the state wildlife area.

The following images were prepared from Landsat TM bands 2, 5 and 7, color coded as blue, green, and red. TM band 2 is green light. TM bands 5 and 7 are mid-infrared portions of the spectrum, which are particularly sensitive to active vegetation, soil moisture, and water bodies. This composite provides a naturalistic, earth-tone view of the landscape. Colors of the images are explained in the table below.

Typical feature colors on Landsat
TM 257 composite image
Image color Ground features
Light green
Dark green 		Active vegetation--summer crops,
cattail marsh, and pasture
Tan & yellow Fallow fields--winter wheat
Bright cyan Dry mudflats, bare ground, roads
Dark cyan Urban--towns and cities
Dark blue Water bodies--lakes and streams
Black Wet (bare) mudflats


Landsat TM 257 composite of Cheyenne Bottoms vicinity, 18 July 1986. The most notable feature of this view is the large, dry mudflat on the western side of the state wildlife area, near scene center (bright cyan color). Click on small image to see large version (486 kb).
Landsat TM 257 composite of Cheyenne Bottoms vicinity, 10 July 1989. Healthy vegetation, abundant water bodies, and wet mudflats represent the culmination of a relatively wet period during the mid-1980s. Click on small image to see large version (484 kb).
Landsat TM 257 composite of Cheyenne Bottoms vicinity, 30 June 1991. Generally sparse vegetation and reduced water bodies reflect drought conditions. Cattail marsh (dark green) has spread over former mudflat areas. Click on small image to see large version (499 kb).
Landsat TM 257 composite of Cheyenne Bottoms vicinity, 11 July 1995. Return to wetter conditions with more vegetation and water bodies. Note the appearance of some new levees in the state wildlife area. Click on small image to see large version (486 kb).
Landsat TM 257 composite of Cheyenne Bottoms vicinity, 25 June 2001. Culmination of a wet phase with expanded water bodies. Still more levees can be seen in the state wildlife area along with several artificial islands (~ features). Click on small image to see large version (499 kb).

Time-series analysis

Time-series analysis refers to changes in land use and land cover through time, as consequences of either natural or cultural impacts. By comparing images taken in the same season from different years, changes in the landscape can be documented. One such technique is to build a multi-temporal composite image that consists of a single TM band from three different years (Pavri et al. 2003). In this case, TM band 4 (near infrared) is selected as it is most sensitive to photosynthetically active (green) vegetation as well as water bodies and moist soil.

Colors of the resulting multi-temporal image represent conditions of change, particularly change in vegetation cover, from year to year in the three-year composite. Bright primary colors (red, green, blue) indicate a substantial change in a single year. Bright secondary colors (yellow, magenta, cyan) result from significant change for two years of the multi-temporal composite. Neutral gray and drab olive colors represent little or no change in the three-year dataset; black shows perennial water bodies.

Landsat TM 4 multi-temporal composite for 1986, 1989 and 1991, color coded as blue, green and red respectively. The most dramatic changes are located in wetland complexes of the state wildlife area and the Nature Conservancy, where bright red zones indicate spread of cattail marsh in 1991.
Landsat TM 4 multi-temporal composite for 1991, 1995 and 2001, color coded as blue, green and red respectively. Agricultural fields display noticable changes, particularly around the oval margin of Cheyenne Bottoms. This zone had increased agricultural vegetation in 1995 and 2001. Bright red in the Nature Conservancy wetland highlights expansion of cattail marsh in 2001. Blue of the state wildlife area shows where cattail marsh of 1991 was removed in 1995 and 2001.


Reference

Return to HYSPIRE research at Cheyenne Bottoms.
Last update: March 2003.