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Use of Satellite Images to Optimize Regional Management Strategies: Adapting a Classification Process to Map Cotton Fields

P.J. Trichilo, L.T. Wilson, R.K. Haldenby


Satellite Thematic Mapper (TM) images were used to quantify the size, shape, and location of cotton fields in 14 counties on the High Plains of Texas. These data were subsequently used to provide maps of cotton fields to Plains Cotton Growers, Inc. (PCG) for use in the High Plains Boll Weevil Diapause Control Program. The key to this study was in adapting a semi-automated system that could classify cotton and identify individual cotton fields. Several changes resulted in substantial improvements over last year, and facilitated a process that produced much more acceptable field maps. These modifications included the following. 1) Use of a satellite image collected in mid-August rather than mid-July. Only by mid-August had plants produced enough vegetation (enough ground cover) to be sufficiently recognizable in the image, especially during a dry year. 2) As mid-August is too late to be of value to the current year's program, an image from mid-August of the previous year was used. It was assumed that changes in field shape and location, as well as data lost to cloud cover would be corrected during land-based (vehicle) reconnaissance, otherwise known as ground-truthing. 3) A geographic information system (GIS) was used to produce buffer strips around digital line graphs (DLGs) of roads and highways, which delineated individual fields in the subsequent maps. Ground-truthing indicated that map accuracy was relatively high for irrigated fields, but less so for dryland cotton. Additionally, a method was developed to estimate susceptibility of cropland to spring weevil infestations, based on proximity to 1/2-mile buffers placed around overwintering habitats.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1086 - 1090
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998