Resumo

GARCIA NIETO, Hilario  e  MARTINEZ LEON, Gilberto. Use of ortophotos for update the land use map in Guanajuato, Mexico. Agric. Téc. Méx [online]. 2007, vol.33, n.3, pp.271-280. ISSN 0568-2517.

The objective of this study was to update the current land use map and to classify the areas accordingly to its potential for maize production under rainfed conditions in the state of Guanajuato, Mexico. The study was carried out from 2004 to 2005. 242 ortophotos obtained during 1993 and 1994 in a 1:20 000 scale and updated at the county level, were utilized. The ArcExplorer 2.0 program was used to display and work with the ortophotos. The printed ortophotos were updated with information collected in the field and digitalized and posisionated with the Universal Transversa of Mercator with the parameters Datum and Spheroid WGS84. The land use then was classified in: Rainfed agricultural land, irrigated agricultural land, urban areas, water bodies and of other uses. In comparison with the previous map the area with rainfed agriculture decreased while the irrigated land increased. The urban areas increased from 57 000 ha in 1997 to 104 000 ha in 2005. The intersection of the updated land use maps with the potential production maps allowed for a precise quantification of the high, medium and low levels of land aptitude for maize production under rainfed conditions. With the use of digital ortophotos, geographic information systems and direct field verification, it was possible to update and classify the land use in Guanajuato, Mexico.

Palavras-chave : Local knowledge; GIS software tools; moisture availability; digital ortophoto.