Imagens multitemporais TM/Landsat-5 da epoca de pre-plantio na estimativa de areas destinadas a cultura de verao / TM/ Landsat-5 data from pre crop season to estimate the area to be planted with summer crop

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

The estimate of the Area of Land to be planted with annual crops and its stratification by municipality are important variables in crop forecast. Nowadays in Brazil, these information are obtained by the Brazilian Institute of Geography and Statistics (IBGE)and published under the report Assessment of the Agricultural Production. Due to the high cloud cover in the main crop growing season (October to March)it is difficult to acquire good orbital images. Thus, one alternative is to work with remote sensing data from dates before the crop growing season. This work presents the use of multitemporal TM/Landsat-5 data gathered on July and September of 1998 (before the summer growing season)in order to estimate the area of land to be planted with summer crops in an area of Sao Paulo State, Brazil. Geographic Information Systems (GIS)and digital image processing techniques were applied for treatment of the available data. Supervised and non-supervised classifications were used for data in digital number and reflectance formats and for the multitemporal Normalized Difference Vegetation Index (NDVI)images. The objective was to discriminate the tracts with higher probability to become planted with summer crops. Classification accuracy s were evaluated using a sampling system developed basically for this study region. The estimated areas were corrected using the error matrix derived from these evaluations. The classification techniques presented an excellent level according to the kappa index. The proportion of crops stratified by municipalities was derived by a field work during the crop growing season. These proportion coefficients were applied onto the area of land to be planted with summer crops (derived from TM/Landsat-5 data). Thus, it was possible to derive the area of each summer crop by municipality. The discrepancies between official statistics and our results were attributed to the sampling and to the stratification procedures. Nevertheless, this methodology can be improved in order to provide good crop area estimatives using remote sensing data, despite the cloud cover during the growing season.

ASSUNTO(S)

cultura de verao landsat 5 estatistica agricola thematic mappers (landsat) geographic information systems land use mapeador tematico (landsat) agronomia sistemas de informacao geografica uso da terra sig crop inventories

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