Modifications in Coverage Patterns and Land Use around the Huizache- Caimanero Lagoon System, Sinaloa, Mexico: A Multi-temporal Analysis using LANDSAT Images

Human activities, such as agriculture and shrimp farming, have influenced the Huizache-Caimanero lagoon system, modifying the landscape and diminishing its natural productivity. Four Landsat MSS (multi-spectral scanner) and TM (thematic mapper) sub-images, taken between 1973 and 1997, were analysed to evaluate trends of changes in the lagoon, saltmarsh, mangrove, agriculture, secondary succession and dry forest classes. The scenes were enhanced by principal components analysis. A thematic map for each sub-image was produced using supervised classification with the extraction and classification of homogeneous objects algorithm (ECHO). Aerial photography and field verification of testing points were used to validate the classification and to assess its accuracy using the Kappa coefficient. The area covered by class and year was estimated and the temporal trends were defined by linear regression. The natural covers (lagoon, mangrove and dry forest) showed a significant reduction in 1997 when compared with 1973, whereas the agricultural areas, secondary succession and saltmarshes showed an increase in cover. The frequency distribution analysis of the normalized difference vegetation index (NDVI) confirmed the observed trends. The Huizache-Caimanero region is a highly disturbed landscape, mainly caused by agricultural practices, that must be rehabilitated to maintain its natural productivity. ? 1999 Academic Press