Spatiotemporal flooding fluctuation analysis: wetland managment Bañado La Estrella, Chaco región, Argentina

The wetlands are widely distributed over the Chaco region. Despite their wide territorial extension and major functional role, Bañado la Estella wetlands have not been appropriately mapped, and this is not a protected area nowadays. Wetlands are ecosystems that depend on periodical flooding, which determine the presence of soils with hydromorphic features and species adapted to permanent or temporary flooding conditions.
The bed of the Pilcomayo River began regressing to the west about 30 years ago, creating a wetlands known as the “Bañado la Estrella”. We propose an integrated approach, based on satellite imagery analysis (Landsat TM), The NDWI index (Normalized Difference Water) and decision trees, to analyze and characterize seasonal variations (1992-2012) and to map seasonal flooding. We use information about land use and herd distribution (anthropogenic use) and validate it with field data.
Four classes of flooding frequency were defined: permanent flooded areas (80-100 % of the time pixels showed water presence), usually flooded areas (60-100% of the time) and regularly flooded areas (40-60% of the time) during the 1992-2012 period. We are able to delimitate and quantify the total area of Bañado La Estrella wetlands which occupies 1682 km2 including the permanently, usually and regularly flooded areas. This spatio temporal analysis shows that during the dry period the permanently flooded areas were reduced 462 km2 of the total wetland area while the usually flooded area occupied 2 % of the total area and the regularly flooded area occupied 5%. Our results suggest that this method can be used to delimitate different zones, gathering together hydrodynamic and anthropogenic activities, in order to be used as tool for the creation of a future protect area in Argentina.