Environment and agriculture in semi-arid Sandia basin of northeast Mexico during the late 20th-early 21st century drought

Changes in land use and land cover (Lu/Lc) and vegetation health, in the sub-decadal scale, estimated the possible impact of late 20th - early 21st century regional drought on the environment and agriculture of Sandia Basin (ca.226 km(2)) at the semi-arid northeast Mexico. Satellite-based Landsat Thematic Mapper (TM) and Operational Land Imager (OLI) data were assessed for the pre-drought (1985 and 1990 CE), drought (1995 and 2000 CE) and post-drought (2005, 2010 and 2015 CE) conditions. Loss of land with shrub in almost one-third of the basin (ca. 84.3 km(2)), ca. 87 % reduction in the very-high vegetation (NDVI>0.6) coverage and almost 3-fold expansion of areas with no vegetation (NDVI<0.1) reflected environmental changes during the drought. Deterioration in vegetation health was also reflected by 3-fold increase in the very-high drought severity (VCI: 0-10). Drought-associated reduction in agricultural activity was marked by ca.68.5 % shrinkage of cropland and ca.42 % expansion of fallow land in 2000 CE imagery compared to the pre-drought. Drought culmination led to more than 2-fold expansion of cropland in 2005 CE imagery. However, the very-high drought severity withstanding more than half of the basin (113-128 km(2)), even during the post-drought phases, showed lack of environmental recovery and it was consistent with a tendency of below-average precipitation as well as anthropogenic Lu/Lc modifications.