ASSESSMENT OF THE EXPANSION OF ALFALFA CULTIVATED AREAS IN THE EMIRATES OF ABU DHABI USING GEOSPATIAL TECHNIQUES

The agriculture sector poses a real threat to groundwater. Irrigated crop cultivation practices change groundwater levels as a result of cultivating crops or farming plants that consume large amounts of water. Alfalfa is an example of a high-water consuming crop, being a widely cultivated crop in the UAE. It needs 18 to 36 inches of water per season and according to Statistics Center Abu Dhabi (SCAD) in 2016, most of the farms are producing alfalfa. This research has been conducted with the objective of assessing the expansion of the alfalfa-cultivated areas in the Abu Dhabi Emirate over two decades. It is based on a total of five vegetation indices (VIs) were calculated and stacked with visible and near-infrared bands (VNIR), producing a composite image. The image was then classified applying unsupervised ISODATA algorithm, with the end goal of generating a map that shows the areas planted with alfalfa for three different years using images provided by the Landsat satellite. As a result, we detected an ongoing increase in the area occupied by alfalfa in around 20 years, which increased from 102.32 km2 to 430.59 km2 between 2002 and 2020. The output was cross validated with field samples, and the overall accuracy of the method was around 81.7%. The significant and rapid increase of the areas planted with alfalfa in Abu Dhabi farms prompts the government to replace it with other crops that are better suited to the region's arid climate.