Palestine is one of the most vulnerable countries in the Middle East region. Besides its political and socio-economic situation, Palestine is under the threat of desertification as the whole are of the country applies to the UNEP (The United Nations Environment Programme) definition of drylands, which based on the aridity index (the ratio between the average annual precipitation and the potential evapotranspiration). This research aims to investigate the spatial and temporal trends in the aridity index in the West Bank, Palestine, and to define the hotspot areas where the aridity index is the lowest.
To achieve this objective, a big climatic dataset was analyzed to obtain the annual precipitation and evapotranspiration for the past three decades using R software. FAO CropWAT software was used to estimate the potential evapotranspiration at the study locations. Then, the aridity index was calculated based on the estimated precipitation and potential evapotranspiration. The GIS software (Arc-Map) was used to investigate the spatial and temporal trends in aridity and to create a map of aridity for each decade. Following that, hotspot areas were defined according to the GIS maps.
The aridity maps showed an upward trend in aridity during the past three decades with a spatial expansion in the areas of low aridity index. The temporal trends on the aridity index and rainfall at the study area were identical, which emphasizes the fact that in the West Bank the AI variation is driven by changes in precipitation rather than changes in potential evapotranspiration.