Climatic Change and Human Activities Link to Vegetation Dynamics in the Aral Sea Basin Using NDVI

The rural and urban areas of Central Asia underwent substantial land cover changes which has escalated the water scarcity condition in the Aral Sea, during past decades. In this article, we analyzed spatial variation of the vegetation based on GIMMS NDVI (Global Inventory Modelling and Mapping Studies) and its correlation with climatic variables (temperature, precipitation and soil moisture) in the Aral Sea Basin (ASB) for growing and non-growing seasons over two different periods, i.e., 1982-1999 and 2000-2015. For this purpose, NDVI was obtained from GIMMS and climatic variables from datasets on the CRU (Climatic Research Unit). The results showed a weak positive correlation between NDVI and climatic variables during the growing season for both the study periods. The analysis revealed 0.08/10 years and 0.04/10 years of vegetation trends during growing and non-growing periods, respectively. During the growing season of 2000-2015, the spatial vegetation trend decreased by 7.84% area coverage as compared to 1982-1999. The small regions that showed only slight vegetation increase were observed over cropland and mountain regions in the northeastern and southeastern parts of basin. The impacts of human activities on the growing NDVI season were further investigated using residual trend analysis. The results revealed that in the growing season of 1982-1999, the human impact on NDVI changes was significant, with a positive residual trend accounting for 37.03% of the total area. For the period 2000-2015, a positive residual trend of 2.22% was found in the basin.