Correlation assessment of NDVI and land use dynamics with water resources for the southern margin of Mu Us Sandy Land, China

To prevent desertification, countries worldwide have made diversified efforts, and vegetation restoration has been demonstrated to be an effective approach. However, in regard to sandy land with limited water resources, measures such as revegetation may lead to an increased drought risk. Despite confirmed sand utilization achievements, many controversies remain regarding the advantages of desert greening, especially considering water scarcity. Therefore, the long-run and causal relationships between sandy land, water consumption, and vegetation coverage are necessarily explored. Choosing the southern margin of the Mu Us Sandy Land as the study area, this study explored the interactions between sandy land, water consumption, and normalized difference vegetation index (NDVI) of 2000-2018 with the vector autoregression (VAR) model approach. In the study area, various revegetation projects have been implemented, resulting in a notable reduction in the sandy land area. In addition, the NDVI increased from 0.196 in 2000 to 0.371 in 2018, an increase of 89.3%. The results indicated that there exist long-term stable equilibrium and causal relationships existed between water consumption and sandy land and NDVI. NDVI enhancement is relatively the direct factor that causes the increase of water consumption. It could be inferred that the implemented revegetation measures may rely on a large water consumption amount, which may further aggravate water shortages and ecological damage issues. More scientific and stronger effective water resource management measures should be locally implemented to achieve a balance between water resources and revegetation.