Effects of Vegetation Restoration on Groundwater Drought in the Loess Plateau, China

The Loess Plateau (LP) is a typical water-limited area. Since the revegetation plan started in 1999, the rapid growth of vegetation has not only significantly changed the local water cycle, but also probably affected regional groundwater drought. However, the effect of revegetation on groundwater drought remains largely unexplored. To this end, we isolated the groundwater anomalies from terrestrial water storage of the Gravity Recovery and Climate Experiment satellites and soil moisture of the Global Land Data Assimilation System, and further used the drought severity index to characterize groundwater drought. The evolution characteristics of groundwater drought in the LP were analyzed, and the effect of revegetation plan on groundwater drought were explored. Results indicated that: (1) Normalized Difference Vegetation Index (NDVI) during 2003 similar to 2015 in the LP was growing rapidly, meanwhile, groundwater storage significantly decreased (p < 0.01) and groundwater drought intensified in terms of its area and intensity; (2) compared with meteorological factors, NDVI is more strikingly correlated (p < 0.05) with groundwater drought on annual, seasonal and monthly scales, especially near the key areas of vegetation restoration; (3) the growth rate of vegetation is a dominant factor affecting groundwater drought in the LP, in which the groundwater consumption rate caused by vegetation dynamics in the significant area is higher than non-significant area. Our research results provide guidance for formulation scientific and sustainable ecological restoration policies in the LP, and also offer new ideas for the study of the relationship between vegetation and groundwater drought.