Unexpected consequences of large-scale ecological restoration: Groundwater declines are reversed

Groundwater resources play a crucial role in vegetation restoration and ecological development in the northern part of the Loess Plateau. However, it remains unclear how the groundwater level has changed with the resto-ration of ecological environments in the last two decades in the region, where long-term groundwater obser-vations are largely not available. This study reconstructed the groundwater level in this region from 2001 to 2020 by establishing relationships between the monthly surface water fluxes (precipitation, evapotranspiration, and runoff) and the observed change in groundwater level from 2018 to 2020 and extrapolating the relationships to the pre-2018 period. We found that the groundwater level strongly decreased before 2011 but increased gradually after 2011. Increase in precipitation change plays a dominated role for the groundwater recovery and increase in evapotranspiration plays a substantial role, despite secondary. Our result is probably unexpected, but provides insights for possible change in groundwater resources in the near future in the regions with large-scale ecological restoration.