Rebound of surface and terrestrial water resources in Mongolian plateau following sustained depletion

Abstract

Water resources have always played an important role in ensuring industrial and agricultural production, as well as maintaining ecosystem security in the Mongolian Plateau (MP), a typical arid to semi-arid region. Previous studies have reported the considerable shrinkages of surface water bodies affected by intense human disturbance in the MP before 2010. However, it is still unclear about the effects of those key ecological restoration efforts (e.g., the construction of ecological civilization since 2012) on water resources in the recent decade. Here, using all the available Landsat-5/7/8 surface reflectance observations, a robust water mapping algorithm based on spectral indices and thresholds, and the Google Earth Engine (GEE) cloud computing platform, we examined the changes in surface water area (SWA) in the MP during 1991–2021. In addition, based on the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) Mascon data products, we investigated the inter-annual variability and trends of terrestrial water storage (TWS) from 2002 to 2021. We found that SWA experienced remarkable increases (85.5 km2/yr) since 2009 after continuous shrinkage of surface water bodies (-205.9 km2/yr) for over 20 years, in which Inner Mongolia played a dominant role in the recovery of SWA (72.2 km2/yr). Also, TWS had undergone continuous decline before 2012 and fluctuating rebound after that. The most significant recovery of TWS mainly happened in the northern part of the MP. Quantitative attribution analyses showed that the key ecological restoration projects in China, especially the construction of ecological civilization since 2012, were the major drivers for the recovery of surface and terrestrial water resources. While previous studies reported the considerable decline of surface water resources induced by human activities in the MP since the 1990s, our research provided gratifying satellite evidence for the significant recoveries of surface and terrestrial water resources in the plateau during the past decade under the influence of ecological restoration efforts.