Analysis of Water Resources in Horqin Sandy Land Using Multisource Data from 2003 to 2010

Over the past four decades, land use/land cover (LU/LC) change, coupled with persistent drought, has resulted in the decline of groundwater levels in Horqin Sandy Land. Accordingly, this study quantifies changes in LU/LC and groundwater storage (GWS). Furthermore, it investigates the effects of LU/LC changes on GWS. GWS changes are estimated using Gravity Recovery and Climate Experiment (GRACE) data and ground-based measurements obtained from July 2003 to December 2010. Soil moisture and snow water equivalent data derived from the Global Land Data Assimilation System (GLDAS) are used to isolate GWS changes from GRACE-derived terrestrial water storage changes. The result shows that the groundwater depletion rate in Horqin Sandy Land is 13.5 +/- 1.9 mm.year(-1) in 2003-2010, which is consistent with the results of monitoring well stations. LU/LC changes are detected using bitemporal imageries (2003 and 2010) from Landsat Thematic Mapper through the post-classification comparison method. The result shows that LU/LC significantly changed during the aforementioned period. Bare soil and built-up land have increased by 76.6% and 82.2%, respectively, while cropland, vegetation, and water bodies have decreased by 14.1%, 74.5%, and 82.6%, respectively. The analysis of GWS and LU/LC changes shows that LU/LC changes and persistent drought are the main factors that affect groundwater resources.