Abstract
It is an effective measure to estimate groundwater storage anomalies (GWSA) by combining Gravity Recovery and Climate Experiment (GRACE) data and hydrological models. However, GWSA results based on a single hydrological model and GRACE data may have greater uncertainties, and it is difficult to verify in some regions where in situ groundwater-level measurements are limited. First, to solve this problem, a groundwater weighted fusion model (GWFM) is presented, based on the extended triple collocation (ETC) method. Second, the Shiyang River Basin (SYRB) is taken as an example, and in situ groundwater-level measurements are used to evaluate the performance of the GWFM. The comparison indicates that the correlation coefficient (CC) and Nash-Sutcliffe efficiency coefficient (NSE) are increased by 9–40% and 23–657%, respectively, relative to the original results. Moreover, the root mean squared error (RMSE) is reduced by 9–28%, which verifies the superiority of the GWFM. Third, the spatiotemporal distribution and influencing factors of GWSA in the Hexi Corridor (HC) are comprehensively analyzed during the period between 2003 and 2016. The results show that GWSA decline, with a trend of −2.37 ± 0.38 mm/yr from 2003 to 2010, and the downward trend after 2011 (−0.46 ± 1.35 mm/yr) slow down significantly compared to 2003–2010. The spatial distribution obtained by the GWFM is more reliable compared to the arithmetic average results, and GWFM-based GWSA fully retain the advantages of different models, especially in the southeastern part of the SYRB. Additionally, a simple index is used to evaluate the contributions of climatic factors and human factors to groundwater storage (GWS) in the HC and its different subregions. The index indicates that climate factors occupy a dominant position in the SLRB and SYRB, while human factors have a significant impact on GWS in the Heihe River Basin (HRB). This study can provide suggestions for the management and assessments of groundwater resources in some arid regions.
Highlights
As an important component of terrestrial water storage (TWS), groundwater plays a key role in domestic, agriculture and industrial use, as well as ecosystems [1,2]
It is necessary to test the performance of the groundwater weighted fusion model (GWFM) before it is applied to the study area and the Shiyang River Basin (SYRB) is chosen as the study area
Many previous studies have reported the time lag; for example, Thomas et al [64] indicated that when the lag time was two months, the correlation between Gravity Recovery and Climate Experiment (GRACE)-based groundwater storage anomalies (GWSA) and in situ groundwater-level measurements reached a maximum in the Central Valley of California
Summary
As an important component of terrestrial water storage (TWS), groundwater plays a key role in domestic, agriculture and industrial use, as well as ecosystems [1,2]. More than 38% of the world’s population lives in arid or semi-arid zones [3], where groundwater is usually the dominant freshwater resource, supplying domestic use and irrigation water [4]. In northwest China, groundwater resources have been facing the risk of depletion, which may lead to the ecological environment of the region losing its ability to self-repair and endangering local ecological security [5]. Accurate estimation of groundwater storage anomalies (GWSA) is essential for the effective use of local groundwater resources. The traditional method of monitoring groundwater level mainly uses monitoring wells.
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