Gravity Recovery and Climate Experiment (GRACE) Storage Change Characteristics (2003–2016) over Major Surface Basins and Principal Aquifers in the Conterminous United States

Naga Manohar Velpuri,Lauren Hay,William Farmer,Gabriel B Senay,Samuel Saxe,Jessica M Driscoll,Julie Kiang

doi:10.3390/rs11080936

Abstract

In this research, we characterized the changes in the Gravity Recovery and Climate Experiment (GRACE) monthly total water storage anomaly (TWSA) in 18 surface basins and 12 principal aquifers in the conterminous United States during 2003–2016. Regions with high variability in storage were identified. Ten basins and four aquifers showed significant changes in storage. Eight surface basins and eight aquifers were found to show decadal stability in storage. A pixel-based analysis of storage showed that the New England basin and North Atlantic Coastal Plain aquifer showed the largest area under positive storage change. By contrast, the Lower Colorado and California basins showed the largest area under negative change. This study found that historically wetter regions (with more storage) are becoming wetter, and drier regions (with less storage) are becoming drier. Fourier analysis of the GRACE data showed that while all basins exhibited prominent annual periodicities, significant sub-annual and multi-annual cycles also exist in some basins. The storage turnover period was estimated to range between 6 and 12 months. The primary explanatory variable (PEV) of TWSA was identified for each region. This study provides new insights on several aspects of basin or aquifer storage that are important for understanding basin and aquifer hydrology.

Highlights

Increased human activity has inevitably led to changes in the water cycle, especially water availability
Fourier transformation of Gravity Recovery and Climate Experiment (GRACE) total water storage anomaly (TWSA) and ∆S signals showed prominent annual and multi-annual peaks and subdued sub-annual peaks. Fourier analysis of both TWSA and ∆S signals reveals that all basins and aquifers show a prominent annual cycle with a statistically significant peak at a frequency of 1 cycle/year
Our results indicate that despite P being the main driver of hydrologic processes, TWSA responds with P with a greater lag than other variables, mainly because it depends on the way P is partitioned into hydrologic fluxes

Summary

Introduction

Increased human activity has inevitably led to changes in the water cycle, especially water availability. There is still little understanding of this primary state variable [1], and its spatiotemporal variability is still emerging [2,3,4], primarily due to data scarcity of storage parameters—it is time consuming and challenging to conduct field campaigns over large areas [5]. Other problems, such as heterogeneous landscapes and basin complexities, introduce error while converting point-scale observations to the resolution of current large-scale hydrology and climate models [1]. A continental-domain understanding of changes in basin storage remains elusive

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