Influence of global climate signals on groundwater anomalies in High Plains aquifer

Abstract:

Groundwater is crucial for the livelihoods and food security in arid and semi-arid zones. An understanding of both spatial and temporal fluctuations in groundwater (GW) and how these are affected by global climate patterns can contribute to better management of groundwater resources. The Gravity Recovery and Climate Experiment (GRACE) mission launched in March 2002 and the Follow-On mission (GRACE-FO) launched in May 2018 have been widely used by scientists to estimate monthly Total Water Storage (TWS) from which groundwater can be derived. With improved releases of processed data products and longevity of the GRACE and GRACE-FO mission, it becomes possible to analyze changes in groundwater and its link with global climate patterns such as El Niño-Southern Oscillation (ENSO). In the current study, TWS-derived from GRACE Mascon RL06, Soil Moisture and Snow Water Equivalent simulated by the Global Land Data Assimilation System (GLDAS) were used in the period 2002-2020 to estimate fluctuations in the High Plains aquifer, which has been subject to pumping and irrigation. A trend analysis was performed, and then Principal Component Analysis (PCA) is carry out to observe spatio-temporal oscillation modes and its relationship with Oceanic Niño Index (ONI). Furthermore, to validate GRACE-derived GW and evaluate a larger period climate pattern such as Pacific Decadal Oscillation (PDO), Depth to Water data from United States Geological Survey (USGS) wells distributed in the aquifer were selected with period 1980-2020 and Spectral Analysis was performed looking for teleconnections.

Results shows increasing trend in zones of the Northern aquifer while a decreasing in the central and southern part of it. First four components can explain over 80% of variance and have relationships with stronger and larger events in the ONI as La Niña 2007-2008, 2010-2011 and El Niño 2015-2016, also periodicities in wells and indices suggest connections of groundwater changes with ENSO as well as with PDO in High Plains.