Climate–groundwater dynamics inferred from GRACE and the role of hydraulic memory

Abstract

Abstract. Groundwater is the largest store of freshwater on Earth after the cryosphere and provides a substantial proportion of the water used for domestic, irrigation and industrial purposes. Knowledge of this essential resource remains incomplete, in part, because of observational challenges of scale and accessibility. Here we examine a 14-year period (2002–2016) of Gravity Recovery and Climate Experiment (GRACE) observations to investigate climate–groundwater dynamics of 14 tropical and sub-tropical aquifers selected from WHYMAP's (Worldwide Hydrogeological Mapping and Assessment Programme) 37 large aquifer systems of the world. GRACE-derived changes in groundwater storage resolved using GRACE Jet Propulsion Laboratory (JPL) mascons and the Community Land Model's land surface model are related to precipitation time series and regional-scale hydrogeology. We show that aquifers in dryland environments exhibit long-term hydraulic memory through a strong correlation between groundwater storage changes and annual precipitation anomalies integrated over the time series; aquifers in humid environments show short-term memory through strong correlation with monthly precipitation. This classification is consistent with estimates of groundwater response times calculated from the hydrogeological properties of each system, with long (short) hydraulic memory associated with slow (rapid) response times. The results suggest that groundwater systems in dryland environments may be less sensitive to seasonal climate variability but vulnerable to long-term trends from which they will be slow to recover. In contrast, aquifers in humid regions may be more sensitive to climate disturbances such as drought related to the El Niño–Southern Oscillation but may also be relatively quick to recover. Exceptions to this general pattern are traced to human interventions through groundwater abstraction. Hydraulic memory is an important factor in the management of groundwater resources, particularly under climate change.

Linkages between GRACE water storage, hydrologic extremes, and climate teleconnections in major African aquifers

“…Exceptions include aquifers in northern Africa (R = 0.15-0.33, lags 3-14 mos), Taoudeni in central Africa (R = 0.24), and Karoo in southern Africa (R = 0.28). Focusing on interannual TWS variability alone relative to cumulative monthly precipitation anomalies results in low correlations in most aquifers, except for the Kalahari and Karoo aquifers (R = 0.48-0.82; table 1), indicating longer term precipitation memory in these aquifers, also noted in previous studies [10,51].…”

Land–Ocean–Atmosphere Influences on Groundwater Variability in the South Atlantic–Gulf Region

“…Additionally, the GWS anomaly in Rajasthan, India, calculated using the Gravity Recovery and Climate Experiment (GRACE) estimates, showed an increasing trend in annual recharge [22]. GRACE is an advanced remote sensing product that provides monthly TWS measurements and has proved to be an effective tool for hydrological studies [23,24]. GRACE is being successively utilized for climate studies, quantification of hydrologic processes, and large-scale GWS changes due to limited spatial and temporal in situ groundwater data.…”

“…GRACE is being successively utilized for climate studies, quantification of hydrologic processes, and large-scale GWS changes due to limited spatial and temporal in situ groundwater data. Opie et al [23] studied the correlation between GRACE GWS and precipitation for 37 large aquifer systems of the world. Identifying the dominant hydroclimatic variables affecting GRACE-derived groundwater variability using singular value decomposition (SVD) is a novel and the main motivation of this study.…”

Assessing Changes in Terrestrial Water Storage Components over the Great Artesian Basin Using Satellite Observations

“…An increasing number of studies have successfully applied GRACE to quantify variations in groundwater storage through space and time [22][23][24][25][26]. GRACE observations have been particularly useful for detecting variations in groundwater storage in semi-arid areas and to better understand the climate and human-driven factors that are responsible for this variation [18,[27][28][29][30][31][32][33][34].…”

“…Similar to many artesian basins, changes in groundwater stores in the GAB are challenging to investigate owing to its sheer size and the relative scarcity of bore monitoring sites. Despite this difficulty, a wealth of knowledge has been gained from investigations of sub-basins of the GAB using GRACE and bore data [32,33,35,36]. For example, Robertson [37] investigated the unsustainable groundwater extraction in the Surat sub-basin (southeast) of the GAB and found that management of GAB requires proper design concepts and improvements in social and political views.…”