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Groundwater, Earth’s largest source of liquid freshwater, is essential for sustaining ecosystems and meeting societal demands. However, quantifying global groundwater withdrawals remains a significant challenge due to inherent uncertainties in input data, sectoral allocation assumptions, and model parameterization. In this study, we analyze global groundwater withdrawals from 2001 to 2020 using a newly developed data-driven Global Groundwater Withdrawal (GGW) model and quantify uncertainties through Monte Carlo simulations. The GGW model integrates reported country-level data with global grid-based datasets to estimate annual withdrawals across domestic, industrial, and agricultural sectors at a 0.1° resolution (≈10 km). Our results indicate an average global groundwater withdrawal of 648 km3 a−1, with an uncertainty range of 465–881 km3 a−1. Agriculture accounts for 50% of total withdrawals, followed by domestic use at 34.5% and industrial use at 15.5%. Temporal analysis shows increasing groundwater withdrawal in 66% of the 44 IPCC WGI reference regions over the 20 years, with a global average annual increase of 0.5% (varying regionally from 6.5% annual increase to 9% annual decrease). Comparison with previous studies highlights the impact of methodological choices and assumptions about groundwater withdrawal on the resulting global estimates. Our findings underscore the need for comprehensive uncertainty assessments and improved datasets. Expanding spatial coverage in underrepresented regions and enhancing temporal resolution, particularly for dynamic variables like irrigated areas, are crucial for more accurate groundwater withdrawal assessments. These improvements will enable better management and conservation of this vital resource in the face of growing global demands and climate change impacts.

Exploitation of groundwater has greatly increased since the 1970s to meet the increased water demand due to fast economic development in China. Correspondingly, the regional groundwater level has declined substantially in many areas of China. Water sources are scarce in northern and northwestern China, and the anthropogenic pollution of groundwater has worsened the situation. Groundwater containing high concentrations of geogenic arsenic, fluoride, iodine, and salinity is widely distributed across China, which has negatively affected safe supply of water for drinking and other purposes. In addition to anthropogenic contamination, the interactions between surface water and groundwater, including seawater intrusion, have caused deterioration of groundwater quality. The ecosystem and geo-environment have been severely affected by the depletion of groundwater resources. Land subsidence due to excessive groundwater withdrawal has been observed in more than 50 cities in China, with a maximum accumulated subsidence of 2–3 m. Groundwater-dependent ecosystems are being degraded due to changes in the water table or poor groundwater quality. This paper reviews these changes in China, which have occurred under the impact of rapid economic development. The effects of economic growth on groundwater systems should be monitored, understood and predicted to better protect and manage groundwater resources for the future.

Crop production in the Central High Plains is at an all-time high due to increased demand for biofuels, food, and animal products. Despite the need to produce more food by mid-century to meet expected population growth, under current management and genetics, crop production is likely to plateau or decline in the Central High Plains due to groundwater withdrawal at rates that greatly exceed recharge to the aquifer. The Central High Plains has experienced a consistent decline in groundwater storage due to groundwater withdrawal for irrigation greatly exceeding natural recharge. In this heavily irrigated region, water is essential to maintain yields and economic stability. Here, we evaluate how current trends in irrigation demand may impact groundwater depletion and quantify the impacts of these changes on crop yield and production through to 2099 using the well-established System Approach to Land Use Sustainability (SALUS) crop model. The results show that status quo groundwater management will likely reduce irrigated corn acreage by ~60% and wheat acreage by ~50%. This widespread forced shift to dryland farming, coupled with the likely effects of climate change, will contribute to overall changes in crop production. Taking into account both changes in yield and available irrigated acreage, corn production would decrease by approximately 60%, while production of wheat would remain fairly steady with a slight increase of about 2%.

Karst aquifers are one of the main potable water sources worldwide. Although the exact global karst water utilisation figures cannot be provided, this study represents an attempt to make an upgraded assessment of earlier and often circulated data. The main objective of the undertaken analysis is not only to provide an assessment of the utilisation of current karst aquifers, but also to estimate possible trends under various impact factors such as population growth or climate changes. In > 140 countries, different types of karstified rocks crop out over some 19.3 × 106 km2, covering > 14% of ice-free land. The main ‘karst countries’, those with > 1 × 106 km2 of karst surface are Russia, USA, China and Canada, while among those with > 80% of the territories covered by karst are Jamaica, Cuba, Montenegro and several others. In contrast, in a quarter of the total number of countries, karstic rocks are either totally absent or have a minor extension, meaning that no karst water sources can be developed. Although the precise number of total karst water consumers cannot be defined, it was assessed in 2016 at approximately 678 million or 9.2% of the world’s population, which is twice less than what was previously estimated in some of the reports. With a total estimated withdrawal of 127 km3/year, karst aquifers are contributing to the total global groundwater withdrawal by about 13%. However, only around 4% of the estimated average global annually renewable karstic groundwater is currently utilised, of which < 1% is for drinking purposes. Although often problematic because of unstable discharge regimes and high vulnerability to pollution, karst groundwater represents the main source of potable water supply in many countries and regions. Nevertheless, engineering solutions are often required to ensure a sustainable water supply and prevent negative consequences of groundwater over-extraction.

We used Interferometric Synthetic Aperture Radar (InSAR)‐derived vertical land motion (VLM) timeseries during 2017–2022 to examine the compounding impacts of natural and anthropogenic processes on groundwater dynamics in the Santa Clara Valley (SCV). VLM strongly correlates (>0.75) with groundwater level in both unconfined and confined aquifers. We show that VLM in SCV is mainly driven by groundwater dynamics in deep aquifer layers below 120 m. Our results show that during the most recent drought from March 2019 to November 2021, Santa Clara County subsided up to 30 mm due to groundwater depletion, three times as large as average seasonal amplitude of VLM. Owing to the managed aquifer recharge, the region has been able to avoid unrecoverable land subsidence. We utilize InSAR data to calibrate storage coefficient and lag time related to delayed response of clay interbeds to groundwater level changes, which further serves to estimate groundwater volume loss in confined aquifer units during drought. Plain Language Summary Santa Clara County in California relies heavily on groundwater as half of the water used in the County is pumped from aquifers. Thus, management of groundwater resources is crucial to the Santa Clara County. Groundwater withdrawal and recharge causes compaction and expansion of aquifer layers which results in land subsidence and uplift, respectively. We use the Interferometric Synthetic Aperture Radar (InSAR) technique to obtain deformation time series in the Santa Clara Valley during 2017–2022 and then use that to understand the spatial and temporal changes of groundwater level and storage in the region. Our results demonstrate the usefulness of InSAR data for sustainable management of groundwater resources. Key Points Santa Clara County subsided up to 30 mm due to groundwater depletion during the most recent California drought from 2019 to 2021 Interferometric Synthetic Aperture Radar (InSAR) deformation confirms the slowdown of land subsidence due to managed aquifer recharge starting in late 2021 InSAR deformation measurements can be used to calibrate the aquifer mechanical properties used in groundwater flow/subsidence model

While most recent assessments of groundwater resources disclose drastic overexploitation in the Northwestern parts of India, for the first time, we reveal that effective regulatory measures have resulted in substantial recovery of heavily stressed aquifer systems in India's capital (Delhi). We use advanced InSAR techniques to derive high‐quality vertical displacement time series for October 2014–October 2023. Our results reveal a halting of subsidence since mid‐2016 in the Dwarka area and subsequent rebound of the aquifer system by 5–10 cm at an uplift rate reaching ∼2 cm/year. Even the subsidence zone located north of Gurgaon, which subsided by more than 1 m during the study period, exhibits exponential decay of subsidence. A significant reduction in the magnitude of subsidence in the central (from 15 to 7 cm/year) and southern parts (from 7 to 2 cm/year) is observed during 2019−October 2023 as compared to November 2014−18. In contrast, the subsidence rate in Faridabad, located outside the administrative boundary of Delhi, increased by 2 cm/year from August 2017 onwards. Our analysis suggests a gain in groundwater storage (0.002–0.007 km3/year) and the onset of pore pressure saturation due to groundwater level recovery in the Dwarka area. The decay of subsidence in the subsidence zone near Gurgaon suggests reduced groundwater extraction/enhanced recharge. The recovery of groundwater levels by more than 1.5 m over the entire Delhi is evident from 2018 onwards despite decreasing rainfall trend and is attributed to improved groundwater management. Plain Language Summary India's national capital, Delhi, has been experiencing severe water scarcity issues due to a steady decline in groundwater levels. Consequently, several regulatory measures were imposed. However, limitations of in situ observation wells pose significant challenges for monitoring the effectiveness of policy intervention. Our analyses of 9 years (November 2014–October 2023) of InSAR time series observations reveal that land subsidence in the Dwarka region due to excessive groundwater withdrawal ceased around mid‐2016, and currently, the area is uplifting at ∼2 cm/year. The region north of Gurgaon, which subsided by more than 1 m (November 2014–October 2023), also shows a decay in the subsidence rate from 2019 onwards. However, the Faridabad region, located outside the administrative boundary of Delhi, shows an increase in subsidence from 2 to 4 cm/year after 2017. The uplift in Dwarka and decay of subsidence in areas north of Gurgaon is attributed to improved aquifer management practices, including the installation of artificial recharge structures since rainfall during the concomitant period shows a declining trend. The InSAR observations are further supported by in situ groundwater level measurements, which show recovery of more than 1.5 m during 2018–21. Key Points SqueeSAR‐based analysis of 9 years of InSAR time series over Delhi, India Evidence of groundwater level recovery in stressed aquifer system Improved aquifer management instrumental in groundwater rejuvenation

Increasing population, economic growth and changes in diet have dramatically increased the demand for food and water over the last decades. To meet increasing demands, irrigated agriculture has expanded into semi-arid areas with limited precipitation and surface water availability. This has greatly intensified the dependence of irrigated crops on groundwater withdrawal and caused a steady increase in groundwater withdrawal and groundwater depletion. One of the effects of groundwater pumping is the reduction in streamflow through capture of groundwater recharge, with detrimental effects on aquatic ecosystems. The degree to which groundwater withdrawal affects streamflow or groundwater storage depends on the nature of the groundwater–surface water interaction (GWSI). So far, analytical solutions that have been derived to calculate the impact of groundwater on streamflow depletion involve single wells and streams and do not allow the GWSI to shift from connected to disconnected, i.e. from a situation with two-way interaction to one with a one-way interaction between groundwater and surface water. Including this shift and also analysing the effects of many wells requires numerical groundwater models that are expensive to set up. Here, we introduce an analytical framework based on a simple lumped conceptual model that allows us to estimate to what extent groundwater withdrawal affects groundwater heads and streamflow at regional scales. It accounts for a shift in GWSI, calculates at which critical withdrawal rate such a shift is expected, and when it is likely to occur after withdrawal commences. It also provides estimates of streamflow depletion and which part of the groundwater withdrawal comes out of groundwater storage and which parts from a reduction in streamflow. After a local sensitivity analysis, the framework is combined with parameters and inputs from a global hydrological model and subsequently used to provide global maps of critical withdrawal rates and timing, the areas where current withdrawal exceeds critical limits and maps of groundwater and streamflow depletion rates that result from groundwater withdrawal. The resulting global depletion rates are compared with estimates from in situ observations and regional and global groundwater models and satellites. Pairing of the analytical framework with more complex global hydrological models presents a screening tool for fast first-order assessments of regional-scale groundwater sustainability and for supporting hydro-economic models that require simple relationships between groundwater withdrawal rates and the evolution of pumping costs and environmental externalities.

Groundwater withdrawal can cause localized and rapid poroelastic subsidence, spatially broad elastic uplift of low amplitude, and changes in the gravity field. Constraining groundwater loss in Mexico City, we analyze data from the Gravity Recovery and Climate Experiment and its follow‐on mission (GRACE/FO) and Synthetic Aperture Radar (SAR) Sentinel‐1A/B images between 2014 and 2021. GRACE/FO observations yield a groundwater loss of 0.85–3.87 km3/yr for a region of ∼300 × 600 km surrounding Mexico City. Using the high‐resolution interferometric SAR data set, we measure >35 cm/yr subsidence within the city and up to 2 cm/yr of uplift in nearby areas. Attributing the long‐term subsidence to poroelastic aquifer compaction and the long‐term uplift to elastic unloading, we apply respective models informed by local geology, yielding groundwater loss of 0.86–12.57 km3/yr. Our results suggest Mexico City aquifers have been depleting at faster rates since 2015, exacerbating the socioeconomic and health impacts of long‐term groundwater overdrafts. Plain Language Summary Groundwater overdraft in Mexico City results from excessive freshwater demand and unsustainable water resource management in a subtropical environment with warm summers and dry winters. Groundwater depletion can result in ground surface deformation and changes in the gravity field, observable by Sentinel‐1 and GRACE satellites. Here, we examine data from both satellite missions between November 2014 and October 2021 to determine groundwater volume loss. Using GRACE, which has a footprint of ∼350 km, we quantify groundwater volume loss to a rate of 0.85–3.87 km3 per year in the broader area surrounding Mexico City. Analysis of high‐resolution Sentinel‐1 synthetic aperture radar images shows land sinks at a rate of 35 cm/yr within the city and surrounding areas uplifts at a rate of ∼2 cm/yr. While the subsidence is a consequence of aquifer compaction, the uplift represents an elastic unloading response of the Earth's crust to water mass loss. Using geophysical models informed by local geology, we show that the region loses groundwater at rates of 0.86–12.57 km3/yr. Our results emphasize the need for groundwater monitoring in Mexico City to assist with managing freshwater resources. Key Points A subsidence rate of >35 cm/yr within Mexico City, surrounded by ∼2 cm/yr of uplift, is observed using space‐borne synthetic aperture radar Groundwater loss of 0.86–12.57 km3/yr in Mexico City causes poroelastic subsidence, a broad‐scale elastic uplift, and gravity field change Mexico City aquifers have been depleting at least since 2015, exacerbating groundwater overdrafts' socioeconomic and health impacts

The Chennai aquifer system, which occupies an area of 6629 km2, is one of the most stressed aquifer systems in southern India and is under severe threat of over exploitation and quality deterioration. This is due to the increasing groundwater abstraction for irrigation, domestic, industrial purposes and for drinking water supply to the ever-expanding Chennai city. To offset the effect of this heavy extraction a paradigm shift towards groundwater management was imperative. A multidisciplinary integrated approach was used to map the aquifers, delineate their geometry, to determine the hydraulic behavior of the aquifer system, and to formulate an aquifer management plan through the development of a groundwater flow model. The main aquifers in the area include weathered and fractured crystalline rocks and recent alluvial formation. Alluvium is the most significant aquifer system in the study area, and this aquifer contains potable quality groundwater except in the eastern part of the study area that has been affected by seawater intrusion. A two-layered groundwater flow model was developed using Visual MODFLOW classic version 4.6 with a 1 km2 grid pattern to simulate groundwater flow for a period of 9 years. The model was calibrated under steady and transient state conditions and allowed components of the water balance of the system to be determined at a regional scale. The simulated results indicate that this aquifer system is under tremendous stress at the prevailing groundwater withdrawal rate of 899 million cubic meter (mcm)/year and would become unstable with the predicted 25% increase in groundwater withdrawal by 2025. However, the interventions to recharge an additional 54 mcm of water could help mitigate the current decline in potentiometric heads and could partially help to arrest the further advancement of seawater intrusion. A scenario of maintaining flow in rivers for a period of 120 days each year coupled with the construction of an unlined canal shows increase in groundwater head and development of the groundwater mounds, which are positive signs for arresting the decline of the water table and pushing saline groundwater in a seaward direction. As a result of the high rate of groundwater depletion in the area, management strategies need to be implemented urgently in the region. These strategies should include the regulation of groundwater abstraction and maintaining an extended flow period in the rivers. These measures are required to improve the sustainability of the available groundwater resources of the region.

Urban ground collapse (UGC) is becoming more common in China, resulting in significant socioeconomic losses and even personal casualties. The frequency of UGC accidents is highest in the east coastal area owing to developed urbanization, while it is lowest in the northeast area because of its smallest land area. Natural causes (such as geological conditions and rainfall) and artificial causes (such as groundwater withdrawal, underground pipeline breakage, underground engineering, and other reasons) all contribute to UGC accidents in China. Groundwater influences most factors that lead to UGC. Adverse geology, such as collapsible loess and karst geology, is sensitive to groundwater. The groundwater environment is vulnerable to rainfall, pipeline leakage or groundwater withdrawal. Under the action of groundwater, the steady state of the soil may change, which finally leads to UGC. Groundwater control, which is essential for mitigating the risk of UGC, can be implemented through detailed geological surveys, sponge city and utility tunnel construction, and groundwater–level control measurement.