Groundwater resources are vital to ecosystems and livelihoods. Excessive groundwater withdrawals can cause groundwater levels to decline^1–10, resulting in seawater intrusion¹¹, land subsidence^12,13, streamflow depletion^14–16and wells running dry¹⁷. However, the global pace and prevalence of local groundwater declines are poorly constrained, because in situ groundwater levels have not been synthesized at the global scale. Here we analyse in situ groundwater-level trends for 170,000 monitoring wells and 1,693 aquifer systems in countries that encompass approximately 75% of global groundwater withdrawals¹⁸. We show that rapid groundwater-level declines (>0.5 m year⁻¹) are widespread in the twenty-first century, especially in dry regions with extensive croplands. Critically, we also show that groundwater-level declines have accelerated over the past four decades in 30% of the world’s regional aquifers. This widespread acceleration in groundwater-level deepening highlights an urgent need for more effective measures to address groundwater depletion. Our analysis also reveals specific cases in which depletion trends have reversed following policy changes, managed aquifer recharge and surface-water diversions, demonstrating the potential for depleted aquifer systems to recover.

Studying groundwater quality is crucial for ensuring its safety because it is widely used for drinking and for domestic, agricultural, and industrial purposes. Owing to the lack of surface water in the Tabuk area of Saudi Arabia, here groundwater wells are one of the primary sources of water for drinking, agriculture, and industry. Groundwater quality is determined by the aquifer characteristics of the regional geology, and it is extensively influenced by both natural and anthropogenic activities. To understand the geochemical evolution and assess the suitability of groundwater for irrigation, major ion geochemistry was utilized to characterize the chemical composition of groundwater in the Tabuk area, which is considered a semiarid plateau region. Depending on its mineral composition, irrigation water’s quality reflects how it affects plants and soil. In total, 80 groundwater samples have been collected and analyzed in laboratory for major cations and anions. Temperature, alkalinity (ALK), pH, total dissolved solids (TDS), electric conductivity (EC), total hardness (TH), oxidation reduction potential (ORP), and cation and anion concentrations were measured. Water chemistry classification was carried out by using a Piper diagram and a Gibbs diagram. In the current study, statistical methods, combined with geochemical modeling and conventional plots, have been used to investigate groundwater and related geochemical processes in the Tabuk area of Saudi Arabia. Applications and calculations of hydrogeochemical parameters, specifically SAR, RSC, PI, CR, MH, Na%, KR, and HI, showed that 92.5% of the collected groundwater well samples are suitable for drinking and irrigation purposes after treatment processes.

To improve the structural stiffness, strength and reduce the weight of nanoplate structure, functionally graded (FG) graphene-reinforced nanocomposite (GRNC) laminated plates are exploited in this paper. The bending and buckling behaviors of FG-GRNC laminated nanoplates are investigated by using novel quasi-3D hyperbolic higher order shear deformation plate theory in conjunction with modified continuum nonlocal strain gradient theory, which considered both length and material scale parameters. The modified model of Halpin–Tsai is employed to calculate the effective Young’s modulus of the GRNC plate along the thickness direction, and Poisson’s ratio and mass density are computed by using the rule of mixture. An analytical approach of the Galerkin method is developed to solve governing equilibrium equations of the GRNC nanoplate and obtain closed-form solutions for bending deflection, stress distributions and critical buckling loads. A detailed parametric analysis is carried out to highlight influences of length scale parameter (nonlocal), material scale parameter (gradient), distribution pattern, the GPL weight fraction, thickness stretching, geometry and size of GPLs, geometry of the plate and the total number of layers on the stresses, deformation and critical buckling loads. Some details are studied exclusively for the first time, such as stresses and nonlocality effect.

Groundwater quality is a critical issue in arid and semiarid countries, where it is one of the most reliable sources of water on which people depend. Water quality is a vital concern in the Kingdom of Saudi Arabia as it affects the health of its people, the growth of its agriculture, and its economic development. In this study, the objectives were to: (1) investigate the depletion rate of groundwater storage (GWS) in the study area by using Gravity Recovery and Climate Experiment (GRACE) data from April 2002 to April 2016 to quantify terrestrial water storage; (2) determine the ionic composition of cations and anions for 24 samples (12 samples from Arabian Shield and 12 from Arabian Shelf in Saudi Arabia); and (3) assess the water quality of the aquifer. The results show a GRACE-derived GWS depletion of − 2 ± 0.13 km³/year. Ionic compositions reveal two main groups: group I, with well depths of 144–607 m, and group II, with well depths of 12–150 m. Group I waters (all from the Saq aquifer) appear to be fossil waters, while group II waters (alluvial aquifer) appear to be mixed waters. As illustrated by the use of a Piper diagram, 85% of the samples in Arabian Shelf are characterized as a mixed water of calcium, magnesium, chloride, and sulfate (SO₄). In the Arabian Shield, 50% of the samples are characterized as Ca–Cl waters. Since most of the samples (98%) are from domestic wells used for drinking water and have the potential for radioactivity in the groundwater, it is essential to complete radioactive analysis and confirm acceptable water quality, based on the standards of the Water Health Organization and the Saudi Arabian Standards Organization.

People use granite in residential buildings on a large scale all around the world. Knowing granite’s radiological characteristics allows for the safe use of its properties to be maintained over time. Our findings are significant for two reasons: first, they may increase public awareness of the naturally radioactive properties of the materials under investigation, and second, they are necessary to establish standards, regulations, and management for the building materials used in Saudi Arabia. In this study, twenty-four granitic rock samples were collected from the Hai’l area in Saudi Arabia, and these samples are used as building material. Gamma spectrometry was used to measure the amounts of ²³⁸U, ²³²Th, ²²⁶Ra, and ⁴⁰K in the collected granitic rock samples. The obtained data was also used to calculate some environmental hazard parameters, such as the absorbed gamma dose rate (AGDR), annual effective dose rate (AEDR), radium equivalent (Ra_eq), external and internal hazard indexes (H_ex and H_in), gamma index (I_γ), alpha index (I_α), and excess lifetime cancer index (ELCR). We concluded that the collected granitic samples are harmful and need more attenuation if used as building materials.