Search for: ground water

Millions of people across the globe are severely afflicted because of water potability issues, and to proffer a solution to this crisis, efficient and cost-effective desalination techniques are necessitated. Membranes, in particular Graphene-derived membranes, have emerged as a potential answer to this grave problem because of their tunable ionic and molecular sieving capability, thin structure, and customizable microstructure. Among graphene-derived membranes, Graphene Oxide membranes have been the most promising, given the replete presence of oxygen-containing functional groups on its surface. However, the prospects of commercial applicability of these membranes are currently plagued by uneven stacking, crossflow delamination, flawed pores, screening and pH effects, and horizontal defects in the membrane. In addition, due to the selectivity–permeability trade-off that commonly exists in all membranes, the separation efficiency is negatively influenced. This review, while studying these challenges, aims to outline the most recent ground-breaking developments in graphene-based membrane technology, encompassing their separation mechanism, selectivity, adjustable mechanical characteristics, and uses. Additionally, we have covered in detail how several process variables such as temperature, total oxygen concentration, and functional groups affect the effectiveness of membrane separation with the focal point tilted toward studying the currently used intercalation techniques and effective nanomaterial graphene oxide membranes for water desalination

Water striders are abundant in areas with high humidity and rainfall. Raindrops can weigh more than 40 times the adult water strider and some pelagic species spend their entire lives at sea, never contacting ground. Until now, researchers have not systematically investigated the survival of water striders when impacted by raindrops. In this experimental study, we use high-speed videography to film drop impacts on water striders. Drops force the insects subsurface upon direct contact. As the ensuing crater rebounds upward, the water strider is propelled airborne by a Worthington jet, herein called the first jet. We show the water strider’s locomotive responses, low density, resistance to wetting when briefly submerged, and ability to regain a super-surface rest state, rendering it impervious to the initial impact. When pulled subsurface during a second crater formation caused by the collapsing first jet, water striders face the possibility of ejection above the surface or submersion below the surface, a fate determined by their position in the second crater. We identify a critical crater collapse acceleration threshold ∼ 5.7 gravities for the collapsing second crater which determines the ejection and submersion of passive water striders. Entrapment by submersion makes the water strider poised to penetrate the air–water interface from below, which appears impossible without the aid of a plastron and proper locomotive techniques. Our study is likely the first to consider second crater dynamics and our results translate to the submersion dynamics of other passively floating particles such as millimetric microplastics atop the world’s oceans.

High Salinity Shelf Water (HSSW) formed in the Ross Sea of Antarctica is a precursor to Antarctic Bottom Water (AABW), a water mass that constitutes the bottom limb of the global overturning circulation. HSSW production rates are poorly constrained, as in-situ observations are scarce. Here, we present high-vertical-and-temporal-resolution salinity time series collected in austral winter 2017 from a mooring in Terra Nova Bay (TNB), one of two major sites of HSSW production in the Ross Sea. We calculate an annual-average HSSW production rate of ~0.4Sv(10⁶m³s⁻¹), which we use to ground truth additional estimates across 2012–2021 made from parametrized net surface heat fluxes. We find sub-seasonal and interannual variability on the order of$$0.1$$$0.1$$${Sv}$$$Sv$, with a strong dependence on variability in open-water area that suggests a sensitivity of TNB HSSW production rates to changes in the local wind regime and offshore sea ice pack.

Seismic design of water retaining structures relies heavily on the response of the retained water to shaking. The water dynamic response has been evaluated by means of analytical, numerical, and experimental approaches. In practice, it is common to use simplified code‐based methods to evaluate the added demands imposed by water sloshing. Yet, such methods were developed with an inherent set of assumptions that might limit their application. Alternatively, numerical modeling methods offer a more accurate way of quantifying the water response and have been commonly validated using 1 g shake table experiments. In this study, a unique series of five centrifuge tests was conducted with the goal of investigating the hydrodynamic behavior of water by varying its height and length. Moreover, sine wave and earthquake motions were applied to examine the water response at different types and levels of excitation. Arbitrary Lagrangian‐Eulerian finite element models were then developed to reproduce 1 g shake table experiments available in the literature in addition to the centrifuge tests conducted in this study. The results of the numerical simulations as well as the simplified and analytical methods were compared to the experimental measurements, in terms of free surface elevation and hydrodynamic pressures, to evaluate their applicability and limitations. The comparison showed that the numerical models were able to reasonably capture the water response of all configurations both under earthquake and sine wave motions. The analytical solutions performed well except for cases with resonance under harmonic motions. As for the simplified methods, they provided acceptable results for the peak responses under earthquake motions. However, under sine wave motions, where convective sloshing is significant, they underpredict the response. Also, beyond peak ground accelerations of 0.5 g., a mild nonlinear increase in peak dynamic pressures was measured which deviates from assumed linear response in the simplified methods. The study confirmed the reliability of numerical models in capturing water dynamic responses, demonstrating their broad applicability for use in complex problems of fluid‐structure‐soil interaction.

Depth‐based and radar‐based remote sensing methods (e.g., lidar, synthetic aperture radar) are promising approaches for remotely measuring snow water equivalent (SWE) at high spatial resolution. These approaches require snow density estimates, obtained from in‐situ measurements or density models, to calculate SWE. However, in‐situ measurements are operationally limited, and few density models have seen extensive evaluation. Here, we combine near‐coincident, lidar‐measured snow depths with ground‐penetrating radar (GPR) two‐way travel times (twt) of snowpack thickness to derive >20 km of relative permittivity estimates from nine dry and two wet snow surveys at Grand Mesa, Cameron Pass, and Ranch Creek, Colorado. We tested three equations for converting dry snow relative permittivity to snow density and found the Kovacs et al. (1995) equation to yield the best comparison with in‐situ measurements (RMSE = 54 kg m⁻³). Variogram analyses revealed a 19 m median correlation length for relative permittivity and snow density in dry snow, which increased to >30 m in wet conditions. We compared derived densities with estimated densities from several empirical models, the Snow Data Assimilation System (SNODAS), and the physically based iSnobal model. Estimated and derived densities were combined with snow depths andtwtto evaluate density model performance within SWE remote sensing methods. The Jonas et al. (2009) empirical model yielded the most accurate SWE from lidar snow depths (RMSE = 51 mm), whereas SNODAS yielded the most accurate SWE from GPRtwt(RMSE = 41 mm). Densities from both models generated SWE estimates within ±10% of derived SWE when SWE averaged >400 mm, however, model uncertainty increased to >20% when SWE averaged <300 mm. The development and refinement of density models, particularly in lower SWE conditions, is a high priority to fully realize the potential of SWE remote sensing methods.

The land surface hydrology of the North American Great Lakes region regulates ecosystem water availability, lake levels, vegetation dynamics, and agricultural practices. In this study, we analyze the Great Lakes terrestrial water budget using the Noah‐MP land surface model to characterize the catchment hydrological regimes and identify the dominant quantities contributing to the variability in the land surface hydrology. We show that the Great Lakes domain is not hydrologically uniform and strong spatiotemporal differences exist in the regulators of the hydrological budget at daily, monthly, and annual timescales. Subseasonally, precipitation and soil moisture explain nearly all the terrestrial water budget variability in the southern basins, while the northern latitudes are snow‐dominated regimes. Seasonal assessments reveal greater differences among the basins. Precipitation, evaporation, and runoff are the dominant sources of variability at lower latitudes, while at higher latitudes, terrestrial water storage in the form of ground snowpack and soil moisture has the leading role. Differences in land cover categorizations, for example, croplands, forests, or urban zones, further induce spatial differences in the hydrological characteristics. This quantification of variability in the terrestrial water cycle embedded at different temporal scales is important to assess the impacts of changes in climate and land cover on catchment sensitivities across the diverse hydroclimate of the Great Lakes region.

Two adjacent groundwater wells on the North China Platform are used to study how earthquakes impacted aquifers. We use the response of water level to solid Earth tides to document changes after earthquakes and how aquifer and fracture properties recovered to pre‐earthquake properties. We consider two models for the phase and amplitude of water level response to the lunar diurnal (O₁) and semidiurnal (M₂) tides: a leaky aquifer model, and a model in which fracture orientation determines the response. In the leaky aquifer model, changes arise from changes in permeability and storage; in the fracture model, changes are due to changes in apparent orientation of transmissive fractures. Responses in one well are best explained by the leaky aquifer model, and can explain the large amplitude coseismic water level and permeability changes and the non‐recoverable changes after the largest earthquake. Responses in the other well are consistent with the fracture model and show little coseismic change in water level but changes in apparent fracture orientation. Larger ground motions lead to larger coseismic water level changes and longer recovery times. We propose that the well in the more permeable and shallow aquifer has less variable pore‐pressures around the well. Larger coseismic strains from water level changes may enable longer‐lasting changes in aquifer properties. We conclude that relatively high permeability aquifers are less susceptible to impacts from seismic waves, and thus have small changes in water levels and hydrogeological properties.

Multidimensional trait frameworks are increasingly used to understand plant strategies for growth and survival. However, it is unclear if frameworks developed at a global level can be applied in local communities and how well these frameworks—based largely on plant morphological traits—align with plant physiology and response to stress.

Read the freePlain Language Summaryfor this article on the Journal blog.

Increasing stream metal concentrations apparently caused by climate warming have been reported for a small number of mountain watersheds containing hydrothermally altered bedrock with abundant sulfide minerals (mineralized watersheds). Such increases are concerning and could negatively impact downstream ecosystem health, water resources, and mine‐site remediation efforts. However, the pervasiveness and typical magnitude of these trends remain uncertain. We aggregated available streamwater chemistry data collected from late summer and fall over the past 40 years for 22 mineralized watersheds throughout the Colorado Rocky Mountains. Temporal trend analysis performed using the Regional Kendall Test indicates significant regional upward trends of ∼2% of the site median per year for sulfate, zinc, and copper concentrations in the 17 streams affected by acid rock drainage (ARD; median pH ≤ 5.5), equivalent to concentrations roughly doubling over the past 30 years. An examination of potential load trends utilizing streamflow data from eight “index gages” located near the sample sites provides strong support for regionally increasing sulfate and metal loads in ARD‐affected streams, particularly at higher elevations. Declining streamflows are likely contributing to regionally increasing concentrations, but increasing loads appear to be on average an equal or greater contributor. Comparison of selected site characteristics with site concentration trend magnitudes shows the highest correlation for mean annual air temperature and mean elevation (R²of 0.42 and 0.35, respectively, with all others being ≤0.14). Future research on climate‐driven controlling mechanisms should therefore focus on processes such as melting of frozen ground directly linked to site mean temperature and elevation.

The predicted intensification of the North American Monsoon is expected to alter growing season rainfall patterns in the southwestern United States. These patterns, which have historically been characterized by frequent small rain events, are anticipated to shift towards a more extreme precipitation regime consisting of fewer, but larger rain events. Furthermore, human activities are contributing to increased atmospheric nitrogen deposition throughout this dryland region.