Water Dynamics Research Articles

Hydrology on Solid Grounds? Integration Is Key to Closing Knowledge Gaps Concerning Landscape Subsurface Water Storage Dynamics

ABSTRACTIndividual approaches to observe water dynamics across our landscape, from the land surface to groundwater, are many though they individually only provide glimpses into the real world due to their specific space–time scales. Comprehensive integration across all available observations is still largely lacking, limiting both our ability to reduce scientific knowledge gaps, and to guide land and water management using the best available scientific evidence. We argue that a stronger focus on integration of observational products, while utilising machine learning and accounting for current perceptual understanding is urgently needed to overcome this limitation. Since Europe is warming faster than any other continent, central Europe is undergoing a dramatic hydroclimatic transition about which such integrated observations would provide timely and valuable insights. Here, we present potential and gaps of current and planned observational methods. We argue that hyperresolution (sub km) integrated estimates of landscape water dynamics are feasible, which could significantly improve our ability to simulate vadose zone and groundwater dynamics, ultimately closing gaps in our current perception of hydrological processes in a temperate region under strong influence from climate change. We close by arguing that an interdisciplinary effort of various scientific communities is needed to enable this advancement.

Synthesis of layered Co9S8-based composites for high-efficiency rotating evaporation of saturated brine

Harvesting freshwater via solar interfacial evaporation is a promising strategy with net-zero emissions. To achieve long-term stable freshwater acquisition, researchers have developed dynamic solar-driven water evaporators. However, these evaporators exhibit limited evaporation rates due to the insufficient photothermal conversion properties of the materials used. In this study, we prepared Co9S8/CoNiO2/Au composite materials through in-situ topological transformation, thereby improving the effect of the heterogeneous crystal lattice mismatch on electron transport. By embedding these materials into a spherical polyurethane sponge, we developed a new type of self-rotating evaporator with a solar full-spectrum absorbance of 95.84 %. The evaporator stably exhibited an evaporation rate of 3.10 kg m−2 h−1 within 240 h in saturated brine. The present work provides insights into the preparation of photothermal composites and the development of high-efficiency stable solar evaporators.

Understanding and simulating of three-dimensional subsurface hydrological partitioning in an alpine mountainous area, China

AbstractCritical zone (CZ) plays a vital role in sustaining biodiversity and humanity. However, flux quantification within CZ, particularly in terms of subsurface hydrological partitioning, remains a significant challenge. This study focused on quantifying subsurface hydrological partitioning, specifically in an alpine mountainous area, and highlighted the important role of lateral flow during this process. Precipitation was usually classified as two parts into the soil: increased soil water content (SWC) and lateral flow out of the soil pit. It was found that 65%–88% precipitation contributed to lateral flow. The second common partitioning class showed an increase in SWC caused by both precipitation and lateral flow into the soil pit. In this case, lateral flow contributed to the SWC increase ranging from 43% to 74%, which was notably larger than the SWC increase caused by precipitation. On alpine meadows, lateral flow from the soil pit occurred when the shallow soil was wetter than the field capacity. This result highlighted the need for three-dimensional simulation between soil layers in Earth system models (ESMs). During evapotranspiration process, significant differences were observed in the classification of subsurface hydrological partitioning among different vegetation types. Due to tangled and aggregated fine roots in the surface soil on alpine meadows, the majority of subsurface responses involved lateral flow, which provided 98%–100% of evapotranspiration (ET). On grassland, there was a high probability (0.87), which ET was entirely provided by lateral flow. The main reason for underestimating transpiration through soil water dynamics in previous research was the neglect of lateral root water uptake. Furthermore, there was a probability of 0.12, which ET was entirely provided by SWC decrease on grassland. In this case, there was a high probability (0.98) that soil water responses only occurred at layer 2 (10–20 cm), because grass roots mainly distributed in this soil layer, and grasses often used their deep roots for water uptake during ET. To improve the estimation of soil water dynamics and ET, we established a random forest (RF) model to simulate lateral flow and then corrected the community land model (CLM). RF model demonstrated good performance and led to significant improvements in CLM simulation. These findings enhance our understanding of subsurface hydrological partitioning and emphasize the importance of considering lateral flow in ESMs and hydrological research.

Fine-scale phytoplankton community transitions in the oligotrophic ocean: A Mediterranean Sea case study

The vast diversity of marine phytoplankton, shaped by intricate water dynamics, remains poorly understood in the oligotrophic ocean. In situ studies reveal fine-scale dynamics affecting phytoplankton distribution, leading to abrupt shifts in abundance and biomass referred here as “phytoplankton community transitions” (PCTs). Using a simple nutrient-phytoplankton-zooplankton (NPZ) numerical model, our study proposes a theoretical framework to explain PCTs observed during an oceanographic cruise in the Mediterranean Sea. We consider both a homogeneous and a variable environment, respectively corresponding to the waters on both sides of a front and to the frontal area itself. In the model, PCTs between one community of smaller phytoplankton and one community of bigger phytoplankton are controlled by nutrient supply, but not directly: nutrient supply affects all compartments of the model and creates PCTs by combining bottom-up and top-down controls. This mechanism is observed for both constant (i.e., within a water mass) and pulsed (i.e., in the front) nutrient supply. These results are consistent with in situ observations of biomass proportion across a front. This theoretical framework helps to better understand and plan in situ observations in oceanic regions characterized by fine-scale dynamics and oligotrophic conditions.

Experimental study on hydrodynamic performance and structural forces of curved and vertical front face pile-supported permeable breakwaters

This paper presents an experimental study on the hydrodynamic characteristics and structural forces of pile-supported permeable breakwaters under regular wave conditions. The study evaluates three distinct configurations: one featuring a vertical superstructure, another with a permeable curved superstructure, and a third that combines a permeable curved superstructure incorporating a perforated diaphragm. Experiments were conducted under regulated wave conditions, focusing on pressures, forces, and hydrodynamic scattering coefficients associated with each structural form. Results from the experiments indicate that, under the conditions tested in this study, the curved permeable superstructure significantly reduces wave reflection coefficients and forces acting on critical elements. The curved permeable superstructure maintains reflection coefficients below 0.3 while ensuring low transmission coefficients. Moreover, the study explores dynamic water pressure on an inclined perforated plate and identifies an asymmetric double-peak phenomenon in the pressure time series, signifying the transition from regular waves to breaking waves. The critical wave steepness for the occurrence of double peaks was found to be lower than the breaking limit steepness. Filter analysis elucidates the generation mechanism and evolution pattern of this double-peak phenomenon, revealing the influence of relative water depth, with second-order harmonics dominating near the bottom and second- and third-order harmonics prevalent at the free water surface. This research contributes to the understanding of the hydrodynamic performance of pile-supported permeable breakwaters and underscores the benefits of the curved permeable superstructure design in reducing wave reflection and structural forces. The findings provide valuable insight for the further development and application of pile-supported breakwater structures.

Achieving Antibiofouling on Microporous Membranes Prepared with a Green Solvent via Spraying an Aqueous Antifouling Copolymer Solution

This study highlights a comprehensive investigation into the fabrication and characterization of sustainable membranes for antifouling applications. It utilizes γ-valerolactone as a green solvent to obtain microfiltration PVDF membranes, and leverages spray-coating technique to modify these membranes. This research aims to enhance the surface and bulk properties of PVDF membranes while promoting sustainable practices. Chemical analyses of the membranes reveal that the surface and bulk of the membranes were successfully modified. Dynamic water contact angle measurements indicated that a 10 mg/mL coating solution (PVDF_10) resulted in the highest hydrophilicity. Different biofouling tests were conducted using proteins and bacteria. In adhesion tests with BSA, and E. coli, the PVDF_10 membrane demonstrated the highest resistance, reducing adhesion by approximately 83% and 94%, respectively. Additionally, cyclical water/bacterial filtration tests demonstrated that PVDF_10 membrane achieved a higher flux recovery ratio compared to commercial hydrophilic PVDF membranes. The modifications remained stable even after 6 weeks of immersion in water. This study highlights the potential of γ-GVL and the spray-coating technique as environmentally friendly solvents and modification techniques for producing green antifouling PVDF membranes, aligning with sustainable practices and significantly enhancing membrane performance.

Leaching Efficiency During Autumn Irrigation in China’s Arid Hetao Plain as Influenced by the Depth of Shallow Saline Groundwater and Irrigation Depth, Using Data from Static Water-Table Lysimeters and the Hydrus-1D and SIMDualKc Models

The need for controlling salinity in arid zones is essential for sustainable agricultural production and irrigation water use. A case study performed for two years in Hetao, Inner Mongolia, China, is used herein to rethink the contradictory issues of arid lands represented by water saving and controlling soil and water salinity. Two sets of static lysimeters, where water table depths (WTDs) were fixed at 1.25, 150, 2.00, and 2.25 m, were continuously monitored, and soil water and solute data were used to calibrate and validate two models: the soil water balance model SIMDualKc and the deterministic soil water and salt dynamics model HYDRUS-1D. Once accurately calibrated, the models were used to simulate maize water use, percolation, and capillary rise, along with the observed variables for the actual WTD and the autumn irrigation applied. Simulation scenarios also considered agricultural system degradation and dynamic water table behavior. Results have shown that large leaching efficiencies (Lefs) were obtained for large irrigation depths in cases of shallow water tables, but higher Lefs corresponded to high application depths when the water table was deeper. Agricultural system degradation, particularly increased groundwater salinity, lowered Lef, regardless of WTD. Conversely, water savings were minimal and only achievable when considering the dynamic nature of groundwater. These results indicate that there is a need to define different WTDs based on soil characteristics that influence fluxes and root zone storage, as well as the impacts of newly installed drainage systems aimed at salt extraction.

Prediction of impulse waves generated by the potential failure of large deposits in the Rumei Reservoir, Lancang River, China

The impulse wave generated by the reservoir landslide seriously endangers the surrounding safety. In this paper, the failure mode of a large deposit in Rumei Reservoir, China was first explored by centrifuge test. Thereafter, a physical model based on Froude similarity (scale 1:200) and a numerical model based on fluid‒solid coupling were constructed. The failure motion process and the generated impulse waves of the deposits at high (2895 m) and low (2750 m) water levels are studied in detail. The results of the two models are similar. The velocity and wave height of the deposits at the 2750 m water level are greater than those at the 2895 m water level. The maximum wave heights generated in the river under both conditions exceed 46 m and 22 m, respectively, and the maximum run-ups formed on the opposite bank are 71 m and 30 m, respectively. This also suggests that landslides in the near field area are dangerous. Waves at both water levels will not overtop the dam, but attention should be given to the effect of the first wave at the 2895 m water level on the dynamic water pressure in the key area of the dam.

The organization of subglacial drainage during the demise of the Finnish Lake District Ice Lobe

Abstract. Unknown basal characteristics limit our ability to simulate the subglacial hydrology of rapidly melting contemporary ice sheets. Sediment-based landforms generated beneath Late Pleistocene ice sheets, together with detailed digital elevation models, offer a valuable means of testing basal hydrology models, which describe the flow and dynamics of water in the subglacial system. However, to date no work has evaluated how well process-based subglacial hydrology models represent the hypothesized conditions associated with glaciofluvial landform formation in the palaeo setting. Previous work comparing model output to geomorphological evidence has typically done so using models that do not resolve subglacial processes and instead express likely subglacial water pathways. Here, we explore the ability of the Glacier Drainage System model (GlaDS), a process-based subglacial hydrology model, to represent the genesis conditions associated with a specific glaciofluvial landform termed “murtoos”. Distinctive triangular landforms found throughout Finland and Sweden, murtoos are hypothesized to form 40–60 km from the former Fennoscandian Ice Sheet margin within a “semi-distributed” system at the onset of channelized drainage in small cavities where water pressure is equal to or exceeds ice overburden pressure. Concentrating within a specific ice lobe of the former Fennoscandian Ice Sheet and using digital elevation models with a simulated former ice surface geometry, we forced GlaDS with transient surface melt and explored the sensitivity of our model outcomes to parameter decisions such as the system conductivity and bed topography. Our model outputs closely match the general spacing, direction, and complexity of eskers and mapped assemblages of features related to subglacial drainage in “meltwater routes”. Many of the predictions for murtoo formation are produced by the model, including the location of water pressure equal to ice overburden, the onset of channelized drainage, the transition in drainage modes, and importantly the seasonal sequence of drainage conditions inferred from murtoo sedimentology. These conclusions are largely robust to a range of parameter decisions, and we explore seasonal and inter-annual drainage behaviour associated with murtoo zones and meltwater pathways. Our results demonstrate that examining palaeo basal topography alongside subglacial hydrology model outputs holds promise for the mutually beneficial analyses of palaeo and contemporary ice sheets to assess the controls of hydrology on ice dynamics and subglacial landform evolution.

Seismic Response Characteristics of a Utility Tunnel Crossing a River Considering Hydrodynamic Pressure Effects

As a long lifeline system of buried structures, the utility tunnel (UT) is vulnerable to earthquake invasion. For utility tunnels with inverted siphon arrangements crossing rivers, the seismic response is more complex due to the basin effect of acceleration in the topography and the influence of fluctuating hydrodynamic pressure, but there is currently a gap in targeted seismic response analyses and references. Based on a UT project in Haikou, this paper studied seismic responses of a cast-in-place UT considering the coupled model of water–soil–tunnel structure on ABAQUS software. Herein, the dynamic fluctuation of hydrodynamic pressure is simulated using an acoustic–solid interaction model. A viscoelastic artificial boundary was used to simulate the soil boundary effect, and seismic loads were equivalent to nodal forces. Considering seismic invading direction and varying water elevation, this paper investigates the dynamic response characteristics and damage mechanisms of river-crossing utility tunnels. This study shows that the basin effect causes the soil acceleration around the UT to show variability in different sections, and the amplification factor of the peak acceleration at the central location is almost doubled. The damage and dynamic water pressure of the UT are intensified under bidirectional seismic excitation, and the damage location is concentrated at the junction of the horizontal section and the vertical section. Bending moments and axial forces are the main mechanical behaviors along the axial direction. Changes in river levels have a certain positive effect on the UT peak MISES, DAMAGEC, and SDEG, and it exhibits a certain degree of energy dissipation and seismic damping effect. For the aseismic design of cross-river cast-in-place utility tunnels, bidirectional seismic calculations should be performed, and the influence of river hydrodynamic pressure should not be neglected.

Molecular dynamics insights into the dynamical behavior of structurally modified water in aqueous deep eutectic solvents (ADES).

Recent studies have demonstrated that the presence of water in deep eutectic solvents (DESs) significantly affects their dynamics, structure, and physical properties. Although the structural changes due to the addition of water are well understood, the microscopic dynamics of these changes have been rarely studied. Here, we performed molecular dynamics simulation of 30% (v/v) (∼0.57 molar fraction) water mixture of DES containing CH3CONH2 and NaSCN/KSCN at various salt fractions to understand the microscopic structure and dynamics of water. The simulated results reveal a heterogeneous environment for water molecules in aqueous DES (ADES), which is influenced by the nature of the cation. The diffusion coefficients of water in ADESs are significantly lower than that in neat water and concentrated aqueous NaSCN/KSCN solution. When Na+ ions are replaced by K+ ions in the ADES system, the diffusion coefficient increases, which is consistent with the measured nuclear magnetic resonance data. Self-dynamic structure factor for water and other simulated dynamic quantities, such as reorientation, hydrogen-bond, and residence time correlation functions, show markedly slower dynamics inside ADES than in the neat water and aqueous salt solution. Moreover, these dynamics become faster when Na+ ions in ADES are replaced by K+ ions. The results suggest that the structural environment of water in Na+-rich ADES is rigid due to the presence of cation-bound water and geometrically constrained water. The medium becomes less rigid as the KSCN fraction increases due to the relatively weaker interaction of K+ ions with water than Na+ ions, which accelerates the dynamical processes.

Probing atomic-scale processes at the ferrihydrite-water interface with reactive molecular dynamics

Interfacial processes involving metal (oxyhydr)oxide phases are important for the mobility and bioavailability of nutrients and contaminants in soils, sediments, and water. Consequently, these processes influence ecosystem health and functioning, and have shaped the biological and environmental co-evolution of Earth over geologic time. Here we employ reactive molecular dynamics simulations, supported by synchrotron X-ray spectroscopy to study the molecular-scale interfacial processes that influence surface complexation in ferrihydrite-water systems containing aqueous MoO42-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext {MoO}_4}^{2-}$$\\end{document}. We validate the utility of this approach by calculating surface complexation models directly from simulations. The reactive force-field captures the realistic dynamics of surface restructuring, surface charge equilibration, and the evolution of the interfacial water hydrogen bond network in response to adsorption and proton transfer. We find that upon hydration and adsorption, ferrihydrite restructures into a more disordered phase through surface charge equilibration, as revealed by simulations and high-resolution X-ray diffraction. We observed how this restructuring leads to a different interfacial hydrogen bond network compared to bulk water by monitoring water dynamics. Using umbrella sampling, we constructed the free energy landscape of aqueous MoO42-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext {MoO}_4}^{2-}$$\\end{document} adsorption at various concentrations and the deprotonation of the ferrihydrite surface. The results demonstrate excellent agreement with the values reported by experimental surface complexation models. These findings are important as reactive molecular dynamics opens new avenues to study mineral-water interfaces, enriching and refining surface complexation models beyond their foundational assumptions.Graphic

Dynamic Water Microskin Induced by Photothermally Responsive Interpenetrating Hydrogel Networks for High‐Performance Light‐Tracking Water Evaporation

AbstractSolar‐driven interfacial water evaporation is attracting increasing attention as a promising environmentally‐friendly solution to freshwater scarcity. It has been proven that a thin water layer on photothermal materials can prevent solar energy from invalidly heating the excess water to enhance the evaporation rate. However, the current water layers are usually formed on inelastic materials via confined capillarity, which are static and uncontrollable. Herein, we propose a flexible hydrogel‐based photothermal conversion material with thermal responsiveness by facile frontal polymerization, which can generate a unique dynamic water microskin (DWMS) during the solar evaporation process. The copolymerized hydrogel, introduced by the second polymeric poly(vinyl alcohol) network and thermally responsive poly(N‐isopropylacrylamide) (PNIPAM), exhibits reinforced mechanical strength and photothermally triggers reversible shrinking/swelling cycles that enable a thin water layer (≈32 µm) to balance the feedwater supply and photothermic energy input dynamically. As a result, a stable superior vaporization rate of 8.7 kg m−2 h−1 is achieved based on a cylindrical hydrogel with 6 cm height under 1 sun. Moreover, the simultaneous responsive bending allows efficient omnidirectional solar evaporation by light‐tracking to ensure maximum perpendicular solar absorption, which provides an alternative strategy for durable high‐efficiency solar evaporators for effective thermal management and solar utilization.

Evapotranspiration measurements in pasture, crops, and native Brazilian Cerrado based on UAV-borne multispectral sensor.

In Brazil, agriculture consumes most of the available freshwater, especially in the Cerrado biome, where the rain cycle is marked by long periods of drought. This study, conducted at the Brazilian Agricultural Research Corporation (Embrapa) Research Corporation unit in Santo Antônio de Goiás, Goiás, Brazil, estimated evapotranspiration (ET) in different crops and soil cover. Using multispectral unmanned aerial vehicle (UAV) images, Sentinel satellite data, weather station information, and towers employing the eddy covariance method, we applied the "Simple Algorithm for Evapotranspiration Retrieving" (SAFER) to calculate ET in common bean, pasture, and semideciduous seasonal forest areas. The results showed a good agreement between UAV and satellite data, with R2 = 0.84, also validated with flow towers by the eddy covariance method. UAV-based ET was observed to correspond well to tower (EC) during full vegetative development of beans but is underestimated at the beginning of planting and in the final periods of plant senescence, due to the influence of soil or straw cover. These findings contribute to a better understanding of water dynamics in the system and to enhancing sustainable agricultural practices. This method, adapted for multispectral aerial imaging, can be applied flexibly and on-demand, in different contexts and ground cover. The study highlights the importance of integrated agricultural practices for better management of water resources and preservation of the Cerrado in balance with cultivation areas.

Summer evapotranspiration-cloud feedbacks in land-atmosphere interactions over Europe

AbstractLand-atmosphere (L-A) feedbacks are important for understanding regional climate functioning. However, the accurate quantification of feedback strength is challenging due to complex, nonlinear interactions and varying background atmospheric conditions. In particular, the role of cloud water in the terrestrial water cycle is often ignored or simplified in previous L-A feedback studies, which overlook the relationship between evapotranspiration (ET) and cloud water (TQC). This study diagnoses the interactions between $$\:ET$$, $$\:TQC$$ and its dynamics ($$\:\varDelta\:TQC/\varDelta\:t$$) under different atmospheric conditions by conducting correlation and a novel scaling analysis, based on a coupled regional climate model simulation. Contrasting correlation relationships between $$\:ET$$, $$\:TQC$$ and $$\:\varDelta\:TQC/\varDelta\:t$$ were identified, indicating the positive feedback between $$\:ET$$ and the dynamics in cloud water. Two types of positive scaling relationships between $$\:ET$$ and $$\:\varDelta\:TQC/\varDelta\:t$$ were identified by K-means clustering. The analysis shows a contrasting north-south distribution of the scaling relationship that is similar to the spatial distribution of energy-limited and water-limited $$\:ET$$ regimes, highlighting the role of ET regimes in modulating the $$\:ET$$ - $$\:\varDelta\:TQC/\varDelta\:t$$ scaling relationships. Moreover, the feedback strength and scaling relationship are affected by atmospheric moisture flux dynamics, providing remote moisture sources and altering dry/wet conditions. Our results highlight the role of cloud water in the atmospheric part of the L-A process chain and reveal the effect of different atmospheric conditions on L-A interactions based on the new analysis framework.

Satellite observations of surface water dynamics and channel migration in the Yellow River since the 1980s

Study regionthe Yellow River (YR) in China. Study focusDue to climate change and human activities, YR channel morphology has undergone significant spatiotemporal variations. Yet, a comprehensive understanding of channel migration in YR and its driving factors remains unclear. Here, we developed a multi-index water extraction method to track the changes in surface water and river channel migration of YR based on Landsat imagery since the 1980s. New hydrological insights for the regionWe find that the average surface water area of YR over the past four decades is 4013 km2, with 73.5 % of permanent surface water. Notably, the surface water extent has experienced a 9 % increase since the 1980s, while the river channel has undergone a 12.2 % decrease. The YR channel’s centerline exhibits diverse change patterns across the entire basin, which can be broadly categorized into six types ranging from unchanged to reverse migration. We identify that climate, particularly temperature and precipitation, contributed 71 % of channel changes in the upper reaches, while 65 % of changes in the lower reaches are from human activities, including reservoir operations and water management policies. Our results unveil the variations in water extent and channel migration of the YR, offering new insights into the interactions between channel migration and climate change and human activities in the YR over the past four decades.

Experimental and numerical evaluation of soil water and salt dynamics in a corn field with shallow saline groundwater and crop-season drip and autumn post-harvest irrigations

In areas with shallow saline groundwater, soil salts inevitably accumulate in the root zone during the growth period due to irrigation and upward movement of salts from the groundwater. In Northern China, autumn irrigation (AIR) with large amounts of water is commonly employed post-harvest to mitigate soil salt stress on crop growth in the subsequent year. Optimizing the total irrigation depth during both crop-growth and non-growth periods is challenging because of the movement of soil salts, which is influenced by their two-dimensional distribution around drippers and the impact of the winter freeze-thaw cycles, significantly affecting water flow and solute transport during winter. In this study, the HYDRUS-1D and HYDRUS-2D models were integrated and calibrated using experimental data collected from 2021 to 2023 in China's Ordos south bank irrigation area. This model integration was conducted to assess soil water and salt dynamics during the non-growth and corn-growth periods under different irrigation strategies: a) AIR with high (AH) and low (AL) irrigation depths, and b) drip irrigation (DIR) with high (DH), medium (DM), and low (DL) irrigation depths. The results indicated that HYDRUS effectively modeled the electrical conductivity of the saturation paste extract (ECe) across different irrigation strategies, yielding an average coefficient of determination (R2) and the root mean square errors (RMSE) of 0.87 and 0.53 dS m−1, respectively. Generally, ECe increased during the growth period with DIR and decreased during the non-growth period with AIR. For the 0–40 cm soil layer, ECe decreased by 5.7 % and 12 % for every 100 mm increase in the AIR and DIR depths, respectively. Compared with the AHDM and AHDL treatments, reducing an AIR depth and increasing a DIR depth resulted in lower ECe in the 0–40 cm layer during the growth period and higher crop yield (CY) and irrigation water productivity (WPI). Specifically, the average ECe in the 0–40 cm layer decreased by 4.8 % during the growth period in the ALDH treatment compared to the AHDM treatment, and CY and WPI increased by 7.2 % and 10.3 %, respectively. Additionally, the irrigation strategy was the most effective in reducing ECe when AIR accounted for 35 % of the total irrigation. This study suggested that combining low AIR and high DIR could enhance water and field productivity.

Understanding future water-carbon-land coupled systems in the era of COP 27: The case of the Hanjiang river Basin, China

The 27th Conference of the Parties (COP 27) emphasized addressing this century's interconnected challenges of food, water, and energy. This study proposes a coupled ecosystem service and multi-scenario land-use change simulation model designed to investigate the future dynamics of water-carbon-land coupled systems in the Hanjiang River Basin (HJRB), the primary objective is to provide valuable insights that can inform strategic spatial management decisions, aligning with the ambitious objectives outlined in COP 27. Specifically, this study utilized the PLUS model, InVEST model, and redundancy analysis to comprehensively analyze the interplay between ecosystem services and land-use changes, with a specific focus on water, carbon, and land dynamics. The results showed that regardless of the simulated scenarios, there was a consistent pattern observed in the changes of land use types within the HJRB, with a decrease in farmland and an increase in forest. However, the water area showed an increasing trend in all scenarios, especially in the ecological land protection (ELP) and sustainable development scenarios. Furthermore, the ELP scenario effectively suppressed the expansion of building land and the erosion of ecological land. Ecosystem services under different scenarios showed similar spatial distribution patterns but presented varying degrees of change related to the impact of future land use and urban development on ecosystem services. The water yield (WY), carbon storage, and soil conservation in the upstream areas increased to varying degrees, while those in the downstream areas decreased. In conclusion, precipitation, land use/land cover change, DEM (Digital Elevation Model), and NDVI (Normalized Difference Vegetation Index) were the main driving factors affecting ecosystem services, with precipitation having the most significant and enduring impact on WY. This study supports the adoption of targeted spatial management measures to promote sustainable development and enhance human well-being.

Enhanced Carbon/Oxygen Ratio Logging Interpretation Methods and Applications in Offshore Oilfields

As the development of most domestic and international oilfields progresses, many fields have entered a mature phase characterized by high water cut and high recovery, with water cut levels often exceeding 90%. Carbon/oxygen ratio logging has proven to be an indispensable tool for distinguishing oil layers from water layers in complex environments, especially where salinity is low, unknown, or highly variable. This logging method has become one of the most effective techniques for determining residual oil saturation in cased wells, providing critical insights into the oil–water interface. In this study, we evaluate two key interpretation models for carbon/oxygen ratio logging: the fan chart method and the ratio chart method. We optimize the interpretation parameters in the ratio chart model using an improved genetic algorithm, which significantly enhances interpretation precision. The optimized parameters enable a more seamless integration of logging results with reservoir and conventional logging data, reducing the influence of lithological variations and physical property differences on the measurements. This research establishes a robust theoretical foundation for enhancing the interpretation accuracy of carbon/oxygen ratio logging, which is crucial for effectively identifying water-flooded layers. These advancements provide vital technical support for monitoring oil–water dynamics, optimizing reservoir management, and improving production efficiency in oilfield development.

Drought-Induced Alterations in Carbon and Water Dynamics of Chinese Fir Plantations at the Trunk Wood Stage.

Over the past three decades, China has implemented extensive reforestation programs, primarily utilizing Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) in southern China, to mitigate greenhouse gas emissions and counter extreme climate events. However, the effects of drought on the carbon sequestration capacity of these forests, particularly during the trunk wood stage, remain unclear. This study, conducted in Huitong, Hunan, China, from 2008 to 2013, employed the eddy covariance method to measure carbon dioxide (CO2) and water fluxes in Chinese fir forests, covering a severe drought year in 2011. The purpose was to elucidate the dynamics of carbon and water fluxes during a drought year and across multi-normal year averages. The results showed that changes in soil water content (-8.00%), precipitation (-18.45%), and relative humidity (-5.10%), decreases in air temperature (-0.09 °C) and soil temperature (-0.79 °C), and increases in vapor pressure deficit (19.18%) and net radiation (8.39%) were found in the drought year compared to the normal years. These changes in environmental factors led to considerable decreases in net ecosystem exchange (-40.00%), ecosystem respiration (-13.09%), and gross ecosystem productivity (-18.52%), evapotranspiration (-12.50%), and water use efficiency (-5.83%) in the studied forests in the drought year. In this study, the occurrence of seasonal drought due to uneven precipitation distribution led to a decrease in gross ecosystem productivity (GEP) and evapotranspiration (ET). However, the impact of drought on GEP was greater than its effect on ET, resulting in a reduced water use efficiency (WUE). This study emphasized the crucial role of water availability in determining forest productivity and suggested the need for adjusting vegetation management strategies under severe drought conditions. Our results contributed to improving management practices for Chinese fir plantations in response to changing climate conditions.