This study focuses on the China–Mongolia Arid Region (CMAR), a vast area spanning approximately 34–48°N latitude and 78–120°E longitude in northern China and southern Mongolia. The aim of this research is to derive a transparent, causally guided empirical model of basin-scale water balance change ( ΔS ) in the CMAR through a combined causal discovery and symbolic machine learning approach. Utilizing a 43-year (1980–2022) monthly ERA5 reanalysis dataset, the study employs the Peter-Clark Momentary Conditional Independence (PCMCI) algorithm to identify robust, lagged predictors from over 200 hydro-meteorological variables. Through a reproducible screening protocol combining physical relevance, redundancy control, and causal stability testing, this pool was reduced to 15 core variables. These causally relevant predictors then inform a symbolic regression (SR) procedure, which evolves an explicit regression form for the basin's water balance anomaly, aiming to bridge the gap between statistical accuracy and mechanistic physical insight. The combined PCMCI → SR workflow reveals that the water balance in the CMAR is co-dominated by energetic forcing (short-wave radiation), zonal moisture transport tendencies, and short-term hydrological memory, particularly runoff lags, while recognising that convergence/divergence ultimately governs the full balance. Notably, the derived equation quantifies a non-additive interaction between regional vapor transport and local precipitation recycling, whereby high recycling rates can intensify water deficits under conditions of strong advection. This causally grounded empirical framework advances the understanding of dryland hydro-climatology and offers a transferable, data-driven modelling approach for data-scarce arid regions. • PCMCI guides symbolic regression for basin-scale water-balance change ΔS . • Radiation, zonal transport, and runoff memory co-dominate arid ΔS . • High moisture recycling can worsen storage balance under strong vapor transport. • SR equation explains 73% of monthly water-balance change ΔS variability.

From hatchling to adult: multi-stressor effects of zinc toxicity and salinity in a benthic marine annelid.

Quantitative assessment of denitrification rates at the freshwater-saltwater interface of a limestone island based on isotopic tracers and mass balance calculation.

Effectiveness of watershed management on water balance components-a review

Lake Tana Sub-Basin, Ethiopia The Lake Tana sub-basin plays a vital role in Ethiopia’s hydropower generation and irrigation development. However, the recent operation of an interbasin water transfer has intensified competition for water resources, raising concerns about long-term hydrological sustainability and downstream ecological flows. To evaluate these impacts, this study developed an integrated modeling framework that couples the HBV Light rainfall-runoff model, a lake water balance model, and the Water Accounting Plus (WA+) approach to assess water availability, consumption patterns, and downstream ecological flow conditions for 2010–2020. The HBV Light model was unable to accurately simulate the natural lake outflow, but its coupling with the lake water balance model significantly improved model performance, resulting in NSE of 0.79 and R² of 0.92. The mean annual inflow to the lake was estimated at 6.9 km³ , with 55% contributed by the Gilgel Abbay catchment. The rainfall and evaporation over the lake was estimated at 4.1 km³ yr⁻¹ and 5.1 km³ yr⁻¹ , respectively. Total annual outflow averaged 5.8 km³ , with 3.1 km³ yr⁻¹ diverted through the interbasin water transfer and 2.7 km³ yr⁻¹ outflow at the natural outlet. The interbasin water transfer now exceeds lake's natural outflow and has increased the frequency of unmet environmental flow requirements from 6% (pre-transfer period) to 27% during 2010–2020. In terms of consumption, rainfed agriculture dominates water consumption at 5.7 km³ yr⁻¹ , while irrigation accounts for only 0.4 km³ yr⁻¹ . Green evapotranspiration (ET) constitutes 68% of total water consumption, with blue ET making up the remaining 32%. These results demonstrate the hydrological implications of interbasin water transfer on lake outflow and downstream ecological conditions. The integrated modeling framework offers a scalable approach for hydrological assessment and water allocation in data-scarce basins. • An integrated modelling framework was developed to address complex water management challenges in the Lake Tana sub-basin. • The interbasin water transfer surpasses the lake outflow at the natural outlet. • Downstream environmental flow requirements are significantly impacted by interbasin water transfers. • Water availability and scarcity indicators were derived to inform sustainable water resource planning • The study offers actionable insights for balancing hydropower development with environmental flow needs.

Land use/Land cover control on groundwater recharge: A multi-method assessment using remote sensing-based Water Balance in the Lusaka Aquifer, Zambia

This study investigates the climate sensitivity and resilience of radial growth in eight coniferous and deciduous tree species in the Vienna Woods, Austria. Using dendrochronological methods, we analyzed tree-ring width data from 63 forest plots to assess growth responses to meteorological variability over the period 1933-2023. Historic climate records were used to develop a water balance model, from which we derived seasonal growth factors. Linear mixed effects models were applied to quantify species-specific relationships between tree-ring width and climatic conditions during the current and preceding two years. Tree-ring width responded not only to climatic conditions of the current growing season but also strongly to those of the previous year. Soil moisture and air temperature emerged as the principal drivers of radial growth, with soil moisture positively and temperature negatively affecting ring width. Climatic conditions during June-July of the current year exerted the strongest impact on ring formation. Using regional climate trends and projected air temperature and precipitation trajectories for Central Europe under RCP4.5 and RCP8.5, we forecast future growing conditions for the region. Both scenarios predict an extended growing season, increased transpiration demand, and heightened drought risk - more pronounced under RCP8.5. However, projected increases in precipitation partly offset the drought risk. By combining historical climate sensitivity of radial increment with future climate projections, we modelled expected tree-ring growth for eight tree species. Most species are predicted to experience notable declines in radial growth, with the strongest reductions in conifers, including European larch (Larix decidua), Norway spruce (Picea abies), Austrian pine (Pinus nigra) and Scots pine (Pinus sylvestris). Deciduous species - Sycamore maple (Acer pseudoplatanus), European beech (Fagus sylvatica), and sessile oak (Quercus petraea) - show moderate declines. In contrast, Turkey oak (Quercus cerris) is projected to increase radial growth under future climate scenarios. These findings suggest that forest management in the Vienna Woods and adjacent regions should prioritize the promotion of warm- and drought-tolerant tree species such as Quercus cerris to enhance forest resilience and sustainability in the face of climate change.

This contribution showcases advanced artificial intelligence applications that transform over 20 years of terrestrial water storage anomaly (TWSA) observations from the Gravity Recovery and Climate Experiment (GRACE) and its follow-on (GRACE-FO) mission into a comprehensive 100-year dataset for the Congo Basin. We develop CM-RecNet, a climate-memory hybrid model, to reconstruct the basin’s TWSA for the period 1923–2024. CM-RecNet combines two RecNet deep learning models—one capturing climate-driven TWSA and another capturing memory effects—fused via a multilayer perceptron. The model achieves strong performance, with a correlation coefficient (CC), Nash–Sutcliffe Efficiency, and normalized root mean square error of 0.82, 0.70, and 0.20 during the testing period, respectively. Our reconstruction aligns well with observed runoff (CC>0.6 at most stations), Normalized Difference Vegetation Index (CC = 0.71), and water balance budget (CC = 0.69). In addition to its consistency with existing reconstructions, CM-RecNet exhibits a heightened capacity to capture the basin’s climate variability. This innovative approach enables access to previously unavailable data within the Congo Basin, necessary for understanding its critical water challenges associated with climate change and anthropogenic activities.

Drought stress significantly reduces citrus yield by disrupting photosynthesis, affecting water balance, and damaging cellular structure. This research examined the effectiveness of exogenous Ascorbic Acid (AsA) in alleviating drought-related damage in sour orange (Citrus aurantium). Plants were subjected to drought stress (water withholding for 14 days) and foliar sprayed with AsA at concentrations of 0, 125, or 250 mg L- 1. Compared to the control, drought severely reduced photosynthetic pigments and relative water content (RWC), while increasing markers of oxidative damage, including malondialdehyde and markers of membrane damage. Application of AsA, particularly at 250 mg L-1 effectively counteracted these effects, markedly enhancing chlorophyll and carotenoid levels, improving water status and significantly boosting the activity of key antioxidant enzymes (catalase and peroxidase), AsA treatment also promoted the accumulation of osmoprotectants (proline, soluble sugars) and total protein. Correlation analysis revealed strong associations among these parameters, suggesting that AsA may strengthen the positive relationships between antioxidant defense, osmotic adjustment, and membrane stability, which could reflect an integrated physiological response to drought. These results highlight AsA as a cost-effective approach to improve drought resilience in citrus, with potential benefits for sustainable horticulture in water limited environments.

ABSTRACT This paper summarizes the 100-page paper of 1915 by Adolph Meyer on “Computing Run-off from Rainfall” and the 53 pages of rather lively discussion and response that follows. The paper outlines Meyer’s methodology for calculating streamflow using a water balance method at annual, monthly and daily time scales. This includes his embryonic perceptual model of each term of the water balance, which is compared with other papers of the early twentieth century. Meyer’s efforts to provide a means of calculating quantitative estimates of evaporation and transpiration are also recorded. He understood the role of storage in correctly estimating water balance components, but his method of correcting for storage effects is not made clear. Meyer’s paper reveals that some of the problems of applying hydrological models over 100 years ago when computers were people still resonate today.

ABSTRACT Power laws pervade hydrology, partly because of the field’s historical ties to engineering and partly because many natural systems exhibit fractal organization across scales. In 1991, the National Research Council’s Opportunities in the Hydrologic Sciences (“the Eagleson Report”) called for renewed emphasis on hydrologic theory, especially in the areas of scaling and ecological optimality. At the center of this challenge lies the water balance, one of the most fundamental and difficult problems in hydrology. Solving the water balance at subannual time scales requires understanding the coupled physical dynamics of catchments and plant–soil–atmosphere interactions. At longer time scales, the challenge shifts to explaining storage trends and evapotranspiration fluxes in terms of climatic drivers such as precipitation and potential evapotranspiration, while also accounting for ecological controls. This presentation argues that percolation theory is centrally relevant to this “central problem of hydrology.”

The manifestation and allocation of the positive externalities of grassland ecosystem products are critical to realizing the value of ecological compensation. Previous studies on ecological compensation have largely overlooked the heterogeneity of ecosystem products within regions and the differences in compensation among various industrial sectors, particularly the alignment and regulatory role between industrial structure and ecological compensation. In response, this study shifts the focus from interregional horizontal compensation to intraregional structural compensation, emphasizing the rational allocation mechanism of ecosystem product value among different industrial actors. Based on meteorological monitoring data and land-use data, the value of grassland ecosystem products is estimated using the water balance method and soil erosion equations. Furthermore, an inter-industry ecological compensation allocation model is constructed based on the consumption value of grassland ecosystem products and the proportion of industrial structure. The results show that: (1) From 2013 to 2023, none of the four major pastoral regions are required to bear ecological compensation for carbon sequestration and oxygen release consumed by the livestock industry; however, the average ecological compensation surplus decreased from 7.38 × 10⁸ CNY to 7.09 × 10⁸ CNY. (2) Most regions are required to bear ecological compensation for air purification consumed by the industrial sector, while some regions in Inner Mongolia and Xinjiang are also required to compensate for water conservation consumed by industry. (3) No region is required to bear ecological compensation for water conservation and soil retention consumed by the tourism industry; however, regions such as Turpan and Alxa are required to compensate for carbon sequestration and oxygen release consumed by tourism, with the average compensation increasing from 1.35 × 10⁶ CNY to 1.54 × 10⁷ CNY.

Renal function in humans and rodents displays a clear circadian pattern with greater glomerular filtration and excretion during the active period. Vasopressin (AVP) regulates water balance primarily through the vasopressin receptor 2 (V2R). Although both V2R agonists and antagonists are used clinically, it remains unclear whether their efficacy vary by the time of day. Because Avpr2 mRNA expression is greater during the active phase in mice, we hypothesized that V2R agonism and antagonism would produce diurnal effects on urine-concentrating responses. Adult male and female C57BL/6J mice were studied. To suppress endogenous AVP, mice were placed on a high-water gel diet one week before a 10 μg intraperitoneal injection of dDAVP at ZT5 or ZT17 and then samples collected one hour later. dDAVP administered during the active period resulted in a more diluted plasma, reflected by lower plasma osmolality at ZT18. This response associated with increased abundance of AQP2 phosphorylated at S256 and S261 in the outer medulla of the ZT18 mice compared to the ZT6 mice. Thus, dDAVP is more effective during the active period when water intake is greatest and there is enhanced renal filtration and reabsorptive capacity. Conversely, when the V2R was inhibited by tolvaptan, urine flow peaked 2 hours post the injection in the male and female mice, regardless of it was ZT18 or ZT6. However, male mice produced significantly more urine than the female mice in response to the tolvaptan. In conclusion, both time of day and sex significantly influenced renal responses to V2R-targeted therapies.

Stomatal density and aperture dynamics regulate drought response and yield in tomato.

The hypothalamus integrates signals from the body and the environment and coordinates homeostatic responses in multiple physiologic processes including: water balance, stress response, temperature regulation, energy balance, feeding behavior, sleep-wake cycles, and reproduction. Endocrinologists care for individuals for whom hypothalamic injury, whether from tumors, their treatment, or other causes, impairs pituitary hormone production and secretion. The extent of other symptoms in affected individuals is also influenced the extent of hypothalamic injury. "Acquired hypothalamic syndrome" refers to this broader collection of problems attributable to hypothalamic injury, variably including not only pituitary hormone deficiencies, but also hypothalamic obesity (or rarely, diencephalic syndrome), sleep and circadian disruption, temperature dysregulation, and behavioral issues (including memory problems and impulse control). Our goal is to present a pragmatic guide to the multidisciplinary, collaborative evaluation and management of hypothalamic syndrome.

Drought represents a major constraint on global wheat production, and climate projections indicate an increased frequency of drought events with irregular rainfall. While physiological and metabolic adjustments contribute to stress adaptation, the regulatory networks integrating these responses remain poorly understood. Ethylene is a stress hormone, yet its role in coordinating drought resilience across contrasting wheat cultivars has not been systematically investigated. Three wheat cultivars differing in drought resilience were evaluated under water deficit by integrating morphological traits, phytochemical composition, metabolite profiling, and transcriptional regulation of ethylene biosynthesis and signaling genes. Drought stress reduced biomass, chlorophyll content, and growth, while MH-97 maintained stable growth, suggesting better stress resilience and maintained photosynthetic capacity. Metabolite profiling revealed enrichment of organic acids, amino acid derivatives, and phenolics, supporting osmotic regulation and antioxidant defense. Elevated sugar-phosphates and TCA intermediates indicated enhanced energy metabolism, while lipid remodeling, terpenoids, and phenylpropanoid derivatives reinforced membrane stability and redox buffering. Expression profiling showed strong induction of TaACO, TaERS, TaETR, and TaEIN2 genes in both roots and shoots of FSD-08, while MH-97 exhibited restrained ethylene signaling with limited induction of TaEBF1-7B and TaRTE3-5A. Contrasting drought adaptation is linked to differential regulation of ethylene biosynthesis and signaling genes, integrated with physiological and metabolic adjustments to maintain water balance and redox homeostasis. By integrating genetic and metabolic insights with a pathway model, this study not only advances the understanding of ethylene-mediated drought tolerance but also lays the foundation for translating these molecular insights into strategies to enhance crop performance and yield stability in wheat under increasingly variable environmental conditions. Further functional validation and quantitative ethylene measurements will be necessary to confirm mechanistic relationships.

Abstract Quantification of long-term partitioning of precipitation into evaporation and runoff is a fundamental pursuit in catchment hydrology. The Budyko framework provides a theoretical basis for this and estimates the evaporative fraction based on the aridity index. However, deviations from the global-average Budyko curve point to additional controls on precipitation partitioning beyond the aridity index. We hypothesized that root zone storage capacity ( S r,max ), defined as maximum subsurface water volume accessible to vegetation roots, is a key driver of these deviations. The relationship between S r,max and precipitation partitioning in the Budyko space was investigated globally across >5000 catchments. S r,max was calculated using the memory method based on runoff observations and the water balance. The ω-parameter from Fu’s equation, which was used here to construct parametric Budyko curves, reflects deviations from the global-average Budyko curve and hence precipitation partitioning. Results revealed a globally stronger correlation (Spearman’s ρ=0.68) of ω with S r,max , than with other potential controls, indicating S r,max as a dominant driver of precipitation partitioning. Further analysis based on Köppen-Geiger climatic zone classification revealed variations in the S r,max -ω relationship, with the strongest correlations observed in cold (ρ=0.87) and Mediterranean (ρ=0.83) climates, followed by temperate (ρ=0.76), tropical (ρ=0.64) and arid climates (ρ=0.61). Regional differences in S r,max indicate that, at a given aridity, E A P largely reflects vegetation adaptation to the seasonal interplay between water supply and atmospheric water demand. This study provides strong empirical evidence on a global scale for S r,max as a governing factor in modulating catchment precipitation partitioning in the Budyko space, extending previous studies to climates and ecosystems that have in the past received limited attention. As a major implication our results provide a theoretical basis for the maximum values of S r,max found in nature, as constrained by the water and energy limits of the Budyko framework.

Enhanced GABA accumulation and conversion contribute to physiological homeostasis and lipid reprogramming in salt-stressed white clover.

Non-flooding irrigation is widely promoted as a carbon–water co-benefit strategy in paddy rice, but field-scale trials overlook return flow compensation within irrigation districts and therefore overstate water-saving potential. To reconcile this scale mismatch, we developed a semi-distributed multi-scale water balance model coupled with a carbon footprint and full-component blue–green–grey water footprint framework and applied it across field, district, and provincial scales in Heilongjiang Province—a leading cold-region japonica rice region in Northeast China—using the Qinglongshan Irrigation District on the Sanjiang Plain as the focal case, supported by two growing seasons of field observations and 35 years of provincial records. Under alternate wetting and drying, apparent field-level water savings of 50–60% converge to 33% after return flow correction, implying that field-based indicators overestimate savings by 40–50%. Carbon mitigation is decoupled from water volume: CH4 suppression dominates total abatement and is governed by drying frequency rather than water saved. At the provincial scale, the water footprint has shifted from grey- to blue-water dominance, suggesting that blue-water efficiency now represents a principal remaining lever for further cold-region carbon–water co-benefits. Two-season coverage and fixed parameter assumptions affect magnitudes but not directions. Water-saving irrigation in cold-region paddy systems should therefore be evaluated at the district scale where data permit, rather than relying solely on field-scale indicators.

Simulating mediterranean rice paddies’ water balance under climate change scenarios