Water Constraints Research Articles

Effects of Short-Term Water Constraints on Electricity Dispatch: A Case Study of ERCOT and SPP Regions

Effects of Short-Term Water Constraints on Electricity Dispatch: A Case Study of ERCOT and SPP Regions

Knowledge and Technology Used in Capacitive Deionization of Water.

The demand for water and energy in today’s developing world is enormous and has become the key to the progress of societies. Many methods have been developed to desalinate water, but energy and environmental constraints have slowed or stopped the growth of many. Capacitive Deionization (CDI) is a very new method that uses porous carbon electrodes with significant potential for low energy desalination. This process is known as deionization by applying a very low voltage of 1.2 volts and removing charged ions and molecules. Using capacitive principles in this method, the absorption phenomenon is facilitated, which is known as capacitive deionization. In the capacitive deionization method, unlike other methods in which water is separated from salt, in this technology, salt, which is a smaller part of this compound, is separated from water and salt solution, which in turn causes less energy consumption. With the advancement of science and the introduction of new porous materials, the use of this method of deionization has increased greatly. Due to the limitations of other methods of desalination, this method has been very popular among researchers and the water desalination industry and needs more scientific research to become more commercial.

Two stressors are worse than one: combined heatwave and drought affect hydration state and glucocorticoid levels in a temperate ectotherm.

Heatwaves and droughts are becoming more intense and frequent with climate change. These extreme weather events often occur simultaneously and may alter organismal physiology, yet their combined impacts remain largely unknown. Here, we experimentally investigated physiological responses of a temperate ectotherm, the asp viper (Vipera aspis), to a simulated heatwave and drought. We applied a two-by-two factorial design by manipulating the daily temperature cycle (control versus heatwave) and the water availability (water available versus water deprived) over a month followed by exposure to standard thermal conditions with ad libitum access to water. Simulated heatwave and water deprivation additively increased mass loss, while water deprivation led to greater plasma osmolality (dehydration). Mass gain from drinking after the treatment period was higher in vipers from the heatwave and water-deprived group, suggesting that thirst was synergistically influenced by thermal and water constraints. Heatwave conditions and water deprivation also additively increased baseline corticosterone levels but did not influence basal metabolic rate and plasma markers of oxidative stress. Our results demonstrate that a short-term exposure to combined heatwave and drought can exacerbate physiological stress through additive effects, and interactively impact behavioral responses to dehydration. Considering combined effects of temperature and water availability is thus crucial to assess organismal responses to climate change.

Deep Learning model and Classification Explainability of Renewable energy-driven Membrane Desalination System using Evaporative Cooler

Recently, the scientific community has become more interested in solar-driven steam materials and systems for desalination and disinfection. Solar thermal energy for membrane distillation desalination provides a green and sustainable option for building settings where there is a strong connection between water constraint and high solar irradiation. Artificial intelligence (AI) is rapidly being used to optimize water treatments and saltwater desalination because of its high precision and accuracy. Explainable AI (XAI) enables people to better understand and trust a model's predictions and to detect and rectify inaccurate AI predictions. This study analyses recent advances in solar-driven steam materials engineering and the significant technological constraints that impede its wide-scale deployment. Using local interpretable model-agnostic explanations (LIME), our study provides an interpretable solution (in addition to the binary classification result of the developed black-box deep learning (DL) model) so that experts can understand why the machine thinks this way, providing critical insights for the decision-making process. The proposed XAI-DL model is based on a DL network consisting of three cascaded convolutional blocks for processing tabular data. Therefore, the XAI-DL classification model achieves a cooling quality accuracy of 82.64% during the validation stage, supporting the explaining capability. During the testing, the [inlet-cooling-water-temperature] pushes the model lower, whereas the [ambient-temperature], [feed-water-flow-rate], and the [inlet-feed-water-temperature] pushes the model higher. The LIME explanation result is consistent with the statistical analysis of the data. Consequently, the proposed explainer assists non-experts in comparing and improving the untrustworthy model through and clarifies the importance of each feature and its relationship to other features and its relationship to the class. Finally, the XAI-DL fits and supports the different manufacturers of membrane desalination system(s) to inspect cooling quality in their designed system and consistency of interpretability and trust.

Adjustments of carbon allocation and stomatal dynamics by target localized strategies to increase crop productivity under changing climates

Increasing crop productivity to ensure food security for future generations is one of the greatest challenges in current plant research. This challenge is even greater due to global climate changes, as enhancing crop yields must occur against the backdrop of increasingly changing environments, particularly rising temperatures and water constraints. Global crop yield growth depends on an improved dynamic balance between carbon and water usage. Here we discuss different approaches that highlight the role of vascular tissue and guard cells in attempting to mitigate the carbon-water trade-off. We argue that crop engineering in the future will require the incorporation of a combination of improved traits. Since targeted gene modifications generally produce fewer undesirable pleiotropic effects than constitutive modifications, we envision that modifications of specific cell types, such as phloem companion cells and guard cells, represent an effective approach for adding beneficial gene modifications in the same plant. This approach will enable trait stacking to design future crops with both high yield and resilience to various climate change stresses.

Assessment of Climate Change and Human Activities on Vegetation Development in Northeast China.

Vegetation in Northeast China (NEC) has faced dual challenges posed by climate change and human activities. However, the factors dominating vegetation development and their contribution remain unclear. In this study, we conducted a comprehensive evaluation of the response of vegetation in different land cover types, climate regions, and time scales to water availability from 1990 to 2018 based on the relationship between normalized difference vegetation index (NDVI) and the standardized precipitation evapotranspiration index (SPEI). The effects of human activities and climate change on vegetation development were quantitatively evaluated using the residual analysis method. We found that the area percentage with positive correlation between NDVI and SPEI increased with time scales. NDVI of grass, sparse vegetation, rain-fed crop, and built-up land as well as sub-humid and semi-arid areas (drylands) correlated positively with SPEI, and the correlations increased with time scales. The negatively correlated area was concentrated in humid areas or areas covered by forests and shrubs. Vegetation water surplus in humid areas weakens with warming, and vegetation water constraints in drylands enhance. Moreover, potential evapotranspiration had an overall negative effect on vegetation, and precipitation was a controlling factor for vegetation development in semi-arid areas. A total of 53% of the total area in NEC showed a trend of improvement, which is mainly attributed to human activities (93%), especially through the implementation of ecological restoration projects in NEC. The relative role of human activities and climate change in vegetation degradation areas were 56% and 44%, respectively. Our findings highlight that the government should more explicitly consider the spatiotemporal heterogeneity of the influence of human activities and water availability on vegetation under changing climate and improve the resilience of regional water resources. The relative proportions and roles map of climate change and human activities in vegetation change areas provide a basis for government to formulate local-based management policies.

Microsite abiotic conditions and juvenile response under three early successional shrub/tree species in a SEMI‐ARID region

AbstractIn environments with water and nutrient constraints, some early successional shrub/tree species may promote facilitation by ameliorating the microclimate and increasing resource availability. We ask whether early successional semi‐arid shrub/tree species have facilitation effects for other woody species and if they do, which mechanisms are involved and how they affect the water status of juvenile plants. Three early successional woody species; Combretum leprosum, Cenostigma bracteosum and Mimosa tenuiflora, were chosen for investigation. The richness of regenerating woody species and their leaf water potential were used as response variables, while air and soil temperature, leaf area index, humidity and soil attributes were used as explanatory environmental variables. Species growing under the canopy of C. leprosum had better water status and growth at higher soil moisture and lower thermal and solar radiation stress, receiving a facilitative effect. The lower leaf area index, higher radiation and more negative soil water content under the canopy of C. bracteosum in comparison to C. leprosum may have a small negative effect on species richness. M. tenuiflora did not reduce environmental stress, and the species associated with it had low water potential, thus no increase in species richness was detected under its canopy. C. leprosum and C. bracteosum improve the environmental conditions under their canopies and provide favourable microsites for the establishment of other species. The positive effects may be generated by functional traits that modify microclimatic characteristics under the nurse species' canopy and lead to a higher water status of the juveniles growing under it.

Investigating the effects of management of irrigation water distribution on farmers' gross profit under uncertainty: A new positive mathematical programming model

The Middle Eastern countries along with Iran possess an arid to semi-arid climates. For this reason, they encounter many problems in water supply and distribution within different sectors, especially agriculture. Hence, it is necessary to achieve some strategies for optimal, efficient and fair use of water supplies and irrigation grids to manage water allocation and distribution for irrigation in agricultural sector to reduce water wastes. To this end, the present study mainly aims to formulate a model for optimal water distribution for irrigation under uncertain conditions and the impact of water redistribution on the gross profit of farmers. In this study, positive mathematical programming was used and for applying uncertainty in water transfer model, robust optimization method was utilized. A combination of these two methods led to invention of a robust positive mathematical programming (RPMP) model. Tajan Irrigation and Drainage Network in northern Iran was selected as a case study to evaluate the ability of the proposed model. The results showed that with the increase in the probability of deviation (p) of the available water constraint, area under cultivation of all the selected crops decreases, and this can reduce production ultimately declining farmers' gross profits. Also, as the probability level (p) increases, amount of water transfer from upstream to downstream of irrigation and drainage network increases. Thus, cultivation structure should be mitigated for farming crops in order to prevent from reduced profit for farmers. The results of Monte Carlo Simulation indicated that using results of RPMP model were reliable and it might noticeably contribute to changing cultivation pattern.

Unravelling the responses of different apple varieties to water constraints by continuous field thermal monitoring

This research aimed at analyzing the response of apple tree varieties subjected to soil water deficit and atmospheric drought in a field phenotyping platform located in the Mediterranean area. The main assumption of the study was that seasonal and daily stomatal behavior can be monitored by continuous measurement of canopy surface temperature (Ts) as a proxy of stomatal closure. To achieve the study objectives, thermal monitoring of 6 pre-commercial apple varieties was simultaneously carried out throughout one season by nadir-oriented thermo-radiometers placed 1.50 m over the tree top canopy. Two water regimes were applied to each variety during a 4-week summer period: normal irrigation (WW) vs progressive water deficit (WS). The maximum difference in Ts between water regimes was recorded daily between 11:00 and 14:20 GMT, with an earlier closure of stomata in WS trees. During the day, a more negative stem water potential (Ψstem) and a higher diurnal Ts (+1° to +2 °C) were observed on WS trees, resulting in a significant limitation of fruit growth. Tree water stress was caused by both edaphic and atmospheric droughts, in the medium and short terms respectively, with inter-varietal and inter-regime differences highlighting distinct stomatal closure behaviors. Results suggest that some of the varieties studied are well adapted to stressful summer conditions, as long as irrigation needs are met, while other varieties show a particular sensitivity to the mid-day evaporative demand, which may limit their extension. Although these results are not comprehensive enough to predict the optimal performance of varieties under different stress scenarios, the proposed methodology allows to assess the dynamics of tree response to water constraints using non-invasive thermal sensors. It opens up new perspectives for the phenotyping of apple cultivars under abiotic stress, achievable through the quantified study of their transpiration flux in response to stress scenarios. These prospects will require further in planta measurements to dissect varietal differences.

Discrepancy in growth resilience to drought among different stand-aged forests declines going from a semi-humid region to an arid region

The growth resilience of forests to extreme drought event has become an urgent topic in global change ecology because of exacerbated water constraints upon trees’ growth over the last few decades. Yet, surprisingly little is empirically known about the contribution of stand age, a key factor influencing forest structure and ecological processes, to variation in growth resilience among stands. This study revealed discrepancies in the drought resilience of forests of different stand ages by analyzing an extensive tree-ring dataset from Qinghai spruce (Picea crassifolia Kom.), a typical moisture-sensitive tree species in northwestern China. We found that older growth Qinghai spruce forest stands have higher resistance to droughts than do younger growth ones. Conversely, however, the post-drought recoveries of these older growth forest stands are lower than those of the younger growth stands. Patterns in the variation of resilience indices were consistent between two contrasting hydrological niche regions, whereas the stand age-related discrepancies in drought resilience became significantly smaller going from the wetter region to the drier region. These findings imply that, instead of a “one-size-fits-all” strategy, more meticulous and more targeted strategies are needed to enhance forest management and strengthen forest conservation given the experienced and projected climate trends, which feature increasing precipitation but higher extreme-drought frequency across this spruce tree’s habitat and distribution in northwestern China.

Farmers’ Attitudes towards Irrigating Crops with Reclaimed Water in the Framework of a Circular Economy

In a global situation where water constraints are a daily concern and expected to worsen in the upcoming years, finding new water alternatives to guarantee its supply is of critical importance. Against this background, reclaimed water has proved to be a sustainable alternative that recycles wastewater from a circular economy approach, thus enhancing water availability for key sectors such as agriculture. In such a context where public policies should encourage the implementation of this sustainable resource that helps reduce climate change by allowing wastewater reuse, there is too often a lack of knowledge of farmers’ perceptions, thus resulting in them being ineffective. In this sense, studying and analyzing agriculturalists’ perceptions is of interest for the development of appropriate policies that truly foster reclaimed water use in agriculture and enhance its shift from waste to resource. For this research 231 farmers, both long-time users of reclaimed water and non-users, were surveyed to find common and differing attitudes and perceptions. Results show how once farmers start irrigating their crops with this alternative resource there is a marked improvement in their opinion. The high price is the most widespread barrier, which can be tempered with public subsidies that absorb part of this cost. The insights obtained from this research may be of interest to other regions, especially for those in arid and semi-arid climates where water scarcity is a critical problem and sustainability a growing concern.

Reproductive colonization of land by frogs: Embryos and larvae excrete urea to avoid ammonia toxicity.

Vertebrate colonization of land has occurred multiple times, including over 50 origins of terrestrial eggs in frogs. Some environmental factors and phenotypic responses that facilitated these transitions are known, but responses to water constraints and risk of ammonia toxicity during early development are poorly understood. We tested if ammonia accumulation and dehydration risk induce a shift from ammonia to urea excretion during early stages of four anurans, from three origins of terrestrial development. We quantified ammonia and urea concentrations during early development on land, under well‐hydrated and dry conditions. Where we found urea excretion, we tested for a plastic increase under dry conditions and with ammonia accumulation in developmental environments. We assessed the potential adaptive role of urea excretion by comparing ammonia tolerance measured in 96h‐LC50 tests with ammonia levels in developmental environments. Ammonia accumulated in foam nests and perivitelline fluid, increasing over development and reaching higher concentrations under dry conditions. All four species showed high ammonia tolerance, compared to fishes and aquatic‐breeding frogs. Both nest‐dwelling larvae of Leptodactylus fragilis and late embryos of Hyalinobatrachium fleischmanni excreted urea, showing a plastic increase under dry conditions. These two species can develop the longest on land and urea excretion appears adaptive, preventing their exposure to potentially lethal levels of ammonia. Neither late embryos of Agalychnis callidryas nor nest‐dwelling larvae of Engystomops pustulosus experienced toxic ammonia levels under dry conditions, and neither excreted urea. Our results suggest that an early onset of urea excretion, its increase under dry conditions, and elevated ammonia tolerance can all help prevent ammonia toxicity during terrestrial development. High ammonia represents a general risk for development which may be exacerbated as climate change increases dehydration risk for terrestrial‐breeding frogs. It may also be a cue that elicits adaptive physiological responses during early development.

Evaluation and management of soil microbial potentialities for improving the carob tree tolerance to water constraints

The carob tree (Ceratonia siliqua L.), an ecological, cultural and industrial component of the Mediterranean basin, has been experiencing a decline of its abundance in recent decades. Three contributing factors have been identified, an agricultural policy in favour of other plant species, an increasing urbanisation of the Mediterranean coastline, which leads to habitat fragmentation, and negative climatic conditions, notably longer periods of drought. The dependency of the carob tree on water resources is an underestimated trait, and yet a crucial one for its survival. The optimisation of the symbiotic association between carob and mycorrhizal fungi has been proposed as a promising strategy to improve its resistance to water stress. However, a more holistic view of plant-microorganism interactions within the environment seems essential to sustainably address the challenges of plant adaptation to environmental stresses. The central hypothesis of the thesis is that the management of interactions between the carob tree and the microbiota of some pioneer plants in its habitat could be the key for a better adaptation of the carob tree to drought. The objectives were (i) to assess the specificity of microbiota associated with plants living with the carob, and (ii) to quantify their impact on carob growth and resistance to water deficit. The results showed a predominance of actinobacteria, proteobacteria and ascomycetes in the studied habitats, with significant functional divergences between North and South of Morocco. Common garden experiments revealed that the type of microbiota was a major driver of the effect on carob growth and resistance, with strong variations depending on the water status. Indeed, the native microbiota of the carob tree is one of the most efficient under non-limiting water conditions but confers little resistance to drought. On the other hand, the microbiota associated with the lentisk provides the best growth-resistance trade-off. This benefit seems to be attributable to a higher abundance of DSE (dark septate endophytes) fungi and an increase in mycorrhizal colonisation in response to water stress. The integration of lentisk in technical practices as a lever for the management of a beneficial microbiota could therefore represent a future strategy for the adaptation of carob to increasing drought in the Mediterranean basin.

Determining a Midday Stem Water Potential Threshold for Irrigation of Table Grapes Water potential threshold

Sustainable table grape production depends on efficient water supply. Water potential is a useful indicator of water constraints in grapevines. In this regard, midday stem water potential (ΨS) is considered to be a better indicator of grapevine water status than leaf water potential (ΨL). The objective of the study was to determine a water potential threshold to set soil water refill lines for table grape irrigation. However, in previous studies carried out locally, only ΨL was measured. The relationship between ΨS and ΨL was determined for ten selected table grape cultivars. Since there were no differences between cultivars, a single equation could be used to convert midday ΨL measured in previous studies with table grapes to ΨS. Vegetative growth, berry mass and colour, as well as juice total soluble solids (TSS) data were pooled, and related to midday ΨS. This showed that -0.8 MPa seems to be a ΨS threshold for water constraints in the pre-harvest period that will allow sustainable growth and berry size for anisohydric table grape cultivars. The optimum ΨS for berry colour is between -0.8 MPa and -1.0 MPa. Consequently, a midday ΨS threshold of -0.8 MPa can be used to set refill points for irrigation where soil water content is measured on a regular basis in table grape vineyards.

Irrigation water use pattern and constraints faced by the farmers in Punjab

Irrigation water use pattern and constraints faced by the farmers in Punjab

A decision model for stochastic optimization of seasonal irrigation-water allocation

Optimal water allocation on a seasonal basis is generally a decision taken with uncertainty regarding seasonal crop needs (unknown yield, precipitation and other environmental factors). Decision criteria, such as “irrigating for the good years of production” and "applying a little extra water just in case it is needed by the plant", are consistent with the rational behaviour of stochastic profit maximization. The motivation behind an increase in water allocation (acquiring water rights or reserving water for certain crops) is that of self-protection: it is better to maintain an extra allocation of water than to face potential yield losses due to water constraints on production in those years when potential yields exceed average levels. The stochastic optimization model presented herein is applied to maize in Spain showing that in current economic and technical conditions, the optimal stochastic water allocation under yield uncertainty is 10% higher than the irrigation dose required under certainty (historical average yield), which leads to an 8% higher expected profit than that obtained for an average-yield water application.

Methodology and meaning of computing heat flux via atomic stress in systems with constraint dynamics

Reliably obtaining thermal properties of complex systems, which often involves computing heat flux to obtain thermal conductivity via either Fourier’s law or the Green–Kubo relation, is an important task in modern molecular dynamics simulations. In our previous work [Surblys et al., Phys. Rev. E 99, 051301(R) (2019)], we have demonstrated that atomic stress could be used to efficiently compute heat flux for molecules with angle, dihedral, or improper many-body interactions, provided a newly derived “centroid” form was used. This was later successfully implemented in the LAMMPS simulation package. On the other hand, small rigid molecules, like water and partial constraints in semi-flexible molecules, are often implemented via constraint force algorithms. There has been a lack of clarification if the constraint forces that maintain geometric constraints and can also be considered as many-body forces contribute to the overall heat flux and how to compute them correctly and efficiently. To address this, we investigate how to apply the centroid atomic stress form to reliably compute heat flux for systems with constraint or rigid body dynamics. We successfully apply the centroid atomic stress form to flexible, semi-flexible, and rigid water models; decompose the computed thermal conductivity into separate components; and demonstrate that the contribution from constraint forces to the overall heat flux and thermal conductivity is small but non-negligible. We also show that while the centroid formulation produces correct heat flux values, the original “group” formulation produces incorrect and sometimes unphysical results. Finally, we provide insight into the meaning of constraint force contribution.

Scheduling coordination of back pressure CHP coupled electricity-heat energy system with adaptive constraint strategy to accommodate uncertain wind power

A scheduling coordination approach with adaptive constraint strategy is proposed for electricity-heat integrated energy system (IES). The approach takes full advantage of heat network flexibility to smooth uncertain wind power and its natural storage capability to improve operational economics. Transmission dynamics of heating network is modeled by describing the heat dissipation in radial direction toward the insulation layer and the heat propagation in axial direction through water flow. Dynamical heating flow and steady power flow with different timescales are integrated to constitute the coordinated scheduling optimization by energy coupling component, i.e. CHP (combined heat and power) unit. In order to mitigate the discrepancy between the predicted and real values of wind power by utilizing the allowed upper limit of water temperature constraint violation, a PID idea based closed-loop adaptive adjustment strategy is implemented on the water temperature constraint at the beginning of supply pipeline. Simulations are conducted to show that in the proposed coordinated scheduling approach, heat network can serve as a natural energy storage to achieve the economic operation of IES, and simultaneously wind power uncertainties can be smoothed by the flexible temperature constraint of water flowing in heat network, with no any probability distribution information of uncertainties needed.

Techno-economic analysis and comparison of coal-based chemical technologies with consideration of water resources scarcity

Existing techno-economic analyses of modern coal chemical technologies (MCCTs) neglect water constraints, which may underestimate the production cost of MCCTs and thus mislead investment activities. Considering this background, this study incorporated water scarcity and indirect water cost into a classic techno-economic evaluation model of MCCT. Using this model, our work evaluated and compared the techno-economic indicators with the latest data for four typical MCCTs, including coal-to-liquids (CTL), synthetic natural gas (SNG), coal-to-olefin (CTO), and coal-to-ethylene glycol (CTEG). The results demonstrate the following: 1) The production costs of CTL, SNG, CTO, and CTEG are 5185 CNY/t, 2653 CNY/kNm3, 5918 CNY/t, 4055 CNY/t, respectively. Under the current prices of oil-related products, investment in SNG and CTEG would be risky, investment in CTL should be considered cautiously, and investment in CTO could lead to a profit. 2) Under the current market price of water resources, which does not consider the water constraint of MCCTs, the production cost would be underestimated by at most 12.4% for CTL, 10.6% for SNG, 27.5% for CTO, and 32.4% for CTEG. The sensitivity of the results to some key parameters and investment recommendations considering profitability, capital investment, material consumption, water constraints, and CO2 emissions are also discussed and provided.

Resilience-Motivated Distribution System Restoration Considering Electricity-Water-Gas Interdependency

A major outage in the electricity distribution system may affect the operation of water and natural gas supply systems, leading to an interruption of multiple services to critical customers. Therefore, enhancing resilience of critical infrastructures requires joint efforts of multiple sectors. In this paper, a distribution system service restoration method considering the electricity-water-gas interdependency is proposed. The objective is to provide electricity, water, and natural gas supplies to critical customers in the desired ratio according to their needs after an extreme event. The operational constraints of electricity, water, and natural gas networks are considered. The characteristics of electricity-driven coupling components, including water pumps and gas compressors, are also modeled. Relaxation techniques are applied to nonconvex constraints posed by physical laws of those networks. Consequently, the restoration problem is formulated as a mixed-integer second-order cone program, which can readily be solved by the off-the-shelf solvers. The proposed method is validated by numerical simulations on electricity-water-gas integrated systems, developed based on benchmark models of the subsystems. The results indicate that considering the interdependency refines the allocation of limited generation resources and demonstrate the exactness of the proposed convex relaxation.