Evaporative Loss Research Articles

Bromeliad rosettes as shelters for hylid treefrogs during a heat wave in the Brazilian Pantanal

During a heat wave in November 2023, we assessed the use of bromeliad rosettes as shelters for hylid treefrogs in the Brazilian Pantanal (area of Nhecolândia). During the day time, four hylid species (genera Boana, Scinax, Trachycephalus) were detected sheltering in 40 rosettes of the terrestrial bromeliad Bromelia balansae; this was a different species complex from when observations were made in October 2019 when the temperature conditions corresponded to long-term averages. The internal and external day time temperature of each shelter was measured. The mean daytime temperature inside the shelters was 36.1 °C (range 24.0–43.5 °C), this varied depending on the microhabitat conditions, and was 1.1 °C lower than the mean temperature of the leaves of the upper part of the rosettes; the difference was statistically significant. We suggest that during this very dry and hot period the main advantage provided by the bromeliad shelters was to enable frogs to have behavioural control of overheating so that they could avoid excessive evaporative water loss.

Validation of livability environmental limits to heat and humidity.

Rising global temperatures, driven by climate change, pose a threat to human health and regional livability. Empirical data and biophysical model derived estimates suggest that the critical environmental limits (CEL) for livability are dependent on ambient temperature and humidity. We use a well-validated, physiology-based, six-cylinder thermoregulatory model (SCTM) to independently derive CELs during sustained minimal, light, and moderate activity across a broad range of ambient temperatures and humidity levels and compare to published data. The activity and environments were considered livable if predicted core temperatures did not reach 38±0.25°C within six hours. The outcomes for minimal activity revealed CELs ranging from 34°C/95% RH to 50°C/5% RH. Corresponding dry heat losses ranged from 14 W·m-2 and -72 W·m-2 (negative = heat gain) and evaporative heat losses ranged from 39 W·m-2 to 104 W·m-2. The wet bulb temperature (Twb) at the CELs ranged from 33.3 to 20.9°C. Activity shifted CELs toward lower temperatures and humidities. Importantly, our predicted CELs largely agree with observed livability CELs from physiology and those from a biophysical model. The physiology-grounded SCTM has utility for assessing the impact of climate change on regional livability.

Movement Characteristics of Droplet Deposition in Flat Spray Nozzle for Agricultural UAVs

At present, research on aerial spraying operations with UAVs mainly focuses on the deposition outcomes of droplets, with insufficient depth in the exploration of the movement process of droplet deposition. The movement characteristics of droplet deposition as the most fundamental factors affecting the effectiveness of pesticide application by UAVs are of great significance for improving droplet deposition. This study takes flat spray nozzles as the research object, uses the Particle Image Velocimetry (PIV) technique to obtain movement data of water droplet deposition under the influence of rotor flow fields, and investigates the variation characteristics of droplet deposition speed under different influencing factors. The results show that the deposition speed and the distribution area of high-speed (>12 m/s) particles increase with the increase of rotor speed, spraying pressure, and nozzle size. When the rotor speed increases from 0 r/min to 1800 r/min, the average increase in maximum droplet deposition speed for nozzle models LU120-02, LU120-03 and LU120-04 is 33.26%, 19.02%, and 7.62%, respectively. The rotor flow field significantly increases the number of high-speed droplets, making the dispersed droplet velocity distribution more concentrated. When the rotor speed is 0, 1000, 1500, and 1800 r/min, the average decay rates of droplet deposition speed are 36.72%, 20.00%, 15.47%, and 13.21%, respectively, indicating that the rotor flow field helps to reduce the decrease in droplet deposition speed, enabling droplets to deposit on the target area at a higher speed, reducing drift risk and evaporation loss. This study’s results are beneficial for revealing the mechanism of droplet deposition movement in aerial spraying by plant protection UAVs, improving the understanding of droplet movement, and providing data support and guidance for precise spraying operations.

Exploring the effect of clothing moisture content on heat and moisture transfer from the human body using a sweating thermal manikin

Evaporative heat loss is an important component of the human body's energy balance and several developed thermal comfort models are available to assess heat and mass transfer during human sweating. However, the impact of sweat-soaked clothing due to human perspiration on heat and moisture transfer from the body remains understudied. In this study, the thermal and moisture properties of typical summer clothing were evaluated and moisture adsorption and desorption curves were obtained. The heat losses of the human body in different sweating states were compared using a sweating thermal manikin. It was found that the clothing moisture content and the clothing coverage ratio had a significant effect on the human body heat loss. As the sweating rate increases, additional resistances of the sweat moisture transfer will be added in the sweat-soaked clothing, which would adversely affect the skin temperature. The results show that the total thermal resistance of fully wetted clothing decreased by an average of almost 30% compared to dry clothing ensembles. To account for such differences, the clothing thermal and evaporative resistance, along with the temperature and vapor pressure at varying moisture contents were evaluated and predicted with empirical equations. This enables integrating a dynamic heat and moisture transfer model for the sweat-soaked clothing into a prevailing thermo-physiological model. Accounting for real clothing physical parameters is vital when evaluating thermal comfort in hot and humid weather conditions.

Effect of Using Polyethylene Plastic Bags against Increased and Stable Body Temperature in Low Birth Weight Babies (LBW) in the Nicu Room of SLG Kediri Hospital

Background: Low Birth Weight Babies often experience unstable body temperature which tends to be low/hypothermia. The method to prevent hypothermia is to use polyethylene plastic bags. Purpose: The aim of this study was to analyze the effect of using polyethylene plastic bags in the increase and stability of body temperature in LBW in the NICU room at SLG Kediri Hospital. Method: The design of this study was Quasy Experimental, using Pre Test and Post Test approaches. Sampling by Accidental Sampling. This study was conducted on 30 BBLR babies with a weight of < 2500 grams. Data collection through observation sheets with the time of conducting research in November-December 2023 in the NICU room of SLG Kediri Hospital. Data analysis used to test the influence of two variables in this study is the Wilcoxon. Results: It is known that the pre-test body temperature before the intervention using polyethylene plastic bags was < 36.5 ℃ for 28 out of 30 respondents (93%). And those who experienced an increase and stability in body temperature were 26 respondents (87%), and 4 respondents did not experience an increase and stability in body temperature. The statistical test in this study used the Wilcoxon test, the results of this statistical test obtained the Asymp value. Sig = 0.000. Conclusion: It can be concluded that the hypothesis is accepted. This means that there is a difference between the results of body temperature measurements for the pre-test and post-test. So it can be concluded that there is an influence of the use of polyethylene plastic bags on the increase and stability of body temperature in low birth weight (LBW) babies in the NICU room at SLG Kediri Hospital. The use of polyethylene plastic bags appropriately can reduce evaporation and heat loss. Plastic as a thermoplastic polymer group can prevent heat loss caused by evaporation and radiation, so as to increase the baby's temperature. In this study the baby was still placed in the incubator.

Cuticular hydrocarbons promote desiccation resistance by preventing transpiration in D. melanogaster.

Desiccation is a fundamental challenge confronted by all terrestrial organisms, particularly insects. With a relatively small body size and large surface-to-volume ratio insects are susceptible to rapid evaporative water loss and dehydration. To counter these physical constraints, insects have acquired specialized adaptations, including a hydrophobic cuticle that acts as a physical barrier to transpiration. We previously reported that genetic ablation of the oenocytes - specialized cells required to produce cuticular hydrocarbons (HCs) - significantly reduced survivorship under desiccative conditions in the fruit fly, Drosophila melanogaster. Although increased transpiration - resulting from the loss of the oenocytes and HCs - was hypothesized to be responsible for the decrease in desiccation survival, this possibility was not directly tested. Here we investigate the underlying physiological mechanisms contributing to the reduced survival of oenocyte-less (oe-) flies. Using flow-through respirometry we show that oe- flies, regardless of sex, exhibited an increased rate of transpiration relative to wild-type controls, and that coating oe- flies with fly-derived HC extract restored the rate to near wild-type levels. Importantly, total body water stores, including metabolic water reserves, as well as dehydration tolerance, measured as the percent of total body water lost at time of death, were largely unchanged in oe- flies. Together, our results directly demonstrate the critically important role played by the oenocytes and cuticular HCs to promote desiccation resistance.

Spatial distribution of remaining movable and non-movable oil fractions in a depleted Maastrichtian chalk reservoir, Danish North Sea: Implications for CO2 storage

Depleted oil and gas fields constitute potentially important storage sites for CO2 in the subsurface, but large-scale injection of supercritical (sc) CO2 in chalk has not yet been attempted. One of the risks is the adverse effect of the substantial amount of remaining oil in the chalk reservoirs on scCO2 injection. In order to counter an undesired effect on injectivity, a fundamental understanding of the spatial distribution and quantity of the movable, semi-movable, and non-movable oil, and solid bitumen/asphaltenes fractions of the remaining oil is critical. In this study a combination of organic geochemistry (gas chromatography of the saturated fraction and programmed pyrolysis), and reflected light microscopy was applied to evaluate and measure the spatial distribution, volume, and saturation of different oil fractions in a well-defined reservoir interval of a waterflooded Maastrichtian chalk reservoir in the Danish Central Graben, North Sea. A total of 127 samples from a slightly deviated vertical well and two ∼5 km-long horizontal wells from the Halfdan and Dan fields were analyzed. An original uneven distribution of oil saturation and composition or different production efficiency of different levels in the reservoir may account for variations in the total oil and oil fraction saturations. Gas chromatography shows that the solvent extractable oil is quite similar in composition, characterized by a dominance of polar compounds and a high content of asphaltenes. Extended slow heating (ESH) pyrolysis reveals that most of the remaining oil saturation consists of semi-movable oil and total non-movable oil (non-movable oil plus solid bitumen/asphaltenes). Reduced oil gravity values (API) are related to evaporation loss of the lightest hydrocarbon fraction during core storage and increase of the relative proportion of the heavier oil fractions by waterflooding during production. Microscopy disclosed three forms of oil: i) Patchy distributed lighter, movable oil showing a bluish fluorescence, ii) Brownish staining with a dark orange to brownish fluorescence, and iii) Dark brown non-fluorescing oil and black solid bitumen/asphaltenes occurring in microfossils and along deformation bands and stylolites, constituting the heavy non-movable oil fractions. There is a general correlation between bulk rock porosity and the total non-movable oil saturation. It thus appears that the heavy non-movable oil fractions preferentially occur in association with low-permeability heterogeneities within high-permeability stratigraphic intervals. These intervals appear to favor accumulation of non-movable oil and solid bitumen/asphaltenes and may carry a higher risk for impeding scCO2 flow.

HOUSING TEMPERATURE ALTERS BURN INDUCED HYPERMETABOLISM IN MICE.

Mice used in biomedical research are typically housed at ambient temperatures (22-24 °C) below thermoneutrality (26-31 °C). This chronic cold stress triggers a hypermetabolic response that may limit the utility of mice in modeling hypermetabolism in response to burns. To evaluate the effect of housing temperature on burn-induced hypermetabolism, mice were randomly assigned to receive sham, small, or large scald burns. Mice recovered for 21 days in metabolic phenotyping cages at 24 °C or 30 °C. Regardless of sex or sham/burn treatment, mice housed at 24 °C had greater total energy expenditure (TEE, P < 0.001), which was largely attributable to greater basal energy expenditure (BEE) when compared to mice housed at 30 °C (P < 0.001). Thermoneutral housing (30 °C) altered adipose tissue mass in a sex-dependent manner. Compared to sham and small burn groups, large burns resulted in greater water vapor loss, regardless of housing temperature (P < 0.01). Compared to sham, large burns resulted in greater BEE and TEE in mice housed at 24 °C, however, this hypermetabolic response to large burns was blunted in female mice housed at 30 °C, and absent in male mice housed at 30 °C. Locomotion was significantly reduced in mice with large burns compared to sham and small burn groups, irrespective of sex or housing temperature (P < 0.05). Housing at 30 °C revealed sexual dimorphism in terms of the impact of burns on body mass and composition, where males with large burns displayed marked cachexia, whereas females did not. Collectively, this study demonstrates a sex-dependent role for housing temperature in influencing energetics and body composition in a rodent model of burn trauma.

Physiological costs of warning: Defensive hissing increases metabolic rate and evaporative water loss in a venomous snake

To minimize predation risk and the cost of confronting predators, prey have developed a range of defensive strategies and warning signals. Although advantageous, defensive warnings may also induce physiological and energy costs to the emitter. Ventilatory sounds (hissing) are the most distributed warning sound in vertebrates. Because they involve the respiratory apparatus, defensive hissing may substantially increase evaporative water loss. Herein, we examined the determinants of hissing as well as its physiological costs in a medium-sized venomous snake, the long-nosed viper (Vipera ammodytes). We first used a neutral arena and applied standardized stimulation to measure the occurrence and acoustic characteristics of warning hissing. Then, we used open-flow respirometry to quantify changes in respiratory gas exchanges (oxygen consumption and evaporative water loss) during defensive responses. We demonstrated that males are more likely to engage in sound warnings when stimulated. Expirations generated the strongest signals compared to inspiration but did not differ between sexes. We found that defensive hissing dramatically increased average metabolic rate and evaporative water loss during the 10-minute stimulation period, and this effect was more pronounced in males. Metabolic rates and evaporative water loss were closely related to the duration of hissing. Overall, our results indicate that respiratory-based warning sounds induce significant physiological costs and may alter water balance. The higher responsiveness in males than females likely reflects sexually selective pressure (higher mobility for mate acquisition) and enhanced risk exposure.

Computational Modelling of the Impact of Evaporation on In-Vitro Dermal Absorption

PurposeVolatiles are common in personal care products and dermatological drugs. Determining the impact of evaporation of volatiles on skin permeation is crucial to evaluate and understand their delivery, bioavailability, efficacy and safety. We aim to develop an in-silico model to simulate the impact of evaporation on the dermal absorption of volatiles.MethodThe evaporation of volatile permeants was modelled using vapour pressure as the main factor. This model considers evaporation as a passive diffusion process driven by the concentration gradient between the air-vehicle interface and the ambient environment. The evaporation model was then integrated with a previously published physiologically based pharmacokinetic (PBPK) model of skin permeation and compared with published in vitro permeation test data from the Cosmetics Europe ADME Task Force.ResultsThe evaporation-PBPK model shows improved predictions when evaporation is considered. In particular, good agreement has been obtained for the distributions in the evaporative loss, and the overall percutaneous absorption. The model is further compared with published in-silico models from the Cosmetics Europe ADME Task Force where favourable results are achieved.ConclusionThe evaporation of volatile permeants under finite dose in vitro permeation test conditions has been successfully predicted using a mechanistic model with the intrinsic volatility parameter vapour pressure. Integrating evaporation in PBPK modelling significantly improved the prediction of dermal delivery.

The Pivotal Role of Evaporation in Lake Water Isotopic Variability Across Space and Time in a High Arctic Periglacial Landscape

AbstractRapidly changing climate is disrupting the High Arctic's water systems. As tracers of hydrological processes, stable water isotopes can be used for high quality monitoring of Arctic waters to better reconstruct past changes and assess future environmental threats. However, logistical challenges typically limit the length and scope of isotopic monitoring in High Arctic landscapes. Here, we present a comprehensive isotopic survey of 535 water samples taken in 2018 and 2019 of the lakes and other surface waters of the periglacial Pituffik Peninsula in far northwest Greenland. The δ18O, δ2H, and deuterium‐excess values of these samples, representing 196 unique sites, grant unprecedented insight into the environmental drivers of the regional hydrology and water isotopic variability. We find that the spatial variability of lake water isotopes can best be explained through evaporation and the hydrological ability of a lake to replace evaporative water losses with precipitation and snowmelt. Temporally, summer‐long evaporation can drive lake water isotopes beyond the isotopic range observed in precipitation, and wide interannual changes in lake water isotopes reflect annual weather differences that influenced evaporation. Following this, water isotope samples taken at individual times or sites in similar periglacial landscapes may have limited regional representativeness, and increasing the spatiotemporal extent of isotopic sampling is critical to producing accurate and informative High Arctic paleoclimate reconstructions. Overall, our survey highlights the diversity of isotopic compositions in Pituffik surface waters, and our complete isotopic and geospatial database provides a strong foundation for future researchers to study hydrological changes at Pituffik and across the Arctic.

Modeling High Pan Evaporation Losses Using Support Vector Machine, Gaussian Processes, and Regression Tree Models

Modeling High Pan Evaporation Losses Using Support Vector Machine, Gaussian Processes, and Regression Tree Models

Quantitative investigation of temperature-dependent bound water degeneration in bentonite clays

Temperature increases in saturated clay alter the physicochemical clay-water interactions and may lead to the conversion of bound water into free water. These changes significantly influence the physical, chemical, and engineering properties of clays, which are critical for geotechnical and geological engineering and minimizing risks in areas with expansive clay soils. However, quantifying this phenomenon remains challenging in the literature. This study presents a robust experimental approach for quantifying the thermal-induced conversion of bound water in clays, providing valuable insights into the mechanisms governing their thermo-mechanical behavior. A novel experimental method is proposed to quantify the degenerated bound water content in a clay system subjected to temperatures ranging from 20 to 50 °C. The research employs the siphon principle to examine volume changes in a clay system at elevated temperatures, focusing on measuring the conversion of bound water to free water. This method accounts for thermal expansion of both the soil constituents and the confining glass cylinder, as well as potential evaporation losses. To validate the setup's accuracy, a calibration test using standard Ottawa sand with negligible bound water was performed. After measuring system error, the primary outcome was calibrated. Results showed that at 30 °C, 40 °C, and 50 °C, 3 %, 9 %, and 15 % of the initial bound water, respectively, converted to free water.

Fe, Zn, and Mg stable isotope systematics of acapulcoite lodranite clan meteorites

AbstractThe processes of planetary accretion and differentiation, whereby an unsorted mass of primitive solar system material evolves into a body composed of a silicate mantle and metallic core, remain poorly understood. Mass‐dependent variations of the isotope ratios of non‐traditional stable isotope systems in meteorites are known to record events in the nebula and planetary evolution processes. Partial melting and melt separation, evaporation and condensation, diffusion, and thermal equilibration between minerals at the parent body (PB) scale can be recorded in the isotopic signatures of meteorites. In this context, the acapulcoite–lodranite meteorite clan (ALC), which represents the products of thermal metamorphism and low‐degree partial melting of a primitive asteroid, is an attractive target to study the processes of early planetary differentiation. Here, we present a comprehensive data set of mass‐dependent Fe, Zn, and Mg isotope ratio variations in bulk ALC species, their separated silicate and metal phases, and in handpicked mineral fractions. These non‐traditional stable isotope ratios are governed by mass‐dependent isotope fractionation and provide a state‐of‐the‐art perspective on the evolution of the ALC PB, which is complementary to interpretations based on the petrology, trace element composition, and isotope geochemistry of the ALC. None of the isotopic signatures of ALC species show convincing co‐variation with the oxygen isotope ratios, which are considered to record nebular processes occurring prior to the PB formation. Iron isotopic compositions of ALC metal and silicate phases broadly fall on the isotherms within the temperature ranges predicted by pyroxene thermometry. The isotope ratios of Mg in ALC meteorites and their silicate minerals are within the range of chondritic meteorites, with only accessory spinel group minerals having significantly different compositions. Overall, the Mg and Fe isotopic signatures of the ALC species analyzed are in line with their formation as products of high‐degree thermal metamorphism and low‐degree partial melting of primitive precursors. The δ66/64Zn values of the ALC meteorites demonstrate a range of ~3.5‰ and the Zn is overall isotopically heavier than in chondrites. The superchondritic Zn isotopic signatures have possibly resulted from evaporative Zn losses, as observed for other meteorite parent bodies. This is unlikely to be the result of PB differentiation processes, as the Zn isotope ratio data show no covariation with the proxies of partial melting, such as the mass fractions of the platinum group and rare earth elements.

Seasonal and between-population variation in heat tolerance and cooling efficiency in a Mediterranean songbird

Discrete populations of widely distributed species may inhabit areas with marked differences in climatic conditions across geographic and seasonal scales, which could result in intraspecific variation in thermal physiology reflecting genetic adaptation, phenotypic plasticity, or both. However, few studies have evaluated inter-population variation in physiological responses to heat. We evaluated within- and inter-population seasonal variation in heat tolerance, cooling efficiency and other key thermoregulatory traits in two Mediterranean populations of Great tit Parus major experiencing contrasting thermal environments: a lowland population subject to hotter summers and a higher annual thermal amplitude than a montane population. Specifically, we measured heat tolerance limits (HTL), body temperature, resting metabolic rate, evaporative water loss, and evaporative cooling efficiency (the ratio between evaporative heat loss to metabolic heat production) within and above the thermoneutral zone during winter and summer. Heat tolerance during summer was greater in lowland than in montane birds; indeed, lowland birds seasonally increased this trait to a significant level, while montane ones did to a lesser extent. Besides, lowland birds showed greater evaporative cooling efficiency during summer (possibly due in part to reductions in total endogenous heat load), while surprisingly montane ones showed the opposite trend. Thus, lowland birds displayed greater seasonal flexibility in HTL, body temperature and resting metabolic rate above thermoneutrality, thus giving some support to the climatic variability hypothesis — that flexibility in thermoregulatory traits should increase with climatic variability. Our results partially support the idea that songbirds’ adaptive thermoregulation in the heat is flexible, highlighting the importance of considering intraspecific variation in thermoregulatory traits when modelling the future distribution and persistence of species under different climate change scenarios.

Harvesting Rainwater and Utilizing for Supplemental Irrigation to Enhance Crop Productivity under Rainfed Conditions: A Case Study of North Eastern Ghats Zone of Odisha

Rainwater harvesting-cum-supplemental irrigation is an important strategy to enhance crop water productivity under rainfed conditions. This study was conducted to assess efficacy of farm pond in harvesting rainwater and utilizing for irrigation to okra-radish cropping sequence during 2018-19 and 2019-20 at Phulbani, Odisha. In this study, runoff harvested from a catchment area of 0.5 ha and stored in farm pond was quantified. Also, seepage and evaporation losses from the farm pond were determined along with computation of area that could be irrigated from the stored water. Three irrigation treatments were considered, namely, T1 – life-saving irrigation to okra and one protective irrigation of 5 cm to radish, T2 –life-saving irrigation to okra and two protective irrigations of 5 cm each to radish, T3 – control without any protective irrigation. Rainwater harvesting potential of the study areavariedfrom8.3% to 8.9% of rainfall. Evaporation and seepage losses from the pond varied from30.6% to27.4% and from18.21% to 17.4% during 2018 and 2019, respectively. About 26.35% and 24.8% of the harvested rainwater was utilized for providing life saving irrigations to 0.4 ha cropped area during Kharif and Rabi seasons in 2018 and 2019, respectively. Treatment T2 consisting of one life saving irrigation to okra and two irrigations to radish resulted in the highest okra equivalent yield (OEY) of 10,156 kg ha-1 and 10,228 kg ha-1during 2018 and 2019, respectively. Crop water productivity was found to be the highest, i.e.,0.63 and 0.632 kg m-3 during 2018 and 2019, respectively for treatment T2. Therefore, pond water can be used for providing life-saving irrigation to the vegetable crops, which resulted in higher returns due to increased crop yields. It will also be possible for the farmers to go for the second crop in Rabi season.

Chemical and isotopic composition of rainwater in the eastern Yucatan peninsula, Mexico

Given that rain is the component of precipitation that reaches the surface of the earth, and aiming to contribute to the global efforts of rainwater monitoring, we present information regarding the origin of ions and their relationship with isotopic patterns and the source of moisture for rainwater in the Mexican Caribbean, which not only may be useful for pollution and atmospheric studies, but also for estimating groundwater recharges, understanding dust nuisances, and offering information about water quality for rainwater harvesting. In this paper, we describe the chemical composition of rainwater in terms of major ions, isotopic composition, and the most probable sources of moisture in the Caribbean coastal zone of Mexico, considering the three main climatic seasons in this area. The chemistry of rainwater displayed a noticeable influence from sea-salt spray, land-blown dust, and anthropogenic impacts such as agriculture and biomass burning. We identified the predominant terrestrial origin of calcium, namely anthropogenic contributions of sulfates and nitrates, plus potassium from sea spray and anthropogenic emissions. The local meteoric water line is δ2H = 8.2 δ18O + 13.8 (R² = 0.9601) suggesting enrichment due to evaporative losses, various moisture sources and local climatic effects. Although isotope composition was not different by site, it was by season, as opposed to water chemistry. We conclude that the water chemistry responds to the local conditions of the air column below the clouds, while the isotope composition is influenced by the origin of moisture and the physical conditions in which water evaporates and condenses as well.

Patterned Hybrid Surfaces for Efficient Dew Harvesting.

Dew harvesting, minimally influenced by climate and geographical locations, is an ideal method for addressing water shortage problems. Superhydrophilic surfaces, characterized by their highest affinity for water, are particularly attractive for this purpose as they can attract more water molecules via condensation. However, a significant challenge arises from the high surface capillary force that impedes water from sliding down and being effectively collected. The resulting water film on the superhydrophilic surface tends to stay around the edge of the water collection surface, leading to evaporation loss and reduced collection efficacy. To overcome this problem, triangular patterns with low surface adhesion to water were introduced at the edge of superhydrophilic surfaces. This modification, achieved through a wet chemical method and masked oxygen plasma treatment, has significantly improved the efficiency of water collection. Results indicate that the hybrid surface reduced the time for the first water droplet to slide down by half and increased water collection efficiency by 78% compared to uniform superhydrophilic surfaces and by 536% compared to uniform superhydrophobic surfaces under a relative humidity of 55% with a temperature difference of 15 °C. The underlying principles were elucidated through computational simulations, and the mechanisms driving the enhancement in collection efficiency were explained.

Integrated operation of sand dam and groundwater dam to increase water supply capacity in mountainous areas of Chuncheon, South Korea

Study regionA valley area in South Korea Study focusSand dams are cost-effective water-storage facilities for water-stressed areas in arid and semi-arid climates, with the advantages of reducing evaporation losses and filtering pollutants. Generally, sand dams are constructed by placing a horizontal barrier across the river bed, creating a naturally sand-filled structure upstream. Unlike this typical construction, a sand dam in Korea in the monsoon climate region was built near a mountainous valley, not in a stream, in Mulori, Chuncheon City, to ensure a sustainable water supply throughout the year, and especially to prevent freezing in the winter. Furthermore, a small-scale groundwater dam was additionally constructed downstream of the sand dam to increase the water supply capacity in preparation for severe droughts. In this study, the hydrological reservoir-routing simulations were performed to evaluate the effects of the combined use of the two dams on increasing water supply. New hydrological insights for the regionDaily discharge rates for the period from March 16, 2020 to July 6, 2022 were simulated for several hybrid operations that supplies water primarily through the sand dam under the normal conditions, but combines both water sources to manage severe droughts. The simulated results showed that, compared with operating the sand dam alone, the hybrid operations could satisfy the village’s water demand by increasing the minimum water supply rates by 24.6–50.0 m³/day for different simulation conditions. The combined use of sand and groundwater dams presented in this study will help provide sustainable water supply in water-stressed areas, especially mountainous uplands vulnerable to droughts and freezes.

Conservation agriculture practices: Adaptation and yield

Abstract Conservation agriculture (CA) has been promoted in sub-Saharan Africa (SSA) to increase crop productivity and for climate change adaptation. CA is the simultaneous application of the three principles: no-till, mulch cover, and crop diversification. The potential benefits are largely linked to moisture conservation of crop residues, reduced run-off and erosion, increased infiltration, and reduced evaporative losses. This study uses a review of recent literature in SSA under rain-fed conditions to synthesize evidence of the effect of CA on yield and climate change adaptation. Web of Science and Google Scholar were used for literature searches. Crop productivity results in the literature suggest that CA increases yield in certain circumstances such as well-drained soils and moderate rainfall, and that poorly drained soils in combination with excessive rains lead to depressed yields. The yield benefits reported range from as low as 4% and as high as 16%, with negative effects also reported. Stability analysis used as a proxy for adaptation revealed only a marginal benefit of CA above conventional practices suggesting the significant effect of seasonal rainfall on crop productivity. The results suggest the need to target CA practices to different agroecologies and other pragmatic local agronomic practices that may be required in cases of excessive rainfall and extended mid-season dry spells. The benefits of CA reported are largely plot level, and only a few studies consider the whole farm, especially within the holistic livelihood framework. In addition, adoption of CA remains low among smallholder farmers, and the widespread benefits of the practices cannot be realized at multiple scales.