Shallow Water Pool Research Articles

Rapid swimmer using explosive boiling due to electrical discharge in water

A strong micro heat engine that can be used in the untethered state is essential for next-generation microrobotics. Here, we propose a rapid swimmer using explosive boiling due to electrical discharge in water. Specifically, we demonstrate that the water-repellent swimmer that has an aluminum discharge antenna in the rear part can swim with the maximum velocity of ∼14 cm/s on the water surface like a water strider between a pair of parallel electrodes in a shallow water pool by applying direct current high-voltage pulses repeatedly. Moreover, by the video observation with high speed (960 fps), we found that an asymmetrical wave was generated immediately after the discharge, and it propelled the swimmer. Our findings should contribute to next-generation microrobots in the future.

Use of Aquatic Insects to Assess the Biological Status of a Perennial Pond in Assam, Northeast India

An investigation was carried out on “Hazara Pukhuri”, a perennial pond in Sonitpur district, North East India, between July 2019 and June 2020. To assess the health of the waterbody, various biotic and diversity indices were applied, with aquatic and semi-aquatic hemipteran populations functioning as bioindicators. The pond’s hemipterans include 17 species from 13 genera and 8 families, including Gerridae, Corixidae, Pleidae, Notonectidae, Nepidae, Belostomatidae, Hydrometridae, and Mesoveliidae. The biotic indices Average Score per Taxon (ASPT), Stream Invertebrate Grade Number-Average Level (SIGNAL-2), and The Biological Monitoring Working Party (BMWP) Score, as well as other diversity indices, were assessed to indicate that the waterbody was unpolluted/ slightly polluted. The presence or lack of littoral vegetation and flooding and drying of nearby shallow water pools and swampy areas were important drivers of the distribution, abundance, and community composition of aquatic and semi-aquatic hemipterans in the studied water body.

Experimental study of liquid spreading and atomization due to jet impingement in liquid–liquid systems

Liquid spreading and atomization due to jet impingement in liquid–liquid systems is considered to be crucial for understanding cooling behavior of high temperature molten martial into shallow water pool. This phenomenon takes place where a liquid jet enters a pool filled with another immiscible liquid. The jet spreads radially after impinging on the floor while forming a thin liquid film and atomizing droplets. In this study, we employed three-dimensional Laser-Induced Fluorescence (3D-LIF) measurements and three-dimensional (3D) reconstruction to quantify its unsteady three-dimensional behavior. Under high flow velocity conditions, atomization occurred along with the spreading of the liquid film. To evaluate the spreading behavior of the liquid film, a comparison was made with the existing theory of gas–liquid systems. The spreading of the liquid film was suppressed compared with that of the gas–liquid system. Furthermore, the particle tracking velocimetry method was successfully used to measure the velocity boundary layer and velocity profile in the liquid film, which are important factors that affect the spreading mechanism of the liquid film. The results revealed that in liquid–liquid systems, shear stress at the liquid–liquid interface causes a decrease in the flow velocity and suppressed development of the velocity boundary layer. To evaluate the atomization behavior, the number and diameter distribution of the atomized droplets were measured from the acquired three-dimensional shape data of the jet. The number of droplets increased with the flow velocity. The results show that the jump radius is affected by such atomization behavior, and since the jump radius was lower than the theoretical value, we can conclude that the location of the hydraulic jump is expected to undergo an upstream transition.

Is Disease Induced by Flooding Representative of Nursery Conditions in Rhododendrons Infected with Phytophthora cinnamomi or P. plurivora?

The degree of flooding commonly used to induce disease in Phytophthora root rot studies rarely occurs in container nurseries. Instead, over-irrigation and poor drainage result in plants periodically sitting in shallow pools of water. Rhododendron plants were grown in a noninfested substrate or substrate infested with Phytophthora cinnamomi or P. plurivora to determine whether root rot induced by flooding represents disease that occurs under simulated nursery conditions when plants are in a shallow pool of water (saucers), or are allowed to freely drain and maintained at ∼75% container capacity (CC). Generally P. cinnamomi caused more disease than P. plurivora, and all water treatments were conducive to root rot. In experiment 1, the amount of disease caused by flooding was similar to that in the saucer treatment (75% CC not tested) while in experiment 2, flooding often caused more rapid and severe disease than the saucer or 75% CC treatment. Pathogens differed in their response to water treatments. P. cinnamomi caused more disease in treatments with >90% substrate moisture for either a short (flood) or long duration (saucer), while P. plurivora was less capable of causing disease when soil moisture was maintained >90% than when substrate moisture was maintained at a more moderate level (flood, 75% CC). Our results indicate that it is not necessary to flood plants to induce disease under experimental conditions and that disease induced by flooding can represent disease in container nurseries when containers are in pools of water or maintained at ∼75% CC. In addition, our results suggest that P. cinnamomi is a more aggressive pathogen than P. plurivora in nursery conditions where drainage is poor; however, both species are capable of causing a similar amount of disease under more typical irrigation management.

Rainfall intensity and catchment size control storm runoff in a gullied blanket peatland

Upland blanket peat is widespread in the headwaters of UK catchments, but much of it has been degraded through atmospheric pollution, vegetation change and erosion. Runoff generation in these headwaters is an important element of downstream flood risk and these areas are increasingly the focus of interventions to restore the peat ecosystem and to potentially mitigate downstream flooding. Here we use a series of multivariate analysis techniques to examine controls on storm runoff behavior within and between ten blanket peat catchments all within 5 km of one another and ranging in size from 0.2 to 3.9 ha. We find that: 1) for all 10 catchments, rainfall intensity is the dominant driver for both magnitude and timing of peak discharge, and that total and antecedent rainfall is important for peak discharge only in small storms; 2) there is considerable inter-catchment variability in: runoff coefficient, lag time, peak runoff, and their predictability from rainfall; however, 3) a significant fraction of the inter-catchment variability can be explained by catchment characteristics, particularly catchment area; and 4) catchment controls on peak discharge and runoff coefficient for small storms highlight the importance of storage and connectivity while those for large events suggest that surface flow attenuation dominates. Together these results suggest a switching rainfall-runoff behavior where catchment storage, connectivity and antecedent conditions control small discharge peaks but become increasingly irrelevant for larger storms. Our results suggest that, in the context of Natural Flood Management potential, expanding depression storage (e.g. distributed shallow water pools) in addition to existing restoration methods could increase the range of storms within which connectivity and storage remain important and that for larger storms measures which target surface runoff velocities are likely to be important.

Thermal stress affects bioturbators' burrowing behavior: A mesocosm experiment on common cockles (Cerastoderma edule)

The intensity of marine heatwaves is increasing due to climate change. Heatwaves may affect macroinvertebrates' bioturbating behavior in intertidal areas, thereby altering the deposition-erosion balance at tidal flats. Moreover, small-scale topographic features on tidal flats can create tidal pools during the low tide, thus changing the heat capacity of tidal flats. These pools could then potentially operate as refuge environments during marine heatwaves. We studied behavior responses to heat waves using the well-known bioturbating cockle Cerastoderma edule as a model species. Different temperature regimes (i.e., fluctuating between 20 and 40 °C) and micro-topographies (i.e., presence vs. absence of tidal water pools) were mimicked in a mesocosm experiment with regular tidal regimes. Our results demonstrate that behavioral responses to heat stress strongly depend on the site-specific morphological features. Cockles covered by shallow water pools moved up when exposed to thermal stress, while burrowing deeper into the sediment in the absence of water pools. But in both cases, their migratory behavior increased under heat stress compared to regular ambient treatments. Moreover, long-term cumulative heat stress increased cockles' respiration rates and decreased their health conditions, causing mass mortality after four weeks of gradually increasing heat exposure. Overall, the present findings provide the first insights into how bioturbating behavior on tidal flats may change in response to global warming.

Full vs. Empty

Full vs. Empty

Breeding Behaviour of Black-Winged Stilt, Himantopus himantopus (Linnaeus, 1758) in Agricultural Landscape of Punjab, India

During the breeding seasons (2017-2019), the hitherto little known aspects of breeding behavior of Black-winged Stilt, Himantopus himantopus were studied in the ploughed agricultural fields, village ponds and adjacent shallow pools located in rural outskirts in district Ludhiana, Punjab, India. Observations on nest structure, egg laying, incubation, hatching and other behavioural aspects of the parents/chicks were inferred from videorecords, photographs and direct field observations made on 19 clutches containing 59 eggs. In the study area the breeding season extended from April to July. The mean clutch size was 3.29±0.77 (range 1-4, n=19) that differed between the dry ploughed field clutches (3.4±0.70, range: 2-4, n=10) and wet pool/pond sites (2.78±1.09, range: 1-4, n=9). In the dry ploughed fields, the nest scrapes were lined mainly with the wheat rootlets/ straw pieces only. However, the nest material used in/around ponds and pools included predominantly dry twigs, decaying leaves and some thermocol chips. The egg length, breadth, weight, egg shape index and volume (n=54) measured 42.22±2.50 mm, 30.71±1.13 mm, 19.77±2.34 gm, 72.88±3.19 and 20.39±2.36 cm3, respectively. The eggs hatched mostly synchronously after biparental incubation period of 25 or 26 days (n=4). As per traditional method, only 20.34% (12 out of 59 eggs) of the eggs hatched successfully and the hatching success calculated as per the Mayfield Method showed that it was only 2.07% in post-harvest field sites and 36.26% in non-agricultural sites (shallow water pools and edge waters of village ponds). The use of polluted sites as nesting grounds has been opined as a habitat shift and an adaptation in process

Drepanocladus lycopodioides rediscovered in the Czech Republic: Abandoned quarries as refugia for endangered fen species

The moss Drepanocladus lycopodioides, considered extinct in the Czech Republic, has been rediscovered. The population occurs in an abandoned sandstone quarry with a shallow water pool; the site known as Lom Rasová is located in the Bílé Karpaty Mts (the White Carpathians) in the south-eastern part of the Czech Republic. The species has not been recorded in the country since the first half of the 20th century. The plant community with D. lycopodioides recorded in the Lom Rasová quarry resembles alkaline fens transient to intermittently wet meadows, i.e. the natural habitat of the species. We conclude that abandoned waterlogged quarries mimic the key environmental conditions that determine the natural occurrence of D. lycopodioides, i.e. high calcium richness, water table fluctuations, low productivity and irregular disturbances that prevent the dominance of competitively superior species. Such conditions no longer occur in current central-European agricultural landscapes. We encourage bryologists and mire ecologists to explore abandoned quarries and other post-mining habitats with shallow water bodies, as they may represent potential refugia for endangered fen species.

Kinetic energy evaluation for the steam explosion in a shallow pool with a spreading melt layer at the bottom

Steam explosion experiments with a melt layer spreading at the bottom of a shallow water pool, namely the PULiMS-E6 and SES-S1 by KTH, Sweden, were simulated by the steam explosion simulation code, JASMINE. The observed impulses in the experiments were successfully reproduced by simulations with assumed premixing conditions. With those simulation results, the adequacy of the kinetic energy evaluation method used for the experiments were examined by comparison of the kinetic energy directly obtained in the simulation, Ek, and the one evaluated based on the impulse and the water mass limited to the center area above the premixing zone, Ekic. It showed that the impulse based kinetic energy evaluation gives about five times overestimation. The impact of the water pool geometry on the validity of the impulse based kinetic energy evaluation method was further examined by a parametric study with variations of the pool geometry in the simulations of PULiMS-E6 and SES-S1 as well as high pressure bubble expansion simulations. The results for the relation of Ekic/Ek and the geometric factors were consistent between the cases for the experiments and the bubble expansion. The results showed that: (1) for the shallow water pool regime, Ekic/Ek shows a trend of convergence to 4–5, (2) for deep water pool regime, the impulse based kinetic energy evaluation with the whole water mass, Eki, rather than Ekic, gives a good estimation. A set of empirical formulas was obtained for Ekic/Ek.

Investigation of steam explosion duration in stratified configuration

A steam explosion is an energetic fuel-coolant interaction process, which may occur during a severe reactor accident when the molten core comes into contact with the coolant water. In the stratified melt-coolant configurations, where the corium melt is released in a shallow water pool or in an initially dry cavity later flooded with coolant water, the melt-water interaction may occur on the interface between the bottom melt layer and the upper water layer. It was long believed that stratified melt-water conditions cannot generate strong explosive interactions, because it was assumed that there is no significant premixing of melt and coolant water prior to the shock wave propagation. However, the recently performed experiments in the PULiMS and SES (KTH, Sweden) facilities with corium simulant materials revealed that strong steam explosions may spontaneously develop also in a stratified melt-water configuration, where a formation of a considerable melt-water premixed layer was observed. Understanding the premixture formation mechanisms is crucial for predicting the stratified steam explosion energetics. One of the external indicators of the way the melt and water are mixed during the stratified steam explosion process is the explosion duration.In the article, the duration of the stratified steam explosion is studied by the analysis of experimental observations in the PULiMS and SES tests using simulation results obtained with the MC3D code (IRSN, France). The explosion characteristics are analysed by varying the available melt mass in the premixed layer, the triggering position, the melt droplet diameter, the void fraction in the premixed layer, the void fraction in the water above the premixed layer and the size of the fine fragments. The analysis showed that longer explosion duration for the experiments with strong explosions cannot be predicted solely by varying the premixed layer conditions. A significant increase of the explosion duration could be obtained only by increasing the size of the fine fragments, which depends on the nature of the explosion. Thus the observed discrepancies between the experimental results and simulations can be explained by the fact that in strong stratified steam explosions there is also significant melt-water layer mixing during the explosion propagation.

Nuclear Abnormalities in Erythrocytes of Frogs from Wetlands and Croplands of Western Ghats Indicate Environmental Contaminations

Anuran amphibians are the biological models to assess the influence of environmental contamination. We conducted nuclear abnormality assessment and micronuclei test in erythrocytes of frogs to identify an early influence of environmental contaminations. In Western Ghats of India, farmers use different agrochemicals and obviously, the amphibian habitat is contaminated with combinations of many residues. Many frog species use these agro-ecosystem for breeding and to complete early life stage. In the present study, we used Indian skipper frog ( Euphlyctis cyanophlyctis (Anura: Ranidae)), a common inhabitant of water bodies in agro-ecosystems of Western Ghats for the assay. We collected the adult frogs from three different habitats; a) the rice paddy fields contaminated with agro-chemicals, b) uncontaminated marsh and c) a shallow water pool. We recorded micronucleus, blebbed, lobed, kidney bean shaped nucleus and nucleus with notches in erythro-cytes of these frogs. These nuclear abnormalities in erythrocytes are quantified. The incidences of occurrence of micronucleus ranged from 0 to 8 in 1000 analyzed cells. More than 80% of the frogs living in agro-chemical contaminated site showed these abnormalities. The appearance of nuclear abnormalities indicates that the frogs are affected by agro-chemicals.

Holocene Lake and Shallow Water Sediments at Mograt Island, Sudan

Abstract This paper presents the results of stratigraphic excavation and soil studies carried out at Mograt Island, the largest of the Nilotic islands in Sudan. Due to its restricted insular environments, Holocene alluvial deposits were observed to be interlocked with archaeological remains of different periods, allowing for a combined chronostratigraphic approach to study both cultural and climatic events. To better understand the environmental context through soil components and pedological features at a microscopic scale, soil block samples were accordingly collected and studied by the application of soil micromorphology. This approach provides insights into the history of Nile terrace aggradation through the suspension of Nile sediment loads under stillwater conditions as well as of the periodical establishment of shallow water pools at the islands′ plateaus by the surface run-off from local rains. Since these patterns vary significantly from the present situation, they offer a key to the scenario in which specific early agricultural and animal herding practices evolved.

Premixing and steam explosion phenomena in the tests with stratified melt-coolant configuration and binary oxidic melt simulant materials

Steam explosion phenomena in stratified melt-coolant configuration are considered in this paper. Liquid corium layer covered by water on top can be formed in severe accident scenarios with (i) vessel failure and release of corium melt into a relatively shallow water pool; (ii) with top flooding of corium melt layer. In previous assessments of potential energetics in stratified melt-coolant configuration, it was assumed that melt and coolant are separated by a stable vapor film and there is no premixing prior to the shock wave propagation. This assumption was instrumental for concluding that the amount of energy that can be released in such configuration is not of safety importance. However, several recent experiments carried out in Pouring and Under-water Liquid Melt Spreading (PULiMS) facility with up to 78kg of binary oxidic corium simulants mixtures have resulted in spontaneous explosions with relatively high conversion ratios (order of one percent). The instability of the melt-coolant interface, melt splashes and formation of premixing layer were observed in the tests. In this work, we present results of experiments carried out more recently in steam explosion in stratified melt-coolant configuration (SES) facility in order to shed some light on the premixing phenomena and assess the influence of the test conditions on the steam explosion energetics.

Factors influencing the success of within-field AES fallow plots as key sites for the Northern Lapwing Vanellus vanellus in an industrialised agricultural landscape of Central Europe

Unsown fallow plots, commonly referred to as ‘lapwing plots’, are widely promoted within the English agri-environmental programme, but remain unstudied outside of England. We tested Lapwing plots in an industrialised agricultural landscape in Central Europe from 2010 to 2015. Lapwings (Vanellus vanellus) and other birds as well as plant species were mapped. Factors influencing the success of the plots were modelled to obtain information on how to design a well-working agri-environment scheme (AES).Lapwings were present at 65% of the 61 lapwing plots studied, whereas colonisation of untreated control sites was significantly lower (37%). 64 lapwing pairs bred at 26 lapwing plots, but only 18 pairs at nine untreated sites. Hatching success was significantly higher than without treatment (24 pairs at 11 lapwing plots vs. 3 pairs at 2 control sites). Other species which benefitted from the measures were Eurasian Skylark (Alauda arvensis) and Yellow Wagtail (Motacilla flava).The modelling of key factors showed that a successful lapwing plot should be: (1) large (at least about 2ha); (2) located at a traditional breeding site; (3) sparsely vegetated; and, (4) equipped with a shallow pool of water. Placing them in winter cereals improved hatching success.Lapwing plots at damp sites are a promising AES for lapwing conservation in industrialised agricultural landscapes in Central Europe.

Experiments on ostrich decomposition and opisthotonus with implications for theropod dinosaurs

Fresh ostrich cadavers were exposed in a natural environment (two on land and one in a shallow pool of water) to investigate decomposition and possible opisthotonus. The decomposition followed through to skeletonization of the ostrich cadavers by maggots, the primary agents of decay. During ostrich decomposition, tissue was consumed sequentially from the soft matrix tissue of muscles to fibrous and ligamentous tissue (both comprising collagen). The feathers (comprising β-keratin) were not consumed. The entire decomposition process was completed in 5 days. Towards the latter stages of the experiment, the cadavers on land showed stages of strong upward arching of the neck which fell short of the opisthotonic posture, while the cadaver in the pool showed the classic form of opisthotonus, strongly supporting the post-mortem hypothesis of the phenomena. Comparisons are made with opisthotonus in the theropod dinosaur, Sinosauropteryx.

Analysis of ex-vessel melt jet breakup and coolability. Part 1: Sensitivity on model parameters and accident conditions

The breakup of a melt jet falling in a water pool and the coolability of the melt particles produced by such jet breakup are important phenomena in terms of the mitigation of severe accident consequences in light water reactors, because the molten and relocated core material is the primary heat source that governs the accident progression. We applied a modified version of the fuel–coolant interaction simulation code, JASMINE, developed at Japan Atomic Energy Agency (JAEA) to a plant scale simulation of melt jet breakup and cooling assuming an ex-vessel condition in the APR1400, a Korean advanced pressurized water reactor. Also, we examined the sensitivity on seven model parameters and five initial/boundary condition variables. The results showed that the melt cooling performance of a 6m deep water pool in the reactor cavity is enough for removing the initial melt enthalpy for solidification, for a melt jet of 0.2m initial diameter. The impacts of the model parameters were relatively weak and that of some of the initial/boundary condition variables, namely the water depth and melt jet diameter, were very strong. The present model indicated that a significant fraction of the melt jet is not broken up and forms a continuous melt pool on the containment floor in cases with a large melt jet diameter, 0.5m, or a shallow water pool depth, ≤3m.

INTEGRATED PALAEOECOLOGICAL INVESTIGATION OF BOTTOM SEDIMENTS FROM LAKE MANZHEROKSKOYE IN THE PIEDMONT ALTAI REGION

Complementary spore-pollen, diatom and geochemical analysis of samples from upper 80 cmof lake sediments from Lake Manzherokskoye, situated in the western piedmont region of Altai Mountains, revealed correlations between trends in the local water content in the lake and changes in the surrounding dry land vegetation triggered by the change of the overall climate humidity. Ecological analysis of diatom complexes from the studied sediment section and reconstruction of pH variation based on diatom indicator-species revealed the following successions: 1 – a shallow water pool during downcore sedimentation; 2 – a sharp rise in the lake water content during mid-core sedimentation; 3 – following decrease of the lake level, and 4 – contemporary new rise of the water level in Lake Manzherokskoye. The reconstructed second stage of change in local conditions in Lake Manzherokskoye agrees with pollen data demonstrated change of dry land vegetation from birch forest-steppe to pine and Siberian cedar forests and, finally, to contemporary birch-pine anthropogenically transformed forest-steppe. During the sharp water rise stage the content of terrigenous elements increased in the lake sediments, whereas diatom complexes degraded considerably during this stage. Human influence on the landscape is seen in the top part of the studied lake sediment as indicated by findings of ruderal pollen ( Triticum, Plantago, Cannabis, Secale, Fagopirum), as well as pollen of Quercus , which is exotic for Siberian flora. Changes in the diatom complexes in the examined section of the lake sediments point to a higher climatic sensitivity of the small and shallow Lake Manzherokskoye compared to the large and deep Lake Teletskoye.

Influence of Physical Manipulations on Short-Term Salt Marsh Morphodynamics: Examples from the North and Mid-Atlantic Coast, USA

Along the mid- and north Atlantic coasts of the USA, over 90 % of salt marshes have been ditched. Ditching was largely abandoned by the mid-twentieth century; however, techniques that create permanent shallow water pools for mosquito control and bird habitat are increasingly being applied to marshes of the USA and elsewhere. Salt marshes in Plum Island Sound, Massachusetts, and Barnegat Bay, New Jersey, were used to examine differences between areas that have been ditched and those altered to increase the density of shallow pools in water table dynamics, salinity, soil and porewater chemistry, as well as short-term sedimentation, accretion, and elevation change rates. We found that the area with plugged ditches, berms, and pools in Plum Island had less drainage, higher salinity and porewater sulfide and ammonium concentrations, and higher soil organic matter than the adjacent ditched area. Despite averaging 8 cm lower in elevation, the Plum Island ditched area had less sediment deposition and was composed of higher elevation plant species than the area with plugged ditches, berms, and shallow pools. Elevation increased in the ditched area at a rate of 3.2 ± 0.5 mm/year, but elevation change was variable in the area with pools. In Barnegat Bay, the marsh area with pools and ditches had less sediment deposition and surface accretion than the ditch-only area, associated, in part, with the higher elevation. An average elevation difference of 4.5 cm was associated with a sixfold difference in mineral sediment deposition. Temporal sediment deposition and surface accretion was important in the ditch-only area but was absent or muted in the area with numerous pools. Elevation increased in both marsh areas at an average rate of 1.8 ± 0.8 mm/year, less than half the long-term average local rate of sea-level rise. Our results illustrate how physical manipulations including changes to tidal hydrology and surface topography interact with elevation to influence short-term biophysical feedbacks.

Water uptake and redistribution during drought in a semiarid shrub species.

In arid systems, most plant mortality occurs during long drought periods when water is not available for plant uptake. In these systems, plants often benefit from scarce rain events occurring during drought but some of the mechanisms underlying this water use remain unknown. In this context, plant water use and redistribution after a large rain event could be a mechanism that allows deep-rooted shrubs to conservatively use water during drought. We tested this hypothesis by comparing soil and plant water dynamics in Artemisia tridentata ssp. vaseyana (Rydb.) Beetle shrubs that either received a rain event (20mm) or received no water. Soil water content (SWC) increased in shallow layers after the event and increased in deep soil layers through hydraulic redistribution (HR). Our results show that Artemisia shrubs effectively redistributed the water pulse downward recharging deep soil water pools that allowed greater plant water use throughout the subsequent drought period, which ameliorated plant water potentials. Shrubs used shallow water pools when available and then gradually shifted to deep-water pools when shallow water was being used up. Both HR recharge and the shift to shallow soil water use helped conserve deep soil water pools. Summer water uptake in Artemisia not only improved plant water relations but also increased deep soil water availability during drought.