Slow-moving Water Research Articles

Hydrologic modelling of niche construction at the Waitetoke Cultivation Complex, Ahuahu, Aotearoa New Zealand

The early Māori settlers of Ahuahu, a small island off the Coromandel Peninsula of Aotearoa New Zealand, engineered the environment to create a raised-bed irrigation system to grow taro (Colocasia esculenta). Three-dimensional computational fluid dynamic (CFD) modelling of water flow provides insights into how the irrigation system functioned. Excavation and coring data and a digital elevation model combine to simulate the hydrology of the raised-bed irrigation system at Waitetoke on Ahuahu. This modelling demonstrates that for operation, the system required a series of channels and weirs to divert water from a nearby spring. The slow-moving water delivered nutrients to the cultivation area and also promoted the growth of nitrogen fixing algae. Exogenous nutrients including wood ash and calcium carbonate along with fire modified rocks derived from nearby household hearths added to the cultivation matrix created ideal conditions for taro growth. Over the span of over two hundred years, Māori engaged in various forms of niche construction to enhance taro production by altering feedback relationships between the geomorphology of the area, a natural spring, the constructed channels and weirs, water, cultivars, algae, and soil nutrients.

Water function zone: A method to improve the accuracy of remote sensing retrieval of water bodies

In water monitoring, it is always a hot issue to exploring a method to improve the accuracy of remote sensing inversion. To this end, based on the actual investigation of the surrounding environment and water quality characteristics of the Fuyang river, this study has established five distinct water functional zones: reservoir (RS), village river (VR), industrial river (IR), artificial lake (AL), and urban river (UR), which are considered as subdivided datasets. Meanwhile, considering that lakes and reservoirs typically contain relatively stationary or slow-moving water bodies, while river channels are characterized by moving water bodies, three multi-type datasets have been constructed for comparison. These are based on the morphological and flow characteristics of different regions within the Fuyang river and include river channel (R), lake (L), and whole basin (W). Based on multi-spectral images of unmanned aerial vehicle (UAV) and measured water quality data, ten types of inversion models were to invert six kinds of water quality parameters, and compare and analyze the performance of the optimal inversion model of the corresponding data sets. The results show that the multivariate regression model is superior to the univariate regression model, and the mean coefficient of determination (R2) of the subdivided data set is 0.936, and the root mean square error (RMSE) and mean absolute error (MAE) appear decrease in different degrees compared with the W with 3.573 and 2.662, respectively. The mean ratio performance to interquartile (RPIQ) of the corresponding model in UR and VR are 3.963 and 2.748, respectively. Extremely Randomized Trees (ERT) model is more suitable for the inversion of multi-type data sets lacking obvious water quality characteristics and with complex components, while Categorical Boosting (CatBoost) model is more suitable for the inversion of subdivided data sets with obvious water quality characteristics. The current method has practical guiding significance for improving the application level of water monitoring technology in ecological environment protection and urban water resources protection.

First natural history observations of the Critically Endangered Wattle-necked softshell turtle Palea steindachneri in its native range

The Wattle-necked softshell turtle Palea steindachneri is poorly understood in its natural habitat, despite being highly productive in farms and commonly observed in the turtle trade. Field observations conducted in Vietnam's Pu Mat National Park represent the inaugural instance of direct, in-the-wild natural history documentation for the species within its native habitat. In contrast, prior research relied on interview data gathered from local communities. The species was found in slow-moving water in a sandy stream, consistent with previous information from community interview data. The limited range and its frequent appearance in the food and traditional medicine trade have led to the species’ classification as Critically Endangered by the IUCN Red List. Keywords: Natural history, observation, Palea steindachneri, Vietnam turtle, Wattle-necked softshell turtle

Relation between fish morphological differentiation and pressure drag difference

Changes in the flow environment can cause changes in fish morphology, but the specific mechanisms by which flows change fish morphology are not known. It would be a useful addition to the field if it could be explored from the point of view of resistance properties. To explore the effect of water flowing over the fish surface, we selected Schizothorax prenanti as a representative species in flowing water and Carassius auratus as a representative fish in slow-moving water and carried out hydrodynamic experiments and numerical simulations without any simplification of the fish body in order to obtain accurate resistance data. The results show that in the simulated flow rate scenarios, the overall resistance of C. auratus and the local resistance at the head, dorsal, lateral, and hypogastrium regions were all higher, with maximum differences of 3.49 times, 3.63 times, 6.47 times, 10.41 times, and 46.77 times those of S. prenanti, respectively. Combining the results of this study with the theory of biomechanical adaptation, we believe that resistance characteristics are important factors in the shaping of fish body shape by water flow. On this basis we believe that in addition to ensuring the integrity of fish life histories, the resistance characteristics of individuals in natural streams need to be measured and recorded. Habitat restoration should provide similar resistance environments for protected species to avoid loss of shape characteristics.

Distribution and Conservation Status of European Pond Turtles Emys orbicularis (L., 1758) in Algeria

The Maghreb population of Emys orbicularis extends over a narrow strip of northern Morocco, Algeria, and Tunisia. Our understanding of the presence of this turtle in Algeria, in contrast to Morocco and Tunisia, is quite limited and frequently rests on a few small-scale studies or even reports from a century ago. The present study provides the first complete data on the distribution and level of threat of this species in Algeria. A field survey was carried out based on the data obtained from scattered local reports and available studies that suggested the presence of the species in Algerian wetlands. Data on climatic and habitat preferences, the geographic elevation of inhabited localities, and their conservation status were collected. A total of 45 wetlands were inhabited by E. orbicularis, of which 40 were part of a well-interconnected eastern metapopulation, joined by an extensive hydrographic network. In some places, the species has persisted for over 130 years in the same wetland complex. However, the five remaining populations living in central North Algeria are fragmented, highly isolated, and therefore more threatened. With a few exceptions, turtles inhabit lowlands below 100 m above sea level. Detected sub-populations inhabit mostly stagnant waters (60%), sometimes dams and lakes (24%), and sporadically also slow-moving water bodies (16%). Altogether, the Algerian distribution of E. orbicularis extends to a total area of 2900 km2, a 40 km wide strip with a length of 490 km west of the Tunisian border. Although restricted to this narrow strip, the persistence of numerous populations in Algeria, especially in Numidia, testifies to their relatively better conservation status. In order to ensure the sustainability of these efforts, follow-up and monitoring activities should be suggested, with special attention paid to highly isolated populations to maintain their long-term viability.

Measurements of tidal flow variability in Ramsey Sound, Pembrokeshire

The nature of the flow at in-stream tidal energy sites is particularly important for predicting array and device performance, and also for operations and maintenance planning. Previous developers have reported issues such as the choice of vessel, cost of operations, and the limits of operation of deployment vessels. The dynamics of the flow around slack water has been of particular interest at Ramsey Sound in Pembrokeshire (UK) for planning the recovery of an existing turbine, the Tidal Energy Limited ‘Deltastream’.
 This research presents flow characteristics of Ramsey Sound, based on analysis of Acoustic Doppler Current Profiler (ADCP) measurements and tide gauge data from the nearby Standard Port of Milford Haven. The ADCP was located approximately 300 m across the channel, at the northern end of the channel, where the channel width was 1200 m and the mean depth was approximately 33 m. The flow dynamics were examined specifically to look at times potentially suitable for offshore operations Two weeks of data were used in the analysis, spanning a complete spring-neap cycle.
 Results demonstrate that flow velocities exhibited clear asymmetry, with stronger flows on the northerly directed flood tide than on the ebb. There was considerable variation in the measured current speed around the time of the maximum, suggesting large scale bed feature generated turbulence. The flood (northerly) current maximum was approximately in phase with high water at Milford Haven. Cross correlation indicated that the flow generally led the elevation by 20 minutes. In contrast to the expected theory, the current strength at mid-depth was stronger than at the surface on the maximum flood tide. The maximum flow speed in the tide was reasonably predictable from the tide range at Milford. A threshold-based analysis of the ADCP measurements allowed the duration of slow-moving water to be identified for operation planning.
 Operations and planning in light of sound understanding of hydrodynamics at tidal energy sites is critical for future economic success of the tidal energy sector. The results shown here from an ADCP deployment in Ramsey Sound have shown the capability to give useful tools for planning recovery operations.

Aeolian-fluvial interactions in the Yellow River Basin, China: Insights from sedimentary characteristics and provenance of the sedimentary sequences

Understanding environmental changes requires the characterization of potential interactions between aeolian and fluvial systems. This study aimed to identify the sedimentary characteristics, provenance, and transport of sediments of the Yellow River Basin, as well as the processes and geomorphological effects of aeolian-fluvial interactions using end-member modelling analysis (EMMA), multidimensional scaling (MDS), and principal component analysis (PCA). Samples (n = 107) collected from sedimentary sequences in the source area, upper, middle, and lower reaches were analyzed for grain size and major element contents. The results showed that sediments in the source area of the Yellow River mainly originated from the Tibetan Plateau, whereas the input of materials from the Chinese Loess Plateau (CLP) gradually increased from the upper to lower reaches. The sediment transport was jointly controlled by simultaneous or alternating aeolian and fluvial processes. Asynchronism in aeolian activity and rainfall and the non-uniformity of runoff and sediment sources resulted in a concentration of aeolian-fluvial interactions in the river reaches traversing through the deserts and CLP. Fluvial sediments in the upper reaches consisted of wash loads deposited in slow-moving water, whereas rapid replenishment of sediment from the CLP in the middle reaches increased sediment transport capacity, thereby enhancing the uniformity of sedimentary characteristics from the upper to lower reaches. Moreover, numerous gullies in the CLP resulted in increased intensities of aeolian-fluvial interactions, thereby accelerating severe sedimentation in the lower reaches. This study can act as a reference for paleoclimatic reconstruction and for soil and water conservation in large-scale watersheds across a range of climatic zones.

Morphometrics, Habitat and Breeding Activity of Asian Common Toad, <i>Duttaphrynus melanostictus</i>, in Pakistan

The scientific data on ecology of amphibians from Pakistan are scarce. Asian Common Toad (Duttaphrynus melanostictus) is widely distributed in South Asia, and has been introduced outside its range causing severe ecological problems. We gathered data on morphometrics, habitat and breeding activity of the species in its western edge, North Punjab, Pakistan, of the range. The morphometric measurements of Asian Common Toad showed that the males were 49 ± 3.4 mm in snout vent length while the females were 58 ± 5.5 mm. Of the 13 measurements tested, the factor analysis produced five (head width, forelimb length, femur length, width of upper eyelid and foot length) significant measurements (r 0.80) for male while six (snout-vent length, head width, head length, greatest tympanum diameter, forelimb length, length of tarsus and foot) for female. The substrate of the habitat of Asian Common Toad was recorded as muddy to stony; water with neutral to slightly alkaline pH; dominated by herbs: Cannabis sativa, Parthenium hysterophorus; shrubs: Dodonaea viscosa, Lantana camara; grasses: Cynodon dactylon, Dactyloctenium aegyptium; and hydrophytes Alternanthera sessilis and Centella asiatica. The mean air and water temperature (day) during the breeding period were 27 – 30.5 and 25 – 28.5°C, respectively. The toad species laid eggs in small sized pools with lentic to slow-moving water with the mean depth of 32 – 64 cm. The males were more abundant than females (2.14♂:1♀) at the breeding sites. The advertisement call was of 9.3 ± 0.80 sec duration with a single note and 49.5 ± 6.5 nodes, –7.45 ± 0.95 average amplitude, 776 ± 51.8 Hz minimum frequency and 7011 ± 1680 Hz maximum frequency.

Impact of Temperature and Oxygen Availability on Gene Expression Patterns of Mycobacterium ulcerans.

Buruli ulcer disease is a neglected tropical disease caused by the environmental pathogen Mycobacterium ulcerans. The M. ulcerans major virulence factor is mycolactone, a lipid cytotoxic compound whose genes are carried on a plasmid. Although an exact reservoir and mode(s) of transmission are unknown, data provide evidence of both. First, Buruli ulcer incidence and M. ulcerans presence have been linked to slow-moving water with low oxygen. M. ulcerans has also been suggested to be sensitive to UV due to termination in crtI, encoding a phytoene dehydrogenase, required for carotenoid production. Further, M. ulcerans has been shown to cause disease following puncture but not when introduced to open abrasion sites, suggesting that puncture is necessary for transmission and pathology. Despite these findings, the function and modulation of mycolactone and other genes in response to dynamic abiotic conditions such as UV, temperature, and oxygen have not been shown. In this study, we investigated modulation of mycolactone and other genes on exposure to changing UV and oxygen microenvironmental conditions. Mycolactone expression was downregulated on exposure to the single stress high temperature and did not change significantly with exposure to UV; however, it was upregulated when exposed to microaerophilic conditions. Mycolactone expression was downregulated under combined stresses of high temperature and low oxygen, but there was upregulation of several stress response genes. Taken together, results suggest that temperature shapes M. ulcerans metabolic response more so than UV exposure or oxygen requirements. These data help to define the environmental niche of M. ulcerans and metabolic responses during initial human infection. IMPORTANCE Buruli ulcer is a debilitating skin disease caused by the environmental pathogen Mycobacterium ulcerans. M. ulcerans produces a toxic compound, mycolactone, which leads to tissue necrosis and ulceration. Barriers to preventing Buruli ulcer include an incomplete understanding of M. ulcerans reservoirs, how the pathogen is transmitted, and under what circumstances mycolactone and other M. ulcerans genes are expressed and produced in its natural environment and in the host. We conducted a study to investigate M. ulcerans gene expression under several individual or combined abiotic conditions. Our data showed that mycolactone expression was downregulated under combined stresses of high temperature and low oxygen but there was upregulation of several stress response genes. These data are among only a few studies measuring modulation of mycolactone and other M. ulcerans genes that could be involved in pathogen fitness in its natural environment and virulence while within the host.

Rare Earth Elements behaviour in different types of mineral waters within Baikal Lake

The current study contains a review of the REE abundance and distribution in thermal and cold mineral waters which are widely spread around Baikal Lake. Studied mineral waters were divided into CH4, N2 and CO2-rich waters by the associated gas composition. We found that the highest REE concentrations were connected with thermal waters that were accumulated in swamps (slow-moving waters). Another core process for accumulating of REE in waters is the rock weathering in CO2 presence. This study shows that there are no correlations between REE and main ions, Eh, TDS and temperature. But dependence of REE on pH and positive correlations of REE with Al, P, Mn, V, Cu, Pb and As, which indicate common processes of microelements migration, were established. Within the study waters the light REE concentrations dominate over heavy REE. The presence of CO2 gas increases heavy REE concentrations, and concentrations of several light elements (La, Ce, Nd). The observed differences in REE contents in studied waters can be provenance dependent and possibly relate to more complicated evolutionary processes as water circulation time, depth and mixing. This is the first investigation of REE distribution and abundance in mineral waters of the Baikal Lake.

Hydrodynamics of Direct Contact Condensation Process in Desuperheater

Due to global environmental conditions, the focus of household heating has shifted from fossil fuels towards environmentally friendly and renewable energy sources. Desuperheaters have attracted attention as a domestic provision involving steam-induced direct contact condensation (DCC)to warm the water. The present study is an attempt to investigate the hydrodynamics in the desuperheater vessel experimentally, namely, when the pressurized pulsating steam is injected into the vessel, where the steam jet interacts co-currently with the slow-moving water. Flow visualization showed a circulation region when the pulsating steam was injected into the slow-moving water, and the peaked vorticity corresponded to the steam injection duration of 10–60 s. Sevenhot film anemometers (HFAs) were traversed axially and radially to determine the velocity fluctuations at 0–20 cm from the steam’s nozzle exit. Vortical structures indicated the entrainment of the steam with the surrounding moving water. The circulation regions were thus exhibited in relation to the steam’s injection durations as well as the downstream axial distances of 2 and 15 cm from the nozzle exit, which showed that the core local circulation at 2 cm downstream of the nozzle exit lost 75–79% of its circulation at 15 cm downstream of the nozzle exit.

What Distinguishes MJO Events Associated with Atmospheric Rivers?

Abstract Atmospheric rivers (ARs) are long and narrow bands of intense water vapor transport that often induce heavy precipitation and flooding along the west coast of North America. Previous studies demonstrate that the Madden–Julian oscillation (MJO) contributes to the predictability of AR activity on a subseasonal time scale. However, individual AR responses vary widely following the same phase of MJO. Here we investigate 96 MJO events following phase 3 (convection over the Indian Ocean) and analyze the differences between events that brought large-scale ARs to the entire Pacific Northwest coastal region and those that did not. The MJO events with ARs tend to stay longer at phase 3 than those without ARs. We use linear regression to isolate the extratropical signals linearly related to the MJO and explore how the residual fields differ between the two groups. The linearly dependent signal shows slow-moving planetary-scale water vapor transport across the North Pacific. The residual field exhibits a contrasting extratropical low-frequency (>10 days) pattern in the Gulf of Alaska resembling the Pacific–North American (PNA) pattern: a trough for events with ARs and a ridge for events without ARs. This low-frequency variability alters the Pacific waveguide such that, for MJO events with ARs, baroclinic waves are directed into the Pacific Northwest with an orientation that favors anomalous positive IVT. For MJO events without ARs, the ridge strengthens large-scale anticyclonic flow over the North Pacific and prevents moisture access to the Pacific Northwest.

Vectors that spread malaria: introduction to the microbiome-science of mosquitoes

Amongst six main mosquito species, Anopheles minimus responsible for transmitting malaria in India. Anopheles minimus is predominant in India particularly northeastern regions and is most accountable for focal infection outbursts marked by an increase in Plasmodium falciparum diseases, and further deaths that can be directly linked to them. According to genetic analysis, Anopheles minimus (formerly species A) is the most common species occurring in India, involving the north-eastern provinces and the East-central Odisha state, out of the three species that make up the Minimus Complex, which is distributed throughout Asia. It is documented throughout the year and explains perennial transmission as shown by records of sporozoite infections. This species has been observed spawning year-round in slow-moving seepage water streams. It is also primarily endophilic and endophagic. Malaria is still a serious public health concern in many parts of the world, especially in tropical areas. It is a vector-borne infectious disease. The protozoan parasite Plasmodium, which causes malaria, is spread via the bite of female Anopheles mosquitoes carrying the infection. Insecticide-treated nets (ITNs) and indoor residual spraying are the major methods used in the control interventions aimed at mosquito vectors that have shown great success over the past 20 years (IRS). Unfortunately, natural mosquito populations are developing resistance to the conventional pesticides now employed in public health, which is impeding the efficacy of the existing vector management measures over the long run. Therefore, it appears vital to enhance vector control strategies through the creation of novel, environmentally friendly methods in order to reach the objective of eliminating malaria. Our review article provides background for describing the biology, information gaps, and possible public health danger of Anopheles viruses.

Effects and mechanism of ultrasound treatment on Chironomus kiiensis eggs.

Chironomids are abundant insects in freshwater ecosystems and lay in still or slow-moving water. The walls of sedimentation tanks in drinking water treatment plants (DWTP) provide such laying habitat, which can lead to larval outbreaks in plant effluent. While chironomid larvae are often associated with poor hygiene, effective methods to control outbreaks are needed. Here, we assessed the effect of ultrasound treatment on Chironomus kiiensis' eggs. The mortality rate of eggs was examined after ultrasound treatment, and the protein content (heat shock protein 70 and hemoglobin) and enzymatic activities of acetylcholinesterase, cytochrome P450, and glutathione S-transferases involved in the ultrasound-induced stress response were analyzed before and after treatment. COMSOL software was also used to examine the characteristics of the ultrasonic field, including frequency, power, exposure distance, and time. Higher egg mortality was observed at lower frequencies. At 28kHz, 450W, 15-mm exposure distance, and 75-s exposure time, 72.4% of eggs showed apoptosis after exposure. At higher frequencies (68kHz), mortality decreased to 50.9%. Exposure time and distance also significantly affected egg mortality. From the geometric models, it could be seen that C. kiiensis' eggs sustained much greater acoustic pressure (2379Pa) with 28-kHz exposure than that with 68-kHz exposure (422Pa); however, the propagation distance was greater at the higher frequency. The hydraulic shear force effect of the ultrasonic radiation appeared to be the primary factor in egg mortality. We expected that array of ultrasonic transducers embedded in the walls of water treatment plants could be effective in killing Chironomus' eggs and highlight the potential for ultrasound as an effective treatment for the prevention of Chironomus outbreaks in treatment plant effluents.

A new species of Acentrella Bengtsson, 1912 (Ephemeroptera: Baetidae) from Thailand.

Following a series of biodiversity surveys conducted in Thailand, Acentrella fimbriata sp. nov. is described and illustrated based on the nymph, male subimago and egg stages. Our new species can be distinguished from other Acentrella species by the following combination of characteristics in the nymphal stage: a head capsule relatively densely covered with long, fine, simple setae, increasing in number on the genae and clypeus; the scape and pedicel densely covered with long, fine, simple setae along the inner margins; femoral margins with dense, irregular rows of long, simple setae; terga lateral margins with numerous fine, simple setae, increasing in number posteriorly; terga posterior margins with poorly-developed denticles, and with scattered ovoid and truncated translucent scales, increasing in number laterally; and gills on segments IIVII with abundant long, fine, simple setae apically. This species prefers cobble substrates in shallow and slow-moving water, where it is found covered with sediment. Extensive new reports of Acentrella (Liebebiella) vera (Mller-Liebenau, 1982) are given that show it to be a species widespread in Thailand and that provide basis for comparisons to our new species. Global systematics of Acentrella Bengtsson, 1912 are discussed.

Comparison of Mosquito Larvicidal Formulations of Diflubenzuron on Culex Pipiens Mosquitoes in Belgrade, Serbia

Abstract Culex mosquitos are important infectious diseases vectors in temperate and tropical regions of the World, affecting nearly 350 million people in both developed and developing countries. Our approach was to “recycle” the well-established larvicide, and by studying the tablets, pellets and granules as floating or sinking formulations, we found a method to optimise the use of diflubenzuron against Culex pipiens mosquitoes in field conditions. A standard WHO procedure was used to test the larvicide efficacy. The combined efficacy of all floating formulations was 10.7% higher than sinking preparations (p-value =0.002) and that maximised throughout the experiment on days 14 and 21, (p-values 0.012 and 0.008, respectively). All floating formulations kept their efficacies above 70% until day 21 of the experiment, while the mortality of sinking designs dropped significantly after day 14. The lowest efficacy was observed when sinking granules were used and the highest when floating tablets were applied in the canals. Only the floating tablets showed no significant changes in efficacy from day 1 to 21, but then that efficacy drops sharp until day 35. Since the larvae spend most of their time on the surface of the slow-moving waters to breathe, and floating pellets and tablets are made of materials that can serve as food sources, we conclude that these formulations have a higher efficacy, at least in conditions of non- or slow-moving waters. This study shows the importance of a systematic approach to reformulation of old, already proven and environmentally safe larvicides which can control the mosquito populations and their spreading of various pathogens.

Male zebrafish (Danio rerio) do not preferentially associate with familiar over unfamiliar conspecifics.

Members of several shoaling species have been shown to prefer to associate with familiar individuals, enhancing the benefits of aggregation. The authors used a series of social preference tasks in the laboratory to evaluate whether prior familiarity with potential partners influences preference of shoaling partner in male zebrafish (Danio rerio), a social species found in shallow, slow-moving waters. The authors found that though male zebrafish exhibited a strong preference for shoaling with a male conspecific as opposed to remaining alone, they exhibited no preference for familiar over unfamiliar conspecifics. This suggests that the benefits of familiarity for shoaling behaviour may not be as important for male zebrafish as has been shown in other social fish species.

Non-Invasive Groundwater Velocity Measurements Using a Novel Electromagnetic Flowmeter

Tracing groundwater flow is of vital importance for managing water resources and understanding the natural water cycle. However, it is a challenge to make accurate measurements of groundwater flow due to its extremely low velocity. A new electromagnetic flowmeter has been developed to conduct non-invasive groundwater flow velocity measurements. In the setup, a customized trapezoidal current source was connected to a 1 m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 1 m square coil to generate a strong vertical magnetic field. Two electrodes were used to sense the potential difference caused by water flowing through the magnetic field. A simulation has been developed based on Faraday’s law to evaluate the flow signal under an idealized condition. Two different lab environments have been built for testing the device: an artificial mini-aquifer and a rolling gantry. The measurements show that the flow signal, in practice, generated by the slow-moving water was orders of magnitude smaller than the inductive and capacitive interferences in the system. A linear signal processing model has been developed, allowing the flow signal to be extracted from the measured results. The results show good agreement with simulation and a strong correlation between the flow speed and the processed flow signal, having an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R^{2}$ </tex-math></inline-formula> coefficient of 0.94.

Design, Analysis, and Fabrication of Water Turbine for Slow-Moving Water

Abstract The energy crisis of the modern era may be overcome by hydrokinetic energy, the most readily and free source of energy available, to provide basic electricity needs to remote and urban areas at a low cost. The kinetic energy of flowing water at low speed could be extracted effectively by designing an appropriate design of the blade, as the turbine’s performance is dependent upon the shape of its blade. In this study, the wind turbine model with some modifications was used to design a blade for the hydrokinetic turbine. The horizontal axis turbine model with propeller type configuration was selected for obtaining higher efficiency. The optimum hydrofoil was selected and designed with an optimal twist angle for the maximum energy extraction process. The model was designed in three-dimensional (3D) modeling software solidworks, and then the power analysis was carried out through numerical simulations using the commercial computational fluid dynamics package ansys fluent. The power output was analyzed with a different number of blades, and performance curves were generated for the most efficient system. The calculations exhibited that for 1.5 m/s rated speed of water with the rotor diameter of 0.6096 m provides the rated power of approximately 150 W at 110 RPMs. The power curve of the turbine was analyzed for the selection of an efficient Permanent Magnet Synchronous Generator, and a direct drive system was preferred to reduce the weight and losses. The turbine model was 3D printed for testing and experimentation. The analytical efficiency calculated was 30.52%, and the experimental efficiency achieved was 28.24%. This study shows that the optimum design of hydrokinetic turbines could be integrated into series to provide energy to remote areas where the construction of dams and other resources are not available.

Knowledge, Attitudes, and Practices on Urinary Schistosomiasis among Primary Schoolchildren in Nelson Mandela Bay, South Africa.

Background Schistosomiasis remains a public health concern in South Africa (SA), with the highest prevalence of infection found among schoolchildren under the age of 15 years. Knowledge, attitude, and practices (KAP) studies on schistosomiasis among schoolchildren under the age of 15 years are lacking in the study area. The study therefore assessed primary schoolchildren in Grades 4–7 to determine their knowledge regarding schistosomiasis in the various ages represented in these grades. Methods The study employed a quantitative descriptive, cross-sectional survey research design approach. A structured, close-ended, Likert-scale, self-administered questionnaire was used to collect data from 458 learners in Grades 4 to 7 aged from 9 to 16 years. Data were analysed using Statistica version 13 software. Bivariate and multivariate techniques were further used to analyse and describe the data and significant associations at p = 0.05 were further interrogated using Cohen's d and Cramér's V, to determine the practical significance. Results Of the 458 learners who completed the questionnaire, 248 (54%) acknowledged having heard of schistosomiasis previously. There was a positive correlation between knowledge and attitude (0.779). The KAP scores were calculated as a percentage ranging between 0% and 100%, and this range was split into five equal width intervals 0–19%, 20–39%, 40–60%, 61–80%, and 81–100%. For knowledge, 210 (46%) of the participants obtained a score in the interval 0–19%. For attitudes, 237 (52%) of the participants obtained a score in the interval 0–19%. Therefore, the overall knowledge and attitudes among the study participants towards schistosomiasis were poor. There was a significant difference (p = 0.0005, V = 0.42 medium) between male and female participants relating to their practices. It was observed that a high percentage, 69 (15%) of males reported to swimming in slow-moving water compared to a significantly lower percentage, 9 (5%) of females. Furthermore, 23% of the participants reported that there was a river on the way to school. Conclusion The study revealed that there was a positive correlation between knowledge and attitude. The overall knowledge and attitudes on schistosomiasis were poor. Furthermore, a gender-related difference based on practices emerged significant in the study. The findings are thus valuable in designing effective and targeted schistosomiasis control programmes.