Submergence Conditions Research Articles

Performance of different rice genotypes cultivated under submergence and normal growing conditions

Abstract Submergence negatively affects the plant growth and yield of rice genotypes, which in turn results in huge financial loss. Thus, identification of submergence tolerance rice genotypes is needed for sustainable rice cultivation in flood-prone areas. Keeping this in view, a two-year (2019 and 2020) field study was undertaken at Rice Research Farm of Bihar Agricultural College, Bihar Agricultural University, Sabour, Bhagalpur to investigate and compare the yield responses of rice genotypes under submergence and normal growing conditions. Twenty-five days old seedlings of 25 rice genotypes were transplanted in a randomized complete block design in two replicates, which were allowed to grow under normal practice for the next 25 days. Thereafter, the 50-day old plants were completely submerged with turbid water of 1.5 m height for the next 18 days. After de-submergence, all the recommended agronomic practices were adopted during the rest of the crop period. Under submergence, higher grain yield was recorded under all the genotypes during 2020 as compared to 2019 mainly due to higher temperature and lesser rainfall during 2020. Under submergence conditions, Jalmagna, Nona Bokra and Swarna Sub 1 were the best performers having produced average yields of 3,167, 2,786 and 2,741 kg/ha, respectively. Whereas under normal growing practice, Swarna Sub 1, Jalmagna and Sudha were the first three best performing genotypes producing average yields of 5,063, 4,565 and 4,456 kg/ha, respectively. Therefore, Jalmagna should be preferred for cultivation in the flood-prone regions of the state, however in non-flooded areas; Swarna Sub 1 may be cultivated.

Positive contribution of shoot apex to the growth and flooding tolerance of Hemarthria altissima upon complete submergence

ABSTRACT Flooding events tend to destroy the original flood-intolerant vegetation in riparian zones, but the flood-tolerant species can confront the stress, and contribute to the riparian ecosystem. Grass species, Hemarthria altissima, are usually dominant in the riparian zones. This species is considered as good forage which is usually grazed by livestock or mowed by local people. Therefore, the apical tissues of the plants are often removed, and the plants have to grow without stem apexes, during their life cycle. In this study, we aimed to examine the differences in growth performance of intact versus apex-cut individuals of H. altissima upon complete submergence. Two groups of H. altissima plants (with and without shoot apexes) were treated with dark non-submergence and dark complete submergence conditions for 200 days. During the experiment, we measured plant growth, biomass changes in plant organs, and the consumption of non-structural carbohydrates (NSC) by different tissues. During submergence, shoot elongation stopped, and around six lateral buds were developed averagely by each plant without apexes. This growth performance finally caused 60% decline of NSC in underground parts. The relatively intensive consumption of carbohydrates in submerged apex-removed plants induced the 21% stem length decreased under water, which indicated the decreasing submergence tolerance of plants with shoot apex removed. Therefore, we suggest that when using H. altissima for restoring degraded riparian ecosystems, the shoot apexes should be protected from grazing by livestock or harvesting by local people in order to maintain the submergence tolerance of H. altissima.

Exogenous metabolite application is a potential strategy for expanding the use of direct rice seeding with the aim of reducing seeding costs

Rice is a staple food for over half of the global population, necessitates efficient and cost-effective production methods to ensure food security. However, direct seeding of rice often encounters challenges due to adverse environmental conditions, resulting in increased seeding costs. In this study, we analyzed the germination and physiological data of sixty-six rice varieties under cold and submergence conditions. Our results demonstrate that selecting rice varieties with superior germination capacity in these adverse conditions can improve germination rates by 39.43%. Transcriptomic and metabolomic analyses of two contrasting varieties revealed potential regulatory mechanisms involving hormonal pathways and the glycerophospholipid metabolism pathway. Furthermore, we found that the exogenous application of specific metabolites provides a cost-effective seed enhancement strategy for varieties with poor germination capacity. These findings suggest that combining suitable variety selection with seed enhancement treatments can significantly reduce seeding costs in rice production. This research offers valuable insights for developing resilient rice varieties and cost-effective seeding strategies, potentially contributing to improved rice cultivation practices and enhanced global food security.

Future Shorelines: A Living Shoreline Site Selection and Design Decision Support Tool that Incorporates Future Conditions Induced by Sea Level Rise

Most living shoreline site selection and design decision support tools are based upon existing environmental conditions. We developed a web-based, geospatial tool called Future Shorelines that integrates high-resolution landscape elevation data and a matrix of locally derived NOAA Interagency Sea Level Rise Scenarios to characterize future conditions of submergence and shoreline translation induced by sea level rise. Once the practitioner selects a location of interest, sea level rise scenario (e.g., high), and target year (e.g., 2050), the tool will generate plan view and cross-sectional informational graphics specific to their choices. This information can then be paired with other menu options, like parcel ownership, to facilitate the planning and construction of nature-based shoreline stabilization solutions that (1) are located where opportunities for horizontal migration are optimized, (2) remain accessible for monitoring and maintenance, and (3) perform as intended over the design life of the installation. The tool’s menu options and the user interface were informed by project partner input solicited during numerous workshops convened over the duration of the 2-year project. This coproduction created a product that was familiar to the end user and therefore increased the likelihood that it would be utilized by them during the planning and design of living shoreline projects. Although developed for use in the Indian River Lagoon, located along the east-central Florida coast, it can be seamlessly replicated for application in other coastal regions of the USA where the requisite data are available.

Evaluation of genetic diversity and population structure for anaerobic germination under saline submergence condition using hypervariable SSR markers in a diverse set of global rice accessions

Evaluation of genetic diversity and population structure for anaerobic germination under saline submergence condition using hypervariable SSR markers in a diverse set of global rice accessions

Experimental study of the effect of the input and output key angles on the discharge coefficient and efficiency of the PKWs

ABSTRACT The results showed that Cd, Ra, and, consequently, the increase in the passing flow discharge have a direct relationship with the inclination angle of the input and output keys, and for this reason, the weir of the piano key weir (PKW) with an angle of 90° has the highest Cd and Ra. An increase in the HT/P ratio in all angles leads to a decrease in Cd and Ra. However, the decrease rate of these parameters is less for a 15° angle compared to other threshold angles of the input and output keys. In the PKWs with different input and output key angles and at low HT/P ratios , the dropping flow nappe needs aeration due to its bonding. However, by increasing this ratio to the submergence condition and transforming into a linear weir, the dropping flow nappe is aerated. At low ratios of HT/P, the dropping flow nappes do not interfere, and the highest discharge coefficient and the highest weir efficiency are obtained. While by increasing the HT/P ratio, the dropping flow nappes start to collide and interfere with each other in the output keys, causing the flow rise and the weir submergence, and consequently, the discharge coefficient is decreased.

Oat-an alternative crop under waterlogging stress?

Waterlogging is one vast environmental constraint that limits crop growth and yield worldwide. Most major crop species are very sensitive to waterlogging, leading to enormous yield losses every year. Much is already known about wheat, barley or maize; however, hardly any data exist on oat and its tolerance against waterlogging. Thus, this study aimed to investigate if oats can be an adequate alternative in crop rotation under conditions of temporal submergence and if cultivar differences exist. Furthermore, this study was to test (1) whether yield was differently affected when stress is applied at different developmental stages (BBCH 31 and 51), and (2) nutrient imbalances are the reason for growth restrictions. In a large-scale container experiment, three different oat varieties were cultivated and exposed to 14 consecutive days of waterlogging stress at two developmental stages. Even though vegetative growth was impaired after early waterlogging and which persists till maturity, mainly due to transient nutrient deficiencies, growth performance after late waterlogging and grain yield of all three oat varieties at maturity was not affected. A high tolerance was also confirmed after late waterlogging in the beginning generative stage: grain yield was even increased. Overall, all oat varieties performed well under both stress treatments, even though transient nutrient imbalances occurred, but which were ineffective on grain yield. Based on these results, we conclude that oats, independently of the cultivar, should be considered a good alternative in crop production, especially when waterlogging is to be expected during the cultivation phase.

Introducing the halophyte Salicornia europaea to investigate combined impact of salt and tidal submergence conditions.

Tolerance mechanisms to single abiotic stress events are being investigated in different plant species, but how plants deal with multiple stress factors occurring simultaneously is still poorly understood. Here, we introduce Salicornia europaea as a species with an extraordinary tolerance level to both flooding and high salt concentrations. Plants exposed to 0.5MNaCl (mimicking sea water concentrations) grew larger than plants not exposed to salt. Adding more salt reduced growth, but concentrations up to 2.5MNaCl were not lethal. Regular tidal flooding with salt water (0.5MNaCl) did not affect growth or chlorophyll fluorescence, whereas continuous flooding stopped growth while plants survived. Quantitative polymerase chain reaction (qPCR) analysis of plants exposed to 1% oxygen in air revealed induction of selected hypoxia responsive genes, but these genes were not induced during tidal flooding, suggesting that S. europaea did not experience hypoxic stress. Indeed, plants were able to transport oxygen into waterlogged soil. Interestingly, sequential exposure to salt and hypoxic air changed the expression of several but not all genes as compared to their expression upon hypoxia only, demonstrating the potential to use S . europaea to investigate signalling-crosstalk between tolerance reactions to multiple environmental perturbations.

Development of Submergence Tolerant Rice Variety BRRI dhan79 for Flash Flood Ecosystem of Bangladesh

Tolerance to submergence stress is an important breeding objective for the areas where rice cultivars are subjected to complete inundation for a week or more. Submergence tolerance is an important trait for rice (Oryza sativa L.) in the flash flood-prone ecosystem. The trait is largely controlled by a major gene designated as Sub1 located on chromosome 9. Submergence of rice (Oryza sativa) by flash flooding is a major constraint to rice production in Bangladesh. Quantitative trait loci analyses have revealed that a large portion of this variation in submergence tolerance can be explained by Sub1. A newly released submergence tolerant rice variety namely BRRI dhan79 was developed by hybridization between BRRI dhan49*6/BRRI dhan52 through Marker Assisted Backcrossing and selection method where BRRI dhan52 (submergence tolerant mega variety in Bangladesh) used as Sub1 donor. It can tolerate upto three weeks complete submergence at vegetative stage whereas Sub1 donor mega variety BRRI dhan52 can tolerate on an average two weeks complete submergence condition. It can also tolerate 50-60 cm water stagnation for 15-20 days after de-submergence. The variety has satisfactorily been passed in the proposed variety trial conducted in flash flood prone farmers' field in Bangladesh. As a result, the National Seed Board (NSB) of Bangladesh approved this rice variety for commercial cultivation for the flash flood affected rainfed lowland ecosystem (Transplanted Aman season) in 2017. It meet up all the trait of modern plant likely medium plant heihght (112 cm), strong and stature culm structure, erect flag leaf with stay green leaf at maturity stage and high yield potential with 140 days growth duration (in case of three weeks submergence mature by 160 days). It can produce 5.5 t/ha grain yield under non-stress condition and 4.0-4.5 t/ha yield under three weeks submergence condition. The grain shape of the variety is medium bold. The rice production scenario in flash flood affected region of Bangladesh has been remarkably improved after releasing this rice variety. It has not only change the socio-economic status of farmers but also sustaining food security.

Turbulent Characteristics of a Submerged Reef under Various Current and Submergence Conditions

Submerged Reefs (SRs) are a kind of artificial fish habitat that can protect coasts and maintain ecological biodiversity. In this study, the flow field of the SR is simulated by solving a Reynolds-averaged Navier–Stokes equation closed with the Realizable k-ε model based on the finite volume method. The turbulent characteristics of SRs under different inflow velocities and submergences in the vicinity of the SR are analyzed. The wake vorticities are the primary turbulent pattern within and around the SR. The back wake and vorticity are chosen as critical indicators to quantitatively assess the hydrodynamic characteristics induced by the SR. The results show: (1) as the main flow passes through the SR, the upwelling is produced in front of the SR and a large-scale wake region is formed behind the SR which contains a clockwise vortex; (2) the length of the wake region formed behind the SR is positively and linearly correlated with both the inflow velocity and submergence; (3) the dipole-type vorticity patterns are induced within the compartment of the SR, where the area and average value of high vorticity have a positive correlation with the flow velocity and a negative correlation with the submergence, respectively.

Impact of Submergence1 (Sub1) Locus in Genetic Background of Modern Rice Varieties (Oryza sativa L.)

Aim: To improve submergence stress tolerance of modern rice varieties (ADT36 and ADT37) through selection of superior rice lines.
 Study Design: Backcross method.
 Place and Duration of Study: This effort was taken in Nethouse of Kandaswami Kandar’s College, Namakkal District, Tamil Nadu, India. This process was completed in four years from 2019 to 2022.
 Methodology: Here, widely cultivated two short-term rice varieties (ADT36 and ADT37) were selected to improve submergence tolerance based on polymorphism at phenotypic and genotypic level. Then, they were improved through backcrossing with respective recurrent parent by selection of superior rice lines compared to parental lines under submergence condition. Likewise, this process was advanced up to BC3F2 generation.
 Results: In this study, a number of two NILs for ADT36 rice variety (ADT36- F12-5-19.18 and ADT36- F15-2-5.17) and five NILs for ADT37 rice variety (ADT37- F113-27-5.2, ADT37- F113-27-5.5, ADT37- F115-2-1.10, ADT37- F115-2-1.14 and ADT37- F115-2-2.14) are selected as superior lines.Selected rice lines exhibited more than 60% submergence tolerance than donor parent. This result indicates the adaptation of Sub1 locus into new genetic background of ADT36 and ADT37 rice variety under submergence condition.
 Conclusion: Improvement process of rice lines under stress condition results in identification of highly active rice lines. Thus, selected submergence tolerant rice lines would be a boon to the rice farmers who are facing crop lose due to frequently occurring cyclones in the Cauvery delta region.

Concretion

The ruins of wrecked ships are often so thoroughly dispersed by their submarine environments as to practically vanish. Sometimes, however, the conditions of a wreck's submergence create complex modes of material endurance. Concretion, which names both a substance that forms on certain immersed surfaces and the phenomenon of that substance's formation, is one such mode. Inspired by maritime-archeological objects and practices, this article asks how concretion—from the Latin concrēscĕre for “to grow together”—marks and reworks imperial (and other) presences at the seabed. The article develops a hermeneutics of benthic becoming at intersections in literary studies, critical theory, cultural geography, and recent subsea turns in the oceanic (and more broadly environmental) humanities. Wrecky concretion, I argue, configures the thickening presences of empire's remains in the course of their underwater lives and in company with seawater, marine organisms, and inanimate beings. In this way, manifestly imperial presences actively coincide with others—and with the agencies, memories, and affects such presences may be understood to express (and not). Pivotally informed by Édouard Glissant's critical deeps, Derek Walcott's “The Sea Is History” (1978), and the politics of memory enacted by the Slave Wrecks Project and Diving with a Purpose, I observe a few of the ways that concretion may be punctuating and revising oceanic spaces, memories, and times. If the world ocean has long been unevenly composed by modernity, capitalism, and empire, it has also been reforming the wrecked stuff it receives into unanticipated configurations, growings-together that these pages provisionally ascertain.

Wave-impact forces and moments due to random waves on a jacket-type platform for different relative submergence of the deck

Force and moment measurements due to wave impacts were conducted on a jacket platform model under six distinct relative deck submergence conditions. The water depth was carefully chosen to facilitate scenarios ranging from sufficient deck air gaps to partial and complete submergence. For the purpose of our analysis, we focused on peak and average peak wave force and moment values. The study uncovers that the peak wave force towards the shore can escalate to 1.5 times the peak wave force towards the sea. Moreover, the ratio of the peak shoreward force to the average peak shoreward force fluctuates between 3 and 4, contingent upon the relative water level at the deck base and the prevailing wave condition. Remarkably, the peak upward wave force on the deck can reach 5 to 7 times the peak inline wave force. A review of existing guidelines suggests a significant need to enhance research regarding the air gap between the deck and the still water level (SWL), as well as its effect on global and local wave forces and moments on the structures. Our finding establishes that the relative water level from the base of the deck is a crucial parameter in the design process of these structures. This study presents a more in-depth understanding of the physical mechanisms at play by utilizing a realistic jacket platform model. It serves as an initial exploration into the influence of air gap and relative water depth on wave-impact forces and moments. The results obtained from this study shed light on optimal design strategies for jacket-type offshore drilling platforms, considering green water effects. This understanding will enhance the life expectancy and survivability of such platforms.

Impact of Climate Resilient Technology on Growth and Yield of Paddy (Oryza sativa L.) under Submergence Condition

The submergence of rice fields is a significant issue in India's rice production, which is further aggravated by the unpredictable monsoon rain patterns and the impact of climate change. Larger variation in rainfall patterns affected by the timing of nursery raising and transplanting later in the main field therefore, we adopted Climate Resilient Technology (CRT) for rice production, Extended seedbed durations for rice seedlings allow for adequate rainfall during the monsoon season. So that the experiment was conducted at 30 farmer’s fields of NICRA village, Khana Bari, Kishanganj, Bihar, India, in 2022 under the supervision farm science Center, Kishanganj, the experiment was framed in randomized block design with ten replications. All plots received the recommended dose of fertilizers (120:60:40 kg ha-1 N.P.K.) in equal amounts. Urea, di-ammonium phosphate, and muriate of potash were used as the sources of nitrogen, phosphorus, and potassium, respectively. To determine the growth characters i.e., plant height (cm) at harvest stage, number of effective tillers hill-1, LAI, Chlorophyll concentration (SPAD) and days to 50 per cent flowering were recorded at 90 days. Yield attributes viz., After the completion of the harvest, various observations were recorded, such as the number of panicles/m2, the number of grains per panicle, the number of filled and unfilled grains per panicle, the test weight in grams, and the yield. This encompassed grain yield, straw yield, biological yield in quintals per hectare, and harvest index percentage. During the field experiment, both the climate-resilient technology Swarna Sub1 and Sabour Sampans paddy varieties were tested. Swarna Sub1 was found to be significantly superior in terms of plant growth, yield attributes, and yield characteristics. under submergence conditions. The significant maximum grain yield (48 q ha-1), straw yield (84 q ha-1), biological yield (153 q ha-1), and harvest index (45%) were recorded in Swarna Sub-1.

Physiological responses and Ethylene-Response AP2/ERF Factor expression in Indica rice seedlings subjected to submergence and osmotic stress

BackgroundThe increased frequency of heavy rains in recent years has led to submergence stress in rice paddies, severely affecting rice production. Submergence causes not only hypoxic stress from excess water in the surrounding environment but also osmotic stress in plant cells. We assessed physiological responses and Ethylene-Response AP2/ERF Factor regulation under submergence conditions alone and with ionic or nonionic osmotic stress in submergence-sensitive IR64 and submergence-tolerant IR64-Sub1 Indica rice cultivars.ResultsOur results indicate that both IR64 and IR64-Sub1 exhibited shorter plant heights and root lengths under submergence with nonionic osmotic stress than normal condition and submergence alone. IR64-Sub1 seedlings exhibited a significantly lower plant height under submergence conditions alone and with ionic or nonionic osmotic stress than IR64 cultivars. IR64-Sub1 seedlings also presented lower malondialdehyde (MDA) concentration and higher survival rates than did IR64 seedlings after submergence with ionic or nonionic osmotic stress treatment. Sub1A-1 affects reactive oxygen species (ROS) accumulation and antioxidant enzyme activity in rice. The results also show that hypoxia-inducible ethylene response factors (ERF)-VII group and alcohol dehydrogenase 1 (ADH1) and lactate dehydrogenase 1 (LDH1) genes exhibited different expression levels under nonionic or ionic osmotic stress during submergence on rice.ConclusionsTogether, these results demonstrate that complex regulatory mechanisms are involved in responses to the aforementioned forms of stress and offer new insights into the effects of submergence and osmotic stress on rice.

Thermal Performance of Foam Glass Aggregate at Different Compaction Ratios

The use of glass waste in the construction industry has a high potential of leading to a higher recycling percentage. Foam glass aggregate (FGA) is around 98% recycled glass waste of various origins and has good insulation properties with big grain size distributions ranging between 10 mm and 60 mm. FGA has a wide range of applicability in the construction industry, which significantly differs from each implementation in the case of built-in conditions of the material. Therefore, investigating the impact of different compaction ratios, temperature, and relative humidity conditions on the thermal performance of such material is very important. In the present work, the samples of foam glass aggregates have been prepared with four different compaction ratios (10%, 20%, 30%, and 40%) to measure their impact on the material’s mechanical and thermal insulation properties. The obtained results revealed that the dry density property of the material linearly increased with elevated compaction ratios. In contrast, the submergence density did not follow the same trend behaviour under the same circumstances. The vertical strain of the foam glass aggregates decreased with increased compaction ratios, and a significant correlation behaviour was observed between the vertical strain and increased compaction ratios at high compressional loads. The material’s thermal conductivity increased with increasing compaction ratios in both 50% relative humidity and 95% relative humidity, while for the submergence condition, a significant decrease in their values was observed after compacting the material by 40%. The thermal conductivity is tested at 10 °C and 30 °C using the TLS and GHP methods. The thermal resistance of foam glass aggregate layers was calculated based on the measured results, showing an approximately linear decreasing trend with increasing compaction ratios. While the submerged foam glass aggregate samples demonstrated stable thermal resistance values at 30% compaction, by raising the compaction ratio to 40%, the material’s thermal resistance increased once again. The experimental results also found the temperature conversion coefficients, which can be used to convert the compacted FGA materials’ thermal conductivity to the temperature experienced in a different built-in state than the laboratory measurements. Our study demonstrates the broad usability of foam glass aggregate as a compacted thermal insulating layer in the building industry.

LIGHT COLOUR INFLUENCES THE MORPHOLOGICAL TRAITS OF THE Cryptocoryne elliptica Hook F., AN AQUATIC PLANT

Light is used to enhance the appearance of the fish and supports the survival of living ornamental aquatic plants in aquariums. The light required by the fresh aquatic plants is different among the species. This study examined the effects of light colours, which are white, blue, red, and green on tissue culture-derived Cryptocoryne elliptica grown under submergence conditions. The morphological traits and chlorophyll content of the planets were measured for ten weeks. Results showed that plantlets’ growth under blue light exhibited the longest petioles (4.9 ± 0.5 cm), leaf length (3.0 ± 0.2 cm), leaf width (1.3 ± 0.4 cm), and leaf number per plantlet (p < 0.05) compared to other lights. The highest chlorophyll content (0.72 mg/g fresh wt.) was recorded in the leaves of plantlets under white light. The number of newly produced shoot tips did not significantly differ among the light treatments (p > 0.05). Experimenting with different propagation methods, hormone treatments, or adjustments to light intensity or duration may provide insights into improving the production of new plantlets in future studies.

ZmWRKY70 activates the expression of hypoxic responsive genes in maize and enhances tolerance to submergence in Arabidopsis

Hypoxic stress due to submergence is a serious threat to the growth and development of maize. WRKY transcription factors are significant regulators of plant responses to various abiotic and biotic stresses. Nevertheless, their function and regulatory mechanisms in the resistance of maize to submergence stress remain unclear. Here we report the cloning of a maize WRKY transcription factor gene, ZmWRKY70, transcripts of which accumulate under submergence stress in maize seedlings. Subcellular localization analysis and yeast transcriptional activation assay indicated that ZmWRKY70 was localized in the nucleus and had transcriptional activation activity. Heterologous overexpression of ZmWRKY70 in Arabidopsis increased the tolerance of seeds and seedlings to submergence stress by upregulating the transcripts of several key genes involved in anaerobic respiration, such as group VII ethylene-responsive factor (ERFVII) (AtRAP2.2), alcohol dehydrogenase (AtADH1), pyruvate decarboxylase (AtPDC1/2), and sucrose synthase (AtSUS4), under submergence conditions. Moreover, the overexpression of ZmWRKY70 in maize mesophyll protoplasts enhanced the expression of ZmERFVII members (ZmERF148, ZmERF179, and ZmERF193), ZmADH1, ZmPDC2/3, and ZmSUS1. Yeast one-hybrid and dual-luciferase activity assays further confirmed that ZmWRKY70 enhanced the expression of ZmERF148 by binding to the W box motif located in the promoter region of ZmERF148. Together, these results indicate that ZmWRKY70 plays a significant role in tolerance of submergence stress. This work provides a theoretical basis, and suggests excellent genes, for biotechnological breeding to improve the tolerance of maize to submergence through the regulation of ZmWRKY genes.

Microscopy research of the steel surface layer in the splash area of ships and ocean technical facilities

The authors of the article describe research of the surface steel layer for the conditions of continuous submergence into the seawater test solution and for the splash area of ships and ocean technical facilities. Results of microscopic examination indicated a substantial difference in the structure and composition of the surface layer depending on the experimental conditions. Further study of the obtained elemental composition and microscopy images will allow the development of the computer-aided data analysis procedure based on the computer vision system with the application of intellectual frameworks to predict shipbuilding steel potentials at various stages of exposure to seawater with the aim to enhance corrosion protection methods.

3D numerical investigation of flow behavior in an open channel with uniform and layered vegetation patches under varying submergence conditions

Staggered vegetation patches (central and outer) in an open channel have a significant effect on flow structure and river geomorphology. Although investigation on vegetation patches has been done in the past, however none of the past studies was carried out for varying submergence conditions from outer to central patches or for layered staggered patches with varying submergence. This knowledge gap has been attempted to bridge in this study. In this research work, a numerical technique has been used to analyze the flow behavior in a riverine flow by modeling central and outer vegetation patches as rigid elements in a rectangular channel. The influence of various vegetation patch configurations and submergence conditions were studied on flow characteristics. Computational fluid dynamics (CFD) package FLUENT was used for simulation purposes. Results showed that the flow in the central region of the channel was highly non-uniform, having a longitudinal distribution of velocities with alternating peaks and troughs throughout the central portion of the channel. However, in the outer regions, the velocity pattern acquired sawtooth distribution inside the patch regions (PR) but stabilized in the free regions (FR). Outer FR has 9% less velocities as compared to central FR. Moreover, the inflection point in velocity profiles and the bulge in contour plots was observed which triggered the shear layer at the top of submerged vegetation and at the interface of outer FR and central PR or vice versa. A complex pattern of secondary flow was also observed due to the turbulence anisotropy in the channel and its magnitude ranged from 0.1 to 3.7% of average velocity U. The results also showed that the state of submergence has a notable effect on the flow blockage and percentage of discharge passing through various regions.