Journal articles: 'Water stratification'

1

He, Zhiguo, Liang Zhao, and Ching-Hao Yu. "HYDRODYNAMIC MECHANISM OF TURBIDITY CURRENTS IN ESTUARY STRATIFICATIONS." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 80. http://dx.doi.org/10.9753/icce.v36.risk.80.

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Water stratification commonly exists in nature, such as thermocline in lakes and oceans and halocline in estuaries and oceans (He et al. 2017). Turbidity currents in estuary often encounter stratified sea water, which may significantly influence their propagation and deposition. This study presents high-resolution numerical simulations of lock-exchange gravity and turbidity currents in linear stratifications on a flat bed. Laboratory experiments are conducted to validate the numerical model and good agreements between numerical results and measurements are found. The evolution process, front velocity, internal wave, and entrainment ratio are analyzed based on the numerical results. For a gravity current in a strong stratification, its front velocity can be maintained as a near constant state for a long time after an initial acceleration period because of interactions between the current and internal waves. However, sedimentation of suspended particles due to the damping effect of ambient stratification on turbulence makes a turbidity current quickly lose its structure so the maintaining effect of the internal waves on its front velocity is quite weak. During the evolution process of a turbidity current, the ambient stratification is found to damp the turbulent structures, and front velocity. Stratification can also decrease the entrainment ratios between a gravity current and ambient water after the initial period, but it has an insignificant influence on the entrainment ratios of a turbidity current. This study provides a better understanding of gravity and turbidity currents in estuary stratifications.

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Hinz, Denis F., Simon Graner, and Christian Breitsamter. "Stratification in hot water pipe-flows." Energy Procedia 116 (June 2017): 324–33. http://dx.doi.org/10.1016/j.egypro.2017.05.079.

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Han, Y. M., R. Z. Wang, and Y. J. Dai. "Thermal stratification within the water tank." Renewable and Sustainable Energy Reviews 13, no. 5 (June 2009): 1014–26. http://dx.doi.org/10.1016/j.rser.2008.03.001.

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Rosengarten, G., G. Morrison, and M. Behnia. "A Second Law Approach to Characterising Thermally Stratified Hot Water Storage With Application to Solar Water Heaters." Journal of Solar Energy Engineering 121, no. 4 (November 1, 1999): 194–200. http://dx.doi.org/10.1115/1.2888166.

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This paper presents a method of characterising and evaluating the performance of hot water storage systems in terms of their temperature distribution. The change in exergy from the stratified state to the delivery state depends on the stored energy and the stratification. It can thus he used to define the storage efficiency for sensible heat storage devices. A new parameter that isolates the stratification component of the exergy is defined and called the stratification efficiency. The effect of temperature distribution, delivery temperature and tank cross-section on exergy and stratification efficiency is investigated. The advantage that stratification offers over a mixed tank is examined in terms of the storage efficiency and overall solar water heating system performance. Exergy is used to assess the operation of mantle heat exchangers in solar water heating systems and it is shown that exergy and stratification efficiency, as well as energy, should be used to ascertain the performance of such heat exchangers.

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Chuo, P. Y., J. E. Ball, and I. H. Fisher. "Thermal stratification in drinking water service reservoirs." Australasian Journal of Water Resources 6, no. 2 (January 2003): 159–67. http://dx.doi.org/10.1080/13241583.2003.11465219.

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Hariharan, K., K. Badrinarayana, S. Srinivasa Murthy, and M. V. Krishna Murthy. "Temperature stratification in hot-water storage tanks." Energy 16, no. 7 (July 1991): 977–82. http://dx.doi.org/10.1016/0360-5442(91)90057-s.

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Davidson, J. H., and D. A. Adams. "Fabric Stratification Manifolds for Solar Water Heating." Journal of Solar Energy Engineering 116, no. 3 (August 1, 1994): 130–36. http://dx.doi.org/10.1115/1.2930071.

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The level of thermal stratification that can be maintained in forced-flow, direct solar water-heating systems using a fabric manifold is studied in a 372-liter tank with an inlet flow rate of 0.07 1/s. A rib-knit, lightweight, spun-orlon acrylic is the most effective manifold material in a comparative study of 13 synthetic and natural fabrics. Thermal stratification (or more appropriately mixing) in the tank equipped with this acrylic manifold is compared to the level of stratification achieved using a rigid, porous manifold and a conventional drop-tube inlet. Initial tank temperature profile, temperature of the water entering the tank, and test duration are varied in three testing schemes. Comparison of vertical temperature profiles and height-weighted energy stored in the tank indicate that under realistic operating conditions, the fabric manifold is 4 percent more effective than the rigid manifold, and 48 percent more effective than the conventional drop-tube inlet.

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Liu, Chang, Shiyan Wang, Liang Wang, Xiaobo Liu, Huaidong Zhou, Budong Li, and Yanliang Du. "Characteristics and driving factors of thermal stratification evolution in Daheiting Reservoir." E3S Web of Conferences 261 (2021): 04010. http://dx.doi.org/10.1051/e3sconf/202126104010.

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Thermal stratification which is common in water bodies is subject to such factors as the water depth of the water body (a lake or reservoir, for instance), the fluidity of the water and the local meteorological conditions. The stable thermal stratification in reservoirs will lead to changes in the physical and chemical properties of the water as well as distribution of aquatic creatures, hence leaving an impact on the water quality. The Daheiting Reservoir was taken as the research object in this study. Based on the continuous monitored water temperature data in the reservoir, the tempo-spatial change features of the water temperature structure in the reservoir were analyzed, and the driving factors of thermal stratification in the reservoir was studied. The research found that air temperature, wind speed, and hydrodynamic factors are the driving factors for the thermal stratification and corresponding water temperature change patterns in Daheiting Reservoir. Among these factors, air temperature is the fundamental precondition, the wind speed is the auxiliary precondition, and the hydrodynamic factors are the disturbance factors for thermal stratification in the Reservoir. All these factors act together to cause the thermal stratification pattern and evolution features in Daheiting Reservoir.

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Struve, Daniel K., Brian A. Oleksak, Takayuki Kawahara, and Ayako Kanazashi. "Germination of Japanese Stewartia Seeds: The Effects of Warm and Cold Stratification." Journal of Environmental Horticulture 17, no. 4 (December 1, 1999): 197–202. http://dx.doi.org/10.24266/0738-2898-17.4.197.

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Abstract Japanese Stewartia (Stewartia pseudocamellia (Maxim.)) is a species with outstanding landscape qualities, but is not widely available because reliable propagation protocols have not been developed, including procedures for overcoming seed dormancy. Three experiments were conducted to determine the warm and cold stratification requirements of Japanese Stewartia seeds. In the first experiment, seeds given a 3-day aerated water soak in 1 mM GA3, followed by 3 months warm moist stratification at 25C (77F) had greater germination 173 to 297 days after initiation of cold (7C, 45F) stratification than seeds given a 3-day aerated water soak and similar warm and cold stratification treatments. Final germination was 70%, but germination was not synchronous, it occurred over 172 days. In the second experiment, germination was low (less than 1%) for seeds given either 9 months cold moist stratification or 3 months warm moist stratification at 20C (68F) before 6 months cold moist stratification. Seeds given a 3-month warm moist stratification at an alternating 12 hr 20/12C (68/54F) cycles and 10 months cold moist stratification germinated from 30 to 93%, depending on mother tree. Germination was asynchronous, beginning after 150 days cold stratification and continuing for the next 165 days. In the third experiment, germination was not enhanced by a 3-day aerated water soak in either 1 mM GA3 or water, compared with seeds given no aerated water soak prior to cold moist stratification. Germination was greatest, 35%, for seeds given a 3-month warm moist stratification at 15C (59F) followed by at least 4 months cold moist stratification. However, germination was asynchronous. The results begin to identify the warm and cold stratification treatments that result in high germination.

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10

KIMURA, Nobuaki, and Yasushi ISERI. "COMPARISON OF STRATIFICATION INDEXES BY WATER DENSITY DISTRIBUTION IN WATER BODIES." Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 74, no. 5 (2018): I_505—I_510. http://dx.doi.org/10.2208/jscejhe.74.5_i_505.

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11

Shi, Jianchao, Lianxiang Wang, Yongrui Yang, and Tinglin Huang. "Effects of Seasonal Thermal Stratification on Ammonia Nitrogen Transformation in a Source Water Reservoir." Processes 9, no. 12 (December 9, 2021): 2218. http://dx.doi.org/10.3390/pr9122218.

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Seasonal thermal stratification has a significant impact on water quality. In this paper, the variation of vertical distribution of ammonia nitrogen in a source water reservoir was studied, on the base of field monitoring data. The dominant factor of the variation in ammonia nitrogen is the anaerobic environment caused by the seasonal thermal stratification, which leads to the degradation of nitrogen-containing organic compounds in the sediments. To determine the rates of ammonia accumulation, an in situ experimental chamber was used. The results showed that, before the formation of thermal stratification in the reservoir, sediments in the bottom of the water have a high tendency to release ammonia; the rates of ammonia accumulation in the overlying water are 40.31–111.41 mg·m−2·d−1. However, thermal stratification causes changes in the physical and chemical properties of the sediment and reduction in the degradability of the nitrogen-containing compound in the sediment. The rates of ammonia accumulation (39.44–44.65 mg·m−2·d−1) after thermal stratification are lower than before. Considering the water pollution hazards caused by seasonal thermal stratification, it is necessary to take corresponding emergency response measures to cope with the possibility of water pollution risk.

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Jin, Juxiang, Scott A. Wells, Defu Liu, and Guolu Yang. "Thermal stratification and its relationship with water quality in the typical tributary bay of the Three Gorges Reservoir." Water Supply 19, no. 3 (August 7, 2018): 918–25. http://dx.doi.org/10.2166/ws.2018.142.

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Abstract The effect of thermal stratification and its relationship with water quality was researched by field observation in this study. Through assessing the degree of thermal stratification by calculating the dimensionless parameter of thermal resistance to mixing (RTRM) indices from 2008 to 2010, it indicated that the water body of Xiangxi River was stratified strongly in the summer months. The analysis of the degree of thermal stratification with both the meteorological and hydrodynamic factors showed thermal stratification intensity was more sensitive to meteorological factors in Xiangxi River. Through the analysis of the relationship between thermal stratification and water quality, the results indicated that the concentration of Chlorophyll a was higher in the epilimnion affected by the thermal stratification, which could cause algal bloom. The results may further help to evaluate the thermal stratification role in eutrophication process and algal bloom formation in Xiangxi River.

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Palshin, N., G. Zdorovennova, T. Efremova, S. Bogdanov, A. Terzhevik, and R. Zdorovennov. "Dissolved oxygen stratification in a small lake depending on water temperature and density and wind impact." IOP Conference Series: Earth and Environmental Science 937, no. 3 (December 1, 2021): 032019. http://dx.doi.org/10.1088/1755-1315/937/3/032019.

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Abstract The dissolved oxygen (DO) is one of the most important parameters in lakes ecosystem. Variability of DO in lakes is associated with the absorption of oxygen due to the decomposition of organic matter and chemical reactions and the release of oxygen as a result of photosynthesis. The DO concentration also depends on seasonal changes in water temperature and mixing regime. The aim of this work is to assess the influence of seasonal thermal and density stratification on the DO stratification in a small mesotrophic lake and to develop a regression DO model, with water temperature and density and characteristics of wind regime as independent variables. Long-term measurements of water temperature and DO in small Karelian Lake Vendyurskoe in 2007-2020 were used. At the stage of spring-summer heating, three periods are considered when the water column was in the state of homothermy (May 15-June 15), weak stratification (July 15-August 15), and strong stratification (July 15-August 15). The wind load (number of days with wind speed more than 3 m/s for each period) was analysed based on the weather station Petrozavodsk data. As a result of multiple regression analysis, taking into account the wind load, dependences of DO stratification on water temperature stratification (R2 = 0.51) and water density stratification (R2 = 0.61) are found. Obtained regression DO models can be used for solving various environmental tasks.

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14

Coutens, A., C. Vastel, S. Cazaux, S. Bottinelli, E. Caux, C. Ceccarelli, K. Demyk, V. Taquet, and V. Wakelam. "Heavy water stratification in a low-mass protostar." Astronomy & Astrophysics 553 (May 2013): A75. http://dx.doi.org/10.1051/0004-6361/201220967.

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15

AL-MARAFIE, ABBAS, SAFWAT M. MOUSTAFA, and ABDULLAH AL-KANDARIE. "Factors Affecting Static Stratification of Thermal Water Storage." Energy Sources 11, no. 3 (January 1989): 183–99. http://dx.doi.org/10.1080/00908318908908953.

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Mishra, Radhey Shyam. "Thermal stratification in thermosyphonic solar water heating systems." Energy Conversion and Management 31, no. 5 (January 1991): 425–30. http://dx.doi.org/10.1016/0196-8904(91)90024-d.

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17

Garnier, C., J. Currie, and T. Muneer. "Integrated collector storage solar water heater: Temperature stratification." Applied Energy 86, no. 9 (September 2009): 1465–69. http://dx.doi.org/10.1016/j.apenergy.2008.12.009.

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18

Gu, Ruochuan, Frederick N. Luck, and Heinz G. Stefan. "WATER QUALITY STRATIFICATION IN SHALLOW WASTEWATER STABILIZATION PONDS." Journal of the American Water Resources Association 32, no. 4 (August 1996): 831–44. http://dx.doi.org/10.1111/j.1752-1688.1996.tb03480.x.

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Kumar, Pradeep, and R. J. Garde. "Stratification in Laboratory Simulations of Water Hyacinth Ponds." Journal of Environmental Engineering 125, no. 4 (April 1999): 382–84. http://dx.doi.org/10.1061/(asce)0733-9372(1999)125:4(382).

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20

Al-Marafie, A. M. R. "Stratification behaviour in a chilled water storage tank." International Journal of Refrigeration 10, no. 6 (November 1987): 364–66. http://dx.doi.org/10.1016/0140-7007(87)90125-3.

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21

Krafčík, Milan, and Jana Peráčková. "Experimental Measurements of Hot Water Stratification in a Heat Storage Tank in Laboratory Conditions." Periodica Polytechnica Mechanical Engineering 63, no. 4 (June 28, 2019): 301–7. http://dx.doi.org/10.3311/ppme.13836.

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The paper focuses on the experimental measurement of the accumulation of hot water storage with its thermal stratificational thermal layers by means created of elementary conical elements. The basic principle of these elements is the automatic distribution of water temperatures according to temperature and volume flow for a specified time of storage of heat energy. This process involves maintaining the thermal stratification at different height levels of the storage tank, which minimizes the process of balancing the hot water. The aim of the experiments was to demonstrate the thermal energy layering in the 1050 l water storage accumulator in 1 hour depending on the different water flow rates from 250 to 1000 l/h from the heat source.

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Smusz, Robert, Joanna Wilk, and Paweł Bałon. "Numerical Simulations of Temperature and Velocity Fields in the Storage Tank with the Three-Coil Heat Exchanger." Advances in Manufacturing Science and Technology 44, no. 3 (June 4, 2020): 74–79. http://dx.doi.org/10.2478/amst-2019-0015.

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AbstractThis article presents the results of the numerical investigation of the thermal stratification in the hot water storage tank. The exchanger consists of three tube coils that are immersed in the storage tank of hot water. Two coils—lower and upper—are designed to warm the water in the tank using the water as a heating medium. Another coil—uses the refrigerant for the waste heat transfer. The temperature stratification device is mounted in the thermal storage tank. The device’s task is to improve the thermal stratification level of heated water. The performed numerical simulations allowed us to obtain the temperature and velocity fields in the storage tank under the conditions of the work of coils filled with water. Calculations were made in the case of the use of the stratification device under the operating conditions of the upper and lower coils with water.

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Sabeti, R., S. Jamali, and H. H. Jamali. "Simulation of Thermal Stratification and Salinity Using the Ce-Qual-W2 Model (Case Study: Mamloo Dam)." Engineering, Technology & Applied Science Research 7, no. 3 (June 12, 2017): 1664–69. http://dx.doi.org/10.48084/etasr.1062.

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Due to the shortage of fresh water, the quality of stored water in reservoirs has become increasingly important. Thermal regime and salinity are factors that affect the quality of water reservoirs. These two parameters were studied in Mamloo Dam in Tehran province. This dam has recently started to be uses as a source of drinking water for Tehran and thus its water quality is of increased importance. In this regard, the hydrodynamic model for 2014 to 2015 was built and calibrated by the CE-QUAL-W2 model and the model was used to simulate the thermal regime and salinity up to 2020. Two main scenarios were studied in this period, the continuation of the current situation or a 2.5% increase in water requirements and 5% decrease in discharge. The results show that the reservoir will experience thermal stratification in the summer and vertical mixing in the winter. Dased on these results Mamloo reservoir is in branch of warm Monomictic lake. Also results showed that thermal stratification and ssalinity stratification dominates simultaneity. Besides this issue with 2.5% increase in water requirements and 5% decrease in discharge, duration of summer thermal stratification will decrease although intensity of thermal stratification will increase.

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Wang, Hao, Nan Ding, and Wenyuan Zhang. "An Adaptive Non-Uniform Vertical Stratification Method for Troposphere Water Vapor Tomography." Remote Sensing 13, no. 19 (September 24, 2021): 3818. http://dx.doi.org/10.3390/rs13193818.

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Global Navigation Satellite System (GNSS) water vapor tomography provides a four-dimensional (4-D) distribution of water vapor in the atmosphere for weather monitoring. It has developed into a widely used technique in numerical weather prediction (NWP). Vertical stratification is essential in discretizing the tomographic region. Traditional discretization methods divide the tomographic area into regular voxels with an equal height interval, which ignores the dynamic exponential distribution of water vapor. In recent years, non-uniform stratification methods have been widely validated by tomographic experiments. However, such experiments have not proposed a specific calculation method for stratification thickness. Therefore, in this paper, we introduced an adaptive non-uniform stratification method that follows the exponential distribution of water vapor in the tomographic region and presented the process of iterative calculation to acquire the optimal stratification interval. The proposed approach was applied based on the exponential decreasing trend in water vapor with increasing altitude. Moreover, it could adaptively calculate the interval of stratification height according to water vapor content. The tomographic experiments were performed using Global Positioning System (GPS) data from 19 ground-based stations in the Hong Kong Satellite Positioning Reference Station Network (SatRef) from 1 to 31 August 2019. The results indicated that, compared to the traditional stratification method, the root mean square error derived from the proposed approach was reduced by 0.26 g/m3. Additionally, severe weather can negatively affect the accuracy of the tomographic results. The results also showed that the accuracy of the tomographic results was reduced with increasing altitude. Moreover, the performance of the tomographic water vapor fields below 3000 m was improved by the proposed approach.

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Ji Hee, Kim, Kim Kyung Ok, Lee Ae Kyung, Roh Mark S, and Suh Jeung Keun. "Germination of Corylopsis seeds evaluated by X-ray imaging and cold stratification." Horticultural Science 44, No. 2 (May 11, 2017): 105–11. http://dx.doi.org/10.17221/194/2015-hortsci.

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Effects of immersing seeds in water and X-ray imagining on germination of Corylopsis seed were investigated. Seeds that sank or floated were collected after immersing in water for 5 min, 4 h or 16 h, and germinated with or without 5°C cold stratification (CS). In C. coreana and C. sinensis var. calvescens, 52% and 89%, respectively, of seeds that sank immediately developed embryos and cotyledons germinated. Germination of C. sinensis var. calvescens seeds that sank after 16 h increased to 45% after the first CS treatment, as compared to 12% without CS. Immersing seeds in water for 16 h to collect full and mostly full seeds is recommended. X-ray imaging coupled with immersion is effective technique to select viable seeds. Dormancy could be partially released by immersing seeds in water for 16 h; however, germination was improved after CS.

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Jin, Juxiang, Scott A. Wells, Defu Liu, Guolu Yang, Senlin Zhu, Jun Ma, and Zhengjian Yang. "Effects of water level fluctuation on thermal stratification in a typical tributary bay of Three Gorges Reservoir, China." PeerJ 7 (May 15, 2019): e6925. http://dx.doi.org/10.7717/peerj.6925.

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Xiangxi River is a typical tributary of Three Gorges Reservoir (TGR) in China. Based on field observations in 2010, thermal stratification was significant in most months of the year. Through field data analysis and numerical simulations, the seasonal and spatial variation of thermal stratification as related to the impact of the operation of TGR were investigated. Thermal stratification was most pronounced from April to September in the Xiangxi River tributary. Air temperature (AT) and water level (WL) were the two dominant variables impacting thermal stratification. AT affected the surface water temperature promoting the formation of thermal stratification, and high WLs in TGR deepened the thermocline depth and thermocline bottom depth. These results provide a preliminary description of the seasonal variation and spatial distribution of thermal stratification, which is important for better understanding how thermal stratification affects algae blooms in Xiangxi River.

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Pham, Hieu T., and Sutanu Sarkar. "Ageostrophic Secondary Circulation at a Submesoscale Front and the Formation of Gravity Currents." Journal of Physical Oceanography 48, no. 10 (October 2018): 2507–29. http://dx.doi.org/10.1175/jpo-d-17-0271.1.

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AbstractLarge-eddy simulations are performed to investigate the development of the ageostrophic secondary circulation (ASC) and associated transport in a submesoscale front. Based on the observations in the northern Bay of Bengal and in the Pacific cold tongue, the model front has a large cross-front density difference that is partially compensated with lateral temperature and salinity gradients. Vertical stratification is varied in different cases to explore its effect on the ASC. The evolution of the ASC differs with stratification. When the front is unstratified, shear instabilities, which develop from the geostrophic shear, cause the front to slump. Cold water from the light side propagates across the front on the surface, while warm water from the dense side spreads in the opposite direction at depth. In cases with stratifications, a shear layer driven by the cross-front pressure gradient forms at the surface to initiate the ASC. Shear-driven turbulence associated with the enhanced shear in the layer causes the front to slump, and the development of the ASC onward is similar to the unstratified case. Irrespective of the initial stratification of the strong fronts simulated here, the surface layer evolves into a gravity current. The ASC is composed of the surface gravity current and a countercurrent that are separated by a middle layer with enhanced stratification and a thermal inversion. Turbulent dissipation is enhanced at the nose of the gravity current and in a sheared region somewhat behind the leading edge of the countercurrent. The gravity current propagates at a speed proportional to the buoyancy difference across the front in the case with no stratification.

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Xu, Jiaxing, Minghan Luo, Dema Ba, Gongde Wu, Ligang Xu, and Taeseop Jeong. "Numerical Simulation Study on the Layered Phenomenon of Lakes and Reservoirs Destroyed by a Forced Circulation Device." Journal of Marine Science and Engineering 10, no. 5 (May 13, 2022): 665. http://dx.doi.org/10.3390/jmse10050665.

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Thermal stratification is a common phenomenon in lakes and reservoirs. It has a significant influence on water quality dynamics. The destruction of the thermal stratification of lakes and reservoirs can affect the water environment, improve the water quality and the water environment quality and prevent the occurrence of eutrophication. In this study, computational fluid dynamics (CFD) combined with a Eulerian two-phase flow model is used to predict the damage caused by an airlift device to the thermal stratification phenomenon of lake water. The results show that the two devices with different sizes can contribute to a certain exchange of kinetic and thermal energy, affecting the liquid velocity and temperature in the lake water under the condition of different gas velocities. Furthermore, the degree of damage to the thermal stratification phenomenon of lake reservoir is small. However, with the same gas velocity, the device with a guide plate can have a greater impact on the liquid velocity and temperature in the lake water. Further prediction results show that the airlift installed with a guide plate can affect the heat transfer of liquid in the lake and reservoir better and destroy the thermal stratification phenomenon effectively. The quantitative results of model prediction can provide an effective basis for future field scale-up experiments.

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Trinuruk, Piyatida, Papangkorn Jenyongsak, and Somchai Wongwises. "Comparative Study of Inlet Structure and Obstacle Plate Designs Affecting the Temperature Stratification Characteristics." Energies 15, no. 6 (March 10, 2022): 2032. http://dx.doi.org/10.3390/en15062032.

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Temperature stratification between outgoing hot water and incoming cold water is a key factor in diminishing energy loss during the discharging process and maximizing the useful hot water delivered from the tank or enhancing the thermal efficiency of the heating device during the heating process. In this study, the inlet structure and the obstacle plate were designed and modified based on two main factors, the reduction of inlet water velocity and the stipulation of the water recirculation area, to develop temperature stratification through the computational fluid dynamics method. The simulation model’s accuracy was validated against the experimental results. The results showed that using the equalizer as an inlet pipe’s auxiliary device was the best approach for decreasing the inlet water velocity, which resulted in enhancing temperature stratification. The discharging efficiency improved from 77.3% for the original tank model to 86.1% for the tank with equalizer IV model, which meant an additional 45 L of useful hot water was gained from the good temperature stratification storage tank. The installation of the obstacle plate for controlling the turbulence zone could not improve temperature stratification significantly, which resulted in an increase in discharging efficiency by only 4% more than the original tank model.

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Toller, Simone, Beatrice M. S. Giambastiani, Nicolas Greggio, Marco Antonellini, Ivo Vasumini, and Enrico Dinelli. "Assessment of Seasonal Changes in Water Chemistry of the Ridracoli Water Reservoir (Italy): Implications for Water Management." Water 12, no. 2 (February 20, 2020): 581. http://dx.doi.org/10.3390/w12020581.

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The Ridracoli artificial basin is the main water reservoir of the Emilia-Romagna region (Northeast Italy). The reservoir was made by construction of a dam on the Bidente River in 1982. It is used as the main drinking water supply of the region and for hydropower production. The physical and chemical parameterseters (temperature, pH, electrical conductivity, and dissolved oxygen) of shallow water are continuously monitored whereas vertical depth profiles of water chemical data (major anions and cations, as well as heavy metals) are available on a bimonthly base. The dataset used in this research is related to the years 2015 and 2016. Data show that the reservoir is affected by an alternation of water stratification and mixing processes due to seasonal change in water temperature, density, and the reservoir water level. In late summer and winter months, the water column is stratified with anoxic conditions at the bottom. During the spring, on the other hand, when storage is at its maximum, water recirculation and mixing occur. The reservoir is characterized by a dynamic system in which precipitation, dissolution, and adsorption processes at the bottom affect water quality along the reservoir depth column. The temperature stratification and anoxic conditions at the reservoir bottom influence the concentration and mobility of some heavy metals (i.e., Fe and Mn) and, consequently, the quality of water that reaches the treatment and purification plant. This study is relevant for water resource management of the reservoir. Assessing the seasonal changes in water quality along the reservoir water column depth is fundamental to plan water treatment operations and optimize their costs. The reservoir assessment allows one to identify countermeasures to avoid or overcome the high concentrations of heavy metals and the stratification problem (i.e., artificial mixing of the water column, new water intakes at different depths operating at different times of the year, blowers, etc.).

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Yao, Yuan, Zhenghua Gu, Yun Li, Hao Ding, and Tinghui Wang. "Intelligent Simulation of Water Temperature Stratification in the Reservoir." International Journal of Environmental Research and Public Health 19, no. 20 (October 20, 2022): 13588. http://dx.doi.org/10.3390/ijerph192013588.

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In order to fully make use of limited water resources, humans have built many water conservancy projects. The projects produce many economic benefits, but they also change the natural environment. For example, the phenomenon of water temperature stratification often occurs in deep reservoirs. Thus, effective ways are needed to predict the water temperature stratification in a reservoir to control its discharge water temperature. Empirical formula methods have low computational accuracy if few factors are considered. Mathematical model methods rely on large amounts of accurate hydrological data and cost long calculation times. The purpose of the research was to simulate water temperature stratification in a reservoir by constructing an intelligent simulation model (ISM-RWTS) with five inputs and one output, determined on the basis of artificial neural networks (ANN). A 3D numerical model (3DNM) was also constructed to provide training samples for the ISM-RWTS and be used to test its simulation effect. The ISM-RWTS was applied to the Tankeng Reservoir, located in the Zhejiang province of China, and performed well, with an average error of 0.72 °C. Additionally, the Intelligent Computation Model of Reservoir Water Temperature Stratification (ICM-RWTS) was also discussed in this paper. The results indicated that the intelligent method was a powerful tool to estimate the water temperature stratification in a deep reservoir. Finally, it was concluded that the advantages of the intelligent method lay in its simplicity of use, its lower demand for hydrological data, its well generalized performance, and its flexibility for considering different input and output parameters.

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Koohestani, Kamran, Yury Stepanyants, and Mohammad Nabi Allahdadi. "Analysis of Internal Solitary Waves in the Gulf of Oman and Sources Responsible for Their Generation." Water 15, no. 4 (February 13, 2023): 746. http://dx.doi.org/10.3390/w15040746.

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A combination of multiple data sources has been used to study the characteristics of internal solitary waves (ISWs) in the Gulf of Oman (GoO). Water column stratification in the Gulf has been examined using field observations and World Ocean Atlas 2018 datasets. The spatiotemporal distribution of ISWs has been obtained from satellite images obtained by means of Synthetic Aperture Radar (SAR) and optical sensors taken from 2018 to 2020. The mechanisms of ISW generation in the GoO have been studied using the data revealed from different available sources. The results show that there are annually two major typical stratifications in the GoO throughout the year, strong stratification in May through September and weak stratification during other months. Dispersion relations corresponding to these types of stratification have been obtained with acceptable accuracy for both deep and shallow regions. The spatiotemporal distribution of ISWs demonstrates that the western and southern regions of the GoO are the hotspots for generation of ISWs in this basin. Several mechanisms of ISW generation in the GoO are discussed including tide, eddies, lee waves, and atmospheric perturbation; the latter one is, apparently, responsible for the appearance of large-amplitude ISWs.

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33

Eddleman, L. E., and J. T. Romo. "Spotted knapweed germination response to stratification, temperature, and water stress." Canadian Journal of Botany 66, no. 4 (April 1, 1988): 653–57. http://dx.doi.org/10.1139/b88-092.

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Spotted knapweed (Centaurea maculosa Lam.) is an introduced noxious weed on grasslands in the northwestern United States and adjoining Canadian provinces. This research examined germination responses of spotted knapweed to stratification, temperature, and water stress under controlled conditions. Immediately after harvest, germination was sharply reduced by sub- and supra-optimal temperatures and water stress; as seeds aged, germination increased at sub- and supra-optimal temperatures. Total germination was enhanced and days to 50% of final germination (D50) was reduced by cool–moist stratification. Under water stress, germination of unstratified seeds was limited at suboptimal temperatures, but seeds pretreated with cool–moist stratification germinated more rapidly and to a higher percentage over a broader range of temperatures and osmotic potentials.

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34

Zhang, Jin, Li Cheng, Yajun Wang, and Chenjuan Jiang. "The Impact of Tidal Straining and Advection on the Stratification in a Partially Mixed Estuary." Water 15, no. 2 (January 13, 2023): 339. http://dx.doi.org/10.3390/w15020339.

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Stratification and mixing of the water column is an important dynamic process in the estuary, which plays a significant role in the estuarine circulation, mass transport and energy exchange. Based on the multi-station synchronous observation data from 26 February to 6 March in 2011 during dry season in the North Channel of the Changjiang Estuary, the Richardson number, the Simpson number and the potential energy anomaly of water were calculated to analyze the tidal variation of the mixing and stratification processes. The roles of the depth-mean straining, longitudinal advection, non-mean straining and tidal stirring in the processes of mixing and stratification of the water column were analyzed by calculating the contribution terms of the time-derivative of potential energy anomaly. The results show that the mixing and stratification of the water column in the North Channel have significant spatiotemporal variation. Stability of the stratification gradually decreases from neap tide to spring tide. In the reaches of salt wedge migration, permanent stratification develops during neap and mean tide, with stability increasing on the flood and decreasing on the ebb, which is dominated by longitudinal advection. During spring tide, periodic stratification develops, with development of stratification on the flood and its breakdown on the ebb, which is dominated by longitudinal advection and tidal stirring. In the main reaches of saltwater intrusion, permanent stratification develops during neap tide, with stability increasing on the ebb and decreasing on the flood, which is dominated by depth-mean tidal straining. During mean and spring tide, periodic stratification occurs, with development of stratification on the ebb and its breakdown on the flood, which is controlled by depth-mean tidal straining and assisted by tidal stirring. In the North Channel, tidal advection is the main stratifying agent in the salt wedge migration reaches, and tidal straining is the main stratifying agent in the main reaches of saltwater intrusion.

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35

Almeida, Manuel C., Pedro S. Coelho, António C. Rodrigues, Paulo A. Diogo, Rita Maurício, Rita M. Cardoso, and Pedro M. Soares. "Thermal stratification of Portuguese reservoirs: potential impact of extreme climate scenarios." Journal of Water and Climate Change 6, no. 3 (April 8, 2015): 544–60. http://dx.doi.org/10.2166/wcc.2015.071.

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Changes in water temperature and stratification dynamics can have a significant effect on hydrodynamics and water quality in reservoirs. Therefore, to assess future climate impacts, projections of three regional climate models for Europe, under the IPCC A1B emission scenario (2081–2100), were used with the CE-QUAL-W2 water quality model to evaluate changes in the thermal regime of 24 Portuguese reservoirs, representing different geographic regions, morphologies, volumes and hydrological regimes. Simulation results were compared with reference simulations for the period 1989–2008 and changes in water temperature and thermal stratification characteristics were evaluated. Future inflow scenarios were estimated from precipitation-runoff non-linear correlations and outflows were estimated considering present water uses, including hydropower, water supply and irrigation. Results suggest a significant increment in the mean water temperature of the reservoirs for the entire water volume and at water surface of 2.3 and 2.5 °C, respectively, associated with a runoff reduction of approximately 23%. Overall, variations in annual stratification patterns are characterized by changes in the mean annual length of stratification anomaly that ranged from −21 to +39 days. Results also show the influence of depth and volume over the reservoir's temperature anomaly, highlighting the importance of future water uses and operation rule curves optimization for reservoirs.

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36

Smith, D. R., C. Huang, and R. L. Haney. "Phosphorus fertilization, soil stratification, and potential water quality impacts." Journal of Soil and Water Conservation 72, no. 5 (2017): 417–24. http://dx.doi.org/10.2489/jswc.72.5.417.

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37

Pak, D. K. "A FORAMINIFERAL ISOTOPIC PROXY FOR UPPER WATER MASS STRATIFICATION." Journal of Foraminiferal Research 32, no. 3 (July 1, 2002): 319–27. http://dx.doi.org/10.2113/32.3.319.

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38

Brownridge, James D. "Solar-induced Thermal Activity and Stratification in Pond Water." Journal of Water Resource and Hydraulic Engineering 4, no. 1 (January 15, 2015): 68–75. http://dx.doi.org/10.5963/jwrhe0401005.

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39

Boehrer, Bertram, Peter Herzsprung, Martin Schultze, and Frank J. Millero. "Calculating density of water in geochemical lake stratification models." Limnology and Oceanography: Methods 8, no. 11 (November 2010): 567–74. http://dx.doi.org/10.4319/lom.2010.8.0567.

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40

Mulitza, Stefan, Anke Dürkoop, Walter Hale, Gerold Wefer, and Hans Stefan Niebler. "Planktonic foraminifera as recorders of past surface-water stratification." Geology 25, no. 4 (1997): 335. http://dx.doi.org/10.1130/0091-7613(1997)025<0335:pfarop>2.3.co;2.

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41

Novotny, Eric V., and Heinz G. Stefan. "Road Salt Impact on Lake Stratification and Water Quality." Journal of Hydraulic Engineering 138, no. 12 (December 2012): 1069–80. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0000590.

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42

Cummins, Patrick F. "The deep water stratification of ocean general circulation models." Atmosphere-Ocean 29, no. 3 (September 1991): 563–75. http://dx.doi.org/10.1080/07055900.1991.9649417.

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43

Osman, Kahar, Syed Muhammad Nasrul Al Khaireed, Mohd Kamal Ariffin, and Mohd Yusoff Senawi. "Dynamic modeling of stratification for chilled water storage tank." Energy Conversion and Management 49, no. 11 (November 2008): 3270–73. http://dx.doi.org/10.1016/j.enconman.2007.09.035.

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44

Andersen, E., S. Furbo, M. Hampel, W. Heidemann, and H. Müller-Steinhagen. "Investigations on stratification devices for hot water heat stores." International Journal of Energy Research 32, no. 3 (2008): 255–63. http://dx.doi.org/10.1002/er.1345.

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45

Li, Yang, Ting-lin Huang, Zi-zhen Zhou, Sheng-hai Long, and Hai-han Zhang. "Effects of reservoir operation and climate change on thermal stratification of a canyon-shaped reservoir, in northwest China." Water Supply 18, no. 2 (June 24, 2017): 418–29. http://dx.doi.org/10.2166/ws.2017.068.

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Abstract Thermal stratification has a significant impact on water quality and ecological characteristics. Reservoir operation and climate change have an effect on the thermal regime. The Jinpen Reservoir is a large canyon-shaped reservoir located in Shaanxi Province with a strong thermal stratification, which resulted in an anaerobic condition in the hypolimnion. We used a hydrodynamic module based on MIKE 3 to simulate the thermal structure of the Jinpen Reservoir and study the relationship between the thermal regime, reservoir operation and climate change. Based on the daily hydrological and climatic data from 2004 to 2013, we made 13 hypothetical simulated conditions that included extreme change of inflow volume, water level, air temperature, radiation, inflow water temperature and selective withdrawal to explore the effect of different factors on the thermal regime. The results showed that the period of thermal stratification, water column stability and surface water temperature were influenced by these factors. With the increase of air temperature, the simulation results indicated a stronger thermal stratification and a higher surface water temperature, which could cause water safety problems. Deep withdrawal could decrease water column stability and prompt water column mixing early, which could be used by reservoir managers to optimize the reservoir operation.

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46

Ohashi, Yoshihiko, Shigeru Aoki, Yoshimasa Matsumura, Shin Sugiyama, Naoya Kanna, and Daiki Sakakibara. "Vertical distribution of water mass properties under the influence of subglacial discharge in Bowdoin Fjord, northwestern Greenland." Ocean Science 16, no. 3 (May 4, 2020): 545–64. http://dx.doi.org/10.5194/os-16-545-2020.

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Abstract. Subglacial discharge has significant impacts on water circulation, material transport, and biological productivity in proglacial fjords of Greenland. To help clarify the fjord water properties and the effect of subglacial discharge, we investigated the properties of vertical water mass profiles of Bowdoin Fjord in northwestern Greenland based on summer hydrographic observations, including turbidity, in 2014 and 2016. We estimated the fraction of subglacial discharge from the observational data and interpreted the observed differences in subglacial plume behavior between two summer seasons with the numerical model results. At a depth of 15–40 m, where the most turbid water was observed, the maximum subglacial discharge fractions near the ice front were estimated to be ∼6 % in 2014 and ∼4 % in 2016. The higher discharge fraction in 2014 was likely due to stronger stratification, as suggested by the numerical experiments performed with different initial stratifications. Turbidity near the surface was higher in 2016 than in 2014, suggesting a stronger influence of turbid subglacial discharge. The higher turbidity in 2016 could primarily be attributed to a greater amount of subglacial discharge, as inferred from the numerical experiments forced by different amounts of discharge. This study suggests that both fjord stratification and the amount of discharge are important factors in controlling the vertical distribution of freshwater outflow.

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47

Loewen, Mark R., Josef Daniel Ackerman, and Paul F. Hamblin. "Environmental implications of stratification and turbulent mixing in a shallow lake basin." Canadian Journal of Fisheries and Aquatic Sciences 64, no. 1 (January 1, 2007): 43–57. http://dx.doi.org/10.1139/f06-165.

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The extent of stratification and vertical mixing in the water column (7–11 m deep) was investigated over an offshore reef in the western basin of Lake Erie. Measurements reveal that the vertical transport of oxygen and heat is controlled by the complex interaction of several physical mechanisms. Generally, when the wind speed (W) was >7 m·s–1 and the air was cooler than the water (Tair< Tw), the water column was well mixed due to turbulent mixing. However, when W < 7 m·s–1 (~65% of the summer), turbulence was too weak to overcome the stratification and mix the water column. An analysis of 25 years of meteorological data revealed that a period of 4.5 ± 1.9 days of calm, warm weather (W < 7 m·s–1 and Tair > Tw) occurs every year. Results indicate that there is strong probability of hypoxia due to stratification (i.e., when diffusivities < 10–6 m2·s–1) and sediment oxygen demand (i.e., 0.1–1.0 g·m–2·day–1) during these periods. The environmental implications of stratification to water quality and its effects on benthic organisms, such as the burrowing mayfly (Hexagenia spp.), require further considerations in large temperate lakes and basins that are sufficiently shallow that there is no permanent seasonal stratification.

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48

Bormans, Myriam, Holger Maier, Michael Burch, and Peter Baker. "Temperature stratification in the lower River Murray, Australia: implication for cyanobacterial bloom development." Marine and Freshwater Research 48, no. 7 (1997): 647. http://dx.doi.org/10.1071/mf97058.

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The relationship between temperature stratification of the water column, river discharge and meteorological forcing was examined for the lower River Murray by using a combination of field measurements and a simple mixing criterion. Wind was found to be the dominant variable affecting the degree of temperature stratification under low flow conditions typical of summer. The results of a three-month intensive study were used in conjunction with six years of historical data to determine the stratification potential of the lower River Murray and its implication for water quality and cyanobacterial bloom development. The physical characteristics and therefore stratification behaviour of the water column in the river section studied are not conducive to sustained blooms at any time of the year because of a combination of strong winds and sufficiently high river discharges.

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Liu, Chunxi, Jijian Lian, and Haijun Wang. "Experimental Analysis of Temperature-Control Curtain Regulating Outflow Temperature in a Thermal-Stratified Reservoir." International Journal of Environmental Research and Public Health 19, no. 15 (August 2, 2022): 9472. http://dx.doi.org/10.3390/ijerph19159472.

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The construction of reservoir dams has changed the environment and natural properties of the river course, and deep-water reservoirs present an obvious phenomenon of thermal stratification. Low-temperature outflow water in spring and summer will have a negative impact on the downstream ecological environment. Therefore, it is necessary to take selective withdrawal measures to regulate low-temperature outflow water. The temperature-control curtain project has the advantages of low cost, convenient construction and wide application. Based on the topographic data, a laboratory test model for regulating outflow temperature by a temperature-control curtain is established. A high-power electric heating system is adopted to form a nonlinear thermal stratification. The accuracy of the test data is verified by the prototype observed water temperature. The main parameters affecting the outflow temperature are investigated, including thermal stratification, flow height above the temperature-control curtain, water level, and discharge flow. The results show the following: firstly, the outflow temperature mainly depends on the thermal stratification, decreases with the increase of water level, and increases with the increase of discharge flow; secondly, the effect of a temperature-control curtain on improving the outflow temperature is directly related to the thermal stratification in different months, and the improvement effect is better in spring and summer; finally, the improvement effect increases with the decrease of flow height above the temperature-control curtain, increases with the increase of water level, and decreases with the increase of discharge flow.

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50

Han, Wang Kook, Jin Man Kim, Tae Hun Lim, Hae Eun Song, and Young Chull Ahn. "Temperature stratification using an air-cooled heat pump system with a mixing valve." Advances in Mechanical Engineering 12, no. 12 (December 2020): 168781402098465. http://dx.doi.org/10.1177/1687814020984653.

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The main factor determining the performance of a thermal storage method is the temperature stratification in the storage tank. At the ideal stratification, the energy efficiency of the storage tank is extremely high. However, when the heat pump is applied, the stratification is disrupted by heat exchange between the layers of the heat medium, and consequent convection in the tank. Therefore, this study analyzed the influence of stratification-related design factors in the water-piping facility area outside a tank heated by a heat pump. In particular, it assessed the thermal stratification and energy efficiency in the storage tank installed with a mixing valve. In the system using the mixing valve, hot water of constant temperature was supplied to the top of the storage tank, reducing the mixing effect of the hot and cold waters; consequently, the stratification index was maximized at 0.42. Comparing the times at which the temperature of the uppermost part reached 70°C in the systems with and without the mixing valve (30 and 75 min, respectively), we find that the mixing valve reduced the time of obtaining effectively hot water by approximately 60%.

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Journal articles on the topic 'Water stratification'

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