Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Elci, SebnemPublisher: search.filters.publisher.IAHR-Int Assoc Hydro-Environment Engineering Research

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  • Conference Object
    Renewable Energy Powered Artificial Mixing of the Reservoirs
    (IAHR-Int Assoc Hydro-Environment Engineering Research, 2023) Hazar, Oguz; Elci, Sebnem
    Reservoirs are essential and critical infrastructures and require proper management practices to improve water quality. Thermal stratification observed in the reservoirs impairs the water quality affecting the algae population and the solubility of heavy metals from sediment particles. Artificial mixing methods are widely used to improve water quality in thermally stratified eutrophic lakes and reservoirs. Air diffuser systems, water pumps, and water jets are commonly applied for aeration and mixing purposes. Although these methods proved to be effective in the literature, aeration and pumping equipment consume a great amount of electricity and require complementary infrastructures and facilities resulting in high costs. The presented study focuses on aeration of the water column powered by renewable energy. A Savonius turbine is implemented to an artificial mixing setup tested in the laboratory. The shaft of the turbine is directly connected to the pump so that the motion is transferred to the pump shaft eliminating the need for the production/storage of the electricity. The effectiveness of the wind turbine on destratification of the water column is investigated based on various wind conditions. In the experiments, static and dynamic torque values are monitored using a modified design of a rope brake dynamometer composed of a highly precise torque sensor, pulleys, and, a platform for connecting this torque measurement system to the wind turbine. The system is further evaluated for its destratification efficiency of the water column through the experiments.
  • Conference Object
    Factors Influencing the Cyanobacterial Dominance in Lakes: Analysis of Lakes in Central Germany
    (IAHR-Int Assoc Hydro-Environment Engineering Research, 2023) Elci, Sebnem; Rinke, Karsten
    This study aimed to identify the key factors influencing the phytoplankton development in twenty- eight lakes located in Central Germany (state of Sachsen-Anhalt). A multivariate analysis of biological (phytoplankton), physicochemical, morphological, and hydrometeorological variables of the lakes collected between 2005 and 2021 is presented here. This analysis is the first approach for this dataset to summarize the statistics and to explore trends and patterns of evolution from a multivariate perspective to improve understanding of the conditions that favor the emergence of different phytoplankton classes and taxons. Correlation analysis of the data showed that both, the biovolume of the phytoplankton and chlorophyll-a were positively correlated with, total nitrogen and phosphorus, and negatively correlated to the depth to epilimnion, residence time and conductivity. The thresholds for total nitrogen, phosphorus and average depths are investigated for cyanobacterial genera of 'Aphanizomenon', 'Anabaena', 'Microcystis' and 'Planktothrix'. Higher chlorophyll-a concentrations (>100 mu g/l) are observed when TN>2 mg/l, P>0.1 mg/l and the average depth was less than 1 m. These thresholds are also valid for higher biovolume values (>5 cm(3)/m(3)) of these cyanobacterial taxons observed in all lakes. The nonlinear equations proposed for chlorophyll-a and biovolume of the phytoplankton derived by the genetic algorithm greatly improved the goodness of fit with respect to the linear models. When all data is considered R2 values are calculated as 68% for chlorophyll-a concentrations and 55% for the biovolume suggesting that these models can be applied for future studies.
  • Conference Object
    Citation - Scopus: 1
    Morphological Analysis of Büyük Menderes River Over the Years Using Satellite Imagery
    (IAHR-Int Assoc Hydro-Environment Engineering Research, 2023) Bor, Asli; Hazar, Oguz; Elci, Sebnem
    Both bank erosion and sediment deposition on the inner margins are important watershed management problems for streams. Bank erosion not only causes the loss of agricultural lands, but also leads to the narrowing of the cross sections of the streams with the accumulation of sediment in the interior, resulting in floods, damage to the cultivated areas, reduction in dam reservoir lifespan and thus, serious damage to a country's economy. In this study, the morphological analysis of the B. Menderes River, which is one of the most important rivers of Turkey and a residential and intensive agriculture region, for the thirty-year period between 1990-2020 is made via utilization of QGIS for the analysis of Landsat satellite images. This study is thought to be a preliminary study to quantify the morphological changes in B.Menderes River and is expected to be a basis for linking these changes to the changes in the hydrological regime in the basin. During this analysis, the shoreline of the main river, approximately 570 km long, was divided into 10 segments and the sinuosity index values, which are fold parameters, were calculated for each segment. According to the study, it is found that the curvature of the meanders of the B. Menderes River varies between 1.5 and 2.5 in most places.