WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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COAR Access Rights: search.filters.coarAccessRights.embargoed accessInstitution Author: search.filters.institutionAuthor.Tayfur, Gökmen

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  • Article
    Citation - WoS: 10
    Citation - Scopus: 11
    Experimental Investigation of Sediment Movement as a Result of Homogeneous Earth-Fill Dam Overtopping Break Over a Simplified Urban Area
    (Elsevier, 2023) Taşkaya, Ebru; Bombar, Gökçen; Tayfur, Gökmen
    When an earth-fill dam breaks, dam body sediment and water flow simultaneously move to downstream area causing devastation. Dam break studies in the literature have concentrated mostly on the water flow part while ignoring the sediment movement by designing the dam body as a movable metal gate. This study, however, is the first one experimentally investigating flow and sediment transport due to an earth-fill dam break by constructing the dam body from sediment. Sediment propagation as a result of homogenous earth-fill dam overtopping break was experimentally studied in a laboratory flume of 18.4 m long and 2.0 m wide, and 0.88 m in height in the Hydraulics Laboratory of Izmir Katip Celebi University, Izmir, Turkey. Downstream section right after the dam body was designed as a smooth bed and rough bed. The rough bed, resembling a simplified urban area, was created by using thirteen 10 × 10 × 10 cm sized concrete blocks. The dam body was constructed as homogenous with uniform material having D50 = 0.441 mm. The earth-fill dam body was built using the standard compression methods; each layer of sediment with a thickness of 10 cm was laid in layers, and the body was prepared with a crest width of 10 cm, a transverse base width of 200 cm, a longitudinal base width of 202 cm and height of 60 cm with upstream and downstream slopes of 1:1.6. The water level behind the dam was gradually raised until it overtopped the crest level. A pre-breach was formed at the top of the dam to trigger the break. During each dam break event, water depths were measured by three ULS-40D level meter sensors at different locations, and the final sediment bathymetry map was generated using the ULS-40D Probes at 10 × 10 cm grids. The results showed that, in both smooth and rough downstream bed cases, the dam body eventually collapsed while a great portion of it was carried away by the flood flow. The sediment spreading occurred all over the downstream area, showing significant non-uniform variation in thickness both longitudinally and transversely, especially in the simulated urban area. All the residential areas, while breaking in motion, were submerged under the muddy flow. Some blocks were almost submerged while sediment heights reached half level of some blocks at the end of the experiment. Sediment heights were higher in the urban area.
  • Article
    Citation - WoS: 24
    Citation - Scopus: 27
    Drought Assessment in the Aegean Region of Turkey
    (Springer, 2022) Mersin, Denizhan; Gülmez, Ayşe; Safari, Mir Jafar Sadegh; Vaheddoost, Babak; Tayfur, Gökmen
    Drought indices are commonly used to monitor the duration and severity of droughts. In this regard, the continuously changing climate regardless of its cause or effect pushes the limit of the water deficit through time and space. Izmir is a raising city in Turkey, which owns various water resources including but not limited to seashores, lakes, river streams, and groundwater aquifers. In this study, the long-term precipitation and temperature records from 14 meteorological stations between 1973 and 2020 (for 47 years) are used to investigate the drought characteristics in Buyuk Menderes, Kucuk Menderes, and Gediz basins located in the Aegean region of Turkey. For this, the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI), Percent of Normal (PNI), and the so-called Discrepancy Precipitation Index (DPI) are used with consideration to 1-, 3-, 6-, and 12-month moving averages to investigate the drought patterns. Results showed that the monthly indices depict very similar results for the entire region. However, in the 1980s and 2010s droughts were more severe than the rest of the historical records. When the moving average operator is implemented in the analysis (3-, 6- and 12-month periods), neither SPI nor the SPEI showed the same results at any stations. It is illustrated that the periods of severe and normal drought have occurred in the past, yet the indices that are obtained using average values are generally within the normal limits, but extreme values (extremely arid or extremely wet) occurred occasionally. It is also concluded that although there is a similarity between the implemented indices, the DPI and PNI depict the highest resemblance.