Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

Browse

Filters

2020 - 20234

Settings

Author: search.filters.author.Tayfur, GökmenPublisher: search.filters.publisher.01. Izmir Institute of Technology

Search Results

Now showing 1 - 4 of 4
  • Master Thesis
    Determination of Flood Risk Areas and Development of Mitigation Strategies in Kabul River Basin, Afghanistan
    (01. Izmir Institute of Technology, 2023) Barez, Esmayel; Tayfur, Gökmen; Tayfur, Gökmen; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Flooding is a devastating and natural catastrophe to population, environment, and socioeconomic development globally. Floods occur frequently in Afghanistan, especially in Kabul River Basin. Many geographical techniques have been established in recent years to map, predict and model flood risks. This research investigates identification of flood-prone zones and development of mitigation measures in Kabul River Basin. First, in this research, GIS and MCDA methodology was applied to generate flood risk map. Also, AHP method was applied to determine the best weights to be assigned to the factors that influence risk of flooding. A flood risk map of KRB was produced using 10 conditioning criteria; soil, rainfall, lithology, LULC, TWI, NDVI, distance to stream channels, curvature, elevation, and slope. Based on the weighted overlay integration of GIS-AHP technique, KRB was grouped into four flood vulnerability zones; very low, low, high, and very high. Generated flood risk map indicates a good match with the flood risk areas and location of past floods in the basin over recent years. Second, 2D HEC-RAS model and flood frequency analysis were developed for different scenarios to simulate the flow of river and to develope mitigation measures with a 500- year return period in the main river of Kunar and the lower Kabul sub-basin. Manning's n values were used to calibrate HEC-RAS model, and past flood events applied for validation. Flood mitigation strategies, including river restoration, construction of dam, and reservoir improvement were proposed on the Kunar and lower Kabul sub-basin. Keywords: Flood Inundation Map, Hydraulic Modelling, ArcGIS-MCDA.
  • Master Thesis
    Experimental and Numerical Investigation of the Evolution of Piping and Resulting Breach in Earth-Fill Dams
    (01. Izmir Institute of Technology, 2022) Tayfur, Gökmen; Tayfur, Gökmen; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Earth-fill dams have been constructed for decades by compacting natural soil materials near the dam site. Piping is of the most important causes of their failure. In the scope of this thesis, 2 m in length homogenous earth-fill dams were constructed in a rectangular flume in the laboratory of the Izmir University of Economics. The experimental and numerical investigations on a breach by generating piping were realized with different weak zone scenarios. Three experiments were performed by placing a weak layer cross-section 5x5 cm2 at the dam bottom center. One scenario was performed by locating a weak layer of 2x2 cm2, 28 cm above the bottom. Temporal breach areas and the breach-wetted areas are evaluated on scaled screenshots by using Gauss’s area formulation. The Temporal breach discharges were calculated from the continuity equation. Furthermore, finite element analyses on the breaching of homogenous earth-fill dams in different scenarios were performed by comparing the hydraulic gradient with the critical value. In addition to the bottom and middle scenarios, two upper scenarios were also modeled. The water depths were used for each scenario to represent the experimental conditions, and some approaches were made for the weak zones. To simulate the breach mechanism with different loops, a python algorithm was integrated with the Jupyter console. As a result of the simulations, it has been observed that the findings obtained by simulations were in accord with the experimental studies, and the dams were exposed to backward piping starting from downstream towards upstream.
  • Master Thesis
    Drought Assessment in Aydın and İzmir Districts in Turkey
    (01. Izmir Institute of Technology, 2022) Tayfur, Gökmen; Safari, Mir Jafar Sadegh; Tayfur, Gökmen; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Drought indices are widely used in order to track the severity, duration, and frequency of droughts, drought indices are frequently utilized. Turkey's Aegean region, which is expanding, has a range of water resources, including lakes, streams, lakes, and groundwater aquifers. In this study, the drought features in the Büyük Menderes, Küçük Menderes, and Gediz basins in the Aegean area of Turkey are investigated using long-term total precipitation and temperature records from 14 meteorological stations between 1973 and 2020 (47 years). For this, the Standardized Precipitation Index (SPI) and the Standardized Precipitation and Evapotranspiration Index (SPEI), and Discrepancy Precipitation Index (DPI) are used to investigate drought patterns, monthly and over 3-, 6-, and 12-month (annual) periods. The results reveal that the monthly indices show almost the same results for the whole study area, but the different indices differ in the severity of drought. As a common belief, moderate, severe, and extreme drought is observed at the end of the 1980s and around 2020, which is the closest year to the present. In addition, the trend analysis of the annual temperature (daily average) and total precipitation time series data collected from these 14 stations is examined. Sen test, Mann-Kendall test, and Spearman's rho test are used for trend detection. The Pettitt test is used to estimate the magnitude of the slope in the series and the Theil-Sen approach is used to detect the change point of the series. For precipitation, all stations showed a statistically significant increase in trends. In the temperature analysis, on the other hand, all stations show statistically significant increasing trends in daily average temperatures. The amount of precipitation increase determined by the Theil-Sen test is found to be between 4.2 and 7.9 mm/year.
  • Master Thesis
    Modelling Rainfall-Runoff Processes in Kabul River Basin Using Arc Swat Model
    (01. Izmir Institute of Technology, 2020) Tanı, Hamidullah; Tayfur, Gökmen; Tayfur, Gökmen; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    SWAT model is applied to Kabul River Basin (KRB) located in Afghanistan to assess the runoff. KRB is located between latitudes 33 ﾟN and 37 ﾟ N, and longitudes 67 ﾟE and 74 ﾟE, with a drainage area of 72000 km2. This study (1) determines the most sensitive parameters that affect the catchment flow, (2) estimates monthly and daily flows of the basin from the available meteorological stations data, (3) calibrates and validates the simulated and observed flow data for different hydrological stations located in the basin, and (4) determines the total amount of surface runoff and water yield in the basin. SWAT-CUP is applied for the sensitivity analysis. Initially 27 different sensitive parameters effecting the runoff are tasted and 20 most sensitive ones are found. Among these, GWQMN.gw (Treshold depth of water in the shallow aquifer required for return flow to occur ), SMTMP.bsn (Snow melt base temperature), CN2.mgt (SCS runoff curve number II), PLAPS.sub (Precipitation lapse rate), and HRU_SLP.hru (Average slope steepness) are found to be the most sensitive parameters. The predicted flow is calibrated and validated against the measured flow for seven different Hydrological Stations both on a monthly and daily time scales. The performance of the model is checked by applying R2, NSE, and the RSR. Overall, the model's monthly simulation flow is superior to the daily simulation.