Environmental Engineering / Çevre Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4321
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Article Citation - WoS: 11Citation - Scopus: 13A Systematic Assessment of Flooding Potential in a Semi-Arid Watershed Using Grace Gravity Estimates and Large-Scale Hydrological Modeling(Taylor & Francis, 2022) Khorrami, Behnam; Fıstıkoğlu, Okan; Gündüz, OrhanThe emergence of the Gravity Recovery And Climate Experiment (GRACE) paved the way for remote tracking of hydrological water cycle components at large scales. With the main motivation of evaluating the feasibility of the coarse resolution GRACE data for small-scale analysis, the GRACE data and large-scale hydrological models were utilized in an integrated manner to monitor the variations of the flood potential index (FPI) over the Western Anatolian Basin (WAB). The results show an ascending trend for monthly and annual FPI over the WAB. The results also suggest that the monthly FPI in 2015, 2003, 2009, and 2016 was the highest, from which the highest potentiality of flood appertains to 2015/07 with an FPI of 0.92. The lowest and highest annual FPI is 0.26 (in 2007) and 0.76 (in 2015), respectively. The validation of the results indicates that variations of FPI coincide with that of the flood incidents, stream discharge, Standardized Precipitation Index (SPI), and the simulated flood risk. The findings accentuate the high feasibility of the GRACE JPL Mascons for better surveillance of floods over local scale areas. Highlights The coarse resolution GRACE JPL mascon functions very well in tracing the spatio-temporal characteristics of flood incidents over local scales. There is an ascending trend in the variations of flood potential over the Western Anatolia Basin (WAB). The WAB has experienced its lowest and highest possibility of flooding in 2007 and 2015 with an average FPI of 0.26 and 0.76, respectively. The variations of the flood potential index (FPI) coincides with that of the reported flood incidents, stream discharge, Standardized Precipitation Index (SPI), and the simulated flood risk.Article Citation - WoS: 36Citation - Scopus: 38Detection and Analysis of Drought Over Turkey With Remote Sensing and Model-Based Drought Indices(Taylor & Francis, 2022) Khorrami, Behnam; Gündüz, OrhanUnder the severe impacts of climate change, drought has become one of the most undesirable and complex natural phenomena with critical consequences for the environment, economy and society. The orthodox drought monitoring approaches use observations of meteorological stations, which are typically restricted in time and space. Remote sensing, conversely, provides continuous global coverage of a variety of hydro-meteorological variables that are influential in drought, and data extracted from remote sensing and modeling missions are now considered more practical and alluring for researchers. In this study, we applied a combination of field data, remotely sensed data and modeled data to detect and quantitatively analyze drought phenomena. To achieve this objective, we utilized Terrestrial Water Storage Anomalies (TWSA) estimations from GRACE mission, Normalized Difference Vegetation Index (NDVI) from MODIS mission, Surface Runoff (R) and Evapotranspiration from ERA5 reanalysis datasets and Soil Moisture (SM) from GLDAS data model to evaluate their feasibility in detecting recent droughts over Turkey. We validated the accuracy of several remote sensing-based indices (GRACE Drought Severity Index, Water Storage Deficit Index [WSDI], Soil Moisture Index, Standardized Runoff Index and NDVI) with the traditional indices (SPI and SPEI) calculated from in situ observations of precipitation. The results revealed that the GRACE-based WSDI gave the best performance with high correlations with the SPI index both temporally and spatially over Turkey. We also found that monthly and annual time series of WSDI agreed well with the SPI index with correlations of 0.69 and 0.73, respectively. The results of drought analysis also indicated that WSDI could be used as a proxy to standard meteorological drought indices over Turkey as it performed well to detect and characterize the recent droughts of Turkey based on its comparisons to SPI results.Article Citation - WoS: 4Citation - Scopus: 5Radiological Modeling of the Impacts of the Chernobyl Nuclear Power Plant Accident on Turkey and Southwest Asia(Elsevier, 2022) Bilgiç, Efem; Gündüz, OrhanMany studies investigated the impacts of the Chernobyl Nuclear Power Plant accident on Europe. However, majority of these have spatially excluded the highly populated southeast region of Chernobyl, including countries such as Turkey, Armenia, Georgia and Iran. In this study, a comprehensive environmental and radiological analysis were conducted particularly for this region. For this purpose, atmospheric dispersion and ground deposition of radionuclides were estimated using a Lagrangian particle dispersion model, FLEXPART. Totally, six simulations were conducted and model results were validated with measurements from Europe and Turkey. Furthermore, total effective dose equivalent (TEDE) values were estimated for adults and infants using the most current dose conversion factors of ICRP. Highest deposition of 137Cs were found in around Eastern Black Sea areas (10–40 kBq/m2). Similar values were found in some locations of Armenia and Azerbaijan under some scenarios, but country averages of 137Cs deposition were lower than 10 kBq/m2 for both countries. No significant depositions were found in southwest Iran, but relatively higher depositions (2–10 kBq/m2) of 137Cs were estimated along the Turkish border. Although there were slightly higher values in northern areas of Syria, Iraq, Lebanon and Cyprus, 137Cs depositions were mostly less than 2 kBq/m2. The 1-year TEDE value was calculated less than 1 mSv throughout the model domain except for some regions of eastern Black Sea. Highest values in lifetime dose values were calculated along the Black Sea coasts of Turkey and Georgia. Overall, infants were affected more from ionizing radiation compared to adults in this region.