Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 7Citation - Scopus: 9A Holistic Overview of the Applications of Grace-Observed Terrestrial Water Storage in Hydrology and Climate Science(Springer, 2025) Khorrami, Behnam; Gunduz, OrhanTerrestrial Water Storage (TWS) represents a vital element of the hydrological cycle, with its fluctuations significantly impacting the climate of the Earth and its ecological balance. Since its launch in 2002, the Gravity Recovery and Climate Experiment (GRACE) satellite mission has revolutionized the ability to observe and analyze large-scale mass changes within Earth's system components. This paper offers a comprehensive and current overview of GRACE satellite gravimetry, highlighting its relevance to hydrological and climate-related studies. It outlines the fundamental measurement principles of the GRACE mission, provides an in-depth explanation of GRACE data products (including spherical harmonic and mascon solutions), examines emerging trends in GRACE-based research, and reviews key applications in hydrology and climate science. Additionally, it addresses the major challenges in utilizing GRACE data and explores promising avenues for future research and applications.Article Citation - WoS: 3Citation - Scopus: 3Analysis of Microplastic Flux From the Gediz River To the Aegean Sea: a Modeling Study for Environmental Management(Academic Press Ltd- Elsevier Science Ltd, 2025) Kazanci, Yigithan; Alyuruk, Nefise; Alpergun, Cumana; Kara, Nursena; Baycan, Neval; Gunduz, OrhanIt is critical to determine the abundance of microplastics in terrestrial inland waters, understand their fate and transport mechanisms, and reveal their status in aquatic environments. This study aimed to develop and calibrate a mathematical model to simulate microplastic (MP) pollution in the Gediz River Basin, T & uuml;rkiye, which focused on MP fate and transport under existing conditions and various management scenarios. The baseline scenario revealed that, despite a ninefold difference in flow rates, the midstream and upstream parts of the basin also exhibited significant contamination, with an average concentration of 25 n/L compared to the downstream average of 29 n/L. The model was later simulated to test the effects of various mitigation scenarios including but not limited to reducing MP discharges from wastewater treatment plants (WWTPs) and implementing vegetative barriers in tributaries. Scenario 4, which involves reducing MP concentrations in upstream tributaries with vegetative barriers, achieved the highest average reduction across all segments (32 %) and specifically in the downstream area (47 %). In contrast, Scenario 1, aimed at reducing wastewater discharges from urban and industrial WWTPs through water reclamation, and Scenario 2, which focused on eliminating MP in Organized Industrial Zone (OIZ) discharges by changing industrial inputs, achieved the most effective MP reductions in the upper basin, with reductions of 20 % and 17 %, respectively. Scenario 3, targeting flow reduction and accumulation through constructed wetlands, had minimal impact, with reductions close to 0 % in most areas. These results highlight the need for comprehensive approaches to effectively reduce MP pollution, particularly in managing upstream and tributary sources.Article Citation - WoS: 1Derivation of Soil Hydraulic Properties (SHPS) Using a Physics-Based Inverse Calibration Method and International Soil Moisture Network Database(Elsevier, 2025) Sahin, Onur Gungor; Gunduz, OrhanThis study used extensive soil moisture records to estimate "inverse-calibrated Soil Hydraulic Properties (SHPs)" using a multi-processing technique via high-performance computing clusters. Within this objective, a mass conservative numerical model was developed to solve the one-dimensional Richards Equation incorporating two different soil hydraulic models: the well-known van Genuchten Mualem (VGM) model and the relatively new Fredlund-Xing-Wang (FXW). A multiprocessing version of the Differential Evolution Algorithm (DEA) optimization technique was used for inverse calibration of the soil hydraulic parameters. For FXW, calibration statistics were calculated as means of the KGE' (0.89 f 0.1 and 0.83 f 0.23), R (0.89 f 0.1 and 0.85 f 0.21) and ubRMSE (0.017 f 0.01 and 0.015 f 0.02) for the depths 50 and 100 cm, respectively. For VGM, calibration statistics were found as means of the KGE' (0.87 f 0.11 and 0.78 f 0.22), R (0.90 f 0.08 and 0.86 f 0.17) and ubRMSE (0.019 f 0.01 and 0.017 f 0.01) for the same depths, respectively. The employed methodology had highly promising statistical performance for both FXW and VGM to derive SHPs. A comprehensive validation methodology was used to evaluate the reliability of derived SHPs. Correlation analysis showed that derived SHPs strongly correlated with the soil properties and environmental variables. Further, as a validation procedure, initial investigations were also conducted to explore the spatial transferability of the parameters. Despite the use of basic k-means clustering, the resulting soil hydraulic datasets showed statistical similarity or even improvement to hyper-resolution maps used in the literature. While the simulation model of the methodology has certain assumptions and limitations, this study proves that the ISMN database can be used to derive soil hydraulic properties and transfer these parameters to locations other than the calibration points. This study shows that FXW is a promising hydraulic model for the determination of soil moisture at root zone within the complete moisture range. The methodology can also be readily extended to other established soil moisture monitoring networks and potentially extended versions of "inverse-calibrated SHPs" and trained pedotransfer functions are considered to be valuable tools to estimate soil moisture profiles at the root zone.Article Citation - WoS: 8Citation - Scopus: 9Comprehensive Comparison of Different Gridded Precipitation Products Over Geographic Regions of Türkiye(Spie-soc Photo-optical instrumentation Engineers, 2024) Khorrami, Behnam; Sahin, Onur Gungor; Gunduz, OrhanThe traditionally used rain gauge stations provide the most reliable data on the spatiotemporal distribution of precipitation; however, they are limited in space and time. As an alternative to field observations, the gridded precipitation products (GPPs) offered by remote sensing missions are widely used. On account of the uncertainties associated with the GPPs, they have to be quality-checked for confidence in application over the region of interest. Although accuracy assessment of precipitation data is a common task, there is a gap in the literature regarding a comprehensive assessment of the currently available GPPs. In this study, 14 GPPs were used to investigate their performance in catching the spatio-temporal characteristics of precipitation over geographic regions of T & uuml;rkiye. According to the results, integrated multi-satellite retrievals for Global Precipitation Measurement (IMERG), multi-source weighted-ensemble precipitation (MSWEP), and Tropical Rainfall Measuring Mission (TRMM) show better performance on monthly and annual scales while on the climatology scale, CHELSA, Climate Hazards Group Infrared Precipitation with Station, ERA5, and ERA5-Land also manifest better performance. The mean monthly correlation over Aegean Region (AEG), Marmara Region (MAR), Central Anatolian Region (CAR), Mediterranean Region (MED), Black Sea Region (BSR), East Anatolian Region (EAR), and South East Anatolian Region (SEA) are 0.77, 0.81, 0.77, 0.80, 0.79, 0.77, and 0.77, respectively. The annual assessment suggests that over the MAR, CAR, MED, and SEA, the IMERG mission performs very well. While TRMM showcases its best performance in the AEG, MED, BSR, and EAR, MSWEP performs well in the BSR and SEA Region. Overall, taking the country-average results into account, it can be stated that among the used GPPs, TRMM, MSWEP, and IMERG yield the best results for T & uuml;rkiye as a whole.