This study investigates the impact of climate change on the Mudurnu Stream Basin in northwest Türkiye by analyzing climate parameters in the Mediterranean region. Historical data from EC-Earth2, HadGEM2-ES, and MPI-ESM-MR GCMs from the CMIP5 Euro-CORDEX archive were assessed, and future precipitation and temperature data were derived using five statistical bias correction methods for the selected EC-Earth2 model under RCP4.5 and RCP8.5 scenarios. The SWAT model was employed to simulate future runoff amounts for the Mudurnu Stream Basin. The findings reveal notable changes in precipitation and temperature. The annual and seasonal variations of total precipitation and average, maximum, and minimum temperatures for the RCP4.5 and RCP8.5 scenarios in the Sakarya and Mudurnu regions were analyzed and determined. The projections for future river flow indicate a significant increase in precipitation during the rainy seasons. The Mudurnu Stream mainstem will experience an increase in flow of between 70 and 140% under RCP4.5 and between 80 and 160% under RCP8.5. In the Dinsiz Stream tributary, a 32–55% increase is observed for the spring and summer months. In this context, the rainfall and runoff projections required for the estimation of potential drought and flood risks in the near and distant future were calculated.

This study presents a scenario-based, two-dimensional flood modeling approach to assess the potential downstream impacts of a piping-induced dam failure triggered by seismic activity. The case study focuses on the Doğantepe Dam in northwestern Türkiye, located near an active branch of the North Anatolian Fault. Critical deformation zones were previously identified through PLAXIS 2D seismic analyses, which served as the physical basis for a dam break scenario. This scenario was modeled using the HEC-RAS 2D platform, incorporating high-resolution topographic data, reservoir capacity, and spatially varying Manning’s roughness coefficients. The simulation results show that the flood wave reaches downstream settlements within the first 30 min, with water depths exceeding 3.0 m in low-lying areas and flow velocities surpassing 6.0 m/s, reaching up to 7.0 m/s in narrow sections. Inundation extents and hydraulic parameters such as water depth and duration were spatially mapped to assess flood hazards. The study demonstrates that integrating physically based seismic deformation data with hydrodynamic modeling provides a realistic and applicable framework for evaluating flood risks and informing emergency response planning.

This study examines the long-term trends of key meteorological variables within the section of the Euphrates-Tigris Basin located within Türkiye’s national borders. Using data from 18 meteorological stations (1965-2023) and applying methods such as the MMK test, SS, SR, and several homogeneity tests, the analysis identifies notable climatic shifts. The combined use of these methods allows for a more consistent evaluation of both trends and potential structural changes in the time series. Significant decreases in precipitation were detected at three stations, while the remaining stations showed no clear trend. This indicates that precipitation changes are limited and station-specific, reflecting spatial variability within the basin rather than a uniform basin-wide pattern. In contrast, maximum temperatures increased significantly at 77.8% of stations, and minimum temperatures rose at nearly 83%. The widespread increase in temperature across most stations suggests a more consistent warming pattern compared to precipitation. Homogeneity assessments revealed major change points in 1989, 1994, and 1998 for both precipitation and temperature. These years may be associated with variations in atmospheric circulation patterns and regional hydro-climatic influences, including reservoir-related effects. The identification of similar change points by different homogeneity tests supports the consistency of these findings. These results suggest an increasing hydro-meteorological imbalance, likely influenced by rising temperatures and declining or stable precipitation. These changes may have an impact on the hydrological processes within the catchment area and on water-dependent sectors. The findings highlight the urgent need for long-term, adaptive, and integrated water management strategies, supported by basin-specific climate change scenarios.