Normal faulting and its role in the drainage divide migration in the Karıncalıdağ region, Menderes Massif, Western Türkiye

Drainage divide migration refers to the shifting boundaries between adjacent drainage basins over time, driven by processes such as tectonic uplift, differential erosion, stream capture, and lithological variations. This phenomenon has a significant impact on water flow patterns and basin extents, serving as an indicator of the landscape's response to active tectonic forces. One of the key drivers of divide migration is asymmetric uplift, which causes divides to shift from areas of lower uplift to regions experiencing higher uplift. Drainage divides are inherently dynamic, evolving over time as drainage networks develop and adjust to changing conditions. This study focuses on the migration of the main drainage divide along Karıncalıdağ, located between Bozdoğan and Karacasu. It employs geomorphic analyses using metrics such as the normalized steepness index (ksn), Chi (χ), and Gilbert metrics. The main divide is categorized into four segments (D1–D4), with the Karacasu Fault, situated along the mountain's north-eastern boundary, identified as the primary factor influencing divide dynamics. Secondary factors include the relatively low elevation of Karıncalıdağ, uniform lithology, and consistent rainfall patterns across the region. The results indicate that the main divide is currently stable, suggesting a balance between uplift and erosion. However, higher χ values in the D4 segment suggest that future erosion may dominate, potentially causing the divide to migrate toward the Bozdoğan Basin. These findings highlight the dynamic nature of drainage divides and the complex interplay of tectonic, erosional, and lithological processes that shape their evolution. Continued monitoring and advanced geomorphic analysis are essential for understanding the long-term stability of the divide and its response to future tectonic activity and erosional modifications.