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Abstract

The spatial variability of geomorphic and topographic indicators along the Akşehir Fault in southwestern Türkiye was evaluated using seven representative geomorphic segments (S1–S7). A 12.5 m resolution DEM was used to determine normalized channel steepness ksn, x, knickpoint (KP) distribution, hypsometric integral (HI), and model-based relative uplift derived from linear inversion of river profiles. To provide a consistent basis for comparison among the representative basins, a common reference concavity of θref =0.53 was determined from basin-specific optimal concavity values and applied to the ksn and x analyses. Fault-normal topographic profiles were additionally used to quantify regression-derived topographic throw, local scarp height, and near-fault topographic height difference. The results reveal pronounced along-strike differences in topographic expression. Mean ksn values are highest in S3 (392.29), S4 (370.70), and S1 (360.27), whereas the lowest value occurs in S7 (149.80). The highest number of KPs is recorded in S1 (24), while S6 contains only two. HI ranges from 0.40 in S7 to 0.62 in S4, and mean model-based relative uplift reaches 2.23 mm yr-1 in both S3 and S4 but decreases to 0.89 mm yr-1 in S7. Fault-normal topographic throw ranges from 16.18 m in S7 to 144.87 m in S4, with local scarp height and near-fault topographic height difference showing broadly similar along-strike variations. Notably, S7 has the highest mean x value (2116.31) despite having the lowest ksn, HI, model-based uplift, and fault-normal topographic values. This divergence demonstrates that individual geomorphic indicators do not necessarily reproduce the same spatial pattern. The results show that S3–S4, particularly S4, represent the clearest convergence among channel-, basin-, inversion-, and fault-normal topographic indicators, whereas the contrasting behaviour of x in S7 highlights the need for a multi-metric assessment of tectonic geomorphic expression.