## 5 Discussion
### Relative Active Tectonics in the Manzai Ranges  
The sensitivity of river/stream channels to deformation is a common indicator of active tectonic modification in a Fold-Thrust belt [52]. In a tectonically active region, the drainage pattern is continuously modified in response to changes in the landscape development as a result of fold growth. The drainage network in the Manzai Ranges was modified following the evolution of the frontal foreland thrusts (<1 Ma) [20; 60] and the present day stream network traverses through the axial surface of the folded and faulted Kundi and Khirgi anticlines. The interplay between the tectonic and climatic conditions control the formation of wind and water gaps in the growing fold [61]. No wind gaps were identified in the study area; however, the water gaps in the form of deflected streams at the folding tip indicate that the uplift along an anticline has not exceeded the erosive power of a stream (Figure 3a,d). A strong deflection is observed in the Shahkar and Qulpe Narai River along the imbricate thrust of the Khirgi Fault (Figure 6). The drainage network flowing southeast shows a deflection to the southwest, following the fault trace and then regaining its initial path geometry. The fault scarp becomes prominent at a few stratigraphic sections along the 38 km-long studied segment of the Khirgi Thrust; however, most of the fault trace is buried by quaternary alluvial deposits. These geomorphic parameters, such as drainage asymmetry and the active incision of alluvial surfaces, show anticlinal growth. Additionally, medium-high Ksn values are distributed along the major rivers in the study area indicating recent tectonic uplift [62]. The spatial correlation of high Ksn values with the low concavity of normalized river profiles and the topographic breaks confirm active tectonic uplift and deformation (Figure 10). The longitudinal river profile shows prominent topographic breaks as knickpoints in upstream, midstream and downstream segments (Figure 9). The upstream segment represents the hanging wall of the Khirgi Thrust, the midstream segment is the footwall covered with alluvial deposits, and the downstream segment is the Manzai anticline. The development of knickpoints is influenced by lithological contrast (soft and hard rocks), tectonic uplift or faulting, and the climatic conditions which are responsible for variations in the base-level [63]. The mapped stratigraphic units with the help of Sentinel-2 data show that the rivers/streams in the Manzai foreland region flow over the uniform lithology from upstream to downstream and show different locations and number of knickpoints (Figure 10). In addition, the knickpoints were developed at various elevations (448-921 m) away from the coast with no evidence of quaternary base-level fluctuations. We refined our knickpoints' selection by choosing their association with high Ksn and maximum concavity. Although topographic breaks were present in the eastern end of the Kundi anticline with low Ksn values and may indicate low tectonic uplift. Hence, we conclude tectonic origin as the main controlling factor for a topographic break in our study area. The convexity of the downstream river profiles flowing across the Manzai anticline indicates warping or uplifting along the Manzai Fault (Figure 9). The anticlinal growth associated with the Manzai anticline deforms the quaternary alluvial fan, along with deep entrenching, which is obvious from the channel incision and convex river profile (Figure 6). Tectonic uplift causes changes in the landscape dynamics and an increase in the channel gradient that ultimately leads to an increase in the erosive power of streams and hence more erosion. The quantitative characterization of the drainage evolution and landscape development in the Manzai Ranges was analyzed using river incision styles and the associated mountain fronts.