River capture frequency and magnitudes are regulated by rock erodibility

River captures reroute river networks and generate transient pulses of erosion. Their frequency, size, and spatial distribution are also important drivers of freshwater biodiversity. How tectonic, climatic, or autogenic processes influence the frequency-magnitude and spatial distribution of river capture events are unexplored gaps in landscape evolution research with cross-disciplinary implications. Using numerical modeling of landscape evolution in Landlab, I apply the simplest form of the stream power equation to explore the sensitivity of river captures to the exhumation of rocks with higher resistance to erosion (i.e. a lower erodibility parameter – K). The exhumation of heterogenous rock types in a slowly eroding landscape allows for a positive feedback loop to evolve until some drainage basins completely shrink while others expand. In these conditions, the exhumation of a resistant rock intersects river systems with differing incision capacities, thus creating differential relief across drainage divides and initiating divide migration. The continuous drainage area loss enhances drainage divide migration and increases the probability of river captures. For the same background erosion rate, doubling the areal extent of the exhumed resistant rock nearly triples the probability of large river captures and quadruples the size of the largest river capture of the model run. Lastly, the mode of drainage area exchange (i.e. divide migration or river capture) is itself sensitive to the degree of base-level perturbation caused by the exhumation of a resistant rock. In tectonically inactive settings with low erosion rates, the complex spatial distribution of rocks can thus create spatially variable frequency-magnitude distributions of river captures. These preliminary findings reveal an exciting avenue for exploring the origins and sensitivity of river captures to autogenic controls and its consequences for sedimentary fluxes and biogeography.