Drainage divides mark the boundaries between adjacent drainage basins. These divides are not static; they migrate over time in response to changes in the tectonic and climatic gradients, influencing the surface distribution of water, erosion, sediment particles, and ecological niches. To date, field-based estimates of divide migration rates typically rely on measurements of erosion rate differences across divides, mostly using cosmogenic isotopes. However, these rates provide only indirect, time-averaged rates; and are insufficient to detect transient migration dynamics.
In this study, we leverage a unique site in the Shaharut plateau in the southern Negev, where drainage divide migration is associated with a channel whose flow direction was reversed from west to east, towards the cliffs that bound the Arava Valley. A well-preserved sequence of terraces along the channel, maintaining the pre-reversal valley gradient, provides direct evidence for the locations of the divide in the past, and serves as a potentially datable record of paleo-divide positions. Using a combination of relative dating, based on the reg soil chronosequence, and absolute dating using luminescence methods, we reconstruct the divide migration dynamics over the last ~230 ka. Our results reveal intermittent migration at timescales of 10⁴–10⁵ years, with phases of rapid migration with at least twice the average migration rates. These phases correlate with regional proxies for paleoclimate fluctuations, highlighting the potential role of climate change in shaping basin geometry over time. This study underscores the episodic nature of divide migration and provides new insights into the relationships between rates of geomorphic processes and Quaternary climatic changes in the southern Negev.