RIDGE MIGRATION MODELING WITH HUMAN ACTIVITIES
In this study, using a numerical landscape evolution model, we illustrated the long-term glacial legacy on the landscape as well as the impact from short-term human activities, such as channel straightening and periodic dredging. With the landscape evolution model, we simulated three scenarios. First, in our control scenario, we allowed a landscape to develop between two fixed outlets from an initial condition that consisted of two downward facing plates containing random perturbations. This landscape represented a natural landscape in static steady state condition. Second, using the results from the first scenario, we extended the channels and fixed them from being eroded or filled. This landscape represented an intensively managed landscape. We found that by extending and maintaining the channel network, it can cause massive ridge migration, river network redistribution, and enlargement of the drainage basin area. Last, using the resulting landscape of the second scenario, we removed the channel fixing constraint and allowed the landscape to evolve. This final landscape represented a landscape that has recovered. In the landscape, river network keeps redistributing, the ridge migrated towards the original position in the natural landscape, but they did not migrated back fully. Comparing the results from our first and last scenario, we were able to see the impact and legacy of the channel modifications. We attribute the legacy to drainage basin reorganization and theorized that humans can have a lasting impact on the landscape even after management has ceased.