RAVINE GROWTH EXPERIMENTS TO UNDERSTAND EFFECTS OF CHANGING HYDROLOGY

Altered overland flow hydrology can impact the rate at which ravines and gullies grow. Using a set of small physical experiments we tested how changing overland flow rates for a fixed volume of water affects ravine morphology and the total volume of sediment excavated from a ravine. We tested ravines in both detachment-limited and transport-limited systems, and found that in both cases the total volume of erosion was independent of the flow rate. Ravines and gullies do not respond like pre-existing channels because channel morphology including channel slope can adjust more quickly in these systems in response to changing flows. The dominant hydrologic alteration that does accelerate ravine growth is the volume of water entering the ravine, where a greater water volume results in greater erosion.