MODELING THE HUMAN IMPACT ON DRAINAGE BASIN EROSION, DEPOSITION AND SEDIMENT YIELD

Humans have had a double impact on how rivers alter drainage basins – with sediment yields and patterns of erosion and deposition changing due to land use changes (e.g deforestation and agricultural practices) and through changing weather and storm patterns.

Numerical modeling, using Landscape Evolution Models (LEMs) that can represent the hydrological, slope and fluvial processes within a drainage basin, provide us a tool to explore how the Anthropocene has altered river systems – and may continue to do so through climate change. This presentation covers four apsects of important research in this area – showing first how changes in land cover left drainage basins primed and vulnerable to changes in rainfall patterns. Second, by using rainfall generators driven by climate models we can show how subtle changes in future rainfall patterns can lead to significant increases in drainage basin erosion, deposition and sediment yields. Third, we can show how local changes in land use can lead to major changes in erosion and deposition patterns both up- and downstream from the disturbance. Finally, we show how sensitive drainage basins are to intensities and patterns of rainfall.

We argue that these advances mean we are at the juncture where we can use high resolution forecasts of future rainfall patterns within probabilistic modeling frameworks to generate meaningful predictions of how landscapes will alter in the future.