[A-HW33] Prediction of water and sediment dynamics from small to large scales

[AHW33-10] Understanding catchment processes and scale effect on catchment flows

*Chris Leong¹, Yoshiyuki Yokoo¹ (1.Fukushima University)

Keywords:process-based, catchment size, flow duration curves, dominant processes, predictions in ungauged basins

The shapes of flow duration curves of catchments are unique to their respective catchments and embedded within these shapes are important hydrological process occurring information within the catchment. This work seeks a process-based understanding of the flow duration curve of three different types of catchment flows, perennial, intermittent and ephemeral and its relational dependencies on scaling issues, in particular is the catchment size. First, the number of dominant processes within the catchments were identified and a tank model was built according to this number of dominant processes. Next, process-based equations that calculated return flows from in and out of the components of the tank model were derived from an initially used linear storage estimation method. The results showed that a combination of lower aridity, humid climate and large catchment size had more dominant processes occurring in it, in contrast to a catchment with a higher arid climate and small catchment size which has fewer dominant processes occurring in it. These combinations that affect the dominating occurring processes cause perennial and ephemeral flows within the catchments respectively. The results in this study contribute to the hydrological initiatives of process-based understanding of catchments in contribution towards predictions in ungauged basins.