2.2.2 Contributing area - HydrogeomorphologyTools/SedInConnect_2.3 GitHub Wiki

The tool uses the multiple flow D-infinity approach (Tarboton 1997) to calculate contributing area, instead of the single-flow direction algorithm (O’Callaghan and Mark 1984) applied in the original model. The advantages of D-infinity over the methods that restrict flow to eight possible directions introducing grid bias (i.e. single-flow direction method) or proportioned flow according to slope introducing unrealistic over-dispersion (i.e. multiple flow direction method) are well known (Tarolli and Dalla Fontana 2009; Hengl and Reuter 2009). In order to correctly model sediment fluxes in mountain catchments, it is fundamental to capture the real flow paths especially on hillslopes where divergent flow predominates. The choice of a reliable algorithm modeling divergent flow is thus reckoned necessary. Another reason that leads to the choice of the D-infinity approach is related to the cell size of HR-DTMs. If the cell size is smaller than the width of the channels in the study area, the use of the single-flow algorithm to derive flow accumulation would limit high-drainage areas (i.e. the channel network) to sequences of single cells, thus underestimating channel widths. In contrast, the D-infinity algorithm better approximates channel width by partitioning flow over the entire cross section. Therefore, the D-infinity algorithm produces a more representative pattern of sediment connectivity through the basins.