2.1 Index of sediment connectivity - HydrogeomorphologyTools/SedInConnect_2.3 GitHub Wiki

IC is derived following the approach of Borselli et al. (2008), who defined the Index of Connectivity as:

Eq. 1

where Dup and Ddn are the upslope and downslope components of connectivity (Fig. 1), respectively. IC is defined in the range of [-∞, +∞], with connectivity increasing for larger IC values.

Figure 1. Connectivity index upslope and downslope components (modified after Borselli et al., 2008).

The upslope component Dup is the potential for downward routing of the sediment produced upslope and is estimated as follows:

Eq. 2

where W is the average weighting factor of the upslope contributing area (see later), is the average slope gradient of the upslope contributing area (m/m) and A is the upslope contributing area (m^2). The downslope component Ddn takes into account the flow path length that a particle has to travel to arrive to the nearest target or sink. Therefore, Ddn can be expressed as:

Eq. 3

where di is the length of the flow path along the ith cell according to the steepest downslope direction (m), Wi and Si are the weighting factor and the slope gradient of the ith cell, respectively. It is worth noting that di can assume two values: cell size (l) in the case of cardinal direction and l√2 in the case of diagonal direction.