The D-Infinity Upslope Dependence tool quantifies the amount each grid cell in the domain contributes to a destination set of grid cells. D-Infinity flow directions proportion flow from each grid cell between multiple downslope grid cells. Following this flow field downslope the amount of flow originating at each grid cell that reaches the destination zone is defined. Upslope influence is evaluated using a downslope recursion, examining grid cells downslope from each grid cell, so that the map produced identifies the area upslope where flow through the destination zone originates, or the area it depends on, for its flow.
The figures below illustrate the amount each source point in the domain x (blue) contributes to the destination point or zone y (red). If the indicator weighted contributing area function is denoted I(y; x) giving the weighted contribution using a unit value (1) from specific grid cells y to grid cells x, then the upslope dependence is: D(x; y) = I(y; x).
This is useful for example to track where flow or a flow related substance or contaminant that enters a destination area may come from.
processing.runalg('taudem:dinfinityupslopedependence', -ang, -dg, -dep)