Select "Data Preparation->Flow Accumulation-Multiple Flow Direction". Specify the parameters, the algorithms and and the output file.
Output: Flow Accumulation
Flow accumulation is an indirect way of measuring the drainage areas (in units of grid cells).
Method: Multiple Flow Direction
A multiple flow direction algorithm assumes that subsurface flow occurs in all downslope directions from any given point.
DEM file
The DEM data of the area.
Algorithm: MFD-Quinn(Quinn et al., 1991)
MFD with a fixed flow partitioning exponent.
P for MFD-Quinn
The flow partitioning exponent.
Algorithm: MFD-md
The maximum downslope gradient was chosen as the local topographic attribute for the flow-partition scheme. Use a linear function of the maximum downslope gradient as f(e).
where e is tangent b with b being the maximum downslope gradient; f(e) is the flow partition function; pu and pl are the upper and lower bounds of f(e) and are used as the p values representing completely divergent and convergent flows, respectively (see discussion below); and emin and emax are the e values which are associated with pl and pu, respectively. The typical values for the bounds (i.e. pu and pl) are 1.1 and 10.