DTM — flow accumulation — D_infinite method

RASTER data (ESRI GRID format), consisting of square cells of 10 m side.Flow accumulation expresses the progressive downstream accumulation of surface run-off water flow (or sub-surface), based on the flow directions provided by the Flow Direction grid based on local topography. In this case the calculation method used is the D-Infinite (Tarboton Dinf, 1997), according to which, unlike other methods such as D8 (see flow_dir_d8), there are infinite possible flow directions, corresponding to any direction within the 360° range. The D-Infinite (Dinf of Tarboton, 1997) is one of the most accredited among the so-called “Flow Tracking” methods. It is able to model not only the accumulation of flow in concave areas but also its dispersion in convex areas. The resulting flow accumulation form is therefore much more “natural” and less angular than that obtained with the D8 method (the only so far the basic content in ArcView/ArcGIS). Moreover, it is not significantly affected by the orientation of the DEM on the territory (if any rotations of the grid cause slight variations in the result). The method, in particular, has the following advantages: 1) returns a much more “natural” figure than the D8 method that forces the “natural continuity” to very restrictive geometric dictates; 2) It manages to model not only the accumulation of the flow but also its dispersion. On the other hand, in the case of surface flows rapidly concentrated in grooves which do not allow the dispersion of water, this method tends to predict even excessive dispersion. Warning: for graphical issues, the numerical value reported for each cell represents the logarithm based on 10 of the draining area (Log10 As). To obtain the actual draining area (As), the numerical value must be elevated as exponent to 10 (As = 10flow_acc_dinf). The unit of measurement is [m].