A physically based watershed partitioning method

Abstract A new contour-based watershed partitioning method, relying on tracking flow lines moving from upslope to downslope, is presented. The model works by using only contour data and consists of three principal steps: 1) Ideal Drainage Network tracking; 2) hillslope and channel elements building; and 3) actual contour-based element network construction. It automatically detects and manages sinks, peaks and saddles and calculates element attributes taking into account the non-planar shape of the elements. Watershed, subwatershed and draining area at any point can be automatically detected by using network elements interconnectivity. It is also possible to determine the Actual Drainage Network. The model is able to manage point data set trough interpolation, according with specific procedures. Also grid datasets can be used as input, the model is in fact provided with an overlapping algorithm for matching grid datasets to elements. Comparisons with an existing contour-based element network construction method show a better and more physically based description of the element network particularly useful for hydrological and mass movements' analyses.