HR: 1340h
AN: H43D-0526    [Abstracts]
TI: A New Method for Computing Flow Paths and Contributing Areas Over Both Convergent and Divergent Topography
AU: * Peckham, S D
EM: peckhams@rivix.com
AF: RIVIX, LLC, 1306 Highland Park Dr., Broomfield, CO 80020 United States
AB: Contributing area grids play a central role in spatial hydrologic modeling and are required for landscape evolution models. A variety of algorithms have been introduced over the last twenty years for the grid-based flow routing and computation of watershed contributing area. The first was the well-known D8 method, which permits flow to only one neighborpixel, and while still useful for certain purposes it does a very poor job on divergent hillslopes. Several different multiple flow direction algorithms were proposed in the nineties, including the D-Infinity method which partitions flow between two neighbor pixels using a slope-based rule, and other methods which use slope-based rules to partition flow between more than two neighbors. A difficulty with these slope-based rules is that they are merely intuitive and do not follow from a conservation law or any other physical principle. Another method called DEMON was proposed that allows flow to at most two neighbor pixels but which attempted to avoid arbitrary slope-based partitioning rules. Unfortunately, this algorithm was incomplete and could not handle all of the different scenarios that occur in real DEMs, particularly in the vicinity of drainage divides. As a result, it appears that it has never been used in an operational capacity. The author will introduce a new method that is similar in some respects to the DEMON method but that provides an improved solution to this important problem. This new ``mass flux" method is based on mass conservation and uses quarter-pixels to avoid various ambiguities in the assignment of continuous flow angles near peaks and divides. Results for test surfaces and the complex topography near Mount Sopris, Colorado will be shown to be superior to results from both the D8 and D-Infinity methods.
DE: 1805 Computational hydrology
DE: 1825 Geomorphology: fluvial (1625)
DE: 1850 Overland flow
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: Fall Meeting 2005