American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 689648 bytes)    Cited by

WATER RESOURCES RESEARCH, VOL. 40, W06303, doi:10.1029/2004WR003069, 2004

A comparison of geographical information systems–based algorithms for computing the TOPMODEL topographic index

Feifei Pan

Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA


Christa D. Peters-Lidard

Hydrological Sciences Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA


Michael J. Sale

Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA


Anthony W. King

Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA


Abstract

The performance of six geographical information systems (GIS)-based topographic index algorithms is evaluated by computing root-mean-square errors of the computed and the theoretical topographic indices of three idealized hillslopes: planar, convergent, and divergent. In addition to these three idealized cases, two divergent hillslopes with varying slopes, i.e., concave (slopes decrease from top to bottom) and convex (slopes increase from top to bottom) are also tested. The six GIS-based topographic index algorithms are combinations of flow direction and slope algorithms: i.e., single flow direction (SFD), biflow direction (BFD), and multiple flow direction (MFD) plus methods that determine slope values in flat areas, e.g., W-M method [ Wolock and McCabe, 1995 ] and tracking flow direction (TFD) method. Two combinations of horizontal resolution and vertical resolution of the idealized terrain data are used to evaluate those methods. Among those algorithms the MFD algorithm is the most accurate followed by the BFD algorithm and the SFD algorithm. As the vertical resolution increases, the errors in the computed topographic index for all algorithms decrease. We found that the orientation of the contour lines of planar hillslopes significantly influences the SFD's computed topographic index. If the contour lines are not parallel to one of eight possible flow directions, the errors in the SFD's computed topographic index are significant. If mean slope is small, TFD becomes more accurate because slope values in flat areas are better estimated.

Received 2 February 2004; accepted 20 April 2004; published 24 June 2004.

Keywords: single flow direction algorithm; biflow direction algorithm; multiple flow direction algorithm; GIS; TOPMODEL; topographic index.

Index Terms: 1899 Hydrology: General or miscellaneous; 1824 Hydrology: Geomorphology (1625); 1832 Hydrology: Groundwater transport.

Read Full Article (file size: 689648 bytes)    Cited by

Citation: Pan, F., C. D. Peters-Lidard, M. J. Sale, and A. W. King (2004), A comparison of geographical information systems–based algorithms for computing the TOPMODEL topographic index, Water Resour. Res., 40, W06303, doi:10.1029/2004WR003069.