Submitted to: Journal of Environmental Modeling and Software
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/26/2002
Publication Date: 6/26/2002
Citation: Interpretive Summary: A wide range of water runoff, soil erosion and water quality issues in watersheds are now commonly investigated by use of computer programs called hydrologic models. Basic watershed information for the hydrologic models is traditionally derived manually from maps, aerial photographs, and field surveys. These techniques are tedious, costly, time consuming and subject to considerable operator interpretation. This paper presents an automated derivation of the watershed information. The procedure is based on a computer evaluation of a large number of elevation values that represent the watershed topography. Derived data include drainage boundaries and drainage areas of catchments within the watershed, channel length and slope, and the arrangement of the channels that form the drainage network. The resulting watershed information is then used by the hydrologic model to estimate the watershed runoff. As a result of this automated procedure, the watershed information that may have taken a skilled operator several weeks to develop using the traditional manual approach can now be accomplished in a matter of only minutes. An example application to a 70 sq. mi. watershed in Canada shows that the watershed runoff values for both the manual and the automated approach are very similar. In addition, the automated procedure allows the rapid investigation of a number of alternative representations of the watershed, which is helpful to identify the most suitable watershed representation for runoff calculations.
Technical Abstract: This paper discusses the application of digital terrain analysis modeling techniques to the parameterization of a semi-distributed hydrologic model. Most current techniques for deriving physiographic parameters in watershed analyses, including those using commercial geographic information systems (GIS), are tedious, costly, and time consuming. The demands of these techniques result in them usually being limited in practical applications to deriving parameters at only one level of detail or for only one set of sub-basins. This paper presents a computerized interface (SLURPAZ) that was developed to combine the output of an established digital terrain analysis model (TOPAZ) with digital land cover data to derive all the necessary physiographic parameters required as input by a widely used semi-distributed hydrological model (SLURP). This interface makes it possible to derive physiographic parameters rapidly and accurately, at several different levels of detail and for varying numbers of sub-basins. This paper describes the methods by which the SLURPAZ interface integrates land cover data with the topographic parameters derived by TOPAZ from a digital elevation model (DEM). It also presents an example application of the interface to an intermediate-sized alpine basin in Yukon, Canada. Hydrological model outputs obtained using the computerized interface are compared with those obtained using manual techniques.