ABSTRACT
In hydrology and erosion mechanics, the use of distributed models is becoming more commonplace. Instead of correlative models that use large-scale measurements of catchment characteristics, spatially distributed data are used by models that attempt to represent the interaction of large numbers of small-scale physical processes (Abbot et al. 1986, Beven et al. 1987). A component of all such models is a procedure to predict the route taken by water or sediment as it flows from upland sources toward the catchment outlet. Presented here is one such routing algorithm and a demonstration of its use in determining the locations of principal streams and their drainage areas within a river basin. It was developed as part of a larger task to model the erosion processes within a river basin for use in conservation planning and the prediction of reservoir sedimentation. It was found necessary to design a routing algorithm that could accurately predict
drainage paths for the construction of sediment delivery ratios and that also could predict the location of subwatersheds to enable local calibration of erosion estimates to be made. (The term “watershed” is used throughout this chapter following the British usage, to indicate the line dividing one catchment (drainage basin) from another.) Existing routing algorithms were found to be insufficiently accurate for both these tasks and especially so in complex terrain.
