As outlined in the preceding sections, CatchmentSIM incorporates a range of algorithms for digital terrain analysis and hydrologic analysis. These include algorithms for the interpolation of a raster DEM from contour and watercourse alignment data. The algorithms provide significant advances on current implementations of profile based DEM interpolation algorithms by utilising variable vector search ray frequency and flat cross-section discounting. The watercourse integration algorithm enables non 3D information to be incorporated into the DEM and ensures that valley areas are accurately defined within the DEM, which effectively preserves the observed stream network in the project.
Flat and pit pixels may then be removed from the DEM using an iterative filling algorithm or an advanced breaching algorithm. The breaching algorithm is based on the work of Jones (2002) but has been updated and improved to incorporate a number of modifications including elevation prioritised processing and 3 additional parameters designed to optimise the speed and accuracy of the algorithm.
CatchmentSIM's flow mapping algorithm is based on the research of Lea (1992). However, important modifications have been made to increase speed and ensure flow paths can no longer travel towards, or cross into, pixels of higher elevation. The modified version of the flow mapping algorithm accurately models flow paths on hill-slopes and within channels. Furthermore, since multiple flow direction algorithms switch to the D8 method in stream channels (using the maximum cross grading area parameter), it is the only algorithm that allows for generation of stream networks that are not based on the D8 method.
CatchmentSIM's flow mapping algorithm has flow-on improvements in many subsequent parts of an analysis including automated catchment break-up and hydrologic analysis. Due to the algorithm's accurate calculation of flow path length statistics, a number of new charting and analysis functions may be introduced which are not available using other flow mapping algorithms.
The urban tools incorporated within CatchmentSIM allow for the software to be applied in regions where the DEM is not entirely representative of the local flow constraints which is commonly the case in urban areas. These tools enable processing of urbanised catchments that would otherwise be difficult, if not impossible, for application by such techniques.
The CSTalk macro language provides a simple method for coupling of CatchmentSIM with any hydrologic or hydraulic computer model. Furthermore, the language provides for the automatic generation of customised report formats improving quality control and eliminating data transfer errors.
The following Program Reference section includes context-sensitive help for every form and menu option within CatchmentSIM. Although this section can be navigated in the usual fashion, the easiest method for obtaining context-sensitive help is to press F1 in CatchmentSIM when you need help on the control, form or menu item that has the current focus.