Knowledge-based system for environmental design of stream modifications

A knowledge-based, microcomputer software package was developed for preliminary selection of environmental features for use with streambank protection projects, straightened and enlarged channels, and flood control levees. The system contains a module for each of the three major alteration types: bank protection, levees, and channels. Each module queries the user for information regarding environmental factors to be protected and a description of the project setting, with the internal logic configured to minimize the number of questions asked. System output consists of a list of environmental design features suitable for the specific location and descriptive information. Help screens explain why certain questions are asked, define terms, and suggest responses or sources of information. At the conclusion of a consultation, additional help screens may be displayed that provide a discussion of each recommended feature, a list of existing projects that incorporate the feature, and a bibliography. The streambank protection module screens a master list of 20 methods based on the dominant erosion mechanisms operative at the project site, and the channel module performs a rough channel stability assessment using regime equations. The latest version of the software aids in feature selection, but does not design channel alterations. However, the software interfaces with routines that perform basic hydraulic computations (e.g., composite roughness, normal depth, riprap size) for steady flow in order to allow users to quickly evaluate feasibility of in-channel environmental features. A survey of users indicated that the package has been used by entry-level and experienced professionals to perform a limited range of specialized tasks. Seventy-four percent of the users described the software as a useful instrument for planning and preliminary design.