2004 RICHARD H. JAHNS LECTURE: ENGINEERING GEOLOGY MAPPING IN THE INFORMATION TECHNOLOGY AGE

Observation remains the foundation of engineering geology mapping, but many aspects of observation are being supplemented and even revolutionized by information technology (IT). Data acquisition is being accomplished with the aid of pen-based computers, digital cameras, and global positioning system (GPS) receivers. Quantitative geophysical and geochemical field methods are being used to produce quantitative measures that can be contoured and/or combined with other forms of observations to construct useful derivative maps. Aerial and space-based spatial data provide base maps or targets for subsequent field observations. Geographic information system (GIS) and computer-aided drafting and design (CADD) software are being used to manipulate and display geospatial data, sometimes during field data collection. Numerical analysis of observational data, including calculated grids derived from vector data, is being used to produce useful derivative products. Challenges for engineering geology practitioners pertain to accuracy of field data; structure of database fields; uniformity of symbols, lines, patterns, and colors; and consistency of derived geospatial map products. Engineering geology maps produced with GIS tools have the potential to mislead even sophisticated users for two reasons: 1) the strikingly professional appearance of GIS maps implies precision even when uncertainties are specifically noted, and 2) field data can be collected as a series of seemingly independent observations and converted by a GIS technician into a professional-appearing map without the benefit of geologic principles or the repeated application of the multiple working hypothesis. Consequently, professional discipline is needed to effectively apply modern IT to engineering geology mapping. The true power IT has is its analytical capabilities which requires engineering geologic data to be in digital format.

A promising new technology is 3D Laser Scanning. Initially, this technology was applied to preparation of as-built plans of structures, such as refineries. Opportunities also exist for engineering geology and geotechnical field applications, such as orientation and spacing of joints in rock slopes and grain-size distribution of deposits that include particles too large to analyze in the laboratory.