ABSTRACT
The computer age has revolutionized the elds of hydrogeology and environmental engineering. Advanced mapping and numerical modeling software are readily available to modern-day hydrogeologists, complete with user-friendly preprocessing and postprocessing interfaces. The practicing professional is no longer burdened by hard-copy data storage, hand calculation, and hand-mapping, or even numerical method formulation and computer coding. The implications of this transformation are far-reaching. Most importantly, hydrogeological data, which are inherently spatial in nature, can easily be stored and visualized through geographic information systems (GIS). The United States Geological Survey (USGS) denes GIS as “computer system(s) capable of capturing, storing, analyzing, and displaying geographically referenced information; that is, data identied according to location” (USGS 2007). In a sense, GIS and associated software create an environment for the hydrogeologist’s data that is a simulation of the real world in three dimensions: longitude, latitude, and elevation. All data in the eld of hydrogeology possess these three dening dimensional features, which can be accurately represented in GIS. However, the real-world representation offered by GIS is temporally discrete in nature; the data stored and visualized in GIS represent snapshots in time. Whether a GIS map is being used to visualize a water table surface, the structure of a river channel, or land surface elevations in a watershed, the hydrogeologist is depicting a discrete representation of these data. In other words, the hydrogeologist can show the average potentiometric surface of the High Plains Aquifer in 1930, the river channel geometry of the Mississippi River in 2005, or the predevelopment elevation surface of the watershed 100 years ago.
