EXPLORING HYDROGEOLOGICAL ENVIRONMENTS USING THE UNITED STATES GEOLOGICAL SURVEY’S HYDROLOGIC INVESTIGATIONS ATLASES

Groundwater resources in the United States occur in a variety of aquifer types that can range from glacial outwash to fractured bedrock aquifers. The U.S. Geological Survey has summarized the geography, geology and hydrologic characteristics of the major aquifers in the United States in a Ground Water Atlas that is divided into 13 Hydrologic Investigation segments (HA730A – HA730N). The series is written for a general audience and includes summaries of the groundwater-water flow system, general water quality and use of the groundwater withdrawn. It can be used to introduce students to the range of hydrogeological environments and groundwater issues that exist in the United States and can also serve as a reference for consultants. The Atlas is a particularly engaging teaching resource because it contains a plethora of rich data and abundant, high quality color illustrations (maps, graphs and figures). For a nominal fee, an oversize hard copy of each segment can be purchased from the USGS and a free digital online version is available.

In my undergraduate hydrogeology class, each pair of students is assigned an Atlas segment and they prepare a short written summary and power point presentation (~12 slides) that focuses on the unique hydrogeological characteristics and issues for their specific region of the United States. Students learn about the structure of aquifers in volcanic rock, glacial, karst and permafrost regions. They teach their fellow students about groundwater problems that result due to over pumping, subsidence, sinkholes, saltwater intrusion and coal mining. For each segment I specify some key questions that students should answer in their presentation. In the absence of this emphasis, many students were overwhelmed by the amount of material in the Atlas and presentations were too descriptive. The assignment thus also requires synthesis of ideas as well as developing effective communication skills, with a focus on concise description and effective use of visual images. Students are responsible for assignment content as it is included on their exam. The principles that control the presence, movement and chemical quality of groundwater in different climatic, topographic and geologic settings are clearly illustrated and make the Hydrologic Atlases an important reference to teach hydrogeology.