ABSTRACT The Mitchell Plateau of south-central Indiana is one of the iconic karst landscapes of the United States. The sinkhole-dimpled forests, fields, and farms; the extensive cave systems; and the deep windows into the groundwater system have fostered curiosity, exploration, and publication since the mid-1800s. This paper is designed to complement a field excursion to the classic features of this landscape. Included are literature reviews focused on three karst basins of the Mitchell Plateau: Mill Creek–Mosquito Creek, Bluespring Caverns, and Lost River. Geomorphic, hydrologic, and geochemical data are synthesized in the modern context of our understanding of epigenetic karst. Revealed are three styles of karst basin: (1) small, shallow karst aquifers strongly controlled by meteoric recharge and epikarst percolation; (2) intermediate-size karst aquifers with significant base flow and surface-water–groundwater interaction; and (3) regional aquifer systems with outcrop belt recharge, downdip transport into confinement with long water-rock interaction times, and artesian flow or entrainment of mineralized waters through fractures into springs or surface waters. Quaternary glaciation has greatly influenced the vertical position of base level through river incision and sediment aggradation; conduit development is controlled by proximity to the major rivers and the stratigraphic position of conduits.

Inexpensive geophysical instruments can help meet a need for cost-effective siting of water wells in developing nations. We have developed resistivity, induced polarization, and seismic-refraction instruments that are useful in shallow hydrogeology studies. In addition, our free software can be used to interpret the data recorded by the instruments and produce predictions of subsurface lithologies. This entire suite of geophysical instruments, including a laptop computer for analysis and reports, can be assembled for less than US$600. It is hoped that trained indigenous well drillers and aid workers will use these instruments in support of their efforts to provide water to rural regions of the world that lack safe water.

Rapid industrial development along Thailand’s eastern seaboard has increased pollution and environmental degradation in this densely populated region of the country. A growing problem is illegal disposal of industrial waste in abandoned borrow pits in many locations, especially in the capital Bangkok and its neighboring provinces. Previous work has identified the most likely illegal dumping sites in Chachoengsao Province. The focus of this work was to establish an impact assessment of potential dumping sites using a geographic information system (GIS) in order to create a patrolling and monitoring program for areas at highest risk. The impact assessment is based upon exposure and sensitivity factors of the illegal dumping sites. The exposure factor attempts to quantify the likelihood of illegal dumping; it includes distances from borrow pits to the nearest villages and highways, as well as the areas of the borrow pits. The sensitivity factor assesses the probability of environmental contamination; it includes site topography, ground permeability, aquifer characteristics, and distances to the nearest rivers. GIS was used to compute distances and to overlay other site characteristics. Variables within exposure and sensitivity factors were weighted based upon previous studies and recent expert analysis to compute exposure and sensitivity indices. Maps were then created in GIS for particular exposure and sensitivity factors, and overall impact assessment maps were constructed to indicate zones with low, medium, and high risk. These assessment maps could be adopted by local and regional governmental agencies, as well as local citizens, as part of preventive measures to conserve the local community and environment. Identification of high-risk areas can contribute to the initiation of a monitoring and patrolling program to prevent illegal dumping and preserve environmental and natural resources.