On March 8 and 9, 1992, a thermal‐infrared‐multispectral scanner (TIMS) was flown over two military ordnance disposal facilities at the Edgewood Area of Aberdeen Proving Ground, Maryland. The data, collected by the National Aeronautics and Space Administration, in cooperation with the U.S. Army and the U.S. Geological Survey, were used to locate ground‐water discharge zones in surface water. The images from the flight show areas where ground‐water discharge is concentrated, as well as areas of diffuse discharge. Concentrated discharge is predominant in isolated or nearly isolated ponds and creeks in the study area. Diffuse discharge is found near parts of the shoreline where the study area meets the surrounding estuaries of the Chesapeake Bay and the Gunpowder River. The average temperature for surface water, measured directly in the field, and the average temperature, calculated from atmospherically corrected TIMS images, was 10.6° C (Celsius) at the first of two sites. Potentiometric surface maps of both field sites show discharge toward the nontidal marshes, the estuaries which surround the field sites, and creeks which drain into the estuaries. The average measured temperature of ground water at both sites was 10.7° C. The calculated temperature from the TIMS imagery at both sites where ground‐water discharge is concentrated within a surface‐water body is 10.4° C. In the estuaries which surround the field sites, field measurements of temperature were made resulting in an average temperature of 9.0° C. The average calculated TIMS temperature from the estuaries was 9.3° C. Along the shoreline at the first site and within 40 to 80 meters of the western and southern shores of the second site, water was 1° to 2° C warmer than water more than 80 meters away. This pattern of warmer water grading to cooler water in an offshore direction could result from diffuse ground‐water discharge. Tonal differences in the TIMS imagery could indicate changes in surface‐water temperatures. These tonal differences can be interpreted to delineate the location and extent of ground‐water discharge to bodies of surface water.

To determine the rate of cover-collapse sinkhole formation in Christian County, Kentucky, we used large scale aerial photographs taken nearly twenty years apart. The negatives were enlarged and printed to 1:3,000 scale and examined for collapses. The photographs constrained the time period within which the collapse could have occurred, and the large scale of the prints provided a means to identify, locate, and field-verify the cover collapses. All features noted on the photographs were checked in the field. Sinkholes seen on the later photographs, but not the earlier ones, were recorded. The rate of formation calculated was 0.2 cover-collapse km 22 yr 21 .

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Most studies of carbonate bedrock weathering have focused on the dissolved inorganic carbon (DIC) flux while dismissing particulate inorganic carbon (PIC) as insignificant. However, under certain flow conditions PIC flux may be an important term in carbonate weathering. In this study, the total inorganic carbon (TIC) flux was calculated in a fluviokarst basin. Water samples and in situ data loggers were used to determine suspended sediment concentration and water chemistry. The mass of PIC within suspended sediments was quantified by cation/anion analysis of dual filtered/unfiltered samples. The flux of bed load material was calculated via stream power calculations. The analysis of recorded storm events indicated that PIC flux is moderate but can be significant during peak storm discharges. A small storm with a 0.87-month return period produced a PIC flux of 14 g s−1 and a DIC flux of 150 g s−1 at 1.4 m3 s−1 discharge. The largest storm had a return period of 7.7 months, a peak discharge of 4.6 m3 s−1, and peak PIC flux of 620 g s−1 compared to a peak DIC flux of 350 g s−1. During storm events, bed load was the most significant component of the total PIC flux, exceeding the suspended load flux by an order of magnitude. When calculated on an annual basis, the data show that PIC contributes about 10 percent to total inorganic carbon removal.

This study shows that the cosmogenic radionuclide beryllium‐7 can be used to track sediment movement through caves. The activities of beryllium‐7 and cesium‐137 were measured in two different karst settings at both surface and subsurface sites before and after storm runoff events. At one site, 7Be‐enriched sediment was detected up to 1.5 km along a stream conduit after a moderate storm event; however, the activity of 137Cs was too variable to show a meaningful pattern. The percentages of surface sediment that was found ranged from 0 to 52% along the entire 3 km cave stream and from 33 to 52% along the upper 1.5 km. At the other site, as much as 96% of the sediment initially discharged at the spring during a storm event was fresh surface material that had traveled into and through the cave stream. Moreover, during the 4 day runoff event, approximately 23% of the total suspended sediment flux was estimated to originate from surface erosion with 78% being reworked sediment from within the cave. The data in this study show that cosmogenic radionuclides with multiyear half‐lives are too long‐lived to track sediment origins in the caves; whereas, 7Be with a 53.2 day half‐life, can be used to track movement of sediment along cave streams.