Elizabeth L. White

Karst hydrology: concepts from the Mammoth Cave area

This volume has its roots in the distant past of more than 20 years ago, the International Hydrologic Decade (IHD), 1964-1974. One of the stated goals of the IHD was to promote research into groundwater situations for which the state of knowledge was hopelessly inadequate. One of these problem areas was the hydrology of carbonate terrains. Position papers published early in the IHD emphasized the special problems of karst; carbonate terrains were supposed to receive a substantial amount of attention during the IHD. There were indeed many new contributions from European colleagues but, unfortunately, in the United States the good intentions were not backed up by much in the way of federal funding. Some good and interesting work was published, particularly by the U. S. Geological Survey (USGS), but in the academic community the subject languished. About this same time the Cave Research Foundation (CRF), organized in 1957 to promote the systematic exploration, survey, and scientific study of the great cave systems of Mammoth Cave National Park, was casting about for a broader scope for its research activities. Up until that time, CRF research had been largely restricted to detailed mineralogical and geological investigations within the caves, with the main part of the effort concentrated on exploration and survey. The decision to investigate the hydrology required a certain enlargement of vision because investigators then had to consider the entire karst drainage basin rather than isolated fragments of cave passage.

Quantitative morphology of landforms in carbonate rock basins in the Appalachian Highlands

Karst topography occurs in the Appalachian Highlands where carbonate rocks are exposed. The principal landforms are sinking streams, dolines, and caves. Landform measures were devised for the drainage features and for dolines and applied to 62 small basins between Pennsylvania and Alabama. Conventional measures included a relief factor, drainage factors, and size and shape factors. Karst measures included carbonate rock fractions, measures of doline development, and measures of internal drainage. Factor analysis showed that the 15 measures contained only five independent variables. Various stream length measures are related to the basin area in much the same way as streams in noncarbonate basins showing the fluviokarst character of the Appalachian basins. Sinking stream length, SINKL, relates to the area of the sinking stream catchment, AB, by SINKL = 2.29 AB 0.85 . Doline karst was measured by either the area of internal drainage into dolines, AD, or by the number of dolines, N, per unit area of carbonate rock. These measures are related by AD = 0.0136 N 1.17 . The frequency of occurrence of dolines falls off exponentially with depth independent of rock type or structural setting. Comparison of several measures of karst in relation to rock type shows smallest and fewest dolines in the Ordovician dolomites and an intermediate size and number in the Ordovician limestones. The largest and most numerous dolines occur in the flat-lying Mississippian limestones of the Appalachian Plateau. This result may be an expression of the more sluggish solution kinetics of dolomite compared to calcite.

Sustained flow in small Appalachian watersheds underlain by carbonate rocks

Abstract The groundwater release from storage as it relates to sustained flows in surface streams was investigated for 57 carbonate basins within the Appalachian Highlands. Comparisons were made between sustained flow and the aerial extent of limestone and dolomite rock outcrop within the basins and with the degree of karst development as measured by internal drainage through dolines and sinking streams. Data analyses by direct correlation, by factor analysis and cluster analysis showed that the basins investigated fell into two distinct populations, those with sustained flows comparable to flows observed in non-carbonate basins and those with exceptionally low sustained flows. Basins with a high degree of karst development tended to have low sustained flow because of poor groundwater storage and short residence times in carbonate aquifers with conduit-type permeability. Higher sustained flows were associated with aquifers of the diffuse-flow type.

The influence of urbanization of sinkhole development in central Pennsylvania

The karsted limestone valleys of central Pennsylvania contain two populations of sinkholes. Solution sinkholes occur in the Champlainian limestone units along the margins of the valleys. Solution sinkholes are permanent parts of the landscape and, although a nuisance to construction, do not present other problems. The second population is the suffosional or soil-piping sinkholes These occur on all carbonate rock units including the Beekmantown and Gatesburg dolomites that comprise the two principal carbonate aquifers in the valley. Suffosional sinkholes are the principal land-use hazard.Suffosional sinkholes are transient phonomena. They occur naturally but are exacerbated by runoff modifications that accompany urbanization Suffosional sinkholes are typically 1.5–2.5 m in diameter depending on soil thickness and soil type. The vertical transport of soil to form the void space and soil arch that are the precursors to sinkhole collapse is through solutionally widened fractures and cross-joints and less often through large vertical openings in the bedrock. The limited solution development on the dolomite bedrock combined with soil thickness, seldom greater than 2 m, limits the size of the sinkholes. All aspects of suffosional sinkhole development are shallow processes: transport, piping, void and arch formation, and subsequent collapse take place usually less than 10 m below the land surfaceFactors exacerbating sinkhole development include pavement, street, and roof runoff which accelerates soil transport Such seemingly minor activities as replacing high grass and brush with mowed grass is observed to accelerate sinkhole development. Dewatering of the aquifer is not a major factor in this region

Karst landforms and drainage basin evolution in the Obey River basin, north-central Tennessee, U.S.A.

Abstract An extensive karst landscape is developed on the Mississippian limestones of the dissected western margin of the Cumberland Plateau. Surface streams rising on the clastic rocks of the Cumberland Plateau flow down the escarpment and sink along its slopes at the upper contact of the Bangor Limestone. Some surface channels are continuous across the karst of the lower slopes while others terminate in blind valleys as swallow holes. At the base of the escarpment is an upland surface of doline karst developed in the Monteagle and St. Louis limestones at an elevation of 300–330 m. It consists of 1–5 km 2 shallow blind valleys and uvala-like closed depressions along with many smaller dolines. The internal drainage from the dolines and from the sinking streams is perched on the impermeable Warsaw Formation and emerges as contact springs on the inner gorges of the rivers which have cut deep narrow valleys below the level of the upland surface. Tributary streams to the Wolf, Obey and Roaring rivers (tributaries of the Cumberland River in north-central Tennessee) were analysed by fitting their longitudinal profiles to exponential and logarithmic functions. Linear segments of semilogarithmic plots permitted extrapolating both active streams and underdrained stream channels through the doline karst. The presently active streams extrapolated through the karst emerge at grade with the present-day base-level streams. Underdrained segments of the tributary valleys extrapolate to the upland surface and suggest that dry karst valleys can be interpreted much like river terraces. The development of interior drainage appears to be a much faster process than is the adjustment of the surface drainage.

Correlation of contemporary karst landforms with paleokarst landforms: The problem of scale

The signature of karst terrain is a suite of characteristic landforms: caves, closed depressions, deranged surface drainage, and sculptured bedrock surfaces. Identification of karst, in reality, is accomplished by an ill-defined mix of morphological, sedimentological, and bedrock-geology evidence. The purely morphological signature depends on an examination of population statistics and the scaling laws for the various landforms. Caves are gragments of active and paleo conduit drainage systems. The distribution of cave lengths is a power function with a fractional (fractal) exponent. The number of closed depressions of given depth or diameter falls off exponentially with increasing size. Blind valley areas relate to stream length and stream order by power laws. Some features of bedrock sculpturing occur at fixed scale. Pinnacle karren, however, appear to be scale invariant over seven orders of magnitude of scale range.

Permeability Measurements on Cementitious Materials for Nuclear Waste Isolation

Gas and liquid permeability measurement methods have been developed and utilized for characterization of cement composites and rocks for application to nuclear waste geologic repository problems. Permeabilities in the millidarcy to tens of nanodarcys range have been measured reproducibly and are related to problems of borehole plugging and shaft sealing.

Hydrated calcium aluminosilicate cements for hydrothermal bonding

Hydrated calcium aluminosilicate cements have been prepared under hydrothermal conditions in the temperature range 110–450°C and pressure range 6.8–68 MPa. Bonding results from mixtures of the phases boehmite, qibbsite, C3AH6, X-phase, hexagonal anorthite, anorthite and quartz which are formed in various combinations under different conditions. Strength and other physical properties remain fairly constant throughout the range. These cements may have applications in cementing at depths in the earth or in refractory castables under elevated temperature and pressure conditions.

Hydrology and Hydrogeology of Mammoth Cave

Mammoth Cave and its associated drainage is the downstream portion of a much larger aquifer system which includes recharge from sinking streams at the southeastern edge of the Sinkhole Plain, internal runoff and diffuse infiltration from the Sinkhole Plain, and runoff from valley drains and the caprock of the Mammoth Cave Plateau. The aquifer drains through a sequence of large springs along Green River. Extensive tracing of flow paths with fluorescent dyes shows that each spring has a distinct drainage basin with some spillover depending on recharge. Basin area can be estimated from measured base flows of the karst springs. Green River flows in a narrow valley that produces high flood levels that backflow into the springs carrying muddy flood waters deep into the conduit system. There is a complex flux of clastic sediments, some from upstream and some back-flooded from the river, that moves through the conduit system in response to storm flow. Chemical analysis of spring water, cave stream water, and cave drip water allows the calculation of dissolved carbonate (hardness), chemical saturation state, and concentration of dissolved CO2. Spring and shaft waters are undersaturated; drip waters are supersaturated. CO2 concentrations exhibit a pronounced maximum during the growing season. Although the Mammoth Cave System contains more mapped passages than any cave in the world, the sad truth is that only a small fraction of the active drainage system is accessible to direct observation and survey.

Rheological and Physical Properties of Magesium Oxide and Silica Fume-Modified Cement Mortars Cured at High Temperature

Physical properties and placement characteristics of cementitious mortars have been studied for their potential as repository sealing materials. They contained various expansive agents and industrial by-products, and were investigated at curing temperatures up to 250° C, the upper limit of an emplacement site or generally of relevance in accelerated reaction studies. An expansive agent, magnesium oxide, and two industrial by-products, silica fume and granulated blast furnace slag have been used at different percentages in the mixtures. Excellent general performance, including very high strengths up to 240 MPa combined with very low intrinsic permeability −8 Darcy (μm 2 ) were generated at 175°C on material having a viscosity of 5000 cP (mPa·s) at 38° C. One 1700 cP(mPa·s) material treated at 250°C had compressive strength >180 MPa and also −8 Darcy (μm 2 ) permeability. MgO was found to accelerate formation of tobermorite and generally cause expansion; at 250° C expansion was also related to xonotlite formation.