Underground River Research Articles

Resistance of groundwater invertebrates to droughts: Two new cases in planarians and isopods

AbstractBenthic invertebrate communities are deeply influenced by hydrological variability in surface freshwater habitats. However, the responses of macroinvertebrates composing stygofauna in aquifers and unsaturated groundwater environments are not well understood nor specifically studied. Here, we present two new cases of resistance to drying in groundwater‐dwelling animals: planarians of the genus Dendrocoelum and the isopod crustacean Monolistra pavani. Multiple surveys were performed in 53 caves of the Italian Alps and Apennines, sampling different stable and unstable subterranean aquatic environments. Planarians and crustaceans were searched visually and by distressing the substrate. When we detected individuals in dry sectors, we photographed them, observed their features, and released them in pools or streams of the same cave. We rinsed dry individuals of M. pavani in small tanks and recorded the time of reactivation. In a dried subterranean stream, we observed a Dendrocoelum planarian encapsulated in a thick mucus layer, which after a total of 5 min started gliding slowly and reached a length of 18 mm. During the drought of January–April 2022, we detected several individuals of M. pavani in dry areas of two caves. In total, 72% of the tested individuals were able to reactivate. This percentage decreased to 42% after 20 days of dryness. Time to reactivate ranged between 0 and 30 s. Living individuals were observed even after 39 days of drought. Our observations provide new insights into the natural history of groundwater‐dwelling invertebrate taxa that are often neglected in the studies of freshwater ecology. Resistance of groundwater‐dwelling animals to droughts has several implications for global climatic changes and could be species‐ and site‐specific, as previously observed in surface macroinvertebrates.

Groundwater invertebrates and droughts: resistance in stygobiont isopods and planarians

In surface freshwater habitats water level can be strongly variable and benthic invertebrates are usually adapted to cope with hydrological variability. Groundwater habitats are usually more stable, even if in sites at the interface with the vadose zone, in epikarst streams and dripping pools hydroperiod may vary. Adaptations to survive droughts are thus likely to have been developed also by groundwater-dwelling animals. However very few studies have been performed to assess stygobiont resistance to dryness. They involve mainly the amphipods of the genus Niphargus and Stygobromus; one case is reported for a triclad of the genus Atrioplanaria. Here we describe cases of resistance to drying in stygobiont planarians of the genus Dendrocoelum and the in the isopod Monolistra pavani. Since 2016 we performed multiple surveys in 53 caves in Italy and Switzerland, sampling different stable and unstable groundwater environments. Stygobionts were searched visually and by distressing the substrate. When we detected stygobionts in dry sectors of a cave, we observed their features and behaviours, we pictured them, and we tried to rinse them. We rinsed M. pavani individuals in small plastic tanks and recorded the time of reactivation. During the surveys we recorded a Dendrocoelum planarian encapsulated in a thick mucus layer on the substrate of a dry subterranean stream. When placed in water the planarian started gliding slowly and reached a length of 18 mm. During the drought of January-April 2022, we detected individuals of M. pavani in dry areas of two different caves. 72% of the individuals were able to reactivate. Time to reactivate ranged between 0 s to 30 s. We recorded living M. pavani individuals that were able to reactivate themselves even after 39 days of drought. Our observations provide new insights into the natural history of groundwater-dwelling invertebrate taxa which global climatic changes increase the risk of drought occurrence in subterranean environments.

Cave map: condition, potential, and danger information of cave passages in Malang Regency, Indonesia

The cave maps provide information of the cave passage condition. Cave maps are generally used in various studies, such as archaeology, geomorphology, hydrology, and others. In this study, the map used is the basic cave map which is generally used in field surveys. The method used in this research is a map literature study which is then followed by a field survey to observe the real conditions. After doing the observation, the next step is interpreting the cave map, digitizing on screen, and doing descriptive analysis. The results of this study show that there is a variety of information presented in the cave map, including the condition of the cave related to the cave passage segment, the overall pattern of the cave passage, and quantitative aspects in the form of passage length, passage depth, cave passage area, and the cave area itself. Potentials that can be seen with the cave map are subterranean rivers and the presence of cave ornaments. And by looking up the map, the information about the dangers in cave exploration related to the dangers of collapse, flooding, landslides/erosion, and low oxygen will be found out.

ELABORATIVE ANALYSIS OF CAVES AS SPECIFIED TOURISM DESTINATION IN MALANG REGENCY – INDONESIA

Malang Regency has variety of landscapes. In the southern part of Malang Regency, there is a karst landscape showed by the existence of caves scattered in Wonosari Formation. The existence of those caves holds an important potential as the environmental services, one of those is as a specified tourism destination. The aim of this study is to know the condition and to analyze the potential of the caves a specified tourism destination in Malang Regency. The data in this study was collected by observing the condition of the cave through the cave passage and by doing in-depth interview with the manager of tourism objects in Malang regency. Field documenting and literature studies were also being conducted in order to support the analysis of this study. Data analyzing was conducted by using interactive data analysis consisted of data reduction, data presentation, ended by conclusion drawing. The result of the study showed that 134 caves had been recorded and 49 caves been mapped. Caves in Malang Regency potentially support the specified tourism destination. This was showed by the passages varied into horizontal cave passage and vertical cave passage. Some of the caves also have long passage. Besides the variety of caves passages, the caves in Malang Regency also have variety of ornament and the condition brings the value of education to the tourists. Some of the caves have subterranean river which can be used by the people. Thus, it becomes tourists’ attraction. The caves in Malang Regency are located close to coastal areas that become beach and marine tourism, so it will really support the development of caves as a specified tourism destination in the future. In order to acknowledge and enrich the society with skills dealing with the existence of caves as a specified tourism destination, the improvement of human resources should be carried out.

Cenote Chen ha, and water quality indicators

The cenotes of the Yucatan Peninsula are characterized by karstic relief, warm temperatures, and transparency of their water bodies. The mixture of fresh water from infiltrations of rainwater and runoff coupled with underground rivers or marine intrusion, make up the habitat of aquatic, amphibian, and terrestrial species. The Chen ha cenote, located in Chocholá, was used for tourist purposes, however, the lack of an environmental culture and some anthropogenic activities cause deterioration and contamination of the wetland, which putting its conservation at risk. The objective of the present work was to carry out a limnological analysis in Cenote Chen ha, to determine the level of fragility of the ecosystem. The variables analyzed were pH, dissolved oxygen, temperature, conductivity and phytoplankton biodiversity. Results. 2600 µS/cm of conductivity, 8.25 pH and 2.8 ppm of dissolved Oxygen. Phytoplankton: Diatoms 46.2%, Cyanobacteria 38.1%, Chlorophytes 8.1%, Euglenas 5.5%, and Dinoflagellates 2.1% predominated. Asterionella was identified as an indicator species of environmental health. Microcystis aureginosa, Planktothrix agardhii, and Cyanosarcina caribeana, Pseudanaena, Peridium and Gonyaulax species are shown as indicators of environmental contamination. No dominance of any species was observed; however, frequent monitoring of indicator species is recommended.

Identification of Karstification Zoning and Aquifer Channels in Karst Basin at Sendang Biru Beach, Malang-Indonesia: A Case Study

Karst zoning and channel aquifers in the karst basin at Sendang Biru Beach, Tambak Rejo Village have been investigated. Sendang Biru Beach has a cave appearance as a karst morphological feature and is composed of limestone. Seasonal karst water sources come from springs, surface runoff, underground rivers, channels in valleys, basins, and slopes that often experience drought. The purpose of this study is to identify the presence of karst aquifers and karstification zones that are prone to damage or disasters in the karst environment. The method used is a geophysical combination of Electrical Resistivity Tomography (ERT), Induced Polarization (IP), and Self Potential (SP). The results showed that the eastern part's karstification zone was characterized by moderate to high resistivity and a chargeability zone with a moderate to high range. In addition, the existence of karst aquifer channels in the anomalous zone of low resistivity, high chargeability, and negative natural potential. This zone is located in the Qas Formation, with the water flowing from west to east and from west to south. The inundated karst aquifer that spreads in a circular pattern with different depths interspersed by limestone cracks causes a heterogeneous karstification process.

Valuasi Ekonomi Kawasan Karst Desa Jatijajar Kecamatan Ayah Kabupaten Kebumen

Jatijajar Village which is included in the Gombong karst area in accordance with the Minister of Energy and Mineral Resources Decree No. 3043 K / 40 / MEM / 2014 and confirmed by the Kebumen Regency Regional Regulation No. 23 of 2012 concerning RTRW of Kebumen Regency for 2011 - 2013. Karst is a landscape of the karstification process of carbonate rock (CaCO3) which is deposited after passing through the available geological space and time. Karst has a distinctive hydrological condition due to the dissolution of carbonate rock due to the physical properties of limestone which is easily soluble and has secondary porosity so that it cannot store water for a long time. Rainwater that flushes the karst area directly falls to the bottom of the water-saturated zone and then flows through cracks and large passageways (caves) such as canals to springs exit points or is directly dumped into the sea, only a small amount flows on the surface. Until now, it has the potential value of environmental services (environmental services) and ecological services both in the karst area itself and in the non-karst area which is used as a buffer zone. The underground river system that is formed in the karst area provides benefits to the environment around the karst area and even the community as a provider of clean water needs that are perennial / flowing throughout the season. Characteristics of natural resources in the Karst Gombong area of Jatijajar Village have resource characteristics in the form of direct use, namely from the existence of a water hydrological system from the karst area which consists of the value of water resource utilization which is used to meet household needs, the value of water resources for lowland rice farming, and Water Resources from underground rivers in the karst area are 15 springs. The total economic value of the potential use of existing resources in the Gombong Karst Gombong area of Jatijajar Village is IDR 87,616,789,519 in one year. The magnitude of this value is the value of natural and environmental resources from the direct use of the availability of natural resources to the community. These values will be lost if the karst area is damaged either from mining activities or changes in environmental functions. In fact, this value will be a value that must be spent by the community in order to compensate for the loss of potential natural resources in the karst area

Detection of karst caves during tunnel construction using ground‐penetrating radar and advanced drilling: A case study in Guangxi Province, China

ABSTRACTIn karst topography, hidden caves or underground rivers may imperil the safety of tunnels. It is critical to accurately detect the location and geometric shape of hidden karst caves for assessing the safety of tunnels. This paper reports a case where a large karst cave was exposed during the construction of the Nongmo tunnel in Duan County, Guangxi, China. A 2D ground‐penetrating radar survey was employed to preliminarily detect the distribution of hidden karst caves along the tunnel axis. Advanced drilling was used to obtain the velocity of electromagnetic waves and verify the 2D ground‐penetrating radar detection. Ground‐penetrating radar 3D grid detection was carried out for further detecting the geometric shape of the hidden karst caves. Rotary thrust power ratio, which is a function of drilling speed, rotating speed, propulsion pressure and torque, was proposed to reflect the integrity of the surrounding rocks. It was found that the depth of the peak value in the rotary thrust power ratio curve is consistent with that of the amplitude jump in ground‐penetrating radar A‐scans and in time–frequency distributions. The results of 3D attributes analysis indicate that due to the variation of highlights in different ground‐penetrating radar signal attributes, the obtained karst cave shapes using different attributes would be various. A multi‐attributes fusion method was proposed to generate a data volume considering various attributes. The 2D geometric shapes at different depths were obtained using the anomalous body lineament in the generated date volume slices. The 3D geometric shapes were reproduced by combining the obtained 2D geometric shapes at various depths. Based on different detection and analysis methods, the outline shape of karst caves at YK364 + 199 ∼ YK364 + 184 of the Nongmo tunnel was revealed in detail.

Trade-off and synergy analysis among ecosystem services in a karst watershed

The underground river watersheds in karst areas are undergoing the degradation of ecosystem functions, thus hindering the development of benefits to humans. Taking the Nandong underground river watershed (NURW) as a test case in southern China, this study evaluated net primary productivity (NPP), water yield (WY), and soil retention (SR) and the relationships between the three factors from 2000 to 2018. The results showed that (1) NPP exhibited a continuously rising trend from 2000 to 2018, and the WY and SR also increased in general; (2) land use was an important influencing factor for ecosystem services, and the synergy between the two improved since 2006; (3) the ecosystem synergy was poor in the NURW, and the conflicts among ecosystem services were especially severe in areas with a high incidence of rocky desertification. This study will provide a reference for regional governments by clarifying the possible future state of the ecosystem.

Distributed rainfall-runoff simulation for a large-scale karst catchment by incorporating landform and topography into the DDRM model parameters

Runoff movement in karst catchments is of great complexity. Although many models have been developed for the rainfall-runoff simulation in karst catchments, the distributed ones, capable of taking into consideration the impacts of the spatial variability of hydrogeological factors, are few and can only be applied to well-explored karst catchments of commonly less than 100 km2 in area. In this study, the previously-published DEM (Digital Elevation Model) -based distributed rainfall-runoff model (DDRM) was applied and modified for distributed rainfall-runoff simulation in a large-scale karst catchment by assuming the main parameters of runoff generation and routing for each grid cell to be a function of karst landform and topographic index (i.e., the mathematical expression of topographic features) to represent the hydrological effects of epikarst and underground river system. For model structure investigation, three versions of the modified DDRMs, i.e., the DDRM considering only karst landform (DDRM_K), the DDRM considering only topographic index (DDRM_T), and the DDRM considering both karst landform and topographic index (DDRM_KT), were set up and compared with the original DDRM (i.e., the original DDRM, termed as DDRM_O). All four DDRMs were calibrated with a multi-objective optimization framework that uses the Kling-Gupta Efficiency of streamflow (KGEQ) and the autocorrelation function of streamflow (KGEACF) as objective functions to improve parameter identifiability. The investigation was conducted in the Xijiang Basin, which is a typical karst catchment in Southwest China with an area of 309300 km2. The results show that, compared with DDRM_O, DDRM_T barely benefits the rainfall-runoff simulation, while both DDRM_K and DDRM_KT noticeably enhance the simulation accuracy in terms of KGEQ. Due to the better performance in high flow and autocorrelation function of streamflow, DDRM_KT outperforms DDRM_K in general and has the potential to be successfully applied to large-scale karst catchments.

Stable isotope variability of precipitation and cave drip-water at Jumandy cave, western Amazon River basin (Ecuador)

Monitoring studies are necessary to better understand the hydrological processes affecting the isotopic signature of cave waters, which are ultimately recorded in speleothems that are used as paleoclimate archives. This research examines changes in the isotopic composition (δ18O and δ2H) of precipitation as it infiltrates through the epikarst and into the Jumandy cave, located in the western Amazon Basin (Ecuador). Meteorological and hydrological parameters were monitored outside and inside the cave, and isotope analyses were carried out in waters from rainfall, an underground river, and drip-water at two sampling sites in the cave between April 2019 and February 2020. At monthly timescale, the rainfall weighted isotopic composition monitored at our stations was strongly correlated with the mean precipitation amount. However, when considered at weekly time-steps, the correlation is only moderate. This implies that the variation of the isotopic composition in the study area cannot be interpreted exclusively as an amount effect. Isotopic values and back-trajectory modeling show that the isotopic signature was affected by the moisture source effect associated with upstream rainout. The moisture flux is dominantly from an east to northeast direction and moisture mainly originates over the Atlantic Ocean, passing through the Amazon Basin. A significant fraction of moisture is associated with local sources within the Amazon Basin. This aspect is confirmed by d-excess values of rainfall and the Local Meteoric Water Lines (LMWLs) that indicate an influence of the high evapotranspiration rate of the Amazon region on the isotopic composition of local rainfall. The infiltrated water resides for about three weeks in the epikarst and then precipitates forming speleothems (residence time). However, this short residence time needs to be confirmed with a longer monitoring period. Despite the different magnitudes of the dripping rates, the isotopic values at the two monitored sites are similar. This suggests that the dripping discharge rate is affected by the karst structure, but the isotopic signature reflects the mixing of individual rainfall events above the cave. Therefore, ẟ18O in speleothems from these caves is mainly recording short-term precipitation changes linked to regional and large-scale atmospheric circulation.

Construction of a hydrogeochemical conceptual model and identification of the groundwater pollution contribution rate in a pyrite mining area

To effectively restore the groundwater environment of the Shiping Mine (SPM) area, which is contaminated by acid mine drainage (AMD), a hydrogeochemical conceptual model was constructed based on groundwater chemistry and environmental stable isotopes. The contribution rate of various pollution sources in the groundwater environment was quantitatively analyzed using an optimized stable isotope mass balance model. A total of 68 groups of water samples were collected. The sampling period covered the dry, intermediate, and wet periods of a complete hydrological year. Samples were taken from rain, springs, mine drainage, tailings leachate, and surface water; and the detection and analysis indicators included 24 parameters, such as inorganic salts, heavy metals, and isotopes. A hydrogeochemical and statistical data analysis was performed. The main source of groundwater replenishment was found to be atmospheric precipitation, with the water-rock interaction of calcite and pyrite, and mining activities being the main controlling factors of hydrogeochemical processes. Acid mine drainage significantly enhanced the dissolution of various minerals, and the detection rate of Zn, Cu, As, Cd, and Pb increased from 0–30%–100% when compared with groundwater in the area upstream of the mines. The optimized mass balance model results revealed that the contribution rates of upstream groundwater, mine water and leachate were 0.78–0.86, 0.08–0.18, and 0.04–0.06 for Heidong underground river, respectively; were 0.27–0.36, 0.62–0.68, and 0.03–0.05 for Tiantang underground river, respectively. Furthermore, based on the water balance analysis, 34–70% of the mine water was found to infiltrate directly through karst fissures and karst pipes and could not be collected at the mine entrance. Acid mine drainage that directly infiltrated through runoff could easily be ignored due to the hidden migration path, which may cause the groundwater environment to be remediated less effectively than expected.

WATER RESOURCE MANAGEMENT UNDER CLIMATE CHANGE: IMPLICATIONS FOR SUSTAINABLE USE ON KARST TERRAIN

The scarcity of freshwater is a critical issue that continuously is considered to be important around the world. The availability of freshwater steadily decreases because of growing population, high water demand and global climate change. Underground streams water and aquifers within karst terrain is assessed as an substantial factor of water supply systems in karst areas, and in the case that is assessed in this paper as well. Therefore, water management on karst area is essential to solve water deficiency problems, particularly during dry season. In this paper, management of karst spring water is discussed based on some cases from Citatah karst. Management of spring water is the main object of this paper that use mix method design, incorporating a qualitative and a quantitative approach. Result showed that inadequate human resource, infrastructure, database system; lack assertiveness, supervision and instrument of rules implementation; and low level of awareness and participation are found as the main factor of poor management of karst spring water at Citatah karst. However, better management could be attained by improving capacity building, strengthening monitoring capabilities, formulation of groundwater policy, implementing economic and financial instruments, improving participatory management and applying sustainable technology for agricultural and domestic water use.

Study on the Characteristics of Surrounding Rock and Design of Backfill Material Parameters for Tunnels Passing through Giant Caverns and Underground Rivers

The influence on tunnel construction of karst and underground rivers is always an important problem in tunnel engineering. In order to demonstrate the rationality of backfill parameters and the effectiveness of supports under the influence of groundwater when a tunnel passes through a large karst cave, the finite element software FLAC3D was used for numerical analysis. Converting the mean values and standard deviations of mechanical response results of the surrounding rock and the supports on multiple sections into the ECULID distance from the origin point on a two-dimensional plane as evaluation indexes, the influence of the reinforcement parameters on the mechanical response of the surrounding rock and the supports was analyzed by orthogonal experiments. Based on fuzzy decision theory, by regarding the ECULID distance between the simulated result of each group and the global optimal value of the multiple evaluation index as the comprehensive evaluation index, a backfill parameter design method was proposed. By comparing the results which used optimal and worst parameters in the FLAC3D, 10 times and 2.5 times differences in longitudinal and horizontal displacement were observed, respectively. Then, the optimal backfill parameters were applied to the actual project for verification. The field monitoring results showed that the optimal backfill parameters can effectively reduce the displacement around the tunnel. After constructing a diversion for the underground river, the water flow in the karst cave did not rise during a rainstorm. This study provides a reference for the design and construction of other projects in the future.

Background clutter amplitude and frequency of GPR signals to analyse water content in sedimentary deposits: Urban infrastructure environment

Soil site studies are crucial in the analysis of seismic hazard in populated areas. This study focusses on the use of the Ground Penetrating Radar as a non-destructive geophysical method to analysis the water content of a sedimentary basin of a local urban area in Cervantes Parks in Barcelona city. Main objective of this work is to understand further the local seismic soil site, and analysis the background clutter amplitude and frequency of the GPR signal applied on the seasonal changes of the underground water content. Changes produces in the GPR signal could be associated to the changes of the ground material due to the existence of water content and water flow, which influence the grain size distribution of the soil characterisation.Previously, several methodologies have been applied to determine the changes of the ground material due to the existence of water content and most importantly effect of the seasonal changes on the soil characterisation. GPR has been applied as a new technology and non-invasive to further analysis water content in shallow geology. Methodology applied on this study compromised in four different phases; Two seasonal data collection using 100 MHz centre frequency shielded antenna in both dry and wet season, radar images are proceeded with common post-processing approaches, following more innovative processing approach based on the Fast Fourier Transform (FFT) method in order to analysis background clutter amplitude and frequency spectrum to achieve an accurate interpretation of underground water content activities, in conclusion a comparative study of the results driven from radar images are elaborated considering historical knowledge. Results show that GPR is an efficient technique to analysis water content invasively considering low frequency antennas to achieve deeper penetration depth in sedimentary deposits, and predict shifting and increasing of the underground streams due to changes in weather conditions. Results could contribute to the enhancing local seismic site behaviour in populated areas considering continuous monitoring of underground water activities in sedimentary basin sites.

The effect of heavy rainfall events on nitrogen patterns in agricultural surface and underground streams and the implications for karst water quality protection

Special hydrological structures coupled with rainfall and agricultural activities have great impacts on water quality in karst areas. High-frequency hydro-chemical, dual nitrate isotopes and a Bayesian mixing model (SIAR) were employed to investigate the effect of heavy rainfall events on nitrogen patterns in surface and underground streams and explore the implications for nitrogen pollution prevention in a typical karst agricultural catchment in Southwest China. The results showed that [NO3--N] was relatively high in both surface and underground streams and the average value in surface stream was two times higher than in underground stream. The lowest [NO3--N] of underground stream was found in the falling limb of the hydrograph. According to source apportionment by SIAR, chemical fertilizer was the dominant nitrate source in the study area, which contributed 52–81% and 29–78% of nitrate in surface stream and underground stream, respectively. The highest dissolved inorganic nitrogen flux and [NO3--N] in surface stream was 5.7 times and 2.4 times higher, respectively, than in underground stream over the same period, which suggested that surface runoff rather than underground stream was the main route of rapid nitrogen loss in the karst catchment during heavy rainfall events. Reasonably planning the fertilization time and optimizing nitrogen fertilizer use should be considered to decrease nitrogen loss from farmland. Rational use of a widespread karst underground conduit system to reduce water nitrogen content may also be a potential method for achieving nitrogen removal.

Age of the epigenetic karst from the central region of Sierra de los Órganos, Pinar del Río, Cuba

The epigenetic karst age in the central region of Sierra de los Órganos, is defined from the moment the carbonated sequences are uncovered and denudation processes begin at the end of the Oligocene and early Miocene (approximately 25 Ma). Although the karstic forms in this region originated at different times, they all coexist in today’s landscape. While the area was rising up slowly and sea level changes were taking place, the regional erosion base level descended giving rise to leveling surfaces desiccated by numerous sinkholes. At this time, surface currents disappear to become underground streams, which have carved out an extensive network of galleries. Satellite images and aerial photos interpretation, geological survey, measurements of morphostructures and multivariate statistical analysis, were the methods used to establish the epigenetic karst evolution model for the region. The model includes nine surfaces of erosion base levels, in a range that goes from the 410 m a.s.l., coinciding with the older erosion base levels conserved in the area (23 Ma before the present), until the 50 m a.s.l., corresponding to the surface of current erosion.

Stephen Bishop: The Celebrated Guide of Mammoth Cave

Stephen Bishop: The Celebrated Guide of Mammoth Cave Angelo I. George (bio) and Gary A. O’Dell (bio) An Extraordinary Man It was a pleasant afternoon in Kentucky in the spring of 1844.1 A few guests lounged on the veranda of the Mammoth Cave Hotel, some strolled about the grounds admiring the verdant scenery and clusters of wildflowers, while others consulted with their host about the evening menu or their plans for underground adventures. They were completely unaware that, deep in the earth below this tranquil setting, a life-and-death struggle was taking place. Here, where the Jordan River ran deep and cold through Mammoth Cave, a tiny group of terrified souls huddled together in neck-deep water in an [End Page 99] absolute and fearful darkness. Torches extinguished by the sudden plunge into the chilly waters, they were unable to discern the features of the nearest person. What began as a thrilling honeymoon adventure for two newlyweds and a pair of their closest friends had turned into a fight for survival when their boat capsized while traversing the subterranean river. They clung to each other and grasped at projections on the mud-slick walls of the passage, convinced of impending death.2 Earlier that day, the wedding party of four from Bowling Green entered the cave, led by African American guide Stephen Bishop. Subsequent events suggest that some in the party became quite inebriated after a rest break in a location near the termination of Cleave-land’s Avenue, also called the Dining Table or Cornelia’s Table. As part of the caving experience, the guides would take a basket full of food and alcoholic beverages to be served at this location. Numerous published accounts record that after the meal, visitors often became tipsy from “choice old sherry.” The wedding party may have been celebrating with alcoholic refreshment even prior to this point. Bishop led his charges into the lowest level of the cave where the Jordan River had to be traversed by boat for nearly a mile, filling the passage from wall to wall and nine feet deep in places. After disembarking at a side avenue and exploring, they came back to the river and boarded the boat for a return to the surface. According to one account, “some of the party, who were in high glee, got into a romp, and overturned the boat. Their lights were extinguished, their matches wet, the boat filled with water and sank immediately . . . [they were] up to their chins in water.”3 Despite the harrowing circumstances, Bishop maintained composure and calmed the frightened tourists struggling in the cold water. [End Page 100] During his independent explorations of the cave, he had on many occasions been forced to traverse passages while neck-deep in water. He knew the present situation was potentially quite perilous and that the visitors could drown if allowed to panic. He cautioned them to “remain perfectly still, for if they moved a single step they might get out of their depth in water, and swimming would not avail them, for they could not see where to swim to.” Moving about could plunge them unexpectedly into water over their heads. When the wedding party failed to return to the surface at the designated time, a search and rescue team from the hotel was dispatched. Mat Bransford, another Black guide, led the rescue party and located the missing tourists when he heard Stephen “cheering them, and directing his movements while swimming, by the sound of their voices, which were raised, one and all, in prayer and supplication for deliverance.” Everyone was returned safely.4 Stephen L. Bishop (1820–1857) was the foremost guide at Mammoth Cave during the antebellum period whose daring exploits, personal magnetism, and knowledgeable discourses on the science of caves brought him international celebrity. Newspaper accounts and guidebooks of the period heralded Bishop as the “Columbus of the Cave;” his enslaver, Franklin Gorin, described him as a “fine genius;” English journalist Thomas Gunn referred to him as the “Cave Lion;” and newspaperman Bayard Taylor reported that Bishop was the “ruler of his realm.” One tourist praised “Stephen the illustrious . . . guide [End Page 101] Click for...

Characteristics of nitrate and heavy metals pollution in Huixian Wetland and its health risk assessment

In order to investigate the main factors that caused the Nitrate increasement in Huixian Wetland, 15N-NO3 and 18O-NO3 analysis were conducted. SIAR model was applied to quantitatively test the contribution proportions of kinds of pollutants. Health risk assessment (HRA) was taken to study ten heavy metals of 96 groups samples in the four main waters in Huixian Wetland: Surface River, Subterranean Stream, Blue Hole and Well Water. The main sources of Nitrate were domestic sewage and animal feces, chemical fertilizer, and soil, with the contribution proportions of 39.1%, 32.2%, and 28.5%, respectively. The heavy metals concentration order is that of Mn > Al > Cr > Zn > As > Pb > Cu > Fe > Cd > Hg. The HRA showed that the average annual total health risks-through drinking and skin penetration-order was: Well Water > Blue Hole > Subterranean Stream > Surface River. The drinking water from Well and Blue Hole can cause the cancer risks in children of 7.08 × 10−5 a−1 and 7.01 × 10−5 a−1, respectively. Both were higher than the recommendation standard (5.0 × 10−5 a−1) from ICRP. As the main element contributed to the health risk of adults and children, the Cr in all the four waters were also over the standard (1 × 10−6 a−1) recommended by the Swedish Environmenta1 Protection Agency and the Dutch Ministry of Construction and Environment and the British Royal Society. The health risk levels of non-carcinogenic metals were 1 × 10−16–1 × 10−10, which were 5–11 order of magnitude lower than the acceptable level.

Wellbore Flow Model and Process Optimization for Gas-Lift Leakage Drilling for Shallow Shale Formations.

The shallow surface karst landform in the Nanchuan-China shale gas area, with developed caves and underground rivers, frequently lost circulation during the drilling operation. To solve the issue, first, according to the actual drilling engineering, this paper analyzes the geological factors and drilling and completion characteristics, optimizes the construction plan, and suggests a new technology for gas-lift leakage drilling based on double-wall drill pipes. Second, a distributed coupling improved Beggs–Brill gas–liquid–solid multiphase flow model is established. This model is used to complete the optimization design of the gas-lift leakage penetration construction scheme of the well sy20-2. Finally, the accuracy, process feasibility, and effect of the model are verified after the field application. The test results show that this method can establish a full drilling fluid circulation without plugging the leakage, control the leakage rate to within 0.5 m3/h, more than 90% reduction in the loss of circulation, and significantly shorten the nonproduction time limit with good application prospects.