Sustainability of Water Resources in Karst Undermined by Tunneling: A Case Example

Water resources in karsts are scarce due to the high cavernosity in the otherwise low-permeability limestone rock mass. The highly variable porosity and transmissivity of karst aquifers are caused by a network of channels, caverns, and caves that typically act as water-bearing, connected vessels. Tunneling in a karst environment can severely deplete an aquifer and undermine the sustainability of water resources over the long term. A research study was carried out to elaborate and develop measures for the sustainable preservation of the water resources in a Slovenian karst, in which two approximately 7 km-long tunnels will be driven as part of the construction of the new Divača–Koper railway line. Hydrogeological site investigations were carried out with an aim to evaluate the transmissivity and spatial spreading of the karst aquifer along the route of the tunnels, including the observation of the long-term variation of the groundwater levels and trace experiments. The main findings, which are presented in this paper, were used to develop a methodology for the selection of adequate measures for tunnel construction with an aim of ensuring the sustainability of water resources in karst aquifers. The construction measures comprise limiting the inflows using injection grouting, obscuring the groundwater intake by undrained sections of the tunnel, and constructing bypasses around the tunnel to preserve the current groundwater flow regime. The presented methodology of dynamically accommodating the preventive measures to the actual hydrogeological conditions onsite is generally applicable for common cases in which the state of the karst aquifer could not be pre-determined with a sufficient accuracy of tens of meters to a meter. The spatially and temporally continuous hydrogeological investigations and decision-making charts to reduce the tunnelling’s impact on the karst aquifer are explained in detail in this paper.

Unusual catchment runoff in a high alpine karst environment influenced by a complex geological setting (Northern Calcareous Alps, Tyrol, Austria)

Garber Schlag (Q-GS) is one of the major springs of the Karwendel Mountains, Tyrol, Austria. This spring has a unique runoff pattern that is mainly controlled by the tectonic setting. The main aquifer is a moderately karstified and jointed limestone of the Wetterstein Formation that is underlain by nonkarstified limestone of the Reifling Formation, which acts as an aquitard. The aquifer and aquitard of the catchment of spring Q-GS form a large anticline that is bound by a major fault (aquitard) to the north. Discharge of this spring shows strong seasonal variations with three recharge origins, based on δ18O and electrical conductivity values. A clear seasonal trend is observed, caused by the continuously changing portions of water derived from snowmelt, rainfall and groundwater. At the onset of the snowmelt period in May, the discharge is composed mainly of groundwater. During the maximum snowmelt period, the water is dominantly composed of water derived from snowmelt and subordinately from rainfall. During July and August, water derived from snowmelt continuously decreases and water derived from rainfall increases. During September and October, the water released at the spring is mainly derived from groundwater and subordinately from rainfall. The distinct discharge plateau from August to December and the following recession until March is likely related to the large regional groundwater body in the fissured and moderately karstified aquifer of the Wetterstein Formation and the tectonic structures (anticline, major fault). Only a small portion of the water released at spring Q-GS is derived from permafrost.

Karst-Induced Geoharzards in Kenya’s Coastal Region: A Case Study of Vipingo Coral Limestone Quarry

As the human population grows, the demand for space to settle and infrastructure development puts a strain on land resources hence people move to occupy areas of difficult terrain such as mountainous regions and karst environments. The trends in anthropogenic activities mean that there will be increased human interaction with the perilous terrain and consequently geohazards associated with them. Studies on geohazards in Kenya have focused mostly on landslides in mountainous regions but not much has been reported on geohazards that are common in areas of carbonate rocks such as coral limestone. Vipingo coral limestone quarry, a coastal quarry, is taken as a case study as a number of hazardous situations have been encountered during mining. This paper outlines the karst features, their formation processes in the coralline limestone rock mass, and the resultant geohazards. Field visits made to the quarry complemented with previous exploration reports enabled the collection of field data on rock mass characteristics, karst features, and potential hazardous sites were mapped out. Karstification is evident in traces of pores and fissures filled with soil in the upper layers of the rock. Cavities, voids, and caves occur randomly in the rock mass and are the genesis of incidents such as bench collapse, sagging of overlying rock slaps leading to sinkholes. The rock mass is weak and prone to slope failures. Suggestions have been fronted for geohazard mitigation and further research work for the scientific community. Thus, this work constitutes an important knowledge base for infrastructure development and any other quarries around the area, and for those who are settled around this karst environment in order to preempt geo-accidents.

Managing Nature-Based Tourism in Protected Karst Area Based on Tourism Carrying Capacity Analysis

Nature-based tourism relies on the beauty of nature to maintain sustainability and attraction. However, karst environment is vulnerable to disturbance due to tourism activity. This study, therefore, aims to analyze the social, ecological, physical, real, and effective carrying capacity of Pattunuang Assue Nature Tourism Object, Bantimurung Bulusaraung National Park. Data were collected through field measurement, observation, and interviews. Data of visitors’ favorite spot and its size were measured through observation and field measurement. Visitors’ perceptions related to the destination, including their duration activities were collected through interviews. It was further collected by observing the various spots of activity, and measuring the area of restrictive factors such as physical (number of rainy days), biotic (vegetation diversity at tree level, the diversity of birds during the busy visiting hours, the initial period of the Tarsius fuscus’ birth). We also observe the equipment and infrastructure of the destination and collected data related to management through interviews with the managers. This study reveals various carrying capacity value which can be used as an option for the managers to choose the best way to manage destination in the right way. The result showed that particular activities exceeded carrying capacity but other activities far below their carrying capacity value. The study furthermore discusses how to deal with numerous activities. It also suggests an increase in the number of visitors by considering their ecological characteristics and management capacity.

Investigation of Drainage Structures In The Karst Aquifer System Through Turbidity Anomaly, Hydro Geochemical And Stable Isotope Analyzes (Kiyan Springs, Western Iran)

Karst aquifers typically have desirable physicochemical properties and can provide an important source of groundwater for drinking. Kiyan karst springs, located in the geological region of the Zagros (western Iran), consist of two springs (Keder and Zolal) situated 3 meters apart. The water of Zolal spring is always clear, with no turbidity during rainfall or earthquake phenomena, but Keder spring, which also provides drinking water to a city of 10,000 inhabitants (Kiyan city), has very high turbidity in these conditions, and this disrupts the drinking water supply for about 1 month per year in the study area. The interpretation of discharge time series diagrams, precipitation, and turbidity in different rainfall and earthquake conditions, composite diagrams, and stable isotope concentrations shows this study area to be a well-developed karst environment with ahighlyeroded tectonic zone and large karst conduits along with turbulent water flow. In general, the difference in the behavior of the two springs is related to different paths of water movement through the drainage area.The two springs share the same source of recharge from rainfall and the same initial underground drainage path from the largest sinkhole in the region; although the path of water movementis divided into two branches, with Zolal spring water entering a narrower fault channel. In the Zolal spring pathway, a siphon-shaped reservoir is formed where muddy rainwatersettles, so that the water from this spring is clear but hashigher concentrations of all ions analyzed here than Keder spring water.

Void Hunting

Karst environments are characterized by voids, i.e. sinkholes and conduits of varying size that arise from the active dissolution of carbonate rock by acidic groundwater. These voids, whether air-, water-, or soil-filled, can be difficult to image using near-surface geophysical methods due to the limited investigation depths of most active-source methods. In addition, due to the significant effort it takes to collect active-source data, investigators are often unable to monitor spatio-temporal variations in the subsurface. The ability to detect, image, and monitor subsurface voids improves the understanding of processes that create and transform voids, a vitally important insight across a variety of scientifc disciplines and engineering applications, including hydrogeology, geotechnical engineering, planetary science and even issues of national security. Using a 54-element nodal array (1C and 3C sensors), I image the subsurface of the USF GeoPark with ambient noise surface wave tomography. I also use complementary active-source geophysical datasets (e.g. 2D ERT) collected at the GeoPark to constrain and/or validate the tomography results. I address two research questions with this study: (1) How do ambient seismic methods complement active-source near-surface methods? (2) Can ambient noise tomography resolve voids in the karst environment? In this thesis, I discuss my answers to these questions and present the current state of surface wave methods in the karst environment, including the feasibility for utilizing ambient noise methods to monitor spatio-temporal changes in sinkhole and conduit formation. In addition to the ability to use seismic methods for temporal monitoring, ambient noise provides lower frequencies than what are achievable with active-source seismic methods. Using frequencies from 5-28 Hz, ambient noise tomography is able to image deeper into the subsurface (up to 100 m at 5 Hz) than previous active-source seismic studies at the GeoPark field site. This study yields a more robust and simple method to image voids in covered karst environments and a long-term installation of ambient seismic nodes enables future investigations of spatio-temporal variations in void structures.

A Combined Morphological and Molecular Evolutionary Analysis of Karst-Environment Adaptation for the Genus Urophysa (Ranunculaceae)

The karst environment is characterized by low soil water content, periodic water deficiency, and poor nutrient availability, which provides an ideal natural laboratory for studying the adaptive evolution of its inhabitants. However, how species adapt to such a special karst environment remains poorly understood. Here, transcriptome sequences of two Urophysa species (Urophysa rockii and Urophysa henryi), which are Chinese endemics with karst-specific distribution, and allied species in Semiaquilegia and Aquilegia (living in non-karst habitat) were collected. Single-copy genes (SCGs) were extracted to perform the phylogenetic analysis using concatenation and coalescent methods. Positively selected genes (PSGs) and clusters of paralogous genes (Mul_genes) were detected and subsequently used to conduct gene function annotation. We filtered 2,271 SCGs and the coalescent analysis revealed that 1,930 SCGs shared the same tree topology, which was consistent with the topology detected from the concatenated tree. Total of 335 PSGs and 243 Mul_genes were detected, and many were enriched in stress and stimulus resistance, transmembrane transport, cellular ion homeostasis, calcium ion transport, calcium signaling regulation, and water retention. Both molecular and morphological evidences indicated that Urophysa species evolved complex strategies for adapting to hostile karst environments. Our findings will contribute to a new understanding of genetic and phenotypic adaptive mechanisms of karst adaptation in plants.

Mesofauna at the Soil-Scree Interface in a Deep Karst Environment

The community patterns of Collembola (Hexapoda) were studied at two sites along a microclimatically inversed scree slope in a deep karst valley in the Western Carpathians, Slovakia, in warm and cold periods of the year, respectively. Significantly lower average temperatures in the scree profile were noted at the gorge bottom in both periods, meaning that the site in the lower part of the scree, near the bank of creek, was considerably colder and wetter compared to the warmer and drier site at upper part of the scree slope. Relatively high diversity of Collembola was observed at two fieldwork scree sites, where cold-adapted species, considered climatic relicts, showed considerable abundance. The gorge bottom, with a cold and wet microclimate and high carbon content even in the deeper MSS horizons, provided suitable environmental conditions for numerous psychrophilic and subterranean species. Ecological groups such as trogloxenes and subtroglophiles showed decreasing trends of abundance with depth, in contrast to eutroglophiles and a troglobiont showing an opposite distributional pattern at scree sites in both periods. Our study documented that in terms of soil and subterranean mesofauna, colluvial screes of deep karst gorges represent (1) a transition zone between the surface and the deep subterranean environment, and (2) important climate change refugia.

The reference genome and transcriptome of the limestone langur, Trachypithecus leucocephalus, reveal expansion of genes related to alkali tolerance

Background Trachypithecus leucocephalus, the white-headed langur, is a critically endangered primate that is endemic to the karst mountains in the southern Guangxi province of China. Studying the genomic and transcriptomic mechanisms underlying its local adaptation could help explain its persistence within a highly specialized ecological niche. Results In this study, we used PacBio sequencing and optical assembly and Hi-C analysis to create a high-quality de novo assembly of the T. leucocephalus genome. Annotation and functional enrichment revealed many genes involved in metabolism, transport, and homeostasis, and almost all of the positively selected genes were related to mineral ion binding. The transcriptomes of 12 tissues from three T. leucocephalus individuals showed that the great majority of genes involved in mineral absorption and calcium signaling were expressed, and their gene families were significantly expanded. For example, FTH1 primarily functions in iron storage and had 20 expanded copies. Conclusions These results increase our understanding of the evolution of alkali tolerance and other traits necessary for the persistence of T. leucocephalus within an ecologically unique limestone karst environment.

A comprehensive examination of the lysine acetylation targets in paper mulberry based on proteomics analyses

Rocky desertification is a bottleneck that reduces ecological and environmental security in karst areas. Paper mulberry, a unique deciduous tree, shows good performance in rocky desertification areas. Its resistance mechanisms are therefore of high interest. In this study, a lysine acetylation proteomics analysis of paper mulberry seedling leaves was conducted in combination with the purification of acetylated protein by high-precision nano LC-MS/MS. We identified a total of 7130 acetylation sites in 3179 proteins. Analysis of the modified sites showed a predominance of nine motifs. Six positively charged residues: lysine (K), arginine (R), and histidine (H), serine (S), threonine (T), and tyrosine (Y) occurred most frequently at the +1 position, phenylalanine (F) was both detected both upstream and downstream of the acetylated lysines; and the sequence logos showed a strong preference for lysine and arginine around acetylated lysines. Functional annotation revealed that the identified enzymes were mainly involved in translation, transcription, ribosomal structure and biological processes, showing that lysine acetylation can regulate various aspects of primary carbon and nitrogen metabolism and secondary metabolism. Acetylated proteins were enriched in the chloroplast, cytoplasm, and nucleus, and many stress response-related proteins were also discovered to be acetylated, including PAL, HSP70, and ERF. HSP70, an important protein involved in plant abiotic and disease stress responses, was identified in paper mulberry, although it is rarely found in woody plants. This may be further examined in research in other plants and could explain the good adaptation of paper mulberry to the karst environment. However, these hypotheses require further verification. Our data can provide a new starting point for the further analysis of the acetylation function in paper mulberry and other plants.