Potential leakage paths at the dams constructed on karst terrains in Iran

Water leakage has been reported from several dams constructed on karst terrains in Iran. In this study the main reasons for dam leakage were identified by studying ten examples, the Lar, Kowsar, Seymareh, Tangab, and Shah-Ghasem dams with considerable leakage, and the Karun I, Karun III, Karun IV, Salman-Farsi, and Marun dams with negligible leakage. The “Potential Leakage Passage (PLP)” is defined as those parts of a karst aquifer which transfer reservoir water to downstream. The most important control on leakage is in the narrowest part of the PLP, the “bottleneck” that depends mainly on the geological settings. At the dams with negligible leakage, sealing of the PLPs was found to be technologically and economically feasible by connecting all the edges of grout curtain to the natural impermeable barriers. In the cases of dams with considerable leakage, wider PLPs were not completely sealed and the installed grout curtain did not fully connect to the impermeable rock. To reduce the risk of leakage and inform effective design of grout curtains, the characteristics of the PLP should be determined during the initial stage of dam studies, and incorporate geological and hydrogeological information in the ground model. This study highlights the significant risk of engineering project failures that can occur if hydrogeological conditions are not properly assessed, understood and managed early in development of dam location, design and construction.

GIS-Based Relief Compartment Mapping of Fluvio-Karst Landscape in Central Brazilian Highlands

The present study describes the preliminary findings of a research project aiming at creating a knowledge-base for the protection of caves heritage at Rio Vermelho preservation area in the central Brazilian highlands. A GIS-based relief compartment mapping was conducted using readily available data (e.g., satellite images, geological, and cave location maps). Four resultant geomorphological domains were identified, including (i) lowlands (282 km2) with a baselevel in silicates and carbonates, (ii) the karst terrains (994 km2) which were developed in carbonates trapped by siltstone lenses, (iii) the talus (1483 km2) having colluvial and alluvial units deposited by the escarpment retreat (Urucuia Formation) and (iv) the highlands (1143.7 km2) developed over the sandstone of the Urucuia Group. The intersection of landform and geological maps resulted in delineating two abrupt contacts, the first between lowland and karst terrains and the second between the talus and highlands that formed canyon escarpment. For sustainability perspective, this study proposed two types of cave systems in the region as superior/vadose (top-bottom) that collect floods from hillslopes and deep Epigene fluvial-karst (bottom-up).

ОЦІНКА ВПЛИВУ ФАКТОРІВ УРБАНІЗАЦІЇ НА НЕБЕЗПЕКУ АКТИВІЗАЦІЇ КАР-СТОВИХ ПРОЦЕСІВ У РЕГІОНАХ УКРАЇНИ

The article presents the analysis of the exogenous geological process activation hazards, namely karst, in the conditions of urbanization processes. The scale of geoecological problems is shown to be directly or indirectly determined by the scale of urbanization. The relevance of the research is associated with the study of the nature of changes in the expansion of karst rocks in regions with different levels of urbanization in the period 2001 – 2020. The main aim is to analyze the hazards of karst development in relation with the factors of urbanization processes in the regions of Ukraine based on the indicator method. The particular characteristics of the impact of urbanized territories on the initiation of natural disasters and geological hazards have been determined. The urbogenic load of the regions was assessed using determined and calculated earlier indicators of ecological and ecological-demographic urbanization. The assessment of the dependence between the hazard indicator of the spread of karst rocks and the indicator of ecological urbanization in the regional context has been carried out. It is shown that in the third part of the regions, the growing hazard levels of karst processes practically coincide with the growth of the ecological urbanization index. A nearly doubling of the area of karst terrains was noted during 2001 – 2020 in all administrative regions. The coefficient of expansion of karst territories for the specified period has been calculated. Four groups of regions were identified according to the increase in karst areas in comparison with the hazards of karst processes and the index of ecological-demographic urbanization. Expansion of open karst areas in the Transcarpathian, Odessa, Rivne, Kherson, Chernivtsi regions was noted. For this group of regions, a tendency to increase the areas of surface karst in accordance with an increase in the values of urbanization indicators has been established. This is due to the exploitation of natural territorial resources, changes in the nature of land use, depletion of vegetation cover, anthropogenic loads on the ground, and imbalances in the interaction of surface and underground waters in urbanized areas. Thus, the Ukraine’s regions with different urbogenic load are differentiated depending on the territorial indicator of the danger of karst terrains, as well as the dynamics of changes in the areas of karst rocks.

Morpho-phylogenetic evidence reveals new species in Rhytismataceae (Rhytismatales, Leotiomycetes, Ascomycota) from Guizhou Province, China

Karst formations represent a unique eco-environment. Research in the microfungi inhabiting this area is limited. During an ongoing survey of ascomycetous microfungi from karst terrains in Guizhou Province, China, we discovered four new species, which are introduced here as Hypoderma paralinderae, Terriera karsti, T. meitanensis and T. sigmoideospora placed in Rhytismataceae, based on phylogenetic analyses and morphological characters. Molecular analyses, based on concatenated LSU-ITS-mtSSU sequence data, were used to infer phylogenetic affinities. Detail descriptions and comprehensive illustrations of these new taxa are provided and relationships with the allied species are discussed, based on comparative morphology and molecular data.

The fauna of caves and other subter-ranean habitats of North Carolina, USA

Over 1,500 caves have been documented in North Carolina, however, cave fauna in the Blue Ridge Mountains and Piedmont regions of North Carolina have been overlooked historically compared to the cave-rich karst terrains in the Appalachian Valley and Ridge and Interior Low Plateau to the west. Here, we provide the first comprehensive faunal list of caves and other subterranean habitats in the state based on over 40 years of periodic surveys and compilation of literature, biodiversity databases, and museum records. We report 475 occurrences from 127 caves, springs, and wells in 29 counties, representing 5 phyla, 17 classes, 43 orders, 90 families, 124 genera, and at least 164 species. Vertebrate fauna comprised 32 species, including 4 fishes, 9 salamanders, 1 lizard, 4 snakes, 2 birds, and 12 mammals (8 bats). Diverse invertebrate groups included spiders (11 families and 18 genera), springtails (7 families and 9 genera), segmented worms (3 families and 8 genera), and snails (6 families and 9 genera). At least 25 taxa are troglobites/stygobites (cave obligates), including 5 species of cave flatworms, 5 cave springtails, and 5 cave amphipods. Most troglobitic/stygobitic fauna documented in this study are endemic to North Carolina. Counties with the greatest cave biodiversity include Rutherford, McDowell, Swain, Henderson, Polk, and Avery counties. Over 20 species documented are of conservation concern, including 14 troglobites and 3 federally-listed bats. Although not as diverse as adjacent states, caves and other subterranean habitats in North Carolina support a diverse community of invertebrates and vertebrates. Our review serves as a base line for future cave biological surveys in the state and highlights the importance of subterranean habitats for North Carolina biodiversity.

The significance of karst areas in European national parks and geoparks

Karst terrains have varied abiotic and biotic values. However, due to their unfavourable conditions for human settling, they are relatively sparsely populated areas. Thus, karst terrains merit and are suitable for nature protection. In this paper, partly or mostly karstic European national parks (NP) and geoparks (GP) are studied. We compiled a dataset based on official information and internet sources, and analysed NPs and GPs by location, morphology and timeline. Nowadays, there are 106 partly or mostly karstic NPs in Europe, that means 23% of all NPs. Many of the karst terrains became protected before the terms of geotourism and geopark came into being. 49% of all GPs contain karst terrains, which means that karsts are key issues in the study of geoheritage and geotourism. Tourism into karstic NPs and GPs can be considered sensu lato geotourism, since tourists travelling to these locations generally visit caves, gorges, travertine lakes and other karst features. Adventure tourism is also significant in karstic NPs and GPs. The most popular NPs host several millions of visitors a year, that implies economic benefits, but also poses environmental problems, thus certain parks already reached their carrying capacity, while other parks plan to increase their visitor numbers.