Marine caves are sites of great interest from geomorphological and ecological viewpoints due to their significant environmental variability, being located at the boundary between marine and ...terrestrial domains. Most of the Mediterranean marine caves resulted from karst phenomena which widely affected the carbonate landscapes. At Tremiti Archipelago (southern Adriatic Sea, Italy), the karst activity is widespread, determining, in combination with existing tectonic features and long-term geomorphological evolution, the presence of several marine caves, partly or completely submerged. Two of these marine caves, located at Cala Caffè and Cala Sorrentino (Capraia Island), were considered for a multidisciplinary study focused on their geomorphological, sedimentological, and ecological characterization. These submerged blind-ended caves, located between 19 and 25 m water depth, show morphologies clearly linked to the tectonic-karst geomorphological setting. Superficial sediment samples were analyzed to derive grain size distribution, total carbon and nitrogen, isotopic ratios, living and dead benthic foraminifers, and dead brachiopods; water parameters were also considered. Sediment distribution showed a similar trend in the two caves, with finer textures, higher organic content in the inner stations, and increased biogenic components. Foraminifers showed a faunal change from the outer to the inner sectors associated with the decreasing grain size and the increased organic matter. Differently, the distribution of brachiopods did not display evident patterns; the differences in absolute abundance between the two sites were mainly attributed to the entrance dimensions and the morphology of the two caves, which deeply affected light penetration. This integrated approach demonstrated that geoforms, due to karst and tectonic processes, create small-scale coastal geomorphological habitats, greatly increasing biodiversity.
•Many marine caves developed during the Quaternary in the carbonate bedrock of Tremiti islands.•An integrated study of geomorphology, sediment features, and faunal content was carried out in two marine caves.•Many geomorphological elements were detected in both emerged and submerged sectors.•Foraminifers and brachiopods' distribution is influenced by sediment characteristics and cave geomorphology, respectively.•A multidisciplinary approach is needed for studying and protecting the cave habitats and their biodiversity.
Droughts are recurrent in southwest China due to the fragility and sensitivity of the karst environment. These events have serious impacts on local agricultural output, ecological diversity, and ...social stability. Understanding spatiotemporal variations and driving factors of drought in this area is of extreme importance for effective mitigation measures. The karst areas situated in southwest China were spatially divided into seven sub-regions according to the topography and degree of karst development. Drought indices, including vegetation condition index (VCI), temperature condition index (TCI), vegetation health index (VHI), normalized vegetation water supply index (NVSWI), and temperature vegetation drought index (TVDI), were calculated from MODIS data during 2000 and 2018 for each sub-region, and drought patterns were examined. The results show that droughts were found to be concentrated in sub-regions such as karst basin, karst plateau, karst gorge, and karst depression areas. Furthermore, there were more drought conditions in karst areas than in non-karst areas. In addition, improvements to drought situation in the study period are significant (
p
<0.05), and mitigation areas respectively account for 80.1% (NVSWI), 74.2% (VCI), 74.2% (VHI), 30.1% (TCI) and 33.2% (TVDI) of the study area, while drought expands slightly (<3.4%) in areas undergoing urban construction. Pearson’s correlation coefficients between drought indices and temperature are generally above 0.5 in all sub-regions. However, the correlation coefficients between drought indices and precipitation mostly fall within the range of 0.3–0.4, indicating a weaker correlation. Our explanation for the spatiotemporal patterns of drought is that karst phenomena are the natural basis of drought and agricultural production is one of important driving forces. Positive changes of drought conditions have benefited from efforts to control rocky desertification and restore ecosystems over the past years.
During road construction investments, the key issue affecting the structure’s safety is accurate subsoil recognition. Identifying subsoil variability zones or natural voids can be performed using ...geophysical methods, and ground-penetrating radar (GPR) is recommended for this task as it identifies the location and spatial range karst formations. This paper describes the methodology of acquisition and processing of GPR data for ground recognition for road investment. Additional subsoil research was performed after karst phenomena were identified in the investment area, formations not revealed by geological recognition from earlier studies during the pre-design stage. Mala Ramac CU II radar with a 250 MHz antenna and a Leica DS2000 with 250 and 700 MHz antennas with real-time geopositioning were used to obtain the data. Regarding GPR data postprocessing, we present a method of converting spatial visualization into a point cloud that allows for GPR and geodetic data integration and confrontation. This approach enabled us to determine the locations of control trenches, the results of which were used for material validation, which is necessary to improve the reliability of subsoil recognition. The results showed a high correlation between the recorded GPR signals and the subsoil structure. Additionally, differences in the quality of results for measurements conducted before laying supporting layers with slag and on the completed road structure surface are illustrated.
The derivation of the term "karst" is treated. Three main approaches to the definition of the one are considered: process, phenomenon and the region, where the karst phenomenon is manifested. It is ...noted that karst rocks occupies nearly 30% of continental area, during which the carbonate
karst (in limestone and dolostones) prevails under evaporate karst (in gypsums, anhydrites and salts). The principal karst phenomena are viewed: on the surface (karren, dolines, uvalas, poljes and karst valleys) and underground: caves. Numerous classifications of the types of karst are discussed.
The intermittent karst spring Slanac east of the town of Trogir is a unique karst phenomenon by its appearance at an altitude of 30 m above sea level. This is a consequence of the areal hydrogeology ...and the development of karstification and karst groundwater flow paths from the most recent glaciation to the present. There are at least three factors controlling the discharge of brackish water at such altitudes during the highest groundwater tides: (a) a considerably greater permeability of calcareous rocks lying below the present sea level in comparison to the permeability of the upper parts, (b) the presence of almost pure sea water upstream of a hanging hydrogeological barrier at the spring site at the end of a dry season, (c) ever higher hydraulic resistance to groundwater flow below the hanging hydrogeological barrier due to ever longer siphonal flows and their gradual colmatation.
The underground karst of the Lot and its real importance : speleometric approach.
It sometimes seems that the «speleological » underground domain -natural caves that can be entered by humans -is ...unlimited, but reality is different Even when considering the upper limits of karstification, and taking into account the large number of openings (caves and springs), the total of cave length and surface (as well as volume) is really small compared with the total karstic area of the Lot department (France).
This constatation must lead to a strong protection of the underground karst areas, because it contains added value in social, economic, and cultural affairs.
Il semble parfois que Je domaine souterrain «spéléologique » -cavités naturelles pénétrables par l'homme -est quasi-illimité. Mais la réalité est bien différente. Même en prenant des hypothèses très hautes, et malgré le fait que les ouvertures (grottes, gouffres, exsurgences...) soient en nombre important, le total des longueurs, des surfaces (et donc des volumes), des cavités est extrêmement faible lorsqu'on le rapporte à l'aire karstique globale du département du Lot (France). Ce constat doit venir à l'appui d'une protection très forte du milieu souterrain karstique pénétrable puisqu'à l'inverse celui-ci est porteur de fortes plus-values sociales, économiques, culturelles.
Evaporite karst in Sicily Liguori, V; Manno, G; Mortellaro, D
Environmental geology (Berlin),
2008, Letnik:
53, Številka:
5
Journal Article
Recenzirano
Karst areas are distributed over most of Sicily. The most widespread karst rocks are carbonates, particularly limestones, but karst phenomena can also be seen in evaporites and particularly in salt ...mines. This report provides an overview of evaporite karst in Sicily, along with a “case history” that shows some of the evaporite karst risks to the environment. In the centre and south of Sicily, a thick sequence of Messinian evaporite rocks are subject to dissolution from meteoric and formation waters. In areas where potassium salts and rock salts are being mined, some geomorphologic changes result from the drilling of boreholes and the collapse of underground mines, thus lowering or collapsing the land surface. An example is the old salt mine “Muti-Coffari”, situated in the commune of Cammarata, where there is a modification of the surface flow of the River Platani. Meteoric waters and runoff flow down through a borehole, enter the underground mine cavity and dissolve the salts, and then the resulting brine flows into a branch of the river, making it salty. Field investigations showed the presence of salt along the edges and on the bed of the stream where it comes out of the cave. Therefore, interventions for risk mitigation are necessary since the old mine constitutes a serious danger for damage or collapse of nearby infrastructures, and can lead to degradation of the river ecosystem and the natural environment.
Rock features are important traces of the formation and development of karst surface. On various karren their record is especially rich, revealing to us the many factors that in diverse conditions ...formed the karst surface on various carbonate and other rock.We have tried to present the most characteristic rock features and through them the most important factors and processes in the formation of the karst surface, the methods of studying them, and the most outstanding examples.Forty-nine contributing authors offer a wide spectrum of content and examples of rock forms from many karst regions around the world.The first part of the book offers an orderly-organized survey and description of the most characteristic rock forms and presents the physical and chemical corrosion of rock, biocorrosion, the modeling of rock forms, their detailed morphometrics, and numerous descriptions of individual rock forms. The second part is devoted to various examples of rock forms found around the world from Slovenia through North and South America to Australia and Asia.
Since 1994, karstologists have participated uninterruptedly in the planning and construction of expressways on Slovenia’s karst. The choice of expressway and railway routes must above all respect the ...integrity of the karst landscape and follow recommendations on avoiding major karst surface features and already known caves. Special attention is devoted to the impact of the construction and use of expressways on karst waters. The results of constant research of karst features discovered in the course of the construction of expressways have enriched our knowledge of the natural and cultural heritage and deepened our karstological knowledge. They also represent starting points for planning life on karst surfaces and the protection of karst. The book is intended for karstologists, experts from the field of earth sciences, engineering geologists, planners of traffic routes, students, nature protectionists, planners in administrative units, managers of karst water resources, waterworks, tourist caves, etc.
This work aims at presenting the geographical characterization of the Cordisburgo karst region, in the State of Minas Gerais, Brazil, by applying the consolidated concepts of the classi-ical karst ...adapted to the reality of the intertropical karst. The characterization of the karst in the region, led to an explor-atory mapping of the main karst features using the methodol-ogy proposed by the Commission of Karst Phenomena of the French National Geography Committee, adapted by Kohler. The choice of this methodology was made on grounds that the existence of many Dinaric and Intertropical Karst maps fa-cilitates comparative analysis. As a result of this study, a map summarized the distribution of the karst features for the first time in this region, providing relevant information for the geoenvironmental compartmentation of the Cordisburgo area and important subsides for the sustainable management of that region. Due to its geological, geomorphological, hydrological and biogeographical characteristics, karst in this region is an expressive example of the Brazilian intertropical karst whose superficial and subterraneous evolution must be understood as a complex phenomenon. There is little research on the Lagoa do Jacare Formation. Thus, it is premature to state that the karst in Cordisburgo presents a low karstification rate in its entire carbonatic pack. Studies on the magnitude and the direction of underground water are still insufficient, however.
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