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1
Jaquet, O., P. Siegel, G. Klubertanz e H. Benabderrhamane. "Stochastic discrete model of karstic networks". Advances in Water Resources 27, n. 7 (luglio 2004): 751–60. http://dx.doi.org/10.1016/j.advwatres.2004.03.007.
2
Somaratne, Nara. "Karst Conduit Networks, Connectivity and Recharge Dynamics of a Sinkhole". Environment and Natural Resources Research 7, n. 3 (21 settembre 2017): 70. http://dx.doi.org/10.5539/enrr.v7n3p70.
Abstract (sommario):
Management of karst aquifers is often limited by a lack of understanding of recharge and flow dynamics. This article presents the identification of conduit networks and the connectivity, dynamic nature of recharge and inherent uncertainties in recharge assessment in karstic settings. The study was carried out at two large sinkholes located in the Poocher Swamp fresh water lens, south east of South Australia. Point recharge to the sinkholes was calculated using stream flow data at gauging stations and water balance of the swamp. Conduit system and their interconnectivity in the vicinity of sinkholes were characterized by the use of transient electromagnetic survey (TEM) to identify high potential porosity zones of the aquifer. Resistivity data were used to estimate aquifer porosities using Archie’s law. Recharge response to the karstic aquifer was monitored using four monitoring wells located at various distances from sinkholes. Measurements were taken during recharge and recession phases. Four dynamic stages of water level rise and fall were observed in response to filling of conduit zones, transmission and possible effects of entrapped air pressure within conduits. Electrical conductivity (EC) profiles were obtained at two stages. These confirmed interconnectivity of conduits, and re-adjustment to ambient groundwater quality following the recharge event. The lower EC water was found in the monitoring well furthest from the sinkholes indicating the complexity of conduit connection and the nature of mixing with ambient groundwater.
3
Cunha, Lúcio. "O Quaternário, a Morfologia Cársica e o Património Ambiental. Exemplos no sector Setentrional do Maciço de Sicó". Estudos do Quaternário / Quaternary Studies, n. 3 (21 dicembre 2000): 111–18. http://dx.doi.org/10.30893/eq.v0i3.40.
Abstract (sommario):
In the main Portuguese calcareous massifs, the karstic process, which led to the formation of unique landforms and landscapes, nowadays considered of high heritage value, was a long and complex process in which the Quaternary represents only a very small part of the time involved.
Considering only the calcareous massifs of the Westem Portuguese Mesocenozoic Border, if we except the calcareous tufas (and especially the largest outcrop, the Tufas of Condeixa) which were formed well into lhe Quaternary, the karstic forms (Karren, dolines, small caves) that developed there therefore being very recent, in the remaining calcareous rocks the karstic process began in the Jurassic period, and was marked by phases of different intensity at the mercy of tectonic changes, and especially of the successive bioclimatic environments registered in the region. 80th in the Calcareous Massif of Extremedura and in the Sicó Massif the Quaternary seems to have been essentially the setting for the exhumation of paleoforms, some pre-cretaceous, others perhaps tertiary, a1 the same time as a karstic retouching of the calcareous surfaces thus uncovered was taking place.
In spite of this, the most spectacular Landforms, those which have an incontestable heritage value and often correspond to the best known image or these massifs, have the indelible mark of the fluvio-karstic and karstic processes that developed in the Qunternary.
Following the raising of the massifs, and depending on the sandstone coverings progressively mobilized since cretaceous times, which at the beginning of the Quaternary still had, if not a continuous nature, at least larger and thicker extension than the ice remains that can be seen today, conditions were created for the development of the networks of rivers responsible for spectacular canyons, such as, in the case of Sicó, the canyons of Poios, Vale das Buracas and Vale da Grota. Other small canyons, perhaps more worthy of the name, given the almost absolute verticality of their sides, as is the case of the canyon of Rio dos Mouros which was only one of the reasons for the establishment of the Roman city of Conimbriga, despite being perhaps more recent,were born for the same reasons.
An important part of the geological interest of these fluvio-karstic canyons arises from the shape of their sides, and especially from the «buracas», shapes of surface karst which seem to be linked to processes of frost shattering and dissolution under the action of cold climates. Short, almost vertical sectors (the «penas»), openings under rock (the «buracas») and debris of various origins are, without a shadow of doubt, quaternary marks on the sides of the fluvio-karstic canyons and other scarped slopes which contribute a great deal to the valorization of the landscape.
The same is true of formations of two other types, authentic signatures of karstic shaping: the karren, responsible for the «stony desert»)with which classic karst is identified, and the caves which are valuable in themselves because of the beauty they enclose, the challenges they lay down and also, particularly, because of their importance in the process of water circulation and storage. In this case, it was also in the
Quaternary that the responsible processes evolved, for the integral sculpture of many karren formations as for the finishing touches seen in them, this was the time that permitted the final restructuring of the network of galleries wl1ich lay out lhe hydrological functioning of the karst of today.
This article discusses the importance of the processes that took place during the Quaternary in the
construction of the karstic landscape, with particular influence on the formations which, for their genetic specificity, spectacular nature and singularity represent more in terms of environmental heritage.
4
Escobar, Renato Gutierrez, Deane Roehl, Franco Borges Quadros e Caroline L. Cazarin. "Stochastic modelling of karstic networks of Potiguar Basin, Brazil". Advances in Water Resources 156 (ottobre 2021): 104026. http://dx.doi.org/10.1016/j.advwatres.2021.104026.
5
Borghi, Andrea, Philippe Renard e Sandra Jenni. "A pseudo-genetic stochastic model to generate karstic networks". Journal of Hydrology 414-415 (gennaio 2012): 516–29. http://dx.doi.org/10.1016/j.jhydrol.2011.11.032.
6
PETROVIĆ, Aleksandar S., Jelena ĆALIĆ e Vojkan GAJOVIĆ. "Paleodrainage network reconstruction on Miroč Mt. (Eastern Serbia)". Revista de Geomorfologie 18, n. 1 (14 novembre 2016): 69–76. http://dx.doi.org/10.21094/rg.2016.119.
Abstract (sommario):
The paper represents a geomorphological study related to the transitional forms between fluvial and karstic process. Karst areas of eastern Serbia are distributed in a large number of relatively isolated segments, and therefore abound in contact karst features. In many cases, central parts of karst areas, away from the contacts, host a variety of relict and dry valleys. Morphological analysis of these valleys may reveal the remnants of paleodrainage networks and help to reconstruct the morphological evolution of the area. This is a case study of the karst of Miroč Mt. in north-eastern Serbia, where geomorphological analysis and relief visualization using the Geomorphological Information System enabled the detection of paleodrainage directions and patterns in the vicinity of the Danube Gorge. Three paleo-river systems were detected, the largest of which is that of the Suva Reka (51 km2).
7
Sartégou, Amandine, Didier L. Bourlès, Pierre-Henri Blard, Régis Braucher, Bouchaib Tibari, Laurent Zimmermann, Laëtitia Leanni, Georges Aumaître e Karim Keddadouche. "Deciphering landscape evolution with karstic networks: A Pyrenean case study". Quaternary Geochronology 43 (febbraio 2018): 12–29. http://dx.doi.org/10.1016/j.quageo.2017.09.005.
8
de Rooij, Rob, e Wendy Graham. "Generation of complex karstic conduit networks with a hydrochemical model". Water Resources Research 53, n. 8 (agosto 2017): 6993–7011. http://dx.doi.org/10.1002/2017wr020768.
9
Tamburini, Andrea, e Marco Menichetti. "Groundwater Circulation in Fractured and Karstic Aquifers of the Umbria-Marche Apennine". Water 12, n. 4 (7 aprile 2020): 1039. http://dx.doi.org/10.3390/w12041039.
Abstract (sommario):
The Umbria-Marche Apennine has a large number of springs that drain water stored in carbonate formations. Spring groundwater constitutes a crucial freshwater resource for many countries, regions, and cities around the world. This study aimed to understand the hydrological mechanisms behind groundwater circulation and their relationship to the structural and stratigraphic settings of specific aquifers. Recession analysis and time series analysis were applied to the daily discharge of six springs monitored over eight years. Both analyses indicated the presence of two types of aquifers: aquifer with unimodal behavior and aquifer with bimodal behavior. The first are characterized by two hydrodynamic sub-regimes, in which fracture networks control the baseflow and conduit networks control the quickflow. In contrast, other springs present only one hydrodynamic sub-regime related to fracture network drainage. Time series analysis confirms the results of recession analysis, showing a large memory effect and a large response time, implying the dominance of the baseflow sub-regime. These results indicate that the Maiolica Formation is characterized by a high degree of fracturation and slight karstification, which control infiltration and percolation, whereas the Calcare Massiccio Formation regulates groundwater circulation in the deeper zones of the aquifer, characterized by a high degree of karstification through moderately developed conduit networks.
10
Matislav Majstrović e Hrvoje Olujić. "THE NEUTRAL CONDUCTOR VOLTAGE IN A MEDIUMVOLTAGE NETWORK DURING A GROUND FAULT". Journal of Energy - Energija 57, n. 3 (11 ottobre 2022): 328–49. http://dx.doi.org/10.37798/2008573327.
Abstract (sommario):
Of all the ground faults that can occur in medium-voltage networks from the standpoint of human and equipment safety, the most problematic is a ground fault in a medium-voltage/low-voltage substation. The grounding system of a lowvoltage network is directly connected to the grounding electrode of the substation. Therefore, each increase in the potential of the grounding electrode of the substation is transmitted directly via the neutral conductor into the customer’s installation. For these reasons, in this article a detailed investigation is presented of the problem of determining the neutral conductor voltage in a low-voltage network during a ground fault at the medium-voltage level in a supply substation that is an element of a medium-voltage network with an isolated neutral point (star point). A computer model is presented for the analysis of the neutral conductor voltage in actual distribution networks. Two characteristic distribution networks located on karstic terrain are analyzed. The results obtained are compared to the results of measurements.
11
Guérin, Roger, Jean-Michel Baltassat, Marie Boucher, Konstantinos Chalikakis, Pierre-Yves Galibert, Jean-François Girard, Valérie Plagnes e Rémi Valois. "Geophysical characterisation of karstic networks – Application to the Ouysse system (Poumeyssen, France)". Comptes Rendus Geoscience 341, n. 10-11 (ottobre 2009): 810–17. http://dx.doi.org/10.1016/j.crte.2009.08.005.
12
Vrsalović, Adrijana, Ivo Andrić, Nenad Buzjak e Ognjen Bonacci. "Karst Lake’s Dynamics Analysis as a Tool for Aquifer Characterisation at Field Scale, Example of Cryptodepression—Red Lake in Croatia". Water 14, n. 5 (7 marzo 2022): 830. http://dx.doi.org/10.3390/w14050830.
Abstract (sommario):
This paper analyses complex hydrological and hydrogeological properties of a deep karstic lake and its surroundings. Red Lake (Croatia) is a cryptodepression in the karst massif rich in well-developed extreme surface karst forms and underground conduit system. It is interconnected with other close water bodies and offers information on groundwater movement and characteristics. The article analyses hourly data on precipitation and water levels in Red Lake and compares them with data on discharges from near Opačac Spring for a period of five years. Data gaps in the record caused by operational interruptions of the measuring equipment were compensated by the use of neural networks. The study of the hydrodynamics of karst surroundings under recession was conducted by observing the receding water levels and corresponding lake’s volumetry. By isolating recession periods from the record of integral water volume change, some of the common techniques in recession analysis were performed aiming to acquire new knowledge on the hydrogeological regime of the karst system at the field scale. Additionally, spectral analysis was used as another tool of karst system characterisation since it enables the signal decomposition in the frequency domain and detection of dominant flow processes.
13
Sivelle, Vianney, Philippe Renard e David Labat. "Coupling SKS and SWMM to Solve the Inverse Problem Based on Artificial Tracer Tests in Karstic Aquifers". Water 12, n. 4 (16 aprile 2020): 1139. http://dx.doi.org/10.3390/w12041139.
Abstract (sommario):
Artificial tracer tests constitute one of the most powerful tools to investigate solute transport in conduit-dominated karstic aquifers. One can retrieve information about the internal structure of the aquifer directly by a careful analysis of the residence time distribution (RTD). Moreover, recent studies have shown the strong dependence of solute transport in karstic aquifers on boundary conditions. Information from artificial tracer tests leads us to propose a hypothesis about the internal structure of the aquifers and the effect of the boundary conditions (mainly high or low water level). So, a multi-tracer test calibration of a model appeared to be more consistent in identifying the effects of changes to the boundary conditions and to take into consideration their effects on solute transport. In this study, we proposed to run the inverse problem based on artificial tracer tests with a numerical procedure composed of the following three main steps: (1) conduit network geometries were simulated using a pseudo-genetic algorithm; (2) the hypothesis about boundary conditions was imposed in the simulated conduit networks; and (3) flow and solute transport were simulated. Then, using a trial-and-error procedure, the simulated RTDs were compared to the observed RTD on a large range of simulations, allowing identification of the conduit geometries and boundary conditions that better honor the field data. This constitutes a new approach to better constrain inverse problems using a multi-tracer test calibration including transient flow.
14
Rabah, Amal, Manuel Marcoux e David Labat. "Effects of Geometry on Artificial Tracer Dispersion in Synthetic Karst Conduit Networks". Water 15, n. 22 (7 novembre 2023): 3885. http://dx.doi.org/10.3390/w15223885.
Abstract (sommario):
This paper presents the modeling results of tracer test simulations performed using COMSOL Multiphysics (version 6.1), a powerful software for multiphysics simulation. The simulations consist of the propagation of artificial tracers injected into different model configurations. This study is based on computational fluid dynamics (CFDs), which allows us to take into consideration the turbulent regime of the water flow in conduits. The objective of this contribution is to identify the relationship between the tracer dynamics and the geometric parameters of synthetic karstic systems via a systematic investigation of the occurrence of dual-peaked breakthrough curves (BTCs) in tracer tests. Various conduit structures were proposed by modifying five key factors: conduit diameter, presence of pools, connection angle between conduits, distance of the outlet from the inlet, and number of branches. The next step will be to confront these computational experiments with real-world tracer test experiments.
15
Lopes, Juliana A. G., Walter E. Medeiros, Vincenzo La Bruna, Alexandre de Lima, Francisco H. R. Bezerra e Denis José Schiozer. "Advancements towards DFKN modelling: Incorporating fracture enlargement resulting from karstic dissolution in discrete fracture networks". Journal of Petroleum Science and Engineering 209 (febbraio 2022): 109944. http://dx.doi.org/10.1016/j.petrol.2021.109944.
16
Dai, Junfeng, Saeed Rad, Jingxuan Xu, Zupeng Wan, Zitao Li, Linyan Pan e Asfandyar Shahab. "Influence of Karst Reservoir Capacity on Flood in Lijiang Basin Based on Modified HEC-HMS through Soil Moisture Accounting Loss". Atmosphere 13, n. 10 (21 settembre 2022): 1544. http://dx.doi.org/10.3390/atmos13101544.
Abstract (sommario):
The objective of this work was to modify the HEC-HMS flood prediction for the karstic watershed of the Lijiang River, South China, through the quantitative inclusion into the model of the available reservoir capacity of karst (ARCK) as a case study. Due to the complexities caused by hidden drainage networks in karst hydrology, as a new approach, soil moisture accounting loss was used to reflect the ARCK in flood forecasting. The soil moisture loss was analyzed against daily rainfall runoff data across 1.5 years by using an artificial neural network via phyton programming. Through the correlations found among the amounts of soil moisture and river flow fluctuations in response to precipitation and its intervals, coefficients were introduced to the model for output modifications. ARCK analysis revealed that while heavy rainfalls with longer intervals (i.e., 174 mm/2d after 112 days of the dry season) may not cause considerable changes in the river flow magnitude (0.1–0.64 higher owing to high ARCK), relatively small rainfalls with higher frequency (i.e., 83 mm/4d during the wet season) can cause drastic raise of river flow (10–20 times greater at different stations) due to lower ARCK. Soil moisture accounting loss coefficients did enhance the model’s simulated hydrographs accuracy (NSE) up to 16% on average as compared to the initial forecasting via real data. However, the modifications were valid for flood events within a few years from the soil moisture observation period. Our result suggested that the inclusion of ARCK in modeling through soil moisture accounting loss can lead to increased prediction accuracy through consistent monitoring.
17
Lee, Byung-Joo, SungWook Park, Dea-Hong Kim e Young-Karb Song. "Ground Subsidence Caused by the Development of Underground Karstic Networks in Limestone Terrain, Taebag City Korea". Journal of Engineering Geology 26, n. 1 (31 marzo 2016): 63–70. http://dx.doi.org/10.9720/kseg.2016.1.63.
18
Zamora-Luria, Juan Carlos, Jorge Adrián Perera-Burgos, Alfredo González-Calderón, Luis E. Marin Stillman e Rosa Ma Leal-Bautista. "Control of fracture networks on a coastal karstic aquifer: a case study from northeastern Yucatán Peninsula (Mexico)". Hydrogeology Journal 28, n. 8 (1 ottobre 2020): 2765–77. http://dx.doi.org/10.1007/s10040-020-02237-4.
19
Fortin, J., S. Meacham, D. Rissolo, C. Le Maillot e F. Devos. "ENVIRONMENTAL CHALLENGES, TECHNICAL SOLUTIONS AND STANDARD OPERATING PROCEDURES FOR DATA COLLECTION IN PHOTOGRAMMETRIC STUDIES TOWARD A UNIFIED DATABASE OF OBJECTS AND FEATURES IN UNDERWATER CAVES IN MEXICO". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2021 (28 giugno 2021): 659–66. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2021-659-2021.
Abstract (sommario):
Abstract. Mexico’s Yucatan Peninsula is predominantly formed as a karstic terrain on limestone substrates where hundreds of kilometres of now submerged caves constitute extended networks of galleries partially accessible through cenotes, or karstic windows. These cenotes and underwater caves contain numerous objects of great biological, historical, cultural and/or paleontological significance: human and animal remains, ancient Maya artifacts, ancient mines and traces of early human activities. Photogrammetric studies by technical divers allow researchers to access a vast array of data pertaining to objects or features which would otherwise remain inaccessible. However, the harshness of the study environment poses technical acquisition challenges which must be specifically addressed. This paper introduces these environmental challenges, including the geological properties of local caves, bottom composition, ceiling percolation and topography, as well as the intrinsic difficulties linked to the absence of light and the limited time available in an underwater work setting. Technical acquisition solutions, setups and standard operating procedures are then proposed to overcome these challenges. A further consideration is added pertaining to the overall goal of creating a global database for the study objects, thus requiring a unified format for all data: unique identifier, geolocation, minimum resolution, and the like. The authors, focusing on the fieldwork and the data-collection aspect of the photogrammetric study, rather than the data processing and metrological steps, define a new image acquisition methodology built around a compact and replicable setup which will allow the documenting of objects previously out of reach of traditional setups.
20
Visser, Anna-Neva, Moritz F. Lehmann, Hermann Rügner, Fernando Mazo D’Affonseca, Peter Grathwohl, Nia Blackwell, Andreas Kappler e Karsten Osenbrück. "Fate of nitrate during groundwater recharge in a fractured karst aquifer in Southwest Germany". Hydrogeology Journal 29, n. 3 (18 febbraio 2021): 1153–71. http://dx.doi.org/10.1007/s10040-021-02314-2.
Abstract (sommario):
AbstractOver the past decades, fractured and karst groundwater systems have been studied intensively due to their high vulnerability to nitrate (NO3−) contamination, yet nitrogen (N) turnover processes within the recharge area are still poorly understood. This study investigated the role of the karstified recharge area in NO3− transfer and turnover by combining isotopic analysis of NO3− and nitrite (NO2−) with time series data of hydraulic heads and specific electrical conductivity from groundwater monitoring wells and a karstic spring in Germany. A large spatial variability of groundwater NO3− concentrations (0.1–0.8 mM) was observed, which cannot be explained solely by agricultural land use. Natural-abundance N and O isotope measurements of NO3− (δ15N and δ18O) confirm that NO3− derives mainly from manure or fertilizer applications. Fractional N elimination by denitrification is indicated by relatively high δ15N- and δ18O-NO3− values, elevated NO2− concentrations (0.05–0.14 mM), and δ15N-NO2− values that were systematically lower than the corresponding values of δ15N-NO3−. Hydraulic and chemical response patterns of groundwater wells suggest that rain events result in the displacement of water from transient storage compartments such as the epikarst or the fissure network of the phreatic zone. Although O2 levels of the investigated groundwaters were close to saturation, local denitrification might be promoted in microoxic or anoxic niches formed in the ferrous iron-bearing carbonate rock formations. The results revealed that (temporarily) saturated fissure networks in the phreatic zone and the epikarst may play an important role in N turnover during the recharge of fractured aquifers.
21
Fournillon, A., S. Abelard, S. Viseur, B. Arfib e J. Borgomano. "Characterization of karstic networks by automatic extraction of geometrical and topological parameters: comparison between observations and stochastic simulations". Geological Society, London, Special Publications 370, n. 1 (2012): 247–64. http://dx.doi.org/10.1144/sp370.8.
22
Sartégou, Amandine, Didier L. Bourlès, Pierre-Henri Blard, Régis Braucher, Bouchaib Tibari, Laurent Zimmermann, Laëtitia Leanni, Georges Aumaître e Karim Keddadouche. "Corrigendum to “Deciphering landscape evolution with karstic networks: A Pyrenean case study” [Quat. Geochronol. 43 (2018) 12–29]". Quaternary Geochronology 57 (aprile 2020): 101050. http://dx.doi.org/10.1016/j.quageo.2019.101050.
23
Fischer, P., A. Jardani e N. Lecoq. "Hydraulic tomography of discrete networks of conduits and fractures in a karstic aquifer by using a deterministic inversion algorithm". Advances in Water Resources 112 (febbraio 2018): 83–94. http://dx.doi.org/10.1016/j.advwatres.2017.11.029.
24
Fischer, P., A. Jardani, M. Cardiff, N. Lecoq e H. Jourde. "Hydraulic analysis of harmonic pumping tests in frequency and time domains for identifying the conduits networks in a karstic aquifer". Journal of Hydrology 559 (aprile 2018): 1039–53. http://dx.doi.org/10.1016/j.jhydrol.2018.03.010.
25
Τσουκαλάς, Ν., e Κ. Παπαδοπούλου - Βρυνιώτη. "THE KARST IN ANO VLASSIA ACHAIA (GREECE) AND THE CONTRIBUTION OF OLONOS -PINDOS GEOTECTONIC UNIT ON ITS FORMATION". Bulletin of the Geological Society of Greece 36, n. 2 (23 luglio 2018): 1068. http://dx.doi.org/10.12681/bgsg.16910.
Abstract (sommario):
The study area includes the Selinous river hydrologie basin on East Erimanthos (Olonos) Mountain, to close to Ano Vlassia village (N. Péloponnèse - Greece). It is formed at an altitude between 700 - 2.169 m and occ 'Dies an area 30 Km2. It belongs to the Olonos - Pindos geotectonic unit, which characterized by lithostratigraphic unevenness, intense folds, successive thrusts with NE - SW directions and transverse faults. Lithostratigraphic and tectonic conditions are accountable for a directed karst development with many karstic basic planes. The above research includes systematic survey in all karstic formations that were observed. Karrens, kluft karrens, shallow dolines and dry karst valleys are developed on the surface. Furthermore, an underground formation was found and composed by caves, gulfs and an underground karstic river. Above 25 karstic fountainheads were observed which gush from the limestones with a 100 m3/h (summer) maximum supply. The imperfect development of surface karst, the good development of underground karst, karstic fountainheads, hydnlogical network and vert, allow for the studied area to be classified to the Transitional type of karst Dy Cvijic (1926) or to Halbkarst by Grund (1903).
26
Namous, Mustapha, Mohammed Hssaisoune, Biswajeet Pradhan, Chang-Wook Lee, Abdullah Alamri, Abdenbi Elaloui, Mohamed Edahbi et al. "Spatial Prediction of Groundwater Potentiality in Large Semi-Arid and Karstic Mountainous Region Using Machine Learning Models". Water 13, n. 16 (19 agosto 2021): 2273. http://dx.doi.org/10.3390/w13162273.
Abstract (sommario):
The drinking and irrigation water scarcity is a major global issue, particularly in arid and semi-arid zones. In rural areas, groundwater could be used as an alternative and additional water supply source in order to reduce human suffering in terms of water scarcity. In this context, the purpose of the present study is to facilitate groundwater potentiality mapping via spatial-modelling techniques, individual and ensemble machine-learning models. Random forest (RF), logistic regression (LR), decision tree (DT) and artificial neural networks (ANNs) are the main algorithms used in this study. The preparation of groundwater potentiality maps was assembled into 11 ensembles of models. Overall, about 374 groundwater springs was identified and inventoried in the mountain area. The spring inventory data was randomly divided into training (75%) and testing (25%) datasets. Twenty-four groundwater influencing factors (GIFs) were selected based on a multicollinearity test and the information gain calculation. The results of the groundwater potentiality mapping were validated using statistical measures and the receiver operating characteristic curve (ROC) method. Finally, a ranking of the 15 models was achieved with the prioritization rank method using the compound factor (CF) method. The ensembles of models are the most stable and suitable for groundwater potentiality mapping in mountainous aquifers compared to individual models based on success and prediction rate. The most efficient model using the area under the curve validation method is the RF-LR-DT-ANN ensemble of models. Moreover, the results of the prioritization rank indicate that the best models are the RF-DT and RF-LR-DT ensembles of models.
27
Petrovic, Aleksandar, e Ratomir Veselinovic. "The genesis and evolution of uvalas in Gajina mlaka paleovalley on the Kucaj mountains". Glasnik Srpskog geografskog drustva 92, n. 1 (2012): 91–104. http://dx.doi.org/10.2298/gsgd1201091p.
Abstract (sommario):
The evolution of Gajina mlaka paleovalley from pre-karstic to current phase reveals the complexity of process of transformation of valleys in karst and formation of fluviokarst uvalas. The creation of river network and formation of the valley of Gajina mlaka are related to successive withdrawal of the Pontiac Sea. Predominance of karstic process over fluvial causes the transformation of fluvial morphology into karstic. The degree of transformation depends on relationship of the intensity between these two opposed processes. Karstification covers all parts of Gajina mlaka valley which are built in karst. Riverbeds are almost completely transformed and dolines are formed along them. In the parts of valleys with more significant lithologic differences, more complex tectonic relationships and different pre-karstic fluvial morphology, larger forms of relief are created by karstic process and they are called uvalas. According to the presented method of genesis and evolution of uvalas it can be concluded that they are clearly morphologically and genetically individualized karst landforms, which negates some contemporary opinions that exclude both the term and form uvala as karstic element of relief.
28
Papadopoulou-Vrynioti, Kyriaki, e Isidoros Kampolis. "The “Selinitsa-Drakos” coastal karstic system in the Messinian Mani Peninsula (southwestern Greece) in relation to the terrestrial geoenvironment". Geologica Balcanica 40, n. 1-3 (dicembre 2011): 75–83. http://dx.doi.org/10.52321/geolbalc.40.1-3.75.
Abstract (sommario):
The studied coastal karstic system comprises “Selinitsa” Cave and “Drakos” Underground River. It is located in southwestern Greece across the western coastline of the Messinian Mani Peninsula. It is developed into limestones of Upper Senonian to Upper Eocene age belonging to the Mani geotectonic unit. “Selinitsa” is mainly developed above the sea level, whereas “Drakos” is under water down to -48 m. These two caves are now connected through a 28-m long narrow passage at depth of -28 m, thus creating a united karstic system. Both caves were initially separate and terrestrial. Today, the majority of cave passages of “Selinitsa” are terrestrial. In “Senitsa-Drakos” karstic system, sequential karstification base levels have been identified. These levels determined the karstic system development. “Selinitsa” passages are phreatic and vadose, whereas “Drakos” passages are only phreatic, acting as lifting tubes. The passage network of both caves presents dentritic pattern and comprises the hydrological equivalent of the surface drainage network. To the east of the karstic system, karst margin plains are present comprising karstified tectonic terraces, whereas above the “Selinitsa-Drakos” system manmade terraces exist for agricultural purposes.
29
Papadopoulou-Vrynioti, Kyriaki, e Isidoros Kampolis. "The “Selinitsa-Drakos” coastal karstic system in the Messinian Mani Peninsula (southwestern Greece) in relation to the terrestrial geoenvironment". Geologica Balcanica 40, n. 1-3 (dicembre 2011): 75–83. http://dx.doi.org/10.52321/geolballc.40.1-3.75.
Abstract (sommario):
The studied coastal karstic system comprises “Selinitsa” Cave and “Drakos” Underground River. It is located in southwestern Greece across the western coastline of the Messinian Mani Peninsula. It is developed into limestones of Upper Senonian to Upper Eocene age belonging to the Mani geotectonic unit. “Selinitsa” is mainly developed above the sea level, whereas “Drakos” is under water down to -48 m. These two caves are now connected through a 28-m long narrow passage at depth of -28 m, thus creating a united karstic system. Both caves were initially separate and terrestrial. Today, the majority of cave passages of “Selinitsa” are terrestrial. In “Senitsa-Drakos” karstic system, sequential karstification base levels have been identified. These levels determined the karstic system development. “Selinitsa” passages are phreatic and vadose, whereas “Drakos” passages are only phreatic, acting as lifting tubes. The passage network of both caves presents dentritic pattern and comprises the hydrological equivalent of the surface drainage network. To the east of the karstic system, karst margin plains are present comprising karstified tectonic terraces, whereas above the “Selinitsa-Drakos” system manmade terraces exist for agricultural purposes.
30
Alili, L., A. Boukdir, M. R. Maslouhi e H. Ikhmerdi. "Karst groundwater vulnerability mapping to the pollution: Case of Dir springs located between EL KSIBA and Ouaoumana (High Atlas, Morocco)". E3S Web of Conferences 37 (2018): 01004. http://dx.doi.org/10.1051/e3sconf/20183701004.
Abstract (sommario):
The study area is located in the north of the province of Beni Mellal, it covers the Piedmont of the high Atlas between El Ksiba and Ouaoumana. It is characterized by a poorly developed hydrographic network and the presence of very important karstic forms. These forms condition the rapid infiltration to the karstic springs are the subject of this study. In this work we presented a method of mapping the vulnerability to pollution of Karstic springs located between El Ksiba and Ouaoumana. To do this, we have introduced a vulnerability index called F which takes into account four parameters (EPIK): Development of the Epikarst, importance of the protective cover, infiltration conditions and development of the Karst network. The overlay of the thematic maps of these parameters through a GIS software (ArcGIS) gave us a map of the vulnerability to contamination on the whole hydrogeological basin of the springs.
31
Feo, Alessandra, Andrea Zanini, Emma Petrella, Rebeca Hernàndez-Diaz e Fulvio Celico. "Analysis of the Saltwater Wedge in a Coastal Karst Aquifer with a Double Conduit Network, Numerical Simulations and Sensitivity Analysis". Water 11, n. 11 (5 novembre 2019): 2311. http://dx.doi.org/10.3390/w11112311.
Abstract (sommario):
We investigate the long-distance salinity in a dual permeability coastal karst aquifer with a double conduit network using a three-dimensional variable-density groundwater flow and multispecies transport SEAWAT model. Sensitivity analyses were used to evaluate the impact of the parameters and boundary conditions on the modeling saltwater wedge in a karstic aquifer situated in the Cuban land territory, including hydraulic conductivity, vertical anisotropy and salinity concentration; both in the conduits network and the fractured medium. These analyses indicated that hydraulic conductivity of the fractured medium and salt concentration were the ones that have a stronger effect on saltwater intrusion in a karstic aquifer. We also show results of the three-dimensional numerical simulations on groundwater salinity for different scenarios with the variabilities of the important parameters and compare results with electric conductivity profiles measured in a well.
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Josnin, Jean-Yves, Séverin Pistre e Claude Drogue. "Modélisation d'un système karstique complexe (bassin de St-Chaptes, Gard, France) : un outil de synthèse des données géologiques et hydrogéologiques". Canadian Journal of Earth Sciences 37, n. 10 (1 ottobre 2000): 1425–45. http://dx.doi.org/10.1139/e00-056.
Abstract (sommario):
Numerous software packages allow the efficient modeling of the hydrodynamic behaviour of aquifers in continuous media. To study pressure transfer in discontinuous media like karsts, the black-box models are restrictive and the models that consider discrete conduit networks are unsuitable for reservoir scale. We show that the utilization of a continuous media model can lead to useful results, even in the case of complex systems, but needs to be adapted to karst specificity. The problem is approached by studying a hydrogeological system located in the Mediterranean Languedoc region: the St-Chaptes basin. This system consists of three superposed aquifers included in four different stratigraphic series. The main aquifer is a karst formation in contact with two other karst formations that belong to different hydrogeologic systems. Considering geological data in addition to hydrological data and with the hypothesis of a relative homogenization of the karst's hydraulic behaviour on a large spatial scale for daily to monthly increments, the model that takes into account the relations with the other aquifers allows (i) a preliminary identification of the main heterogeneities inside the reservoir; (ii) the location of barriers and low-permeability zones that isolate some parts of the aquifer; (iii) the observation of a curious behaviour of the piezometric levels in the confined zones of the aquifer; and (iv) the characterization of the exchanges with the other low-volume but existing aquifers.
33
Ong, Poh Yee, e Siti Nur Fathiyah Jamaludin. "Fracture Network Analysis of Karstified Subis Limestone Build-Up in Niah, Sarawak". Applied Sciences 13, n. 22 (7 novembre 2023): 12110. http://dx.doi.org/10.3390/app132212110.
Abstract (sommario):
Understanding complex carbonate fracture networks and karstification at various geological scales is challenging, especially with limited multi-scale datasets. This paper aims to reduce uncertainty in the fracture architecture of Central Luconia karstified reservoirs by narrowing observational gaps between seismic and well data by using the discrete fracture models of exposed limestone outcrops as analogues for the subsurface carbonate reservoir. An outcrop-based fracture network characterisation of a near-surface paleo-karst at Subis Limestone combined with lineament analysis was conducted to extract fracture parameters. The karst structure was first delineated using a digital elevation map and outcrop examination. Then, topology analysis was performed, following the creation of two-dimensional discrete fracture models. Two main fracture sets oriented northeast–southwest and northwest–southeast and 79 potential dolines were identified. Fracture intersections, northeast–southwest major orientations, and drainage systems highly influenced the karst features. The Subis Limestone fracture model revealed that the highest number of fractures and total length of fractures were concentrated in the northern part of the Subis Limestone build-up (X: 250–350, Y: 150–250) and became denser towards the northwest direction of the outcrop (X: 600–800). The fractures in the Subis paleo-karsts appear isolated, with I-nodes ranging from 0.74 to 0.94. Hence, it is crucial to incorporate matrix porosity into multiple scales of fracture network modelling to improve upscaling and the modelling of fracture–vug networks, as well as to minimise the underestimation of discrete fracture networks in fractured and karstified limestone.
34
Ke, Tingting, Longcang Shu e Xunhong Chen. "Modeling the groundwater recharge in karst aquifers by using a reservoir model". Water Science and Technology 68, n. 2 (1 luglio 2013): 406–12. http://dx.doi.org/10.2166/wst.2013.266.
Abstract (sommario):
The estimation of the groundwater recharge in a karstic system becomes an important challenge due to the great hydrodynamic variability in both time and space. This paper proposes a two reservoir conceptual model to simulate inflow into both the conduit system and the fissure network system based on the analysis of the spring hydrograph. The structure of the model and the governing equations are proposed on the basis of the physical considerations, with the assumption that flow at the outlet of the reservoirs obeys a linear threshold function. The model is applied on the Houzhai karstic underground river basin where it successfully reflects the temporal recharge distribution. The simulated accumulation recharge is 34.29 mm, which is reasonable in relation to the actual rainfall of 92.8 mm. The variations of water volume in two reservoirs represent the storage and transform characteristics of the karst aquifer system. However, this model is particularly well suited to simulate the recharge event after intensive rainfall.
35
An, Guanping, Yanhao Huang, Tao Huang, Yulong Cui e Daoping Peng. "Stochastic simulation and uncertainty analysis of karst conduit network using pyKasso". E3S Web of Conferences 520 (2024): 01015. http://dx.doi.org/10.1051/e3sconf/202452001015.
Abstract (sommario):
Owing to the intrinsic heterogeneity and anisotropy of karst systems, traditional hydrological exploration methods face significant challenges when investigating karst conduit networks. This study employs pyKasso for the stochastic simulation of karst conduit networks in Panzhou City, focusing on uncertainty analysis through local sensitivity analysis and Monte Carlo methods. The simulation process incorporates geological, topographic, and fracture data to create a realistic representation of the karst network. We found that the spatial configuration and characteristics of the karst network are significantly influenced by various input parameters such as fracture parameters, inlets, outlets, and cost ratios. We highlight the minimal influence of fracture densities and the substantial impact of the count of inlets and outlets on crucial network metrics. The results demonstrate the critical role of parameter sensitivity and variability in modeling the intricate karst systems, providing valuable insights for hydrogeological studies and the management of karst water.
36
Lončar, Nina, e Ivana Grcić. "GIS-based analysis of doline density on Miljevci karst plateau (Croatia)". Acta Carsologica 51, n. 1 (20 maggio 2022): 7–17. http://dx.doi.org/10.3986/ac.v51i1.10465.
Abstract (sommario):
The doline density and their spatial distribution analysis is one of the methods used for karst relief morphostructural analysis. We present the results of morphometric features, doline spatial distribution and their relationship on Miljevci karst plateau based on digital elevation model (DEM). Altogether, 286 dolines were mapped in the study area. The doline density analysis has been applied. The results show that the doline spatial distribution is clustered. Two larger areas with densities of 30 and 34 dolines/km2 are determined. Their distribution along the river canyons could indicate the existence of a palaeodrainage network. The strongest link between the doline density and topography is with inclination and vertical relief dissection, whereas the number of dolines decreases with an increase of slope inclination and relative relief. Such distribution confirms the suitability of karstic plateaus without active drainage for doline formation.
37
Vandycke, S., e Y. Quinif. "Recent active faults in Belgian Ardenne revealed in Rochefort Karstic network (Namur Province, Belgium)". Netherlands Journal of Geosciences 80, n. 3-4 (dicembre 2001): 297–304. http://dx.doi.org/10.1017/s0016774600023891.
Abstract (sommario):
AbstractThis paper presents observations of recent faulting activity in the karstic network of the Rochefort Cave (Namur Province, Belgium, Europe). The principal recent tectonic features are bedding planes reactivated as normal faults, neo-formatted normal faults in calcite flowstone, fresh scaling, extensional features, fallen blocks and displacement of karstic tube. The seismo-tectonic aspect is expanded by the presence of fallen blocks where normally the cavity must be very stable and in equilibrium. Three main N 070° fault planes and a minor one affect, at a decimetre scale, the karst features and morphology. The faults are still active because recent fresh scaling and fallen blocks are observable. The breaking of Holocene soda straw stalactites and displacements of artificial features observed since the beginning of the tourist activity, in the last century, also suggest very recent reactivation of these faults. This recent faulting can be correlated to present-day tectonic activity, already evidenced by earthquakes in the neighbouring area. Therefore, karstic caves are favourable sites for the observation and the quantification of recent tectonic activity because they constitute a 3-D framework, protected from erosion. Fault planes with this recent faulting present slickensides. Thus a quantitative analysis in term of stress inversion, with the help of striated faults, has permitted to reconstruct the stress tensor responsible for the brittle deformation. The principal NW-SE extension (σ3 horizontal) is nearly perpendicular to that of the present regional stress as illustrated by the analysis of the last strong regional earthquake (Roermond, The Netherlands) in 1992. During the Meso-Cenozoic, the main stress tectonics recorded in this part of the European platform is similar to the present one with a NE-SW direction of extension.The discrepancy between the regional stress field and the local stress in the Rochefort cave can be the result of the inversion of the σ2 and σ3 axes of the stress ellipsoid due to its symmetry or of a local modification at the ground surface of the crustal stress field as it has been already observed in active zones.
38
Parise, M. "Flood history in the karst environment of Castellana-Grotte (Apulia, southern Italy)". Natural Hazards and Earth System Sciences 3, n. 6 (31 dicembre 2003): 593–604. http://dx.doi.org/10.5194/nhess-3-593-2003.
Abstract (sommario):
Abstract. Karst environments are characterized by peculiar hydrologic features, and in particular by a very limited, if not absent, surface hydrography. Water tends to infiltrate rapidly underground through the complex network of fractures and karstic conduits in the rock mass. However, on the occasion of concentrated rainfall, as well as in case of prolonged precipitation, such network might not be able to allow flowing of large amounts of water, which causes the occurrence of floods. This contribution illustrates the flood history in a classical karst area of Southern Italy, the town of Castellana-Grotte, in Apulia. The oldest part of the town lies at the bottom of a karst valley, which was hit by many flood events in the last centuries. More than twenty of these are here documented, starting from critical analysis of existing publications and documents, integrated with additional historical researches. Aimed at reconstructing the flood history at Castellana-Grotte, the best-documented events are described, together with the main factors, which played a role in distribution and gravity of the related damage. Eventually some engineering works realized during the first decades of the last century, in order to avoid further damage on the occasion of catastrophic floods, are also described.
39
Thorn, Richard, David Drew e Catherine Coxon. "The Hydrology and Caves of the Geevagh and Bricklieve Karsts, Co. Sligo". Irish Geography 23, n. 2 (2 agosto 2016): 120–35. http://dx.doi.org/10.55650/igj.1990.598.
Abstract (sommario):
The paper describes the hydrology, both relict and modern, of the Geevagh and Bricklieve upland karsts in Co. Sligo. The Geevagh karst is characterised by point recharge via sinking streams running off juxtaposed non-carbonate rocks. The flow mechanism in the karst, as determined by water tracing and hydrochemical analysis, is both conduit and fissure and there is extensive cave development. The Bricklieve karst lacks an impermeable cover to concentrate flow and recharge is largely diffuse. Flow in this karst appears to be predominantly through a network of solutionally widened fissures and cave development is limited.
40
Berthelin, Romane, Michael Rinderer, Bartolomé Andreo, Andy Baker, Daniela Kilian, Gabriele Leonhardt, Annette Lotz et al. "A soil moisture monitoring network to characterize karstic recharge and evapotranspiration at five representative sites across the globe". Geoscientific Instrumentation, Methods and Data Systems 9, n. 1 (25 febbraio 2020): 11–23. http://dx.doi.org/10.5194/gi-9-11-2020.
Abstract (sommario):
Abstract. Karst systems are characterized by a high subsurface heterogeneity, and their complex recharge processes are difficult to characterize. Experimental methods to study karst systems mostly focus on analysing the entire aquifer. Despite their important role in recharge processes, the soil and epikarst receive limited attention, and the few available studies were performed at sites of similar latitudes. In this paper, we describe a new monitoring network that allows for the improvement of the understanding of soil and epikarst processes by including different karst systems with different land-cover types in different climate regions. Here, we present preliminary data form the network and elaborate on their potential to answer research questions about the role of soil and epikarst on karstic water flow and storage. The network measures soil moisture at multiple points and depths to understand the partitioning of rainfall into infiltration, evapotranspiration, and groundwater recharge processes. We installed soil moisture probes at five different climate regions: Puerto Rico (tropical), Spain (Mediterranean), the United Kingdom (humid oceanic), Germany (humid mountainous), and Australia (dry semi-arid). At each of the five sites, we defined two 20 m×20 m plots with different land-use types (forest and grassland). At each plot, 15 soil moisture profiles were randomly selected and probes at different depths from the topsoil to the epikarst (in total over 400 soil moisture probes) were installed. Covering the spatio-temporal variability of flow processes through a large number of profiles, our monitoring network will allow researchers to develop a new conceptual understanding of evapotranspiration and groundwater recharge processes in karst regions across different climate regions and land-use types, and this will provide the base for quantitative assessment with physically based modelling approaches in the future.
41
Reinhart, Hilary, Rakhmat Dwi Putra e Muhamad Rifki Rafida. "Karst ecosystem services and their roles in the management of Gunung Sewu UNESCO global geopark". Sustinere: Journal of Environment and Sustainability 7, n. 3 (31 dicembre 2023): 220–33. http://dx.doi.org/10.22515/sustinere.jes.v7i3.349.
Abstract (sommario):
As a member of the Global Geopark Network, Gunung Sewu UNESCO Global Geopark is designed to attract tourists, with a focus on the tourism industry to generate revenue. However, this development triggers environmental pressure on the already fragile karstic ecosystem, necessitating the implementation of mitigation measures. This research aims to employ Karst Ecosystem Services (KESs) as a tool for managing the karst area and the Geopark itself, exploring both the concept and its implementation. Two examples of ecosystem services, scenic and habitat quality, are generated using InVEST tools as the representations of Karst Ecosystem Services. In the Karst of Gunung Sewu, the habitat quality of tree covers, ponds, and caves is threatened by limestone mining, agriculture, and large-scale infrastructure, while the scenic quality is degraded by the presence of construction sites, large statues, and unused or abandoned building. These ecosystem services can contribute to strengthening the Geopark’s pillars through conserving intactness and maintaining energy flow within the habitat for the Geoconservation pillar. For geoeduaction pillar, scenic landscapes provide visual interpretation, and the integrity of landforms supports morphological interpretation. Lastly, habitat and scenic quality can be developed to enhance tourism attraction while maintaining the environment quality for the Sustainable Local Economic Development pillar.
42
He, Guizhen, Mingzhao Yu, Xiang Zhao, Lei Zhang e Lina Shen. "Karst Landscape Governance in the Guilin World Heritage Site, China". Heritage 6, n. 6 (23 maggio 2023): 4492–509. http://dx.doi.org/10.3390/heritage6060237.
Abstract (sommario):
Sustaining karst landscape areas in World Heritage Sites under increasing human pressures and climate change is an emerging challenge. Growing evidence has highlighted the transition from traditional government-oriented regulation to the collaborative governance of different stakeholders in governing karst landscape resources. However, the complexity and dynamics of karst landscape policy and stakeholder networks are poorly understood. This study combined a legislative analysis, network analysis, and public survey to explore effective methods of karst landscape conservation in the Guilin World Heritage Site, China. The policy analysis showed that various national laws and local regulations have been enacted in China, but these regulations often focused on individual aspects of karst–human interactions. The network analysis indicated the complexity and relationship of networks in karst World Heritage Site governance at the national, provincial, and municipal scales. The majority of questionnaire respondents (65–89%) reported a medium and high level of karst landscape governance effectiveness. The insights in the present study may be valuable for other karst World Heritage Sites facing complex challenges, especially in developing countries.
43
Dan, Yong, Liangbiao Lin, Bin Liang, Qingyu Zhang, Yu Yu, Jianwen Cao e Jingrui Li. "Eogenetic Karst Control of Carbonate Reservoirs during a Transient Exposure: A Case Study of the Ordovician Yingshan Formation in the Northern Slope of the Tazhong Uplift, Tarim Basin, China". Minerals 8, n. 8 (9 agosto 2018): 345. http://dx.doi.org/10.3390/min8080345.
Abstract (sommario):
The Tazhong area of the Tarim Basin contains abundant oil and gas resources in Ordovician carbonate rocks, especially in the karst pores and caves of the Yingshan Formation. Research has indicated that the Yingshan Formation underwent a 7–11 Ma exposure during the middle Caledonian Period, resulting in large-scale karst pores and caves. However, the continental freshwater karst model cannot adequately explain the origin and distribution of karst pores and caves. In order to develop a more accurate karst model to guide petroleum exploration in the region, we analyzed the karst morphology, cave development statistics, and paleokarst environments. Karst reservoir characteristics were analyzed on the basis of the following analysis: (1) Karst morphological analyses based on core description and formation micro-imager (FMI) log analyses. The results showed that alveolar-like and Swiss cheese-like solution pores, spongy dissolution zones, pit cenotes, and small continuous karst caves developed in the Yingshan Formation. (2) The statistical analysis of pore and cave characteristics indicated that most of the karst pores and caves developed within 50 m below the unconformity where the average height of these features ranged from 0.1 to 3.0 m and their widths ranged up to 100 m. These pores and caves were commonly filled with gravel, clay, and calcite. Horizontal well and seismic attribute analysis indicated that these pores and caves were distributed over a large area. In plain view, the karst pore-cave system is comprised of cross-linked anastomosing networks of horizontal cave passages. And (3) Cathode luminescence and electron microprobe analyses suggested that clay filling within karst caves was freshwater related, while calcite filling was of seawater origin. Cements within solution pores showed three phases of luminescence, suggesting an alternating freshwater and seawater environment. Based on these characteristics, the karsts of the Yingshan Formation in the Tazhong area are interpreted to be similar to the eogenetic karsts in the Yucatan Peninsula of modern Mexico. Accordingly, this study indicates that the pore-caves of the Yingshan Formation can be subdivided into three sections. Further, the development and filling of these pore-cave sections are interpreted to have formed by eogenetic mixed-water karstification during three phases of relatively stable sea level in a coastal margin environment.
44
Naouadir, Iliass, Abdallah Dridri, Hicham El Asmi, Anaas Marzouki, El Hassane Chellai, Mohammed Ettaki, Amos Frumkin e Ismail Naouadir. "Coupling Field Investigations with the Contribution of Remote Sensing and GIS for the Moroccan Middle Atlas Karst: A Case Study of the El Menzel Causse". Iraqi Geological Journal 56, n. 2A (31 luglio 2023): 19–35. http://dx.doi.org/10.46717/igj.56.2a.2ms-2023-7-11.
Abstract (sommario):
Little work has been done on the processes that control karstic phenomena in the Causse of El Menzel. This carbonate section of the Moroccan tabular Middle Atlas has undergone significant karstification due to favorable conditions that contribute to good karstification potential. Our field and remote sensing results confirm the tectogenetic nature of a set of expressions found in the Causse. The maps produced show good agreement between the structural, fluvial, and karstic network, given that the large NE-SW oriented faults in the sector played an inhibiting role in the triggering of karstic processes during the different phases of the Alpine cycle and neotectonics: on the one hand by the fact of weakening the liasic carbonate series sensitivity to dissolution at faulted zones and on the other hand by guiding the action of the external phenomena causing incision and fluvial erosion, forming a system of valleys which simultaneously coincides with the genesis of the karstic forms found in the Causse of El Menzel.
45
Sanz Pérez, Eugenio, Cristina Fonolla, Ignacio Menéndez Pidal e Pablo Rosas Rodriguez. "Paleohydrogeology of the Karstic System of Fuentetoba Spring (Soria, Spain): An Interdisciplinary Approach". Sustainability 13, n. 13 (28 giugno 2021): 7236. http://dx.doi.org/10.3390/su13137236.
Abstract (sommario):
As a preliminary phase in the conservation and sustainable management of a karst system in Fuentetoba, Soria, Spain, an interdisciplinary study was carried out to determine its hydrogeological evolution. The hydrogeological history of this aquifer system began during the late Miocene, where discharges were driven by paleo-emergences in the moor, and associated conduits were developed under phreatic (or vadose) conditions—for example, the upper syngenetic galleries in the main known karst cave (Majada del Cura cave). Later on, the nearby karstic massifs, a general flattening of the relief, occurred during the Quaternary Period, during which the karstic base level had been in decline. The aquifer flow was then derived and modified towards the Fuentetoba spring from the earliest stages through the galleries of the aforementioned cave. The observations made in this cave indicate the existence of a unique type of hydrogeological organization. The hypogean network is the result of the excavation of the same water flow that has been entrenching and abandoning the vadose regimen toward the free regimen. The dating of the tuffaceous buildings, associated with the emergences, indicates that since almost the Middle Pleistocene, flow lines have converged in the Fuentetoba spring, inducing a high grade of karstification in the saturated zone of the syncline basin. Moreover, a major drainage conduit was developed by dissolution. During the late Upper Pleistocene, an essential component of the groundwater flow had been derived towards the source of the Mazos River spring. Tufa and paleogour datings in caves indicate that the aquifer has undergone different climatic stages during the latest Quaternary and, therefore, different feeding and recharge processes. These tufas and paleogours are interrelated as well, as they are associated with the warm stages during the most recent Quaternary, according to the regional context, when there was less natural recharge. The simulation of the springs’ flow enabled an approximate quantification of the variation in the aquifer’s hydraulic balance during the different climatic stages. For example, during the last glaciation, the natural recharge was impacted by snowmelt and increased by 160%.
46
Qarqori, Kh, M. Rouai, F. Moreau, G. Saracco, O. Dauteuil, D. Hermitte, M. Boualoul e C. Le Carlier de Veslud. "Geoelectrical Tomography Investigating and Modeling of Fractures Network around Bittit Spring (Middle Atlas, Morocco)". International Journal of Geophysics 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/489634.
Abstract (sommario):
Direct current Resistivity (DCR) method was carried out to characterize the hydrogeological connection between the Tabular Middle Atlas (TMA) and the Saïs Basin. The TMA is one of the most important aquifers in northern Morocco that supplies the deep aquifer of the Saïs Basin. Electrical resistivity tomography (ERT) survey was focused on the Bittit area that is one of the most important outlet discharges, and it is representative of the relations between the TMA and the Saïs Basin. The high resolution capabilities of the electrical tomography were used to define the geological draining features in the framework of water paths from the TMA to the karstic springs. The synthetic data were calculated for the similar model expected in field data inversion and inversion result of these synthetic data used as a guide for the interpretation of the inverse data resistivity sections. Joint interpretation of geophysical, geological, structural, and synthetic simulation data allowed identifying a conductive horizontal shallow layer overlying two subvertical families of fractures of NE-SW and NW-SE directions. This result leads to propose hydrological behaviour of water from the Tabular Middle Atlas and the Saïs Basin at the Bittit Spring, which takes into account for both horizontal flows through stratification joints or karst and through subvertical fractures.
47
Le Borgne, François, Michel Treuil, Jean-Louis Joron e Michel Lepiller. "Hydrogeochemical balance sheet of natural and anthropogenic impacts onto Orleans valley karstic network performed with major elements : the “dynamic confinement” model quantification". Bulletin de la Société Géologique de France 177, n. 1 (1 gennaio 2006): 37–50. http://dx.doi.org/10.2113/177.1.37.
Abstract (sommario):
Abstract The Orleans valley aquifer comprises both the alluvia of the Loire river and its underlying calcareous stratum. This aquifer is fed by river recharge, thanks to a substantial karstic network in its calcareous part. The main outlets of the aquifer are the Loiret springs, including the famous “le Bouillon” spring. As a result, entries and exits of Orleans valley watertable make a natural observatory, allowing study of the transit of the chemical species inside the aquifer. Since 1997, this natural observatory has been improved with the installation of 52 piezometers (37 in the alluvial aquifer and 15 in the carbonate aquifer) within an alluvial quarry located in the middle of Orleans valley. Tracer experiments, carried out in this extended observatory, have shown that the porous calcareous and alluvial part of the aquifer constitute a “dynamically confined system”. As a result, the hydrochemical input of the porous domain of the aquifer to the karstic flow must be negligible. The aim of this study is to confirm this theory with the use of major elements as large-scale temporal and spatial tracers of these exchanges. At “le Bouillon” karstic spring, the Na+, K+, Mg2+, Cl− and SO42− concentrations are closely correlated to those of the Loire river if a 3–4 day time lag is considered. This indicates a quasi-conservative transit of these elements in the karst. Conversely, calcite dissolution accompanying the organic matter biodegradation induces significant enrichments in Ca2+, HCO3− and NO3− (mean annual concentrations of which are, respectively, 27.0, 87.8 and 4.9 mg.L−1 in the Loire river and 37.3, 127 et 7.3 mg.L−1 at “le Bouillon” spring). After fertiliser spreading, the alluvial waters are highly enriched in NO3−, Cl−, SO42− (respectively 67.2, 24.0, 57.5 mg.L−1) compared to the Loire river (respectively 5.5, 12.7, 17.5 mg.L−1). The anthropogenic input is insignificant for Na+, of which the average concentration in the alluvial watershed (11.7 mg.L−1) remains close to the Loire river (12.9 mg.L−1). The alluvial watershed is depleted in K+ (1.3 mg.L−1) with respect to the Loire river (3.7 mg.L−1) and correlatively enriched in Mg2+ (17.0 mg.L−1 against 5.0 mg.L−1). High major element concentrations are measured in several calcareous piezometers confirming that vertical flows occur between the alluvial and calcareous parts of the aquifer. Furthermore, enrichment heterogeneity in those two strata is induced by a dynamic redistribution, with no significant leaching of anthropogenic inputs which were previously homogeneously spread. This redistribution is pulsed by ascents of the Loire river, impacts of which on the watershed are clearly identified on Mg/K-Na/K diagrams showing a main K ⇆ Mg exchange between Loire water and clays minerals. Taking into account average K and Mg concentrations in the different parts of Orleans valley’s watershed, the volume of porous aquifer water brought to the karstic network flow mean estimated is 2.4 % of the total volume which transits between the Loire and the “le Bouillon” spring, showing the dynamic confining action of the aquifer porous domain. Taking into account more precisely seasonal river Loire and spring composition variation, these inputs can be more precisely established : 1.6% during winter and 1.2% during summer at “Le Bouillon” spring; 2.4% during winter and 3.9% during summer at “La Pie” spring. But such a weak global contribution of the porous domain accounts for 10% nitrate composition of the karstic springs. Seasonal spring nitrate composition balance is clearly explained by 60% river Loire, 30 % organic matter oxydation – carbonate dissolution and 10% porous domain inputs during winter, and 30% river Loire, 60% organic matter, – carbonate dissolution and 10% porous domain inputs. Same calcium mass balance calculations point out the necessity of CO2 winter complementary input by local rain fall penetrations.
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Fandel, Chloé, Ty Ferré, François Miville, Philippe Renard e Nico Goldscheider. "Improving understanding of groundwater flow in an alpine karst system by reconstructing its geologic history using conduit network model ensembles". Hydrology and Earth System Sciences 27, n. 22 (28 novembre 2023): 4205–15. http://dx.doi.org/10.5194/hess-27-4205-2023.
Abstract (sommario):
Abstract. Reconstructing the geologic history of a karst area can advance understanding of the system's present-day hydrogeologic functioning and help predict the location of unexplored conduits. This study tests competing hypotheses describing past conditions controlling cave formation in an alpine karst catchment, by comparing an ensemble of modeled networks to the observed network map. The catchment, the Gottesacker karst system (Germany and Austria), is drained by three major springs and a paleo-spring and includes the partially explored Hölloch cave, which consists of an active section whose formation is well-understood and an inactive section whose formation is the subject of debate. Two hypotheses for the formation of the inactive section are the following: (1) glaciation obscured the three present-day springs, leaving only the paleo-spring, or (2) the lowest of the three major springs (Sägebach) is comparatively young, so its subcatchment previously drained to the paleo-spring. These hypotheses were tested using the pyKasso Python library (built on anisotropic fast-marching methods) to generate two ensembles of networks, one representing each scenario. Each ensemble was then compared to the known cave map. The simulated networks generated under hypothesis 2 match the observed cave map more closely than those generated under hypothesis 1. This supports the conclusion that the Sägebach spring is young, and it suggests that the cave likely continues southwards. Finally, this study extends the applicability of model ensemble methods from situations where the geologic setting is known but the network is unknown to situations where the network is known but the geologic evolution is not.
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Borgne, François Le, Michel Treuil, Jean-Louis Joron e Michel Lepiller. "Natural and EDTA-complexed lanthanides used as a geochemical probe for aquifers: a case study of Orleans valley’s alluvial and karstic aquifers". Bulletin de la Société Géologique de France 176, n. 6 (1 novembre 2005): 513–29. http://dx.doi.org/10.2113/176.6.513.
Abstract (sommario):
Abstract The transit of chemical elements within the different parts of Orleans valley’s aquifer is studied by two complementary methods. Those methods rely on the fractionation of lanthanides (Ln) during their migration in natural waters. The first method consists in studying natural lanthanides patterns within the watershed, at its entries and exits. The second one lies on multi-tracer experiments with Ln-EDTA complexes. This work is completed through an observation network consisting of 52 piezometers set on a sand and gravel quarry, and the natural entries and exits of the aquifer. Orleans valley’s aquifer, which is made of an alluvial watershed lying on a karstic aquifer, is mainly fed by the Loire river via a large karstic network. At the entries of the aquifer (Loire river at Jargeau), the Ln concentrations in the dissolved fraction (< 0,22 μm) vary with the flow of the river. During floods, Loire river waters display bulk continental crust-like Ln compositions with a slight enrichment in heavy Ln from Dy to Lu. When the Loire river flow becomes low level, the crust-normalised Ln patterns show a depletion in light Ln whereas Lu concentrations remain identical. The same evolution spatially occurs between the entries and exits of the karstic network. Spring waters are depleted in light Ln relative to the Loire river whereas heavy Ln (Yb, Lu) remain constant during transit. Furthermore, the depletion in light Ln increases with the distance between entries and exits. Tracer experiments using EDTA-complexed Ln within and between the alluvial and calcareous parts of the watershed have shown that complexed Ln are fractionated across all these geological strata. The recoveries of tracers always follow the order light Ln < heavy Ln. Moreover, both sediments analyses and filtering experiments at a porosity of 0,02 μm show that, in the presence of EDTA, Ln adsorb onto sediments and colloids in the order light Ln > heavy Ln. On the other hand, the filtration of alluvial groundwater with high colloids content induces no significant Ln fractionation when the solution contains no strong chelating agent. Hence, the transit of natural and artificial Ln in Orleans valley aquifer can be explained by two complementary processes. (1) Decanting/filtering or, on the opposite, stirring of colloids. Those processes induce no important Ln fractionation. (2) Exchanges of Ln between solute complexes, colloids and sediments due to the presence of strong chelating agents. Those exchanges fractionate the Ln in the order of their stability constants. Considering the natural Ln fractionation that occurs in the Loire river and in the studied aquifer, the carbonates, the stability constants of which follow the order light Ln < heavy Ln, are the best candidates as natural strong chelating agents. From the hydrodynamic point of view, both tracer experiments and natural Ln concentrations show that the transfer of elements within the alluvial watershed is pulsed by the Loire river movements. During an ascent phase, the elements migrate away from and perpendicularly to the karstic channels direction. During the river descent, horizontal flows are quasi absent and migrations are mainly vertical from the alluvia down to the calcareous part of the aquifer. Due to those hydrodynamic characteristics, alluvia and non fissured limestone have a high dynamic confining capacity. Elements with high affinity for solid or colloidal phases (e.g. light Ln) have an increased confining capacity in the whole aquifer, by sorption and colloid filtration within the alluvia and at the alluvial-calcareous interface, and by colloid decanting within the karstic channels. Overall, this model combines two components. The first one, hydrodynamical, results from the repartition of the loads pulsed by river Loire through the karst. The second one physico-chemical, results from the element distribution mainly controlled by colloïde/solute complexes exchange coefficients.
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Gregor, Miloš, e Peter Malík. "Construction of Master Recession Curve Using Genetic Algorithms". Journal of Hydrology and Hydromechanics 60, n. 1 (1 marzo 2012): 3–15. http://dx.doi.org/10.2478/v10098-012-0001-8.
Abstract (sommario):
Construction of Master Recession Curve Using Genetic Algorithms The article describes a new methodology of using genetic algorithms to assemble a natural time series of discharge recession, from which a master recession curve can be interpreted both for streams and for springs. Presented approach can avoid obstacles such as limited time-series datasets, incomplete recessions or too many recessionary segments in many recession series, different time intervals of observations (daily or weekly frequencies). Short time-series intervals, imprecise or mistaken measurements and different types of datasets (averaged or directly measured data) are taken into account as well. Even rough measurements of discharges with inaccurate sensing range can be analysed, if sufficiently long observation is available. Complicated hydrograph shapes in the case of e.g. karstic springs (often caused by combination of laminar and turbulent discharge sub-regimes due to karst network settings) can be processed as well. Subsequent construction of master recession curve is much easier an offers better conditions for its interpretation. Presented algorithm was already implemented to a programme solution, completed on the user form.