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Management of dewatering schemes in an open cast mine operation using groundwater fow modeling: a case study of karst aquifer, Tamil Nadu, India

Mohan Sankaralingam, Pramada Subhashini Kumudesan, Anju Maramvittil

Acta Geophysica

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2022

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Vol. 70, no 1

283--303

EN

An efficient dewatering scheme helps the management authority of mines in decision-making on the minimum quantity of withdrawal of groundwater from open-cast mines to avoid excessive groundwater withdrawal from the mines. Karst aquifers are characterized by a dual flow system consisting of Darcy flow and non-Darcy flow in the Matrix and conduits respectively. Due to lack of site-specific data, it is difficult to model the flow behavior in the dual flow system. This study evaluated equivalent porous medium (EPM) approach and the hybrid approach/combined discrete-continuum approach (CDC) for modeling groundwater flow in a karst aquifer and found that hybrid approach is suitable for modeling the flow in the karst aquifer system. Hybrid approach is applied to derive the optimum dewatering scheme for safe mining of limestone in the Adanakurichi limestone mines of Tamil Nadu, India and was found that an additional 20% increase in pumping is required in the year 2020 compared to 2016 to bring the water level to the limestone bottom. Wavelet coherence diagram was used to identify the interrelation between rainfall and groundwater levels, and also between the groundwater levels at different locations. The results from the study will be helpful for the better management of groundwater control operations in karst aquifers, under various safe level of operations. MODFLOW 2005 was used to model the aquifer based on EPM approach and for modeling based on hybrid approach conduit fow process (CFP) Mode 1in MODFLOW was used.

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A groundwater flow model for the Wolin Island area, including glaciotectonic deformation

Hoc R., Sadurski A., Wiśniowski Z.

Geologos

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2018

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Vol. 24, No. 3

207--216

EN

During the construction of mathematical models for mapping hydrogeological conditions it is necessary to apply simplifications, both in the geological structure and in hydrogeological parameters used. The present note discusses problems surrounding the mapping of glaciotectonic disturbances that occur in the northern part of Wolin Island (northwest Poland). For this part of the island, a direct outflow of groundwater towards the Baltic Sea basin has been determined on the basis of geophysical survey results. An important feature in the hydrogeological conditions here is the isolation of groundwater from both the Baltic Sea and Szczecin Lagoon by clay with a Cretaceous xenolith. Such a geological structure explains the presence of perched water at considerable heights in zones close to the cliffs, without any significant hydraulic connection with surrounding reservoirs. Hydrogeological conditions of Wolin Island have been modelled using the Visual MODFLOW package v.4.2. In the vertical section, these conditions can be simplified to one aquifer (Pleistocene-Holocene), in which two aquifers can be distinguished. In a large part of the island, these remain in mutual hydraulic contact: layer I – upper, with an unconfined aquifer, and layer II – lower, with a confined aquifer, locally an unconfined one. The schematisation of hydrogeological conditions adopted here has allowed to reproduce present groundwater dynamics in the study area.

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Wykorzystanie niestacjonarnego modelu przepływu do oceny rzeczywistej wielkości eksploatacji wód podziemnych z piętra jurajsko-kredowego na obszarze intensywnych nawodnień rolniczych w rejonie Kalisza

Matusiak M., Przybyłek J.

Przegląd Geologiczny

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2017

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Vol. 65, nr 11/2

1218--1224

EN

The paper presents an increasing problem of uncontrolled groundwater extraction of the Jurassic-Cretaceous aquifer near Kalisz. Groundwater abstraction for irrigation purpose leads to a significant decrease in groundwater pressure in the northern reaches of the Kalisz district. Spatial and temporal analyses of the depression cone development made the author searchingfor a reason that would cause an ongoing decrease in the groundwater level of agriculturally utilized areas. Due to a significant range ofJurassic- Cretaceous piezometric pressure fluctuations, a transient model has been constructed to achieve this task. The model analysis indicates that the groundwater extraction of 1240 m3/h, required to make the piezometric field distribution compatible to field measurements, is to be 30% higher than recorded. Water abstraction may rise up to 1790 m3/h in the growing season and contribute to a progressive development of a regional depression crater as a consequence. Following the over-exploitation, the piezometric pressure of the Jurassic-Cretaceous basin has already been lowered by over 20.0 m in depth in the Blizanów community.

4

Wpływ projektowanego przejścia drogowego na wody gruntowe w bagiennej dolinie rzeki

Wielechowska A., Mioduszewski W.

Woda-Środowisko-Obszary Wiejskie

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2003

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T. 3, z. 1

157-166

PL

Planowane przejście drogowe przez dolinę rzeki Rospudy wzbudza wiele kontrowersji. Istnieją uzasadnione obawy, że inwestycja ta może ujemnie oddziaływać na walory przyrodnicze bagiennej doliny. Między innymi mogą zmienić się stosunki wodne, co prowadzi do degradacji flory i fauny. W pracy przedstawiono wyniki badań modelowych stanu wód gruntowych w dolinie zarówno podczas realizacji inwestycji, jak i eksploatacji obiektu po zakończeniu prac budowlanych. Zastosowano model numeryczny MODFLOW, który umożliwił odwzorowanie obecnych warunków wodnych (położenie wód gruntowych) na obszarze doliny, a także oszacowanie wielkości zmian w położeniu zwierciadła wód gruntowych pod wpływem realizacji planowanej inwestycji. Metodykę prac badawczych oraz wyniki wariantowych (różne technologie przejścia doliny) obliczeń położenia zwierciadła wód gruntowych przedstawiono w niniejszym opracowaniu.

EN

Planned pathway across the Rospuda river valley seems to be rather controversial. There is a reasonable fear that the investment may negatively affect natural values of the valley. Water conditions, for example, may change posing a risk of degradation to flora and fauna. This paper presents computer modelled groundwater conditions in the valley during both construction and exploitation of the pathway. The numerical model MODFLOW used in this study allowed to simulate present groundwater conditions of the valley. With this model it was also possible to predict the magnitude of likely future changes in groundwater tables after accomplishment of the construction. Methodology of the research and model outputs in various scenarios (different technologies of running the road) are presented in the paper.