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Understanding Saltwater Origins and Mechanisms in the Coastal Aquifers of Da Nang Area (Central Vietnam)

Nguyen Thao Bach, Duc Nhan Dang, Dao Bang Duc

Inżynieria Mineralna

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2023

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no. 2, vol. 1

281--288

EN

Saltwater intrusion in the rapidly developing city of Da Nang in central Vietnam is currently causing various water-related challenges, including inadequate water supply and water pollution. An integrated SWAT-MODFLOW numerical model was used to investigate the origin and mechanism of saltwater in Holocene and Pleistocene aquifers. Geophysical and isotopic approaches were used to validate the SEAWAT model applied for simulating saltwater intrusion. The results suggest that the ebb and flow of tides, as well as water levels in rivers primarily impact coastal aquifers. However, effective water resource planning and management, along with maintaining the natural recharge of fresh water from local rain during the rainy season, could enable the rational and efficient utilization of groundwater, reducing saltwater intrusion in many areas. During the dry season, groundwater is recharged from higher altitude areas. The current saltwater intrusion mainly occurs along the rivers up to the hydraulic dam. Simulated models, using scenarios of stop abstracting groundwater, but changing to the use of surface water for drinking water, show that the area of saline water shrinks quickly after 30 years, reducing from 59.6 km2 to 39.5 km2 and from 40.2 km2 to 28.6 km2 in the Holocene and Pleistocene, respectively.

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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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Ocena zmian warunków hydrogeologicznych podziemnych zakładów górniczych w GZW za pomocą modeli numerycznych

Niedbalska K.

Biuletyn Państwowego Instytutu Geologicznego

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2013

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nr 456 Hydrogeologia z. 14/2

425--429

PL

W artykule podjęto próbę scharakteryzowania możliwości zastosowania modeli numerycznych w aspekcie ich wykorzystania dla prognozowania warunków hydrogeologicznych, zagrożenia wodnego, przebiegu likwidacji kopalń i zatapiania wyrobisk na potrzeby i w warunkach górnictwa węgla kamiennego w GZW. Przeanalizowano zarówno wyniki doświadczeń GIG, jak i informacje dostępne w zebranej literaturze. Ocenę przeprowadzono pod kątem możliwości wykorzystania modeli hydrodynamicznych jako podstawy do kreowania różnych rozwiązań problemów hydrogeologicznych i prognoz opartych na bieżąco uzupełnianych danych.

EN

In this article author attempted to characterize the applicability of numerical models in the context of their use for prediction of the hydrogeological conditions, water hazards, processes of mines closure and mine workings flooding up for purposes of coal mining in Upper Silesian Coal Basin. Results of the GIG experience and information from the subject literature were analyzed. The evaluation was carried out for the possibility of using hydrodynamic models as a basis for creating a various solutions of hydrogeological problems and predictions based on data systematically collected and applied to the model.

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Pozyskiwanie danych do modelowania przepływu wód podziemnych na obszarze leja depresji BOT KWB Bełchatów S.A.

Szczepiński Jacek, Górski Grzegorz, Stachowicz Zbigniew, Szczepanik Paweł

Geologos

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2006

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Vol. 10

263--270

EN

The paper presents problems related to data availability for the ground water flow modeling in the region of the Bełchatów lignite mine. The U.S. Geological Survey’s program MODFLOW was used to reconstruct past and to present the existing conditions in the aquifers within the Bełchatów lignite mine influence. Ground water and surface water monitoring system which enables to assess changes of hydrodynamical and hydrological conditions in the region as well as methods which make possible to obtain additional hydrogeological parameters were discussed. The means in which data are collected and processed were presented.