Faculty Publications

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Publications by NITK Faculty

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    Characterizing aquifers when using magnetic resonance sounding in a heterogeneous geomagnetic field
    (EAGE Publishing BV P.O.Box 18667 Newark NJ 07191-8667, 2011) Vouillamoz, J.M.; Legchenko, A.; Nandagiri, L.
    It has previously been reported that the heterogeneity of the geomagnetic field disturbs the currently-measured free induction decay signal of magnetic resonance sounding (MRS). To overcome the limitation of MRS in a non-homogeneous geomagnetic field, we adapted the spin-echo methodology usually used at the laboratory scale and in boreholes. We present examples of measurements carried out in a sandy aquifer in southern India. The 15-25 m thick sand deposit overlays a gneissic basement. Two sources of geomagnetic field heterogeneity have been identified at this site, both affecting the geomagnetic field within the sandy aquifer: the gneissic bedrock and an intruded dyke into the bedrock. Spin-echo and free induction decay signals have been recorded at six locations. We found that the groundwater content, the thickness of the saturated aquifer and its transmissivity calculated with free induction decay measurements are underestimated compared to those derived from spin-echo measurements. The closer to the dyke the higher the underestimation. Time-domain electromagnetic measurements indicate that the aquifer is rather homogeneous at the site scale, as suggested by spin-echo results. We also found that a small heterogeneity of the geomagnetic field can go unnoticed, thus leading to an unknown mis-estimate of aquifer properties when using free induction decay measurements. Thus spin-echo measurements can be used to improve the accuracy of aquifer characterization when using MRS in geological contexts where geomagnetic field heterogeneity exists. © 2010 European Association of Geoscientists & Engineers.
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    Groundwater hydrochemistry of Rajnandgaon district, Chhattisgarh, Central India
    (Elsevier B.V., 2020) Ankit, A.; Nanda, A.; Sahu, B.L.; Sahu, Y.K.; Patel, K.S.; Pervez, S.; Gulgundi, M.S.; Cuchí-Oterino, J.A.; Martín-Ramos, P.; Bhattacharya, P.
    The spreading of fluorosis diseases in Central India related to high concentrations of fluoride ion (F?) is a cause of major concern. In this work, the hydrochemistry of the aquifers related to Seonath River, in Rajnandgaon district, Chhattisgarh state, India, has been studied, focusing on the presence and sources of F?. Hydrochemical parameters were analyzed in the post-monsoon season in 160 wells located in nine tehsils, finding F? concentrations ranging from 0.6 to 18.5 mg L?1. Seasonal variations were also studied in Chhuikhadan tehsil, in which the highest F? values were registered, finding a noticeable enrichment in the pre-monsoon months. In many locations of the district, F? concentrations exceeded the recommended value of 1.5 mg L?1, which have led to the appearance of several health issues. Multidimensional analysis statistical methods were adopted to investigate the sources of F?, and the mineralization of bedrock elements into the groundwater was observed to be the primary source. © 2020 Elsevier B.V.
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    Electrical resistivity, remote sensing and geographic information system approach for mapping groundwater potential zones in coastal aquifers of Gurpur watershed
    (Taylor and Francis Ltd., 2021) Virupaksha, H.S.; Lokesh, K.N.
    Electrical resistivity method and RS & GIS techniques are very much useful in identification of potential aquifer zones for exploitation, management and recharge of groundwater. Vertical Electrical Soundings are conducted at 35 locations in Gurpur watershed using Schlumberger array. The thematic layers like porosity, transmissivity and hydraulic conductivity are prepared using electrical resistivity data. Total of 13 thematic layers are used for vector integration and identification of Groundwater Potential Zones (GWPZ). The numerical weights and ranks are assigned to the themes based on their relationship with groundwater. The findings shows that the depth to bedrock varies from 9.1 to 44.4 m and most of the mid land and low land region shows moderate to high depths of about 25–44 m. The GWPZ are classified into five classes namely, Very Good (?21.02 km2), Good (?231.35 km2), Moderate (?420.76 km2), Poor (?185.05 km2) and Very Poor (?19.56 km2). The Good and Moderate categories cover ?75% of total area. © 2019 Informa UK Limited, trading as Taylor & Francis Group.