Papers by Elango Lakshmanan
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Pathogens isolated from the groundwater showed resistance to antibiotics, namely ceftriaxone, dox... more Pathogens isolated from the groundwater showed resistance to antibiotics, namely ceftriaxone, doxycycline and nalidixic acid. However, they were sensitive to chloramphenicol, ciprofloxacin, norfloxacin, and tetracycline.
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Pathogens isolated from the groundwater showed resistance to antibiotics, namely ceftriaxone, dox... more Pathogens isolated from the groundwater showed resistance to antibiotics, namely ceftriaxone, doxycycline and nalidixic acid. However, they were sensitive to chloramphenicol, ciprofloxacin, norfloxacin, and tetracycline.
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The study attempts to determine the chemical characters of detrital garnets provenance in the Cau... more The study attempts to determine the chemical characters of detrital garnets provenance in the Cauvery River Basin. The geochemical results reveal that the detrital garnets are derived from biotite schist, charnockite, and gneisses of intermediate felsic, moderate to strong weathered provenance. The end member composition of the garnets indicates almandine species that are metamorphosed in amphibolite to granulite facies P-T conditions. The angular outline of detrital garnet in the upstream and sub-rounded to rounded grains in the downstream attribute it’s transport from the upstream of the Cauvery River.
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A three-dimensional variable-density finite element model was developed to quantify the impact of... more A three-dimensional variable-density finite element model was developed to quantify the impact of groundwater over use on submarine groundwater discharge (SGD). The model was applied to the Arani-Korttalaiyar river basin, north of Chennai, India. This region has an upper unconfined and lower semi-confined aquifer extending up to 30 km inland from the coast and beyond this distance; the two aquifers merge and become a single unconfined aquifer. The model simulated that during the period from 2000 to 2012, the flux of seawater to the aquifer has increased from 17,000 to 24,500 m3/day due to over-exploitation of groundwater from the semi-confined aquifer. Where as in the unconfined aquifer, SGD has been taking place. Scenarios showing the impact of newly constructed managed aquifer recharge structures, 10% additional increase in rainfall recharge, and termination of pumping from five well-fields on the groundwater conditions in the area were studied. The model predicted a SGD of 85,243...
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<p&amp... more <p>Increasing water demand and climate change poses a great challenge in managing water resources availability. Reservoir operation during heavy rainfall events in an urbanized region is crucial in terms of decision making. The objective of this study is to assess the significance of reservoir operation during extreme rainfall events on flood mitigation and future domestic water supply. One of the major water supply reservoirs in Chennai city was chosen for this study. Rainfall record of recent four decades were analyzed and a major flood event occurred in 2015 was chosen. A combined model of hydrologic-hydraulic processes was carried out using Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS) and a box model based on input-output parameters. These models were calibrated and validated with historical flood events with good performance indications. Four different scenarios were framed for the analysis by targeting reduction in outflow and higher storage in the end of the event. Reducing the reservoir storage in advance and releasing with its maximum capacity at the beginning of the event will reduce the outflow from 5 to 27% and increase the time to peak by 11 to 16 hours. Available hydraulic facilities for higher storage at the end of the event were analyzed. It reveals that with the available facilities, reducing the initial storage from 75 to 50% will help to store 27 to 40% of inflow at the end of the event. Whereas the available hydraulic facilities will not allow to have a 75% of the reservoir storage at the end of this event. New gates can be provided for the safe operation during extreme rainfall events associated with the higher initial storage in the reservoir. Increased storage capacity combined with additional provisions of gates will reduce the outflow by 30% and increase the time to peak by 20 hours with the actual condition. By adapting these reservoir operation strategies, flood mitigation and fresh water augmentation during extreme events can be achieved to a significant extent. The developed combined modelling approach can be used to simulate various combinations of reservoir operations to assess the significance of timely decision on release during extreme rainfall events.</p><p>Keywords: flood mitigation, reservoir operation strategies, urban water supply, modelling</p>
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Journal of Earth System Science, 2020
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Arabian Journal of Geosciences, 2018
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Journal of Earth System Science, 2019
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Computers & Mathematics with Applications, 2018
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Chemosphere, 2018
The objective of this study is to develop a Fluoride Index for mitigation of geogenic contaminati... more The objective of this study is to develop a Fluoride Index for mitigation of geogenic contamination by Managed Aquifer Recharge (FIMAR). This index was tested by applying to the Pambar river basin in southern India. About 40% of the study area had fluoride >1.5 mg/L, contributed from the dissolution of fluorite, fluorapatite, biotite and hornblende. The relationship between groundwater level and fluoride concentration exhibited two types of relationship. In shallow wells, groundwater recharge during monsoon increases the groundwater level and dilutes the fluoride concentration. During summer, evaporation decreases the groundwater levels and increases the fluoride content. In deep wells, the fluoride-rich salts that is deposited in the unsaturated zone due to evaporation in the pre-monsoon season is flushed during groundwater recharge and thus, the fluoride concentration increases with increase in groundwater level. This relationship was used as a key layer in FIMAR. Overlay analysis including the well type derived from the groundwater level and fluoride fluctuation, average fluoride concentration, geology, geomorphology, soil, drainage density, land use, lineament density and thickness of the weathered zone indicated 30% of the area was suitable for MAR to mitigate fluoride contamination. Since the construction of new MAR structures is cost-intensive, it is proposed to rejuvenate the existing ponds in the areas identified by FIMAR to induce recharge and dilute fluoride concentration. The positive impact was confirmed using numerical and geochemical modelling. This proves that FIMAR can be used as a planning tool in fluoride endemic areas and that the future MAR methods will be beneficial to mitigate geogenic fluoride contamination.
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Journal of Earth System Science, 2017
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International Journal of Research in Engineering and Technology, 2013
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Papers by Elango Lakshmanan