Optimal characterization of pollutant sources in contaminated aquifers by integrating sequential-monitoring-network design and source identification: methodology and an application in Australia   总被引：1，自引：0，他引：1  

Om Prakash  Bithin Datta 《Hydrogeology Journal》2015,23(6):1089-1107

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Application of electrical resistivity to map the stratigraphy and salinity of fluvio-deltaic aquifers: case studies from Bangladesh that reveal benefits and pitfalls     

Pedrazas  Micaela N.  Cardenas  M. Bayani  Hosain  Alamgir  Demir  Cansu  Ahmed  Kazi Matin  Akhter  Syed Humayun  Wang  Lichun  Datta  Saugata  Knappett  Peter S. K. 《Hydrogeology Journal》2021,29(4):1601-1610

Fluvio-deltaic aquifers are the primary source of drinking water for the people of Bangladesh. Such aquifers, which comprise the Ganges-Brahmaputra-Meghna Delta, are hydrogeologically heterogeneous. Because of widespread groundwater quality issues in Bangladesh, it is crucial to know the hydrostratigraphic architecture and hydrochemistry, as some aquifer units are contaminated, whereas others are safe. Geophysical methods provide a potentially effective and noninvasive method for extensive characterization of these aquifers. This study applies and investigates the limitations of using electrical resistivity imaging (ERI) for mapping the hydrostratigraphy and salinity of an aquifer-aquitard system adjacent to the Meghna River. Some electrical resistivity (ER) sections showed excellent correlation between resistivity and grain size. These suggest that ERI is a powerful tool for mapping internal aquifer architecture and their boundaries with finer-grained aquitards which clearly appear as low-ER zones. However, in parts of some ER sections, variations in electrical properties were determined by porewater resistivity. In these cases, low ER was indicative of brine and did not indicate the presence of finer-grained materials such as silt or clay. Accordingly, the following hydrostratigraphic zones with different resistivities were detected: (1) aquifers saturated with fresh groundwater, (2) a regional silt/clay aquitard, and (3) a deeper brine-saturated formation. In addition, shallow silt/clay pockets were detected close to the river and below the vadose zone. ERI is thus a promising technique for mapping aquifers versus aquitards; however, the observations are easily confounded by porewater salinity. In such cases, borehole information and groundwater salinity measurements are necessary for ground-truthing.

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Global Optimal Design of Ground Water Monitoring Network Using Embedded Kriging   总被引：1，自引：0，他引：1  

by Anirban Dhar  Bithin Datta 《Ground water》2009,47(6):806-815

We present a methodology for global optimal design of ground water quality monitoring networks using a linear mixed-integer formulation. The proposed methodology incorporates ordinary kriging (OK) within the decision model formulation for spatial estimation of contaminant concentration values. Different monitoring network design models incorporating concentration estimation error, variance estimation error, mass estimation error, error in locating plume centroid, and spatial coverage of the designed network are developed. A big-M technique is used for reformulating the monitoring network design model to a linear decision model while incorporating different objectives and OK equations. Global optimality of the solutions obtained for the monitoring network design can be ensured due to the linear mixed-integer programming formulations proposed. Performances of the proposed models are evaluated for both field and hypothetical illustrative systems. Evaluation results indicate that the proposed methodology performs satisfactorily. These performance evaluation results demonstrate the potential applicability of the proposed methodology for optimal ground water contaminant monitoring network design.  相似文献   

The great 1950 Assam Earthquake revisited: Field evidences of liquefaction and search for paleoseismic events   总被引：1，自引：0，他引：1  

D.V. Reddy  P. Nagabhushanam  Devender Kumar  B.S. Sukhija  P.J. Thomas  Anand K. Pandey  R.N. Sahoo  G.V. Ravi Prasad  K. Datta 《Tectonophysics》2009,474(3-4):463-472

Extensive field investigations were carried out for the first time in the meizoseismal area of the great 1950 Assam Earthquake aimed at exploring the paleoseismic history of the NE Indian region through documentation of liquefaction features and radiocarbon (¹⁴C) dating. Trenching at more than a dozen locations along the Burhi Dihing River valley and within the alluvial fans adjoining the Brahmaputra and Dibang Rivers resulted in the identification of more than a dozen very prominent liquefaction features (sand dykes, sills, sand blows etc.) as evidences of large to great earthquakes. ¹⁴C dating of the organic material associated with some of the features indicates a paleoseismic record of about 500 yrs archived by the sediments in this region. Compelling geological evidence(s) of the great 1950 earthquake are well constrained by ¹⁴C dating. Out of the two historically reported seismic events (1548 AD and 1697 AD) from this region, ¹⁴C dating could constrain the 1548 AD event though not distinctly. Further studies using combined ¹⁴C and OSL dating may better constrain the seismo-chronology of the study region.  相似文献   

Hazardous Waste Pollution Prevention Using Clay with Admixtures     

Papita Saha  Siddhartha Datta  Shyamal Kanti Sanyal 《洁净——土壤、空气、水》2008,36(2):230-238

Landfill is the most commonly used method for disposal of waste materials since it is one of the least expensive methods. In order to dispose of any hazardous material to a landfill, a liner is used, which protects the underlying land and groundwater since it acts as a barrier to fluid movement. Of the various methods available for providing improved and more effective properties of landfills, methods involving the use of bentonite, cement, lime, gypsum, etc., have been explored in the laboratory. The aim is to overcome the problem and deficiencies of the existing liners. It is observed from the experimental results that the metal concentrations of the input waste solution can be reduced to 80–98% using a soil‐cement admixture, 60–95% using a soil‐gypsum mixture, 45–95% using a soil‐bentonite mixture, 50–90% for soil, 35–80% using a soil‐lime mixture, as liner materials. The permeation rate of different metals through the different soil‐admixture media depends on various factors. A simple mathematical treatment of the phenomenon related to the permeation of liquid through the admixture of the clay and other components has been developed. The experimental results show satisfactory agreement with the predictions.  相似文献   

Implications of kHz quasi-periodic brightness oscillations in X-ray binaries for neutron star structure     

Arun V. Thampan  Dipankar Bhattacharya  Bhaskar Datta 《Monthly notices of the Royal Astronomical Society》1999,302(4):L69-L73

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Probability-credibility health risk assessment under uncertain environment     

Rituparna?ChutiaEmail authorView author&#;s OrcID profile  D.?Datta 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(2):449-460

The ability to describe variables in a health risk model through probability theory enables us to estimate human health risk. These types of risk assessment are interpreted as probabilistic risk assessment (PRA). Generally, PRA requires specific estimate of the parameters of the probability density of the input variables. In all circumstances, such estimates of the parameters may not be available due to the lack of knowledge or information. Such types of variables are treated as uncertain variables. These types of information are often termed uncertainty which are interpreted through fuzzy theory. The ability to describe uncertainty through fuzzy set theory enables us to process both random variable and fuzzy variable in a single framework. The method of processing aleatory and epistemic uncertainties into a same framework is coined as hybrid method. In this paper, we are going to talk about such type of hybrid methodology for human health risk assessment. Risk assessment on human health through different pathways of exposure has been attempted many a times combining Monte Carlo analysis and extension principle of fuzzy set theory. The emergence of credibility theory enables transforming fuzzy variable into credibility distribution function which can be used in those hybrid analyses. Hence, an attempt, for the first time, has been made to combine probability theory and credibility theory to estimate risk in human health exposure. This method of risk assessment in the presence of credibility theory and probability theory is identified as probabilistic-credibility method (PCM). The results obtained are then interpreted through probability theory, unlike the other hybrid methodology where the results are interpreted in terms of possibility theory. The results obtained are then compared with probability-fuzzy risk assessment (PFRA) method. Generally, decision under hybrid methodology is made on the index of optimism. An optimistic decision maker estimates from the \(\alpha\)-cut at 1, whereas a pessimistic decision maker estimates from the \(\alpha\)-cut at 0. The PCM is an optimistic approach as the decision is always made at \(\alpha\)=1.  相似文献   

Non-axisymmetric guided waves in a composite cylinder with transversely isotropic core     

N. Rattanawangcharoen  Subhendu K. Datta  Arvind H. Shah 《Geophysical Journal International》1994,118(2):317-324

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Optimal operation of reservoirs for downstream water quality control using linked simulation optimization     

Anirban Dhar  Bithin Datta 《水文研究》2008,22(6):842-853

A methodology is developed for optimal operation of reservoirs to control water quality requirements at downstream locations. The physicochemical processes involved are incorporated using a numerical simulation model. This simulation model is then linked externally with an optimization algorithm. This linked simulation–optimization‐based methodology is used to obtain optimal reservoir operation policy. An elitist genetic algorithm is used as the optimization algorithm. This elitist‐genetic‐algorithm‐based linked simulation–optimization model is capable of evolving short‐term optimal operation strategies for controlling water quality downstream of a reservoir. The performance of the methodology developed is evaluated for an illustrative example problem. Different plausible scenarios of management are considered. The operation policies obtained are tested by simulating the resulting pollutant concentrations downstream of the reservoir. These performance evaluations consider various scenarios of inflow, permissible concentration limits, and a number of management periods. These evaluations establish the potential applicability of the developed methodology for optimal control of water quality downstream of a reservoir. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Application of criteria and indicators in community based sustainable mangrove management in the Sunderbans,India     

Debajit Datta  P. Guha  R.N. Chattopadhyay 《Ocean & Coastal Management》2010,53(8):468-477

Management of mangroves in a sustainable ecological as well as economic way is a difficult proposition and needs multi-disciplinary intervention. This paper highlights the importance of criteria and indicators to evaluate the status of performance of communities in managing their mangroves sustainably. The framework developed on the basis of 6 principles, 12 criteria, 36 indicators and 47 verifiers had been applied for assessment of Eco-Development Committees of the Sunderbans, India. Results show the presence of a highly positive correlation between performance of the committees and condition of the mangrove environment. Level of implementation of legal and institutional management strategies to protect mangroves proves to be the essential pre-condition in achieving sustainability. The study further demonstrates the effectiveness of the developed framework in the context of community forestry since the methodology was designed to be simple and flexible so as to apply it in forest management unit level without any major difficulty.  相似文献