scholarly journals Joint estimation of groundwater salinity and hydrogeological parameters using variable-density groundwater flow, salt transport modelling and airborne electromagnetic surveys

2021 ◽  
pp. 104118
Author(s):  
Jude King ◽  
Tobias Mulder ◽  
Gualbert Oude Essink ◽  
Marc.F.P. Bierkens
Keyword(s):  
Groundwater Flow ◽  
Variable Density ◽  
Joint Estimation ◽  
Salt Transport ◽  
Groundwater Salinity ◽  
Transport Modelling ◽  
Hydrogeological Parameters ◽  
Airborne Electromagnetic ◽  
Electromagnetic Surveys

Improved parameterization of airborne electromagnetic surveys for groundwater salinity mapping using 3D variable-density groundwater flow models

2020 ◽  
Author(s):  
Jude A. King ◽  
Gualbert H. P. Oude Essink ◽  
Marc F. P. Bierkens
Keyword(s):  
Groundwater Flow ◽  
Initial Conditions ◽  
Regional Distribution ◽  
Variable Density ◽  
Salt Transport ◽  
Inversion Method ◽  
Groundwater Salinity ◽  
Groundwater Model ◽  
Two Factors ◽  
Airborne Electromagnetic

<p>Airborne electromagnetics is a cost-effective and rapid method with which to map the regional distribution of saline groundwater in coastal areas, however the process of transforming observed data into salinity estimates comprises multiple sources of uncertainty. The resulting error primarily relates to two factors: (1) the transformation (or inversion) from airborne observations into physical properties, (2) the availability of lithological information to transform inversion results to salinity estimates. Recent research has shown that this uncertainty can significantly affect the accuracy of resulting groundwater salinity estimates, in particular the location of the fresh-saline interface. Reducing error relating to the two factors is not trivial. Firstly, as the inversion process is non-unique, an infinite number of models can fit the data. Secondly, the availability of lithological information on regional scales is generally low. To highlight potential sources of error and improve parameterization, we investigate the usefulness of combining airborne electromagnetic data with a 3D variable-density groundwater flow and coupled salt transport model. We quantitatively present findings using a synthetic model which was created using an existing large-scale (~100km<sup>2</sup>) 3D groundwater model based on real data from the Netherlands. The model is created in two steps: (1) the available groundwater model is run until a state of equilibrium is reached with the model boundaries and stress terms and (2), an airborne survey is simulated using standard geophysical forward modelling techniques, resulting in set of observations. The airborne observations are then inverted and used alongside a simulated lithological data acquisition programme, which are finally input as initial conditions to a groundwater model. As the groundwater model is assumed to be in a state of equilibrium, we show the effect of implementing an optimization framework that penalizes the rate of groundwater salinity fluctuations by iteratively changing the input parameters of both the inversion method and the lithological data. Results quantitatively highlight the effectiveness of implementing a simple, inter-disciplinary approach to airborne electromagnetic groundwater mapping.</p>

scholarly journals Probabilistic Groundwater Flow, Particle Tracking and Uncertainty Analysis for Environmental Receptor Vulnerability Assessment of a Coal Seam Gas Project

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3177
Author(s):  
Dennis Gonzalez ◽  
Sreekanth Janardhanan ◽  
Daniel E. Pagendam ◽  
Daniel W. Gladish
Keyword(s):  
Risk Assessment ◽  
Coal Seam ◽  
Groundwater Flow ◽  
Contaminant Transport ◽  
Particle Tracking ◽  
Gas Wells ◽  
Coal Seam Gas ◽  
Transport Pathway ◽  
Transport Modelling ◽  
Contamination Risk

The production of coalbed methane, or coal seam gas (CSG) in Australia increased 250-fold since the 1990s to around 1502 petajoules in 2019 and continues to expand. Groundwater flow in the aquifers intersected by gas wells could potentially facilitate a transport pathway for migration of contaminants or poorer quality water from deeper formations. While regulatory and mitigation mechanisms are put in place to minimize the risks, quantitative environmental impact assessments are also undertaken. When many gas wells are drilled in a wide area where many potential receptors are also spatially distributed, potential source-receptor combinations are too numerous to undertake detailed contamination risk assessment using contaminant transport modelling. However, valuable information can be gleaned from the analysis of groundwater flow directions and velocities to inform and prioritise contamination risk assessment and can precede computationally challenging stochastic contaminant transport modelling. A probabilistic particle tracking approach was developed as a computationally efficient screening analysis of contamination pathways for a planned CSG development near Narrabri in northern New South Wales, Australia. Particle tracking was run iteratively with a numerical groundwater flow model across a range of plausible parameter sets to generate an ensemble of estimated flow paths through the main Great Artesian Basin aquifer in the area. Spatial patterns of path lines and spatial relationships with potential receptors including neighbouring groundwater extraction wells and hydrologically connected ecological systems were analysed. Particle velocities ranged from 0.5 to 11 m/year and trajectories indicated dedicated contaminant transport modeling would be ideally focused at the local scale where wells are near potential receptors. The results of this type of analysis can inform the design of monitoring strategies and direct new data collection to reduce uncertainty and improve the effectiveness of adaptive management strategies and early detection of impacts.

scholarly journals Analysis of Water Cycle in Weizhou Island of Beihai City, Guangxi Province, Part II: Study On Groundwater Exploitation Plan

2018 ◽  
Vol 246 ◽  
pp. 02047
Author(s):  
Shunfu Zhang ◽  
Changjun Liu ◽  
Chuanke Li ◽  
Sili Long ◽  
Jian Zhou ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Ground Water ◽  
Seawater Intrusion ◽  
Groundwater Level ◽  
Water Cycle ◽  
Variable Density ◽  
Analysis Model ◽  
Guangxi Province ◽  
Groundwater Exploitation ◽  
Groundwater Levels

To relieve the drop of groundwater and seawater intrusion in Weizhou Island caused by overexploitation, the analysis model of precipitation-runoff and variable-density groundwater flow in Weizhou Island was established and the model’s parameter identification results were used to investigate groundwater level and seawater/freshwater interface changes under different groundwater exploitation plans. Thereafter, a rational groundwater exploitation plan could be made to prevent the lowering of groundwater levels caused by ground water overexploitation and ecological deterioration caused by seawater intrusion. This could help accelerating the recovery of ground water and maintaining ecological system.

Simulation of Groundwater Flow and Pollutant Transport for Alluvial Aquifer in Kampung Tekek, Tioman Island

2012 ◽  
Author(s):  
Norhan Abd. Rahman ◽  
Woei–Keong Kuan
Keyword(s):  
Groundwater Flow ◽  
Flow Simulation ◽  
Pollutant Transport ◽  
World Health Organisation ◽  
Peninsular Malaysia ◽  
Tourism Industry ◽  
World Health ◽  
Visual Modflow ◽  
Transport Modelling ◽  
Potential Contaminant

Pulau Tioman terletak di pantai timur Semenanjung Malaysia. Akibat pembangunan yang pesat dalam industri pelancongan, permintaan terhadap bekalan air dijangka akan meningkat di pulau ini. Daripada kajian yang telah dijalankan sebelumnya, didapati airbumi merupakan sumber air yang berpotensi. Satu perisian model 3–dimensi (Visual MODFLOW) telah digunakan untuk menghasilkan model aliran airbumi dan pengangkutan bahan pencemar di Kampung Tekek dengan tujuan meramal simpanan airbumi dan penyebaran bahan pencemar, iaitu nitrat, semasa pengepaman. Daripada keputusan simulasi aliran airbumi yang diperolehi, pengepaman akuifer di Kampung Tekek dapat mencapai pada kadar 4000 m3/hari. Kajian model bahan pencemar menunjukkan kepekatan bahan pencemar nitrat yang tercatat di telaga pam didapati agak rendah dan memenuhi piawaian air minuman World Health Organisation (WHO). Kata kunci: Aliran airbumi, bahan pencemar, model numerik, Visual MODFLOW, pulau Tioman Island is situated in the east coast of Peninsular Malaysia. With rapid growth in tourism industry, the demand for water supply is expected to increase in this island. From previous studies, groundwater was found to be a potential source of water. A 3–dimensional numerical modelling software (Visual MODFLOW) is used to simulate the groundwater flow and pollutant transport of the aquifer in Kampung Tekek, for the prediction of available yield of groundwater, and also for studying the migration of potential contaminant source, i.e. nitrate, due to the withdrawal. The groundwater flow simulation results showed that the aquifer is capable of pumping 4000 m3/day. Results of pollutant transport modelling showed that the estimated concentration of nitrate in the pump well is generally low and complies with World Health Organisation (WHO) standard for drinking water. Key words: Groundwater flow, pollutant transport, numerical model, Visual MODFLOW, island

scholarly journals Joint Estimation of Hydraulic and Biochemical Parameters for Reactive Transport Modelling with a Modified ILUES Algorithm

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2161
Author(s):  
Ruicheng Zhang ◽  
Nianqing Zhou ◽  
Xuemin Xia ◽  
Guoxian Zhao ◽  
Simin Jiang
Keyword(s):  
Reactive Transport ◽  
Biochemical Parameters ◽  
Transport Model ◽  
Joint Estimation ◽  
Model Parameters ◽  
Transport Modelling ◽  
Selection Scheme ◽  
Related Model ◽  
Ensemble Smoother ◽  
Iterative Ensemble Smoother

Multicomponent reactive transport modeling is a powerful tool for the comprehensive analysis of coupled hydraulic and biochemical processes. The performance of the simulation model depends on the accuracy of related model parameters whose values are usually difficult to determine from direct measurements. In this situation, estimates of these uncertain parameters can be obtained by solving inverse problems. In this study, an efficient data assimilation method, the iterative local updating ensemble smoother (ILUES), is employed for the joint estimation of hydraulic parameters, biochemical parameters and contaminant source characteristics in the sequential biodegradation process of tetrachloroethene (PCE). In the framework of the ILUES algorithm, parameter estimation is realized by updating local ensemble with the iterative ensemble smoother (IES). To better explore the parameter space, the original ILUES algorithm is modified by determining the local ensemble partly with a linear ranking selection scheme. Numerical case studies based on the sequential biodegradation of PCE are then used to evaluate the performance of the ILUES algorithm. The results show that the ILUES algorithm is able to achieve an accurate joint estimation of related model parameters in the reactive transport model.

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