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Dr. Chuen-Fa Ni
Graduate Institute of Applied Geology, National Central University

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0 Groundwater Contamination
0 Hydrogeology
0 Numerical Modeling
0 water resource
0 Groundwater and surface water interaction

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Groundwater Contamination
Groundwater and surface water interaction
Numerical Modeling

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Technical note
Published: 07 May 2021 in Hydrology and Earth System Sciences
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This work develops a transfer function to describe the variation in the integrated specific discharge in response to the temporal variation in the rainfall event in the frequency domain. It is assumed that the rainfall–discharge process takes place in a confined aquifer with variable thickness, and it is treated as nonstationary in time to represent the stochastic nature of the hydrological process. The presented transfer function can be used to quantify the variability in the integrated discharge field induced by the variation in rainfall field or to simulate the discharge response of the system to any varying rainfall input at any time resolution using the convolution model. It is shown that, with the Fourier–Stieltjes representation approach, a closed-form expression for the transfer function in the frequency domain can be obtained, which provides a basis for the analysis of the influence of controlling parameters occurring in the rainfall rate and integrated discharge models on the transfer function.

ACS Style

Ching-Min Chang; Chuen-Fa Ni; We-Ci Li; Chi-Ping Lin; I-Hsien Lee. Technical note: Discharge response of a confined aquifer with variable thickness to temporal, nonstationary, random recharge processes. Hydrology and Earth System Sciences 2021, 25, 2387 -2397.

AMA Style

Ching-Min Chang, Chuen-Fa Ni, We-Ci Li, Chi-Ping Lin, I-Hsien Lee. Technical note: Discharge response of a confined aquifer with variable thickness to temporal, nonstationary, random recharge processes. Hydrology and Earth System Sciences. 2021; 25 (5):2387-2397.

Chicago/Turabian Style

Ching-Min Chang; Chuen-Fa Ni; We-Ci Li; Chi-Ping Lin; I-Hsien Lee. 2021. "Technical note: Discharge response of a confined aquifer with variable thickness to temporal, nonstationary, random recharge processes." Hydrology and Earth System Sciences 25, no. 5: 2387-2397.

Journal article
Published: 16 February 2021 in Journal of Hydrology
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This study presents a new concept that integrates the index-overlay method and a physical-based numerical model for predicting groundwater sustainability under various climate conditions and anthropogenic activities. The index-overlay DRASTIC method was modified with an analytical hierarchy process theory and employed to create groundwater vulnerability maps for the Pingtung plain groundwater basin in southern Taiwan. The physical-based MODFLOW model was used for predicting the dynamics of a basin-scale groundwater system. Solutions and calibrated hydrogeological parameters in the MODFLOW model provide feedback to the factors in the modified DRASTIC method which enables predicting groundwater vulnerability. In this study, different climate conditions were considered in the numerical model to obtain the changes in depth of water and net recharge for predicting future groundwater vulnerability and for evaluating the current state of the sustainability indicators. Results show that the depth of water and net recharge obtained from the groundwater model improve the accuracy of the groundwater vulnerability prediction. The variations of future climate conditions have less influence on the variations of groundwater vulnerability because of the dense river network that controls the shallow groundwater levels in the Pingtung plain groundwater basin. Therefore, the influence of climate conditions on the risk of groundwater contamination is also relatively low. Based on the analysis of the sustainability indicators, we found that the groundwater resource system in the Pingtung plain groundwater basin is in a critical condition of high vulnerability.

ACS Style

Tien-Duc Vu; Chuen-Fa Ni; Wei-Ci Li; Minh-Hoang Truong; Shaohua Marko Hsu. Predictions of groundwater vulnerability and sustainability by an integrated index-overlay method and physical-based numerical model. Journal of Hydrology 2021, 596, 126082 .

AMA Style

Tien-Duc Vu, Chuen-Fa Ni, Wei-Ci Li, Minh-Hoang Truong, Shaohua Marko Hsu. Predictions of groundwater vulnerability and sustainability by an integrated index-overlay method and physical-based numerical model. Journal of Hydrology. 2021; 596 ():126082.

Chicago/Turabian Style

Tien-Duc Vu; Chuen-Fa Ni; Wei-Ci Li; Minh-Hoang Truong; Shaohua Marko Hsu. 2021. "Predictions of groundwater vulnerability and sustainability by an integrated index-overlay method and physical-based numerical model." Journal of Hydrology 596, no. : 126082.

Preprint content
Published: 23 November 2020
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This work develop a transfer function to describe the variation of the integrated specific discharge in response to the temporal variation of the rainfall event in the frequency domain. It is assumed that the rainfall-discharge process takes place in a confined aquifer with variable thickness, and it is treated as nonstationary in time to represent the stochastic nature of the hydrological process. The presented transfer function can be used to quantify the variability of the integrated discharge field induced by the variation of rainfall field or to simulate the discharge response of the system to any varying rainfall input at any time resolution using the convolution model. It is shown that with the Fourier-Stieltjes representation approach a closed-form expression for the transfer function in the frequency domain can be obtained, which provide a basis for the analysis of the influence of controlling parameters occurring in the rainfall rate and integrated discharge models on the transfer function.

ACS Style

Ching-Min Chang; Chuen-Fa Ni; We-Ci Li; Chi-Ping Lin; I-Hsian Lee. Technical note: Discharge response of a confined aquifer with variable thickness to temporal nonstationary random recharge processes. 2020, 2020, 1 -29.

AMA Style

Ching-Min Chang, Chuen-Fa Ni, We-Ci Li, Chi-Ping Lin, I-Hsian Lee. Technical note: Discharge response of a confined aquifer with variable thickness to temporal nonstationary random recharge processes. . 2020; 2020 ():1-29.

Chicago/Turabian Style

Ching-Min Chang; Chuen-Fa Ni; We-Ci Li; Chi-Ping Lin; I-Hsian Lee. 2020. "Technical note: Discharge response of a confined aquifer with variable thickness to temporal nonstationary random recharge processes." 2020, no. : 1-29.

Journal article
Published: 04 November 2020 in Water
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The scarcity of groundwater and precipitation stations has limited accurate assessments of basin-scale groundwater systems. This study proposes a workflow that integrates satellite and on-site observations to improve the spatial and temporal resolution of the groundwater level and enable recharge estimations for the Choushui River groundwater basin (CRGB) in Western Taiwan. The workflow involves multiple data processing steps, including analysis of correlation, evaluation of residuals, and geostatistical interpolation based on kriging methods. The observed groundwater levels and recharge are then the basis to assess spatial-temporal interactions between groundwater and recharge in the CRGB from 2006 to 2015. Results of correlation analyses show the high correlation between the groundwater level and the land surface elevation in the study area. However, the multicollinearity problem exists for the additional precipitation data added in the correlation analyses. The correlation coefficient, root mean square error, and normalized root mean square parameters indicate that the Regression Kriging (RK) performs better the groundwater variations than the Ordinary Kriging (OK) dose. The data-driven approach estimates an annual groundwater recharge of approximately 1.40 billion tons, representing 37% of the yearly precipitation. The correlation between groundwater levels and groundwater recharge exhibits low or negative correlation zones in the groundwater basin. These zones might have resulted from multipurpose pumping activities and the river and drainage networks in the area. The event-based precipitation and groundwater level have shown strong recharge behavior in the low-land area of the basin. Artificial weir operations at the high-land mountain pass might considerably influence the groundwater and surface water interactions.

ACS Style

Lamtupa Nainggolan; Chuen-Fa Ni; Yahya Darmawan; I-Hsien Lee; Chi-Ping Lin; Wei-Ci Li. Data-Driven Approach to Assess Spatial-Temporal Interactions of Groundwater and Precipitation in Choushui River Groundwater Basin, Taiwan. Water 2020, 12, 3097 .

AMA Style

Lamtupa Nainggolan, Chuen-Fa Ni, Yahya Darmawan, I-Hsien Lee, Chi-Ping Lin, Wei-Ci Li. Data-Driven Approach to Assess Spatial-Temporal Interactions of Groundwater and Precipitation in Choushui River Groundwater Basin, Taiwan. Water. 2020; 12 (11):3097.

Chicago/Turabian Style

Lamtupa Nainggolan; Chuen-Fa Ni; Yahya Darmawan; I-Hsien Lee; Chi-Ping Lin; Wei-Ci Li. 2020. "Data-Driven Approach to Assess Spatial-Temporal Interactions of Groundwater and Precipitation in Choushui River Groundwater Basin, Taiwan." Water 12, no. 11: 3097.

Journal article
Published: 14 October 2020 in Applied Sciences
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The landforms and human activities play important roles in quantifying surface water and groundwater interactions (SGIs) for water resources management. The study uses the groundwater and surface-water FLOW model (GSFLOW) model to quantify the dynamics of SGIs in the Pingtung Plain groundwater basin (PPGB) in southern Taiwan. Specifically, the study uses a physical-based numerical model to quantify the spatial and seasonal variations of water cycles influenced by complex fluvial landform conditions and human activities. Results of the model calibrations show good agreement with the data obtained from the available groundwater monitoring network and the selected stream stations. The basin-scale water budgets show highly nonuniform precipitation in the study area, and over 80% annual precipitation is from wet seasons in the PPGB. With high permeable surficial deposits in the PPGB, the year-averaged surface runoff and infiltration are approximately 57% and 40% of the total precipitation. The fluvial landforms with the high slope in the PPGB lead to 70% of annual surface runoff that becomes the streamflow, and the interflow dominates water interactions near streambeds. Results show that the interflow rate in the wet seasons is 200% more than that in the dry seasons. The net groundwater discharge to the streams is relatively small as compared to the interflow. Only 10% of the river flow is from the net groundwater discharge. In the PPGB, The pumping-induced variations of groundwater levels are insignificant as compared with the factor of the natural landforms. Because of the relatively small area of the proposed artificial lake, the contribution of the artificial lake on the local water budgets is insignificant, indicating the low impact of the artificial recharge lake on the surface water environment.

ACS Style

Quoc-Dung Tran; Chuen-Fa Ni; I-Hsien Lee; Minh-Hoang Truong; Chien-Jung Liu. Numerical Modeling of Surface Water and Groundwater Interactions Induced by Complex Fluvial Landforms and Human Activities in the Pingtung Plain Groundwater Basin, Taiwan. Applied Sciences 2020, 10, 7152 .

AMA Style

Quoc-Dung Tran, Chuen-Fa Ni, I-Hsien Lee, Minh-Hoang Truong, Chien-Jung Liu. Numerical Modeling of Surface Water and Groundwater Interactions Induced by Complex Fluvial Landforms and Human Activities in the Pingtung Plain Groundwater Basin, Taiwan. Applied Sciences. 2020; 10 (20):7152.

Chicago/Turabian Style

Quoc-Dung Tran; Chuen-Fa Ni; I-Hsien Lee; Minh-Hoang Truong; Chien-Jung Liu. 2020. "Numerical Modeling of Surface Water and Groundwater Interactions Induced by Complex Fluvial Landforms and Human Activities in the Pingtung Plain Groundwater Basin, Taiwan." Applied Sciences 10, no. 20: 7152.

Journal article
Published: 21 April 2020 in Applied Soft Computing
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Deep learning for enhancing simulation IoTs groundwater flow is a good solution for gaining insights into the behavior of aquifer systems. In previous studies, corresponding results give a basis for the rational management of groundwater resources. The users generally require special skills or knowledge and massive observations in representing the field reality to perform the deep learning algorithms and simulations. To simplify the procedures for performing the numerical and large-scale groundwater flow simulations, we apply the deep learning algorithms which combine both the numerical groundwater model and large-scale IoTs, groundwater flow measuring equipment and various complex groundwater numerical models. The mechanism has the capability to show spatial distributions of in-situ data, analyze the spatial relationships of observed data, generate meshes, update users’ databases with in-situ observed data, and create professional reports. According to the numerical simulation results, we revealed that the deep learning algorithms are high computational efficiency, and we can enhance precise variance estimations for large-scale groundwater flow problems. The findings help users to best apply the deep learning algorithms in an easier way, get more accurate simulation results, and manage the groundwater resources rationally.

ACS Style

Yu-Sen Su; Chuen-Fa Ni; Wei-Ci Li; I-Hsien Lee; Chi-Ping Lin. Applying deep learning algorithms to enhance simulations of large-scale groundwater flow in IoTs. Applied Soft Computing 2020, 92, 106298 .

AMA Style

Yu-Sen Su, Chuen-Fa Ni, Wei-Ci Li, I-Hsien Lee, Chi-Ping Lin. Applying deep learning algorithms to enhance simulations of large-scale groundwater flow in IoTs. Applied Soft Computing. 2020; 92 ():106298.

Chicago/Turabian Style

Yu-Sen Su; Chuen-Fa Ni; Wei-Ci Li; I-Hsien Lee; Chi-Ping Lin. 2020. "Applying deep learning algorithms to enhance simulations of large-scale groundwater flow in IoTs." Applied Soft Computing 92, no. : 106298.

Journal article
Published: 27 November 2019 in Water
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Fractures are major flow paths for solute transport in fractured rocks. Conducting numerical simulations of reactive transport in fractured rocks is a challenging task because of complex fracture connections and the associated nonuniform flows and chemical reactions. The study presents a computational workflow that can approximately simulate flow and reactive transport in complex fractured media. The workflow involves a series of computational processes. Specifically, the workflow employs a simple particle tracking (PT) algorithm to track flow paths in complex 3D discrete fracture networks (DFNs). The PHREEQC chemical reaction model is then used to simulate the reactive transport along particle traces. The study illustrates the developed workflow with three numerical examples, including a case with a simple fracture connection and two cases with a complex fracture network system. Results show that the integration processes in the workflow successfully model the tetrachloroethylene (PCE) and trichloroethylene (TCE) degradation and transport along particle traces in complex DFNs. The statistics of concentration along particle traces enables the estimations of uncertainty induced by the fracture structures in DFNs. The types of source contaminants can lead to slight variations of particle traces and influence the long term reactive transport. The concentration uncertainty can propagate from parent to daughter compounds and accumulate along with the transport processes.

ACS Style

Phuong Thanh Vu; Chuen-Fa Ni; Wei-Ci Li; I-Hsien Lee; Chi-Ping Lin. Particle-Based Workflow for Modeling Uncertainty of Reactive Transport in 3D Discrete Fracture Networks. Water 2019, 11, 2502 .

AMA Style

Phuong Thanh Vu, Chuen-Fa Ni, Wei-Ci Li, I-Hsien Lee, Chi-Ping Lin. Particle-Based Workflow for Modeling Uncertainty of Reactive Transport in 3D Discrete Fracture Networks. Water. 2019; 11 (12):2502.

Chicago/Turabian Style

Phuong Thanh Vu; Chuen-Fa Ni; Wei-Ci Li; I-Hsien Lee; Chi-Ping Lin. 2019. "Particle-Based Workflow for Modeling Uncertainty of Reactive Transport in 3D Discrete Fracture Networks." Water 11, no. 12: 2502.

Journal article
Published: 26 November 2019 in Water
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The groundwater vulnerability (GV) assessment for contamination is an effective technique for the planning, policy, and decision-making, as well as for sustainable groundwater resource protection and management. The GV depends strongly on local hydrogeological settings and land-use conditions that may vary in response to the activities of agricultural development. In this study, a modified DRASTIC model, which employs an additional factor of land use coupled with the analytic hierarchy process (AHP) theory, was used to quantify the spatial and temporal variation of GV and groundwater contamination risk in the Pingtung groundwater basin. The results show that the GV slightly decreased due to the decrease in agricultural areas under the change of land use over two decades (1995–2017). The yearly changes or a shorter period of observations incorporated with the accurate land-use map in DRASTIC parameters could improve GV maps to obtain a better representation of site-specific conditions. Meanwhile, the maps of yearly contamination risk indicated that the counties of Jiuru and Ligang are at high risk of nitrate pollution since 2016. In other agriculture-dominated regions such as Yanpu, Changzhi, and Gaoshu in the Pingtung groundwater basin, the climate conditions influence less the temporal variations of groundwater contamination risk. The results of this study are expected to support policy-makers to adopt the strategies of sustainable development for groundwater resources in local areas.

ACS Style

Tien-Duc Vu; Chuen-Fa Ni; Wei-Ci Li; Minh-Hoang Truong. Modified Index-Overlay Method to Assess Spatial–Temporal Variations of Groundwater Vulnerability and Groundwater Contamination Risk in Areas with Variable Activities of Agriculture Developments. Water 2019, 11, 2492 .

AMA Style

Tien-Duc Vu, Chuen-Fa Ni, Wei-Ci Li, Minh-Hoang Truong. Modified Index-Overlay Method to Assess Spatial–Temporal Variations of Groundwater Vulnerability and Groundwater Contamination Risk in Areas with Variable Activities of Agriculture Developments. Water. 2019; 11 (12):2492.

Chicago/Turabian Style

Tien-Duc Vu; Chuen-Fa Ni; Wei-Ci Li; Minh-Hoang Truong. 2019. "Modified Index-Overlay Method to Assess Spatial–Temporal Variations of Groundwater Vulnerability and Groundwater Contamination Risk in Areas with Variable Activities of Agriculture Developments." Water 11, no. 12: 2492.

Article
Published: 18 January 2019 in Environmental Monitoring and Assessment
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This study employed experimental and numerical methods to assess the behavior of conservative solute transport for a selected temporary solid waste site in a reclamation area in western Taiwan. Calibrating a site-specific numerical model, finite element model of water flow through saturated-unsaturated media (FEMWATER), relies on observations from field- and laboratory-scale hydraulic tests and spatial-temporal monitoring. The field-scale experiment used a modified hydraulic tomography survey (MHTS) to identify near surface aquifer stratifications and estimate the distribution of saturated hydraulic conductivity. The pressure plate experiments provided parameters for the van Genuchten soil characteristic model. Sensitivity analyses were then conducted based on varied recharge rates and dispersivities applied to the calibrated model. Observations of groundwater levels and salinity in the wells indicated that the regional groundwater flow was from southeast to northwest. In addition, a shallow freshwater layer was noted in the study area. The tidal-induced amplitudes for water level fluctuation in the wells ranged from 2 to 20 cm, depending on their distance from the seawater body. MHTS showed clear stratification, similar to that of well loggings at the storage site. The hydraulic conductivity at the test site ranged from 8 to 10 m/day, which is close to that obtained from the laboratory falling head test. The results of particle-tracking modeling showed that the critical recharge rate for the site needed to enhance plume traveling is 1000 mm/year. The increase in dispersivity values induced a decrease in plume travel time of up to 1000 days from the site to the coastal line. A special case for pulse releasing solute at the site shows that the key factor in controlling plume migration is the recharge rate. This is due to the low natural head gradient in the reclamation area. The results therefore suggest that a land drainage system near the site can play an important role in contaminant transport in the reclamation area.

ACS Style

Chuen-Fa Ni; Wei-Ci Li; Shaohua Marko Hsu; I-Hsien Lee; Chi-Ping Lin. Numerical assessments of recharge-dominated groundwater flow and transport in the nearshore reclamation area in western Taiwan. Environmental Monitoring and Assessment 2019, 191, 83 .

AMA Style

Chuen-Fa Ni, Wei-Ci Li, Shaohua Marko Hsu, I-Hsien Lee, Chi-Ping Lin. Numerical assessments of recharge-dominated groundwater flow and transport in the nearshore reclamation area in western Taiwan. Environmental Monitoring and Assessment. 2019; 191 (2):83.

Chicago/Turabian Style

Chuen-Fa Ni; Wei-Ci Li; Shaohua Marko Hsu; I-Hsien Lee; Chi-Ping Lin. 2019. "Numerical assessments of recharge-dominated groundwater flow and transport in the nearshore reclamation area in western Taiwan." Environmental Monitoring and Assessment 191, no. 2: 83.

Journal article
Published: 02 January 2019 in Hydrology and Earth System Sciences
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This study presents the stochastic Monte Carlo simulation (MCS) to assess the uncertainty of flow and conservative transport in 3-D discrete fracture networks (DFNs). The MCS modeling workflow involves a number of developed modules, including a DFN generator, a DFN mesh generator, and a finite element model for solving steady-state flow and conservative transport in 3-D DFN realizations. The verification of the transport model relies on the comparison of transport solutions obtained from HYDROGEOCHEM model and an analytical model. Based on 500 DFN realizations in the MCS, the study assesses the effects of fracture intensities on the variation of equivalent hydraulic conductivity and the exhibited behaviors of concentration breakthrough curves (BTCs) in fractured networks. Results of the MCS show high variations in head and Darcy velocity near the specified head boundaries. There is no clear stationary region obtained for the head variance. However, the transition zones of nonstationarity for x-direction Darcy velocity is obvious, and the length of the transition zone is found to be close to the value of the mean fracture diameter for the DFN realizations. The MCS for DFN transport indicates that a small sampling volume in DFNs can lead to relatively high values of mean BTCs and BTC variations.

ACS Style

I-Hsien Lee; Chuen-Fa Ni; Fang-Pang Lin; Chi-Ping Lin; Chien-Chung Ke. Stochastic modeling of flow and conservative transport in three-dimensional discrete fracture networks. Hydrology and Earth System Sciences 2019, 23, 19 -34.

AMA Style

I-Hsien Lee, Chuen-Fa Ni, Fang-Pang Lin, Chi-Ping Lin, Chien-Chung Ke. Stochastic modeling of flow and conservative transport in three-dimensional discrete fracture networks. Hydrology and Earth System Sciences. 2019; 23 (1):19-34.

Chicago/Turabian Style

I-Hsien Lee; Chuen-Fa Ni; Fang-Pang Lin; Chi-Ping Lin; Chien-Chung Ke. 2019. "Stochastic modeling of flow and conservative transport in three-dimensional discrete fracture networks." Hydrology and Earth System Sciences 23, no. 1: 19-34.

Preprint content
Published: 07 November 2018
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ACS Style

Chuen-Fa Ni. Response to Reviewer #2. 2018, 1 .

AMA Style

Chuen-Fa Ni. Response to Reviewer #2. . 2018; ():1.

Chicago/Turabian Style

Chuen-Fa Ni. 2018. "Response to Reviewer #2." , no. : 1.

Preprint content
Published: 07 November 2018
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ACS Style

Chuen-Fa Ni. Response to Reviewer #1. 2018, 1 .

AMA Style

Chuen-Fa Ni. Response to Reviewer #1. . 2018; ():1.

Chicago/Turabian Style

Chuen-Fa Ni. 2018. "Response to Reviewer #1." , no. : 1.

Preprint content
Published: 21 August 2018
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This study presents the stochastic Monte Carlo simulation (MCS) to assess the uncertainty of flow and conservative transport in 3D discrete fracture networks (DFNs). The MCS modeling workflow involves a number of developed modules, including a DFN generator, a DFN mesh generator, and a finite element model for solving steady-state flow and conservative transport in 3D DFN realizations. The verification of the transport model relies on the comparison of transport solutions obtained from HYDROGEOCHEM model and an analytical model. Based on 500 DFN realizations in the MCS, the study assesses the effects of fracture intensities on the variation of equivalent hydraulic conductivity and the exhibited behaviors of concentration breakthrough curves (BTCs) in fractured networks. Results of the MCS show high variations in head and Darcy velocity near the specified head boundaries. There is no clear stationary region obtained for the head variance. However, the transition zones of nonstationarity for x-direction Darcy velocity is obvious and the length of the transition zone is found to be close to the value of the mean fracture diameter for the DFN realizations. The MCS for DFN transport indicates that a small sampling volume in DFNs can lead to relatively high values of mean BTCs and BTC variations.

ACS Style

I.-Hsien Lee; Chuen-Fa Ni; Fang-Pang Lin; Chi-Ping Lin; Chien-Chung Ke. Stochastic modeling of flow and conservative transport in threedimensional discrete fracture networks. 2018, 2018, 1 -31.

AMA Style

I.-Hsien Lee, Chuen-Fa Ni, Fang-Pang Lin, Chi-Ping Lin, Chien-Chung Ke. Stochastic modeling of flow and conservative transport in threedimensional discrete fracture networks. . 2018; 2018 ():1-31.

Chicago/Turabian Style

I.-Hsien Lee; Chuen-Fa Ni; Fang-Pang Lin; Chi-Ping Lin; Chien-Chung Ke. 2018. "Stochastic modeling of flow and conservative transport in threedimensional discrete fracture networks." 2018, no. : 1-31.

Journal article
Published: 20 August 2018 in Remote Sensing
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This study proposes a workflow that enables the accurate identification of earthquake-induced damage zones by using coherence image pairs of the Sentinel-1 satellite before and after an earthquake event. The workflow uses interferometric synthetic aperture radar (InSAR) processing to account for coherence variations between coseismic and preseismic image pairs. The coherence difference between two image pairs is useful information to detect specific disasters in a regional-scale area after an earthquake event. To remove background effects such as the atmospheric effect and ordinal surface changes, this study employs the two-step threshold method to develop the coseismic coherence difference (CCD) map for our analyses. Thirty-four Sentinel-1 images between January 2015 and February 2016 were collected to process 30 preseismic image pairs and two coseismic image pairs for assessing multiple types of disasters in Tainan City of southwestern Taiwan, where severe damages were observed after the Meinong earthquake event. The coseismic unwrapping phases were further calculated to estimate the surface displacement in east-west and vertical directions. Results in the CCD map agree well with the observations from post-earthquake field surveys. The workflow can accurately identify earthquake-induced land subsidence and surface displacements, even for areas with insufficient geological data or for areas that had been excluded from the liquefaction potential map. In addition, the CCD details the distribution of building damages and structure failures, which might be useful information for emergency actions applied to regional-scale problems. The conversion of 2D surface displacement reveals the complex behavior of geological activities during the earthquake. In the foothill area of Tainan City, the opposite surface displacements in local areas might be influenced by the axis activities of the Kuanmiao syncline.

ACS Style

Chih-Heng Lu; Chuen-Fa Ni; Chung-Pai Chang; Jiun-Yee Yen; Ray Y. Chuang. Coherence Difference Analysis of Sentinel-1 SAR Interferogram to Identify Earthquake-Induced Disasters in Urban Areas. Remote Sensing 2018, 10, 1318 .

AMA Style

Chih-Heng Lu, Chuen-Fa Ni, Chung-Pai Chang, Jiun-Yee Yen, Ray Y. Chuang. Coherence Difference Analysis of Sentinel-1 SAR Interferogram to Identify Earthquake-Induced Disasters in Urban Areas. Remote Sensing. 2018; 10 (8):1318.

Chicago/Turabian Style

Chih-Heng Lu; Chuen-Fa Ni; Chung-Pai Chang; Jiun-Yee Yen; Ray Y. Chuang. 2018. "Coherence Difference Analysis of Sentinel-1 SAR Interferogram to Identify Earthquake-Induced Disasters in Urban Areas." Remote Sensing 10, no. 8: 1318.

Article
Published: 23 March 2018 in Journal of Radioanalytical and Nuclear Chemistry
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Diffusion characteristics in bentonite are essential to quantify the transport of radionuclides through buffer/backfill materials in waste repositories. This study employs through-diffusion techniques to investigate the diffusion behavior of 99TcO4− through SPV bentonite with various densities. The apparent diffusion coefficients for bentonite densities are estimated using Marquardt–Levenberg optimization algorithm in the HYDRUS-1D model. Based on the experimental and calculation results, 99Tc could be considered as non-sorbing radionuclides. The data obtained in this study provide a valuable reference for the safety assessment of waste repositories.

ACS Style

Yu-Hung Shih; I-Hsien Lee; Chuen-Fa Ni; Tsuey-Lin Tsai; Liang-Cheng Chen; Chuan-Pin Lee; Shih-Chin Tsai; Te-Yen Su. Experimental and numerical investigations of 99TcO4− diffusion in compacted SPV 200 bentonite. Journal of Radioanalytical and Nuclear Chemistry 2018, 316, 1081 -1089.

AMA Style

Yu-Hung Shih, I-Hsien Lee, Chuen-Fa Ni, Tsuey-Lin Tsai, Liang-Cheng Chen, Chuan-Pin Lee, Shih-Chin Tsai, Te-Yen Su. Experimental and numerical investigations of 99TcO4− diffusion in compacted SPV 200 bentonite. Journal of Radioanalytical and Nuclear Chemistry. 2018; 316 (3):1081-1089.

Chicago/Turabian Style

Yu-Hung Shih; I-Hsien Lee; Chuen-Fa Ni; Tsuey-Lin Tsai; Liang-Cheng Chen; Chuan-Pin Lee; Shih-Chin Tsai; Te-Yen Su. 2018. "Experimental and numerical investigations of 99TcO4− diffusion in compacted SPV 200 bentonite." Journal of Radioanalytical and Nuclear Chemistry 316, no. 3: 1081-1089.

Proceedings article
Published: 01 January 2018
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ACS Style

Yu-Huan Chang; Graduate Institute of Applied geology; Chuen-Fa Ni; Chih-Yi Chen; Chun-Yu Yang; I-Hsien Lee; Che-Ping Lin; Wi-Ki Li. CHARACTERIZE PREFERENTIAL FLOW PATHS AND HEAT TRANSPORT IN A SHALLOW AQUIFER SYSTEM BY UTILIZE HYDRAULIC AND HEAT TRACER TESTS. 2018, 1 .

AMA Style

Yu-Huan Chang, Graduate Institute of Applied geology, Chuen-Fa Ni, Chih-Yi Chen, Chun-Yu Yang, I-Hsien Lee, Che-Ping Lin, Wi-Ki Li. CHARACTERIZE PREFERENTIAL FLOW PATHS AND HEAT TRANSPORT IN A SHALLOW AQUIFER SYSTEM BY UTILIZE HYDRAULIC AND HEAT TRACER TESTS. . 2018; ():1.

Chicago/Turabian Style

Yu-Huan Chang; Graduate Institute of Applied geology; Chuen-Fa Ni; Chih-Yi Chen; Chun-Yu Yang; I-Hsien Lee; Che-Ping Lin; Wi-Ki Li. 2018. "CHARACTERIZE PREFERENTIAL FLOW PATHS AND HEAT TRANSPORT IN A SHALLOW AQUIFER SYSTEM BY UTILIZE HYDRAULIC AND HEAT TRACER TESTS." , no. : 1.

Journal article
Published: 01 January 2017 in Terrestrial, Atmospheric and Oceanic Sciences
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We established a stress-history-dependent porosity model of potential target rocks for CO2 geosequestration based on rock sample porosity measurements...

ACS Style

Wen-Jie Wu; Jia-Jyun Dong; Andrew Tien-Shun Lin; Yun-Chen Yu; Tsun-You Pan; Lun-Tao Tong; Ming-Hsu Li; Chuen-Fa Ni; Toshihiko Shimamoto. Stress history influence on sedimentary rock porosity estimates: Implications for geological CO2 storage in Northern Taiwan. Terrestrial, Atmospheric and Oceanic Sciences 2017, 28, 247 -258.

AMA Style

Wen-Jie Wu, Jia-Jyun Dong, Andrew Tien-Shun Lin, Yun-Chen Yu, Tsun-You Pan, Lun-Tao Tong, Ming-Hsu Li, Chuen-Fa Ni, Toshihiko Shimamoto. Stress history influence on sedimentary rock porosity estimates: Implications for geological CO2 storage in Northern Taiwan. Terrestrial, Atmospheric and Oceanic Sciences. 2017; 28 (3):247-258.

Chicago/Turabian Style

Wen-Jie Wu; Jia-Jyun Dong; Andrew Tien-Shun Lin; Yun-Chen Yu; Tsun-You Pan; Lun-Tao Tong; Ming-Hsu Li; Chuen-Fa Ni; Toshihiko Shimamoto. 2017. "Stress history influence on sedimentary rock porosity estimates: Implications for geological CO2 storage in Northern Taiwan." Terrestrial, Atmospheric and Oceanic Sciences 28, no. 3: 247-258.

Journal article
Published: 22 April 2016 in Environmental Monitoring and Assessment
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This paper presents numerical investigations on quantifying the hydrodynamic effects of coastal environment factors, including tidal fluctuations, beach slopes, hydraulic conductivity, and hydraulic gradients on sea-derived benzene transport in unconfined coastal aquifers. A hydrologic transport and mixed geochemical kinetic/equilibrium reactions in saturated–unsaturated media model was used to simulate the spatial and temporal behaviors of the density flow and benzene transport for various hydrogeological conditions. Simulation results indicated that the tidal fluctuations lead to upper saline plumes (USPs) near the groundwater and seawater interfaces. Such local circulation zones trapped the seaward benzene plumes and carried them down in aquifers to the depth depending on the tide amplitudes and beach slopes across the coastal lines. Comparisons based on different tidal fluctuations, beach slopes, hydraulic conductivity, and hydraulic gradient were systematically conducted and quantified. The results indicated that areas with USPs increased with the tidal amplitude and decreased with the increasing beach slope. However, the variation of hydraulic conductivity and hydraulic gradient has relatively small influence on the patterns of flow fields in the study. The increase of the USP depths was linearly correlated with the increase of the tidal amplitudes. The benzene reactive transport simulations revealed that the plume migrations are mainly controlled by the local flow dynamics and constrained in the USP circulation zones. The self-cleaning process of a coastal aquifer is time-consuming, typically requiring double the time of the contamination process that the benzene plume reach the bottom of a USP circulation zone. The presented systematic analysis can provide useful information for rapidly evaluating seaward contaminants along a coastal line with available hydrogeological properties.

ACS Style

Wei-Ci Li; Chuen-Fa Ni; Chia-Hsing Tsai; Yi-Ming Wei. Effects of hydrogeological properties on sea-derived benzene transport in unconfined coastal aquifers. Environmental Monitoring and Assessment 2016, 188, 1 .

AMA Style

Wei-Ci Li, Chuen-Fa Ni, Chia-Hsing Tsai, Yi-Ming Wei. Effects of hydrogeological properties on sea-derived benzene transport in unconfined coastal aquifers. Environmental Monitoring and Assessment. 2016; 188 (5):1.

Chicago/Turabian Style

Wei-Ci Li; Chuen-Fa Ni; Chia-Hsing Tsai; Yi-Ming Wei. 2016. "Effects of hydrogeological properties on sea-derived benzene transport in unconfined coastal aquifers." Environmental Monitoring and Assessment 188, no. 5: 1.

Journal article
Published: 22 February 2016 in Pure and Applied Geophysics
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Electrical Resistivity Imaging (ERI) was carried out continuously for 10 days to map the subsurface resistivity distribution along a potentially hazardous hillslope at the Jieshou Junior High School in Taoyuan, Taiwan. The reliability of the inverted resistivity structures down to about 25 m depth was examined with synthetic modeling using the same electrode arrangements installed on land surface as in field surveys, together with a DOI (depth-of-investigation) index calculated from the ERI data. The subsurface resistivity distribution is consistent with results from well logging. These ERI recordings were taken daily and provided highly resolved imagery of the resistivity distribution underground and illustrated the dynamical fluid-flow behavior due to heavy rainfall infiltration. Using Archie’s law, the resistivity distribution was transformed into a map of relative water saturation (RWS), which is strongly correlated with the rainfall infiltration process. We then found that the averaged RWS is significantly correlated with daily precipitation. Our observations indicate that time-lapse ERI is effective in monitoring subterraneous rainfall infiltration; moreover, the preferential flow paths can be delineated according to the changes in averaged RWS derived from the ERI data.

ACS Style

Gang Zhang; Gui-Bin Zhang; Chien-Chih Chen; Ping-Yu Chang; Tzu-Pin Wang; Horng-Yuan Yen; Jia-Jyun Dong; Chuen-Fa Ni; Su-Chin Chen; Chao-Wei Chen; Zheng-Yuan Jia. Imaging Rainfall Infiltration Processes with the Time-Lapse Electrical Resistivity Imaging Method. Pure and Applied Geophysics 2016, 173, 2227 -2239.

AMA Style

Gang Zhang, Gui-Bin Zhang, Chien-Chih Chen, Ping-Yu Chang, Tzu-Pin Wang, Horng-Yuan Yen, Jia-Jyun Dong, Chuen-Fa Ni, Su-Chin Chen, Chao-Wei Chen, Zheng-Yuan Jia. Imaging Rainfall Infiltration Processes with the Time-Lapse Electrical Resistivity Imaging Method. Pure and Applied Geophysics. 2016; 173 (6):2227-2239.

Chicago/Turabian Style

Gang Zhang; Gui-Bin Zhang; Chien-Chih Chen; Ping-Yu Chang; Tzu-Pin Wang; Horng-Yuan Yen; Jia-Jyun Dong; Chuen-Fa Ni; Su-Chin Chen; Chao-Wei Chen; Zheng-Yuan Jia. 2016. "Imaging Rainfall Infiltration Processes with the Time-Lapse Electrical Resistivity Imaging Method." Pure and Applied Geophysics 173, no. 6: 2227-2239.

Journal article
Published: 01 January 2016 in Terrestrial, Atmospheric and Oceanic Sciences
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This study simulated the natural convection of dissolved carbon dioxide (CO2) in a small-scale heterogeneous saline formation using the state module E...

ACS Style

Chi-Ping Lin; Chuen-Fa Ni; I-Hsien Lee; Wei-Ci Li. Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations. Terrestrial, Atmospheric and Oceanic Sciences 2016, 27, 121 .

AMA Style

Chi-Ping Lin, Chuen-Fa Ni, I-Hsien Lee, Wei-Ci Li. Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations. Terrestrial, Atmospheric and Oceanic Sciences. 2016; 27 (1):121.

Chicago/Turabian Style

Chi-Ping Lin; Chuen-Fa Ni; I-Hsien Lee; Wei-Ci Li. 2016. "Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations." Terrestrial, Atmospheric and Oceanic Sciences 27, no. 1: 121.