Zhu etal SI FINE

Journal of Hydrology, 2014

We present a numerical study keyed to the analysis of the impact on hydraulic head statistics of two selected methodologies for the stochastic simulation of hydro-facies spatial arrangement. We analyze the distribution of hydraulic heads in a confined aquifer under steady-state convergent three-dimensional flow to a fully penetrating well, superimposed to a mean uniform regional gradient. The heterogeneous structure of the system is modeled on the basis of available field information comprising detailed lithological data collected within an aquifer system located in northern Italy. These data are grouped into five litho-type categories and the aquifer system is modeled as a random composite medium. Monte Carlo realizations of the three-dimensional geo-material distributions are generated through the Sequential Indicator and the Truncated Plurigaussian Simulation methods. The latter enables one to integrate geological conceptual information in the simulation procedure, while the former relies mainly on a variogram-based analysis. Point and vertically averaged hydraulic heads, corresponding to typical observations collected within screened boreholes, are analyzed by evaluating the dependence of their sample probability distributions on (i) the hydro-facies generation scheme, (ii) the extent of the vertical averaging interval and (iii) the relative distance between the location of observation boreholes, hydrological boundaries and the source term. Theoretical probability density function models are fitted against numerically simulated distributions within a maximum likelihood context. Our results indicate that hydraulic heads associated with the Truncated Plurigaussian Simulation method exhibit increased variability when compared to their counterparts evaluated upon relying on a Sequential Indicator based modeling strategy of the system heterogeneity. Covariance matrices and probability distributions of point and vertically averaged hydraulic heads display similar key representative features and patterns. This suggests that typical measurements collected in screened boreholes can be used to infer qualitative information about the correlation structure and the statistical properties of heads.

2013

S4.11. Graph showing steady-state groundwater-flow model results shown as observed and simulated potentiometric levels, and observed potentiometric levels and corresponding residuals, steady-state groundwater-flow model calibration, Hadnot Point-Holcomb Boulevard study area, U.

Research Journal of Environmental and Earth Sciences, 2013

A physically-based model namely the Soil Water Assessment Tool (SWAT) was used on the Roodan watershed in southern part of Iran; the watershed has an area of 10570 km2. The main objectives were to simulate monthly discharge and evaluate the base and peak flows separately. Required parameters to run the model were meteorological data, soil type, land use, management practices and topography maps at watershed scale. To find the sensitive parameters, an initial sensitivity analysis was performed using the Latin Hypercube sampling One-at-A-Time (LH-OAT) method embedded in the SWAT model. Then, the model was calibrated and validated for stream flow using the SWAT-CUP program. Generally, the model was assessed using the modified coefficient of determination (bR2), Nash-Sutcliffe (NS) and PBIAS. Values of bR2 and NS were 0.93 and 0.92 for calibration respectively and 0.69 and 0.83, respectively, for validation. For calibration and validation, PBIAS were obtained at 23 and 5%, respectively. Reviewing the results, it seems that simulation of the monthly peak flows has better harmony (fluctuation) than monthly base flows for Roodan watershed. To summarize, the simulated SWAT stream flow was within the acceptable range for Roodan watershed as an arid catchment.

Water Resources Research, 2003

1] This work highlights the lack of unique solutions for regional groundwater flow models and quantifies the degree of freedom concerning hydraulic conductivities for models calibrated on measured hydraulic heads. The potential of 4 He as an independent tracer at reducing the nonuniqueness problem is tested. Four different calibrated groundwater flow scenarios are presented for the Carrizo aquifer and surrounding formations in Texas. It is shown that variations of hydraulic conductivities up to 2 orders of magnitude in the Carrizo aquifer and overlying confining layer lead to similar calculated hydraulic heads. No clear-cut arguments are present to invalidate one groundwater flow scenario over a different one. In contrast, when tested with a 4 He transport conceptual model, all groundwater flow scenarios except one failed to reproduce a coherent 4 He transport behavior in the system. This study exemplifies possible future contributions of 4 He at discerning which model most closely replicates natural conditions. Citation: Castro, M. C., and P. Goblet, Calibration of regional groundwater flow models: Working toward a better understanding of site-specific systems, Water Resour.

2003

(PNNL) have embarked upon a new initiative designed to strengthen the technical defensibility of the groundwater flow and transport model at the Hanford Site in Southeast Washington State and to develop a more robust capability to incorporate uncertainty into the model. One aspect of the initiative is developing and using a three-dimensional transient inverse modeling approach to estimate the hydraulic conductivities, specific yields, and other site-wide scale parameters that incorporates data on the transient behavior of the unconfined aquifer system resulting from Hanford Site waste management since 1943. Over the historical period of Hanford operations, the large volumes of wastewater discharged to a variety of waste facilities resulted in large water table changes over most of the Hanford Site and created significant groundwater mounds (in excess of 20 m) under waste management facilities in the central part of the site. Since 1988, the mission of the Hanford Site has changed from producing weapons to restoring the environment. Thus wastewater discharges have declined significantly, which has caused significant water table declines. The three-dimensional transient inverse calibration, which an external peer review panel recommended to DOE, is being performed using UCODE, a universal inverse modeling code developed jointly by the U.S. Geological Survey and the International Groundwater Modeling Center of the Colorado School of Mines. The work uses the existing consolidated site-wide groundwater model (SGM) implemented with the Coupled Fluid Energy and Solute Transport (CFEST) code, which is the forward model whose parameters are estimated by UCODE. The transient inverse calibration uses approximately 70,000 water level measurements made at the Hanford Site since the mid-1940s. Compared with the prior model, the initial baseline transient inverse calibration effort (Cole et al. 2001a) significantly improved the ability of the baseline model to simulate historical trends in water table changes over the entire site for the 1943-1996 period of calibration. Most notably improved were the historical trends of water table changes and mound building observed near major discharge facilities in the 200 West Area. The focus of the inverse modeling initiative in the following year (Vermeul et al. 2001) was to use the developed inverse calibration methodology to test an alternative conceptual model (ACM-1) that no longer considered the underlying basalt bedrock system the no-flow base of the unconfined aquifer system as it had in the past. This alternative SGM model was used to examine and evaluate a variety of mechanisms that affect intercommunication between the Hanford Site unconfined aquifer system and the underlying upper basalt-confined aquifer system. The focus of the ACM-2 inverse modeling initiative, as documented in this report, has been to 1) address data and model implementation limitations identified in the ACM-1 model, 2) complete the implementation and evaluation of the facies-based approach for representing the hydraulic conductivity distribution in both the Hanford and middle Ringold Formations, 3) develop the approach and implementation methodology for generating multiple ACMs of Unit 1 zonation and Ringold mud unit distribution based on geostatistical data analysis, and 4) develop an approach for inverse modeling of these stochastic ACMs. The ACM-2 transient inverse model was developed to test the SGM that incorporates conceptual model modifications that were identified for investigation based on knowledge gained during previous inverse calibration efforts. The primary modifications incorporated into ACM-2 that were not in Hydraulic conductivity of conductive units: In general, the solution was sensitive to the hydraulic conductivity of the more conductive units. The only permeable units not determinable by the inverse were Ringold Units 7 and 9, which are moderately permeable and situated deeper in the profile, where fewer observational data are available. Hydraulic conductivity of the Ringold mud units: The solution was sensitive to the hydraulic conductivity of the lower-conductivity, slightly more extensive mud unit (Unit 8) and insensitive to Unit 6. Because of the limited saturated extent of the upper Ringold mud (Unit 4), this parameter was not included in the inverse. Vertical hydraulic conductivity of underlying basalt layer: The solution was sensitive to this parameter, which affects basalt leakage. Features associated with increased basalt leakage: In general, hydraulic conductivity associated with head-dependent flux boundaries at the erosional window and thrust fault was insensitive. One exception was a section of fault in Cold Creek Valley upgradient of the Cold Creek flow impediment. High basalt heads upgradient of this feature are the primary reason for the solution's increased sensitivity to hydraulic conductivity, controlling leakage over this section of the thrust fault. Specific yield of the conductive units containing the water table: The solution was generally insensitive to all tested specific-yield parameter values. The specific yield of several facies of the Hanford and Ringold formations across the 200 Area plateau, where the largest amount of groundwater mound buildup occurs, however, were marginally sensitive for a limited time during the inverse process but became insensitive as the inverse progressed. Anisotropy ratio of all conductive hydrogeologic units: The solution was insensitive to all anisotropy parameters. Components of surface recharge: The solution was insensitive to areally distributed surface recharge but sensitive to run-on recharge from Cold Creek, Dry Creek, and Rattlesnake Hills.

Water Resources Research, 2003

1] Analytic relations between input parameters, output variables, and statistics for confidence are derived for semiconfined groundwater flow in a circular domain around a well. The statistics of the two calibrated parameters are derived analytically using a least squares target function. The statistics of the piezometric head are approximated using linear variance analysis (LVA, also known as first-order second moment method (FOSM)) and quadratic variance analysis (QVA). LVA values for the capture zone radius have been calculated based on numerical derivatives. The results are used to verify TrCalCon, the calibration and confidence module of the groundwater flow simulation package TRIWACO. The LVA and Monte Carlo (MC) results of TrCalCon compare well with the analytic LVA and QVA values, respectively. The problem is only weakly nonlinear in the heads, so that the LVA is accurate enough for practical purposes, and QVA or MC analysis would not be needed. The test can be applied as well to other groundwater simulation packages with a module for automatic parameter optimization and reliability analysis. As presented, the problem is quite simple, and the parameter optimization is relatively easy. The analysis can be expanded easily to make the problem more intricate by adding parameters, changing parameter values, and including other measurements.

Fourteen guidelines are described which are intended to produce calibrated groundwater models likely to represent the associated real systems more accurately than typically used methods. The 14 guidelines are discussed in the context of the calibration of a regional groundwater flow model of the Death Valley region in the southwestern United States. This groundwater flow system contains two sites of national significance from which the subsurface transport of contaminants could be or is of concern: Yucca Mountain, which is the potential site of the United States high-level nuclear-waste disposal; and the Nevada Test Site, which contains a number of underground nuclear-testing locations. This application of the guidelines demonstrates how they may be used for model calibration and evaluation, and also to direct further model development and data collection.

2020

The COVID-19 pandemic has a severe impact on education all over the world. The closures of educational institutions affected teaching and learning processes and had an impact on students’ motivation and engagement. In this context, AR/VR technology can provide assistance to students and support for educators. This paper presents a review of literature on augmented and virtual reality in educational settings in the last 5 years. In total 23 research studies were included in the study. Target group, field of education, reported advantages, limitations and concerns have been investigated and reported. The findings showed that students’ learning can benefit both technologies by increasing engagement, motivation, collaboration and learning achievement.

International Journal of Molecular Sciences, 2012

The Bridging Sheet domain of HIV-1 gp120 is highly conserved among the HIV-1 strains and allows HIV-1 binding to host cells via the HIV-1 coreceptors. Further, the bridging sheet domain is a major target to neutralize HIV-1 infection. We rationally designed four linear peptide epitopes that mimic the three-dimensional structure of bridging sheet by using molecular modeling. Chemically synthesized peptides BS3 and BS4 showed a fair degree of antigenicity when tested in ELISA with IgG purified from HIV + broadly neutralizing sera while the production of synthetic peptides BS1 and BS2 failed due to their high degree of hydrophobicity. To overcome this limitation, we linked all four BS peptides to the COOH-terminus of GST protein to test both their antigenicity and immunogenicity. Only the BS1 peptide showed good antigenicity; however, no envelope specific antibodies were elicited upon mice immunization. Therefore we performed further analyses by linking BS1 peptide to the NH2-terminus of the E2 scaffold from the Geobacillus Stearothermophylus PDH complex. The E2-BS1 fusion peptide showed good antigenic results, however only one immunized rabbit elicited good antibody titers towards both the monomeric and oligomeric viral envelope glycoprotein (Env). In addition, moderate neutralizing antibodies response was elicited against two HIV-1 clade B and one clade C primary isolates. These preliminary data validate the peptide mimotope approach as a promising tool to obtain an effective HIV-1 vaccine.