Modeling flow and transport in unsaturated fractured rock: an evaluation of the continuum approach

Liu, Hui‐Hai; Haukwa, C.; Ahlers, C.F.; Bodvarsson, G.S.; Flint, Alan L.; Guertal, William B.

doi:10.1016/s0169-7722(02)00170-5

Cited by 66 publications

(54 citation statements)

References 19 publications

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“…Liu et al (1998) further assumed that van Genuchten (1980) relations are approximately valid for the active pore space. In a separate study, Liu et al (2003) reports values of porosity between 0.01 and 0.03 for the pore space used with the active fracture model.…”

Section: Particle Swarm Optimizationmentioning

confidence: 99%

A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

Brunetti

Šimůnek

Piro

2016

Journal of Hydrology

110

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a b s t r a c tThe increasing frequency of flooding events in urban catchments related to an increase in impervious surfaces highlights the inadequacy of traditional urban drainage systems. Low Impact Development (LID) techniques have proven to be a viable and effective alternative by reducing stormwater runoff and increasing the infiltration and evapotranspiration capacity of urban areas. However, the lack of adequate modeling tools represents a barrier in designing and constructing such systems. This paper investigates the suitability of a mechanistic model, HYDRUS-1D, to correctly describe the hydraulic behavior of permeable pavement installed at the University of Calabria. Two different scenarios of describing the hydraulic behavior of the permeable pavement system were analyzed: the first one uses a singleporosity model for all layers of the permeable pavement; the second one uses a dual-porosity model for the base and sub-base layers. Measured and modeled month-long hydrographs were compared using the Nash-Sutcliffe efficiency (NSE) index. A Global Sensitivity Analysis (GSA) followed by a Monte Carlo filtering highlighted the influence of the wear layer on the hydraulic behavior of the pavement and identified the ranges of parameters generating behavioral solutions. Reduced ranges were then used in the calibration procedure conducted with the metaheuristic Particle swarm optimization (PSO) algorithm for the estimation of hydraulic parameters. The best fit value for the first scenario was NSE = 0.43; for the second scenario, it was NSE = 0.81, indicating that the dual-porosity approach is more appropriate for describing the variably-saturated flow in the base and sub-base layers. Estimated parameters were validated using an independent, month-long set of measurements, resulting in NSE values of 0.43 and 0.86 for the first and second scenarios, respectively. The improvement in correspondence between measured and modeled hydrographs confirmed the reliability of the combination of GSA and PSO in dealing with highly dimensional optimization problems. Obtained results have demonstrated that PSO, due to its easiness of implementation and effectiveness, can represent a new and viable alternative to traditional optimization algorithms for the inverse estimation of unsaturated hydraulic properties. Finally, the results confirmed the suitability and the accuracy of HYDRUS-1D in correctly describing the hydraulic behavior of permeable pavements.

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Section: Particle Swarm Optimizationmentioning

confidence: 99%

A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

Brunetti

Šimůnek

Piro

2016

Journal of Hydrology

110

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“…The corroborative studies include simulations of percolation in the unsaturated zone below the root system, based on the Richards equation model (BSC 2003a), analysis of borehole temperature measurements , chloride (Liu et al 2003), and calcite (Paces et al 1996) data, groundwater recharge (Hevesi et al 2003), neutron logging of moisture content, and environmental tracers based on the age-dating information (USGS 200 1 b).…”

Section: A3 Responsementioning

confidence: 99%

“…Table A Because the water-balance model provides reasonable estimations of net infiltration in the shallow subsurface that fit those from multiple corroborative numerical and experimental investigations, there is no need now to initiate simulations of net infiltration in the shallow subsurface using the Richards equation. It is evident that if the Richards equation model applied for the simulation of net infiltration over the Yucca Mountain area, it would have generated reliable estimates of the spatial distribution of net infiltration, comparable to those used as an upper boundary condition in UZ Flow Models and Submodels (BSC 2003a;Liu et al 2003).…”

Section: A3 Responsementioning

confidence: 99%

“…The environmental conditions and the results of Alcove 1 infiltration tests are summarized in In Situ Field Testing of Processes (BSC 2003c, Table 4.1-12b, Table 6.12.5-1, Section 6.12.5.1) and by Liu et al (2003). Comparisons between experimental and modeling results for the infiltration rate ( Figure E-2), seepage rate ( Figure E-3), and tracer concentration ( Figure E-4) show that the continuum modeling approach captures essential features of flow and transport processes observed from the test (Liu et al 2003).…”

Section: E433 Data Availablementioning

confidence: 99%

“…They determined that the simulated net-infiltration volumes are in good agreement with the estimated recharge volumes, and the best fit of simulated and observed data corresponds to the net infiltration model that accounts for streamflow coupled to the root-zone component; this approach was used in the INFIL model for the determination of net infiltration. Validation Using Chloride Data-The results of simulation of net infiltration for the present-day conditions can be compared with those from calculations based on pore-water chloride data (Liu et al 2003). To assess the net infiltration distribution, the modeled area was divided into nine regions, according to the available chloride data, as well as hydrogeologic and hydrostructural features.…”

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Technical Basis Document No. 1: Climate and Infiltration

NA¹

2004

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Hydrologic issues associated with nuclear waste repositories

2015

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Significant progress in hydrology, especially in subsurface flow and solute transport, has been made over the last 35 years because of sustained interest in underground nuclear waste repositories. The present paper provides an overview of the key hydrologic issues involved, and to highlight advances in their understanding and treatment because of these efforts. The focus is not on the development of radioactive waste repositories and their safety assessment, but instead on the advances in hydrologic science that have emerged from such studies. Work and results associated with three rock types, which are being considered to host the repositories, are reviewed, with a different emphasis for each rock type. The first rock type is fractured crystalline rock, for which the discussion will be mainly on flow and transport in saturated fractured rock. The second rock type is unsaturated tuff, for which the emphasis will be on flow from the shallow subsurface through the unsaturated zone to the repository. The third rock type is clay-rich formations, whose permeability is very low in an undisturbed state. In this case, the emphasis will be on hydrologic issues that arise from mechanical and thermal disturbances; i.e., on the relevant coupled thermo-hydromechanical processes. The extensive research results, especially those from multiyear large-scale underground research laboratory investigations, represent a rich body of information and data that can form the basis for further development in the related areas of hydrologic research. General IntroductionSignificant progress in hydrology, especially in subsurface flow and solute transport, has been made over the last 35 years because of sustained interest in the performance assessment of proposed underground nuclear waste repositories. The present paper attempts to provide an overview of the key hydrologic issues involved and to highlight the advances in their understanding and treatment because of these efforts. This paper is not focused on the development of high-level nuclear waste repositories and their safety assessment; it focuses instead on the advances in hydrologic science which have emerged from such studies. These advances may find applications in other hydrology-related problems of current importance at the national and international levels, such as environmental contamination remediation, carbon dioxide geosequestration, and natural gas production through fracking.In the next section, we present, in a general way, the context for the hydrologic framework related to performance and safety assessment of underground nuclear waste repositories that are proposed to be constructed in three particular rock formations-crystalline rock, unsaturated tuffs, and clays. Then, we discuss some particularly challenging factors concerning the research common to these three formations. This discussion will be followed by three sections devoted to each of these three rock types, respectively, to present a review of hydrologic research in these areas.

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Modeling flow and transport in unsaturated fractured rock: an evaluation of the continuum approach

Cited by 66 publications

References 19 publications

A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

Technical Basis Document No. 1: Climate and Infiltration

Hydrologic issues associated with nuclear waste repositories

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