Journal: Advances in Water Resources

Abbreviation

Adv. Water Resour.

Publisher

Elsevier

Journal Volumes

ISSN

0309-1708
1872-9657

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Publications 1 - 10 of 85
  • Fostering cooperation in power asymmetrical water systems by the use of direct release rules and index-based insurance schemes
    Item type: Journal Article
    Denaro, Simona; Castelletti, Andrea; Giuliani, Matteo; et al. (2018)
    Advances in Water Resources
  • Ekman circulation and downwelling in narrow lakes
    Item type: Journal Article
    Toffolon, Marco (2013)
    Advances in Water Resources
  • An enhanced temperature index model for debris-covered glaciers accounting for thickness effect
    Item type: Journal Article
    Carenzo, Marco; Pellicciotti, Francesca; Mabillard, Johan; et al. (2016)
    Advances in Water Resources
    Debris-covered glaciers are increasingly studied because it is assumed that debris cover extent and thickness could increase in a warming climate, with more regular rockfalls from the surrounding slopes and more englacial melt-out material. Debris energy-balance models have been developed to account for the melt rate enhancement/reduction due to a thin/thick debris layer, respectively. However, such models require a large amount of input data that are not often available, especially in remote mountain areas such as the Himalaya, and can be difficult to extrapolate. Due to their lower data requirements, empirical models have been used extensively in clean glacier melt modelling. For debris-covered glaciers, however, they generally simplify the debris effect by using a single melt-reduction factor which does not account for the influence of varying debris thickness on melt and prescribe a constant reduction for the entire melt across a glacier. In this paper, we present a new temperature-index model that accounts for debris thickness in the computation of melt rates at the debris-ice interface. The model empirical parameters are optimized at the point scale for varying debris thicknesses against melt rates simulated by a physically-based debris energy balance model. The latter is validated against ablation stake readings and surface temperature measurements. Each parameter is then related to a plausible set of debris thickness values to provide a general and transferable parameterization. We develop the model on Miage Glacier, Italy, and then test its transferability on Haut Glacier d’Arolla, Switzerland. The performance of the new debris temperature-index (DETI) model in simulating the glacier melt rate at the point scale is comparable to the one of the physically based approach, and the definition of model parameters as a function of debris thickness allows the simulation of the nonlinear relationship of melt rate to debris thickness, summarised by the Østrem curve. Its large number of parameters might be a limitation, but we show that the model is transferable in time and space to a second glacier with little loss of performance. We thus suggest that the new DETI model can be included in continuous mass balance models of debris-covered glaciers, because of its limited data requirements. As such, we expect its application to lead to an improvement in simulations of the debris-covered glacier response to climate in comparison with models that simply recalibrate empirical parameters to prescribe a constant across glacier reduction in melt.
  • On the applicability of connectivity metrics to rough fractures under normal stress
    Item type: Journal Article
    Javanmard, Hoda; Saar, Martin O.; Vogler, Daniel (2022)
    Advances in Water Resources
    Rough rock fractures have complex geometries which result in highly heterogeneous aperture fields. To accurately estimate the permeability of such fractures, heterogeneity of the aperture fields must be quantified. In this study heterogeneity of single rough rock fractures is for the first time parametrized by connectivity metrics, which quantify how connected the bounds of a heterogeneous field are. We use 3000 individual realizations of synthetic aperture fields with different statistical parameters and compute three connectivity metrics based on percolation theory for each realization. The sensitivity of the connectivity metrics with respect to the determining parameter, i.e the cutoff threshold, is studied and the correlation between permeability of the fractures and the computed connectivity metrics is presented. The results show that the Θ connectivity metric predicts the permeability with higher accuracy. All three studied connectivity metrics provide better permeability estimations when a larger aperture value is chosen as the cutoff threshold. Overall, this study elucidates that using connectivity metrics provides a less expensive alternative to fluid flow simulations when an estimation of fracture permeability is desired.
  • Numerical modelling of river morphodynamics: Latest developments and remaining challenges
    Item type: Other Journal Item
    Siviglia, Annunziato; Crosato, Alessandra (2016)
    Advances in Water Resources
  • Measuring the effect of structural connectivity on the water dynamics in heterogeneous porous media using speedy neutron tomography
    Item type: Journal Article
    Schaap, J. D.; Lehmann, Peter; Kaestner, A.; et al. (2008)
    Advances in Water Resources
  • A stochastic model for air injection into saturated porous media
    Item type: Journal Article
    Stauffer, Fritz; Kong, Xiang-Zhao; Kinzelbach, Wolfgang (2009)
    Advances in Water Resources
  • A comparison of seven methods for the inverse modelling of groundwater flow
    Item type: Journal Article
    Hendricks Franssen, Harrie-Jan; Alcolea, A.; Riva, M.; et al. (2009)
    Advances in Water Resources
  • Improved pore network models to simulate single-phase flow in porous media by coupling with lattice Boltzmann method
    Item type: Journal Article
    Zhao, Jianlin; Qin, Feifei; Derome, Dominique; et al. (2020)
    Advances in Water Resources
    In this paper, different pore network models to simulate single-phase flow in porous media are built and their accuracy is evaluated. In addition to the conventional pore network model (CPNM) which consists of regular pore bodies and throat bonds, three improved pore network models (IPNMs) are developed allowing to better describing the real pore and throat geometry. The first improved pore network model (IPNM1) replaces the regular throat bond with a throat bond showing the real throat cross section. The second improvement (IPNM2) uses a series of sub-throat bonds with varying cross sections to better describe the real throat geometry, which is firstly proposed in this paper. The third model (IPNM3) extracts the real pore-throat-pore geometry without simplification. The conductance of fluid flow through these more realistic throat bonds is calculated by the lattice Boltzmann method (LBM). The accuracy and computational efficiency of the different pore network models are evaluated taking the LBM simulation over the whole porous medium as reference solution. The global permeability and detailed pressure distributions in the pores for the different pore network models are validated. The results show that the accuracy of the pore network model increases from CPNM to IPNM3, but at the expense of increasing computational cost. This study suggests that IPNM3 can replace a whole-domain LBM simulation with similar accuracy but much lower computational cost. As a first-order approximation the newly proposed IPNM2 is suggested as good compromise between accuracy and computational cost.
  • Infiltration through series of soil aggregates: Neutron radiography and modeling
    Item type: Journal Article
    Carminati, Andrea; Kaestner, Anders; Hassanein, René; et al. (2007)
    Advances in Water Resources
    Soils are often structured as fine-porous aggregates separated by large inter-aggregate pores. Under unsaturated conditions, water is mostly stored in the aggregates and water flow depends on the properties of the aggregates as well as on those of the contacts between aggregates. The goal of this study is to model and evaluate the hydraulic properties of the contacts. We used neutron radiography to monitor the infiltration of water through series of aggregates. The flow process was numerically simulated by considering the hydraulically conducting contact area between aggregates as a variable that depends on the capillary pressure. This contact area was evaluated by matching the observed and simulated water flow across aggregates. We determined the conductivity of the contacts assuming that it scales with the contact area. We also measured the equivalent conductivity of series of aggregates. We found that during drainage the hydraulically conducting contact area drastically decreases and the conductivity of the contacts becomes much smaller than that of the aggregates. We also found that the equivalent conductivity of the aggregate series decreases as the conductivity of the contacts. We concluded that the contacts control the flow: they are highly conductive when wet, but act as bottle-necks under drained conditions. The abrupt transition between these two limiting cases indicates that the contact region is more rapidly drained than the aggregate interior. Our findings might be extended to describe water transfer to an evaporating boundary, infiltration and storage of water in unsaturated aggregated soils.
Publications 1 - 10 of 85