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Brunner, Philip

Nom
Brunner, Philip
Affiliation principale
Fonction
Professeur ordinaire
Email
philip.brunner@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/165
_
0000-0001-6304-6274

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  • Publication
    Accès libre
    Sources of Surface Water in Space and Time: Identification of Delivery Processes and Geographical Sources With Hydraulic Mixing-Cell Modeling
    (2021-10)
    Glaser, Barbara
    ;
    Hopp, Luisa
    ;
    Partington, Daniel
    ;
    Brunner, Philip 
    ;
    Therrien, René
    ;
    Klaus, Julian
    Knowledge of the sources of surface water in riparian zones and floodplains is critical to understanding its role in runoff generation and impact on biogeochemical and ecological processes. In this study, we demonstrate the potential of integrated surface-subsurface hydrologic modeling (HydroGeoSphere) in combination with a hydraulic mixing-cell approach to decipher different sources of surface water and their mixing in space and time. We present a novel approach to processing the model data that allowed us to compare which mechanisms ultimately transferred water to the surface (delivery processes) and from where the surface water originated (geographical sources) for varying wetness states and phases of wetting or drying across 36 test locations within the riparian-stream continuum of an intensively-studied, humid-temperate, forested headwater catchment (45 ha). Consistent with current process understanding for the study site, water exfiltrating from the subsurface was simulated as the dominant source for riparian surface water and intermittent streamflow. The model further helped to specify the relevance of different subsurface stores, revealing a wetness-dependent activation of upslope source areas. Contributions of riparian overland flow and precipitation were minor during all investigated phases of wetting and drying. Moreover, the spatial variability of surface water sources proved to be smaller than expected for the heterogeneous patterns and frequencies of the surface saturation observed and simulated. Based on these findings, we discuss the value of hydraulic mixing-cell modeling to complement the planning and interpretation of field investigations and to enhance process understanding regarding the spatio-temporal sources of surface water.
  • Publication
    Accès libre
    Commemorating the 50th anniversary of the Freeze and Harlan (1969) Blueprint for a physically-based, digitally-simulated hydrologic response model
    (2020-11)
    Simmons, Craig T.
    ;
    Brunner, Philip 
    ;
    Therrien, René
    ;
    Sudicky, Edward A.
    The year 2019 marks the 50th anniversary of a pioneering publication in hydrology. Allan Freeze and Richard Harlan published their Blueprint for a physically-based, digitally-simulated hydrologic response model (Freeze and Harlan, 1969) in this journal. Their vision was for a futuristic model that would integrate key processes and compartments in the hydrologic cycle: precipitation, evapotranspiration, overland runoff, infiltration and groundwater exchange (into and out of) surface water bodies, such as rivers and lakes. Today, the original Blueprint is a reality. Our paper commemorates the 50 year anniversary of the original Blueprint paper. Through personal communications with Allan Freeze, we document the history and genesis of this paper for the first time. We reflect on the uptake of the Blueprint into modern hydrology, the development of numerical models that enabled this, and the range of challenges being tackled by these models. Finally, we consider challenges and opportunities for the future of this area of modelling and hydrologic science.
  • Publication
    Accès libre
    Blueprint for a coupled model of sedimentology, hydrology, and hydrogeology in streambeds
    (2017-2)
    Partington, Daniel
    ;
    Therrien, René
    ;
    Simmons, Craig T.
    ;
    Brunner, Philip 
    The streambed constitutes the physical interface between the surface and the subsurface of a stream. Across all spatial scales, the physical properties of the streambed control surface water‐groundwater interactions. Continuous alteration of streambed properties such as topography or hydraulic conductivity occurs through erosion and sedimentation processes. Recent studies from the fields of ecology, hydrogeology, and sedimentology provide field evidence that sedimentological processes themselves can be heavily influenced by surface water‐groundwater interactions, giving rise to complex feedback mechanisms between sedimentology, hydrology, and hydrogeology. More explicitly, surface water‐groundwater exchanges play a significant role in the deposition of fine sediments, which in turn modify the hydraulic properties of the streambed. We explore these feedback mechanisms and critically review the extent of current interaction between the different disciplines. We identify opportunities to improve current modeling practices. For example, hydrogeological models treat the streambed as a static rather than a dynamic entity, while sedimentological models do not account for critical catchment processes such as surface water‐groundwater exchange. We propose a blueprint for a new modeling framework that bridges the conceptual gaps between sedimentology, hydrogeology, and hydrology. Specifically, this blueprint (1) fully integrates surface‐subsurface flows with erosion, transport, and deposition of sediments and (2) accounts for the dynamic changes in surface elevation and hydraulic conductivity of the streambed. Finally, we discuss the opportunities for new research within the coupled framework.
  • Publication
    Accès libre
    Channel Representation in Physically Based Models Coupling Groundwater and Surface Water: Pitfalls and How to Avoid Them
    (2014-5-18)
    Käser, Daniel
    ;
    Graf, Tobias
    ;
    Cochand, Fabien
    ;
    McLaren, Rob
    ;
    Therrien, René
    ;
    Brunner, Philip 
  • Publication
    Accès libre
    Interpreting streamflow generation mechanisms from integrated surface subsurface flow models of a riparian wetland and catchment
    (2013-5-18)
    Joseph Partington, Daniel 
    ;
    Brunner, Philip 
    ;
    Frei, S.
    ;
    Simmons, Craig Trevor
    ;
    Werner, AD
    ;
    Therrien, René
    ;
    Maier, Holger Robert
    ;
    Dandy, Graeme Clyde
    ;
    Fleckenstein, JH
  • Publication
    Accès libre
    Evaluation of outputs from automated baseflow separation methods against simulated baseflow from a physically based, surface water-groundwater flow model
    (2012-5-18)
    Joseph Partington, Daniel 
    ;
    Brunner, Philip 
    ;
    Simmons, Craig Trevor
    ;
    Werner, A. D.
    ;
    Therrien, René
    ;
    Maier, Holger Robert
    ;
    Dandy, Graeme Clyde
    Baseflow is often considered to be the groundwater discharge component of streamflow. It is commonly estimated using conceptual models, recursive filters or a combination of the two. However, it is difficult to validate these methods due to the current challenges of measuring baseflow in the field. In this study, simulation of a synthetic catchment's response to rainfall is carried out using a fully integrated surface water-groundwater flow model. A series of rainfall events with differing recovery periods and varied antecedent moisture conditions is considered to span a range of different streamflow generation dynamics. Baseflow is estimated for the outlet hydrograph of the synthetic catchment using a selection of commonly used automated baseflow separation methods. These estimates are compared to the baseflow signal obtained from the numerical model, which serves as the control experiment. Results from these comparisons show that depending on the method used, automated baseflow separation underestimates the simulated baseflow by as much as 28%, or overestimates it by up to 74%, during rainfall events. No separation method is found to be clearly superior to the others, as the performance of the various methods varies with different soil types, antecedent moisture conditions and rainfall events. The differences between the various approaches clearly demonstrate that the baseflow separation methods investigated are not universally applicable. (c) 2012 Elsevier B.V. All rights reserved.
  • Publication
    Accès libre
    A hydraulic mixing-cell method to quantify the groundwater component of streamflow within spatially distributed fully integrated surface water–groundwater flow models
    (2011)
    Joseph Partington, Daniel 
    ;
    Brunner, Philip 
    ;
    Craig T. Simmons
    ;
    Therrien, René
    ;
    Werner, A.D.
    ;
    Dandy, G.C.
    ;
    Maier, H.R.
    The complexity of available hydrological models continues to increase, with fully integrated surface water–groundwater flow and transport models now available. Nevertheless, an accurate quantification of streamflow generation mechanisms within these models is not yet possible. For example, such models do not report the groundwater component of streamflow at a particular point along the stream. Instead, the groundwater component of streamflow is approximated either from tracer transport simulations or by the sum of exchange fluxes between the surface and the subsurface along the river. In this study, a hydraulic mixing-cell (HMC) method is developed and tested that allows to accurately determine the groundwater component of streamflow by using only the flow solution from fully integrated surface water–groundwater flow models. By using the HMC method, the groundwater component of streamflow can be extracted accurately at any point along a stream provided the subsurface/surface exchanges along the stream are calculated by the model. A key advantage of the HMC method is that only hydraulic information is used, thus the simulation of tracer transport is not required. Two numerical experiments are presented, the first to test the HMC method and the second to demonstrate that it quantifies the groundwater component of streamflow accurately.
  • Publication
    Accès libre
    Modeling Surface Water-Groundwater Interaction with MODFLOW: Some Considerations
    (2010)
    Brunner, Philip 
    ;
    Simmons, Craig T.
    ;
    Cook, Peter G.
    ;
    Therrien, René
    The accuracy with which MODFLOW simulates surface water-groundwater interaction is examined for connected and disconnected losing streams. We compare the effect of different vertical and horizontal discretization within MODFLOW and also compare MODFLOW simulations with those produced by HydroGeoSphere. HydroGeoSphere is able to simulate both saturated and unsaturated flow, as well as surface water, groundwater and the full coupling between them in a physical way, and so is used as a reference code to quantify the influence of some of the simplifying assumptions of MODFLOW. In particular, we show that (1) the inability to simulate negative pressures beneath disconnected streams in MODFLOW results in an underestimation of the infiltration flux; (2) a river in MODFLOW is either fully connected or fully disconnected, while in reality transitional stages between the two flow regimes exist; (3) limitations in the horizontal discretization of the river can cause a mismatch between river width and cell width, resulting in an error in the water table position under the river; and (4) because coarse vertical discretization of the aquifer is often used to avoid the drying out of cells, this may result in an error in simulating the height of the groundwater mound. Conditions under which these errors are significant are investigated.
  • Publication
    Accès libre
    Modeling Surface Water?Groundwater Interaction with MODFLOW: Some Considerations
    (2009-5-26)
    Brunner, Philip 
    ;
    Simmons, Craig Trevor
    ;
    Cook, Peter G.
    ;
    Therrien, René
  • Publication
    Accès libre
    Channel Representation in Physically Based Models Coupling Groundwater and Surface Water: Pitfalls and How to Avoid Them
    Käser, Daniel
    ;
    Graf, Tobias
    ;
    Cochand, Fabien
    ;
    McLaren, Rob
    ;
    Therrien, René
    ;
    Brunner, Philip 
    Recent models that couple three-dimensional subsurface flow with two-dimensional overland flow are valuable tools for quantifying complex groundwater/stream interactions and for evaluating their influence on watershed processes. For the modeler who is used to defining streams as a boundary condition, the representation of channels in integrated models raises a number of conceptual and technical issues. These models are far more sensitive to channel topography than conventional groundwater models. On all spatial scales, both the topography of a channel and its connection with the floodplain are important. For example, the geometry of river banks influences bank storage and overbank flooding; the slope of the river is a primary control on the behavior of a catchment; and at the finer scale bedform characteristics affect hyporheic exchange. Accurate data on streambed topography, however, are seldom available, and the spatial resolution of digital elevation models is typically too coarse in river environments, resulting in unrealistic or undulating streambeds. Modelers therefore perform some kind of manual yet often cumbersome correction to the available topography. In this context, the paper identifies some common pitfalls, and provides guidance to overcome these. Both aspects of topographic representation and mesh discretization are addressed. Additionally, two tutorials are provided to illustrate: (1) the interpolation of channel cross-sectional data and (2) the refinement of a mesh along a stream in areas of high topographic variability.