A global-scale two-layer transient groundwater model: development  and application to groundwater depletion

Graaf, Inge de; Beek, Rens van; Gleeson, Tom; Moosdorf, Nils; Schmitz, Oliver; Sutanudjaja, Edwin H.; Bierkens, M. F.

doi:10.5194/hess-2016-121

Cited by 36 publications

(73 citation statements)

References 14 publications

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“…Studies in the past have suggested groundwater may not exert strong controls to the near‐surface soil dynamics when it is far from the surface (Maxwell & Kollet, 2008; Ferguson & Maxwell, 2010; Lo & Famiglietti, 2010). However, the use of JULES‐GFB even for deep aquifer systems may be justified if the purpose is to use JULES applied to water resources studies where a representative volume of subsurface water is a key component of the study (de Graaf et al, 2017; Fan et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

Towards the representation of groundwater in the Joint UK Land Environment Simulator

Batelis

Rahman

Kollet

et al. 2020

Hydrological Processes

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Groundwater is an important component of the hydrological cycle with significant interactions with soil hydrological processes. Recent studies have demonstrated that incorporating groundwater hydrology in land surface models (LSMs) considerably improves the prediction of the partitioning of water components (e.g., runoff and evapotranspiration) at the land surface. However, the Joint UK Land Environment Simulator (JULES), an LSM developed in the United Kingdom, does not yet have an explicit representation of groundwater. We propose an implementation of a simplified groundwater flow boundary parameterization (JULES‐GFB), which replaces the original free drainage assumption in the default model (JULES‐FD). We tested the two approaches under a controlled environment for various soil types using two synthetic experiments: (1) single‐column and (2) tilted‐V catchment, using a three‐dimensional (3‐D) hydrological model (ParFlow) as a benchmark for JULES’ performance. In addition, we applied our new JULES‐GFB model to a regional domain in the UK, where groundwater is the key element for runoff generation. In the single‐column infiltration experiment, JULES‐GFB showed improved soil moisture dynamics in comparison with JULES‐FD, for almost all soil types (except coarse soils) under a variety of initial water table depths. In the tilted‐V catchment experiment, JULES‐GFB successfully represented the dynamics and the magnitude of saturated and unsaturated storage against the benchmark. The lateral water flow produced by JULES‐GFB was about 50% of what was produced by the benchmark, while JULES‐FD completely ignores this process. In the regional domain application, the Kling‐Gupta efficiency (KGE) for the total runoff simulation showed an average improvement from 0.25 for JULES‐FD to 0.75 for JULES‐GFB. The mean bias of actual evapotranspiration relative to the Global Land Evaporation Amsterdam Model (GLEAM) product was improved from −0.22 to −0.01 mm day−1. Our new JULES‐GFB implementation provides an opportunity to better understand the interactions between the subsurface and land surface processes that are dominated by groundwater hydrology.

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Section: Discussionmentioning

confidence: 99%

Towards the representation of groundwater in the Joint UK Land Environment Simulator

Batelis

Rahman

Kollet

et al. 2020

Hydrological Processes

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“…The aquifer hydrogeologic parameters in this model were determined from global‐scale lithology (Hartmann & Moosdorf, ), and transmissivities were derived using shallow bedrock permeability data from Gleeson et al (). Based on this single layer steady state model, De Graaf et al () further extended this model to a two‐layer transient model for both confined and unconfined aquifer systems. The transient model was developed by coupling the hydrological model PCR‐GLOBWB (Van Beek et al, ) and the groundwater model using MODFLOW (McDonald & Harbaugh, ).…”

Section: Discussionmentioning

confidence: 99%

“…Fan et al () also developed an empirical‐based map of soil permeability that targets the shallow vadose zone (~1‐ to 2‐m depth) based on the U.S. soils map (http://ldas.gsfc.nasa.gov/) but does not include the permeability of bedrock. ( De Graaf et al, ) used both sedimentary and the shallow bedrock permeability data sets to represent the subsurface, including confining units, by developing geometric relationships between surficial expressions of units and their potential depth relationships. Recreating the hydrogeologic structure of the subsurface over large scales remains a major source of uncertainty in applying groundwater flow models accurately at continental scales.…”

Section: Discussionmentioning

confidence: 99%

“…A practical challenge of groundwater flow modeling is compiling accurate input parameters, including recharge rates and hydraulic conductivities. Due to limitations in obtaining detailed information for these parameters over large spatial scales (Anderson et al, ; De Graaf et al, ) and quantifying their uncertainty (Gleeson et al, ), groundwater flow models have traditionally been used for smaller‐scale studies with well‐constrained hydrogeologic information. Groundwater flow models also require that hydraulic head values and fluxes converge to internally and externally (i.e., matching boundary conditions) consistent values.…”

Section: Introductionmentioning

confidence: 99%

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Opportunities and Challenges in Computing Fresh Groundwater Discharge to Continental Coastlines: A Multimodel Comparison for the United States Gulf and Atlantic Coasts

Zhou

Befus

Sawyer

et al. 2018

Water Resources Research

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The fresh component of submarine groundwater discharge (fresh SGD) transports nutrient and contaminant loads from land to sea. Fresh SGD fluxes are poorly known but depend on geology, topography, climate, and land use. Here we assess two general approaches for quantifying the magnitude of fresh SGD over regional to continental scales—water budgets (lumped parameter models) and groundwater flow models—focusing on the U.S. Atlantic and Gulf Coasts as a large‐scale case study. Estimates of fresh SGD fluxes from groundwater flow models are more variable than estimates from water budgets, and both are often less than field‐based estimates. Both approaches predict the volume of fresh SGD within approximately 50% of 12.3 km3/year, in line with previous estimates, and differences are largely driven by hydrographic data inputs. The simplified water budget approach, while computationally cheap, cannot resolve flow paths or continuous flux distributions and may neglect groundwater flow from deep aquifers or distal recharge zones. Conversely, three‐dimensional groundwater flow models can resolve flow paths and fresh SGD contributions from heterogeneous aquifer systems but are computationally expensive and require more parameterization. Ultimately, multiple models and integrated field data are needed to improve our estimates of fresh SGD fluxes over a wide range of scales.

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“…The challenge is to estimate spatial variations in the storage and transmission properties of the landscape. Advances are possible through the development of new data sources on geophysical attributes (Simard et al, 2011;Gleason and Smith, 2014;Fan et al, 2015;Chaney et al, 2016b;Pelletier et al, 2016;De Graaf et al, 2017), new approaches to link geophysical attributes to model parameters (Samaniego et al, 2010;Kumar et al, 2013;Rakovec et al, 2015), and new diagnostics to infer model parameters Yilmaz et al, 2008;Pokhrel et al, 2012). Such focus will give the parameter estimation problem the scientific attention that it deserves, rather than the far-too-common approach where parameter estimation is relegated to a "tuning exercise" in model applications.…”

Section: Summary and Next Stepsmentioning

confidence: 99%

The evolution of process-based hydrologic models: historical challenges and the collective quest for physical realism

Clark

Bierkens

Samaniego

et al. 2017

Hydrol. Earth Syst. Sci.

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227

160

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Abstract. The diversity in hydrologic models has historically led to great controversy on the "correct" approach to processbased hydrologic modeling, with debates centered on the adequacy of process parameterizations, data limitations and uncertainty, and computational constraints on model analysis. In this paper, we revisit key modeling challenges on requirements to (1) define suitable model equations, (2) define adequate model parameters, and (3) cope with limitations in computing power. We outline the historical modeling challenges, provide examples of modeling advances that address these challenges, and define outstanding research needs. We illustrate how modeling advances have been made by groups using models of different type and complexity, and we argue for the need to more effectively use our diversity of modeling approaches in order to advance our collective quest for physically realistic hydrologic models.

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A global-scale two-layer transient groundwater model: development and application to groundwater depletion

Cited by 36 publications

References 14 publications

Towards the representation of groundwater in the Joint UK Land Environment Simulator

Towards the representation of groundwater in the Joint UK Land Environment Simulator

Opportunities and Challenges in Computing Fresh Groundwater Discharge to Continental Coastlines: A Multimodel Comparison for the United States Gulf and Atlantic Coasts

The evolution of process-based hydrologic models: historical challenges and the collective quest for physical realism

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