Regional flow in a complex coastal aquifer system: Combining voxel geological modelling with regularized calibration

Meyer, Rena; Engesgaard, Peter; Høyer, Anne‐Sophie; Jørgensen, Flemming; Vignoli, Giulio; Sonnenborg, Torben O.

doi:10.1016/j.jhydrol.2018.05.020

Cited by 25 publications

(57 citation statements)

References 46 publications

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“…Hence, Pleistocene sand 1 may to some extent represent a mixture of sand and clay. Additionally, uncertainties in the estimates of hydraulic conductivity from Meyer et al (2018a) will translate into errors in seepage flux and hence ages. Uncertainties and errors in hydraulic conductivity may therefore be partly compensated by estimates of effective 5 porosity that are somewhat different from the expected value.…”

Section: Calibration Resultsmentioning

confidence: 99%

“…The age simulation and calibration of effective porosities builds upon the calibrated regional-scale groundwater flow model (MODFLOW) of a highly heterogeneous coastal aquifer system by Meyer et al (2018a). First, advective transport simulation using MODPATH (Pollock 2012) was used for the calibration of effective porosities of seven different geological units.…”

Section: Methodsmentioning

confidence: 99%

“…The flow solution of the calibrated flow model (Meyer et al 2018a) constitute the base for the 3D advective transport model.…”

Section: Calibrating Porosity 25mentioning

confidence: 99%

“…As the calibration approach is similar to the one of Meyer et al (2018a) only additional characteristics are described in the following. Average corrected 14 C groundwater ages from 11 samples with 30 a 14 C activity higher than 5 pMC (Table 1) were used as calibration targets.…”

Section: Calibrating Porosity 25mentioning

confidence: 99%

“…Meyer et al (2018a) investigated the regional flow system and identified the most dominant mechanisms governing the flow system comprising geological features and land management that are visualized in a conceptual model in Figure 2.…”

mentioning

confidence: 99%

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Estimation of effective porosity in large-scale groundwater models by combining particle tracking, auto-calibration and <sup>14</sup>C dating

Meyer¹,

Engesgaard²,

Hinsby³

et al. 2018

Preprint

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Abstract. Effective porosity plays an important role in contaminant management. However, the effective porosity is often assumed constant in space and hence either neglected or simplified in transport model calibration. Based on a calibrated highly parametrized flow model, a three-dimensional advective transport model (MODPATH) of a 1300 km is improved significantly by the calibration of seven porosity units by a reduction of ME of 99% and RMS of 82% compared to a uniform porosity approach. Groundwater ages range from a few hundred years in the Pleistocene to several thousand years in Miocene aquifers. The advective age distributions derived from particle tracking at each sampling well show unimodal (for 10 younger ages) to multimodal (for older ages) shapes and thus reflect the heterogeneity that particles encounter along their travel path. The estimated effective porosity field, with values ranging between 4.3% in clay and 45% in sand formations, is used in a direct simulation of distributed mean groundwater ages. Although the absolute ages are affected by various uncertainties, a unique insight into the complex three-dimensional age distribution pattern and potential advance of young contaminated groundwater in the investigated regional aquifer system is provided, highlighting the importance of estimating effective porosity 15 in groundwater transport modelling and the implications for groundwater quantity and quality assessment and management.

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Section: Calibration Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…The flow solution of the calibrated flow model (Meyer et al 2018a) constitute the base for the 3D advective transport model.…”

Section: Calibrating Porosity 25mentioning

confidence: 99%

Section: Calibrating Porosity 25mentioning

confidence: 99%

mentioning

confidence: 99%

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Estimation of effective porosity in large-scale groundwater models by combining particle tracking, auto-calibration and <sup>14</sup>C dating

Meyer¹,

Engesgaard²,

Hinsby³

et al. 2018

Preprint

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Current and future state of groundwater salinization of the northern Elbe-Weser region

Gonzalez

Deus

Elbracht

et al. 2021

Grundwasser - Zeitschrift der Fachsektion Hydrogeologie

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Salinization of the upper aquifer of the northern Elbe-Weser region almost extends to the surface. Chloride content exceeds 250 mg/l and the groundwater is therefore, according to the German Drinking Water Ordinance, not suitable as drinking water. The chloride content in the aquifer originates from early flooding with seawater which occurred during the Holocene sea level rise. Depth and extent of the salinization were mapped by airborne electromagnetic surveys and validated by groundwater analyses. In the transition zone between the marshlands and geest areas, the fresh-saline groundwater interface falls to a depth of > −175 m NHN. Due to the extensive drainage of the marshlands, seepage of fresh groundwater is impeded. Instead, an upconing of the fresh-saline groundwater interface appears due to an upwardly directed hydraulic gradient. Due to climate change, chloride concentrations will increase along the coastlines. Further inland, a decrease of chloride content in near-surface groundwater will occur.

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Assessment of regional inter-basin groundwater flow using both simple and highly parameterized optimization schemes

et al. 2019

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The need for regional-scale integrated hydrological models for the purpose of water resource management is increasing. Distributed physically based coupled surface-subsurface models are usually complex and contain a large amount of spatiotemporal information that leads to a relatively long forward runtime. One of the main challenges with regard to regional-scale inverse modeling relates to parameterization and how to adequately exploit the information embedded in the existing observational data while avoiding parameter identifiability issues. This study examined and compared the calibration of a Bhighly parameterized^model with a Bclassical^unit-based parameterization scheme in which the dominant geological features were assumed to be known. The physically based coupled surface-subsurface model MIKE SHE was used for conducting the study of five river basins (4,900 km 2) in central Jutland in Denmark, characterized by heterogeneous geology and a considerable amount of groundwater flux across topographical catchment boundaries. The results indicated that introducing more flexibility in the parameter estimation process through a regularized approach significantly improved the model performance, in particular head and water balance errors. The highly parameterized calibration results additionally provided very useful insights into the model deficiencies in terms of conceptual model structure and incorrectly imposed boundary conditions. Furthermore, the results from data-worth analysis indicated that the highly parameterized model has more effectively utilized the information in the dataset compared to a traditional unit-based calibration approach.

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Regional flow in a complex coastal aquifer system: Combining voxel geological modelling with regularized calibration

Cited by 25 publications

References 46 publications

Estimation of effective porosity in large-scale groundwater models by combining particle tracking, auto-calibration and <sup>14</sup>C dating

Estimation of effective porosity in large-scale groundwater models by combining particle tracking, auto-calibration and <sup>14</sup>C dating

Current and future state of groundwater salinization of the northern Elbe-Weser region

Assessment of regional inter-basin groundwater flow using both simple and highly parameterized optimization schemes

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Regional flow in a complex coastal aquifer system: Combining voxel geological modelling with regularized calibration

Cited by 25 publications

References 46 publications

Estimation of effective porosity in large-scale groundwater models by combining particle tracking, auto-calibration and &lt;sup&gt;14&lt;/sup&gt;C dating

Estimation of effective porosity in large-scale groundwater models by combining particle tracking, auto-calibration and &lt;sup&gt;14&lt;/sup&gt;C dating

Current and future state of groundwater salinization of the northern Elbe-Weser region

Assessment of regional inter-basin groundwater flow using both simple and highly parameterized optimization schemes

Contact Info

Product

Resources

About

Estimation of effective porosity in large-scale groundwater models by combining particle tracking, auto-calibration and <sup>14</sup>C dating

Estimation of effective porosity in large-scale groundwater models by combining particle tracking, auto-calibration and <sup>14</sup>C dating