Karst Geology and Regional Hydrogeology in Denmark

Nilsson, Bertel; Gravesen, Peter

doi:10.1007/978-3-319-51070-5_34

Cited by 5 publications

(2 citation statements)

References 34 publications

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“…2). Morphological features of the glacial deposits related to karstification of the upper parts of fractured chalk and limestone aquifers have been interpreted and reported in the Danish geological literature (Nilsson and Gravesen 2018). Based on this, a generic geographical information system (GIS) database with information on karst feature types, underlying carbonate lithology, thicknesses of glacial cover layers, and geographical position, was compiled and evaluated.…”

Section: Research Areamentioning

confidence: 99%

“…A survey of surface karst features by Nilsson and Gravesen (2018) has been supplemented with recent years of reports of surface karst features from citizens directly to the Geological Survey of Denmark and Greenland or via the media (in total 42 locations). The karst features can be separated into sinkholes that are funnel-shaped (including fluviokarst) or vertical-sided dolines, karst-lakes or sinkhole ponds with subsurface outlets, small caves, karst springs and losing stream sections to chalk and limestone aquifers (here named 'disappearing streams').…”

Section: Geomorphological Featuresmentioning

confidence: 99%

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Evidence of karstification in chalk and limestone aquifers connected with stream systems and possible relation with the fish ecological quality ratio in Denmark

Nilsson

Chen

et al. 2022

Hydrogeol J

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Although chalk aquifers are not too often associated with conduit flow, they are highly productive groundwater systems and, like limestone aquifers, they can be vulnerable to contamination when exposed to land use activities. The Danish carbonate rocks are generally recognized to be highly fractured and covered by thick Quaternary sediments. Fissure flow is pronounced, occurring in the upper 50–100 m due to Pleistocene glaciations. According to recently published maps of the distribution of karst in Europe, Denmark has no karst. However, this study concludes that karstified chalk and limestone aquifers are an important source of freshwater in Denmark. Four national datasets on karst features, groundwater flow, groundwater chemistry, and fish ecological quality ratio (EQR) data now indicate more heterogeneous structures and preferential flow pathways in the chalk and limestone aquifers than had been conceptualized and modelled with a national water resources groundwater/surface-water model in the recent past. This study provides new qualitative evidence that rapid and preferential flow of water and agrochemicals from the surface through thinner parts of the Quaternary cover layers, sinkholes and solution-enlarged fractures may likely impact the vulnerability of chalk and limestone aquifers. Additionally, due to the preferential flow system, some gaining streams discharged by karstified chalk and limestone aquifers show increased fish EQR values when using observed river daily discharge data instead of simulated daily discharge.

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Section: Research Areamentioning

confidence: 99%

Section: Geomorphological Featuresmentioning

confidence: 99%

Evidence of karstification in chalk and limestone aquifers connected with stream systems and possible relation with the fish ecological quality ratio in Denmark

Nilsson

Chen

et al. 2022

Hydrogeol J

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Evaluation of underground karst development state for tunnel construction by using the extension assessment method

Zhang,

Zheng,

Zhou

et al. 2023

Bull Eng Geol Environ

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Groundwater level monitoring of Danish chalk and limestone aquifers to survey trends in quantitative status and groundwater resources

Henriksen

Nilsson

Ditlefsen

et al. 2023

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Chalk and limestone aquifers contribute 1/3 of the drinking water supply in Denmark, and 1/6 of that national groundwater resource is assessed as Poor quantitative WFD status due to intensive abstraction. The paper describes the national groundwater level monitoring network with regard to three applications: (i) when used as part of annual surveying and reporting of groundwater resource and impacts from climate and groundwater abstraction; (ii) as part of real time monitoring and modelling for daily and seasonal forecasting; and (iii) for tracking long-term climate change impacts on groundwater level. Groundwater level monitoring provides a particularly important indicator of abstraction pressure and the sustainable balance compared with recharge. Many larger chalk and limestone groundwater bodies (GWBs) in Denmark are only monitored by local water companies and not represented in the national groundwater level network. This raises the concern that the current national groundwater level monitoring does not fully support integrated modelling and assessment purposes for chalk and limestone groundwater bodies. This also implies that, for tracking of long-term climate change and anthropogenic impacts on groundwater level, the national groundwater monitoring network especially lacks long term records with complete 30-year time series for many intensively exploited large chalk and limestone aquifers. Supplementary material at https://doi.org/10.6084/m9.figshare.c.6420292

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Karst Geology and Regional Hydrogeology in Denmark

Cited by 5 publications

References 34 publications

Evidence of karstification in chalk and limestone aquifers connected with stream systems and possible relation with the fish ecological quality ratio in Denmark

Evidence of karstification in chalk and limestone aquifers connected with stream systems and possible relation with the fish ecological quality ratio in Denmark

Evaluation of underground karst development state for tunnel construction by using the extension assessment method

Groundwater level monitoring of Danish chalk and limestone aquifers to survey trends in quantitative status and groundwater resources

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