Hydro-System Flow Modelling for Water Resources Management in the Fractured and Karstified Chalk Aquifer Environment of Eastern Normandy

Pennequin, Didier; David, Pierre-Yann; Marie, Servière,; Amraoui, Nadia; Loiselet, Christelle

doi:10.1007/978-3-319-45465-8_22

Cited by 2 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In Upper Normandy, the Chalk constitutes a single karst aquifer 50-350 m thick and over 12,000 km 2 in extent. The aquifer is cut by faults that compartmentalize the aquifer into blocks with minor differences in behaviour (Slimani et al, 2009;Pennequin et al, 2017). The water table elevation varies across the region from 0 to 35 m altitude.…”

Section: Chalk Aquifer and Cave Developmentmentioning

confidence: 99%

“…Flow velocities measured from tracer tests can be >300-400 m h -1 (Maurice et al, 2006;Keim et al, 2012) and spring discharges in excess of 5 m 3 s −1 (Brenner et al, 2018). For these reasons, an increasing number of hydrogeological studies consider the Chalk as a triple porosity aquifer, with a combination of fracture and matrix porosity, and localized karst permeability (Mangin, 1975;Pennequin et al, 2017), or just as a karst aquifer in which karstification is less well developed than in other more massive and indurated limestones (Maurice et al, 2006;El Janyani et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stratigraphical influence on chalk cave development in Upper Normandy, France: implications for chalk hydrogeology

Ballesteros¹,

Farrant²,

Nehmé³

et al. 2020

IJS

View full text Add to dashboard Cite

Classically, the Upper Cretaceous Chalk Group aquifer of northwest Europe is conceptualized as a homogenous dual-porosity aquifer, with high porosity related to its fine-grained porous matrix, and intermediate hydraulic conductivity associated with fractures. However, an increasing number of hydrological studies visualize the Chalk as a heterogeneous karst aquifer due to the localised presence of dissolutionally enlarged conduits. Field investigation suggests that cave development is guided by distinct stratigraphical and tectonic discontinuities within the rock mass. Identifying which potential inception horizons within the Chalk aquifer are favoured, and why, is important for developing future robust conceptual models of groundwater behaviour. This study focusses on the Chalk of the Upper Normandy region in France where karstic conduits are common and are linked to major sources of groundwater for public water supply. We analyse the geometry and geomorphology of six chalk caves exposed in the Seine Valley with an aggregated length of over 5.7 km, along with other caves in southern England, and identify the key inception horizons associated with their development. The data shows that prominent Turonian, Coniacian and Santonian hardgrounds have influenced the development of 68% of the studied caves length, with sheet-flints and marl seams also playing a prominent role. Caves developed on or between hardgrounds typically display a complex interlinked anastomotic passage network, whereas passages subjected to paragenetic conditions caused by a high sediment flux tend to be concentrated into fewer, larger conduits. The new evidence from Normandy and Southern England demonstrates the role of lithostratigraphy, and in particular stratigraphical discontinuities on conduit development. The data reinforces the idea that the Chalk aquifer should be viewed as a heterogeneous triple porosity karstic aquifer, in which conduit development is influenced by key stratigraphical discontinuities. This improved conceptual model can be used to develop better groundwater flow models and improved catchment delineation.

show abstract

Section: Chalk Aquifer and Cave Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stratigraphical influence on chalk cave development in Upper Normandy, France: implications for chalk hydrogeology

Ballesteros¹,

Farrant²,

Nehmé³

et al. 2020

IJS

View full text Add to dashboard Cite

show abstract

The genesis and evolution of karstic conduit systems in the Chalk

Farrant

Maurice

Ballesteros

et al. 2022

View full text Add to dashboard Cite

The Upper Cretaceous Chalk Group is renowned as a major aquifer, but the development of secondary porosity due to karstic conduits is poorly understood. Hydrogeological data and evidence from boreholes, sections, and tracer tests indicate that dissolutional conduits occur throughout the Chalk aquifer. Here, we assess the evidence for Chalk karst, and combine it with theoretical models of dissolution and cave formation to produce a conceptual model for the development of karstic conduits. Dissolution due to the mixing of saturated waters of contrasting chemistry along key lithostratigraphical inception horizons form extensive but isolated conduit networks. These form a significant proportion of the secondary porosity and enhance permeability. They prime the aquifer for the development of more integrated conduit networks formed by focussed recharge of unsaturated surface derived water. However, the porous, well-fractured nature of the Chalk means that the time needed to form large integrated cave systems is often longer than timescales of landscape change. Continued landscape evolution and water table lowering halts conduit development before they can enlarge into cave systems except where geological and geomorphological settings are favourable. Groundwater models need to consider the formation of secondary karst permeability as this has a major influence on groundwater flow.

show abstract

Hydro-System Flow Modelling for Water Resources Management in the Fractured and Karstified Chalk Aquifer Environment of Eastern Normandy

Cited by 2 publications

References 0 publications

Stratigraphical influence on chalk cave development in Upper Normandy, France: implications for chalk hydrogeology

Stratigraphical influence on chalk cave development in Upper Normandy, France: implications for chalk hydrogeology

The genesis and evolution of karstic conduit systems in the Chalk

Contact Info

Product

Resources

About