Territory Stories

Development of a Groundwater Flow Model - Berry Springs

Details:

Title

Development of a Groundwater Flow Model - Berry Springs

Creator

Knapton, Anthony

Collection

E-Publications; E-Books; PublicationNT; 17/2016

Date

2016

Location

Berry Springs

Description

Made available via the Publications (Legal Deposit) Act 2004 (NT).

Table of contents

Table of Contents -- List of Figures -- List of Tables -- Acknowledgements -- Glossary of Terms -- Executive Summary -- 1 Introduction -- 1.1 Background -- 1.1 Aim of the study -- 2 Site Description -- 2.1 Study area location -- 2.2 Climate -- 2.2.1 Rainfall data -- 2.2.2 Evaporation data -- 2.3 Hydrology -- 2.4 Land use -- 2.5 Groundwater extraction -- 2.6 Water quality -- 3 Hydrogeology -- 3.1 Geological formations -- 3.1.1 Mount Bonnie Formation (Pso) -- 3.1.2 Unnamed Dolostone Unit (Psd): Berry Springs Dolostone -- 3.1.3 Burrell Creek Formation (Pfb) -- 3.1.4 Depot Creek Formation (Ptd) -- 3.1.5 Petrel Formation (JKp) -- 3.1.6 Darwin Member (Kld) -- 3.2 Geological structure -- 3.3 Aquifer characteristics -- 3.3.1 Hydraulic conductivity -- 3.3.2 Storage coefficient -- 4 Groundwater hydrology -- 4.1 Groundwater flow -- 4.2 Recharge -- 4.2.1 Water balance method -- 4.2.2 Water table fluctuation method -- 4.2.3 Spring discharge -- 4.2.4 Evapotranspiration -- 4.3 Rainfall-runoff modelling -- 4.4 Predicted natural conditions compared to recent observed flows -- 4.5 Groundwater chemistry -- 5 Available data -- 5.1 Climate data -- 5.2 SRTM digital terrain model -- 5.3 Geological data -- 5.4 Groundwater level data -- 5.4.1 Steady state groundwater levels -- Berry Springs Groundwater Flow Model -- 5.4.2 Time series groundwater levels -- 5.5 River discharge data -- 5.5.1 Manual gauging data -- 5.5.2 Continuous recorder data -- 5.6 Pumping data -- 5.7 Data gaps -- 6 Groundwater flow model development -- 6.1 What is a groundwater flow model? -- 6.2 Conceptual model -- 6.3 Modelling approach -- 6.4 Model package -- 6.5 Model mesh geometry -- 6.5.1 Mesh design -- 6.5.2 Mesh generation -- 6.6 Material properties -- 6.7 Fracture flow -- 6.8 Boundary conditions -- 6.8.1 Recharge and Areal ET Flux -- 6.8.2 Constant head BC values -- 6.9 Pumping data -- 6.10 FEFLOW settings -- 6.10.1 Problem class -- 6.10.2 Temporal and control data -- 7 Calibration -- 7.1 Steady state finite element model -- 7.1.1 Steady state model results -- 7.2 Transient finite element model -- 8 Scenarios -- 8.1 Water balance assessment -- 8.2 Scenario A – Historic climate without pumping -- 8.2.1 Water balance under historic climate -- 8.3 Scenario B – Historic climate with current pumping estimates -- 8.3.1 Pumping estimate methodology -- 8.3.2 Water balance under historic climate and current pumping -- 8.3.3 Impacts of pumping on groundwater discharge at Berry Springs -- 8.3.4 Flow duration -- 9 Results and discussion -- 9.1 Measurable impacts -- 9.1.1 Reduced dry season flows -- 9.1.2 Recession slope of dry season flows -- 9.1.3 Groundwater levels -- 9.2 Rainfall, recharge & minimum flows analysis -- 9.3 Impacts of pumping based on zones -- 10 Conclusions -- 10.1 Key performance indicators -- 11 References -- Appendix A - Groundwater level hydrographs -- Appendix B - Calibrated transient model results

Language

English

Subject

Berry Springs Dolostone; Berry Springs aquifer System; Groundwater Flow Model

Publisher name

Department of Land Resource Management

Place of publication

Darwin

Series

17/2016

Format

72 pages : colour illustration and maps ; 30 cm.

File type

application/pdf.

ISBN

9781743501092

Copyright owner

Check within Publication or with content Publisher.

Parent handle

https://hdl.handle.net/10070/272355

Citation address

https://hdl.handle.net/10070/428025

Page content

Berry Springs Groundwater Flow Model Page 18 of 72 3 Hydrogeology The major hydrogeological feature of the Berry Springs area is the fault bounded sedimentary basin which has an area of approximately 90 km 2 . The major aquifer in the basin is an unnamed dolostone unit (Psd), known as the Berry Springs Dolostone which has been weathered to form karstic features. Previous studies relating to the hydrogeology of the Berry Springs region have been largely confined to mapping the geology (Crick, 1983; Pietsch, 1986; Pietsch and Stuart-Smith, 1987). Hydrogeological mapping was undertaken in 1994 to examine the hydrogeology and groundwater dynamics of the area (Verma, 1995). This work identified the extent of the dolomite basin, groundwater discharge areas and the likely groundwater movement (Verma, 2002). 3.1 Geological formations 3.1.1 Mount Bonnie Formation (Pso) The Mount Bonnie Formation of the South Alligator Group consists of interbedded pelite, felspathic greywacke, sandstone, pyritic siltstone & shale, phyllite and rare banded iron formation (BIF). 3.1.2 Unnamed Dolostone Unit (Psd): Berry Springs Dolostone The unnamed dolostone (Psd) is the upper layer of the South Alligator Group and overlies the Mount Bonnie Formation (Pso). Weathered dolomite is exposed in the northern region - along the springs inside the Wildlife Park and the Berry Springs Nature Park; and in the Berry Creek at the Hopewell Road crossing. It consists of silicified dolomite, dolomitic siltstone, saccharoidal quartzite (after carbonate), calcite crystals, siltstone, shale, phyllite, commonly carbonaceous, pyritic, cherty & siliceous. Yields from this formation are generally > 5.0 L/s, which may be higher if fracturing and/or weathering is present (Verma, 1995). 3.1.3 Burrell Creek Formation (Pfb) The Burrell Creek Formation (Pfb) of the Finniss River Group conformably lies over the South Alligator Group and consists of mica schist, siltstone, shale, phyllite, greywacke, slate which are very similar to that of the Mount Bonnie Formation. Bore yields from this formation are generally < 0.5 L/s which may be higher if fracturing and/or weathering or fractured quartz veins are present. Higher yields (up to 5.0 L/s, airlifted) have been obtained in the highly fractured graben between the eastern boundary of the dolostone (Psd) and the Mt Bonnie Formation (Pso). 3.1.4 Depot Creek Formation (Ptd) The Depot Creek Formation (Ptd) of the Tolmer Group is of Proterozoic age and lies unconformably over the Lower Proterozoic sediments (mostly dolostone in this area) and they are nearly flat lying. This formation occurs in the Darwin River subcatchment. It consists of pink quartzite, quartz sandstone with ripple marks. 3.1.5 Petrel Formation (JKp) The Petrel Formation (JKp) is of Jurassic age and consists of friable quartz sandstone, quartz-pebble, conglomerate, conglomeratic sandstone, ferruginous sandstone, and minor breccias. This formation is flat lying and overlies the Depot Creek Formation (Ptd). The base of this formation is exposed along the Darwin River near Old Bynoe Road. This formation is also very porous and good for recharging the underlying layers.


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