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 33 of 72 6 Groundwater flow model development 6.1 What is a groundwater flow model? A model is a simplified representation of a physical system. Groundwater models are used to represent the natural groundwater flow in the environment. Groundwater models may also be used to predict the effects of hydrological changes (like groundwater abstraction or irrigation developments) on the behaviour of the aquifer and are often named groundwater simulation models. Also nowadays the groundwater models are used in various water management plans for urban areas. Mathematical or numerical groundwater models are based on groundwater flow equations which are based on the real physics of groundwater flow. Preceding and underlying the mathematical model is a largely qualitative description of the structure of the system under study and the physical, chemical, and biological processes to be included in the model. This qualitative description is called a conceptual model. 6.2 Conceptual model A conceptual model provides a simplified overview of a complex natural system. The major geological units represented in the groundwater model are presented in Table 6. Table 6 Hydrogeological units relevant to the groundwater modelling study. Unit name Age Dominant Lithology Hydrologic type Comment Berry Springs dolomite Mesoproterozoic Dolostone Karstic aquifer Aquifer with major discharge Metasediments Hydrologic basement Underlies the Berry Springs dolostone. Mullaman Beds Early Cretaceous Claystone and basal sandstone Overlies large portions of the Berry Springs dolostone and reduces the amount of recharge The groundwater system consists of two hydrogeological layers representing the Cretaceous sands and clays and the karstic Proterozoic dolostone; The weathered highly permeable portion of the aquifer is assumed to extend to 50 metres below the mean sea level; Conceptually, the groundwater system developed in the weathered dolostone aquifer is a dual continua consisting of karsts / fractures within a porous media, although at a regional scale it appears to behave as porous media; Continuum flow (often termed diffuse flow) processes are active in low permeability matrix blocks or slightly fissured limestone beds, while concentrated flow processes can be observed in a discrete conduit network in the karst features; The water level and discharges dynamics observed are characteristic of a highly permeable media with relatively limited storage; The groundwater flow within the Berry Springs dolostone is from the south to the north where it discharges to the bed of the rivers and creeks and via discrete springs such as the Berry Springs complex, Parson Spring and Twin Farm Springs;


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