Territory Stories

Development of a Groundwater Model for the Western Davenport Plains

Details:

Title

Development of a Groundwater Model for the Western Davenport Plains

Creator

Knapton, Anthony; CloudGMS Pty Ltd

Commissioned by

Northern Territory. Department of Environment, Parks and Water Security

Collection

E-Publications; E-Books; PublicationNT; WRD Technical Report 27/2017

Date

2018-03

Location

Western Davenport Water Control District

Abstract

CloudGMS has been commissioned by DENR to develop a numerical groundwater model of the aquifers within the central area of the WDWCD to improve confidence in the sustainability of the groundwater resources, as this is the area within the WCD with greatest potential for intensive development.

Notes

Made available by via Publications (Legal Deposit) Act 2004 (NT); Prepared for Dept Environment and Natural resources

Table of contents

Executive summary -- 1 Background -- 2 Physical -- 3 Available data -- 4 Conceptual model -- 5 Model design & construction -- 6 Parameter estimation -- 7 Water balances -- 8 Sensitivity analysis -- 9 Predictive scenarios -- 10 Conclusions -- 11 Reference -- 12 Document history and version control -- Appendix A - Groundwater level hydrographs - Appendix B - Alek range horticultural farm sub-regional modelling

Language

English

Subject

Groundwater; Northern Territory; Western Davenport Water Control District; Conceptual mode

Publisher name

Northern Territory Governmnet

Place of publication

Palmerston

Edition

version 2.0

Series

WRD Technical Report 27/2017

Format

ix, 127 pages : colour illustration and maps ; 30 cm

File type

application/pdf

ISBN

9781743502976

Use

Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government

License

https://creativecommons.org/licenses/by/4.0/

Related links

https://hdl.handle.net/10070/842058 [LANT E-Publications: Development of a Groundwater Model for the Western Davenport Plains, version 1.1]

Parent handle

https://hdl.handle.net/10070/858845

Citation address

https://hdl.handle.net/10070/858846

Page content

Western Davenport WCD Groundwater Model (v2.0) Appendix CloudGMS 122 Aquifer parameters Transmissivity values used for estimating the throughflow ranged from 1000 to 5000 m2/d, assuming an aquifer thickness of 200 metres results in a hydraulic conductivity range of between 5 and 25 m/d. Transmissivity and inferred hydraulic conductivity values are presented in section 3.8, the range used to determine throughflow is on the upper end of the range determined from the pumping tests. Model selection, grid, layers and boundaries The numerical groundwater flow modelling package MIKESHE (DHI, 2016) was used for this work The extent, boundary conditions and features of the regional model are shown in Figure 2.2. A uniform grid size of 50 metres was used. The model covers an area of approximately 29km by up to 29km with the southeast and northwest boundaries oriented roughly perpendicular to the regional groundwater flow. The boundary conditions were set as no-flow The model comprises two layers. Layer 1 represents the Cenozoic sediments and the lower level was set at 42 mBGL, consistent with the bore lithological logs in the area. Layer 2 represents the Chabalowe Fm. The top of the model was set at a constant 377 mAHD. Parameter estimation process Parameters were estimated using PEST (Doherty, PEST Model-Indepedent Parameter Estimation User Manual Part I: PEST Software, 2016). Parameters considered in the parameter estimation process are presented below in Table 35. Although the specific yield of Layer 2 (Sy2) was considered in the setup of the PEST problem, it is not relevant as the aquifer does not become unconfined and is therefore tied to the specific yield of Layer 1 (Sy1). Similarly, the specific storage of Layer 1 is not relevant and has been tied to the specific storage of Layer 2. Table 35 Parameter bounds used during PEST optimisation. Parameter Range Unit Kxy1 6e-06 1e+00 m/s Adjustable Kz1 1e-10 1e+00 m/s Adjustable Sy1 1e-10 3e-01 - Adjustable Ss1 1e-10 0.3 - Tied to Ss2 Kxy2 1e-10 1e+00 m/s Adjustable Kz2 1e-10 1e+00 m/s Tied to Kxy2 Sy2 1e-10 0.3 - Tied to Sy1 Ss2 1e-10 0.3 - Adjustable