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) Conclusions CloudGMS 109 10 Conclusions 10.1. Overall outcomes A groundwater model has been developed of the source aquifer for the Western Davenport WCD incorporating all of the major hydrological processes identified in the conceptual model. Hydraulic conductivities ranging from 0.8 to 2 m/d and averaging 1.1 m/d in the model domain have been determined from calibration. Specific yield averaging 0.04 in the model domain have been determined through calibration. The calculated values for hydraulic conductivity and specific yield do not represent a unique modelled solution but are considered the best estimates from the available data. There is no evidence that the groundwater flow system is constrained by aquitards or structural feature with the groundwater moving freely across the different formations. The basin aquifers can be regarded as a relatively contiguous system that responds isotropically to recharge and pumping stressors Recharge occurs in two main forms: i. Regular mountain front recharge along the flanks of the basin, which maintains the observed throughflow, and occurs principally where surface run off is concentrated in the floodouts of the creeks such as Taylor Creek. ii. Irregular major recharge events occur by direct infiltration when extensive surface flooding occurs across the study area. The recurrence interval of such events is estimated at 15 20 years. Average annual recharge into the Northern Zone = 16GL/yr, Central Zone = 95GL/yr and SZone = 55GL/yr with high variability due to episodic nature of recharge events, determined over the simulation period 1970-2016. Demand will be met primarily from storage. Total groundwater storage in the area modelled is large and is estimated to be around 145000 GL at the end of the natural model scenario in 2015. The majority of groundwater is stored in the central zone and is estimated to be 141500 GL. Assuming a maximum economic depth of groundwater abstraction of 150 metres below ground level, the accessible volume in storage in the saturated zone is about 36000 GL. The storage is self-draining towards the discharge areas along the eastern margin of the aquifer system and the Wiso Basin to the north. 10.2. Aquifer occurrence and geometry There are some limitations related to the definition of the aquifer geometry particularly to the northwest and southeast. Further work using geophysical methods is warranted to understand the geometry and extent of the aquifer in these areas. Additional groundwater monitoring boreholes should be installed in the Southern and southeastern zones which currently have very sparse monitoring and field data