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) Predictive Scenarios CloudGMS 106 the available groundwater in storage in the aquifer; the capacity of the borefield(s) to extract the groundwater in storage from the aquifer system; and impacts to groundwater dependent vegetation. The ultimate long-term sustainability of the borefield(s) is dependent on the recharge to the aquifer system, however, there is considerable storage in the aquifer system that during periods of little or no recharge can be used as a buffer to the natural climate variations. If it is assumed that the return interval of recharge events comparable to the 1974-1979 and 2005-2010 is between 15 and 20 years, then the storage depletion over this time interval will determine if a pumping regime is sustainable in the long-term. 9.5.2. Water allocation planning policy framework Currently the water allocation planning policy in the arid zone the Northern Territory Government has followed the principle that: total extraction over a period of at least 100 years will not exceed 80 per cent of the total aquifer storage at start of extraction; and there will be no deleterious change in groundwater discharges to dependent ecosystems. In the event that current and/ or projected consumptive use exceeds the threshold levels of 80% of the consumptive pool for aquifers, or groundwater discharges to groundwater dependent ecosystems are impacted, new groundwater licences will not be granted unless supported by directly related scientific research into groundwater dependent ecosystem/cultural requirements. 9.5.3. Groundwater sustainability metrics With the water allocation policy in mind, the sustainability of the Western Davenport Central Zone will be examined with respect to the two following metrics: the available groundwater in storage in the aquifer; and impacts on modelled ET fluxes at groundwater dependent vegetation (GDV) sites. MIKE SHE reports saturated zone storage as a storage depth in millimetres, which is then multiplied by the budget area to provide a storage volume. 9.6. Impacts to existing users 9.6.1. Surface water diversions Diversions of drainage in the WDWCD such as Murray Creek, Skinner Creek, Taylor Creek or Wycliffe Creek may have an impact on the volume of water that can recharge the aquifer by reducing the number of smaller events recharging the up-gradient areas of the aquifers and possibly impacting on the extent of the inundation along drainage and floodplains during large rainfall events which may also result in reduced recharge. 9.6.2. Groundwater access The magnitude and extent of drawdown forecast by the model for the future groundwater abstraction scenario (SC4) indicates that there is likely to be impact on adjacent existing users by either reducing available drawdown, thus reducing bore yields, or reducing groundwater levels below the current