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) Conceptual Model CloudGMS 54 Gilbert & Jolly (1990) Used a gradient of 0.001, T = 1000 m2/d and W = 24.7 km give a throughflow of 9 GL/yr (24700 m3/d). Using a more conservative gradient of 0.0005, T = 800 m2/d (cf Arrinthrunga) and W = 24.7 km gives a throughflow of 3.61 GL/yr (~10000 m3/d). However, based on the summary of hydraulic parameters presented in section 3.8 and the groundwater level response to pumping in the vicinity of the Alekerange Horticultural Farm, the transmissivity of the Cambrian aquifers is probably an order of magnitude lower at between 100-200 m2/d. The NTGS stratigraphic holes (Section 3.3) indicate a 25 km wide, wedge-shaped cross-section to the aquifer in the central sector of the Western Davenport WCD with Chabalowe wedging out towards the east. The southern sector has a greater width of aquifer (~ 60 km) with a more complete and thicker sequence of Cambrian. Hence throughflow is funnelled through the section from Alekarenge to Wycliffe well as reflected by greater hydraulic gradients than to the south of Alekarenge. Using hydraulic conductivity values of between 0.8 and 2.2 m/d a wedge shaped cross-sectional area of 24.7 km by 300 metres and a groundwater gradient of 0.001 results in a throughflow of 1.1 3 GL/yr (~3000 8250 m3/d). 4.6.4. Groundwater storage The volume of groundwater stored in the study area is dependent on the volume of saturated aquifer material and the porosity of the aquifer. Assuming a drainable porosity of 0.04 and using the aquifer geometry in the groundwater model, the saturated volume of each of the aquifers is detailed above in Table 10. It should be noted that the volume reported for the Central Zone is an order of magnitude less than the value specified in the Water Allocation Plan document as the value has been incorrectly quoted from the supporting document (Hydro Tasmania Consulting, 2009).