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) Water Balance CloudGMS 93 7.2. Natural scenario (SC0) water balances 7.2.1. Total catchment water balance The natural scenario reflects a situation where no groundwater pumping is applied to the model, it is used as a base case for comparing the impacts of the various development scenarios. The inflows, outflows and storage changes from the entire model domain for the overland flow, unsaturated zone and saturated zone components for the natural scenario (SC0) were determined using the total catchment water balance option from the MIKE SHE water balance tool. The accumulated total catchment water balance for the simulation period 1970 2016 is presented below in Table 26. The values have been converted from the normalised storage depth values in millimetres to volumes using the area of active model cells (15581 x 106 m2). The water balance indicates that rainfall is the major inflow and evapotranspiration is the major outflow from the model domain. This is consistent with the conceptual model for an arid zone hydrologic system presented in section 4. It is apparent that the proportion of ET and OL flow is greater than the applied precipitation and that this deficit is associated with evapotranspiration accessing available water in the unsaturated and saturated zones, which is reflected in the sub-surface storage change value. Due to the nature of the outer boundary conditions, there is no inflow to the model domain across the model boundary for either the overland flow (OL) or saturated zone flow (SZ) components and are therefore equal to 0. The total cumulative model error is 3.1 mm, which is equal to 0.02% of the total inflow to the model domain. The error of 0.02% is much less than the 1% error identified as a target performance criterion identified previously in Table 23 and is considered an acceptable water balance error. Table 26 Western Davenport model domain water budget for the natural scenario (SC0) for the simulation period 01/01/1970 01/01/2016. Component Storage depth [mm] Vol. [GL] Ave Annual Vol. [GL/yr] Proportion [%] Precipitation -17212 -261200 -5960 96.7 Evapotranspiration 17353.5 270380 6009 97.5 OL storage change 0.4 6.2 0.1 0 OL out 352.3 5488 122 2.0 Sub-surface storage change -580.5 -9045 -201 3.3 SZ out (throughflow) 2.9 45.2 1 0 SZ drain outflow 86.5 1348 30 0.5 Pumping 0 0 0 0 Error 3.1 -48.5 1.1 0 OL = overland flow; SZ = saturated zone +ve values are losses to the system -ve values are gains to the system 7.2.2. Natural scenario total catchment saturated zone water balance The total catchment saturated zone water balance is presented below in Table 27. The total recharge to the groundwater system in the model domain for the period 01/01/1970 to 01/01/2016 is 7396 GL. This is equivalent to ~164 GL/yr, however, the episodic nature of the recharge events means that actual annual recharge values vary considerably.