2.6.2.2 Review of existing models


Summary

There have been many groundwater models developed in the Namoi subregion for a variety of different purposes. This review identified two models of a sufficient scale and complexity that warranted a detailed investigation as to their suitability for use in the bioregional assessment (BA) for the Namoi subregion. The owners of both of these models made them available for use in BA. The Namoi Catchment Water Study model did not suit the stability requirements that is necessary for BA analysis and the Gunnedah Basin Regional Model has limitations around the conceptualisation of the alluvium and Great Artesian Basin layers. Neither model was able to be re-purposed for use in BA in its current form and this warranted the development of a new model for BA.

There have been many models developed over the years in the Namoi subregion for a variety of purposes. These range from small-scale investigations on mine sites (e.g. Rocglen (Douglas Partners, 2010)) to the scale of the entire Great Artesian Basin (Welsh, 2006). Table 4 lists a selection of the existing models in the Namoi subregion relevant to the BA. It is clear that models developed for mining developments generally have a smaller extent (area) and a smaller grid cell size than the models developed for coal seam gas (CSG) operations or water resources assessment. To be useful in a BA context, a model would need to cover (or be extended to cover) the region that encompasses all developments and the potentially impacted area from these developments (see companion product M07 (as listed in Table 1) for groundwater modelling (Crosbie et al., 2016)). In the Namoi subregion there are two models that fulfil this criteria and warrant further investigation: the Namoi Catchment Water Study (NCWS) model (SWS, 2012) and the Gunnedah Basin Regional Model (GBRM) developed for the Narrabri Gas Project (CDM Smith, 2014). The extent of these models is shown in Figure 6.

Table 4 Summary of existing models in the Namoi subregion


Project name

Assessment purpose

Area

(km2)

Grid size

(m)

Reference

GABtran model

Water resources

1,539,480

5000

Welsh (2006)

Lower Namoi

Water resources

5,267

2500

Merrick (2001)

Upper Namoi

Water resources

2,365

1000

McNeilage (2006)

Boggabri

Mine

892

50–100

AGE (2010)

Werris Creek

Mine

93.5

25–100

RCA (2010)

Rocglen

Mine

<100

60–500

Douglas Partners (2010)

Maules Creek

Mine

1,190

50–500

AGE (2011)

NCWS

Cumulative impacts of mining and CSG

30,381

1000

SWS (2012)

Tarrawonga

Mine

1,518

50–500

Heritage Computing (2012)

Vickery

Mine

957

50–500

Heritage Computing (2013)

Watermark

Mine

6,825

50–500

AGE (2013)

Narrabri CSG

CSG

11,460

500–1000

Santos (2013)

Narrabri CSG (GBRM)

CSG

53,219

1000–5000

CDM Smith (2014)

Caroona

Mine

6,832

400

Hydro Simulations (2014)

Narrabri North

Mine

3,970

50–500

Hydro Simulations (2015)

CSG = coal seam gas; GABtran model = Great Artesian Basin transient model; NCWS = Namoi Catchment Water Study; GBRM = Gunnedah Basin Regional Model. All these models were developed in MODFLOW.

Figure 6

Figure 6 Location of regional-scale groundwater models in the Namoi subregion

GBRM =Gunnedah Basin Regional Model; NCWS = Namoi Catchment Water Study

Data: Bioregional Assessment Programme (Dataset 1)

Last updated:
6 December 2018
Thumbnail of the Namoi subregion

Product Finalisation date

2018
PRODUCT CONTENTS

ASSESSMENT