2.1.3.1 Observed data


Most of the data required for groundwater modelling are obtained from bore data. Bore data for the Gloucester subregion were obtained from the Bureau of Meteorology, but originated from NSW state groundwater databases. The data acquired extends to November 2013. Not all model parameters are available at all bore locations. Table 5 lists the datasets that have been used to obtain hydrogeological data for the Gloucester subregion. Figure 14 shows the distribution of bores within the Gloucester subregion.

Table 5 Groundwater datasets used for hydrogeology and water quality analysis in the Gloucester subregion


Observed data

Dataset

Data item namea

Bore construction

NSW Office of Water – National Groundwater Information System 20140701 (NSW Office of Water, Dataset 1)

Bore

Construction Line

NGIS_v2_20140701

NSW allocation of aquifer for screened unit of monitoring bores (Bureau of Meteorology, Dataset 2)

Aquifers_assignment_JS_Jan13

Groundwater level

HYDMEAS – Hydstra Groundwater Measurement Update_NoW_Nov2013 (NSW Office of Water, Dataset 3)

HYDMEAS

Hydraulic parameters

State Transmissivity Estimates for Hydrogeology Cross-Cutting Project (Geoscience Australia, Dataset 4)

NSW_Pump_Test_Data_WRON_Nov2013_consolidated

tguess_NSW_full_set

Groundwater quality

HYDMEAS – Hydstra Groundwater Measurement Update_NoW_Nov2013 (NSW Office of Water, Dataset 5)

ALL WQ IN SELECTED REGION_gw_28112013

Allocation

Gloucester Groundwater Usage Estimates v20150501 (Bioregional Assessment Programme, Dataset 6)

GLO_GW_licenses_ExtractionVolumes_BoreDepths_20150501

aTypography is as used in the dataset.

Figure 14

Figure 14 Spatial distribution of bores with hydrogeological information for the Gloucester subregion

Source: Figure 25 in companion product 1.1 for the Gloucester subregion (McVicar et al., 2014)

2.1.3.1.1 Groundwater levels

Groundwater levels for the Gloucester subregion were obtained from the NSW Office of Water (Dataset 3). Water levels in this dataset are expressed as depths below the ground surface (mBGL) (i.e. a positive value indicates a watertable below the ground). Ground level elevations are missing for many bores.

Table 6 summarises the bores by groundwater-bearing unit. Almost 90% of groundwater level records in the dataset are from bores located in alluvium, with the remaining in fractured rock aquifers. Records of groundwater level for bores in deep water-bearing aquifers are not available in the NSW state groundwater dataset (NSW Office of Water, Dataset 3). There are nine bores with unknown bore depths, however they have been recorded as zero mBGL in the NSW Office of Water groundwater level database (Dataset 3).

Table 6 Summary of water level records for bores in the Gloucester subregion


Groundwater-bearing unit

Number of bores

Groundwater depth (mBGL)

Total number of monitoring records

Minimum

Maximum

Standard deviation

Alluvium

36

0.08

13.39

4.27

126

Fractured Rock

4

0

18.09

7.53

24

Deep water-bearing

0

NA

NA

NA

NA

‘NA’ means data not available.

Data: NSW Office of Water (Dataset 3)

In the NSW groundwater bore datasets (NSW Office of Water, Dataset 3), 205 monitoring records over a period of 23 years (1980 to 2002) were available from 49 bores for the Gloucester subregion. Most bores (around 24) have a single monitoring record (Table 7), although 20 bores have more than 7 monitoring records. Useful further work could include extracting data about groundwater levels available in various reports for the Gloucester subregion and assigning this data to the hydrogeology units. Due to limited availability of yearly groundwater levels in the dataset (NSW Office of Water, Dataset 3) no spatial and temporal data trend analysis is performed. Mining companies and coal seam gas resource developers often collect water level data and more information may be available at locations across the Gloucester subregion than has been reported in Dataset 3 (NSW Office of Water groundwater).

Table 7 Summary of monitoring records for bores in the Gloucester subregion


Number of monitoring records

Number of bores

1

24

2

1

4

3

5

1

7

9

8

8

9

1

12

1

14

1

Data: NSW Office of Water (Dataset 3)

2.1.3.1.2 Hydraulic parameters

Hydraulic parameters provide critical input into the numerical groundwater model – the identification of uncertainties in the hydraulic parameter fields is essential as they can contribute significantly to the overall uncertainty associated with the modelling of impacts.

The NSW groundwater data (NSW Office of Water, Dataset 1, Dataset 3; Bioregional Assessment Programme, Dataset 7) contains limited pumping test data, which usually include the date and duration of the test, initial water level, pumping rate and maximum drawdown. Available hydrogeological data sources (e.g. university theses, consultancy reports and government reports) were examined and hydrogeological records (e.g. stratigraphy, water level, pumping test results) were incorporated into the datasets (Bureau of Meteorology, Dataset 2; Geoscience Australia, Dataset 4) where appropriate.

Transmissivity values were estimated from pumping test data using the TGUESS approach (a computerised technique for estimating the hydraulic conductivity of aquifers from specific capacity data; Bradbury and Rothschild, 1985). Hydraulic conductivity was computed from the derived transmissivity data where screen interval data were available (Geoscience Australia, Dataset 4). However, where hydraulic conductivity or transmissivity was available in the original state database, this value was kept as the primary value for the statistical analysis. When multiple hydraulic conductivity or transmissivity records were present, the mean was used for the statistical analysis. No pumping test records or storage values (Ss and ST) are available for the bores located in the Gloucester subregion in the NSW bore database (NSW Office of Water, Dataset 3). No transmissivity or storage values for the bores located in the Gloucester subregion are available in the Bureau of Meteorology (Dataset 2) and Geoscience Australia (Dataset 4) datasets.

Hydraulic conductivity values for the aquifers reported in various reports (Heritage Computing, 2009, 2012; Parsons Brinckerhoff, 2013; SRK, 2010) are reproduced in Table 8.

Table 8 Range of hydraulic conductivity data for bores in the Gloucester subregion as reported in various reports


Groundwater-bearing unit

Hydraulic conductivity range

(m/day)

Alluvium

0.3–500

Fractured Rock

0.01–20

Deep water-bearing

0.002–0.03

Source: Heritage Computing (2009, 2012); Parsons Brinckerhoff (2013); SRK (2010)

2.1.3.1.3 Groundwater quality

The observed water chemistry and quality data for the Gloucester subregion are sourced primarily from the NSW state groundwater dataset (NSW Office of Water, Dataset 5). It contains 1015 water chemistry sampling records from 32 groundwater bores across the Gloucester subregion. As the aquifers in which the bores in this dataset are screened are not available for any bores, the attribution to aquifer (Table 9) is based on the depth of the bore and the thickness of aquifer recorded in the various hydrogeological reports for the Gloucester geological basin. Mining companies and coal seam gas resource developers often collect water quality data and more information may be available at locations across the Gloucester subregion than has been reported in Dataset 5 (NSW Office of Water).

Table 9 Number of water chemistry records for the Gloucester subregion


Groundwater-bearing unit

Number of bores

No of water chemistry records

Alluvium

21

621

Fractured Rock

11

394

Data: Bioregional Assessment Programme (Dataset 6)

A summary of groundwater chemistry results for the bores in the NSW groundwater dataset (NSW Office of Water, Dataset 5) is provided in Table 10. Further information about the analysis of water chemistry in the Gloucester subregion is available in Section 1.5.2.2 of companion product 1.5 for the Gloucester subregion (Rachakonda et al., 2015).

Table 10 Summary of water chemistry results for the Gloucester subregion


Analyte

Unit

Minimum

Maximum

Median

Acidity as CaCO3

mg/L

0

300

25

Alkalinity (Total) as CaCO3

mg/L

17

330

210

Alkalinity as Bicarbonate (HCO3)

mg/L

20.75

687.05

125.08

Calcium as Ca – soluble

mg/L

17

160

59.50

Calcium as Ca – total

mg/L

15.23

226.85

21.04

Chloride as Cl

mg/L

27

5270

1572.50

Electrical Conductivity at 25 °C

µS/cm

106

630,000

3470

Fluoride as F – soluble

mg/L

0.02

2.66

0.17

Iron as Fe – soluble

mg/L

0.01

53

0.14

Iron as Fe – total

mg/L

0.01

82

8.27

Lead as Pb – soluble

mg/L

0.01

0.01

0.01

Magnesium as Mg – soluble

mg/L

5.2

60

45.50

Magnesium as Mg – total

mg/L

13.37

149.35

16.77

pH

---

3.1

8.6

6.90

Potassium as K – soluble

mg/L

1.56

16.81

3.80

Solids – total dissolved (calculated)

mg/L

300

4700

2500

Solids – total suspended at 105 °C

mg/L

1

872

4

Sulfate as S

mg/L

1

498

91

Sulfate as SO4

mg/L

19.21

182.03

46.11

Data: NSW Office of Water (Dataset 5)

2.1.3.1.4 Allocation

The allocation data are summarised in Table 11. Most of the licensed allocation is from alluvial aquifers, with a lesser volume from fractured rock aquifers. There is no licensed allocation to extract water from the deep water-bearing units.

An industrial report prepared by Parsons Brinckerhoff (2013) reported that annual stock and domestic bore use is approximately 1 ML/bore. Australasian Groundwater and Environmental (2013) has reported that a single groundwater facility exists (irrigation bore) in the Avon River management area with an annual entitlement of 20 ML/year from the alluvium. Further information about the analysis of entitlements and/or allocations in the Gloucester subregion is available in Section 1.5.1.2.1 of companion product 1.5 for the Gloucester subregion (Rachakonda et al., 2015).

Table 11 Summary of allocation data for the bores in the Gloucester subregion


Groundwater-bearing unit

Total number of bores

Licensed water allocation (ML/y)

Number of bores with no allocation record

Alluvium

107

1530

100

Fractured rock

53

334

42

Deep water-bearing

15

0

15

Total

175

1864

157

Data: Bioregional Assessment Programme (Dataset 6)

Last updated:
22 January 2019
Thumbnail of the Gloucester subregion

Product Finalisation date

2018