Aquaculture Groundwater Resource Atlas - Pilbara Coast

Overview

The most important groundwater resources along the Pilbara coast are in the alluvial aquifers along the major rivers from the Ashburton to the De Grey. These aquifers consist of sands and gravels, which are mainly recharged by fresh water from river flow. The Ashburton aquifer differs, as the present river course is north east of the aquifer, and it contains brackish groundwater, recharged only by large floods. Groundwater is also available from aquifers in the Canning Basin to the east and from the Carnarvon Basin to the west. There are no major groundwater resources known in the rocks of the Pilbara Craton along the coast. Minor groundwater resources occur along the smaller rivers such as the Maitland and Harding. Elsewhere on the coastal plain, pastoral supplies of brackish to saline groundwater are drawn from low yielding bores and wells.

Investigations have been carried out where only there is fresh groundwater. It is likely that all the alluvial aquifers contain saline groundwater at the coastline, and may therefore be possible high yielding sources of saline water for aquaculture.

Low salinity groundwater from aquifers along the the Cane, Yule and De Grey Rivers is currently used for town water supply.

References: Davidson, 1975. Forrest and Coleman, 1996.

Main alluvial aquifers (yellow) along the Pilbara coast

Click here for a enlarged view

Ashburton River alluvium

A palaeochannel associated with a previous course of the Ashburton River runs north westwards from the point of entry of the river onto the coastal plain near Nanyingee Hill. It has been investigated as far as 18km from the river, but can be inferred to extend farther, possibly to the coast. The palaeochannel consists of sand and gravel as much as 37 m thick, of which the basal 15 m are saturated. Groundwater salinity ranges from 2 to 5 ppt in the area investigated, but is likely to increase towards the coast.

Alluvium along the current river course is mainly fine grained, and low yielding, and unlike the other major rivers, there is no known significant aquifer.

Reference: Hydrogeology Report HR 43 by C. Yesertener.

Cane River alluvium

The alluvium along the lower Cane River consists of relatively thin sands, interbedded with silt, along the current river course. Groundwater is fresh only close to the river, and is pumped by relatively low yielding bores for Onslow town water supply.

Reference: Hydrogeology Report 1989/4 by M. Martin.

A limited resource of fresh groundwater, recharged from the Cane River, also occurs in the Birdrong Sandstone and  fractured Proterozoic quartzites on the inland margin of the Carnarvon Basin, just downstream of the North West Coastal Highway crossing. This is currently not utilized.

Reference: Hydrogeology Report HR 32 by C. Yesertener and C.J. Prangley.

Robe River alluvium

The gravel aquifer along the lower Robe River extends from the Northwest Coastal Highway to the coast in a strip 3 to 5 km either side of the present river bed. The aquifer consists of gravel and cobbles up to 5 cm diameter, which are predominantly banded iron formation derived from Hamersley Basin rocks. The gravel reaches a saturated thickness of as much as 13 m, and the aquifer includes calcrete, probably part of the Trealla Limestone. The gravel is overlain by about 5 m of flood plain silt.

Recharge takes place from the river bed gravels when the river flows. Groundwater salinity ranges from about 0.5 ppt, similar to that of river flows, up to 1.2 ppt on the margin of the aquifer.

Bore yields in excess of 1000 kl/day have been achieved. Currently the aquifer is not developed, other than for pastoral use.

Reference: Commander, 1994.

Fortescue River alluvium

The gravel aquifer along the lower Fortescue River extends from the Northwest Coastal Highway to the coast in an alluvial fan, extending up to 15 km to the west of the present river bed. The aquifer consists of gravel and cobbles up to 5cm diameter, which are predominantly basalt derived from Hamersley Basin rocks. The gravel reaches a saturated thickness of as much as 15m, and is overlain by about 5m of flood plain silt.

Recharge takes place from the river bed gravels when the river flows. Groundwater salinity ranges from about 0.5 ppt, similar to that of river flows, up to 1 ppt on the margin of the tidal flats, where there is an interface with saline water.

Bore yields in excess of 500 kl/day have been achieved. Currently the aquifer is not developed, other than for pastoral use.

Reference: Commander, 1994 (ref 399).

Yule River alluvium

The alluvial aquifer along the Yule River has been investigated for about 30 km north of the North West Coastal Highway crossing, and extends about 5km either side of the river. There is a maximum thickness of about 60 m of alluvium at the northern end of the investigation area. The alluvium is composed of sands near the surface, gravels below, consisting of pebbles and cobbles, with a basal silt or clay. The zone of low groundwater salinity, less than 1 ppt, extends several kilometres either side of the river bed. 

Bore yields have been tested up to 1400 kL/day. The aquifer is currently used for Port Hedland town water supply

References: Whincup, 1967; Forth, 1972.

Turner River alluvium

Alluvium along the Turner River is developed downstream of about 5km north of the North West Coastal Highway crossing to a maximum depth of 44 m in the area investigated. The aquifer consists of thin clayey sands representing former river beds, beneath sandy clay flood plain deposits. Groundwater is also produced from the weathered bedrock below the alluvium. Fresh groundwater (less than 1 ppt) extends between 2 km and 5 km either side of the river.

Groundwater was formerly pumped for Port Hedland town water supply.

Reference: Farbridge, 1967.

De Grey River alluvium

A sand and gravel filled palaeovalley as much as 82 m deep extends from at least 30 km upstream of the North West Coastal Highway crossing, and runs to the east of the current De Grey River course downstream of the crossing. The saturated thickness of the alluvium exceeds 70 m in the north of the area investigated by Davidson (1973), and is likely to increase towards the coast. Groundwater salinity ranges from fresh to brackish, and bore yields have been tested to as much as 4500 kL/day.

Groundwater is currently utilized for Port Hedland town water supply, and was formerly used to supply Goldsworthy.

Reference: Davidson, 1973, 1975; Hydrogeology Report HR 34 by M. Martin.