1.1.2 Geography


The Northern Sydney Basin bioregion covers an area of about 17,390 km2, of which the Gloucester subregion covers about 348 km2. The Gloucester subregion is defined by the geological Gloucester Basin. It is located just north of the Hunter Valley in NSW, it is approximately 85 km north-northeast of Newcastle and relative to proximal regional centres is 60 km south-west of Taree and 55 km west of Forster. The subregion extends 55 km north–south (at its longest) and 15 km east–west (at its widest). Elevation in the subregion ranges from 10 to 515 m (Australian Height Datum), and it is mostly undulating with relative low slopes; some steep slopes are found at the edge of the subregion in bordering mountain ranges. Soils are mainly Kurosol (62.3%); both Rudosol and Ferrosol are also present. Pre-European vegetation was dominated by eucalypt forest and current vegetation cover is mainly persistent vegetation, associated with the border forests and grazing (the primary land use); vegetation in the grazing areas grows more in summer. Vegetation height exceeds 30 m in the forests. There are numerous rivers in the subregion which straddles a catchment divide; northern-flowing rivers contributing to the Manning River and discharging to the Tasman Sea beyond Taree and the southern-flowing rivers contributing to the Karuah River and discharging into Port Stephens. About 5000 people live in the subregion, primarily located in the towns of Gloucester and Stroud. Water for these towns is extracted from local rivers, and there are no major dams or major wetlands in the subregion. From a groundwater perspective it is a closed system. The climate is sub-tropical, characterised by summer dominant precipitation. Average precipitation over the last 30 years (1982 to 2012) for the subregion was 1095 mm/year with potential evapotranspiration (PET) of 1587 mm/year. There were no distinctive precipitation trends over this period but there was a decreasing trend for PET due to declining rates of wind speed, net radiation and vapour pressure deficit offsetting PET increases associated with rising air temperatures. Future precipitation may decrease and accordingly there may be a decrease in runoff generations from the Gloucester subregion.

Last updated:
5 January 2018