1.1.2 Geography

Summary

The Maranoa-Balonne-Condamine subregion, in the Northern Inland Catchments bioregion, is located predominantly within the central and eastern part of the Queensland Murray–Darling Basin, with a small extension into NSW, west of the western margins of the three other Northern Inland Catchments subregions: Gwydir, Namoi and Central West (Figure 3). It spans an area of 144,890 km², extending from the headwaters of the Condamine River in the east and the Maranoa River in the north-west to floodplains of the Upper Darling Plains, where the river system fans out into a number of distributary channels, which discharge into the Barwon-Darling River system and the Narran Lakes system. Maximum and minimum elevations for the subregion itself are about 1350 mAHD in the Great Dividing Range and 100 mAHD west of Brewarrina in NSW, respectively.

The main rivers draining the subregion are the Condamine-Balonne, Maranoa, Moonie and Macintyre rivers, but these become or feed into other rivers, including the Narran, Culgoa and Bokhara rivers, and ultimately the Barwon-Darling River. The most significant water-dependent assets are the nationally significant Balonne River Floodplains, Gums Lagoon, Lake Broadwater, and Blackfellows Creek. The Culgoa River Floodplains (Queensland and NSW) and the Narran Lakes system (NSW) are downstream of the subregion. The northern part of the Narran Lakes system is an internationally significant wetland under the Ramsar Convention.

Soils vary considerably across the subregion, with extensive areas of Vertosols and Sodosols. The Vertosols are well structured and have a good mix of pores for both transmitting and storing water, so plant growth on these soils is typically very good relative to other soil types and they are productive or highly productive for agriculture. Kandosols are extensive in the west, particularly on the lower Balonne and lower Moonie floodplains. Overall, the land and soil resources of the subregion mean that the majority of the area is deemed ‘good quality agricultural land’ (QMDC, 2008). The most limiting land and soil hazards in the subregion are soil fertility decline, soil acidification and salinity. A number of legal and planning instruments have been introduced in Queensland to protect and conserve the land and soil resources.

The subregion has undergone significant modification of its land cover, with most areas having between 10 and 30% of their pre-clearing vegetation. Since the introduction of Queensland’s Vegetation Management Act 1999, land clearing rates have fallen dramatically. The historical loss of wetlands is up to 70% across the Queensland Murray–Darling Basin. There are six endangered ecological communities that are protected under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999.

The subregion has an average annual rainfall of 585 mm (1900 to 2011). The climate varies from temperate conditions with no dry season and warm to hot summers in the upland areas to hot, persistently dry climate in the west.

The main population centres are Toowoomba, Warwick, Dalby, Chinchilla, Roma, St George and Goondiwindi. Agriculture is the mainstay of the economy, with the gross value of agricultural production in the Condamine and the Border Rivers Maranoa-Balonne natural resource management regions in 2010–11 estimated at $2.4 billion (ABS, 2012). Domestic tourism contributed $1.1 billion to the regional economy in 2011–12 (TQ, 2012).