1.1.7.1 Namoi river basin setting

Table 13 Management units of the Namoi river basin

Land management unit	Key features	Extent (ha)
Sedimentary hill tops and steep slopes (generally >15%)	Sedimentary or metamorphic hilltops. Soils are shallow lithosols and skeletal red-brown earths. Vegetation is characterised by natural pastures with open woodlands to open forests.	396,023
Sedimentary slopes (generally 8–15%)	A midslope land unit fringing the Liverpool Plains, Duri Hills and East Pilliga Hills. Soils are moderately shallow lithosols and red-brown earths with scattered rocky outcrops. Vegetation includes natural pastures, woodlands and forests.	442,300
Sedimentary footslopes (2–8%)*	Transition zone between the hillslopes and floodplains. Soils are deep red earths, red-brown earths and solodic soils with moderate fertility. Potential for perched watertables. Tree vegetation is a mixture of box, casuarinas and cypress. Major land use in native and improved pasture.	329,621
Sandy Pilliga footslopes	Occur at the transition zone from the hills to floodplain associated with the Pilliga sandstones. Soils are deep solodic soils and earthy sands with very sandy to sandy loam topsoil, with low fertility. Vegetation is mainly a mixture of white cypress casuarina type associations.	226,292
Riparian corridor*	Defined as the 20 m wide buffer from each streambank. Soil and vegetation types vary based on base geology and geomorphology. The riparian corridor is dynamic with varied geomorphology and large variance in water level.	93,827
Upland bogs and swamps*	Small peaty valley fills in the New England tablelands and the Liverpool Ranges. Recognised as significant water storages that release water gradually into the upper reaches of the river basin.	2,881
Central black earth floodplains*	Exist in association with major creeks and rivers in the central part of the river basin, consisting of floodways and floodplains. Soils are typically deep black earths, brown or grey clays and earthy sands. The land units support both farming and maintenance of native vegetation including river red gum communities. Floodplains have been extensively cleared for cropping. High quality groundwater occurs where alluvium overlays coarse gravels.	347,800
Recent western floodplains*	Includes recent floodplains along the Namoi River and Pian Creek within the Darling Riverine plains. Consists of inset meander plains and backplains dominated by very deep grey clays and minor black earths. High quality groundwater is common in deep gravels. Land use includes grazing and native or improved pastures. Flooding is common.	165,420
High western floodplains	Dominated by back plains which are a mixture of older alluvium and modern alluvium associated with less frequent flooding. Soils are dominated by grey clays with high subsurface salinities. Has been extensively cleared but Coolibah communities are scattered throughout.	178,030
Dry western floodplains	Characterised by a lack of major flooding and dominated by the oldest clay back plains along the former path of the Namoi. Dominated by a mixture of grey clays and brown clays. Subsoil sodicity and salt levels are high. The major land use is grazing of native pastures. Coolibah and River Coolibah communities are common, with low saltbush and mitchell grass understorey.	282,682
Central mixed floodplain soils*	Dominated by extensive meander plains with variable black earths, brown and grey clays, red-brown earths and hardsetting duplex soils. Deep freshwater aquifers are found where the alluvium sits on coarse gravel fill over basement material, recharged from surface streams with gravel beds well-connected to the underlying aquifers. Native vegetation is bimble box, white box, rough barked apple, river red gum and Myall with localised treeless plains dominated by plains grass.	224,822
Western hardsetting floodplains	Generally associated with the Bugwha formation, a series of coarse and sandy sediments. Soil types vary considerably with solodic and very sodic grey and brown earths common, very susceptible to scalding. Land use is grazing on native pastures. Vegetation includes bimble box, grey box black box, Coolibah, belah, bull oak wilga, warrior bush, leopardwood and buddah. Understorey consists of Acacia and saltbush.	115,058
Flat Pilliga outwash	Dominates the central and north-western sections of the Pilliga outwash. Dominated by deep solodic soils with sandy to loamy sand topsoils. Land use is diverse dominated by forestry and nature reserves with vegetation ranging from low heaths to open forests and woodlands.	441,308
Colluvial black earths (2–8%)	Alluvial plains and slopes between 2–8% derived from volcanic geological material. Soil predominantly black earths >2 m and reducing as slope increases. Land use is mainly summer and winter cropping on slopes less than 5% and grazing on higher slopes. Mostly cleared of native vegetation, although some box communities and isolated trees remain.	229,887
Basaltic slopes and hills (8–20%)	Flanking the southern edge of the Liverpool Plains with some occurrences associated with the Garrawilla, Warrumbungle and Nandewar basalts. Soils range from black earths to brown clays, red-brown earths with soil depth decreasing with increasing slope. This is a major recharge area with shallow watertables, and salinity is a minor problem associated with basalt flow edges. Vegetation is usually scattered timber of white and yellow box, Myall and rough barked apple with some river red gum along watercourses.	153,396
High fertility basalt uplands	A feature of the crest of the Liverpool Ranges and southern parts of the New England table lands. Soil types include Krasnozems, with black earths and chocolate soils common in lower rainfall areas. Land use is dominated by forestry and nature reserves. Vegetation is generally tall open forest grading to low alpine woodlands at elevation above 1100 m.	43,143
Steep basaltic hills (>20%)*	Basalt hill with slopes >20% flanking the southern edge of the Liverpool Plains with some occurrences with the Garrawilla, Warrumbungle and Nandewar basalts. Soils are shallow and range from black earths to prairie to brown clays, red-brown earths to lithosols on upper slopes and skeletal area. A major source of recharge into groundwater systems. Some grazing occurs on lesser slopes with deeper soils in valleys or hilltops. Vegetation is usually uncleared consisting of white and yellow box, Myall and rough barked apple.	103,987
Tableland granites	A feature of the New England tablelands part of the Namoi. Soils are earthy and siliceous sands as well as soloths and solodic soils. Land use is dominated by grazing on improved pasture, with some minor forestry and nature reserves. Soil acidity is common with some areas of salinity occurring in cleared areas. Vegetation is generally low open woodland with minor areas of open forest in wetter areas.	193,445
Tablelands sedimentary hills	A feature of the central parts of the New England Tablelands. Soils dominated by silty solodic soils and soloths. Land use is dominated by grazing on improved pastures, with some forestry, cereal cropping and horticulture. Induced soil acidity is common with some salinity in drier areas. Vegetation is generally tall open forest with some areas of low woodland and alpine woodland at higher elevations.	67,960
Peel floodplain*	The Peel floodplain from the main drainage for the Duri Hills, in the eastern and central Tamworth Ford belt section. This land management unit (LMU) is dominated by high quality chernozems utilised for cropping and intensive pasture production. High quality groundwater is common in this LMU, but the system is stressed. Vegetation is largely cleared but remnant river red gum, yellow box and rough barked apple occurs. Broad-scale flooding a feature of this landscape.	10,487
Duri hills	Low undulating hills between the New England tablelands and the Liverpool Plains. Soils are red-brown earths or non calcic brown soils. Soils are generally less than 1.5 m. Land use is dominated by a mosaic of winter cropping and grazing on improved and native pastures. Vegetation has been largely cleared but remanets are dominated by white and grey box.	144,827
Disturbed lands	Generally small road base quarry sites or landfill. Several large mining areas make up most of this LMU. Poorly protected disturbed sites form significant sediment and pollution sources in the Namoi.	2,519

*Characterised by high quality water resources

Source data: Namoi CMA (2009)

Major primary industries in the Namoi river basin include cotton, livestock production, grain and hay, poultry horticulture and forestry. The economic output from these industries is over $1 billion with dry land and irrigated agriculture contributing over half of this (Green et al., 2011). The major land use in the river basin is sheep and cattle grazing (over 61% of the river basin). Wheat, cotton and other broad acre crops are grown on the alluvial floodplains; there is over 800 km² of irrigation for cotton and in excess of 300 km² irrigated pasture and fodder crops. Extensive areas of native woodland (mostly Pilliga scrub) and forests occur in the middle of the Namoi river basin to the south of Narrabri and account for approximately 18% of the river basin. Major land use statistics are shown in Table 14.

Table 14 Land use statistics for the Namoi river basin

Land use type	Extent (km²)	Proportion of river basin (percentage)
Grazing	25,727	61.2%
Dryland cropping and horticulture	6,810	16.2%
Forestry	4,339	10.3%
Native landscapes	2,136	5.1%
Conservation	1,351	3.2%
Irrigation	1,259	3.0%
Residential	256	0.6%
Lakes, rivers, dams	139	0.3%
Wetland	12	<0.1%
Mining	7	<0.1%

Source data: Green et al. (2011)

Last updated:

5 January 2018

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