Traralgon (Tg)

	Area: 96 sq. km (0.5%) Drainage depressions along tributaries of the La Trobe River, in which fine-textured alluvium predominates, have been mapped as the Traralgon land system. Variability in stream hydrology and in the nature and history of the catchments has affected the characteristics of these areas. Most have narrow, alluvial plains, often poorly drained, and more or less sinuous, central stream channels. In places there is a pattern of slightly depressed, abandoned stream channels. Some artificial channels have been dug to promote drainage. Post-settlement increments of alluvium are common. Thomson land system also occurs on the lowest, clayey terraces but Traralgon differs from it in occurring along smaller streams in the more humid parts of the Western lowlands. Flood regime and native vegetation also differ.	A broad, alluvial terrace adjacent to the incised system
Impeded soil drainage and relatively youthful parent materials have resulted in little soil development beyond the accumulation of organic matter in the topsoil, the formation of mottles and the development of weak to moderate blocky structure below the topsoil. Minor variations in soil features are often traceable to differences in soils of the source catchments. Erosion hazards are minor but human activities in the catchments may lead to large deposits of sediments on the drainage depressions. The original vegetation, probably open forest II or III, may often have been shrubby. It is now largely removed.

CLIMATE Rainfall mean (mm) Temperature, mean (°C) Seasonal growth limitations	Annual 700 - 1200; lowest January (40 - 70), highest October (70 - 100) Annual 12 - 14; lowest July (8 - 10), highest February (19 - 21) Temperature <10°C (av.): June - August Rainfall < potential evapotranspiration: November – March
GEOLOGY Age, lithology	Holocene fluviatile deposits, mostly clayey
PHYSIOGRAPHY Landscape Elevation range (m) Relative relief (m) Drainage pattern Drainage density (km/km²)	Narrow poorly drained alluvial plains with small meandering streams 20 - 500 0 - 5 Channel with closely-spaced meanders 5.0
PRESENT LAND USE	Mostly cleared: grazing of beef and dairy cattle on improved or native pastures; some apiculture

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Traralgon- cs

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Traralgon- graph

LAND COMPONENT Percentage of land system Diagnostic features	1 100 Drainage depressions and minor terraces
PHYSIOGRAPHY Slope %, typical and (range) Slope shape	<2, (0 - 10) Straight
SOIL
Parent material	Mostly clayey alluvium
Description	Mainly very dark greyish brown silty loam to clay loam topsoil, in places quite organic, commonly with fine yellowish brown mottles, grading into greyish brown or grey strongly mottled clay loam to clay subsoil with blocky structure; profiles usually mildly to moderately acidic throughout; stratification common. Small areas of better drained whole-coloured soils.
Classification	Wiesenboden; some Humic Gleys; Brown Earths in occasional well drained sites Gn4.51, Gn4.52, Gn4.41, Gn3.41, Gn2.81, Uml.44, Uf6.12, Dd2.21
Surface texture	Silty loam to clay loam
Surface consistence	Friable to firm when moist
Depth (m)	>2.0
Nutrient status	Moderate to high
Available soil water capacity	Moderate
Perviousness to water	Slow
Drainage	Mostly poor to somewhat poor; in places moderately good to good
Exposed stone (%)	0
Sampled profile number	-
NATIVE VEGETATION Structure of vegetation and characteristic species of dominant stratum (+ Predominant species)	Open forest II, III, often shrubby: Mainly E. ovata+; better drained sites with E. obliqua+ and E. radiata+ or E. viminalis+

Disturbance	Affected process and trend	Primary resultant deterioration			Casual activities	Primary off-site process
Disturbance	Affected process and trend	Form	Susceptibility of components	Incidence with components	Casual activities	Primary off-site process
Alteration of vegetation: — reduction in leaf area, rooting depth and/or perenniality	Reduced transpiration, resulting in raised watertable	Waterlogging	1; low - moderate	Common: in low-lying areas	Reduced plant water-use in the catchment	Increased run-on and ponding in low-lying areas
Increased exposure of surface soil	Increased soil detachment by flood waters	Scour erosion	1; very low	Uncommon	Overgrazing, cultivating and earth-moving activities.	Increased sediment load and turbidity
Increased physical pressure on soil	Increased compaction	Structure decline	1; moderate	Uncommon	Increased trafficking, cultivation, overgrazing, export of organic matter	-
Increased soil disruption	Increased soil break-up	Streambank erosion	1; low	Uncommon	As for scour erosion above	Increased sediment load and turbidity of streams.
Comments: -

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