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Traralgon (Tg)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Traralgon- geoArea: 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 study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Traralgon- image
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 <10C (av.): June - August
    Rainfall < potential evapotranspiration: November – March
GEOLOGY
Age, lithology
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- csA 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
    Form
    Susceptibility of components
    Incidence with components
    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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