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Rotamah (Rh)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Rotamah - geoArea: 14 sq. km (0.1%)

Rotamah land system occurs near Lakes Entrance on Holocene sands added to the inner barrier; these sands are adjacent to the modern coastal foredune system. As with the rest of the inner barrier which is of older sands, an uneven sand sheet has formed from a close sequence of beach-ridge deposits. There is also a slightly different vegetation type, probably resulting from the slightly more humid climate.

Although the marine sands originally contained shell fragments, the carbonate has been removed by leaching. The sands are now acidic, of very low fertility, droughty and susceptible to wind erosion.

The vegetation is a ferny open woodland I dominated mainly by E. botryoides, with Banksia spp. and Pteridium esculentum.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Rotamah - image
An aerial photograph showing the causeway to Rotamah Island with a typical woodland of
Eucalyptus hotryoides and Banksia species in the background

CLIMATE
Rainfall, mean (mm)
Temperature, mean (C)
Seasonal growth limitations

    Annual 600 - 900; lowest July or August (40 - 70), highest October (60 - 90)

    Annual 12 - 14; lowest July (9 - 10), highest February (19 - 20)
    Temperature <10C (av.): No months
    Rainfall < potential evapotranspiration: December – March
GEOLOGY
Age, lithology

    Holocene barrier and coastal foredune sand deposits
PHYSIOGRAPHY
Landscape
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

    Uneven sand sheets formed from a close sequence of beach ridge deposits

    0 - 20
    0 - 5
    Nil
    0
PRESENT LAND USE
    Mostly uncleared: mainly within The Lakes National Park; some privately owned uncommitted lands

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

LAND COMPONENT
Percentage of land system
Diagnostic features
1
90
Ridges
2
10
Swales
PHYSIOGRAPHY
Slope %, typical and (range)
Slope shape
4, (2 - 8)
Mainly convex
<1, (0 - 2)
Concave or straight
SOIL
Parent material
Sand of marine origin
Description
No observations — probably leached acidic sand, pale or whitish in the subsurface, generally over coffee rock or bright yellowish brown sand;
light coloured sand below
Classification
Probably Podzols; Uc4.3-, Uc2.3-, Uc4.2-, Uc2.2-
Siliceous Sands; Uc1.21
Surface texture
Sand
Surface consistence
Loose or soft
Depth (m)
>2.0
Nutrient status
Very low
Available soil water capacity
Very low
Perviousness to water
Very rapid
Drainage
Somewhat excessive
Exposed stone (%)
0
Sampled profile number
-
NATIVE VEGETATION
Structure of vegetation and
characteristic species of
dominant stratum
(+ Predominant species)
Ferny open woodland I:
Variable composition — species including E. botryoides, E. viminalis var. racemosa, Banksia serrata, B. integrifolia (near lake shores) and Pteridium esculentum

    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 increased deep percolation and leaching
    Nutrient loss
    1,2; high
    Not determined
    Removal of trees
    Increased movement of water to groundwater
    Increased exposure of surface soil
    Increased wind velocity over soil and increased detachment of sand
    Wind erosion





    Wave erosion
    1; high
    2; moderate




    2; moderate
    Uncommon





    Uncommon
    Clearing, overgrazing, road building and other earth-moving activities, rabbit burrowing, trafficking by stock and vehicles.

    Removal of protective
    reeds along shore line
    Encroachment by sand





    Turbidity of lake waters
    Increased physical pressure on soil
    Increased compaction
    Structure decline
    1; very low
    2; low - moderate
    Not determined
    Increased trafficking, overgrazing, export of organic matter
    -
    Increased soil disruption
    Increased loosening of sand
    Wind erosion


    Wave erosion
    1; high
    2; moderate

    2; moderate
    Uncommon


    Uncommon
    As for wind erosion
    Above

    As for wave erosion
    above
    Encroachment by sand


    Turbidity of lake waters
    Comments: Regeneration of vegetative cover is poor in areas exposed to wind and wave erosion, and expensive remedial works may be required
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