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Soil/Landform Unit 1

Landform Unit Description



Unit 1 image-a
The steep slopes of this unit line the Lal Lal Reservoir. This reservoir is a major water supply of the Central Highlands
      Area: 2685 ha
      0.20% of CMA region

      Hills and scarps associated with Ordovician sandstones and shales are the main landforms of this distinct unit near Lal Lal. Surrounding the Lal Lal Reservoir, this unit has a high level of remnant vegetation on these steep slopes that drain towards the reservoir. As part of the Western Uplands, this unit is significant for its vegetation but also its water catchment value for the Central Highlands. Native vegetation classes of these hills include Valley Grassy, Grassy Dry and Herb-rich Foothill Forests as well as Plains Grassy, and Grassy Woodlands. Whilst the major land use of this unit is a water supply catchment area, other land uses such as grazing and cropping also occur. Soils include red mottled yellow gradational or texture contrast soils on the slopes, shallow stony red gradational soils on crests, black gradational soils on drainage depressions and shallow brown texture contrast/gradational soils on scarps and steep slopes. The main hazards to land use are overland flow causing sheet and rill erosion, gully erosion (where subsoils are exposed) and minor compaction.
Geomorphology map unit 1

Unit 1 image-b
Steep slopes and scarps that line Lal Lal Reservoir.
These scarps include
Ordovician sediments of this unit
Unit 1 cross section
Unit 1 graphUnit 1 image-c
Lal Lal Reservoir

Component
1
2
3
4
5
6
Proportion of soil-landform unit
3%
34%
2%
31%
20%
10%
CLIMATE
Rainfall (mm)

Annual: 720
Temperature (oC)
Minimum 7, Maximum 17
Precipitation less than potential evapotranspiration
November-March
GEOLOGY
Age and lithology

Ordovician marine sandstone and shale, Quaternary basalt and alluvium
Geomorphology
LANDUSE

Uncleared: Nature conservation; water supply

Cleared: Sheep and beef cattle grazing; softwood plantations; cropping (cereal); water supply
TOPOGRAPHY
Landscape

Steep hills and scarp beside main creek including channel
Elevation range (m)
303-540
Local relief (m)
65
Drainage pattern
Dendritic
Drainage density (km/km2)
3.7
Landform
Hill
Scarps with locak rock outcrop
Creek bed
Landform element
Moist protected slopes
Dry exposed slopes
Drainage lines
Crest
Slope
Floodplain
Slope and range (%)
15 (12-35)
15 (10-25)
3 (1-5)
3 (1-8)
13 (10-35)
2 (1-5)
Slope shape
Straight
Straight
Concave
Convex
Convex
Straight
NATIVE VEGETATION
Structure

Tall open forest

Open forest

Open forest

Open forest

Open forest

Open forest
Dominant species
E. obliqua, E. ovata, E. radiata,
E. viminalis
E. obliqua, E. dives, E. radiata,
E. viminalis
E, ovata, E. radiata, E. viminalis
E. obliqua, E. dives, E. radiata,
E. viminalis
E. viminalis, E. ovata
E. viminalis, E. ovata
SOIL
Parent material

In situ weathered sandstone and shale

In situ weathered sandstone and shale

Alluvium, clay, silt, sand, grvel

In situ weathered sandstone and shale

In situ weathered basalt

Unconsolidated sedimentary and in situ weathered Ordovician sediments
Description
(Corangamite Soil Group)
Red mottled yellow and brown gradation (25) or texture contrast soils, fine structure (26)
Red mottled yellow and brown gradational (25) or texture contrast soils, fine structure (26)
Black gradational soil - variable (34)
Shallow stony red and brown or yellow gradational soil (40, 41)
Shallow brown texture contrast or gradational soils (37)
Black clay soil, coarse structure (31)
Soil type sites
CLRA1, SW29, SW57
BD1, SW96, BD3
Surface texture
Fine sandy loam
Fine sandy loam
Clay loam
Gravelly loam
Clay loam
Clay
Permeability
High
High
Moderate to low
High
High
Low
Depth (m)
1
2
>1
0.5
1
1.5
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Steep slopes and hardsetting surfaces can cause overland flow, and sheet and rill erosion.
Steep slopes and hardsetting surfaces can cause overland flow, and sheet and rill erosion. Soil compaction also a limitation when soils are waterlogged.
Moderate permeability soils with hardsetting surfaces. Overland flow and subsurface flow compound waterlogging and gully erosion. Soil compaction also a limitation when soils are waterlogged.
Moderate permeability soils with hardsetting surfaces. Overland flow and subsurface flow compound waterlogging and gully erosion. Soil compaction also a limitation when soils are waterlogged.
Slopes and hardsetting surfaces can cause overland flow and sheet and rill erosion.
Poorly drained site with low permeability can cause overland flow. Waterlogging along with streambank erosion and soil compaction are issues.
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