Soil/Landform Unit - Mount William Creek2

Mount William Creek with remnant vegetation aligning floodplains and significant creek flow

Area: 10 580 ha

0.45% of CMA region

This unit consists of a few small discreet depositional entities that form the upper part of the Mt William Creek

sequence that divides the Grampians Ranges (to the west) from the Dissected Uplands to the east. As a unit within the defined terraces and floodplains subdivision (2.1.7) of the Dissected Western Uplands, the extensive alluvial

Quaternary

sediments abut colluvial sediments (Grampians Plains) to the west, as well as older sedimentary and volcanic rock units (e.g. Mt Dryden) to the east. Dominated by alluvial plains, drainage depressions, alluvial flats and bordering dunes also occur within the plains. Drainage is mainly dendritic and extensive away from the main drainage lines. Soil types are predominantly yellow and brown gradational (

Dermosols

) and texture contrast soils (

Chromosols

) with yellow, brown and grey

sodic

texture contrast soils (

Sodosols

) occurring on lower slopes and minor depressions. Seasonal inundation is more likely due to runoff from these steeper surrounding slopes and the more extensive, flatter plains. Grazing (sheep and cattle) is the major enterprise. Common remnant vegetation communities recorded include woodlands (e.g. Lateritic, Plains Grassy, Heathy, Herb-rich) and Sand Heathland.

Looking south along Mount William Creek
	Red gum on alluvial plains

Component	1	2	3	4	5
Proportion of soil-landform unit	50%	15%	15%	15%	5%
CLIMATE Rainfall (mm)	Annual: 720
CLIMATE Rainfall (mm)	Annual: 720
Temperature (^oC)	Minimum 8, Maximum 20
Precipitation less than potential evapotranspiration	October–March
GEOLOGY Age and lithology	Quaternary fluvial gravel, sand and silt, gully alluvium; Cambrian basalt, andesite, boninite, rhyolite, gabbro and lithics
GEOLOGY Age and lithology
Geomorphology	2.1.7 Terraces and floodplains of the Dissected Western Uplands
LANDUSE	Uncleared areas: water supply; nature conservation Cleared areas: sheep and beef cattle grazing; dryland cropping; water supply
LANDUSE
TOPOGRAPHY Landscape	Alluvial plain
TOPOGRAPHY Landscape	Alluvial plain
Elevation range (m)	168–370
Local relief (m)	2
Drainage pattern	Dendritic
Drainage density (km/km²)	1.3
Landform	Alluvial plains
Landform element	Plain	Drainage depression	Alluvial flat	Drainage line	Dune
Slope and range (%)	1 (0-3)	1 (0-1)	0 (0-1)	1 (0-1)	2 (0-5)
Slope shape	Straight	Concave	Straight	Concave	Convex
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassy Woodland (38.6%), Plains Woodland/Plains SedgyWoodland/Damp Sands Herb-rich Woodland Mosaic (8.1%), Heathy Woodland (7.5%), Damp Sands Herb-rich Woodland (6.0%), Other (34.8%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	Fluvial gravel, sand and silt	Alluvial gravel, sand and silt	Alluvial gravel, sand and silt	Alluvial gravel, sand and silt	Aeolian dune sand
SOIL Parent material	Fluvial gravel, sand and silt	Alluvial gravel, sand and silt	Alluvial gravel, sand and silt	Alluvial gravel, sand and silt	Aeolian dune sand
Description (Corangamite Soil Group)	Yellow and brown gradational and texture contrast soils (11)	Sodic brown, yellow and grey texture contrast soils (12)	Yellow and brown gradational and texture contrast soils (11) and sodic brown, yellow and grey texture contrast soils (12)	Yellow and brown gradational and texture contrast soils (11) and sodic brown, yellow and grey texture contrast soils (12)	Sandy gradational soils (14)
Soil type sites	WLRA66, WLRA63	DOAGW12, WLRA144, WLRA145, WLRA148	WLRA66, WLRA63, DOAGW12	WLRA66, WLRA63, DOAGW12	GRAMP335
Surface texture	Loamy sand	Loam, fine sandy (heavy)	Loam, fine sandy to loamy sand	Loam, fine sandy to loamy sand	Sandy loam
Permeability	Moderate to high	Slow	Slow	Very slow	High
Depth (m)	> 2	> 2	> 2	> 2	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Lighter surface susceptible to sheet and rill erosion and compaction. Subsoil susceptible to rill and gully erosion where sodic and deeper. Lighter variants are well drained.	Lighter surface susceptible to sheet and rill erosion and compaction. Subject to periodic inundation and waterlogging, especially during flood events. Lighter soil variants are well drained within the depressions. Upper soil susceptible to acidification.	Lighter surface susceptible to sheet and rill erosion and compaction. Subject to periodic inundation and waterlogging, especially during flood events. Lighter soil variants are well drained within the depressions. Upper soil susceptible to acidification.	Lighter surface susceptible to sheet and rill erosion and compaction. Subject to periodic inundation and waterlogging, especially during flood events.	Light sandy soils generally rapidly drained. Weakly coherent surfaces with little organic matter are susceptible to sheet and wind erosion where exposed. Acidic soils with low inherent fertility.

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