Soil/Landform Unit - Mount William Creek

Mount William Creek at Dadswells Bridge before anabranching into the Wimmera River

Area: 13 295 ha

0.57% of CMA region

This unit consists of a few large and some small discreet depositional entities that form the lower part of the Mt William Creek

alluvial

sequence. Dividing the Grampians Ranges to the west from the Dissected Uplands to the east, this extensive alluvial unit of

Quaternary

sediments abuts colluvial sediments (Grampians Plains) to the west, the Wimmera River to the north and other sedimentary and volcanic rock units (e.g. Mt Dryden, Mokepilly) to the east. Alluvial flats and footslopes, plains, anastomotic plains and drainage lines, and bordering dunes are all present. Drainage is mainly dendritic and extensive away from the main drainage lines, which may be anastomotic. Site drainage is generally slow. Soils are predominantly yellow and brown gradational (

Dermosols

) and texture contrast soils (

Chromosols

) with yellow, brown and grey sodic texture contrast soils (

Sodosols

) occurring on poorly drained areas. Sheet and rill susceptibility is associated with the lighter top soils, while dunes are susceptible to wind erosion also. Seasonal inundation is likely in lower areas. Grazing (sheep and cattle) is the major enterprise. Woodlands such as Plains Grassy Woodland, Heathy Woodland, Creekline Grassy Woodland, Grassy Woodland, Plains Woodland and Shrubby Woodland are the most common remnant vegetation found.

Hillslopes leading to Mount William Creek
	Sandy undulations within the alluvial floodplain

Component	1	2	3	4
Proportion of soil-landform unit	25%	5%	60%	10%
CLIMATE Rainfall (mm)	Annual: 580
CLIMATE Rainfall (mm)	Annual: 580
Temperature (^oC)	Minimum 8, Maximum 20
Precipitation less than potential evapotranspiration	October–April
GEOLOGY Age and lithology	Quaternary fluvial silt, sand and minor gravel; Cambrian ‘greenstone’ - basalt, andesite, boninite, rhyolite, gabbro, lithic sandstone, chert, shale and breccia
GEOLOGY Age and lithology
Geomorphology	2.1.5 Cainozoic landscapes of the Dissected Western Uplands
LANDUSE	Uncleared areas: water supply; nature conservation Cleared areas: sheep and beef cattle grazing; dryland cropping; water supply; sand extraction
LANDUSE
TOPOGRAPHY Landscape	Alluvial plain
TOPOGRAPHY Landscape	Alluvial plain
Elevation range (m)	141–285
Local relief (m)	2
Drainage pattern	Dendritic
Drainage density (km/km²)	1.5
Landform	Plains	Low dunes	Alluvial plains
Landform element	Plain	Dune	Alluvial flat and footslope	Anastomotic plain and drainage line
Slope and range (%)	4 (1-7)	5 (2-9)	1 (0-2)	1 (0-2)
Slope shape	Straight	Convex	Straight	Straight
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassy Woodland (22.0%), Creekline Grassy Woodland (19.7%), Red Gum Wetland (14.2%), Plains Woodland (8.6%), Other (33.1%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	Fluvial gravel, sand and silt	Aeolian dune sand	Alluvial gravel, sand and silt	Alluvial gravel, sand and silt
SOIL Parent material	Fluvial gravel, sand and silt	Aeolian dune sand	Alluvial gravel, sand and silt	Alluvial gravel, sand and silt
Description (Corangamite Soil Group)	Yellow and brown gradational and texture contrast soils (11)	Sandy gradational soils (14)	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)
Soil type sites	WLRA66, WLRA63	GRAMP335	WLRA66, WLRA63, DOAGW12	WLRA66, WLRA63, DOAGW12
Surface texture	Loamy sand	Sandy loam	Loam, fine sandy to loamy sand	Sany loam to clay loam
Permeability	Moderate to high	High	Slow	Slow to very slow
Depth (m)	> 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.	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.	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. Upper soil susceptible to acidification.	Soil surface susceptible to compaction. Subject to periodic inundation and waterlogging, especially during flood events. Lighter soil variants are well drained. Upper soil susceptible to acidification.

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