Soil/Landform Unit - Six Mile and Seven Mile Creeks

Erosional scars of Six Mile and Seven Mile creeks surrounding the Concongella hills

Area: 6788 ha

0.29% of CMA region

The Six Mile and Seven Mile creeks are located east of Stawell and west of the upper Wimmera River. These creeks are drainage pathways for surface flow and groundwaters of the Concongella hills and surrounding rises. Belonging to the terraces and floodplains (2.1.7) division of the Dissected Western Uplands, these plains, flats and drainage depressions are fed from the south, dissect the outwash terrain and flow northward into the broad Wimmera River alluvial plain. Hill slopes and crests, along with rise slopes (upper and lower slopes) contribute to the distinct drainage depressions with drainage lines. Drainage consists of concentrating flow from the Concongella hills and the outwash slopes. Soils include yellow and brown gradational (

Dermosols

) and texture contrast soil (

Chromosols

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

Sodosols

) found in the poorer drained positions. Sheet and rill erosion are potential issues given the texture contrast soils, as is gully erosion. These creeks are used for grazing (sheep, beef cattle), with occasional dryland cropping. Remnant woodland vegetation communities include Heathy Woodland, Plains Grassy Woodland, Alluvial Terraces Herb-rich Woodland, Creekline Grassy Woodland, Grassy Woodland and Plains Woodland.

Gully and tunnel erosion at the head of Six Mile Creek
	Six Mile Creek

Component	1	2
Proportion of soil-landform unit	40%	60%
CLIMATE Rainfall (mm)	Annual: 575

Temperature (^oC)	Minimum 8, Maximum 20
Precipitation less than potential evapotranspiration	October–April
GEOLOGY Age and lithology	Quaternary alluvial gravel, sand and silt; Cambrian marine sandstone, siltstone and biotite schist (St Arnaud Group); Devonian granite (Stawell Granite)

Geomorphology	2.1.7 Terraces and floodplains of the Dissected Western Uplands
LANDUSE	Uncleared areas: nature conservation; water supply Cleared areas: sheep and beef cattle grazing; dryland cropping

TOPOGRAPHY Landscape	Drainage complex

Elevation range (m)	195–290
Local relief (m)	3
Drainage pattern	Dendritic
Drainage density (km/km²)	2.3
Landform	Alluvial plains–drainage depressions
Landform element	Creek/drainage depression/gully	Alluvial plain
Slope and range (%)	1 (0-2)	2 (0-5)
Slope shape	Concave	Straight
NATIVE VEGETATION Ecological Vegetation Class	Grassy Woodland (41.3%), Creekline Grassy Woodland (20.6%), Plains Grassy Woodland (17.1%), Other (19.1%)

SOIL Parent material	Fluvial gravel, sand and silt	Alluvial gravel, sand and silt

Description (Corangamite Soil Group)	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, DOAGW12	WLRA66, WLRA63, DOAGW12
Surface texture	Loamy sand	Loamy sand
Permeability	Moderate to very slow	Moderate to slow
Depth (m)	> 2	> 3
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Lighter surface susceptible to sheet and rill erosion and compaction, especially surfaces with low organic matter. Subsoil susceptible to gully erosion where sodic subsoils are exposed. Lighter variants are well drained.	Lighter surface susceptible to sheet and rill erosion and compaction, especially surfaces with low organic matter. Subsoil susceptible to gully erosion where sodic subsoils are exposed. Lighter variants are well drained.

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