Soils on Quaternary Unconsolidated Sediments

Qap - Alluvial Plains | Qya - Alluvium - Variable Soils

Alluvium - Variable Soils

This unit represents 3.6% of the survey area or 7.4 km2 The unit consists of river deposits of gravel and sand along the main streams in the Shire, such as the West Branch of the Moorabool River. There are often up to four recognizable terraces with soil profiles tending to become more differentiated (i.e. duplex rather than uniform) the further you go away from the stream. The predominant land use is grazing, and a high flood risk limits more intensive uses.

COMPONENT	1	2	3	4
Proportion %	91	3	3	3
CLIMATE (Average) Rainfall mm	500 - 760
*Temperature °C	Average annual 12⁰C
*Seasonal growth limitations	Temperature less than 10⁰C May - September
GEOLOGY Age, growth	Quaternary; river deposits, gravels, sands & clays
TOPOGRAPHY Landscape	Alluvium of the southern creeks of the Shire
Elevation (range) m	321
Local relief (av.) m	1-3
Drainage pattern	-
Drainage density km/km²	3.3
Land form	Terrace 1	Terrace 2	Terrace 3	Terrace 4
Position on land form	-	-	-	-
Slope (av.) ,%, slope shape	1-2 ; Straight	1-2 ; Straight	1-2 ; Straight	1-4; Straight
NATIVE VEGETATION Structure	Woodland (?)
Dominant species	E. viminalis, E. radiata
SOIL Parent material	Unconsolidated gravel, sand, silt and clay
Description	Dark brown soil, Uniform texture (variable)	Yellow brown duplex soil	Yellow duplex soil, coarse structure	Yellow duplex soil
Surface texture	Fine sandy clay loam	Sandy clay loam	Medium sandy clay loam	Clay loam
Permeability	Moderate-low	Moderate-low	Moderate-low	Moderate-low
Depth (av.) in	2	2	2	2
LAND USE	Grazing
SOIL DETERIORATION Critical land features	Low lying areas receiving drainage	Low permeability, weak surface structure hard setting surface
Processes	Waterlogging, overland flow	Overland flow; movement of salts, subsurface flow, waterlogging
Forms	Stream bank erosion, gully erosion	Stream bank erosion, gully erosion, compaction

* Ballan figures

LAND UNIT: Alluvium – variable soils

COMPONENT: 1 – Terrace 1 – Dark brown soil – uniform texture (often flood prone)

MAP SYMBOL: Qya 1

CAPABILITY OF THE LAND TO SUPPORT VARIOUS ACTIVITIES			CAPABILITY OF THE LAND TO SUPPORT SUBDIVISION
ACTIVITY	RATING	MAJOR LIMITING FEATURES OF THE LAND	SUBDIVISION TYPE	RATING	MAJOR LIMITING ACTIVITIES
Building houses	Very poor to poor	Depends on flood risk (return period) also variable soil drainage.	Urban (sewered)	Very poor	Building houses; secondary roads.
Absorption fields	Very poor	Soil drainage-seasonal watertable; proximity to creek.	Small Farmlets 4 ha	Very poor	Building houses; gravel roads; access tracks; absorption fields - effluent; (otherwise fair for small farm dams).
Secondary roads	Poor	Soil drainage-seasonal watertables.	Large Farmlets 16 ha	Poor	Building houses; access tracks; absorption fields - effluent.
Gravel roads	Poor	Soil drainage-seasonal watertable	Bush Blocks 4 ha.	Very Poor	Building houses; gravel roads; access tracks; absorption fields - effluent. Uncleared areas are rare.
Access tracks	Poor	Soil drainage; seasonal watertable-pot holes
Shallow excavations	Poor	Seasonal watertable (good if excavation is in dry months).
Small farm dams	Fair to poor	Variable construction material; storage to excavation ratio.
Sewerage lagoons	Poor	Percolation rate; proximity to creek.
Topsoil - Quality	Good	Thin layer
- Removal	Fair	Soil drainage; proximity to creek.
- Resowing	Fair
Sand - Quality	Variable	Some areas of sand of various quality and quantities.
- Operation
Gravel - Quality	Variable	Areas of gravel of various quality and quantities.
- Operation
Grazing	Good	Soil drainage in wet months.
Cultivation	Fair	Soil drainage in winter months; Some areas flood.
Clearing	Good to very poor	Depending on proximity to the creek or drainage line.

EFFECT OF SUBDIVISION OF THE LAND ON TOWN WATER SUPPLY
URBAN:	This unit is a geological flood plain. Floods are likely to be the major hazard to urban development. Note. also that these areas are close to watercourses and therefore would be better left as a buffer zone.
FARMLET:	Although sections of this unit may be included as part of a larger farmlet, housing, access roads etc., should not be constructed on this unit. It should remain for grazing, cultivation or recreation. Systems of disposal of effluent by soil absorption may present stream pollution problems.
BUSH BLOCK:	Uncleared areas are rare. The comments for "Farmlets" would apply to bush blocks.

LAND UNIT: Alluvium – variable soils

COMPONENT: 3 – terraces 3 – yellow duplex soil

MAP SYMBOL: Qya 3

CAPABILITY OF THE LAND TO SUPPORT VARIOUS ACTIVITIES			CAPABILITY OF THE LAND TO SUPPORT SUBDIVISION
ACTIVITY	RATING	MAJOR LIMITING FEATURES OF THE LAND	SUBDIVISION TYPE	RATING	MAJOR LIMITING ACTIVITIES
Building houses	Fair	Soil drainage-seasonal watertable.	Urban (sewered)	Fair to poor	Building houses; secondary roads.
Absorption fields	Poor	Soil drainage-seasonal watertable; percolation rate; proximity to creek.	Small Farmlets 4 ha	Poor	Absorption fields - effluent; (otherwise-fair: building houses; gravel roads; access tracks).
Secondary roads	Fair	Soil drainage-seasonal watertable	Large Farmlets 16 ha	Poor	Absorption fields - effluent; (otherwise-fair: building houses; access tracks).
Gravel roads	Fair	Soil drainage (seasonal).	Bush Blocks 4 ha.	Poor	Absorption fields - effluent; (otherwise-fair: building houses; gravel roads; access tracks).
Access tracks	Poor	Soil drainage (seasonal).
Shallow excavations	Fair	Soil drainage (seasonal).
Small farm dams	Good
Sewerage lagoons	Poor	Small areas; creek proximity
Topsoil - Quality	Fair	Hardsetting
- Removal	Poor	Thin layer
- Resowing	Fair	Poorly structured subsoil & drainage.
Sand - Quality	Poor	Sand deposits are rare.
- Operation
Gravel - Quality	Poor	Gravel deposits are rare
- Operation
Grazing	Good to fair	Drainage; impermeable clay
Cultivation	Fair to poor	Hardsetting topsoil; impermeable subsoil; soil drainage.
Clearing	Good

EFFECT OF SUBDIVISION OF THE LAND ON TOWN WATER SUPPLY
URBAN:	Note that these areas are close to major watercourses and the creek environment would be better protected if they were included in a buffer zone, free from development.
FARMLET:	As for component 1, the lower terrace (terrace 1), housing, access and effluent disposal would be better confined to a unit further from the watercourse to protect the creek environment.
BUSH BLOCK:	Uncleared areas are rare.

LAND UNIT: Alluvium – variable soils

COMPONENT: 4 – Higher terrace number 4 – yellow duplex soil

MAP SYMBOL: Qya 4

CAPABILITY OF THE LAND TO SUPPORT VARIOUS ACTIVITIES			CAPABILITY OF THE LAND TO SUPPORT SUBDIVISION
ACTIVITY	RATING	MAJOR LIMITING FEATURES OF THE LAND	SUBDIVISION TYPE	RATING	MAJOR LIMITING ACTIVITIES
Building houses	Fair	Soil drainage; temporary perched watertables	Urban (sewered)	Fair	Building houses; secondary roads; shallow excavations.
Absorption fields	Poor	Soil drainage; temporary perched watertables; percolation rate.	Small Farmlets 4 ha	Poor	Absorption fields - effluent; (otherwise-fair:- building houses, gravel roads; access tracks; small farm dams).
Secondary roads	Fair	Soil drainage; temporary perched watertables.	Large Farmlets 16 ha	Poor	Absorption fields - effluent; (otherwise-fair: building houses; access tracks; small farm dams).
Gravel roads	Fair	Soil drainage; temporary perched watertables.	Bush Blocks 4 ha.	Poor	Absorption fields - effluent; (otherwise-fair: building houses; gravel roads; access tracks).
Access tracks	Fair	Soil drainage; temporary perched watertables.
Shallow excavations	Fair	Soil drainage; temporary perched watertables.
Small farm dams	0-2% Fair 2-5% Good	Storage to excavation ratio; catchment needs.
Sewerage lagoons	Fair to poor	Small areas, proximity to major watercourse.
Topsoil - Quality	Fair	Hard setting structureless
- Removal	Poor	Thin layer.
- Resowing	Poor	Clayey, poorly structured sub-soil
Sand - Quality	Poor	Overburden thickness, sand deposits are rare.
- Operation
Gravel - Quality	Poor	Overburden thickness, gravel deposits are rare.
- Operation
Grazing	Good	Soil drainage; hard setting topsoil; low fertility.
Cultivation	Good to fair	Soil drainage; hardsetting topsoil; poor structure; impermeable clay; small areas
Clearing	Good	Dispersible clay; erosion prior to pasture establishment.

EFFECT OF SUBDIVISION OF THE LAND ON TOWN WATER SUPPLY
URBAN:	Urban development leads to a high pollution load trammel-point sources which may be unacceptable in a domestic water supply catchment. However, there are no special features of this land component, other than its proximity to a major watercourse, which would cause abnormal difficulties.
FARMLET AND BUSH BLOCK:	This component has poorly drained soils and is close to major watercourses. Any absorption fields which fail will be a high risk to water quality in these watercourses.

Qap - Alluvial Plains

This unit represents 5.1% of the total survey area or 10.5 km². It consists mainly of a large alluvial flat north of Ballarat; parts of it used for industrial and small lot residential uses. However it is mostly poorly drained and subject to waterlogging which limits its usefulness for intensive development.

COMPONENT	1	2
Proportion %	20	80
CLIMATE (Average) Rainfall mm	660 - 711
*Temperature °C	Average annual 12⁰C
*Seasonal growth limitations	Temperature less than 10°C May - September
GEOLOGY Age, growth	Quaternary alluvium, colluvium
TOPOGRAPHY Landscape	Alluvial plain north of the city of Ballarat
Elevation (range) m	450
Local relief (av.) m	1-2
Drainage pattern	-
Drainage density km/km²	-
Land form	Plain
Position on land form	-
Slope (av.) ,%, slope shape	1 3; Convex
NATIVE VEGETATION Structure	Open forest
Dominant species	E. ovata, A. melonoxylon	E. obliqua
SOIL Parent material	Unconsolidated alluvial & colluvial deposits
Description	Dark grey yellow mottled sodic duplex soils	Variable soils, yellow mottled red gradational soils
Surface texture	Clay loam	Fine sandy loam
Permeability	Low	Low
Depth (av.) in	2	2
LAND USE	Grazing, industrial
SOIL DETERIORATION Critical land features	Hard setting surfaces, dispersibility	Poorer drained soil
Processes	Overland flow	Waterlogging
Forms	Gully erosion	Compaction

* Ballan figures

LAND UNIT: Alluvial plain

COMPONENT: 1 – Higher terrace – dark grey/yellow mottled sodic duplex soil

MAP SYMBOL: Qap 1

CAPABILITY OF THE LAND TO SUPPORT VARIOUS ACTIVITIES			CAPABILITY OF THE LAND TO SUPPORT SUBDIVISION
ACTIVITY	RATING	MAJOR LIMITING FEATURES OF THE LAND	SUBDIVISION TYPE	RATING	MAJOR LIMITING ACTIVITIES
Building houses	Fair	Soil drainage; seasonal watertables; (shrink- swell).	Urban (sewered)	Fair	Building houses; secondary roads; shallow excavations.
Absorption fields	Poor	Soil drainage; seasonal watertables; percolation rate.	Small Farmlets 4 ha	Poor	Absorption fields - effluent; (otherwise-fair: building houses; access tracks; gravel roads).
Secondary roads	Fair	Soil drainage.	Large Farmlets 16 ha	Poor	Absorption fields - effluent; otherwise-fairs building houses; access tracks).
Gravel roads	Fair	Seasonally poorly drained.	Bush Blocks 4 ha,	Poor	Absorption fields - effluent; (otherwise-fairs building houses; access tracks; gravel roads).
Access tracks	Poor to fair	Seasonally poorly drained; boggy areas.
Shallow excavations	Fair	Seasonally poorly drained
Small farm dams	Good
Sewerage lagoons	Good
Topsoil - Quality	Fair	Hard setting; structureless.
- Removal	Poor	Thin layer.
- Resowing	Fair	Infertile clayey subsoil; poor drainage.
Sand - Quality	Poor	Sand deposits rare
- Operation
Gravel - Quality	Poor	Overburden thickness; gravel deposits rare.
- Operation
Grazing	Good to fair	Soil drainage; boggy.
Cultivation	Fair to poor	Soil drainage; seasonal watertables; hard setting topsoil; impermeable clay
Clearing	Good

EFFECT OF SUBDIVISION OF THE LAND ON TOWN WATER SUPPLY
URBAN:	Urban development leads to a high pollution load from non-point sources which may be unacceptable in a domestic water supply catchment. However, there are no special features of this land component, other than the poor drainage and its proximity to watercourses, that are likely to lead to abnormal difficulties.
FARMLET:	Failure of absorption trenches will be a severe risk to water supply if the land is subdivided more closely. Absorption fields will not work efficiently during the wetter months due to poor soil drainage. If effluent disposal does not rely on soil absorption and is not likely to be a risk, then there are no special features of this component which will cause abnormal problems of water quality, other than the pollution normally anticipated with^.increased roading and building sites.
BUSH BLOCK:	(uncleared areas are rare) otherwise - as for farmlets.

LAND UNIT: Alluvial plain

COMPONENT: 2 – Lower terrace – variable soils

MAP SYMBOL: Qap 2

CAPABILITY OF THE LAND TO SUPPORT VARIOUS ACTIVITIES			CAPABILITY OF THE LAND TO SUPPORT SUBDIVISION
ACTIVITY	RATING	MAJOR LIMITING FEATURES OF THE LAND	SUBDIVISION TYPE	RATING	MAJOR LIMITING ACTIVITIES
Building houses	Poor	Seasonally poorly drained - watertables; (shrink-swell).	Urban (sewered)	Poor	Building houses; secondary roads; shallow excavations.
Absorption fields	Very poor	Poorly drained; slow percolation rate	Small Farmlets 4 ha	Very poor	Absorption fields - effluent; (otherwise - poor: building houses; gravel roads; access tracks; small farm dams).
Secondary roads	Poor	Seasonally poorly drained - watertables	Large Farmlets	Very poor	Absorption fields - effluent (otherwise - poor: building houses; access tracks).
Gravel roads	Poor	Seasonally poorly drained - watertables	Bush Blocks 4 ha.	Very poor	Absorption fields - effluent (otherwise – poor: building houses; gravel roads; access tracks).
Access tracks	Poor	Seasonally poorly drained - watertables
Shallow excavations	Fair to poor	Seasonally poorly drained - watertables; plastic hard-setting clay
Small farm dams	0-2% Poor 2-5% Good	Catchment; storage/excavation ratio
Sewerage lagoons	Good	Proximity to watercourses
Topsoil - Quality	Fair	Hard setting structureless
- Removal	Poor	Thin layer
- Resowing	Fair	Infertile clayey subsoil; poor drainage
Sand - Quality	Poor	Sand deposits rare
- Operation
Gravel - Quality	Poor	Gravel deposits rare
- Operation
Grazing	Fair	Soil drainage
Cultivation	Fair to poor	Soil drainage; hard setting structureless topsoil; impermeable clay
Clearing	Good	Proximity to creeks.

EFFECT OF SUBDIVISION OF THE LAND ON TOWN WATER SUPPLY
URBAN:	Urban development leads to a high pollution load from non-point sources, which may be unacceptable in a domestic water supply catchment. However, there are no special features of this land component, other than the poor drainage and its proximity to watercourses, that are likely to lead to abnormal difficulties.
FARMLET:	Failure of absorption trenches will be a severe risk to water supply if the land is subdivided more closely. Absorption fields will not work efficiently during the wetter months due to poor soil drainage. If effluent disposal does not _relyon soil absorption and is not likely to be a risk, then there are no special features of this component which will cause abnormal problems of water quality, other than the pollution normally anticipated with increased roading and building sites.
BUSH BLOCK:	(uncleared areas are rare) otherwise - as for farmlets.

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