Deepdene Land System

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An extensive lateritic plateau to the north of the Otway Range has been dissected by the Barwon River and its tributaries. There are several plateau remnants separated by alluvial plains of the Barwon River land system. In general, flat or gently undulating plains occupy the highest parts of the landscape, and these are surrounded by gentle slopes leading to slightly lower surfaces or by steep scarps falling away to the alluvial plains.

The areas to the west of the Barwon River is more dissected, with generally steeper slopes.

The soils on the highest levels have been strongly lateritized, with ironstone throughout the profile and concentrated in discontinuous layers at about 1.2 m depth. Similar soils without ironstone are found on lower levels, while the gentle slopes between these levels possess heavier-textured soils with coarse blocky structures in the subsoils.

Clearing has been widespread and the land is used for sheep and beef cattle grazing as well as some dairying. Soil salting has occurred in some areas, and major problems have arisen due to gully and tunnel erosion. The more dissected areas to the west of the Barwon are the most susceptible, and damage has been widespread.

A Study of land in the catchments of the Otway Range and adjacent plains - deepdene

Dispersible subsoils on the steeper slopes of this landscape are highly
susceptible to gully erosion and landslips.

Area: 179 km²	Component and its proportion of land system
Area: 179 km²	1 40%	2 15%	3 20%	4 10%	5 7%	6 8%
CLIMATE Rainfall, mm	Annual: 650 – 700, lowest January (30), highest August (85)
Temperature, 0^oC	Annual: 13, lowest July (8), highest February (9)
	Temperature: less than 10^oC (av.) June – August
	Precipitation: less than potential evapotranspiration early October – late April
GEOLOGY Age, lithology	Pliocene clay, silt and sand
TOPOGRAPHY Landscape	Undulating plain inland of the Otway Range
Elevation, m	120 - 190
Local relief, m	40
Drainage pattern	Dendritic
Drainage density, km/km²	1.0
Land form	Rise			High level terrace	Drainage line	Scarp
Land form element	Broad crest	Gentle upper slope	Gentle broad slope	-	-	-
Slope (and range), %	1 (0-2)	5 (2-1)	3 (0-7)	1 (0-2)	0 (0-1)	35 (10-50)
Slope shape	Linear	Linear	Convex	Linear	Concave	Linear, Convex
NATIVE VEGETATION Structure	Open forest	Open forest	Open forest	Woodland	Closed scrub	Open forest
Dominant species	E. viminalis, E. obliqua, E. radiata	E. viminalis, E. ovata	E. obliqua, E. viminalis, E. ovata, E. radiata	E. viminalis, E obliqua, E. ovata	Leptospermum juniperinum Melaleuca squarrosa	E. obliqua, E. viminalis
SOIL Parent material	Lateritized sediments	Clay	Clay, silt and sand	Alluvial clay, silt and sand	Alluvial clay, silt and sand	Clay, silt and sand
Description	Mottled yellow and red duplex soils with ironstone	Yellow-brown sodic duplex soils, coarse structure	Mottled yellow and red duplex soils	Yellow-brown calcareous sodic soils, coarse structure	Grey gradational soils	Yellow sodic duplex soils
Surface texture	Sandy loam	Fine sandy loam	Sandy loam	Fine sandy loam	Fine sandy clay loam	Sandy loam
Permeability	Moderate	Low	Moderate	Low	Very low	Moderate
Depth, m	1.2	>2	>2	>2	>2	>2
LAND USE	Cleared areas: Sheep and beef cattle grazing; cash and row cropping; dairy farming.
SOIL DETERIORATION HAZARD Critical land features, processes, forms	Low inherent fertility, phosphate fixation, and permeable surface soils lead to nutrient decline.	Dispersible clay subsoils of low permeability are prone to gully and tunnel erosion. Sodic subsoils of low permeability receiving saline seepage are prone to soil salting.	Low inherent fertility, phosphate fixation and permeable surface soils lead to nutrient decline.	Dispersible clay subsoils of low permeability are prone to gully and tunnel erosion and soil salting.	High seasonal water table leads to waterlogging, soil compaction and soil salting. Dispersible clay subsoils are prone to gully and tunnel erosion.	Dispersible soils on steep slopes subject to periodic saturation are prone to landslips and sheet erosion.