Barwon River Land System

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The flood-plains of the Barwon River and its tributaries extend from the foothills of the northern side of the Range to the basalt plains near Winchelsea and encompass a comparatively wide climatic variation. The vegetation reflects these changes, with tall open forests of Eucalyptus viminalis and E. ovata occurring in the south and woodlands of E. camaldulensis dominating in the north. The soils also show a gradual transition from acid, freely drained profiles to heavier neutral soils as the influence of basalt-derived alluvium increases towards the north.

Flooding and siltation are common on these plains. Waterlogging of soils is a problem, particularly on low-lying areas such as cut-off meanders and infilled swamps. Gully erosion and stream-bank erosion are also common.

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

Gully erosion and stream-bank erosion are particularly common
on these alluvial plains, where streams emerge from the foothills
of the Otway Range.

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

Area: 762 km²	Component and its proportion of land system
Area: 762 km²	1 5%	2 85%	3 10%
CLIMATE Rainfall, mm	Annual: 600 – 1,000, lowest January (30), highest August (80)
Temperature, 0^oC	Annual: 13, lowest July (8), highest February (9)
	Temperature: less than 10^oC (av.) June – August (Also September in higher-rainfall areas)
	Precipitation: less than potential evapotranspiration October – April in lower-rainfall areas November – March in higher-rainfall areas
GEOLOGY Age, lithology	Recent alluvium – sand, silt, clay and gravel
TOPOGRAPHY Landscape	Alluvial flood plain of the Barwon River and its tributaries with numerous cut-off meanders
Elevation, m	90 - 150
Local relief, m	3
Drainage pattern	Deranged with major meandering channel
Drainage density, km/km²	1.6
Land form	Plain
Land form element	Rise	Plain	Streambank, infilled meanders
Slope (and range), %	4 (1-6)	1 (0-2)	2 (1-8)
Slope shape	Convex	Straight	Convex
NATIVE VEGETATION Structure	Woodland
Dominant species	E. ovata, E. viminalis, Acacia melanoxylon, in north E. camaldulensis
SOIL Parent material	Sandy alluvium	Clayey alluvium	Sandy alluvium
Description	Brown sandy loam soils, uniform texture	Grey gradational soils	Brown sandy loam soils, uniform texture
Surface texture	Fine sandy loam	Fine sandy clay loam	Fine sandy loam
Permeability	Very high	Moderate	Very high
Depth, m	>2	>2	>2
LAND USE	Dairy farming; cropping; sheep and beef cattle grazing.
SOIL DETERIORATION HAZARD Critical land features, processes, forms	High permeability and leaching lead to nutrient decline.	High seasonal water table leads to waterlogging, soil compaction and salting. Dispersible clay subsoils are prone to gully and tunnel erosion. High discharge rates along some watercourses lead to flooding and siltation.	High discharge rates and weakly structured soils lead to streambank erosion and siltation. High seasonal water tables lead to waterlogging.

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