Connewarre Land System

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Many of the outlets of creeks and rivers to the east of the Otway Range possess tidal swamps with braided channels and brackish lagoons. Thompson Creek and Painkalac Creek have such river mouths, although the most extensive swamp lies just outside the present study area, surrounding the mouth of the Barwon River.

Only minor differences in height above mean tide level determine the differences between the land components. The marine terraces escape inundation in all but extremely rare combinations of floods and high tide, while most other tracts of land are flooded either regularly or irregularly.

Halophytic shrubs and herbs colonize the grey and structureless silty clays found on these swamps. The structure and species of each community are strongly influenced by the height above mean tide level and the degree of salinity of the tidal water.

Some parts of these areas have been drained or filled to provide for agriculture or recreational facilities. However, most parts remain in their natural state.

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

These swamps lie just inland from the coastal dunes
and provide valuable habitats for wildlife.

Area: 41 km²	Component and its proportion of land system
Area: 41 km²	1 30%	2 30%	3 10%	4 15%	5 15%
CLIMATE Rainfall, mm	Annual: 625, lowest January (30), highest August (60)
Temperature, 0^oC	Annual: 14, lowest July (10), highest February (18)
	Temperature: less than 10^oC (av.) July
	Precipitation: less than potential evapotranspiration October – early April
GEOLOGY Age, lithology	Recent estuarine sand, silt, clay and plant remains				Veneer of aeolian sand
TOPOGRAPHY Landscape	Flat estuarine lowlands with braided channels
Elevation, m	0-4
Local relief, m	1
Drainage pattern	Deranged
Drainage density, km/km²	-
Land form	Marine terrace			Swamp
Land form element	-	Upper surface occasionally inundated	Lower surface regularly inundated	Free water surface	Area adjacent to sand dune
Slope (and range), %	1 (0-2)	0 (0-1)	0	0	1 (10-2)
Slope shape	Convex	Linear	Linear	-	Irregular
NATIVE VEGETATION Structure	(Not known)	Low shrubland	Closed grassland	-	Sedgeland
Dominant species	-	Arthrocnemum arbusculum, Gahnia filum	Frankenia pauciflora, Samolus repens, Arthrocnemum arbusculum	-	Scirpus nodosus
SOIL Parent material	Estuarine clay, silt and sand	Estuarine clay, silt and plant remains	Estuarine clay, silt and plant remains	Estuarine clay, silt and plant remains	Aeolian sand, shell grit over estuarine clay, silt and plant remains
Description	Yellow sodic duplex soils	Saline soils	Saline soils	Saline soils	Grey sand soils, weakly structured clay underlay
Surface texture	Sandy loam	Silty clay loam	Silty clay	Silty clay	Sandy loam
Permeability	Moderate	Very low	Very low	Very low	Low
Depth, m	>2	>2	>2	>2	>2
LAND USE	Cleared areas: Some of the higher areas cleared for grazing, cropping and recreational facilities. Uncleared areas: Nature conservation; refuse disposal.
SOIL DETERIORATION HAZARD Critical land features, processes, forms	Sodic subsoils with high saline groundwater tables are prone to soil salting, surface compaction and sheet erosion.	Occasional influx of estuarine saline water on clays of low mechanical strength leads to soil salting and compaction.	Regular influx of estuarine saline water on clays of low mechanical strength leads to soil salting and compaction.	Minor hazards	Sodic subsoils with low permeability and high saline groundwater tables are prone to surface compaction and soil salting.

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