Soil/Landform Unit - West Wimmera swamp, lake and lunette complex

WLRA Landform West Wimmera lake and lunette complex

String of lakes orientated north-south between former stranded beach ridges south of Wombelano

Area: 12 889 ha

0.55% of CMA region

This unit of swamps and lunettes occurs south of the Little Desert and west of the Douglas Depression. As part of the North West Dunefields and Plains, these swamps and wetlands of Quaternary lacustrine and

aeolian

sediments occur between the NNW/SSE orientated ridges as gently undulating plains and depressions. Lakes and swamps,

lunettes

, backplains and low rises are all prominent land components. Drainage is very slow and is restricted to draining to the local depressions. Grey cracking clay soils (

Vertosols

) and sodic, yellow and grey texture contrast soils (Sodosols) occur in the drainage depressions with sodic red texture contrast soils (

Sodosols

) occurring on the low rises. Periodic to seasonal inundation and waterlogging are the main land issues of the flat terrain and in depressions. Land use is mixed between grazing (sheep and cattle), dryland cropping, water supply and recreation. Vegetation found includes communities such as Lignum Swampy Woodland, Shallow Sands Woodland, Plains Woodland, Freshwater Lake Mosaic, Dune Soak Woodland, Brackish Wetland, Lignum-Cane Grass Swamp and Red Gum Wetland.

Swamp located within east-west sand plains south of Goroke
	Wetland bordering east-west sand plain

Component	1	2	3	4
Proportion of soil-landform unit	5%	10%	15%	70%
CLIMATE Rainfall (mm)	Annual: 550
CLIMATE Rainfall (mm)	Annual: 550
Temperature (^oC)	Minimum 8, Maximum 21
Precipitation less than potential evapotranspiration	September–April
GEOLOGY Age and lithology	Quaternary paludal silt & clay; Neogene marine sand & silt (Parilla Sand); Quaternary Aeolian dune sand (Lowan Sand)
GEOLOGY Age and lithology
Geomorphology	5.5.2 Low ridges and oriented swales of the North West Dunefields and Plain
LANDUSE	Uncleared areas: Water supply; nature conservation Cleared areas: Sheep and beef cattle grazing; dryland cropping; water supply
LANDUSE
TOPOGRAPHY Landscape	Swamp, lake and lunette complex
TOPOGRAPHY Landscape	Swamp, lake and lunette complex
Elevation range (m)	94–184
Local relief (m)	5
Drainage pattern	Dendritic
Drainage density (km/km²)	1.6
Landform	Rises	Plains	Lakes, swamps and lunettes
Landform element	Low rises	Backplain	Lunette	Lake and swamp beds
Slope and range (%)	3 (1-8)	0 (0-1)	3 (1-10)	0 (0-1)
Slope shape	Convex	Linear	Convex	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Woodland (35.1%), Red Gum Wetland (12.7%), Shallow Sands Woodland (11.3%), Plains Savannah 5.8%), Other (28.8%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	Marine sand and silt	Paludal silt and clay	Aeolian sand, silt and clay	Paludal sailt and clay
SOIL Parent material	Marine sand and silt	Paludal silt and clay	Aeolian sand, silt and clay	Paludal sailt and clay
Description (Corangamite Soil Group)	Sodic red texture contrast soils (39)	Grey and brown cracking clay soils (37)	Sodic brown, yellow and grey texture contrast soils (38) and sodic red texture contrast soils (39)	Seasonally wet soils: sodic yellow and grey texture contrast soils (33)
Soil type sites	NA174	LS3, LSWW9, LSWW5	LSWW11, LSWW17, NA174	NA171, NA141, NA178
Surface texture	Sandy loam	Medium clay	Loamy sand	Sand
Permeability	Moderate	Slow	Moderate	Very slow
Depth (m)	> 1.2	> 2	> 2	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Hardsetting upper soil susceptible to sheet and rill erosion along with wind erosion when exposed. Dispersive and deep subsoils susceptible to gully erosion on steeper slopes.	Susceptible to inundation and waterlogging on backplain. Surface soils friable and only slightly susceptible to wind erosion. Soils susceptible to compaction at critical moisture contents.	Susceptible to wind and sheet erosion where sandy surfaces with little organic matter are exposed. Susceptible to compaction where hardsetting and restricted drainage. Upper soil is susceptible to acidification.	Susceptible to seasonal inundation, waterlogging and ultimately soil salinity. Upper soils susceptible to sheet erosion and wind erosion when exposed.

Page top