Soil/Landform Unit - Wal Wal prior stream plains

WLRA Landform Wal Wal prior stream plains

Level clay plains near Lubeck

Area: 21 906 ha

0.93% of CMA region

This prior stream plains unit is found north of Glenorchy on the eastern border of the Wimmera CMA. This plains complex with leveed channels is part of the Northern Riverine Plains older

alluvial

plains (4.2) geomorphological unit. The

Quaternary

alluvial sediments lie adjacent to the major stream units of the Wimmera River, Yariambiack Creek and Dunmunkle Creek, clay plains and higher residual sand plains. There are four components, the level plains are dominant and flats sub-dominant. The other components are gentle slopes and drainage lines. Soil types include cracking clay soils with limited

self-mulching

surfaces (

Vertosols

) and some red sodic texture contrast soils (

Sodosols

) on slight rises (levees). Periodic inundation and waterlogging occur on extensive flat areas and depressions. This unit is used for dryland cropping and grazing (sheep, beef cattle). Remnant vegetation is largely either Plains Grassland or Plains Woodland.

Component	1	2	3	4
Proportion of soil-landform unit	55%	15%	25%	5%
CLIMATE Rainfall (mm)	Annual: 470
CLIMATE Rainfall (mm)	Annual: 470
Temperature (^oC)	Minimum 8, Maximum 21
Precipitation less than potential evapotranspiration	September–April
GEOLOGY Age and lithology	Quaternary fluvial silt, sand and minor gravel (Shepparton Formation); Neogene marine sand and silt (Parilla Sand); Quaternary fluvial gravel, sand and silt
GEOLOGY Age and lithology
Geomorphology	4.2.1 Plains with leveed channels of the Older Alluvial Plains
LANDUSE	Uncleared areas: water supply; nature conservation Cleared areas: dryland cropping; sheep and beef cattle grazing
LANDUSE
TOPOGRAPHY Landscape	Prior stream floodplain
TOPOGRAPHY Landscape	Prior stream floodplain
Elevation range (m)	131–181
Local relief (m)	1–2
Drainage pattern	Dendritic
Drainage density (km/km²)	0.6
Landform	Plains		Prior streams
Landform element	Level plain	Gentle slope	Alluvial flat	Drainage line
Slope and range (%)	0 (0-1)	1 (0-3)	0 (0-1)	0 (0-1)
Slope shape	Straight	Linear	Straight	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Woodland (77.3%), Plains Grassland (19.0%)
NATIVE VEGETATION Ecological Vegetation Class	Plains Woodland (77.3%), Plains Grassland (19.0%)
SOIL Parent material	Fluvial gravel, sand and silt	Marine sand and silt	Fluvial gravel, sand and silt	Fluvial gravel, sand and silt
SOIL Parent material	Fluvial gravel, sand and silt	Marine sand and silt	Fluvial gravel, sand and silt	Fluvial gravel, sand and silt
Description (Corangamite Soil Group)	Cracking clay soils (23)	Cracking clay soils (23) and sodic red texture contrast soils (25)	Cracking clay soils (23)	Cracking clay soils (23)
Soil type sites	WIA11, WIA12, WIA17, HOR04	WIA11, WIA12, WIA16	WIA11, WIA12, WIA17, HOR04	WIA11, WIA12, WIA17, HOR04
Surface texture	Light clay	Sandy loam to light clay	Light clay	Light clay
Permeability	Slow	Slow to moderate	Very slow	Very slow
Depth (m)	> 2	> 2	> 2	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Flat areas susceptible to inundation and waterlogging, but can be variable locally due to micro relief (gilgai). Surface soils generally not friable but are susceptible to compaction (less structure).	Soils may be slightly susceptible to inundation and waterlogging where surface soil is shallow. Hardsetting soil slightly susceptible to sheet and rill erosion. Soils are prone to compaction at critical moisture contents. Slight susceptibility to acidification of surface soil.	Flats are susceptible to inundation and waterlogging along with flooding. Surface soils generally not friable and are susceptible to compaction (less structure).	Drainage depressions are subject to seasonal inundation, waterlogging and flooding. Surface soils generally not friable and are susceptible to compaction (less structure).

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