South East (Province 1)
This province has a cool, moist climate with long mild summers. Mean annual rainfall is highest in the southernmost portion of the province, about 850 mm per annum, and decreases northward to about 500 mm. Rainfall is the coastal zone shows a more definite winter maximum than further inland. Temperatures are generally cool throughout the province, the coastal zone having more restricted seasonal and diurnal ranges than inland. Evaporation is high during the summer and, except for the winter months, mean monthly potential evaporation exceeds the median monthly rainfall.
The South East is characterized by an unusual suite of coastal landforms which owe their development to Pleistocene sea level fluctuations, beach progradations and a complex history of earth movements.
Along most of the coastline there is a narrow belt of active dunes rising steeply from the sandy beach, and backed by extensive lagoons with occasional narrow outlets to the sea. In the south, sea-cliffs have formed locally in outcrops of calcarenite (consolidated calcareous sand).
The dominant relief features of the province are a series of calcarenite dune ridges or 'ranges' aligned roughly parallel to the present coastline. They stand out as individual ranges in the south-east of the province but coalesce in the north-west.
The dune ridges rise from a surface which slopes very gently to the south-west and which is divided by the ranges into numerous elongated interdunal plains. There plains often lack natural surface drainage, so that extensive swamp and lake systems have formed within them.
Unconsolidated sand dunes and sand sheets overlie both the consolidated dune ridges and the intervening plains.
In the far south-east of the province the Tertiary limestone bed-rock, which underlies the Quaternary sequence of dunes, rises to the surface and forms an irregular undulating plain. In addition, there are several Tertiary volcanic cones which rise prominently above the plain.
The landscape is dominated by cultural influences. Large areas of native woodlands, forests and heaths have been replaced by sown pastures and pine plantations. In addition, many swamps and seasonally flooded plains are now drained by a system of channels. Remnants of the original swamp vegetation are now found mainly in the north-west of the province.
Land use is dominated by livestock grazing. Improved pastures are found on the moderately deep imperfectly drained soils of the interdunal plains whist the ranges with shallow well-drained sandy soils provide alternative rough grazing during wet periods when parts of the plains are flooded. Dairy cattle comprise about 20% of animal units (1 animal unit = 1 cow or 8 sheep) in the higher rainfall areas of the south, and merino sheep are important (about 60% of animal units) in the far north where there is little pasture growth during summer. Elsewhere beef cattle dominate, providing 60-70% of animal units, with coarse wool sheep grazing on the drier ground.
There is limited horticultural activity in the vicinity of Mt Gambier on the moderately deep well-drained loams of moderate fertility derived from volcanic ash and near Millicent on drained clay soils. Two small but increasing areas of vineyards occur in the province, one long established at Coonawarra and the other, smaller and more recent, at Padthaway. These are on friable, highly permeable clays of moderate to high fertility on slightly elevated areas within the plains so they never flood, but they do have a water table within root range.
Plantation forestry occurs in localities which have a combination of higher rainfall and soil conditions suitable for Monterey pine (Pinus radiata). Pine plantations are mainly confined to deep, well-drained sands with a pan at depth. These sandy soils are generally of low fertility but the presence of the pan increases the available water in the form of a perched water table. The plantations in the South East Province represent about 84% of the State's total. Small nature conservation reserves occur throughout the province representing a wide range of local environments, typical of must of the province.
The extensive beaches of the coastline and associated lakes and lagoons offer considerable opportunities for water-based recreation and conservation.
Five environmental regions are recognized in this province: