Alice Springs town basin, review 2003
Read, R. E.
E-Publications; E-Books; PublicationNT; Report ; no. 42/2003
Made available via the Publications (Legal Deposit) Act 2004 (NT).
Department of Infrastructure, Planning and Environment
Report ; no. 42/2003
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2 Physiography Alice Springs was developed on the flood plain of the Todd River. To the south the east west trending MacDonnell Ranges form a barrier, cut through at Heavitree Gap. Surrounding the valley of the Todd to the north, east and west are low hills, broken by valleys along minor drainages. 3 Geology This was well described by Quinlan and Woolley (1969). 3.1 Structure The basin is an in-filled valley of the Todd. There is a constriction between Billygoat Hill and Meyers Hill. South of this the deepest part of the basin is west of the present day course of the Todd. The eastern side of the basin is fairly steeply defined. Much of the western side is gently shelving. Quinlan and Woolley (1969) produced a map of the elevation of basin bedrock. A modified version of this is shown in Figure 2. With the exception of the railway yards area there is little additional information about the fringes of the basin since 1969. Most of the basin is filled with silt of low permeability. The main aquifers are strips of sand marking former courses of the Todd and possibly the Charles River. Quinlan and Woolley (1969) mapped five sand aquifers, named the 1810, 1820, 1830, 1840 and 1850 aquifers for their elevation in feet. 3.2 Strata BMR (1983) shows the geology of the area. Rocks of the Arunta Complex, that is Teppa Hill Metamorphics, Emily Gap Schist and Alice Springs Granite, are overlain by Quaternary alluvium of the Todd River. In addition there are extensive areas of weathered bedrock on the fringes of the Town Basin. Some bores have obtained small supplies from these, but they have little importance for groundwater supply. They are a hazard for land development as they have shallow saline water tables and large accumulations of salt in the unsaturated zone. 4 Surface water The Todd River carries the largest volume of water into and out of the Town area. Before European settlement drainage into the Todd from the east was obstructed by over-bank deposits, resulting in the Coolibah Swamp. With urbanisation run-off has increased and drains have been constructed to carry water into the Todd more efficiently. 3