[Dr Vincent Kotwicki's Lake Eyre Site]

The Neales

The Neales originates at Mount Brougham, 430 km from the western shore of the Lake. Joined by Arckaringa Creek and Lora Creek, creating in their lower reach the Peake Creek, it runs across the broad floodplain to the Dividing Bluff and then branches, entering the Lake by three channels.

The Neales has a catchment area of 35 000 km2 . Major floods have been recorded in the area in 1885, 1908, 1950, 1953, 1967 1974, 1976 and 1984. However, the majority of floods must have gone unnoticed due to the lack of permanent observation. Nothing quantitative is known about these floods, but on occasions they were heavy, as described by Hunt (1918):

10 March 1908, - Oodnadatta. - There was no telegraphic communication between Oodnadatta and the south, from noon on 6 March until the evening of 9 March, owing to the water rising high above the wires at Peake Creek; and the train from Warrina was detained for five days. The flood water at the Peake Creek (about 10 miles from Warrina) rose 12 feet above the bridge, and the rapidity with which it subsided was remarkable. Between Dalhousie and Macumba stations a plain about 40 miles long was under water.

The Macumba

The Macumba, which joins the Kallakoopah in discharging its waters into the Warburton Groove, consists of four rivers. Its longest potential tributary, the Finke, which rises in the MacDonnell Ranges 825 km NW from Lake Eyre, is ephemeral and there is no hard evidence that its waters ever reached the lake, being absorbed by the sands of the Simpson Desert (Williams, 1970). However, there is some information that the Finke did reach Lake Eyre in 1909, 1938 and 1945 (Bonython, 1963). Irrespective of this the Finke catchment area of 63 000 km2 contributes little water to the Lake.
River stages are measured by the Northern Territory Department of Transport and Works at:

GS 005136 — Horseshoe Bend
GS 005137 — Idracowra
GS 005138 — Finke Siding.

However, the stations are not instrumented, are not connected to Australian Height Datum, and the stages have not been converted to flow figures.

In 1967, one of the most devastating floods in central Australia caused the Finke to rise to 6.98 m in Hermannsburg, 3.36 m at ldracowra and 2.84 m at Finke. Highest velocities in the western Lake Eyre Basin were estimated at 3.5-3.7 m/s which corresponds to a discharge of 1200 m3/s at Idracowra (Williams, 1970, 1971). However, the Finke did not reach the Lake. Being 11 km wide with an average depth of 0.8 m southwest of Andado homestead, and farther downstream 3 km wide with depths of up to 1.4 m at McDills Well, the distributary stream ran north-east into the sand dunes filling interdune corridors to a depth of 6 m. Water remained in some of the corridors for nineteen months (Williams, 1970).

The duration of recession flows of the Finke is probably very short. Some indication is given by the adjacent Todd River, where a pre-1973 maximum of only five days has been noted. It has risen to sixty-seven days after rain in May 1974 and to in excess of sixty days after rain in March 1976 (Verhoeven, 1977).

The Alberga, the Hamilton and the Stevenson rise on the eastern foothills of the Musgrave Ranges, some 500 km WNW from the Lake and join their courses more or less in the middle of this distance. If the floodwaters enter the Lake via the Macumba, they originate almost certainly from the catchments of these rivers which have a total area of 39 000 km2. The Engineering and Water Supply Department has good photographic aerial coverage of the extent of the 1984 flood.

The length of the Finke to the Macumba is 725 km with a mean slope of 6.7 x 10-4. The Hamilton to the Stevenson is 260 km with a mean slope of 1.7 x 10-3. The Stevenson and the Alberga are 230 and 380 km to their confluence respectively, with similar slopes of 1.3 x 10-3.

The Frome

The Frome rises at Mount Rose in the northern Flinders Ranges. Joined by Taylor, Mundy and Leigh creeks, it passes Marree and Muloorina and enters the southeastern part of Lake Eyre North, known as Lake Clayton.

The length of the Frome is 245 km and its catchment area is 18 200 km2 . The highest floods in living memory occurred in 1938, 1974 and 1984. The river ran 1.5 km wide in 1885.
 

Other tributaries

Many smaller ephemeral rivers enter the Lake from the western side. A number of them originate on the range of hills peaking with Mt Margaret at 412 m and Mt Anna at 265 m, 80 km west of the Lake. The longest of them, Douglas Creek, which empties into Halligan Bay, has a length of 93 km with a mean slope of 2.8 x 10-3. The 65 km long Sunny Creek which empties into the southern branch of the Neales has a mean slope of 3.8 x 10-3.  Named watercourses include the 34 km long Cooinchina Creek discharging into Belt Bay, and Koorakarina and Anchor creeks which flow into Lewis Bay and have a length of 49 and 25 km respectively. Nothing quantitative is known of flows in these creeks although on occasions of heavy rains, runoff to the Lake can be significant due to their proximity and therefore lower transmission losses.

In arid central Australia, 15 to 20 mm of rain of moderate intensity can cause flow in such minor streams which lasts for only an hour or two. Such a flow may occur as often as five times each year. However, about 50 mm is needed for full channel flow and these rainfalls can be expected less frequently than once per year.
 

The Neales in flood at the old railway crossing.

The Finke (left bottom) flows towards Lake Eyre (centre).

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