Brisbane flood prediction map, 1933

15 April 2015
15 April 2015
Department of Lands

Collection of the Museum of Lands, Surveying and Mapping

Brisbane flood prediction map, 1933. Drawn by the Survey Office, this map was prepared by the Bureau of Industry in 1933. At the time it provided information on which areas of Brisbane were likely to be inundated under various flood scenarios: 10, 15, 20, 25 and 30 feet. These areas were shaded blue, pink, yellow, green and plum respectively. Because ‘improvements’ (dredging and channel widening) had been made in the lower river, flood heights were expected to be at least four feet lower from the Victoria Bridge downstream, however, no appreciable effects were expected upstream. The map contained a list of major floods since 1841 as well as a table estimating the probable duration of floods at different heights. The last major flood was on 7 February 1931 which rose just below 15 feet. Its approximate extent can be inferred from the areas shaded red. According to the map, 15 feet at the Port Office gauge was the ‘critical level’ where ‘no serious damage need be anticipated by a flood which does not exceed that height.’ A flood around 15 feet or below would not be treated as lightly. The cost of this map was three shillings. Collection of the Museum of Lands, Surveying and Mapping

Brisbane flood map, 1974

Australia
15 April 2015
15 April 2015

Location

Australia

Collection of the Museum of Lands, Mapping and Surveying

Brisbane flood map, 1974. Based on field inspection, aerial photographs as well as information made available from the Brisbane City Council, this map was prepared by the Survey Office and published in February 1974.  The extent of the Australia Day floods is shown as a red line, while according to various heights at the Port Office gauge, ‘areas of probable inundation’ were shaded blue, pink, yellow, green and plum. This information was obtained from an earlier flood map produced by the Bureau of Industry in 1933. The location of the massive tanker, the ‘Robert Miller’, is shown downstream of Kangaroo Point where it broke its moorings during the flood. According to the Survey Office, while the map was compiled from ‘the best information available’, it contained a clear warning for users: ‘no warranty is given to the correctness of the flood perimeter shown hereon.’ Lack of reliable contour information in 1933 as well as physical changes to the flood plain and channel since would all affect the possible extent of a flood. This was demonstrated in 1974 when Brisbane River invaded further than expected while other areas remained dry. A copy of this map could be purchased for $1. Collection of the Museum of Lands, Mapping and Surveying

Brisbane flood heights, 1841-96

10 June 1896
15 April 2015
15 April 2015

Collection of the Fryer Library, University of Queensland

Brisbane flood heights, 1841-96. In response to the 1893 floods, the head of the Water Supply Department, J.B. Henderson, compiled this diagram in recording the history of floods from 1841. Based on historical accounts, it was probably the first time any comprehensive and comparative analysis had been made. According to reputable accounts, Brisbane’s first recorded flood was in September 1825, but no information could be found regarding its height and it was not included. The first major flood shown on this diagram was 14 January 1841 which, by Henderson’s calculations, was at least two inches higher than the ‘Great Flood’ in early February 1893. Included on the diagram were the computed flood levels for three flood mitigation schemes recommended by the Water Supply Department: ‘A’, ‘B’, ‘C’. Scheme ‘B’, straightening the river by cutting through Kangaroo Point and New Farm, would have the highest flood mitigation impact. According to Henderson, in an 1893 flood event the water level would be reduced to about one foot over the floor of the Queen’s Hotel, the equivalent height above the Norman Wharf. Queensland votes and proceedings, vol.4, 1896

Township and works at Somerset Dam, 1937

1 January 1937
15 April 2015
15 April 2015
Bureau of Industry

Collection of University of Queensland Library

Township and works at Somerset Dam, 1937. For the purposes of building Somerset Dam, a small township was established at the construction site.  As shown by this map, the township boasted a hospital, school, police station and even tennis courts. A ‘swimming pool’ was located downstream in the river. The workshops, storage sheds and crushing plant were located upstream. The stone quarry, used for dam building, was at the top of the hill. By 1937, 126 workers’ cottages were constructed. The inset in the top left corner shows the location of the dam above the junction of the Stanley and Brisbane Rivers. In a letter to the Brisbane Courier in 1935, H.P. Somerset explained that his name’s association with the dam and township was not in relation to his efforts to warn Brisbane back in 1893, rather, it was his suggestion of the site after writing to the Water Board in 1906. Somerset was flatteringly described as an ‘engineer’ for noticing the rock formation as well as its suitability for dam construction. Queensland Parliamentary Papers, Vol.2, 1937

Proposed flood diversion canal cross sections, 1896

10 June 1896
15 April 2015
15 April 2015

Collection of the Fryer Library, University of Queensland

Proposed flood diversion canal cross section, 1896. After the ‘Great Flood’ of February 1893, the Water Supply Department and its director, J.B. Henderson, investigated the possibility of building flood diversion canals to protect the city. This cross section map shows one canal leaving from Oxley and the other leaving from Yeronga, both with a common outlet at Tingalpa Creek at the ocean. This map shows that the maximum depth of cutting for the upper canal would be approximately 252 feet and, for a length of around 8.5 miles, the average depth would be about 120 feet. For the lower canal, the maximum cutting depth would be about 170 feet while for a length of around six miles the average depth would be 100 feet. According to Henderson’s report, both canals would have ‘colossal dimensions’ and rival some of the largest canals in the world. As shown by another map depicting the proposal, either canal would require purchasing land between the Brisbane River and Moreton Bay. The canals would also require the construction of several new rail and road bridges, revetting to protect embankments, and finally an inlet weir. According to Henderson’s calculations, the excavation alone would cost £9,523,194 for the upper canal, and about £7,138,000 for the lower canal. In addition to affecting navigability and tidal behaviour of the Brisbane River, the canals would need frequent dredging. Henderson advised parliament to abandon consideration of this and other similar schemes. Queensland votes and proceedings, vol.4, 1896

Proposed diversion canal scheme, 1896

Australia
10 June 1896
15 April 2015
15 April 2015

Location

Australia
Water Supply Department

Collection of the Fryer Library, University of Queensland

Proposed flood diversion canal scheme, 1896. Under J.B. Henderson’s direction, the Water Supply Department investigated a variety of flood mitigation schemes to protect Brisbane from future floods. A report was presented to Parliament in 1896 and included this map of two flood diversion canals. According to Henderson, at the time there appeared to be a ‘prevailing belief  ̶  that without difficulty a canal could be formed at some point on the river to the sea by means of which floods below the canal entrance at the river end would be wholly averted.’ However, building them would not be simple. Either canal would involve the purchase of much land, the construction of several new bridges, revetting to protect embankments, and finally an inlet weir. According to Henderson’s calculations, the excavation alone would cost £9,523,194 for the upper Oxley canal, shown in orange, and about £7,138,000 for the lower Yeronga canal shown in light blue. In addition to affecting navigability and tidal behaviour of the Brisbane River, the canals would need frequent dredging. Henderson advised parliament to abandon consideration of this and other similar schemes. Queensland votes and proceedings, vol.4, 1896

Caboonbah homestead, 1932

1 January 1932
15 April 2015
15 April 2015

Collection of the Fryer Library

Caboonbah homestead, 1932. Overlooking where the Brisbane and the Stanley Rivers combine, this map depicts the scene at which H.P. Somerset saw floodwaters approaching Brisbane in February 1893. A cloudburst in the upper Stanley catchment caused the Brisbane River to rapidly rise in early February where, to the south, he saw the waters submerge a gum tree at 55 feet, exceeding the level of the last major flood in 1890. The whole house shook as the flood waters crashed into the cliff nearly 200 yards away. To the north, he observed that the flat on the far side of the Brisbane River was already flooded. Saw logs were racing upstream a distance back from the river. These were later deposited on a ridge shown. Closer inspection by Somerset later revealed that they were red cedar logs bearing Mr F. Bowman’s brand. These had been felled near the head of the Reedy Creek. This clearly indicated that it was the Stanley River which had carried them downstream. The dam site suggested by Somerset is shown above the junction of the Stanley River and Reedy Creek. Collection of the Fryer Library

Channel widening and river training scheme, 1896

1 January 1896
15 April 2015
15 April 2015
Water Supply Department

Collection of the Fryer Library, University of Queensland

Channel widening and river training scheme, 1896. Under the direction J.B Henderson, this channel widening and river training scheme was proposed by the Water Supply Department in 1896. To prevent a repeat of the disastrous 1893 floods, areas shaded orange would be removed to widen the channel. A series of flood walls would also be built to protect the inner city and South Brisbane. Where the walls would abut existing permanent structures, watertight joints would be formed keeping flood waters in the channel. These walls would have gates at key locations only closed in the event of a flood higher than in 1890. In the city, flood gates were proposed on the corner of Creek and Charlotte streets and on the corner of Alice and Edward Streets. In South Brisbane, flood gates were proposed at the end of Russell, Glenelg, Ernest and Tribune streets. This map includes the 1893 flood line and shows only part of the Victoria Bridge which was destroyed during the flood. Queensland votes and proceedings, vol.4, 1896

Brisbane flood, left bank, 1893

1 January 1893
15 April 2015
15 April 2015
Survey Office

Collection of the Museum of Lands, Mapping and Surveying 

10 chains to an inch

Brisbane flood, left bank, 1893. Produced by the Survey Office, this map shows the extent of the ‘Great Flood’ of February 1893 on the left bank of the Brisbane River through St Lucia, Toowong, Taringa and Auchenflower. Drawn over an existing sheet map of Brisbane, only one side of the river is shown. Field staff surveyed the city one section at a time from which a single map could be compiled. This map is signed by the staff surveyor ‘Mr Bedford’ and dated 25 March 1893. Collection of the Museum of Lands, Mapping and Surveying 

Built around a tidal river, some 20 km from Moreton Bay, Brisbane often floods, usually in conjunction with La Niña events bringing heavy wet conditions and cyclonic activity across the state.

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