Brisbane Flooded
The city of Brisbane suffered extensive damage due to flooding in 1893 and again in 1974. The prospect of damming the Brisbane River for flood mitigation was first investigated in the 1890s, in 1933 and in the 1960s. In the 1970s, land acquisition began for Wivenhoe Dam and construction was approved in 1976. During construction, in 1983, the partially completed dam mitigated a flood event that would have been on par with the 1893 floods. The dam was finally completed in 1985. Wivenhoe dam holds twice as much water as Sydney Harbour.
During the month of December 2010 Queensland experienced it's wettest month on record with an average rainfall of 209.45mm. The heavy rainfall was caused by Tropical Cyclone Tasha and affected large areas of Queensland including the Brisbane River catchment. With large volumes of water entering the catchment, Wivenhoe Dam was filled to 191% of it's capacity. When storage exceeds 100%, water must be released through the dam's floodgates. Wivenhoe Dam is not an overflow dam. If the water overflows the dam's walls, the walls could be eroded causing the dam to fail. This would happen if the dam reached 225% capacity.
To prevent the dam overflowing, massive releases of water from the dam took place on Tuesday 11th January 2011. Around 2:30pm that afternoon, the Brisbane River broke it's banks. The floods hit the city on 12th January and peaked on 13th January at a lower than expected level of 4.46m. Around 20,000 homes were inundated in low-lying suburbs including the Brisbane CBD, Fortitude Valley, West End, Milton, Toowong, St Lucia, Graceville, Chelmer and Rocklea.
Once the waters began to recede, Brisbane's residents came out in numbers and formed a "mud army", helping out those affected to clean up the mess. In affected suburbs, thick layers of mud were left behind by the receding waters and many people were unable to return to their homes for some time afterwards.
Mud Army
This cache will take you for a walk or cycle around our beautiful city and give you an idea of just how high the flood waters rose. You will begin in the beautiful Botanic Gardens.
Floodlines Stage 1
At the posted coordinates, is a marker showing the level of the 1974 floods. After the 2011 floods, a plaque was added to also show the level for that flood. Answer the following questions to calculate the coordinates for Stage 2.
- ABC = the amount of rainfall on Saturday night
- DEFG = the number of homes ruined
- H = B - D
Stage 2 is located at S27 28.AFD E153 01.ACH
Floodlines Stage 2
At Stage 2, look up to find the next flood marker. I hope you brought your snorkel. Answer the following questions to calculate the coordinates for Stage 3.
- I = the number of full bricks in the wall beneath the flood marker (including the brick that the bottom of the marker is attached to)
- J = I + H
Stage 3 is located at S27 28.GDH E153 00.JAF
Floodlines Stage 3
When you arrive at Stage 3, keep to the left and watch for other users of the path who can be travelling quite quickly. You do not need to cross to the right hand side of the path to answer the following questions.
- K = the number of recessed lines between the ground and the flood marker
- L = the number of rings beneath the flood marker
- M = A - L
Stage 4 is located at S27 28.LMK E153 00.DJM
Floodlines Stage 4
There is a nice little viewing platform at stage 4 so you can take your time and appreciate the artwork while you answer the following questions.
- N = the number of coloured stripes on the wall with the flood marker
- P = the number of letters in the first word of the name of the artwork
- Q = the last digit of the year of the artwork
The final cache is located at S27 28.LNQ E153 00.KPP
I hope you enjoy your experience and remember to be considerate of other users of the paths.
Many thanks to nikid1 for beta testing this cache.