The Tuia Mātauranga - Pōkai Whenua GeoTour: Whā follows the footsteps of early explorers of Aotearoa New Zealand taking you to places where leaders of the past searched for food, resources and ways to adapt and survive in this new land.
Use the Pōkai Whenua GeoTour as your classroom to explore the stories of the past, in the present, to preserve what is unique in Aotearoa New Zealand for the future.
Collect the codewords to get the Geocoin puzzle pieces
To be able to complete this GeoTour and receive your special Geocoin collectable, remember to take a note of the codeword placed in the cache. This will need to be recorded in your passport which can be downloaded here.
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63 of the 150 Pōkai Whenua GeoTour caches will contain a randomly placed special FTF token (a replica of the Tuia Mātauranga GeoTour commemorative coin). This is yours to keep! If you find more than one, you might consider leaving it for the next person who finds the cache.
The Rangitata Diversion Race is a masterful piece of engineering that was started at the tail end of the Great Depression.
Potted history:
- 2 April 1937 - Construction commenced
- 1938-39 - Picks and Shovel replaced by modern mechanised equipment
- 19th October 1940 - First pipe laid for the Surrey Hills high-pressure system
- 1944 - Race completed
- 8 June - First power generated from Highbank power station
- 1978-79 - Sand Trap installed (stop sand getting into the water race and damaging equipment)
- June 1982 - First power generated from Montalto power station
- 1 October 1990 - The government transfers the ownership of the RDR to a user owned limited liability company called Rangitata Diversion Race Management Ltd
Some facts
- Rangitata Race is 67km long extending from an intake on the Rangitata River at Klondyke to a discharge at Highbank on the Rakaia River.
- Can carry a flow of approximately 30 cubic metres of water per second.
- A second intake on the South Ashburton River can also divert approx 7 cubic metres per second of water (when available) into the RDR.
- Three Community Irrigation Schemes, two hydroelectric power stations, Ashburton District Council stockwater race system and various private stockwater and irrigation schemes are supplied by the race.
- Irrigation has priority of supply during the irrigation season extending from September 10th to May 9th each year.
- During the rest of the year, Highbank power station located at the Rakaia end of the race has priority of supply.
- The other power station, Montalto, is located 1.5kms downstream from the Mayfield-Hinds Irrigation Scheme.
- Major control structures built along the race include the Rangitata intake and sandtrap, checkgates, spillways and siphons passing under rivers and streams which cross the race.
- In total the RDR supplies irrigation to over 100,000ha of land during the irrigation season.
- It was officially opened in 1945, but wasn't in its present form until 1982 when the Montalto Power station was built.
- It is New Zealand’s largest irrigation scheme.
Bob Semple was Minister of Public Works during the depression and he saw that there would be huge gains in irrigating the Canterbury Plains - the largest area of flat land in New Zealand. The massive unemployment of the 1930s depression provided the catalyst for the work to start. Much was done at the beginning with pick and shovel.
The canal's engineering is amazing. The canal is diverted under several river and creek beds by an inverted siphon from the south side which pops up on the north side. There is one right by the cache.
Part of the consent conditions under the 1991 Resource Management Act required the RDR to install fish diversions to reduce the number of native and exotic fish from becoming entrained in the race. This has been a problem for the RDR to face as whilst a physical screen would work, the amount of didymo would clog it up too fast. 2kms downstream from the Rangitata River intake a behaviourial screen called a Bioacoutic Fish Fence that uses bubbles and underwater sounds to divert fish to a channel returning them to the river, was installed in 2007. At the South Ashburton River, a physical rock gallery was installed in 2008 together with a bypass to return fish to the river. The Rangitata and the Ashburton rivers both would usually have trout and salmon which are migratory fish and if they get into the water race they could be trapped and not able to get either out to sea or inland to their spawning grounds. so care is taken to make sure this doesn't happen. It is an issue that RDR still are dealing with today. They consult with a variety of interested parties such as the runanga at Arowhenua, ecologists, Fish and Game Associations, Department of Conservation, Environment Canterbury and others in order to find a solution that all agree with. The latest proposal is a rotary fish screen.
The new fish screen is in place! Fish screen newspaper article April 2022
You will need a pen.