GC4TD8D Top of the stopbank (Manawatu) (Multi-cache) in North Island, New Zealand created by the Seagnoid

GC4TD8D ▼

A cache by the Seagnoid Message this owner

Hidden : 11/23/2013

Difficulty:

Terrain:

Size: Size: small (small)

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Geocache Description:

The floods of the Manawatu.

Here at the page coordinates you will find a tall pole, a flood marker, showing just some of the floods that the Manawatu district has endured. See my cache Manawatu rail: Oroua Bridge for a more complete list.
The Manawatu is a large flat plain, and originally was heavily forested, nature's way to control flooding. The introduction of settlers in the 1870s converted the forest into pasture and now very little of that original forest is left.
Flooding has become such a major issue that the city and regional councils have built stop banks over much of the entire length of the Manawatu. The only places this has not been done are places like right here - where there is a natural bank up to the Victoria Esplanade. Incorporated into the stop banks are spillways that release flood waters out of the river and onto neighbouring farms (if flood waters break over a stop bank they will erode them, and cause uncontrolled flooding. Better to have controlled flooding in an area that can be managed). The farmers are given plenty of warning to move their livestock, and the councils pay for this privilege by charging cheaper rates.
The stop banks have been progressively raised over the years. Indeed, the one just upstream, adjacent to the Massey bridge was raised by another metre this year, in 2013.

The 2004 flood

In February 2004 heavy rains on both sides of the Tararua and Ruahine ranges produced a one in a one hundred year flood. The storm raised the Manawatu River 8.5m higher than normal (as measured at the measuring station just upstream from here). Water flow increased from a normal flow of about 70,000 liters per second to 3.5 million liters per second! Due to its stop banks, Palmerston North was largely unaffected, although some outlying people were unable to get to work. Country people did not fare so well. A few days after the rains stopped I had to travel to Levin. At Opiki I saw a paddock full of water, with a house in the middle of it flooded to the top of its garage door. Luckily the living spaces were all upstairs. Here the stop banks compounded the problem - should flood waters get past, they prevent the water from receding once the river level drops.
The storm affected most of the lower North Island, from Wanganui to Wellington. While the Manawatu and Wanganui rivers only (!) had a 10 and 70 year flood event, the Whangaehu and Oroua (Feilding) rivers where in excess of a 200-year event. Over 1000 farms were flood damaged, 5000 sheep and about 800 cattle were lost. 2300 people were evacuated, and 3 months later 400 homes were still uninhabitable, nearly 1000 people still homeless. 300 cars were written off. Due to the loss of crops and the resulting shortage, the price of vegetables in the lower North Island rose over 200%. Insurance payouts totalled $112m. Soil repairs consumed another $10m. Roading repairs $77m. River and flood control repairs $25m. $13.5m in lost milk production. Many roads were still closed a week later. The main gas line from Manawatu to Hawkes Bay was closed, 6000 users affected.

The 2015 flood

Although not as bad as the 2004 flood, after a week of heavy rain in June 2015 much of the west coast of the lower North Island declared a state of emergency. Foxton Beach had the worst flooding in 30 years, Te Horo in 70 years. In Feilding residents were asked to avoid using water at all - drinking water was fine, but the sewer systems were overloaded. In New Plymouth sewer contaminated water was in the streets, and the council was forced to discharge raw sewerage directly into the sea. One house in Bainesse was flooded to the roof. Palmerston North came away mostly unscathed due to its stopbanks.

The cache

The cache is hidden at S 40° 22.ABC E 175° 37.DEF, which is only a short walk away.
Where:
A = Month number of highest flood recorded.
B = Number of events recorded during the 1900's
C = Sum of the digits of the range of years recorded.
D = 3rd digit of the year of the lowest flood.
E = Last digit of year of the flood that reached 2.2m above ground here.
F = Number of eels in the panel behind you, minus two.
Checksum = 20

The cache is hidden hopefully out of reach of any floodwaters.
Were you affected by the 2004 flood? Tell us what happened in your log! You are welcome to post photos, but note that if the answer to the questions above are legible in a photo, it will be deleted.

Happy hunting!

Images from the 2004 flood:

Ballance Bridge. The main road crosses the Manawatu Gorge at the Woodville end here. Showing a normal and a not-so-normal day!

Fitzherbert Bridge looking towards Massey.

Fitzherbert Bridge.

The stop bank at Ruahine Street.

	Scotts Ferry was the worst hit. Yes, that is how high it got!
The Saddle Road bridge over the Pohangina River, Ashhurst.

From the 2015 flood:

Fitzherbert Bridge. Not as high as last time!

Pioneer Highway bridge, beside the cache Manawatu rail: Awa Puni.

References:
"Destructive Deluge" published by Westmount School, Palmerston North, 2004. All of the photos of the 2004 flood were taken from this book.
Stuff.co.nz
Palmerston North City Council
Niwa Historic Events catalog, hwe.niwa.co.nz.

Additional Hints (Decrypt)

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)