Once again, the people of Napier, Taradale, Bay View, Eskdale and Tangoio, have been subject to disastrous flooding with severe losses by both town and country people. Possibly ﬂood is one of the calculated risks we have got to face, like earthquake, and no amount of men or machines can entirely prevent such disasters occurring, they can only be minimised.
As nobody knows just what form the next deluge will take or where it will fall, engineers etc. and all the people concerned with flood control have a most difficult task. This does not mean that we should be resigned to our fate, every effort should be made to prevent and minimise ﬂooding of any kind, and it should be borne in mind that in any ﬂood control plans, human life is by far the most important subject matter to be safe-guarded. As a point of interest, we re-publish the drawing and context of the Heretaunga Plains River scheme.
Right up to recent years the Heretaunga Plains of Hawke’s Bay have been subject to ﬂooding, – not just surface water from local rains, but major ﬂooding from three of the six main rivers that enter the Bay – the Tutaekuri, Ngaruroro and Tukituki Rivers. Although two of the worst ﬂoods occurred in 1867 and 1897, before back-country hills were entirely denuded of bush, the clearing of land for grazing has certainly not helped the plains area with its ﬂood problems. However, since the Rivers Board, and later Catchment Board, have been formed, the control of these three rivers has been less a matter of chance.
Now, the Catchment Board is completing the scheme which should protect the Heretaunga Plains from any further floods.
In the diagram below, the Catchment Board has outlined the changes to be made.
1. Redesign Tutaekuri banks to take 100,000 cusec. flood.
2. Divert Tutaekuri to form common mouth with Ngaruroro.
3. Redesign overﬂow banks to take full ﬂood ﬂow of Ngaruroro of 160,000 cusec.
4. Divert Ngaruroro completely into its overflow channel.
5. By double banks, discharge flood waters of Tutaekuri Waimate into system by gravity.
6. Build new road and rail bridges which will be at least 400 ft. longer than existing bridges.
7. Construct new bridge at Pakowhai over Ngaruroro, 1,300 feet.
8. Retain existing channel of Ngaruroro for free discharge of Karamu and Raupare Streams draining 200 square miles.
9. Install pump station to drain 2,600 acres of Pakowhai-Waiohiki area.
10. Install pump station to drain 2,300 acres of Brookﬁeld-Awatoto area.
11. Karamu Stream ﬂoodgates to be removed.
12. Remove bank between Tutaekuri and overﬂow to use existing Tutaekuri bridges as outlet for excess floodwaters.
The reasons for making these sweeping and costly changes in our river system are also made clear by the Board. At present neither the Tutaekuri nor the Ngaruroro is capable of maintaining an open mouth to the sea, on its own. The re-alignment of the two rivers so that they combine about three-quarters of a mile inland will give a much stronger ﬂow aimed more directly at the beach. The Tutaekuri, from Brookﬁelds to the sea, loses ﬂood capacity through silting up; the Pakowhai area becomes ﬂooded when ﬂoodgates are closed on the Tutaekuri-Waimate; the Ngaruroro also tends to silt up from Pakowhai to the sea; the area served by the Karamu Stream and its tributaries – an area of 200 square miles including Hastings and Havelock North – becomes ﬂooded when ﬂoodgates are closed at the junction with the Ngaruroro. This latter area will beneﬁt greatly from the proposed scheme. Not only will the Karamu Stream have free outﬂow into the existing Ngaruroro riverbed, but, £160,000 will also be spent on improving the Karamu and its tributaries.
The whole scheme, spread over four years, will cost in the vicinity of £620,000, of which local ratepayers will have to ﬁnd approximately £200,000.
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