RIVERS CONTROL

Hawke's Bay Tribune, Volume XVIII, Issue 46, 6 February 1928, Page 6

RIVERS CONTROL

COMMITTEE’S INVESTIGATIONS hearing of evidence. the WAITANGI Messrs A. J. Baker (chairman), H. \ ickerihan, and J. D. Tolmes, the committee appointed to conduct investigations in the district within the authority of the Hawke's Bay Rivers Board, with the object of arrivng a ta concluson as to the best means of controlling these rivers, continued their inquiries in Hastings this morning, when they took evidence. Mr T. E. Crosse, the first witness, said his experience extended to 1864. At that time the Waitangi was almost negligible, with a small channel and a narrow embankment across the impression. The big flood of 1867 and 1868 washed out a considerable channel at the present Waitangi opening. Every succeeding flood enlarged this opening. The 1897 flood washed away the whole of the Waitangi bridge and enlarged a deep water channel. He was a member of the local bodies at the time and they built a temporary bridge. Nine years after, the present bridge was built as a permanent structure. In doing so they fully estimated how necessary strength was. In 1910 they had to put in a full span to cover the whole of the river. That went to show that in each succeeding flood an increasing amount of water went 'll that direction, showing that it was a natural outlet. In the 1897 flooi]/ t*.rte was no evidence of cutting in the hard ground except in the Waitangi channel. The whole of the ground round the Waitangi was hard pan. If was a papa bed which gradually hardened. THE WAITANGI MOUTH. The formation of the Waitangi mouth said Mr Crosse, was different. When thev released the first pile it went into the bottom six feet on its own weight, apd on the first drive it went down two inches. After the pie was driven six feet, the next drive, instead of going two inches, went five, and continued at that until it was 30 feet in the ground. Then thev spliced the new pile on (6 or 7 feet) and that reached ground about 40 feet down. With regard to water getting out through the present channel, he noticed that the water did not strike the channel at all. The flood inter struck a few chains to the south of the present bridge towards Farndon station and then made a double curve. If the water went direct into the channel, the water would not accumulate before the river began to act. In bis opinion, that should be one of the first works to provide a channel to take the water away. The crux of the matter was to have a large mouth to take the water away.

THE OVERFLOWS. Regarding the oversows. Mr Crosse said he had no firm opinions, but lie felt certain that it was esential regarding the sNjaruroro overflows to make a complete channel for the Tutaekuri. If this channel was a thorough success it would he easy to decide the best wav to deal with, .lie water in the Ngaruroro. Regarding the_ Ngaruroro at the time of the 1897 flood be owned land between the .Napier road and the Ngaruroro at Whakatu. Prior to that flood there was a much smaller accumulation of shingle at the junction of the old bed and the new one but afterwards the accumulation was tremendous. The shingle caused the water to go over to the northern bank. The Whakatu bridge in that flood was badly shaken, and to strengthen the piles rocks were placed there. It was prior to his owning the land that the first rocks were placed there hut they were added to in 1897 to strengthen the pile's. A good deal of the accretion was caused by the shingle bed. and the shingle bed was caused by the contraction of the channel ;.t the bridge. The river channel, from Pakowhai down had carried the water without difficulty, and it took a big flood to overflow the Pakowhai bridge hut now it did not take a heavy flood. In each succeeding flood there seemed to be less and less water going under the Clive bridge, so that the obstruction in the channel seemed to be increasing between Pakowhai and the sea. He was convinced that these obstructions should be dealt with before the question of embankments were Proceeded with. Since he bought his property. 30 years ago. the level of the water from St. George's "oad, Havelock, had risen, and there was dead water non- where 30 years ago there was a considerable flow. - THE LIABILITY. The liability for finding a mouth for the Tutaekuri river rested with the Harbour Board, continued Mr Crosse because thev decKlen cli.il before the- could proceed with the harbour—that did not refer to the Breakwater or to the Inner Harbour —they would have to deal with the river. Then the whole district would extend from Mohaka to Woodville, whereas if it rested with the Rivers Board, the Meeanee district would he solely responsible. If the Rivers Board had machinery thev -ould have a satisfactory channel for ever, but restricted finance made it necessary to do work which was destroyed by every succeeding flood. The Tuki Tuki works were permanent, because the work was not piecemeal. The proper procedure was to deal jrith the bottoms of the rivers before raisin- embankments, which would only create trouble in the future.

Mr. C. E. Evans, Hastings, borough engineer, said he had been borough engineer for over four years, but he had not previously been in the district. They were anxious that v hatever was done would benefit the district by lessening the flood levels. The flood waters did not really concern Hastings, but siltation in the river had been going on. It had been hoped that the river from I’akowluii would have been straightened in order to increase the velocity and thus reduce the flood level. The removal of structures would in a great measure assist in keeping the level down without great expenditure being involved. FLOOD LEVELS. Mr. Evans asked what flood levels of any new scheme would be in relation to the Pakowhai bridge. If the scheme gave a higher flood level it would then affect. Hastings as far as the outlet for a sewer. In reply t> Mr. Baker, Air. Evans stated that *the river did back up the sewer, i rich could be overcome

by the reduced flood level. If high stop banks were to be the only means of dealing with the flood waters then it would bo greatly affected. He could supply the average datum of the Borough of Hastings in respect to low-tide level. Mr. T. Donovan, a member of the Hawke’s Bay Rivers Board representing Hastings, said that he was well acquainted with the district during the last 44 years. When the sewer was built there was a decided drop from the bottom into the river of about four feet, and now owing to silting up it had to be sounded with a pole. Referring to Mr. Hay’s schemes, Mr. Donovan said it . ould cause the water to back up the sewer as far as Tomoana, and consequently the sewerage. His own opinion of the better way of dating with the rivers would be to straighten and deepen them. The Fernhill bridge had twice been washed away with flood waters, on each occasion the water going over the top of the decking. The level of the present structure was considerably higher than that of the previous two. The whole of the. water over Broughton’s flat, much of which got behind the stopbank, had to come through, and in order to confine the waters, ne was of the opinion that the northern bank should be extended. SAFETY OF WHAKATU WORKS. Mr. George Ebbett, managing director of the Whakatu Freezing Works, then gave evidence, Mr. F. S. Candy (manager), and Mr. John Barker being in attendance. Mr. Ebbett said that their concern was the safety of the Whakatu works. From Mr. Hay’s scheme they gathered that the whole of the waters of the Ngaruroro from Fernhill downward was to be confined between banks to a spot near the works opposite which was to be a spillway. Realising what the effect of the whole of this water being confined between banks would be, they engaged Mr. Climie to make various surveys. The effects of floods would .be the flooding of the works. . Mr. Climie had advised that before the water could flow over the spillway, it would be level with the floor in the works. Mr. Candy explained that there would be but two feet going over the spillway when the level or the floor would be reached. Continuing, Mr. Ebbett said that it would mean the installing of expensive machinery to pump tlie drainage

from the works over the bank. lf f the whole of the water for some distance up the river was to be confined to the river, the works might easily be seriously affected by even a moderate flood. Mr. Candy stated that during the past 12 years there had only been three or four floods which had interfered with the works, when the level of the drainage was on a level with the boiler-house floor. Whether it had been the level of the river he would not like to say. Such conditions had never occurred during the height of the killing season. It was very important that the river at Whakatu should not be dried up. If the volume of water became small a nuisance from the drainage would be such as could not be tolerated. Mr. Baker said that there was no scheme contemplated which would have that effect. WOULD LIKE TO BE SURE. Mr. Ebbett said that great changes often took place, and they wouid like to feel very sure about it. Mr. Baker, in reply, said it was intended, he understood, to utilise the maximum capacity of the present river channel. The installation of a pumping plant, which could be brought into operation once the water was rising, would overcome the difficulty at the works. The high peaks of the floods did not last long, and such dangerous floods apparently only came at remote intervals. The works proprietors naturally had the welfare of the district at heart. There was about £200,000 worth of buildings and plant at stake, and any scheme that would endanger their safety would be strenuously opposed by the directorate. The chairman said that the position of the works would be borne in mind in the committee’s findings. It had to be remembered that no scheme could be taken into consideration that would altogether minimise the works’ present drainage problems. Mr. Ebbett said that they were all right as they were, and work could proceed without serious interruption. Once alterations were made to a river there was no telling what the effect would be. The highest flood in history had never been known to flow over, the land opposite the works. Many fears ago there was a pa established there, the Maoris always making it a practice to build only on high ground. Mr. Isaac Robin, who owns land opposite the Whakatu Works, said that the whole area along the river from Pakowhai was very high. He bad never known floods go over it. The Whakatu bridge, however, hud

been an obstruction to the flood waters, there being a difference in the levels of about six feet. During flood time the bridge somewhat resembled a waterfall. The strip of land that remained dry was not, however, very wide, owing to the waters from the Tutaekuri and overflow water from the Ngaruroro higher up coming in behind. He was strongly of the opinion that the overflow should be through the lowest country, leaving the river some distance above the Pakowhai bridge. Through the swamp, he thought, was. the propercourse for any overflow. The channel had narrowed very considerably, while the bed had been filled with,, gravel of many feet. The shingle deposits had changed from time to time, even at Kahupatiki the river’s formation had changed considerably during the past twelve months. MR G. ROCHFORT’S EVIDENCE. The committee resumed its sitting this afternoon when Mr G. Rochfort, civil engineer and surveyor, save evidence. Mr Rochfort stated that, in March 1924, there was an exceptional flood in which the water sot round the northern bank at Fernbill. Since then the bank had been extended and raised In answer to a question by the 1 chairman. Mr Hay said that his pro posals provided for extra banking above Fernhill bridge. Continuing. Mr Rochfort said that the first survey of the Ngaruroro was made in 1919 and the second in 1925. The second survey showed deposits cf shingle and denudation of the main channel. The Hastings sewer was above tidal level when it was put in about 40 years ago. He admitted that a very considerable area had eroded on the southern side of the river betwen Fernhill and Roy’s Hill during the last 15 years. This would account, no doubt for some of the filling in of the river channel below Fernhill. He had no knowledge of any hard pan in the Ngaruroro river. The mouth had travelled northward along the beach near the Waitangi bridge. As far as he knew there was no hard pan at the Waitangi or the Washout. The 1897 flood was the first one that he saw. it being one of great magnitude. There was a record showing the area inundated and the levels reached by the waters. The water came over the lower Roy’s Hill and inundated a portion of the south end of Hastings The next big flood was in 1917, which later gave rise to the 1919 report

,’J'hat flood did no great damage, it being about 50 per eent lesser magnitude than the 1897 flood. It was a sharp occurrence, the maximum height being equal to that of the '97 flood but the peak did not last for more than an hour. Mr. Rochfort then dealt with the March 1924 flood and that of July last. The latter, he said, maintained its peak for about 18 hours. The level at the Fernhill bridge was five feet lower than that of March. 1924. Asked whether the damage created by any of the floods warranted an expenditure of about £150,000. Mr. Rochfort said that if the March flood had lasted for 12 hours Napier would have been flooded. A flood equal to that of 1897 would to-day do tremendous damage and if the peak of subsequent floods had lasted longer much greater damage would have resuljjpd. He considered that the expending of such an amount was warranted for the safety of the district. ENG IN EERS’ EVIDENCE. The commitee on Friday examined Mr P. C Hay. consulting engineer 01 the Rivers Board, and Mr H. R, Climie. of Messrs Climie and Son. Mr Hay produced and explained the plans he has submitted to the Board for the complete control of the Tutaekuri and Ngaruroro rivers, including the diversion of the Tutaekuri river from PowdrelJ’s Bend through the Washout railway bridge, and the stop-banking of the Ngaruroro river to carry the whole of its flood waters down to the proposed overflow on the right bank immedi ately above the Whakatu railway bridge. This stop-banked overflow will run in a north-west direction to junction with the diverted Tutaekuri river in the vicinity of the Washout railway bridge, and the combined waters after passing under the railway. will be carried bv a separate outlet to the sea. Mr Climie produced plans of his proposals which are substantially the same as those submitted by him to the Rivers Board on 25th July, 1926. I nder these proposals Hood waters of ‘.he Ngaruroro river will be diverted af “'rhe Piifes,” and carried bv in overflow channel via the old Ohiwa stream bed and other depressions near Waiohiki to junction with the Tutaekuri diversion channel which lakes oil from (he existing bed of the Tutaekuri river at a point about I II) rhains above P>.- droll’ - Bend. Mr Climie |>i • ■ a spillway at the cntrancce io «'• X <>•■.! ruroro < ver How 20 chain” ’ s height to be .*-(» regulated th” 1 ixihium floods

the Ngaruroro river be required to carry below the spillway flood raters equal to the capacity of the river at the Whakatu bridge, the balance being carried by the overflow., but at ordinary floods a lesser quantity will proceed down the Ngarururo. tho balance likewise being taken bv the overflow channel. It is proposed to stopbank the overflow channel, cut ting a pilot channel in it. it then being lett for the floods as they occur t o enlarge the channel by scour, so that its capacity will be brought up to the maximum required. The Tutaekuri diversion channel is to have sufficient width to carry the combined Tutaekuri waters and the overflow of the Ngaruroro. Mr Climie’s proposals provide foi this stopbanked channel as it appraches the railway being widened as to include both the Washout and Waitangi ailway bridges, the waters then proceeding via the lagoon to the sea through the existing Ngaruroro river mouth. On Saturday the members of the committee of engineers, accompanied v Mr J. A. Miller, chairman of the Hawke’s Bay Rivers Board, made a detailed inspection of the route selected for “The Rivers” diversion channel as far as Powdrell’s Bend, and of the route selected for the Ngaruroro overflow at the Whakatu rail-.-ridge NAPIER’S EVIDENCE. iriSENTATIVES HOLD MEETING. A meeting of representatives of various local bodies was held in Napier this morning to consider what evidence should be placed before the committee which is now investigating Hawke’s Bay rivers control. The meeting found itself hampered to some extent bv the absence of definite information as to what schemes were being investigated. It was decided, however, to watch proceedings very closely, and arrangements were made for evidence to he tendered setting out the views of the Napier local bodies in regard to the various schemes which it is understood are under consideration, in so fur as such ehenies nine affect Napier. Taradale. Greeiiineadows \li ii a ami the immediate district.