RIVER EROSION IN SOUTH WESTLAND

Hokitika Guardian, 14 January 1929, Page 3

RIVER EROSION IN SOUTH WESTLAND

The Little Wanganui river during last week’s flood, as lias been reported already, eroded its north bank considerably to the danger of the InterWangamii Settlement. Mr E. A. Wells, County Chairman, at the request of Messrs Scarle and Chinn, members of the County Council, visited the locality, on Saturday, and was fully impressed with the seriousness of the position. The Harihari Settlement is greatly menaced by the flooding from the river, which overflows and covers the Flat by way of La Fontaine stream. The settlers immediately affected are greatly perturbed, and the situation is not only very serious, but presents a problem of protection very difficult to handle readily or effectively.

A visit was first paid to Lower La Fontaine. There the stream was not large enough to carry all the flood water, and it overflowed into other adjacent streams and depressions, while paddocks were covered, and for a tirnt the roads were under water. The water threatened to invade some of the settlers homes in the locality referred to, in one instance the water being within an inch of entering a raised building. Some fencing was carried away and other damage done to the paddocks. Alfred road bridge, near Mr A. Wall’s, was washed out, and part of the structure was recovered over a mil© down stream. Other bridges in the locality were covered with water during the height o*f the flood. One small culvert was washed out and restored, so that generally traffic requirements were met.

At the Little Wanganui river danger point where pile driving was to have been carried out under the original scheme of protection, the river made a dead set. and in a short time during the night carried away two chains in dootli of the embankment. This resulted in a good deal of County plant being washed away. The pile driving derrick was carried some six chains down stream and deposited close to the bank, where it would be recovered yesterday. A large Totnra tree, to which a heavy bush hauler was attached was aiso carried away, and despite the weight, the tree was carried seven chains down stream and deposited in mid-Channel. At first the hauler could not be located, but horsemen on Saturday discovered it submerged in midstream, in the centre of the river, and plans were at once laid for its recovery, the necessary gear being sent south Yesterday.

A heavy pile driving monkey and an iron hand-winch connected with the derrick .also disappeared at the height of the flood, and had not been located on Saturday evening. It will he seen from this that there was a great flood of water, with immense force behind it to do so much damage in so short a time. Workmen are engaged to-day recovering the plant. The river eroded with equally bad results further down stream. The lowlands along tlie north bank attracted the rushing waters, and native bush, willows and other plantations were washed out. The river made a deeper cut into the bank at tlie danger point where the overflow to La Fontaine swamp takes place, and all day Saturday a considerable stream of the river was pouring into the swamps. Thi c fed La Fontaine stream which was koot no to ordinary flood level throughout the day. Water was over Petersen’s road, and one culvert was washed out, while the homestead of Mr W. Witiskie was invaded, and he had to leave his quarters in the early hours of Friday morning.

It will he seen from the foregoing that the matter is very serious. A very large area of fanned land is involved, all closely settled, and with good homes. The damage now done has resulted from comparatively small floods. It is feared that were an “old man” flood to be experienced, and nothing done to check the flooding, a very grave disaster would result. The remedial measures have long been asked for. In the first instance the Public Works authorities thought it best to watch the position ! The watching continued till the river made its actual breach. Then a protective scheme was devised, and the work was about to begin when a- settler’s objection caused the authorities to stop the work. After a survey and further consultation with headquarters, an alternative protection scheme was fixed upon, of the nature of an earthen stop hank. This was the recommendation of the Public Works officers at Wellington. This work in turn was held up awaiting permission to enter on private lands to start the work. Then came last week’s flood.

The general situation is altered to some extent, and should lie inspected further and urgent work decided on and proceeded with. There are those in trie locality—who do not consider an unprotected embankment of earth can save the position. The experience with the river last week seems to hear that out. Local advice is in the direction of continuous piling, set apart, to direct rather than deflect the course or the river. It is considered that the present bight in the river lied presents a good opportunity to carry put such a scheme of protection, which would enable the bank behind tbn piles to form and gradually build up a material protection. It. seems imperative that tbo overflow of tbe river into the swamp should be chocked immediately. Tbe capacity of tbe creeks draining tbe swamp area is small, and tbe flood waters must overflow and do damage. Tbe bridges along fflie route are in jeopardy, and road access mnv be cut off at any time, which would be very serious for the settlers, most of whom are dairv farmers.

Mr Wells, County Chairman, though the matter is in tlie hands of the Inter-Wanganui River Board, is reporting fully oil the position to the Public Works Department, and asking for an immediate inspection of the position by the Department’s officers.