DRAINAGE IN URBAN AREA

Press, Volume LXXXVII, Issue 26399, 18 April 1951, Page 8

DRAINAGE IN URBAN AREA

Flooding In Recent Storms BOARD’S VIEW OF PROBLEM “For nearly five years the board has not been allowed to put its plans into action, and the two recent storms, with the resultant flooding, have emphasised in an unmistakable manner the correctness of the board’s contention that the separation of the drainage control of the urban area from the rural areas north and south would be fraught with direct and serious consequences for Christchurch.” said the chairman of the Christchurch Drainage Board (Mr E. H. S. Hamilton) in a report to a meeting of the board last evening. “The effective drainage of the metropolitan area depends upon the full control of the whole of the watersheds of the Styx, the Avon, and the Heathcote being in the hands of the authority," the report said. “Continued separation of the drainage control of the urban area from the rural areas north and south will bring dire consequences to Christchurch, and those who advocate separation are assuming a very heavy responsibility and will be doing a grave disservice to Christchurch.

“The heavy downpours of rain on February 9 and 10 and April 1 and 2 caused severe flooding in several parts of the board’s district and have re-emphasised the necessity for major stormwater relief. Christchurch and the surrounding districts are on a flat plain, little above sea level, and drainage of the area depends upon three main outlets, the Heathcote end Avon rivers through the city, and the Styx river to the north.

“The district has normally a low average rainfall which can be dealt with by a fairly effective drainage system, but periods of heavy rain bring wide and extensive flooding. Each year, as more houses are built and roads formed through what was previously open country, thus speeding up the discharge of rainwater into the drains and rivers, the problems of disoosal of flood waters are increased.

“The Christchurch Drainage Board adopted in 1946, on the advice of its officers, a policy which involved full control of the whole of the watersheds of the Styx, Avon and Heathcote.

The problem in connexion with the Heathcote river is not only one of maintaining adequate waterways, but also of controlling the run-off from the Port Hills and dealing with the problems of erosion. Full agreement has been reached with the North Canterbury Catchment Board regarding these matters, but the Port Hills are at present excluded from the Drainage Board’s district , “The river Styx offers the only logical solution of the problem of relief of the northern parts of the metropolitan area, and of the adjoining productive rural areas, from the flooding but again the key to the solution of the difficulties is outside of the boards district

At present Dudley Creek is .the main drainage outlet for the whole 01 the densely settled area of northern Christchurch and is so closely built upon that there is little room for its enlargement” Engineer’s Report Further reference to the recent floods was made in the report of the engineer (Mr E. F. Scott), who said that the Dudley creek area suffered severely. “Little can be done to relieve the position at the height of a flood except by major works,” Mr Scott said. “One feature of the recent flood was the ‘cloudburst’ on Mount Pleasant on the morning of April 2, which caused serious erosion on the Port Hills. All hillsides, particularly from Murray Aynsley’s Hill to Sumner, carried large streams of water which did much damage to roads, and deposited silt and clay on the lower levels. Augusta street was one such area to be so flooded with clay-laden water, due largely to the fact that Tauhina avenue above Moncks Spur road has inadequate drainage pipes across it, and earned large volumes of water that should flow into McCormack’s Bay, down the road until discharged into the Augusta street valley. “A large number of telephone and written complaints have been received, and the staff have met several groups of residents in particular cases. The overloading of the sewerage system has added materially to the concern of householders. “The works committee recommends that a meeting be arranged with local members of Parliament in order that the board’s views on the drainage problems of the metropolitan area, and the necessity for the control of drainage from the Styx to the Heathcote watershed by one authority may be reiterated.

“It is also recommended that a conference be held with the Heathcote County Council regarding hillside drainage, and further that the chairman of the board, the chairman of ttie works committee, and the engineer, prepare a statement in regard to flooding, for the information of the public.”

Mr J. E. Jones said he agreed witn the statement, but thought it might have explained more clearly why the board had been unable to carry out its plans. The fact was, he said, that the Local Government Commission’s report had not been implemented. It would be well for the public to know that the board had a plan of action but that it had been held up, said Mr R. Jones. “Mr Scott has shown he is concerned. He is no alarmist, but he has given us a clear warning that the future solution of the drainage problem is a matter for concern,” said Mr H. P. Smith. “I hope this will not be taken as a squeal by the board against absorption. Whether the board is absorbed or not. this problem remains unsolved.” plr Hamilton stated that the meeting with members of Parliament would be held on Thursday.