LEITH FLOODING

Evening Star, Issue 22596, 13 March 1937, Page 22

LEITH FLOODING

CITY PROTECTION WORKS EARLY REPORT TO COUNCIL ONE SECTION TO COST £50,000 LINK WITH HARBOUR BOARD’S SCHEME Although it is nearly eight years since the last disastrous Hood in the Leith and over six years since the three engineers presented their £617,000 scheme for flood protection, the City Council has yet to undertake a major part of the works in the city area. However, the Harbour Board, which is responsible for that section of the Leith Canal between the Forth street bridge and tho outlet, is making very satisfactory progress witli the widening, first started in 1932 and suspended for some time. The City Council’s engineer is at present completing the plans for the enlargement of tho canal above the Forth street bridge to the Union street bridge, and Cr J. W. Munro, M.P. (chairman of tho Works Committee), stated to-day that the details would be placed before the council shortly. The problem of finance had played a part also in delaying the initiation of the council’s protective works. A sum of about £50,000 was involved for this section, he stated, and tho city engineer (Mr J. G. Alexander) and the harbour engineer (Mr J. M‘G. Wilkie) were working in close collaboration. The huge scheme outlined after the 1929 flood by Mr F. W. MacLcan. the Wellington engineer, and Messrs Alexander and Wilkie was of a nature that lent itself to an exceptional extent to dissection, and it is possible for one or more of the recommendations to receive attention from time to time: without prejudice to the scheme as a'whole. Soon after the report of the Engineering Commission was issued, the City Council constructed two boulder traps in • the Water of the Leith near the Woodhaugh palper mills, and Lindsay’s Creek has also been deviated, widened,, deepened, • and straightened' above the Gardens. The original scheme—” to afford reasonable • immunity from flooding _ —proposed • substantial alterations in the structure of bridges that have been constructed across both the Leith and Lindsay’s Creek —in some instances renewal and, in others, the provision of increased waterway either by the building of side culverts or by raising the deck level—and the widening ot tho Leith throughout a largo portion of its length and the deviation of the stream at certain acute bends. . A MODIFIED SCHEME. The maximum discharge of the Leith in the flood of March 19-20-,-1929, was estimated to be 11,500 cusecs, and the three engineers considered that , im munity would be provided in the future if provision were made for a _ .?J~ discharge of 14,000 cusecs in the Leith below the Lindsay’s Creek junction, with proportional discharges in the flood, was believed to he the highest , ev.er ,experienced! in the Water of the Leith,' being caused 'by, tremendous rainfall in the hills and the city. The scheme, was,, at, the time,. 'beyond) the -financial' capacities, of the City Council and the Harbour-Hoard, ■and the latter body o.btamcd a further report from Messrs Wilkie and h. JWilliams that reasonable provision tor protection of its property and the area over which, it was held responsible would be given by widening the canal to carry 10,000 , cusecs— double the original maximum capacity of the channel—and amended the scheme accordingly, the City Council agreeing to the adoption of 10.000 cusecs as the standard'. , , „ , rr „ From Forth street to Harbour Terrace the Harbour Board has increased the width of the canal from 40ft to 70ft, and from Harbour Terrace, to Anzac Avenue, a distance of 660 ft, a new channel 40ft . wide has been constructed. The City Council’s engineering staff is now extending the highway bridge, built shortly before the Exhibition but difficulties in finding suitable foundations have hampered -the progress of the work. BELOW THE HIGHWAY. Now the board is continuing steadily with its work below the highway. towards the sea. For 200 ft the width of the channel has been increased from 50ft to 100 ft, and the concreting of the walls and the bottom is to _ be started without delay on this section. The cantilever bridge across the present, canal is to be removed.* Later. the waterway under the railway bridge and thence to the harbour will also be increased to a width greater than the canal yet to be excavated down-from the present stage of the work. Earth levees to hold any overflow back are to be constructed on both sides of the canal below the highway. While the work now in hand is less ambitious than the scheme first proposed by the engineering coinmission, provision can be made at some future time, if necessary, to carry 14,000 cusecs from Auzac Avenue to the sea. URGENCY PREVIOUSLY STRESSED The urgency of the protective works was one of the reasons advanced by the Harbour Board in its application in September, 1931, to the Unemployment Board for assistance under scheme No. 5, and in 1934 the secretary-trea-surer-(Mr James Renton) reported:— “ It is considered that now the parapet walls have been raised below Forth street the further works proposed to be undertaken by the board would be practically useless if unaccompanied by the widening of the council’s portion of the canal at and above Forth street bridge.” The advancement of the board’s work suggests that the City Council is soon about to undertake its constructional _ programme on the Leith. The necessity for co-operation has always been admitted by the two bodies, and Cr Munro stated to-day that the city and Harbour engineers were still collaborating closely. In addition to widening, the City Council’s original proposals on tlie stretch of canal above the Forth street bridge to the Union street bridge included a new traffic bridge at Leith street. From the University across the Pelichet Bay reclamation, the Leith has a very flat gradient, and consequently the widening < .i this long portion will be greater than on any other section. ■' From the character of their catchment areas, the Leith and its tributaries are very liable to sudden extreme floods. Before the areas in the lower and flatter portions of their valleyc were built over, the streams were free in flood time to overflow on to the adjoining lands, and to change the course of their channels. With the occupation of the land by streets and buildings, and the reclamation at the mouth of the Leith, this freedom has

been restricted. Indeed some of the land built on near the harbour is very little above the level, of the high tides usually associated with storms causing floods during south-easterly winds. These factors, coupled with the mountain torrent nature of the streams, affect the difficulty and expense ' of dealing -with flood waters. Tfye widening, under the subsidised scheme, is estimated to cost nearly £25,000 to the Harbour Board, whose share of the extra span of the Anzac avenue bridge is estimated to be nearly £5,000. while the estimate for the City Council’s work on Lindsay’s Creek from Opohp road to the northern boundary of the Nithvale property, near Craigleith street, is over £16,000.