PORT MOUTHS & SCOUR.

Dominion, Volume 6, Issue 1784, 24 June 1913, Page 5

PORT MOUTHS & SCOUR.

talk with me. Reynolds, c.b,

As instance of the effect of scour upon the approach to a harbour when the outflowing tidal currents, have been trained and guided, tho following particulars regarding Nelson Harbour are interesting—perhaps the more so because the conditions governing the approach to Nelson Harbour and Napier Inner Harbour ore analogous. So says Mr. Leslie H. Reynolds, C.E., who is the designer of the, Nelson works, and who has ateci investigatccl aptl reported on xsapier HarSpeaking to a reporter yesterday, Mr. Reynolds said: "The old entrance and approach to Nelson Harbour had a My water depth of from seven to eight feet. This was discarded in favour of the new entrance through the Boulder Bank, where tho depth seaward ranged from nine feet near the shore to 17 feet at low water over a distance of more than half a'mile out. My scheme provided' for ail entrance of 500 feet bottom width, with o depth of 15 feet at low water. The •Nelson Harbour Board, however, decided to execute a cut of about half the width recommended. Therefore practically only one-half of the tidal volumes allowed for in my scheme find ingress and egress through the new entrance. Notwithstanding this, however, the scour has teen instrumental ■in cutting cn approach to sea for a distance! of about 1800 feet and over an area of 141 acres, with a depth of from 42 feet to a minimum of 23 feet at low water spring tides, and over on area of 30 acres with a minimum depth, of 17 feet at low water extending to sea for over 2000 feet." Mr. Repolds went on to say that, had a full-width entrance been cut (and consequently the columns of the tidal outflow doubled), the scour would have been very much greater, and in his report of March, 1913, to the Nelson Harbour Board, ho had advised that if the out through the? Boulder Bank were enlarged, and certain dredging carried out inside the harbour, vessels of the Athenic class, or larger, could be handled and berthed at Nelson. Mr. Reynolds statqd that Wanganui furnishes another instance of efficient scour duo to efficient training of tlio currents. Ho is confident of obtaining 32 feet depth at the entrance and lower leaches of the Wanganui River, and he was emphatic., in his opinion that, when once the' entrance to tho inner harbour has been .widened and deepened, and the moles extended on certain lines which he has recommended, no further dredging will bo necessary. The increased scour, 1 ' he held, will maintain a depth in the approach of from 20 feet to 30 feet out to sea at low water. In connection with the port of Wangitnui, it ia of interest to record that the Union Company's salvage tug Tetawhiti (drawing over 13ft.) worked tho Wanganui bar recently an hour before low water. ,