RIVER PORTS IN THE MAKING.

Dominion, Volume 6, Issue 1860, 20 September 1913, Page 13

RIVER PORTS IN THE MAKING.

Sir, —Under tho above heading in today's issuo of your papor is to bo found a most interesting and instructive account of Mr. C. li. Howorth's investigations as to port-making while on a visit to tho Home country and elsewhere, and his comparisons of circumstances affecting such work there and hero aro worthy of deep thought. Thero. is ono point, however, that has been either overlooked or skimmed over, i.e., tho removal of obstruction, such as sand, etc., by dredging. It is true that it is instanced by what is said with reference to tho dredging in the Mersey. It is not stated, however, whether this sand trends south from Morecambe Bay, where, I believe, thero aro larger sand reaches, or from what sourco the said accumulation is derived. It is not stated, either, if there is any travel of gravel such as is to bo found in New Zealand, andhas to be met. In New Zealand this, travel of gravel has been described ill a most illuminating way by the lato Mr. Blair, one of tho most scientific civil engineers w ; e have had, in a paper headed "Earth Sculpture." Not having the paper by me, I have to write therefrom from memory. In it then, as far as I can remember, ho points to the fact that Farewell Spit is tho result of the gravel from the West Coast of the Middle Island travelling north. Surely this is a stupendous object lesson of tho forces of Nature and of tho ponderosity of atoms, which we in New Zealand are trying to combat. Reference, too, is made to tho trend of gravel from tho south in the direction of Wanganui and New Plymouth. When passing tho latter place some years ago I noticed that dredging operations wero carried on in the inner portion of the breakwater, and the dredge proceeded out seawards to deposit it somewhere, I think, beyond a sand-bank, or somo other natural obstruction. Getting into conversation with a resident, I asked this question: "When tho breakwater was being made, w hat was the effect oil tile beach north thereof?" Tlio answer j was that the beach was denuded of ai portion of the protectivo gravel; to which I ■ replied: Does not that show that if the dredge deposited its load in that direction instead of out to sea that Nature would have removed it? I , also said that dredgingifrom tho innerpart protected by tho breakwater only made a hole for the sand to fall into, and that it might give better results if the dredging was done on the outer side of tho breakwater. Upon this I was told that much sand was blown over I from the shore.

. I bolieve that tho same ( denudation of the Western Spit took place when the Napier breakwater was made. A harbour with natural advantages, frco from tlio trend of gravel, was to be found at tho Kidnappers, but the vested interests probably in Scindo Island wore too strong to admit of that being adopted. Meantime tho gravel travels, and thero will bo accumulations on the outer sido of the breakwater which will have to bo met by dredging or protective groynes on the beach, as is done on tho coast of Norfolk, where much land has been reclaimed from the sea. The like conditions exist, in a measure at Gisbornc. In addition to tho gravel there is the deposit carried down by every stream to the rivers, and the rivers to the sea. As the country becomes settled, bush on the edges of the streams instead of being protected by legislation is cleared off, tho land stocked becomes hardened, and the soil, instead of absorbing the rain, only becomes a vehicle for a rush of water. Silt accumulates, hence floods, which will increase in intensity every yoar. It is evident, then, that here in New Zealand wo havo to contend against the travel of the gravel, plus the denosit carried down by tlio rivers, and wo are trying ill this Dominion to force Nature not to assist it. —I am, etc..

GEORGE HENRY DAVIES, Karori, Wellington. September 19. 1913