TRANSACTIONS OF SECTION G. 757 



The following Report and Papers were read : — 



1. Report of the Estuaries Committee. See Reports, p. 386. 



The Ystradyfodivg and Pontypridd Main Sewerage. 

 By G. Chatterton. 



3. The Biver UsJc, and the Harhour of Newport. By L. F. Yernon-Harcocrt, 

 M.A., M.Inst.G.E., Engineer to the Newport Harhour Commission. 



The river Usk rises on the western horder of Bi-eckiiockshire, and, traversing 

 this county and Monmouthshire, it flows into the Bristol Channel, ahout 4 

 miles helow Newport, after a course of 65 miles. Its basin is 6-34 square miles ; 

 and the Afon Llwyd joins it at Caerleon, and the Ebbw near its mouth. The com- 

 mercial importance of the Usk commences below Newport Bridge, about 6 miles 

 from its mouth ; and wharves extend along the right bank for 2\ miles below the 

 bridge, and the vessels lying at the wharves rest, at low tide, on the soft mud 

 covering specially levelled berths. The Newport and Alexandra Docks also afford 

 floating accommodation for large vessels on the western side of the river, on which 

 side the town of Newport is mainly situated. These docks have water areas of IH 

 and 285 acres respectively, and the depth of water over the sills of their entrances, 

 at spring tides, is .30 and 35 feet. A large extension of the Alexandra Dock, and 

 a new entrance lower down the river, are approaching completion. The quays are 

 supplied with coal tips, sidings, and hydraulic appliances ; and the docks and 

 wharves are connected by railway with the mines and works in the neighbouring 

 district. The eastern side of the river is almost wholly undeveloped; but roads 

 are being made, arid the East Usk Eailway has been authorised, which will give 

 facilities for trade, and .should lead to the extension of the port along the left bank. 

 The portion of the river constituting the harbour of Newport is very winding ; and 

 though it increases considerably in width between the bridge and its mouth, thus 

 favouring the tidal influx, the enlargement is not uniform, which causes changes 

 in the velocity of the current, and promotes deposit in the channel where the cross 

 section is excessive. Moreover, the bends of the river make the flow and ebb, 

 coming in opposite directions, form channels on opposite sides of the river between 

 the bends, leading to the growth of a central sandbank between these side channels. 

 Besides these central shoals of sand and silt, readily formed in a river densely 

 charged with material in suspension, there are some hard natural shoals of clay and 

 stones, and also shoals at the confluence of tributaries, formed of detritus and 

 refuse from works, brought down by the current in flood-time, and deposited in 

 the Usk. The great tidal rise of the Usk, amounting to 34 feet at the bridge and 

 40 feet at the mouth at the top of springs, and 14 and 16^ feet respectively at 

 neaps, has hitherto enabled Newport to maintain a large and increasing sea-going 

 trade, in spite of the deficiencies mentioned above. Comparative cross sections of 

 the river, taken in 1884 and 1890, have shown, however, that accretion is taking 

 place in the river, and gradually reducing its depth, whilst the draft of vessels 

 tends to increase. Accordingly the Commissioners have decided, on the advice of 

 the author, to dredge a channel across these shoals, so as to form an adequately 

 wide navigable channel, not less than from 24 to 20 feet deep at high water of 

 the lowest neap tide, down to the Alexandra Dock entrance, and 26 feet deep (or 

 2 feet lower than the lowest dock sill) from this point to the mouth of the river. 

 These works, involving the removal of over 300,000 cubic yards of material from the 

 bed of the river, will meet the present requirements of the port ; .and further 

 improvements can be gradually carried out in conjunction with the work of 

 maintenance, as circumstances may render expedient. The formation of this 

 improved channel will lower the low-water line, and regulate its fall, which at 

 present is not uniform, and thus increase the tidal capacity of the river, and im- 

 prove the scour of the current. In order to render the flow of the river more 



