DISADVANTAGES OF RIVER NAVIGATION
It will have been assumed, from the two preceding chapters, that rivers, whether naturally navigable or rendered navigable by art, were of material service in supplementing defective roads, in opening up to communication parts of the country that would then otherwise have remained isolated, and in aiding the development of some of the greatest of our national industries.
While this assumption is well founded, yet, as time went on, the unsatisfactory nature of much of the inland river navigation in this country became more apparent.
Some of the greatest troubles arose from, on the one hand, excess of water in the rivers owing to floods, and, on the other, from inadequate supplies of water due either to droughts or to shallows.
The liability to floods will be at once apparent if the reader considers the extent of the areas from which rain water and the yield of countless springs, brooks, and rivulets may flow into the principal rivers. In the Report of the Select Committee of the House of Lords on Conservancy Boards, 1877, there was published a list which showed that the 210 rivers in England and Wales had catchment basins as follows:—
| 1000 miles and upwards | 11 |
| 0500 m"is to 1000 miles | 14 |
| 0100 m"is " 0 500 m"is | 59 |
| 0050 m"is " 0 100 m"is | 24 |
| 0010 m"is " 00 50 m"is | 102 |
| —— | |
| Total | 210 |
The rivers having catchment basins of 1000 miles or upwards are given thus:—
| Name. | County. | Length. Miles. | Area of Basin. sq. miles. | Tributaries. United length. No. miles. | |
| Humber | York | 37 | 1229 | 2 | 55 |
| Mersey | Lancaster | 68 | 1707 | 6 | 188 |
| Nen | Northampton | 99 | 1055 | 1 | 11 |
| Ouse | York | 59½ | 4207 | 11 | 629 |
| Ouse | Cambridge | 156¼ | 2894 | 8 | 212 |
| Severn | Gloucester | 178 | 4437 | 17 | 450 |
| Thames | — | 201¼ | 5162 | 15 | 463 |
| Trent | Lincoln | 167½ | 3543 | 10 | 293 |
| Tyne | Northumberland | 35 | 1053 | 6 | 154 |
| Witham | Lincoln | 89 | 1052 | 4 | 75 |
| Wye | Hereford | 148 | 1655 | 9 | 223 |
In times of heavy storms or of continuous rainy weather, rivers which drain up to 5000 square miles of country may well experience floods involving a serious impediment to navigation.
The Severn, which brings down to the Bristol Channel so much of the water that falls on Plinlimmon and other Welsh hills, and is joined by various streams, draining, altogether, as shown above, an area of 4437 square miles, is especially liable to floods. In a paper read before the Institution of Civil Engineers in 1860, Mr. E. L. Williams stated that floods had been known to raise the height of the Severn 18 ft. in five hours, and they had not infrequently caused it to attain a height of 25 ft. above the level of low water. The Thames and the Trent, also, are particularly liable to floods, and so, down to recent years, when considerable sums were spent on its improvement, was the Weaver.