NA TURE 



66i 



THURSDAY, OCTOBER 24, 1878 



THE CONSERVATION OF RIVERS 



'H'^HE question of the control of rivers has during the 

 -i- last two years occupied more attention than had 

 previously been bestowed upon it for a considerable 

 period. The disastrous floods in South Wales and other 

 parts of the country in the summer of 1875 caused a great 

 outcry at the time, and this had hardly been forgotten 

 when the evil recurred with still greater intensity, and in 

 some cases more damaging effects in the winter of 

 1876-77. The immense amount of damage caused by 

 floods in these two years, coupled with the fact that, in 

 the opinion of a great many, they occurred at more 

 frequent intervals than in former years, at length drew 

 the attention of Government to the subject. Conse- 

 quently in 1877 a Select Committee of the House of 

 Lords was appointed to inquire into the operation of 

 existing statutes in regard to the formation of, and pro- 

 ceedings by, Commissioners of Sewers, and Conservancy, 

 Drainage, and River Navigation Boards ; to consider by 

 what means they could be more inexpensively constituted 

 and their powers enlarged so as to provide more effi- 

 ciently for the storage of water and the prevention of 

 floods. At the same time two other committees of the 

 House of Commons were sitting on the same subject, but 

 with reference only to the River Thames, one dealing 

 with the question of the prevention of floods within the 

 metropolitan district and the other within the whole 

 valley of the Tham,es. A vast amount of information 

 was collected from the numerous witnesses examined by 

 these committees. Considerable difference of opinion 

 was, as might be expected, found to exist in respect of 

 the causes and best means of prevention of the severe 

 floods experienced of late years in our different river 

 basins, but by far the greater majority of the witnesses 

 agreed that the floods were, yearly getting worse than 

 formerly, that the river channels were getting into a 

 worse and worse state of neglect, and, what is a most 

 important point in the practical bearing of the ques- 

 tion, that the damage caused was so great that 

 the carrying out of extensive remedial measures could 

 in most instances be made to pay. It would ap- 

 pear at first sight a comparatively simple matter, given 

 the drainage area of the river basin, the intensity 

 and duration of the maximum observed rainfall, and 

 the hydraulic inclination of the river, to calculate the 

 sectional area of channel requisite for the maximum 

 discharge ; this is doubtless the case, but unfortunately in 

 the early history of the world the formation of rivers was 

 left entirely to the forces of nature without the profes- 

 sional assistance of a competent engineer. If an engineer 

 of suitable experience were called upon to design a river 

 from source to the sea, he could doubtless successfully 

 accomplish the work, but the problem the legislature is 

 now called upon to deal with is of far greater complexity. 

 Not only hare the rivers themselves been doing all 

 they could to make things difficult, meandering in 

 graceful curves through plains where they ought to have 

 gone in straight lines, and silting up where greater depth 

 of channel was necessary, but the inhabitants of the 

 Vol. XVIII. — No. 469 



country most interested have followed the same course 

 now for some centuries by constituting themselves under 

 Acts of Parliament into innumerable small drainage 

 boards with certain definite powers within their own 

 districts, but unable and unwilling to join together and 

 act for their general good. 



The Select Committee on the Prevention of Floods 

 within the I^Ietropolitan District had a comparatively 

 simple question to deal with. Accurate and long-con- 

 tinued observations on the levels of high water were 

 produced, showing the result of the various works of 

 improvement that have been carried out since it was 

 decided to remove old London Bridge. The tides 

 in the Thames are the resultant of two tidal waves, 

 one reaching the mouth of the river by the North 

 Sea, the other by the English Channel, the former 

 arriving at the river usually about three hours before 

 the latter. But certain conditions of the wind on some 

 occasions bring these two tidal waves together ; thus 

 a south-westerly gale accelerates the English Channel 

 wave and retards the North Sea wave, while again the 

 latter may be increased by a north-west wind off the 

 coast of Scotland blowing at the same time. The highest 

 tide on record in the Thames was that of November 15, 

 1875, which rose to the height of 4 feet 7 inches above 

 Trinity high-water, or 3 feet 2 inches above the predicted 

 height; that of January 2, 1877, exceeded the predicted 

 height by 3 feet 4 inches, and reached a height of 4 feet 

 above Trinity high-water. The conditions producing 

 these results were nearly the same : in the south a south- 

 westerly gale, in the north a north-westerly with an 

 easterly wind blowing up the Thames, combined with a 

 low barometric pressure over the river valley and con- 

 tinued heavy rains. Almost the worst possible concur- 

 rence of circumstances having on previous occasions 

 occurred, it will not be too much to predict their recur- 

 rence at some future time, and possibly with much more 

 disastrous effects ; for whereas the highest tide on record, 

 that on November 15, 1875, was only 3 feet 2 inches 

 above its calculated height, that of December 12, 1845, 

 rose to 5 feet 7 inches above its predicted height, show- 

 ing that a suitable concurrence of conditions might pro- 

 duce a tidal wave upwards of 2 feet at least above the 

 highest on record. In the face of these facts and the 

 repeated inundations of low-lying parts of the metropolis, 

 it is simply astounding that so little should be done not 

 only to obviate the recurrence of a well-known evil, but 

 to prevent a much worse one from happening. Bearing 

 in mind the great and costly works carried out by the 

 Metropolitan Board of Works in the main drainage of 

 London, the Thames embankments and the numerous 

 new streets, and, finally, also in their last great work of 

 buying up and freeing the bridges, it would appear a small 

 thing to raise the height of the river banks at the few places 

 necessary to prevent the periodical inundations ; but though 

 there is no difference of opinion as to the character and 

 extent of the works required, the Select Committee and 

 the Board do not seem to have agreed on the question of 

 how the improvements are to be paid for, and the matter 

 appears again to have gone to sleep. 



The general question of the control of the entire 

 river channels is one of much greater complexity than 

 the prevention of the periodic overflows of the Thames 



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