182 



THE FARMER'S MAGAZINE. 



FLOOD WATERS. 



BY CUTHBEKT "W. JOHNSON, ESQ., F.R.S. 



The copious rainfall of the present season, and 

 the repeated floods which they have occasioned, 

 revives, very naturally, the landholder's attention 

 to the imperfect state of our rivers, and other main 

 watercourses. The greatly diminished supply of 

 rain during the last two or three years, led many 

 persons to believe that our climate was becoming 

 drier, that our springs were thus rendered perma- 

 nently less copious, and that the water-line of our 

 wells, like that of the deep borings in London, 

 would become lower. By a reference, however, to 

 the rain records of the last twenty years, we learn, 

 that the recent fluctuations in our rainfall, and in 

 the flow of our flood waters, were neither very re- 

 markable nor unusual. Let us examine the rainfall 

 near London, since the year 1840, and let us 

 suppose, what is sufficiently near to the truth for 

 our purpose, that the annual rainfalls during that 

 period, above 25 inches, were wet, flood-producing 

 seasons, and that all below that depth of rain 

 were dry and pretty free from those injurious out- 

 pourings. Let us then place the rainfalls at 

 Chiswick, near London, in separate tables, viz., 

 those years above 25 inches, and those below that 

 depth of rain. The result we obtain is as fol- 

 lows : — 



ABOVE 25 INCHES. 



1841 



1843 

 1846 

 1848 



1842 

 1844 

 1845 

 1847 

 1849 

 1850 

 1851 



30.97 



25.48 



27.71 



28.34 



1852 32.55 



1859 25.54 



1860 to July 1, 

 about.... 15.74 



BELOW 25 INCHES. 



22.27 

 21.34 

 23.33 

 16.65 



22.84 

 18.28 

 20.79 



1853 

 1854 

 1855 

 1856 

 1857 

 1858 



24.37 

 18.92 

 24.38 

 22.72 

 21.06 

 15.78 



We see from these tables that since the year 

 1840 the rainfall has been during six years above 

 25 inches, and during thirteen years below that 

 depth. So that in fact, the larger rainfall, on 

 an average, occurs about every third year. (It 

 is noticeable that the rainfall this year, 1 860 to 

 July 1, has been about 15,74 inches, or about 

 equal to the whole rainfall of 1858.) 



If then such is the fact, that the greater rain- 

 falls, and the consequent larger floods, occur at 

 certain average intervals, it only remains for us to 

 consider whether the ill eff"ects of those flood 



waters are a necessary or unavoidable infliction 

 upon the lowland farmer. If, on enquiry, we 

 soon find that these flood waters would not natu- 

 fully cause the present amount of damage if their 

 course towards the sea was not impeded by artifi- 

 cial causes, then the next branch of the enquiry 

 which presents itself is, the best means of dimi- 

 nishing the evil. 



It is, perhaps, for the great mass of my readers 

 an unnecessary task for me to prove the existence 

 of the injury ; but for many it may be well to pro- 

 duce the evidence of two or three eminent practical 

 men on this nationally important subject. Let me 

 render this testimony, as much as possible, in 

 their own words. First then, as to the existence, 

 origin, and extent of the mischief to English 

 agriculture. 



" Our drainage arteries, large and small," obser- 

 ved Mr. A. Clarke, in his prize essay on trunk 

 drainage {Jour. R. A. S., vol. xv., p. 3), " might 

 possibly have fulfilled their office had they been 

 left to follow their native levels, or at any rate if 

 their current had been assisted by prudent art. 

 But a glance at the map will tell how they have 

 been used for other purposes, dammed into re- 

 servoirs, intercepted for canals, or lifted to gain a 

 water power for numberless mills, often appro- 

 priating the whole fall of the stream. Thence 

 comes the floods of our valleys — the rank, coarse 

 herbage of our meadows — the loss of our flocks — 

 the miasmata and fogs of our low grounds." 



Mr. W. Bryan Wood {Jour. R. A. S., vol. xiii., 

 p. 368) has given a summary of these obstructions. 

 They chiefly consist of abrupt turns and windings 

 of the course, shallows, islands, trees, and bushes 

 growing into the stream : bridges, which appear 

 to have been built only with regard to the passage 

 over, having low and narrow arches, and uselessly 

 large piers; and lastly, though not the least cause 

 of damage on many streams, are the mills. In 

 many instances a mill affects the drainage of much 

 land, sometimes hundreds of acres above it, and 

 does yearly more damage to such lands by pound- 

 ing the water, than its annual rent bears any cora- 

 parision to. Mr. Wood instances the Thames 

 Valley, in Gloucestershire, Berkshire, and Ox- 

 fordshire, and the Wiltshire Avon Valley, " There 

 are fields in my neighbourhood," says Mr, Pusey, 

 {ibid 370), " which have been covered with water 

 for months ; and in a foitner year, a large meadow 



