88 TRANSACTIONS OF ROYAL SCOTTISH ARBORICUI.TURAL SOCIETY. 



"We cannot shut our eyes to the fact that in many cases our 

 rivers and our tributary streams are not only unable to take the 

 flood waters, but on the contrary their condition is frequently 

 the cause of the damming back of water on the lands adjoining. 



" We need not go far for examples. The River Thames, 

 flowing past our doors, now and again rises in flood, and 

 notwithstanding many improvements carried out by the Thames 

 Conservancy above Teddington, in dredging, renewing and 

 widening locks, weirs, and sluices, and in regulating the discharge 

 of flood water, still, at times, it overflows its banks and floods 

 large areas of land, streets and dwelling-houses, causing much 

 damage to produce, crops and property. 



" The Thames is by no means an exception. There are large 

 areas of land in the valleys of numerous other rivers in England, 

 Scotland and Ireland which in times of exceptional rainfall are 

 deeply flooded, causing in the aggregate enormous losses to 

 land-owners and their tenants. 



" The largest agricultural areas subject to floods are on the 

 east side of England, and are included in the valleys of the 

 Waveney, the Bure, and the Yare, all discharging into the sea 

 through the narrow channel of the Yare at Yarmouth, and in the 

 valleys of the Great Ouse, the Nene, the Welland, and the 

 Witham, flowing into the Wash through separate channels. 



" In many cases measures for improvement would meet with 

 difficulties, and the works might be costly, but in not a few 

 instances a quick return might be expected, while in others the 

 improved value over a period of, say, 25 or 30 years would be 

 sufficient to redeem the capital expenditure. 



" It is not, however, always the case that in the valleys of 

 rivers with the least fall or the most sluggish flow the greatest 

 damage occurs. As an illustration of this fact I may refer to the 

 River Spey. 



" The Spey is credited with having the most rapid flow of any 

 river in this country. It is about 100 miles in length and has a 

 fall of 1 145 feet, or a rate on the average of nearly 12 feet to the 

 mile. The river flows in a north-easterly direction, and takes a 

 sinuous course through a wide and fertile valley, sheltered for 

 the most part by high mountain ranges on each side. Needless 

 to say, on the mountains on each side forming the gathering- 

 area the rainfall is heavy, and is intensified at times by melting 

 snow. Hence the river is subject to sudden and violent floods. 



