200 Modern Drainage Problems 



By 1934, this sum had been expended, and it became necessary to 

 prepare a supplementary scheme of ^103,000 to carry on the work. Early 

 work under both these schemes was mainly confined to dredging. The 

 dredged material was not of much use for embankment work, and for 

 this purpose the Board, following the practice of the Internal Boards, 

 obtained its clay from the Roswell Pits near Ely. Photographs of the pits 

 in 1913 show work being done by hand, but gradually operations have 

 been mechanised and fully organised. It has also been found economic to 

 open up subsidiary pits. As a general rule, the banks are heightened and 

 breasted or faced with clay to prevent them being washed away under 

 wave action caused by high winds on the flood waters. 



In floods prior to that of 1937, one bank at least had always broken. But 

 during the floods of March 1937 no breach of any consequence took place, 

 so that water levels in the streams rose higher than hitherto. The danger 

 is that these high-water levels create a head sufficient to force water under 

 the banks. It is therefore felt advisable to strengthen the banks, and future 

 work will carry the clay breasting down the front of a bank by trenching 

 on to the clay below. Previously, in weak places, this has been done by 

 hand; but now, with a new and more extensive programme, it is being 

 undertaken by trenching machines. 



The floods of 1936 and 1937 yielded much valuable data, from which it 

 has been possible to re-design the section for the main river from Littleport 

 to Denver, to which all the other rivers in the South Level are tributary. 

 This stretch is to be widened and some half a million yards will be 

 dredged away. It is calculated that this widening will reduce flood 

 conditions at Littleport, when the river is discharging, by a matter of 10 in. 

 This in turn will provide greater storage capacity for the periods when 

 Denver Sluice is closed by tidal waters.^ The cost of the scheme will 

 amount to ^266,000, and a 75 per cent grant has been obtained from the 

 Ministry. 



The Hundred Foot River and the Old Bedford River are also receiving 

 attention. The Middle Level Barrier Bank, which protects the Middle 

 Level area from the flood waters from the Uplands, was heightened under 

 a scheme completed in 1933. The Old Bedford River, too, is now being 

 improved ; and, consequent upon damage during the unprecedented flood 

 of I937> most of the Middle Level Barrier Bank is being protected with 

 clay at the cost of about ^^60,000. 



Denver Sluice was partially remodelled in 1923, when one large eye, 

 34 ft. in width, was installed instead of two smaller discharging sluices. 



' See p. 193 above. 



