50 YEAR OLD GABION STRUCTURE - RIVER HUMBER

For many years there had been severe erosion to the north  bank of the River Humber at Brough, which is some ten   miles to the west of Hull. Much of the land at Brough is   below the level of ordinary spring tides in the Humber, and   the agricultural land, together with the main railway line to   Hull, an aircraft factory, and a timber yard are protected by   an earthen flood embankment. Erosion continued and the   Hull and East Yorkshire River Board considered a number of   schemes. It eventually agreed that the remedial works   should comprise about 1000 yd. of half tide wall, and a   similar length of gabion revetment. 

A ‘half-tide’ gabion wall, 2m high on an 18m wide gabion  apron (0.5m thick). The volume of protection was   approximately 13,200 cu.m of PVC gabions, mesh 80 x   100— 2.7mm. 

The wall was started by dumping 200 ton loads of lump   chalk from a hopper barge at high water and it was   completed by running tipping lorries on to it at low water. 

The flexible nature of the gabion platform enabled it to   follow exactly the profile of the foreshore, and if erosion   continues the platform will be able to take up the new   profile. The main purpose of the gabion wall is to provide   sufficient weight to anchor the gabion platform. 

The PVC coated gabions, which are specially produced for   sea defence works, were used, and these were filled with   blast furnace slag. The work was completed in 1964, and so   far no maintenance work has been required on the gabions. The total cost of the works was £260,000. of which £188,   000 was for the half-tide wall and £72,000 for the gabion   platform and wall. 

The wall was built with its crest below the high water level to   allow over topping at high tide and silt to build up behind   the wall. The area behind the wall is now completely built up   and the area has become a natural haven for wildlife By   1993 silt had built up over the gabion apron, almost to the   crest and erosion has been completely halted.