At the time of writing on the evening of February 9th 2022 there are flood alerts issued again for the tidal River Yare, from Thorpe St Andrew to Breydon Water and the tidal River Waveney from Ellingham to Breydon Water. This area is of interest because the alert mentions a heightened risk at the Haddiscoe New Cut, which has its embankment reduced. Emergency repair work is currently being undertaken following the incident on January 30th when a Greater Anglia train was halted as a section of railway embankment was washed away.
A dramatic video from Greater Anglia news shows the severity of the damage to the track at Haddiscoe. What is interesting about the video is that the flood water appears to be gushing below the railway line in a massive breach underneath the track. The water also appears to be flowing from holes in the bank of the river underneath the vegetation presumably separating the track from the river. This could possibly be as a result of a process known as Dessicated Cracking, when flood water exploits cracks in riverbanks or flood defences to seep through to force slippages or breaches in clay earthen structures.
Flooding in this area is also of concern to Carlton Marshes nature reserve as on the same morning as the Haddiscoe incident, there was also a sizeable breach in flood defences at Carlton Marshes at the White Cast reedbed. The area of the reserve affected remains vulnerable to further breaches from high tides as it awaits repairs. At Carlton marshes, the inundation occurred at the end of a month of lower-than-average-rainfall. So on 30th January the flooding was the result of high tides and not heavy rainfall. This is of concern because certain habitats on coastal marshes are freshwater only, and a surge of tidal salt water can cause irreparable damage to wildlife reserves.
The new year has witnessed a series of high tides, the usual reasons including Spring Tides combined with heavy rainfall at the start of January and February and the effects of Storm Malik and Storm Corrie. However, flood warnings and alerts have been consistently and regularly issued, with coastal towns and villages experiencing flooding of town centres and coastal frontages with high waves testing the resilience of flood defences. One contributory factor to the flooding on the River Waveney concerns a process known as the natural tide locking effect. High tidal waters moving up the rivers from Great Yarmouth restrict drainage out to sea at low tide.
Future consideration of this discussion will look at the question whether recent events suggest a change in the behaviour of coastal tides. Whether the New Year winter flooding is simply a result of winter conditions or does it signify a departure in usual tide levels seen at this time of year.
alteredcoast 