MSc ECE student Lia Bennet reports on Lauren Burt’s seminar on the past, present and future of Hurst Spit:
On the 7th December Lauren Burt, part of the New Forest District Council’s Coastal Team and an alumna of the MSc ECE, gave a presentation on the past, present and future management of Hurst spit. This is an eroding gravel barrier beach at the east end of Christchurch Bay which is in the formation of a spit, providing protection for the low-lying land of west Solent and has experienced much human intervention in the past to maintain it.
Erosion over the years has caused the spit to migrate in a north easterly direction due to over washing and long-shore transport, with movement of over 100 m in places over just 70 years. Frequent storms which result in over-topping are experienced here such as those in the 1980s and early 1990s, which narrowed the crest to only 3 m in places. There have therefore been many attempts to stabilise Hurst Spit, such as in 1996/97 when 300,000 m3 of off-shore shingle was used to raise the crest by 7 m and a rock breakwater was inputted for stabilisation.
Details of past management plans for Hurst Spit were given, which are funded by the Environmental Agency. Beach recycling has been carried out frequently, where accumulated sediment at North point is placed back along the spit to insure it is of a suitable length and width. However, this source can be seen to be declining. The high magnitude storms of 2013/14 resulted in severe damage to the spit and a loss of 55,081 m3 of sediment, so subsequent reprofiling was carried out- resulting in a slightly altered alignment. Due to fear of breaching if another storm of this magnitude occurs, the area is in need of another major recharge such as that in 1996 to protect its amenity value and vital saltmarsh. Without such management, the life of the spit is predicted at roughly only 20 years. Therefore, future projects must be sustainable in order to protect the land from sea level rise in an affordable way which works with natural processes.
Lauren then discussed the ongoing research being carried out at Hurst Spit. She showed that by using aerial photography, digitised vegetated areas of the spit could be analysed to show areas which are experiencing the most severe erosion as well as the recovery time of vegetation post-storm. A tracer study is currently underway, where GPS is used to track the dispersal and location of sediment to define the volume of loss. Furthermore, the possibility of loading onto the saltmarsh landward of the spit was discussed to increase its width. This would result in consolidation of sediment on the rear of the spit, a process which would generally occur naturally as the barrier retreats with sea level rise.