Storm Pierrick Update
Spring high tides and storm surges have created extreme coastal conditions across our region in recent days.
In preparation for Storm Perrick on the 9th of April, floodboards were installed and seafront road gates were closed at many locations. Extra Coastal Incident Officers (CIOs) were also deployed to monitor, record and manage the situation.
Tide, wind, and surge conditions
Storm Perrick fell on a spring tide cycle when tides were higher than usual. The stormy conditions created an intense storm surge which meant the Environment Agency predicted tide levels increased.
At the peak of the overnight tide on the 9th of April some locations across our region experienced the highest levels of tides ever recorded.
The high tide reached 5.8m CD, which is the highest level recorded at the Class A Portsmouth tide gauge since deployment in the 1960s. Alongside the high spring tides, the area received significant wave heights of 2.1m and a spike in peak wave height of 4.4m one hour after high tide, measured from the National Network of Regional Monitoring Programme’s Hayling wave buoy. Crucially, the coast battering conditions were also created by swell waves which peaked at 16 seconds, one hour after high tide and a windspeed that was recorded at 45 kts in Chichester Harbour.
The combination of the extremely high spring tide, southerly winds and peak in wave height and swell waves coinciding, pushed coastal defences to the limit on the 9th of April. In isolated areas, it led to property and infrastructure flooding across the 246 km of coastline that we manage.
Current situation
The majority of flood alerts issued by the Environment Agency have now been removed or reduced. They have advised that although tides are still high, they are not being intensified by storm surges and so the risk of flooding has reduced.
Alongside our Partners, we will now carry out detailed inspections to ensure suitable measures are taken to consolidate sea defences.
For information on what to do after a flood please visit our Flood Protection page and UK Health Security Agency advice.
The future
The conditions experienced on the 9th of April broke records in many areas. Using Portsmouth as an example and Environment Agency sea level rise guidance, in approximately 70 years, with estimated sea level rise, the high tide experienced last night will become the ‘normal’ highest astronomical tide.
In approximately 100 years, the same high tide will become the ‘normal’ mean high water spring tide.