In areas vulnerable to flooding and coastal erosion, increasingly as a result of climate change, tidal lagoons can act as a barrier to potentially damaging and disruptive storm surges and waves that threaten coastal communities and infrastructure. Here’s why:
Tidal lagoons can be designed to withstand 1 in 500 year storm surges and waves
This has been proven by our series of two-dimensional physical model tests at HR Wallingford in Oxfordshire; one of the leading providers of analysis, advice and support for engineering and environmental hydraulics and the management of water.
We examined the stability of rock armour under various design conditions with different combinations of water levels and wave heights, including wave overtopping and sea level rises resulting from climate change. The impact of storm waters was also measured to ensure that the final design structure is optimised for long-term stability and safety.
Even in 1 in 500 year storm events, the integrity of our design was not compromised, with only minimal damage to the structure, repairable in situ.
Tidal lagoons are designed for future increases in sea level
With an asset life of 120 years, it is necessary to ‘future-proof’ our developments. This includes an allowance in our designs for predicted sea level rise (which varies by location). If further adaptation to sea level rise is required, we could further increase the height of the bund wall structure. Therefore, as increasing sea levels threaten the coast, tidal lagoons could help coastal communities adapt and be more resilient to climate change.
Private capital investment in tidal lagoons may displace public spending on flood and coastal risk management
The roll-out of tidal lagoons in appropriate locations around the UK can be financed privately. It is reasonable to assume that some of this investment could help avoid expensive emergency responses to storms and floods, and reduce required spending from the public purse on ongoing flood and coastal risk management. Tidal Lagoon Power has commissioned independent studies in this area, in both North and South Wales, the early results of which indicate that a large tidal lagoon may save hundreds of millions of pounds through enhanced flood protection.
The flexibility in the operating cycle of a tidal lagoon may enable weather events to be better managed
Ordinarily, the 24 hour operating cycle of a tidal lagoon will be optimised for power generation and minimal environmental impacts.
During incidence of flooding, it may be possible to manage the operating cycle of a tidal lagoon so that the structure holds back the sea on peak spring tides, creating a short-term temporary reservoir to help with drainage of low-lying areas, as well as creating a steeper gradient to encourage run-off from the land and rivers in the area behind the lagoon. Should there be demand for a tidal lagoon to operate in this way, this would need to be examined in detail.