Boscastle Flood Defence Scheme

Described in guidebooks as ‘absurdly picturesque’, the village of Boscastle has for at least 150 years attracted significant tourist numbers, drawn in largely by the striking physical setting of the village. The lower village and harbour sits within an Area of Outstanding Natural Beauty, a Conservation Area and the lower valley is largely in National Trust ownership. Changing patterns of use and development over the centuries have created a complex, characteristically Cornish, port settlement.

In 2004 a catastrophic flood tore through the village destroying 5 buildings and damaging 47 others. Remarkably no life was lost. Following this disaster the challenge was to reshape and enhance Lower Boscastle’s flood protection, creating a safe environment that maintained the community’s sense of place and identity.

Nicholas Pearson Associates (NPA) was appointed as landscape architects to the project team to work with Halcrow Group Ltd to deliver a flood alleviation strategy in a way that was responsive to this sensitive and heavily protected landscape. A full Environmental Impact Assessment was undertaken with NPA providing concept design inputs, consideration of high level design alternatives and preparing a Landscape and Visual Impact Assessment of the preferred solution. The project team worked within a challenging brief defined jointly by the Environment Agency, North Cornwall District Council, the National Trust and the local community.

The design process consisted of three main steps:

1) Identification of the distinctive characteristics of Lower Boscastle: the village can be divided broadly into three character areas. Landscape strategies were devised for each character area. Achieving flood alleviation, landscape conservation and landscape enhancement together was the overarching priority.

2) Assessment of the flood damage on ‘micro’ scale landscape elements: the condition and value of physical elements that remained post flood were assessed in order to understand the damage caused and what items retained historical integrity. This phase drew upon earlier character studies, photographic evidence, discussions with local people and historic map studies. The assessment showed for example that the constrained river channel had been wider in places during the eighteenth century, and over time the channel had been in filled and riverside land had been built on to allow port activities to expand. The scheme allowed for the restoration of some lengths of bank to their earlier positions.

3) To review and tailor the engineering design options to the location: A significant element of the process was to define how much change could be tolerated by the protected landscape. This understanding of acceptable change influenced the development of design options. The most significant design interventions were directed towards those parts of the environment that had the greatest capacity to accommodate change or which would benefit most from enhancement whilst coping with flood flow predictions.

All proposals were evaluated in terms of their potential for beneficially influencing the overall sense of place in order to protect the historic integrity of the village.

The widening and deepening of the river channel, a key element in increasing the capacity of the river to handle flood flows was facilitated through the preparation of a river walling design guide that identified and retained surviving, authentic stone walls, defined vernacular wall styles and walling techniques to be used. It also guided the selection of appropriate materials, stone sizes and colours to avoid any possibility of losing the key sense of detail, variety and authenticity.

The main car park access was improved and the parking area was moved away from the river edge incorporating the design of over land flow routes and vehicle escape routes, reducing the risk of flooding and improving the riverside environment. This improved river habitat and increased biodiversity potential through the use of native planting, meadow restoration and hedge replacement has been established on reinforced embankments beside new riverside footpaths.

The final element of the project was to reconnect the east and west banks by the harbour with a new foot and vehicle bridge to replace the one washed away by the flood. Considering the potential future flood flows, the picturesque protected setting and significant stakeholder influence, a number of options were developed and tested through the preparation of photomontages. The favoured bridge design, now complete, appears on post cards of Boscastle and has been recognised for the quality of its design.