How Did Our Medieval Ancestors Cope with Flooding?

It is about 30 years since the Thames Barrier was opened by Queen Elizabeth II on 8 May 1984. Costing nearly £500 million, it is one of the world's largest movable flood barriers, spanning 520 metres across the Thames. The disastrous tidal surge of 1953, which saw the loss of about 300 lives along England's east coast and within the Thames Estuary, acted as a catalyst for the search for long-term flood solutions. Since then, defence systems have remained on the agenda, no more so than in early 2014.

Although the construction of the Thames Barrier was a landmark in England's fight against rising sea levels, flood defence construction is nothing new. Surviving examples of medieval defences are relatively rare, but one of the best is a stretch of embankment at Botolph's Bridge, West Hythe in Kent.

Flood defences: always a priority

Initially, water defences were created as the first step in converting coastal salt marsh, inland fen and peat bog into farmland, rather than to protect existing settlements. This process of reclamation is thought to have begun in England as early as the 1st century AD.

The flood defence at Botolph's Bridge - a scheduled ancient monument - is situated at the edge of Romney Marsh and dates to the later Anglo-Saxon period (8th/9th century).

A curving earthwork 358 metres long, up to 20 metres wide and 0.5 metres high, it was probably constructed to protect the fertile agricultural land behind it from flood water. It is also believed that the original flood defence may have extended much further - in fact, for several kilometres along the River Rother (formerly known as the Limen).

Flood defences in the Middle Ages were such a priority in periods of severe weather that, just like today, their regular maintenance sometimes exhausted finances. For instance, in AD 1293-4, Canterbury Priory's bill for drainage and flood defences was more than £128, compared to their annual income of just over £74.

Fighting a losing battle?

Botolph's Bridge symbolises one historic solution to flooding - that is, building higher and stronger river walls. Increasing the height of these walls was a permanent, maintainable option, and medieval landowners clearly believed that vast embankments were worth the considerable cost.

Eventually, however, higher and wider flood defences became unpopular because they blocked views of coastline and rivers, so other solutions were sought. The movable Thames Barrier was considered a landmark in British flood construction, but some now believe it is inadequate for the long term.

Given the permeability of flood defences, it is remarkable that ancient monuments like the Botolph's Bridge defences still survive. This longevity and the evident influence of these structures on low-lying land today provide a vital insight into how our medieval ancestors tackled the ever-present problem of flooding.

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