castle on the coast that gets flooded yearly

A 3 m (10 ft) wave, believed to have been triggered by water pooling behind debris caught under a bridge and then being suddenly released as the bridge collapsed, surged down the main road.

The torrential rain led to a 2 m (7 ft) rise in river levels in one hour. The cause of the very heavy localised rain is thought to be an extreme example of what has become known as the Brown Willy effect. The rain was very localised: Otterham and Lesnewth, both a few miles inland from Boscastle, recorded 24 hour totals of 200 mm and 185 mm respectively on the day, whereas four of the nearest 10 rain gauges showed less than 3 mm of rain in the same period. In Boscastle, 89 millimetres (3.5 in) of rain was recorded in 60 minutes.

At the peak of the downpour, at about 15:40 GMT, 24.1mm of rain (almost one inch) was recorded as falling in just 15 minutes at Lesnewth, 2.5 miles (4 km) up the valley from Boscastle. 185 mm (7 inches) of rain fell over the high ground just inland of Boscastle. With convergence and coalescence, enhanced moisture levels resulted in heavy rainfall on the afternoon of 16 August 2004. Upon contact with the topographically vertical coast, these winds experienced a strong up-drafting force thus causing internal moisture to reach the atmosphere, and consequently cool as a string of storm clouds. On the 16th, warm air picking up moisture – due to residual heat from the Atlantic Ocean – travelled towards the South West Cornish coast as prevailing winds. Coincidentally, this was 52 years to the day before Boscastle's 2004 flood. On 16 August 1952 the small town of Lynmouth, 50 miles (80 km) north-east along the north coast in Devon near Exmoor, suffered extensive damage in a catastrophic flood, in which 34 people lost their lives. The last time Boscastle had suffered notable flooding was in 1996 as a result of Hurricane Lili, but floods are recorded in 1847, 1957, on 3 June 1958 (one man drowned) and on 6 February during the Winter of 1962–63 in the United Kingdom. At midday on 16 August 2004, heavy thundery showers had developed across the South West due to a weak disturbance to the northeast of the United Kingdom. The probability each year of the heaviest three-hour rainfall is about 1 in 1300 (although rainfall probability is not the same as flood probability). The annual chance of this (or a greater) flood in any one year is about 1 in 400. The peak flow was about 140 m 3/s, between 5:00 pm and 6:00 pm BST. A study commissioned by the Environment Agency from hydraulics consulting firm HR Wallingford concluded that it was among the most extreme ever experienced in Britain. The floods were the worst in local memory. The flood in Boscastle was filmed and extensively reported but the floods in Crackington Haven and Rocky Valley were not mentioned beyond the local news. The villages suffered extensive damage after flash floods caused by an exceptional amount of rain that fell over eight hours that afternoon. The 2004 Boscastle flood ( Cornish: An Lanwes Kastel Boterel 2004) occurred on Monday, 16 August 2004 in the two villages of Boscastle and Crackington Haven in Cornwall, England, United Kingdom.

Looking upstream from the bridge after the flood

Castle on the coast that gets flooded yearly