Floods
Exmoor is well known for its flood disaster of 1952, to which has been devoted several pages of its own. However, as is only to be expected of an area of high rainfall, flooding has been a frequent occurrence. Improved drainage of farmland and more extreme rainfall events in winter have led to a greater likelihood of flooding in recent years. However, this has been coupled with flood relief schemes and the effects of flooding are not as evident as they were.
One village that was once regularly flooded before a relief works were constructed was Roadwater. Before the 1960s it was not uncommon to see people rowing down the main street in winter. The Roadwater Inn and village bakery were often flooded and lost trade as a result. Protests from the owners were so frequent that they fell on deaf ears after a while. There was a particularly bad flood in 1931. The Valiant Soldier Inn was flooded but customers were so accustomed to flooding that they just stood in the bar in their wellingtons. Most people in Roadwater had sandbags at the ready but some said that it was better to open their doors and let the flood through as the silt was less likely to build up that way. The last big floods at Roadwater were in 1955 and 1960.
The 1960 flood also affected Bossington, Dunster, Washford, Williton and Exford. Particularly badly affected was Porlock, where the Hawkcombe stream caused much damage. The flood at Bossington was the third in a fortnight. Dunster now has a flood relief scheme. A large channel takes overspill flood waters from the Avill at Dunster lawns straight to the sea at Dunster Beach and away from housing estates at Marsh Street, through which the river continues its original course. In a scheme at Dulverton, finished in 1987, the River Barle is prevented from spilling over onto its flood plain by raised banks. At the same time the culvert carrying the Hollam Brook under Dulverton's main street has been enlarged.
Avill flood relief channel at Dunster Beach
There are many records of floods on Exmoor and it is difficult to make comparisons with floods from more than a century ago because of the lack of rainfall and river flow measurements. There are records of flooding on the River Exe going back to 1250. Exmoor was very isolated at the time and the old records tend to be from further down the Exe, at Tiverton and Exeter. There are records of destructive floods from every century since the 13th century. There was a particularly bad flood in 1625 that caused devastation along the whole course of the river. The best known floods at Exeter in recent years were in 1960, when there was devastation both in October and December. Some say that the Lynmouth flood of 6th or 7th August 1770 must have been caused by greater rainfall than the one in August 1952. The damage was not as great but the course of the river was in no way restricted as it was in 1952. Incidentally, the date of this flood is often erroneously given as 1769 or 1796. The 1952 flood was not a record in terms of rainfall for Britain. In fact it was the fifth highest recorded rainfall in 24 hours. The seventh highest record, with just 12mm less rain, was at Timberscombe in June 1917. This must have caused severe flooding but there is little mention of it.
Drought
Drought on Exmoor is usually caused by high-pressure systems. These are known as “blocking highs” because they get stuck in one area and wet depressions coming in off the Atlantic are diverted around them. If it is dry on Exmoor it can be wet in the Mediterranean or Scandinavia. This can happen at any time of the year but more often in summer. January 2006, however, was particularly dry, with Exmoor having only 60% of its usual rainfall. Two dry winters in succession cropped up in the late 1800s and early 1900s, as well as 1933-34. Now winters are tending to become wetter but, as summers are becoming drier, any drop in winter rain is taken seriously as it is this rain that is relied upon to top up the reservoirs. Exmoor does not generally suffer from drought but as areas to the east suffer more and more from drought there is always a fear of new reservoirs being constructed on Exmoor. Exmoor itself receives little water from its largest reservoir, Wimbleball. Much of this goes to central Somerset, Tiverton, Exeter, east Devon and Torbay. Three times since the first water came over the dam in 1980 has the water level in the lake dropped significantly, drying up the arms of the lake (there were severe droughts in 1984, 1990 and 2003). Now there is a pumped storage scheme whereby water is extracted from the River Exe and pumped back through an 800 metre long tunnel to the lake when necessary. Despite this, at the end of 2003 the reservoir dropped to just over 30% of its capacity following the longest dry spell since 1921.
Dry bed of Wimbleball Lake in 1995
The droughts of 1921, 1933-34, 1959, 1975-1976, 1984, 1989-90 were considered to be major droughts of national significance. Whenever drought is mentioned, the long, hot summer of 1976 is often quoted. Exmoor suffered from that drought like much of Britain, but the effects were most severe in southern England and particularly in the West Country. The drought was not just about a long hot Summer, it was the culmination of a prolonged period of meagre rainfall. A hot, dry summer in 1975 was followed by a parched winter and spring. No rain fell in parts of Cornwall during April and in parts of Devon in June. Strong heat set in on the 23rd June and for 14 consecutive days the temperature topped 32°C in southern England, a record for modern times.The longest run of days with no measurable rain was 45 at Milton Abbas, Dorset and Teignmouth, Devon.The drought and great heat combined to provide the ideal conditions for the propagation of heath and forest fires and some proved devastating. There were many fires on Exmoor and the National Park Wardens, as they were then called, spent much of the summer firewatching. A fire on the sea cliffs at Trentishoe proved particularly difficult to deal with because access was so remote and dangerous. The peak of the drought coincided with the holiday season and much of the south west of Britain could not cope with the increased demand for water. A Drought Act was passed and standpipes were in use in Devon. Throughout Britain people became adept in saving water. It was not until October that any substantial rain set in. South West Water's three largest reservoirs, including Wimbleball, have been built since 1976, quadrupling the water storage capacity that was available during that drought.