The River Brue, Somerset

where the river brue located

• somerset

• runs from its source at brewham, close to the dorset border to its mouth at highbridge burnham on sea

• at its mouth it enters the bristol channel

• runs west for 61km, total fall of 126m

• runs across somerset levels which are composed of moores and low lying wetland

• also supplies an extensive drainage network across the levels.

What is the history of the river brue?

• route has been altered by humans between glastonbury and the sea.

• new channel was constructed between 1230 and 1250

• at the same time extensive drainage system was implemented consisting of rhines

  • to mitigate flooding and improve agricultural activity

• 1833 was a port at highbridge for coal and brick exports that closed 1949

What are the physical causes for flooding on the river brue?

• low lying area

• soil composition

• precipitation

What are the human causes of flooding on the river brue?

• agriculture

• climate change

low lying area as a cause of flooding…

• generally marshed 3-4m above sea level (15% at or below)

• the Bristol channel tidal range is 12-14m, making it the 2nd largest tidal range in the world

• this means likelihood of tidal surges is high and the narrow estuary mouth an exacerbate effects, and causing a faster river level rise (flashier flooding)

soil composition as a cause of flooding…

peatlands are common around the river brue influencing the hydrological cycle greatly

although being an effective flood buffer, peat digging is common in somerset for the use of compost (some compost up to 70% peat)

removal of this water store leaves the land that is left behind vulnerable

government failed to meet 90% reduction of peat digging by 2010

takes thousands of years to form so is not readily available

what is peat?

partially made up od decomposed plant matter that due to lack of oxygen under water has mixed with soil

peat has a high water holding capacity acting as a sponge which can help during flooding along with its low permeability meaning it can store large volumes for a long time

precipitation as a cause of flooding…

the catchment area of the river receives a significant amount of rainfall, especially in wetter months.

intense or prolonged rainfall events can lead to rapid runoff into the river causing levels to rise

eg 2013/14 floods were caused by 350mm rainfall in january and feb.

100mm above average

agriculture as a cause of flooding…

drainage infrastructure (eg rhines) have been developed to lower water tables for agricultural activities. however can increase runoff into rivers and watercourses due to a change in soil moisture. (change in the water table). this is due to the compaction of the soil reducing infiltration

historically large areas of the levels were wetlands and peatlands which was an effective water store, but drainage of large proportions of it has occured for agriculture eg dairy farming

selwood forest was deforested in the 17th cent to be sold for farmland

climate change as a cause of flooding…

a global issue that is worsened by human causes, putting the river brue and surrounding areas a a greater risk of increasing floods

• increases in temperature have coincided with an increases in severe weather events (rainfall)

• rising sea levels already are posing a large risk

• by 2080 at the current rates flooding in england will have doubled

What have been the historical flood management methods around the river brue?

land drainage

• historically has been a fundamental aspect of flood management, involving drainage channels, ditches and rhines. this method spans back to the roman period

drainage boards

• in 17th and 18th cent drainage boards were established to oversea management of drainage infrastructure in the region

community efforts

• maintaining flood defences and responding to flood events

• creates a sense of community cohesion and resilience among

What are the modern day management methods of the river brue?

• investment in flood defences (2008-2018 £45 million was invested)

• dredging and chanel maintenance = after 13/14 floods had some cause due to lack of dredging for 20 years prior, there was more emphasis on removal of clogging material and sediment in waterways

• natural flood management = increasing interest in natural methods such as tree planting, leaky dams and wetland restoration funded by the somerset rivers authority. these decrease flood risk and increase water quality