The Eden Basin Flashcards
Where is the Eden Basin located?
The Eden drainage basin is in north west England, between the mountains of the Lake District and the Pennines. The river drains the north east Lake District fells and the north west Pennines.
Where is the River Eden’s source and mouth located?
The River Eden’s source is in the Pennine hills in south Cumbria. It flows north west through Appleby in Westmorland and Carlisle. It’s mouth is in the Solway Firth at the Scottish border.
Why is Carlisle vulnerable to flooding?
Carlisle is particularly vulnerable to flooding as its at a confluence of the Eden, Petteril and Caldew rivers, and is fairly low lying.
Why is rainfall higher than the national average in the basin?
Because of the relief of the area - the mountainous terrain encourages orographic rainfall. High rainfall means lots of water enters the river channels.
What are the slopes like within the basin?
They are steep which reduced lag time and increases peak discharge.
What type of rock is found at the highest ground of the basin?
The highest ground, to the west of the basin, is made of igneous rocks, which are impermeable. Infiltration is very slow and surface runoff is high in these areas, reducing lag time.
What is the main rocks that the majority of the basin is made up of?
Much of the basin, however is made up of limestone and sandstone, which are permeable. When precipitation falls in these areas, infiltration is quick and there is little surface runoff, increasing lag time. The amount of water in ground stores increases.
How has farming affected the drainage basin’s water cycle and increased flood risk?
More intense farming has caused soils to become compacted, e.g. by heavy machinery or trampling by livestock. Between 2000 and 2009, there was a 30% increase in the number of cattle in the Eden Valley, meaning that much more land is likely to have been trampled.
Compaction of soils reduces infiltration, so surface runoff is higher. This means water levels in rivers rise quickly during heavy rainfall, increasing the risk of flooding.
Grazing in upland areas, e.g. hill farming of sheep, has also reduced the amount of vegetation that can intercept rainfall, resulting in more water reaching rivers.
How has construction affected the drainage basin’s water cycle and increased flood risk?
Although the majority of the Eden Basin is rural, built areas have increased. Many new housing estates have been built in and around Carlisle in recent years, e.g. the Eden Gate development to the north of the city, and where are plans to develop to a huge ‘garden village’ to the south of the city, including 100,000 new homes.
Surfaces in built up areas tend to be impermeable, which reduced the size of infiltration flows and greatly increased the size and speed or surface runoff flows.
Some new developments, particularly near Carlisle, have been built on floodplains. This has created a flood risk to property and has required the construction of flood defences to protect homes. Building on floodplains can cause flooding downstream as water that would naturally infiltrate on the floodplains flows downstream instead.
How has deforestation affected the drainage basin’s water cycle and increased flood risk?
Deforestation has taken place in the basin for thousands of years e.g. to provide timber, and land for farming. Much of the original forest cover in the Eden Basin has now been removed, giving way to large areas of open grassland and heathland.
Trees increase infiltration and decrease runoff, so fewer trees means more runoff, flashier flood hydrographs and a greater risk of flooding.
When did Storm Desmond hit?
In December 2015, Storm Desmond caused devastating flooding in Cumbria. Some of the worst floods occurred in the Eden Basin.
How many properties were affected in Carlisle?
2000 properties were flooded in Carlisle alone.
