Carbon And Water: Eden Basin Flashcards
Location
North-west England, between the mountatins of Lake District and the Pennines.
Description
River drains the north-east Lake District fells and north-west Pennines. It flows through Appleby-in-Westmorland and Carlisle. It’s mouth is in the Solway Firth at the Scottish Border.
It’s largely rural, though it does flow through the city of Carlisle. The upland areas that drain into the River Eden experience extreme weather that can cause flooding downstream. Carlisle is particularly vulnerable as its at the confluence of 3 rivers and is fairly low-lying.
Water cycle
Rainfall is higher than national average due to the relief of the area. The mountainous terrain encourages orographic rainfall. This means lots of water enters the river channels.
The Basin is long and relatively narrow, increasing lag time.
The slopes within the basin are steep, reducing lag time and increasing peak discharge.
The basin is made up of igneous, impermeable rocks at the highest ground to the west of the basin.
Much of the basin is made up of limestone and sandstone, which are permeable. Infiltration is quick and there is little surface run off, increasing lag time. Amount of water in ground stores increases.
Farming
More intense farming compacted the soil e.g. livestock and heavy machinery. Between 2000 and 2009, 30% increase in cattle, meaning compaction has increased. This reduces infiltration rates, so surface runoff is higher, meaning water levels in rivers rise quickly during heavy rainfall, increasing risk of flooding.
Grazing in upland areas has also reduced the amount of vegetation that can intercept rainfall, resulting in more water reaching rivers.
Construction
Urban areas increased. New housing estates built in and around Carlisle in recent years, e.g. the Eden Gate development, with 10,000 new homes.
Urban surfaces tend to be impermeable, reducing infiltration rates and increasing the size and speed of surface runoff.
Some developments built on floodplains, creating a flood risk to property, requiring construction of flood defences to protect homes. This can cause flooding downstream as water that would naturally infiltrate on floodplaims flow downstream instead
deforestation
Talken place in the basin for thousands of years for timber and land for farming. Much of the original forest cover has been removed. Trees increase infiltration and decrease runoff, so fewer trees means more runoff, flashier flood hydrographs and a greater risk of flooding.
Climate change
Change rainfall patterns in UL e.g. western UK could get up to 35% more winter rainfall by 2080. This would increase runoff and flood risk.
Storm Desmond
December 2015, caused devestating flooding in Cumbria. Some of the worst flooding occured in the Eden Basin.
In some areas, there was record rainfall of 262.6mm in 48 hours, nearly 50mm more than average rainfall for the whole of December.
More than 2000 properties flooded in Carlisle alone, leaving many homeless.
