Hydrology and fluvial geomorphology (case studies) Flashcards
Keswick: How much rainfall occured in December 2015?
517.6mm record rainfall in December in Keswick, double the average December rainfall
Keswick: Meteorological conditions in December 2015
- December 2015 was the wettest month on record
- December followed a particularly wet november
Keswick: When was the date range in December when new 24hr and 48hr rainfall records were set?
Between the 4th and the 7th of December. The previous records were also set within Cumbria
Keswick: Why was a wet November problematic?
Because much of the soil was already saturated by December, meaning there was less capacity for infiltration and the River Greta would be more likely to exceed bankful capacity
Keswick: What was the name of the storm that occured?
Storm Desmond
Keswick: Causes- drainage basin layout
(not geology)
- The River Greta flows through Keswick and is fed by the River Glenderamackin, and St. Johns Beck.
- There is a high drainage basin density and many smaller tributaries that feed into the river
Keswick: Causes- Geology
- The Northern part of the drainage basin is mostly made up of sedimentary rocks such as sandstone, mudstone and siltstone. They are permeable and porous mostly so allow for infiltration
- However, the Southern part has impermable igneous intrusions, and despite some faults they are mostly impermeable.
- This encourages overland flow and decreases infiltration/percolation
Keswick: Impacts - How many people were affected across which regions?
- An estimated 14,694 people in total were affected
- This is in the regions of Allerdale, Carlisle, Eden and South Lakeland
Keswick: Impacts - What is noticeable about how Carlisle was impacted?
- In Carlisle 30% of the most deprived areas were directly affected
- 22.5% of fading owner occupied terraces (financially stretched category) were affected by the flooding in the Carlisle area.
Keswick: Impacts - How much of the damage to highways was classed as “significant”
56% of the 354.8km of affected highway was classed to be “significantly damaged”
Keswick: Impacts - How much was paid out from Community Foundation flood appeal?
£3.86 million, with the majority of this being for flood defences
Keswick: Defences - When was the “Flood Risk Management scheme” put into place?
In 2011/2012
Keswick: Defences- As part of the FRMS what was put into place on Penrith Road?
(Did it work in ‘15?)
- A Stone-clad concrete defence wall and flood gate was implemented
- This proved ineffective in coping with the 2015 floods as the Penrith Road area became inundated with water and cut off this crucial access route
Keswick: Defences - name all the hard engineering solutions of the FRMS
(Spoiler: 2015 floods overpowered all of them)
- Penrith road concrete flood defence wall
- Drainage holes
- Stone clad reinforced concrete wall with glass panels to retain visibility of the river at High Hill
The government has tasked the environmental agency with delivering (WHAT AMOUNT) in flood defences across the UK since 2015?
After the flood of 2015, the government has allocated £2.6 Billion to the Environmental Agency to distribute across the UK.
Keswick: How many homes and businesses were flooded?
730
Keswick: What recent target has been exceeded by the environmental agency?
It has exceeded its target of protecting 300,000 homes across the UK from flooding, with thousands of these homes being in Cumbria
Keswick: How much has the Carlisle Flood Risk Management Scheme cost?
£25 million
Keswick: How many properties will be protected by the Carlisle Flood Risk Management scheme?
1,200 homes and 106 businesses
Keswick: How will the Carlisle Flood Risk Management Scheme protect residents and businesses?
- By raising and extending flood walls
- Improving the flow of water through Botcherby Bridge to allow a greater volume of water to pass through during a flood.
Keswick: Evaluating short term responses - how was communication with residents during the event?
- The Environment Agency contacted KFAG (Keswick flood action group) to raise awareness
- The Environment Agency also sent messages to stakeholders via the Cumbria Community Messaging (CCM) system
Keswick: How many survey respondents said they heard about the “flood fund” for financial assistance after the flood in good time?
80% of those who’s property was damaged
Keswick: How many applicants to the flood fund recieved all the money they applied for?
76% of applicants
Keswick: Evaluating short term responses- what action was taken to help those immediately affected?
Government help + Local people help
- 200 military personnel
- 50 high volume pumps
- A chinook helicopter deployed
- £400,000 donated by the public within 48 hours
Keswick - Why was Storm Desmond so severe?
An “atmospheric river” bringing moist air from the Carribean to Britain and an area of low pressure
EXAMPLE: Deltas
The Nile delta - arcuate delta
The Tiber delta (Tyrrhenian sea) - Cuspate delta
The Mississippi delta - birds foot delta
Keswick: How many sheep are there and why is this a problem?
- There are 50,000 sheep in Keswick
- These sheep trample the land and compact the soil, closing gaps within the soil which would have aided with infiltration
Keswick: Land use types
- Largely pastoral land, the herdwick sheep species is particularly prevalent
- In Keswick the tourism industry is key and this urbanisation has also impacted in infiltration
Keswick: Short term responses to reduce further flood damage
Actions taken by Local government in the short term.
- 4th December: Closed 3 floodgates and inspected watercourse structures for any blockages
- 5th December: Supplied a community pump to try and return flooding on Penrith Road back to the river
- The EA started emergency works to remove 25,000 tonnes of gravel from the river Greta to increase channel capacity
- Used the Cumbria Comunity Messaging system and worked with the KFAG to communicate with those at risk
Keswick: how much did the glass panelled defence wall at High Hill cost and when was it installed?
- Cost £6 million
- Installed after the severe floods of 2009
What were the environmental impacts of Storm Desmond/keswick flooding?
- In Cumbria, Desmond + flooding caused £185k of damage to forestry assets
- South Lakeland also experienced landslides and river erosion at Kirkby Lonsdale
- Some Mature parkland trees were lost
-
Leaking fuel tanks, mainly
heating oil, were reported in the Eden district, and an oil spillage at Mintsfeet,
Keswick: Reservoir use
- Hard engineering method
- Thirlmere reservoir managed by United Utilities was designed to hold excess precipitation,
- 14,000 megalitres (millions of litres) entered the reservoir on 5th of December alone, and this could be argued to have prevented some of the flooding
What were the Hard Engineering solutions attempted in Keswick?
- Therlmere resevoir
- Stone clad concrete flood wall in Penrith lane
- Glass panneled defence wall in High Hill
- Improving the flow of water through Botcherby Bridge
What were the soft engineering solutions attempted in keswick?
-Floodplain zonation south of Keswick where land use is largely parkland and caravan sites
How much was needed to restore roads and paths post 2015?
£7.9 million in restoration of roads and path
