Costal Hazards and Management 🪸 Flashcards
Why are some communities vulnerable to flooding and erosion?
Geographical factors- magnitude, duration, predictability, and regularity
Human factors- development, wealth, education, age, population density, emergency services
How does climate change contribute to vulnerability of coastlines?
1) SEA LEVELS RISE 50-100 cm by 2100 => more coastal flooding!
2) warmer seas => storm surges
3) THEREFORE, Expensive sea defences will be required
LECZ AND SIDS MOST VUNERABLE
How does social and economic development affect vulnerability?
Talk about the UK and Nile Delta Egypt
UK- High income country, 20 million love within 10km of coastline. Whilst impacts could be devastating, some parts can invest, however, level of investment dependant on a cost benefit analysis
Nile Delta Egypt- 40 million inhabitants high pop density. Alexandria = poor infrastructure, poverty, protected by a sand belt => particularly vulnerable. Agriculture land, 1/3 of fish profit, tourism loss, salination, environmental refugees
Why are some areas geographically vulnerable (maladives)
LECZ- ie Maldives
They’re an LIC so little money to deal with effects. 87% dependant on rainwater, and loss of tourism since 2004 tsunami- can’t invest in sea defences
Solutions- JAPAN $60 million sea wall, artificial islands (city of hope) , Australia
UN- uninhabitable by 2100
Why is management of coastlines increasingly necessary?
RISING SEA LEVEL!!
1) homes and businesses need protecting
2) more frequent storm surges
3) natural habitats at HUGE risk
Give some hard engineering strategies, and state advantages and disadvantages.
• SEA WALL: reflect wave energy => wave reflected back on itself. Long life span, effective but massively expensive and can increase erosion of beach material.
• GROYNES: wooden barriers catching sed and preventing long shore drift. Larger beach = more wave e absorbed. Cheap and sustain, deprives beaches further down coast
• RIP RAP- massive boulders (Cornwall 🤪) cheap and efficient, but unsightly and stunted access.
Give some soft engineering strategies, with advantages and disadvantages.
• BEACH NOURISHMENT- beaches made higher and wider by importing sand and shingle. Relatively cheap and retains natural look of beach, but req regular replenishment and effects ecosystems
• sand dune stabilisation- dunes undisturbed = natural ecosystem, broadwalks = accessible to tourists, however expensive and management time consuming
• managed retreat- NEW INTERTIDAL ZONE CREATED => natural flooding and erosion. Maintains balance of ecosystem and encourages development of beaches and ecosystems. However, people loose homes and livelihoods
Express opinion on ‘hold the line’
Borth Ceredigion
Hold the line = existing defences maintained, popular with residents and tourists. IE- BORTH CEREDIGION. They chose hold the line bc managed retreat would flood the place in 10-15 years which would mean about £11 million properties lost, peat bog (Special area of conservation) lost. They put in four rock groynes, rock reef to encourage depo and beach nourishment. 18 million so far, successful
Give advantages and disadvantages of ‘managed retreat’
MEDMERRY
FAIRBOURNE
Managed retreat = residents moved out of danger zone and land left to nature. Less expensive but unpopular IE MEDMERRY SUSSEX- hole in sea wall to make more insland. Red flood risk, nature reserve, local economy. Cost 28 million but so far has protected 348 properties and maintained road. Cattle grazed in salt marsh= beef IE FAIRBOURNE, WALES- remove all sea defences. House prices plummet, businesses, community lost, issue back, train company
What is const benefit analysis? Why is it applied?
CBA= adding up benefits for course of action. Cost of managing should be less than the benefits of maintaining land, particularly in areas of high value.
App to-
• protect deserving coastlines
• protect natural habitats
What are the different shoreline management plans? What factors should be considered before action is taken?
Do nothing- allow erosion/floods. Low value land
Hold the line- hard engineering. Valuable land
Retreat the line- hole in existing defences. Allow land flood between high and low naturally. Sand dunes and salt mashes good barrier.
Advance the line- new defences further out. VERY HIGH value land
Factors: population, cost of re building roads, economic value, historical sites
Give an example of shoreline management plan
HOLDERNESS COAST
Holderness coast, Yorkshire
• highest erosion rate Europe => erode 2m a year
• fertile farmland, villages and road loss and tourism gone
• Holliday resort protected w/ grognes, sea wall and rip rap
• mappleton protected w/ groynes ( whole other issue tbh)
Whilst ur at it, u may as well explain the Mappleton stuff
• sea defences expensive asf for small village (2 million 1992) and depriving cowden and Aldborough of sediment- exposed, erode 6x faster, spurn point washing away
How does monitoring, hazard mapping and planning affect vulnerability?
>FFC
Monitoring- being able to predict
Mapping- what areas affected
Emergency services- response time
UK- Flood Forecasting Centre= flood forecasts and HAZARD MAPS- identify at risk areas and allow es to respond
Example of Hazard Mapping
