Theme 1 Rivers and Coasts case studies 2013

A. Cumbria floods Nov 2009, River Derwent, Cockermouth Page 86-91

Short term management Sustainable? Long term management Sustainable? £1 million cleanup and repairs Yes, houses were repaired for future

use but it does not prevent more floods

Locals improve the main street Yes it is helping the community in the future SEE.

Evacuated 50 people RNLI rescues people Yes it saved lives, but did not prevent future floods

Lottery money helps the local environment £500,000

Helping the community and the environment in the future.

Flood recovery fund set up £10 Million Yes it helped victims get back to normal. Does not prevent future floods

Flood action groups were set up to decide what should be done in the local areas

Community involvement is sustainable – they have a say in what happens

Temporary train station; footbridge; library and Tescos

No, they were temporary The River Derwent was dredged to increase the size of the channel.

Can damage habitats and will need to be repeated as the river deposits more sediment. Cheaper option than flood walls.

New flood windows were built in Keswick at a cost of £6 million

Very expensive and will need maintaining. Stops flooding & does not spoil views of the river.

Causes:

1. Relief rainfall – warm, moist air blows onto the land and is forced to rise over the hills, the air cools, condenses, forms clouds and it rains. Nearly 500mm fell in 34 hours. The discharge in the rivers increased and the rivers flooded. This was the main cause of the flooding. 2. Cockermouth is located at the confluence of the River Derwent and Cocker. Two full rivers met here – double the discharge. 3. There are steep mountains, so the rain ran over the surface without infiltrating, reducing the lagtime and increasing the discharge rapidly 4. The ground was saturated from a wet autumn, so the rain could not infiltrate and ran over the surface into the rivers. This is called antecedent rainfall. 5. The floodplain had been built on reducing infiltration and causing more surface run off.

Impacts:

39 schools were forced to close across the region; 1,200 people were left without electricity; telephone

lines down; more than 200 people rescued by boat and helicopter in Cockermouth – 1300 homes were

flooded & contaminated with sewage. They spent the night in emergency reception centres, at local

schools and leisure centres; 12 bridges were closed and four were destroyed; PC Bill Barker was killed

when Northside Bridge over the River Derwent in Workington collapsed; River Greta bursts its banks,

rising 1.5m. The town of Keswick was shut off and up to 250 homes were without power; Cockermouth,

at the confluence of the rivers Cocker and Derwent, suffered the worst flooding. Water was up to 2.5m in

places; the Ambulance Service, Cumbria Police, Mountain Rescue, The Lifeboat Institution, The RAF,

RSPCA and a civilian army of volunteers helped; many trees and branches were uprooted and dumped

where the waters had left them. Cars were overturned; furniture from the town’s restaurants was

overturned and lay discarded amongst smashed glass from dozens of broken windows. Many businesses

were ruined; average cost per hose was £28,000; insurance costs were £100 Million.

B. River Zambezi, 2009 Page 92-95

COUNTRY IMPACTS

Botswana 430 displaced, 8 villages submerged

Namibia 92 dead, 350,000 people affected, villages & medical services cut off, food prices rose by 37%, roads damaged, boy killed by Croc, hippo attacked man

Zambia 5,000 houses destroyed, $5 million of damage, 21 districts submerged, one cut off, 600,000 people affected

Angola 20 dead, 200,000 affected, 25,000 homes lost.

SHORT – state of emergency declared and the army helped;

charities raised funds to help; emergency aid was given – food,

medicines, tents & mosquito nets.

LONG – Zambezi River Basin Inititative run by the Red Cross

(helping 800,000 people; disaster prep, water supplies, disease

prevention.

Maphanda Nkuma Dam – dam costing $2.3 Billion, control the

flow of the Zambezi & provide HEP

Integrated Water Resource Management for Zambia – satellite

images and weather forecasting t give flood warning and map

flood risk areas.

C. River Derwent Page 77 A case study of one river valley and its landforms

UPPER COURSE – the source is in the mountains at Sty Head Tarn,

water collects here and flows into steams forming tributaries.

There are V shaped valleys, waterfalls & rapids in the upper stage.

There is vertical erosion and fast flowing turbulent water, The

channel is narrow, shallow, lots of angular sediment and steep

gradients. There is relief rainfall of up to 3,000 mm per year!

MIDDLE COURSE – The River Derwent flows into a lake, Derwent

Water and continues through Bassenthwaite Lake to the

confluence with the Greta. The river meanders and the floodplain

gets wider. The river begins to erode laterally. The channel is

wider, deeper, smaller sediment and lower gradients.

LOWER COURSE – the river has more

discharge as it approaches the Irish Sea. At

Workington the floodplain is large and wide

with big meanders. Where the river meets the

sea is an estuary which is tidal. This land was

used for industry and is now good for

shipping, chemicals and leisure. The river is

wide & deep and is slowing down as it meets

the sea. It carries lots of suspended sediment.

D. The Dorset Coast: Old Harry and Swanage Bay

HEADLAND & BAY

On the Dorset coast at Swanage there are different rock types that are resistant to erosion and

less resistant to erosion. The destructive waves have allowed headlands & bays to be formed

here as the rocks are perpendicular to the coastline- a discordant coast

Where the less resistant clay meets the sea at Swanage to sea has eroded a large bay using

Hydraulic action and corrosion processed, The material has been carried away by longshore

drift.

Where the hard rock is, the waves cannot erode so easily and headlands are formed sticking

out into the sea at Handfast Point and Peveril Point.

OLD HARRY’S ROCKS

Handfast Point is a headland that is made of

resistant chalk and sticks out into the sea.

The waves are refracted towards the headland

and erosion processes and weathering have

created distinctive landforms here – arches, caves,

stacks & stumps.

A crack in the chalk is eroded by hydraulic

pressure and corrosion and enlarges to form a

cave.

Further erosion causes the cave to break through

and make an arch. This will collapse forming a

Stack.

Physical, chemical & biological weathering along

with more erosion cause the stack to collapse

leaving a stump.

E. Poole Harbour & Studland Bay A case study of coastline management, including reasons for protection, measures taken, resulting effects and possible conflicts.

Location Description Advantages Disadvantages

STUDLAND Relocate

facilities;

Remove

gabions

Regenerate

sand dunes;

Limit

parking; No

cars or dogs

on beach;

5mph

speed limit

on water;

Ban jet skis;

Information

boards;

Tourist

facilities

near to car

parks

Removes

unsightly

gabions;

Allows

regeneration;

Maintains

conservation

area;

Preserves

rare habitats;

Informs

public;

Maintains

facilities

Upset jet

skiers; Damage

water based

tourism;

Unsightly

fences; Lack of

parking may

reduce

numbers of

tourists;

Tourist

facilities

moved

Location Description Advantages Disadvantages

POOLE BAY Five rock

groynes;

Improve cliff

drainage; beach

monitoring

programme

Maintains beaches;

Protects buildings; Less

water in the cliffs;

Monitoring will help in the

future

Unsightly groynes. ; Cost

£1.9 million for the

groynes.; Cost £3 million on

cliff drainage

Why does it need protection? Sea walls built in the past have stopped the supply of sand to the beach by stopping the erosion. This means the beaches need replenishing. Sandbanks is a spit with very expensive properties so it needs asn to protect it. It is low lying so sea level rise will be a concern in the future. The area relies upon tourism as its main industry & the beaches are why people visit – without them the local economy will suffer. Lots of stakeholders use the harbour – ferry company, sailors, wind surfers, national Trust, swimmers etc.

SUSTAINABLE? Local rocks are used Less fuel needed for transport Groynes provide a habitat Building in winter avoids peak season Dredging cuts the flood risk Dredging allows industries sea access Better beach means more tourists Ramps give access to disabled people Houses are protected

UNSUSTAINABLE? More tourism causes litter & crowding Increased dust Noise pollution More congestion Beach not in use Dredging affects habitats Eyesore – groynes. Energy used