3.1.4 Management of Coastal Environments

Question 1

What are the three aims of management?

Answer 1

• Protect from erosion
• Protect from flooding
• Conserve ecosystems

Must consider sustainability - environmental - pollution and aesthetic, economic - communities maintain living standards and social - maintaining communities

Question 2

What are shoreline management plans?

Answer 2

Drawn up for every coastline based on sediment cells so the future impact is considered. Mainly used to define the flooding and erosional risks to people and natural environment over the next century, identifying the impacts of those policies, to inform planners of the risk, highlight where knowledge is lacking, provide action plans for the SMP

Question 3

What are the options for coastal management?

Answer 3

Hold the line - maintain current defences
Advance the line - build new defences onshore
No intervention

Question 4

What are the general issues and benefits of coastal management?

Answer 4

Costs - expensive, maintenance, increased erosion down drift, reduced access, reduced recreation, smaller beach, disrupt environment, ugly, disrupts natural processes.

Benefits - protects infrastructure, land, land prices, peace of mind, employment

Question 5

What are sea walls?

Answer 5

Vertical sea walls - solid concrete walls, withstand severe wave action, maintains line of coastline, prevents erosion, resists exposure and safe for the public.

However expensive, high maintenance, waves deflected downwards so undermine wall, reduced access to beach, poor energy absorption, wave reflection and scour destabilises beach

Question 6

What are recurved sea walls?

Answer 6

Sea walls with curved lips to reflect waves back - very expensive and reduce beach access but effective at reducing impacts.

Question 7

What are groynes?

Answer 7

Barriers to prevent LSD and encourage deposition. Usually cheap , encourages deposition so makes wider beaches, easy to build, less exposure to defences and quick to make

Often high maintenance, do not last long, ugly, cause issues downstream, sour and LSD down coast, less sand downcoast, can’t control cross shore sand, less safe

Question 8

What is breakwater?

Answer 8

Solid structures deflect waves and protect areas behind from wave action. Very expensive , high maintenance and increased erosion downcoast

Question 9

What are gabions?

Answer 9

Wire cges filled with stones to reduce energy. Cheap to build however short lifespan and high maintenance costs

Question 10

What are revetments?

Answer 10

Sloping walls running along the coast which dissipate wave energy and reflect waves - cheap.

The overtopping of waves can occur at high tide, eroding them quickly

Question 11

What is rock armour

Answer 11

Large boulders of hard rock which dissipates wave energy, used in exposed sites. They are generally cheap to construct, little maintenance and used with sea walls to reduce scour.

It is more effective in reducing energy, needs to be big and wide, visually ugly, less safe for public.

Question 12

What are splash walls?

Answer 12

Control overlapping and flooding, reduces scale of waves

Needs space and width, high maintenance

Question 13

What are flood banks?

Answer 13

Sheltered locations to control flood banks, set back rom main defence, cheap solution

Used as a primary defence but needs toe protection?

Question 14

What are offshore structures?

Answer 14

These break waves earlier to reduce impact, helps build and maintain beach, reduces exposure, little maintenance

Tends to be big and costly, reduces navigation and safety, increased down drift erosion, hard to construct

Question 15

What is beach nourishment?

Answer 15

Building up the beach, making it bigger and absorb more energy - requires lots of maintenance.

Sand dune conservation is similar as sand dunes provide areas with protection, store sand, dissipates energy whilst also making a good area for wildlife, tourism, etc. These may have high costs and cause erosion downstream

Question 16

What is managed retreat?

Answer 16

Allowing defences to be breached to allow sea to access low lying land beyond. The land sacrificed is often low cost agricultural land to protect settlements inland. New defences may need to be built inland and the work is costly and disruptive

Question 17

What is cliff drainage and regrading?

Answer 17

Draining the face removes water and risk of mass movement - expensive

Regrading - vertical cliffs more gentle due to removal fo material from top, added to bottom. Makes more stable and less prone to mass movement - often expensive, unsightly and disruptive

Question 18

What are planning controls?

Answer 18

Planning permissions in at risk areas refused to prevent development in areas at risk

Question 19

What are barrages and embankments.

Answer 19

Solid dams across estuaries and deltas to prevent seawater reaching land - very expensive. They can create lakes behind them and encourage reclamation of land from the lake.

Temporary barriers may be raised at times of danger. Embankments may also be built to prevent seawater from flooding low lying land - need constant maintenance.

Question 20

What are shoreline management plans?

Answer 20

-Look at entire sediment cell to decide what option to choose. The EA, council and DEFRA work together for cost-benefit analysis for social and economic benefits against cost of protection. The plan aims to coordinate interests and actions for all bodies responsible.

Looks at coastal erosion, managed retreat, tourism pressures, rising sea level, human activity offshore, land use changes, scale - rates and size and time - short/long term

Question 21

What are the 2 acts?

Answer 21

Coast protection act 1949 - prevents erosion and encroachment by sea

Drainage Act - protects land against flooding by sea using sea defence

Question 22

What is the importance of sediment cells?

Answer 22

Receive inputs of sediment from cliffs, rivers and other cells due to LSD and currents which may remain within the cell and not transferred anymore. Natural barriers may be created between cells such as canyons to keep sediment in. Coastal defences may disrupt the flow of sediment, causing erosion downdraft

Question 23

What are the 4 DEFRA strategies?

Answer 23

No active interaction - no investment in defending against flooding or erosion

Hold the line - build or maintain existing defences to keep position of the shoreline

Advance the line - new defences built on seaward side in front of old defences

Managed retreat - allowing shoreline to move naturally but directed into certain low cost areas.

Question 24

How do defences interfere with equilibrium?

Answer 24

1. Protection put in place
2. Alters sediment supply rates, loss of adjacent beaches, increased erosion of foreshore and cliff line. Also alters transport rates leading to beach instability as sand is lost due to increased wave activity
3. Silt monitoring occurs to monitor the levels pre and post construction
4. Loss of sediment supply may be countered by redesigning works so more allowed to bypass, or recirculates or re nourished. Modifications to the design made to reduce wave activity and reflection or increase dissipation rates to retain equilibrium