SUMMARY OF THE PRESENT SITUATION.

Natural Defences.

The natural coastal defences, i.e. the beaches, dunes and immediate coastal hinterland, endure some of the most hostile wind and wave conditions in the world. Since sea levels started to rise at the end of the last Ice Age there is no doubt that coastal edge retreat has been occurring over much of the beach areas of the Western Isles. It is a rather more difficult task to determine whether there is any increase in the rate of coastal erosion in recent years. Trends in coastal erosion can be determined by comparison of modern with historical aerial photographs or ordnance survey maps. Insufficient aerial photographs exist which would allow comparison, and there are few such historical maps of the Western Isles to allow intercomparison. Indications of coastline retreat may also be found in historical accounts. For instance, the translation of Baleshare means east island, suggesting that at one time there was also a west island with no obvious geological evidence now of its existence. Similarly, Statistical Accounts report parts of Kirkibost island being literally blown away, with the sea occupying land which had once grown substantial barley crops. Accounts from the 18th and 19th century indicate problems of the instability of the coastline; "The depredations of the sea and storms are alarming, ... many places have lost a quarter of a mile in breadth.". In more recent times local residents, for instance at Arnol on Lewis, can remember when land extended out to particular rock outcrops, often over 30m seaward of the present day coastal edge.

Over much of the Western Isles, the major concern at present seems to be about beach erosion rather than substantial loss of agricultural land. In comparison with historical accounts, therefore, it would appear logical that present day coastal retreat is certainly not occurring at a greater rate than it has done in the past. Instead it would appear that there has been a period of stability and low beach retreat rates over the last 100 years or so.

The occurrence of a number of particularly severe storms in the last few years, eg the `Braer storm' has caused an increase in the short term erosion rate, causing a perception in the public eye that coastal erosion is on the increase. Erosion of the sand beach and dune face is often less serious than shingle beach recession. Long period Atlantic swell waves will restore sand, which has been transported offshore under storm conditions, back onto the beach with wind action transporting sand back into the dunes. Although many of the dune systems may appear to be eroding, it is often the case that erosion has occurred during a storm some months (or even years) before, with the dune system slowly rebuilding.

At present it is too early to assess whether the increase in coastal erosion due to recent storms is part of a long term trend. The lack of information on sea level rise on the western coastline makes it extremely difficult to judge whether this is a significant factor. There is also evidence that the wave climate in the North Atlantic is becoming more severe, which would have a significant effect on the rate of beach retreat.

Dune erosion due to wind action is another natural process. It is recommended that where no other influences other than natural ones occur, the area should be left to develop naturally. Where such erosion is affecting infrastructure or housing due to aeolian transport, some remedial work may be required to limit the effects.

To monitor beach rates of erosion, reliable information on the state of the coastal edge is required over a period of time. No formal periodic monitoring programme is currently being conducted.

Coastal Defences.

Most of the existing coastal protection works are performing adequately with limited effect on adjacent beach systems. The use of rock revetments tends to be the most suitable option to halt erosion where infrastructure may be affected.

Table 1 lists the main coastal protection works in the Western Isles.

Table 1 Summary of the expected life of existing coastal defences

Management Unit	Location	Defence type	Present state
1	Holm Braigh na h-Aoidh Braigh na h-Aoidh Braigh na h-Aoidh Suardail	Rock revetment Rock wall Sea wall Groynes Gabions	good fair good fair fair
2	Port nan Giuran	Masonry walls Concrete apron and upstand	fair good
3	Aiginis Branahuie Branahuie	Rock wall Sea wall Groynes	fair good poor
4	Stornoway Airport Tong Tong	Rock revetment Rock revetment Gabions	good good fair
5	Traigh Chuil	Masonry wall	fair
6	Gress Lodge	Gabions	fair
14	Dalmore	Timber breastwork	good
15	Kneep	Rock wall	good
23	Northton	Rock wall	fair
27	Hougharry	Rock revetment	good
31	Balivanich	Rock revetment	good
33	Stinky Bay	Rock revetment	good
34	Balgarva	Rock revetment	good
35	RA Ranges	Gabion mattress	good
38	Pollachar East/West Kilbride	Rock wall Rock revetments	fair good
39	Rhuban/Balla	Rock wall	fair

Criteria

poor: Indicates that the structure is now so deteriorated it serves little purpose.

fair: Possibility of being damaged during a severe storm event.

good: Functioning adequately but routine repairs will be required to retain the required level of protection.

Table 2 Summary of recommendations of required future coastal protection work.

Management Unit	Location	Timescale	Suggested possible protection
2	Port nan Giuran	long	Rock revetment
3	Aiginis	short	Rock protection at toe of eroding cliffs
3	Branahuie (East)	long	Rock rip rap at toe of sea wall or recycling of shingle material from western end.
9	Port of Ness	long	Rock toe protection or spur breakwater
13	Bragar (Cemetery)	long	Rock revetment protection along access road
20	Luskentyre (Cottage and house)	long	Rock upstand and revetment to limit effects of waves
31	Balivanich (An Ceothan)	short	Rock toe protection at eroding till cliff
31	Balivanich (west)	short	Continue rock revetment with upstand along entire frontage.
35	Ardivachar	long	Rock revetment if erosion becomes a threat to the cemetery or fire station
38	East/West Kilbride	short	Three sections of rock revetment with upstands required similar to existing.

Notes:

1. A short timescale indicates that protection is likely to be required within the next five years.

2. A long timescale indicates that work will be required in the future but as yet is not urgent.

3. These are only initial suggestions and a much more detailed assessment of the various coast protection options will be required. An example of comparing various alternatives is provided in Section 6.

Tourism and recreation.

The effects of tourism, and the recreational uses, of the coastline of the Western Isles are still relatively localised and mainly concentrated on a few beaches. The provision of facilities should be carried out with the day visitor in mind, eg accommodating car parking. The exception to this is at the caravan park at Traigh na Berie, where a formal plan for the management of the caravan park is required.

The degree of tourism and recreational use of the beaches in the Western Isles is summarised in Table 3.

Table 3 Summary of tourist and recreational beaches in the Western Isles

High Usage	Medium Usage	Low Usage
Branahuie Traigh Mhor Traigh Geiraha Traigh na Berie Uig Culla	Coll Sands Traigh Ghriais Port of Ness Dalbeg Dalmore Traigh na Clibhe Hushinish Traigh Iar (Harris) Traigh Iar (North Uist) An Tom Liniclate Halaman Bay Vatersay	Eoropie Stinky Bay to Borve All beaches in South Uist Balla Eoligarry beaches

Criteria

high: where tourism facilities have been provided, eg car parking.

medium: few facilities but beaches visited by tourists

low: beaches generally only used by local inhabitants

Table 4 Summary of recommendations for beaches used for recreational purposes

Management Unit	Beach	Recommendations
15	Traigh na Berie	· Prohibiting caravans from dune areas. · Access tracks over machair to facilitate caravan parking.
16	Traigh Geiraha	· Influence pedestrian access (eg boardwalks) to beach from car park. · Restrict human and animal access to eroded machair (fencing).
16	Traigh Mhor	· Influence pedestrian access (eg boardwalks) to beach from car park.
27	Traigh Iar (North Uist)	· Redirect pedestrian access to beach to northern end of dunes.
31	An Tom	· Provision of pedestrian access to beach from road.
32	Culla	· Restrict pedestrian access to beach through dunes. · Encourage pedestrian access at car park.
21	Traigh Iar (Harris)	· Stabilise pedestrian access to beach from road.
4	Coll sands	· Prevent caravans and car parking on immediate machair edge.
5	Traigh Ghriais	· Influence pedestrian access (eg boardwalks) to beach at location of cemetery.
17	Uig	· Provision of car parking at gate to machair. · Pedestrian access (eg boardwalks) to beach from car park.
14 14 19 3 34	Dalbeg Dalmore Hushinish Branahuie Liniclate	· Redirect pedestrian access

Agriculture & livestock

The coastal hinterland, and in particular the machair, has a long history of agricultural use. At present, and over a number of decades, the intensity of agricultural use of the machair has been decreasing. The emphasis has shifted from the rotational cropping of the common township land to more intensive livestock grazing of the machair. The number of working crofts has diminished and it is really only in the Uists that traditional agricultural practices are still conducted. Due to the decrease in the intensity of machair cultivation, cultivation practices are now not a significant factor in initiating erosion.

The increase in the intensity of livestock grazing, however, has created additional pressures on both the coastal edge and hinterland surfaces. Overgrazing and trampling can lead to instability of vegetated surfaces which are then further eroded by wind action.. Large populations of rabbits also have an effect. The most serious trampling effects occur on the seaward dune or machair face again leading to an increase in the effects of wind erosion of the dune or machair face. Along much of the coastline of the Western Isles it is recommended that livestock be restricted from the frontal dune systems and areas of instability such as blowout holes. Table 5 lists the frontages where it is recommended that restrictions on livestock access be implemented and areas where high rabbit populations are having a significant effect on the machair

Table 5 Summary of recommended livestock restriction areas

Management Unit	Location	Effect of Livestock access	Recommendations	Rabbit effects
3	Branahuie			low
8	Traigh Mhor	Sheep trampling on dunes	Monitor	mod
8	Traigh Geiraha	Sheep overgrazing on machair surface	Restrict access	high
10	Swainbost Sands	Sheep tracking on machair	Monitor
12	Barvas	Sheep overgrazing and tracking on dunes	Reduce intensity	high
14	Dalmore	Sheep tracking and overgrazing on steep machair	Restrict access
16	Traigh na Clibhe	Sheep tracking and overgrazing on steep machair	Reduce intensity	high
18	Mangersta	Sheep tracking on steep machair	Monitor
19	Hushinish	Sheep overgrazing on machair	Monitor	mod
20	Luskentyre		Restrict access
21	Traigh Iar	Sheep grazing on dunes	Monitor
22	Traigh Scarasta			mod
23	Traigh na Cleavag	Sheep grazing on steep machair	Reduce intensity	mod
25	Machair Robach	Sheep tracking on dunes	Restrict access	high
26	Machair Leathann	Sheep and cattle grazing and trampling on machair and dunes	Restrict access and reduce intensity	high
27	Traigh Stir	Cattle tracking through dunes	Restrict access	high
27	Traigh nam Faoghailean	Sheep tracking on dunes	Monitor	high
28	Traigh Iar	Cattle/sheep tracking on dunes	Restrict access from dunes and blowouts	high
28	Port Scolpaig	Cattle/sheep tracking on dunes and machair	Restrict access and lower intensity	high
36	Ormiclate	Sheep grazing on machair	Reduce intensity	high
40	Traigh Scurrival	Cattle/sheep trampling in dunes	Restrict access
42	Traigh Eais		Restrict access
43	Allasdale	Cattle/sheep tracking through dunes	Restrict access
44	Vatersay (west)	Cattle/sheep tracking in dunes	Restrict access

Sand and shingle extraction.

At present there are no areas where sand quarrying for agricultural purposes is on such a scale that it is having a serious effect on the overall stability of the system. Localised effects, mainly due to wind action, occur on most quarried areas. However, unless the deflated area shows signs of expanding, the quarried areas should be left to stabilise naturally. Generally, once all human activity has been removed, and provided livestock and rabbits are not a serious problem, many old quarry sites have stabilised and revegetated. The most worrying aspect of aggregate quarrying is the removal of shingle from the ridges protecting the machair edge along parts of the South Uist. The importance of these shingle ridges in protecting the hinterland can not be stressed enough.

Based on the site survey a number of guidelines for the quarrying of sand and shingle can be defined:

1. Quarrying should not occur on any part of the frontal dune ridge and be restricted to the landward side of a dune or sand hillock.

2. Small amounts of sand extraction may be allowed from the beach provided the beach is in a reasonably healthy state.

3. It is recommended that where large volumes of sand are being extracted, other sources be investigated such as extraction from sand banks on the large intertidal areas found within the Uists.

4. On no account should shingle be extracted from the upper beach.

5. Vehicular access to the beach should be concentrated where the machair is lowest. Tracks should be restricted from occurring through frontal dune systems.

6. Monitoring of existing, and approval of new, quarry areas should be conducted, possibly with assistance from SNH.