14 November 1997

Dear Mr Rogerson

Dredging at Helwick Bank: Government View
Thank you for consulting the RSPB on this matter. We have read both the HR Wallingford report and the Environmental Statement.
Our particular interest in this issue is the nature conservation of the Burry Inlet/Carmarthen Bay proposed Special Area of Conservation (under the Directive on the Conservation of Habitats and of Wild Fauna and Flora, 92/43/EEC). Carmarthen Bay is also being considered for designation under the Directive on the Conservation of Wild Birds (79/409/EEC) as a Special Protection Area. It is a Site of Special Scientific Interest, designated under the Wildlife and Countryside Act 1981. Of particular significance is the UK's largest flock of internationally important wintering common scoter (a sea duck which feeds on molluscs on the intertidal and sub-littoral habitats within Carmarthen Bay).
We are also concerned to maintain the intertidal and coastal features which are of importance for wildlife, especially on the beaches at the west of Gower and the sand-dune habitats especially at Whiteford and Oxwich National Nature Reserve.
We are pleased that the HR report is clear and well structured in view of.the complexity of the issues involved. There are, however, a number of issues that we believe remain inadequately resolved at the present time. These are:
1 the relationship between dredging and the transport of fine (silt) sediments into or from Carmarthen Bay
2 the longer term implications of climate change, including sea-level rise and predicted increase in storminess
3 the trend in the volume of Helwick Bank above -5.OmOD
4 sediment transport to and from Helwick Bank
5 guidance..on alternative sand.-sau-rces in the Bristol Channel which might be used.
We enlarge,on these aspects below:
1 The relationship between dredging and fine silt transportation into Carmarthen Bay
The report identifies (4.3.7) that this is inadequately understood at present'. The scale of'this; which could potentially be influenced by lowering of the Bank crest; is unknown. As it could have'sign'ificant implications for the food chain.on which the internationally important bird populations feed, we believe that some further work should be undertaken to establish the scale of the potential problem.
2 Implication of climate change for sea-level rise and increased storminess
The report clearly raises the issues of major changes in_the loss of.or re-distribution of.sediments.during storm events (eg page 25). We believe that the additional pressures on the system due to the range of predicted and observed changes due to climate change should have been considered further. This would include looking at 'worse' or at least 'lower quartile' scenarios. The modelling appears to have been run under 'normal' conditions only.
3 Trends in the volume of Helwick Bank above -S.OmOD We are not convinced by the summary in 5.1.(a).. We appreciate that the December 1996.data were added at later.stages to.the report, but..it clearly shows that changes to the volume of Helwick Bank can occur under certain climatic conditions (this emphasises our comments under 2 above). If the December 1996 data were included in the assessment at face value, there would have been strong evidence for a continuing andworrying decrease in-.the upper volume of the bank.
This is precisely the opposit.e conclusion that.is drawn from earlier data. The future of the upper bank is probably critical for.the long-term beach protection and fine sediment transport patterns.
4 Sediment transport to and from Helwick Bank
We were unable to identify from the report the key mechanisms that were operating for the movement of sand off and the replenishment of sand onto Helwick Bank. Are the storm events which mobilise sediment or the tidal streams resulting in nett loss of sediment and so feeding the sand waves a kilometre or so south of the Bank? If there is no nett loss, then sediment, presumably from further east, must be feeding the bank. Is th~ sediment source large enough to do this? for how long? Could some of the changes seen on Gower beaches, such as at Oxwich, be partly a result of continuous feeding of Helwick Bank? We do not have answers but there do appear to be issues no fully resolved by this study.
5 Guidance on alternative sources of sand
Clearly,there are potentiai..sources of sand..which lie further out.in deeper water and, because they are moving westwards out of the Bristol.Channel, could potentially be exploited without resulting in the concern for inshore habitats that arise from the dredging of Helwick Bank. We realise that the wider study on Bristol Channel Sediment transport is examining these sediments, however, we would hope that detailed work to inform the Government View of Helwick Bank dredging could also examine alternative marine sources. Even if current dredgers used are unable to exploit these sources, the technology exists to use them and we suggest will be required soon. Thus examining options now should be included in the View procedure.
There are therefore, several aspects which, in our view, need further examination. However, we accept that major changes in the area have not been unambiguously associated with the pre.s.ent dredging. We would prefer that the precautionary principle were used in this instance and dred.ging..stopped for a period to assess sediment transport in the area. If; dredging were to be allowed here; then we agree with the recommendations in 7.2. We would however, also wish to see some work done on the transport of fine sediment, especially into Carmarthen Bay.

I hope that these comments are of help. If you require any further clarification please come back to me.

Yours sincerely
Dr Tony Prater (Deputy Wales Officer)

BIRDS MAIN MENU